aMpwfhl RADIOLOGICAL 
DEFENSE 
A Series of Indoctrination Lectures on 
Atomic Explosion, with Medical Aspects 
COMPILED BY 
The Armed Forces Special Weapons Project 
Vol. Ill 
Not to be reproduced without permission of 
The Armed Forces Special Weapons Project FOREWORD 
This volume is the third in a series of Radiological Defense Manuals 
issued by the Armed Forces Special Weapons Project for training in the 
National Military Establishment. Volume III is a compilation of lectures 
presented in Washington, D. C., during 1947, 1948 and 1949 in a joint course 
on “Medical Aspects of Nuclear Energy” presented by the Armed Forces 
Special Weapons Project. This joint course is conducted for indoctrination 
of Medical Officers of the Armed Services with participation open to repre- 
sentatives of all interested government agencies. The lectures delivered 
in the course and printed herein represent the experience and opinion of 
their authors. As further technical information becomes available there 
may be changes of view which will be reflected in later presentations. Never- 
theless, these lectures have “weathered” well and collectively they comprise 
an important body of latest thought on the subject. 
This volume presents information which should assist defense per- 
sonnel in preparing themselves for the complex casualty problems which 
must be faced during atomic warfare. It does not purport to be definitive or 
final. Much more research must be accomplished before satisfactory mass 
handling procedures for the casualties of atomic warfare can be realized. 
Much of this lecture material is believed to be of interest to the line officer 
and layman as well as to medical personnel. It is hoped that this volume 
will extend such information as is available not only to personnel of the 
Armed Services but throughout the entire civil defense structure. 
% s. 
K. D. NICHOLS 
Major General, USA 
Chief, Armed Forces Special Weapons Project 
III CONTENTS 
Title of lecture Author Page 
Elements of Nuclear Energy R. E. Lapp, Ph.D 1 
Atomic Bomb and the Resultant Phenomena Herbert Scoville, Jr., Ph.D., AFSWP 16 
Essentials of Instrumentation Howard L. Andrews, Ph.D., USPHS 24 
Medical Effects of Atomic Explosion Col. James P. Cooney, MC, USA 30 
Biological Effects of Radiation Lt. Col. K. H. Houghton, USAF (MC) 39 
Fundamentals of Radiation Pathology Col. Elbert DeCoursey, MC, USA 47 
Pathological Anatomy of Radiation Effects of 
Atomic Emplosion Col. Elbert DeCoursey, MC, USA 52 
Diagnosis of Ionizing Radiation Injury by 
Physical Examination and Clinical Labora- 
tory Procedures LCDR. Eugene P. Cronkite, (MC) USN 57 
Therapy of Radiation Illness CAPT. R. H. Draeger, (MC) USN 65 
Treatment of Acute Radiation Illness Maj. Albert J. Bauer, MC, USA 69 
Therapy and Handling of Mechanical and Herman E. Pearse, M.D. and 
Thermal Injury from the Atom Bomb .... J. Thomas Payne, M.D 71 
Internal Hazards of Fission Products and 
Plutonium 1st Lt. Robert J. Soberman, MC, USA 79 
Public Health Aspects of Atomic Energy . . Medical Director Edwin G. Williams, USPHS 83 
Radioactive Decontamination Problems CDR. E. J. Hoffman, USN 87 
Protection Against Atomic Bombs Maj. William W. Stone, CmlC, USA 91 
Radiological Defense Capt. George M. Lyon, (MC) USNR 
(Inactive) 97 
Command Aspects of Radiological Defense . . CAPT. Frank I. Winant, Jr., USN 102 
Psychological Factors in Atomic Warfare . . . Col. James P. Cooney, MC, USA 110 
The Production, Procurement and Handling 
of Radioisotopes Maj. Maxwell Dauer, MSC, USA 114 
Tracer Techniques Capt. John R. Hogness, MC, USA 122 
Radioactive Isotopes in Clinical Medicine .... Capt. Edgar Leifer, MC, USA 127 
Bibliography 133 
V RADIOLOGICAL DEFENSE 
THE ELEMENTS OF NUCLEAR ENERGY 
RADIOACTIVITY 
Ralph E. Lapp, Ph.D. 
"Fundamentai Particles" 
In their search for an understanding of the 
composition of matter, physicists have had to 
continually re-define their concepts of the funda- 
mental units of which all matter is constituted. 
As the quest for the ultimate constituents of 
matter progressed, it became increasingly 
apparent that more and more “fundamental 
particles” were required in order to build up 
a consistent picture of the atom and its nucleus. 
At first, it seemed that two particles, namely, 
the electron and the proton, would suffice to 
explain the constitution of the elements. Then 
two more particles — the neutron and the 
positron — appeared on the horizon. There- 
after, in quick succession, two more particles — 
positively and negatively charged mesons or 
mesotrons (the names are used interchange- 
ably) were discovered and in the past 2 years, 
three new mesons have also come to light, 
bringing the total to five kinds of mesons. All 
in all, this adds up to a total of nine funda- 
mental particles. 
Furthermore, there are in addition to these 
particles, two other fundamental entities which 
do not conform to the definition of a particle, but 
behave more like waves. These are the photon 
and the neutrino. As we shall see later, there is 
no very distinct line of demarcation between 
waves and particle; sometimes a particle be- 
haves as though it were a wave and at other 
times a photon or a neutrino may exhibit what 
are manifestly properties of a particle. 
We shall endeavor to give you some concept 
of the manner in which this variety of particles 
is involved in the building-up of atoms and 
nuclei, so that you may more profoundly appre- 
ciate the phenomena associated with radioac- 
tivity and fission. 
Waves and Particles 
Normally one thinks of a particle such as a 
bullet as being a solid object which rigorously 
obeys the laws of Newtonian mechanics. One 
would be surprised if it were pointed out that a 
bullet, traveling with high speed, has asso- 
ciated with it a “wave length” that we charac- 
teristically use to describe a wave phenomenon 
such as X-radiation or light waves. However, 
the French physicist, de Broglie, deduced that 
any particle of mass m and velocity v should 
have associated with it an equivalent wave- 
length A given by the relation: 
A=— (1) 
m v 
where h is Planck’s constant and is numerically 
equal to 6.6 X 10 27 erg sec. 
Now Eq. (1) shows that a small bullet travel- 
ing with a high velocity would have an associ- 
ated de Broglie wavelength of about 1(H2 cm. 
Such a wave length is of course utterly beyond 
our present means of measurement, but experi- 
ence with other phenomena leaves no doubt that 
the bullet actually possesses this associated 
wavelength. 
When we apply our concept of a de Broglie 
wave to a particle much smaller than a bullet, 
say, to an electron, then because of the small 
mass and high velocity of the electron the 
equivalent wavelength is of the order of 10~8 
cm (or 1 Angstrom unit) and is easily measur- 
able using the techniques of modern physics. 
You have undoubtedly heard of electron dif- 
fraction and can now understand that in this 
instance, electrons give validity to the principle 
announced by de Broglie. 
It is at first often perplexing to a student that 
under one set of circumstances a particle should 
behave precisely as a particle, and under other 
conditions exhibit wave properties. In reality, 
any experiment or measurement involves some 
kind of interaction between the thing being 
observed and the means by which intelligence 
is transmitted to the observer. The latter may 
consist of light rays entering a microscope and 
striking the observer’s eye or they may be 
X-rays which are recorded by a photographic 
film, or they may even be electrons which are 
projected in an electron microscope. In any 
event the means by which intelligence is con- 
1 RADIOLOGICAL DEFENSE 
veyed, i.e. the light rays, X-rays, or electrons, 
must interact with the thing being observed and 
in the process of this interaction it may exhibit 
either wave or particle properties depending 
upon the existing conditions. 
The Electron 
We shall now proceed to describe the various 
particles and physical entities introduced in 
such a rapid-fire manner at the beginning of 
this lecture in the section titled “Fundamental 
Particles.” From the standpoint of history, the 
first fundamental particle to be identified and 
exhaustively investigated was the electron. You 
are all familiar with the word “electron” but 
perhaps its properties are not so well known to 
you. In vacuum tubes, such as those used in any 
radio, electrons are produced by a hot filament 
in the tube elements. These electrons are 
evaporated off the glowing filament by the high 
temperature which is created in the filament. 
Careful measurements have shown that all of 
these electrons have the same physical proper- 
ties. Furthermore, electrons produced from a 
glowing filament are exactly the same as elec- 
trons produced by other means, as for example, 
by release from a photo-electric cell. 
The American scientist, Millikan, first showed 
that an electron is always characterized by a 
discrete electrical charge of 4.80 XKH° electro- 
static units. It is significant that this electronic 
charge, written as -e is the smallest observable 
bit of electricity. That it is the unit of electric 
charge is shown by the fact that other particles 
such as the proton, positron, and meson all have 
numerically the same value for their charge. 
The electron is an extremely light particle, 
weighing only 9 X 1(L28 grams. All electrons at 
rest are found to have exactly the same mass. 
The vast majority of electrons are not found 
“free” in nature but are more or less tightly 
bound within a unit of matter known as an 
atom. In certain metals we do find very loosely 
bound electrons; for example, in a conductor 
such as copper there are many free electrons 
and when a potential difference (i.e. a voltage) 
is applied across a section of a copper wire a 
current of electricity is observed to flow. This 
electric current is simply the mass migration 
of the free electrons within the copper. 
The Atom 
Certainly all of you are familiar with the con- 
cept of a chemical element such as gold, tin or 
hydrogen. An atom is simply the smallest part 
of a chemical element which enters into a chemi- 
cal reaction. In this lecture we shall be con- 
cerned with events which take place within the 
atom and it is therefore necessary to talk about 
the structure and constituents of the atom. For 
an understanding of atomic structure and for a 
visualization of a model of an atom, you may 
find ARMY TALK No. 157, “A NEW WORLD 
WITHIN THE ATOM” very helpful. 
The concept of the atom as a structure which 
is mostly “space” is one which can be appreci- 
ated best by realizing the magnitude of atomic 
and nuclear dimensions. 1 gram of hydrogen 
contains 6 X 1023 atoms! Thus even if this 
1 gram of gas is contained in a very large vessel 
the number of atoms per cubic centimeter (1 
inch equals 2.5 centimeters) is still extremely 
high. Each hydrogen atom has a diameter of 
about 1(H cms (centimeters) which is less than 
one hundred millionth of an inch. 
Doctor Lapp is both a professional physicist 
and author. His most recent book is MUST WE 
HIDE?, a non-technical evaluation of atomic haz- 
ards. In the technical field he has collaborated 
with Doctor H. L. Andrews in writing NUCLEAR 
RADIATION PHYSICS. Upon completing his 
graduate studies at the University of Chicago 
he joined the Manhattan Project; there he worked 
for the war period and became Assistant Director 
of the Metallurgical Laboratory. He then accepted 
a position with the War Department General 
Staff as scientific advisor on atomic energy. When 
the Research and Development Board was formed 
Doctor Lapp became Executive Director of its 
Committee on Atomic Energy. Thereafter, he 
acted as Head of the Nuclear Physics Branch 
of the Office of Naval Research. Doctor Lapp 
has been interested in problems of radiological 
defense since his work at Bikini. He is currently 
engaged in collaborating in the writing of two 
new books—NUCLEAR RADIATION BIOLOGY 
and A NUCLEAR REFERENCE MANUAL. 
2 RADIOLOGICAL DEFENSE 
We now know that any atom is composed of 
two parts: 
(a) An inner part called the nucleus 
(b) An outer part called the electron shell 
In order to attack systematically the problem 
of atomic and nuclear structure, we shall ini- 
tially confine our discussion to the simplest pos- 
sible atom. Now the lightest of all the elements 
is hydrogen and we shall first consider the ordi- 
nary hydrogen atom which is known as protium. 
As some of you may be aware, there is a heavy 
form of hydrogen called deuterium which we 
shall discuss later. 
The Proton 
We conceive of the simplest hydrogen (pro- 
tium) atom as consisting of a central tiny core 
or nucleus about which circles a single planetary 
electron. This core or nucleus of the simplest 
hydrogen atom is called the proton. A proton is 
simply a protium nucleus and is formed by 
stripping off an electron from the lightest 
hydrogen atom. It should be emphasized that 
the proton occupies negligible volume inside the 
hydrogen atom even though it constitutes almost 
the entire weight of the atom. Its weight is 
1840 times greater than that of the electron. 
The electric charge carried by a proton is 
+ 4.80 X 10~10 esu (electrostatic units) or + e, 
where e denotes the electronic charge. If we 
add up the charge in a protium atom, we see 
that the charge on the proton is counter- 
balanced by the charge on the single planetary 
electrons, so that the atom as a whole is elec- 
trically neutral. 
Protons are not normally found free in nature 
for there is usually such an abundance of elec- 
trons everywhere that a free proton would 
immediately attract an electron and become a 
neutral hydrogen atom. If, however, we strip 
off the electron from a hydrogen atom and 
accelerate it in an evacuated vessel we can 
momentarily obtain “free protons”; this is 
also true in certain regions of intergalactic 
space. 
Electron Shells 
Electrons are the only particles which are 
found within the atom outside of the nucleus 
and since these electrons are negligibly small in 
size as compared to the atom, it is clear that 
the greatest part of the atom is a void. Why 
then should the atom possess such apparent 
shape or rigidity which we know from experi- 
ence it must have? The reason for this lies in the 
electrical nature of the nucleus as well as that 
of the electrons which speed about it in never 
ending orbital paths. In every normal atom, the 
nucleus carries a positive charge of electricity 
which is exactly the same as the total negative 
charge of all the electrons within the atom. This 
is merely another way of saying that in any 
neutral atom, the number of protons within 
the nucleus is exactly equal to the number of 
orbital electrons. 
Between the protons inside the nucleus and 
the electrons outside of it, there exists an elec- 
trostatic force which pulls the particles together. 
However this force of attraction is just bal- 
anced by the centrifugal force due to the whirl- 
ing motion of the electrons around the nucleus. 
Thus the electrons perpetually gyrate around 
the nucleus in orbital paths through the fric- 
tionless void of the atom. 
Starting with the simplest atom (hydrogen 
has atomic number 1) the number of orbital 
electrons is one. The atomic number of any atom 
is equal to the number of protons in its nucleus. 
For heavier elements, more and more electrons 
are found in the orbits. Helium with Z = 2 
(Z is the atomic number) has two electrons; 
iron with Z = 26 has 26 orbital electrons and 
uranium has 92 such electrons. These electrons 
arrange themselves in certain very definite 
ways about the nucleus and obey rigorous 
atomic rules. Thus they build themselves up 
about the atomic core in systematic shells which 
are peculiar in that each shell can hold just 
so many electrons. When one shell is filled, the 
electrons start another shell which is farther 
away from the nucleus. 
These electrons which are in the outermost 
shell are called the valence electrons. They 
determine the chemical properties of the atom. 
Since these outer electrons are farthest from the 
nucleus, it is reasonable to suppose that these 
electrons will not be bound so tightly to the 
atom. The outer electrons are in a sense shielded 
3 RADIOLOGICAL DEFENSE 
from the nuclear charge by the inner electron 
shells so they cannot “see” the nucleus. On the 
other hand, these electrons in the innermost 
shell (the innermost shell is called the K shell) 
are close to the nucleus and are thus more 
tightly bound to it. 
Ionization of an Atom — Ions 
If by some means we could pull one of the 
outermost electrons away from an atom, the 
resulting atom would no longer be electrically 
neutral but would have a net charge of +1. The 
process of removing an electron from an outer 
shell is called ionization and the resulting atom 
is called an ion. An atom can be ionized by shoot- 
ing high-speed electrons at it. These minute pro- 
jectiles may collide with some of the outer elec- 
trons and knock them out of their orbits away 
from the atom. 
By bombarding an atom with very high 
energy electrons, it may happen that an electron 
in a K shell will be knocked out creating a va- 
cancy in it and one of the outer electrons jumps 
down into the K shell to fill it up. In jumping 
down (an electronic transition) energy is lib- 
erated from the atom in the form of an X-ray. 
In general, the ability of a particle to cause 
ionization depends upon the nature of the par- 
ticle (i.e. its charge and mass), its velocity, and 
the state of the medium which it traverses. An 
electron normally produces about 60 ions per 
centimeter of air whereas a proton and alpha 
particle are much more potent, the latter pro- 
ducing tens of thousands of ions per cm of air. 
In a liquid or solid, more atoms are present 
per centimeter of the particles’ path and for this 
reason more ions per cm are created. 
From the viewpoint of the biologist or medical 
man, the phenomena of ionization are of the 
greatest importance since it is the ionizing 
event that serves to initiate the complex series 
of reactions that characterize radiation damage 
to tissue. It must be remembered that for any 
penetrating radiation to cause primary damage 
to tissue it must produce ionization within the 
tissue. All charged particles such as protons 
and electrons readily produce ionization in 
tissue but X-rays (and gamma rays, for these 
are identical in nature) are sparsely ionizing 
and only a relatively few such rays which 
traverse a layer of tissue will produce ioniza- 
tion ; the rest pass harmlessly through the 
tissue. 
X-rays 
The emission of an X-ray from an atom 
always occurs when an electron from an outer 
shell jumps down to fill a vacancy in a K shell. 
Because the electrons in different atoms (of 
different elements) are bound to their respective 
nuclei with different energy, the energy of the 
X-ray given off will depend upon the element 
which is producing them. You have undoubt- 
edly heard of X-ray tubes which have different 
elements for targets and know that the radia- 
tion from a tungsten target is much “harder” 
than that from a copper target. We have men- 
tioned “hard” radiation but for any real dis- 
cussion we must specify the radiation more 
exactly. To do this we can either refer to the 
energy of the X-ray or to its wavelength. 
Energy is usually measured in terms of electron 
volts (at least for X-rays). An electron volt is 
that energy which is acquired by an electron in 
being accelerated across a potential of 1 volt. 
In X-ray tubes the electrons emitted by the fila- 
ment are accelerated by perhaps 100 kilovolts 
(100,000 volts) and we therefore say that these 
electrons acquire 100,000 ev (electron volts) 
of energy. We abbreviate 100,000 ev either as 
0.1 Mev (million electron volts) or as 100 Kev. 
To find the shortest wavelength of X-radiation 
emitted by an X-ray tube operated at V volts, 
we use the relation; 
. 12,345 . . , 
A-min = —y~— in Angstrom units (2) 
Using Eq, (2) we see that an X-ray tube oper- 
ated at an effective voltage of 50,000 volts emits 
radiation as hard as 0.25 A (A is the abbrevia- 
tion for the Angstrom unit). 
It is, perhaps, more difficult for the student 
to grasp the physical significance of an X-ray 
since it does not possess the apparent simplicity 
of a particle. Physicists are used to speaking of 
a quantum of X-radiation or of a photon; by this 
4 RADIOLOGICAL DEFENSE 
they mean a packet of electromagnetic energy 
which has an energy that is the product of 
Planck’s constant (h) and the velocity of light 
(c) all divided by the wave length of the radi- 
ation. Thus: 
sidered and the nature of the absorbing ma- 
terial. A given X-ray quantum may traverse a 
considerable quantity of matter before it inter- 
acts with an atom and gives up its energy. Thus, 
there is no definite distance or range that an 
X-ray of a given energy travels before it is 
absorbed. There is, however, a quantity, known 
as the half-thickness that can be used to de- 
scribe the gross absorption of X-rays in matter. 
The half-thickness (XM) is that thickness of 
material which is just sufficient to reduce the 
intensity of an X-ray beam by a factor of two. 
For example, the half-thickness of lead for 1.0 
Mev X-rays is 0.87 cm. This means that 0.87 cm 
of Pb will absorb 50 percent of the 1.0 Mev 
X-rays incident upon it; similarly 1.74 cm of 
Pb will reduce the intensity of the same X-ray 
beam by a factor of 4. Doubling the thickness 
of material produces 4 times as effective a shield 
for the same energy X-radiation. 
Natural Radioactivity 
About 50 years ago physicists found that cer- 
tain elements such as uranium and radium give 
off penetrating radiation. The radiation emitted 
by these radioactive elements was not immedi- 
ately separated into its component parts and 
identified, but today we know that the naturally 
occurring radioactive elements emit three kinds 
of radiation: 
1. Alpha particles 
2. Beta particles (high-speed negative elec- 
trons) 
3. Gamma rays 
The alpha and beta particles are discussed in 
more detail in subsequent sections. All the 
natural radioelements can be grouped into three 
major series of elements, namely the uranium, 
the thorium and the actinium series. 
Because of its great penetrating power, the 
gamma radiation was the object of much inves- 
tigation by research workers. We now know that 
gamma rays are photons or quanta having ex- 
actly the same properties as X-rays. Except 
that the two arise from a different site within 
the atom, they are identical in their nature. Thus 
gamma radiation is absorbed by the same mech- 
anisms as hold for X-rays. Actually gamma 
E = — (3) 
If we thus define the wave length of any X-ray, 
we also state its energy as given in Eq. (3). 
Absorption of X-rays 
X-rays are, by themselves, not ionizing. They 
can produce ionization only after they interact 
with matter to produce a high speed electron 
by one of the following processes: 
1. Photoelectric Effect in which case the 
X-ray interacts with an atomic electron 
and ejects it from its parent atom. The 
photoelectron thus ejected carries off the 
energy of the incident photon and pro- 
duces ionization characteristic of any 
electron of that energy. In the process 
the incident photon is completely ab- 
sorbed and disappears. 
2. Compton Effect wherein the X-ray quan- 
tum behaves as though it were a particle 
and collides with an atomic electron 
ejecting it (Compton recoil electron) from 
the atom. This recoil electron does not 
carry off all the energy of the incident 
photon for the photon survives the col- 
lision but is reduced in energy (i.e. made 
of longer wave length). 
3. Pair Production is the name given to the 
process whereby high energy photons 
interact with atoms (near the nucleus) 
and completely give up their energy to 
form a pair of electrons. One electron is 
the ordinary negatively charged type 
(negatron) that we have already dis- 
cussed but the other is a new type called 
a positron which we will discuss later 
under a section by that title. The latter 
is the same as an ordinary electron ex- 
cept that it is positively charged and has 
a transitory existence. 
These three effects vary in importance de- 
pending upon the energy of the photon con- 
5 RADIOLOGICAL DEFENSE 
rays arise from excitation of nuclei as will 
become clearer in the following sections. 
When a member of a radioactive series under- 
goes a disintegration or decay, we describe this 
process most succinctly by using equations. In 
order to understand the equations involved in 
these radioactive transformations, we introduce 
the following nomenclature: 
Z = atomic number, i.e. the number of pro- 
tons in the nucleus 
A = mass number, i.e. the sum of the nu- 
cleons* in a nucleus 
n = symbol for a neutron 
3H4 or p = symbol for a proton 
e~ or /?- or _3e° = negative electrons 
e+ or /3+ or +1e° = positron 
Any element of atomic number Z may have more 
than 1 mass number associated with it, i.e. have 
more than 1 isotope, so that we have to specify 
the exact mass value for any given value of Z. 
We do this by writing the chemical symbol of 
the element, adding a superscript to indicate 
the mass number and for convenience, a sub- 
script for the atomic number. Thus 
the proton is written as 3H4 
the deuteron (a deuterium nucleus) as 3H2 
and the gold nucleus as 79Au197 
More generally, 
(Chem. Symbol) Mass Number or zxA 
Atomic Number 
The Alpha Particle 
If a quantity of pure radium is sealed in a 
glass tube and allowed to stand for some months, 
it is found that a gas accumulates within the 
tube. By spectroscopic means, this gas has been 
identified as the noble gas, helium. Now we know 
that helium is the simplest of all elements ex- 
cept hydrogen and we conclude that the radio- 
active decay of radium must involve the emis- 
sion of helium nuclei (or alpha particles). We 
express this radioactive transformation as 
follows: 
Here the emission of an alpha particle reduces 
the atomic number of radium by 2 units and the 
mass number by 4 units and we see that equa- 
tion (4) is balanced, so far as subscripts and 
superscripts are concerned, in much the same 
manner as in an ordinary chemical equation. 
The new element radon, formed in the decay of 
radium, is also unstable and proceeds to decay 
forming an isotope of element 84 (polonium). 
The latter is also radioactive and decays by alpha 
emission to form an isotope of lead. We can thus 
piece together a series of transformations, all 
of which are intimately related and form part 
of the uranium series. This part of the series 
is shown as 
U234 « TVl230 « X> y-i 226 a T>rl222 
—» 90 n —* ggXVIl —> ggXVll 
a Pr>2i8 a Ph214 (5) 
—> Si-17 U —> 82-*" u 
where the a (alpha) is used to denote the emis- 
sion of an alpha particle. Scientists commonly 
call the decaying isotope, the “parent” and the 
decay product, the “daughter”. 
As emitted from nuclei alpha particles have 
of the order of 5 Mev of energy and therefore 
move with high velocity. They simply are par- 
ticles composed of 2 neutrons and 2 protons and 
compared to electrons, such nuclei are massive 
and might be expected to be easily absorbed in 
matter. This is really the case for most alpha 
particles are completely stopped by a few sheets 
of thin paper. We shall see later that this very 
short range of action for an alpha particle 
does not prevent it from being effective in dam- 
aging cell tissue. 
Beta Particles 
Lead is commonly thought of as a very stable 
element. By that we mean that it does not under- 
go radioactive decay. However, the isotope of 
lead which is formed in the radioactive series 
(Eq. 5) is not stable. It has 214 nucleons in its 
nucleus and since it must have 82 protons, there 
are 214 — 82 or 132 neutrons in its nucleus. 
Of the lead atoms found in nature the heaviest 
isotope is 82Pb208. Thus the isotope 8„Pb214 is 
much heavier than the heaviest natural lead iso- 
tope for it contains six additional neutrons. 
Instead of emitting an alpha particle which 
88Ra220 8nRn222 + .He4 
(Radium) goes to (Radon) plus (Alpha Particle) (4) 
*The term nucleon refers to either a neutron and/or proton in 
a nucleus. 
6 RADIOLOGICAL DEFENSE 
would make the neutron surplus even worse, the 
lead isotope 82Pb214 emits a beta particle and the 
reaction is as follows: 
82Pb214 83Bi214 + _xe° (6) 
Lead goes to Bismuth plus Beta Particle. 
In this case, lead changes to an element of higher 
atomic number since the emission of an electron 
is equivalent to adding a charge of +e to the 
lead isotope 82Pb214 emits a beta particle and the 
charge is always equal on each side of the equa- 
tion i.e., charge is conserved. Since the electron 
has negligible mass the atomic weight of the 
isotope of bismuth is the same as the parent 
atom. By succeeding /?- and a-emissions the 
bismuth atom is finally transformed to a stable 
isotope of lead (82Pb206), This isotope then 
terminates this series. In addition, the two 
naturally radioactive series, the thorium and 
the actinium series, both finally decay to stable 
isotopes of lead. 
When they are emitted from radioactive 
nuclei, beta particles have of the order of 1 Mev 
energy and thus move with very high velocity. 
In spite of their high velocity these electrons 
are easily stopped in matter. Most beta particles 
have a range of a few millimeters in water and 
only the most energetic penetrate more than a 
few millimeters of aluminum. In contrast to the 
absorption of gamma rays, both alpha and beta 
particles have a rather definite range in matter 
and are easily stopped in relatively small thick- 
nesses of shielding material. 
Later on we discuss the mechanism of the 
emission of beta particles. At this point, how- 
ever, the student may be puzzled as to the 
origin of these beta particles for we have only 
spoken of neutrons and protons as making 
up the nuclei of atoms. One must think of the 
process of beta-decay as similar to that of X-ray 
emission in that the beta particle is created in 
the emission process in the same way that an 
X-ray is created. 
Artificial Radioactivity 
If a nucleus of an atom is subjected to bom- 
bardment by charged particles, such as protons, 
deutrons, or alpha particles, which have been 
artificially accelerated to high velocity in a 
cyclotron or similar machine, it is possible that 
some of the bombarding particles will make a 
collision with target nuclei and a nuclear reac- 
tion may occur. In some instances, the nucleus 
of the target material may be simply “excited” 
by the bombarding particle and it may return 
to its normal state by the emission of a photon 
of appropriate energy. In other cases, the nu- 
cleus may undergo a radioactive transformation 
to form an isotope of another element. In gen- 
eral, substances which are thus made artificially 
radioactive decay either by emission of gamma 
rays, or by beta-decay; in some cases a neutron 
may be emitted but in this instance the reaction 
is an instantaneous one. 
Artificial radioactivity may also be induced in 
many elements by bombarding them with a 
beam of neutrons. 
Certain nuclei, made artificially radioactive, 
by bombardment with charged particles have 
also been found to emit positrons. (See section 
on The Positron.) 
The Neutron 
Prior to 1932, when the proton and electron 
were the particles used to explain the constitu- 
tion of nuclei, theoreticians were unsuccessful 
in their attempts to account for the postulated 
presence of electrons within nuclei and for the 
disagreement of predicted and measured values 
for nuclear constants. In 1932 an English physi- 
cist discovered a new particle known as the 
neutron which was immediately used to success- 
fully explain the physicial constitution of nuclei. 
Chadwick produced neutrons by bombarding 
beryllium with natural alpha particles. This 
reaction is illustrated as 
4Ben + 2He4 —> 6C12 + on1 
The neutron is actually slightly heavier than a 
proton, weighing 1.008937 mass units in com- 
parison to 1.007581 m.u. for a proton. We con- 
ceive of any nucleus of mass number A and 
atomic number Z as made up of N neutrons 
and Z protons. Obviously N must equal A — Z. 
The neutron does not enjoy a “free” exist- 
ence outside the nucleus for it is itself unstable 
and decays according to the reaction 
7 RADIOLOGICAL DEFENSE 
oil1 jH1 + -ffl0 + ,,77° (8) 
where the symbol ov0 (Greek eta) is used to 
denote a new entity called the neutrino (see 
next section). 
In contrast with charged particles which must 
ordinarily have high energy in order to initiate 
nuclear reactions, the neutron is a particularly 
useful particle at even very low (i.e. %0 e.v.) 
energy. 
The Neutrino 
Our previous discussion of beta particles did 
not postulate a mechanism for their emission 
from nuclei. The beta particles emitted from a 
radioactive element such as carbon-14 (C14) are 
not all of the same energy but exhibit a distri- 
bution of energies with a maximum number of 
beta particles having about one-third the maxi- 
mum (EMax) energy. Obviously, we must some- 
how account for the energy which a nucleus has 
available for beta decay. If in a given decay, a 
beta particle carries away energy less than 
EMax, where then does the rest of the energy go ? 
Careful experiments have shown that it is not 
emitted in the form of gamma radiation so that 
a major nuclear mystery is at hand. To solve 
this baffling problem, Pauli postulated the exist- 
ence of a neutral “particle” of almost zero rest 
mass which is emitted during the process of beta 
decay — this particle is called a neutrino and is 
written as oV° where the subscript and super- 
script indicate it has zero mass and no charge. 
There, is very little direct experimental evi- 
dence to substantiate the existence of a neutrino 
and although some experiments support the 
neutrino hypothesis, we must regard the evi- 
dence as supporting rather than proving the 
existence of the neutrino. Once emitted the 
neutrino does not interact with matter or if it 
does so this interaction is not measureable — 
we might say that the half-thickness for absorp- 
tion is several light-years of lead! 
The Positron 
Certain nuclei, such as Cu64, are observed to 
emit positive electrons (positrons), a reaction 
which we describe by the equation 
29Cug4 -> 28Ni64 + +e° + ov° (9) 
Here again in order to account for the observed 
phenomena, we postulate that a neutrino is 
emitted. Once emitted, the positron lives only 
for a few millionths of a second for it is quickly 
absorbed in matter (in pure space it would live 
forever) by a bizarre reaction known as anni- 
hilation. In this unusual process, the positron 
interacts with an electron and there transforms 
itself into two quanta of energy. We indicate 
this reaction as follows: 
+1e° + .jC0 —> 2 Gamma rays (10) 
Thus two particles are destroyed in the anni- 
hilation process to create a pair of gamma rays. 
As we shall see in the material under the 
topic Nuclear Fission, matter and energy 
are interconvertible according to the Einstein 
relation E = me2. In this process two electron 
masses, equivalent when at rest to 1.02 Mev 
energy, produce two 0.51 Mev gamma rays. 
Instead of decaying by positron-emission, the 
Cu64 nucleus may swallow up (it might be 
called a cannibal nucleus) one of its own 
K-electrons in a process known as K-capture. 
Thus 
29Cu"4 + _1en —> 28Ni64 + o77° (11) 
The same end product nucleus (Ni®*) results as 
given in Eq (9). 
The Curie 
You have probably been wondering about the 
time scale on which these radioactive transfor- 
mations take place. Does the radium atom, for 
example, disintegrate in 1 second or in 1 year? 
Actually the process is statistical in nature and 
if we were able to look at one isolated radium 
atom, we might see it decay in a minute or we 
might have to wait a million years for it to dis- 
integrate. If, however, we look at 1 gram of 
radium atoms, we see that there are so many 
atoms ( X 1023 = 3 X 1021 atoms) that 
LiLi O 
there is an average value for the time during 
which 50% of these atoms will decay. This time 
is called the half-life and for radium it is 1,600 
years. If we start out with one gram of radium, 
8 RADIOLOGICAL DEFENSE 
then in 1,600 years we will have only one-half 
gram on hand. 
Radium is said to be long-lived but other 
atoms have extremely short half lives of the 
order of one-millionth of a second. Still others 
like 92U238 (the heavy isotope of uranium) is 
very long-lived, having a half-life of 4.5 X 10° 
years. 
In order to calculate the activity of any sample 
of a radio-active material we multiply the num- 
ber of atoms present as follows: 
and is defined as that quantity of X-radiation 
which on passing through 1 cubic centimeter of 
normal air produces 1 electrostatic unit of ions. 
While it was originally defined only for X-rays, 
the definition is equally valid for gamma rays. 
A smaller unit, the milliroentgen (mr) is often 
used in practice. The definition is perhaps not 
too meaningful to you because of the term 
“electrostatic unit” which is used. Physically, 
one should think of the definition as meaning 
that the quantity of X-rays which is measured 
by a certain number of ions produced in a 
standard volume of air. Quantitatively, 1 roent- 
gen is equivalent to 2.083 X 10° ion pairs per 
cc of standard air. Other equivalences are 
1 r = 1.61 X 1012 ion pairs/gram air 
1 r = 6.77 X 104 Mev/cc air 
1 r = 83.8 erg/gram air 
Later on you will see that different types of 
instruments can be used to measure X-radia- 
tion. These are ionization chambers, Geiger- 
Mueller counters, and photographic emulsions. 
One should sharply distinguish between two 
types of measurements — 
A — Those that measure the dose or total quan- 
tity of radiation. 
B — Those which give the dose-rate or the in- 
tensity of radiation. 
Dose is measured in roentgens whereas dose- 
rate is measured in terms of roentgens/second 
or roentgens/minute or in other time units. It 
is one thing to give a patient a dose of 1 r of 
X-rays and quite another to expose a patient to 
a dose-rate of 1 r/second. In the latter case, the 
patient receives a 1 roentgen dose in one second 
and a 60 roentgens dose in 1 minute. In 1 hour 
the patient would be dead or would be as good 
as dead. 
Activity = (No. of Atoms) (.69) 
y Half Life (in seconds) 
= disintegrations per second 
Suppose we calculate the activity of 1 gram 
of radium. Now 226 grams of radium are equal 
to 6 X 1023 atoms so 1 gram is 2.6 X 1021 atoms 
and since the half-life is 1,600 years or 5 X 1010 
seconds 
A .. ,A * , * „ (2.6 X 1021) , 
Activity of 1 gm of Ha = 5 x lb4~ 
= 3.7 X 1010 disintegrations/second. 
In practice this activity is called the curie and 
is an accepted standard unit. You are perhaps 
familiar with the millicurie (me) unit which is 
1 thousand times smaller than the curie. A new 
unit, known as the rutherford, abbreviated rd, 
is defined as the quantity of a radioisotope that 
disintegrates at the rate of 1 million disintegra- 
tions per second (i.e. 106 dis/s). 
The Roentgen 
In treating a patient with y radiation from 
a radium capsule it is necessary to measure the 
dose which is given. For this purpose we use a 
unit called the roentgen named after the discov- 
erer of X-rays. The roentgen abbreviated is r 
9 RADIOLOGICAL DEFENSE 
NUCLEAR FISSION 
Ralph E. Lapp, Ph.D. 
The Nucleus 
We have already given some description of 
the constitution of the nucleus but as yet we 
have not given any explanation of the forces 
operating within the nucleus, neither have we 
discussed the nature of the meson. As it hap- 
pens, the two are intimately related for the 
meson is postulated to be a particle that is 
“exchanged” between a pair of nucleons within 
a nucleus and thus binds them together. In the 
next section we shall have more to say about 
mesons; for the present let us confine our atten- 
tion to the neutrons and protons within the 
nucleus. 
The central core or nucleus of an atom is a 
dense aggregate of nucleons all of which are in 
a constant state of agitation and rapid motion. 
We liken the nucleus to a liquid drop in which 
the nucleons are bound to each other by short 
range nuclear forces. By using the words “nu- 
clear forces” we refer to the queer type of forces 
that are exerted between nucleons and keep the 
nucleus together. Other types of forces, such as 
gravitation or electrostatic, are utterly inca- 
pable of explaining the magnitude of the energy 
bound up within the nucleus. We are thus forced 
to assume the existence of a nuclear force that 
is effective over a very short range (about 
IQ-13 cm) and is negligible outside the nucleus. 
All nuclei are of practically negligible volume 
in an atom when compared to the total volume 
of the atom as defined by its outermost electron 
shell. Furthermore a nucleus of aluminum is 
not very much smaller than that of the heaviest 
naturally occurring isotope, i.e. U238. If we 
imagine an atom viewed in cross section, the 
atom itself has an area of about IQ-16 sq. cm. 
whereas the nucleus occupies only about 10~24 
sq. cm. Physicists often refer to the unit of 
10~24 sq. cm. as a ham. 
The Meson 
At this stage in the student’s development it 
may seem unduly sophisticated to introduce any 
discussion of the meson and we do so with the 
assumption that he will skip quickly to the next 
section should he be too confused by the nature 
of the unusual particle. 
There are two distinct kinds of mesons (or 
mesotrons) ; a heavy kind having a mass about 
285 times that of an electron and a light or 
ordinary kind that is found in the cosmic radi- 
ation. The light meson has a mass about 215 
electronic masses and in common with the heav- 
ier type occurs both as a positively charged 
particle and also as one bearing a negative 
charge equal to that carried by an electron. In 
this discussion we shall consider only the heav- 
iest mesons for they are the ones which are 
involved in nuclear forces. These mesons are 
extremely unstable and decay in about 4 X 1(T8 
seconds. Normally they are not found outside 
the limits of the nucleus. Theoretical physicists 
assume that a neutron within a nucleus changes 
into a proton, and similarly a proton into a 
neutron, by the emission of a positive or nega- 
tive meson respectively. These interchanges of 
identity of the nucleons occur with extreme 
rapidity and the meson thus acts as an exchange 
particle serving to bind a pair of nucleons 
together. 
The Mass-Energy Law 
The relation E = mc2, first announced by Ein- 
stein, achieved front-page headlines with the 
detonation of an atomic bomb over the city of 
Hiroshima. In an atomic bomb detonation a 
large number of uranium-235 or plutonium-239 
(a transuranium element manufactured from 
U238) nuclei are split in two parts or fissioned. 
Splitting of a compact heavy nucleus into two 
approximately equal parts serves to “convert” 
an appreciable amount of mass, actually about 
*4 mass unit, into energy. Let us now apply the 
Einstein equation to a single fission process and 
calculate the energy released. 1 mass unit is 
about the weight of one proton or one neutron 
and is equal to 1.6 X 10~24 grams. Therefore 
10 RADIOLOGICAL DEFENSE 
mass unit is 0.4 X 10-24 grams and the 
energy equivalent to it is simply 
(0.4 X 10-24) X (3 X 1010)2 
where 3 X 1010 cm/sec is the velocity of light. 
Multiplying, we see that this product equals 
3.6 X 10~4 ergs. To convert to electron volts, we 
must multiply ergs by a factor 6.25 X 1011. This 
multiplication yields 230 Mev (million ev). 
Thus the fission of a single U235 nucleus yields 
roughly 200 Mev of energy. However, the origi- 
nal unfissioned U235 nucleus is itself equivalent 
to a total energy of about 220,000 Mev so that 
per fission we realize a release of only 200/ 
220,000 or one-thousandth of the total energy. 
Previously in this section the word—convert 
—was used in quotation marks so that the 
reader would not assume that mass is actually 
converted into energy in the sense that a frac- 
tional part of a neutron or proton is trans- 
formed into energy. The fission process for 
U235 can be represented by Equation (1) 
pj235 _|_ ni pp + pp _|_ energy (1) 
where FP is the symbol for fission product. In 
this process the U235 nucleus splits into two 
lighter nuclei which are more stable than the 
U235 nucleus. The total number of neutrons and 
protons before and after fission remains the 
same. We can write the equation relating 
masses of the Equation (1) as: 
Mass (U235 + Mass (n1) 
= Mass of FPs + A (2) 
where A is the mass equivalent of the energy 
released. 
If we consider a hypothetical example in 
which the two fission products are both tin 
nuclei of mass number 118 (Sn118) we can re- 
write Equation (2) as: 
Mass (U235 + n1) 
— Mass (Sn118 + Sn 118) + A (3) 
Given that U235 weighs 235.112 mass units 
(m.u.), the neutron 1.009 m.u. and the Sn118 
as 117.940 m.u., we see that the masses on 
the left hand side of the equation total 236.121 
m.u. while the right hand side equals 235.880 
m.u. Thus the more stable tin nuclei weigh 
less than the nucleus from which they split. The 
mass difference A = 0.231 m.u. when multi- 
plied by 931 Mev per m.u. is equal to 215 Mev; 
this is the energy released in fission. 
Bombarding the Nucleus 
We have already postulated that the nuclear 
forces are such that their effect, or more pre- 
cisely termed their field i.e. area of influence, is 
confined to the nucleus. However, the protons 
inside the nucleus make themselves known out- 
side the confines of the nucleus by their electro- 
static “field”. This “field” forms a barrier 
around the nucleus which prevents any charged 
particles from entering the nucleus. If, however, 
the particle which seeks to enter it is uncharged, 
the nucleus cannot see it and offers no resistance 
to its entry. For this reason, neutrons of low 
energy can easily slip inside the nucleus whereas 
protons of very high velocity are barred. Every 
technique that man has devised for producing 
high energy charged particles involves consider- 
able equipment and operational cost far in ex- 
cess of the energies generated by the nuclear 
reactions which are produced by the bom- 
bardment. 
In any bombardment of a target with a beam 
of charged particles we find that the number 
of “hits” made by the bombarding particles 
are small in comparison to the number of 
particles in the incident beam. The reason for 
this low “batting average” is that the nucleus 
is such an infinitesimal part of the atom that it 
exposes very little target surface to the bom- 
barding missile. If we consider only the geomet- 
rical cross-section of the nuclei (i.e. 10~24 sq. 
cm.) then we see that the chance that an inci- 
dent particle will strike in this area is 10~24/10~16 
where the denominator is the area of a single 
atom; this means that the probability is only 1 
in 100,000,000 that the particle will score a “hit”. 
Actually this probability is somewhat higher 
since a single particle may pass through many 
layers of atoms, say, a 100, so that only one 
incident particle out of every million produces 
a “hit”. 
It is a peculiar property of the neutron that 
it produces nuclear reactions with a much 
higher probability than do charged particles. 
11 RADIOLOGICAL DEFENSE 
Another way of saying this same thing, is to 
state that some nuclei have an extremely large 
‘‘cross section” for neutron-induced reactions. 
These cross sections may be 500, 1000, or 
10,000 (and even more) barns; this, in effect, 
means that the nucleus presents a virtual 
cross sectional area for the neutron far larger 
than its geometrical area. One of the reactions 
which has such a high cross section is that of 
nuclear fission in the heavy elements. 
A Model of the Fission Process 
A few very heavy nuclei, such as U235, when 
bombarded by slow neutrons react very violent- 
ly by splitting into two almost equal parts. The 
process is called nuclear fission or simply fission 
and the isotopes which exhibit this unusual be- 
havior are called fissionable. The heavy products 
of the fission reaction, i.e. the two halves of the 
heavy atom are known as fission products or 
fission fragments. 
We can picture the fission process by bring- 
ing into consideration the liquid drop model of 
the nucleus which we have just discussed. Let 
us imagine that before the neutron enters the 
uranium 235 nucleus all the 92 protons and 143 
neutrons are in constant motion inside the 
spherical nucleus. Let us assume that because 
these nucleons are so close together and move 
about so rapidly, that they lose their individual 
identity and may be thought of as forming a 
fluid or liquid drop of uniform density. With 
the intrusion of a neutron into this contented 
system, the liquid drop has energy added to it 
and becomes excited. The particles inside the 
nucleus are set into more violent motion and the 
drop begins to lose its spherical shape. As it 
deforms into a non-spherical shape it sets up 
rapid oscillations which deform it still further 
into a dumbbell pattern. At this point the orig- 
inal sphere is essentially drawn out into two 
smaller spheres with a tenuous connecting link 
which then snaps. Then the two fission products 
shoot away from each other with high velocity. 
All this happens in an exceedingly short time 
interval of less than 1(H2 seconds. 
Of the 200 Mev of energy released in a single 
fission process the majority of the energy goes 
into energy of motion of the fission fragments 
(kinetic energy). If the material undergoing 
fission is in the form of a metal, then the fission 
fragments will travel only a very short dis- 
tance before they lose their energy. In this short 
distance the kinetic energy of the fission prod- 
uct is imparted to other surrounding atoms 
which then are excited to higher speeds. Thus 
if a sufficient number of fissions occur per unit 
volume of the metal, then the totality of the 
unfissioned atoms will be increased in their ki- 
netic energy and as a result the temperature of 
the mass will increase proportionately to the 
number of fissions taking place. Whether or not 
the energy is released in an atomic bomb ex- 
plosion or in an atomic power plant, the source 
of energy is the same, namely, in the heat energy 
produced by the fission fragments. 
The Fission Products 
It would be rare for a pair of fission prod- 
ucts to have the same mass and we know that 
it is much more common for one of the prod- 
ucts to be heavier than the other. In general, 
there are two groups of fission products, one 
with an average mass number of about 95 and 
the other of about 139. Just why the two frag- 
ments are unequal in mass, we do not know. 
We do know, however, that the fission prod- 
ucts are intensely radioactive, emitting high- 
energy beta particles and gamma rays. By 
emitting /3-particles, the isotopes which contain 
too many neutrons (or too few protons) tend 
to make themselves more normal since 
sion is equivalent to changing a nuclear neutron 
into a proton. Because the fission products are 
born with such extreme neutron excesses (or 
proton deficits) it requires four or five separate 
/3-decays to result in stable atoms. Thus each 
fission product is often associated with a chain 
of radioactive isotopes and for this reason we 
speak of fission chains. Almost all fission prod- 
ucts emit very penetrating gamma rays in addi- 
tion to beta particles. The half lives for the vari- 
ous fission products vary from a fraction of a 
second to many years. 
The result of fissioning a large number of 
atoms is that we have an aggregate of many 
12 RADIOLOGICAL DEFENSE 
different fission products representing almost 
every element from atomic number 40 to 70. 
This fact makes the chemical decontamination 
of fission products a veiy difficult task. 
If we were to assume that a U235 is split into 
fission products of exactly the same mass and 
atomic number, then we would have two Pd118 
nuclei (Pd is the symbol for palladium). The 
heaviest naturally occurring isotope of this ele- 
ment is Pd110 so we see that such a fission prod- 
uct as Pd118 would have a neutron excess of 
8 neutrons as compared to Pd110. As we have 
just explained this neutron excess can be re- 
lieved by successive emissions of beta particles 
from the fission product nucleus. One might 
wonder, however, if an alternate process might 
occur: could not the fission product emit a 
neutron ? 
Neutrons from Fission 
Actually neutrons are observed to be emitted 
in fission. Work by Zinn and Szilard (see ref- 
erence) has shown that an average of 2.3 
neutrons are emitted per fission. Over 99 per- 
cent of these neutrons are 'prompt, i.e. emitted 
within an extremely short time of less than 10~10 
seconds, but even so it has been shown that these 
neutrons are emitted by the fission products. 
There are some (less than 1%) of the neutrons 
which are not prompt but are delayed in emis- 
sion by 10,15, 30, and 45 seconds. These delayed 
neutrons are of extreme importance in the appli- 
cation of nuclear fission in a chain reactor or 
pile. Only a very few of the fission products are 
known to emit delayed neutrons and the longest 
half-life observed for delayed emission is 1 
minute. 
In addition to the neutrons emitted from fis- 
sion, there are rarer events associated with the 
fission process. Sometimes, perhaps once per 
thousand fissions, the nucleus fissions into three 
fragments rather than into the customary pair 
of fission products. Furthermore, high energy 
alpha particles sometimes accompany the fis- 
sion process. One should remember that these 
are rare events and do not alter our simple pic- 
ture of the fission process as given in the sec- 
tion on a model of the fission process. 
The Chain Reaction 
If we wish to talk about the fission of large 
numbers of uranium atoms it is necessary to 
have large numbers of neutrons available. Be- 
cause the fission process requires only one 
neutron to initiate it and yet gives off between 
two and three neutrons per fission, it is possible 
to use fission neutrons to start a “chain” of fis- 
sion reactions. Each fission adds more neutrons 
to the reaction so that more and more reaction's 
are possible. Such reactions are called self- 
sustaining or chain reactions. 
Since the fission process occurs so quickly, it 
is conceivable that if we were to properly as- 
semble a certain “critical” mass of fissionable 
material such as U-235, we could set off a series 
of fissions which would proceed so quickly that 
the recoiling fission products and radiations 
would raise the critical mass to a multi-million 
degree temperature within a fraction of a sec- 
ond. By definition, such a process would be 
explosive in nature. 
Prior to World War II, no pure U-235 was 
available. Ordinary uranium metal contains 
140 times more U-238 than it does U-235. Now 
U-238 is not suitable for a chain reaction be- 
cause when it absorbs a neutron into its nucleus, 
it merely changes into a heavier element with- 
out fissioning. Since the two isotopes of uranium 
are chemically identical, they had to be sepa- 
rated by exceedingly difficult physical methods. 
In fact, the methods presented so many technical 
obstacles, that the Manhattan Project set up 
huge plants which used nuclear reactors running 
on natural uranium to generate a new man-made 
fissionable material — plutonium. 
Plutonium 
With neutrons released in the fission of the 
small amount of U-235 present in natural ura- 
nium metal, it was possible to sustain a chain 
reaction in a pile of graphite and uranium. 
Under proper conditions a large number of these 
fission neutrons can be absorbed by the U-238 
atoms. This results in an unstable U-239 nu- 
cleus which rapidly decays by beta emission 
as follows: 
13 RADIOLOGICAL DEFENSE 
,2U!“ + „n‘ 82U““ 93Np'39 + .,e» (4) 
Here Np is the symbol for the new transura- 
nium element neptunium. Neptunium is itself 
radioactive and soon decays to form an isotope 
of element 94 which has been named plutonium. 
Thus 
„oNp239 2 3d ..Pu239 + 0 (5) 
The figure 2.3d over the arrow means that this 
reaction has a half-life of 2.3 days. 
Plutonium is a dense silvery metal similar to 
uranium U-235 in that it is fissionable with slow 
neutrons (i.e. neutrons which are of low en- 
ergy) . Like U-235 it is also an alpha emitter 
but since it has a half-life of 24,000 years, it is 
much more active than U-235 which has a half 
life of 7 X 108 years. The alpha activity of plu- 
tonium is sufficiently intense so that it con- 
stitutes a dangerous health hazard of about the 
same order as radium when it is deposited in 
bone matter. 
The Concept of Critical Size 
One of the unique characteristics of an atomic 
explosive is that it must be assembled into a 
certain critical size before it can explode. The 
reason for this unusual characteristic is that the 
chain reaction will not be a self-perpetuating 
one unless there are sufficient neutrons to cause 
continued fission. Suppose, for example, we wish 
to run a chain reaction at a rate of 500 fissions 
per second. Suppose, further, that each fission 
generates exactly two neutrons. This requires 
that one out of every two neutrons generated 
must be used to produce more fissions, so that 
we have to have 500 neutrons being used every 
second to cause fission. This leaves an addi- 
tional 500 neutrons which we can afford to 
“lose” from our system either by absorption 
(not leading to fission) or by loss through es- 
cape from the system. By increasing the 
amount of fissionable material in the assembly, 
we finally succeed in overcoming the loss of 
neutrons and the system becomes supercritical 
and self-sustaining. 
If we know the number of fissions occurring 
per unit time in a reactor we can immediately 
deduce the power level of operation by using 
the relation that 1 watt of power is equal to 
3 X 1010 fissions/seconds. Thus in a 1000 kilo- 
watt pile 3 X 1016 atoms are fissioned each sec- 
ond and in one day’s operation 86,400 X 3 X 
1016 or 2.5 X 1021 atoms are fissioned. To con- 
vert this figure into grams of U235 consumed 
per day, we multiply the mass number —235 
and divide by Avogadro’s number — 6 X 1023, 
This yields a result that 1 gram of U235 is fis- 
sioned per day and, of course, 1 gram of fission 
products is produced per day, 
The Atomic Bomb 
A logical way to assemble an atomic bomb 
might be to take two hemispheres of fissionable 
material each of which is sub-critical and bring 
them very quickly together to form an over- 
critical mass. A heavy gun barrel might be 
used for the purpose of achieving such a result. 
One hemisphere of pure U-235 might be im- 
bedded in a large mass of material (tamper) 
placed at the target end of a gun barrel. At the 
other end of the barrel might be another hemi- 
sphere which serves as a projectile. Separated 
by the length of the gun barrel, each hemisphere 
would be sub-critical and safe, but by firing the 
one hemisphere down the barrel, it would attain 
a high velocity and weld itself together with the 
target into an over-critical mass. The inertia of 
the projectile together with an appreciable 
length of time of contact would be necessary so 
that a large amount of the uranium would be 
fissioned. This might insure a high “efficiency” 
for the reaction. No data are available to specify 
a value for this efficiency. 
The value for a critical mass of U235 or Pu239 
is secret but we can easily calculate the value 
of the amount of U235 that is fissioned in an 
atomic detonation given as equivalent to 20,000 
tons of high explosive—this value is the prod- 
uct of the amount of fissionable material used 
in the bomb multiplied by the efficiency of the 
gross fission process. Now 20,000 tons of high 
explosive are equal to 1.8 X 1013 calories or 
4.8 X 1026 Mev. We know that each fission 
releases about 200 Mev of energy, about 85 per- 
cent of which is released in the form of heat. 
14 RADIOLOGICAL DEFENSE 
This means that 20,000 tons of high explosive 
4 8 X 1026 
= ' 170 X 2.8 X 1024 U235 atoms fissioned. 
The latter is equal to 1100 gms of U235 or 
roughly 1 kilogram of U235. 
Atomic Bomb Phenomena 
In the Appendix, the reader will find refer- 
ences for the various effects associated with the 
detonation of an atomic bomb. One should bear in 
mind that there are the instantaneous or prompt 
effects as well as the prolonged or what may be 
called the long-term effects. Each effect is sen- 
sitive to the conditions under which the bomb is 
exploded. Thus a high air burst leaves little or 
no residual radioactivity in the vicinity of the 
bomb burst whereas an underwater explosion 
is certain to produce severe local contamination. 
Wherever radioactive contamination occurs, 
the area must be carefully surveyed with reli- 
able radiation measurement instruments in 
order to determine the nature and degree of the 
radioactive hazard. Thereupon the data obtained 
must be reviewed and interpreted by a trained 
health physicist or radiological safety officer in 
order to insure that personnel admitted to the 
area are not unduly exposed to radioactivity. 
Health Protection 
In the case of fission products or other radio- 
active material which is deposited on a surface, 
we may divide up the hazards into two 
categories: 
A. The External Hazard 
Because of the extreme penetrating 
power of gamma rays, any source emitting these 
rays may constitute an external hazard even 
though the source is considerably removed from 
the site of exposure. Long experience with 
X-radiation has led to a permissible dose rate 
of 0.1 roentgen per day. Setting up a figure of 
0.1 r/day should not be interpreted as giving 
personnel license to receive this full amount of 
radiation per day; wherever possible, operations 
should be conducted so that the minimum 
amount of dose is received. Present indications 
are that a dose of 0.1 r per day received 5 days 
a week for long periods of time is not harmful to 
personnel, but we caution that too little is known 
of the long-term chronic effects of penetrating 
radiation to regard this permissible dose rate 
as absolute. If a pharmacologist assures you 
that a daily dose of so many grains of arsenic 
is not injurious to the human system, we are 
certain that you will not be tempted to take that 
much arsenic on a daily basis; the same caution 
should apply to nuclear radiation. 
B. The Internal Hazard 
Should radioactive emitters gain en- 
trance into the body, either through ingestion or 
inhalation or by other means, they may be re- 
tained in the body and constitute an internal 
radioactive hazard. Whereas alpha and beta 
particles rarely constitute a source of external 
hazard, when they are emitted in the body they 
may create intense ionization in localized areas, 
such as bone marrow, where they may do irrep- 
arable damage to vital cell structures. Further- 
more, since the emitters may lodge deep within 
the body and be difficult to identify with health 
monitoring instruments, the hazard is all the 
more insidious. For this reason, health physi- 
cists set up certain tolerance concentrations for 
specific isotopes in air and in liquids, and sys- 
tematically monitor these media to prevent ex- 
posure of personnel to dangerous hazards. The 
actual quantity of a given radioelement that 
can be tolerated without damage to the body 
depends upon the chemical form of the element, 
the percentage uptake by the body, the rate of 
excretion from the body, the physical character- 
istics of the isotope (half-life, particle emitted, 
energy of radiation, etc.), and the site where 
the radioelement lays down in the body. 
Lest the reader feel undue apprehension about 
the feasibility of large scale work with radio- 
active material, let us point out that given prop- 
er health surveillance and monitoring equip- 
ment, operations with even very large quantities 
of radioactivity may be carried out safely. But 
because radioactive hazards must be detected 
by instruments sensitive to them (nature not 
having seen fit to endow man with faculties to 
sense nuclear radiation) we must be ever alert 
to the potential of radioactive hazards. 
15 RADIOLOGICAL DEFENSE 
THE ATOMIC BOMB 
AND THE RESULTANT PHENOMENA 
Herbert Scoville Jr., Ph.D. 
Technical Director, 
Armed Forces Special Weapons Project 
The basic reaction in an atomic bomb explo- 
sion is the fission of either uranium-235 or 
plutonium. This reaction may be broken down 
into the following steps: 
(a) The capture of a neutron by a U-235 
nucleus to form a very unstable nucleus 
Uranium-236. 
(b) The deformation of the unstable U-236 
nucleus. G0 
(c) Fission of U-236 into two unstable fis- 
sion products and with the production 
of one to three neutrons and two gamma 
rays per fission. 
In an atomic bomb this reaction is made to 
occur almost simultaneously on the part of a 
very large number of atoms. Since this reac- 
tion produces large amounts of energy (200 
Mev per fission) from the conversion of some 
of the mass of the original U-235, tremendous 
quantities of energy are released. This energy 
will be released in several different forms, i.e. 
as blast pressure, by the bomb explosion, opti- 
cal or thermal radiation, and nuclear radiation. 
All explosive weapons produce high blast pres- 
sure and release some thermal radiation. Of 
all weapons yet devised, only the atomic bomb 
will release nuclear radiation. For this reason 
and not because it is necessarily of dominant 
importance, greatest emphasis in this discus- 
sion will be placed on the nuclear radiation, 
and the blast and thermal effects will only be 
mentioned for comparison with the nuclear 
radiation. 
Types of Nuclear Radiation 
Nuclear radiations produced from the det- 
onation of an atomic bomb consist of a number 
of different types. First, and most important, 
are the gamma rays. Gamma radiation is high 
energy, electromagnetic radiation similar to 
visible light or x-rays. In fact, gamma rays 
have quite similar properties to x-rays, the 
only difference being that they have more 
energy and are consequently more penetrating. 
When an atomic bomb is detonated, gamma 
rays are generated chiefly in two ways. First, 
prompt gamma rays are produced directly as 
a product of the fission reaction itself. Since 
the fission reaction is completed within a mi- 
nute fraction of a second after the bomb is 
detonated, these prompt gamma rays are emit- 
ted practically instantaneously at the time of 
detonation. The second main source of gamma 
rays are the fission products themselves. In an 
atomic bomb explosion the fissionable material, 
uranium-235 or plutonium, splits into two 
atoms of intermediate atomic weight. Since the 
fission reaction does not always take place in 
exactly the same manner, many different ele- 
ments are produced by fission in any atomic 
bomb detonation. These fission products are 
almost all unstable and undergo radioactive 
decay emitting either or both gamma rays and 
beta particle. 
The rate of decay of each of the various fis- 
sion products is different, and the half-lives of 
the individual fission products will vary from 
fractions of a second to thousands of years. 
(The half-life of a radioactive material is the 
time required for half of the atoms of that 
material to undergo decay.) Because of this 
variation in the half-life, gamma rays from 
fission products are emitted in decreasing quan- 
tities from the time of detonation to years later. 
As an approximation, it may be stated that 
the rate of decay is inversely proportional to 
the time after detonation. In practice this 
means that 1 hour after the detonation the 
radiation from fission products is 1/60 of that 
at 1 minute. Similarly, 1 day later the radia- 
tion is 1/24 of that at 1 hour, and 1 year later 
it is 1/365 that at 1 day. 
In addition to the gamma radiation produced 
16 RADIOLOGICAL DEFENSE 
by an atomic bomb detonation, there are large 
quantities of neutrons emitted. A neutron, one 
of the elementary building blocks of all matter, 
is a neutral particle with an atomic mass of 
one. Because of their lack of charge, neutrons 
are extremely penetrating. Neutrons which 
have a very high energy, (i.e. fast neutrons) 
are produced as a direct product of the fission 
reaction. In addition, a smaller number of so- 
called delayed neutrons are emitted within a 
few seconds of the detonation as a product of 
the decay of a certain few fission products. The 
delayed neutrons also have high energies. Fast 
neutrons are slowed down by collision with 
molecules in the air so that at any appreciable 
distance from the detonation, both slow and 
fast neutrons are present. When neutrons are 
absorbed or “captured” by an atom of matter, 
they frequently make the matter artificially 
radioactive. This “induced” radioactivity is then 
often an additional source of gamma radiation. 
As previously mentioned, the decaying fission 
products emit beta particles as well as gamma 
rays. These beta particles are high speed elec- 
trons which are produced in a nuclear reaction. 
Although the energy of these beta particles is 
high, their penetrating power is relatively low 
and would not produce appreciable effects more 
than a few meters from their source. They 
might, however, produce serious effects to per- 
sonnel, operating in an area contaminated with 
radioactive fission products. Beta emitting 
materials provide a serious hazard if absorbed 
internally. 
Finally, a further type of nuclear radiation 
which may be present following an atomic bomb 
detonation is alpha particles. Any unfissioned 
plutonium or uranium-235 which may be 
present following a detonation will decay very 
slowly with the emission of alpha particles. 
The half-life of plutonium is 25,000 years and 
U-235 is 109 years so that the a-emission per 
unit time is greater for plutonium than for 
corresponding amounts of U-235. Since alpha 
particles have little penetrating power and can 
be stopped even by a sheet of paper, they do 
not provide any external radiation hazard, but 
if an emitter gains entrance into the body 
either by inhalation, ingestion or through a 
wound, then the alpha activity might provide 
a serious hazard. 
Detonation of an Atomic Bomb in the Air 
Most of the atomic weapons which have been 
exploded to date were detonated in the air. The 
altitudes of these detonations have varied from 
close to the ground, in the case of the New 
Mexico tests, to high altitudes in the case of 
the two attacks on Japan. The information ob- 
tained from observations on personnel at 
Hiroshima and Nagasaki, and confirmed by 
physical measurements made during tests, indi- 
cate that a median lethal exposure of gamma 
radiation is obtained in the open at a distance 
of about three-quarters to 1 mile from the 
point of detonation. Thus, most exposed per- 
sonnel in an area of about 2 square miles 
would have been killed by these rays. However, 
the blast and thermal radiation throughout this 
same area would also have been very great so 
that a large number of casualties observed re- 
sult from these causes rather than directly from 
the gamma rays. For comparison it is inter- 
esting to note that the blast damage to heavy 
concrete structures was extensive in Japan at 
distances greater than 1 mile from the point of 
detonation and residential structures were af- 
fected at distances greater than 2 miles. Ex- 
posed personnel were subjected to first-degree 
burns at distances as far as 2 miles from the 
point of detonation, and serious flash burns 
were obtained at a distance of three-quarters of 
a mile. Protection against flash burns can, how- 
ever, be relatively easily obtained since even 
thin coverings are sufficient to provide protec- 
tion against this effect. Excellent examples of 
this are the photographs from Japan, which 
show severe scorching of exposed parts of the 
Doctor Scoville received his B.S. at Yale and 
his Ph.D. in Physical Chemistry at the Uni- 
versity of Rochester. During World War II he 
worked with Division 10, National Defense Re- 
search Committee on chemical warfare problems. 
He participated in the atomic tests at Bikini and 
Eniwetok. At present, he is the Technical Direc- 
tor of the Armed Forces Special Weapons 
Project. 
17 RADIOLOGICAL DEFENSE 
body as compared with relatively little effect 
on the skin, protected by light colored clothes 
which reflected the radiation. 
The great penetrating power of gamma rays 
makes the problem of providing protection 
against them at close range extremely difficult. 
Experiments have indicated that about 1 inch 
of steel is required to reduce the gamma radi- 
ation by a factor of two. Concrete is about a 
third as effective as steel and ordinary dirt, 
about one-fifth as effective. Since, with an air 
burst, practically all of the effective gamma 
radiation is emitted almost instantaneously at 
the time of detonation, the radiation can be 
considered as coming from a sphere essentially 
centered at the point of detonation. Therefore 
important shadow effects are produced by a 
shield. However, since at the distances where 
shielding is at all practicable, the radiation may 
be scattered several times, an important frac- 
tion of the total gamma radiation must be 
considered as coming from all directions. 
Therefore, although it is most important to 
have protection between the individual and the 
point of detonation, it is necessary to have some 
shielding on all sides of the individual. This 
consideration is, of course, somewhat academic 
in practice since it will not ordinarily be possi- 
ble to know in advance in what direction will 
be the point of detonation. It should be pointed 
out, in this respect that since the largest frac- 
tion of the gamma rays are emitted almost at 
the time of detonation, it will be almost impos- 
sible for an individual to take shelter from the 
radiation after he has seen the bomb explode. 
Personnel will only be safe if they are in dug- 
outs, heavily constructed buildings, or large 
warships at the time the bomb explodes. 
Although large quantities of neutrons are 
emitted at the time of the detonation of an 
atomic bomb, their range of effectiveness is in 
most cases negligible by comparison to that of 
the gamma rays. Nevertheless, because of the 
even greater penetrability of the fast neutrons, 
a situation could conceivably arise in which the 
gamma rays were absorbed and yet the neu- 
trons penetrated and produced effects. How- 
ever, in most practical situations the neutrons 
can be neglected. They might, however, induce 
radioactivity in certain elements near the point 
of detonation, and these might provide some 
residual radioactivity. This was the case in 
test Able at Bikini where the sodium in the sea 
water captured neutrons and became radioac- 
tive. While this interfered slightly with opera- 
tions during the test at Bikini, it was probably 
not of sufficient magnitude to provide a serious 
problem in wartime operations. 
The residual contamination both from depos- 
ited fission products and neutron induced radio- 
activity will depend on the altitude from which 
the bomb is detonated. Thus, at Alamagordo 
where the bomb was exploded close to the 
ground, the crater contained considerable 
amounts of residual radioactive material. Sam- 
ples of material from this site are still radio- 
active. The size of this contaminated area, how- 
ever, was quite limited. In Japan, where the 
bomb was detonated at much higher altitudes, 
there was little detectable radioactivity within 
a few days of the detonation. 
Most of the fission products and unfissioned 
material in an airburst are carried up to 30,000 
to 60,000 feet in the atomic bomb cloud. These 
are then dispersed downwind and rapidly di- 
luted so as to provide little hazard. However, 
there is a certain hazard downwind from a 
fallout of this radioactive material, either as 
rain or as dust. For example, 50 miles away 
from the Trinity site in New Mexico radio- 
active materials fell on some cows and turned 
their hair white in spots. No other harmful 
effects were noted on these animals. Because of 
this danger it will always be desirable to track 
the cloud as it moves downwind, and survey 
areas which might possibly be contaminated by 
material falling out of it. However, in all 
probability, such fallout would be only a sec- 
ondary hazard under wartime conditions. 
Detonation of an Atomic Bomb Underwater 
In an underwater detonation of an atomic 
bomb, such as occurred at Test Baker at Bikini, 
the effects are quite different from those which 
occur following an airburst. For example, with 
the one detonated at the depth used at Bikini, 
the thermal radiation effects were almost com- 
pletely absent. The blast pressure produced by 
18 RADIOLOGICAL DEFENSE 
the explosion was evidenced in two forms, i.e., 
underwater shock and air blast. The air blast 
produced was not as great as that which occurs 
following an airburst, but was, nevertheless, 
very great and would have produced significant 
damage at some distance. 
The nuclear radiation effects are also quite 
different in the two types of detonation, and 
would, in most cases, probably be more serious 
following an underwater shock than an air- 
burst. The prompt gamma rays and neutrons 
are practically all absorbed by the water which 
surrounds the bomb. However, the radioactive 
fission products and unfissioned material are 
trapped in the water and carried aloft in the 
column and cloud. While the neutron activity 
induced in sea water may contribute to the 
total radioactivity carried aloft in this manner, 
it is nevertheless only a small fraction of the 
total. Thus the effects would be practically the 
same if the bomb were detonated in fresh or 
salt water. When the column descends, a con- 
centrated mist shoots out from the base and 
spreads the radioactive materials over the sur- 
rounding area. The rain from this mist or so- 
called base surge and from the cloud will then 
deposit these materials leaving serious contam- 
ination over a large area. 
The exact area covered by this mist and sub- 
sequently contaminated will depend on the wind 
velocity. As a rough approximation the lethal 
area may be considered to extend about one-half 
mile upwind and two or more miles downwind. 
Serious contamination would be obtained at a 
much greater distance. At Bikini nearly all the 
target ships, although otherwise undamaged, 
were heavily contaminated, and if the bomb 
were detonated offshore of some large city, the 
situation might well be catastrophic. In such 
a case a city might have suffered little visible 
damage and yet be essentially a ghost city. 
Most of the inhabitants at the time of the 
explosion would have been killed, evacuation 
would have been required for all others, and 
reentry of personnel would be restricted to 
limited periods. The effect of such an attack on 
a number of our large cities might completely 
paralyze the industrial power of our nation. 
To give an idea of the magnitude of the 
problem it might be best to compare the radio- 
activity of the fission products with that of 
radium. A gram of radium is an extremely 
large quantity of this material and in fact 
only a few pounds had been isolated up to the 
beginning of the war. In general one deals 
with thousandths or even millionths of a gram. 
The radioactivity from the fission products 
deposited in Bikini lagoon has, however, been 
estimated to be equivalent to thousands of tons 
of radium shortly after the detonation. This is 
a billion times the radioactivity from a gram 
of radium. Such is the truly fantastic radio- 
activity associated with an atomic bomb deto- 
nation. 
Fission products deposited on the water 
would probably in most cases be diluted fairly 
rapidly, but would require tracking for appre- 
ciable periods of time. In the Bikini lagoon, 
which is a large body of water, intensities 
above tolerance were measured for almost a 
week, and even nontarget vessels operating in 
water at sub-tolerance levels concentrated the 
radioactive material in their salt water lines 
and on their hulls in sufficient quantities to 
produce intensities above tolerance inside the 
vessels. This feature proved a great nuisance 
following the Baker test at Bikini, but would 
not have been sufficient to provide a serious 
hazard in wartime. However, had the concen- 
trations in water been higher, then a serious 
hazard might have been produced. For exam- 
ple, at Pearl Harbor the volume of water is 
small and there is little exchange of water with 
the outside ocean. Under these conditions the 
water contamination might provide a serious 
problem. 
Material deposited on solid surfaces such as 
the decks of the target ships or the streets of 
a city, downwind of such a detonation would 
be far more serious since it would not be sub- 
ject to any diluting influences. The radioactive 
materials would be strongly absorbed and their 
removal would provide an extremely difficult 
problem. Decontamination of radioactive mate- 
rials is quite different than for chemicals, for 
the former must be physically removed while 
the latter need only undergo some chemical 
reaction. As previously mentioned, the decay 
19 RADIOLOGICAL DEFENSE 
rate of a fission product mixture can be ap- 
proximated by a 1/T law. Thus, the radiation 
from the contamination would at one month be 
about 1/30 that at the end of one day. How- 
ever, if weathering could be neglected, another 
80 months would be required before the radia- 
tion would be reduced by another factor of 30. 
Thus, it is obvious that any area which is still 
dangerous one month after the detonation will 
remain so for long periods of time. At Bikini 
half the target ships still had average top-side 
radiation intensities greater than 1 roentgen 
per 24 hours two weeks after the test. 
As time goes on, the danger from the ex- 
ternal radiation, (i.e. exposure to gamma rays 
from a contaminated surface) will gradually 
become a secondary factor and the internal 
radiation hazard will become of primary im- 
portance. Thus, long-life fission products and 
unfissioned material may be absorbed into the 
human system by inhalation of dust or by eat- 
ing contaminated food stuffs. Under these con- 
ditions, beta and alpha emitters provide the 
most serious radiation hazard. This type of 
hazard may well make large areas unfit for 
continuous occupation but it would not pre- 
clude the use of the area for temporary opera- 
tions provided adequate precautionary meas- 
ures were employed. 
One further point requires mention with re- 
spect to the hazards from an underwater det- 
onation. Unlike the airburst, the radiation 
exposure obtained following an underwater 
explosion is accumulated over a measured 
period of time after detonation. Thus, person- 
nel in the open at a distance of one mile might 
have 30 seconds in which to take cover from 
the advancing radioactive mist. Direct expo- 
sure within this base surge would undoubtedly 
result in eventual death. Moreover unlike the 
airburst, the underwater detonation presents a 
hazard to any person entering the area some- 
time after the explosion has occurred. The ex- 
tent of this hazard will, of course, depend on 
the time elapsed before such reentry is made. 
Thus if reentry into an area with an intensity 
of 150 r/hour were made 1 hour after the det- 
onation, then a lethal exposure of 400 r would 
be obtained in 6 hours and a dangerous expo- 
sure of 100 r in about one hour. 
In order to understand some of the problems 
which are created by a possible underwater 
explosion, it is interesting to consider a hypo- 
thetical attack on one of our cities. First, the 
bomb, fitted with a fuse designed to fire at 
some later date, might be brought in peacetime 
by some innocent looking merchant vessel, de- 
posited on the harbor bottom, and the ship 
could then retire without leaving an inkling of 
the impending disaster. At some later time the 
bomb would be detonated and we would have 
no sure knowledge even of whom our enemy 
might be. Thus, it might be feasible for some 
country apparently on good terms to carry out 
the disastrous attack with little fear of retal- 
iation. Instead, our attack bombers might take 
off to drop their cargoes on some completely 
innocent country. The only method of avoiding 
such a situation is by alert intelligence. The 
need for competent intelligence services in this 
era of atomic warfare cannot be overempha- 
sized. 
An observer on the water front at the time 
the bomb was detonated might be suddenly 
surprised to see a tremendous mass of water 
shoot rapidly into the air and within a fraction 
of a second he would be knocked over by the air 
blast. If this, by chance, did not prove fatal, 
he would soon be engulfed in a driving rain 
and mist. This mist which is loaded with radio- 
active materials would expose him to a lethal 
amount of gamma radiation within a second 
after it reached him. For a mile inland of the 
water front the gamma rays from the radio- 
active rain and mist would probably be lethal 
to nearly all personnel. Few would have time 
to take adequate evasive action and all but a 
few who by chance happened to be in highly 
protected places would be doomed to eventual 
death. 
Further downwind a variety of situations 
might occur. In some sections adequate alarm 
would not be received and these people would 
unknowingly receive serious and in many cases 
lethal exposures to the nuclear radiation. In 
other sectors the danger might be appreciated, 
but because of inadequate training and prepa- 
20 RADIOLOGICAL DEFENSE 
ration, no effective evasive action would be 
taken. Instead, the people might mill around in 
the streets, panic stricken. Instead of an order- 
ly evacuation they would, in many cases, move 
into highly contaminated areas and thereby 
increase their exposure. Thousands would be 
needlessly killed both by the nuclear radiation 
and by panic. The situation would be compar- 
able to a fire in a theatre, except on an urban 
scale. 
Where the advance preparation and training 
had been carried out effectively, the reduction 
in casualties might be considerable. Upon 
receipt of warning, the people should hastily 
descend to a basement and remain in an air 
tight room for as long as feasible. If the people 
can stay relatively well protected until the base 
surge has passed by, a tremendous reduction 
in the total exposure would be obtained. More- 
over, the longer one can avoid venturing into 
a contaminated area, the smaller will be the ex- 
posure. As has been previously mentioned, the 
radioactivity decays very rapidly during the 
first few minutes or hours after the detona- 
tion. Thus, a person moving in a contaminated 
street five minutes after the detonation would 
receive more than twelve times the exposure of 
a person who could remain protected until one 
hour after the explosion. 
Eventually, it will be necessary for all people 
to evacuate contaminated areas. If the planning 
has been adequate, this will be carried out in 
an orderly manner and with a minimum expo- 
sure to the radioactivity. This evacuation will 
be extremely difficult in certain cities. New 
York, for example, has few lines of exit and in 
the event of attack, many of these might be 
blocked off. It will be desirable for the people 
in charge of the evacuation to have, as rapidly 
as possible, an estimate of what localities are 
the most highly contaminated in order to avoid 
traversing them. One method of accomplishing 
this quickly will be by means of aircraft. Planes 
flying over the contaminated area at an altitude 
of 500 or 1,000 feet can make fairly good esti- 
mates of the degree of contamination at the 
surface. Such a survey could be made quite 
rapidly and would provide valuable informa- 
tion to rescue parties. A helicopter carrying a 
loud speaker could be used to direct people to 
uncontaminated areas. 
Once the personnel have been evacuated from 
the danger areas, it will then be necessary to 
send in survey parties to determine the exact 
degree of contamination and what measures 
can be taken to rehabilitate the area. This will 
require large numbers of trained monitors. In 
addition, an adjacent command organization 
will have to be set up to correlate the results 
of the surveys made by the various individuals. 
Without such a command center, it will be 
virtually impossible to reenter or rouse a city 
without extreme danger to personnel. 
One point which should be kept in mind in 
all of these surveys and rescue operations is the 
large number of personnel which will be re- 
quired. The areas to be covered will be large 
and the work of necessity slow. Moreover, the 
attrition in manpower may well be great even 
though no casualties are suffered. It is not 
intended to give here any precise value for a 
threshold or minimum exposure which will 
begin to produce important biological effects, 
since sufficient information is not yet available 
on what this should be. However, for illustra- 
tion purposes only, it might be assumed that 
this minimum exposure will be 50 roentgens. 
Thus, if a monitor in surveying an area, or a 
man in an area subjected to attack, accumu- 
lates 50 roentgens, he will be able to withdraw 
without suffering any ill effects. However, over 
a limited period of time there is little recovery 
or repair from an exposure to nuclear radia- 
tion so that it would be dangerous for him to 
receive any further exposure for a considerable 
period. Therefore, insofar as radiological de- 
fense operations are concerned, this man will 
be of no further use and he will have to be 
withdrawn insofar as possible from any danger 
of additional exposure. This using up of expo- 
sure will thus create tremendous trained man- 
power attrition. Moreover, it will provide a 
serious administrative problem in order to keep 
track of the exposures of large numbers of 
personnel. This would probably be a medical 
responsibility, but in addition, it poses many 
difficulties for the commanding officer since 
he may have a company composed of ten 
21 RADIOLOGICAL DEFENSE 
men having had 50 roentgens and therefore 
unable to enter radioactive areas, 10 men 
with 25 roentgens who would be capa- 
ble of limited operations, and others who 
could carry out normal radiological safety du- 
ties, Eventually it would probably be necessary 
to move all people who had 50 roentgens expo- 
sure into the so-called 50 roentgen company 
which would not be used in radiological defense 
operations. The same procedure would prob- 
ably be followed for intermediately exposed 
personnel. 
Summary 
Airburst atomic bombs will produce lethal 
effects over an area of 2 square miles and 
measurable effects over an area of 7 square 
miles as a result of the prompt gamma radia- 
tion emitted at the time of detonation. The 
residual radioactivity is of little importance 
except in the area close to the center of a low 
altitude explosion. 
In an underwater detonation, radioactive 
fission products and unfissioned material will 
be spread by the cloud and base surge over a 
large area. The gamma radiation from these 
materials will be lethal to exposed personnel 
more than two miles downwind, and serious 
contamination will result at even much greater 
distances. This contamination will provide a 
serious hazard for an indefinite period of time. 
Prompt and intelligent evasive action at the 
time of the detonation will permit the reduc- 
tion of casualties, and orderly evacuation and 
reentry procedures will undoubtedly pay great 
dividends in minimizing the effects. 
22 RADIOLOGICAL DEFENSE 
Figure 1. Air Burst Atomic Bomb Immediately After 
Detonation (Ring on Water Surface Caused by Blast 
Pressure). 
Figure 2. Cloud Produced by Air Burst of an Atomic 
Bomb. 
Figure 3. Column Produced by Underwater Atomic 
Bomb Detonation (10 seconds after detonation). 
Figure J). Base Surge and Mushroom-Like Cloud 
Produced by an Undenvater Detonation. 
23 RADIOLOGICAL DEFENSE 
ESSENTIALS OF INSTRUMENTATION 
Howard L. Andrews, Ph.D. 
Chief, Nuclear Radiation Biology Section 
Laboratory of Physical Biology 
National Institutes of Health 
The detection and measurement of high 
energy radiation depends entirely upon the 
proper use of suitably constructed instruments 
since nature has not seen fit to provide man 
with senses capable of responding to it. With- 
out instruments even intense radiation fields 
will not be recognized until irreparable damage 
has been done. If photographic film and a few 
special methods are excepted, all detecting 
devices are based upon the ionization produced 
in gases by the incident radiation. When an 
ionizing agent enters a gas, it may act on a 
neutral atom or molecule with a force large 
enough to remove one or more electrons from 
the atom. It is most probable that two ions 
will be formed, and so it is customary to speak 
of the formation of ion pairs. The average 
energy loss per ion pair in air is about 33 
electron volts. 
If ions are formed in a gas subject to an 
electric field, they will move in opposite direc- 
tions, the negative ions toward the positively 
charged anode and the positives toward the 
negatively charged cathode. The current flow 
will be extremely small, and special measuring 
devices are required to detect it. Because of the 
mutual attraction of oppositely charged parti- 
cles there is always a tendency for ions to re- 
combine and form neutral atoms. The chance of 
recombination is greater the longer the time 
before the ions reach the electrodes. The frac- 
tion lost decreases with increasing voltage, 
and eventually all of the ions are collected so 
there is no further increase in current. This 
condition is known as saturation, and the max- 
imum current is called the saturation current. 
Instruments for measuring the amount of 
electric charge collected in an ionization cham- 
ber are known as electroscopes and electrom- 
eters. The Lauritsen electroscope is one of the 
most generally useful instruments for radiation 
measurements. The moving system consists of 
two quartz fibers about 5 microns in diameter, 
fused together to form a T. These fibers are 
made conducting with a thin metal coating and 
are cemented to one arm of a metal wire bent 
into an L. When an electric charge is placed 
on this system the mutual repulsion of like 
charges causes the fiber to deflect away from 
the side of the L. This deflection can be ob- 
served in a microscope with an eyepiece scale 
focused on the head of the T. Ions formed inside 
the case will neutralize the charge and the 
fiber will return toward its uncharged position. 
Another useful quartz fiber instrument is the 
pencil type electroscope, or dosimeter. This is 
essentially a Lauritsen electroscope modified so 
that the entire instrument is about the size of 
a large fountain pen. Instruments of this type 
are very useful for measuring integrated expo- 
sures. They can be made with a sensitivity such 
that 0.1 roentgen will produce about one half 
of full scale deflection. 
Ionization chamber instruments vary widely 
depending on the particular type of radiation 
to be detected. Short range radiation is admit- 
ted to the chamber through a suitable window. 
Thin mica or stretched nylon film about 0.0001 
inch thick is satisfactory for alpha particles. 
If beta particles are to be measured, the win- 
dows need not be so thin. When a photon 
enters an ion chamber and is absorbed, high 
speed electrons are produced which travel 
through the gas in the chamber producing ions 
until their kinetic energy is spent. The roentgen 
is defined in terms of ionization in air and 
standard air chambers can be constructed 
which will measure photon radiation properly 
in roentgens. Unfortunately, these chambers 
must be rather large for the photon energies 
regularly encountered. 
A small portable chamber should have the 
same absorption for X- and gamma rays as the 
air in the standard chamber and should also 
24 RADIOLOGICAL DEFENSE 
have the equivalent of the long air paths for 
the absorption of the high energy electrons, 
chamber walls are regularly made of bakelite 
or plastics which contain a high percentage 
of carbon atoms and which absorb much like 
air of high density. Since human tissue is com- 
posed chiefly of carbon, oxygen, nitrogen, and 
hydrogen, such an instrument will simulate 
absorption by the body. Ionization chambers 
designed on these considerations are known 
as thimble chambers. One successful thimble 
chamber instrument is the condenser r meter. 
The condenser r meter is not entirely satis- 
factory for survey purposes. The chambers 
must be charged, left in the radiation field for 
an appropriate time, and then read with the 
meter. If a large contaminated area is to be 
surveyed, the number of chambers required be- 
comes exorbitant. Area surveys require an in- 
strument which will give a steady deflection 
that is proportional to the amount of radiation 
striking the chamber. Unfortunately ionization 
currents are too small to be measured directly 
with portable meters, and it is necessary to 
use other means. It is perfectly feasible to 
measure currents of this order with suitable 
vacuum tube circuits and this is the method 
used in most portable ion chamber survey 
meters. 
Geiger-Mueller (G-M) counters take advan- 
tage of the gas amplification that can be ob- 
tained when high accelerating voltages are 
applied to an ionization chamber. When an ion 
has an energy greater than the ionization 
energy of the gas molecules, it may produce 
secondary ions upon collision. The secondary 
ions formed will in turn be accelerated by the 
electric field and may produce further ioniza- 
tion. This cumulative effect is known as Town- 
send or avalanche ionization. If a total of A ion 
pairs results from one original pair, the process 
is said to have a gas amplification factor of A. 
In practice A varies from about 10 in gas- 
filled photoelectric cells to 108 in some Geiger- 
Mueller counter tubes. At a pressure of 10 
centimeters of mercury, gas amplification can 
be obtained at voltages of 250-1,500 volts de- 
pending on the gas and the tube dimensions. 
G-M counters usually have a cylindrical cath- 
ode from 1 to 10 centimeters in diameter with 
a length from 2 to 10 times the diameter. The 
anode consists typically of an insulated axial 
wire 0.001-inch to 0.005-inch in diameter. 
Assume such a counter exposed to a constant 
amount of radiation, each ionizing particle or 
photon having the same energy. Each ionizing 
particle entering the chamber will produce a 
definite number of ion pairs in the gas, and 
these ions will proceed to the collecting elec- 
trodes where they will be neutralized and will 
produce a pulse of current in the external cir- 
cuit. If now the size of the pulse is plotted 
against the voltage applied to the electrodes, a 
curve similar to that of figure 1 will be ob- 
tained. Regions A and B represent the normal 
ionization chamber working conditions where 
the only ions contributing to the pulse are 
those produced by the original radiation. Over 
region C there is some gas amplification oc- 
curring very close to the central wire. In this 
region the gaseous amplification is quite stable 
for any given voltage and does not depend on 
the number of initial ions present. Thus if the 
voltage is adjusted to a value such that the gas 
amplification factor is 103 and an incident beta 
particle produces 100 ion pairs, the pulse re- 
ceived at the electrode will be 100 X 103 = 105 
ions. Under the same voltage conditions an 
alpha particle producing 105 primary ion pairs 
will yield a pulse of 105 X 103 = 10s ions. Be- 
cause of the rather strict proportionality 
Dr. Andrews received his B.S., M.S. and 
Ph.D. in Physics at Brown University and later 
instructed at that institution. After completion 
of research studies with several organizations 
prominent in the scientific research field he joined 
the staff of the USPHS as a physicist in 1937. 
Since that time he has rendered valuable assist- 
ance to the military establishment at the Bikini 
and Eniwetok atomic tests; in the development 
of Radiological Defense Training Schools; as 
Chairman, Subcommittee on Instruments and 
Monitoring Methods, National Committee for 
Radiation Protection. At present he is a Scientific 
Director in the U. S. Public Health Service and 
Chief, Nuclear Radiation Biology Section, Labor- 
atory of Physical Biology, Experimental Biology 
and Medicine Institute, National Institute of 
Health, Bethesda, Maryland. 
25 RADIOLOGICAL DEFENSE 
between the amounts of initial and total ioniza- 
tion this portion of the curve is known as the 
region of proportionality, and a counting tube 
operating in this region is called a proportional 
counter. A proportional counter can be used 
to measure alpha particles or neutrons in the 
presence of strong beta and gamma radiation. 
If the voltage is raised still further, the gas 
amplification factor will continue to increase, 
of primary ions. This is known as the Geiger 
region and is characterized by gas amplifica- 
tion factors of the order of 108. This is the 
portion of the tube characteristic commonly 
used for counting beta and gamma radiation. 
The Geiger region usually extends over a range 
of about 200 volts. When still higher voltages 
are used, the region of continuous discharge, F, 
is reached. In this region the tube is too unsta- 
ble for useful operation, and care must always 
be taken to keep the tube voltages below the 
continuous discharge value. Actually the tube 
does not go into continuous discharge but 
rather produces a series of closely spaced 
pulses from one initial ionizing event. 
A second type of characteristic curve is help- 
ful in understanding the operation in the 
Geiger region. Assume the tube to be exposed 
to a constant radiation intensity and connected 
to an electronic counting circuit. When the 
number of pulses per second recorded is plotted 
against the voltage applied to the tube a curve 
is obtained similar to that shown in figure 2. 
Figure 1—Ion chamber size versus voltage. 
but in region D the amplified pulses are no 
longer proportional to the number of primary 
ions. A sort of saturation effect begins to enter 
at this point and consequently a few primary 
ions will produce nearly as many total ions 
as are obtained from a large number of pri- 
maries. There is still some difference in final 
pulse sizes however, so this region is known as 
the region of limited proportionality. 
The gas amplification continues to increase 
with further increases in voltage, and region D 
gradually changes to region E where all pro- 
portionality ceases. Here a single ion pair is 
sufficient to produce an amplified pulse of the 
same size as that obtained from a large number 
Figure 2—G-M tube characteristics. 
The associated electronic equipment for re- 
cording the number of pulses will not respond 
to the small pulses produced in the ionization 
chamber region where there is no gas amplifi- 
cation. Consequently the curve will have a 
threshold, A, below which no pulses will be 
recorded. As the voltage is raised and the gas 
amplification becomes appreciable, the most en- 
ergetic particles will be counted, but the weak 
ones will be lost. This is the region of propor- 
tional counting AB. As the gas amplification 
26 RADIOLOGICAL DEFENSE 
continues to increase with voltage, more of the 
less energetic particles will be counted until 
point C is reached. C is the threshold of the 
Geiger region, CD, and here practically every 
particle entering the tube is counted. D is the 
threshold of the continuous discharge region. 
The Geiger region CD is known as the pla- 
teau, and it is obviously desirable for a tube to 
have a long, flat plateau since here the counting 
rate does not depend strongly on the applied 
voltage. To obtain desirable plateau character- 
istics the filling gas and pressure must be 
carefully chosen, and the central wire must 
be free from dust, sharp points or diemarks. 
Oxygen and water vapor are particularly un- 
desirable and must be completely removed be- 
fore filling. Argon is a very satisfactory gas 
and is used in practically all counters. 
Near the central wire a large number of elec- 
trons and positive ions will be formed in each 
avalanche. The electrons have a small mass and 
are already close to the central wire so they 
will move toward it with high velocities and 
will be completely collected by the wire in 10~6 
seconds or less. The positive ions, on the other 
hand, have to travel out of the negatively 
charged cylinder. Since they have compara- 
tively large masses, they move more slowly 
than the electrons. The positive ion cloud will 
reach the cylinder in perhaps 1(H seconds, long 
after the electrons have been collected at the 
wire. 
As a positive ion approaches very close to 
the cylinder, it will pull an electron from the 
cylinder and become a neutral molecule. In 
general the electron will go into one of the 
upper energy levels so the molecule, although 
neutral, will be in an excited state. The mole- 
cule will, however, promptly turn to the ground 
state and in so doing will radiate a characteris- 
tic series of spectral lines. Some of these lines 
will be in the ultra-violet region of the spec- 
trum and consequently will have sufficient 
energy to liberate photoelectrons from the 
metal cylinder. With high tube voltages a single 
photoelectron will be sufficient to start a second 
avalanche and thus the entire process will be 
repeated over and over again. 
It is possible, however, to construct counters 
in which the discharge can be stopped. These 
are known as self-quenching or fast counters. 
A self-quenching counter can be produced by 
adding to the usual filling gas a small amount 
of a polyatomic vapor, such as alcohol or 
xylene. These organic molecules strongly 
absorb ultra-violet light, and by this mecha- 
nism the photoelectric emission at the cathode 
is prevented. Most of the polyatomic molecules 
introduced to make self-quenching counters are 
vapors at room temperature, and these coun- 
ters are apt to show a sensitivity which 
changes with temperature. A further disadvan- 
tage lies in the fact that some of the quenching 
gas is broken down (dissociated) at each dis- 
charge, and so these counters have a limited 
life. A very satisfactory self-quenching counter 
can be made by filling the tube with 10 percent 
alcohol and 90 percent argon to a total pressure 
of 10 centimeters of mercury. With a non-self- 
quenching tube an auxiliary circuit must be 
used to stop the discharge. 
Any counter will give counts when placed in 
a neutron field, but better results can be ob- 
tained with specially designed tubes. To detect 
slow neutrons the counter is filled with boron 
trifiuoride, BF3, which is a gas at room temper- 
ature. Slow neutrons react with the light 
isotope of boron according to the reaction 
SB10 + 0n1 8Li7 + 2He4. This reaction 
liberates a considerable amount of energy, and 
the alpha particle and the recoiling lithium will 
have sufficient kinetic energy to produce heavy 
inoization which will trip the counter. By using 
the counter in the proportional range it is pos- 
sible to obtain a count for each disintegration 
even in the presence of large beta and gamma 
intensities. The reaction probability decreases 
with the neutron velocity so the reaction is not 
efficient for fast neutrons. 
Fast neutrons may be detected through the 
recoil atoms which they produce when they col- 
lide with the gas atoms in the counter. The 
recoil atoms produce intense ionization, and 
hence if the counter is adjusted to the propor- 
tional range, the counter will discriminate 
against beta and gamma radiation. Fast neu- 
tron counters have a rather low efficiency be- 
cause of the low cross section for the collision 
27 RADIOLOGICAL DEFENSE 
process. Neutron counting is complicated by the 
change in behavior with velocity, and the pres- 
ent neutron counters are far from satisfactory. 
None of these devices gives an absolute mea- 
sure of radiation intensities. It is therefore 
necessary to calibrate them in terms of known 
standards. This is not difficult if a gamma ray 
calibration is required in terms of roentgens. 
It has been established by careful measure- 
ments that 1 milligram of radium, in equilib- 
rium with its products and enclosed in 0.5 
millimeters of platinum or its equivalent, will 
produce an intensity of 8.4 roentgens per hour 
at a distance of 1 centimeter. The inverse 
square law can be used to calculate the intensi- 
ties at other distances. Standard y-ray sources, 
properly aged and carefully calibrated, are 
available from the National Bureau of Stand- 
ards. Calibration of X-ray or y-ray measuring 
instruments should be carried out against pri- 
mary standard ionization chambers or carefully 
calibrated secondary standards by a well- 
equipped laboratory such as National Bureau 
of Standards or by a reliable instrument manu- 
facturer. 
In making alpha and beta particle measure- 
ments quite different considerations enter. 
Radioactive materials emit particles in all di- 
rections with equal probability and in general 
a chamber or G-M tube will intercept only a 
fraction of the total emission. For example, if 
the active material is spread in a thin layer on 
the bottom of the chamber, only one-half of the 
ejected particles will reach the gas and produce 
ionization. It is then necessary to calibrate the 
chamber and in terms of a known radioactive 
material. Various members of the naturally 
radioactive series are useful for this purpose. 
Photographic materials are also important 
tools for the measurement of radiation since 
high speed particles and high energy photons 
produce developable images. Although photo- 
graphic films and papers lack the accuracy at- 
tainable in the laboratory by electrical methods, 
they still play an important role in radiation 
measurements. A film is one of the simplest 
detectors of radiation, is small and light, can be 
obtained with a wide range of sensitivity, pro- 
vides a permanent record of exposure, and has 
no complicated electronic circuits to get out of 
adjustment. For many applications these facts 
more than outweigh the disadvantages of film 
processing, the time required to obtain a meas- 
urement, and the variations inherent in photo- 
graphic materials. 
Table I 
Emulsion: 
Type K 0.05 2.0 
Type A 1.0-10 
Cine positive 5301 5-80 
Cine positive fine grain 5302 40-400 
Kodalith 6567 70-700 
Kodabromide G 3 400-8,000 
548-0, double coat 2,000-10,000 
548-0, single coat 5,000-20,000 
Useful sensitivity 
range (roentgens) 
Table I lists a series of emulsions that have 
proved useful for measuring beta and gamma 
radiation. It can be seen that a single emulsion 
will cover an exposure range of about 1-10. 
Photographic film meters are usually made 
into packets of dental film size (11/4 X 1% 
inches) and covered with an opaque wrapping 
to protect the film from visible light. Any com- 
bination of suitable emulsions can be put into 
a single packet. A cross of thin sheet metal 
about 1 mm thick is customarily attached to the 
packet. This absorber is sufficient to stop all 
beta particles so any darkening under the cross 
will be due to gamma rays. The cross also 
serves to enhance the darkening due to gamma 
rays because of the larger number of electrons 
ejected from the metal. The regular wrapping 
is sufficiently thin to permit the penetration of 
all but low energy beta particles. Thus the film 
can be used to measure both beta and gamma 
exposures. 
In general, film processing is carried out in 
accordance with the manufacturers’ recommen- 
dations, but variations may be used satisfac- 
torily. Whatever procedure is used, it is most 
important to control time and temperature as 
accurately as possible. The developer should be 
in a tank surrounded by a constant tempera- 
ture bath, and the films agitated throughout 
development. The importance of time and tem- 
perature control, scrupulous darkroom tech- 
nique, and the use of fresh chemicals cannot be 
overemphasized. 
28 RADIOLOGICAL DEFENSE 
Special emulsions are now commercially 
available which are almost insensitive to visible 
light, beta and gamma radiations, but which 
will respond to heavy particles such as protons, 
deuterons, or alpha particles. These particles 
have such a low penetrating power that the 
emitting substance must be placed in direct 
contact with the emulsion. These emulsions are 
not used for personnel monitoring but rather to 
detect alpha particle contamination. These 
emulsions will detect alpha particles in the 
presence of strong beta and gamma radiation, 
and under conditions that make the operation 
of electrical alpha particle detectors uncertain 
if not impossible. 
With weak exposures the plate will not be 
uniformly darkened and individual alpha par- 
ticle tracks can be seen in a microscope. Since 
alpha particles are emitted with an energy 
characteristic of the emitting nucleus, the track 
lengths may frequently be used to identify the 
alpha emitter. 
The various film emulsions can be used to 
make radio-autographs of specimens containing 
radioactive materials. By exposing sections of 
the specimen it is possible to determine the 
cross-sectional distribution as well. However, 
it must be emphasized that the resolving power 
of photographic emulsions for determining the 
precise position is limited, and it is scarcely 
possible to determine the location of radioac- 
tivity to less than 1/100 mm. 
29 RADIOLOGICAL DEFENSE 
MEDICAL EFFECTS OF ATOMIC EXPLOSION 
Colonel James P. Cooney, MC, USA 
Chief, Radiological Branch 
Division of Military Application 
Atomic Energy Commission 
Medical effects from the atomic bomb may 
roughly be divided into three categories as fol- 
lows : 
1. Trauma 
2. Burns 
3. Radiation Injury 
1. Trauma—inflicted by the mechanical 
force of the explosion, either as blast or indi- 
rect trauma due to flying debris. As in the 
case of the bombing of Britain, the latter was 
much more important. The atomic bomb explo- 
sion differs from an ordinary bomb blast in the 
wide compass of its range. No one was closer to 
the bomb than several hundred meters. At that 
distance the peak pressure must already have 
fallen, and its duration must have greatly de- 
creased in comparison with what it was in the 
center. The explosion did not have the trip 
hammer blow effect of high explosive, but was 
rather like a sudden violent gust of air which 
lasted for a brief but appreciable period. 
Japanese medical observers on the spot could 
not find any cases of direct damage to the in- 
ternal organs by the blast. Necropsy of the 
early cases shows no typical evidence of blast 
damage to the lungs. Many individuals re- 
ported having lost consciousness temporarily, 
with no history of direct trauma to the head. 
Observations of Zuckerman (British report) 
tend to discount cerebral concussion resulting 
directly from the blast. A report shows the 
total of 17 ruptured eardrums at Hiroshima 
and 22 at Nagasaki. According to the British 
investigators there is a great variation in the 
intensity of the blast pressure which will result 
in the rupture of the eardrums in man. In ex- 
plosions where persons were subject to pres- 
sures estimated at between 45 and 100 pounds 
per square inch, less than one-half of a small 
group suffered rupture of the tympanum. The 
drum may, however, rupture under pressures 
as low as 2 to 4 pounds in excess of atmos- 
phere. Facts of acceleration of pressure may 
also be important in determining the incidence 
of blast effect on the biological target. 
a. Indirect effects of blast caused by fall- 
ing walls, flying glass, etc. Windows were 
broken as far away as Kure, 20 km. The 
radius of complete collapse of the wooden 
natives’ buildings was 2.4 km., almost sym- 
metrically distributed about the center. The 
incidence of mechanical injury is about 60% 
between 500 and 1,250 meters. It is only 
beyond 2,700 meters that the incidence of 
mechanical injury begins to fall off rapidly. 
Even at 4,500 meters, the incidence of me- 
chanical injury in the survivor group is still 
14%. Fatal injuries, however, are almost en- 
tirely in the zone of complete destruction. 
Those indoors in heavy buildings, surpris- 
ingly, show a higher incidence of injury 
than those remaining in native Japanese 
buildings. Since most of the injuries were 
inflicted by flying glass and the concrete 
buildings have more glass than those of the 
native type, the explanation of the paradox is 
clear. Furthermore, this ratio of injury ap- 
plies only to non-fatal injuries in survivors. 
It is assumed that the total mortality from 
immediate trauma is higher in the Japanese 
buildings than in the concrete buildings at 
the same distance, the reason being that over 
a wide area of impact the Japanese buildings 
collapsed from blast while the concrete build- 
ings generally retained their structural in- 
tegrity. Exactly how much of the total mor- 
tality was caused by the traumatic factor 
will never be known, because within one-half 
hour following the blast both cities were 
swept by fire before rescue operations could 
be instituted. Consequently, even though me- 
chanical injury was not directly responsible 
for death, it probably contributed vitally to 
30 RADIOLOGICAL DEFENSE 
the actual mortality. This accounts for the 
low incidence of severe forms of injury 
among the survivors. 
The British estimate that a bomb similar 
to the one used at Nagasaki if exploded at 
the same height over a city such as London 
would cause complete collapse of normal 
buildings for a distance of 3,000 ft. from zero 
point, damage all houses beyond repair out 
to a distance of one mile, render houses un- 
inhabitable without extensive repairs up to 
a distance of 11/2 miles, and would render 
houses untenantable without immediate re- 
pairs out to a distance of 2i/o miles. Over 
London the bomb would completely wreck 
30.000 houses, badly damage 35,000 and 
damage from 50,000 to 100,000. Based upon 
a density of population of one person per 
1.000 sq. ft., the bomb would kill 75,000 
people. Compare this with a 500 lb. bomb 
dropped in the same area which would cause 
a mortality of six people and a block buster 
which would cause a mortality of 30 people. 
b. Types and mechanism of injury from 
otie grotty of patients at a military hospital 
were as follows: 
Fractures 11.5% 
Contusions 53.8% 
Lacerations 34.7% 
Flying glass was the cause of the greater 
percentage of lacerated wounds. The frag- 
ments were so small that in many cases 
clothing was sufficient to protect the body. In 
one case at 1,000 meters, the patient was 
struck by glass fragments which, even 
though they did not penetrate his trousers, 
struck with sufficient force to pierce the skin 
of the upper portion of the bared torso and 
produce an injury. 
2. Burns. The burns that occurred may be 
classified as “flash burns”, which are the result 
of the direct action of radiant energy, and 
flame burns. The latter were relatively rare; 
for the reason that it took some time, perhaps 
one hour as stated above, for the fires that 
were started following the blast to spread 
within the city. Consequently, those who did 
not escape were burned to death. 
The radiant energy covered the entire width 
of the spectrum, which resembled that of the 
sun. Let us now consider only the ultraviolet, 
visible light and infra red rays. None of these 
has a high degree of penetration, so that any 
solid object, such as clothing or even leaves, 
was sufficient to produce a shadowing effect 
(outline of the man who was in the direct line 
of rays projected upon the asphalt of Bantai 
Bridge), only surfaces directly exposed to the 
rays were effected by them and thus results 
the so-called “profile” burns. The wood of dark 
colored telephone poles was superficially car- 
bonized at 3,000 meters from the center. From 
the data of Ashe and Roberts, a temperature 
of 4,000 degrees Centigrade acting for approx- 
imately 0.5 seconds is necessary to produce a 
second degree burn. It appears that the in- 
jurious agents causing flash burns were of 
extreme intensity but lasted for a very short 
duration. Burns were remarkably common 
among those indoors, as it was summer and 
many of the windows were open. Burns were 
of no significance beyond 4,000 meters. Beyond 
Col. Cooney was commissioned in the U. S. 
Army Medical Corps in August 1927. He became 
a Diplomate of the American Board of Radi- 
ology December 11, 1939. In February 1946 he 
was assigned to the Manhattan Engineering Dis- 
trict in preparation for the Bikini tests. At 
Bikini he served as personal representative of 
the Surgeon General, U. S. Army and partici- 
pated in all types of radiological safetey oper- 
ations. After Bikini, he was sent on a special 
mission to Japan to make a study of the survivors 
of Hiroshima and Nagasaki. He was then 
assigned as Medical Director of the Manhattan 
Engineering District. Since 1947 Col. Cooney 
has been assigned as Consultant to the Chief of 
the Armed Forces Special Weapons Project and 
served as Chief of the Special Projects Division, 
Office of the Surgeon General, U. S. Army. He is 
currently assigned as Chief of the Radiological 
Branch, Division of Military Application, Atomic 
Energy Commission. During the atomic tests at 
Eniwetok Atoll, Col. Cooney served on the staff 
of Lt. Gen. John E. Hull as Radiological Safety 
Officer. 
31 RADIOLOGICAL DEFENSE 
3,000 meters few burns required treatment. 
Fifty-three percent of the deaths attributed 
to burns died within the first week and 75 per- 
cent of the total within 2 weeks. 
Symptoms associated with the burns varied 
from case to case, but tended to follow a fairly 
definite pattern. In individuals close in, both 
burns and blisters were apparent in five min- 
utes. Further out, in the vicinity of 1,500 
meters, burns appeared in two hours’ time and 
the blisters in from 4 to 6 hours. Within 2,000 
meters, the burns appeared in about 3 hours 
and blisters after an elapse of 10 hours. How- 
ever, in one patient at 2,000 meters there was 
vesiculation within 10 minutes. 
a. Effects of radiant energy upon the eye. 
Direct injuries to the eye were remarkably 
few. Only a few palpebral burns were noted. 
The shadowing effects of the supraorbital 
ridges and the blink reflex helps to explain 
this finding. Almost all of the patients had 
temporary amblyopia which lasted for an av- 
erage of five minutes. A few patients had con- 
junctivitis and kerititis. Only one patient 
with a permanent scotoma from perforation 
of the macula was reported. Two patients de- 
veloped traumatic cataracts following contu- 
sions of the eyeball. A slight reduction in the 
transparency of the cornea was observed in 
some but they presented no subjective diffi- 
culties. One patient was so blinded by the 
flash that he was unable to distinguish light 
from dark for approximately two days but 
he made a complete recovery. 
b. Keloid Changes. Keloid changes ap- 
peared frequently and in many cases were 
extreme. According to the Japanese physi- 
cians, the incidence of keloids is not a char- 
acteristic of race and they attributed its large 
incidence to the extreme temperature. How- 
ever, it has been noted that where skin 
flaps were removed for plastic surgery, heal- 
ing resulted in keloid changes. A follow-up 
of the “keloid problem” is being made by the 
Atomic Bomb Casualty Commission. 
c. Pigmentation and Depigmentation. 
Among the striking features of burn were 
the changes in pigmentation. At a distance 
of approximately 2,000 meters beyond center, 
the pigmentation was extreme and resem- 
bled a walnut stain (Mask of Hiroshima). 
These burns were preceded by an intense 
erythema, which within a few days became 
increasingly pigmented. Surrounding the 
hyper-pigmented area is a sharp border in 
which is found a zone where there is even 
less pigment than normal skin. This zone 
represents an area where some melanophores 
have abandoned to enter the hyper-pigmen- 
ted tissue. This pigmentation began to fade 
only in a few cases at four months and in 
many cases still persists. 
Depigmentation of the exposed skin oc- 
curred in distances less than 2,000 meters. It 
was not necessarily associated with the scar- 
ring of the skin. There is histological evi- 
dence that loss of pigment in the basal layers 
can occur, even though the epithelium of the 
surface is not destroyed. At the margins of 
the depigmentated zones there is found a 
narrow band of increased pigmentation ex- 
ternally to which there is again a vaguely 
defined depigmented border as described 
above. In the area of depigmentation, the 
erector pilorum muscles were not damaged. 
d. Etiology of the burns. Certain features 
of the burns suggest the action of specific 
wave lengths, probably in the ultraviolet 
range. The intensity of the pigmentation at 
2,000 meters and the extreme depigmenta- 
tion without destruction of the skin closer 
to the bomb is certainly an unusual result of 
thermal injury. It must be remembered that 
a relatively small quantity of air intervened 
between the patients and the bomb in com- 
parison with the entire atmosphere and stra- 
tosphere which filters much of the ultra- 
violet from the sun. Gamma rays are not 
responsible for the sharply outlined pig- 
mentary phenomena that has been described, 
since clothing would be no barrier to their 
action. 
e. Protective effect of clothing. Clothing- 
exerted a protective effect depending upon a 
series of inter-related factors that include: 
(1) Distance from the bomb 
(2) Color and shade 
32 RADIOLOGICAL DEFENSE 
(3) Tightness of the clothing 
(4) Thickness and number of layers 
(1) Distances. A khaki uniform, coat 
and shirt worn together, were protective 
beyond 1,500 meters. Closer to the bomb, 
clothes were no protection. In some in- 
stances clothing actually caught fire and 
the resultant flame burns were among the 
most severe that were encountered. 
(2) Color and shade. Darker shades 
absorb more heat than lighter shades. The 
effect of selected absorption in many cases 
was remarkable. At 1,600 meters in the 
case of a white rayon shirt with a pattern 
of dark blue polka dots, 2mm in thickness 
and 1 cm apart, the polka dots were burned 
in the line of the rays but the intervening 
white material was undamaged. Extremely 
interesting is the effect upon cotton cloth 
with flower pattern in a light pink back- 
ground. The flowers were dark red roses 
with leaves of varying shades of green. 
Some of the flowers were entirely burned 
out, others showing only scorching of the 
darker portions of the leaves and petals, 
while the intervening material showed no 
effects. 
(3) Tightness. Where the clothing was 
more tightly stretched over the scapular 
and deltoid regions, burns were much more 
likely to occur. 
(4) Thickness and number of layers. 
The protective effect of the seams and 
double layer effects of the folded over col- 
lar demonstrated the protective effect of 
the thickness of clothing. 
3. Radiation Injury. The pathogenesis of 
the signs and symptoms will first be considered 
and then will follow an outline of the common- 
est clinical syndromes: 
a. Skin. Epilation was frequently ob- 
served among persons who had been close 
to the bomb and who had survived for more 
than two weeks. At 500 meters the incidence 
was approximately 75 percent and fell off 
sharply at 1,250 meters. The time of the on- 
set of epilation reached a very sharp peak 
between the 13th and 14th days after the 
bombing. Peak for males and females coin- 
cided. The hair suddenly began to fall out 
in bunches upon combing or general pluck- 
ing, or it was found in considerable quanti- 
ties on the pillow in the morning. This proc- 
ess continued for one or two weeks and then 
ceased. In most cases the distribution was 
that of an ordinary baldness, involving first 
the frontal and then the parietal and occipital 
regions, and sparing the temporal regions 
and the scruff of the neck. The eyebrows 
and even more so, the eyelashes and beard 
were relatively resistant. In one group of 
patients coming to autopsy, 48 had epilation 
of the head, and 8 of the axilla, 6 of the 
pubic regions, 4 of the eyebrows and 2 of the 
beard. Complete epilation is not necessarily 
correlated with a bad prognosis. On the other 
hand, 14 percent of all individuals who died 
of radiation effect at approximately the 
fourth week had no epilation. It can be as- 
sumed that such cases received some shield- 
ing effect such as concrete buildings, thereby 
filtering out the softer rays, with death 
resulting from the hard penetrating rays 
which have little effect upon the skin. 
Even in severe cases, the hair had begun to 
return by the middle of October and two or 
three months later had fully returned. In no 
case reported was epilation permanent. 
b. Oral and Gastro-intestinal Tissue. In 
some patients, severe nausea and vomiting 
occurred as early as 30 minutes following 
the detonation. In other cases, it did not oc- 
cur until the next day. Thirty-two percent of 
the individuals within the first 1,000 meters 
and 23 percent who were between 1,100 and 
1,500 meters suffered from vomiting on the 
day of the bombing. The incidence fell sharp- 
ly to 6 percent at 2,000 meters. Diarrhea, 
sometimes sanguineous, occurred within the 
first few days in many patients. Membranes, 
similar to the type found in agranulocytic 
angina, occurred throughout the gastro- 
intestinal tract. 
c. Gonads. Histologically, radiation ef- 
fects on the testes were discernible as early 
as the fourth day and were profound in all 
fatal cases who had been within 1,500 meters 
33 RADIOLOGICAL DEFENSE 
of the bomb. It was obviously of interest to 
study the sperm counts in the survivors. Only 
three of the 23 patients studied who had been 
within 1,500 meters had a count in excess 
of 40,000 (lower limit of normal) ; of 39 who 
had been within 2 km, 13 had counts below 
40,000. According to Macomber and Sanders, 
it is unusual for pregnancy to occur if the 
spermatozoa count is below 40,000. Several 
of the patients complained of a loss of libido 
or even loss of potency following the bomb- 
ing. According to the Japanese physicians, 
the return to normalcy has been slower in the 
male than in the female. 
d. Ovaries. Histologically, the ovaries 
showed less striking changes than the testes. 
During the war years in Japan, there was a 
high incidence of amenorrhea, increasing 
from 4.3 percent in 1932 to 12.0 percent in 
1944. In 1944 the incidence among 316 
nurses of the Tokyo Imperial University was 
13.3 percent. According to the Japanese 
gynecologists, this was due to malnutrition, 
overwork, and anxiety associated with bomb- 
ing. Thirty-six percent of the women in 
Hiroshima and 29 percent of the women in 
Nagasaki, between the ages of 15 and 49, 
who were within a distance of 5,000 meters 
experienced menstrual disorders. The major- 
ity of these had one normal period following 
the bomb and had cessation for an average 
of 3 to 4 months. A year later no cases 
complaining of menstrual disorders attribut- 
able to the bombing were found. 
e. Hematopoietic System. In persons ex- 
posed to radiation, the lymphoid and hemo- 
topoietic tissues underwent rapid necro- 
biosis. According to the Japanese, the effect 
on the blood was biphasic. The lymphocytes 
dropped immediately and reached their low 
point in about 5 days. A few days later the 
granulocytes began to drop and about the 
same time the lymphocytes began to recover. 
About the same time the reds began to fall 
and about the end of the third week, in many 
cases, there was a recovery of the lympho- 
cytes with a marked decrease in granulo- 
cytes and an associated anemia. However, 
in some cases as early as five days following 
the bombing white blood counts as low as 150 
cells per cubic millimeter were reported. 
Specimens of vertebral marrow obtained 
after 10 days following the bombing showed 
an almost total loss of myelopoietic tissue. 
f. Hemorrhagic Aspects. Involved in this 
are four factors, namely, platelet factor, 
dietary factor, infection factor, and capillary 
fragility factor. 
(1) Platelet factor. In 14 cases dying 
between the fourth to seventh week, in 
whom platelet counts were available, only 
two were above 60,000 per cubic milli- 
meters. Most of the cases ranged between 
10,000 and 25,000. In all of these cases the 
bleeding time was increased, in some as 
long as 46 minutes. 
(2) Dietary factor. Needless to say, 
vitamin C levels were low. 
(3) Infection factor. Specific bacterio- 
logical data was unsatisfactory. However, 
there were cases of bacteremia demon- 
strated by streptococci and bacilli found 
in freshly fixed tissues derived from the 
bone marrow. 
(4) Capillary fragility factor. Capillary 
fragility was found in individuals at the 
fifth week and at that time seemed to run 
parallel to the white blood count. 
g. Characteristics of the Hemorrhagic 
Phenomena. For convenience these will be re- 
ferred to as purpura. In the skin, purpura 
was almost always manifested in patients dy- 
ing from the third to sixth week, inclusive. 
Its incidence at various distances from the 
center ran almost exactly parallel to that of 
epilation and fell off sharply after 1,250 
meters. Purpuric spots tended to appear at 
about the same time as fever. Their peak is 
between the 16th and 22nd day, some 5 days 
later than the peak of epilation. The hemor- 
rhages are most common in the upper half of 
the body and involved, more particularly, the 
head, face, flexer surfaces of the upper arm, 
and the anterior aspect of the thorax. Asso- 
ciated with their onset, there is an increased 
tendency to bleed from lacerations, fractures 
and burns. Healing of wounds was prolonged, 
coincident with the appearance of radiation 
34 RADIOLOGICAL DEFENSE 
sickness. The growth of granulation tissue 
stopped and no tendency to heal was shown. 
In those who survived, the granulation tissue 
improved following recovery from radiation 
sickness associated with the purpuric spots 
on the skin. After the onset of the purpura 
of the skin, hemorrhages were also found in 
the gingivae and from the rectum, nose, uri- 
nary tract and respiratory passages in that 
order of frequency. The lungs are frequently 
involved in a necrotizing and hemorrhagic 
process. 
4. Clinical Syndrome. Patients who died of 
radiation sickness may be roughly divided into 
three groups as follows: 
a. Patients who died within the first two 
weeks. In this group there is histological evi- 
dence of radiation effects upon the skin, gas- 
tro-intestinal tract, lymphoid tissue, bone 
marrow, gonads or ovaries, but these have 
not been clinically manifested. There was no 
epilation nor purpura. Patients complained of 
nausea and vomiting on the first day of the 
bombing, followed by anerexia, malaise, se- 
vere diarrhea, thirst and fever. Death ensued 
in delirium. Profound leukopenia was pres- 
ent. Temperature records in all these patients 
were remarkably similar. Usually between 
the fifth and seventh days and sometimes as 
early as the third day there was a step-like 
rise in temperature, usually continuing to the 
day of death. The earlier the fever, the more 
severe the symptoms and the poorer the 
prognosis. 
A typical case: A 31-year old petty officer 
of the Japanese Navy was admitted to the 
hospital the night of August 9th. He was 
within 250 meters at the time of the bombing 
and suffered first degree burns of the back, 
neck and chest, contusions of the nose and 
right hand and an abrasion of the left elbow. 
On the 12th of August he began to complain 
of abdominal pain, nausea, anorexia, dizzi- 
ness and diarrhea, which reached a frequen- 
cy of 15 stools a day. At the same time his 
temperature began to rise and gradually con- 
tinued upward until the day of his death, 15 
August 1945. His blood count on 12 August 
1945 was 4.6 million red blood cells and 150 
white blood cells. 
b. Patients dying the third, fourth, fifth 
and sixth weeks or surviving severe symp- 
toms. In this group, the anatomical and clini- 
cal results of radiation attained their acme. 
Epilation is prominent, as is the hypoplasin 
of the bone marrow. The hemorrhagic and 
necrotizing lesions are entirely comparable 
to those seen in aplastic anemia and agranu- 
locytosis, and occur in the gums, respiratory 
and gastro-intestinal tract. Petechiae of the 
skin are almost always present. The sequence 
of symptoms is somewhat as follows: 
In a typical severe case, the first evidence 
of the disease is nausea and vomiting on the 
day of the bombing, followed by a feeling of 
malaise. The patient then begins to improve 
and feels fairly well until about the begin- 
ning of the second week when epilation be- 
gins. A few days later he then again experi- 
ences malaise and a fever occurs, steplike in 
character. At approximately the same time 
pharyngeal pain may appear. Sanguineous 
diarrhea is a prominent symptom. The leuco- 
cytes and platelets reach very low levels and 
there may be an anemia and greatly debili- 
tated condition for a long period. 
A typical case: A twenty-five year old sol- 
dier was at the 104th Garrison, approximate- 
ly 1,000 meters, on the upper floor of a two- 
story Japanese building at the time of the 
explosion. Fragments of glass struck his 
right arm and shoulder, inflicting a laceration 
on the former and contusion on the latter. 
That night he slept in a field but he returned 
to the garrison on the 7th. Between the 10th 
and 14th he worked on the east drill field 
and was able to march 15 km. Epilation 
began on the 20th of August but he continued 
to work. On the 27th he felt feverish and on 
the next day petechiae occurred. He was ad- 
mitted to the hospital on the 30th of August. 
At that time he complained of malaise, head- 
ache and swelling of the gums. He had previ- 
ously had malaise on the day after the bomb- 
ing. The gingivae continued to swell and on 
4 September they were extremely painful. He 
had a sore throat on 1 September and had 
35 RADIOLOGICAL DEFENSE 
dysphagia on the 7th. Superficial ulcerations 
of the angles of the mouth were noted and on 
the next day he had trismus. His temperature 
rose sharply on 1 September and attained 
40.6 degrees Centigrade. On the next day it 
began to fall and reached normal levels on 
the 14th of September, Petechiae began to 
clear on 9 September and he was sufficiently 
well on 4 October to be discharged. He was 
next seen on 23 October by members of the 
Joint Commission who found him at work 
on his farm. At that time he complained only 
of shortness of breath. His white blood count 
had reached 1400 in contrast with a low of 
900 on 4 September. 
c. In some individuals, in whom the bone 
marrow fails to recover, the symptoms de- 
scribed in (b) above continue and the patients 
die after a chronic illness of extreme emacia- 
tion. In others, concomitant with partial or 
complete recovery of the marrow, most of the 
striking manifestations classed as anemia, 
disappear, but they nevertheless succumb to 
the complications such as lung abscess, tuber- 
culosis, etc. 
A typical case: A 31-year old man admit- 
ted to the hospital on 5 September 1945, com- 
plained of epilation, gingival pain and high 
fever. At the time of the bombing he was in 
the military barracks approximately one km 
from the center. At the time he sustained a 
large wound of the occipital region and lac- 
erations of the upper arm and dorsum of the 
left foot. On 25 August the scalp hair began 
to fall out and he began to complain of gingi- 
val pain. At the time of admission his tem- 
perature was 39.5 degrees Centigrade, pulse 
was 102. He was pale and undernourished 
and appeared moderately ill. There was a 
striking degree of gingival hemorrhage and 
ulcers were present on his lips. It was im- 
possible for him to eat on account of pain. 
Epilation was complete but no petechiae were 
seen on the skin. On 15 September, his fever 
increased and his coughing was so severe 
that he was unable to sleep. However, his 
external wounds began to heal. On 14 No- 
vember there was hemoptysis of approx- 
imately 100 cc. On 15 November he was in an 
agonal state and died. His total stay in the 
hospital was 72 days. On the 19th of Sep- 
tember his red blood count was 2.2 millions, 
hemoglobin 36, and white blood count, 3,200. 
On 8 November his red count had descended 
to 1.7 millions but his white blood count had 
increased to 4,300. 
36 RADIOLOGICAL DEFENSE 
Figure 1. 
Figure 2. 
Figure 1. Selective heat absorption effect on cloth. 
The light-colored material is intact. 
Figure 2. The dark portion of the kimono pattern 
is burned into the patient’s skin. 
Figure 3. The skin under areas of contact with cloth- 
ing is burned. The protective effect of seams or thick 
material can be seen on the shoulders and across the 
back. 
Figure 3. 
37 RADIOLOGICAL DEFENSE 
Figure U. Epilation in a Japanese patient following exposure to ionizing radiation. 
Figure 5. Petechia (areas of hemorrhage in the skin) and gingivitis (infection and ulceration of the gums) 
evidenced in a Japanese suffering from radiation sickness. 
38 RADIOLOGICAL DEFENSE 
BIOLOGICAL EFFECTS OF RADIATION 
Lt. Col. Karl H. Houghton, USAF, (MC) 
Chief, Medical Branch, Radiological Defense Division 
Armed Forces Special Weapons Project 
History 
In 1895, while experimenting with cathode 
rays, Roentgen observed the fluorescence of 
some crystals lying at a distance from a 
Crookes-Hittorf tube. It was disclosed that a 
new ray had been discovered which was called 
an “X-ray”. This discovery opened a new field 
of scientific and medical research and first 
brought ionizing radiation to the attention of 
mankind. 
In 1896, natural radioactivity was discovered 
by Becquerel during a study of the fluorescent 
effects of various substances. While working 
with uranium, he found that photographic 
paper was darkened and, more important, that 
the air adjacent to the salts conducted elec- 
tricity and discharged an electroscope. These 
phenomena indicated to him the presence of an 
ionizing radiation, a radiation that was a spe- 
cific property of uranium. In 1898 the Curies 
isolated the naturally radioactive elements po- 
lonium and radium from pitchblende. 
It was soon after the discovery of the X-ray 
that the biological effects of radiation on skin 
were noted. This was the first indication of the 
biological hazards of radiation. Ikcquerel’s 
classical accident was an example. After carry- 
ing a vial of radium in his vest pocket, he dis- 
covered a burn on the underlying skin. 
During the next decade, radiation was used 
extensively as a therapeutic and diagnostic 
measure on almost every known disease and 
frequently with disastrous results. It was not 
until 1903-1905 that the marked sensitivity 
of the blood-forming organs and reproductive 
organs of animals sounded the first warning 
that other than skin effects were occurring. 
Since that time the use of X-ray and radium 
has been approached with more caution as the 
dangers were recognized. 
’The above brief history has been pointed out 
to show that radiation is not a new problem 
introduced by atomic energy. However, the in- 
creased seriousness of the radiation problem 
because of the atomic energy industry and the 
more widespread use of radioactive material in 
the laboratory and in industry has stimulated 
more intense interest in studying the effects of 
radiation and especially the mechanism by 
which radiation produces biological effects. 
Ionization 
The damage or effect of radiation on tissue 
depends upon the absorption of the energy of 
the radiations by the biological material. The 
mechanism of this absorption is called “ioni- 
zation”, hence, “ionizing radiation”. This mech- 
anism consists of a radiation directly or indi- 
rectly striking an atom and dislodging an elec- 
tron with the production of a positively charged 
atom and an electron, which are called “an ion 
pair”. An atom which is in this state is capable 
of entering into abnormal chemical combina- 
tions or of breaking down or synthesizing com- 
plex molecules. 
The different radiations produce ionization 
by different mechanisms. In brief, the charged 
particles, beta and alpha, act directly by apply- 
ing their kinetic energy or electrical forces on 
the neutral atom and dislodge an orbital elec- 
tron. Electromagnetic radiations (gamma, 
X-ray) and neutrons, ionize indirectly by accel- 
erating a secondary charged particle which, in 
turn, produces the ionization. The gamma and 
X-ray photons strike free or lightly held elec- 
trons and impart all their energy to these 
secondary particles which, being accelerated, 
produce the ionization. That process is known 
as the “photoelectric effect”. There are two 
other methods by which photons produce ioni- 
zation, but the results are essentially the same 
and in the interest of simplification, will not be 
discussed. Neutrons ionize primarily by collid- 
ing with nitrogen atoms with the release of a 
39 RADIOLOGICAL DEFENSE 
fast proton or by direct collision with hydrogen 
nuclei (proton) ; here as with gamma rays the 
accelerated secondary particle produces the ion- 
ization. All these radiations have in common 
the production of ion pairs. The ionization 
produced by any type of ray or particle is iden- 
tical qualitatively, but quantitatively they vary 
as we will see later. But regardless of the 
quantitative effects of different radiations all 
radiation absorbed is damaging or of no value 
to the cell or tissue. One hears of stimulating 
doses of X-ray. Actually no such phenomena 
occurs and it is probable that the so-called 
stimulating effect is the response of the tissue 
to damage and is a mobilization of the body’s 
protective mechanism. 
Units of Radiation Measurement 
The damage to tissue is due to the absorptions 
of energy from the radiation. At this time it is 
impossible to measure the exact amount of en- 
ergy absorbed by the tissue, but it is assumed 
that the amount absorbed is proportional to the 
amount delivered within reasonable limits. In 
the measurement of radiation, the unit of 
quantity is the “roentgen” and it is defined as 
“the quantity of gamma or X-radiation such 
that associated corpuscular emissions per 
.001293 grams of air produce in air, ions carry- 
ing 1 ESU of electricity of either sign.” This 
definition is a little difficult to visualize. It can 
be said more simply to be the production of 
1.6 X 1012 ion pairs per gram of air or 2 X 109 
ion pairs per cc of air or the absorption of 83 
ergs per gram of air. The roentgen is a unit of 
absorption so a roentgen of different kinds of 
radiation will not represent the same energy 
flux as those of gamma or X-ray because of 
difference in wave length or absorption coeffi- 
cient. Thus roentgen equivalents have been 
developed which will allow comparisons. One is 
the “rep” which is that amount of radiation 
which produces energy absorptions of 83 ergs 
per cc of tissue. A second is the “rem” which is 
that amount of radiation which produces a bio- 
logical effect equal to that produced by Ir of 
high voltage X-ray (400 kv). The use of the 
latter unit will permit additive radiation doses 
within limits. 
The following is a comparative scale of the 
various units and types of radiations: 
X-rays and gamma rays — 1 r = 1 rep = 1 rem 
Beta rays — 1 rep = 1 rem 
Protons and fast neutrons — 1 rep = 4 rems 
Slow neutrons — 1 rep = 4 rems 
Alpha particles — 1 rep = 10 rems 
Specific Ionization 
As can be seen from the above chart, the 
biological effectiveness as indicated by the rem, 
varies with the type of radiation. As previously 
stated, the biological effect is due to the absorp- 
tion of energy, and the energy absorption is 
manifest by the ionization in the biological 
material. “Specific ionization” is the term used 
to indicate the relative ability of a radiation 
to produce ionization in a short distance and is 
defined as the number of ion pairs produced 
directly or indirectly per unit length of the 
ionization tracks. In general, the biological 
effectiveness increases with the increase in spe- 
cific ionization since more energy is absorbed 
per unit of tissue. This accounts for the state- 
ment that the effects of different types of radi- 
ation are qualitatively indistinguishable but 
differ in their quantitative results. A general 
rule that may be followed is: along the track of 
an individual particle, the specific ionization 
varies directly with the square of the particle 
charge and inversely with its speed. On this 
basis, alpha with its two charges is more ef- 
fective than a proton or an electron. Also an 
electron of high energy would be less effective 
than one of lower energy or less speed in pro- 
Lt. Col. Houghton received his M.D. degree 
from the University of Southern California in 
1936 and following his internship at Letterman 
General Hospital, San Francisco, California, was 
commissioned in the Medical Corps, U. S. Army. 
In August 1949 he transferred to the Medical 
Service, U. S. Air Forces. Col. Houghton has 
been associated with the Armed Forces Special 
Weapons Project since May 1947 and is currently 
the Chief of the Medical Branch, Radiological 
Defense Division, During Operation Sandstone at 
Eniwetok Atoll in the Spring of 1948, he was 
Executive Officer of the Radiological Safety Task 
Group. 
40 RADIOLOGICAL DEFENSE 
ducing specific ionization. When the electro- 
magnetic radiations are considered, their bio- 
logical effectiveness varies with their energy 
and the energy imparted to the secondary elec- 
tron which produces the ionization. This is 
based on the theory of multiple hits or several 
ionizing events in the same cell being required 
to produce biological effects. The probability 
of a radiation with ionizing events scattered 
throughout a long track producing a demon- 
strable effect is less than one concentrating its 
energies in a small unit of tissue. To illustrate, 
the following dosage in roentgen units was 
required to kill mice within three weeks after 
whole body radiation. 
Gamma 2 mev 675r 
X-ray 200 kv 500r 
Fast neutrons 225 rep (90n) 
The figures given for the specific ionization of 
a particle usually represent the average specific 
ionization as the amount of ionization changes 
along a track as the speed decreases, which fol- 
lows the general rule given above. 
Internal and External Radiation 
There are two general methods of exposure 
to radiation which must be differentiated, i.e. 
external and internal. 
External. Here the source of radiation is lo- 
cated outside the body and the radiation must 
pass into the skin and into the deep tissue, de- 
pending upon the type of radiation producing 
the effects. With an external source, radiation 
effect may be stopped by removing the source, 
moving away from the source, or by interpos- 
ing adequate shielding between the body and 
the source. 
Internal. In this case the source of radia- 
tion is taken into the body by ingestion, inhala- 
tion or through a break in the skin. The fission 
products or other radioactive elements are then 
deposited in the various organs of the body, the 
most important being a deposition in the bones 
in close proximity to the bone marrow. When 
radioactive material is fixed in the tissue, it is 
often excreted very slowly and so remains a 
long term source of radiation bombardment 
within the individual. There is no known proc- 
ess to destroy or neutralize the radiation 
source, and methods to speed the excretion or 
shield the fixed material are unsatisfactory. 
The only limiting process, other than excretion, 
is the normal decay rate of the radioactive 
element. 
It might be well to mention at this time other 
units which occur in the literature and in any 
discussion of internal hazards. The physicists 
have defined for you the half-life of a radioac- 
tive element as the time required for one half 
the element to decay. In biology and medicine 
we have two other units: (a) “biological half- 
life”—the time required for one half of the 
material to be excreted, and (b) “effective half- 
life”—the time required to lose one half the 
material by a combination of excretion and 
radioactive decay. 
Tolerances or Maximum Permissible Dose 
Past experience in using X-ray and radium 
for diagnosis and therapy and laboratory ex- 
perience in radiation has developed levels of 
radiation which at least tentatively are consid- 
ered safe to absorb over a long period. This 
has been set at O.lr or 100 mr/24 hrs of gamma 
or an equivalent amount of the other radia- 
tions. The rate at which it is absorbed within 
the daily permissible dose is immaterial. The 
rate of absorption is important, however, when 
considering higher dosage, as you will see later. 
In all industrial processes, an effort is made to 
stay within this tolerance figure. At the present 
time reduction in the permissible dose is being 
considered, especially for women workers, due 
to the greater susceptibility of the female ute- 
rus and ovaries to radiation injury as evidenced 
by animal experimentation. The 100 mr/24 hrs 
is a permissible dose, not a dose that is de- 
sired nor one that should be taken unneces- 
sarily. No more radiation should be absorbed 
than is required for the job. 
The above tolerance is established as an in- 
dustrial and peacetime value. We of the mili- 
tary, however, must keep in mind that in the 
event of war, most values change and specifi- 
cally we must expect that military and defense 
personnel will be called upon by necessity to 
exceed the peacetime tolerance value. Individ- 
41 RADIOLOGICAL DEFENSE 
uals are injured in war by the conventional 
weapons while doing the job that is required, 
and it must be expected in respect to radiation 
that a military tolerance must be developed and 
accepted as one of the risks of warfare. This 
value must be set at a level short of acute 
radiation illness so that the majority of the in- 
dividuals will be able to complete their job or 
mission and at a comparable risk to that com- 
monly accepted by field commanders working 
under the hazards of conventional weapons. 
With regard to internal radiation in peace- 
time or in industry, the goal is no absorption 
of radioactive material. Tolerance levels in in- 
ternal radiation are more difficult to determine 
because of variable biological factors such as 
absorption and excretion and the difficulty in 
measuring the amounts actually fixed in the 
tissues, and also the lack of actual toxicity, 
experience or figures in man. Experimental 
work with these materials must necessarily be 
done with animals and the translation into 
values for man is questionable. The notable 
exception is radium as the result of the histori- 
cal radium dial poisoning cases. The maximum 
allowable figure for radium fixed in the tissue 
is 0.1 microgram. Another element, plutonium, 
has been widely used in the atomic energy in- 
dustry and sufficient work has been done to es- 
tablish the value of 1 microgram as the limit 
of tolerance. 
Lethal Dose. The lethal dose of external ra- 
diation is fairly well established and current 
thinking places the median lethal dose, the dose 
at which 50 percent deaths would be expected, 
at 400 to 450 r or roentgen equivalents and the 
100 percent lethal dose at approximately 700 
to 800 r. It must be remembered that when we 
speak of doses of hundreds of roentgens being 
lethal or causing serious physical damage, we 
are speaking of irradiation of the entire body 
or whole body radiation. Doses up to thousands 
of roentgens may be given to a small confined 
area of the body without causing serious injury 
except to the desired area. 
Observed Biological Effect in the Cell 
The damage which results through the action 
of radiation on tissue takes place in the cell 
or in its immediate environment. The actual 
mechanism by which this ionizing energy 
causes injury is still unknown. Several mecha- 
nisms have been advanced and among them are; 
1. Some chemical exchange which inter- 
feres with the normal interchange be- 
tween the nucleus and the rest of the 
cell. 
2. Changes in permeability of the cell 
membrane. 
3. Production of a toxic substance in the 
cell. 
4. Changes in the intercellular environ- 
ment. 
Intensive work is being done in the experimen- 
tal laboratories in an effort to solve this prob- 
lem. 
After the damage to the cell has occurred, 
some effects can be directly observed by mi- 
croscopic techniques such as: 
Chromosome breaks. 
Clumping of the chromatin. 
Changes in cell division with formation 
of giant cells or abnormal mitosis. 
Increased granularity of cytoplasm. 
Changes in affinity for various stains. 
Changes in motility or function of cell. 
Cytolysis. 
Swelling of the nucleus or of the entire 
cell. 
Less direct physical methods reveal other ef- 
fects, such as changes in the viscosity of the 
protoplasm, or in the permeability of the cell 
membrane. It seems probable that only a small 
fraction of the cellular effects produced have 
yet been observed, and it must be mentioned 
that the above observable effects can result 
from other stimuli besides radiation and a spe- 
cific radiation effect has not been discerned. 
Factors Involving Radiation Effects 
on Biological Material 
Cellular response. A cell is made up of sev- 
eral distinguishable parts which differ in chem- 
ical makeup. As radiation passes through or 
into the cell, all its parts are radiated simul- 
taneously at random and it is not surprising 
42 RADIOLOGICAL DEFENSE 
that many effects can be observed in the same 
cell or groups of similar cells following the 
same dose of radiation. When many-celled or- 
ganisms are radiated, the complexities are in- 
creased by the variation in response of individ- 
ual cells of the same type and of cells of 
different types, and the possibility that in mul- 
ticelled organisms, radiation damage to one 
tissue may produce indirect effects on others. 
Cellular Environment. Changes or alterations 
in the cellular environment may be a direct or 
indirect factor determining the observed cellu- 
lar damage due to ionizing radiation. It is 
known that changes in environment will alter 
the radiosensitivity of the tissue. Cold-freezing 
and anoxemia will decrease the radiosensitivity. 
Changes in the acid base relationship which 
effect the osmosis of the cell membrane will, in 
certain tissues, increase their radiosensitivity. 
Sensitivity of Tissue. Radiosensitivity of the 
tissue means the relative vulnerability of the 
tissue in its normal state to ionizing radiation. 
This sensitivity, within limits, is predictable for 
different types of tissue under the same condi- 
tions of exposure. A general rule can be given 
that is useful as a rough guide; less highly 
specialized tissue (white blood corpuscles and 
reproductive cells) are more sensitive than the 
highly specialized tissues (brain, nerve cells). 
Further, the rapidly multiplying or actively 
reproducing tissues are more sensitive than 
those in a more quiescent state. This is par- 
tially the basis for use of radiation in the treat- 
ment of new growths or malignancies. The 
tumor suffers greater radiation damage than 
the surrounding normal tissue. Without detail, 
the following may be accepted as a list of the 
common tissues in order of their decreasing 
radiosensitivity: 
Lymphoid tissue, bone marrow, blood 
lymphocytes, lymph nodes, Peyer’s 
patches. 
Polymorphonuclear leukocytes. 
Epithelial cells. 
Gonads and ovaries. 
Salivary glands. 
Skin and mucous membrane. 
Endothelial cells — blood vessels and 
peritoneum. 
Connective tissue cells. 
Muscle cells. 
Nerve cells. 
Species Sensitivity. One of the peculiarities 
of radiation is the wide variation in response 
of different species to identical doses of radia- 
tion delivered under the same conditions. An 
example of the variation can be seen in the 
different values of the median lethal dose for 
animals exposed to 200 kv X-ray: mice, 500r; 
guinea pigs, 250r; rabbits, 875r. This species 
difference is troublesome since by necessity we 
must use animals in the exploration of radia- 
tion effects, and it is not always possible to 
apply the results, other than qualitatively, to 
man. As in all biological work, and especially 
so in radiation because of the variation in re- 
sponse even within a species, it is impossible to 
measure effects of a single specimen but all 
results must be measured by statistical 
methods. 
Intensity of Radiation. Another factor which 
must be considered in discussing the biological 
effects of radiation is the influence of rate of 
delivery on the final results. It can be summa- 
rized in three categories: 
a. Many effects are produced independent 
of the rate of delivery of the radiation. These 
are the so-called cumulative or additive ef- 
fects. The total dose is the important value. 
Among these are genetic effects and the in- 
fluence of radiation on the development of 
uterine tumors in mice. 
b. In a few instances it has been reported 
that the effectiveness of radiation has been 
increased by the decrease in rate of delivery. 
This is explained on the basis of an increase 
in radiosensitivity of tissue under prolonged 
radiation. 
c. In most instances, the biological effec- 
tiveness of a given dose decreases as the rate 
of exposure decreases. This is explained by 
the theory that the radiosensitivity of the 
tissue decreases under prolonged radiation, 
but it is more easily explained by assuming a 
recovery factor of the tissue. If, however, the 
intensity or rate of delivery is increased, 
recovery falls behind the damage and an in- 
43 RADIOLOGICAL DEFENSE 
crease in effectiveness of a dose is apparent. 
It is this recovery factor or decreased effec- 
tiveness of low intensity exposures which is 
important to industrial workers suffering 
daily exposure. If all effects were cumulative, 
it would be impossible to operate under such 
a low tolerance value as 100 mr/24 hrs. 
Reversibility of Effects. Tissue which has 
been damaged by radiation follows the same 
general rules as tissues damaged by other stim- 
uli. Those tissues which are incapable of repro- 
ducing functional cells after destruction will 
not recover from radiation damage except by 
the formation of scar, i.e. muscle, brain and 
portions of the kidney and eye. Those which 
normally regenerate functional cells will re- 
cover. This, of course, is dependent on the total 
amount of radiation absorbed, there being a 
level of damage in all tissues at which recovery 
is impossible and tissue is replaced with scar. 
It must be remembered that tissues receiving 
repeated damage by radiation may not recover. 
If extensive damage has been done to a tissue 
by radiation, a repetition of this injury must be 
avoided if a functional result is to be obtained 
or if the possibility of malignancy is to be 
eliminated. 
Distribution and Penetration of Radiation. 
In all our discussions on the effects of the atom- 
ic bomb, we are speaking in terms of whole 
body radiation and not localized radiation as is 
used in therapy. 
We have already discussed the biological ef- 
fectiveness or specific ionization of the various 
rays and particles. Penetration of the radiation 
must be considered in evaluating the biological 
hazard. To produce their effects, regardless of 
their ionizing ability, they must reach tissues 
which can be damaged. Alpha particles (heavy 
charged particles) are highly ionizing, but their 
range of action is limited by their poor pene- 
tration in tissue (approximately .1 mm). This 
practically eliminates alpha particles as an ex- 
ternal hazard as they may be shielded with a 
few pieces of paper or the squamous portion of 
the skin. It is only when they are deposi- 
ted internally in vulnerable organs such as 
the bones that severe damage due to the 
highly ionizing ability becomes apparent. Beta 
particles have a similarly poor penetration 
quality (approximately 5 to 10 mm in tissue) 
so may be rated as an internal radia- 
tion hazard. However, they do have a strong 
caustic effect on the skin at short distances so 
must also be considered as an external hazard. 
High energy gamma rays and X-rays have a 
much less degree of ionization than alpha par- 
ticles. But their ability to penetrate and reach 
the deep tissues makes them the major external 
radiation hazard. The penetrating ability of 
neutrons is somewhat less than that of gamma 
and their ability to ionize is from 5 to 10 times 
as effective as gamma so they may be classified 
as a serious external hazard. 
Acute and Chronic Radiation 
Acute radiation injury must be separated 
from chronic in any discussion of radiation 
hazards. The acute results from dosage produc- 
ing an effect that can be determined by clinical 
and laboratory examination. It results from 
doses approaching 50 r. Acute radiation sick- 
ness is a clinical entity which will not be dis- 
cussed in this lecture. Chronic effects resulting 
from dosages ranging from so-called tolerance 
levels to approximately 10 to 20 r per day are 
the subject of intensive research but little data 
on man is available. The results of animal ex- 
perimentation must suffice because of the un- 
suitability of exposing humans to this hazard. 
The predominant effects expected of chronic 
radiation are shortening of the life span, pre- 
mature aging, production of malignancies, 
skin changes from beta, soft gamma, and 
X-ray, and genetic injury. It must be remem- 
bered that the above effects are the result of 
repeated and prolonged radiation, not to be ex- 
pected from occasional exposure over the tol- 
erance dose. Most of the evidence now avail- 
able on these injuries has been obtained from 
injuries of radiologists and industrial X-ray 
workers. It is worth repeating again that the 
chronic effects of radiation are due to pro- 
longed or repeated insults to the tissue and not 
occasional mild or moderate overexposures. 
Blood Changes 
The blood is a factor mentioned as an index 
of radiation exposure. This is in line with the 
44 RADIOLOGICAL DEFENSE 
high radiosensitivity of lymphoid tissues and 
the bone marrow. Off hand, one would assume 
that observations of the blood count and injury 
to the blood forming tissues should reflect ra- 
diation damage. This is true for severe over- 
exposure. Alteration of the blood picture may 
be observed a few hours after overexposure to 
whole body radiation. This alteration is seen 
as a reduction in the white blood cells and in 
very severe overexposure, a reduction in the 
red count. However, in low grade overexpo- 
sures or those exposures in the neighborhood 
of the tolerance value, the blood count is not a 
reliable index when considered independently. 
The daily normal variations, existence of unob- 
served low grade infections, and variations in 
counting technique are among the factors re- 
ducing its reliability in measuring the relative 
small variations to be expected. A count on an 
individual exposed to frequent radiation show- 
ing a reduction, even when compared to the 
individual’s previously established normal, is 
not a positive indication of radiation injury 
and must be evaluated with other physical fac- 
tors. Importance can be attached to the reduc- 
tion only if the individual is a member of a 
group exposed to the same radiations and all 
show the same variation. That would possibly 
indicate an overtolerance exposure to radiation 
for the group. 
Reproductive Organs 
The elements of the reproductive organs 
which are injured by radiation are the pro- 
generators of the adult germ cell. High intensi- 
ties of radiation or prolonged radiation will 
cause a complete destruction of the germ cell 
producing tissue. Permanent sterility can be 
produced in the male with a dosage in the 
neighborhood of 800 r and in the female of 
600 r. Temporary sterility is produced at lower 
dosages and as for the Japanese casualties who 
survived large doses of whole body radiation 
and were sterile, the majority have recovered. 
It is somewhat of a paradox that among the 
female casualties a higher percentage has re- 
covered and at a faster rate than the male. The 
differences between sterility and impotence 
must always be kept in mind when speaking 
to the laymen about radiation effects or more 
specifically, effects from the atomic bomb. Con- 
fusion does exist in their minds and they can 
be assured that impotence is not a result of 
radiation and is a separate and distinct entity 
from sterility. 
Genetic Injury 
Genetics is a complicated science rarely con- 
sidered by the average medical man. In radi- 
ation, however, it is constantly mentioned as a 
hazard and no discussion of radiation injury is 
complete without the mention of genetic injury. 
A factor which probably causes the most con- 
cern is that accumulative dosage without re- 
gard to rate or energy produces the effects. 
Further, it is thought that only one ionizing 
event is sufficient to cause a change in the gene 
rather than multiple hits or several ionizations 
as is considered necessary to produce the 
majority of the biological effects. Little is 
known of the actual effects to be expected in 
man because of his long life span, small num- 
ber of offspring, and the difficulty of controlling 
long-term experiments. The information most 
quoted has resulted from studying the fruit fly 
and various species of fish. Thirty or 40r is 
sufficient in the fruit fly to produce demon- 
strable increases in mutation rates. Approxi- 
mately 500 r are required to produce similar 
changes in mice and it is estimated that 600 r 
would be required to produce significant 
changes in the mutation rate in man. 
The gene is a germinal factor present in the 
chromosomes which carry the hereditary char- 
acteristics. There are two types, the dominant 
and the recessive. The recessive requires a like 
gene or a like contribution from both parents 
for expression in the offspring. A dominant 
gene will be expressed in the direct offspring 
regardless of the other parent. Mutations are 
the changes in the characteristics of a gene. 
It is these mutations that produce abnormali- 
ties in the offspring which may be either dele- 
terious or beneficial to the race. They occur 
naturally and under artificial stimulation. Radi- 
ation will produce mutations. As stated before, 
mutations in dominant genes may be detected 
45 RADIOLOGICAL DEFENSE 
in the next generation while those in recessive 
genes may go undetected for generations. 
Fortunately, the majority of the natural and 
artificial mutations are recessive and require 
a similarly abnormal gene for expression. The 
one exception to the general rule of recessive 
requiring a like recessive for expression is the 
sex linked genes carried by the female sex cell. 
Because the male does not carry a similar gene, 
they act as a dominant and abnormalities in 
that gene will be apparent in the next genera- 
tion. 
Mutations in man, whether spontaneous or 
artificial, are about 95 percent lethal or sub- 
lethal which means that the offspring will die 
during gestation or shortly afterwards. Of the 
viable mutations (5 percent of all mutations) 
about 95 percent are deleterious. Of these, 
about 96 percent pertain to other than sex 
chromosomes. The subject of genetic changes 
and the production of a race of monsters in 
Japan as the result of the atomic bombings has 
received a large amount of publicity in this 
country. Actually, no such disaster is con- 
templated by geneticists. The National Re- 
search Council and the Atomic Energy Com- 
mission, through an organization called the 
Atomic Bomb Casualty Commission, are run- 
ning a long-term study in Japan to determine 
if possible any evidence of genetic changes. 
The fact of survival indicates that probably 
less than 400 r had been absorbed which is 
considered too low a dosage for genetic changes 
to appear in man except for the changes which 
may appear in the sex linked genes in females 
or those that appear with lower doses in any 
statistically measured effect. Ordinarily, more 
males are born than females and in Japan they 
expect possibly to find an increase in the male 
mortality rate and as a result, a change in the 
male-female ratio to approximately 1 to 1 or 
possibly a slight increase in the number of fe- 
males. The number of survivors in the repro- 
ducing age group which were in that border 
line zone of high dosage but survived, is rela- 
tively small when considered against the total 
population of their city and would be produc- 
tive of low demonstrable genetic changes. 
46 RADIOLOGICAL DEFENSE 
FUNDAMENTALS OF RADIATION PATHOLOGY 
Colonel Elbert DeCoursey, MC, USA 
Commandant, Army Medical Department Research and Graduate School 
Army Medical Center, Washington, D. C. 
The qualitative biologic effects of alpha, beta, 
gamma, X-ray or neutron radiation are ap- 
parently the same, the degree and localization 
of ionization being the basic factors. Energy is 
released in the cells by the formation of ion 
pairs. Grossly and microscopically only de- 
structive effects are seen. I have not seen evi- 
dence of ionizing radiation effect that has been 
primarily stimulating. 
According to Dr. Shields Warren, “alpha 
particles are about 100 times as effective in in- 
juring cells as beta rays. Both are less pene- 
trating and more destructive than gamma rays 
(hard X-rays of supervoltage) ”. This is in 
close agreement directly with their ionizing 
powers (10,000; 1,000; 1) and inversely with 
their ranges. Neutrons are apparently about 
eight times as potent biologically as physical 
equivalent amounts of roentgen rays. 
Not the reading of an ionization chamber 
but the amount of radiation absorbed and the 
rate at which it is absorbed determine the ef- 
fect on tissue. Thus well filtered radiation (say 
at 1000 KV of 500 r dose) will give a much 
greater dose in a field 10 X 10 cm. in tissue 10 
cm. thick (with not even erythema of skin) 
than in a 3X 5 cm. field. The same dosage over 
the entire body would be lethal. 
Not all cells of an irradiated area are ion- 
ized. The discontinuous state of matter and of 
energy is an important consideration. Crowther 
has suggested that if a c.c. of air were irra- 
diated at 1 r/sec. for 500 years, only one-third 
of the air would be ionized. This viewpoint is 
basic when considering ionizing effect on tissue 
either for intended therapy or from accidental 
or martial injury. 
External or internal radiation differs in effect 
only as to location of the source and range, or 
penetrating power, of the type of energy (beta, 
gamma etc.). Total body irradiation from 
an external source will be the most important 
part of this discussion and its effects are quite 
different on the integrated organism from the 
effects of localized irradiation. When the source 
of internal radiation is in the blood stream, 
then the effect is that of total body irradiation. 
In internal radiation the physiologic action of 
the chemicals determine their localization in 
the body after absorption through the respira- 
tory, gastrointestinal or integumentary sys- 
tems. This, therefore, determines the location of 
the source of radiation from those chemicals 
that may be radioactive. That radioactive iso- 
topes are handled no differently physiologically 
by normal cells than stable isotopes, is an ac- 
cepted concept. For example, strontium acts 
like calcium and quickly localizes in bone. When 
absorbed from an aerosol, about 95 percent of 
the strontium disappears from the lungs in an 
hour and 60 percent localizes in bone within 
four hours. Thus the radiation effect of aerosol 
Sr89 (t/2, 55 days) after twelve hours is 
greater on the skeleton than on the respiratory 
tract. (Strontium, which is a strong, ordinary, 
chemical poison, has meanwhile occupied the 
blood stream.) On the other hand, 90 percent 
absorption of other bone localizers such as zir- 
conium, yttrium and cerium aerosols is meas- 
ured in days or weeks; therefore the lungs 
receive most of the radiation from such 
radioactive aerosols (MDDC-248). 
Injury from radiation may not be immedi- 
ately apparent. Some changes appear early and 
others may appear only after a latent period. 
Evidence of injury may not appear for months 
or even years. The progress of irradiation 
changes may be slow, continuous and of long 
duration. Within a half hour after onset of 
rather intense radiation, a decrease in mitotic 
activity may be apparent. Phagocytosis stops 
within a few hours. Mitosis is almost absent up 
to twelve hours, and occurs again after about 
18 to 24 hours. Abnormal mitosis are most 
47 RADIOLOGICAL DEFENSE 
common during the second, third and fourth 
days. The blood lymphocyte count is percep- 
tibly decreased in the first few hours following 
total body dosage. Oxygen consumption of tis- 
sues is decreased. 
Edema, erythema (vascular dilation), in- 
creased mucus secretion, and perivascular 
round cell infiltration appears within a few 
days. Later changes are telangiectasis, fibrosis, 
atrophy, vascular occlusion and ulceration. Re- 
peated irradiation necessitates long continued 
regeneration that may lead to neoplasia, such 
as skin carcinoma, fibro-sarcoma, osteogenic 
sarcoma, lung carcinoma, and leukemia. 
Fingerprint changes have been studied by 
Harvey and by Nickson. In 68 percent of radi- 
ologists, 55 percent of orthopedic surgeons 
using the fluoroscope and 40 percent of dentists 
who hold films, there was atrophy of finger 
ridges. The number of capillaries in nail fold 
areas seems to be correlated with hand radia- 
tion so that in young individuals capillaries 
seem to simulate those of old age. Flattening 
and atrophy of ridges, atrophic fissures perpen- 
dicular to ridges and epithelial proliferation are 
found on chronically exposed fingers. Acute 
radiation of 800 to 1100 r in monkeys resulted 
in temporary atrophy only. 
According to either the “poison” or “target” 
theories, changes in tissue components may be 
on the basis of the following factors: freeing 
of H and OH ions, the so-called activation of 
water; release of poisons from decomposed pro- 
tein of cells; interference with enzyme systems, 
especially those with sulfhydryl (SH) groups; 
large molecule changes; and direct hits of ion- 
izing particles on cell structures. Lesions also 
may be secondary to systemic changes such as 
radiation leukopenia. Cellular, intercellular and 
vascular changes are most important. 
Cellular changes may consist of alteration of 
function, chromosomal alteration that effects 
subsequent progeny, or necrosis. Alteration in 
cell function may be seen in the loss of motility 
by granulocytes or the loss of motion of epi- 
thelial cilia. 
The enzyme ribonuclease is inhibited by ra- 
diation. The basophilic stain in cell cytoplasm 
results from the ribose nucleoprotein present. 
Ribonuclease aids in the change from ribose 
nucleic acid to desoxyribose nucleic acid which 
forms the nuclear chromatin, and an excess of 
which must be present for mitosis to occur. 
This may be an explanation why one sees de- 
creased numbers of mitotic figures, after irra- 
diation. There are also mitotic figures showing 
fragmented chromosomes, lagging chromo- 
somes, complete or partial adhesion of chromo- 
somal pairs, asymmetry and/or tripolarity or 
Y-shaped figures. Mitotic injury has been 
divided into three stages: (1) “the immediate 
stage with inhibition of mitoses, pseudo- 
amitosis and pyknosis; (2) the intermediate 
stage, during which mitotic activity is practi- 
cally absent; (3) and the later stage during 
which abnormal or multiple nuclei are formed 
as a result of a division of nuclei whose chro- 
mosomes have been injured.” In a previous 
course Lt. Col. Carl Tessmer has listed the 
following miscroscopic changes that may be 
seen following radiation: (1) changes in stain- 
ing characteristics, usually an increase in eosi- 
nophilic properties; (2) increased granularity, 
usually of cytoplasm; (3) vacuolation of a vari- 
able degree; (4) swelling of cellular compo- 
nents; (5) distortion of cellular structures; 
(6) cytolysis (loss of definitive borders) ; 
(7) pyknosis; (8) changes in Golgi’s appa- 
ratus; (9) reduction in mitotic activity; (10) 
production of abnormal mitoses; (11) chromo- 
somal changes (fragmentation, clumping) ; and 
Col. Elbert DeCoursey received his A.B. degree 
from the University of Kentucky in 1924 and 
M.D. from Johns Hopkins Medical School in 1928. 
He was commissioned in the Medical Corps of the 
US Army in 1928. Since that time, he has spe- 
cialized in pathology and became a Diplomate of 
the American Board of Pathology in 1936. In 
1945, Col. DeCoursey became a member of the 
Joint Commission on the Investigation of the 
Effects of Atomic Bombs in Japan, He was a 
member of the Naval Medical Research Section 
and the Radiological Safety Section at Bikini. 
He is now the Commandant of the Army Medical 
Department Research and Graduate School at 
the Army Medical Center, Washington, D. C. and 
Consultant to the Division of Biology and Medi- 
cine, U. S. Atomic Energy Commission. 
48 RADIOLOGICAL DEFENSE 
(12) increased refractile neutral red staining 
bodies within leukocytes seen by vital staining 
methods. 
Different types of cells differ remarkably in 
radiation response. Cells in mitosis are much 
more sensitive than resting cells. There is a 
common assumption that more primitive cells 
are more sensitive. Lymphocytes are more sen- 
sitive than the specialized neuron. That this is 
not a consistent rule is evidenced by the high 
resistance of the giant ameba and the high 
sensitivity of specialized ciliated epithelial cells 
of the bronchus (of mammals), and the greater 
sensitivity of older over primordial ova and 
probably of spermatocytes over spermatogonia. 
Cells organized into a structural entity are 
more sensitive than when alone as in tissue 
culture. When the cytoplasm is involved, the 
effect is slight but when the nucleus is involved 
the effect is apt to be lethal. A large cell with 
much cytoplasm will be more resistant than a 
small cell with a large proportion of nuclear 
material. 
Intercellular changes vary from slight alter- 
ation to necrosis. Collagen fibers at first seem 
to be separated by edema, then become swollen 
and fuse into wide bands; later there is in- 
creased collagen which becomes homogeneous. 
The elastic fibers swell, fray and may be in- 
creased or decreased in amount. 
Vascular changes range early from thrombo- 
sis to endothelial swelling and later from telan- 
giectasia to partial or complete occlusion. 
Changes in irradiated blood vessels play a most 
important part. Arteries and veins show 
changes in all layers. The endothelium early 
swells and later proliferates sometimes to near- 
ly fill the lumen; then there may be edema of 
the wall and decrease in the number of smooth 
muscle cells. The elastica is distorted or dis- 
appears. Sometimes the endothelium shows ne- 
crosis followed by thrombosis which in small 
vessels results in occlusion. The late changes of 
complete or partial occlusion from thrombosis 
or endothelial proliferation, and of telangiec- 
tasia in superficial vessels appear after several 
wreeks. The collagen of the media shows its 
usual proliferation and hyalinization; this may 
require years. The lesions are slowly progres- 
sive. There seems to be increased capillary 
permeability. Secondary nutritive changes in 
such a vascular bed may be profound. 
All three factors, cellular necrosis, dense 
stroma and vascular deficiency result in the 
X-ray ulcerative lesion. This unfavorable envi- 
ronment along with the changed heredity of the 
newly formed cells discourages healing of the 
ulcer. 
Not only are responses of tissues to various 
types of ionizing radiation qualitatively simi- 
lar, but also are individual tissue effects to 
other stimuli similar. For instance, lipoid ve- 
hicles of injected drugs may produce abnormal 
mitoses; heat of cauterization may produce 
hyaline collagen; and many physical and chem- 
ical agents produce vascular damage. A com- 
bination of such changes, such as giant and 
irregular nuclei, hyaline collagen and thick 
hyaline blood vessels, however, are strongly 
presumptive evidence of radiation effect. 
Relative radiosensitivities of various body 
tissues are fairly well established, but there are 
differences depending on whether the dosage is 
single, intermittent, localized, or total-body. 
We are mostly concerned with a single dose of 
total-body radiation. From the most sensitive 
tissue, lymphocytic (erythrocytic as judged by 
Bloom & Bloom), approximately decreasing 
sensitivity is shown by granulocytic tissue, 
then testis, gastrointestinal epithelium, skin, 
ovary, fibroblasts and their products, bone of 
adults, pancreas, liver, kidney, heart and stri- 
ated muscle, and nerve tissue. 
Skin: Definite changes appear within 48 
hours and more appear later. From sufficient 
dosage erythema is seen in two or three cycles, 
the first wave being between 1 and 4 days, the 
second wave between 8 and 28 days, and a 
third wave between 34 and 51 days. The early 
effects are directly from radiation, the later 
being largely secondary. Immediately epithelial 
mitoses decrease, the vessels dilate and inflam- 
matory cells begin to infiltrate the cutis. Dur- 
ing the second cycle there is desquamation of 
the stratum corneum, occasionally thickening of 
the granular layer, edema and vacuolation of 
the prickle and basal cells and of the upper 
cutis, all of which is usually followed by pig- 
49 RADIOLOGICAL DEFENSE 
mentation. Collagen fibers swell, homogenize, 
and later proliferate to form a dense hyaline 
mass. Later the epidermal edema becomes in- 
tercellular, the basal layer degenerates and 
contains increased pigment, and near the edges 
of the irradiated area chromatophores are 
darker. There is an inverse relationship be- 
tween the amount of sulfhydryl (SH) present 
and melanin pigmentation. The infiltrate is in- 
creased through the cutis and around the hair 
follicles, sebaceous glands and sweat glands, 
which have shown changes in the order listed. 
Epilation appears about the third week. Folli- 
cles show cessation of mitoses, vacuolation of 
cytoplasm and sometimes necrosis. Chronic 
radio-dermatitis is characterized by hyperkera- 
tosis, acanthosis, sparse or absent hair follicles 
and brittle and deformed nails in the hypertro- 
phic type or in the atrophic type the skin is 
shiny, scaly, thin, and spider telangiectases are 
prominent. The epithelium and cells are thin, 
abnormal and disarranged, and the rete pegs 
are flattened. Lack of secretions from the ab- 
sent glands keeps the thin, scaly, irradiated 
epidermis dry and harsh. Trauma easily results 
in ulceration, and the ulcer then tends to per- 
sist for years. It is the regenerative edge of one 
of these ulcers that tends to become carci- 
nomatous. The superficial vessels are telangiec- 
tatic and the deeper ones are in various states 
of degeneration. The corium is a dense hyaline 
mass of collagen. Areas of fibrin may appear in 
this otherwise old process as evidence of slow 
progression. 
Lungs: The initial changes are similar to 
those of skin. More cells appear in the alveolar 
walls giving a picture of pneumonitis, the alve- 
olar lining proliferates and irregular cuboidal 
cells appear. Hyaline membranes may form in 
the alveoli. Elastic fibers become numerous. 
Large doses lead to progressive fibrosis. 
Gastro-intestinal Tract: The intestine has 
seemed about twice as sensitive as the stomach. 
The epithelium first shows edema, hyperemia, 
increased secretion, the reaction being estab- 
lished after about four days and reaching a 
peak, with ulceration, in one or two months. 
The epithelial cells may show early edema and 
decreased mitoses, then swollen nuclei with 
heavy stained chromatin and other atypical 
regenerating cells. Mucinous degeneration may 
be striking. The usual edema, hyalinosis and 
giant fibroblasts are seen in the connective 
tissue. 
Urinary Tract: In the kidney large doses 
may give extensive tubular degeneration and 
interstitial fibrosis, hyalinization and atrophy 
of glomeruli and thickening of Bowman’s cap- 
sule. Later the organ appears small, has a thick 
capsule and shows dense hyaline interstitial tis- 
sue. The sensitivity is less than skin or liver 
but more than muscle or nerve. The ureter and 
bladder are relatively resistant but late ulcers 
may appear in the latter. 
Gonads: In the ovary matured or maturing 
follicles are more sensitive than primary folli- 
cles. Treatment of ovaries in young adult by 
500 r will temporarily sterilize. Edema, hemor- 
rhages and later fibrosis occur. Corpora lutea 
are most resistant. The ovary, for destruction 
of function, has seemed to require about twice 
the dosage that is necessary to produce asper- 
matogenic testes. 
In the testes, rats have shown necrosis of 
first order of spermatocytes on the third day, 
and vacuolations of the Sertoli cell cytoplasm 
during the latter half of the first week. The 
Leydig cells may show apparent increase with 
the tubular atrophy. There is variation in the 
sensitivity of different species. 
Endocrines: The adrenal cortex is fairly 
sensitive but recovers soon. The minimal 
changes are difficult to interpret microscopi- 
cally. The weight increased surprisingly in rats 
after lethal radiation, adrenal cholesterol was 
decreased, and irradiated animals whose adre- 
nals were protected had lower mortality than 
controls (Graver 1947). 
The thyroid, pituitary, and pineal glands are 
fairly resitant. 
Eye: Conjunctiva, cornea and iris are radio- 
sensitive in that order. Radioconjunctivitis ap- 
pears quicker than the dermatitis and during 
the third week usually becomes mucopurulent 
along with keratitis and bleaching or hyper- 
emia of the iris. The epithelium reacts as does 
the skin. In the cornea the peripheral cells are 
swollen and irregular in shape and the substan- 
50 RADIOLOGICAL DEFENSE 
tia presents enlarged interspaces. Pigment 
clumps in the chromatophores of the iris; later 
this occurs in the choroid. The retina is con- 
sidered more resistant than the lens. The lens 
is also resistant, the young being more suscep- 
tible to cataract which may show equatorial and 
posterior cortical cellular proliferation. 
Bone: Eburnation and death without leuco- 
cytic reaction or sequestration or zone of de- 
marcation are the effects of radiation to bone. 
Osteoblasts and osteocytes may disappear leav- 
ing the lacunae as empty spaces. The ivory-like 
texture is distinct as dense zones in the roent- 
genogram. Lack of osteoclasts, as the more ra- 
diosensitive bone cells, and therefore decreased 
bone absorption may be a factor. There is in- 
creased brittleness. Cells of the epiphyseal car- 
tilage are sensitive and the normal columnar 
pattern is changed; 1200 r in children stops 
growth, and prolonged fluoroscopy over the 
epiphysis in setting a fracture in a child must 
be avoided. Chondroblasts are also sensitive but 
hyaline cartilage is relatively insensitive. Peri- 
chondritis as in the ear, nose, and larynx 
develops late, sometimes after years. 
The irradiated heart, which is resistant, may 
go into auricular flutter or fibrillation. Fatty 
degeneration, edema and cellular infiltration 
may be seen. 
The nerves and ganglion cells are very re- 
sistant but in an irradiated area may show 
changes secondary to the vascular effect. 
Body weight decreases after total body radi- 
ation. Most visceral organs are affected less 
than body weight. Muscle weight is parallel 
to body weight and spleen, thymus, gonads and 
gonadol fat are reduced out of proportion in 
rats (Brues et al, 1946). Except for radiosen- 
sitive organs, the weight loss is similar to that 
of inanition. 
The lymphopoietic and hemotopoietic tissues 
are strikingly altered. Not only is grave atro- 
phy visible, but also there are secondary effects 
of hemorrhagic tendency and increased sus- 
ceptibility to infection, as in other profound 
aplastic anemias. A heparin-like substance is 
present along with prolonged clotting as well 
as prolonged bleeding time. No leukopenia is 
present in the normal animal cross circulated 
with the irradiated cat. Rabbits with regenera- 
tive anemias induced by phenyl hydrazine or 
bleeding when irradiated, 800 r, show no in- 
creased anemia or retardation in recovery as 
compared with controls (Jacobson 1948). This 
would also seem to indicate that rubrablasts or 
other early progenitors of erythrocytes are not 
as radiosensitive as erythrocytic cells in non- 
stimulated, normal marrows, 
51 RADIOLOGICAL DEFENSE 
PATHOLOGIC ANATOMY OF RADIATION EFFECTS 
OF ATOMIC EXPLOSION 
Colonel Elbert DeCoursey, MC, USA 
Commandant, Army Medical Department Research and Graduate School 
Army Medical Center, Washington, D. C. 
Before considering the radiation effects on 
the systems of the body, it is important to 
consider the relationship of lesions and time 
of death. In Japanese patients dying within 
two weeks after exposure there was histologic 
evidence of radiation in the lymphoid tissue, 
bone marrow, blood, gonads, gastrointestinal 
tract, and skin that was not manifested clini- 
cally. In the group dying in the third to sixth 
weeks, bone marrow changes predominated, 
while neutropenic ulcers and hemorrhages were 
very common. The general nutritional state de- 
clined. Gross changes were at the peak. Those 
dying in the third and fourth months showed 
beginnings of recovery in bone marrow and 
hair regeneration. Testicular changes remained 
prominent. There was an increase in the num- 
ber of emaciated patients. The poor nutrition 
was not based entirely on shortage of food, 
intestinal lesions and other factors playing 
important parts. 
Skin. The quickly visible changes, other than 
ordinary trauma and burns, in Japanese af- 
fected by an atomic bomb were the pigmented 
areas that appeared in the first few weeks and 
persisted. These had such sharply demarcated 
outlines that they were considered as thermal 
flash burns. Development of what we have 
recognized as ionizing ray skin burns was not 
seen. There were a few early cases with bullous 
edema that may have been from gamma rays. 
Epilation appeared mainly on the scalp, occa- 
sionally more on one side than the other, but 
far less commonly in the axilla, pubic region, 
and eyebrows. 
Microscopically the hair follicles showed dis- 
tinct changes both in the epidermal and dermal 
coats. Adequate early specimens were not ob- 
tained, but in the fourth week the internal 
root sheaths could not be identified, the exter- 
nal sheath (continuous with the malphigian 
layer of the epidermis) being continuous with 
the hair shaft. Vascularity of the papillae was 
reduced, and the adjacent epithelium was atro- 
phic. Pigment was irregularly clumped. The 
dermal coat showed thickening both of the in- 
ner hyaline membrane and the cellular fibrous 
layer. In pushing the base of the hair toward 
the surface a continuous shrinking in the bot- 
tom of the follicle occurred until regeneration 
took place with new cells over the papillae in 
a manner similar to ordinary hair replacement. 
There was also atrophy of the sebaceous glands, 
but this was also present when old hairs were 
replaced in the normal individual. 
Some of the sweat glands were small, their 
cells occasionally vacuolated and pyknotic, and 
the basal membranes thickened. Evidence of 
radiation on the skin was not definite. Third 
degree flash burns could also be expected to 
have some radiation effect, but interpretation 
was difficult. At the edge of the burn areas 
there was hyperpigmentation in basal cells and 
chromatophores. Depigmentation of flash- 
burned skin in individuals nearer the explosion 
and hyperpigmentation in those further away 
were unexplained features. Some thinning of 
epidermis, hyperkeratosis, ironing out of papil- 
lae, and hyperpigmentation of basal cells were 
found in the scalp. Vascular and collagen 
changes were minimal. 
Pituitary. Large basophilic cells with much 
cytoplastic vacuolation appeared in 25 percent 
of the males dying in the third to sixth weeks. 
Because cells of this type are found in mammals 
after castration, they are known as '‘castration 
cells.” In the second and third months large 
basophils were found, only a few being vacuo- 
lated. 
Adrenals. In the first two weeks there was a 
loss of lipoid in the cortex, but in the next 
months the cortex progressively lost its orange- 
yellow color and was distinctly thin. Micro- 
scopically, most cells were granular rather than 
52 RADIOLOGICAL DEFENSE 
foamy, and the atrophy was most marked in 
the outer zona glomerulosa, contrary to what 
was expected. When foam cells were present, 
they were usually in the inner layer. The me- 
dulla was normal, usually. 
Heart. Epicardial petechiae were found with- 
in the first two weeks, and there was micro- 
scopic evidence of some perivascular and rare 
muscle edema in the myocardium. These 
changes continued to be present during the 
second month when myocardial hemorrhages 
were also seen. After the second month distinct 
irradiation changes were rare. 
Lungs. Only the slight perivascular edema 
of the pleura that appeared in the first two 
weeks might be a primary radiation effect. 
Hemorrhagic and necrotizing pneumonia were 
common after the first weeks, as secondary 
lesions. 
Genitourinary System. Except for hemor- 
rhagic manifestation, there were no primary 
lesions in the kidneys and ureters. In the 
hemorrhagic stage of the radiation disease, mu- 
cosal hemorrhages in the bladder might result 
in necrotizing ulceration without evidence of 
leukocytic infiltration. The prostate and sem- 
inal vesicles were not remarkable, except for 
an occasional neutropenic necrosis and the 
presence of a few spermatozoa that were mor- 
phologically normal in spite of the irradiation. 
The testes showed intense changes in almost 
every cadaver. As early as the fourth day when 
the parenchyma had a normal appearance 
grossly, the histologic sections presented 
marked injury of the germinal epithelium, 
numerous cells of which were necrotic and free 
in the tubules and even in the rete testis. The 
number of mitoses was small. Sertoli cells were 
increased in number. Mature spermatozoa were 
found even in later specimens with no sperma- 
togenesis. Apparently uninjured spermatozoa 
appeared in the seminal vesicles. In the second 
month gross examination revealed little. A few 
necrotic germ cells remained, but most had dis- 
appeared, and phagocytic or infiltrating inflam- 
matory cell activity was absent. A few bizarre 
cells still approximating the basal membrane 
appeared to be spermatogonia. Sertoli cells 
were more numerous. The tubules had started 
to shrink. At this time also the interstitial cells 
of Leydig were so prominent that some inter- 
preters considered them hyperplastic. Some of 
the small interstitial vessels showed the most 
marked vascular change of any part of the 
body. Beneath the distinct thin endothelium 
was an eccentrically located mass of eosino- 
philic, homogeneous, refractile material that 
almost occluded the lumen. This change was 
often best seen near the tunica albuginea and 
was present also in the third and fourth 
months. It is not differentiated from sclerosis 
seen in older individuals. The interstitial tissue 
was less, but still prominent. The basement 
membranes were quite thick, wavy, and acellu- 
lar. The tubules, more atrophic at this stage, 
were often hyalinized. Elsewhere Sertoli cells 
had replaced the germ cells, which were rare. 
In the third and fourth months the state of 
nourishment was poor, and specimens from the 
Dachau prison camp in Germany have been 
described as showing similar testicular changes. 
Changes in the ovaries were much less strik- 
ing. Gross changes, except as part of the 
hemorrhagic phenomena, were absent, even to 
the presence of a well-developed corpus luteum 
of pregnancy seen about the end of the first 
month after irradiation. Histologically, primary 
ova were usually present and only occasional 
specimens had a few atretic primary follicles. 
The absence of developing follicles was usual. 
There were no corpora lutea and the “resting 
phase” of the endomentrium reflected this. 
Amenorrhea was distinctly increased in Naga- 
saki, and a significant number of abnormal 
births and an increased death rate of the moth- 
ers in relation to distance from the explosion 
were found there. 
Gastrointestinal Tract, This tract was one of 
the first to show gross lesions. Even before 
hemorrhagic manifestations the cecum or colon, 
particularly, might present a widespread 
change marked by swelling, green and yellow- 
gray coloration, and induration of the mucosa, 
sometimes with a pseudomembranous effect, 
and with much submucosal edema. Later mu- 
cosal hemorrhage might institute another cycle 
of similar change in the stomach or intestine. 
53 RADIOLOGICAL DEFENSE 
This change might begin with ulceration of the 
mucosa at the site of the hemorrhage and pro- 
gress to a pseudomembrane or deep ulcer. 
Often in 60 to 120 days the enteritis recurred, 
usually in the distal portion of the large in- 
testine but sometimes the small intestine and 
occasionally the stomach might present the most 
prominent lesion. In the small intestines only 
the tips of the folds might first be involved. 
These looked at first as though they had been 
dipped in boiling water and then became green 
or yellow-gray. A few specimens of small in- 
testine had a diffuse mucosal process. The 
large intestine in this late stage usually had a 
more widespread process that might extend 
from the ileocecal valve to the rectum. The 
thickened wall was characteristic. A pseudo- 
membrane and ulceration were sometimes pres- 
ent so that the morphology was similar to that 
of bacillary dysentery. Much of the process 
here was not only an irradiation effect of the 
sensitive intestine, with lowered local ability 
to cope with intestinal microorganisms, but 
also probably more important, lowered anti- 
biotic capabilities of the blood. 
Microscopically the epithelium early con- 
tained extremely bizarre cells with giant hy- 
perchromatic nuclei and multipolar mitoses. 
The swelling was seen to be from edema and 
some of the peculiar coloration from the ab- 
sence of infiltrating leukocytes. Later, areas of 
mucosal ulceration with much fibrin, few leu- 
cocytes, and in the remarkably edematous sub- 
mucosa quite a few histocytes, a few lympho- 
cytes, and occasional eosinophils were seen. 
Plasma cells of the lamina propria remained 
numerous. 
Spleen. The lymphoid elements here reacted 
to radiation as in the nodes. Early spleens 
were usually small, but occasionally showed the 
early swelling reaction. On section, they were 
dark red and not soft. The follicles were in- 
distinctly seen, and the trabeculae were promi- 
nent. Besides the near absence of lymphocytes, 
large mononuclear cells were increased, and 
erythrophagocytosis and hemosiderin deposits 
were seen. In the second month the spleen was 
small and follicles were absent. There was a 
syncytial reticulum around the follicles in 
which the slight lymphocytic content of the 
organ was seen. Atypical large mononuclear 
pleohistiocytes, indistinguishable from Dorothy 
Reed cells, were found. Through the fourth 
month there was still some atrophy. Occasional 
germinal centers appeared, and the lympho- 
cytic content showed evidence of recovery. 
Lymph Nodes. The high sensitivity of lym- 
phoid tissue to ionizing radiation resulted in 
tremendous atrophy seen as early as the third 
day. Lymphocytes almost disappeared, leaving 
a lacy framework that was histologically spec- 
tacular. A similar picture was found in the 
tonsils and other lymphoid tissue. Changes in 
the germinal centers might be necrobiosis, but 
a departure from normal was not marked ex- 
cept when the germinal centers disappeared, as 
they did in three-fourths of those who died in 
the first two weeks. The early gross appearance 
of human nodes was not known, but bombed 
animals showed some enlargement, softening, 
and a paler color. By the second week large 
atypical mononuclear cells, pleohistiocytes, con- 
sidered by one observer as lymphoblasts, ap- 
peared. Again, these are the same as Reed- 
Sternberg cells but in a different environment 
than when they were first recognized and 
named. These cells logically could be patho- 
logic forms whose sensitive nuclear chromatin 
was deformed by the radiation. About the fifth 
week, the nodes were usually small and almost 
devoid of lymphocytes and germinal centers. 
Bizarre large cells were more numerous. Plas- 
ma cells, eosinophils, and mast cells, along with 
increased numbers of reticulum cells, were 
present. Lymphocytes were more numerous in 
the fourth month but were still reduced. 
Bone Marrow. The cellular picture of irra- 
diated bone marrow was tremendously changed 
in the first week after the bomb explosion. 
There was almost total disappearance of blood- 
forming elements, excepting small islands of 
erythropoiesis. By the end of the week, retic- 
ulum began to proliferate and differentiated 
first into plasma cells and lymphocytes rather 
than granulocytic cells. This type of differen- 
tiation was predominant until the fourth week 
when myeloid differentiation was seen. Most 
marrows of those dying before six weeks were 
54 RADIOLOGICAL DEFENSE 
hypoplastic, but a few showed hyperplasia with 
lack of maturation. Most of the fatal cases of 
the third and fourth months showed hyperpla- 
sia, which in the femur was grossly evident 
as pink marrow extending through from one- 
third to one-half of the shaft. In these the 
maturation increased and more segmented cells 
were found in the peripheral blood and in 
infected tissues. A few of the older cases, 
however, showed aplasia with pink gelatinous 
femur marrow. Some grossly appearing hyper- 
plastic marrows were really hypoplastic, some 
of the pink color coming from dilated blood 
vessels. Whatever the marrow picture, there 
was usually a profound leukopenia at some time 
in those dying in the first six weeks. Later 
leukopenia did not persist, and even some of 
those who died had leukocytosis. Anemia was 
greatest about the sixth week in those that 
lived, but in those that died anemia progressed 
even into the fourth month. 
Miscellaneous. Only secondary hemorrhagic 
or necrotic changes were found in the brain. 
No changes were found in the pancreas, except 
for some mitoses in the islet cells. The pres- 
ence of any irradiation effects in the liver 
is a moot point. 
Secondary Effects of Radiation of Reticulo- 
Endothelial System. Hemorrhagic lesions and 
leukopenic necrosis most prominently affected 
the irradiated body about the end of the first 
month. The pharynx and its connections, the 
gastrointestinal tract, the respiratory organs, 
and the skin manifested both changes. In addi- 
tion, particularly the urinary tract, mesothelial 
linings, muscles, and all soft tissues, showed 
petechiae, purpuric patches, or large ecchy- 
moses. These changes were outstanding clini- 
cally after the second week, but appeared in the 
viscera in the first week. The severity depended 
on the location of the larger hemorrhagic le- 
sions. Hemorrhages in the linings of the pha- 
ryngeal regions, of the bowel, or of the 
urinary tract gave signs externally. Large sub- 
mucosal hemorrhages as well as petechiae ap- 
peared in the kidney pelves and in the bladder 
and sometimes in the ureters. There were cases 
with prolonged clotting time as well as bleed- 
ing time, consonant with the presence of hepa • 
rin-like substance as well as thrombocyto- 
penia. Hemorrhages breaking through the 
epithelium of bacteria-laden surfaces often ini- 
tiated the neutropenic ulcers, which in the 
pharynx were similar to acute agranulocytosis. 
Ulcers sometimes extended to the tongue, gums, 
buccal mucosa, lips, and even the skin to give 
the picture of noma. Such ulcers also began 
without hemorrhage. Bacteria ordinarily non- 
pathogenic might cause serious consequences 
through the loss of sufficient reticule-endothelial 
reserves. Ulcers throughout the gastrointesti- 
nal tract were on a similar basis, as indeed, 
many of the diffuse mucosal changes might be. 
The necrotizing pneumonia appeared to be a 
part of this picture. There was little leukocytic 
reaction in these lesions, which overwhelm the 
patient and lead to death. 
Case History. A 29-year old man was at a 
distance of 0.7 km. from the explosion center. 
He was outdoors a few paces from a concrete 
building and was struck by a falling roof that 
inflicted slight head and neck injuries. There 
was nausea on 6 August 1945. On this first 
day he vomited about 25 times. Malaise, ac- 
companied by anorexia, began on 6 August and 
lasted until 10 August. He again experienced 
malaise from 21 August until he died on 1 Sep- 
tember. Anorexia appeared 4 days after the 
second onset of malaise. There was epilation 
and gingivitis on 21 August, which persisted. 
The gingivae began to bleed on 30 August. On 
25 August tonsillitis and purpura were noted. 
Both of these symptoms lasted until death. 
There was a high fever between 24 August and 
the time of death; and there was a productive 
cough beginning on 25 August with a hemop- 
tysis on 30 August. The urine examined on 
29 August was positive for albumin and nega- 
tive for sugar. 
Sections of marrow in this patient were hy- 
perplastic, showing vascular adipose tissue 
crowded by a large number of young myelo- 
cytes. Mature polymorphonuclear leucocytes 
and even stab cells were rare. There was an 
occasional megakaryocyte. Occasional cells were 
found in mitosis. A few small cells with 
55 RADIOLOGICAL DEFENSE 
shrunken nuclei, thought to be normoblasts, 
also were found. Other important lesions at 
necropsy were: petechiae of the skin; epilation 
of the scalp; focal necrosis of the pharynx, 
tongue, tonsils, and larynx; necrotizing gingi- 
vitis; an abscess in the region of the right 
mandibular joint; necrotizing and hemorrhagic 
aplastic pneumonia; and minute hemorrhages 
of the gastrointestinal tract, trachea and renal 
pelvis. 
56 RADIOLOGICAL DEFENSE 
DIAGNOSIS OF IONIZING RADIATION INJURY BY PHYSICAL 
EXAMINATION AND CLINICAL LABORATORY PROCEDURES 
By 
Lieutenant Commander Eugene P. Cronkite, (MC), USN 
Head, Hematology Section 
Avomic Energy Medical Division 
Naval Medical Research Institute 
Foreword: This article first appeared in NMRI Project 007039, Report No. 8, April 8, 1948. 
INTRODUCTION 
more potent materials. Prevention is the first 
consideration (104) and recognition of the in- 
jury is the second consideration in any program 
of preventive medicine. The purpose of this 
report is to outline the available knowledge on 
diagnosis of ionizing radiation injury by means 
of physical examination,, and laboratory proced- 
ures. Dosimetry, the basis of prevention, will 
be referred to only for illustrative purposes. 
In the course of this discussion frequent ref- 
erence to animal experimentation will be made, 
where human data are lacking or inadequate. 
It must be fully appreciated as will be brought 
out in the course of this report, that the rela- 
tionship between time of exposure and the ap- 
pearance of signs and symptoms is not the 
same for man and smaller laboratory animals. 
All values for radiation dosage and laboratory 
procedures are the best possible estimate, based 
on available knowledge, and will have to be 
modified as more precise information becomes 
available. 
Both acute and chronic effects may result 
from either internal or external ionizing radi- 
ation. The resulting clinical and laboratory pic- 
ture is a function of the amount of radiation, 
its rate of delivery, and the depth dosage (69, 
111). This report will be divided into two 
parts dealing with the single intense exposure 
and the repeated exposure of lesser intensity. 
Diagnosis of single intense exposure to ion- 
izing radiation. For the purpose of the present 
discussion a single intense exposure will be de- 
fined arbitrarily as a total body exposure of 
more than 25 roentgen units delivered within 
a few hours. An exposure of 25 r is set as the 
lower limit because the effects of lesser amounts 
are most difficult, if not impossible, to detect 
by clinical means (55). Whether lesser amounts 
Prior to the advent of the cyclotron in 1931, 
sources of exposure to ionizing radiation were 
limited largely to X-rays, radium, and its dis- 
integration products. The occupational injuries 
such as radiation burns, ulcers, and carcinoma 
(52), aplastic anemia (52, 97)*, leukemia (49, 
75) and radium poisoning (76) were common 
among the pioneer workers. In recent years 
these occupational hazards have been reduced 
but not entirely eliminated by means of edu- 
cation, refinements in technique, and a better 
understanding of the biological effects of ioniz- 
ing radiation. 
With the installation of cyclotrons in many 
universities and scientific institutions and the 
development of the atomic energy industry, 
sources of exposure to ionizing radiation are 
increasing with great rapidity. In addition to 
the increased number of sources there are the 
artificial radioisotopes produced by the cyclo- 
trons and the chain reacting piles that are 
being extensively distributed for scientific study 
and therapy of radiosensitive diseases. A haz- 
ard of contamination of domestic and wild ani- 
mal and plant life by radioactive substances 
will occur if any notable volume of radioactive 
sewage from industrial and scientific services 
should develop. Again, if atomic warfare should 
occur, disposal of radioactive fission products 
will be impossible and widespread contamina- 
tion of urban areas and watersheds may occur. 
Injuries produced by the new sources and 
radioactive materials are no different than the 
injuries produced by the old sources. The prob- 
lem today is qualitatively the same but quanti- 
tatively there are more people working with 
♦Numbers in parenthesis refer to bibliography. 
57 RADIOLOGICAL DEFENSE 
may produce deleterious late effects is not 
known with certainty. The effect of exposure 
to ionizing radiation is determined to a con- 
siderable extent by the physical characteristics 
of the ionizing radiation concerned, that is, the 
type (alpha, beta, gamma, X-ray, or neutrons), 
the ability to penetrate (type and energy), 
and the rate at which the radiation is being 
delivered. With a single accidental exposure 
that may occur, these physical characteris- 
tics are usually known because of the nature 
of the experiment. Dosimetry (104, 8A) deter- 
mines to a large extent the above-mentioned 
physical characteristics. These physical charac- 
teristics are important because the clinical pic- 
ture varies with the number of organ systems 
involved. Total body exposure to highly pene- 
trating radiation in which all organ systems are 
affected, produces the severest picture but 
with a lesser amount of radiation than larger 
amounts absorbed superficially. 
Symptomatology in man following the single 
intense exposure is quite well known from the 
experiences of the Japanese following the atom- 
ic bomb explosions over Hiroshima and Naga- 
saki (71, 112), 
A few hours after exposure to the atomic 
bomb ionizing radiations, nausea and vomiting 
appeared. This lasted for a few hours and then 
subsided for a variable latent period of days. 
The shorter the latent period the more severe 
the symptoms of recurrent nausea and vomit- 
ing, mucous or bloody diarrhea, purpura, epila- 
tion, and agranulocytic infections. In general, 
the tempo at which the disease progressed in 
the Japanese and the Bikini animals was a 
direct function of the amount of radiation re- 
ceived (17, 71, 105, 112). 
The latent period, the length of time between 
exposure and the development of symptoms, is 
of great interest. The duration of the latent 
period in mammals is inversely proportional to 
the amount of radiation received. With very 
large amounts of radiation, in excess of 10,000 r, 
the latent period becomes very short and 
death may occur within 24 hours or even while 
the radiation is being received (17, 23, 47 III). 
Each species has its characteristic latent period 
for the development of the full symptomatol- 
ogy. In goats it appears to be 3-5 days; in swine 
it is approximately 5-7 days (17). In man it 
is probably longer. It is important to remember 
that with short latent periods death may occur 
before the full syndrome develops. 
In the case of ionizing radiation that can 
penetrate only a few millimeters of tissue, 
signs and symptoms are limited to the surface 
of the body. Raper (89) has described the ef- 
fects of beta radiation upon the skin of rats. 
Robbins, et al., (92) have described the effect 
of scattered cathode rays on the skin of man. 
In general one can state that the effects upon 
skin resemble thermal burns and that any- 
thing from erythema and massive vesiculation, 
to full thickness destruction of the skin may 
occur. Cutaneous changes are manifested by 
1-3 stages depending upon the intensity of the 
radiation. For full details the reader is referred 
to the articles by Robbins (92), Raper (89), 
and Ellinger (22). 
The early hematologic responses of man to 
single intense exposures to ionizing radiation 
is not well known. Unfortunately, the early 
blood changes were not observed in the Japa- 
nese hence reference will have to be made to 
laboratory animals in order to get an idea of 
what might be expected. There is no reason 
to expect any qualitative difference but there 
may be significant differences in sensitivity and 
rate changes in the peripheral blood. 
The hematologic responses of laboratory ani- 
mals to single intense exposures to penetrating 
ionizing radiation are quite uniform (12, 16, 
'33, 47, 55, 78). However, following exposure to 
less penetrating radiation the blood changes 
Comdr. Cronkite received his A.B. degree in 
1936 and his M.D. in 1940 at the Leland Stanford 
University at Palo Alto, California. He has been 
on duty with the U. S. Navy Medical Corps since 
June 1942. Comdr, Cronkite was Hematologist 
with the Naval Medical Research Section, Joint 
Task Force One, Operation Crossroads at Bikini 
in 1946. He is currently Head, Hematology Divi- 
sion, Naval Medical Research Institute and is 
studying the effects of radiation on the hema- 
tapoietic systems and the therapy of radiation 
illness. 
58 RADIOLOGICAL DEFENSE 
may be fleeting, slight or absent despite severe 
superficial injury. 
Beginning shortly after exposure to pene- 
trating radiation there is a prompt decrease 
in the total lymphocyte count which is most 
marked within 24-72 hours depending upon 
the amount of radiation received (55) (Fig. 1 
and Table 1). Recovery following a non-lethal 
dose begins within a few hours or days. De- 
veloping simultaneously with the progressive 
lymphocytopenia is a moderate granulocytic 
leukocytosis which appears as two peaks ap- 
proximately 12 and 24 hours after exposure in 
rabbits (55) (Fig. 1). If counts are not per- 
formed at about hourly intervals, one of the 
peaks may be missed. After the 24-hour peak 
there is a progressive decline in the granulocyte 
count for the next 4-6 days when there is a 
fleeting increase in granulocytes which is par- 
alelled by a wave of bone marrow activity (4). 
This activity is short lived and the granulocytes 
again decrease. The subsequent course depends 
upon whether the exposure is lethal or non- 
lethal. In non-lethal exposures a sustained 
though small rise in the granulocytes appears 
around 15-17 days. In lethal exposures this 
sustained return of granulocytes is absent 
(17). Granulocytic leukocytosis may not occur 
after very heavy radiation (47 II, 47 III). 
Reduction in the number of platelets, red 
cells, and the morphologic changes in the leuko- 
cytes appear more slowly and are not so uni- 
formly observed. In the Bikini goats and swine 
a marked shower of immature red cells ap- 
peared in the peripheral blood 10-12 days after 
the atomic bomb air burst (16). This phenom- 
enon has been repeatedly observed in smaller 
laboratory animals (111). Atypical and im- 
mature leukocytes and nucleated red cells 
appear in the peripheral blood beginning 3-10 
days after exposure (16, 111). 
In concluding the section of this report on 
the single intense exposure to ionizing radia- 
tion it is felt that the following can tentatively 
be stated regarding man, until actual observa- 
tions substantiate or refute these suppositions. 
If no decrease in the total lymphocyte count 
occurs in the first 48 hours, usually the first 
24 hours, the exposure has certainly been less 
than 25 r and symptoms probably will not ap- 
pear. If exposure has been between 25-100 r 
a fleeting lymphocytopenia will develop and 
symptoms will probably be mild. If exposure is 
between 100-200 r the lymphocytopenia will be 
of greater severity and last longer. Severe 
symptoms of radiation illness and death will 
occasionally occur. If exposure is greater than 
200 r the symptomatology of radiation illness 
will be much more severe and deaths will occur 
more frequently. The leukocytic changes par- 
ticularly the early lymphocytopenia, will be 
marked. 
The foregoing determination of a decrease 
in total lymphocytes or total leukocytes unfor- 
tunately cannot be predicated on a normal aver- 
age for man or animals. The range of normal 
blood cell counts is great for all animals par- 
ticularly in mongrel populations like man (12, 
29, 82). Normal hematologic values of man will 
be considered in the second part of this report 
along with schemes for the detection of devia- 
tion from the normal ranges. Needless to say, 
in order to detect fleeting changes in members 
of the leukocyte population total white and dif- 
ferential blood cell counts must be performed 
every hour or so. 
Diagnosis of acute radiation illness by the 
leukocyte count is obviously totally impractical 
under conditions of a catastrophe or atomic 
warfare. Hence the development of an easily- 
read casualty dosimeter is imperative. 
The diagnosis of cumulative small exposures 
to ionizing radiation. The diagnosis of repeated 
small exposures to ionizing radiation presents 
an entirely different problem. The changes are 
insidious and progressive. If excessive cumula- 
tive exposure is not detected early, the changes 
may be irreversible and may lead to serious 
and fatal diseases (33, 38, 39, 48, 49, 52, 59, 75, 
76, 79, 85, 97, 111). At the present time 0.1 
r/day has been set as the maximum amount 
of radiation that can be tolerated daily with 
impunity. Animal experimentation by Lorenz, 
et al., (74) on mice suggests that the tolerable 
dose of radiation for females should be set even 
lower because of increased incidence of ovarian 
tumors. 
The physical characteristics of the radiation 
59 RADIOLOGICAL DEFENSE 
determine to a great extent the effects that will 
appear from chronic exposure. The penetrating 
radiation may result in generalized systemic 
and hematologic disorders in addition to the 
purely superficial effects of radiation with a 
very low degree of penetrability. 
The physical characteristics of the radiation 
are usually known as a specific job hazard. 
Relative exposure to beta, soft X-ray and 
gamma radiation is determined by suitable 
dosimeters (104, 8A). 
The superficial lesions that appear are large- 
ly limited to the skin and eyes. Cutaneous le- 
sions are apt to appear in fluoroscopists, radio- 
chemists, and radium handlers. An increased 
brittleness of the finger nails with a tendency 
to develop increased longitudinal ridges is com- 
mon. Later there may be a loss of the integrity 
of the fingerprint due to patches of atrophy. 
Pigmentation, ulceration, and carcinoma may 
follow the atrophy. Epilation of hairy parts 
may occur. Impaired sensation of the finger 
tips commonly accompanies the above changes 
(52, 110). In the eyes, radiation cataracts may 
occur at an early age (97). However, the alter- 
ation in the blood is the best biological index of 
chronic total body over-exposure to ionizing 
radiation. 
Many investigators have called attention to 
the great variability of the blood of man chron- 
ically exposed to ionizing radiations. Leukocy- 
tosis, lymphocytosis, leukemoid reactions, leuko- 
cytic leukemias, erythrocytosis, reticulocytosis, 
leukopenia, thrombopenic purpura, aplastic 
anemia, and leukopenic leukemias have all been 
reported as produced by chronic exposure to 
radiation (21, 33, 38, 39, 49, 52, 59, 62, 75, 76, 
79, 85, 97, 109, 111). The blood picture may be 
temporarily or permanently altered by many 
diseases and industrial intoxications in addition 
to radiation. For example, infectious mononu- 
cleosis may affect the total and differential 
white blood count of young adults for many 
months after symptomatic recovery (19). Ex- 
amples of industrial poisons which affect the 
blood are benzol (36, 37) and heavy metals 
(52). Hence it is apparent that a “normal” 
range of blood counts for man must be estab- 
lished. This is difficult because the blood picture 
varies with age and to a variable degree with 
sex, pregnancy, meals, humidity, and temper- 
ature. 
Osgood (82) gives the “normal” values for 
individuals of different age and sex (see Table 
2). 
In naval personnel without any recent his- 
tory or sign of disease (18) between the ages 
of 17-35 in the tropics and in a temperate 
zone, the total white count varied from 4,GOO- 
16,000. The total lymphocyte count was usually 
below 3,000 and rarely above 5,000, Probably 
90 percent of the adult population will have 
total white counts between 5,000 and 11,000 per 
cmm. The 10 percent of adults whose counts 
are outside of this range may cause consider- 
able consternation in a radiological safety pro- 
gram and lead to medico legal problems. 
Goldwater (36) has correctly called attention 
to the wide range of normal lymphocyte counts 
in his data and that of Osgood (82). The data 
on naval personnel confirm this concept. In ad- 
dition Goldwater calls attention to the neces- 
sity of having comparable parallel control 
studies on subjects that are not subjected to 
any known toxic agents. 
How are the blood changes of prolonged or 
repeated exposure to radiation determined? It 
is apparent that the average count is not de- 
pendable for the general population or specific 
age groups, hence base line complete blood 
counts must be performed on all individuals 
before exposure takes place. Subsequent counts 
should be performed at not less than monthly 
intervals. Notations on the occurrence of colds 
and infections, must parallel the blood records 
for without these base line records and a knowl- 
edge of each individual’s response to infections 
an evaluation of leukocyte changes is more 
difficult. 
A partial review of the literature (21, 22, 
38, 39, 48, 52, 59, 60, 62, 76, 78, 79, 85, 97, 109, 
111) confirms the opinion that if any of the fol- 
lowing alterations are noted in an individual 
whose usual blood values are known and who 
has been exposed to ionizing radiation it is 
presumptive evidence of excessive exposure un- 
til proved otherwise: 
60 RADIOLOGICAL DEFENSE 
a. A persistent depression of the total leuko- 
cyte count below 4,000 per cmm. 
b. A persistent elevation of the total leuko- 
cyte count above 15,000 per cmm. with an 
absolute lymphocytosis. 
c. A relative lymphocytosis with a low total 
count (4,000-6,000 per cmm.) that re- 
turns to base line range following removal 
from exposure. 
d. An increased mean corpuscular volume 
(MCV), a shift in the Price-Jones curve 
to the right, an increase in the mean 
corpuscular diameter (MCD), 
e. A reticulocyte count over 2 percent. 
f. An erythrocytosis: 
(1) Red blood count over 5.8 million 
per cmm. 
(2) Hemoglobin over 18.0 gm/100 cc. 
blood. 
Many other phenomena have been suggested 
as hematologic evidences of excessive exposure. 
Changes in blood coagulation, prothrombin 
time, platelets (60), and morphologic changes 
in leukocytes (97) have been suggested. It is. 
exceedingly difficult to evaluate the importance 
and the diagnostic value of these changes. A 
more recent observation on excessive exposure 
has been the description of refractile “Dickie 
bodies” in the lymphocytes (21). These refrac- 
tile bodies are stained with neutral red in a 
supravital preparation and the authors believe 
that increased numbers of the bodies are spe- 
cific evidence of exposure to radiation or indus- 
trial poisons. The procedure necessitates a flaw- 
less supravital technique which is not widely 
available, hence the technique may not be gen- 
erally useful. Limited personal experience with 
swine and goats suggests that these bodies ap- 
pear irregularly in lymphocytes as the lym- 
phocytes age in the supravital preparations, 
hence a rigid time control might be necessary. 
The foregoing criteria depend upon abnor- 
malities in the enumeration or morphology of 
blood cells which arise from either depressed 
hematopoiesis, an increased lability of the he- 
matopoietic organs, or abnormal maturation. 
The establishment of the presence of these 
criteria must of necessity be done without ade- 
quate controls that would not be permitted in 
the average biologic experiment. Hence it is 
much better to have some type of human con- 
trol. This can be attained by establishing a 
comparable control group which are not sub- 
jected to any known toxic agent and perform- 
ing parallel studies upon this group. Average 
values for exposed and control groups should 
be studied statistically to see if there are sig- 
nificant differences between the means of the 
two groups. In a comparable fashion the pre- 
exposure counts of the exposed group can be 
used as the control. If the average leukocyte 
count of the group for a given exposure period 
is significantly less than the group average leu- 
kocyte count of the pre-exposure period one 
can state with considerable certainty that ex- 
cessive exposure to ionizing radiation or other 
toxic agent has occurred. 
The following procedures will aid in deter- 
mining the cause of any abnormal blood find- 
ings in a person suspected of having been ex- 
cessively exposed: 
a. Remove the suspect from all possible 
exposure to ionizing radiation. 
b. Do differential counts of radiation on 
excreta, nasal swabs, and expired air in 
order to estimate the type and degree of 
internal exposure to radioactive isotopes. 
c. Study the blood at weekly intervals and 
compare with the pre-exposure base line 
leukocyte counts and search for an in- 
crease in the number of highly refractile, 
neutral red bodies in the lymphocytes. 
d. Endeavor to eliminate other factors such 
as infectious lymphocytosis, infectious 
mononucleosis, virus diseases, benzol poi- 
soning, and heavy metal poisoning. 
SUMMARY AND CONCLUSIONS 
1. The diagnosis of a single excessive expo- 
sure to ionizing radiation by blood examination 
is not difficult. If serious exposure has occurred, 
a prompt, marked lymphocytopenia results and 
is followed by a characteristic sequence of 
events in the other members of the leukocyte 
population. 
2. The diagnosis of repeated exposures to 
small amounts of ionizing radiation in an indi- 
61 RADIOLOGICAL DEFENSE 
vidual is much more difficult and uncertain. It 
requires in addition to blood studies, differen- 
tial counts of radiation in urine, feces, and 
nasal secretions, and lastly the elimination of 
other industrial hazards. 
3. The determination of repeated exposure 
to small amounts of ionizing radiation in 
groups of personnel by the statistical compari- 
son with a control group or by statistical com- 
parison of the pre- and post-exposure average 
leukocyte count is a reasonably accurate diag- 
nostic procedure. 
4, The main bulwark of protection from ion- 
izing radiation must remain physical control 
of radiation intensities by established monitor- 
ing procedures and prevention of contamination 
of personnel by radioactive materials. This is 
essential because most of the signs and symp- 
toms appear relatively late after the radiation 
injury has been sustained. 
62 RADIOLOGICAL DEFENSE 
Table 1—Tabulation of the changes in white blood cells of rabbits after exposure to ionizing radiation* 
Dose 
(r) 
Degree of depression 
in percent 
Time of 
depression 
maximum 
in hours 
Time required before 
return to 
normal limits (days) 
Lymphocytes 
Heterophils 
Lymphocytes 
Heterophils 
Lymphocytes 
Heterophils 
5 
0 
0 
10 
0 
0 
— 
— 
25 
25 
0 
24 
— 
2 
50 
25 + 
0 
48 
— 
16 
100 
50 
— 
48 
— 
36 
300 
74 
± 
24 
± 
50 
± 
500 
90 
50 
48 
72 
50 
9 
600 
90 
75 
48 
96 
50 
9 
700 
90 
80 
48 
96 
— 
800 
90 
90 
72 
96 
50 
23 
* From Jacobson, 
et a!. (55) 
Table 2—Tabulation of the variations of the leukocyte count of man with age and sex* 
Number 
of 
Subjects 
Age 
(In years) 
Sex 
Average 
in 1000’s 
per cmm. 
Range 
Leukocyte 
86 
4-7 
10,400 
6,000-15,000 
count 
242 
8-18 
M&F 
8,300 
4,500-13,500 
269 
19-30 
7,400 
4,500-11,500 
% 
% 
Neutrophiles, 
241 
4-14 
38.0 
18-58 
segment 
120 
15-19 
M&F 
48.0 
25-75 
236 
20-30 
54.0 
33-78 
Neutrophiles, 
219 
4-13 
3.0 
0-10 
band 
378 
14-30 
M&F 
0.8 
0-5 
Lymphocytes 
241 
4-14 
48.0 
21-71 
120 
15-19 
M&F 
22-62 
236 
20-30 
18-65 
* From Osgood (82) 
63 RADIOLOGICAL DEFENSE 
Figure 1 - The initial effect (during the first 48 hours) of total body irradiation on the number of 
heterophils in the peripheral blood. Jacobson, et al. (55) 
64 RADIOLOGICAL DEFENSE 
THERAPY OF ACUTE RADIATION ILLNESS 
Captain R, H. Draeger, (MC), USN 
By 
Head, Atomic Energy Medical Division 
Naval Medical Research Institute 
INTRODUCTION 
The present status of the therapy of acute 
radiation illness is difficult to present largely 
due to the confused state of our knowledge on 
this subject. A large number of therapeutic 
agents have been proposed which have not been 
critically evaluted. Much research is being con- 
ducted in this field and new facts, almost daily, 
brought to light. Time will be required to as- 
similate this information and work out a ra- 
tional therapeutic regime. It must be admitted 
that we now have little in the way of specific 
therapy. In view of these facts it is my inten- 
tion to outline the medical problems with which 
we are confronted rather than to attempt to 
discuss a therapeutic regime in great detail. 
The use of atomic energy is invariably as- 
sociated with the liberation of ionizing radia- 
tion and the possibility of external or internal 
radiation injury. The atomic bomb is capable 
of exposing large numbers of individuals to 
ionizing radiation at the time of the explosion 
or later through contamination by fission prod- 
ucts. The liberation of atomic energy in the 
uranium pile or in atomic power plants is also 
accompanied by a radiation hazard. Thus it will 
be seen that the problem of radiation injury 
or illness has become of great medical impor- 
tance. 
RADIATION ILLNESS 
Definition 
Radiation illness is a symptom complex 
caused by the direct action of ionizing radia- 
tion upon certain tissues or organs and partly 
due to the systemic action of toxic substances 
released in the course of tissue disintegration. 
Etiology 
The etiology of radiation illness is ionizing 
radiation delivered as total body irradiation or 
the irradiation of certain radiosensitive por- 
tions of the body. The irradiation of the upper 
abdomen is most prone to produce radiation 
illness. Irradiation of the thorax is less apt to 
produce radiation illness and the pelvis even 
less in comparable doses. Irradiation of the 
head, neck and extremities does not readily 
produce radiation illness. 
The source of this ionizing radiation may be 
external such as X-rays or the nuclear radia- 
tions from the atomic bomb or fission products 
including gamma rays, neutrons and beta par- 
ticles. Internal radiation, produced by radio- 
active substances taken into the body, will also 
cause radiation illness. In all cases it is the 
ionization produced within the tissues of the 
body which is the cause of the radiation illness 
irrespective of the source or particular type of 
radiation. 
The amount of ionization produced by an 
alpha, beta, or gamma ray will depend upon two 
factors: the total ionization and the specific 
ionization. Alpha, beta and gamma rays of 
equal energy will produce the same total ioni- 
zation when completely absorbed. However, the 
number of ions per cm. of path will vary 
enormously. The energy of the gamma rays 
will be distributed over a path measured in 
meters while the beta rays will be stopped in 
a few cm. at the most. Alpha particles, on the 
other hand, will only penetrate for a few 
microns. 
From this it is evident that the effects of 
gamma rays will be highly diffuse regardless 
of whether the source is external or internal. 
The effect of beta rays will be somewhat more 
restricted while alpha particles will be confined 
to a few layers of cells immediately surround- 
ing the source. 
The amount of radiant energy absorbed by 
the body from a lethal dose of ionizing radia- 
tion is surprisingly small. I have made some 
calculations in this regard which illustrate this 
point. Thus 1 r equals 83.8 ergs per gram of 
tissue and when calculated for a 150 lb. man 
65 RADIOLOGICAL DEFENSE 
receiving 500 r, the total energy is 283 X 107 
ergs or 283 joules or 283 watt-seconds which is 
sufficient to light a 50 watt lamp for 5.5 sec- 
onds or raise the total body temperature about 
1/100 of a degree. The body absorbs about 40 
times this much heat energy from a hot cup 
of coffee. 
Although total body irradiation may pro- 
duce ionization within every cell in the body, 
the initial harmful effects are manifest in the 
radiosensitive cells of a few tissues and organs 
located chiefly in the bone marrow, lymph 
glands, G.I. tract, skin and gonads. 
According to the law of Bergonie and Tri- 
bondeau, the biological action of X-rays is 
greater the higher the reproductive activity of 
the cell. This law was formulated by work on 
the testes but its validity has been confirmed 
for many other tissues. 
I will now enumerate the most important 
tissues of the body in the order of their dimin- 
ishing sensitivity to ionizing radiation: 
1. Lymphoid cells. 
2. Polymorphonuclear and eosinophilic 
leucocytes. 
3. Epithelial cells—including 
a. Basal epithelium of the secretory 
glands. 
b. Basal epithelium of the gonads. 
c. Basal epithelium of the skin. 
d. Epithelium of lung alveoli and bile 
ducts. 
e. Tubular epithelium of kidneys. 
4. Endothelium of blood vessels, plura and 
peritoneum. 
5. Connective tissue cells. 
6. Muscle cells. 
7. Bone cells. 
8. Nerve cells. 
Diagnosis 
Let us next consider some of the problems of 
radiation illness particularly as related to a 
disaster in which large numbers of individuals 
would be exposed to ionizing radiation. In such 
a situation it is extremely important to be able 
to determine quickly what dose of radiation 
each has received in order to segregate individ- 
uals into those who should carry on from those 
requiring hospitalization and therapy. Since 
the effects of irradiation are latent, it is likely 
that many individuals will be “psychological 
casualties” until the degree of their exposure 
is established. 
Clinical or laboratory examinations do not 
appear to be adequate for this purpose since 
they require highly trained professional per- 
sonnel and consume too much time. It might 
even be questioned whether the clinician will 
even be able to make a satisfactory prognosis 
prior to the onset of symptoms. A satisfactory 
dosimeter should be rugged, inexpensive and 
capable of being readily worn on the person. 
It should be capable of being read in a matter 
of seconds by relatively untrained personnel. 
Symptomatology 
Let us consider the symptom complex of 
radiation illness. It is convenient to divide the 
major symptoms into: general, gastrointesti- 
nal, cardio-vascular, hematologic and neurolog- 
ical or psychic. 
1. General Symptoms: Headaches, vertigo, 
debility, abnormal sensations of taste 
or smell. 
2. Castro-Intestinal Symptoms: Anorexia, 
nausea, vomiting, diarrhea. 
Captain Draeger attended the University of 
California at Berkeley and received his A.B. 
degree in 1924 and his M.D. in 1927. He was com- 
missioned in the Medical Corps, U. S. Navy in 
June 1927. He served as Executive Officer of the 
Naval Medical Research Institute from 1942 to 
1946 when he was assigned as the Officer in 
Charge of the Naval Medical Research Section 
of Joint Task Force One to direct and plan the 
biological and medical research aspects of the 
atomic bomb tests at Bikini. CAPT. Draeger con- 
ducted the biological test program at Eniwetok 
in 1948. At the present time he is Head of the 
Research Branch, Atomic Energy Division, Bu- 
reau of Medicine and Surgery, Department of 
the Navy; Senior Medical Officer of the Atomic 
Energy Medical Division at the Naval Medical 
Research Institute at Bethesda, and Chairman 
of the Council on Radiobiology, Atomic Defense 
Division, Bureau of Medicine and Surgery, 
Department of the Navy. 
66 RADIOLOGICAL DEFENSE 
3. Cardio-Vascular Symptoms: Tachycar- 
dia, arrythmia, fall of blood pressure, 
shortness of breath. 
4. Psychic Symptoms: Increased irritabil- 
ity, insomnia, fear. 
Metabolic Changes 
Alternations in body metabolism include the 
following: 
1. Water Metabolism: Absorption of fluids 
from tissues into the blood. 
2. Metabolism of Inorganic Substances: 
a. Acid-base equilibrium; bi-phasic ac- 
tion with initial acidosis, lasting for 
72 hours, followed by alkalosis. 
b. Loss of minerals; concerning chlo- 
rides, sodium calcium sulfur and 
phosphates. 
c. Relative increase of blood potassium. 
3. Protein Metabolism: 
a. Increased total protein content of the 
blood. 
b. Increase of non-protein nitrogen 
content in blood and tissues. 
c. Increased nitrogen excretion with 
the urine. 
4. Purine Metabolism: 
Increased urinary excretion of purines. 
5. Fat Metabolism: 
Fall (sometimes increase) in serum 
cholesterol levels. 
6. Carbohydrate Metabolism: 
Bi-phasic action; initial fall of blood 
sugar (12-24 hrs) followed by a rise. 
7. Gas Exchange: 
Slight increase in oxygation, rise in 
respiratory quotient. 
The mechanism responsible for the lethal 
effects of irradiation is not well understood; 
however, it may be worth while to examine 
some of the most conclusive evidence. In the 
light of recent investigations it appears that 
the toxic agents liberated during tissue break- 
down, following irradiation, may best be de- 
scribed as histamine-like in nature if not 
histamine itself for the following reasons: 
1. Histamine is capable of producing most 
of the symptoms and metabolic changes 
of radiation illness. 
2. Histamine is also capable of producing 
fatty changes in the liver similar of the 
changes seen following irradiation. 
Daugherty and White have observed that 
leukopenia following X-ray irradiation is at 
least, in part, caused by the indirect action of 
tissue decomposition products. These authors 
demonstrated that the normal leukopenia re- 
sponse in mice was not present in adrenalec- 
tomized animals. However, a larger dose 
caused leukopenia apparently due to direct ac- 
tion upon lymphatic tissues. Torgersen, in Oslo, 
has demonstrated the role of tissue decompo- 
sition products in the production of radiation 
effects in the adrenal cortex by the irradiation 
of ears of rabbits. 
In summing up this accumulated clinical and 
experimental evidence, the mechanism of radi- 
ation illness may possibly be explained as 
follows: 
Irradiation of sufficiently large volume of the 
body results in the release of histamine-like 
substances or histamine itself. These sub- 
stances induce the anterior-pituitary to secrete 
corticotropic hormone, which in turn stimulates 
adrenal cortical activity. This stimulation re- 
sults in exhaustion of the gland thus producing 
the symptoms of radiation illness. This sug- 
gests certain lines of therapy to be discussed 
later. 
Therapeutic Measures 
Any consideration of the therapy of radia- 
tion illness must take into account the fact that 
many cases of irradiation will be complicated 
by flashburn and blast injuries. Since the ef- 
fects of the atomic bomb include blast, thermal 
and ionizing radiation, it is difficult to evaluate 
the relative importance of each of these factors 
individually, all three contributing to the death 
of many individuals. We are confronted with 
the possibility that the presently accepted 
treatment of burns, for example, may not be 
the best in concurrently irradiated individuals. 
A large number of substances have been sug- 
gested for the treatment, of radiation illness 
but so far few have proved to be of value. 
Folic acid and pyridoxine are of no value in 
67 RADIOLOGICAL DEFENSE 
mice if given after irradiation. Rutin also ap- 
pears to be of no value. 
The use of antibiotics to combat the tendency 
to infection and septicemia in the agranulocy- 
tic stage of radiation illness will no doubt play 
an important part in the future treatment of 
this condition. 
Following the identification of an anticoag- 
ulant with heparin-like properties in acute ra- 
diation illness by Allen, it was hoped that the 
use of anti-heparin agents such as toluidine 
blue and protamine would favorably affect mor- 
tality but this had not yet been demonstrated. 
Since blood production practically ceases for 
a period of days following irradiation, blood 
transfusions are probably of value in main- 
taining resistance to infection and the oxygen- 
carrying capacity of the blood. 
In 1946, Ellinger, reported that desoxycorti- 
costrone acetate protects the liver against ra- 
diation fatty degeneration and at the same time 
reduces the X-ray mortality rate in mice. From 
this and other experimental evidence it was 
concluded that desoxycorticostrone would be 
useful in the therapy of radiation illness. Clin- 
ical studies in patients undergoing therapy 
have verified this opinion. This treatment ap- 
pears to counteract the mechanisms largely re- 
sponsible for the chain of events causing radia- 
tion illness. 
Recently sulfhyclryl (-SH) containing agents 
such as glutathione and cysteine have been 
investigated for the prophylaxis of radiation 
illness. This work has followed the discovery 
by Barron, et al, that sulfhydryl containing 
enzymes were reactivated by certain -SH con- 
taining substances and it was reasoned that 
such agents might favorably affect the course 
of radiation illness. This investigation in 
rodents has shown that administration shortly 
before exposure significantly decreases the 
LD50, minimizes the weight loss and decreases 
the severity of the symptomatology. 
Another point which cannot be too strongly 
emphasized is the need for immediate hospitali- 
zation of irradiated individuals with proper 
sedation. It can be shown that irradiated ani- 
mals are readily susceptible to injury from 
stress conditions such as chilling, fatigue 
and hunger which ordinarily produce little ill 
effect. 
CONCLUSION 
In conclusion I would like to point out the 
fact that much research work on the problem 
of radiation illness is now under way and im- 
portant discoveries may be anticipated which 
will lead to better and more specific therapy. 
68 RADIOLOGICAL DEFENSE 
TREATMENT OF ACUTE RADIATION ILLNESS 
By 
Major Albert J. Bauer, MC, USA 
Chief, Special Projects Division 
Office of the Surgeon General 
At one time or another, almost every drug 
in the pharmacopoeia has been recommended 
for the treatment of acute radiation illness; 
as you might expect with such a multitude of 
cures, none of them produces astounding re- 
sults. It is the purpose of this paper to present 
an outline of a course of practical therapy 
based on what we know today. As work con- 
tinues, it is hoped that the discovery of a spe- 
cific will render this effort obsolete, but until 
such a discovery is made, we must make every 
effort to be prepared to do the best we can with 
the tools available. Since the strain on our 
medical facilities will be great, it is just as 
important to shun ineffective procedure as to 
institute effective ones. 
Most important in the handling of cases is 
the maintenance of water balance. These pa- 
tients are nauseated, vomit and develop diar- 
rhea. The water loss may be excessive and oral 
intake will surely be low. Once dehydration is 
allowed to develop, the problems of acid-base 
balance will complicate the treatment. Time 
and effort can be saved by the early use of 
intravenous saline and 5 percent glucose. 
Almost as important as fluid balance is the 
maintenance of an adequate diet. These pa- 
tients have undergone tissue destruction and 
the materials for repair must be provided. This 
becomes a difficult problem in a person whose 
gastro-intestinal tract has received a major 
insult. It is impossible to orally feed these pa- 
tients to a point where the daily dietary re- 
quirement of 3,000 to 4,000 calories, including 
150 to 200 grams of protein, can be met. Every 
dietary trick, including the use of lactose and 
predigested food, must be utilized. Oral intake 
will have to be supplemented by intravenous 
feedings. It is interesting to note that 1,000 cc 
of blood plasma, that is the plasma from 2,000 
cc of whole blood, will furnish between 50 and 
60 grams of protein. Plasma being a complete 
protein, this will just about meet the daily 
nitrogen requirement. 1,000 cc of plasma rep- 
resents about 250 calories so additional calories 
must be supplied through the use of glucose. 
The continued administration of plasma tends 
to decrease red cell production and an occa- 
sional whole blood transfusion should be given 
when indicated. Every effort should be taken 
to aid the gastro-intestinal tract in its recovery 
by the use of emollient drugs and foods, and 
gastric sedatives. 
The vitamin intake must be maintained. With 
the two following exceptions, no specific vita- 
min therapy has proven advantageous and the 
exceptions are themselves questionable. It has 
been claimed that Vitamin B6 will decrease the 
incidence of nausea in patients undergoing 
X-ray treatment. It appears that B6 is more 
effective in preventing nausea than in relieving 
the symptom once it has developed. It therefore 
appears expedient to administer 25 Mg of Vita- 
min B6 daily to all patients who have received 
substantial radiation exposures. Work with 
Vitamin C indicates that it favorably effects 
the recovery of white cell production and its 
administration is also recommended. Of course 
the demand and the availability of these drugs 
will influence the decision as to its routine 
administration. 
At present toluidine blue and protamine sul- 
fate give promise of controlling the hemor- 
rhagic tendency which develops in the second 
and third weeks of radiation illness. Doses up 
to 8 Mg/Kg have been given to humans with- 
out producing toxic symptoms. 5 Mg/Kg have 
been reported to control hemorrhage and 3 
Mg/Kg have been reported to continue control 
once hemorrhage has been stopped. Rutin has 
not proved too satisfactory and it should not 
be given along with toluidine blue. 
Whole blood tranfusions appear to have lit- 
tle effect on the hemorrhage but as the case 
progresses the red and white counts fall; trans- 
fusions become necessary to furnish the means 
69 RADIOLOGICAL DEFENSE 
of oxygen transportation along with white cell 
and antibodies to bolster the body’s bacterial 
defenses. The number and frequency of trans- 
fusions will depend on each individual’s re- 
sponse and the availability of whole blood. Un- 
less the exposure has been overwhelming, the 
bone marrow will regenerate if given time. 
The rationale of whole blood transfusions, in 
fact of all recommended therapy, is to provide 
time for this regeneration to take place. 
As the white count falls, infections will de- 
velop and spread. The free use of antibacterials 
is recommended along with transfusions as 
indicated. These patients greet all types of 
trauma with poor bacteriological defenses. 
Therefore all procedures where the skin is 
broken must be done under sterile conditions 
and the maximum use made of each traumatic 
procedure. In severe cases it is probably wise 
to institute a continuous intravenous drip of 
normal saline and 5 percent glucose and use 
this channel for all parenteral administrations. 
The epilation which may occur in the second 
or third week does not respond to treatment. 
It is mentioned here because of its adverse 
effect on patient morale. If the patient is 
warned to expect this development, assured that 
it has no bearing on the final outcome of his 
case, and appraised that the hair will return in 
a few months, a great deal of psychic trauma 
can be eliminated. It must never be forgotten 
that these patients will be apprehensive and 
anything that can be done to reassure or make 
them more comfortable will be helpful, includ- 
ing the free use of sedatives when indicated. 
Many other measures are under study or 
have been recommended from time to time but 
at present none of them has proven of definite 
value. The use of adrenal cortical hormone or 
its substitutes should receive special considera- 
tion. There is some indication that its use offers 
protection to the liver—if it is available, it 
should be used on a series of cases to test its 
effectiveness. 
It must be kept in mind that many of these 
patients will be suffering from burns and trau- 
matic injuries as well as radiation illness. The 
necessary debridements and surgical proce- 
dures should be carried out as soon as possible 
after the radiation injury has been received 
as the poor response to infection and the hem- 
orrhagic tendency which develop in the second 
and third week dictate that surgical procedures 
be kept at a minimum at that time. 
The above suggestions are merely thoughts 
on therapeutic measures stimulated by a review 
of the literature. They are not presented as 
hard and fast rules. They are open to change 
at any time. It is hoped that they will be of 
some value if an emergency develops and you 
are called upon to decide the proper allocation 
of medical supplies between numerous casual- 
ties. Undoubtedly the availability of supplies 
and medical personnel will govern the type and 
extent of treatment. 
Maj. Albert Bauer received his M.D. from the 
University of Tennessee in 1941 and was com- 
missioned in the Medical Corps, U. S. Army in 
1942. He practiced radiology from 1943 until 1946 
and from 1947 to 1948 was on the staff of the 
Health Division at the Los Alamos Scientific 
Laboratory, Los Alamos, New Mexico. From 1948 
to 1949 he was Acting Chief of the Special 
Projects Division of the Office of the Surgeon 
General, U. S. Army. 
70 RADIOLOGICAL DEFENSE 
THERAPY AND HANDLING OF MECHANICAL AND THERMAL INJURY 
FROM THE ATOM BOMB* 
Herman f. Pearse, M.D. and J. Thomas Payne, M.D. 
By 
Department of Surgery, The University of Rochester 
School of Medicine and Dentistry, Rochester, N. Y. 
The energy released by the explosion of an 
atom bomb is of an order of magnitude unsur- 
passed by anything known to man. In addition 
to large amounts of radioactive energy, great 
quantities of thermal and mechanical energy 
are released. It is these latter two categories 
of energy that produce the great physical dam- 
age, large number of casualties, and utter de- 
moralization of the population subjected to the 
explosion. Photographs of the damage done by 
the atom bombs in Japan emphasize the mag- 
nitude of the damage from mechanical and 
thermal effects, and give mute evidence of 
the human demoralization and disorganization 
which takes places after such catastrophes. 
Injuries to personnel from the atom bomb 
explosion have been divided into three cate- 
gories: (1) Radiation injury, (2) Trauma, (B) 
and Burns (Table I) (9 and 71) f. Radiation 
injury is covered elsewhere in this manual. 
The arbitrary separation of the medical effects 
of the bomb makes the approach to the prob- 
lems raised more simple, but it should be borne 
in mind that one individual may have all three 
types of injury, and, as has been pointed out by 
Parsons (84), can be killed “three times over”. 
For purposes of clarity therefore, the remain- 
der of this paper will be devoted to the trau- 
matic and thermal effects of the bomb alone. 
Trauma of the primary type, due to blast 
alone (Table I), is difficult to evaluate. Appar- 
ently the blast did not have the trip-hammer 
effect of other high explosives but was more 
like a sudden violent gust of hot air, which 
lasted over a relatively long period (2). Pul- 
monary and other visceral blast effects were 
not noted, nor was the incidence of perforated 
eardrums excessively high (9). 
Table I 
Type of injury 
Est. percentage 
total per type 
injury (9, 71) 
Totals 
(67) 
I. Radiation Injury 
over 30% 
15% 
A. Primary. 
B. Secondary. 
II. Trauma 
70% 
A. Primary — Direct 
result of blast. 
B. Secondary — 
Fly- 
ing debris, such as 
glass, collapsing 
buildings, etc. 
>85% 
1. Fractures . . 
2. Lacerations 
3. Contusions . . 
,11% 
.37% 
.52% 
f Ninoshima 
1 Hospital (8) 
III. Burns 
65-85% 
1. Flash 
.95% 
2. Secondary .... 
. 5% 
The distribution and amount of secondary 
trauma was dependent on the distance from the 
ground center of the explosion. Figure 1 illus- 
trates the approximate zones of damage. With- 
in a radius of 2.4 km. there was complete col- 
lapse of the native wooden buildings. Within 
this zone, the incidence of mechanical injury 
was very high, dropping off gradually to less 
than 14 percent beyond 2.7 km. (2). 
The injuries consisted of fractures, lacera- 
tions and contusions. The low incidence of 
fractures (at least in the hospital given as the 
usual example—Table I) is probably because 
persons with major fractures were unable to 
seek treatment, or perished in the collapsed 
buildings. There is no evidence that these frac- 
tures were unusual in any respect. The contu- 
sions did not seem to be remarkable. The high 
incidence reported for these injuries is prob- 
*This paper 5s based on work performed under contract with the 
United States Atomic Energy Commission at the University of 
Rochester Atomic Energy Project, Rochester, N. Y. 
tNumhers in parenthesis refer to bibliography. 
71 RADIOLOGICAL DEFENSE 
ably explained by the fact that they are rela- 
tively minor, and permitted the individual to 
seek treatment. 
The lacerations were of interest in that they 
were largely due to flying glass fragments. 
These fragments were so small that clothing 
protected the individual in some instances. In 
other circumstances the fragments were of such 
size as to make removal difficult. Multiple 
lacerated wounds were very common (Fig. 2). 
The exact amount of morbidity and mortality 
attributable to the traumatic factor in the Japa- 
nese explosions will probably never be known, 
because immediately following the blasts, fire 
and disorganization prevented adequate and 
early rescue measures. It would seem reason- 
able, however, to suppose that both the morbid- 
ity and mortality from the traumatic factor 
could be greatly reduced by a properly organ- 
ized and functioning rescue system, instituted 
early. Once the casualty is in the hands of 
medical personnel, treatment itself should pre- 
sent no unique problem other than that of 
materiel. It might be important to treat these 
cases (particularly the lacerations) vigorously, 
and in a definitive manner, all possible effort 
being made to effect healing within the first 
two weeks, for thereafter, the major effects of 
irradiation sickness begin to appear. If the 
casualty were close enough to the hypocenter 
to receive much ionizing irradiation, irradia- 
tion sickness resulting, his unhealed wounds 
would break down, infection of uncombatable 
degree would supervene, and death ensue from 
even a relatively minor injury. 
The largest, and most important category 
(numerically) of atomic bomb injury is the 
burn. This group of injuries also can be di- 
vided into primary (due to the bomb, per se) 
and secondary (due to burning buildings, etc.) 
(Table I). Tsuzuki (108) estimated that about 
90 percent of patients treated within the first 
few days were burned. LeRoy (71) estimated 
that less than five percent of the burns were 
caused by the fires in buildings and debris. 
There then remains a group consisting of about 
85 percent of all casualties treated within the 
first week who were suffering from primary 
atom bomb burns. 
The energy which produced this high inci- 
dence of primary burns, had certain charac- 
teristics. The heat was intense, and largely 
radiant, with extremely high ultraviolet, vis- 
ible, and infra-red components. The exposure 
was very brief—probably less than a second 
(Table II). 
Table II 
Components of Atomic Bomb Flash (2) 
Temperature Est. at over 4000° C. 
Transmission Largely by radiation. 
Spectrum High in Ultraviolet. 
High in Infra-Red. 
High in visible light and 
brilliancy. 
Duration Less than a second. 
As with the traumatic factor, the thermal 
effects were closely related to the distance from 
the ground center of the explosion (Fig. 3), the 
heaviest damage being within the 0.8 km. 
radius, the severity diminishing to practically 
Dr. Pearse obtained his A.B. from the Uni- 
versity of Missouri in 1921 and his M.D. from 
Harvard University in 1925. He received his 
surgical training at Johns Hopkins Hospital and 
the Strong Memorial Hospital at Rochester, New 
York. Since 1927 he has been Assistant Instruc- 
tor, Assistant Professor, Associate Professor, 
and Professor of Surgery at the University of 
Rochester School of Medicine. Dr. Pearse was 
a member of the Radiological Safety Section 
at Operations Crossroads at Bikini in 1946; was 
Special Consultant on the Atomic Bomb Casualty 
Commission National Research Council; studied 
the Japanese casualties at Hiroshima and Naga- 
saki in 1947 and is currently the Responsible 
Investigator for the Section on Flash Burns and 
Consultant to the Atomic Energy Project, Roch- 
ester University. 
Dr. Payne received his M.D. degree from 
Vanderbilt Medical School in 1942 and after a 
year of surgical internship, served- for three 
years as a Medical Officer of the U. S. Army, 
participating in the Italian Campaign. Following 
two years of postgraduate surgical training, he 
was appointed as a Section Chief of the Flash 
Burn Program in the University of Rochester 
Atomic Energy Project. 
72 RADIOLOGICAL DEFENSE 
nothing at 4 km. Because the thermal energy 
was largely radiant, effects were modified by 
shading of buildings, and the angle of incidence 
of energy. Clothing served as sufficient protec- 
tion in some cases, light colored clothing being 
better than dark; however if the clothing were 
adherent to the skin by perspiration, burning 
occurred even through this protection. 
The burns produced were of varied severity 
and distribution. “Profile” burns were common 
(Fig. 4), the parts directly exposed to the 
flash being burned most severely. Mild burns 
occurred, without vesication. These burns were 
usually sustained beyond 2 km. from the center 
and were intensely erythmatous within the 
few days immediately after exposure. However, 
they gradually became pigmented finally at- 
taining a “walnut stain” hue. This was most 
commonly seen on the face and therefore was 
called the “mask of Hiroshima”. The pigmen- 
tation began to fade within a few months in 
some individuals, but in others has persisted 
for years (2) (Fig. 5). 
More severe burns, corresponding to second 
degree moderate temperature burns, were fre- 
quent, but apparently did not carry the high 
mortality for large areas, seen in the latter 
type of burn (Fig. 4). Vesication was present, 
and often appeared within a matter of min- 
utes. More severe burns were sustained, and 
complete transfascial burns were found among 
the dead. 
The course of these burns was, in some cases, 
benign, many healing with little or no treat- 
ment, despite some superimposed radiation 
sickness as well. However more often the heal- 
ing was arrested or the burn turned to a seri- 
ous one by the subsequent lack of treatment 
and resulting complications. The sequellae were 
remarkable for the large number of contrac- 
tures and the high incidence of keloids (Figs. 
6, 7, and 8) (higher than noted in flame burns 
in Tokyo and other Japanese cities (3)). Both 
of these complications may well have been due 
to the lack of adequate treatment and the ex- 
tremely poor nutritional state of these people. 
These keloids seem to become inactive with the 
passage of time. 
The low incidence of flame burns has been 
explained on the basis of the time lag between 
the bomb burst, and the onset of fires. It is said 
that people escaped the fires if they were not 
severely injured. Those trapped in burning 
buildings perished, and no reliable figures are 
available on their number. 
The care of a single traumatic or burned 
casualty, or a small group of casualties of such 
types as might result from an atomic bomb 
explosion, would present somewhat of a prob- 
lem. Certain essential supplies and facilities 
would be required. These would include: (1) 
surgical dressings of all types, (2) morphine 
and sedatives, etc., (3) Antibiotics and similar 
agents, (4) whole blood and plasma, (5) hos- 
pitalization and/or adequate shelter of some 
type, and (6) medical and technical personnel. 
The volume of materiel and the number pf 
personnel required to treat a single severely 
burned patient (approximately 40 percent of 
the body surface) in a modern hospital is illus- 
trated in Figure 9. Many such patients do not 
survive, despite such treatment. 
The figures given for casualties at Hiroshima 
and Nagasaki are given in Table III. From 
these it can be calculated that the severely 
burned group alone, at Hiroshima probably ex- 
ceeded 34,000! If it were necessary to treat all 
of these cases in a manner similar to the case 
illustrated in Figure 9, the requirements in 
personnel and equipment would be staggering 
(Fig. 10). 
Table III 
Atom bomb casualties (71) 
Hiroshima Nagasaki 
Population 300,000 200,000 
Dead 80,000 40,000 
Injured 40,000 25,000 
Patients in need of 
immediate care 85,000 50,000 
It seemed important, therefore, to reevalu- 
ate the modern therapy of burns, in terms of 
the burns produced by the atom bomb. This 
lesion has been called the flash burn. It is pro- 
duced by an extremely high intensity wave of 
radiant heat, applied over a very brief period 
of time. Experimentally, various types of burns 
have been defined. It has been found that the 
more intense the heat source, the briefer the 
73 RADIOLOGICAL DEFENSE 
Table IV 
Source 
Duration of 
flash in 
seconds 
Approximate 
temperature C° 
Burn 
produced 
Complication 
FT14 Xenon 
flash tube. 
0.002 
6300 
None 
Unable to focus energy. 
Exploding wire . . . 
0.00001 
20000 
None 
Unable to focus energy; 
too brief blast wave. 
Thermite 
Variable 
3500 
Not used 
Spatter, low intensity; han- 
dling difficulty. 
Gunpowder 
To 1.0 
3000 
Failed 
Low intensity. 
Magnesium 
0.34 
3500 
Severe 
Smoke. 
Carbon Arc 
Constant 
4000 
Severe 
Small area burn. 
A summary of various sources tried (86) 
period of time required to produce a burn of a 
given severity. This is shown graphically in 
Figure 11, and has been worked out in some 
detail for the lower temperature zones, by 
Henriques and Moritz (46) of Boston. However 
the darkened area (adjacent to the question 
mark) represents the flash zone, and is now 
being studied in detail in the laboratory. 
Experimentally, many problems arise in the 
production of flash burns in the laboratory. The 
search for a suitable source is one of the most 
difficult. iCertain criteria must be met to pro- 
duce an ideal flash: 
1. Transient duration on the order of 0.1 
second. 
2. Extremely high intensity, of a known 
degree. 
8. A known or obtainable spectral distri- 
bution. 
4. Safety and convenience of handling. 
Three general principles of flash production 
were tried: (1) the release of electrical energy 
from a bank of condensers to create a flash, (2) 
the creation of a constant high intensity source 
directed upon a target for known intervals 
by means of a shutter or trip mechanism, and 
(3) the use of substances that burn rapidly 
with an intense flame. The various sources 
tried, with appropriate comments, are listed in 
Table IV. 
The flash produced by burning magnesium 
powder, has been used clinically to produce a 
burn, therefore this agent was chosen (30). The 
burns produced by the burning magnesium 
flash, have several interesting characteristics, 
most strikingly demonstrated in the histolog- 
ical picture. Most remarkable is the abrupt 
and diagrammatic demarcation between burned 
and normal skin. The normal, basophilic epi- 
dermal cells change on a straight line, to the 
acidophilic burned cells which have all charac- 
teristics of thermal injury (Fig. 12). In the 
deeper skin, this demarcation is at the bum 
border, in the crypts and hair follicles. It is 
present in the dermis but is less easily demon- 
strated. There is no gradual transition zone 
as in the moderate temperature burns. An- 
other characteristic of the flash burn is the 
method of healing. The burned epidermis and 
dermis represents a coagulative “fixed” type 
of necrosis, with eschar formation and subse- 
quent sequestration, rather than the organiza- 
tion seen in the non-coagulative necrotic tissue 
of the moderate temperature burn. With a 
flash-burn of average severity the epithelium 
grows out freely (and indeed beautifully) from 
normal borders and hair follicles, beneath the 
unorganized eschar so that healing is rapid. 
Yet if the area is large and the injury deep 
enough to destroy the epithelium in the crypts 
and hair follicles, then this characteristic de- 
marcation will result in delayed repair from 
lack of epithelial islands (86). 
Other factors about these experimental flash 
burns are their similarity to the ones noted 
clinically. For instance, severity diminishes as 
the distance from the source increases. Cloth- 
ing and heavy creams seem to be adequate pro- 
74 RADIOLOGICAL DEFENSE 
tection at reasonable distances from the source. 
Severity also decreases with the angle of inci- 
dence. 
Despite the fact that more and more is being 
learned about the flash burn, little change in 
the accepted treatment of burns can be made 
as yet. It is possible that many of these burns 
will heal rapidly (if they are not too deep), 
provided adequate shelter and diet is provided 
the individual. The prevention of infection— 
by adequate dressings and antibiotics—will 
probably pay high dividends in the prevention 
of morbidity, sequellae, and uncalled-for fatal- 
ities. The entire problem is being studied from 
several approaches with some promise of a 
more practical and effective solution. 
In conclusion certain facts should be em- 
phasized. 
(1) Thermal and mechanical injuries ac- 
count for the majority of the casualties 
from an atomic bomb. 
(2) From the experiences in Japan, 90 per- 
cent of all persons requiring medical 
attention in the first week will have 
burns and 60-85 percent of all patients 
will be burned. 
(3) The burns are of the “flash” type, pro- 
duced by a high intensity, brief dura- 
tion source. They are of all degrees 
of severity, and while some may heal 
speedily with little treatment, this is 
by no means a general condition. Se- 
quellae and overall mortality probably 
will vary with the treatment. 
(4) Every effort should be made to evacuate 
the thermal and traumatic casualties 
early, and treat them vigorously, to 
reduce the incidence of complications 
from delay. 
75 RADIOLOGICAL DEFENSE 
AtOM BOMB BLAST DAMAGE 
Figure 2. The scarring resulting from multiple lac- 
erations sustained by flying glass fragments, as photo- 
graphed some nine months after injury. The wounds 
probably were infected as evidenced by the wide scars. 
(Photograph by Signal Corps, U. S. Army.) 
Figure 1. The relatively constricted zone of damage 
(in black) should be compared to the spread of thermal 
effects in figure 3 (2). 
ATOM BOMB THERMAL DAMAGE 
6.4 KMS 
Figure U. A flash burn of moderate severity and 
extent, photographed early in the course of healing. 
The distribution of the lesion shows that the patient 
was walking in an axis, perpendicular to the explo- 
sion, with the right side facing the bomb, the left arm 
swinging forward, to expose the medical surface, and 
the right arm hanging down by the side. The lack of 
burning in the sternal depression demonstrates the 
effect of even the little protection afforded by the pro- 
trusion of the right anterior chest wall. The eyes were 
not severely damaged, the swelling probably being 
attributable to the inflammatory effects of adjacent 
burns. (U. S. Army Medical Museum.) 
Figure 3. The range of thermal damage was probably 
the greatest of that due to any of the forces unleashed 
by the atom bomb explosion. Compare this with figure 
1 (2). 
76 RADIOLOGICAL DEFENSE 
Figure 5. A mild flash bum of exposed portions of 
the skin, as it appeared sixty-three days after the 
Nagasaki explosion. The protected portions are outlined 
by the undershirt. The burned portions of the face, 
shoulders, and arms, were of “walnut stain” color (9). 
Figure 6. Residua of a mild burn, with color changes 
between the burned area and the area protected by the 
slip, photographed two years after burning. Note the 
scarring beneath the right scapula, where the skin was 
burned through adherent or moist clothing. (Photo- 
graphed by Signal Corps, U. S. Army.) 
Figure 7. Contracture and ulceration resulting from 
an inadequately treated flash burn on the dorsum of 
the right wrist, photographed two years after burning. 
(Photograph by Signal Corps, U. S. Army.) 
Figure 8. Keloids following an extensive flash burn 
of the hack, photographed twenty months after the 
injury. The uneven distribution of the keloid over the 
burned area is characteristic. (Photographed by Signal 
Corps, U. S. Army.) 
77 RADIOLOGICAL DEFENSE 
MINIMUM MATERIALS AND PERSONNEL NEEDED TO TREAT 34,000 
SERIOUS BURN CASES 
PERSONNEL AND MATERIALS 
NEEDED TO TREAT ONE MAN 
WITH A 40% BURN 
Figure 9. Composite representation of materials and 
personnel required in the treatment of one patient with 
a UO percent “moderate temperature” burn. Data rep- 
resents the actual situation for a patient treated in a 
University hospital in the summer of 19U7. Subsequent 
hospitalizations for corrective measures are not in- 
cluded in this picture. 
Figure 10. The multiplication of the data in Figure 9 
by an estimated number of severe burns from an atomic 
bomb explosion over a city of 300,000, results in stag- 
gering total requirements! 
FLASH AND FLAME 
THERMAL INJURY 
CURVE. 
Figure 11. Using the separation of the epidermis 
from the dermis as an end point, Henriques and Moritz 
(6) demonstrated the relationship of time and tempera- 
ture in the production of thermal injury. This graph 
is a simplified, composite representation of this concept. 
Studies of thermal effects within the moderate tem- 
perature ranges are fairly complete, however in the 
extremely high ranges, little has been done. In this zone 
(shaded in the graph and indicated by the question 
mark), many factors come into play, which can be ig- 
nored in the lower temperature, longer time zones (11). 
Figure 12. Biopsy of skin taken immediately after 
the production of a magnesium flash burn on the side 
of an anesthetized pig. The abrupt lateral demarcation 
is seen in the epidermis—normal epidermis being to 
the left and burned to the right. This picture is charac- 
teristic of the flash bum. 
78 RADIOLOGICAL DEFENSE 
INTERNAL HAZARDS OF FISSION PRODUCTS AND PLUTONIUM 
By 
Department of Radiobiology 
Army Medical Department Research & Graduate School 
Capt. Robert J. Soberman, MC, USA 
Army Medical Center 
We are faced today with radiation problems 
on a scale that never before existed. It is esti- 
mated that up until the recent war there were 
about 1,000 grams of purified radium in the 
entire world. We are now told that the amount 
of radioactivity in the column of water in the 
second test at Bikini was not of the order of 
1,000 grams, but in the range of 100 tons 
(100,000,000 grams). It is apparent that this 
is no small isolated problem, but one of wide 
scope and great magnitude. 
Before we proceed to discuss the detailed 
problems related to the internal hazards of the 
fission products of the atomic bomb, let us con- 
sider briefly those properties of ionizing ra- 
diation which make them dangerous to the 
body, namely the ability to ionize and to pene- 
trate tissue. Whether we deal with alpha or 
beta particles, X-rays, or neutrons, the effect 
of all these radiations is the release of energy 
within the cells by the production of ion pairs. 
Survival or death of the cell depends upon the 
location of this process, and if a vital cellular 
constituent is affected, a lethal effect will re- 
sult. A measure of the ionizing effect of ra- 
diation is the roentgen. It is a quantity of 
gamma or X-radiation that produces 1.6 X 1012 
ion pairs per gram of air, or the absorption of 
83 ergs per gram of air under standard condi- 
tions. The roentgen equivalent physical or rep 
is that amount of radiation of a or /3 rays 
which produces energy absorption of 83 ergs 
per gram of tissue. The rep depends upon the 
type of radiation because of the variation of 
ionizing density for different types of radiation. 
The roentgen equivalent man, or rem, is the 
amount of energy absorbed in tissues which is 
biologically equivalent in man to one roentgen 
of gamma or X-rays. The rem is not only 
dependent upon ionization density, but also 
upon the chemical composition of the tissue and 
the species of organism irradiated. If we re- 
member that the specific ionization of a particle 
varies directly with the square of the particle 
charge and inversely with its speed, we can see 
that biological effectiveness varies with the 
type of radiation. For example, one rep of beta 
rays is equivalent to one rem; one rep of alpha 
rays is equivalent to 10 rem. This property of 
specific ionization, which depends upon the 
speed and charge of a particle, is counterbal- 
anced by the ability of this particle to pene- 
trate tissue. Alpha particles with a mass of 
four and a charge of two can only penetrate 
tissues to a depth of about 0.1 mm; beta par- 
ticles, 5-10 mm; and gamma rays and neu- 
trons, many times greater than beta particles. 
Thus we can see that the external hazard of 
alpha particles with their slight penetrating 
ability would be negligible as compared to the 
highly penetrating gamma rays. The internal 
hazard of alpha particles, with their high spe- 
cific ionization and biological effectiveness, 
would be great as compared to beta or gamma 
rays. 
In considering the effects products may have 
upon the body, one would have to take into 
account the mode of entrance — oral, respira- 
tory or direct injection (cuts, etc.) into the 
body and the amount of retention and excretion 
and selective localization. These factors — de- 
gree of absorption (gastro-intestinal tract, 
etc.) and selective localization, e.g. bone, and 
inhalation — depend in part upon solubility 
and particle size. In this connection the con- 
cept of biological half-life, the time required 
for one-half the material to be excreted, and 
the effective half-life, the time required to lose 
one-half of the material by the combination 
of excretion and radioactive decay should be 
kept in mind. If the material is readily excre- 
ted, it will not cause great damage; if it is not 
79 RADIOLOGICAL DEFENSE 
excreted, the half-life of the element involved 
becomes important. If a substance with a long 
half-life is poorly excreted, there is a very real 
risk, especially if the element is an alpha 
emitter. Incidentally, it is elements with these 
characteristics that chiefly concern us. Certain 
radioactive materials or their breakdown prod- 
ucts are also chemically dangerous. Strontium, 
a common product of fission, is a poison. 
In considering the effects of radiation on the 
body tissues, it is necessary to distinguish be- 
tween the effects of total body and localized 
radiation. How much total radiation can the 
body withstand? Which tissues are most sus- 
ceptible to radiation? Doses from 350 to 600 
roentgens are within the lethal range for total 
body radiation. This means each gram of the 
body receives 350-600 r. The therapeutic range 
is ten times this amount because radiation used 
for therapy is restricted to a small area of the 
body, and the total amount of tissue irradiated 
is relatively small. It has been found that after 
subjecting the total body to radiation, some 
tissues are much more susceptible than others. 
As a general rule, the effect on tissue is di- 
rectly proportional to the shortness of the 
tissue’s life (the mitotic cycle). Thus bone 
marrow, lymphoid tissue, and germinal epithe- 
lium are very sensitive as compared to nerve 
cells, which require more than 20,000 roentgens 
to kill them. Reasoning teleologically, one 
might say this is a protective mechanism for 
once a nerve cell dies, it is not replaced. 
Current standards in this country permit a 
dose of .05 r per day or 0.3 r per week over the 
entire body. It is desirable, however, that any 
chronic daily exposure be kept as far under 
this as possible. Compare this dosage with 
somewhat more familiar experiences: A rou- 
tine chest X-ray delivers 1-2.5 r to the chest; 
chest fluoroscopy delivers 30-40 r to the chest; 
dental X-ray may give the tongue as much as 
30 r; a GI series delivers approximately 40 r 
to the abdomen. Of course these are examples 
of nonchronic local radiation, and as such do 
not constitute a hazard. 
The greatest hazard that arises from the re- 
lease of nuclear energy as a result of the atomic 
bomb is radiations produced directly from fis- 
sion and subsequently emitted by the resultant 
fission products and plutonium. 
This discussion will not deal with the haz- 
ards of external radiation so we can omit the 
immediate effects resulting from a bomb explo- 
sion. A correct and thorough understanding of 
the hazards of the fission products not only 
necessitates a knowledge of their radioactive 
characteristics, but also of the manner in which 
they are handled by the organism, namely their 
metabolism within the body. 
The fission of uranium results in the produc- 
tion of 34 radioactive elements, extending from 
zinc to europium. Many fission products have 
been prepared, isolated, and subjected to meta- 
bolic studies. These studies, which were per- 
formed on adult rats, have resulted in informa- 
tion concerning the absorption, distribution, 
retention, and excretion of these fission prod- 
ucts. The radio-chemically pure and carrier- 
free elements were administered by parenteral 
injection, stomach tube, and intratracheal in- 
tubation. The quantity of radioactivity was 
such as not to alter the normal metabolic state 
of the experimental animal. I will not go into 
the exact details of procedure of these experi- 
ments. These are reported by J. Hamilton in the 
July 1947 issue of Radiology. These studies 
have shown that most of the fission products 
and all of the actinide elements (elements above 
actinide on the periodic table) are not absorbed 
to a significant degree by way of the digestive 
tract. Of all the fission products which have 
been investigated, only strontium, barium, tel- 
lurium, iodine, and cesium are absorbed from 
the digestive tract to a significant degree. Fol- 
Capt. Soberman graduated from the New York 
University Medical School in 1946. He interned 
at Bellevue Hospital and completed a year as a 
Research Resident with the New York University 
Research Service at Goldwater Memorial Hos- 
pital in New York City. Capt. Soberman entered 
the Army in 1948 and was assigned to the De- 
partment of Radiobiology at the Army Medical 
Department Research and Graduate School, Army 
Medical Center, Washington, D. C. During the 
past three years, he has utilized the various 
radioactive isotopes in the course of his research 
and in the diagnosis and treatment of patients. 
80 RADIOLOGICAL DEFENSE 
lowing parenteral administration, they are ac- 
cumulated in the skeleton and eliminated from 
this organ very slowly. Xenon is rapidly ab- 
sorbed through and is readily eliminated from 
the lung. Strontium and barium are retained 
to a high degree by the skeleton. Iodine con- 
centrates in thyroid. Tellurium accumulates 
somewhat in the kidney and blood, and it is 
released rapidly from these tissues. Cesium is 
distributed uniformly and is excreted rapidly. 
With the exception of ruthenium, the remain- 
der of the fission product series and all of the 
actinide elements accumulate largely in bone 
and are retained for a long period of time. 
With few exceptions, the rates of elimination 
of the different fission products that are 
accumulated in the skeleton are less than their 
rates cf radioactive decay. However, rubidium, 
tellurium, xenon, and cesium are rapidly ex- 
creted at rates greater than their half-lives. 
As has been stated before, the rates of elim- 
ination of the actinide elements from the skele- 
ton are slow and in the case of plutonium, the 
excretion in the rat falls to 0.01 percent per 
day of the amount remaining in the body 
within a year following the intramuscular ad- 
ministration of this element. 
The direct introduction into the lung of solu- 
tions of carrier-free fission products and plu- 
tonium showed that those elements which were 
not absorbed from the digestive tract were 
retained to a considerable degree for a pro- 
longed period of time by the lungs. The distri- 
bution in the lung was in the alveoli. Since 
absorption took place through the lung, the 
absorbed material was deposited in the bone as 
expected. Those elements which were readily 
absorbed through the digestive tract were also 
absorbed readily through the lungs. A series 
of aerosol inhalation studies revealed that 
about 75 percent of the material inhaled was 
retained in the rat; this was equally divided 
between the upper and lower respiratory tract. 
The 38 percent in the upper respiratory tract 
rapidly disappeared and was recovered in the 
feces. About 10 percent of inhaled plutonium 
aerosol was absorbed in the first 48 hours and 
deposited in the skeleton. Eight months after 
exposure 4 percent of the total quantity inhaled 
still remained in the lung. 
Thus we see a great predilection of the long 
life fission products and actinide elements for 
deposition and retention in the skeleton. With 
the exception of strontium which is deposited 
in the mineral structures, these elements ap- 
pear to be localized in and adjacent to the 
osteoid matrix, placing them in a class with 
radium as far as bone retention is concerned. 
Once the radioactive element has been in- 
corporated into the tissues of the body, what 
are the resultant effects? These have been pre- 
sented to you in the previous lecture. However, 
I wish to stress the long-term effects of minute 
amounts of radioactive material found in the 
body. It has been shown that the incidence of 
carcinoma in susceptible mice increases mark- 
edly when they are exposed to known amounts 
of radiation. This evidence corroborates the 
facts learned from studies of the radium dial 
workers before protective measures had been 
instituted. I think it would not be amiss to dis- 
cuss these in some detail since much of what 
we know of the long-term effects of internal 
radiation in humans has been learned from 
cases of radium poisoning. In 1924 Blum and 
Hoffman suggested that radium produces ne- 
crosis of the jaw. In 1925 Martland, Caske and 
Krinker described independently similar ef- 
fects in the jaws of workers who had absorbed 
radium salts. Other abnormal clinical results of 
radium have been the high percentage osteo- 
genic sarcoma and the appearance of severe 
anemias. 
It had been the practice to moisten the brush 
used for painting radium dials by placing it in 
the mouth. In this manner significant amounts 
of radium were absorbed. If the amount of 
radium deposited is large (10-100 micro- 
grams) , clinical symptoms of acute radium 
poisoning including leukopenia, lymphocytosis, 
osteomyelitis, necrosis and other tissue lesions 
may be seen within a year or two. In chronic 
radium poisoning, where the body contains 
1-10 micrograms of radium fixed in the skele- 
ton of the body, usually no symptoms appear 
until five to fifteen years after the exposure. 
81 RADIOLOGICAL DEFENSE 
Bone necrosis and osteogenic sarcoma are often 
seen terminally. 
Five micrograms of radium in the body will 
deliver 1 rep per day to the bone. Ten rep/day 
for a period of fifteen years will usually result 
in osteogenic sarcoma (calculated from study 
of cases of radium dial workers). However, 
due to wide variation in individual resistances, 
cases are known to have resulted fatally when 
the radium content of the body was between 
1.2 to 2 micrograms of radium. 
Measurement of the Total Amount of Radium 
in the Body. Radium disintegrates into radon 
which in 8 steps disintegrated into a non-radio- 
active form of lead. One of these steps is 
radium C, which emits a penetrating gamma 
radiation, which can be detected with the aid 
of suitable equipment outside the body. How- 
ever, not all of the radium in the body reaches 
the stage of radium iC since about 45 percent 
of the radon formed is exhaled from the lungs. 
Thus, if one determines the amount of radon 
exhaled and the amount of radon which has 
disintegrated to radium C in the body, an esti- 
mate of the total amount of radium in the body 
can be made. 
The principle of determining the amount of 
radioactivity stored in the body by assaying 
the radioactivity in the excretory products— 
urine, feces, and exhaled air—can be applied 
to other elements as well. 
The rate of radium loss by the patient is 
directly measured by analysis of the feces and 
urine; over 90 percent of radium taken orally 
is eliminated within five days; for chronic cases 
0.005 percent is eliminated per day, 91 percent 
in the feces and 9 percent in the urine. 
Once radium is found in the skeleton of the 
body, what measures can be taken to hasten 
the rate of excretion? Since radium is deposi- 
ted in bone in a fashion similar to that of 
calcium, any procedure that would increase the 
turnover of calcium and hasten its excretion 
would similarly affect radium and incidentally 
other elements having the same properties as 
far as bone deposition is concerned. Such 
agents as parathormone, ammonium chloride, 
thyroid extract, etc. increase the rate of radium 
excretion. However, this is to no avail although 
the rates of radium excretion are increased 
5-10 fold, the amount of radium which is with- 
drawn is not sufficient to significantly lower 
the determinations of total stored radium in 
the body. 
Thus we see that although it is difficult to 
get a sizeable amount of any of the fission prod- 
ucts or actinide elements into the body, it is 
equally difficult to get even a small amount out 
of the body after it has been deposited in the 
bone and other tissue. We see too, that it is 
not necessary to have a large amount in the 
body to result in harmful effects; a small 
amount of a radioactive element, especially an 
alpha emitter, whether it be stored in the lung 
or skeleton, acting over a long period of time, 
will damage the tissue and may eventually re- 
sult in a malignant tumor. Once the radioactive 
material is fixed in the tissue, there is no 
known method to neutralize the radiation 
source or effectively increase the excretion rate. 
Prevention, rather than cure, is the only satis- 
factory measure available at the present time. 
82 RADIOLOGICAL DEFENSE 
PUBLIC HEALTH ASPECTS OF ATOMIC ENERGY 
By 
Medical Director Edwin G. Williams 
Chief, Radiological Health Unit 
Bureau of State Services 
U. S. Public Health Service 
Public Health is that branch of medicine 
which deals with the relationships between in- 
dividuals and the community. The concept of 
public health is fluid and changing. There was 
the “Hygienic” era with its abolition of the 
roller towel; the “Prophylactic” era, so well 
known to military men and those of the dental 
profession. At the present time the emphasis 
is shifting from the negative — absence of 
disease — to the positive, presence of health. 
Through it all permeates the philosophy of a 
general bonification of the environment in 
which we live. The mere vastness of the field 
carries with it the danger of loss of perspective. 
This leads to the expending of undue effort on 
relatively unimportant aspects at the expense 
of those which should have priority. A reten- 
tion of perspective becomes increasingly neces- 
sary in warfare or other widespread emer- 
gencies. 
ASSESSMENT OF HAZARD 
You as medical officers will be called upon to 
assess the hazard and to advise the command 
accordingly. You will probably have the neces- 
sary physical findings supplied to you. The 
presence or the magnitude of the hazard will 
depend upon many factors. You will frequently 
need the advice of not only the physicist (En- 
gineer Corps or other specially trained line 
officer) but also of such disciplines as meteor- 
ology, geology and hygrography. In damp or 
rainy weather there is little dust, therefore, 
ground contamination will not be as serious 
from an internal (inhalation) standpoint as 
during dry conditions. 
In assessing the hazard keep ever in mind 
that external radiation is more easily dealt 
with than internal radiation. You can guard 
against external radiation but you must pre- 
vent internal radiation. Decontamination of the 
skin, though at times difficult, is far easier 
than decontamination of the liver, lungs or 
bone. 
Personnel monitoring devices are of many 
kinds. Most usual at the moment are: 
a. Film meters. 
b. Pocket ionization chambers. 
c. Pocket electroscopes. 
d. Geiger-Mueller tubes. 
Area monitoring instruments include: 
a. Geiger-Mueller tubes. 
b. Electroscopes. 
c. Ionization chambers. 
d. Film meters. 
e. Dust or air sampling devices. 
Let us assume that an area is contaminated. 
It may be contaminated with: 
a. Alpha emitters. This will constitute a 
most serious hazard if such substances 
gain access to the interior of the 
body. There will be no external radi- 
ation hazard. 
b. Beta emitters. This will constitute 
both external and internal radiation 
hazard—more serious per unit if in- 
ternal. 
c. Gamma emitters. Here again we must 
think of both external and internal 
hazards, more serious from a practi- 
cal standpoint as an external hazard. 
d. Combination. Contamination will al- 
most certainly not be limited to one 
of the above types of radiation. 
ADVICE AS TO EATING FOOD 
IN CONTAMINATED AREA 
It must be assumed that all food found in 
the area is dangerous. The food may contain 
induced radioactivity. This is unlikely to be 
present in dangerous quantities because of 
generally unfavorable reactions, and because of 
short half-life of many substances. You as med- 
ical or veterinary officers will, however, prob- 
83 RADIOLOGICAL DEFENSE 
ably be called upon to give an opinion in these 
cases. 
The food may have deposited radioactivity 
on its surface and this is most likely to be the 
case. Here, as in many cases, decontamination 
will be impractical or impossible. Canned or 
otherwise protected foods may be eaten only 
after careful inspection and most rigorous and 
wise attention to detail of removing the food 
from the protecting agent. 
If it is necessary to bring food into the area, 
a high degree of precision must be maintained 
in the handling of it. 
Livestock 
A serious food supply situation may arise as 
a result of bombing near large stock yards. 
Let us assume that the stock, be it cattle, sheep, 
swine or other, has probably received a lethal 
amount of radiation but that many have sur- 
vived the blast effect. Let us further assume 
that there has been no appreciable fall-out, and 
that we are in the area shortly after the deto- 
nation. We are therefore dealing with animals 
suffering from external irradiation. To be sure 
there will be some induced radioactivity but 
this will be of so small an amount as to be 
negligible. The animals could therefore be 
slaughtered and the meat saved for food. This, 
along with all operations in the area must of 
course be carried on under the surveillance of 
the radiological defense or safety group. If the 
area is contaminated and the stock has been 
eating contaminated food for a few days, the 
picture is considerably more complicated. Hides 
and viscera will be contaminated and should 
be removed and handled in such a way as not 
to contaminate the meat. Meat must be care- 
fully examined for radioactivity and discarded 
if more than a trace is found. If time is avail- 
able and other conditions permit it may be well 
to consider moving the stock to non-contami- 
nated areas and feed on non-contaminated food. 
The physical and biological half-life will lead 
to less highly contaminated animals and the 
shifting of elements during metabolism will 
shunt most of the more harmful elements away 
from the muscle. In contemplating such a move, 
the feasibility of properly handling contamina- 
nated excreta and slaughter house offal must be 
considered. It is reasonable to expect milk pro- 
duced by an internally contaminated cow to 
contain radioactive elements. Here one must 
be guided by the facts as they present them- 
selves, If the milk is contaminated, centrifuge 
and test the cream and skimmed milk sepa- 
rately. If only one portion is contaminated, the 
other portion may be used as food. If both are 
contaminated, the degree of contamination 
must be weighed against the need for the food. 
Remember that field detecting instruments 
were not designed for this purpose and a low 
reading may indicate serious contamination. 
Contaminated hides, excreta, and slaughter 
house offal may best be disposed of by burial in 
the contaminated area. 
ADVICE AS TO THE DRINKING OF WATER 
IN THE CONTAMINATED AREA 
If possible no water should be drunk in the 
area. If canteens are to be taken in, troops 
must be drilled in the matter of drinking with- 
out contaminating the mouth of the canteen. 
Large amounts of water may have to be taken 
in — this greatly increases your responsibility. 
The water in an area may be contaminated 
as a part of the general area contamination or 
may have become contaminated up-stream. 
What can be done about decontamination? 
1. Physical. 
a. Boiling. This is obviously useless or 
may be harmful. It is unlikely that 
all contaminants will be volatile. 
Boiling will then serve only to con- 
In 1924 Dr. Williams received his B.S. degree 
and in 1926 his M.D. from Emory University. 
He was commissioned in the U. S. Public Health 
Service in 1929. During the period 1945 to 1948 
he did extensive research and field work in radio- 
biology and from 1946 to 1948, research and 
supervision of radiation protection at the Na- 
tional Institute of Health. He has been Chief of 
the Radiological Health Unit, U. S. Public Health 
Service since 1948. Dr. Williams is a member of 
the National Committee on Radiation Protection. 
He participated as a member of the Radiological 
Safety staff at Joint Task Force One at Bikini 
in 1946. 
84 RADIOLOGICAL DEFENSE 
centrate and increase the contamina- 
tion. 
b. Storage. This time-honored and often 
successful method of water purifica- 
tion, though useful for short-lived 
isotopes, is impractical for field op- 
erations and of little benefit for long- 
lived isotopes. 
c. Filtration. Here we may be some- 
what more hopeful—especially hope- 
ful since experimental work is being 
done and the value of filtration as 
can be applied in the field will be 
established. 
2. Chemical. 
In the sense of applying the usual 
water purification techniques (chlo- 
rine) this is obviously useless. 
3. Physico-chemical. 
If we can combine precipitation and 
filtration, we may greatly reduce the 
load on filtration. Here again meth- 
ods must be developed that are ap- 
plicable to the field. Experimental 
work is being done by the Atomic 
Energy Commission and the Armed 
Forces to evaluate existing purifica- 
tion methods and develop new tech- 
niques or modify existing methods. 
4. Biological, 
Although activated sludge is usually 
thought of as being applicable to 
sewage and waste treatment, biolog- 
cal processes may well lend them- 
selves to the problems of water de- 
contamination. Such methods would 
not seem to be adapted easily to 
field requirements. 
PREVENTION OF DISSEMINATION 
Prevention of dissemination by personnel is 
often of great importance. The underlying 
principles are always the same and may be 
illustrated by a discussion of the evacuation 
of an area. 
1. Decontamination center for area evac- 
uation. 
a. Clothing change and bathing facili- 
ties. 
b. Laundry (decontamination) facili- 
ties. 
c. Monitoring facilities. 
d. Eating and surgical dressing only on 
“clean” side. 
2. On entering contaminated zone. 
a. Remove all clothing (or outer cloth- 
ing). 
b. Leave all smokes and eats behind. 
c. Go to “dirty” side and put on work 
clothes (overalls, hat, gloves, and 
boots). 
3. On leaving contaminated zone. 
a. Remove hat and gloves. 
b. Wash face, neck, and hands thor- 
oughly five times with soap and 
water. 
c. Remove remaining clothing. 
d. Soap and thoroughly wash entire 
body five times. 
e. Go to monitoring room (between 
shower and clean side). 
f. With permission of monitor go to 
clean side and put on original cloth- 
ing. 
MORTUARY CONSIDERATIONS 
Morticians and others having to do with the 
dead will be guided by the same principles and 
employ the same general precautions as will 
the evacuation parties and first aid groups. 
Irradiated bodies do not constitute a radiation 
hazard; contaminated bodies must be handled 
with the same precautions as apply to other 
contaminated objects. 
Mortuary considerations may be discussed 
under three headings as to time and circum- 
stances. 
1. Air Burst 
a. Any time after explosion. 
There is no radiation hazard to be 
anticipated since there will be no appre- 
ciable contamination and induced radio- 
activity will not be sufficiently great to 
endanger the mortician or his staff. This 
assumption must be checked by the Ra- 
85 RADIOLOGICAL DEFENSE 
diological Safety group and if verified, 
the bodies may be handled without re- 
gard to further radiation precautions. 
2. Burst leaving appreciable contamina- 
tion. 
a. Immediate handling of bodies. 
For purposes of identification, burial 
on the site or removal for burial, the 
mortician and his staff must work under 
the continued advice of the Radiological 
Safety group. The first question is, of 
course, how long can the party stay in 
the contaminated area. The answer will 
be based upon the type and degree of 
contamination. Protective clothing will 
be worn. Ordinarily, where possible, this 
will be light weight disposable clothing, 
covering head, hands and body. If prac- 
tical, bootees will be worn over shoes, 
but in field operations a change of shoes 
may be necessary. If the bodies are to 
be buried in the area without embalm- 
ing, it will be necessary only to handle 
them in such a way as not to transfer 
contamination to the worker. For this, 
protective clothing and reasonable care 
will suffice. 
If they are to be embalmed and moved 
out of the area, they should go through 
the decontamination procedure in much 
the same way as evacuees but the degree 
of decontamination need not be so 
thorough, i.e. contaminated clothing and 
readily removable surface body contam- 
ination should be removed. For ease of 
operation, rubber gloves may be used in 
place of cotton gloves for embalming 
procedures. 
b. Later disinterment and shipment. 
This will usually occur sufficiently 
long after the explosion so that the 
amount of radioactivity will be greatly 
reduced. Therefore there will be little 
question as to hazard to the mortician. 
He will be guided in this regard by 
Radiological Safety advisors. Since the 
bodies will be in sealed caskets, there 
will be no serious question of contami- 
nating the areas to which they are sent. 
86 RADIOLOGICAL DEFENSE 
RADIOACTIVE DECONTAMINATION PROBLEMS 
CDR. £. J. Hoffman, USN 
By 
Chief, Radiological Safety Branch 
Ship Technical Division 
Bureau of Ships 
I have been asked to speak to you today on 
Radiological Decontamination Problems. This 
is a rather broad field and consists of several 
entirely different classes of problems to some 
of which the solutions are currently in a satis- 
factory state of development and others which 
are completely in an unknown stage. I will en- 
deavor to cover such things in two phases 
depending upon how the contamination is re- 
ceived. The first of these is the ordinary con- 
tamination that may be received incident to the 
use of radioisotopes in the laboratory. The sec- 
ond of these is the considerations governing 
contamination received incident to use of nu- 
clear weapons in wartime. The measures re- 
quired to cope with contamination received by 
these two greatly different avenues are radi- 
cally different. 
I will consider the easy phase first. This is 
the problem of laboratory contamination. The 
best way to handle this type of contamination 
is to prevent it from occurring. This sounds 
like a trite statement but it is surprising that 
sufficient care is not always used to prevent 
unwanted radioactive materials from accumu- 
lating in places where they are not desired. 
The chief help in handling of isotopes is ac- 
curate and detailed planning of each operation 
that involves moving of the radioactive mate- 
rial. The commonest form of unwanted contam- 
ination is the contamination of glassware and 
counting equipment. The second form of un- 
wanted contamination is that resulting from 
spills or unforeseen escape of materials. The 
third results from the disposal of materials 
upon completion of a test or experiment. In 
medical research the commonly used isotopes 
are in two general classes; those of relatively 
short half-life such as Phosphorous (P-32), 
Sodium (Na-24), Iodine (1-131), and longer 
half-lived materials extending to Carbon (C-14) 
with a half-life of approximately five thousand 
years. A laboratory is more apt to accumulate 
contamination when relatively long half-lived 
materials are used. The contamination received 
in the laboratory will, of course, vary with the 
uses to which the radioactive isotopes are being 
put. If these materials are in some stage of 
process employed as a gas or compound with 
high vapor pressure, it may be expected that 
contamination will be more difficult to control 
and be somewhat more general. The methods 
of controlling contamination involve keeping 
track of the isotope from its receipt until its 
ultimate disposal. 
It is desirable to restrict the area in which 
the isotopes are used to the minimum consis- 
tent with satisfactory working conditions. All 
desks, floors, bulkheads and apparatus that are 
essential in this space should preferably be 
protected by a semi-permanent removable cov- 
ering similar to “Tygon” plastic. Such material 
in the room which cannot be covered with the 
readily removable coating can be covered with 
paper or other temporary covering when dan- 
ger of spills, or other contamination may take 
place. When using the isotopes that have been 
noted, decontamination will consist of just 
plain scrubbing and washing with solutions 
that are known to be effective in rendering 
the tagged compound employed soluble and 
subsequently disposing of the washing solu- 
tions. Obviously the minimum amount of wash- 
ing solution will be desirable in order to re- 
duce the bulk of the residue for disposal. When 
a space has been used for a considerable period 
of time with some of the longer half-life iso- 
topes, it may become necessary to remove the 
entire temporary coating and re-coat before 
resuming work. In carefully controlled experi- 
mental work the purpose for decontaminating 
will often be to reduce the background of 
counting equipment used, less frequently per- 
87 RADIOLOGICAL DEFENSE 
sonnel hazards of the 0.1 r variety will be en- 
countered. 
There are, of course, a great many isotopes 
that offer much different problems. They are 
not commonly used by the medical profession 
but they may be used in the future since they 
are becoming more available and may behave 
differently from a chemical or hazard stand- 
point. For all such small scale decontamination, 
radical changes in principles are not to be ex- 
pected. If extensive work is planned with com- 
pounds which embody radioactive materials, 
it would be advisable to seek the chemical be- 
havior of such compounds in the non-radioac- 
tive state to insure knowledge of the best wash- 
ing compound to remove. It will be found that 
when the radioactive isotopes are added, they 
will behave in the same manner as the non- 
radioactive material upon which property de- 
pends their first usefulness. 
We now come to an entirely different type of 
contamination and decontamination. This is the 
type which may result from the employment of 
nuclear weapons in warfare. As you no doubt 
know, there is not one but literally hundreds 
of isotopes produced in an explosion of an 
atomic bomb. Furthermore, when contamina- 
tion is received, it is received by an area to 
which a great deal of preparation has not been 
feasible. At the time contamination is received 
it will be accompanied by panic and probably 
physical destruction. In other words, contami- 
nation is received under completely uncon- 
trolled conditions and by generally unprepared 
areas. We will not be thinking of hazards of the 
0.1 r variety but of exposures that cause biolog- 
ical damage in a comparatively short time. 
The considerations which govern the decon- 
tamination process will vary depending upon 
the method by which the radioactive materials 
are spread. The first objective will be to pro- 
tect and reduce the exposure of personnel in 
the area subjected to contamination. The second 
will be to restore an area to unrestricted use, 
if practicable, but failing that to at least par- 
tial operability. We can do little more than 
explore the considerations which are involved 
in the protection of personnel that are subjec- 
ted to contamination. Because of the short half- 
life of bomb fission products, it seems today 
that the only feasible method of protecting 
personnel is by evacuation to a heavily shield- 
ed area or to an uncontaminated area as rapid- 
ly as possible. In order to illustrate how the 
effect of decay limits one’s potential efforts we 
will cite a few figures: If one assumes that 
contamination from a bomb is received at + B 
minutes, the subject will receive fifty percent 
of the potential exposure in one hour and a 
half. If contamination is received at + 1 min- 
ute, fifty percent exposure will be received in 
30 minutes. 
In the practical solution the conditions are 
probably much worse than indicated due to the 
fact that considerable exposure of personnel is 
occasioned during the process of distributing 
contamination. These figures are cited to illus- 
trate that adequate decontamination will not be 
any panacea for the deleterious effect of widely 
distributed radioactive materials. 
I can probably lead you to the considerations 
which would indicate when decontamination 
might be required from atomic bomb detona- 
tion. With an air burst it is unlikely that se- 
vere contamination will be received in the im- 
mediate area affected by the burst of the bomb. 
It will, if it occurs at all, be due to freak at- 
mospheric conditions which have not been ex- 
perienced to date and result in contaminating 
an area some distance from the point of burst. 
Commander Hoffman graduated from the U. S. 
Naval Academy in 1936. After various assign- 
ments in which he utilized his engineering duty 
special training, he participated with the Hull 
Division of Ship Material at Bikini. He made 
major contributions toward solving problems of 
ship decontamination following Test BAKER. 
Upon his return from Bikini he became assistant 
to the Officer in Charge, Radiological Safety 
Section, San Francisco Naval Shipyard where 
he participated in the decontamination operations 
on the support vessels returned from Bikini. 
Later, as Officer in Charge, Radiological Safety 
Section, Bureau of Ships he developed a Radio- 
logical Safety program for the naval installations 
and laboratory at San Francisco. At the atomic 
tests at Eniwetok, he was in charge of a special 
project of considerable interest to the Bureau 
of Ships. He is presently stationed in Guam. RADIOLOGICAL DEFENSE 
The potential exposures that are probable in 
this instance are moderate. If, however, a 
bomb is detonated underwater or underground, 
contamination will be received in the vicinity of 
the burst over a considerable area but one 
which is distinctly limited, being of the order 
of several square miles. 
The statement that one bomb could contam- 
inate substantially the whole of New York City 
or San Francisco is ridiculous. The radioactive 
material will be spread uniformly over the area 
affected and will concentrate in those places 
which one would normally expect it to, as the 
result of its being suspended either in water or 
in dust. In the case of shore installations con- 
tamination resulting from an underwater burst 
will cause gutters, low spots, puddles and the 
like to be relatively “hotter” than the remain- 
der of the terrain. The decontamination re- 
quired in a shore establishment or a city area 
at the present time is seen as a project com- 
parable to removing evidence of the smoky his- 
tory of the city from many blocks of Pitts- 
burgh. It will of necessity be first restricted to 
those areas which are vitally important. I be- 
lieve that we can say that such areas as hospi- 
tal buildings and access thereto, communication 
centers, transportation centers, and possibly 
other installations will have enhanced impor- 
tance in event of atomic attack on a city. The 
methods of removal of contamination will vary 
with place or location which it is necessary to 
decontaminate. Obviously whatever method is 
employed on the outside of a building would not 
necessarily be suitable for an operating room, 
the methods employed on a concrete highway 
will not be satisfactory for clothing or food. 
Specific methods cannot be cited for the many 
varieties of material which it may be necessary 
to use after an attack. However, it must be 
remembered that the radioactive materials de- 
posited will behave exactly as any other com- 
pound, or dirt, that is deposited from a liquid 
or suspended in dust. It will be on the outside 
of tangible things. Materials which are subject 
to washing can be washed, the exact optimum* 
washing compound is not yet known. At pres- 
ent the vegetable acids which form complex 
ions with most of the fission products, which 
are in most cases soluble in water, offer con- 
siderable promise. The problem is complicated 
by the necessity of removing such minute 
quantities of radioactive materials. The forces 
which bind one element to another in contact 
play a very important part in the decontam- 
inating process. Another method of decontam- 
inating is removal of the outer coatings of the 
object which is to be decontaminated if that 
is easier. This latter method (sandblasting) 
has been used on ships and is a feasible method 
of decontamination to permit complete rehabili- 
tation. However, it requires a considerable 
amount of equipment and time to accomplish. 
Very porous materials such as unpainted 
wood, porous concrete and porous brick are 
not readily decontaminable by this method. One 
of the greatest misimpressions that is prevalent 
among wide segments of the populace is that 
some mysterious effect is had by the material 
itself as a result of contamination. This, as 
you all know, is quite in error. The phenomena 
of radioactive contamination is exactly the 
same as getting “dirty” except that very small 
amounts of “dirt” are required and the “dirt” 
is radioactive. One of the biggest factors in 
decontamination on the wide scale that has 
been indicated to be present, and which re- 
mains to be determined, is the statement of 
when is a building, a street, or an object, in 
fact, decontaminated sufficiently for use, or for 
use under limited conditions. 
Another problem that will be encountered in 
decontamination is to secure the safe disposal 
of the removed material. This is one which is 
even further removed from adequate develop- 
ment as yet since it hinges on the practice of 
decontamination. In any area where provisions 
are made for draining of storm water these 
will probably also serve as the avenue for 
disposal of liquid waste. Should there be exten- 
sive quantities of inert materials, mixed with 
contamination, such as might result from sand- 
blasting, this will present a special problem. 
These materials may be piled up temporarily 
and covered with a cement coating to prevent 
scattering. Where important land areas such 
as railroad yards are contaminated, the addi- 
tion of fixatives to the surfaces may be sufficient 
89 RADIOLOGICAL DEFENSE 
to permit use. Again it becomes impossible to 
cite specific disposal methods for the infinite 
variety of possible situations that may occur; 
each case that can be visualized, however, has 
an acceptable solution. Much hinges on pre- 
cisely what is considered acceptable. In event of 
war it is almost certain that the concept of 
safe disposal will be liberalized. 
In the course of our conversation we have 
considered, primarily, the case of radioactive 
contamination of shore establishments. In the 
Navy we are also concerned with the problem 
of radioactive contamination of ships. The 
principles and considerations which influence 
decontamination and disposal are the same. The 
problems involved are somewhat easier. Dis- 
posal into the ocean is usually convenient. By 
reason of its smaller area and high intrinsic 
value, it may be feasible to accomplish a con- 
siderable amount of pre-preparation to mini- 
mize the amount of radioactive material re- 
tained and facilitate its removal. 
The subject of my talk was well titled, “De- 
contamination Problems”. There are a great 
many more “problems” than answers at pres- 
ent. We believe, however, that in the event it 
should come to pass that specific radioactive 
contamination situations arise, a specific solu- 
tion will be available to accomplish the objec- 
tives of restoring an area or unit of material 
to usefulness. It will probably always be a hard 
task but distinctly not impossible or improb- 
able. 
90 RADIOLOGICAL DEFENSE 
PROTECTION AGAINST ATOMIC BOMBS 
By 
Major William W. Stone, Cml C, USA 
Technical Branch 
Radiological Defense Division 
Armed Forces Special Weapons Project 
In considering protection against atomic 
bombs, we find that the words “protection” and 
“defense” are almost synonymous. We will 
treat this subject by dividing it into two broad 
categories: passive defense and active defense. 
Because of the nature of this conference, 
emphasis will be placed upon those factors 
bearing a relatively close relationship to medi- 
cine. For completeness, however, other aspects 
will be mentioned. 
It is important to realize from the very be- 
ginning that the important effects of the atom- 
ic bomb against which protection must be de- 
veloped are: 
1. Blast or Shock Wave. 
2. Visible and Near-visible Radiation. 
3. Nuclear Radiation. 
4. Psychological Effects. 
I. Passive Defense and Protection 
In considering all of the effects of the atomic 
bomb, it should be noted that these forces all 
decrease in intensity extremely rapidly as one 
moves away from the point of detonation, thus 
it is apparent that distance is always the best 
protection. In devising methods of protection, 
one always has the very difficult job of fighting 
against the extremely rapid increase with dis- 
tance toward the bomb of the forces capable 
of creating damage. 
1. Blast or Shock Wave 
a. Primary shock or blast damage, is de- 
fined as the compressing and distorting action 
of the shock wave on the human body. When 
one interposes between the blast and the 
body an object of strength, this form of dam- 
age is effectively reduced. Primary shock is 
thus of greatest importance when a person is 
in the open and exposed simultaneously to 
lethal amounts of other effects of the atomic 
bomb. Living things are remarkably resist- 
ant to shock damage and are much stronger 
in this respect than normal buildings. Un- 
derground shelters and normal reinforced 
concrete buildings protect against this effect 
up to very close to the point of detonation. 
This damage in its mildest forms is seen as 
petechial hemorrhages of the lung. In its se- 
verest forms major abdominal hemorrhages 
appear. 
b. Secondary shock or blast damage is ex- 
tremely important and is defined as being 
due to flying objects hitting and lacerating 
the body. The atomic bomb shock wave is 
very much like an extremely strong wind 
which lasts for about one second. This wind 
is strong enough to throw the body many 
feet. It also breaks windows, knocks down 
plaster, and throws other objects around with 
great violence. When these objects strike a 
human or the human strikes an object, sec- 
ondary shock damage, or trauma, results. 
There are many things that the individual 
can do for himself to reduce his chances of 
this type of injury if he has some advance 
warning of the detonation. It is obvious that 
he should keep away from the windows and 
that he should get flat on the floor or ground. 
One should avoid standing under overhang- 
ing cornices, beneath chimneys and other 
heavy objects which are easily knocked down. 
Underground installations or shelters greatly 
reduce this effect because very little of the 
air shock is transmitted into the ground 
and thence into shelters or basements. In 
Japan, this form of injury combined with 
burns accounted for most of the casualties. 
The rapid follow-up of fire on the blast 
damage caused many fatalities among the 
injured. Injuries of this type require evacua- 
tion, treatment and hospitalization. In the 
case of primary shock damage there is an 
amazingly small boundary zone. One is either RADIOLOGICAL DEFENSE 
dead immediately or all right as far as this 
effect is concerned after a few minutes. 
There is much that can be done in the design 
of vital installations to reduce damage from 
these secondary shock effects. 
2. Visible or Near-visible Radiation 
a. Flash burns are those injuries which 
are created by direct exposure to the visible 
and near-visible radiation emanating from 
the point of detonation. The thinnest type of 
non-transparent material will shield effec- 
tively from this effect. Light colored clothing 
is particularly good as it reflects almost all 
this radiation. Dark colored clothing will 
not transmit this radiation but will catch 
fire and produce flame burns on the skin 
beneath the clothing. This form of damage is 
important only when the person is in the 
open and in direct line of sight from the 
point of detonation. Because of the nature of 
the atomic bomb, this form of damage oc- 
curs at greater distances than that caused 
by any other effect. 
b. Flame burns are those injuries which 
are produced by fires started in inflammable 
material or buildings. Those effects were 
very prevalent in Japan but would be ex- 
pected to occur to a lesser degree in an 
American city. The possibility of fire and 
subsequent injury can be greatly reduced by 
making structures less inflammable. Also, the 
development of adequate and large amounts 
of fire-fighting equipment and trained per- 
sonnel can furnish significant protection. To 
reduce this form of damage it will be neces- 
sary to have fire-fighting equipment and per- 
sonnel so located that a major proportion will 
not be wiped out by the detonation. Reading 
of the accounts of Hiroshima and Nagasaki 
points out the complete inadequacy of Japa- 
nese fire-fighting equipment and procedures. 
In both cities, about 90 percent of the equip- 
ment and personnel for these duties were 
wiped out immediately. Major efforts should 
be placed on reducing the possibility of this 
type of personnel damage, not only because 
of its capabilities of producing a very large 
number of casualties, but also because these 
casualties subsequently need even larger 
amounts of personnel and equipment for 
treatment and hospitalization. 
3. Nuclear Radiation 
a. The utilization of nuclear radiation in 
warfare presents completely new problems 
for both the military and the civilian. These 
effects are not only important but complex. 
They constitute the primary reason for this 
conference. In considering this subject we 
will break it down into several categories. 
The most important division is into external 
and internal hazards. Another division which 
is of importance and helps to clarify the 
situation is to divide these effects into imme- 
diate and delayed hazards. For all nuclear 
radiation effects the general statement is 
again pertinent—that distance is by far the 
best protection. 
(1) Prompt or immediate radiation. By 
prompt radiation we mean those forms of 
damage which are produced in a matter 
of a fraction of a second after detonation. 
With the atomic bomb much of the nuclear 
radiation produced comes out in the first 
fraction of a second after the detonation. 
These radiations emanate from the de- 
tonating bomb and the ball of fire which 
is formed immediately afterwards. They 
consist of penetrating radiations which 
come from outside the body. Hence, all 
prompt nuclear radiation is described as 
an external hazard. 
Major Stone studied physics at California 
Institute of Technology, Pasadena, California 
from 1936 to 1941 and obtained B.S. and M.S. 
degrees at that school. Between 1942 and 1945 
he participated in experimental field testing of 
airborne chemical munitions in the United States, 
Panama, and the Philippines. During 1946 while 
assigned to Manhattan Project he was Assistant 
Reporting and Plotting Officer, RadSafe Group, 
Staff, JTF-1, at the Bikini tests. From 1947 to 
1948 he was assistant to the Technical Director, 
Headquarters, AFSWP, and was Operations 
Officer, Task Group 7.6, JTF-7, at the 1948 
Eniwetok tests. Late in 1948 he was assigned to 
Special Projects Office, Research and Engineering 
Division, Office of the Chief, Chemical Corps 
which position he now holds. 
92 RADIOLOGICAL DEFENSE 
Large amounts of gamma rays come out 
almost immediately from the detonation, 
radiating in all directions. These rays 
travel as does light. They are highly pene- 
trating and it takes a large amount of 
material to absorb and stop them. It is of 
importance to realize the directional and 
shadow producing characteristics of this 
radiation. One needs shielding on all sides, 
but, since the gamma rays which have been 
scattered by one or more collisions with 
atoms in the atmosphere are less penetrat- 
ing than those which have come directly 
from the source, the preponderance of the 
shielding should be between one and the 
burst. Of course, we will not know in ad- 
vance the point of Metonation, so any prior 
planning for shadow shielding against an 
atomic bomb explosion is academic. In 
shielding against gamma radiation, the im- 
portant thing is the weight of the material 
which is between you and the source. The 
chemical characteristics of the constitu- 
ents are of no importance. Lead is often 
used in laboratories where gamma radia- 
tion or X-radiation occurs. This is a suit- 
able substance because it occupies a very 
small volume in comparison to its weight. 
Equal weights of water, steel, concrete or 
wood are just as effective except for their 
space consuming characteristics. The effec- 
tiveness of a shield is most often described 
by means of thickness of the material 
which is necessary to reduce the intensity 
to one-half (l/2) the initial amount. This is 
called the half-thickness of that material. 
It is useful to know very rough half-thick- 
nesses for common construction material. 
They are: 
1" for steel. 
3" for concrete. 
4" for wood or earth. 
Neutrons also constitute an external haz- 
ard at the time of the detonation. They are 
not anywhere near as effective at great 
distances as the gamma rays but require 
consideration close to the bomb. Because 
neutrons are uncharged particles, they 
are difficult to stop and shield against. 
Shieding is not as simple as in the case of 
gamma radiation because weight of the 
shielding is not the important factor. In- 
stead, the important characteristic is the 
ability of the particular chemical or ele- 
ment to slow down and then capture neu- 
trons. The neutrons which occur in the 
detonation of an atomic bomb are essen- 
tially fast neutrons. Substances such as 
cadmium and boron capture slow neutrons 
to an amazing degree. Because these neu- 
trons are not initially slow these sub- 
stances are of no particular value in 
defense against the atomic bomb until the 
neutrons have been slowed down by colli- 
sions with atoms. The best substances for 
slowing down fast neutrons are those with 
low atomic weights. Hydrogen, the lightest 
of all substances, is the best; hence in 
shielding against neutrons the best sub- 
stances for their weight are those con- 
taining large amounts of hydrogen. Such 
shields would be materials like water or 
paraffin. Very rough half-thicknesses can 
be given for common structural materials 
and are as follows: 
Somewhere between 3" and 12" for 
steel. 
About 6" for concrete, earth or 
wood. 
About 6" for water. 
Fast neutrons, like gamma rays, also 
travel in a straight line from the point of 
detonation, going in all directions. For 
these the shielding need be only between 
the person and the source. However, once 
a fast neutron has been sufficiently slowed 
down it has a random motion, and shield- 
ing against slow neutrons must be the 
same in all directions. It should be em- 
phasized that normally neutrons are an 
insignificant hazard in comparison with 
other effects of the atomic bomb. 
From the figures given above it is ob- 
vious that protection from prompt or 
immediate nuclear radiation is feasible 
only for the most vital installations. Mas- 
sive structures that are very expensive are 
the only protection against this hazard. 
93 RADIOLOGICAL DEFENSE 
(2) Delayed radiation. This is the frac- 
tion of the nuclear radiation which does 
not come off immediately but which comes 
from the decay of the fission products 
produced by the nuclear explosion. In an 
air burst, where the fire ball and mush- 
room cloud containing the fission products, 
go up in the air to be dispersed by the 
wind, this delayed radiation is negligible 
and of no importance as a hazard. In an 
underwater burst, or possibly a surface 
land burst, a base surge like Test BAKER 
at Bikini will probably occur. This cloud 
moving along close to the ground contains 
a large proportion of the fission products. 
As this cloud sweeps out over ships or 
cities it surrounds buildings, people and 
equipment. The radiating material is then 
extremely close to personnel in the target. 
The relatively small amount of radiation 
that is left after the detonation is greatly 
enhanced in its effectiveness because of its 
proximity. This base surge, in comparison 
to the mushroom cloud after the air burst 
produces radiation intensities on the 
ground which are higher by a factor of 
thousands, perhaps millions. This is due 
solely to the fact that the base surge can 
surround individuals on the ground. When 
it is realized that at Test BAKER this 
base surge moved over an area of roughly 5 
square miles, this is seen to be a very real 
hazard. It, of course, takes time for this 
cloud to move, and, as the radiation from 
it is only of importance when it surrounds 
the point in consideration, there is avail- 
able a varying amount of time in which to 
get out of the way or to dodge the cloud. 
This base surge moves with varying 
speeds. Initially it spreads out at about 
50 mph. Its speed constantly decreases un- 
til it reaches zero at its outer limits. For 
this cloud to spread over its maximum 
area requires several minutes. If one is in 
a city, great protection will be afforded if 
one gets down into a basement or sub- 
basement, or into an air-raid shelter. It is 
of importance also to note that this radia- 
tion from the base surge is non-directional 
as it comes from all points in the cloud. 
Hence any shield which is devised must be 
on all sides, including on top of, the loca- 
tion considered. 
Delayed gamma radiation from the base 
surge is similar to prompt gamma radia- 
tion except in its non-directional charac- 
teristics. The shielding requirements are 
similar to the previous situation in that 
the same half-thicknesses are applicable. 
There are no delayed neutrons of sig- 
nificance; hence, special shielding is of no 
importance. 
In the delayed situation we also have im- 
portant beta radiation. Prompt beta radia- 
tion does occur but does not travel a very 
great distance from the source because of 
the efficient shielding furnished by air. 
Where the base surge is surrounding the 
location in question, beta radiation is im- 
portant because the range of betas in 
air is roughly 3 or 4 yards. Normal cloth- 
ing furnishes some shielding to beta radia- 
tion. Similarly thin walls and the glass 
in windows are adequate. It is of course 
non-directional and comes from all sides. 
The extent of the external hazard fur- 
nished by beta radiation is not well under- 
stood. It is believed comparable to that of 
gamma radiation when a base surge has 
been created and the individual is in the 
open. 
Alpha radiation occurs from the non- 
fissioned material; in other words, plu- 
tonium or uranium is its source. This ra- 
diation constitutes no external hazard as 
the skin furnishes adequate shielding. All 
the alpha rays are absorbed in the epidermis 
with no resulting damage to living tissues. 
(3) Nuclear radiation (internal). With 
an internal hazard we have the situation 
where radioactive materials, either fission 
products or non-fissioned materials, get 
into the body through inhalation, ingestion 
or injection. This is, of course, a delayed 
hazard and is possible only where one is in 
the base surge, in the mushroom cloud, or 
working in an area over which the base 
surge has previously passed. The internal 
94 RADIOLOGICAL DEFENSE 
hazard occurs generally only where there 
is also an external hazard. If one is ex- 
posed to the base surge or is in the mush- 
room cloud, the external hazard is often 
lethal in its own right without any con- 
sideration of an internal hazard. If one 
is working in a highly contaminated area 
after the detonation, there is a significant 
but not necessarily lethal amount of ex- 
ternal hazard, but there is also a very 
great internal hazard. This is created by 
disturbing the deposited material by kick- 
ing up dust and is usually taken into the 
body through inhalation. An additional 
hazard exists from eating with contami- 
nated hands and thus getting the active 
material into the body through the mouth. 
It is important to realize that in the case 
of an atomic explosion the very small 
weight of active material is dispersed ini- 
tially in the form of a gas or vapor. Almost 
all of the active material adsorbs later 
onto particles of dust or droplets of water. 
Protection against these particulates is 
probably achieved with the use of ordinary 
gas masks containing modern filters. These 
contaminated particles have a size range 
of from 0.1 microns to 10 microns. The 
filters on modern gas masks such as the 
assault mask are believed to be quite ade- 
quate. These filters are extremely efficient. 
It is quite possible that masks will be 
coming out which have adequate protec- 
tion for atomic warfare, biological war- 
fare and chemical warfare. Such a devel- 
opment obviously is highly desirable. 
It is probable that protective clothing 
will be required for workers entering con- 
taminated areas. It would probably be per- 
meable clothing. Its main requirement is 
that it should be disposable. Its functions 
would be to keep contaminated material 
from the skin and possible later entry into 
the body. 
Collective protectors with filters or in- 
closed air conditioning systems are prob- 
ably indicated for vital installations and 
underground shelters in anticipation of 
atomic warfare. Such items would prevent 
the entry of the highly contaminated air 
of the base surge into installations which 
otherwise would furnish adequate protec- 
tion against the effects of the atomic bomb. 
The development of decontamination 
techniques and facilities is indicated to re- 
duce the possibility of personnel becoming 
contaminated and later having active ma- 
terial enter the body through the digestive 
tract. Such techniques will probably con- 
sist of washing away, carrying away, or 
burying the active material. 
4. Planning 
a. Education. In an attack on a modern 
city it is believed that approximately 50,000 
mortalities would be created by a single 
bomb. It is felt that if the individual civilian 
and soldier in these cities or installations 
were adequately trained as to what he could 
do for himself after the detonation occurs, 
that perhaps 10,000 lives could be saved. 
Exactly how much and what kind of educa- 
tion this requires is not yet known. It is be- 
lieved to be relatively simple and is obvious- 
ly important. The development of atomic 
defense for the individual will be the subject 
of much work. Also of importance is the 
education of large numbers of personnel, 
both civilian and military, for special jobs 
in atomic warfare. This requires a much 
greater degree of education and will proba- 
bly be given to such people as radiological 
safety personnel, medical officers and civilian 
doctors, civil defense technicians, etc. The 
method by which the individual indoctrina- 
tion and the specialized training is given 
will determine to a large extent the psycho- 
logical preparation which will be attained 
in a population. It is highly desirable that 
the proper amount of knowledge be given to 
all so that there is created a proper respect 
for the special hazards of atomic warfare 
and that we avoid the undesirable extremes 
of excessive fear or ignorance. This will be 
a difficult job and the nation is far from 
attaining this ideal situation at the present 
time. 
95 RADIOLOGICAL DEFENSE 
b. A large amount of detailed defense 
planning will be required for protection of 
the nation. It will include large scale training 
of such specialists as fire-fighters, police, 
evacuation control personnel, first aid per- 
sonnel, and decontamination groups. Large 
stockpiles of food supplies, medical supplies 
and disaster equipment will be required in 
relatively invulnerable and widely separated 
locations. Preparations will be required for 
mutual aid between cities and major installa- 
tions. 
c. All groups, civilian and military, will 
need to be equipped and trained in the de- 
tection and isolation of contaminated areas. 
This new hazard created by nuclear radia- 
tion is the one hazard which may not be 
detected by any of the physical senses. It 
requires special instruments and special 
consideration. 
d. With sufficient indoctrination and a few 
minutes advance warning that an attack will 
occur, it is quite possible that a 50 percent 
saving in mortalities and casualties can be 
effected. This establishes the fact that devel- 
opment of advance detection techniques and 
warning signals is of the greatest importance. 
II. Active Defense 
1. Of less direct importance to the medical 
profession but of the utmost importance to the 
nation is active defense, which by its name 
means the actual prevention of an atomic 
attack. Regardless of our degree of preparation, 
and protection, large numbers of casualties and 
a more important amount of disorganization 
and dislocation will occur in atomic warfare, 
a. United Nations Organization. The at- 
tempts of the UNO to set up machinery to 
insure peace in the future can be by far 
the greatest protection we can possibly have 
against the atomic bomb if it is successful. 
b. Military preparedness. The basic re- 
sponsibilities of military organizations re- 
quire that they assume that war will occur. 
Otherwise they are negligent in their duties. 
Regardless of the political situation the mili- 
tary must constantly endeavor to have its 
preparedness kept at the highest level. In the 
case of atomic warfare this will consist of 
extensive stockpiling of all weapons, includ- 
ing atomic bombs. It will require readiness 
of retaliation forces. Because of the nature 
of the atomic bomb it will require extensive 
protection of our ability to retaliate and 
conduct an offensive war. As was seen above, 
advance warning is most important—thus an 
efficient foreign intelligence corps is vital. 
c. A vital part of active defense which is, 
in my opinion, erroneously played down in 
articles in the press is the believed impossi- 
bility of interception of an atomic bomb 
carrier and thus preventing delivery of, the 
bomb on the target. Recently our author- 
ities on guided missiles have stated openly 
that it is their belief that guided missiles 
cannot be used as a carrier for at least an- 
other ten or fifteen years. The military must 
consider the intervening years in which it is 
anticipated that manned aircraft are the 
most likely vehicle. We have had only a fair 
degree of success in the interception of air- 
craft on bombing missions. There is no scien- 
tific reason why our degree of interception 
can’t be raised to nearly 100 percent if an 
easily justifiable amount of money, time and 
technical ability is put on the problem. 
Atomic warfare, as you have seen, presents 
a truly severe outlook. It is our duty to 
develop to the utmost any active or passive 
defense procedure which could possibly re- 
duce its effectiveness against us. 
96 RADIOLOGICAL DEFENSE 
RADIOLOGICAL DEFENSE 
By 
Captain George M. Lyon, (MC), USNR (Inactive) 
Special Assistant for Atomic Medicine— 
Chief, Radioisotope Section 
Department of Medicine & Surgery 
U. S. Veterans Administration 
GENERAL CONSIDERATIONS 
For the purpose of military planning it must 
be assumed that atomic weapons may be em- 
ployed against us in the event of our country 
ever becoming involved in another war. 
In the defensive aspects of atomic warfare, 
because of the radiological hazards which may 
be created by atomic attack, the military com- 
mander and the medical officer will be con- 
fronted with many new and difficult problems 
in respect to conserving man power and sus- 
taining morale. 
To meet these problems a technology, new to 
military practice, has been developed and its 
application within the Armed Services is at the 
present time being extended both in plans and 
in training. 
To this activity the term “radiological de- 
fense” is applied. More specifically it consists 
of those measures of a defensive nature in- 
tended to minimize the antipersonnel effects 
which may be occasioned by the injurious ex- 
posure of military personnel to the radiological 
hazards which may be created by atomic 
attack. 
In atomic warfare, just as in any other form 
of warfare, risks must, and will, be taken. Such 
risks as relate to radiological hazards must be 
calculated and accepted in accordance with the 
demands of the military situation and in such 
manner as may be justified by the importance 
of the mission to be achieved or of the objective 
to be gained. A sound principle of economy of 
man poiver demands, however, that such risks 
as are avoidable, and at the same time unneces- 
sary or unjustifiable, will not be taken. To ac- 
complish this it is necessary that certain tech- 
nical information relating to the existence, 
nature and seriousness of any such radiological 
hazard be obtained and that it be evaluated in 
accordance with appropriate standards. 
The medical evaluation of such a situation 
requires that the medical officer be provided 
with such technical information as he may 
need to form the basis for his recommendations 
to the commander. 
The commander in order to most advantage- 
ously make his decisions will require this tech- 
nical information together with the recom- 
mendations of the medical officer in relation 
thereto. 
The detection and measurement of radiation 
in field operations will usually be carried out by 
non-medical personnel or technical specialists 
of the line who are trained and equipped to do 
this type of technical work. As such they are 
technical representatives of the radiological de- 
fense organization rather than of the medical 
department. 
The role of the medical officer will be that 
normal to his position. This will include specific 
responsibilities with respect to advising the 
commander in the medical aspects of radio- 
logical safety. 
The technical aspects of radiological defense 
which are unique center around the techniques 
of detection and measurement of ionizing 
radiation and in the application of informa- 
tion so obtained in the evaluation of the mili- 
tary significance of such radiological hazards. 
The operational aspects of radiological de- 
fense which are unique center around the 
detection and avoidance of radiological hazards 
in such manner as may be consistent with 
sound military practice. As such they consist of 
the employment by military personnel of the 
techniques of health physics and the principles 
of radiological safety adapted to the require- 
ments of military practice and applied thereto 
in such a manner as may be feasible and prac- 
ticable. 
The implementation of radiological defense 
97 RADIOLOGICAL DEFENSE 
measures is in many respects similar to that 
required for chemical defense. While it is true 
that there is little similarity between the haz- 
ards which may be encountered, and while the 
techniques of detection are not similar, there is 
on the other hand a considerable similarity in 
the application of these quite different tech- 
niques both in the organization for, and in the 
conduct of, military operations. 
While there is some degree of similarity with 
respect to the aplication of the principles of 
individual protection, there is very much 
greater similarity with respect to the applica- 
tion of the broad principles of collective protec- 
tion. 
Because the problems of internal radiation 
(radioactive poisoning) are essentially toxico- 
logical in nature, there is a considerable 
similarity between the measures which may be 
taken to protect personnel against such hazards 
and the measures which may be taken to pro- 
tect personnel against certain of the toxic 
agents of chemical warfare. 
The pattern followed in the past in regard to 
planning, organizing and training for chemical 
defense is one which in general outline may be 
followed in making similar preparation for 
radiological defense. 
Each requires the employment of a sound 
philosophy which reflects not only appreciation 
of the military requirements hut keen technical 
knowledge and practical, well balanced common 
sense as well. 
Because the atomic weapon is characterized 
by such destructive and terrifying effects and 
because of the great emphasis which has been 
placed upon the unique characteristics of radio - 
logical hazards, we are today confronted with 
a serious psychological problem which involves 
military as well as civilian personnel and which 
demands at all levels of responsibility leader- 
ship which is intelligent, sound and effective. 
This situation requires a reasonably accurate 
evaluation of the probable effects of such 
weapons and the dissemination and interpreta- 
tion of this information in such a manner as to 
gain the most widespread understanding and 
appreciation thereof. This represents one of 
the most important phases of radiological de- 
fense. Effective leadership and widespread 
appreciation of the facts are both essential. 
Failure is certain if either one or the other is 
lacking. 
Even this, however, is not all that is re- 
quired. It is necessary that there be developed a 
plan for radiological defense in order that the 
effects of atomic attack may be minimized as 
much as possible. It is further important that 
this be widely recognized and that there be 
general appreciation of the fact that such plans 
exist and that they are a direct answer to the 
question, “Well, what can we do?”. 
All military personnel will have some re- 
sponsibilities of an individual nature with 
respect to radiological defense. Those in posi- 
tions of command will have a particular re- 
sponsibility with respect to the individuals and 
elements of their command. Still other individ- 
uals, or groups of individuals, will have specific 
duties of a technical or operational nature. 
It is most desirable that all military person- 
nel, regardless of position or rank, be suitably 
prepared by such indoctrination, training or 
experience as may be needed to enable them to 
fulfill to the best advantage such responsibili- 
Dr. Lyon graduated from Johns Hopkins 
Medical School in 1920. During World War II, 
Dr. Lyon served as a Captain, Medical Corps, 
U. S. Navy Reserve and as Chemical Officer, 
Staff, Commander, U. S. Naval Forces in Europe, 
was responsible for the chemical defense prepa- 
ration and training for personnel of the U. S. 
Navy engaged in the invasion of North Africa 
and Normandy. His activities in relation to 
atomic energy have been: Safety Advisor, Man- 
hattan Engineering District and Medical Officer, 
Thermal Diffusion Plant, Navy Yard, Philadel- 
phia; Safety Consultant, Atomic Bomb Tests at 
Alamagordo, New Mexico; Safety Advisor and 
representative of the Surgeon General, U. S. 
Navy on the staff of Commander Joint Task 
Force One at Bikini; Safety Advisor, Joint Cross- 
roads Committee and Director of the Radio- 
logical Safety Division, Bureau of Medicine and 
Surgery, U. S. Navy; Consultant to the Armed 
Forces Special Weapons Project, Washington, 
D. C.; and Radiological Defense Advisor, Office 
of Civil Defense Plans, Office of the Secretary 
of Defense. 
98 RADIOLOGICAL DEFENSE 
ties as attach to the position, or duty, to which 
they are assigned. This responsibility will 
obtain regardless of whether it relates directly 
or indirectly to radiological defense, or 
whether in relation thereto it is specific or 
general in nature. 
While interest in radiological defense may be 
great in the minds of many of us, we must not 
let it distort our sense of values. There will 
continue to be other matters of fundamental 
importance and in relation to which radio- 
logical defense should be accorded only that 
consideration which is appropriate. On the 
other hand great harm may be done to the mili- 
tary effort of the future if radiological defense, 
and the broad implications thereof, are not 
given proper attention. 
In this connection the very serious conse- 
quences which may arise from the “pyramiding 
of ignorance” must be stressed. This is an ever 
present problem and one which today we are 
not meeting very successfully. This must be 
recognized at all levels of responsibility and 
interests. 
In matters of such a highly technical nature 
as may be involved in the technical and medical 
evaluation of a radiological hazard the careless 
or improper application of a little knowledge 
may become a very serious matter indeed. 
In a similar manner the employment in 
radiological defense training programs of in- 
adequately trained or poorly qualified per- 
sonnel may lead to irreparable damage. This 
poses a particularly difficult problem because 
of the need for rapid extension of training in 
radiological defense. This will continue until 
such time as there are developed within the 
military services sufficient numbers of person- 
nel adequately qualified with respect to their 
ability to serve as reliable instructors, and 
until there are sufficient numbers of personnel 
adequately qualified with respect to their 
assuming positions of responsible leadership in 
matters of radiological defense. 
It is hoped that in time a suitable under- 
standing of the problems of radiological de- 
fense may be universal among all personnel of 
the military services. That such a practical 
understanding may be developed is well within 
the realm of possible attainment. Admiral 
Parsons has suggested that such an under- 
standing could be centered around a simplified 
“nuts and bolts” attitude. This is a goal for 
which those responsible for the development of 
radiological defense measures should strive. 
Man has learned to work reasonably safe with 
the serious hazards of high tension lines and 
of highly toxic and dangerous chemicals. It 
is not too much to think that man can learn 
to meet the problems associated with radio- 
logical hazards. The techniques to be employed 
are now reasonably well known. The measures 
to be applied in the way of planning, organiz- 
ing and conducting such operations are known 
and have been successfully employed in atomic 
bomb tests. Training in both the technical and 
non-technical aspects of radiological defense is 
actively underway within the services at the 
present time. It is being progressively in- 
creased in scope and effectiveness as time and 
experience permit. The Armed Forces Special 
Weapons Project through its Joint Radiological 
Safety Training Committee has done a remark- 
ably good job in providing guidance and in 
developing uniformity of content and training 
practice within the Armed The value 
of this will be more fully appreciated with time. 
There is great danger inherent in attempts 
to oversimplify the technical aspects of radio- 
logicial safety. In this connection there are cer- 
tain limitations which must be respected. This 
is particularly true in relation to the evaluation 
of the probable effects of ionizing radiation on 
living tissue and in an even more striking 
manner in relation to explaining and evaluat- 
ing the hazards of internal radiation (radio- 
active poisoning). With this the medical officer 
will find himself deeply concerned. 
Due to the nature of military organization 
effective radiological defense operations within 
the Armed Services can be achieved to a quite 
satisfactory extent if there is proper planning, 
organization and training, and if there is ap- 
propriate leadership at all levels of responsi- 
bility. To what extent this could be achieved by 
volunteer workers in a civil defense activity is 
a matter of considerable uncertainty. The need 
for radiological defense operations to be con- 
99 RADIOLOGICAL DEFENSE 
ducted in an orderly fashion by properly 
trained and qualified personnel in accordance 
with a sound plan of organization and opera- 
tion, presents a particularly difficult problem 
with respect to the civil defense activities. 
THE MEDICAL SPECIALIST IN 
RADIOLOGICAL DEFENSE 
Some medical officers will be given special- 
ized training in the medical aspects of radio- 
logical defense in order that they may serve as 
special staff advisers, and in order that they 
may assist in the training of other medical 
officers in the more general medical aspects of 
radiological defense. 
The mission of such a specialist will be: 
1. At the direction of the commanding 
officer to establish, develop and 
execute plans for the medical aspects 
of radiological defense within the 
command. 
The tasks and functions of such a specialist 
will include: 
1. To serve as principal adviser to the 
commanding officer in all matters per- 
taining to the medical aspects of 
radiological defense. 
2. To maintain sufficiently close contact 
with operations conducted within the 
command or subordinate units so as 
to be able to evaluate all radiological 
hazards which may be encountered. 
3. To conduct the health protection pro- 
gram of radiological defense in such 
a manner as to support the overall 
Radiological Defense Plan of the com- 
mand. 
4. To conduct, or arrange for the conduct 
of such medical examinations or 
special medical studies as may be re- 
quired and otherwise to observe the 
health status and psychologic effects 
in personnel engaged in all operations 
involving radiological hazards, and of 
all personnel prior to, and upon com- 
pletion of, their assignment to such 
duty. 
5. To provide, or arrange for, such special 
monitoring, including photographic 
dosimetry, as may be necessary to 
ascertain for medical purposes the 
degree of radiological exposure of 
personnel. 
6. To provide, where necessary, such 
medical supervision as may be re- 
quired in effecting the decontamina- 
tion of personnel who have been in 
contact with radioactive material, and 
of their clothing and individual equip- 
ment. 
7. To maintain a system of regular in- 
spection of all radiological safety 
arrangements in order to assure com- 
plete compliance with the local radio- 
logical defense plan and with those 
requirements established by higher 
authority. 
8. To provide for the immediate care of 
personnel who may be injured while 
engaged in any activity involving ex- 
posure to radiological hazard. 
9. To make adequate arrangements for 
personnel who may have received any 
radiological injury or who may be 
deemed to have received an injurious 
over-exposure. 
10. To supervise the professional and 
technical work of all medical and 
other personnel under his cognizance. 
11. To report to the commanding officer 
as well as to higher authority within 
the Medical Department any serious 
infraction of radiological defense dis- 
cipline and violation of radiological 
defense regulations. 
12. To advise the commanding officer in 
the preparation of radiological de- 
fense regulations applicable to the 
command. 
13. To maintain adequately such records 
pertaining to the medical aspects of 
radiological defense as are required 
by local regulation and by higher 
authority and to submit to appropri- 
ate authority such reports on the 
medical aspects of radiological defense 
and radiological safety operations as 
may be required by the Medical De- 
100 RADIOLOGICAL DEFENSE 
partment and by other higher author- 
ity. 
14. To provide for such support from the 
Medical Department as may be re- 
quired by the radiological defense or- 
ganization in the carrying out of the 
Radiological Defense Plan of the com- 
mand. 
15. To provide for such assistance as 
may be required in the general and 
specific training of personnel of the 
command in matters involving the 
medical aspects and the psychologic 
aspects of radiological defense. 
RADIOLOGIAL DEFENSE PLAN 
The Radiological Defense Plan will be pre- 
pared as an Annex to the Operations Plan or as 
an Annex to the Station Defense Plan. 
It will be prepared for the commanding 
officer by the Radiological Defense Officer, 
with such assistance as he may require from 
the Medical Officer. 
The body of the Annex will outline the gen- 
eral plan of radiological defense. Suitable ap- 
pendices to the Annex will be written to cover 
the detailed aspects of training, administra- 
tion, organization, operation, and logistic sup- 
port. They will show how suitable integration 
or coordination is effected between the various 
operating elements and the radiological defense 
organization. One appendix will describe the 
integration or coordination of the medical ac- 
tivities with the radiological defense organiza- 
tion. 
The personnel of the radiological defense 
organization in the main will be officers and 
enlisted men of the line who have been specially 
trained in radiological defense. 
101 RADIOLOGICAL DEFENSE 
COMMAND ASPECTS OF RADIOLOGICAL DEFENSE 
Captain Frank I. Winant, Jr., USN 
Chief, Radiological Defense Division 
Armed Forces Special Weapons Project 
Prudence dictates that we should be pre- 
pared for attack whenever a potential enemy 
is capable of delivering an attack. The United 
States delivered two atomic bombs within 6 
years after the discovery of fission. Therefore, 
recognizing that others may attempt to match 
our performance we must be fully ready at an 
early date. 
Unless our defenses are superior to those 
of Hiroshima and Nagasaki we can anticipate 
that an atomic bomb exploded over a major 
U. S. city will kill or wound on the order of 
100,000 people. Of these, 40 percent will be 
killed and 40 percent will be seriously injured. 
The serious injuries will include burns, radia- 
tion sickness and mechanical injuries from col- 
lapse of buildings, flying glass and debris. 
We rather expect that an enemy would try 
to burst his atomic bombs high in the air. 
When this is done the instantaneous radiation 
will assist the blast and heat in taking a toll of 
lives. As at Hiroshima and Nagasaki, the 
lingering radiation from the bomb will be 
negligible. On the other hand, an explosion of 
the bomb at considerably reduced altitudes, 
whether by intent or accident, can increase the 
significance of lingering radiation. 
Defensive measures against atomic explo- 
sions should lead to the saving of an indeter- 
minate but considerable number of lives. Such 
defensive measures may be divided into four 
(4) broad categories: 
(a) Material measures to prevent instan- 
taneous personnel injury. 
(b) Indoctrinational measures to reduce 
instantaneous personnel injury. 
(c) Assistance measures to stop the oc- 
currence of personnel injury after the 
explosion. 
(d) Curative measures to increase life ex- 
pectancy of injured personnel. 
Of these, the material measures seem most 
appealing. In theory, so much can be done. 
Wide application of such measures, however, 
appears improbable because of economic con- 
siderations. The concept of making every build- 
ing proof against an atom bomb seems far 
more unsound than the Maginot Line theory 
of defense. 
Where the importance of a particular ob- 
jective demands, the proofing of structures 
against the atom bomb appears possible. The 
alternative is defense by dispersal. Insofar as 
we are bound to an economy characterized by 
large cities and large industrial units, we are 
highly vulnerable to atomic bomb attack. 
Under such circumstances, an atomic bombing 
like that at Hiroshima can kill more people 
than were killed by bombs throughout England 
in World War II. 
Radiological Defense consists of protective 
measures to minimize personnel and material 
damage caused by radioactivity. Radiological 
Defense does not purport to make war safe. 
It cannot remove atomic bombings from the 
category of unspeakable disaster. But if it 
can reduce death and disorder, expedite re- 
covery of a few thousand persons and permit 
removal of critical war materials, the defensive 
effort of training and equipping limited num- 
bers of radiological defense personnel will pay 
for itself at any disaster scene. 
Let us consider some ways in which radio- 
logical defense measures can pay off. We can 
indoctrinate people with the object of reducing 
injuries provided they have a warning of the 
explosion. There may be no warning. But a 
fraction of a second will help. People can be 
taught to shield themselves. Thermal shielding 
is of great importance. A handkerchief over 
the face will help. A shirt, a blanket, a tree; 
anything between you and the bomb will reduce 
flash burns. At certain distances from the blast 
this shielding may allow treatment for radia- 
tion to replace hospitalization for thermal and 
radiation exposure combined. 
102 RADIOLOGICAL DEFENSE 
Shielding against instantaneous gamma radi- 
ation is of comparable importance but is 
harder to effect. Here again, anything consti- 
tutes a shield, but heavier shielding is neces- 
sary to give significant protection. Three 
inches of concrete, although inadequate at close 
range, might provide a good protective factor 
at greater distances. In many situations, sub- 
stantial buildings can provide a degree of 
radiation shielding. There is, however, the need 
for an evaluation of the protection provided by 
various types of buildings to be found in a, 
typical target area as against the hazards of 
collapse. 
We can, with some hope of benefit, teach 
fundamentals of self help; avoidance of fire, 
radioactive areas and overcrowding. Indoctri- 
nation which will cause people to seek sound 
underground shelters during atomic alerts may 
avoid some of the horrors of Hiroshima and 
Nagasaki. 
The next defensive category consists of 
measures to prevent occurrence of personnel 
injury after the explosion of the atomic bomb. 
This field is of major significance to the radio- 
logical defense personnel. It involves rescue of 
persons who are in radioactive areas as well as 
control of those who must be sent to work 
there. The combating of fire will be of major 
significance in rescue operations. Many people 
who could have been rescued will burn to their 
deaths. Others will die from neglect. Our 
preparations must include the development of 
fire-fighting equipment which can operate in 
rubble-strewn areas from self-contained water 
or chemical supplies. They must include ade- 
quate logistic preparations for the treatment 
of thousands of burn injuries. Radiological 
defense operations should assist the general 
rescue efforts, which will include not only per- 
sonnel recovery and fire fighting, but control 
of panic, logistics, communications and many 
other passive defense measures. Radiological 
defense must not impede the rescue of endan- 
gered personnel. It must not delay operations 
nor permit overemphasis of the less significant 
hazards. 
We must consider the controversial matter 
of lingering radiation such as that found on 
the Bikini ships. From the defensive point of 
view, lingering radiation is one of the most 
optimistic features of the atomic bomb. It is 
the one thing about which we will really have 
time to do something. It offers a promise of 
successful countermeasures. Therefore, we 
have played it up in our service educational 
programs and in our service research pro- 
grams. This year we are spending millions of 
dollars in the National Military research and 
development programs to combat lingering 
radioactivity and there is prospect that the 
next two years will show the development and 
modest availability of radiological instruments 
capable of fulfilling military requirements. It 
is to be hoped that similar progress can be 
made in research and development programs 
associated with the thermal effects of the bomb. 
Curative measures will be concerned largely 
with mass treatment. Therefore, the logistic 
phases are very important. Provisions must be 
made for large stocks of blood and penicillin 
and for dressings. Hospital space and medical 
personnel will be at a premium. The sorting of 
casualties to place the lesser injured at first- 
aid dressing stations and away from the hos- 
pitals will be necessary. The problems raised 
here are different from the problems of con- 
ventional warfare mainly in point of the mag- 
nitude of effort and preparation. They will 
A graduate of the Naval Academy in 1930, 
Captain Winant subsequently was attached to 
the Postgraduate School both as a student and 
instructor in ordnance. He was gunnery officer 
of the USS MEDUSA during the Pearl Harbor 
attack, and afterward participated extensively 
in ordnance repair work on the Pacific Fleet. 
At the war’s end and subsequently during the 
Japanese occupation, he was Executive Officer of 
the USS VICKSBURG. During the Bikini atom 
bomb tests he was gunnery officer on the staff 
of Commander Target Vessel Group and was in 
charge of unloading of all ammunition from the 
radioactive Bikini Fleet at Kwajalein during the 
autumn of 1946. Since April 1947 he has been 
Chief, Radiological Defense Division, Armed 
Forces Special Weapons Project and served with 
General Hull during the SANDSTONE atomic 
tests at Eniwetok as Commander Task Group 
7.6, the Joint Radiological Safety Group. 
103 RADIOLOGICAL DEFENSE 
depend largely upon the outcome of medical 
research associated with mass treatments. For 
example, the average hospital treatment for 
severe burns at the present time costs several 
thousand dollars. Thinking of this, not in terms 
of money but of facilities and skilled personnel 
required, the hopelessness of a situation involv- 
ing thousands of cases in a disaster area be- 
comes apparent. The methods of treatment 
must be simplified to a point where cases now 
involving maximum efforts within our hospitals 
will be handled by first-aid measures for pro- 
tracted periods. This goal can be achieved if 
we can develop suitable equipment and tech- 
niques and it must be achieved if we are to 
prevent excessive loss of life. 
The problems of Radiological Defense are 
of common concern throughout the military 
services. One important phase of our Radio- 
logical Defense Training Program is to provide 
the military commander with assistance in 
solving the unconventional aspects of these 
problems. 
The problems of radiological defense may 
be subdivided into three (3) categories which 
I shall call: 
(a) Psychological aspects. 
(b) Medical aspects. 
(c) Technical aspects. 
The psychological aspects will prove hardest 
to deal with. For the most part they deal with 
unreasonable fear. Reasonable fear can be a 
useful thing in our lives. It can cause us to 
dodge an on-rushing automobile or to get inside 
of a tank or battleship or behind a machine 
gun. But the hazards of lingering radioac- 
tivity are the food of unreasoning fear. Such 
hazards are nonsensory. They cannot be seen 
nor tasted. They cannot be felt nor smelled. 
They can be internal or external, or both. They 
can be quick-acting or long-delayed. Lingering 
radioactivity is not mythical; it can range from 
insignificance in the case of a high airburst to 
considerable importance in the case of ground 
or waterbursts. It could have preponderant im- 
portance in the event of disaster in our own 
atomic installations or in event of an enemy’s 
resort to some form of radioactive warfare. 
These versatile qualities of lingering radiation 
make it a powerful psychological tool. Whether 
or not we can use such propaganda features 
against an enemy, we can certainly let them 
work to our own disadvantage. 
If psychological weapons are to be forged 
against us, let an enemy do it. Let’s not 
penalize ourselves. The general thinking in 
military circles at the present time is that 
atomic bombs will be used to produce air 
bursts. So long as we feel that an enemy will 
not find it desirable to exploit the radiological 
features of the weapon, at a sacrifice in other 
destructive effects, we should not exploit these 
features for him and add unnecessary com- 
plexities to the panic which will probably fol- 
low an atomic bombing. We should not enhance 
the value of an enemy’s weapons by making 
them psychologically more potent. Radiological 
hazards should be assumed nonexistent in an 
atomic bombed area until they are proved to 
exist. This would mean that the firemen, police, 
stretcher-bearers and medical personnel would 
have immediate and free access to stricken 
zones. Radiological monitoring must be con- 
ducted promptly to confirm the assumption 
that an area is safe. This places upon the 
shoulders of the radiological defense organi- 
zation the problem of being ready and having 
personnel at any atomic bombing scene 
promptly in event of a true radiological dis- 
aster. 
If the air burst of Hiroshima and Nagasaki 
and Test ABLE have established positive evi- 
dence that high air bursts leave little lingering 
radioactivity, certainly Test BAKER has pro- 
vided room for doubt in other instances. It is 
reasonable to assume that an enemy will create 
some radioactive areas in the United States, 
even if only from a malfunctioning of bomb 
fuses. These areas will constitute major prob- 
lems in radiological defense. We can and will 
work in such radioactive areas. Our atomic 
tests have proved this. But we must work intel- 
ligently. 
The military commander will have medical 
advisors to assist him. But how much physical 
injury will he accept within his own command? 
Where and how will he “draw the line”? It is 
104 RADIOLOGICAL DEFENSE 
my opinion that the wartime military com- 
mander in a radioactive area will establish 
a limitation for personnel exposure which I 
shall call the “Wartime Military Tolerance” 
(WMT). This is an arbitrary guide which* 
will limit the time that personnel may be em- 
ployed in radiological areas. It can be estab- 
lished as an arbitrary percentage of the median 
sickness dosage as indicated in the following 
equation : 
WMT = K X MSD 
MSD means “Median Sickness Dose.” MSD 
is the cumulative dosage which will cause half 
of all persons exposed to it to become radio- 
logical casualties. Such persons will show acute 
manifestations of radiation injury. MSD has 
not been defined with finality. It will vary with 
the rate of exposure. It may run as low as 100 
roentgens for very rapid exposures and higher 
than 200 roentgens for low rates of exposure. 
The determination of what constitutes me- 
dian sickness is a matter of medical research 
and is not a problem of military command. In 
terms of conventional warfare, MSD might cor- 
respond to the probability that a bullet injury 
would necessitate hospitalization — obviously 
not a command but a medical problem. 
The equation suggests that WMT, the larg- 
est amount of radiation to which a military 
commander can afford to expose his men, is a 
certain percentage of the median sickness 
dosage. We want WMT to constitute a suitable 
limitation which the commander can prescribe 
throughout his organization. Its value will de- 
pend on the proper choice of the control factor, 
K. 
Let’s examine the significance of this control 
factor. We will find that it must be appreciably 
less than unity, and appreciably greater than 
zero and that the exact positioning between 
its upper and lower limitations will be con- 
troversial The upper limitation will be a medi- 
cal control. If we let K equal unity and allow 
personnel to work in radiological areas until 
they have accumulated up to 200 roentgens 
then we shall require the hospitalization of 
50 percent of our rescue personnel at a time 
when all hospitals in the area are already 
hopelessly overloaded with atomic casualties. 
On the other hand, we shall find that the radia- 
tion casualties will decrease as the value of K is 
decreased below unity. For example, if K were 
established at 50 percent, then we might expect 
less than 10 percent of our rescue personnel to 
become radiologically ill. Under wartime cir- 
cumstances the losses would not be deemed 
serious. Injuries resulting from a K of less 
than 50 percent would probably be more on the 
psychological than the physiological side. 
There is another consideration in establish- 
ing the upper limitation of K which I will 
call a “margin for error.” When a wartime 
military tolerance is established it is meant to 
be an actual working tolerance to which the 
local commanders can subject their troops 
with assurance. Therefore if WMT lies right 
on the border line of physical injury, we shall 
find that those persons who unwittingly exceed 
the WMT will be endangered. This is not de- 
sirable. It is almost impossible to insure that 
some personnel will not exceed any estab- 
lished limit, or putting it another way, you can 
assume that 5 to 10 percent of employed per- 
sonnel will exceed existing limitations and that 
a very few persons will significantly exceed 
them. It will be of great advantage to us if 
we can assure all personnel that the standards 
which we establish are sufficiently safe so they 
are positively guaranteed against radiological 
injury. In this basis I would say that the value 
of K ought not to exceed 40 percent. 
In considering the lower limitations of K, 
we are concerned with technical problems 
and must make provisions for operating effi- 
ciency of our personnel. How long can we work 
in a radiological zone and keep the risk and 
effort commensurate with the work accom- 
plished? The absorption of radiation is never 
desirable and should never be permitted unless 
necessary. But when we get down to a value 
of K on the order of 10 percent, we begin 
penalizing ourselves and encumbering the 
personnel to a point where they cannot work 
efficiently in areas that are appreciably radio- 
active. Obviously, the law of diminishing re- 
turns must govern. During Operations CROSS- 
ROADS and SANDSTONE the value of K was 
on the order of two percent. Work in radioac- 
105 RADIOLOGICAL DEFENSE 
tive zones was carefully planned to permit the 
personnel to enter these zones quickly and 
secure information or equipment of scientific 
value. Even with this careful planning the 
work was considerably hampered by the high 
degree of personnel protection which we main- 
tained. In some instances personnel arriving 
in radioactive areas were scarcely able to orient 
themselves to a job before they found it neces- 
sary to withdraw. Such operations led to fast 
Jeep rides over rough terrain where the read- 
ing of radiological instruments became inac- 
curate and sometimes defeated the prescribed 
precautionary measures. It would be practical 
in wartime, without serious consequences to 
personnel, to work in radiological areas well 
beyond the SANDSTONE limitations. 
On occasion the desire for extreme caution 
may lead to more serious hazards of other 
natures. For example, in the Ammunition 
Removal Operation on the Bikini vessels after 
Operation CROSSROADS, the extreme pre- 
cautions for personnel involving the wearing of 
rescue breathing apparatus to protect against 
possible, but actually insignificant, concentra- 
tions of radioactive material in the air led to 
the amplification of explosive and other types 
of physical hazards. The poor vision afforded 
by the rescue breathing apparatus was a con- 
tributing source of difficulty. On the battleship 
Nevada, one man received a glancing blow that 
could have been fatal from a falling ammuni- 
tion charge simply because he couldn’t see 
clearly. The injuries actually received in this 
operation were negligible but the hazards were 
potentially great. 
There can be a very real danger from in- 
creasing our protective requirements too great- 
ly. If we set K at 10 percent the time will 
come when a local commander will be more 
impressed with the inefficiency of his command 
than with the need for protection against 
radiation. He will become aware of the fact 
that radiation within his command is harmless 
and at the same time he is failing to get a job 
done because of extreme precautionary meas- 
ures against radiation. He is likely to kick over 
the traces and assume that radiation hazards 
are overrated. He may issue orders that the job 
be accomplished regardless of the hazards in- 
volved. This is about the worst thing that can 
happen because the hazards are there no matter 
how intangible they maj seem and they will in- 
evitably take a toll if suitable precautions are 
disregarded. For this reason the working limi- 
tations should be reasonable to a point where 
the local commander realizes that he must not 
exceed WMT but that the established value of 
WMT will allow him to work with the greatest 
possible freedom. With this in mind it would 
appear that the value of K could profitably be 
set at 20 percent and that any value below this 
would unnecesarily restrict the efficiency of the 
organization and might possibly hamper the 
protective measures themselves. 
The next problem becomes that of estab- 
lishing a reasonable value of K somewhere 
between the upper limitation of perhaps 40 
percent and the lower limitation of 20 percent. 
The major influence in determining the proper 
establishment of this value would appear to be 
psychological. No matter how hard we may try 
to evaluate calmly radiation as a hazard and 
place it in its proper scale with other forms of 
military hazards it has psychological aspects 
which simply do not fit our normal modes of 
approach. 
Suppose, that for training confirmation you 
approach a group of men with the purpose 
of obtaining one hundred volunteers to crawl 
through an area where they will be exposed 
to well-controlled machine-gun fire. You give 
them assurance that they will be carefully 
watched and that the fire will be stopped if 
an injury to anyone is noted. You would not 
expect too much difficulty in getting volunteers 
for this mission during wartime training. 
“Hope springs eternal in the human breast”. 
There is a possibility that one man may get 
hurt, perhaps killed, but each man with a faith 
in his own destiny knows that it will be some- 
body else, and that he will be safe. Now, to 
recognize the psychological pitfall introduced 
by a nonsensory danger, let’s change the prob- 
lem to one in which the fate of every man is 
pegged to that of his comrade. If the group 
were standing in the beam of a giant X-ray 
machine no one would expect preferential pro- 
106 RADIOLOGICAL DEFENSE 
tection. Let’s assure the men that the radiation 
will be turned off as soon as any one of them 
falls. Draw your own conclusions as to how 
many volunteers you will get for a test like 
this. In the first example while under machine 
gun fire each man has 99 chances out of a 
hundred of survival. In the second example 
every man should meet a fate as bad as that 
of anyone else in the group. Gamma rays are 
not respecters of persons. Whether they sub- 
ject everyone to a withering dose or to an 
insignificant exposure, they hit everyone in the 
target area with almost identical effect. To 
understand the psychological factors which 
this creates, you must consider the ideas, trivial 
or otherwise, that run through the minds of 
your soldiers. They will think about this sort of 
thing when they are confronted with hazards 
which they can neither see nor taste nor smell 
but which they, nevertheless, know are having 
physical effect upon them. Such hazards prey 
strongly upon the mind. The men must have 
a powerful faith in the commanding officer to 
work continuously and calmly in the presence 
of unobservable but sure hazards. Establish- 
ment of the lowest practicable K factor will 
foster this faith. 
Now let me emphasize once more that we 
would not expect highly radioactive zones in 
the average atomic bomb explosion. Radio- 
logical defense concerns itself with readiness 
for the instances in which such residual radio- 
activity is found. If radiological defense meas- 
ures are to be invoked when they are needed or 
when a need for them is erroneously suspected, 
then we must prepare for them now by training 
and equipping personnel to comply with their 
missions when required. We must expect 
atomic bombs in future wars. We must expect 
injury and it is proper to assume that we will 
encounter residual radioactivity in some cir- 
cumstances. Such radioactive zones will not nec- 
essarily contain rates of radiation which would 
approach lethality under normal working con- 
ditions. But we can expect significant dosages. 
The areas bombed may be our most im- 
portant installations—atomic plants, ordnance 
plants, big industries, the things which we 
must restore to operation if we are going to 
carry on the war. If we approach the problem 
with the assumption that such an area is radio- 
active and if we put a big fence around it and 
stay out—we are licked! We can, and must, 
work in radioactive zones. But we must work 
in them under controlled conditions. We can’t 
go to the commander and say, “Now, there are 
no hazards in here at all. You are free to 
work.” What we can say is, “We would like 
you to attempt work, but it will be dangerous. 
You must be prepared to work for limited 
periods only. There will be overexposures. For 
this reason you must have replacements at 
hand. Exposure records of personnel must be 
maintained. Personnel must receive qualifying 
physical examinations, since a limited number 
of people can thus be separated as undesirable 
radiological risks for such work.” 
The technical aspects of Radiological De- 
fense constitute a field in which much has been 
done to assist the commander. The Radio- 
logical Defense Officers will be important 
assistants to him. More than one thousand have 
already been trained, and we are training about 
that number yearly in joint courses conducted 
by the Army, Navy and Air Force at Edge- 
wood, Treasure Island, and Keesler Air Force 
Base. These are the personnel who will assist 
the commander organizationally. They under- 
stand the calibration and use of detection 
instruments and the nature and evaluation of 
radiological hazards. 
In this discussion, my references to radia- 
tion have implied gamma radiation, the long 
range killer. There are others. For example, 
alpha and beta emissions will have great sig- 
nificance where lingering toxic effects are 
to be feared. Underwater bursts or surface 
bursts may contaminate areas with a multi- 
plicity of fission products in the form of radio- 
isotopes. After a period of time, rates of decay 
will eliminate certain fission products as sig- 
nificant hazards and the readings which are 
obtained from some detection instrument types 
may become negligible. Such fission products 
may be superseded by others as principal haz- 
ards. Under circumstances where sabotage 
might be involved, the most serious hazards 
may be hardest to detect. Such complexities 
107 RADIOLOGICAL DEFENSE 
give rise to serious problems of personnel and 
material decontamination and point up the need 
for special personnel and equipment. 
Protective equipment consisting of masks 
and disposable clothing for the workers may 
be indicated. Careful monitoring of radioactive 
areas and supervision of workers will be neces- 
sary to prevent operations in “hot spots” of 
radioactivity. It will be necessary to have field 
laboratories and special technicians for the 
analysis of radioactive materials and to deter- 
mine the freedom from toxicity of air, water 
and food. Training of specialized personnel has 
commenced and development is under way on 
all necessary types of instrumentation and 
equipment. It is hoped that the current service 
research program may lead to some simplifica- 
tion in the complex material requirements of 
Radiological Defense. 
Radiological Defense is a responsibility of 
command. The establishment of a Wartime 
Military Tolerance (WMT) will provide a 
planning guide for the military commander. It 
will enable him to complete requirements for 
timely replacement of personnel. It will be a 
guide in protecting personnel against external 
radiological hazards but will not be an absolute 
limitation placed upon the commander. Under 
conditions where personnel must travel through 
or work in atomic areas with the only alterna- 
tive being destruction from other causes, any 
established tolerances would serve no purpose. 
Realizing that no simple guides will prove 
unfailing and that complete reliance upon 
specially trained advisors is not always ex- 
pedient, the current program for radiological 
defense training is aimed at service-wide 
indoctrination. 
Over and above our training programs, 
there will be many operational problems for 
which there is no simple scientific or text book 
approach. Our training program admittedly 
needs stiffening along these lines. There is very 
little realistic experience upon which to base 
standard operational procedures. We have had 
atomic bomb bursts under conditions of war 
in Japanese cities but the residual radioactive 
conditions were lacking. We have had a series 
of atomic bomb tests but these were not asso- 
ciated with the disaster conditions to be ex- 
pected in wartime. We can say one very definite 
thing about radiological hazards. We may not 
have them associated with every atomic bomb 
burst. We may not, and we probably will not. 
But when we do have them, the radiation haz- 
ards will invariably be associated with cata- 
clysmic destruction resulting from the atomic 
bombing in the form of vast numbers of in- 
jured personnel, fires, broken water mains, gas 
lines and electric wires, disrupted communica- 
tions and the probable failure of logistic sup- 
port and panic. Our operational development 
must be guided by the fact that our radiological 
defenders in accomplishing their primary mis- 
sion, must work in the presence of these other 
complicating conditions. 
The normal employment for radiological de- 
fense personnel will be in areas of sublethal 
contamination. Our efforts must be to deter- 
mine what we can do, rather than what we 
cannot do in these areas. We can and will work 
in them when there is cause. We will not 
sacrifice vital industry and war plants simply 
because they are contaminated with a radia- 
tion level of 10 or 20 roentgens per day. Under 
such conditions a well trained staff group will 
be indispensable in prescribing the working 
conditions, techniques, lengths of exposure, pro- 
tective devices, decontamination procedures 
and in providing adequate supervision. 
We should not disregard the possibility 
that many of our personnel trained for radio- 
logical defense may be called into disaster 
areas even in event of high altitude atomic 
bursts. There may be no need and no reason 
for this other than the fact that these people 
have had a special training course. 
We must not leave our problems of opera- 
tional development unsolved awaiting hurried 
solutions under conditions of actual warfare. 
Future atomic tests should be very useful for 
developing our standard operational procedures 
and organizations. To increase our service 
experience, military personnel should be em- 
ployed in radiological defense work in these 
tests. Such tests are few and far between and 
are sometimes limited to specialized objectives. 
Since they fall short of the disaster conditions 
108 RADIOLOGICAL DEFENSE 
toward which our planning must be pointed, 
it seems vital that there be operational devel- 
opment within the services. We have a great 
deal to do in properly evaluating the air recon- 
naissance of radiological areas, in determining 
the value of helicopters for radiological survey, 
in perfecting remote and projectable telemeter- 
ing instruments and techniques and in com- 
pleting time studies and work planning and 
on-the-spot orientation methods for such condi- 
tions. We have a great deal more planning to 
do in the matter of provision of adequate and 
timely personnel replacements in radiologically 
hazardous areas. 
Operational development work will provide 
a continuous testing of textbook training and 
prevent stagnation of training doctrine. With- 
out it our training in theoretical aspects can 
advance only to the limit of the most recent 
physics text and in its practical aspects to the 
limits of the last information which has 
emanated from atomic tests. 
No discussion of this nature could be com- 
plete without some reference to Civil Defense. 
Since most of us have families, we are natu- 
rally interested in this problem. The armed 
services are responsible for effecting their 
primary military missions in wartime and will, 
in general, be unable to effect civil defense. 
Recognizing this condition, it is proper that 
the military should keep out of civil defense as 
much as possible. This will confront the Civil 
Defense Organization with the responsibility 
of growing up to meet its own problems. It 
would be sheer folly, however, to overlook the 
fact that civil defense will have a great influ- 
ence on our capabilities to wage war. Another 
war may very well be won or lost on the home 
front. Recognizing this, we are trying to do 
what we can in support of civil defense without 
complicating it. Our research programs are 
pointed toward developing equipment which 
will be as useful to the civil defenders as to the 
military. 
The field of radiological defense, from its 
inception, has been a universal field with uni- 
versal language, equipment, techniques and 
training. It is a military goal to increase our 
readiness in equipment and trained personnel 
so near to the service requirements that if 
called upon in emergency we can release radio- 
logical defense personnel to any point neces- 
sary. To this end we have initiated a truly 
joint training program with the Army, Navy, 
and Air Force turning out of their own schools, 
joint student groups who have been trained in 
joint curricula under joint staffs so that in 
emergency they can be banded together quickly 
and work together with intelligence and pre- 
cision as they did in Operation SANDSTONE. 
109 RADIOLOGICAL DEFENSE 
PSYCHOLOGICAL FACTORS IN ATOMIC WARFARE 
Colonel James P. Coooney, MC, USA 
Chief, Radiological Branch 
Military Application Division 
Atomic Energy Commission 
Many of the ideas I want to discuss are 
matters of opinion—and they are, in some 
cases, ideas on which the diversity of opinion 
seems to be a function of the number of people 
having the ideas. I want to present my ideas 
with the hope of stimulating thought and more 
careful consideration of a most important prob- 
lem. 
Please do not interpret any of my remarks 
as indicating anything less than the fullest 
respect for the phenomenon of radioactivity 
as a diabolical instrument of death and injury 
to men. I only want to point out that we are 
justified in taking a rather hardboiled attitude 
toward it. Since we have no choice but to live 
with it, we must keep it in proper perspective. 
Since the advent of nuclear explosives in the 
so-called atom bomb, with its attendant ioniz- 
ing radiations in massive amounts, unfortunate 
psychological reactions have developed in the 
minds of both the military and civilians. 
This reaction is one of intense fear, directed 
against forces that cannot be seen, felt or 
otherwise sensed. I have observed the reactions 
of the military, who were not acquainted with 
the technical details, on two missions, Bikini 
and Eniwetok, and the fear reaction of the 
uninitiated is appalling. The fear reaction of 
the uninitiated civilian is ever evident. It is of 
such magnitude that it could well interfere 
with an important military mission in time of 
war. 
The effect of ionizing radiation upon living 
cells is detrimental. It must be realized, how- 
ever, that nature has been constantly bombard- 
ing the populations of the world with ionizing 
radiation since the formation of the universe— 
by constant exposure to cosmic radiations and 
to radiations emanating from natural radio- 
active elements—such as radon and thoron. 
This kind of injury must be considered, not 
standing by itself, but in connection with the 
total situation, i.e., weighed in relation to the 
objectives in view, both in regard to their im- 
portance under the circumstances and their 
probability of attainment. Unless we can thus 
integrate it with our whole philosophy of na- 
tional defense, the atom bomb can prove a 
liability rather than an asset. 
With the publicity incident to the atom bomb, 
the term “roentgen” has become a household 
word. It is a term of physical measurement 
such as “centimeter” or “gram”. It is based 
upon one of the physical effects of certain 
types of electromagnetic waves that cannot be 
measured with a yardstick. The large step from 
such a physical measurement to expected bio- 
logical behavior in human beings is based upon 
experimentation on lower animals, empirical 
observations, and clinical investigations. There 
are, however, many blank spaces in our experi- 
ence and many superstitions have been intro- 
duced. Since it is impossible to stipulate all 
conditions of experimentation and observation 
in most of the articles written about radiation 
for lay consumption, an idea has evolved in 
many minds that any and all radiation exposure 
will cause immediate and mysterious injury or 
death. This reasoning is fallacious, but it is 
also attractive and has become contagious. 
The problem of radiation injury is not one 
which can be easily simplified. In fact, over- 
simplification may be the cause of a situation 
such as we are combating at this time. It seems 
desirable to explore radiation hazards more 
fully in relation to other hazards which are 
considered more common and acceptable. 
The permissible radiation dose is 0.2 or 0.1 r 
per day, or 0.3 r per week according to your 
authority.. This should no longer be called the 
“tolerance dose” for no amount of radiation 
should be tolerated without good reason. One 
is willing, however, to name a dose so small 
that a person might be exposed to it every day RADIOLOGICAL DEFENSE 
of his life and suffer no observable injury nor 
shortening of the life span. 
When one is dealing with radiation techni- 
cians or with industrial workers who are ex- 
posed to this hazard daily, one can easily see 
how the maintenance of exposures at or below 
this level is a very desirable thing. Day by day 
contact with radiation or radioactive materials 
demands that a low limit of exposure be ad- 
hered to if late complications of such chronic 
trauma are to be avoided. Similar occupational 
hazards exist in all branches of production— 
as the inhalation of noxious gases and dust 
to the coal miner, the steel worker and the 
chemical worker. It has been known for years 
that if a miner is subjected to small amounts 
of dust containing silica, he eventually will 
develop silicosis, frequently complicated by 
tuberculosis, with a fatal termination. For this 
reason, methods of counting and analyzing 
dust have been perfected, and forced ventila- 
tion systems have been established to minimize 
the danger. This does not mean that if an 
individual makes a one day visit to a mine and 
inhales 100 times the daily minimal allowance 
for miners, he will develop silicosis. The toler- 
ance limit in this instance has nothing in its 
definition which refers to acute exposure. 
Neither is the 0.1 r per day tolerance limit 
related to acute exposure to radiation. 
The total body dose of radiation received in 
an acute exposure is known from therapeutic 
experience to vary with the patient. This and 
the lethal dose for man have not received the 
same attention from rule-making bodies that 
the “permissible dose” has had. We may take 
450 r as the median lethal dose. 
Going further down the scale, one may con- 
sider a limit of 200 r, which may cause radia- 
tion sickness in 50 percent of human subjects 
when delivered, as an acute dose of total body 
radiation. Since some subjects may be relatively 
sensitive to radiation and others relatively re- 
sistant, it is difficult to calculate the precise 
effects to be expected. 
It is not unusual to subject a patient to 
multiple X-ray studies of the skull, spine, long 
bones, gastro-intestinal tract, kidneys, sinuses, 
etc. in a relatively short space of time, thus 
subjecting him to a dose of radiation which may 
well approach 25 r. These procedures are not 
done without purpose and the benefit derived 
from them outweighs all fear as to the possible 
injury from radiation. Full body irradiation 
in doses of the order of 25 to 100 r has been 
given to patients for treatment of various con- 
ditions. Again these exposures are prescribed 
for a purpose which outweighs the fear of radi- 
ation injury. 
As stated above it is not my purpose to under- 
estimate or understate the radiation hazard. 
But from a military standpoint the physical 
danger must be evaluated against the objective 
to be gained. 
War is fought with the knowledge that men 
will be killed. Campaigns are planned with the 
expectation of losing so many thousand men. 
If this is regarded as an “acceptable hazard,” 
then it is obviously not wise to treat radiation 
hazards very differently. If other military haz- 
ards will be lessened by acceptance of the radi- 
ation hazard, then it should be accepted. This 
can only be done, however, if the attitude of 
the men exposed is psychologically similar 
toward the two types of hazard. If they are 
going to be as much terrified by the knowledge 
that a recent atom bomb explosion has contami- 
nated the ground they are walking over as they 
would be by seeing one in ten of their buddies 
fall by machine gun fire, one cannot apply the 
“ideal” solution. What is dominant for actual 
percentage survival is the resultant of all the 
actual hazards. But for battle discipline and 
military effectiveness the dominant measure is 
not the hazard itself but the soldiers’ estima- 
tion of the hazard. 
Men at war suffer many hazards, acute and 
chronic, besides bullets: malaria, venereal dis- 
ease, exposure to cold and wet, starvation, etc. 
Some of these, e.g., VD, are underevaluated 
by the doughboy. Others as filariasis, are 
grossly overevaluated. At present radiation is 
perhaps the most overevaluated of all, partly 
due to our great care in Operations Crossroads. 
That operation was conducted at the peacetime 
level of safety to personnel. Unless we had 
openly proclaimed immediate danger of war, 
the military level for hazardous training pro- 
111 RADIOLOGICAL DEFENSE 
grams, such as we had actually adopted during 
the war, using live grenades and live ammuni- 
tion in the machine guns, was not tolerable at 
Bikini. It must be emphasized that hazards 
acceptable in a peacetime operation cannot be 
adhered to in wartime. 
Psychological training for the military level 
of acceptable radiation hazard is possible and 
should be prosecuted, even though operation 
field training does not permit this to be accom- 
plished at the present time. 
We hear much about sterility as a result of 
exposure to ionizing radiation. It must be borne 
in mind that sterility results only from a large 
dose of acute radiation, or from smaller doses 
over a long period of time—a matter of years. 
Sterility also results from other accepted haz- 
ards encountered in war, notably venereal dis- 
ease. We are aware of hundreds of paraplegias 
due to spinal fractures, gun shot wounds of the 
cord, etc., during the last war resulting not 
only in sterility but impotence. Leukemia may 
be another late result in casualties from re- 
peated radiation, but amoebic dysentery and 
schistosomiasis carry a great delayed hazard, 
as does beri-beri, which was so prevalent 
among our prisoners-of-war. 
I have knowledge of a death at Bikini caused 
by drinking wood alcohol. There were other 
deaths due to various types of accidents. At 
Eniwetok we had a death due to drowning; one 
due to a truck accident, and one due to a frac- 
ture of the skull encountered in a fight. A sailor 
sustained a fracture of the cervical spine with 
severence of the cord by diving into shallow 
water. He will be paralyzed, sterile and impo- 
tent as long as he lives. None of the above 
tragic episodes received national news pub- 
licity. However, had we had a single death due 
to radiation, would it have been publicized? 
It would have received front page publicity 
throughout the country. 
During August of 1946 I interviewed and 
examined a large number of Japanese who had 
recovered from radiation sickness. They ap- 
peared perfectly normal and were handicapped 
in no way toward pursuing their manner of liv- 
ing. Such is not the case with thousands of our 
soldiers who participated in “conventional” 
warfare in World War II. They are handi- 
capped by loss of limbs and eyes. Neither is it 
true of many of the Japanese who received no 
radiation injury but suffered severe burns and 
traumatic injury as a result of the bombing. 
It has been estimated that from 5 to 15 percent 
of the deaths at Hiroshima and Nagasaki were 
due to radiation. Why do we concentrate on the 
15 percent and forget the 85 percent? 
The atomic bomb was developed as a blast 
weapon of war and strategically so used. The 
radiation effect was never considered to be the 
prime component of its effectiveness. The de- 
struction attendant upon the blast, heat and 
secondary fires was paramount. In Japan there 
was no significant “poisoning” of the ground 
by fission products or induced activity from 
neutron capture; yet many believe that the 
bomb is primarily a weapon which destroys by 
mysterious radioactivity. 
I have appeared before local defense agencies 
in many of our cities. They are preparing for 
defense against an atomic bomb attack and 
universally they are thinking only of radiation. 
Invariably they ask, “Where will we get Geiger 
counters?” Geiger counters are not their only 
problem—fire-fighting equipment is many times 
more important, as are well-organized rescue 
squads. “But we have been told that we will 
not be able to go into a bombed city and rescue 
the injured.” Hiroshima and Nagasaki disprove 
this. The residual radiation from an air burst 
bomb is insignificant. The significant radiation 
occurs in a matter of microseconds and does 
not extend beyond a 2000 yard radius. Imme- 
diately after a detonation, such as occurred 
at Hiroshima or Nagasaki, it is perfectly safe 
to enter into a bombed area and rescue the 
thousands whose injuries will be such that they 
will not be able to walk. Unless evacuation of 
these injured is effected, thousands will be 
burned to death by secondary fires. Such was 
the case at Hiroshima and Nagasaki. But how 
about an underwater or ground burst? In such 
cases certainly the residual radiation hazards 
would be increased many fold, but the blast and 
fire hazards and the prompt radiation hazard 
would be proportionately decreased, and in my 
112 RADIOLOGICAL DEFENSE 
opinion, the total number of casualties would 
be less. 
Much has been written about “poisoned” 
water. In case the water supply of a city is 
contaminated by fission products or unfissioned 
material from an air burst of an atomic bomb, 
all the evidence on hand at present indicates 
that, after passing through a modern filtration 
plant, the water at the tap would be safe to 
drink. More work will be done to prove or dis- 
prove this statement. We do know, from our 
experience at Bikini, that the water from 
evaporators used on the ship is safe for drink- 
ing. Again we must not forget that frequent 
cases of typhoid fever still occur from drinking 
polluted water. 
If we are to live with this piece of ordnance 
and ever have to use it again in the defense 
of our way of living, we must acquire a prac- 
tical attitude, not only toward its efficiency or 
limitations as a bomb, but also toward the pos- 
sible effects and limitations of this “mysteri- 
ous” radiation. We must recognize that the 
casualties caused by the blast and burns from 
this weapon will be many times greater than 
the deaths caused by radiation. We must also 
dispel the erroneous idea that the rescue work 
of the injured will be impossible due to residual 
radiation. 
It is of the utmost importance that we recog- 
nize that the radiation hazards are additional 
hazards. They only add to the complexity and 
perhaps even the severity of the other hazards 
of total warfare. Therefore, we must not and 
cannot concentrate on this phase of atomic 
warfare to the detriment of other defensive 
preparations. Rather, we must know and under- 
stand the facts about ionizing radiations if we 
are to survive the other dangers. 
113 RADIOLOGICAL DEFENSE 
THE PRODUCTION, PROCUREMENT AND HANDLING OF RADIOISOTOPES 
Major Maxwell Dauer, MSC, USA 
Radiological Branch 
Division of Military Application 
Atomic Energy Commission 
INTRODUCTION 
The artificial production of radioisotopes for 
scientific use dates back about 14 years. How- 
ever, the radioactive elements that occur in 
nature were used as sources of radiation, and 
even as tracers, virtually from the time of 
their discovery during the early years of this 
century. The first tracer experiment was con- 
ducted by Hevesy in 1912 who demonstrated 
that radium-D was chemically the same as 
lead. 
Most of the naturally occurring radioisotopes 
belong to the heavy elements between thallium 
and uranium. There are four relatively light 
natural radioactive elements, which include 
potassium, rubidium, samarium, and lutecium. 
None of these enter much, if at all, into life 
processes. Therefore, few biological tracer ex- 
periments were performed with the natural 
radioisotopes. The primary use was for radium 
and its associated elements as a therapeutic 
agent. 
In 1934, the Joliot-Curies discovered that 
radioactive isotopes of the naturally stable ele- 
ments could be produced by nuclear bombard- 
ment. Within a few years, cyclotrons and other 
particle accelerators had produced radioiso- 
topes of all of the stable elements. By 1940, 
some 370 varieties were known. 
As soon as radioisotopes of carbon, phos- 
phorus, sulfur, iron, iodine, and other elements 
entering into life processes became available 
investigators put them to work. It was tremen- 
dously costly to produce isotopes in cyclotrons. 
However, their value as research tools was 
unique and the effort to produce them with 
cyclotrons was justified. 
The wartime development of the atomic pile 
made possible the widespread use of radioiso- 
topes in hitherto undreamed of quantities. The 
production of about 200 millicuries of carbon 
14 in a period of a few weeks at the Oak Ridge 
pile, theoretically would require about one 
thousand cyclotrons to equal this output. Al- 
most a year after the first use of the atomic 
bomb, the first shipment of radioisotopes was 
made from Oak Ridge. By late 1947, the in- 
creased supply of radioisotopes permitted allo- 
cations for research in all fields. 
The production of radioisotopes is dependent 
primarily upon the pile facilities of the Atomic 
Energy Commission and to a minor extent on 
particle accelerators. The procurement of radio- 
isotopes from the Atomic Energy Commission 
must conform to certain procedures which will 
be described. The widespread use of radioiso- 
topes introduces a requirement for precaution 
in order to avoid the hazards of these radio- 
active materials. 
CYCLOTRON PRODUCTION OF RADIOISOTOPES 
The two outstanding instruments for the 
production of radioisotopes are the chain re- 
acting pile and the cyclotron. Versatility in 
isotope production is the outstanding feature 
of the cyclotron. There are other particle 
accelerators which may be used for isotope 
production. However, the cyclotron, at present, 
is the principal apparatus together with the 
pile for the production of radioisotopes. The 
number of particle accelerators—cyclotrons, 
synchrotons, betatrons, linear accelerators, etc., 
in operation in about 50 U. S. laboratories will 
be doubled by construction already scheduled. 
At least two dozen of the new atom smashers 
will be capable of bombarding the nucleus with 
particles accelerated to more than 100 million 
volts. The giant 184 inch synchrocyclotron at 
the Radiation Laboratory of the University of 
California, Berkeley, is the world’s greatest at 
this time. A proton synchrotron is being con- 
structed at Brookhaven National Laboratory 
to yield protons with energies between two 
and three billion electron volts (Bev). A simi- 
114 RADIOLOGICAL DEFENSE 
lar machine is being constructed at Berkeley to 
yield protons with energies between six and 
seven Bev. 
The essential component of the cyclotron 
consists of two short, hollow, half cylinders, 
called dees. The dees ‘are mounted inside a 
vacuum chamber between the poles of a power- 
ful electromagnet and connected externally to a 
high frequency alternating current generator. 
When a trace of hydrogen gas is introduced 
into the evacuated chamber, a hot wire filament 
ionizes some of the hydrogen atoms producing 
the protons. By alternating the charges on the 
dees, the protons move through the strong 
magnetic field of the huge magnet in a circular 
pattern. As the potential reverses periodically 
in the dees, the proton travels faster and faster 
moving in ever expanding circles until it passes 
out through a narrow open window. In this 
manner the beam is used to bombard various 
substances which are studied by various means 
of detecting devices. Perhaps the most inter- 
esting fundamental principle that makes the 
cyclotron work at all is the fact that the time 
required for charged particles to make half the 
turn within the dees is the same for all speeds. 
The faster a particle travels, the larger is the 
circle it must travel, thus keeping the time 
constant. Hence, with a constant frequency 
with an alternating current supply, some par- 
ticles may be just starting to move while others 
farther out may be moving with higher speeds. 
When the hydrogen in the evacuated cham- 
ber in the cyclotron is replaced by deuterium, 
a beam of high energy deuterons is obtained. 
If helium gas is used in place of deuterons, 
many of the atoms become doubly ionized in 
the cyclotrons and thus emerge from the cyclo- 
tron window with an energy double that of the 
deuterons and protons. By increasing or de- 
creasing the frequency of the potential applied 
to the dees and properly adjusting the mag- 
netic field, various energies of protons, deute- 
rons, or«alpha particles of 1 Mev and up become 
available. 
Cyclotron targets are bombarded in two loca- 
tions; in the external beam and on a probe. 
By deflecting the deuteron beam out of its last 
circle in the cyclotron chamber by means of a 
high negative potential on a deflector electrode, 
the beam can be made to pass through a thin 
aluminum alloy window at the side of the 
vacuum chamber. With a suitable external 
target chamber low melting or volatile mate- 
rials such as sodium, red phosphorus, or salts 
can be bombarded on water-cooled plates in an 
inert gas atmosphere, such as helium. Because 
only a fraction of the total number of ions 
accelerated can be directed into an external 
beam, the production efficiency of this method 
of bombardment is comparatively low. 
In utilizing the probe for bombardments, the 
problem of power dissipation seriously limits 
this method. Here the target material is fas- 
tened to a water cooled target head and inserted 
into the vacuum chamber to a point nearer the 
middle of the gap between the end of the dees. 
In this location, the target intercepts the circu- 
lating ion beam in its final circle of the cham- 
ber. In order to spread the beam over a large 
area, the target head is bent so the beam hits 
the target at a small angle. The bombarded 
area is still further increased by making the 
target head oscillate. When using probe targets, 
such as a cobalt-copper telluride for making 
1-130, more than half of the activity is lost 
by volatilization. 
The yields of isotopes by cyclotron produc- 
tion depend upon beam current, voltage, and 
fraction of target element in the target mate- 
rial. Of course, the yield decreases with vola- 
tilization of the product and target. 
If the cyclotron target is beryllium metal, a 
high yield of neutrons from the reaction 
,Be9 + aH2 5B10 + on1 
Maj. Dauer received his A.B, and M.S. degrees 
from New York University where he majored in 
the biological-physical sciences. He has been 
assigned to the Army School of Roentgenology, 
the Manhattan Engineering Project and the 
Radiological Branch, Military Applications Divi- 
sion, Atomic Energy Commission. He participated 
in the Bikini tests as a Radiological Monitor and 
was Operations Officer with the Atomic Energy 
Proving Ground Group for the Eniwetok tests. 
Major Dauer received his certification as a 
Radiation Physicist by the American Board of 
Radiology in 1948. 
115 RADIOLOGICAL DEFENSE 
is obtained. For 14 Mev deuterons, these neu- 
trons have a maximum energy of 18 Mev and 
a high flux of fast neutrons exist directly be- 
hind the target. 
The 'cyclotron is able to produce all the 
synthetic radioisotopes which are known. Table 
1 lists some of the cyclotron produced radio- 
isotopes. 
PILE PRODUCTION OF RADIOISOTOPES 
There are three ways in which neutrons in 
the pile produce radioisotopes: (1) by splitting 
atoms of fissionable uranium into new atoms 
of entirely different elements—fission products, 
so-called—which are radioactive themselves; 
(2) by being captured in the nuclei of atoms 
of special “target material” inserted into the 
pile, turning them into heavier isotopes of the 
same element; (3) by altering the electrical 
charge of the nuclei of atoms of target mate- 
rial, thereby transmuting them into isotopes of 
a different element. 
Uranium fission products removed from the 
pile contain a great variety of radioactive 
materials, which—in method (1) above—can 
be extracted and purified by chemical means. 
However, the radioisotopes obtained are all 
those of elements near the center of the atomic 
scale between zinc (30) and gadolinium (64). 
With the exception of iodine 131, these do not 
now enter significantly into medical, biological, 
agricultural, or most industrial processes. 
Therefore, most of the radioisotopes supplied 
by Oak Ridge must be prepared by methods 
(2) and (3). These call for the preparation 
and pile irradiation *of special target materials. 
Phosphorus 32, a widely used radioisotope, can 
be produced by both methods and may be used 
to illustrate. 
In the production of phosphorus 32 by “neu- 
tron capture,” method (2), phosphorus 31, con- 
tained in phosphate, is put into aluminum cans 
which are set in holes in a graphite block and 
pushed into the center of the pile. Each atom 
of the stable element phosphorus 31 that cap- 
tures a neutron becomes phosphorus 32. But 
not enough neutrons are present in “low flux” 
piles to convert more than a small proportion 
of the phosphorus atoms to the radioactive 
state. Hence the phosphorus 32 is still much 
diluted with phosphorus 31, and the treated 
phosphate is not highly radioactive. 
In practice, therefore, phosphorus 32 is 
usually produced by method (3), “transmuta- 
tion,” This process starts with a target element 
different from the element of which an isotope 
is desired. Sulfur is the target for the produc- 
tion of phosphorus 32. Bombardment by neu- 
trons in the pile changes the electrical charge 
of the nuclei of some of the sulfur atoms, and 
thus transmutes them into phosphorus 32. 
When the sample has been removed from the 
pile, the radioactive phosphorus can be chemi- 
cally separated from the target sulfur. Phos- 
phorus 32 in a very pure form, high in radio- 
activity, can thus be obtained. Unfortunately 
many important radioisotopes—those of cal- 
cium, iron, and zinc, for instance—cannot 
effectively be made by transmutation. They can 
be produced only by neutron capture, and this, 
as stated above, gives a product low in radio- 
activity. When a pile of higher neutron flux 
becomes available, it will be possible to produce 
radioisotopes of greater usefulness for re- 
search. 
From the preparation of the target material 
to the final shipment of the product, the pro- 
duction of radioisotopes demands skilled per- 
sonnel and special equipment. When the pile 
is shut down for the removal of the irradiated 
samples, each member of the team of workers 
must know precisely his assignment in the 
operation and carry it out quickly and without 
error. Geiger counters and other radiation de- 
tection equipment must be used constantly to 
check the radiation present. In subsequent 
chemical treatment of materials, the work must 
be carried on behind lead shields, the workers 
using tongs and mirrors to avoid exposure. 
Many chemical operations are conducted inside 
a “hot lab,” a room with thick concrete walls 
in which apparatus is manipulated from out- 
side by remote control devices, the chemist 
viewing his work through periscopes. Each 
radioisotope, moreover, is a separate produc- 
tion problem, involving its own combination of 
requirements—for target material, irradiation 
time, chemical treatment, safety precautions, 
116 RADIOLOGICAL DEFENSE 
and the rigid time limits associated with its 
inflexible half-life. 
Table 2 includes some of the more important 
pile isotopes useful in biological and medical 
sciences. 
PROCUREMENT OF RADIOISOTOPES 
The program for the distribution of pile- 
produced isotopes was formulated with the 
assistance of the best scientific advice obtain- 
able. Early in 1946, at the request of the Man- 
hattan Project, the president of the National 
Academy of Sciences nominated a panel of 
distinguished scientists from which an interim 
Advisory Committee on Isotope Distribution 
Policy was formed with two members experi- 
enced in each of the major fields of isotope 
application. This group was largely responsible 
for establishing the policies that have guided 
the distribution program since its inception. 
Originally, radioisotopes were allocated in 
the following order of priority: (1) for pub- 
lishable research in the fundamental sciences, 
including human tracer applications, requiring 
relatively small samples; (2) for therapeutic, 
diagnostic, and tracer applications in human 
beings and publishable research in the funda-* 
mental sciences requiring larger samples; (3) 
for training and education by accredited insti- 
tutions in the techniques and applications of 
radioisotopes; and (4) for publishable research 
in the applied sciences, including industrial re- 
search. Now, however, production has increased 
to the point where it is not necessary to apply 
priorities to the distribution of the more im- 
portant isotopes. Radioisotopes are made avail- 
able to individuals only through institutions 
that have the personnel and equipment to 
handle them usefully and safely. Secondary 
distribution is not permitted without specific 
authorization. 
At present 100 kinds of available radioiso- 
topes are listed and described in the AEG Cata- 
logue and Price List issued by the Isotopes 
Division. Now prospective purchasers submit 
an application describing the research they pro- 
pose and their facilities for radiation measure- 
ment and health safety monitoring, and agree 
to publish the results of their investigations. 
Applications are reviewed by scientists in the 
Isotopes Division and if necessary by the Sub- 
committee on General Applications and by the 
Subcommittee on Human Applications when 
such use is contemplated. In the two years of 
the project’s operation, 1,742 applications have 
been received and 1,700 approved. 
By the end of June 1948, 3,136 shipments 
of pile-produced radioisotopes had been sent 
from Oak Ridge to users outside the Commis- 
sion in 33 states of the United States, the 
District of Columbia, and Hawaii. The recipi- 
ents were 236 institutions: 54 medical organi- 
zations and hospitals, 111 educational institu- 
tions, 53 industrial organizations, and 18 pub- 
lic and private nonprofit research institutions. 
Within these institutions more than 385 differ- 
ent departments are using radioisotopes. 
SHIPPING OF RADIOACTIVE MATERIALS 
The widespread use of radioisotopes and 
their shipment to various laboratories has been 
a serious problem. In order to provide adequate 
protection, the Interstate Commerce Commis- 
sion promulgated regulations for controlling 
shipment of radioactive materials. The most 
pertinent points of this regulation* are ab- 
stracted below. 
1. Radioactive Materials: 
a. Group I. Radioactive materials 
that emit gamma rays only or 
gamma rays and alpha and/or 
beta rays. 
b. Group II. Radioactive materials 
that emit neutrons only or neu- 
trons and alpha, beta and/or 
gamma rays. 
c. Group III. Radioactive materials 
emit alpha or beta rays only. 
2. Packaging and Shielding Requirements: 
a. Radium, plutonium or strontium 
must be packed in an inner 
metal container of stainless 
steel, malleable iron or brass, 
not more than 3 in. in diameter 
or 8 in. in length, minimum 
wall thickness Vs in. and hav- 
ing screw closure. 
* Federal Register, Vol. 12, No. 220, pages 7329—7333. 
117 RADIOLOGICAL DEFENSE 
b. Fogging of undeveloped film at 
15 ft for 24 hrs must not ex- 
ceed that produced by 11.5 mr 
of gamma rays of radium fil- 
tered by V2 in. of lead. 
c. Minimum dimensions of outside 
container is 4 in. 
d. Outside container must be of 
such design that gamma radia- 
tion will not exceed 200 mr/hr 
at surface. 
e. Group I radioactive materials 
must be so packed and shielded 
that gamma radiation at one 
meter (39.3 in.) from radio- 
active source does not exceed 
10 mr/hr. 
f. Group II radioactive materials 
must be so shielded and packed 
as to prevent the escape of pri- 
mary alpha or beta radiation, 
and secondary radiation at the 
surface of the package must 
not exceed 0.4 mr/hr (10 
mr/24 hrs). 
g. Liquid radioactive materials 
must be surrounded by absorb- 
ent material which will com- 
pletely absorb liquid in case of 
breakage. Materials packed in 
metal tube do not require ab- 
sorbent packing. 
3. Labels: 
a. Each outside container of Group 
I or II radioactive materials 
must carry the special red on 
white label with certification. 
b. Each outside container of Group 
III radioactive materials must 
carry the special blue on white 
label with certification. 
4. Exemptions: 
Radioactive material that meets all 
of the following conditions is ex- 
empt from prescribed packaging, 
marking and labeling requirements: 
a. Package must be such that there 
can be no leakage during nor- 
mal transportation. 
b. Package must contain not more 
than: 
(1) 0,1 me of radium or polo- 
nium. 
(2) That amount of Sr89, Sr90 or 
Ba140 which distintegrates at 
a rate of more than 5 X 10° 
atoms/sec (0.13 me). 
(3) That amount of any other 
radioactive substance which 
disintegrates at a rate of 
more than 50 X 106 atoms/ 
sec (1.3 me). 
c. Package must be such that no 
significant alpha, beta or neu- 
tron radiation is emitted at the 
surface of the package and the 
gamma radiation at any sur- 
face must be less than 0.4 mr/ 
hr (10 mr/24 hrs). 
HANDLING OF RADIOISOTOPES 
Personnel handling radioisotopes must take 
adequate steps to prevent exposure to high 
intensities of radiation. Likewise, equipment 
and facilities must be properly designed to 
provide protection for laboratory personnel 
and minimize radioactive contamination. The 
amount of external radiation not in excess of 
300 millirems per week has been proposed as 
the permissible exposure. 
Every worker with radioactive materials is 
exposed to potential personal danger from two 
directions. The first is from radiation external 
to the body, and originating from the source, 
from contamination outside the source con- 
tainer, or from contamination of one’s clothes 
or person. The second is from internal radia- 
tion originating from the inhalation of radio- 
active material, from the ingestion of radio- 
active material, or from radioactively contami- 
nated wounds. When the external radiation 
hazard is not significant, the problem reduces 
to that of maintaining a radiochemically 
“aseptic” technique and is similar in principle 
to that met in handling infectious bacteria. 
Contamination problems are, in general, a 
function of the half-life of the radioisotope 
which is involved, while the radiation health 
118 RADIOLOGICAL DEFENSE 
hazard is dependent upon the amount and 
energy of the activity present. For example, 
both sodium 24 (14.8 hrs half-life, 1.4 Mev beta, 
1.4 and 2.8 Mev gamma) and potassium 42 
(12.4 hrs half-life, 75 percent 8.58 Mev beta, 
25 percent 2.07 Mev beta, and 1.51 Mev 
gamma) present substantial health hazards in 
millicurie amounts since they emit high energy 
beta and gamma radiations but only minor con- 
tamination hazards since they have short half- 
lives. On the other hand, when working with 
high millicurie strengths of a pure beta emitter 
with a long half-life (for example, Ca 45, 180 
days half-life, 0.3 Mev beta), the health hazard 
of external radiation will be small while the 
contamination hazard is considerable. 
Here are listed some general rules for han- 
dling beta and gamma emitters in a typical 
“hot” laboratory: 
1. No person should enter a “hot” labora- 
tory unless he has a reason to be 
there. Visitors especially should be 
limited. 
2. Laboratory coats usually worn in the 
“cold” laboratory should be removed 
before entering the “hot” laboratory. 
3. All persons working in the “hot” 
laboratory should wear a laboratory 
coat; such coat to be kept and worn in 
“hot” laboratory only. 
4. Each person should monitor bench top, 
apparatus and material with which he 
is working before and after comple- 
tion of the work. Meter readings are 
to be recorded in the “hot” laboratory 
notebook. The following tolerance 
levels of radioactive contamination 
should not be exceeded: 
Shoes 1,000 counts per minute 
(cpm). 
Laboratory coats and 500 cpm. 
clothing. 
Table tops, floors, etc. 300 cpm with counter in 
contact. 
Inside intermittently 4,000 cpm. 
used hood. 
Smear test on table Zero cpm. 
tops, floors, appa- 
ratus, etc. (2 sq. in. 
filter paper smeared 
over 12 sq. in. and 
checked with a coun- 
ter). 
Boxes for shipment by Zero epm with smear test, 
air or mail. Total radiation at out- 
side surface of box in 
accordance with Inter- 
state Commerce Com- 
mision Regulations. 
All laboratory and op- All areas with radiation 
erating areas. greater than 12.5 mr/hr 
should be posted. 
5. Before leaving “hot” laboratory, hands 
should be monitored and scrupulously 
cleaned until smear tests yield a read- 
ing of zero. Under no circumstances 
should direct readings on the hands 
exceed 700 cpm. If it is not possible 
to reduce the activity to this degree, 
a responsible individual within the 
laboratory should be informed imme- 
diately. 
6. No work should be done on bench tops 
unless absorbent paper is first laid 
down. 
7. When work is completed, each person 
should individually clean and/or dis- 
pose of contaminated material. 
8. Activity should be disposed of in waste 
jars kept in each sink; paper towels 
should be disposed of in special con- 
tainers, etc. 
9. The “hot” laboratory should receive a 
general clean-up and monitoring the 
last day of each week. 
10. All unused activities should be kept in 
the “hot” laboratory safe. The re- 
moval of any activity should be done 
early with the approval of a respon- 
sible individual within the laboratory. 
11. All activities entering or leaving the 
“hot” laboratory—for shipping, for 
use in a “cold” laboratory, or for any 
other reason—should be monitored 
and a dated and initialed record en- 
tered in the “hot” laboratory log book. 
12. No Smoking, Eating or Drinking 
should be permitted in the “hot” 
laboratory at any time. 
119 RADIOLOGICAL DEFENSE 
DISPOSAL OF RADIOACTIVE WASTES 
burial purposes, and an- 
alyses should be provided 
of the soil, so that the fate 
of the material can be de- 
termined to be a safe dilu- 
tion. 
b. The material should be 
buried at a minimum depth 
of 5 feet. 
3. Radioactive materials may be buried 
when properly enclosed in a container 
sufficiently well constructed to retain 
the isotope for a period of five years, 
provided: 
a. For materials having half- 
lives of 2 years, the radio- 
isotope is adulterated, 
prior to enclosure, with 
sufficient quantities of con- 
crete or stable isotopes of 
the same element to reduce 
the dissipation of energy 
from the remaining ac- 
tivity at the end of 5 years 
to 4.15 ergs per gram of 
adulterant. The dosage 
rate at the surface of the 
container shall not exceed 
6.25 mr/hr. 
b. For materials having half- 
lives of 2 years, the radio- 
isotope should be adulter- 
ated, prior to enclosure, 
with sufficient quantities 
of concrete or stable iso- 
tope to reduce the dissipa- 
tion of energy to the ex- 
tent of 4.15 ergs per gram 
of adulterant per day. 
c. The burial is made in com- 
pliance with 2a above. 
4. Materials may be buried at sea when 
enclosed under conditions stated in 3 
above and buried beyond the three- 
mile limit. 
5. Materials containing radioisotopes may 
may be incinerated if the calculations 
of safe permissible concentration in 
With an expansion of the radioisotope dis- 
tribution program of the AEG, it is becoming 
increasingly apparent that some guides must 
be established for the proper disposal of waste 
radioisotopes. There has been no general agree- 
ment, as yet, regarding the recommended prac- 
tices for waste disposal. Nevertheless, the fol- 
lowing suggestions are offered: 
1. Radioisotopes having half-lives of less 
than 30 days may be disposed of in the 
sewer, provided the daily volume of 
water flowing through the particular 
outlet used is sufficient to dilute the 
radioisotope to 0.1 millicuries per liter 
or to safe limits of concentration as 
set for that particular isotope. This 
practice should be contingent on cer- 
tain provisions such as: 
a. The maximum activity dis- 
posed of in any one insti- 
tution should not exceed 
100 me. per week. 
b. Regular radiation surveys of 
the plumbing fixtures, 
c. Appropriate surveys before 
repairing the plumbing 
between the disposal out- 
let and the main sewer. 
2. Radioisotopes of any half-life may be 
buried in the earth, provided that they 
are uniformly diluted with stable iso- 
topes of the same element to the ex- 
tent that 4.15 ergs (equivalent to 50 
mr/day in tissue) is dissipated per 
gram of element per day, provided: 
a. The burial is made only in 
suitably selected areas 
which are in possession of 
and will be maintained by 
the user. These areas 
should be properly marked 
and enclosed with suitable 
fencing. In case of pos- 
sible release into the soil, 
a thorough geological in- 
vestigation should be made 
of the area selected for 
120 RADIOLOGICAL DEFENSE 
exhaust air and in disposed ashes are 
based on known values. In the absence 
of specific information, the following 
assumptions should be made: 
a. For the air calculation, that 
all the active material es- 
capes in the air. 
b. For the handling of the 
ashes, that all the activity 
is retained in the ashes. 
The ashes and/or effluent 
residue are then disposed 
of in accordance with 2 
and 3. 
Some 
Table 1 
cyclotron produced radioactive isotopes 
of interest 
Production 
Bombardment 
Criteria* 
Isotope 
Half-life 
reaction 
location 
for listing 
Be7 
43d 
Li (d,n) .... 
Ext 
a 
Probe.. .. 
C11 
20.5m. . . . 
B (d,n) 
Ext 
b 
F18 
112m. . . . 
0 (d,n) 
Ext 
a 
Probe.. . . 
Na22 
3.0y 
Mg (d,a) . 
Ext 
b 
Probe.. .. 
Si31 
170m 
Si (d,n).... 
Ext 
d 
Cl38 
37m 
Cl (d,p) ... 
Ext 
d 
Mn52 
6.5d 
Cr (d,2n). . . 
Probe.. . . 
b 
Mn54 
310d 
Fe (d,a) ... 
Probe., . . 
b 
Fe55 
4y 
Mn (d,2n) . . 
Probe.. . . 
be 
Fe59 
44d 
Co (n,p) 
(fast neu- 
tron) 
Probe.. . . 
be 
56 
85d 
57 
270d . . . 
Co58 
65d 
Fe (d,n) 
(d,n2n) . . 
Probe.. . . 
b 
Zn«5 
250d 
Cu (d,2n) . . . 
Probe.. . . 
b 
As74. . . . 
16d 
Ge (d,2n). . . 
Probe.. . . 
b 
Se75 
115d 
As (d,2n) . . 
Probe.. . . 
b 
Kr(79.81). 
34h 
Br (d,2n) . . . 
Ext 
b 
Xe127 
34d 
I (d,2n) 
Ext 
b 
1130 
12.6h 
Te (d,2n) . . 
Ext 
a 
Hg197. . . . 
23h 
Au (d,2n) . . 
Probe.. . . 
b 
64h 
*Criteria for listing: (a) available only by bombardment with 
high energy 
positive ions, (b) carrier-free isotopes of these ele- 
ments available from the 
cyclotron, (c) 
isotopieally pure products 
best obtained with the cyclotron, (d) important isotopes with half- 
lives too short to use away from the source of production. 
Table 2 
Pile produced isotopes especially useful in the biological 
and medical sciences 
Isotope 
Half-life 
Reaction 
C 14 
5100 yr 
n, proton 
n, gamma 
n, proton 
n, proton 
n, gamma 
n, alpha 
n, gamma 
n, proton 
n, gamma 
n, gamma 
n, gamma 
n, gamma 
n, gamma 
n, gamma 
n, gamma 
daughter of n, gamma 
Ge77 
n, gamma 
n, gamma 
fission products mixture 
only 
fission products mixture 
only 
n, gamma 
n, gamma 
n, gamma 
n, gamma, mixture only 
n, gamma, mixture only 
daughter of n, gamma 
Sn 125 
fission product or daugh- 
ter of n, gamma Te 131 
Na 24 
14.8 hr 
P 32 
14.3 d 
S 35 
87 d 
Cl 36 .... 
106 hr 
A 37 
34 d 
K 42 
12.4 hr 
Ca 45 
180 d 
Fe 55 
Fe 59 
Co 60 
5.3 yr 
Ni 59 ... 
15 yr 
Cu 64 
12.8 hr 
Zn 65 
250 d 
As 76 
26.8 hr 
As 77 
Br 82 
40 hr 
34 hr 
Rb 86 
19.5 d 
Sr 89 
53 d 
Sr 90 
25 yr 
Mo 99 
67 hr 
Ag 110. . . . 
Ag 111 . . 
Sb 122 
225 d 
7.5 d 
2.8 d 
Sb 124 
60 d 
Sb 125 
2.7 yr 
I 131 
8 d 
121 RADIOLOGICAL DEFENSE 
TRACER TECHNIQUES 
Captain John R. Hogness, MC, USA 
Isotope Laboratory 
Army Medical Department Research and Graduate School 
Army Medical Center, Washington, D. C. 
No discussion of the medical aspects of 
atomic energy can be complete without some 
mention of the use of radioactive isotopes as 
tracers, for it is in this field that the greatest 
advances in medical science resulting from the 
work on the atomic bomb have so far occurred. 
It is the purpose of this discussion to present, 
in very general terms, some of the techniques 
applicable to the use of isotopic tracers in the 
field of biology. It is hoped that pointing out 
a few specific examples may lead to application 
of these techniques in various fields of medical 
interest. 
First let us define what we mean by a tracer 
substance. An isotopic tracer is an isotope of 
an element substituted for a “normal” atom 
of the same element and introduced into a 
biological system either as the element itself 
or as one of the constituents of a given com- 
pound. Such an isotope behaves the same as 
a “normal” atom chemically and in the body. 
However, because of certain physical char- 
acteristics, either radioactive disintegration or 
a slight difference in mass (in the case of the 
stable isotopes), we are able to distinguish 
these atoms in the laboratory, whereas the 
body cannot. Hence, by knowing that a mole- 
cule is “tagged” with an isotope, we can trace 
the course of that molecule through a biological 
system. 
As an illustration, let us suppose that a wolf 
pack has been discovered in a given region. 
By some means we manage to catch one wolf. 
We paint him with luminous paint and then 
release him. If on any future night we see 
this luminous wolf, then, knowing that wolves 
travel in packs, we know that the entire pack 
is in the vicinity. 
Similarly, we may “tag” a compound and 
administer it to a living organism. Because 
of its peculiar properties we can then follow 
its course through, various stages of metab- 
olism in the organism. 
Radioactive isotopes of a large proportion 
of the elements essential to life, namely, hydro- 
gen, carbon, sodium, phosphorus, sulfur, 
chlorine, potassium, calcium, iron, cobalt, cop- 
per, zinc and iodine, can now be produced in 
the atomic pile or the cyclotron. Many of these 
are available for research and therapeutic pur- 
poses. However, for administration to human 
beings, only isotopes with a suitable half-life 
or excretion rate or a combination of these 
two (expressed as the “biological half-life”) 
may be used. Radioactive isotopes which de- 
posit in tissue and remain for long periods 
of time are undesirable because of the pro- 
duction of long term irradiation effects and 
the possibility of the development of malignant 
degeneration. 
The Production of Tracer Compounds 
As mentioned before, isotopes may be used 
in tracer work as the element itself, as in the 
case of Sodium 24 in studies of circulation 
and sodium space. More commonly, however, 
such an isotope is incorporated into a given 
molecule and by its presence, the course of this 
molecule traced throughout a biological system. 
For example, urea may be synthesized using 
radioactive Carbon 14 as the carbon atom in 
the molecule, and the fate of this compound 
studied in animals. 
Such “tagged” compounds may be prepared 
for use in two main ways: 
1. Chemical Synthesis. Ordinary methods 
of organic synthesis as carried out 
by an organic chemist in the labora- 
tory may be adapted to the synthesis 
of radioactive compounds. Special 
micro-techniques and radiochemical 
122 RADIOLOGICAL DEFENSE 
precautions are essential, however, in 
the application of organic synthetic 
procedures to work with radioiso- 
topes. Most compounds now available 
in this new field have been produced 
in the laboratory by such means. 
2. Biosynthesis. 
a. Animal synthesis. 
Some compounds useful in re- 
search are not readily made in 
the laboratory but are synthe- 
sized by animals in the course 
of their normal metabolic proc- 
esses. In such cases, it is 
simpler to administer the iso- 
tope to an animal in a simple 
and readily obtainable form 
and then isolate the metabolic 
product from the animal. Such 
a metabolite will, then, be 
“labeled” with the isotope 
administered and may be puri- 
fied and used in further re- 
search. 
b. Synthesis by Plants and Micro- 
organisms. 
As in the case of animals, 
plants and micro-organisms 
may also be used to synthesize 
“tagged” compounds. Again, 
the isotope is made available 
to the organism as part of the 
nutrient medium (including 
the surrounding air), and the 
“tagged” compound is later 
isolated from the organism. 
The utilization of animals, 
plants, and micro-organisms in 
the synthesis of tagged com- 
pounds is still in its infancy 
but this technique will prob- 
ably be used to a far greater 
extent in the near future. One 
of the major difficulties with 
this method is that it is usually 
impossible to control the rela- 
tive position of the isotope in 
the chemical structure of the 
compound synthesized in this 
fashion. The fact that such 
synthesis must be carried out 
in closed systems, for the most 
part, provides a serious draw- 
back in large scale work of this 
nature. 
Let us now assume, however, that by one 
of these three methods, probably the first, we 
have obtained a radioactive, “labeled” com- 
pound—perhaps a vitamin containing radio- 
active Carbon 14 and wish to study its meta- 
bolic path in an animal. How might we ap- 
proach the problem? 
Gross Metabolism Studies 
In studying the fate of a drug in an animal, 
it is first necessary to determine the amount 
of the drug or its metabolites excreted in the 
urine, feces, and exhaled air as well as the 
amount present in the various body tissues 
as a function of time; in other words, the 
“gross metabolism”. Suppose then, we admin- 
ister the C14 labeled vitamin to a series of mice, 
place them in a closed system and collect urine, 
feces and C02. At various time intervals, the 
animals are sacrificed and the various organs 
and tissues removed. All these products as well 
as the tissues are then analyzed for radio- 
activity. In the case of compounds containing 
Carbon 14, this may be done in one of several 
ways. Body fluids such as urine or plasma, 
or extracts of such products as feces may 
be plated directly onto planchets and the 
activity determined with an electronic counting 
apparatus (see Assay, below). The exhaled C02 
may be absorbed in NaOH and then precipi- 
tated with barium chloride as barium car- 
Captain Hogness received his B.S. in Chemistry 
from the University of Chicago in 1943. After 
receiving his M.D. from that school, he interned 
at the Presbyterian Hospital, New York City 
until 1947. He was a Radiobiologist at Los 
Alamos Scientific Laboratories from 1947 until 
1948 and from 1948 to 1949 was a staff member 
of the Isotope Laboratory at the Army Medical 
Department Research and Graduate School, Army 
Medical Center, Washington, D. C. 
123 RADIOLOGICAL DEFENSE 
bonate. This precipitate may then be' analyzed 
for radioactivity. 
Perhaps the most commonly used technique 
of analyzing for C14 is that of combustion. 
This method involves the burning of all organic 
material to C02 and collection and precipitation 
as mentioned above for “exhaled C02”. This 
technique is applicable to all organic materials, 
but is especially useful in analysis of C14 
activity in tissues. 
Thus we see how a gross metabolism study 
in the case of a Carbon 14-containing com- 
pound might be carried out. By determining 
the amount of radioactivity present in any of 
the excretory products or tissues we know the 
fraction of the originally administered com- 
pound or its metabolites present. Compounds 
containing other isotopes would each require 
special techniques or modifications of the above 
methods, depending upon the element and the 
type of radiation involved. 
Assay of Radioactive Materials 
In order that those studies mentioned above 
may be carried out on a quantitative basis, 
it is necessary that the originally administered 
compound as well as the final products and 
tissues be assayed accurately for the amount 
of radioactivity each contains. The determina- 
tion of radioactivity in a specific substance 
depends upon the isotope involved, or more 
specifically, the properties of the radioactive 
particles emitted by that isotope. 
A discussion of various types of instruments 
has already been presented. However, in gen- 
eral, those isotopes emitting beta and gamma 
rays may be assayed with a system employing 
a Geiger-Mueller tube as its essential unit, the 
thickness of the wall of the tube in each case 
being dependent upon the energy and penetrat- 
ing ability of the beta or gamma ray involved. 
Carbon 14, for example since it emits a very 
weak beta particle, requires a Geiger-Mueller 
tube with a thin mica window for assay 
work. Alpha emitters, because of the extremely 
low penetrating power and high ionizing power 
of the alpha particles, require an instrument 
of the “proportional counter” type. Alpha 
emission is encountered for the most part 
among the heavier elements, especially those 
involved in the processes of fission. 
In the case of the stable isotopes, where 
there is no radioactivity involved, analysis 
must be made on the basis of slight differences 
in mass between isotopes. Assay in this 
instance becomes far more difficult and time 
consuming. Various methods of analysis have 
been developed, the commonest technique being 
that involving the use of the mass spectrom- 
eter. 
Radioautographs 
Once the gross distribution of radioactivity 
in the body has been determined, it is of inter- 
est to attempt to localize the radioactive mate- 
rial within the specific tissue. For this purpose 
the technique of radioautography (or auto- 
radiography) is extremely useful. 
Radioautography implies that the tissue (or 
other substance) containing radioactive mate- 
rial takes a picture of itself. This is, in fact, 
precisely what occurs. The various emanations 
from radioactive materials will, like X-rays, 
darken photographic plates. Thus, when a sec- 
tion of tissue containing a radioactive sub- 
stance is placed in contact with a photographic 
film, allowed to remain in contact for a suit- 
able exposure time and the film then developed, 
darkening will be apparent on the film in the 
areas corresponding to those were radioactiv- 
ity was present in the tissue. 
Again, take the example of the mouse 
injected with a radioactive Carbon 14 “tagged” 
vitamin. Assume this compound is present in 
the kidney (among other organs) and we wish 
to know just where in the kidney the vitamin 
is located. We can make a tissue section and 
place it next to a photographic film. After 
leaving the film and tissue in contact for a 
period of several weeks, we then develop the 
film. It is possible to compare the dark, 
exposed, areas on the film with the tissue sec- 
tion and, correlating these, pick out the part 
of the tissue from which radiation was emanat- 
ing and hence the area in which the vitamin 
or its metabolite is located. 
124 RADIOLOGICAL DEFENSE 
There are, in general, three modifications of 
radioautographic technique in use at present, 
each having its own application. 
a. The tissue section may be mounted on 
a glass slide in the ordinary manner, 
and the photographic film brought in 
close contact with the slide and fixed 
in position during the exposure 
period. This technique has the dis- 
advantages that the tissue is not in 
as close approximation to the film as 
might be desired, and also that once 
developed, the film and the tissue sec- 
tion must be viewed separately rather 
than simultaneously, under the same 
microscope. It has the advantage that 
after exposure the tissue section may 
be stained without fear of affecting 
the emulsion. 
b. The tissue section may be mounted 
directly on the film itself where it 
will adhere very firmly. Following 
exposure and development of the film 
(with the tissue still adherent), it 
will be possible to focus through the 
tissue to the film and thus view both 
simultaneously. 
c. A third method of making radioauto- 
graphs involves the spreading of 
photographic emulsions directly over 
the tissue mounted on a slide. This 
provides very close contact between 
tissue and emulsion but presents diffi- 
culties in staining the section of tissue 
afterwards. 
In some instances in the making of radio- 
autographs, using special emulsions, it is pos- 
sible to distinguish not only darkened areas but 
definite tracks on the emulsion made by the 
particles given off by radioactive substances. 
By tracing several of these tracks back to a 
common point source, it may be possible to 
localize one individual radioactive atom in a 
specific part of one cell. This technique is par- 
ticularly applicable in the case of alpha emit- 
ters having a long decay chain. Recently emul- 
sions have been developed on which beta 
particles will produce tracks. 
Eadioautography has numerous applications 
in radiobiology, a few examples being in trac- 
ing iodine uptake by the thyroid gland, in the 
localization of strontium as well as plutonium 
and other heavy metals in bone, and in study- 
ing sodium exchange in the eye. 
Filter Paper Chromatography 
Another very useful technique in tracer 
work is that of filter paper chromatography. 
Chromatography as such was first used about 
one hundred years ago as a method of sepa- 
rating mixtures of various materials. More 
recently, this technique has been adapted for 
use in the separation of small amounts of 
radioactive compounds, by using long strips of 
filter paper in place of the customary absorp- 
tion columns. 
Briefly, the technique is as follows. Long 
strips of filter paper are suspended inside air- 
tight columns, the upper end of the strip being 
dipped into a solvent system such as, for 
example, a saturated solution of butanol in 
water. The air in the column is also saturated 
with the vapor phase of this system. A drop 
of solution containing the radioactive materials 
to be separated is then placed on the filter 
paper strip just down the strip from the point 
where it is immersed in the solvent system. 
Then, as the solvent runs down the filter paper 
by wick action, the various radioactive com- 
ponents spread out on the strip according to 
their differential solubilities in the solvent, the 
most soluble migrating the fastest and the 
least soluble the slowest. These compounds are 
therefore effectively separated according to 
their solubilities. The strip is then dried and 
placed in contact with an X-ray film for a suit- 
able period and a radioautograph of the strip 
is made. By examining the autograph, it is 
possible to determine the number of radio- 
active compounds present and their location 
along the strip. From this point on, it is neces- 
sary to identify each radioactive band on the 
strip. This can be done chemically, by utilizing 
the physical properties of the individual com- 
ponents, or occasionally by bacterial assay. 
Filter paper chromatography has been used 
in such problems as the separation of amino 
acids in tissue hydrolysates or plasma and the 
125 RADIOLOGICAL DEFENSE 
separation of metabolites of drugs in the urine 
and other body fluids and tissues. 
Examples of Applications of Tracer Technique 
It will perhaps be interesting and instructive 
to cite a few examples of biological tracer 
studies already carried out. From these ex- 
amples it is hoped that possible applications in 
other fields may be suggested. 
In the clinical field the applications of radio- 
active tracers are very extensive and the pos- 
sibilities are greater still. Some examples of 
these applications such as the use of Sodium 
24 in studies of circulation and body sodium 
space and the use of Iodine 131 in studies of 
thyroid metabolism have already been men- 
tioned. Other clinical applications include the 
use of radioactive sodium in studies of sodium 
exchange across body membranes, the use of 
radioactive iron in studies of red cell life and 
circulation, the use of Iodine 131 in studies of 
organic iodine turnover in the body, and the 
use of deuterium and possibly tritium (H3) 
in body water studies. 
The applications of tracer techniques to 
animal work are even more extensive than in 
clinical investigation because the number of 
isotopes that can be used safely in humans 
is quite limited. Much of the work done with 
animals concerns studies of the fate of drugs 
and other compounds in the body as well as 
determinations of the rate and mechanisms of 
synthesis of various body compounds. One 
example of the former type of study is the 
tracing of “tagged” vitamins mentioned previ- 
ously. Examples of the latter type include the 
administration of “tagged” acetate to animals 
and the study of its utilization in the forma- 
tion of body cholesterol, as well as the use of 
Phosphorus 32 in studies of the fate and 
synthesis of nucleic acids and nucleoproteins. 
Tracer materials offer an important new 
tool to the bio-medical investigator. Many sig- 
nificant advances have been made in the past 
three or four years through the use of isotope 
tracer techniques but the surface has barely 
been scratched. 
126 RADIOLOGICAL DEFENSE 
RADIOACTIVE ISOTOPES IN CLINICAL MEDICINE 
Captain Edgar Leifer, MC, USA 
Isotope Laboratory 
Army Medical Department Research and Graduate School 
Army Medical Center, 
Washington, D. C. 
The purpose of this lecture is to present a 
resume of the clinical uses of radioactive iso- 
topes. The major portion of the discussion 
will be confined to the diagnostic and thera,- 
peutic uses of the artificial isotopes but several 
experiments will also be mentioned to illustrate 
the potentialities of further investigations. 
The production of artificial radioactivity by 
the use of a radium-beryllium source for neu- 
trons, through the use of the cyclotron or 
the uranium pile, has made possible a great 
deal of work on the use of radioactive isotopes 
in human physiology and in the treatment of 
malignant diseases. Several years ago it might 
have been possible in a talk such as this to 
present a fairly complete review of isotopes 
in medical research. Studies have progressed 
so rapidly that this can no longer be done. Of 
necessity, therefore, the discussion of each of 
the isotopes will be brief. 
The first to be considered is radioactive 
sodium (Na24). Following its discovery in 
1934 it soon became apparent that this isotope 
of sodium possesses many characteristics 
which make it particularly suitable for physio- 
logical studies. It has a short half-life (14.8 
hours), is evenly distributed throughout the 
extracellular fluid, is a non-foreign and non- 
toxic substance. The radioactive atoms disinte- 
grate by the ejection of a beta ray and the 
emission of powerful gamma rays which makes 
it possible to use Na24 in in vivo experiments 
as well as in vitro. The quantities required 
in in vivo experiments produce an overall 
radiation of about 0.5 roentgen equivalent 
physical (rep), about as much as the chest 
receives in a routine chest X-ray. This isotope 
has been used in studies of electrolyte balance, 
extracellular sodium space, the mechanism of 
sodium shift in shock, and the transport of 
sodium through the skin, mucous membranes, 
the placenta and across the pulmonary epithe- 
lium in nebulized solutions. It has been used 
in the study of peripheral vascular disease and 
has been especially helpful in the determina- 
tion of levels of good circulation in cases where 
amputation is necessary. It has recently been 
reported to be useful as a diagnostic aid in 
cardiac circulation. 
Blumgart and Weiss in 1927 were the first 
to utilize radioactive substances in the study 
of the velocity of blood flow. They injected 
radium B into the antecubital vein of the 
upper extremity and studied the rate at which 
it would arrive in other extremities. Although 
it decayed with a half-life of 26 minutes, 
Radium D, an isotope of lead, was formed with 
a half-life of twenty-two years. This is de- 
posited in bone and produces a prolonged 
radiation effect. Sodium 24 as has been pointed 
out, has none of these objections. 
There are two methods for studying circula- 
tion in the extremities using Na24. 
1. Intravenous injection and study of the 
accumulation of Na24 in the tissues. 
2. Rate of removal of Na24 following 
intramuscular injection. 
Following an intravenous injection of Na24 
in the form of sodium chloride the time* 
required for the Na24 to flow through the blood 
vessels from the injection site to the site under 
investigation is determined with a Geiger- 
Mueller tube placed over the skin. Thus the 
circulation time from the antecubital vein to 
foot has been found to be about 30 sec. The 
circulation time itself is not significant as a 
measure of adequacy of blood flow as it has 
been shown to have such a large variation in 
normal subjects. However, the rate of uptake 
of radioactivity and the equilibrium point 
reached are to some degree a measure of the 
volume of blood to an extremity if accurate 
127 RADIOLOGICAL DEFENSE 
standardization of the amount of injected 
radioactive sodium is made. In cases of 
extremely poor peripheral circulation if one 
determines the tissue radioactivity at different 
levels along an extremity, one can arrive at 
a line of demarcation between adequate and 
inadequate circulation which will give an 
amputation level. This method has provided 
useful information for the clinical evaluation 
of symptoms, circulatory insufficiency and the 
results of various forms of therapy in pe- 
ripheral vascular disease (arteriosclerosis, 
Buerger’s Disease, Raynaud’s Disease) largely 
in the hands of Quimbly and her co-workers. 
The second method of circulation study using 
radioactive sodium is the injection of Na24 
into the muscle, e.g. gastrocnemius muscle— 
the application of a Geiger counter directly 
over the injection site and study of the dis- 
appearance rate of radioactivity. This is most 
suitable for the study of drugs and the medical 
and surgical techniques for circulatory im- 
provement. 
Similar investigations by Tobias and co- 
workers have shown that in general there is 
a decreased circulation in patients suffering 
from rheumatoid arthritis which fits the clin- 
ical experience that many of these patients 
have cold extremities. 
At this point it might be proper to mention 
that although the therapy in rheumatoid ar- 
thritis is largely empirical, many clinics have 
obtained encouraging results using gold. To 
study its action, radioactive gold salts were 
used to determine the distribution of gold in 
tissue samples. In one series of experiments, 
the labeled gold was injected I.V. into normal 
rabbits and into rabbits suffering from a chem- 
ically induced arthritis. Among the findings are 
the relatively high uptake of gold by the liver, 
kidney, and bone marrow (sites of toxic reac- 
tions) and likewise a high uptake in the in- 
volved synovial tissue. This is confirmed in 
rheumatoid arthritis patients but is not the 
complete story as gold is taken up by all areas 
of inflammation. This, too, fits with the clinical 
impression that patients who have evidence of 
active inflammation of joints are benefited 
most by gold therapy. 
Since sodium is an extremely important 
cation component of tissue fluids, measure- 
ments of the dilution of tagged sodium atoms 
following their administration (allowing suffi- 
cient time for uniform mixing) are significant 
in determining the sodium space. Assuming a 
uniform distribution of sodium in the extra- 
cellular fluid compartment, the amount of 
radioactivity remaining in the body (amount 
injected minus the amount excreted) divided 
by the amount per unit volume of plasma 
(measured) gives the volume of fluid in which 
the sodium is dissolved, the so-called sodium 
space. The latter value usually runs about 
5 percent greater than the extracellular fluid 
volume due to the deposition of sodium in the 
bone. 
By determining the radioactivity in the 
urine, feces and blood plasma as a function 
of time, one can measure the sodium turnover 
of the body. 
The problems of circulation would be incom- 
plete without mention of the application of 
isotopes to problems of blood flow thru the 
heart in health and disease. 
If one injects Na24 into a vein and places a 
G. M. counter connected to a direct writing 
recorder over the precordium, one would 
expect to obtain an M shaped pattern—the 
first peak of the M as blood comes into the 
right heart and the second peak as blood comes 
into the left heart. This pattern has been called 
a radiocardiogram by Prinzmetal and his co- 
workers. The distance between the peaks repre- 
sents the pulmonary circulation time. In con- 
genital heart defects and in heart failure, 
one would expect variations from the normal 
M shaped pattern. Present methods for diag- 
nosis of congenital heart disease consist of 
Capt. Leifer received his Ph.D. in Physical 
Chemistry at Columbia University in 1941 and 
his M.D. at the College of Physicians and Sur- 
geons, Columbia University in 1946. He served 
as Radiobiologist at the Los Alamos Scientific 
Laboratories from 1947 to 1948 and from 1948 to 
1949 was Chief of the Isotope Laboratory, Army 
Medical Department Research and Graduate 
School, Army Medical Center, Washington, D. C. 
128 RADIOLOGICAL DEFENSE 
careful history and physical examination, 
X-ray and fluoroscopy of the heart, electro- 
cardiogram and cardiac catheterization. Radio- 
cardiography may become an additional impor- 
tant diagnostic tool, and has already been 
found useful in the diagnosis of patent ductus 
arteriosus. 
The absorption of ions, both positive and 
negative, from the gastro-intestinal tract as 
well as from the lungs, the skin, the vagina 
and other locations in the body has attracted 
considerable attention both from the stand- 
point of pure physiology and from the prac- 
tical aspect. These investigations find applica- 
tion in almost every specialty of medicine, 
e.g. otolaryngologists have been interested in 
the passage of nebulized solutions of Sodium 
24 to determine the efficacy of aerosols; ophthal- 
mologists have been interested in the passage 
of Sodium 24 across the ciliary body of the eye. 
Another isotope which has attracted consid- 
erable attention is radioactive iodine. Although 
there are several radioactive isotopes of iodine, 
this discussion will be limited to I131 which 
emits both beta and gamma rays. It has been 
known since the beginning of the century that 
radioactive materials have destructive powers 
as far as tissues are concerned and can be used 
to treat tumors providing the tumor is radio- 
sensitive. A most significant problem is the 
localization of the radiation in the tissue one 
desires to treat. Using the external radiation, 
one attempts to do this by using lead shields 
and cross firing. This protects the region 
around the irradiated area to a great extent 
but the skin over the tumor region may receive 
an excessively large dose. Using radioactive 
isotopes, one can take advantage of any of the 
following methods: 
(a) Physiological Concentrating Ability— 
to be illustrated by iodine. 
(b) Use of Colloids to carry radioactive 
element to a desired location in the 
reticulo-endothelial system, e.g. fol- 
lowing the intravenous injection of 
radioactive gold or chronic phosphate 
(P32) in the form of colloids, a marked 
selective irradiation of the liver and 
spleen can be produced 
(c) Local Implantation of radioactive ele- 
ments, e.g., radium needles or Cobalt 
60 in the form of wire for interstitial 
use. 
Radioactive iodine is important in therapy 
because of the marked physiological concen- 
trating ability of the thyroid gland. Of a total 
of 25 mg. of iodine found in the human organ- 
ism 15 mg. is in the thyroid gland. Since the 
normal thyroid gland weighs about 30 gm. 
and the total body about 60 Kg. the concen- 
trating ability of the thyroid gland is about 
2,000-3,000 times. Thus in cases of treatment 
which will be discussed, it can be readily seen 
that the thyroid gland will receive a large 
majority of the radiation of any amount of 
I131 fed to the normal person. 
In the thyroid gland the inorganic iodine is 
converted to monoiodotyrosine (as has been 
shown recently with I131), then diiodotyrosine 
which in turn is converted to thyroxine. The 
latter combines with a protein to form thyro- 
globulin the active hormone of the thyroid 
gland. 
Before undertaking any thyroid studies it 
was necessary to determine at what level the 
thyroid gland itself would begin to show bio- 
logical effects of radiation. 
Skanse investigated the effects of radioactive 
iodine on growing chicks and finds beginning 
effects on thyroid function for about 1700 reps 
(roentgen equivalent physicals). Similar expe- 
riences in man in the treatment of thyrotoxi- 
cosis show that the thyroid gland appears to 
be effected by about 2,000-3,000 reps. 
In a study of thyroid physiology, the dose 
should be kept as small as possible. Using doses 
of 10-100 microcuries which delivers about 
20 reps to the thyroid gland, numerous investi- 
gators have studied the uptake of carrier-free 
radioactive iodine by the thyroid gland and 
have drawn some rather interesting con- 
clusions. 
It has been found that the thyroids of 
normal or Euthyroid patients pick up 15-40 
percent of the administered dose; hypothyroid 
patients, less than 15% ; hyperthyroid patients 
greater than 40% (40-80 percent). This forms 
129 RADIOLOGICAL DEFENSE 
the basis for an important diagnostic test and 
one that can be used in difficult diagnostic 
problems—e.g. in self-induced thyrotoxicosis 
(Alimentary Thyrotoxicosis) due to exogenous 
administration of thyroid extract the clinical 
picture may be indistinguishable from spon- 
taneous thyrotoxicosis. The latter would show 
high (40-80 percent) uptake of I131 whereas 
former would reveal almost complete elimina- 
tion. Such tracer studies might also aid in the 
diagnosis of hypothyroidism or hyperthyroid- 
ism in infants where it would be extremely 
difficult to determine the basal metabolic rate 
by the routine method. 
At the present time, radioactive iodine has 
become one of the accepted forms of therapy 
in a diffuse toxic goiter. Toxic adenomas are 
to be eliminated from this form of therapy as 
approximately 5 percent of these prove to be 
cancer on histologic examination and thus 
these should be treated by operation. 
For diffuse toxic goiter three forms of 
therapy are available: (a) surgery; (b) med- 
ical management using goiterogenic drugs; 
(c) radioactive iodine. It is not our purpose 
here to evaluate all forms of therapy. How- 
ever, it would be proper to give some of the 
statistics based on results of treatment with 
I131. To date about one thousand cases have 
been reported. In 90 percent of the cases hyper- 
thyroidism was controlled in two to four 
months by one or two treatments (75 percent 
were cured with 1 treatment and about 75 per- 
cent of remainder were cured in two treat- 
ments). Others still remain under observation. 
The dose administered varies from 100-200 
microcuries/gm. of estimated gland weight. 
The type of response obtained compares very 
favorably with the type of response following 
an adequate thyroidectomy—with fall of 
B. M. R. and serum protein bound iodine to 
normal in one to four months. 
This discussion would not be complete with- 
out some mention of the complications to 
treatment. About 3 percent of patients develop 
transient hypothyroidism which does not re- 
quire any therapy. About 1 percent develop 
permanent hypothyroidism easily controlled 
with thyroid extract. The problem of long- 
term effects e.g. production of carcinoma 
due to the radiation has been proposed as a 
possible objection to this form of therapy. To 
date none has been seen but, of course, long- 
term follow-up is necessary; on the basis of 
X-ray experience, it is not expected that these 
will be found. It is to be noted that there is 
a zero mortality and no effect on the para- 
thyroid glands and vocal cords. These compli- 
cations compare very favorably with other 
forms of therapy. However, until long-term 
follow-up data becomes available, cases for 
such treatment must be selected carefully. 
Those most suitable would fall into the fol- 
lowing categories: 
(a) Recurrent hyperthyroidism after med- 
ical or surgical management. 
(b) Over age of 45. 
(c) Hyperthyroidism with complicating 
disease. 
Carcinoma of the thyroid gland is a rare 
disease. Primary carcinoma without evidence 
of metastases should be treated surgically. The 
following discussion will be confined to carci- 
noma of the thyroid gland with metastases. 
In the groups of cases reported in the litera- 
ture it has been found that most metastatic 
foci pick up I131 rather poorly—depending upon 
the type of carcinoma and its differentiation. 
Whereas we would expect to get 20-40 percent 
pick up if it acted like normal thyroid gland, 
the amount taken up is in the neighborhood 
of about 1 percent. 
To increase the pickup of I131 Seidlin and 
his co-workers studied a series of metastatic 
thyroid cancers in which they used thyroidec- 
tomy and thyrotropic stimulating hormone in 
an attempt to induce metastatic foci to accu- 
mulate I131. Their results indicate that whereas 
a tumor might not take up radioactive iodine 
initially, the stimulation by thyroidectomy and 
thyrotropc stimulating hormone may cause 
pickup. Furthermore, they noted a cyclical up- 
take so that if there is no success, a second 
trial might show a larger concentration. 
Using doses of 100 to 700 millicuries large 
amounts of radiation can be delivered to meta- 
static foci—as much as 500,000 reps—which 
130 RADIOLOGICAL DEFENSE 
could not be delivered with external radiation 
without burning the skin. 
These techniques can produce a dramatic 
improvement in the status of an occasional 
patient with this otherwise uniformly fatal 
disease. In the presence of carcinoma of the 
thyroid gland and metastases, there is nothing 
else to offer. Thus even an occasional remission 
is worth this effort. 
The question of danger to physicians, nurses 
and other attendants of the patients so treated 
has been raised. In cases of hyperthyroidism 
where 3 to 7 millicuries are used, the danger 
is minimal. There is no escape of beta rays; 
the intensity of gamma rays escaping from the 
patient is very low. At 2 meters gamma ray 
intensity is 0.6 X KH r/hr per millicurie. In, 
24 hours from 3 me. dose is .004 r at 2 meters 
so that as far as the treatment of hyper- 
thyroidism is concerned, there is no danger to 
any of the attendants. On the other hand, 
patients treated for metastatic carcinoma usu- 
ally receive large doses—hence their urine is 
highly radioactive and they themselves present 
a slight hazard so that usual radiological safety 
precautions should be taken. These patients 
should be kept isolated and their urine handled 
with 20 to 30 centimeter tongs. 
Another isotope which has received consid- 
erable attention is P32. This isotope of phos- 
phorus which emits only a beta ray of maxi- 
mum energy of 1.69 Mev, has been used in 
the form of sodium dihydrogen phosphate since 
1936 in the treatment of chronic leukemia and 
polycythemia vera. The use of P32 in these 
diseases is based upon its selective localization 
in the leukemic tissue and bone marrow and 
the resulting selective radiation. However, the 
degree of selective localization is not so great 
as would be desirable. Its main advantage over 
spray X-radiation is that it can be given more 
easily in centers equipped to do so and does 
not produce radiation sickness which spray 
radiation does. 
Patients with Polycythemia Vera or Ery- 
thremia have been found to receive marked 
benefit from treatment with P32. The obvious 
treatment in this disease, the cause of which is 
unknown, is either to remove the excess blood 
by repeated venesection or to control the for- 
mation of blood by either X-ray, P32 or chem- 
ical agents toxic to the bone marrow such as 
phenylhydrazine. Since the life of the red cells 
is long—about 120 days—the dosage schedule 
is 3-7 millicuries I.V. repeated three to four 
weeks for effect. It takes several weeks before 
one can notice an obvious trend in red cell 
formation. Using this or similar schedules, 
several hundred patients have been treated and 
the results have been reported in the literature 
—about 80% are relieved of their symptoms— 
about 85% obtain a satisfactory hematological 
remission which in the majority lasts from 
1/2 to 5 years and then may require further 
treatment. 
The complications to this form of therapy 
are overtreatment with the development of 
leukopenia, thrombocytopenia and anemia. 
Therefore, patients’ blood counts must be fol- 
lowed in first few weeks of treatment rather 
carefully. A higher incidence of acute leuke- 
mias has been reported in patients so treated; 
however, this is very difficult to evaluate as 
prior to P32 treatment 10% of patients with 
polycythemia vera died with blood picture of 
leukemia (acute and chronic). The cases re- 
ported after P32 treatment may thus represent 
the normal incidence in this disease. The exact 
significance must await further study. 
The demonstration that the uptake of P32 
by rapidly growing leukemic cells is consid- 
erably higher than the uptake of normal cells 
led to the investigation of the therapeutic pos- 
sibilities in leukemia. 
The initial dose is 1-3 millicuries (less than 
in polycythemia vera—as one does not want 
to affect the red cells) and thereafter 0.5 to 
2.0 me. biweekly for effect. The interval be- 
tween successive treatments is shorter than 
in polycythemia vera as the life of the white 
cells is about two to five days. Furthermore, 
the erythroid elements appear to be more 
radio-resistant in these conditions than in 
polycythemia vera. 
The results obtained for the treatment of 
chronic myelogenous and chronic lymphatic 
leukemias are very similar to the results of 
X-ray therapy, essentially palliative, not cura- 
131 RADIOLOGICAL DEFENSE 
tive but capable of producing remissions. Other 
blood dyscrasias have been studied but only 
occasional benefit has been reported. 
Since P32 emits only a beta ray with a range 
of penetration in tissue of several millimeters 
(half penetration approximately one milli- 
meter) it is being used at present experi- 
mentally in treating skin cancers. Theoret- 
ically, it would appear quite useful and supe- 
rior to X-ray or radium as it would avoid 
irradiation of the deeper uninvolved tissues. 
There are too few results to draw conclusions 
at present. 
The deposition of P32 in superficial tissues 
of patients suffering from melanoma and carci- 
noma has been investigated. Both the rate of 
uptake and elimination were different than 
normal skin—suggesting a more active metab- 
olism. After an injection of a small dose of 
P32, it was found that if the radioactivity 
over the surface of various types of breast 
tumors lying very close to the skin were meas- 
ured, the activity was 25 percent or more 
greater on the side of the malignant tumor 
than in a comparable normal; and slowly 
growing mucoid carcinomata. In benign condi- 
tions this difference was less than 25 percent. 
Accordingly, Low-Beer proposed this as a diag- 
nostic test in differential diagnosis of breast 
tumors. 
During the war the radioactive isotopes of 
the noble gases were employed to study the 
problems of decompression sickness. The in 
vivo technique was used in an attempt to 
evaluate the factors responsible for the 
“bends”. The results of these extensive and 
detailed studies indicate that the limiting fac- 
tor of inert gas exchange is the blood tissue 
perfusion rates and not the diffusion rates and 
capillary permeability to the labeled gas. 
Diiodofluorescein has recently been found to 
concentrate many-fold in brain tumors com- 
pared with normal brain tissue. When this 
compound is labeled with radioactive iodine, 
the tumor may then be tagged with radio- 
activity. If directional counters are used, 
tumors can then be localized with more cer- 
tainty. This method originally suggested by 
Moore and his associates is under investigation 
at present in many clinics—and appears prom- 
ising as another diagnostic aid to the neuro- 
surgeon. 
From this discussion it is obvious that the 
field is a very broad one although the practical 
applications are somewhat limited at present. 
It is also apparent that the use of these iso- 
topes requires a good deal of thought, careful 
preparation and evaluation as well as a thor- 
ough understanding of instrumentation. With 
these illustrations, it is hoped that you will 
each see further clinical applications of these 
new radioactive isotopes in your particular 
fields of endeavor. 
132 RADIOLOGICAL DEFENSE 
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☆ u. S. GOVERNMENT PRINTING OFFICE; 1950—844195 
137