se
38
magnetic tape of a 704 computer. The task of
“spectral stripping” was carried out on the computer with a FORTRAN program. In this operation
the spectrum ofeach individualisotope is removed
from the total spectrum obtained for the subject,
which represents the combination of the contributions from ail the isotopes deposited in that subject.
Spectra for each of the individual isotopes quantitated in this study were obtained with the use of
an Alderson phantom (REMCAL). Solutions of
known concentration of each radionuclide were
placed in the phantom to approximatetheeffects
of tissue absorption and scatter. The spectrum of
the phantom for each of the isotopes was obtained
under conditions of counting geometry identical
00.000 pr mn
GAMMA RAY SPECTRA OF PLASTIC Mana
FE Cs"? (0942 pe, 0.66 Mev!
5
J
10,000 ~
COUNTS 30 MINUTES /20 kev CHANNEL
E
\
2n** (0.463 yc, 112 Mev)
S
:
54
4
4
|
‘000
SPECTRUM
|
|
~
L
100
NET Zn*3ec3""
|
:
EF
|
4
K id gk"146 Mev)
'
,
4
1
_e NET TOTAL,
maocy |
|
SPECTRUM |
NET C37 “|
5
|
7
SPECTRUM
i.
[-
with that used in counting the subjects. By this
technique it was possible to simulate quite closely
with the phantom the multicomponentspectra of
=
5
the Marshallese. A representative Marshallese
.-
IK
4
20
44
68
92
He
ENERGY
140
164
188
Mev
Figure 35. Gammaspectrum otthe calibration phantom
containing Cs'*. Zn"’, and Kin the approximate range
found in Marshallese subjects. The dotted lines indicate
the results of spectral stripping of the higher energy
photopeaks.
spectrum obtained by adding K, Cs'**, and Zn"
at average levels (as determined in the medical
study of 1959) to the phantom is shown in Figure
55. The K, Cs'*", and Zn"? were distributed homogeneously throughout the phantom. while Co"
was placedin theliver only.
Analyses of the complex spectra were performed
by subtracting the calibrated pulse-height spec-
trum for each gamma emitter to be quantified.
Although these spectra are obtained ideally trom
a subject of identical build, an approximationis
i
ie
ll
a
o
TT Lay “ETERNAL
B- US MALE, MEDICAL TEAM
AGE 41) YRS-WT=: 77 Kg
Zn*(98 myc)
CPA IO 2 myc)
18
de LL
5878
O88
ie
ENERGY (Mev)
~~
t
‘
/
i
|
I
k
{
co
fem
38
“>
wo
sat
_
K(AtI39.4g 682140.3g)
o
TUTTtrity
5
hide
die
de
COUNTS /30 MINUTES/20 kev CHANNEL
+A
a
38
158
Lititil
A-MARSHALLESE MALE
AGE 45 YRS-WT=70 Kg
Po tea th
os17 ye)
Yaduiu
obtained with the use of the plastic phantom.
Figure 56. Spectrum of typical Marshallese adult male
compared with that of memberof the U.S, medical team.
Computation was carried out by an IBM-704 computer. Starting with the highest energy photopeak.
that of K'° (after correction for background and
normalization of the K*° photopeak to that of the
subject), the computer performs a channel-bychannel subtraction of the normalized K’*”spectrum. In a similar manner, the normalized spectra
for Zn**, Co®, and Cs'** were subtracted from the
total spectrum (see Figure 55).
Individual 24-hr urine specimenswere collected
and one pooled urine sample of 20 liters. The
radiochemical procedure for the Sr*° analysis has
been described previously.’
RESULTS
A spectrum for an average Marshallese adult
male, obtained in the 1961 study, is shown in
Figure 56, with the spectrum of a memberofthe
U.S. medical team of about the same body weight