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 of each individual isotope is removed
fromthe total spectrum obtained for the subject.
which represents the combination of the contribu-
rb lilt
100,500 &
“GAMMA RAY SPECTRA OF PLASTIC MANcs'7? 6542 uc, 0.66 Mev:
'
CUUNTS #30 MINUTES / 20 Kev CHANNEL
tions from all the isotopes deposited in that subject.
Spectra for each ofthe individual isotopes quan-
titated in this study were obtatned 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
NET ZnB ecg
|
SPECTRUM
|
«aC aK” 86 Mav
the phantom for each of the isotopes was obtained
1
_
|
|
s0cyY
|
oe
NET
—
with that used in counting the subjects. Bythis
technique it was possible to simulate quite closelv
with the phantom the multicomponentspectra of
SPECTRUM
o5 77
SPECTRUM "|
—.
under conditions of counting geometry identical
-NET TOTAL
1
“
|
ne!
|
the Marshallese. A representative Marshallese
spectrum obtained by adding K, Cs'"*, and Zn"'
at average levels (as determined in the medical
iC
20
— +
44
68
32
116
ENERGY
ido
studyof 1959) to the phantom is shownin Figure
—
68401838
35. The K. Cs'**, and Zn’ were distributed homo-
Mev
Figure 53, Gammaspectrum otthe calibration phantom
containing Cs'**, Zn“, and K"" in the approximate range
found in Marshallese subjects. The dotted lines indicate
the results of spectral stripning of the higher energy
photopeaks.
=
2
A-MARSHALLESE
MALE
B-uS MALE, MEDICAL TEAM
AGE 41 YRS -wT: 77Kq
*
CA 10.2 muc)
4
are
3
— \ Cs” (25 muc)
_ ss .
A‘
‘sa
Tome
\
_
~
_
~
K(471394g 8=140.3q)
/ {
\
,
=
l
2n°*(98 myc}
+
| 8
%
r
1
“ot
Lt
‘
i
oN
\
hr
if
‘
pus
ay
/
7
-
/
=
=
=
_
4
:
3
a
—
7
by subtracting the calibrated pulse-height spectrum for each gamma emitter to be quantified.
Although these spectra are obtained ideally from
a subject of identical build, an approximation ts
obtained with the use of the plastic phantom.
Computation was carried out by an [BM-704 computer. Starting with the highest energy photopeak,
that of K*” (after correction for background and
normalization of the K' photopeakto that ofthe
subject), the computer performs a channel-by-
channel 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 53).
Individual 24-hr urine specimens werecollected
and one pooled urine sample of 20 liters. The
radiochemical procedurefor the Sr’” analysis has
been described previously.'
J
-
COUNTS / 40 MINGTES/20 kev CHANNEL
AGE 45 YRS-wWT=70 Kg
bila
Ie,
5871 iP acl
geneously throughout the phantom, while Co”®
was placed in theliver only.
Analyses of the complex spectra were performed
RESULTS
10.
18
38
58
73
98
18
ENERGY (Mev)
138
-
Figure 56. Spectrum oftypical Marshallese adult male
compared with that of memberofthe U.S. medical team.
A spectrum for an average Marshallese adult
male, obtained in the 1961 study, is shown in
Figure 56, with the spectrum of a member of the
U.S. medical team of about the same body weight