Dr. Robert A.
Conard
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April 18, 1977
Brookhaven National Laboratory
“Page 27
no abnormal concentrations of high energy emitting radionuclides are present in the body of either individual,
The
K-40 photopeak is prominent for each Figure.
The detection of low energy photon-emitting radionuclides
in vivo is determined using two or three thin (15 cm. dian.)
dual-crystal scintillation detectors (NaI-CsI(Tl) positioned
about the head or.over the thorax of the subject in a manner so
as to achieve a maximum counting sensitivity. The measurement
of low energy phatons from the head are’ representative of
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“radionuclides which-are deposited in the skeleton,
Counting.
over the thorax is indicative of radionuclide: deposition in
the lung as well as soluble radionuclides which have migrated
to the skeleton and are present on thoracic skeletal surfaces.
Our head counting geometry has been described in detail in
various publications and the thorax counting geometry is
Standard in many laboratories across the country.
Figures 3
and 4 give the results of individual one hour in vivo
-counting sessions in the head-geometry for Drs.
respectively.
By comparison of the quantitative counting data
in the plutonium and americium energy regions with our control
subject population, it has been determined that if either
individual has any skull contamination by these nuclides,
it is less than or equal to .02 nCi of Am-241 or~5.0 nCi
Pu-239, the detection limits of our counting system for this
geometry.
ws
“the detection of plutonium or americium in the lung is
accomplished in the third in vivo counting procedure by
positioning ‘two detectors over the chest.
Contribution to the
total thorax count from activity deposited on rib cage
structures is calculated from information of the skeletal
concentration as measured from the head counting geometry.
Thus, the actual amount of activity contained in the skeleton
and lung from internally deposited radionuclides can be
'
Calculated from the measurement of the head (skull) and thorax
{lung) using several of these dual crystal detectors.
Figures 5
and 6 are the gross spectra resulting from 30 minute counts
with two detectors positioned above the thorax of Drs.
respectively. Again, no activity attributable to
plutonium or americium nuclides above our limit of detection
(i.e. 0.15 nCi Am-241; 25 nCi Pu-239
) was noted.
As I indicated, we have collected 24-hour urine samples
from each subject in addition to a partial day's sample collected
during their visit to the Institute for whole body counting.
These urine samples will be prepared according to our standard
bioassay radiochemical procedures which require ion exchange
separation of the transuranics from the sample followed by
alpha spectrometry using low level Sibi surface-barrier detection
systems.: As soon as this information is available, I will
MM 5011755
PRIVROYACTMATERIAL REMOVED