is human
for
APPENDIX D
RADIATION DETECTION EQUIPMENT FOR JN VIVO MEASUREMENT OF PLUTONIUM
ots
Bt ae EI ie
rhe three following types of radiation detect-
thickness.
Each detector functions as an anti-
iny equipment are currently used to estimate the
coincidence system, resulting in a suppression of
quantity or plutonium in the body:
background caused by Compton scatter from higher-
(1) proportional
counters; (2) thin sodium iodide crystals and dual
iodide;
god{um
and
(3)
cesium iodide crystals.
Al-
energy radiations originating from within the body
and in the local environment,
The MDA at the 95 per-
thoush these instruments are often called ‘lung”
cent confidence level for this system averages about
counters,
7 nci 239 bu for a 30-minute counting period.
they cannot distinguish between radio-
active materials in the pulmonary and lymphatic tisgue.
=n an effort to localize plutonium, partic-
ularly
in
the hilar lymph nodes,
probe is being developed.”
1
an intraesophogeal
All of these instruments
Measure
Sim-
ilar MDA values have been obtained at other facilities (for example, at the Lawrence Livermore
Laboratory).
To achieve MDA's in the range of
roughly one-third the commonly accepted 16-nCi
low-energy X-rays or gamma rays from pluto.
'
'
243
nium or contaminant radionuclides such as
Am
241
formed by decay of
Pu.
The radiation energies
occupational lung burden, one must carefully esti-
of
Measurements must be made also in "“low-background”’
greatest
interest are the
17- to 20-Kev uranium
L x-rays From 24 tou and the 60-Kev gamma ray from
241
24]
.
Am.
Low-energy x-rays also emitted by
Am
mate an individual's chest thickness.
Ultrasonic
techniques are used for this purpose at LASL.
counting chambers constructed of massive iron
shielding.
must be differentiated from those given off by
plutonium,
The system used at the Los Alamos Scientific
Laboratory to measure im vivo deposits of plutonium
' in our subjects is comprised of two combined crys-
REFERENCE
1.
K. L. Swinth, J. F. Park, and P. J. Moldofsky,
“Counting Plutonium in the Tracheobronchial
Lymph Nodes," Health Phys. 22, 899 (1972).
tals, Nal backed by a 50-mm CsI crystal, each of
which ts about 125 mm in diameter and 3 mm in
24 TAemiamE aE FE
ita exist
ngewe,
or establish-
EE: 1353(1030)
31