Project Title:
14,
Scope:
Exposure to External and Internal Radiation
;
In Vivo Measurement of Radionuclides in Man; Body Burden and
Kinetic Factors, Computer Applications
(Cont'd.)
RX-01-01-(b)
development of a method for absolute measurement of internally deposited
radionuclides using a whole-body counting technique.
In addition, the technique of in vivo neutron activation analysis was developed in order to measure
the rate of loss of Ca from the body in the numerous skeletal disorders under
ts
Pores
study. The paramount need for the in vivo measurement of absolute levels of
internally deposited radionuclides occurs in the diagnosis of cases of
Do
accidental intake of radionuclides.
2,
ar
ss
It is also essential in numerous clinical
studies, The main effort in the whole-body counting program has been directed
toward minimizing the variation in counting efficiency due to spatial distribution of internally deposited radionuclides and changes in their energy absorption as a function of body weight and habitus.
A number of clinical studies which previously had not been amenable to
investigation because of the necessity of absolute measurements or spatial
localization of radionuclides have been conducted, These studies include:
measurement of absolute levels of whole-body potassium and determination
of its spatial distribution in the body; measurement of lean-body mass in
grossly obese children, based on measurement of K-40; measurement of lean-body
mass in growth-deficient children undergoing therapy with growth hormone;
measurement of levels of Cs-137 and K-40 in BNL staff members as a function of
time and sex; and calibration procedures for absolute measurements and computer
C
programs associated with such measurements,
Anti-coincidence circuitry is
available in the whole-body counter and its use is being explored with
administered positron emitters which would improve the spatial localization
capability of the counting system.
Besides determining absolute levels of calcium in the body,
levels of
sodium, chlorine and phosphorus have been measured by neutron activation with
the aim of developing diagnostic techniques as well as obtaining basic
information on disease processes,
Of the ten most abundant elements in the
body, six have been measured and the possibilities of measuring hydrogen,
carbon and oxygen are explored.
Effort has been made to improve the accuracy of the in vivo neutron
activation technique by improving the uniformity of thermal neutron irradiatio
flux density in the irradiated subjects. Activation is now performed with a
unique Pu-238, Be neutron irradiation facility rather than with the 14 MeV
neutron generator originally employed.
The reduced dose to the patient,
tog
er with the inherent simplicity of operation of the PuBe neutron source,
ma
in
this technique the most desirable for total body neutron activation
{cal diagnosis and research.
(Cohn)
‘Data published by Oftedal indicate that for some end points very low
doses of radiation may be more effective than would be predicted by extrapolation from high doses.
It is proposed that experiments be conducted under
conditions of less than natural background in order to define the response
(See Continuation Sheet)
PE Udi-th
RX-14