Calculating concentration of inhaled radiolabeled particles from external gamma counting: external counting efficiency and attenuation coefficient of thorax.
Langenback EG; Foster WM; Bergofsky EH
J Toxicol Environ Health 1989 May; 27(1):139-152
A direct method was used to determine the amount and distribution of a radionuclide in the lungs of five Q-fever negative, mixed breed female sheep between 2 and 4 years of age. Using a series of noninvasive gamma scintillation camera images and postmortem dissections, the exact amount of radionuclide in the form of insoluble carbonized polystyrene particles tagged with cobalt-57 (13981505) was determined. The lungs of the sheep were inflated with one breath, 1 liter, of aerosol each minute for 60 to 90 minutes. Each of these breaths was held for 6 seconds. Measurements made on different sheep at various radionuclide concentrations in the lung have yielded a curve converting counts per minute acquired on the gamma scintillation camera to actual microcuries or particles in the lung of the intact sheep. This relationship permitted the calculation of the external radionuclide counting efficiency and the attenuation of the emitted gamma rays by the chest wall. This has made it possible to standardize a number of variable parameters and quantitate radionuclide or particle dose in the lungs, allowing an accurate evaluation of uptake and change of radionuclides. The results of the study suggest that the data may be extrapolated to humans, but additional experimental support would be needed.
NIOSH Publication; NIOSH Grant; Pulmonary system disorders; Radionuclides; Analytical instruments; Animal studies; Pulmonary system; Tissue distribution; Inhalation studies; Lung tissue
Medicine Suny at Stony Brook Hsc, T-17, Room 040, Stony Brook, NY 11794
Journal of Toxicology and Environmental Health
State University New York Stony Brook, Stony Brook, New York