Quantitative determination of uranium lung burden

This paper describes practical aspects of a whole-body counter calibration and quantitative determination of the uranium lung burden. Uranium-235 may be detected directly through observation of its gamma emission; however, U-238 does not provide observable gamma rays and must be monitored through the emissions of its daughter thorium-234. The counter system consisted of an 8 X 4-inch NaI(T1) crystal within a shielded room. System calibration was performed through use of an anthropomorphic chest phantom with provision for variable chest-wall thickness. Removable lung inserts contained calibrated standard activity distribution with blank inserts provided for background control. The primary objective was to define net error magnitude resulting from various sources of uncertainty, which included (10 the control population, (2) individual subject physique, (3) calibration factor, (4) count statistics, and (5) daily system response. The minimum detectable activities were determined for the three phantom configurations and various control population groups