A Monte Carlo approach to assessing 147Pm in the liver of the adult phantom.
A low-background phoswich detector is used to detect small amounts of 147Pm--a pure beta-emitting nuclide--present in the liver of an occupational worker. The assessment was based on the measurement of bremsstrahlung radiation produced by the beta particles in the tissue. Computer programs based on Monte Carlo techniques for photon transport have been developed to calculate the response of an external phoswich detector to 1) a 147Pm point source embedded in tissue-equivalent slabs of various thicknesses; and 2) various source distributions of 147Pm in the liver of an adult phantom. The goal is to theoretically calibrate the phoswich detector for each source distribution and to study the variation of maxima of the spectra with the depth of the source in the adult phantom liver and tissue-equivalent slabs. The initial bremsstrahlung photon distribution of 147Pm in water has been computed using Wyard's and Pratt's methods. These calculations have been compared with experimental measurements using Perspex acrylic sheet slabs. Good agreements have been noted when the initial bremsstrahlung spectrum is obtained by using Wyard's method. These results find applications in monitoring the liver burdens in occupational workers handling 147Pm-based radioluminous paints.
Health Physics Division, BARC Hospital, Bombay, India.
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Bhati
D000328:Adult; D006801:Humans; D008099:Liver / Q000737:chemistry*; D008961:Models, Structural; D009010:Monte Carlo Method; D016273:Occupational Exposure; D011399:Promethium / Q000032:analysis*; D011874:Radiometry / Q000295:instrumentation; D012984:Software
D011399:Promethium