PHOTON ABSORBED FRACTIONS FOR CYLINDRICAL GEOMETRY - HOMOGENEOUS NONRADIOACTIVE CYLINDER CONTAINING A HOMOGENEOUS CYLINDRICAL DISTRIBUTION OF ACTIVITY

The purpose of this study was to calculate photon absorbed fractions i n tissue surrounding a radioactive source where both the source and th e surrounding tissue are assumed to have cylindrical geometry. Specifi cally, we treated two cases: the case of a cylindrical source of homog eneous activity placed in air, and second, the case of a cylindrical s ource of homogeneous activity placed in a cylindrical nonradioactive a bsorbing material. In this study we offer an analytical solution to th ese problems followed by numerical integration. The computer program a llowed for very general calculations, e.g., different tissues, differe nt geometrical setups. Tables of absorbed fractions have been develope d for commonly used radionuclide energies and tissue-equivalent materi al. A comparison between our results and the results of other related studies showed the advantages and limitations of this approach. (C) 19 96 American Association of Physicists ts in Medicine.