DISTRIBUTION OF DOSE IN THE BODY FROM A SOURCE OF GAMMA RAYS DISTRIBUTED UNIFORMLY IN AN ORGAN.

When a gamma emitter is present in an organ of the body, only a fraction of the emitted gamma energy is absorbed in that organ. Many evaluations of the absorbed fraction have been published, mostly for highly idealized and perhaps oversimplified cases. The use of an effective radius and a spherical geometry is one instance of such drastic simplification. Although an exact theory of gamma photon interaction with matter is known in detail, application of this theory is usually difficult since an enormous amount of mathematical computation is involved. However, by use of a high-speed digital computer these calculations become feasible. A Monte-Carlo-type calculation has been used to estimate the dose in 22 organs and 100 subregions of an adult human phantom for four initial gamma energies. This report is divided into three sections; in section one is a description of the phantom, in section two are some details of the Monte Carlo method used, and in section three are the dose estimates from a gamma source distributed uniformly in (1) the total body and (2) the skeleton.