Evaluation of specific absorbed fractions in voxel phantoms using Monte Carlo simulation

Kinase, Sakae   ; Zankl, M.*; Kuwabara, Jun ; Sato, Kaoru   ; Noguchi, Hiroshi; Funabiki, Jun*; Saito, Kimiaki  

There exists a need to calculate specific absorbed fractions (SAFs) in voxel phantoms for internal dosimetry. For the purpose, an EGS4 user code for calculating SAFs using voxel phantoms was developed on the basis of the EGS4 user code (UCPIXEL). In the developed code, the transport of photons, electrons and positrons in voxel phantoms can be simulated, particularly the transport simulations of secondary electrons in voxel phantoms can be made. The evaluated SAFs for the GSF "Child" voxel phantom using the developed code were found to be in good agreement with the GSF evaluated data. In addition, SAFs in voxel phantoms developed at JAERI were evaluated using the developed code and were compared with several published data. It was found that SAFs depend on the organ masses and would be affected by differences in the structure of the human body.