Evaluation of specific absorbed fractions from internal photon sources in the ICRP Reference Male Phantom

In order to estimate the dose caused by internal radiation, it is necessary to know the specific absorbed fraction (SAF) values; through this work these values have been calculated using the Adult Male Reference Computational Phantom (RCP-AM) from the Publication 110 of the International Commission Radiologic Protection and the Monte Carlo transport code MCNPX. These values were calculated for a combination of 980 pairs of source and target organs, for a total of 12 energies. The results were validated and compared with the results reported by other authors: Hadid et al. (RCP-AM), Petoussi-Henss and Zankl (Golem) and the Oak Ridge National Laboratory (ORNL) stylised model reported by Cristy and Eckerman. Mostly, the SAF values calculated with the RCP-AM do not present significant differences in relation to its previous model Golem. When comparing the SAF values of RCP-AM with that of the ORNL stylised model, huge differences were found. These differences can be explained by the shape of the organs and their relative positions, which are more realistic in the voxelised phantoms.