2011 Volume 60 Issue 12 Pages 505-512
Electron absorbed fractions(AFs) and S values were evaluated in a voxel-based mouse phantom for preclinical evaluations of radiopharmaceuticals. The sources were considered monoenergetic in the electron energy range 10keV to 4MeV, and to be distributed uniformly with isotropic emission in the organs. The radiation transport was simulated using a Monte Carlo method. It was confirmed that electron AFs were dependent on the volume, density, and geometry of the source and target organs. The electron AFs for organ self-irradiation (i.e., the target is the source) decreased with increasing electron energy. The results from this study were consistent with other published data and indicated that the electron AF for self-irradiation was not always 1.0 and strongly depended on electron energy. The electron AFs for organ cross-fire (i.e., the target is not the source) were dependent on the electron energy emitted by the source and the geometries of source and target. Additionally, S values in the major organs of the voxel-based mouse phantom were tabulated for 131I, 153Sm, 188Re, and 90Y using the photon and electron AFs. The results of this study will be useful in determining organ doses in mice for radiopharmaceutical development.