Evaluation of Electron Specific Absorbed Fractions in Organs of Digimouse Voxel Phantom Using Monte Carlo Simulation Code FLUKA

Background: For preclinical evaluations of radiopharmaceuticals, most studies are carried out on mice. Values of electron specific absorbed fractions (SAF) have had vital role in the assessment of absorbed dose. In past studies, electron specific absorbed fractions were given for limited source target pairs using older reports of human organ compositions.Objective: Electron specific absorbed fraction values for monoenergetic electrons of energies 15, 50, 100, 500, 1000 and 4000 keV were evaluated for the Digimouse voxel phantom incorporated in Monte Carlo code FLUKA. The organ sources considered in this study were lungs, skeleton, heart, bladder, testis, stomach, spleen, pancreas, liver, kidney, adrenal, eye and brain. The considered target organs were lungs, skeleton, heart, bladder, testis, stomach, spleen, pancreas, liver, kidney, adrenal and brain. Eye and brain were considered as target organs only for eye and brain as source organs. From the latest report (International Commission on Radiological Protection ICRP) publication number 110, organ compositions and densities were adopted.Results: The electron specific absorbed fraction values for self-irradiation decreases with increasing electron energy. The electron specific absorbed fraction values for cross-irradiation are also found to be dependent on the electron energy and the geometries of source and target. Organ masses and electron specific absorbed fraction values are presented in tabular form. Conclusion: The results of this study will be useful in evaluating the absorbed dose to various organs of mice similar in size to the present study.