Absorbed dose estimates at the cellular level for 131I

Microdosimetric calculations of I-131 have been evaluated for a single cell and for cell clusters. A VsBasic program has been used to calculate stopping power, linear 3 energy transfer, range values and deposited energies per decay for beta particles, Auger and conversion electrons of I-131. The chemical composition of the cell has been taken into account in this model; results were compared with water medium. Besides, total absorbed doses have been calculated for the radionuclides distributed randomly within the cell and clusters. Cross-fire irradiation has been considered for clusters of cells. In this case, absorbed doses per cell within a cluster were found to be significantly higher than absorbed doses per single cell, depending on the cluster size. Results showed that I-131, is a promising radionuclide for therapy of tumors from millimeter to centimeter dimensions. (c) 2004 Published by Elsevier Ltd.