Intercomparison of S-Factor values calculated in Zubal voxelized phantom for eleven radionuclides commonly used in targeted prostate cancer therapy

In this study we aimed at comparing various radionuclides ordinarily used in targeted prostate cancer therapy, thereby evaluating S-Factor parameter in the prostate organs as well as in its surrounding healthy tissues, namely the urinary bladder and rectum. InterDosi code version 1.1 was used to estimate S-Factor values in Zubal voxelized phantom for 11 radionuclides, namely 225 Ac, 21 At, 67 Cu, 125 I, 131 I, 212 Pb, 177 Lu, 223 Ra, 161 Tb, 227 Th and 90 Y. The prostate organ was considered the source of different ionizing radiation emitted by the radionuclides cited above. The results showed that among all studied alpha-emitting radionuclides, 225 Ac, 223 Ra and 227 Th provide equidistantly the highest self-irradiation S-Factors whereas, 211 At provides the lowest cross-irradiation S-Factors. On the other hand, considering only beta-emitting radionuclides, it is shown that 177 Lu and 90 Y induce respectively lowest and highest cross-absorption S-Factors on the surrounding healthy organs. We conclude that 177 Lu and 211 At are more adequate for prostate radionuclide therapy because they can relatively prevent surrounding organs from radiation toxicity and at the same time provide sufficient dose to treat the prostate tumor.