Dosimetric analysis for the selection of radionuclides in bone pain palliation targeted therapy: A Monte Carlo simulation

Introduction:The use of beta emitters is one of the effective methods for palliation of bone metastasis. The risk of normal tissue toxicity should be evaluated in the bone pain palliation treatment. Methods: In this study, the Monte Carlo simulation code MCNPX was used for simulation a bone phantom model consisted of bone marrow, bone and soft tissue. Specific absorbed fractions were calculated for monoenergetic electrons, photons and eight betaemitters: 32P, 89Sr, 90Y, 153Sm, 166Ho, 177Lu, 186Re and 188Re. Beta and gamma S-factor, absorbed dose and cumulative dose of mentioned radionuclides were obtained to the selection of radionuclides with optimal radiation characteristics. Results: The results show 177Lu gives a higher local dose to source organ. 177Lu has fewer side effects on critical organ including bone marrow in comparison with other radionuclides such as 89Sr, 32P and 90Y. Cumulative dose versus time shows after a long time, long half-life radionuclides delivering a higher dose in comparison with the short-half radionuclides. Conclusion: According to the results, low energy β-emitters177Lu, 153Sm and 186Re can be used for bone pain palliation especially in vertebra. Different combination of these radionuclides can be used to improving therapeutic effects for tumors with different size.