Monte Carlo Simulation Study On The Enhanced Biological Effects Of Radioactive ~9C Beam

Compared to conventional X-ray radiotherapy, heavy ion therapy is mainly characterized by an increased relative biological effect(RBE) within the Bragg peak and an optimized dose distribution within the penetrating pass, implying physical and biological advantage for medical use. Hence, heavy ion therapy has achieved a great success against cancer. To date, heavy ion therapy has become an increasingly important option for cancer treatment. Even so, studies on exploring optimal beam species have become an active realm of ion beam therapy.In 2002, the idea of using radioactive beam, 9C for example, was proposed by Qiang Li et al. Subsequent experiments showed that the RBE values for the 9C beam were higher almost 2 times than those for the 12 C beam around the Bragg peak.To verify the nature of the RBE enhancement effect of 9C beam, a simulation describes the biological process at the Bragg peak of 9C beam was designed and conducted. First of all, a simplified cell model was established so as to form a tumor tissue within the GATE simulation toolkit based on Geant4, and then the tumor virtually irradiated with comparable 9C and 12 C beam. Subsequently, the decay and nuclear-hit processes were simulated, based on data derived from GATE, using a local effect model based re-implementation so as to deduce cell survival fractions. Finally, the biological effects of X-ray, 9C and 12 C beam were compared and the nature of RBE enhancement of 9C beam was substantiated.To further conduct our study, next step of research has been started, which mainly explore the interaction of solid tumor tissue and spread-out-Bragg-peak of 9C. To date, the database supporting the algorithm is under development.Collectively, the increased local doses and clustered damages derived from the decayed secondary particles emitted from 9C particle led to the RBE enhancement effect of 9C beam. Compared to traditional 12 C beam, 9C beam delivers less dose within healthy tissue while inducing similar biological effect around the Bragg peak, meaning that 9C beam could reduce the toxicity of radiotherapy.