Abstract
Recent studies have showed that the sharp of the LET-RBE curves of biological effects was different, when using different ion species even if similar LET values. In this study, we investigated LET- and ion-species dependence on mutation induction and deletion spectrum of exons in hprt locus. Normal human skin fibroblasts were irradiated with carbon-, neon-, silicon- and iron- ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS). Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies, and deletion spectrum of exons was analyzed by multiplex PCR. The LET-RBE curves of mutation induction for carbon- and neon-ion beams showed a peak around 75keV/micrometer and 155keV/micrometer, respectively. On the other hand, there observed no clear peak for silicon-ion beams. The deletion spectrum of exons was different in induced mutants among different ion species. These results suggested that quantitative and qualitative difference in mutation occurred when using different ion species even if similar LET values.
