title: LET and ion-species dependence for cell killing and mutation induction in normal human fibroblasts.
abstract: We have been studying LET and ion species dependence of RBE values in cell killing and mutation induction. Normal human skin fibroblasts were irradiated with heavy-ion beams such as carbon (290 Mev/u and 135 Mev/u), neon (230 Mev/u and 400 Mev/u), silicon (490 Mev/u) and iron (500 Mev/u) ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS). Cell killing effect was detected as reproductive cell death using a colony formation assay. Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies. The RBE-LET curves of cell killing and mutation induction were different each ion beam. So, we plotted RBE for cell killing and mutation induction as function of Z*2/beta2 instead of LET. RBE-Z*2/beta2 curves of cell killing indicated that the discrepancy of RBE-LET curves was reconciled each ion species. But RBE-Z*2/beta2 curves of mutation induction didn't corresponded between carbon- and silicon-ion beams. These results suggested that different biological endpoints may be suitable for different physical parameter, which represent the track structure of energy deposition of ion beams.
authors.affiliation: International Space Radiation Laboratory, National Institute Radiological Science.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Tsuruoka
authors.forename: Masao
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Fujitaka
mesh_terms: D002244:Carbon; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects; D020450:Heavy Ions; D006801:Humans; D007501:Iron; D018499:Linear Energy Transfer; D016296:Mutagenesis; D009356:Neon; D010315:Particle Accelerators; D012062:Relative Biological Effectiveness; D012825:Silicon
chemical_list: D009356:Neon; D002244:Carbon; D007501:Iron; D012825:Silicon