Survival Responses and Potentially Lethal Damage Repair of Normal 10T1/2 and Its Transformed TCL 15 Cells After Irradiation with 43 Mev Proton Produced Neutrons

Abstract

Normal 10T1/2 fibroblasts and their transformed counterparts (TCL 15) were used in order to evaluate the RBE, TGF and PLD repair for a therapeutic fast neutron beam (43 MeV proton←Be). For plateau-phase culture, the RBE of 10T1/2 cells were 2.0 and 1.7 at 10 and 1% survival levels respectively and 1.3 from D₀. The corresponding RBE values of TCL 15 cells were 2.1, 1.8 and 1.5, and thus the TGF values were 1.05 and 1.1 respectively at 10% and 1% survival levels and 1.8 from D₀. For log-phase culture, the survival responses of 10T1/2 and TCL 15 cells to ⁶⁰Co gamma-rays or neutrons were not significantly different (the RBE at 10% was 2), and thus the TGF value was unity. For neutrons, as a rule no PLD repair has been reported in vitro and in vivo in previous studies. However, in the present study PLD repair occurred in plateau 10T1/2 and TCL 15 cells irradiated with neutrons.