Abstract
Facilities for particle radiotherapy are increasing in number these days. Using mouse gut crypt survivals as an endpoint, we have investigated and here report the biological effectiveness of proton beams in domestic facilities. Also, we compared carbon-ion beams at Darmshtad (Germany) GSI and at Chiba HIMAC. Therapy facility and the irradiation condition: Wakasa wan energy research center 180MeV/u proton-beam 6cm-SOBP entrance plateau or middle position of SOBP (reference: Fukui medical university Linac4MeV/u). Shizuoka cancer center: 190MeV/u proton-beam 6cm-SOBP entrance plateau or middle position of SOBP (reference : Linac Shizuoka cancer center 6MeV/u). GSI: 290MeV/u carbon-beam 6cm-SOBP proximal, middle, distal HIMAC: 290MeV/u carbon-beam 6cm-SOBP proximal, middle, distal We obtained 3 isoeffect doses (D0, D30 and D10) from a crypt survival curve, and calculated a representative RBE value by averaging 3 RBE values obtained for the isoeffect doses. RBE of the proton beam in the Wakasa wan energy research center was 0.98 at the entrance plateau, and at the middle position of SOBP was 1.13. RBE of the proton beam in Shizuoka cancer center was 0.99 at the entrance plateau, and at the middle position of SOBP was 1.05. Commonly observed was that RBE at the middle position of SOBP was slightly larger than RBE in the entrance plateau. When we compared isoeffect doses for the carbon beam between GSI and HIMAC, biological effectiveness of HIMAC beams stronger than that of GSI by 5 %.
