Radiobiology with laser-accelerated quasi-monoenergetic proton beams

準単エネルギーレーザー駆動陽子線による放射線生物研究

余語 覚文; 前田 拓也*; 堀 利彦*; 榊 泰直; 小倉 浩一; 西内 満美子; 匂坂 明人; Bolton, P.; 村上 昌雄*; 河西 俊一*; 近藤 公伯

Yogo, Akifumi; Maeda, Takuya*; Hori, Toshihiko*; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Bolton, P.; Murakami, Masao*; Kawanishi, Shunichi*; Kondo, Kiminori

Human cancer cells are irradiated by laser-driven quasi-monoenergetic protons. Laser pulse intensities at the W/cm level provide the source and acceleration field for protons that are subsequently transported by four energy-selective dipole magnets. The transport line delivers 2.25 MeV protons with an energy spread of 0.66 MeV and a bunch duration of 20 ns. The survival fraction of in-vitro cells from a human salivary gland tumor is measured with a colony formation assay following proton irradiation at dose levels up to 8 Gy, for which the single bunch does rate is Gy/s and the effective dose rate is 0.2 Gy/s for 1-Hz repetition of irradiation. Relative biological effectiveness at the 10% survival fraction is measured to be using protons with a linear energy transfer of keV/m.