Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline

レーザー駆動準単エネルギー陽子線照射装置を用いたヒトがん細胞における生物学的効果比の測定

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; 桐山 博光; 岡田 大; 金沢 修平; 下村 拓也; 中井 善基*; 田上 学*; 笹尾 文崇; Bolton, P.; 村上 昌雄*; 野村 大成*; 河西 俊一; 近藤 公伯

Yogo, Akifumi; Maeda, Takuya; Hori, Toshihiko; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Kiriyama, Hiromitsu; Okada, Hajime; Kanazawa, Shuhei; Shimomura, Takuya; Nakai, Yoshiki*; Tanoue, Manabu*; Sasao, Fumitaka; Bolton, P.; Murakami, Masao*; Nomura, Taisei*; 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 17.1 keV/m.