@misc{oai:repo.qst.go.jp:00059919,
 author = {Furusawa, Yoshiya and Aoki, Mizuho and Shino, Yayoi and Lee, Ryonfa and Zhou, Guangming and Takai, Nobuhiko and Monobe, Manami and Fukawa, Takeshi and Miyato, Yasuyuki and Kagiya, Gou and 古澤 佳也 and 青木 瑞穂 and 志野 弥生 and 周 光明 and 高井 伸彦 and 物部 真奈美 and 扶川 武志 and 宮戸 靖幸 and 鍵谷 豪},
 month = {Aug},
 note = {INTRODUCTION
HIMAC (Heavy-ion Medical Accelerator in Chiba) has constructed in 1993, and clinical trials has started in 1994 together with academic research activities, including physics, engineering, and biology. Pre-clinical radiobiological studies have performed to estimate clinical RBE for hadron beams. Following the HIMAC, several hadron therapy facilities (HIBMC, Hyogo; NCCHE, Kashiwa; WERC, Tsuruga; PMRC, Tsukuba; SCC, Shizuoka) have started the therapy in Japan. We have evaluated the RBE of each hadron beams for all the facilities with the same biological system and technical staffs as well as at HIMAC. 
METHODS
Human salivary gland tumor cells (HSG) were used for the studies. All experiments were performed with single-dose exposures for both proton beams and linac X-rays at each facilities. All 60 mm SOBP beams were generated from 180-190 MeV proton beam, and the energy of high-energy linac X-rays were 4-6 MeV, but it depends on the facilities. Samples were placed at the plateau position or the entrance, middle, or proximal positions of SOBP beam or at the 50 mm depth position of the linac beam. The D10 values from survival curves by the colony formation assay were obtained. The RBE values of proton beams were calculated to X-ray data. 
RESULTS
The average RBE at the middle of SOBP beam from all facilities was 1.030+/-0.017 (mean +/- SD). Flatness of the RBE in the SOBP were slightly disposed to increase with the depth. The values were slightly lower at the entrance, and little bit higher at the distal than that at the middle position. 
DISCUSSION
X-ray data showed very good agreement and the deviations were less than 2 % among the facilities. The RBE values also showed good agreement among the facilities with 2 % or less standard deviation. Some difficulties were found in the irradiation systems, i.e. the dose determination and/or geometrical sample setting methods are different among the facilities. This may makes difficult exact comparative judgments of the radiobiological data. During the radiobiological experiments process, several problems were found and have solved. In this point of view, preclinical experiments were important as a simulation of patient treatments. 
CONCLUSION
The RBE values for all proton therapy facilities in Japan were similar (1.02) with small deviation. The depth-dose distribution of all the SOBP beams has designed very well, and showed good uniformities of biological dose at all facilities. Physical dosimetry system should be unify for all the facilities to compare the results., WC2003},
 title = {Intercomparison of Radiobiological RBE Among Japanese Proton Therapy Facilities},
 year = {2003}
}