@misc{oai:repo.qst.go.jp:00070164,
 author = {Matsumoto, Yoshitaka and Inaniwa, Taku and Wada, Mami and Kase, Yuki and Satou, Shinji and Furukawa, Takuji and Takeshita, Eri and Himukai, Takeshi and Noda, Kouji and Matsufuji, Naruhiro and Furusawa, Yoshiya and et.al and 松本 孔貴 and 稲庭 拓 and 和田 麻美 and 佐藤 眞二 and 古川 卓司 and 竹下 英里 and 日向 猛 and 野田 耕司 and 松藤 成弘 and 古澤 佳也},
 month = {May},
 note = {Purpose: More than 5000 patients have been treated with passively generated carbon-ion SOBP beam at HIMAC during 1994 and 2009. Active scanning beam is another method to produce a SOBP, and is used at some facilities such as GSI. There may be some differences in biological effectiveness caused by difference in design of beam distribution, effects from fragmentation, dose-rate at unit area, and so on. The aim of this study is to confirm the difference in the biological effectiveness of scanning beams and passive beams. 
Materials and Methods: We used HSG cells that have been used as a standard for RBE measurements of therapeutic ion beams in Japan. The cells were cultured in Eagle-MEM medium supplemented with 10% fetal bovine serum and antibiotics in CO2 incubator. The cells were seeded on 25 mm diameter culture cover slips (1.5x105 cells/slip) in 35 mm dishes or NUNC slide flasks 1.5 days before irradiation. The cells on the slips were transferred into a special made Cell-Stack chamber at defined 4 different depths in the SOBP. Cell exposure was performed with passive and scanning beams at NIRS or scanning beam at GSI. Colony formation assay was applied to obtain cell survival after 14 days post-incubation.
Results: The biological effectiveness in SOBP at proximal (-25 mm), middle (+/- 0 mm), distal (+25 mm) and distal-end (+28 mm) positions, at 10% survival were decreased slightly with the depth at NIRS (passive beam), and it increased slightly at GSI (scanning beam). This may caused the difference in physical dose distribution in SOBP that depends on calculation models used at each facility. Biological dose distribution at distal position normalized to that at proximal position was 1.04 at HIMAC (a ridge-filter #002) and 0.93 at GSI (4 GyE clinical distribution), where as the physical dose distribution was 0.66 and 0.74, respectively. The ratio of biological and physical doses showed a good agreement and the difference were both 12% (= 1.04 / 0.93 or 0.74 / 0.66). Another preliminary experiments with new scanning beam at HIMAC showed better uniformity of biological distribution in the SOBP.
Conclusion: We could confirm no big difference in uniformity of biological distribution between passive and scanning carbon-ion beam. The efficiencies to unit dose of those beams were the same. Dose rate may affects on the killing efficiency, at such high-dose rate., PTCOG 49},
 title = {Comparison of Biological Efficiencies of Scanning and Broad Carbon-ion Beams},
 year = {2010}
}