@misc{oai:repo.qst.go.jp:00069038,
 author = {Matsumoto, Yoshitaka and Shimao, Daisuke and Aoki, Mizuho and Hirayama, Ryoichi and Kubota, Nobuo and Ando, Koichi and Tsujii, Hirohiko and Furusawa, Yoshiya and 松本 孔貴 and 青木 瑞穂 and 平山 亮一 and 窪田 宜夫 and 安藤 興一 and 辻井 博彦 and 古澤 佳也},
 month = {Jul},
 note = {(Introduction) Heavy-ion beams have good dose distribution for tumor. Carbon beams, accelerated by HIMAC in National Institute of Radiological Sciences (NIRS), is a candidate for use in hypofractionated radiotherapy of tumors included malignant melanoma of choroid, non-small cell lung cancer or hepatocellular carcinoma. In this case, relative biological effectiveness (RBE) at high dose region (low survival level) must be considered however, the RBE is calculated physically and not verified biologically. (Purpose) The purpose of this study is to estimate RBE at high dose range as well as low dose range using monolayer cells and multicellular spheroids. (Materials and Methods) One human malignant melanoma cell line, HMV-I was used for this study. We used the 96 wells spheroid plates (SUMILOM MS-0096S) for making the multicellular spheroids. Cells were irradiated with 290 MeV/u carbon ions, 490 MeV/u silicon ions or 500 MeV/u argon ions with a dose-averaged about 13, 35, 100 and 300keV/um LET and X-rays. (Results) Surviving fractions of cells exposed to carbon beams and X-rays at a lower dose range (0-8 Gy) and a higher range (8-15 Gy) were obtained using monolayer cells and multicellular spherooids, respectively. The lenear-quadratic (LQ) equation fits well in survival data of monolayer cultures after both radiation at lower dose region. The multi-target single-hit (MT) equation fits well in those of spheroids at higher dose region. In addition, we could fit with a formula combined MT equation and initial slope part of LQ equation as well as multi-process (MP) equation, to survival data. This equation has good fitting for survival data in wide dose range when both monolayer and spheroid data was combined. (Conclusion) We could estimate RBE values of carbon beams from low to high dose range by converting the surviving fractions of spheroids into monolayer cells using the MP equation. RBE values at high dose range converged on the fixed values at 1.1-1.4, but varied in LET values at very low dose range (0-4 Gy)., The 13th International Congress of Radiation Research},
 title = {Estimation of RBE Values for Carbon-Ion Beams at High-Dose Region Using Multicellular Spheroids of HMV-I Cells},
 year = {2007}
}