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利用日本千叶重离子医用加速器HIMAC提供的碳离子束,对人类唾液腺细胞(HSG)在剂量率为0.5Gy/h的低剂量率条件下进行了辐照,运用标准的克隆形成法得到了3种不同剂量平均线性能量转移(LET)碳离子束辐照HSG细胞的剂量存活效应.与先前HSG细胞在治癌剂量率(1￣5Gy/min)下对相近剂量平均LET碳离子束辐照的剂量存活效应数据相比,HSG细胞对高LET碳离子束辐射表现出明显的剂量率效应.为在相同条件下得到碳离子束对HSG细胞的相对生物学效应(RBE),利用60Co-#射线在剂量率为0.5Gy/h的条件下辐照了HSG细胞,得到该细胞系对低LET射线响应的剂量存活效应.与先前在治癌剂量率下得到的RBE值相比,低剂量率条件下得到的RBE值总体减小.由实验发现的剂量率效应及低剂量率条件下RBE值的减小,表明由高LET碳离子束造成的辐射损伤在低剂量率条件下也存在着显著的修复效应.据此,对辐射造成细胞致死的原因进行了探讨.
Human salivary gland cells (HSG) were irradiated at a low dose rate of 0.5 Gy / h using a carbon ion beam supplied from HIMAC, a Chiba heavy ion medical accelerator, Japan. The standard clonogenic method was used to obtain 3 The dose-survival effects of different doses of mean linear energy transfer (LET) carbon beam irradiation on HSG cells were compared with those of the previous HSG cells exposed to similar doses of LET carbon ion beam at dose rates of 1 to 5 Gy / min HSG cells showed a significant dose-rate effect on high-LET carbon ion beam radiation compared to the dose-survival effect data.For the purpose of obtaining the relative biological effect (RBE) of carbon ion beam on HSG cells under the same conditions, the effect of 60Co- # ray HSG cells were irradiated at a dose rate of 0.5 Gy / h resulting in a dose-survival effect of the cell line in response to low LET radiation.Compared to the RBE values previously obtained at the cancer dose rate, low dose rate conditions The RBE value obtained under the overall decrease.From the experiment found that the dose rate effect and low dose rate RBE value under the conditions of reduction, indicating that high LET carbon ion beam radiation damage caused by the low dose rate conditions also exist significant According to this, on the radiation Causes of cell death caused by the discussion.