模拟多野三维适形放疗对人HeLa细胞生物效应的研究

Biological Effects of HeLa Cell Line in Three-dimensional Conformal Radiation Therapy Model with Multi-beam

目的:探讨多个照射野三维适形放疗模式对人宫颈癌细胞系HeLa细胞的生物效应。方法:采用指数生长期HeLa细胞制成单细胞悬液,接种后24h内分成3组:(1)空白对照组,细胞不进行照射,接种后直接置孵箱培养,待测。(2)急速照射组,包括1、2、4、6、8、10Gy共6个剂量点,每个剂量点的照射完成时间为1～2min。(3)模拟适形放疗照射模式组,每组所含照射剂量点同急速照射组,每个剂量点的照射完成时间为10min,各组剂量率为3Gy/min。采用成克隆分析法计算存活分数,绘制细胞存活曲线,用多靶单击数学模型拟和曲线,求出平均致死剂量Do、准阈剂量Dq等参数值。结果:急速照射组、10min照射组的照射2Gy的细胞存活分数SF2分别为0.675、0.761,Dq值分别为1.682Gy、2.136Gy,Do值分别为1.685Gy、1.832Gy。结论:多个照射野三维适形放疗模式下随分次照射时间的延长,相对剂量率降低,细胞的生物效应下降。

Objective： To investigate the radiobiological effects of mimic clinical three-dimensional conforrnal radiation therapy model with multi-beam in HeLa cell line. Methods： Single cell suspension solution of HeLa cell line were prepared with exponential growth phase cell, then irradiated by two different models 24 hours after seeding. In control group, the cells were cultured in the incuba- tor without being irradiated. In acute irradiation model, the cells were irradiated at 1, 2, 4, 6, 8, 10 Gy dose level by 6MV X ray. With each dose delivered within 1 to 2 minutes. In 3DCRT model, the same dose levels and dose rates as acute irradiation model were delivered within 10 minutes with a pulse manner. The cell-survival curves were plotted by classical colony forming assay. The values of SF2, Dq and Do in two groups were calculated according to the ＂single-hit multi-target model＂. Results： The values of SF2, Dq and Do were 0.675, 1. 682Gy and 1.685Gy in acute irradiation group, 0.761, 2.136Gy and 1.832Gy in 10 minutes irradiation group, respectively. Conclusions： This study showed that prolonged fraction delivery time, as that of 3DCRT model, would decrease the radiobiological effects.