中文摘要：

目的：综合考察纳米铁核素（^99Fe）的照射剂量率和照射时间对杀死肿瘤细胞的影响，为低剂量率的β粒了放射性核素靶向疗法提供指导。方法：采用的三个肿瘤细胞系为：SKBR-3乳腺癌、U-118MG神经胶质瘤和A-431宫颈癌；实验模型为：在每一个样品中取10^3个肿瘤细胞,用低剂量率的β粒了照射；初始剂量率为：0．1Gy／h～0．8Gy／h；持续照射时间为：1天、3天或者7天。结果：分别用0．2Gy／h～0．3Gy／h和0．4Gy／h～0．6Gy／h的剂量率连续照射肿瘤细胞7天和3天，能够将所有肿瘤细胞样品中的细胞杀死。细胞的总辐射剂最为30Gy～40Gy。而用0．8Gy／h的剂量率照射24小时后，仅SKBR-3细胞被杀死．其它肿瘤细胞系的所有细胞都能自动修复。结论：在低剂量率的β粒了放射性核素靶向疗法中，该实验结果为照射剂量率和照射时间的确定提供了指导。

英文摘要：

Objective： The purpose of this study was to identify the effect of different dose rate and expasure time on the tumor cells, which can provide a series of direction for the targeted radionuclide therapy applying low dose rate beta irradiation. Methods： Three tumor cell lines, U- 118MG gliomas, A-431 cervical squamous carcinoma and SKBR-3 breast cancer,were used. An experimental model with 10^3 tumor cells in each sample was irradiated with low dose rate beta particles. The initial dose rates were in the range of 0.1 Gy/h-0.8 Gy/h, and the cells were continuously exposed for l day, 3days or 7days. Results： Continuous irradiation with dose rates of 0,2 Gy/h-0.3 Gy/h and 0,4 Gy/h-0.6 Gy/h for 7days and 3 days, respectively, could kill all cells in all tumor cell samples, The given total radiation doses was 30 Gy-40 Gy, However, when exposed for 24 h with about 0.8 Gy/h, only the SKBR-3 cells were successfully treated and all the other cell types recovered. Conclusions： The results served as a guideline for the combinations of dose rate and exposure time. It is necessary to kill tumor cells that low dose rate beta irradiation should be applied.