Sasaki T, Mashiyama S
Gan No Rinsho. 1985 Sep;31(12):1502-11.
Recent analysis on normal tissue responses to fractionated irradiation indicated that the effect of dose-fractionation is closely related to the cell kinetics of the target cells. Namely, the dose-fractionation spares more late-responding tissues than tissues in early response. The difference between early and late-responding tissues seems to depend not only on intrinsic survival curve of target cells, but also on the capacity of PLD recovery and the redistribution in the cell cycle. Although alpha/beta ratios in LQ model calculated from data of rapidly growing animal tumors have been reported similar to those of early responding tissues, there are few reliable data on slowly growing human tumors. Thus it seems difficult at present to select indicative cases for accelerated or hyperfractionation. Thymidine labeling index of human solid tumors is widely distributed ranged from 0.03% to 57% and the corresponding potentially doubling time can be calculated at p less than 0.001 with an empirical statistical equation. Since the potential doubling time is related to the rate of repopulation of tumor cells during radiotherapy, it may be an useful indicator for selecting individual patient for specific type of dose-fractionation schedule.
最近对正常组织对分次照射反应的分析表明，剂量分割效应与靶细胞的细胞动力学密切相关。也就是说，与早期反应组织相比，剂量分割对晚期反应组织的损伤更小。早期和晚期反应组织之间的差异似乎不仅取决于靶细胞的固有存活曲线，还取决于潜在致死性损伤修复能力和细胞周期中的再分布。尽管根据快速生长的动物肿瘤数据计算出的LQ模型中的α/β比值已被报道与早期反应组织的相似，但关于缓慢生长的人类肿瘤的可靠数据却很少。因此，目前似乎很难选择适合加速分割或超分割的指示性病例。人类实体瘤的胸苷标记指数分布广泛，范围从0.03%到57%，并且可以用经验统计方程在p小于0.001的情况下计算出相应的潜在倍增时间。由于潜在倍增时间与放疗期间肿瘤细胞的再增殖速率有关，它可能是为特定类型的剂量分割方案选择个体患者的有用指标。
