Radiat Res. 2012 Aug;178(2):AV125-38. doi: 10.1667/rrav10.1.
Multiple-fraction experiments have been carried out to determine the response to repeated small doses of 240 kV X rays down to 45 rad per fraction, using the mouse skin reaction system. A method of irradiating without anesthetic was developed so that up to 64 fractions could be given within 8 days; over this time, proliferation was negligible. It was found that the total dose required to produce a given reaction continued to rise with the number of fractions above 30 fractions, in contradiction to the recent conclusions of Dutreix and colleagues. The plot of reciprocal total dose against size of each fraction was shown to be linear. This finding led to an analysis in terms of a function F(e), which is proportional to the slope of the chord of the appropriate cell survival curve from the origin to the dose per fraction used. The cell survival curve derived here was well fitted by an equation of the form (s = e(-(αD+βD(2)). The initial slope was 1/690 rad and the slope at 2340 rad was 1/126 rad. Thus, 1 rad at a dose approaching 0 rad has 18% of the effect of 1 rad at a single dose of 2340 rad for mouse skin reactions. A cell survival theory based on Neary's theory of chromosome aberrations is presented and the current results are consistent with the postulate that cell death results from the formation of chromosome aberrations.
已经进行了多次分次实验，以确定使用小鼠皮肤反应系统对重复小剂量 240 kV X 射线（每个分次剂量低至 45 rad）的反应。开发了一种无需麻醉的照射方法，以便在 8 天内给予多达 64 个分次剂量；在此期间，增殖可以忽略不计。结果发现，要产生给定反应所需的总剂量随着分次剂量超过 30 次而持续增加，这与 Dutreix 及其同事最近的结论相矛盾。结果表明，每个分次剂量的倒数总剂量与每个分次剂量大小的关系呈线性。这一发现导致了一种基于函数 F(e)的分析，该函数与从原点到使用的每个分次剂量的细胞存活曲线弦的斜率成正比。这里得出的细胞存活曲线很好地符合形式为 (s = e(-(αD+βD(2)))的方程。初始斜率为 1/690 rad，在 2340 rad 时斜率为 1/126 rad。因此，在接近 0 rad 的剂量下，1 rad 的效果为单次剂量 2340 rad 下 1 rad 的效果的 18%，适用于小鼠皮肤反应。提出了一种基于 Neary 染色体畸变理论的细胞存活理论，目前的结果与细胞死亡是由染色体畸变形成的假设一致。
