Joiner M C, Denekamp J, Maughan R L
Int J Radiat Biol Relat Stud Phys Chem Med. 1986 Apr;49(4):565-80. doi: 10.1080/09553008514552811.
The partial tolerance type of 'top-up' experiment has been investigated to determine the resolution of this approach for studying the damage to mouse skin from very small doses of X-rays and neutrons. The effect of 20 fractions, each as small as 0.10 Gy of X-rays or of 0.05 Gy of neutrons, can be detected if 3 MeV neutrons are used as the 'top-up' reference radiation. This capability results from the almost linear underlying dose-response curve and highly reproducible dose-effect relationship for the low energy neutrons. The data fit the linear quadratic model of dose fractionation for X-rays down to fractional doses of 0.75 Gy, but at lower doses there is a trend towards an increase in the skin radiosensitivity. Modelling shows that this might be consistent with a sub-population of the cells showing an exceptional radiosensitivity, and a replenishment of this subpopulation occurring in the 8 h between small dose fractions. More experiments are needed at very low doses in order to confirm this hypothesis for skin and for other tissues.
已经对“追加”实验的部分耐受类型进行了研究，以确定这种方法在研究极小剂量X射线和中子对小鼠皮肤损伤方面的分辨率。如果使用3兆电子伏中子作为“追加”参考辐射，那么20次分割照射（每次低至0.10戈瑞的X射线或0.05戈瑞的中子）的效果是可以检测到的。这种能力源于低能中子几乎呈线性的潜在剂量反应曲线以及高度可重复的剂量效应关系。对于X射线，数据符合剂量分割的线性二次模型，直至分割剂量低至0.75戈瑞，但在更低剂量时，皮肤放射敏感性有增加的趋势。模型显示，这可能与表现出异常放射敏感性的细胞亚群以及在小剂量分割照射间隔的8小时内该亚群的补充有关。为了证实皮肤和其他组织的这一假设，需要在极低剂量下进行更多实验。
