Kogelnik H D, Withers H R
Radiol Clin (Basel). 1978;47(5):362-9.
The initial shape of a cellular dose-survival curve is a factor of major importance in determining radiotherapy responses. It is probable that survival curves for mammalian cells exposed to X- and gamma-rays, as well as higher LET beams have an initial exponential region after which they bend downwards. The slope of this initial segment of the curve, and more importantly, the width of the shoulder before it bends significantly are the subject of the investigations to be reported. Because of the difficulty in measuring the biological effects of low doses of radiation--particularly in vivo--we have used multifraction experiments to determine the effects of the fractional doses. Such studies help determine the width of the shoulder and, with less precision, the slope of the initial part of the curve. The tissues we have studied include the bone marrow, testis, fibrovasculature, transplantable tumors, and the gastrointestinal tract. The results will be presented and some of the difficulties in their interpretation will be discussed.
细胞剂量存活曲线的初始形状是决定放射治疗反应的一个极其重要的因素。暴露于X射线和γ射线以及高传能线密度射束下的哺乳动物细胞的存活曲线，很可能在出现向下弯曲之前有一个初始指数区域。本报告将对该曲线这一初始部分的斜率，更重要的是，对其显著弯曲之前的肩部宽度进行研究。由于测量低剂量辐射的生物学效应存在困难——尤其是在体内——我们采用了多分次实验来确定分次剂量的效应。此类研究有助于确定肩部的宽度，并能较不精确地确定曲线初始部分的斜率。我们研究的组织包括骨髓、睾丸、纤维血管组织、可移植肿瘤和胃肠道。我们将展示研究结果，并讨论其解释过程中存在的一些困难。
