Burns F J, Jin Y, Koenig K L, Hosselet S
Institute of Environmental Medicine, New York University Medical Center, New York 10016.
Radiat Res. 1993 Aug;135(2):178-88.
The carcinogenicity of electron radiation relative to argon ions in rat skin was examined, specifically investigating whether the linear-quadratic model is useful for predicting cancer yield for one type of radiation based on yields observed for a different type. Three experiments were conducted to obtain information on the relationship between cancer yield and the dose of electron radiation: (1) a conventional dose-response protocol where the number of rats per group was based on the expected tumor yield; (2) a multiple-fraction protocol designed to take advantage of yield additivity as a way to estimate carcinogenicity at lower doses; and (3) a protocol to examine the effect of age at the time of irradiation on the dose-response relationship for cancer induction. Published data on the induction of skin cancer in rats irradiated with electrons were reanalyzed and combined with results of the new experiments. Skin cancer yield versus dose for argon ions was consistent with the linear-quadratic model, but the cancer yield for electrons was considerably lower (by a factor of 6.7 at 10 Gy) than the prediction based on the linear-quadratic model. The cancer yield for electron radiation was better fitted by a dose-cubed power function than a linear-quadratic function. The results indicate a substantially lower carcinogenic effectiveness for electron radiation, especially at lower doses, in comparison to argon ions and suggest that electrons may cause cancer by a three-event pathway instead of the two-event pathway that is consistent with the results for argon ions.
研究了电子辐射相对于氩离子在大鼠皮肤中的致癌性，具体研究线性二次模型是否可用于根据一种辐射的观察产率预测另一种辐射的癌症产率。进行了三项实验以获取癌症产率与电子辐射剂量之间关系的信息：（1）一种传统的剂量反应方案，其中每组大鼠的数量基于预期的肿瘤产率；（2）一种多分割方案，旨在利用产率相加性作为估计低剂量致癌性的方法；（3）一种方案，用于研究照射时的年龄对癌症诱导剂量反应关系的影响。对已发表的关于电子辐照大鼠皮肤癌诱导的数据进行了重新分析，并与新实验的结果相结合。氩离子的皮肤癌产率与剂量符合线性二次模型，但电子的癌症产率比基于线性二次模型的预测低得多（在10 Gy时低6.7倍）。电子辐射的癌症产率用剂量立方幂函数比用线性二次函数拟合得更好。结果表明，与氩离子相比，电子辐射的致癌效力显著较低，尤其是在低剂量时，并表明电子可能通过三事件途径而非与氩离子结果一致的两事件途径导致癌症。
