Broerse J J, van Bekkum D W, Zoetelief J, Zurcher C
Institute of Applied Radiobiology and Immunology TNO, Rijswijk, The Netherlands.
Radiat Res. 1991 Oct;128(1 Suppl):S128-35.
The risks of total-body irradiation with large doses of X rays (average dose 6.7 Gy) and fission neutrons (average dose 3.4 Gy) were investigated by keeping a group of long-term surviving monkeys from an experiment on acute effects under continuous observation. On the basis of the number of animals developing tumors in each group as a function of the total observation period and the average absorbed dose, relative biological effectiveness (RBE) values between 4 and 5 have been derived at these high dose levels. In experiments on mammary carcinogenesis in rats the highest RBE values are observed for neutrons with energies of 0.43 to 1 MeV as produced by the p + T reaction or by the fission process. Based upon linear dose-response curves for neutrons and X rays, a maximum RBE value of 15 was observed for induction of adenocarcinomas in WAG/Rij rats. Appreciably higher RBE values would be obtained if the results of the gamma-ray exposure, indicating a nearly quadratic dose-response relationship, were used as a baseline. For radiation protection applications it should be realized, however, that such an increase will be caused by the lower efficiency of low-linear-energy-transfer radiation rather than by an increase in efficiency of the neutron irradiation at low doses.
通过持续观察一组来自急性效应实验的长期存活猴子，研究了大剂量X射线（平均剂量6.7 Gy）和裂变中子（平均剂量3.4 Gy）全身照射的风险。根据每组中发生肿瘤的动物数量作为总观察期和平均吸收剂量的函数，在这些高剂量水平下得出相对生物效应（RBE）值在4至5之间。在大鼠乳腺癌发生实验中，观察到由p + T反应或裂变过程产生的能量为0.43至1 MeV的中子具有最高的RBE值。基于中子和X射线的线性剂量反应曲线，在WAG/Rij大鼠中诱导腺癌时观察到的最大RBE值为15。然而，如果将表明几乎呈二次剂量反应关系的γ射线照射结果用作基线，则会获得明显更高的RBE值。但是，对于辐射防护应用，应该认识到这种增加将是由低线性能量传递辐射的较低效率引起的，而不是由低剂量中子照射效率的提高引起的。
