Schmid Ernst, Roos Hartmut, Kramer Hans-Michael
Radiobiological Institute, University of Munich, 80336 Munich, Germany.
Radiat Prot Dosimetry. 2008;130(4):442-6. doi: 10.1093/rpd/ncn069. Epub 2008 Mar 6.
Radiobiological evidence is shown concerning a significant depth-dependence of the maximum relative biological effectiveness at limiting low doses (RBE(M)) of (60)Co gamma rays in a cubic polymethylmethacrylate (PMMA) phantom of 30 cm edge length. Using the dose-response curve for the dicentric data in human lymphocytes obtained in the present experiment at a depth of 20 cm, together with the comprehensive and consistent data set determined earlier at smaller depths of the PMMA phantom, there is an increase in the RBE(M) value by a factor of 2.18 +/- 1.25 at a depth of 20 cm relative to 1 cm in the phantom. All the dicentric data are based on identical exposure durations and irradiation temperatures as well as identical culture and evaluation conditions, with blood from the same donor.
在边长为30厘米的立方聚甲基丙烯酸甲酯（PMMA）模型中，给出了关于（60）Coγ射线在低剂量限制条件下最大相对生物效应（RBE(M)）显著深度依赖性的放射生物学证据。利用本实验在20厘米深度处获得的人淋巴细胞双着丝粒数据的剂量反应曲线，以及先前在PMMA模型较小深度处确定的全面且一致的数据集，相对于模型中1厘米深度处，20厘米深度处的RBE(M)值增加了2.18±1.25倍。所有双着丝粒数据均基于相同的暴露持续时间、辐照温度以及相同的培养和评估条件，且使用的是同一供体的血液。
