Simpkin D J, Dixon R L
St. Luke's Medical Center, Milwaukee, WI 53201-2901, USA.
Health Phys. 1998 Mar;74(3):350-65. doi: 10.1097/00004032-199803000-00008.
Methods are presented for determining the thickness requirements for barriers against scatter and leakage radiation generated in a diagnostic x-ray facility. Equations are developed that express the shielded doses due to scatter and leakage with explicit dependence on the operating potential used in clinical settings. The 1972 scatter experiment of Trout and Kelley is revisited, with suggested values for the scatter fraction that are somewhat different from those used in Report Number 49 of the NCRP. The dose from leakage radiation due to operation at clinical kVp settings is seen to be orders of magnitude below that predicted by the model in NCRP49. The unshielded secondary radiation dose in air at unit distance and workload is presented as a function of operating potential and for clinical workload distributions. The net transmission of secondary radiations through common shielding materials is presented. Compared to that for the primary beam at the same potential, the transmission of secondary radiation is more penetrating due to the inclusion of leakage radiation that has been hardened by the tube housing. Sample shielding calculations illustrate the utility of this scheme.
本文介绍了确定诊断X射线设备中散射和泄漏辐射防护屏障厚度要求的方法。推导了一些方程，这些方程明确表示了由于散射和泄漏导致的屏蔽剂量与临床使用的工作电压之间的关系。重新审视了1972年特劳特和凯利的散射实验，提出的散射分数值与NCRP第49号报告中使用的值略有不同。在临床千伏峰值设置下运行时，泄漏辐射产生的剂量比NCRP49模型预测的剂量低几个数量级。给出了单位距离和工作量下空气中未屏蔽二次辐射剂量与工作电压以及临床工作量分布的函数关系。介绍了二次辐射通过常用屏蔽材料的净传输情况。与相同电压下的初级射线相比，由于包含了被管套硬化的泄漏辐射，二次辐射的穿透性更强。屏蔽计算示例说明了该方案的实用性。
