Metzger R, Richardson R, Van Riper K A
Radiation Safety Engineering, Inc., Chandler, AZ 85225.
Health Phys. 1993 Aug;65(2):164-71. doi: 10.1097/00004032-199308000-00006.
Recent recommendations by the NCRP and the ICRP have lowered the nonoccupational dose limit from 5 mSv y-1 to 1 mSv y-1 [corrected]. This change has also been incorporated in the recently revised Title 10 Code of Federal Regulations, Part 20. Shielding installed in most current diagnostic x-ray rooms was based on the 5-mSv limit when rooms or corridors adjacent to the x-ray room were unrestricted areas. A computer model for evaluating shielding in a diagnostic x-ray room has been developed using the following: the Monte Carlo Code MCNP, all materials that would normally attenuate the beam in an x-ray room, realistic assumptions for work load, and a spectrum of tube potentials based on actual usage. Results indicate that most radiographic x-ray rooms with shielding designed using the conservative assumptions in NCRP 49 will meet the new standards.
美国国家辐射防护与测量委员会（NCRP）和国际辐射防护委员会（ICRP）最近的建议已将非职业性剂量限值从5毫希沃特/年降至1毫希沃特/年[已修正]。这一变化也已纳入最近修订的《联邦法规汇编》第10编第20部分。当与X射线室相邻的房间或走廊为非限制区时，大多数现有诊断X射线室安装的屏蔽是基于5毫希沃特的限值设计的。利用以下条件开发了一种用于评估诊断X射线室屏蔽的计算机模型：蒙特卡罗代码MCNP、X射线室中通常会衰减射线束的所有材料、对工作量的实际假设以及基于实际使用情况的管电压谱。结果表明，按照NCRP 49中的保守假设设计屏蔽的大多数射线照相X射线室将符合新标准。
