Numark N J, Kase K R
Health Phys. 1985 Mar;48(3):289-95. doi: 10.1097/00004032-198503000-00005.
We present comparisons of calculated and measured dose equivalent rates outside the shielding and in the entry mazes of 2 medical linac facilities producing x rays at 6 and 15 MV. Calculations were made using the NCRP recommendations for estimating transmission of radiation through a shielding wall and scattering of radiation in a maze. We found that, for walls made of high-density concrete, the x-ray dose rate outside the shield was estimated within 50% if transmission factors measured in the appropriate high-density concrete were used. The dose rate was overestimated by a factor of 2-4 when transmission factors for normal concrete were scaled using a density ratio. Dose equivalent rates calculated for x rays and neutrons in the entry mazes agreed within a factor of 2 with the measurements.
我们对两台分别产生6兆伏和15兆伏X射线的医用直线加速器设施屏蔽墙外和入口迷宫处的计算剂量当量率与测量剂量当量率进行了比较。计算是根据美国国家辐射防护与测量委员会（NCRP）的建议进行的，用于估算辐射透过屏蔽墙的传输以及在迷宫中的散射。我们发现，对于由高密度混凝土制成的墙壁，如果使用在适当高密度混凝土中测量的传输因子，则屏蔽墙外的X射线剂量率估计误差在50%以内。当使用密度比来缩放普通混凝土的传输因子时，剂量率被高估了2至4倍。入口迷宫中X射线和中子的计算剂量当量率与测量值在2倍的范围内相符。
