Trappier A S, Johnson L P
Physics Department, Medgar Evers College (CUNY), Brooklyn.
J Natl Med Assoc. 1993 Mar;85(3):205-8.
Radiation shielding is required in radiotherapy accelerators to limit the dose equivalent rate from x-rays produced at the target in all directions except that of the useful forward directed beam. Calculations were made in terms of weekly workload of 50,000 cGy delivered to the isocenter per 5-day week, treating 25 patients per day at 400 cGy per patient. It is desirable to reduce the total exposure at the maze door below 30 Rem (0.30 Sv)/wk assuming full-time occupancy. The maze was designed to reduce the neutron dose to an acceptable level by slowing the neutrons to thermal velocities and then absorbing them in a low Z material in the egress.
放射治疗加速器需要进行辐射屏蔽，以限制靶区产生的X射线在除有用前向束方向之外的所有方向上的剂量当量率。计算是基于每周5天的工作量，即每周向等中心输送50,000 cGy，每天治疗25名患者，每名患者400 cGy。假设全时占用，希望将迷宫门处的总暴露量降低至每周30雷姆（0.30 Sv）以下。迷宫的设计是通过将中子减速至热速度，然后在出口处用低Z材料吸收它们，从而将中子剂量降低到可接受的水平。
