Hi-Art tomotherapy加速器机房的辐射防护屏蔽评价

Evaluation of the room shielding thickness of Hi-Art tomotherapy system

利用Hi-Art tomotherapy加速器辐射场的数据,来计算某医院同型加速器机房防护屏蔽厚度,并进行职业病危害辐射防护评价。由于螺旋断层加速器自屏蔽结构的存在,对于其机房屏蔽防护设计只需考虑散射线和漏射线。根据同型加速器辐射场特性,计算以加速器中心点为中心、每隔15o张角所对应机房墙体辐射防护屏蔽厚度,并对机房的设计值进行对比评价。结果表明,机房各屏蔽体所需防护屏蔽厚度最大值为与加速器中心点张角为15o处,东、南、西、北面墙体、顶棚、地板所需屏蔽厚度分别为1023、975、917、1460、1147和1189mm。经核实计算,除北侧防护墙设计厚度(1200mm)偏小外,其余均满足辐射防护屏蔽的要求。

In this paper,we calculate and evaluate the room shielding thickness of a Hi-Art tomotherapy system,which is a new type of radiotherapy facility. Due to the self-shielding of the accelerator,only scattered beam and beam leakage were considered in calculating the room shielding thickness. The radiation field of the tomotherapy system was used as the basic data to calculate the shielding thickness of every 15o solid angle. The maximum shielding thickness required of each shielding wall was at the position with the angle of 15o,and the calculated shielding thickness were 1023,975,917,1460,1147 and 1189 mm for the east wall,south wall,west wall,north wall,the roof and the floor,respectively. According to the calculation results,all shielding walls,ceiling and floor could meet the requirement of the radiation protection,but the north wall thickness of 1200 mm was a little thinner.