摘要
目的探讨在不同辐射能量的情况下,通过漏、散射线之间的比较关系,选择适宜的射线种类来评估屏蔽厚度。方法应用常规法和修正法计算主、副屏蔽墙厚度的辐射防护情况。结果在散射线的安全系数为2,能量<15 MV时,修正法的比例系数大于常规法的比例系数;能量>15 MV时,其修正法的比例系数和常规法的比例系数较接近。在漏射线的安全系数不同时为1,且能量<15 MV的情况下,常规法的比例系数大于修正法的比例系数;在能量>15 MV时,修正法的比例系数和常规法的比例系数较接近。在主屏蔽中,由于主射线能量比其他射线大得多,所以主要考虑主射线的屏蔽即可;如:在副屏蔽墙壁厚度计算时,在安全系数同时为2时,如大于其相应的比例系数(能量为4、6、10、15、18、20、24 MV时,其比例系数a值分别为1.6×10~8、4.2×10~7、2.6×10~7、5.8×10~6、8.0×10~6、5.7×10~6、4.6×10~6),只考虑漏射线的作用即可;反之,小于每种情况下对应的比例系数时,只考虑散射线的作用即可。结论在主屏蔽厚度计算时,由于主射线远大于漏散射线,所以可不考虑其比例系数的问题,只需应用主射线计算其屏蔽厚度即可;在副屏蔽墙厚度计算时,需根据漏射线与散射线的比例及能量大小情况,来选择适宜的射线种类,进而对辐射防护屏蔽进行优化。
[Objective] To discuss finding suitable rays to evaluate shielding thickness via comparison of leaking rays and scattered rays,under different levels of radiation energy.[Methods] Conventional method and correction method were used to calculate the thickness of main shield wall and deputy shield wall.[Results]When the safety coefficients of the scattering rays were 2,energy 〈15 MV,the proportionality coefficient of correction method was greater than that of conventional method. When the energy15 MV,the proportionality coefficient of correction method was close to that of conventional method. When the safety coefficients of the leaking rays were 1 not at the same time,and the energy〉 15 MV,the proportionality coefficient of correction method was close to that of conventional method. In the main rays shielding,due to the bigger energy of main rays,just considering shielding of it was necessary,for example,in the calculation of shield wall thickness,when safety coefficients were 2at the same time and greater than other proportionality coefficients（when the energy was 4,6,10,15,18,20,24 MV,the proportionality coefficient a was 1.6 ×10^8,4.2 ×10^7,2.6 ×10^7,5.8 ×10^6,8.0 ×10^6,5.7 ×10^6,4.6 ×10^6）,only considering the effect of leaking rays was necessary. On the contrary,when safety coefficients were smaller than the corresponding proportionality coefficient in each case,only considering the effect of scattered rays was necessary.[Conclusion]In the calculation of main shield wall thickness,because main rays are greater than scattering rays,therefore proportionality coefficient can be ignored,only to calculate the shield thickness by using main rays＇ energy is necessary. In the calculation of deputy shield wall thickness,the choice of suitable ray depends on the proportion of leaking rays to scattered rays and the size of the energy,then the radiation protection shielding can be optimized.
出处
《职业与健康》
CAS
2017年第8期1023-1026,共4页
Occupation and Health
关键词
医用电子直线加速器
辐射防护
屏蔽优化设计
Medical accelerator
Radiation protection
Shielding optimization calculation
