电子线放疗患者屏蔽防护实验研究

目的 探讨1~4层铅围裙（LA，0.5 mm铅当量/层）和自有专利防护装置（BSD，1~2 mm铅当量）对6~15 MeV电子线放疗时野外辐射剂量的屏蔽效果。方法 利用JR1152-B氟化锂热释光剂量片（TLD），测量不同能量、不同限光筒大小、不同距离处，经不同层数铅围裙和不同厚度BSD屏蔽前、后的野外辐射剂量，计算出铅围裙和BSD对野外辐射的遮挡率，对比分析两种方法的屏蔽效果。结果 当限光筒不变时（10 cm×10 cm），遮挡率随测量点的距离增加而增大（r=0.717，P < 0.05），随电子线能量的增大而减小（r=-0.678，P < 0.05）；当能量不变时，遮挡率与限光筒的尺寸大小无相关性（P > 0.05）；对于6和9 MeV的较低能量电子线，1 mm Pb-BSD的遮挡率略高于2层铅围裙（t=2.519、2.662，P < 0.05）， 其变化范围分别为81.5%~95.3%和55.4%~84.6%；对于12和15 MeV的较高能量电子线，2 mm Pb-BSD的遮挡率略高于4层铅围裙（t=3.768、7.934，P < 0.05），其变化范围分别为64.6%~93.4%和51.1%~92.4%。结论 铅围裙或BSD都能大幅减小野外辐射剂量，可望降低患者野外辐射二次致癌的风险，与铅围裙相比，BSD具有更明显的优势。

Experimental research of shielding the patients during electron beam radiotherapy

Objective To explore the shielding effects of 1-4 layers of lead aprons (LPs) and body shielding devices (BSDs) against stray radiation (SR) outside the electron beam field of 6-15 MeV. Methods JR-115B LiF TLDs were used to measure the stray radiation doses (SRDs) to the patient undergoing treatment, before and after being shielding, for different distances, different energies, different applicators, variable layers of LPs, and different thickness of body shielding devices (BSDs), respectively, along long calculating and comparing the shielding ratios of LPs and BSDs against SR. Results When the applicator (10 cm×10 cm) is unchanged, the shielding ratio increased with the increased distance from measuring point (r=0.717, P < 0.05) and decreased with the increased electron energy (r=-0.678, P < 0.05); when the energy was constant, there was no correlation between the shielding ratio and the size of applicator (P > 0.05); For lower energy electron beam of 6 and 9 MeV, the shielding ratio for 1 mm Pb-BSD was slightly higher than that for 2 layers of LA (t=2.519, 2 662, P < 0.05), ranging from 81.5% to 95.3% and 55.4% to 84.6%, respectively. For 12 and 15 MeV higher energy electron beam, the shielding ratio for 2 mm Pb-BSD was slightly higher than that for 4 layers of LA (t=3.768, 7.934, P < 0.05), ranging from 64.6% to 93.4% and 51.1% to 92.4%, respectively. Conclusions LAs or BSDs are availavle for effectively reducing the doses from stray radiation, and may help reduce the secondary risks from stray radiation. BSDs have more obvious advantages than LPs with regard to shielding effect.