Experimental research of shielding the patients during electron beam radiotherapy

Abstract

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); 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. Key words: Beam field; Stray radiation dose (SRD); Thermoluminescent dosimeters (TLDs); Electron beam