Department of Radiation Oncology, Peking University International Hospital, Beijing, China.
Department of Radiation Oncology, Peking University 3rd Hospital, Beijing, China.
J Appl Clin Med Phys. 2021 Jan;22(1):327-336. doi: 10.1002/acm2.13089. Epub 2020 Dec 9.
To evaluate the shielding effect of lead aprons (LAs) on peripheral radiation doses outside the applicator of electron beams from a linear accelerator.
Out-of-field radiation doses of 4-, 6-, 8-, 10-, 12-, and 15-MeV electron beams from an Elekta Synergy linear accelerator (linac) were measured by thermoluminescence dosimeters (TLD) at different depths (0, 0.5, 1.0, and 2.0 cm) and distances from the applicator edge (0-58 cm) in a water-equivalent slab phantom with a different number of layers of LA shielding (0-5 layers). Measurements were performed by 6 × 6, 10 × 10, 14 × 14, and 20 × 20-cm applicators at a gantry and collimator angle of 0°. The out-of-field radiation dose profiles were normalized to the maximum dose of every energy and measuring depth.
The out-of-field radiation doses (beyond 3 cm away from the field edge) decreased with an increase in the number of LA layers and distance away from the central beam axis (CAX). After shielding with the LA, the out-of-field doses decreased by up to approximately 99% compared with the no shielding group. For 4-MeV electron beams, there was a peak at 24.5 cm from the CAX, which weakened with an increasing number of LA layers.
The shielding effect of the LA varied for a different number of LA layers as well as different depths and distances away from the CAX. Four LA layers were sufficient for shielding out-of-field doses of 4-15-MeV electron beams.
评估直线加速器电子束应用器外周边辐射剂量的铅围裙（LA）屏蔽效果。
在水等效平板体模中，使用热释光剂量计（TLD）在不同深度（0、0.5、1.0 和 2.0 cm）和距施源器边缘（0-58 cm）的不同位置，测量来自 Elekta Synergy 直线加速器（linac）的 4、6、8、10、12 和 15 MeV 电子束的场外辐射剂量，体模带有不同层数的 LA 屏蔽（0-5 层）。使用 6×6、10×10、14×14 和 20×20 cm 的施源器，在机架和准直器角度为 0°时进行测量。将场外辐射剂量分布归一化为每个能量和测量深度的最大剂量。
场外辐射剂量（距场边缘 3 cm 以外）随 LA 层数和距中央射束轴（CAX）距离的增加而降低。与无屏蔽组相比，LA 屏蔽后场外剂量降低了约 99%。对于 4 MeV 电子束，在距 CAX 24.5 cm 处存在一个峰值，随着 LA 层数的增加而减弱。
LA 的屏蔽效果随 LA 层数以及距 CAX 的不同深度和距离而变化。对于 4-15 MeV 电子束，使用 4 层 LA 即可屏蔽场外剂量。
