Monte Carlo modelling of a virtual wedge
Monte Carlo modelling of a virtual wedge
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DOI：
10.1088/0031-9155/44/12/402
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发表时间：
1999-12-01
影响因子：
3.5
通讯作者：
Das, IJ
中科院分区：
文献类型：
--
作者：
Verhaegen, F;Das, IJ
与一组物理光子楔相比，由移动准直器钳口实现的非物理楔（虚拟或动态楔）提供了一种替代方案，其允许创建具有任意楔角的楔场，而不是传统的四个物理楔（15度、30度、45度和60度）。人们通常认为，非物理楔形不改变光子光谱相比，物理楔形，引入射束硬化和剂量均匀性的损失在非楔形方向。本文用蒙特卡罗程序EGS 4/BEAM研究了6-10 MV西门子MD 2加速器中单个光楔对光子谱的影响。对于6和10 MV光子束，在最大剂量深度和10 cm深度（20 x 20 cm（2）射野）的计算和测量横向剂量分布之间获得了良好的一致性。通过比较蒙特卡罗模型的物理楔形和虚拟楔形，在这项工作中所研究的，它被证实，后者有一个微不足道的影响光束质量，而前者可以引入显着的光束硬化。
Compared with a set of physical photon wedges, a non-physical wedge (virtual or dynamic wedge), realized by a moving collimator jaw, offers an alternative that allows creation of a wedged field with any arbitrary wedge angle instead of the traditional four physical wedges (15 degrees, 30 degrees, 45 degrees and 60 degrees). It is commonly assumed that non-physical wedges do not alter the photon spectrum compared with physical wedges that introduce beam hardening and loss of dose uniformity in the unwedged direction. In this study, we investigated the influence of a vidual wedge on the photon spectra of a 6-10 MV Siemens MD2 accelerator with the Monte Carlo code EGS4/BEAM. Good agreement was obtained between calculated and measured lateral dose profiles at the depth of maximum dose and at 10 cm depth for 20 x 20 cm(2) fields for 6 and 10 MV photon beams. By comparing Monte Carlo models of a physical wedge and the vidual wedge that was studied in this work, it is confirmed that the latter has an insignificant effect on the beam quality, whereas the former can introduce significant beam hardening.