Chin P W, Spezi E, Lewis D G
Department of Medical Physics, Velindre Hospital, Cardiff CF14 2TL, UK.
Phys Med Biol. 2003 Aug 21;48(16):N231-8. doi: 10.1088/0031-9155/48/16/401.
A software solution has been developed to carry out Monte Carlo simulations of portal dosimetry using the BEAMnrc/DOSXYZnrc code at oblique gantry angles. The solution is based on an integrated phantom, whereby the effect of incident beam obliquity was included using geometric transformations. Geometric transformations are accurate within +/- 1 mm and +/- 1 degrees with respect to exact values calculated using trigonometry. An application in portal image prediction of an inhomogeneous phantom demonstrated good agreement with measured data, where the root-mean-square of the difference was under 2% within the field. Thus, we achieved a dose model framework capable of handling arbitrary gantry angles, voxel-by-voxel phantom description and realistic particle transport throughout the geometry.
已经开发出一种软件解决方案，用于使用BEAMnrc/DOSXYZnrc代码在斜机架角度下进行射野剂量学的蒙特卡罗模拟。该解决方案基于一个集成体模，通过几何变换来考虑入射束倾斜的影响。相对于使用三角学计算出的精确值，几何变换在±1毫米和±1度范围内是准确的。在非均匀体模的射野图像预测中的应用表明，与测量数据具有良好的一致性，其中场内差异的均方根在2%以内。因此，我们实现了一个剂量模型框架，该框架能够处理任意机架角度、逐体素体模描述以及整个几何体中的真实粒子传输。
