Ezzati Ahad Ollah, Studenski Matthew T, Gohari Masuomeh
Department of Nuclear Physics, Faculty of Physics, University of Tabriz, Tabriz, Iran.
Department of Radiation Oncology, University of Miami, Miami, FL, USA.
J Med Phys. 2020 Oct-Dec;45(4):221-225. doi: 10.4103/jmp.JMP_29_20. Epub 2021 Feb 2.
Source modeling is an approach to reduce computational burden in Monte Carlo simulations but at the cost of reduced accuracy. Although this method can be effective, one component of the source model that is exceptionally difficult to model is the electron contamination, a significant contributor to the skin and shallow dose.
To improve the accuracy for the electron contamination component of the overall source model, we have generated a spatial mesh based surface source model.
The source model is located downstream from the flattening filter and mirror but upstream from the movable jaws. A typical phase space file uses around ten parameters per particle, but this method simplifies this number to five components. By using only the electron distance from the central axis, angles from the central axis and energy, the computational time and disk space required is greatly reduced.
Despite the simplification in the source model, the electron contamination is still accurate to within 1.5%.
源建模是一种在蒙特卡罗模拟中减少计算负担的方法，但代价是精度降低。尽管这种方法可能有效，但源模型中一个特别难以建模的成分是电子污染，它是皮肤和浅层剂量的一个重要贡献因素。
为了提高整体源模型中电子污染成分的精度，我们生成了一种基于空间网格的表面源模型。
源模型位于均整滤过器和反射镜的下游，但在活动挡块的上游。一个典型的相空间文件每个粒子大约使用十个参数，但这种方法将这个数字简化为五个成分。通过仅使用电子到中心轴的距离、与中心轴的角度和能量，所需的计算时间和磁盘空间大大减少。
尽管源模型有所简化，但电子污染的精度仍在1.5%以内。
