Department of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9, Canada.
Med Phys. 2011 Mar;38(3):1705-8. doi: 10.1118/1.3555296.
Easy particle propagation (Epp) is a user code for the EGSnrc code package based on the c+ + class library egspp. A main feature of egspp (and Epp) is the ability to use analytical objects to construct simulation geometries. The authors developed Epp to facilitate the simulation of x-ray imaging geometries, especially in the case of scatter studies. While direct use of egspp requires knowledge of c+ +, Epp requires no programming experience.
Epp's features include calculation of dose deposited in a voxelized phantom and photon propagation to a user-defined imaging plane. Projection images of primary, single Rayleigh scattered, single Compton scattered, and multiple scattered photons may be generated. Epp input files can be nested, allowing for the construction of complex simulation geometries from more basic components. To demonstrate the imaging features of Epp, the authors simulate 38 keV x rays from a point source propagating through a water cylinder 12 cm in diameter, using both analytical and voxelized representations of the cylinder. The simulation generates projection images of primary and scattered photons at a user-defined imaging plane. The authors also simulate dose scoring in the voxelized version of the phantom in both Epp and DOSXYZnrc and examine the accuracy of Epp using the Kawrakow-Fippel test.
The results of the imaging simulations with Epp using voxelized and analytical descriptions of the water cylinder agree within 1%. The results of the Kawrakow-Fippel test suggest good agreement between Epp and DOSXYZnrc.
Epp provides the user with useful features, including the ability to build complex geometries from simpler ones and the ability to generate images of scattered and primary photons. There is no inherent computational time saving arising from Epp, except for those arising from egspp's ability to use analytical representations of simulation geometries. Epp agrees with DOSXYZnrc in dose calculation, since they are both based on the well-validated standard EGSnrc radiation transport physics model.
Easy particle propagation（Epp）是 EGSnrc 代码包基于 c++类库 egspp 的用户代码。egspp（和 Epp）的一个主要特点是能够使用分析对象来构建模拟几何形状。作者开发了 Epp 来方便 X 射线成像几何形状的模拟，特别是在散射研究的情况下。虽然直接使用 egspp 需要了解 c++，但 Epp 不需要编程经验。
Epp 的功能包括在体素化模型中计算沉积的剂量和光子传播到用户定义的成像平面。可以生成原始、单 Rayleigh 散射、单 Compton 散射和多次散射光子的投影图像。Epp 的输入文件可以嵌套，从而允许从更基本的组件构建复杂的模拟几何形状。为了演示 Epp 的成像功能，作者模拟了 38keV 从点源传播通过直径为 12 厘米的水圆柱的 X 射线，使用了圆柱的分析和体素化表示。模拟在用户定义的成像平面上生成原始和散射光子的投影图像。作者还在 Epp 和 DOSXYZnrc 中模拟体素化模型中的剂量评分，并使用 Kawrakow-Fippel 测试检查 Epp 的准确性。
使用 Epp 模拟水圆柱的体素化和分析描述的成像结果之间的差异在 1%以内。Kawrakow-Fippel 测试的结果表明 Epp 和 DOSXYZnrc 之间的一致性较好。
Epp 为用户提供了有用的功能，包括从简单几何形状构建复杂几何形状的能力和生成散射和原始光子图像的能力。除了 egspp 能够使用模拟几何形状的分析表示形式之外，Epp 没有固有的计算时间节省。Epp 在剂量计算方面与 DOSXYZnrc 一致，因为它们都基于经过充分验证的标准 EGSnrc 辐射传输物理模型。
