Boone J M, Cooper V N
Department of Radiology, University of California, Davis, Sacramento 95817, USA.
Med Phys. 2000 Aug;27(8):1818-31. doi: 10.1118/1.1287052.
The purpose of this investigation was to compare and validate the performance of the SIERRA Monte Carlo simulation routines for the analysis of the scatter to primary ratio (SPR) in the mammography setting. Two Monte Carlo simulation methods were addressed, the direct method was a straightforward and geometrically accurate simulation procedure, and the convolution method uses idealized geometry (monoenergetic, normally incident delta function input to the scattering medium) to produce scatter point spread functions (PSFs). The PSFs were weighted by the x-ray spectrum of interest and convolved with the field of view to estimate SPR values. The SPR results of both Monte Carlo procedures were extensively compared to five published sources, including Monte-Carlo-derived and physically measured SPR assessments. The direct method demonstrated an overall agreement with the literature of 3.7% accuracy (N=5), and the convolution method demonstrated an average of 7.1% accuracy (N=14). The comparisons were made over a range of parameters which included field of view, phantom thickness, x-ray energy, and phantom composition. Limitations of the beam stop method were also discussed. The results suggest that the SIERRA Monte Carlo routines produce accurate SPR calculations and may be useful for a more comprehensive study of scatter in mammography.
本研究的目的是比较和验证SIERRA蒙特卡罗模拟程序在乳腺摄影中分析散射与原发射线比率（SPR）的性能。研究了两种蒙特卡罗模拟方法，直接法是一种简单且几何精确的模拟程序，卷积法使用理想化几何结构（单能、垂直入射到散射介质的δ函数输入）来生成散射点扩散函数（PSF）。通过感兴趣的X射线光谱对PSF进行加权，并与视野进行卷积以估计SPR值。将两种蒙特卡罗程序的SPR结果与五个已发表的数据源进行了广泛比较，包括蒙特卡罗推导的和物理测量的SPR评估。直接法与文献的总体一致性准确率为3.7%（N = 5），卷积法的平均准确率为7.1%（N = 14）。比较是在一系列参数范围内进行的，这些参数包括视野、体模厚度、X射线能量和体模组成。还讨论了束流阻挡法的局限性。结果表明，SIERRA蒙特卡罗程序能进行准确的SPR计算，可能有助于对乳腺摄影中的散射进行更全面的研究。
