Levine Zachary H, Blattner Timothy J, Peskin Adele P, Pintar Adam L
National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.
National Institute of Standards and Technology, Boulder, CO 80305 USA.
J Res Natl Inst Stand Technol. 2019 May 22;124:1-23. doi: 10.6028/jres.124.013. eCollection 2019.
Fundamental limits for the calculation of scattering corrections within X-ray computed tomography (CT) are found within the independent atom approximation from an analysis of the cross sections, CT geometry, and the Nyquist sampling theorem, suggesting large reductions in computational time compared to existing methods. By modifying the scatter by less than 1 %, it is possible to treat some of the elastic scattering in the forward direction as inelastic to achieve a smoother elastic scattering distribution. We present an analysis showing that the number of samples required for the smoother distribution can be greatly reduced. We show that fixed forced detection can be used with many fewer points for inelastic scattering, but that for pure elastic scattering, a standard Monte Carlo calculation is preferred. We use smoothing for both elastic and inelastic scattering because the intrinsic angular resolution is much poorer than can be achieved for projective tomography. Representative numerical examples are given.
通过对截面、CT 几何结构和奈奎斯特采样定理进行分析，在独立原子近似下找到了 X 射线计算机断层扫描（CT）中散射校正计算的基本限制，这表明与现有方法相比，计算时间大幅减少。通过将散射修改不到 1%，可以将正向的一些弹性散射视为非弹性散射，以实现更平滑的弹性散射分布。我们进行的一项分析表明，对于更平滑的分布所需的样本数量可以大幅减少。我们表明，固定强制检测可用于非弹性散射，所需点数少得多，但对于纯弹性散射，首选标准蒙特卡罗计算。我们对弹性和非弹性散射均使用平滑处理，因为其固有角分辨率比投影断层扫描所能达到的要差得多。文中给出了代表性的数值示例。
