Combining deterministic and Monte Carlo calculations for fast estimation of scatter intensities in CT
Combining deterministic and Monte Carlo calculations for fast estimation of scatter intensities in CT
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DOI：
10.1088/0031-9155/51/18/008
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发表时间：
2006-09-21
影响因子：
3.5
通讯作者：
Kalender, Willi A.
中科院分区：
文献类型：
--
作者：
Kyriakou, Yiannis;Riedel, Thomas;Kalender, Willi A.
通过在计算机断层摄影（CT）中使用多行和平板探测器来增加体积覆盖的副作用是散射辐射对测量信号的贡献同时增加。为了研究散射对用于CT成像的X射线投影的影响，我们的研究旨在开发一种用于快速计算初级和散射强度的模拟工具。我们开发了一种确定性的方法来评估单散射事件的测量信号的贡献。通过蒙特卡罗模拟对多次散射的研究表明，与单次散射相比，它会产生平滑的信号。提出了一种混合方法，以优化性能的散射模拟：一个快速和准确的分析计算的单散射强度结合粗蒙特卡罗（MC）估计的多个散射，以减少整体计算费用，同时确保可接受的信号质量。总散射的混合模拟的结果与相应的MC仅模拟非常一致，从而使我们能够将计算时间减少几个数量级。平板CT成像的二维散射分布的估计花费约30-40 s（每个投影）。混合方法提供了一个现实的模拟X射线散射，并提供了散射校正方法的基础。
A side effect of increased volume coverage by using multi-row and flat-panel detectors in computed tomography ( CT) is the concurrently growing contribution of scattered radiation to the measured signal. In order to investigate the effect of scatter on x-ray projections used for CT imaging, our study aimed at the development of a simulation tool for fast calculation of primary and scatter intensities. We developed a deterministic method to assess the contribution of single-scatter events to the measured signal. The investigation of multiple scatter by Monte Carlo simulations showed that it results in a smooth signal as compared to single scatter. A hybrid method is proposed in order to optimize the performance of the scatter simulation: a fast and exact analytical calculation of the single-scatter intensity combined with a coarse Monte Carlo ( MC) estimate of multiple scatter to reduce overall computational expenses, while assuring an acceptable signal quality. The results of the hybrid simulation of total scatter were in excellent agreement with the corresponding MC only simulations, thereby allowing us to reduce computational time by orders of magnitude. Estimates of two-dimensional scatter distributions for flat-panel CT imaging took about 30-40 s (per projection). The hybrid method provides a realistic simulation of x-ray scatter and offers a basis for scatter correction approaches.