In computed tomography (CT), scattering causes server quality degradation of the reconstructed CT images by introducing streaks and cupping artifacts which reduce the detectability of low contrast objects. Monte Carlo (MC) simulation is considered the most accurate approach for scatter estimation. However, the existing MC estimators are computationally expensive, especially for high-resolution flat-panel CT. In this paper, we propose a fast and accurate MC photon transport model which describes the physics within the 1 keV to 1 MeV range using multiple controllable key parameters. Based on this model, scatter computation for a single projection can be completed within a range of a few seconds under well-defined model parameters. Smoothing and interpolation are performed on the estimated scatter to accelerate the scatter calculation without compromising accuracy too much compared to measured near scatter-free projection images. Combining the fast scatter estimation with the filtered backprojection (FBP), scatter correction is performed effectively in an iterative manner. To evaluate the proposed MC model, we have conducted extensive experiments on the simulated data and real-world high-resolution flat-panel CT. Compared to the state-of-the-art MC simulators, the proposed MC model achieved a 15\(\times\) acceleration on a single-GPU compared to the GPU implementation of the Penelope simulator (MCGPU) utilizing several acceleration techniques, and a 202 \(\times\) speed-up on a multi-GPU system compared to the multi-threaded state-of-the-art EGSnrc MC simulator. Furthermore, it is shown that for high-resolution images, scatter correction with sufficient accuracy is accomplished within one to three iterations using a FBP and the proposed fast MC photon transport model.

在计算机断层扫描 (CT) 中，散射通过引入条纹和杯突伪影导致重建 CT 图像的服务器质量下降，从而降低低对比度对象的可检测性。蒙特卡洛 (MC) 模拟被认为是最准确的散射估计方法。然而，现有的 MC 估计器的计算成本很高，尤其是对于高分辨率平板 CT。在本文中，我们提出了一种快速准确的 MC 光子传输模型，该模型使用多个可控关键参数描述了 1 keV 至 1 MeV 范围内的物理场。基于该模型，在定义明确的模型参数下，可以在几秒的范围内完成单次投影的散射计算。与测量的近无散射投影图像相比，对估计的散射执行平滑和插值以加速散射计算，而不会过多地牺牲精度。将快速散射估计与滤波反投影（FBP）相结合，以迭代方式有效地执行散射校正。为了评估提出的 MC 模型，我们对模拟数据和真实世界的高分辨率平板 CT 进行了广泛的实验。与最先进的 MC 模拟器相比，所提出的 MC 模型达到了 15 我们对模拟数据和真实世界的高分辨率平板 CT 进行了广泛的实验。与最先进的 MC 模拟器相比，所提出的 MC 模型达到了 15 我们对模拟数据和真实世界的高分辨率平板 CT 进行了广泛的实验。与最先进的 MC 模拟器相比，所提出的 MC 模型达到了 15与使用多种加速技术的 Penelope 模拟器 (MCGPU) 的 GPU 实现相比，单 GPU 上的\(\times\)加速，与多 GPU 系统上的 202 \(\times\)加速相比多线程最先进的 EGSnrc MC 模拟器。此外，它表明，对于高分辨率图像，使用 FBP 和提出的快速 MC 光子传输模型在一到三个迭代内完成具有足够精度的散射校正。