A Thomson scattering X‐ray source can provide quasi‐monochromatic, continuously energy‐tunable, polarization‐controllable and high‐brightness X‐rays, which makes it an excellent tool for X‐ray fluorescence computed tomography (XFCT). In this paper, we examined the suppression of Compton scattering background in XFCT using the linearly polarized X‐rays and the implementation feasibility of linearly polarized XFCT based on this type of light source, concerning the influence of phantom attenuation and the sampling strategy, its advantage over K‐edge subtraction computed tomography (CT), the imaging time, and the potential pulse pile‐up effect by Monte Carlo simulations. A fan beam and pinhole collimator geometry were adopted in the simulation and the phantom was a polymethyl methacrylate cylinder inside which were gadolinium (Gd)‐loaded water solutions with Gd concentrations ranging from 0.2 to 4.0 wt%. Compared with the case of vertical polarization, Compton scattering was suppressed by about 1.6 times using horizontal polarization. An accurate image of the Gd‐containing phantom was successfully reconstructed with both spatial and quantitative identification, and good linearity between the reconstructed value and the Gd concentration was verified. When the attenuation effect cannot be neglected, one full cycle (360°) sampling and the attenuation correction became necessary. Compared with the results of K‐edge subtraction CT, the contrast‐to‐noise ratio values of XFCT were improved by 2.03 and 1.04 times at low Gd concentrations of 0.2 and 0.5 wt%, respectively. When the flux of a Thomson scattering light source reaches 10¹³ photons s⁻¹, it is possible to finish the data acquisition of XFCT at the minute or second level without introducing pulse pile‐up effects.

中文翻译：

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基于Thomson散射光源的线偏振X射线荧光计算机断层扫描：蒙特卡洛研究。

汤姆森散射X射线源可以提供准单色，连续能量可调，偏振可控和高亮度X射线，这使其成为X射线荧光计算机断层扫描（XFCT）的绝佳工具。在本文中，我们研究了使用线性偏振X射线抑制XFCT中的康普顿散射本底以及基于这种光源的线性偏振XFCT的实现可行性，涉及幻像衰减的影响和采样策略及其优势。超过K边缘消减计算机断层扫描（CT），成像时间和潜在脉冲堆积效应（通过蒙特卡洛模拟）。在仿真中采用了扇形光束和针孔准直仪的几何形状，模型是聚甲基丙烯酸甲酯圆柱体，内部装有cylinder（Gd）负载的水溶液，Gd浓度为0.2至4.0 wt％。与垂直极化的情况相比，使用水平极化将康普顿散射抑制了约1.6倍。通过空间和定量鉴定成功地重建了含Gd幻影的准确图像，并验证了重建值和Gd浓度之间的良好线性。如果不能忽略衰减效果，则必须进行一个完整的周期（360°）采样并进行衰减校正。在低Gd浓度为0.2和0.5 wt％的条件下，K边缘减影CT的XFCT的对比度噪声比值分别提高了2.03和1.04倍。当汤姆逊散射光源的光通量达到10 ^13个 光子s ^-1时，可以在不引起脉冲堆积效应的情况下，在分钟或秒级完成XFCT的数据采集。