中文摘要：

目的：基于光子计数探测器的X线CT（PhotonCountingComputedTomography，PCCT）较传统CT成像最突出的特点是可实现多参数成像，包括基物质成像和单能量成像等。然而，当前商用光子计数探测器的计数率低、能量分辨率有限，大大限制了PCCT更为广泛的临床应用。为了更好地研究PCCT成像技术，本文系统地研究了基于光子计数探测器的X线CT蒙特卡罗仿真方法，深入探讨了K值效应及能量段宽度对成像质量的影响。方法：首先通过PENELOPE（Pene．trationandEnergyLossofPositronsandElectrons）仿真软件对PCCT成像系统进行设计，完成光子计数探测器的配置，其后基于仿真系统完成不同体模的能谱CT数据仿真。针对K值效应及能量段宽度对图像质量的影响，对相关数据进行了定量分析。结果：本研究设计的PCCT成像仿真系统能有效地实现能谱CT数据采集与成像性能分析，其中对比剂在K缘处的对比度噪声比较其在非K缘处高，并且对比剂在适当宽度的能量段里获得优质的图像。结论：本研究设计的PCCT成像仿真系统能有效地实现能谱CT数据采集与成像性能分析。

英文摘要：

Objective Compared with conventional computed tomography （CT）, photon counting CT （PCCT） can achieve multi-parameter imaging, including basic material imaging and virtual monochromatic spectral CT imaging. Nowadays commercial PCCT has low count rate and limited energy resolution, significantly restricting the wider clinical application. The PCCT imaging technology is better studied in the paper by systematically introducing X-ray CT Monte Carlo simulation method based on photon counting detector, and studying in-depth the effect of K-edge effect and energy bin window width on PCCT image quality. Methods The PCCT imaging system was designed by using PENELOPE simulation software to configure the photon counting detector. Based on the simulation system, the energy spectrum CT data simulations of different phantoms were achieved. Finally, the data related to the effect of K-edge effect and energy bin window width on PCCT image quality were quantitatively analyzed. Results The designed PCCT simulation system effectively realized the energy spectrum CT data acquisition and imaging performance analysis. The contrast-noise ratio of contrast agent at K-edge was higher than that of contrast agent not at K-edge. And high-quality images were obtained when the contrast agent was in the energy bin with suitable window width. Conclusion The designed PCCT simulation system can effectively achieve the energy spectrum CT data acquisition and imaging performance analysis.