基于光子计数探测器的CT系统在蒙特卡罗模拟平台的实现

为了解决利用Matlab,C++等软件对投影图像、重建算法的模拟无法真实反映CT系统的成像过程的问题,在研究模拟理论的基础上,首先利用Geant4和Gate数据包搭建蒙特卡罗模拟平台;然后通过光子计数探测器模拟多能谱CT成像,同时分析在不同标准下的阈值划分对重建图像的影响,利用光子计数探测器同时扫描出多个不同能段下的投影图像,并对比出各个能段下的投影效果;其次,根据不同能段的划分,选取每个能段的360度下的投影数据,利用FBP算法重建投影切片图像;最后,对所得到的切片图像进行材料区分,得到硫和铝的衰减系数曲线。实验结果表明,模拟方法对光子计数探测器的成像过程做出了模拟,得到了较好的模拟图像,并给出了相关阈值的划分依据,可为其他CT成像研究提供参考。

CT system based on photon counting detector is implemented in monte carlo simulation platform

In order to solve the Matlab and C++ to simulation the projection images, reconstruction algorithm cannot really reflect the imaging process of the CT system problems. on the basis of the research of simulation theory, first using Geant4 and Gate structures, monte carlo simulation platform, the data packets and then simulate to tellurium cadmium zinc (CZT) as the material of photon counting detectors to much energy spectrum CT imaging process, analysis under different standard of reconstruction image threshold value division, the influence of using photon counting detector at the same time can scan out several different segments of the projected image, and compare the projection of each paragraph can effect; Secondly, according to the division of different energy segments, the projection data of each energy segment is selected from 360 angles, and the projected slice image is reconstructed by FBP algorithm. Finally, the attenuation coefficient curves of sulfur and aluminum were obtained by material separation of the obtained slice images. The experimental results show that the simulation method simulates the imaging process of the photon counting detector, gets a better simulated image, and gives the basis for the division of related threshold value, which can provide reference for other CT imaging studies.