基于EI的X射线相衬显微CT成像方法及源影响机理研究

基于相衬机制的X射线相衬显微CT除了具有传统显微CT无损、精密的特点，还能显著提升图像衬度和灵敏度，在材料细微结构表征具有广阔的前景。但目前该技术主要在同步辐射源上实现，推广应用难度大。针对该问题，本项目拟利用EI原理对源相干性要求较低、射线利用率较高等优势，开展实验室X射线源相衬显微CT成像方法及源影响机理研究。首先，基于EI原理构建实验室X射线源相衬显微CT成像方案，利用几何光学近似和蒙卡方法建立相衬显微CT成像模型，实现相衬显微CT模拟仿真，研究信息提取方法和图像重建算法；在此基础上表征实验室X射线源条件对成像结果的影响因素并研究其影响机制，通过模拟计算定量研究源条件对成像结果的影响趋势和程度，并基于研究结果优化成像方法；最后搭建原理验证装置对成像方法及源影响机理进行验证，并开展针对TATB颗粒的成像实验。研究成果将为实验室X射线源相衬显微CT技术的实现及应用提供新的理论和方法支撑。

X-ray phase-contrast micro-CT, which is based on a phase-contrast mechanism, not only has the non-destructive and precise characteristics of the traditional micro-CT, it can also significantly improve the image contrast and signal sensitivity, which has broad prospects in the field of material microstructure characterization. However, this technology is mainly implemented on synchrotron radiation sources, which is difficult to promote and apply. To solve this problem, this project intends to study phase-contrast micro-CT imaging methods and the source influence mechanism based on laboratory X-ray sources, utilizing the EI principle which has the advantages of low coherence requirements and high X-ray utilization. Firstly, a laboratory X-ray source-based phase-contrast micro-CT imaging scheme is built using the EI principle, and a phase-contrast micro-CT imaging model is established through geometrical optics approximation and the Monte Carlo method. Simulations of the phase-contrast micro-CT are performed to study the phase retrieval method and image reconstruction algorithm. On the basis of this, the main influencing factors of laboratory X-ray source conditions on imaging results are characterized, and its influence mechanisms are analyzed theoretically. The trend and degree of the influence of source conditions on imaging results are studied quantitatively by simulations, and optimizations of the imaging method are carried out based on research results. Finally, the validations of the imaging method and the source influence mechanism, as well as imaging experiments for TATB granules will be carried out through the principle prototype. The research findings will provide new theoretical and technical methodology support for the realization and application of laboratory X-ray source-based phase-contrast micro-CT technology.