单次曝光X射线微分相位衬度成像新理论和新方法研究

项目名称： 单次曝光X射线微分相位衬度成像新理论和新方法研究

项目编号： No.11475170

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 王志立

作者单位： 合肥工业大学

项目金额： 100万元

中文摘要： 基于光栅干涉仪的X射线微分相位衬度成像方法，能够有效利用常规X光源进行高灵敏度相衬成像，在生命科学、材料科学等领域具有广阔的应用前景，已经成为近年来X射线成像领域的研究热点之一。X射线微分相衬成像通常采用相位步进法来采集实验数据、提取物体的吸收、相移和散射信息。这种方法要求在横向扫描光栅的同时，对物体进行多次曝光采集多张图像。这不仅降低了成像速度，更严重的是，多次曝光增加了物体的辐射剂量。这与X射线成像设备快速、低辐射剂量的发展趋势是矛盾的，阻碍了X射线微分相衬成像方法的实用化推广。为克服相位步进法的局限性，本项目提出单次曝光X射线微分相位衬度成像新理论和新方法研究，将光子计数探测器的能量分辨能力，与物体吸收、相移和散射系数的能量变化规律有机结合起来，实现真正意义上的单次曝光相衬成像。新方法的发展将实现快速、低辐射剂量的相位衬度成像，推动X射线相衬成像技术在临床医学诊断等领域的应用。

中文关键词： X射线成像；相位衬度；信息提取；光子计数探测器；光栅干涉仪

英文摘要： X-ray differential phase contrast imaging using grating interferometry can efficiently utilize conventional X-ray sources to realize highly sensitive phase imaging. The method has also shown widespread potential applications in life science, materials science and many other fields, and therefore become a hot topic in X-ray imaging community.In X-ray grating interferometry,the phase stepping technique has been routinely adopted to collect experimental data and retrieve the absorption,phase and scattering information of the investigated object. This technique requires transverse grating scanning, and multiple exposures to the object. This results in a decreased imaging speed. More seriously, multiple exposures increase the radiation dose to the object. These two major limitations are contradictory to the development tendency of X-ray imaging devices in terms of fast and low dose, and hinder the practical implementations of X-ray differential phase contrast imaging. To overcome the limitations of the phase stepping technique, single-shot X-ray differential phase contrast with photon counting detectors is presented in this project. The novel method combines the energy resolving capability of photon counting detectors, with the energy dependence of the absorption, phase shift and scattering coefficients, to realize single-exposure phase imaging in the true sense. The novel method will allow fast and low dose X-ray phase contrast imaging, and promote the widespread implementations of X-ray phase contrast imaging in clinical medical imaging and many other fields.

英文关键词： X-ray imaging;Phase contrast;Phase retrieval;Photon counting detector;Grating interferometry