基于同步辐射的X射线荧光CT是和X射线透射CT互补的一种发射型计算机断层成像技术，可无损重建样品内部元素空间分布，是上海光源重点发展的实验方法，拥有大量的用户需求。但目前该方法的数据采集速度较慢，大量的时间耗费在数据采集上，限制了该方法的广泛应用，快速X射线荧光CT成像一直是该领域研究的焦点和追求的目标。本研究旨在建立一种快速X射线荧光CT方法，拟基于控制与数据采集、图像重建等领域的理论与技术手段，采用"飞行"扫描模式提高数据采集效率，同时将PET和SPECT中常用的OSEM算法应用到X射线荧光CT图像重建中，减少图像重建对投影数据量的需求，实现快速X射线荧光CT成像。

Synchrotron-radiation-based X-ray fluorescence computed tomography (XFCT), a complement to absorption computed tomography (CT), is a stimulated emission tomography modality. It allows for the reconstruction of element distributions on a virtual section across a sample using various algorithms. However, XFCT has not been used as a routine tool as yet, because this has traditionally required significant data acquisition time. This study presents new approaches to accelerating XFCT that are grounded in both novel image acquisition strategies that improve the quality of the data acquired and in image reconstruction strategies that reduce the amount of data acquired. First, a method of fast scanning X-ray fluorescence imaging, on-the-fly, will be used to collect the fluorescence photons.Secondly,the ordered-subsets expectation maximization (OSEM) algorithm will be introduced to XFCT, which will lead to further reduction in data-acquisition time.