微束X射线荧光CT可无损地重建样品中三维元素分布信息，已广泛应用到多个研究领域。微束XFCT采用点扫描的成像模式，获取一副元素分布图像特别是元素三维分布时，需花费大量的时间，严重限制了该方法的广泛应用。本研究旨在建立一种全场X射线荧光CT方法，采用全场照明方式，利用多毛细管准直器法测量样品内部发出的特征X射线荧光，最后基于OSEM迭代算法和全变分约束（OSEM-TV）获得欠采样条件下较好的重建结果，提高Ｘ射线荧光CT的实验效率；同时利用成像探测器采集透射CT数据，一次实验获得全场X射线荧光CT与透射CT的数据，结合图像融合技术实现从结构成像到功能成像。

Microbeam X-ray fluorescence computed tomography（μ-XFCT）can obtain the element distribution on an arbitrary virtual section. μ-XFCT has been applied in many fields. In μ-XFCT studies, the sample is scanned line by line with a pencil beam of synchrotron X-rays, which takes an enormous amount of acquisition time to acquire a 3D tomographic image. In this project, a full-field X-ray fluorescence computed tomography is to be developed at SSRF to improve the test efficiency. The object is illuminated with a whole-volume incident beam. And X-ray fluorescence photons are collected by an X-ray detector with a polycappillary collimator. Combining subset expectation maximization and total variation(OSEM-TV) to reconstruct the information of samples with high image quality from undersampled data. Another X-ray camera is used for detecting the transmission x-rays for transmission CT(TCT). Base image fusion from XFCT image and TCT image, the resulting image will be more informative: from structural imaging to functional imaging.