Full-Field Imaging System of X-Ray Transmission, Scattering, and Fluorescence Tomography With Polychromatic Source

X-ray transmission computed tomography (XCT) is a method to image the structure of objects. X-ray fluorescence computed tomography (XFCT) is a way for quantitative imaging of high-Z element concentrations. The dual-modality imaging system integrating XCT and XFCT has been designed and extensively studied. In the existing dual-modality imaging system, the detector of XFCT not only collects fluorescence photons but also scattering photons, and the scattering photons are always regarded as noise signals. But in fact, the scattering photons contain electron density information, which is complementary to XCT. In this paper, we design a new three-mode imaging system for transmission, fluorescence, and scattering tomography, which consists of a conventional polychromatic X-ray tube, a pinhole collimator, a photon-counting detector with high energy resolution for scattering and fluorescence imaging, and an energyintegrating detector with high spatial resolution for transmission imaging. Through this system, linear attenuation coefficient, high-Z element concentration, and electron density could be reconstructed simultaneously. We also propose a new algorithm to simultaneously realize the virtual monoenergetic imaging at different energies and the accurate attenuation correction of XFCT without extra prior information. The system’s feasibility and the algorithm’s accuracy are verified through both numerical simulations and experiments.