Narrow-beam X-ray Luminescence Tomography Imaging System And Reconstruction Method Research

X-ray luminescence tomography imaging?XLCT?is an image that uses some nano-phosphor particles?PNPs?to generate near-infrared light under narrow beam X-ray excitation.The near-infrared light signal emitted by the fluorescent nanoparticles is received by the highly sensitive photosensitive detector,and the distribution of PNPs in the biological tissue can be recovered by the corresponding reconstruction method.Compared with traditional optical molecular imaging technology,XLCT has the following characteristics:?1?The imaging mode is free from the interference of autofluorescence;?2?Duing to X-ray has strong penetrability in biological tissues,the method can have a deeper imaging depth;?3?Since the excitation source is X-ray,XLCT can simultaneously achieve bimodal imaging of structure and function.In this paper,a narrow beam X-ray excitation luminescence tomography system is developed by single photon counting technology.Based on the experimental system,the three-dimensional reconstruction of narrow beam XLCT is carried out.In view of the ill-posed of the three-dimensional distribution of PNPs in tissue utilizing the surface fluorescence data obtained by the detector,this paper uses the gradient-decreasing L₁ regularization method to improve the ill-posed of the inverse problem and compare it with the ART method.Finally,we carried out a phantom experiment,and the experiment reconstructed the position of the PNPs inside the phantom,which further verified the feasibility of the reconstruction algorithm and system.In addition,we have carried out some meaningful simulation studies,such as the impact of X-ray beam width on image reconstruction quality.Since the narrow beam XLCT takes a long time to acquire the measurement data,we verified the feasibility of multi-narrow beam X-ray excitation luminescence tomography through simulation experiments in order to reduce the scanning time.However,it weakens the a priori position information,leading to a decrease in the quality of reconstructed images.Based on this,we propose a multi-narrow beam XLCT reconstruction method based on X-ray beam intensity-weighted modulation,which can effectively improve the image reconstruction quality by weakening the fluorescence intensity influence of other narrow beams to some narrow beam excitation.