Geometry Optimization And Experiment Study Of X-ray Luminescence Computed Tomography Imaging System

X-ray luminescence computed tomography(XLCT)is an emerging hybrid imaging modality which has the potentials for achieving both high sensitivity and spatial resolution simultaneously.The system utilizes X-ray excitation of phosphorescent nanoparticles to produce visible or near-infrared light,which are received by highly sensitive photosensitive detectors.The distribution of phosphorescent nanoparticles in the biological tissue is then recovered by optical image reconstruction.In this paper,we proposed two kinds of narrow beam XLCT scanning systems to study the spatial resolution and scanning efficiency separately.And the feasibility and effectiveness of the systems are verified by numerical simulations and phantom experiments.In terms of spatial resolution,based on previous work,the spatial resolution is generally considered to be determined by the x-ray beam width,taking step sizes equal to the beam width,and a spatial resolution of approximately twice the x-ray beam width can be achieved by using a collimated ultra-fine X-ray beam.In this paper,in order to break the current spatial resolution limit,we propose a new scanning strategy achieved by reducing the scanning step size to be smaller than the x-ray beam size.We performed numerical simulations and phantom experiments and have demonstrated that our proposed scanning method can greatly improve the XLCT reconstructed image quality compared with the traditional scanning approach.In our simulations,using a fixed x-ray beam size of 0.8 mm,we were able to successfully reconstruct 6 embedded targets as small as 0.5 mm in diameter and with the same edge-to-edge distances by using a scanning step as small as 0.2 mm which is a 1.6times improvement in the spatial resolution compared with the traditional approach.Lastly,the phantom experiment further demonstrated the efficacy of our proposed method in improving the XLCT image quality with all image quality metrics improving as the step size decreased.In addition,in terms of scanning efficiency,we presented an engineeringfeasible multi-narrow beam XLCT imaging system based on coded-aperture masks.And the simulation results show that the system can effectively improve the scanning efficiency while ensuring the quality of XLCT reconstruction.In this paper,we first studied the correlation between the single-element mask coding and the quality of XLCT reconstruction,and then extended to the multi-narrow beam XLCT imaging system based on two-element and three-element masks.And we evaluated the imaging quality to explore the general law.Considering the scanning time and system complexity,we also studied the influence of the number of projection angles and detection positions on the reconstructed image quality,and found that 80 projection angles and 4 detection positions can be obtained higher image quality by simulation experiments.And compared to the traditional narrow beam XLCT,our system does not require linear translation,only considers three-dimensional rotational scanning,which can effectively improve scanning efficiency.