Simulation is a valuable tool for designing and evaluating the performance of x-ray imaging systems. In previous work, a hybrid CT+XRD imaging system was developed for improved identification of threat objects in checked baggage. Through large-scale simulations of this hybrid CT+XRD system, we can investigate the impact of various parameters on system performance. These parameters include varying energy resolution, multi-energy acquisitions, and additional system views. We will report on our findings and evaluate the system performance resulting from these and other variations of the simulated system as well as discuss how these findings may inform future system design.
X-ray coherent scatter yields a weak signal relative to X-ray transmission leading to a challenging reconstruction problem of estimating the scatter spectrum of a material. Here we consider the estimation problem of recovering the spatial mapping of the X-ray coherent scatter spectrum using a spatially modulated (coded-aperture) fan-beam illumination and angle dispersive measurements. We demonstrate that by using both spatial and spectral regularization, within a Bayesian inference framework, we can improve the fidelity of the recovered scatter spectrum from relatively weak scatter measurements. More specifically, in this work we validate this reconstruction performance using experimental measurements obtained from a dual modality X-ray transmission and scatter system. We quantify the reconstruction fidelity our technique relative to maximum-likelihood and group-TV reconstruction techniques.
Aviation security, mail inspection, medical diagnostics and many other industries all face the same challenge: to accurately identify the presence of a target material concealed within a cluttered surrounding environment. X-ray systems that combine transmission and diffraction measurements promise excellent detection performance with low false alarm rates; however, conventional approaches to combining these measurements typically under-utilize the available information and result in higher overall system resource costs. Here, we consider a fully integrated approach to hybrid X-ray transmission and diffraction systems and discuss simulation- and experimental-based investigations of the design and performance (both imaging and detection) of such systems. Based on this analysis, we describe a hybrid system capable of scanning boxes and/or luggage and report its ability to distinguish materials of interest to aviation security and pharmaceutical inspection.
A passively illuminated scene presents a variety of photon pathways: direct and indirect, which convey varying levels of information about the scene across different dimensions of the light field. In indirect passive imaging, the object of interest is occluded from the imager which has no control over illumination. Using a second-order (non-linear) image formation model we demonstrate (experimentally) the feasibility of passive indirect diffuse imaging.
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