Model-Based Reconstruction of Spectral and Spatial Source Distribution for Objects With Known Motion

Radiation imaging has many applications ranging from health care to homeland security and defense, and source motion is present in many of these applications. When the motion profile of the source is known or otherwise estimated, one can use motion-compensation techniques to reduce blur in the reconstructed image. In this paper, we present a model-based source-intensity reconstruction in the energy and spatial domains using list-mode data. The model includes separate parameterization for objects moving with known motion that is independent of the stationary backdrop. This approach corrects for object motion without smearing stationary sources in the backdrop space. The goal is to simultaneously obtain an estimate of the incident energy and spatial distribution of the radiation field for the stationary backdrop and for each moving object. Experimental Compton-imaging results using an 18-detector array of 3-D-position-sensitive CdZnTe detectors show that the method can successfully reconstruct the source intensity of moving objects while also revealing stationary sources in the backdrop. Also, by modeling the possibility of partial photon energy deposition in the detector, the incident energy spectrum is reconstructed more accurately.