Applications of the energy-imaging integrated deconvolution algorithm for source chatracterization

The energy-imaging integrated deconvolution (EIID) algorithm is capable of deconvolving the source image at any specific energy, as well as the incident spectrum from any direction. This spectrum-image reconstruction method takes place in integrated spatial and energy domain using the maximum likelihood expectation maximization (MLEM) algorithm. This technique has been demonstrated for combined two-, three- and four-interaction Compton events from an array of 2 cm × 2 cm × 1.5 cm detectors in our previous work. By including Compton continuum events in the system model and using a sensitivity image to correct efficiency effects, the MLEM solution estimates the true incident gamma-ray spectrum with correct branching ratio. For each direction, we can then identify the source isotope based on the peak energy and relative peak area. After identifying the source isotope, the source activity can be estimated. From the reconstructed image and change of the relative peak areas from the branching ratio, the presence of shielding and the material and thickness of shielding can be estimated.