EVALUATION OF FEW-VIEW RECONSTRUCTION PARAMETERS FOR ILLICIT SUBSTANCE DETECTION USING FAST-NEUTRON TRANSMISSION SPECTROSCOPY

We have evaluated the performance of an illicit substance detection sy stem that performs image reconstruction using the Maximum Likelihood a lgebraic reconstruction algorithm, a few number of projections, and re latively coarse projection and pixel resolution. This evaluation was d one using receiver operator curves and simulated data from the fast-ne utron transmission spectroscopy system operated in a mode to detect ex plosives in luggage. The results show that increasing the number of pr ojection angles is more important than increasing the projection resol ution, the reconstructed pixel resolution, or the number of iterations in the Maximum Likelihood algorithm. A 100% detection efficiency with essentially no false positives is possible for a square block of RDX explosive, a projection resolution of 2 cm, a reconstructed pixel size of 2x2 cm, and five projection angles. For rectangular shaped explosi ves more angles are required to obtain the same system performance.