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 system that performs image reconstruction using the maximum likelihood algebraic reconstruction algorithm, a few number of projections, and relatively coarse projection and pixel resolution. This evaluation was done using receiver operator curves and simulated data from the fast-neutron transmission spectroscopy system operated in a mode to detect explosives in luggage. The results show that increasing the number of projection angles is more important than increasing the projection resolution, 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 2×2 cm, and five projection angles. For rectangular shaped explosives more angles are required to obtain the same system performance