Departmental Papers (CIS)

Date of this Version

June 1996

Document Type

Journal Article


Copyright 1996 IEEE. Reprinted from IEEE Transactions on Nuclear Science, Volume 43, Issue 3, June 1996, pages 1352-1356.

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NOTE: At the time of publication, the author was affiliated with Argonne National Laboratory. Currently March 2007, he is a faculty member of the Department of Computer and Information Sciences at the University of Pennsylvania.


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 2x2 cm, and five projection angles. For rectangular shaped explosives more angles are required to obtain the same system performance.



Date Posted: 26 March 2007

This document has been peer reviewed.