Non-intrusive inspection (NII) systems with high throughput are required for screening baggage, vehicles and cargo at ports of entry. Of the existing NII techniques, systems employing X-rays have undergone rapid evolution. Though well established, the probability of detecting contraband goods in the radiographic image obtained using conventional high energy X-ray systems depends on operator skill and orientation of the contraband material inside the container. Alternative techniques employing back and forward scattered X-rays operating at dual energy can only broadly classify objects containing contraband material and cannot be used to uniquely locate the contraband good. Limitations of X-ray radiography and scattererd imaging systems could be resolved using 2D tomography systems. But, the complexities associated with practical implementation of an X-ray CT system for screening baggage, vehicles and cargo is far from realization. This paper presents an X-ray imaging technique capable of providing 2D tomograms using limited-view projections as an ideal compromise for detecting packaged, vehicle-borne and human-borne explosives, weapons and contraband goods. Numerical simulations of the proposed system employing L-shaped detectors and iterative reconstruction algorithms indicate the feasibility of an alternate security screening system to detect and uniquely locate explosives and contraband goods concealed in cargo, baggage and vehicles.
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