Difference image reconstruction from a few projections for nondestructive materials inspection

An image reconstruction algorithm is defined for nondesructive testing of solid objects using computer aided tomography (CAT) when a limited data set is available. The situation is of interest in cases when the number of scans which can be performed is constrained by the geometry of the configuration being scanned. The method involves a difference algorithm, wherein the analysis is carried out pixel by pixel, with the primary image being one of a standard cross section. Projections are calculated for the imaged object and subtracted from the ideal object. An image of the difference is then obtained by a backprojection technique, which reveals regions of densities deviating from those of the standard projection. Error reduction methods are defined, and sample images are provided from scans of a fuel pin array.