Two- and three-dimensional reconstructions of doubly connected binary objects at finite numbers of projections and small observation angles

Computerized x-ray photography is the most common method for testing pipes and visualizing corrosion flaws, as well as being used for evaluating wall thickness based on variations of the optical density of a film along the pipe diameter. Errors of such estimates are 0.2-0.3 mm, but such errors must be reduced to 0.1 mm or less to serve the needs of modern industry. To upgrade the resuloution and accuracy of flaw location, low-aspect x-ray tomography can be used. To overcome the difficultry associated with teh large dimensionality of the inverse problem, we used original algorithms with shell representations of reconstructed objects. Shell methods for reconstruction of two- and three-dimensional doubly connected binary objects based on limited numbers of X-ray projections taken in small angles have been developed. (Example: stainless steel pipe.)