COLUMN-RELAXED ALGEBRAIC RECONSTRUCTION ALGORITHM FOR TOMOGRAPHY WITHNOISY DATA

A tomographic reconstruction algorithm similar to the well-known algeb raic reconstruction technique (ART) is presented. Similar to ART, the approximate algebraic reconstruction technique (AART) technique consis ts of a sequence of displacements of the image vector based on the pro jection error. AART is a column-relaxation technique that is a series of vector displacements of the image vector parallel to its coordinate axes. AART is compared with ART, a standard conjugate-gradient techni que, and a conjugate-gradient technique augmented by nonnegativity. Th e use of relaxation parameters to improve the performance of both ART and AART in the presence of noise is discussed, and the use of an iter ation termination criterion based on random generalized cross validati on is illustrated.