ALGEBRAIC RECONSTRUCTION TECHNIQUES CAN BE MADE COMPUTATIONALLY EFFICIENT

Algebraic reconstruction techniques (ART) are iterative procedures for recovering objects from their projections. It is claimed in this pape r that by a careful adjustment of the order in which the collected dat a are accessed during the reconstruction procedure and of the so-calle d ''relaxation parameters'' that are to be chosen in an algebraic reco nstruction technique, ART can produce high-quality reconstructions wit h excellent computational efficiency. We demonstrate this by showing, on an example based on a particular (but realistic) medical imaging ta sk, that ART can match the performance of the standard EM approach for maximizing likelihood (from the point of view of that particular medi cal task), but at an order of magnitude less computational cost.