Greedy projection access order for SART: Simultaneous algebraic reconstruction technique

Abstract

The projection access order in which the projections are used in the Simultaneous Algebraic Reconstruction Technique (SART) has great influence on the convergence rate and the quality of the reconstructed image. It is a well known fact that the correlation between the used projections should be as small as possible. Common methods achieve a small correlation based on the projection angles by applying special angle schemes. In this paper, we present a novel Greedy Projection Access Order (GPAO). GPAO is an angle-independent method, which is based on the structural information of the object itself. We create a projection-based information vector for each angle. By using the pairwise correlation of these vectors, a Greedy algorithm finds a short path through all projections. In this order the SART uses the projections to reconstruct the image. As the simulation results show, the performance of GPAO is similar to the performance of a random order. Advantageously, GPAO is robust and adapted to the object. Potentially, more complex path finding algorithms will show better results than the Greedy solution.