On two versions of a 3-pi algorithm for spiral CT

Abstract

A 3pi algorithm is obtained in which all the derivatives are confined to a detector array. Distance weighting of backprojection coefficients of the algorithm is studied. A numerical experiment indicates that avoiding differentiation along the source trajectory improves spatial resolution. Another numerical experiment shows that the terms depending on the non-standard distance weighting l/[x - y (s)] can no longer be ignored.