A new anti-aliased projection operator for iterative CT reconstruction

A new projection operator is presented and evaluated. This operator has been designed to suppress aliasing artifacts due to (i) false high frequencies contained in the footprint function, and (ii) high frequencies caused by a divergent beam geometry. It is easy to implement and allows for efficient computer implementations. Instead of sampling the footprint as done in most projection operators, the footprint is integrated. This integration suppresses false high frequencies, frequency components that cause aliasing and approximately takes into account the finite size of focus and detector. Two-dimensional parallel beam experiments are presented. These experiments confirm that artifacts due to false high frequencies can be suppressed by the proposed technique. In order to investigate the advantages for divergent beam geometries, current experiments must be complemented with cone-beam experiments.