Non-stationary filtering technique for improved cone beam SPECT

A truly 3-D reconstruction formulation is derived for the single-orbit cone beam SPECT (single photon emission computed tomography) based on the 3-D Fourier slice theorem. In the formulation, a nonstationary filter is derived which depends on the distance from the central plane of the cone beam. This filter is applied to the 2-D projection data in directions along and normal to the axis of rotation. The nonstationary filtering technique was evaluated using both computer simulation and phantom measurements. Significant improvement in image quality was demonstrated in terms of decreased artifacts along the axis of rotation at the cost of a fivefold increase in processing time. The quality of the reconstructed image from the 3-D algorithm is superior to that from the Feldkamp algorithm, especially near the ends of the image along the axis of rotation.<>