Comparison of an analytical and an iterative based collimator-detector response compensation method in SPECT

This study compares two collimator-detector response (CDR) compensation methods in SPECT; an analytical method by Pan et al. (1997), and an iterative method which accurately models the CDR. The spatial resolution recovery is evaluated using simulated data of a point source placed at different distances from the center-of-rotation of the camera. The image noise properties are evaluated using simulated data from a uniform disk phantom. The two methods provide general improvement in spatial resolution but generate reconstructed point source images showing different asymmetric shapes. The analytical method is fast but assumes CDR characteristics that are not fully met in practice. It amplifies high frequency noise drastically. To reduce the noise level, a smoothing filter is used with concurrent degradation in resolution. The iterative method is much slower but achieves improved spatial resolution with lower noise in the reconstructed images. We conclude that the iterative method provides more accurate CDR compensation and lower image noise as compared with the analytical method at a cost of a longer computation time.