Theoretical determination of the collimator geometrical transfer function for the reconstruction of SPECT data

Iterative SPECT reconstruction algorithms allow for the inclusion of inform ation related to the geometric system response with accuracy and flexibilit y Since the experimental setup of a camera-collimator system may vary consi derably, it is necessary to fit the restoration potential of the algorithm to the actual acquisition conditions. In order to avoid any experimental pr ocedure, we developed a method to calculate weighting factors from the theo retical knowledge of the geometric system response of a multihole collimato r. The calculation of the weighting factors was based on an appropriate dis cretization of the Radon transform whose kernel was modified to describe th e variable system response of the collimator.