Analytical compensation for spatially variant detector response in SPECT with varying focal-length fan-beam collimators

The authors present a new method to compensate for the spatially variant detector response in single photon emission computed tomography (SPECT) with varying focal-length fan-beam (VFF) geometry. In this method, the deblurred projection is explicitly expressed as an integral of the collimator blurred data and the fully calibrated system kernel matrix with certain transforms. It needs a little more computation time than the conventional filtering techniques but provides much more accurate compensation. This method also represents a unified framework for detector response compensation in parallel-hole fan-beam and VFF SPECT with a circular scan orbit.