Abstract: A calibration method for calibrating at least one gamma radiation detector includes a monolithic scintillation crystal. The calibration method comprises obtaining event data for a plurality of scintillation events. The event data for each scintillation event includes a plurality of location sensitive signals observed by the at least one gamma radiation detector to be calibrated, applying an unsupervised learning algorithm to embed the event data on a low-dimensional manifold, and obtaining calibration data considering the low-dimensional manifold embedding.

Abstract: A collimator for a SPECT system, the collimator being adapted for absorbing and collimating gamma rays emitted by a radiation source within a field of view the collimator, said collimator having an alignment direction for directing along a longitudinal axis of a measuring cavity of the SPECT system and said collimator comprising at least one collimator body of radiation absorbing material, the collimator body comprising a plurality of apertures being formed in the collimator body, the plurality of apertures being arranged in a plurality of groups separated from each other in said alignment direction. The apertures of each group are oriented such as to define at least one projection view along a corresponding at least one projection direction. The plurality of said projection directions corresponding to each and every of said plurality of groups cover an angular range sufficiently large for sufficient image information for artifact-free reconstruction.