1. A collimator for a SPECT system, the collimator being configured for absorbing and collimating gamma rays emitted by a radiation source within a field of view of the collimator, said collimator having an alignment direction for directing along a longitudinal axis of a measuring cavity of the SPECT system, said collimator comprising at least one collimator body formed as a continuous block of radiation absorbing material, the collimator body comprising a plurality of apertures, the plurality of apertures being arranged in a plurality of groups separated from each other in said alignment direction, wherein the apertures of each group are oriented such as to define at least one projection view along a corresponding at least one projection direction, and wherein 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.