The invention relates to a radiation detector for detecting radiation impinging in a detection zone, having detector elements which are arranged in the form of a preferably two-dimensional array in rows and columns running orthogonally with respect to one another and each have a scintillator and a photodiode interacting with the latter. In this case, detector elements arranged at the edge of array are provided, whose scintillators have an extent transversely with respect to the edge of the array which is larger than is necessary for encompassing the detection zone.