A radiation detector, in particular a gamma camera, is constructed and operated
in such a fashion that only a predetermined number of light sensors (such as PMT's)
adjoining each other in a cluster are used to generate a signal with amplitude
and event position information. The camera may also use an array of individual
scintillation elements (crystals) in place of a single crystal, with certain advantages
obtained thereby. According to another aspect of the invention, there is a reflector
sheet that defines an array of apertures through which scintillation light can
pass from the scintillation crystal to a plurality of light sensors optically coupled
to an optical window in an array corresponding to the array of apertures in the reflector.
