When employing specular reflective material in a scintillator crystal array, light trapping in the crystal due to repetitive internal reflection is mitigated by roughening at least one side (16) of each of a plurality of pre-formed polished scintillator crystals. A specular reflector material (30) is applied (deposited, wrapped around, etc.) to the roughened crystals, which are arranged in an array. Each crystal array is coupled to a silicon photodetector (32) to form a detector array, which can be mounted in a detector for a functional scanner or the like.