A radiation detector (10, 10′) includes scintillator pixels (30) that each have a radiation-receiving end, a light-output end, and reflective sides extending therebetween. The reflective sides have a reflection characteristic (40, 40′, 41, 44) varying between the radiation-receiving end and the light-output end such that a lateral spread of light emanating from the light-output ends of the scintillator pixels responsive to a scintillation event generated in one of the scintillator pixels depends upon a depth of the scintillation event in the scintillator pixel. A plurality of light detectors (46) optically communicate with the light-output ends of the scintillator pixels to receive light produced by scintillation events.