An imaging detector assembly is provided comprising a detector array and a scintillator assembly positioned in communication with the detector array. The imaging detector assembly further includes a first collimator array optimized to shield the scintillator assembly. The first collimator array is mounted to the scintillator assembly. The imaging detector assembly further includes a second collimator array optimized to reduce x-ray scatter. The second collimator array is mounted independently from the first collimator array.