A detector assembly 18 for an imaging system 10 is provided comprising a plurality of scintillator elements 50 positioned within a scintillator pack 56. The scintillator pack 56 forms a scintillator pack upper surface 58 and a plurality of scintillator pack walls 60 positioned between the plurality of scintillator elements 50. A plurality of collimator elements 64 are mounted on the scintillator pack upper surface 58. Each of the plurality of collimator elements 64 is comprised of a stack laminated base 66 mounted to the scintillator pack upper surface 58 and a cast upper wall 68 formed on the stack laminated base 66.