A detector assembly for a CT system includes a plurality of detector modules, each detector module including a grid of pixelated scintillators, a photodiode having pixelations that correspond with the pixelated scintillators, and an electronics package for processing acquired X-ray data, a support structure extending along a Z-direction of the CT system and having the plurality of detector modules positioned thereon, and a heat sink extending along the Z-direction and having the support structure mounted thereon, the heat sink including a passageway passing therethrough and along the Z-direction, such that cooling air may pass into the passageway at a first end of the heat sink and exit the passageway at a second end of the heat sink opposite the first end.