Imaging detectors and methods of manufacturing are provided. One imaging detector includes a first detector layer within a detector module and a second detector layer within the detector module and spaced apart from the first detector layer, wherein the second detector layer has an opening therethrough. The imaging detector also includes a collimator mounted to the detector module, wherein the collimator is one of a single pinhole collimator or a multi-pinhole collimator. Additionally, the second detector layer is mounted within the detector module closer to an opening of the collimator than the first detector layer.