A collimator includes an x-ray blocking surface including one or more generally flat plates defining an aperture edge. The aperture edge includes a first end portion including a first end of the aperture edge, a second end portion including a second end of the aperture edge, and a central portion including a center of the aperture edge. The first end portion of the aperture edge corresponds to a first end portion of a detector, the second end portion of the aperture edge corresponds to a second end portion of the detector, and the central portion of the aperture edge corresponds to a central portion of the detector. A profile of the aperture edge is discontinuous at a point between the first end of the aperture edge and the center of the aperture edge.