A CT system includes a rotatable gantry having, an x-ray tube having a focal spot, and a detector assembly positioned to receive the x-rays that pass through the object. The detector assembly includes an array of module support structures positioned along a channel direction, each module support structure having module support surfaces extending along the Z-axis, the array including a first module support structure and a second module support structure that are side-by-side, and a plurality of detector modules positioned on each module support structure and having collimating elements that are generally aligned toward the focal spot. Each of the first and second module support structures includes two steps symmetrically disposed along the Z-axis, such that a first gap between the detector modules of the first and second module support structures at a center of each is less than a second gap formed at each step.
