Systems and methods for scanning with radiation detectors are provided. One system includes at least one radiation scanning camera-head, an array of at least one pixelated radiation detector having an imaging surface including a two dimensional array of pixels, and a scanning unit positioned between the radiation detector and the object. The scanning unit includes first and second radiation blocking plates having first and second two-dimensional arrays of openings, respectively, wherein the array of pixels and the first and second arrays of openings have a same pitch. Additionally, for each of a plurality of scan positions of the scanning unit, the first and second moveable plates and the imaging surface are positioned differently with respect to each other to produce different inclination angles in response to each scan position.