An imaging system and detector for obtaining x-ray images of a region of interest (ROI) within an object is provided that does not require movement of the detector and/or object/patient for alignment with the x-ray source. The detector is formed with an array of detector elements disposed on a substrate that has an area larger than the area of the objects/patients to be imaged. In use, the object/patient is positioned between the x-ray source and the detector and the x-ray source is targeted at the ROI. The control mechanism determines the area of the detector aligned with the x-ray source and ROI and operates the selected detector elements in the area struck by the x-rays from the source passing through the ROI of the object/patient. The control mechanism receives image data from the area of the detector formed by the detector elements in order to form images of the ROI.