A device for inspecting a cargo container such as a motor vehicle or freight pallet, with penetrating radiation. A source of penetrating radiation is mounted on a moveable bed, thereby allowing a beam of penetrating radiation to sweep the large container. At least one detector is also mounted on the bed, ether on the side of the source or on a boom, so that, as the beam is scanned across the container, the container and any contents of the container are characterized by transmitted or scattered radiation, or both.