A mobile scanning system and methods for inspecting contents of a container. Multiple detector plates are arrayed along an arcuate member coupled to a conveyance with wheels, capable of road travel. A source generates high-energy penetrating radiation that irradiates each of the detector plates from a single position. The arcuate member is disposed, during the course of operation of the system, in a vertical plane. The system has one actuator for rotating the arcuate member about a horizontal pivot into a horizontal plane, and a second actuator for further rotating the arcuate member, once rotated into the horizontal plane, about a vertical pivot, so that the arcuate member is contained, for purposes of transport, entirely within a volume defined by a rectangular prism that does not extend horizontally outward from the conveyance beyond any of its wheels.