A system and method for inspecting a vehicle by means of one or more sources and detectors of penetrating radiation. The source(s) and detector(s) are carried on a mobile conveyance and deployed at a point of operation. One source swings away from the conveyance on a deployable member, such as a boom, such that the source can irradiate a vehicle from above or below. A detector deploys outwardly from the mobile conveyance, remaining mechanically coupled to the mobile conveyance in a position in a horizontal plane, such that the detector intercepts penetrating radiation from the source positioned above the inspected vehicle, which penetrating radiation has interacted with the inspected vehicle. A ramp may be provided to allow the inspected vehicle to be driven to a position between the vertically irradiating source and a transmission detector.