American Science & Engineering’s (AS&E) relocatable, drive-through Sentry Portal system uses a high-energy X-ray transmission source that allows for the high-throughput, rapid screening of cargo for security threats and contraband. This high-penetration system enables thorough inspection of even densely-loaded cargo containers at up to 12 inches (300 mm) of steel. The system features an advanced cargo sensing subsystem that begins scanning only after the cab has passed to maintain a safe environment and the extremely low scattered radiation dose means the system is safe for all drivers and operators. The system also features a compact footprint allowing for installation in areas with space constraints. In addition to operating with AS&E’s Z Portal System, the Sentry Portal system can be integrated with radiation detection, container identification, and license plate reading systems.