With increasing concerns regarding border and port security, the Canada Border Services Agency (CBSA) and the US Customs Service (USCS) are using radiographic cargo inspection systems to screen commercial trucks and cargo containers for contraband or other threats. While there are a number of radiographic cargo inspection systems on the market, CBSA and USCS are using the Vehicle and Cargo Inspection System (VACIS^®), a technology developed and offered by Science Application International Corporation (SAIC).

The Canadian Nuclear Safety Commission (CNSC) has licensed the Canada Border Services Agency for the use of several mobile radiographic cargo inspection units.  The  systems are being used at land border crossings, marine ports and international airports throughout the country.

What is a radiographic cargo inspection system?

To verify cargo contents, the system scans vehicles to reveal undeclared dangerous goods and contraband. In the case of VACIS, a cesium137 or cobalt 60 sealed source is utilized to generate gamma rays which penetrate the cargo being inspected, similar to X-ray based systems. The gamma rays are emitted from a small radioactive pellet with an electronically controlled shutter. The rays penetrate material as they pass through the vehicle and are measured with a detector. A computer then generates an image of the interior of the vehicle. The inspection takes from one to three minutes.

Safety and Protection

Radiographic cargo inspection systems require a small amount of protection (called 'localized shielding') to minimize exposure and maintain protection. Operators are trained in radiation safety and they wear a badge (dosimeter) to measure any radiation exposure. To date, the dosimeters have indicated that Canadian operators have received very little or no dose associated with the operation of VACIS.

In the case of land border crossings, the CBSA requires the driver and any passengers to exit the vehicle and move to a safe area before scanning begins. The system operator then moves the mobile unit in position and scans the vehicle. Another procedure that may be used allows the driver to remain in the vehicle; however, the driver is positioned beyond the gamma ray scanning beam path. The system operator moves the mobile unit and scans only the container/cargo portion of the vehicle.

A study was conducted by British Columbia’s Radiation Protection Services to determine if the scanning of the trucks has caused any appreciable radiation dose to Canadian drivers. The results indicate that, similar to the system operators, the drivers have received very little or no dose associated with VACIS. Given the measured levels of exposure, drivers and operators will not be likely to experience any health impact due to the scanning procedure.