Portal VACIS

Portal VACIS™ is a high-throughput imaging system for port gates and
roadways and provides a quick and effective tool to detect high-value stolen
goods before they leave the country, or illegal materials smuggled into the
country. Engineered to operate in very small areas, Portal VACIS can be deployed
in conjunction with existing vehicle control points, such as weigh scales, and
provides permanent protection to port gates and roadways. Figure 2 shows the
geometry of Portal VACIS which uses two opposing sources and detector arrays
which facilitate imaging an entire container or truck without requiring sourcedetector
separation distances greater than the width of a standard road lane. Thus,
Portal VACIS units can be installed on adjacent multiple lanes. The prototype
Portal VACIS used to verify that “empty” trucks entering Mexico were indeed
empty is also shown in Figure 2. Figure 3 shows two Portal VACIS units installed
on adjacent traffic lanes at the Mexican seaport of Manzanillo. Portal VACIS can
scan at speeds up to 8 km/hr allowing it to be used in tandem with a RPM in the
integrated system without impeding the flow of vehicles. The gamma beams are
shuttered off as the tractor passes the area of the beams. Once the tractor and
driver have cleared the beam area, fast-a
cting shutters open to allow imaging ofthe container (being pulled through on a chassis) or cargo portion of a truck. The speed of the vehicle during the scan is monitored by a radar gun and used to correct the image distortion resulting from variable speed during a scan. The tight collimation of the gamma beams ensures that the driver receives no radiation dose. A stowaway in a scanned container would receive less than 5 microrem (0.05 microSeiverts), equivalent to about 15 minutes of natural background radiation at sea-level. A VACIS average radiation dose to cargo is more than an order of magnitude less than the lowest dose 450 kV x-ray system and about three orders of magnitude less than that of a 2 to 6 MeV x-ray system.(1)