Gamma-ray Radiographic Imaging

SAIC’s Vehicle and Cargo Inspection System (VACIS®) gamma ray imaging technology provides clear radiographic images (much like x-ray images) of containers, showing the
outlines and density of the contents. With its very low radiation dose, the VACIS scan is much safer than comparable x-ray systems. Over 170 VACIS units have been purchased by the US Government (Customs and Border Protection and the Defense Department)
and foreign customs agencies for use at cargo facilities around the world.
The principle of operation of VACIS is similar to that of a line-scan x-ray system; except, VACIS uses a gamma-emitting radioisotope. The source, consisting of a pellet a few mm in diameter, is collimated to project a fan-shaped beam onto a linear array of very sensitive NaI-photomultiplier scintillation gamma-ray detectors. The gamma-ray energies are 662 keV for cesium-137, and an average of 1253 keV for cobalt-60. The heart of all VACIS products is SAIC’s patented (U.S. patent number 6,507,025B1) high-efficiency photon-counting technology. Portal VACIS and Mobile VACIS have both been integrated with the Exploranium RPM. Unless mobility is required, the PortalVACIS is optimum for use in the integrated system. Following are brief descriptions of
each.