Portal VACIS® Inspection System

Frequently Asked Questions

What is the VACIS® inspection system, and how does it work?

SAIC’s VACIS inspection system is a gamma ray based system designed to non-intrusively inspect the contents of trucks, containers, and cargo for contraband. VACIS systems generate gamma rays from either a cesium or cobalt source housed in a container called the source holder, which emits a narrow, vertical fan beam directed at a highly sensitive detector array. As the fan beam penetrates a moving or stationary object, the detector counts the particles passing through the object and transmits these readings to a computer. Using the readings from the detector array, the computer generates a high-resolution image, similar to an x-ray, of the inspected object. SAIC’s custom-designed software allows trained operators to analyze this image to determine whether the contents of the evaluated object require further inspection.

What is the difference between using x-ray and gamma ray radiation for cargo inspection?

All non-intrusive cargo inspection systems use some form of penetrating radiation in order to produce an image of the internal contents of a sealed truck, intermodal container, private vehicle, air cargo container, etc. The VACIS inspection system utilizes a cesium-137 or cobalt-60 radioisotope (depending on configuration) to generate gamma rays, which penetrate the cargo being inspected. This is similar to x-ray cargo inspection systems, which use x-rays for this purpose. The method of creation is different: x-rays are electromechanically generated when needed for inspection, while gamma rays continually emit from a small radioisotope pellet, which is equipped with a shutter to briefly open the source enclosure when inspection is required. The gamma source offers greater reliability and a lower cost of ownership because it does not require a complicated, high-voltage electrical system to create the radiation.

Gamma ray systems typically use radiation of just one or two discrete energy levels in the range 0.6 to 1.3 MeV. In contrast, x-ray systems typically use radiation with a broader spectrum of energy levels in the range 0.5 to 9 MeV, produced by a linear accelerator (“linac”) or other electromechanical device. Other than these differences, the two types of radiation are essentially the same.

How much material can the VACIS® inspection system penetrate?

Material penetration by radiation (x-ray or gamma) does not necessarily indicate the level of image quality that will be displayed in an image. Once the radiation has penetrated a certain thickness of material, a detector must accurately measure it, and those signal values are then converted into an image the operator can view. This is where the VACIS inspection system provides exceptional efficiency, even using low-intensity doses of radiation. The VACIS inspection system maximizes the image penetration for a given system spatial resolution and scan speed with its mono-energetic gamma beams.

Penetration figures are often given in levels of steel, aluminum or other metals. In the case of the VACIS inspection systems, equipped with a Cobalt-60 source, a maximum thickness of 6.25 inches (159 mm) of steel can be penetrated while maintaining the rated contrast sensitivity. This makes the VACIS system ideal for use in the inspection of cargo containers.

How many configurations of the VACIS® inspection system are there?

SAIC offers five configurations of the VACIS® inspection system, all utilizing SAIC's patented gamma ray technology:

• The Mobile VACIS system is a truck-mounted version that is being used to inspect the contents of trucks, containers, cargo, and passenger vehicles.

• The Relocatable VACIS system is a track-and-trolley based system used to inspect sea containers, trucks, and other vehicles.

• The Railroad VACIS system is currently the only available solution for non-intrusive inspection of loaded and moving railroad cars. The Railroad VACIS system is unique in its ability to inspect any size train traveling at speeds up to 10 miles per hour.

• The Portal VACIS system consists of a high-throughput system for port gates and roadways. Engineered to operate in very small areas, the Portal VACIS system can be deployed in conjunction with existing vehicle control points, such as weigh scales.

• The Pallet VACIS system is a self-contained gamma ray based imaging system, with a small footprint, designed to quickly image pallets or pallet-sized containers.

How long has SAIC been involved with producing VACIS® systems?

SAIC has produced VACIS systems for more than 10 years. SAIC has developed and manufactured similar devices for over 20 years.

How many VACIS systems have installed or ordered?

As of April 2005, over 290 VACIS systems have been sold. VACIS systems lead all competitors in unit sales of cargo container inspection systems with comparable penetration capability.

Where are VACIS systems installed?

VACIS systems are used throughout the world—30 units have been sold to Mexico, 15 to Canada, 10 to Central America, 10 to Europe, 14 to Asia, and 50 to the Middle East as of April 2005. There are over 160 VACIS systems in use in the U.S.

What is the scanning speed (throughput) of VACIS® systems?

Railroad VACIS systems can inspect trains of any length at speeds between 1 and 8 mph (1.6 and 12.9 km/h) with maintaining 5.25 in. (133 mm) penetration of steel.

Mobile and Portal VACIS systems are designed to maintain 6.0 to 6.25 in. (152 to 159 mm) penetration of steel at a scan speed of about 2 mph (3 km/h). This equals slightly less than 3 ft/sec (0.9 m/sec), which means they can scan a 40-foot (12.2-m) cargo container about every 15 seconds. This is sufficient to support processing, including truck entry, exit and image analysis, of up to 90 trucks towing 40-ft. (12.2-m) cargo container trailers per hour.

Relocatable VACIS systems typically scan at a rate of about 1 ft/sec (30 cm/sec), allowing for full inspection of a 40 ft. (12.2 m) container in less than one minute, or up to 60 such containers per hour. And Pallet VACIS systems quickly examine fully loaded pallets or pallet-sized containers via a conveyor mechanism that continually moves cargo through the system.

It should be noted that typical processing time may increase in times of high alert or depending on the specific inspection mission. Even so, it is important to compare typical VACIS system processing time to manual inspections, which could take several hours. The VACIS system has a quantifiably positive effect on cargo inspections because it is designed with the goal of minimal impact to overall operations.

The VACIS® system uses a radioactive isotope. Is it dangerous?

Radiation is always a concern, whether from an x-ray device or gamma ray system. When following the manufacturer's operational guidelines, SAIC’s VACIS systems can provide cargo images using such low radiation doses that no additional shielding is required to meet U.S. Nuclear Regulatory Commission (NRC) requirements per the Sealed Source and Device Registry. This is because the VACIS system’s gamma ray technology allows for cargo imaging with a smaller dose of radiation compared to normal x-ray technology.

Far from being “dangerous,” gamma rays have many beneficial industrial uses, such as moisture gauges, leveling gauges, thickness gauges, aircraft defect checking, well logging devices, cold pasteurization of food, liquid flow measurement and control, fill-level verification, and durability hardening of wood and plastic composites for commercial flooring. Gamma rays, like x-rays, also have significant beneficial medical applications.

What is the VACIS® system’s radiation dose per scan?

VACIS gamma ray cargo inspection systems typically impart about 0.02 mrem (0.0002 mSv) or less radiation per scan (at the centerline of the container being scanned). But just how much radiation is this? Here are a few comparisons with common real-world events:

• A VACIS system scan is equal to the amount of radiation a passenger in an airplane flying at 30,000 ft. (about 10,000 m) receives in one minute.

• A typical dental x-ray produces about 6 mrem (0.06 mSv), which is 300 times more than the dose imparted by a VACIS system scan.

• A typical lung x-ray produces about 15 mrem (0.15 mSv), which is 750 times more than the dose imparted by a VACIS system scan.

• A typical lower intestinal x-ray produces about 400 mrem (or 4 mSv), which is 20,000 times more than the dose imparted by a VACIS system scan.

• Even consuming three bananas, which are mildly radioactive due to the Potassium-40 they contain, would impart nearly as much radiation (about 0.018 mrem, or 0.00018 mSv) to a person as would a VACIS system scan.

• In order for the radiation dose given to an inadvertently scanned stowaway to reach the annual radiation exposure limit of 100 mrem (1 mSv) set by the U.S. Nuclear Regulatory Commission, he or she would have to be scanned 5,000 times by a VACIS system.

Are VACIS® systems safe for inspecting food?

Gamma radiation is already routinely used in the production, processing, and handling of food. The radiation sources used in VACIS systems contain from 1 to 2 Curies of radioactive isotope. Radiation sources currently used in modern food sterilization (cold pasteurization) systems contain as much as several million Curies of material. VACIS systems are therefore safe for inspection of food. Furthermore, at the energies used for cargo container inspection, gamma rays leave behind no residual radiation in inspected items—they are simply not powerful enough.

What are some benefits of SAIC’s VACIS® system gamma ray technology?

VACIS systems offer innovative, cost-effective solutions for non-intrusive inspection of everything from intermodal containers to passenger vehicles. Benefits include:

• Cost of ownership—Because VACIS systems are simpler and have fewer critical parts than comparable x-ray systems, they are more rugged and cost less to maintain. This allows VACIS systems to achieve very high system availability, typically 98% or more.

• Maximum flexibility—VACIS systems are offered in five configurations to meet almost any inspection requirement or scenario.

• Low radiation dose—The VACIS system’s radiation dose per scan is a fraction of the dose emitted by comparable x-ray systems. This allows VACIS systems to be operated without additional shielding while still meeting NRC requirements per the Sealed Source and Device Registry.

• High reliability—VACIS systems are built and tested to help ensure continuous operation in extreme weather conditions.

• Easy to maintain—VACIS systems’ simple, modular design and minimal moving parts streamline maintenance and repair operations and promote higher overall availability.

• High throughput—VACIS systems can scan 40 ft. cargo containers in under 10 seconds, and can inspect trains traveling up to 10 miles per hour.

• Comprehensive training and support—Whether it’s around-the-clock technical support, in-depth operator training or maintenance certification programs, SAIC provides exceptional customer support.