A High Energy Rapiscan Eagle Transmission X-ray system easily finds contraband, weapons, explosives, narcotics, currency and illegal goods.

The Great Debate

Reprinted from Cargo Security International July 2009

Peter Kant of Rapiscan Systems asks whether transmission x-ray or backscatter technology is best suited to protect the worlds ports and national borders.

National security issues are top priorities for governments around the world today. The United States government and its counterparts are actively developing strategies to eradicate crimes across borders and ensure the safety of citizens and troops. Terrorism threats, weapons of mass destruction (WMD), and explosives and narcotics smuggling are ubiquitous and ever evolving. Coupled with todays flow of commerce, cargo and vehicle screening needs to occur 24 hours a day, seven days a week. Such intensity requires advanced technology that readily moves goods through borders and check points, both on land and at sea.

Further, with the increasing sophistication and intelligence of terrorists and criminals, detection needs to be as flexible and effective as possible, regardless of where and how threats are concealed. At the centre of mitigating these threats are two inspection technologies backscatter and transmission x-ray. Both are x-ray based. Both have received significant media coverage. Both can help address security threats. However, as someone who provides both technologies to customers, I believe that, on balance, transmission x-ray is the best technology to use for the screening of cars, trucks and cargo containers for narcotics, weapons and other important threats. As the manufacturer of solutions that employ both technologies, Rapiscan Systems is well qualified to offer insight on both.

Applications and limitations

Backscatter x-rays reflect back to the direction they came from, capturing data from photons that are scattered from the object undergoing inspection. These photons scatter differently when they encounter different types of materials. The result is a clear, photo-like image.

Because backscatter x-rays do not fully penetrate objects, the rays are well suited for seeing objects just below a surface i.e. up to 10 millimetres (mm). The most promising application for backscatter x-ray technology today is people see objects underneath a persons clothes and emits low radiation. It has the ability to detect a wide range of threats metal, explosive, plastic or ceramic. Because of this, backscatter has been deployed successfully to screen people at aviation checkpoints, military bases, correctional facilities and border crossings around the world.

However, the same reason that backscatter x-ray is an appropriate solution for people screening seeing objects near the surface also makes it a poor choice for cargo screening. While the technology can discern objects close to the surface of a container or truck (such as in the door, wheel wells or hood), it cannot penetrate enough to detect objects hidden deeper in the cargo, particularly when they are concealed behind other objects. In fact, most of the cargo inside the truck or container is not examined. Because of this, it is possible to circumvent the technology by putting objects where backscatter cannot find them.

In 2004, this position was upheld globally. The World Customs Organization (WCO) issued guidance to its members via a report on container scanning equipment, stating: For drugs concealed in the fabric of a container, a systems with a backscatter facility (in which the rays do not penetrate into cargo but are scattered back from the walls) is beneficial, although it will have very limited ability apart from this.

High-energy Transmission X-ray

Only a transmission x-ray system can produce an image that shows everything inside, regardless of where the item is in the container and whether or not it is shielded by other objects. Using a transmission-based solution to screen cargo and containers results in a complete picture of the content, enabling inspectors to readily find contraband articles such as weapons, drugs, people, and explosives.

Unlike backscatter, transmission x-rays can penetrate up to 43 centimetres (cm) of steel, the highest level available in the market. Unlike its counterpart, it is also excellent at finding prohibited items inside liquids. Transmission x-rays also meet US Customs and Border Protection (CBP) Cargo Imaging Performance Specifications when tested per ANSI N42.46. Because of these features, this technology has become the preferred screening technology for ports, borders, military operations and other installations the world over.

For all these reasons, customers consistently chose transmission x-ray to secure their borders and ports.

Consider these facts:

• of the top 50 seaports worldwide, over 90% use transmission x-ray to screen cars, vehicles and cargo
• of the top US airports, over 90% use transmission x-ray to screen carry-on bags and air cargo
• transmission x-ray is the most widely deployed technology by US government agencies charged with protecting US borders.

To meet these market demands, Rapiscan Systems Eagle product line (available in mobile, gantry and fixed site configurations) was developed to inspect shipping containers and trucks for hidden contraband, including weapons, explosives, weapons of mass destruction, drugs and undeclared goods at seaports and land border crossing. The systems can produce a high-resolution image of a 40-foot equivalent unit (FEU) container in less than 30 seconds and reduce the need for time-consuming manual inspections. The company has deployed numerous units within the US and at other installations throughout the world.