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Cargo Inspection: Imaging Solutions Wait for Government's Call
by Winn Hardin, Contributing Editor - AIA Posted 12/13/2002
Financial losses to the US following the terrorist attack of September 2001 were estimated at more than $100 billion by mid-November 2001. To put that money in perspective, the annual budget for the new Homeland Security Department with its 170,000 employees – including the new army of federal baggage inspectors -- is only $40 billion per year. Interestingly, given their cost, only a fraction of the losses endured after 9-11 would put advanced explosives detection systems and improved computed tomography x ray machines in every airport in the US, put marshals on every plane, and security at every gate, greatly reducing the threat of someone using hijacked airplanes as weapons of mass destruction (WMD).
Today, a potential war with Iraq has made WMD a household acronym, but has the US learned from its past mistakes? Results from a new terrorist ‘war game’ reported in the The Wall Street Journal’s December 4th edition cast a questionable pall over the US’ ‘homeland security.’ The simulation centers on the coordinated shipping of several dirty bombs, essentially a pile of C4 plastique and the radioactive isotope Cesium 137, to US ports. Under the scenario, some bombs are discovered, while one blows up in Chicago. The threat and explosion closes the US ports on two occasions putting shipping and transportation interests three months behind, crushing supply chains across US industry and costing the country some $58 billion.
Despite widely available tried-and-true cargo inspection techniques and imaging systems, the US has made relatively little progress adding non-destructive cargo inspection systems to its network of 185 deep-water ports. (The US has some 365 river and seaports, with about 40 of those making up some 80 percent of the cargo flow.) Cost is often cited as the reason for the lack of deployment, but only by the short sighted. Some 200 million intermodal cargo containers carry an estimated $12.5 trillion in cargo by ship, rail and truck each year. Today, only 2 percent or of cargo containers are inspected at US ports, and of those inspected, the containers’ contents match the manifest only about 30 percent of the time.
US moves forward
Although progress has moved slowly on cargo inspection, the US has some successes. The Congress recently passed the Hollings bill, which mandates tighter controls and cargo inspection levels at US borders and ports. Unfortunately, the bill includes limited funding provisions, including $90 million to investigate cargo inspection systems and a $200 million increase in the US Coast Guard’s budget for intercepting and monitoring cargo vessels. Experts estimate that fielding the necessary cargo inspection systems will cost billions more, most of which will have to come from the government since a fee based inspection process was struck from the Hollings bill before it passed Congress.
In the meantime, companies that provide cargo screening equipment are busy educating government agencies and waiting for official system specifications, such as what spatial resolution and throughput are required for a particular border crossing and port, should the system be fully automated, what role will the operator play and what types of materials should the system be able to detect?
‘‘In many ways, parts on a manufacturing line are just like cargo and vehicles on the roadways. You can’t slow the system down for inspection, just like in manufacturing. The biggest impact of terrorism is economic, so the impact of product flow is a key issue just as it is for vision systems in a manufacturing plant,’‘ said Computer Recognition Systems Ltd. (Cambridge, MA), president Salvatore D’Agostino. CRS provides vehicle tracking systems and a GUI front end through its AVISTA product that can incorporate a variety of hazardous material sensors, depending on the location (border, building or port).
A typical sensor supplier might be L3 Communications (New York City), which offers a series of inspection systems from 150 keV to several MeV systems. ‘‘There’s a big discussion right now on cargo inspection in the US to determine what is suitable and what is not. People may want a 150 keV system to inspect a 4x4 pallet. That’s OK if you just want to wave your hand at inspection. But if you want to do the inspection properly, you need to match the equipment to the application and that’s where the US is right now,’‘ explained John Avolio, director of cargo, aviation and government affairs at L3 Communications. ‘‘A lot of stuff has been done outside the US in the cargo and high-energy inspection area that hasn’t been done here. There are a lot of lessons that could be learned and that’s why companies are working with government agencies to go visit overseas locations.’‘
Cargo imaging inspection systems fall into two modalities, x-ray and gamma ray. X-ray sources split into two main types, tube sources and linear accelerators. ‘‘One mega-electron volt is pretty much the cutoff for X-ray tubes,’‘ said L3’s Avolio. L3 offers several systems using x ray tubes, including a 160 keV, 320 keV and 450 keV. The 450 keV system is the beginning of L3’s mobile cargo inspection systems. Avolio claims the 450 keV system delivers 4 inches of steel penetration. To put that in perspective, most intermodal cargo containers are made 1/8’‘ steel, so 4’‘ would seem more than adequate for any inspection.
‘‘The answer to the question, what is the minimum power for cargo inspection is, ‘it depends,’’‘ said BIR’s vice president of business development, Dan Bundy. ‘‘Checking empty containers to make sure they are indeed empty before returning them is a good application for lower energy systems. You don’t need high energy to see that…In the case of our systems, where the content is varied and densely packed, you really need – in our opinion – a floor of 6 MeV.’‘ Today, vendors are working with US agencies to change educated opinions into national standards.
In addition to the fixed cargo inspection facilities in Japan, BIR is developing mobile systems that can move within a single port or border facility, and can be moved between ports and different borders, and larger, relocatable systems that can be easily redeployed at different locations. ‘‘Mobility is a requirement for a few general reasons: cost, because not every port system can purchase their own system, so some ports may share a system,’‘ said Bundy. ‘‘Another reason is real estate. It’s difficult to get a commitment on one area in a port for a dedicated facility for scanning.’‘
US customs has recently agreed to purchase eight of Aracor’s EAGLE 6 MeV mobile systems for cargo inspection, saying that its compromise of penetration and radiation safety will enable it to penetrate and inspect up to 98 percent of cargo containers entering the US.
Both of BIR’s proposed systems will operate in the 6 MeV range, according to Bundy. Other companies with comparable product offerings include L3, OSI (Hawthorne, CA), Aracor (Sunnyvale, CA), Heimann Systems (Wiesbaden, Germany) and others. These systems all use linear accelerators as the x-ray source, typically from Varian (Las Vegas).
Radioactive isotope exposes nuclear threats
Science Applications International Corp. (SAIC, San Diego, CA) offers a less expensive system that uses Cesium 137 or Cobalt 60 radioactive isotopes to generate gamma rays that penetrate the cargo container. Because of the few number of photons generated by an isotope, these systems use special arrays of photomultiplier tubes rather than arrays of photodiodes as the x-ray systems do. The photomultiplier tubes are larger than the photodiode arrays, and so the spatial resolution is reduced, from a maximum of 9 mm for the gamma ray system compared to around 2 mm for x-ray systems. Gamma rays also penetrate approximately 6.25’‘ of steel compared to up to 12 inches for high-energy x-ray systems. This can translate to throughputs of 1 foot per second for high-energy x-ray systems at maximum resolution compared to 1 inch per second for SAIC’s relocatable isotope-based gamma ray systems
On the plus side, SAIC’s isotope based systems require a fraction of the shielding required by linear accelerator-based systems. Cargo inspection systems operating at 6 MeV and above require many tons of shielding around the source and detector at considerable cost, which can increase system costs by a factor of two or more and preclude truly mobile systems capable of highway driving. Another advantage is that an isotope source is a constant source of radiation, while linear accelerators are pulsed. Constant wave sources do not require synchronizing the accelerator, detector and cargo movement for image processing as linear-accelerator-based x-ray systems do. With SAIC’s systems, a simple speed sensor that monitors the scanning head movement or the movement of the cargo container can correct for distortion.
Experts are quick to point out that isotope based systems are complementary rather than competitive with x-ray systems. In the end, they say, it’s a matter of matching the system to the inspection scenario. For instance, because isotope systems are significantly smaller and lighter, these systems can be integrated into truly ‘mobile’ platforms capable of driving on the highway. Local police have purchased one such system to patrol the Washington D.C. area. ‘‘You can set up a mobile system and scan parked vehicles or vehicles waiting to go through a gate, one after the other,’‘ said SAIC’s chief scientist for cargo inspection operations, Rex Richardson.
At the other end of the scale are the pulsed fast neutron analysis (PFNA) systems from Ancore Corp (Santa Clara, CA), which was recently purchased by OSI Systems Inc. These systems use dual pulsed neutron sources to create a 3D scan of a cargo container. The scan contains 3D structural information in addition to chemical composition of objects within the cargo container. PFNA’s capabilities do not come without a cost, however. Reported estimates put a PFNA system at between $10 and $15 million (US), compared to $5 million for a 3 MeV mobile system or less than $2 million for a mobile isotope based system. Higher power x-ray based systems fall between the $5 million and $10 million level depending on the power levels, single or dual x-ray sources and other considerations.
As the US government searches for guidance and financing for its new seaport security initiative, cargo inspection companies look for competitive edges over their competition. A single winner is unlikely in what will become a billion dollar business annually within the next decade. Incremental improvements are likely to set the competitive landscape in cargo inspection, just as they govern the machine vision world. ARACOR’s ability to combine high-energy x-ray inspection in a radiation-safe mobile and relocatable system may have given that company an edge in recent months. US Customs plans to purchase eight of ARACOR’s Eagle systems, according to ARACOR’s president, Bob Armistead. Measurements have shown that the Eagle, which operates at 6 MeV and can penetrate more than 12’‘ of steel, provides the capability of large fixed systems. The Eagle has been in operation at the Port of Miami since early 2001. In the near term, despite the ongoing terrorist threat, the US will likely focus on the basic underpinnings of making the country more secure, including goals as lofty as establishing the Homeland Security Department and as blasé as building chain link fences around Army warehouses.
‘‘The people who worry about terrorists have to decide where their principal threats are and what systems meet those threats. Before 9-11, Customs was worried about drug interdiction, now their focus is on explosives and WMD,’‘ explained ARACOR’s Armistead. ‘‘Now they have to go back to their data bases and decide what are the best security strategies to put in place. It’s about deciding what to do and getting the budget to do it.’‘
What’s an effective inspection?
Few countries around the world are as large (in area, trade, etc.) as the US, which makes their cargo inspection quandary less intimidating– and less costly – than the US’. L3 Communications has had success in Amsterdam with a pair of fixed, 9 MeV dual view system, while Bio-Imaging Research Inc. (BIR, Lincolnshire, IL) has had similar success in Japan with five similar dual view systems. In the US, a number of ports and border crossings have pushed 6 MeV systems to the fore, because US Customs has determined that these systems offer the right compromise of radiation safety and penetration. But as L3’s Avolio explained, the key to a solid national policy requires matching the right system to the application.
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