Covert X-rays tested as security tool
Airport X-rays aren't just for baggage anymore.
Radiation-emitting devices now are screening people and vehicles at terminals, border crossings, and other checkpoints where security officials want to look for weapons or contraband. More such use is likely after officials from the Food and Drug Administration and other agencies described how lower-level radiation machines could be used without special precautions.
The FDA is planning discussions with Homeland Security officials about covert X-ray screening of people as well. But already some passengers at US and foreign airports are knowingly being X-rayed, part of a broader effort to step up transportation security in the wake of terrorist attacks.
Several years ago, US Customs and Border Protection officials began X-raying some passengers arriving on foreign flights. Then last month scanning was begun of some passengers departing from London's Heathrow Airport by a low-powered X-ray system. Also in October, officials started scanning vehicles driven onto a ferry between New Jersey and Delaware.
Law-enforcement agencies say they're just testing the effectiveness of these devices before deciding whether to buy more of them. The machines are based on new technology set to emit lower levels of radiation than medical X-ray systems, and until recently were used primarily to peer into cargo containers as a way around having to open them.
But X-raying of individuals is likely to become more common since the FDA and other groups crafted recommendations last year on how to mitigate health concerns, say government and security industry officials.
Frank Cerra, who leads an FDA radiation laboratory in Rockville, Md., expects growing demand for the X-ray systems from security officials to move people through checkpoints quickly. ''That's why we were very interested in getting the standards written," Cerra said.
Industry and scientific groups, including the Health Physics Society, say people should know when they're exposed to the radiation created by the machines, but Cerra said he plans to talk with the Department of Homeland Security and other agencies about when individuals might be scanned without their knowledge.
''If it's covert, no matter what we regulate, certain agencies are going to do it," Cerra said.
The idea of covert scans also came up last year in a report Cerra helped write for the National Council on Radiation Protection and Measurements called ''Screening of Humans for Security Purposes Using Ionizing Radiation Scanning Systems." The report says one possible use of the X-ray technology would be to scan vehicles and their occupants at customs checkpoints or at the approach of a vulnerable bridge or tunnel. ''Covert systems capable of scanning a vehicle traveling at 5 to 30 m.p.h. are possible," it states.
The report technically defined what it called ''general use systems," meaning those that don't require special precautions because they emit low levels of radiation.
Some see the low-power X-ray systems as preferable to the increasing use of pat-down searches at airports that have drawn criticism, especially among women, for being intrusive. But because the X-rays penetrate clothing, they show images of their subjects essentially naked. For that reason, others fear the X-rays pose their own potential invasion of privacy.
''We don't willy-nilly allow people to be strip-searched," said Barry Steinhardt, a technology specialist for the American Civil Liberties Union. Steinhardt said he's also concerned about potential health risks from the systems.
Department of Homeland Security spokesman Donald W. Tighe said in a statement: ''We look forward to working with the FDA and other federal, state, and local partners in evaluating what protective measures are put in place and what technologies are used, balancing security and privacy with public health."
According to the report by the radiation protection council, a nonprofit organization in Bethesda, Md., passenger scans with low-power X-ray technology require ''no special precautions" even for children or pregnant women. The report said it would take at least 2,500 scans of the same individual per year before the total exposure would reach maximum recommended exposures. It did recommend testing to ensure scanning units remained below certain thresholds.
Traditional X-ray systems transmit their rays through a subject to be captured on film or sensors. The newer versions are called ''backscatter" systems because their beams bounce back to sensors on the same side of the subject.
According to the radiation protection council's report, the backscatter systems expose humans to about 5 microrem per checkpoint, one hundredth as much as a person might receive on a one-hour commercial flight, or one-thousandth as much as a medical chest X-ray.
David J. Brenner, professor of radiation oncology at Columbia University, and a co-author of the radiation protection report that the various government agencies will use to decide whether to broaden the use of X-rays, said he wants to see more research before concluding it would be safe to screen all 700 million US air passengers per year. Some people, he noted, are more sensitive to radiation than others.
''Of course the needs of aircraft security cannot be ignored, but if there are alternatives to the use of X-rays for mass screening of passengers . . . they should certainly be fully investigated before the country commits itself to a mass X-ray program," Brenner wrote in an e-mail.
Brenner mentioned one alternative scanning technology that uses high-frequency microwaves, which are theoretically safer since they are reflected by the skin. Companies working on that technology include Safe-View Inc. in Santa Clara, Calif., and a Woburn unit of L-3 Communications Holdings Inc.
''We just believe the real test is how the general public reacts and health officials react to the use of ionizing radiation. Obviously some have concerns," Safe-View chief executive Rick Rowe wrote in an e-mail response to questions.
The trial X-ray system at Heathrow Airport is made by Rapiscan, a division of
Rapiscan vice president Peter Williamson said his company is also looking at high-frequency microwaves but doesn't think the technology is effective yet. He said the radiation protection report and similar guidelines from the American National Standards Institute have helped him address customers' fears about the X-ray system's health effects. When he mentions the reports to airport officials, Williamson said, ''that takes one concern off the table."
The system at the New Jersey/Delaware ferry, testing of which was to end Nov. 21, is made by
The van's X-ray is more powerful than the Bodysearch version, and so far the company doesn't have the certifications to screen individuals with it. Richard Mastronardi, American Science vice president, said the company is in talks with the FDA about the van but wouldn't describe them. The FDA's Cerra said one topic is the van's lack of a backstop to absorb some of the energy it emits, which might raise concerns on where it can be used. Even so, Cerra said, he expects the company will market the van for covert surveillance uses. ''I"m sure they'll target that market," he said.
Ross Kerber can be reached at kerber@globe.com.
