Using backscatter X-ray on passengers at airports

Implications: Current passenger screening techniques don't find explosives, only metallic objects.  New techniques are available to find explosives on people, but they are controversial for two reasons and haven't yet been deployed for screening passengers.  One is the issue of privacy, the other, at least for backscatter X-ray, is radiation exposure. 


Analysis: Terrorists know that metal detectors in use at airports can be circumvented by using non-metallic weapons (including explosives). New technology is needed to screen passengers.  Governments are investigating a revamp of the screening checkpoint to meet the ongoing threat of suicide bombers.  In the US, there are roughly 1900 checkpoint lanes at the nation's airports (historically the early adopters of new security technology).  Late adopters (government buildings, courthouses and other sensitive facilities) use over 10,000 screening checkpoints and are currently also using metal detectors.  Historically, they eventually adopt the airport screening approach, but are much more price sensitive.

The options for improved screening of passengers are limited; hard radiation that can be applied to bags cannot be used on passengers for health reasons.  An additional factor is concern over personal privacy.  Several technologies could potentially be used: full body trace explosives detectors e.g. from GE.

Three companies have introduced backscatter X-ray systems. Two, OSI Rapiscan and American Science & Engineering, make full body X-ray systems currently under evaluation in the US and overseas.  The third company; Spectrum San Diego, makes a scaled-down version for screening medical casts, prosthetic limbs and wheelchair-bound passengers. The primary competition for these systems appears to be from millimeter-wave body imaging systems made by companies such as SafeView (recently brought by L3 Communications) and Smiths Detection.  Both technologies have advantages and disadvantages.  Millimeter wave technology is currently faster and could be used on all passengers, but backscatter X-ray has a better image and could be used to resolve rejected passengers in lieu of a hand search.

Concerns are radiation exposure and privacy.  These play differently in different countries.  In the US, radiation concerns are minor; whereas in Europe it is a big concern even though dose from a backscatter scan is equivalent to ~5 minutes flying at 30,000 ft.  On the other hand, privacy is a big concern in the US, whereas in the UK, virtually no passengers had a problem.  US privacy advocates liken these technologies to an "electronic strip search".  In reality (and I have seen and used both types of systems) it's not nearly that dire.  Faces are unrecognizable in both; and the best body image is much less revealing than a naked mannequin in a store window. Still,  companies are looking at "modesty" algorithms to better conceal the image, eliminating storing of images and investigating other operational methods to mitigate concerns.  Airport trials are underway - an initial X-ray backscatter trial has begun at Phoenix airport in the US and Heathrow Airport in the UK has trialed both backscatter X-ray and millimeter wave systems.  Typically, it takes 2 - 4 years to move from early trials to full deployment if no major problems are found.  A further ongoing challenge will be how to pay for these devices: each is over 10 times as costly as the most expensive metal detectors in use today.  Of course, that can get accelerated and cost becomes less of an issue if there are more terrorist attacks or attempts and if the US Congress gets involved.