Backscatter technology: the future of airport security scanning?

Future passenger security checks at airports may no longer include pat-downs, as a new full-body imaging technology undergoing trials at Manchester Airport.

Siobhan Wagner writes that Manchester Airport’s Terminal 2 is testing the Secure 1000 Single Pose, which uses backscatter technology and proprietary image processing software to produce a ghost-like outline of an individual’s body. A concealed threat such as a knife or gun would be clearly detectable on the image.

The U.S.-based developer of the technology, Rapiscan Systems, believes that the technology could, one day, replace metal detectors in airports.

Tim Raynor, the European Union (EU) government affairs technical director for the company, said that the imaging system is different to normal X-ray machines.

The Rapiscan system works by bouncing X-rays off an individual’s skin to produce an outline image of the person’s body, he added. A normal X-ray imaging system detects X-rays that are generated through a person. Raynor said that, in an airport security check scenario, an individual would be asked to stand between two machines for a few seconds. Each machine would generate a pencil beam of X-rays that would scan an individual in a raster fashion over the body.

Each point of backscatter would be picked up by an array of detectors in the machine. With this input, an image would be formed using Rapiscan’s image processing software and transmitted to a remote security officer who would then electronically confirm if the passenger can proceed or whether a search is required.

Raynor said that the officer would see an image of the person 0.5mm below their skin surface. “It is very difficult, if not impossible, to recognize the person,” he said, addressing concerns about privacy. “You do have the curves of the body visible. Anything that is on the body or in clothes being worn by the body show up as different contrasts on an otherwise flat background.”

According to Raynor, a belt buckle or gun would show up as dark shadowed images on the otherwise ghost-like outline of a person, making their detection clearly visible.

Rapiscan performed a trial of its technology at Heathrow Airport in 2004. Raynor said that the trial was a success, but that the technology has now been advanced in a way that “improves the passenger experience.”

The system now includes an additional sensor so that a person’s front and back can be scanned at the same time. “In the 2004 trial, the passenger needed to pose in a variety of poses for each side of the body to be imaged and therefore scanned,” he said.

The scanning time has also been decreased by reducing the X-ray dosage and running the pencil beam faster. Raynor said that this change did decrease image quality a bit, but it is still effective. In addition to privacy concerns, he said that Rapiscan is prepared to address any trepidation about safety.

“Because we are using a raster pencil beam, the amount of X-rays used to generate images is extremely low,” he said. “The effective dose of the X-ray is similar to the dose you get in an aircraft at 30,000ft for five minutes.”

The equipment in the voluntary trial has been approved by the National Radiological Protection Board, which is part of the Health Protection Agency and is responsible for licensing all X-ray equipment in the United Kingdom.

The imaging technology trial will run in Manchester Airport’s Terminal 2 only for at least twelve months or until enough data is gathered to assess all aspects of the equipment.

Rapiscan recently received an order worth $25 million from the U.S. Transportation Security Administration (TSA) for multiple units of the Secure 1000 Single Pose for airport security screening systems. According to Raynor, Rapiscan fully expects other governments to approve their use and roll out the systems in other parts of the world following the U.S. deployment.

“In the U.S., you will find that the walk-through metal detectors will be augmented — if not replaced — by whole-body imaging systems,” he said.

“That will lead the EU to make similar requirements that therefore will need to be rolled out in Europe,” added Raynor. “Manchester Airport will obviously understand how that works operationally from the trial it is now doing.”