TSA Says Shoe X-Rays Can Detect Bombs

Transportation Security Administration (TSA) workers screen passenger belongings at a security checkpoint at Washington Dulles International Airport in Chantilly, Va., Friday, Aug. 11, 2006. After a day of long lines and confusion, travelers arriving at U.S. airports Friday were better prepared for new rules, tighter security and bans on liquids of all types. (AP Photo/Charles Dharapak) (Charles Dharapak - AP)

WASHINGTON -- The government sought to assure airline travelers Tuesday that X-raying shoes at security checkpoints was a reliable way of detecting improvised bombs, a claim contradicted by a Department of Homeland Security study.

"Screening shoes by X-ray is an effective way of identifying any anomaly, including explosives," said Kip Hawley, Transportation Security Administration chief, at a news conference at Reagan National Airport just outside Washington.

A study by the Homeland Security Department, obtained by The Associated Press, states that X-ray images "do not provide the information necessary to effect detection of explosives."

Under new orders this week, all airline passengers must put their shoes through X-ray machines before boarding their flights.

A scientist who has studied the issue said the truth lies somewhere between the study's findings that X-ray machines can't detect bombs and Hawley's assertion that they can.

Richard Lanza, senior research scientist at the Massachusetts Institute of Technology, said the X-ray image doesn't identify what a gel or a liquid is made of. But, Lanza said, screeners can "look at the image and connect regions that look the same in density and shape."

It's not a foolproof method, but it is often effective, he said.

"Nothing is 100 percent," Lanza said. "But if the bad guys think you have a good shot at discovering it, they'll do something different."

Hawley said that 31,000 screeners have been specially trained to see if a shoe has been tampered with when they look at its X-ray image.

"It does take the human brain to make the interpretation on X-ray, but it is, frankly, not the most difficult thing we have to do to find potential shoe bombs," Hawley said.

He displayed copies of X-ray images of two pairs of shoes _ one with no explosive device and one worn by Richard Reid, who was arrested aboard a trans-Atlantic flight in 2001 when he tried to ignite a bomb in his shoe.

"You can see very clearly the difference between a shoe with an explosive and one without," Hawley said.