IRVING (CBSDFW.COM) – About half of the 15 security checkpoints at the Dallas/Fort Worth International Airport have or will soon have controversial full body scanners.

The new machines and the more thorough pat-downs come nearly one year after a Nigerian man tried to blow up a U.S.-bound jet with explosives in his underwear.

“It detects things that the walkthrough metal detector does not detect, such as the Christmas day bomber that had an explosive device that was all non-metallic,” said John Pistole, director of the Transportation Security Administration.

Officials are using that analogy to combat critics’ complaints, which allege that the machines – which can see through clothes – and pat-downs are an invasion of privacy.

Some aviation experts, however, are expressing doubts that the new technology would have detected the Christmas day bomber’s explosives.

Retired airline captain and aviation safety consultant debates Pistole’s point, saying that the bombing suspect’s underwear was not bulky and had no wires or a detonator connected. There was only a thin layer of explosives sewn into the underwear.

“That would not have caught the underwear bomber and it wouldn’t because it doesn’t have the definition and it doesn’t localize things enough to find it,” Kelly said.

Security experts say the so-called “puffer” machines at checkpoints that blew air onto travelers could detect explosives, but the government has removed those machines because they were too expensive to maintain.

Experts also say that full X-Ray scanners used in other parts of the world can see what’s inside the body, such as heroin pellets found in a suspect’s stomach. That technology works, Kelly said, but security at U.S. airports has not substantially changed with the new systems, Kelly said.

“The American people think these methods at the airport are really protecting them, and they’re not,” he said.

Recent polls show a majority of travelers support TSA’s efforts. Experts say a better solution is using a combination of the puffer machines and body scanner. They also suggest using explosive trace detection technology on carry-on bags as well.

“I just think we need to be a little more thankful we have this,” said DFW Airport traveler Derrick King.

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