Privacy advocates want to stop airport body scans which project images that can be very revealing.

This week they plan on launching an online petition campaign to stop -- at least for the time being -- what they refer to as a "virtual strip search."

The technology, called millimeter wave, doesn't leave much to the imagination as it scans the body looking for concealed items.

“You look like you are naked even with your clothes on,” said Susan Bale, a Denver resident. “I don’t want anyone to see me naked except the people I choose to see me naked. I’d rather they use other methods to make me safe while flying.”

"It basically just let's us know if there is anything out of the ordinary sticking out, their belt, a cell phone," said Dede Colton, an imaging operator with TSA.

The transportation security administration is pilot testing millimeter wave at screening checkpoints at 19 airports, including at Denver International Airport, with an eye to deploying it more widely.

But privacy advocates said there are no formal rules for how the machines and the images they generate will be used.

"I'm worried that the technology can retain images, that those images may be used for more than just travel screening purposes," said Lillie Coney, of Electronic Privacy Information Center.

For instance, they might turn up on the Internet.

But the TSA said the machines have been disabled so they cannot store, send or print images. A spokeswoman said the images are not overly detailed and other privacy steps have been taken.

"The officer who attends the passenger at the machine never gets to see the images that are generated,” said Jon Allen, of the TSA. “The officer who views the image, views those in a remote location. They never physically get to see the passenger."

But the privacy community is launching a petition drive to suspend millimeter wave testing. It fears TSA will change the rules on how the technology is used unless it goes through the formal, public, federal rulemaking process.

"It forces the issue out into a more transparent process,” said Coney. “And when it's all said and done we all have the rule book."

The TSA said all passengers are given the option of choosing a different screening method and that the majority of the time they pick millimeter wave.

But privacy advocates argue that's because the public isn't adequately informed.

“I wasn’t aware that they were in use,” said Don Harms, who was flying from Denver to Canada. “I think people should be made fully aware and have the option.”