(BOSTON, MA) -- Some might consider it an X-rated X-ray. The government calls it security.

A device called BodySearch is being used by U.S. Customs inspectors at six airports to detect contraband. The low-power X-ray penetrates only a few millimeters below the skin, seeing through clothing and eliminating the need for strip or pat-down searches.

BodySearch scans are so sharp that the shape of a person's navel is visible, along with the shapes of other, more private parts. And that's raised the concern of groups who say it violates privacy.

U.S. Customs uses BodySearch at international airports in Atlanta, Chicago, Houston, Los Angeles, Miami and New York's John F. Kennedy. It also is being used at six U.S. prisons and a gold mine in South Africa. And with a price tag of roughly $140,000, some private businesses could likely afford one.

``I think they're kind of controversial for an employee operation,'' said Ralph Sheridan, president and CEO of American Science and Engineering, which makes BodySearch.

However, he sees no harm in governments using the device for security and crime-fighting.

``Our whole goal is to make the government more effective in dealing with these problems,'' Sheridan said.

American Science and Engineering, based in Billerica, near Boston, has developed similar products that can see into trucks and unopened cargo containers. Though these devices can also pick up human forms, the resolution isn't as good, and features of the body can't be seen clearly.

BodySearch has earned its manufacturer a dubious distinction. Privacy International, based in Washington, gave the company one of its annual ``Big Brother'' awards. The prize honors the invention that most invades people's privacy.

David Banisar, deputy director of Privacy International, said his colleagues were shocked when they saw an image recorded by the device.

``If you look at the pictures, you could literally see everything,'' Banisar said. ``This is a very intrusive thing. It has been installed with very little discussion ... about whether this is a good idea or not.''

U.S. Customs spokesman Dean Boyd said BodySearch scans are strictly voluntary, and that people have to sign a release form before the government can do the scan.

``Everyone thinks this is some government people who sit around in a crowded room and look at the images and store them and pass them around to people. Like we're doing this just for kicks,'' Boyd said.

Boyd said U.S. Customs doesn't keep BodySearch images unless contraband is detected. In those cases, the images could aid prosecutors.

At the six airports, only passengers suspected of having contraband are asked to undergo a pat-down search or a BodySearch; that affects only one in 2,000 passengers, the Customs Service says.

Still, the American Civil Liberties Union isn't satisfied the technology is being used fairly.

``The biggest problem in Customs searches is that they are conducted with only a minimum level of suspicion and are conducted disproportionately against people of color,'' said ACLU legislative counsel Greg Nojeim.

The ACLU is urging Congress to consider limiting Customs' use of BodySearch. But Sheridan doesn't think that's necessary.

``It's an alternative to a strip search,'' he said. ``And a strip search is much more invasive than the BodySearch technology.''