Denver is one of five airports in the country that has begun “full body scanning” of passengers.

The Transportation Security Administration today will start screening travelers at Denver International Airport using a machine that bounces radio waves off skin to produce a graphic, whole-body image. The scan aims to reveal weapons, explosives or other items hidden on a passenger’s body. But because the image is anatomically explicit, millimeter-wave screening is controversial. DIA and five other U.S. airports are using the new technology in pilot programs to assess its capabilities, said David Bassett, TSA’s federal security director in Denver.

Passengers who object can request a pat down search. The other cities:

Sky Harbor International Airport in Phoenix, Los Angeles International, JFK International in New York, Baltimore-Washington International and Albuquerque International.

This is a very invasive machine.

Whole-body imaging “is an extremely high invasion of privacy,” although TSA’s effort to ensure that images are never made public is “commendable,” said John Soma, a University of Denver law professor and executive director of the Privacy Foundation.

As for protections:

To deal with privacy concerns, TSA is offering protections on whole-body scanning, including blurring the faces on images of passengers being screened, examining the images in a remote room and offering no possibility for images to be stored, printed, transmitted or reproduced, Bassett said.