A new full-body scanner is debuting Wednesday at the Minneapolis-St. Paul International Airport.
Passengers are asked to hold their hands above their head and empty their pockets and they still must take off their shoes.
The new technology detects items that may be hidden under a passenger's clothes. The Transportation Security Administration says passengers can opt out of the new machine, and an officer will conduct a pat-down instead.
The TSA uses two types of full-imaging scanners. The one in Minneapolis is a "millimeter wave" machine, which sends radio waves over a person and produces a three-dimensional image by measuring the energy reflected back.
Frequent traveler Nancy Bendickson of Maple Plain offered her lukewarm support of the technology.
"I guess if it speeds people through the airport and does a better job of identifying problems, I guess I'll have to put up with it," she said.
The images are viewed by a TSA officer in a different room. The screening process takes about 20 seconds.
The machine began service Wednesday at a lower-traffic checkpoint in a skyway between concourses.
Minneapolis-St. Paul is one of 56 airports using the new technology, and officials expect to receive more units this fall.
(The Associated Press contributed to this report.)