Just in time for the holiday travel season, passengers departing Tucson International Airport will be faced with a new security regimen never before imposed here: full-body scanners.

The U.S. Transportation Security Administration is installing two millimeter-wave, full-body scanners at TIA and expects to have employees trained and the systems fully operational by November or December, said Lorie Dankers, a TSA spokeswoman.

Up to now, air passengers departing from Tucson have been spared from full-body scanning because older models of the scanners wouldn’t fit in the airport’s narrow security corridor.

“The airport at Tucson, like a lot of airports, has a pretty narrow checkpoint area,” Dankers said. Installing the larger machines would have reduced the number of available security lanes, she said.

The newer millimeter-wave scanners have replaced the older, backscatter X-ray machines, which were removed by the TSA amid criticisms of the nudelike images they create and health concerns over radiation exposure.

The new scanners also are narrower than the old machines — 60 inches versus 76 inches wide — allowing the TSA to fit one into each of the Tucson airport’s two security checkpoints, Dankers said.

The new scanners at least partially address both the privacy and the health concerns that dogged the X-ray machines, which were first installed in a few airports in 2008 and later expanded nationwide before they were all removed by mid-2013. Though current figures weren’t immediately available, by last fall about 750 millimeter-wave scanners were in use at about 160 U.S. airports, according to TSA data.

Unlike the older X-ray scanners, the new millimeter-wave scanners create images by emitting high-frequency electromagnetic radio waves.

But the new scanners are designed so TSA screeners never view detailed body scans, Dankers said. The millimeter-wave scanners are used with special “automatic target recognition” software that reduces scanned body images to a cartoonlike outline on an operator’s screen and generates boxes around body regions that may hold hidden contraband, for a follow-up pat-down search of the area.

When no suspicious objects are detected, the scanner generates only a green “OK” screen to the operator.

“On the generic image there’s a box on the area of the body where the software has indicated some follow-up screening needs to be performed,” Dankers said. “If that’s on your arm, they’ll just pat down your arm, they don’t need to pat down the entire body.”

While the millimeter radio waves emitted by the newer scanners generally are considered safer than X-rays, their effects are largely unknown and some public-health advocates say more studies are needed.

But the TSA believes the millimeter-wave machines are safe. Dankster said the scanners emit “10,000 times less energy than a cell phone call.”

The removal of the X-ray scanners assuages some critics, but privacy advocates such as the Electronic Privacy Information Center still oppose full-body scanners as invasion of privacy, even when nude-like images aren’t displayed.

Meanwhile, the new scanners provide some relief to air travelers with artificial joints or other metallic medical implants, who typically trip up metal detectors and have to submit to additional screening, Dankster said.

The scanners should be welcome news to many Tucson passengers with medical implants, said TIA spokesman David Hatfield, recalling a recent e-mail from a local resident with an artificial joint, asking when the body scanners will finally arrive.

Travelers who wish to avoid the body scanners can largely do so by enrolling in the TSA’s PreCheck program, which offers expedited security checks by exempting travelers from having to remove their shoes, belts, liquids, laptops and light jackets while screened, Dankers noted.

PreCheck passengers are routinely allowed to skip full-body scans, though the TSA still conducts some random scans on PreCheck fliers, she said.

“No passenger is ever guaranteed expedited screening. … We have to be able to have that random factor,” she said.

Travelers can join PreCheck by providing required documentation such as a passport or a birth certificate and driver’s license and paying an $85 fee to get a “known traveler number” good for five years.

Expedited screening also is available to members of the U.S. Customs and Border Protection’s Trusted Traveler programs, including Global Entry and SENTRI, which is used to cross the border with Mexico.

Further changes are coming to TIA that will affect the security checkpoints in the next couple of years, as the airport launches a terminal optimization project that will include relocating and expanding the two TSA checkpoints.

The overall project is expected to start construction in the second quarter of 2016 and be completed sometime in 2017, TIA’s Hatfield said.

Senior reporter covering business and technology for the Arizona Daily Star/Tucson.com