Carry-on luggage is fed into a new CT scanner at Washington Dulles International Airport. (Andrea Sachs/The Washington Post)

For what feels like eons, Transportation Security Administration officers have been reminding travelers to remove all electronics and liquids from their carry-on bags and place them in a tray. At more than a dozen airports, however, passengers are hearing a new refrain: Keep your items in your luggage.

This summer, the agency is amping up its pilot test of new CT scanners (in longhand, computed tomography checkpoint scanners). Fifteen airports throughout the country, including Washington Dulles and BWI Marshall, will employ the new technology. Phoenix Sky Harbor International Airport was the first facility to receive the advanced screening innovation, in 2017, followed by Boston Logan and New York’s JFK.

The 3-D imaging equipment resembles a hospital CT scanner, with bags replacing bodies. The technology uses an X-ray camera to shoot hundreds of images, thereby assembling a fuller view of the objects tucked inside carry-ons. TSA officials can rotate the items on three axes, a vast improvement from the current scanners, which provide only 2-D images. By improving detection, TSA hopes to reduce the number of secondary bag inspections and speed up the security process, a triple bonus for travelers.

“This is the same technology as checked bags,” said Lisa Farbstein, a TSA spokeswoman. “This can really detect explosives.”

The agency will integrate the 3-D scanners into regular security lines. To participate in the test, head for the lane with the giant white machine that resembles a sci-fi movie prop. Then, fight the urge to remove your electronics and liquids, and walk on through.

Despite the change of one rule, several others remain, including the size restriction on liquids (remember your 3-1-1). You must also remove your coat and shoes, unless you are part of a trusted traveler program such as PreCheck.

TSA plans to install up to 40 units by the close of the year and more than 145 by the end of fiscal year 2019.

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