As some travelers threaten a nationwide protest today, the head of the Transportation Security Administration said the agency is exploring the feasibility of less-invasive procedures.

However, John Pistole announced no immediate changes, and promoters of National Opt-Out Day hope many holiday travelers will reject screening by advanced-image machines.

Denver International Airport predicts this will be the busiest week in its history but said there will be no special lanes for those who opt out of the advanced-image screening. Those who opt out of the screening will receive a full patdown. Those who refuse both will not be allowed to board their flights.

Pistole acknowledged that some travelers find the current pat-down procedure excessively intrusive. But he reiterated that one of the TSA’s primary missions is to ensure that air travel is safe.

“To those who are concerned about them being more thorough, I’m sympathetic to those concerns,” Pistole said. “But I’m also trying to be respectful of those who want to have the highest level of confidence, each time you get on a plane, to know that everybody else on that plane has been thoroughly screened just like you have or I have.”

The TSA’s pat-down procedure became much more rigorous at the start of this month, and some passengers have complained that it is highly invasive and at times humiliating.

“We are exploring ways that they might be less invasive, yet with the same outcome in terms of detection,” Pistole said.

A number of air travelers also have been concerned about another method of passenger screening that relies on Advanced Imaging Technology machines that perform what some describe as an electronic strip-search of travelers.

These machines use either a millimeter-wave or backscatter X-ray technology to create a naked image of the traveler that a screener in a private room can examine for hidden weapons or explosives.

DIA has six of the millimeter-wave scanners, and travelers who opt out will be subjected to a thorough pat-down by the TSA, the agency said.

The Denver airport is expecting the busiest week in its history with a projected 1,017,476 travelers through next Monday. The TSA “is fully staffed and prepared for the busy holiday travel season,” the agency said in a statement.

“Passengers who decline screening with Advanced Imaging Technology will receive alternative screening, which includes a pat-down,” it added. “Passengers who refuse to complete the screening process will not be allowed to fly. In keeping with TSA policies, if a passenger becomes disruptive, our screening officers will seek assistance from local law enforcement.”

Amy Marschak said she wants people to descend on the state Capitol at noon today for a “Denver Says No to Full-Body Scanners and Pat-Downs” rally.

“We need our civil liberties back,” she said. “You can’t say every single person is a suspect.”

Pistole said the TSA is working to introduce Automated Target Recognition (ATR) software to scanners that the agency says would display a “computer-generated, generic human image” or “avatar” instead of the actual stripped-down image of the passenger now shown.

Pistole said the TSA hopes to deploy ATR technology sometime next year, but “I’m not going to roll it out until the technology is proven.”

Jeffrey Leib: 303-954-1645 or jleib@denverpost.com