Airport passenger screening measures have become a touchy issue in the U.S. in the past week, but in the past year the controversial measures have detected more than 130 prohibited, illegal or dangerous items that otherwise would have made it onto airplanes, the Transportation Security Administration says.

The TSA now requires all passengers at some U.S. airports either to pass through a full-body scanning device, which reveals everything beneath their clothing, or to submit to a thorough pat-down inspection -- a choice that has some travelers livid about their loss of privacy.

But the TSA says keeping passengers safe is its top priority, and the new measures are necessary.

"This year alone, the use of advanced imaging technology has led to the detection of over 130 prohibited, illegal or dangerous items," TSA spokesman Greg Soule told FoxNews.com. The TSA would not disclose exactly what those items were, but it said they included weapons like ceramic knives and various drugs -- including a syringe filled with heroine hidden in a passenger’s underwear.

"The advanced imaging technology can detect both metallic and non-metallic threat items that are concealed on a person’s body," TSA spokesman Nick Kimball told FoxNews.com. "…Intelligence tells us that our enemy still seeks to target airplanes, and as we saw illustrated last Christmas Day, that threat can manifest itself in an improvised explosive device that has no metal in it."

Kimball stressed that the TSA has put measures in place to ensure that travelers' privacy isn't compromised when they walk through the scanners.

"The officer that looks at the image is in a separate walled-off room where they’re unable to see the passenger that’s going through, and the officer working with the passenger doesn’t see the image," he said. "After the officer is able to determine there’s no threat item on the passenger, the image is deleted before the officer can scan the next passenger."

Passengers who feel uncomfortable going through the scanners have the option to be patted down by an officer of the same sex -- a procedure that may involve touching the breasts and genitals through the clothing.

TSA Chief John Pistole, who submitted to a pat-down inspection before putting the procedure in place, described it as "thorough" and admitted it made him feel "uncomfortable." "It was more invasive than what I was used to," he told the Senate Wednesday.

But Pistole said the procedure is necessary for passengers who are unwilling to walk through the scanners.

"The purpose of that is obviously to detect the type of devices that we had not seen before last Christmas," he said, referring to Umar Farouk Abdulmutallab, a Nigerian man accused of boarding a U.S.-bound plane with explosives hidden in his underwear and then trying to blow up the plane in midair as it approached Detroit.

"I am very sensitive to and concerned about people’s privacy concerns and I want to work through that as best we can," Pistole said.

The International Air Transport Association, an international trade body that represents roughly 230 airlines, says for now the TSA needs to improve communication and ensure that passengers are aware of any changes to airport security. And travelers, in turn, need to prepare themselves.

"Passengers need to readjust their expectations on what they’re going to find at the airport," IATA spokesman Steve Lott told FoxNews.com.

But in the future, he said, the TSA should "stop looking for bad objects or bad things and start looking for bad people."

"The government has a lot of information on everyone who gets on a plane… so let’s integrate that intelligence into the checkpoint," he said. "Today the checkpoint is just looking for bad objects – like tweezers and shampoo, but the agent doesn’t know anything about the traveler."

With a quick background check, Lott said, agents could better assess the risk associated with each traveler, then use things like scanners and pat-downs to further analyze those deemed high risk.

Kimball says the TSA is always looking for ways to improve, but for now the scanners and pat-downs are the best way to keep people safe in the sky.

"The threat that we have is real and our security methods must evolve," he said. "And we are always assisting and evaluating what we have in place in order to make sure that we are addressing the most current threats."