- Backscatter technology projects an ionizing X-ray beam over the body surface at high speed. The reflection, or "backscatter," of the beam is detected, digitized and displayed on a monitor. Each full body scan produces less than 10 microrem of emission, the equivalent to the exposure each person receives in about two minutes of airplane flight at 30,000 feet. It produces an image that resembles a chalk etching.
- Millimeter wave technology bounces harmless electromagnetic waves off of the human body to create a black and white image (not a photograph). It is safe, and the energy emitted by millimeter wave technology is thousands of times less intense than a cell phone transmission. This technology is not new. The TSA is not the first to use this technology. It's currently being used in Canadian airports and U.S. courthouses in Colorado and Texas, as well as international locations.
How is radiation measured:
The biological risk of exposure to radiation is measured using a unit called a rem. The daily background radiation to which we're all exposed is about 1 millirem, or 1/1000th of a rem. The amount of radiation exposure absorbed by the body during these scans is about 0.005 millirem.
How many scanners and how much:
There are more than 50,000 federal screeners at more than 440 commercial airports across the country. The TSA told Congress that the full-body scanners cost between $130,000 and $170,000 per unit, and the TSA is deploying 1,800 units.