The other issue besides privacy that has surrounded backscatter X-raying has to do with radiation exposure. Most of us do not get X-rayed on a regular basis; and when we do get X-rayed in a hospital or doctor's office, we've got a lead vest thrown over our vital organs. But at airports, there's no lead vest. So are people who travel a lot going to be subjected to dangerous levels of radiation if they get backscattered too often? Most experts say no. According to the Health Physics Society (HPS), a person undergoing a backscatter scan receives approximately 0.005 millirems (mrem, a unit of absorbed radiation). American Science and Engineering, Inc., actually puts that number slightly higher, in the area of .009 mrem. According to U.S. regulatory agencies, 1 mrem per year is a negligible dose of radiation, and 25 mrem per year from a single source is the upper limit of safe radiation exposure. Using the HPS numbers, it would take 200 backscatter scans in a year to reach a negligible dose -- 1 mrem -- of radiation. You receive 1 mrem from three hours on an airplane, from two days in Denver or from three days in Atlanta. And it would take 5,000 scans in a year to reach the upper limit of safety. A traveler would have to get 100 backscatter scans per week, every week, for a year, in order to be in real danger from the radiation. Few frequent flyers fly that frequently.
For more information on backscatter technology, airport security and related topics, check out the links below.
More Great Links
- Bowers, Faye. "With full-body X-ray, a closer look at air travelers." The Christian Science Monitor. Feb. 26, 2007. http://www.csmonitor.com/2007/0226/p02s02-ussc.html
- Frank, Thomas. "Revealing X-ray scanner makes its debut." USA Today. Feb. 26, 2007. http://www.usatoday.com/travel/flights/2007-02-26-backscatter-usat_x.htm
- "Radiation Exposure Examples." HyperPhysics. http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/radexp.html
- "Screening Individuals with Backscatter X-Ray Systems." Health Physics Society. http://hps.org/hpspublications/articles/screenindx-ray.html
- "Z Backscatter." American Science and Engineering, Inc. http://www.as-e.com/products_solutions/z_backscatter.asp