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Do You Know How Much Radiation and Nude Exposure You Get at an Airport?

Tim Boyer's picture

X-ray scans consist of ionizing radiation that penetrates the skin and has been proven to be a cause of DNA mutations that can lead to cancer. Examples of x-ray radiation exposure that has had health officials concerned over the years have been from high-dose sources such as medical chest x-rays and dental x-rays. Today, however, one of the most common non-natural sources of x-ray exposure is from one type of scanner used at airports―the x-ray backscatter scanner, of which a new report by an independent task force tells us just how much radiation airline passengers are exposed to by it.

This report is based on work performed by a team of independent physics experts volunteering their expertise who were commissioned by the American Association of Physicists in Medicine (AAPM) to determine through rigorous and unbiased study just how safe x-ray backscatter scanners are with respect to the actual amount of radiation an airline passenger is exposed to.

Backscatter scanners use low level X-ray beams directed over a passenger’s body to create a reflection of the body displayed on the monitor. The image produced is described as resembling a 2-dimensional chalk etching.

What the independent task force found was that the radiation exposure from the x-ray backscatter type scanner measured from two scanners in active use at Los Angeles International Airport (and seven other scanners not in active use) delivered a radiation dose of 11.1 nano-sieverts of radiation, which is equivalent to what a typical passenger would receive while standing in line at an airport for 1.8 minutes; or, a dose equivalent to every 12 seconds while seated and flying to their destination. For comparison, an average plane flight of just under 3 hours would expose a passenger to 9.4 micro-sieverts of radiation―nearly 1,000 times greater than the dose delivered by an x-ray backscatter scan before boarding the plane.

Radiation exposure while standing in line is from ubiquitous natural sources of radiation such as radon in the air, cosmic radiation from space, and decay of potassium in the human body. Radiation exposure from cosmic sources is greater while flying at high altitudes because there is less atmosphere to shield passengers from cosmic rays.

According to a press release issued by the American Association of Physicists in Medicine:

“This report represents a wholly independent review of the X-ray scatter airport scanners and is the first we know of to look at multiple scanners including those in actual airport use," said Christopher Cagnon, PhD, DABR, the chief of radiology physics at UCLA Medical Center and one of the lead authors of the new report. "We think the most important single take-away point for concerned passengers is to keep an appropriate perspective: the effective radiation dose received by a passenger during screening is comparable to what that same passenger will receive in 12 seconds during the flight itself or from two minutes of natural radiation exposure.”

While the report is reassuring, recent news reports state that the x-ray backscatter scanner may be phased out of airports in place of a competing whole-body scanner type referred to as the “millimeter-wave scanner” that uses radiofrequency radiation to produce a safer and more detailed image of the passenger being scanned. The millimeter-wave scanner produces a 3-D image whereas the x-ray backscatter scanner produces a 2-D image.

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Reportedly, the move to using millimeter-wave scanners is not due to that it provides a more detailed image of a passenger’s body when scanning for restricted objects, but due to a need for speed and a response to customer complaints about privacy issues with whole-body scanners.

Millimeter-wave scanners process passengers through a security check faster than x-ray backscatter scanners can. Furthermore, new contracts with scanner manufacturers that can provide software to convert the nude-like images produced by their machines into much less intrusive stick-like figures are more desirable. Currently, the maker of a popular line of millimeter-wave scanners provides scanners with the converted image capability.

However, thus far, only the major airports are being outfitted with millimeter-wave scanners that show stick-figure displays of passengers. The older x-ray backscatter scanners with their 2-D body imaging displays are being re-deployed at smaller terminals.

According to Digital Trends:

“If a traveler is unsure about which scanner is being used at their airport, each scanner has a unique design. The backscatter x-ray scanner requires a traveler to step between two, large rectangular walls to be scanned. However, the millimeter-wave scanner looks more like a circular glass booth. Both scanners require the traveler to lift their arms up in the air before the scan is performed.”

Image Source: Courtesy of Wikipedia


“Radiation Dose from Airport Scanners” Report of AAPM Task Group 217 June 2013; by American Association of Physicists in Medicine.

Digital Trends: “TSA removing backscatter x-ray scanners from large U.S. airports.”