Backscatter x-ray scanners, more common in airports: image via blog.silive.comThe Transportation Security Administration (TSA) has deployed 486 full body scanners in U.S. airports and plans to install another 1000 by the end of 2011. Besides the privacy issues that have become quite controversial, there has been concern over the amount of radiation these scanners emit and what their potential is for increasing risk of serious health problems.
Rebecca Smith-Bindman, MD, and Pratik Mehta from the department of Radiology and Biomedical Imaging at the University of California, San Francisco, have evaluated the radiation in each of the two machines the TSA has put into use to ascertain their levels of potential health damage.
One of the x-ray scanners is a millimeter-wave scanner which, the researchers indicate, emits extremely low radiation, each scan emitting 'a small fraction of the energy of a cell phone." The millimeter-wave scanner also captures any reflected energy.
The backscatter x-ray scanner, which is more commonly found in airports, uses levels of ionizing radiation similar to those found in medical imaging, but rather than passing through the person imaged, the radiation reflects off the person imaged. This radiation is absorbed primarily by the skin.
The researchers write that though the level of damage depends on the dose of radiation, that emitted by the backscatter x-ray is so low that it is not possible to know whether it has a potential to cause harm. Nevertheless, they put the risk in perspective, writing that the exposure to radiation from a backscatter x-ray is minuscule compaired to the amount of radiation exposure from the flight itself and even smaller compared to a dental x-ray.
The authors continue:
It is informative to contextualize the exposure from the backscatter
scans with the other sources of radiation frequently experienced.
An individual would have to undergo more than 50 airport scans
to equal the exposure of a single dental radiograph, 1000 airport
scans to equal the exposure of a chest radiograph, 4000 airport
scans to equal the exposure of a mammogram, and 200 000 airport
scans to equal the exposure of a single abdominal and pelvic computed
tomographic scan. Thus, the doses for the airport scans are
exceedingly low compared with doses routinely received in the health
Though the researchers attempt to quantify the risk of cancer for frequent flyers, all flyers, and 5-year old frequent flyers, their estimations are admittedly shaky. "as the risks are truly trivial." And they conclude that travelers should not fear going through the scanners for health reasons.
You can read the report, Airport Full-Body Screening, in the Online First edition, March 28,2011, in the Archives of Internal Medicine.
Archives of Internal Medicine via LA Times