John C. Hayes
Diagnostic Imaging 
Sunday, January 10th, 2010
Since the attempted explosion of an airliner as it was landing in Detroit on Christmas Day by an alleged terrorist from Nigeria, global air safety experts have been scrambling to enact new safety measures. A quick answer has come in the form of whole-body scanners that use low-level radiation to allow screeners to see through clothing to identify hidden weapons or explosives.
These things have been around for a while, but, outside of a few pilot locations, haven’t really gained much attention until now. Given the circumstances of the Detroit incident, we shouldn’t be surprised that airports all over the world are rushing these systems into use.
Most of the press has been concerned with privacy issues—the systems essentially strip passengers naked—and focused far less on health safety matters. Still, the safety issue is starting to engage the public. Recent news reports have suggested the new scanners are basically safe. But a more nuanced look at the question suggests the answers are not yet all that clear.
There are two technologies in use in the U.S.: Backscatter technology uses x-rays delivering less than 10 microrem of radiation per scan, equivalent to the radiation one receives inside an aircraft flying for two minutes at 30,000 feet, according to the American College of Radiology . Another approach relies on millimeter-wave technology, which uses radio waves in the millimeter-wave spectrum. Two rotating antennae cover the passenger from head to toe with low-level radiofrequency energy.
The ACR said it was not aware that either of the scanning technologies that the Transportation Security Agency is considering would present a significant biological threat for passengers screened. Indeed, ACR chair Dr. James Thrall was quoted on ABC news as saying, “the individual x-rays themselves are very low energy. And unlike the x-ray spectrum that we use in medicine, the backscatter x-rays don’t really penetrate to the organs in the body.” Click here  for the article.
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