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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