http://www.reuters.com/article/idUSTRE60553920100106But the radiation levels are well below the threshold that could be considered a risk to an individual's health, said Dr. James Thrall of the American College of Radiology and chief of radiology at Massachusetts General Hospital in Boston.
"All of the concerns that we have about the medical use of X-rays really don't apply to these devices," Thrall said in a telephone interview.
"The exposure is extremely low and the energy of the X-rays is also very, very low," he said.
"When X-rays are used for medical imaging purposes, they have to be energetic enough to get through the human body. The X-rays used in the backscatter machines in airports have such low energy that they literally bounce off the skin. That is what backscatter implies," Thrall said.
As for the actual radiation dose, he said the typical backscatter machines deliver about 0.1 microsevert of radiation. The average chest X-ray, by comparison, delivers 100 microseverts of radiation, and a chest computed tomography or CT scan delivers 10,000 microseverts.
According to the Transportation Security Administration website, the radiation dose from a single scan on a backscatter machine is the equivalent of two minutes of flying on an airplane.
