Radiation risk from full-body airport scanners low, new analysis

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The radiation hazard from full-body airport scanners of the type of "backscatter", that use low energy X-rays said very low, even for frequent flyers, researchers, who analyzed the risk of cancer by these devices, of which there are now several hundred provided in airports in the United States.

You can read as Dr. Rebecca Smith-Bindman, Professor of Radiology at the University of California, San Francisco (UCSF), the calculations with Pratik Mehta, made undergraduate at the University of California, Berkeley, in an online edition of the archives of internal medicine, published this week.

Smith Bindman and Mehta concluded that the risk of cancer by the backscatter devices is very low, as long as they work correctly and properly run.

"The amount of radiation in these scans must be so low that you not worried," said the press Smith-Bindman.

Backscatter scanners use X-rays, electromagnetic waves, which are small enough in wavelength on chemical bonds, and for this reason, that they can cause damage to DNA, which means that there is a risk with exposure to X-rays from any source.

Exposure figures from the design specifications of the devices, Smith Bindman and Mehta calculated that the amount of radiation that passenger would absorb in a single backscatter machine scan is approximately the same as that of the average person every three to four minutes is, as they go about their normal lives on the ground, only from background radiation, which everywhere around us around.

They calculated the average flyer 100 times more radiation at the same time would include in the air (as if we are airborne, we are a source of background radiation are closer to the Sun), as they woud by standing in the scanner.

She moved well comparisons with typical claims to other devices, for example, if we have Xrays for medical and dental treatment:

"Individual would have to more than 50 airport of scans right dental radio graph take the exposure of a single, 1,000 airports of scans is the exposure of a chest radiograph, 4,000 airport of scans the same exposure a Mammographieund 200,000 airport of scans equal to the exposure of the review of a single abdominal and pelvic computed tomographic", "they wrote."

But could they not exclude other security risks, for example as a result of errors in the software, human error or machine malfunction, cause that may be, that the scanner that expose the limits of its design specifications and thus passengers in higher radiation.

They could work design documents only with the data in the machines, because they may not test on the field devices.

Smith Bindman said currently the US Transportation Security Administration (TSA) the scanner are independently tested by scientists does not allow, and calls for, it would be wise, change their mind.

"Indicating how many people on these machines are exposed, only I would like to make sure that no possible unforeseeable error could happen," she said, and proposes the TSA can test independent scientists in the field of the scanner.

Backscatter scanner using low-energy X-rays, penetrate the clothing, and show the underlying human body and no hidden items. They are not like a conventional Xray machine that uses radiation reflected rays from the body through the body, using backscatter-scanner.

You are compared to another type of scanner used in airport security, the millimeter wave scanner, the radiation with a wavelength relatively new, much larger than Xrays used.

Backscatter scanner have increased in number in airports in the United States since a failed bombing in December 2009 when a passenger managed to hidden on board a flight to Detroit with explosives in his underwear.

There are now over 500 of these devices in 78 US airports, and there are plans to increase this number to around 1,000 by the end of this year said Smith-Bindman.

Smith Bindman and Mehta calculated that full implementation of these devices would not significantly increase the risk of cancer, life for passengers at airports in the United States, where about 700 million people each year take 750 million flights.

For example, in a set of calculations, they appreciate the cancer risk from the scanner for a million frequent flyers among ten trips per year, with each trip of approximately 6 hours. Provided that they are all X-rays of Backscatter scans on each trip, exposed to this amount of exposure can result in 4 additional cancers under 1 million passengers.

However, she noticed that:

"This 4 excess cancers must be taken into account within the 600 cancers that could occur from the radiation from the flying at high altitudes, and in the context of the 400,000 cancers that would occur in this one million persons in the course of their life span."

Smith Bindman and Mehta as the exposure for children, the group, which may be most at risk because they are longer than adults and thus potentially with a higher lifetime to live risk of cancer.

Using a theoretical group of frequent flyers five years girls take a round trip once a week and scanned with a backscatter scanner each time, Smith Bindman and Mehta concluded that exposure to X-rays of such scanners risk of cancer not much would increase their life.

For this part of their calculation they focused on the breast dose for the Backscatter scans and the impact on the breast-cancer risk. They estimated that "for each 2 million girls, the 1 round trip per week travel, 1 additional breast cancer of these scans could be during their lifetime".

Again, however, noted that:

"The increase of cancer 1 per 2 million young girls must be taken in the context of the 250,000 breast cancer, which will occur in these girls throughout their lifespan due to the 12% lifetime incidence of breast cancer."

Smith Bindman and Mehta completed as a whole, that it there is no significant risk of radiation of backscatter scanners in airports, and commented, that:

"The estimate is difficult, the cancer risks associated with these scans but use the only available models, the risk would be extremely small even among frequent flyers."

"Airport full-body screening: what is the risk?"
Pratik Mehta; Rebecca Smith-Bindman
You Arch Intern Med. 28 online published March 2011.
Doi:10.1001/archinternmed.2011.105

Additional sources: University of California - San Francisco (28 Mar 2011).

Posted by: Catharine paddock, PhD
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