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June 09, 2005
X-Ray Machines & TSA, Part III
Link from Schneier:
EPIC has highlighted the problems with backscatter X-ray technology in their spotlight on surveillance. They are focusing on eliminating the use of the technology, rather then trying to find a way to limit the privacy issues. The relevant part of their analysis is:
The risks to privacy rights can be lowered only slightly with some modifications to TSA's current X-ray machine program. The agency could tailor the backscatter technology with the digital equivalent of a "fig leaf." As recently as November, the British press reported that the TSA did not intend to deploy the scanner until manufacturers had made such modifications. Whether the agency will modify the scanners before they are used at the 16 airport test sites is uncertain. . . . But even this technique leaves open the question of whether the original unedited image is obtained and stored by scanning device, whether or not it is available to a screener at a particular point in time.
I don't know why they didn't discuss the methods in my earlier post. Maybe those methods won't work or maybe no one is interested in pursuing a somewhat less intrusive method.
Posted by rshah at June 9, 2005 09:11 PM
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Comments
They should scan luggage and carryons with X-rays, but not people. Using ionizing radiation on people for anything other than medical purposes is not a good idea. We would have no way of tracking the approximate accumulated absorbed dose. Any ammount of ionizing radiation can potentially cause delayed effects later in life, and infants, children, adolescents, and pregnant women would be at a significantly higher risk. By “backscatter” they mean that the radiation photon has interacted with a molecule of the body, causing it to bounce back. Any time you have an interaction, a molecule can become ionized, and thereby, change its properties or destroy its function. If it hits, say, a water molecule, no big deal, it will just pull an extra oxygen atom and become peroxide, which will not kill you. However, if it hits a molecule of DNA, the cell code could be changed, resulting in cell death, or worse: cancer. Now, you have to produce enough backscatter for the scanner to pick up and make an image. Thats alot of interactions. Did I mention dose is something that accumulates? The more you get exposed, the more chance of cellular damage and cancer. So, if they start using these in airports, they better be ready for a gradual but significant increase in cancer among air travellers, especially frequent flyers. They also legally have to warn every traveller of the risk because radiation is a hazard. Also, the opperator would be at great risk from constant exposure to the backscattered radiation. Not to mention the expense of equipment.
The risk to health and the subsequent cost of the machines and in healthcare and lawsuits should prevent them from using something like this ever.
Senior Airman Richard Sabo, USAF Radiology
Posted by: Richard Sabo at June 12, 2005 03:36 AM
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