Backscatter X-ray Sample The Boston Globe says that, starting this fall, [Logan Airport will be equipped with backscatter X-ray scanners][1] for screening people. Now, at the stated radiation levels, backscatter X-rays (despite being ionizing radiation) are considered “safe” for hundreds of doses per year. Assuming you trust that scientists set the exposure limits prudently, and that the machine does not go [Therac-25][2] on you, the X-rays themselves should not pose much of a problem.

More worrisome is the fact that most people seem to be comfortable with the idea of letting the TSA take what are essentially nude pictures. (Certainly, the woman in this picture might want to reconsider.) This opens up a big privacy issue that is not going to be solved, as the TSA plans to do it, by simply putting the machine operator in a concealed room.

Also, if these machines are designed anything like the ion-mobility spectrometers that we are already asked to use at some airports, I am going to be really annoyed. The GE EntryScan was presumably supposed to seem kind of like a regular metal detector (albeit a $200,000 one). But instead you’re asked to walk into a tiny booth with doors that automatically shut behind you, trapping you while you’re assaulted with high pressure jets of air. Then it continues to trap you for 5-10 long, uncomfortable seconds. If the experience is anything like that, count me out. This isn’t livestock processing. I don’t understand why people would volunteer to subject themselves to treatment like that.

Backscatter X-rays aren’t even useful. While the TSA may boast that they are the missing link for catching all attempts to conceal their “prohibited items” (more than 3 ounces of yogurt?), the list of threats that they can deter is very short. Guns and most knives are easily caught by simple, cheap metal detectors. Conventional explosives can be detected by spectrometers. Can the steep financial and social cost of this process really be justified by the threat from ceramic knives and plastic explosives?