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Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

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Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#11

Post by alanh »

zipdog wrote: post #3

> Peter Rez ... calculated the risk of getting cancer from a single scan at about 1 in 30 million His odds were for a single flight, but I wonder if the scanner radiation has a cumulative effect? Surviving a plane flight has no impact on the likelihood of the next one, so taking a lot of flights would edge the odds in favour of dying from the scanner cancer. But then there`s the wide difference in the type of death.

> But then there’s the wide difference in the type of death.

Good point, I would rather die in a terrorist attack than after months of chemo and hospital food… that said, one is a lot more premature! (Edit: Actually, if you got cancer from the scanner, it would probably kill you within a few years.)

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#12

Post by gojomo »

wnoise wrote: post #2

Oh, well if they're equal, then that means this is a perfectly proportional and appropriate response.

Only if:

• the scan completely offsets the risk of terror death. I suspect not; someday someone will tell the TSA and/or terrorists about drug mules.

• the economic cost of the scanning infrastructure/training/delays etc. is equal or less than the economic cost of the terror deaths offset.

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#13

Post by maninthemirror »

zbanks wrote: post #4

More tellingly, on an average two-hour flight, you'd receive about 100 times the radiation from a single scan. But, by using the transitive property, you're more likely to die from radiation at flying altitudes than from a terrorist attack on said airplane. EDIT: Sorry, I forgot to include the link: http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effect... Which comes from: http://hyperphysics.phy-astr.gsu.edu/…

You are understating the risk from backscatter radiation. Because the radiation is sent in a burst, and targets skin tissue, the DNA damage may be far greater than a similar dose of cosmic radiation.

You are also assuming that the backscatter machines are functioning properly and aren't overdosing people.

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#14

Post by [deleted] »

zbanks wrote: post #4

More tellingly, on an average two-hour flight, you'd receive about 100 times the radiation from a single scan. But, by using the transitive property, you're more likely to die from radiation at flying altitudes than from a terrorist attack on said airplane. EDIT: Sorry, I forgot to include the link: http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effect... Which comes from: http://hyperphysics.phy-astr.gsu.edu/…

[deleted]

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#18

Post by aphyr »

Actual web page: http://www.public.asu.edu/~atppr/bodyscan.html

Actual article: https://docs.google.com/viewer?url=http://www.public.asu.edu...

The first thing you'll learn in radiation safety is that the nature of the dose matters a lot. Sometimes you're A-OK if you can survive the initial dose. Other doses are accumulative. It depends on the energy of the radiation, the tissue's scattering cross-section, the time, and the flux, among other things.

This means that the Sievert (a unit of biological impact due to radiation) is only meaningful in the context of the dose geometry. It's great for talking about a chest X-ray, where the dose is spread out over a big volume of tissue. Where it's unclear is in the case of rapidly-thermalizing or compton-scattered particles: like backscatter. Look at the graph in that article. Something like half of the energy is deposited in the first couple centimeters of tissue.

We haven't done this before, and don't have a good model for the long-term effects. My guess? This kind of exposure is a hell of a lot worse for melanomas than a chest X-ray delivering the same energy. Claiming compliance to a metric like the ANSI limits is meaningless.

Edit: Oh, and the concern raised over the beam stopping and delivering a couple Sv to a quarter-sized patch of skin is definitely scary. We did exactly that to several people with medical cyclotrons.

Edit: I should also mention that tissues have varying tolerance to radiation. Rapidly-dividing cells tend to be hit the hardest, which is why your stomach lining, skin, and hair slough off after acute ionizing rad exposure. Your skin, stomach, lungs, breast and thyroid are also the most frequent to undergo cancer in radiation-linked longitudinal studies. See, for example,

http://pats.atsjournals.org/cgi/content/full/5/9/934

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#19

Post by naz »

maninthemirror wrote: post #13
zbanks wrote: post #4

More tellingly, on an average two-hour flight, you'd receive about 100 times the radiation from a single scan. But, by using the transitive property, you're more likely to die from radiation at flying altitudes than from a terrorist attack on said airplane. EDIT: Sorry, I forgot to include the link: http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effect... Which comes from: http://hyperphysics.phy-astr.gsu.edu/…

You are understating the risk from backscatter radiation. Because the radiation is sent in a burst, and targets skin tissue, the DNA damage may be far greater than a similar dose of cosmic radiation. You are also assuming that the backscatter machines are functioning properly and aren't overdosing people.

A single backscatter X-ray scan gives a radiation dose of 0.009 mrems, about the same as eating a banana.

http://en.wikipedia.org/wiki/Banana_equivalent_dose

Don't get me wrong, I'm opposed to the scanners as much as anyone for privacy reasons and general pointlessness. But I'm seeing a lot of bad science thrown around here.

Re: Chance of Dying From Backscatter Radiation Same as Chance of Terrorism

#20

Post by mechanical_fish »

eru wrote: post #10
wnoise wrote: post #2

Oh, well if they're equal, then that means this is a perfectly proportional and appropriate response.

Judging by the other replies, I guess you should put explicit sarcasm tags around your comment.

Yes. And then it still won't be very funny. It's too similar to something an actual TSA flack would say.
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