My guess is that we see the tibia in that scan because it lies just under the skin, and is dense and large and extremely reflective. You'll have noticed that it doesn't show up from the back.
But that only goes to illustrate more of the issues with these machines. How carefully can wavelength really be managed so that only clothing is penetrated? The answer certainly seems to be, not carefully enough, especially given that I've seen discussion that seems to admit that at least some of the intended radiation penetrates the skin, a nontrivial issue especially for those flying frequently and for those who have been treated with radiation.
Like, for example, most breast cancer patients who have opted for breast-conserving surgery, since it's usual practice to irradiate the tumor bed to be sure of having killed any stray cancer cells. Or like any breast cancer patients who've had mastectomies but whose tumors had high-risk characteristics, where best practices often call for chest wall radiation. After these treatments people are advised not to even allow the affected area to get any sun, like, ever again in their lives; they (we) carry tiny tattoos so that medical personnel know where to make sure they avoid hitting us with any further radiation; changes in the skin from the treatment are obvious to those in the know. (I do not look forward to explaining all of this to the nice ladies and gentlemen of the TSA next time I fly. And I'm good at explaining these things without irritating security people.)
And these safety problems are only the ones that come up if the machines work as intended, and if there's never an accident with the operating software. If and when there is, all bets are off. It's enough that on balance, I'm more pleased than not to have a medical issue that would and will force me to opt out of the backscatter machines, no matter how dreadful the alternative becomes.
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Date: 2010-11-24 03:10 pm (UTC)But that only goes to illustrate more of the issues with these machines. How carefully can wavelength really be managed so that only clothing is penetrated? The answer certainly seems to be, not carefully enough, especially given that I've seen discussion that seems to admit that at least some of the intended radiation penetrates the skin, a nontrivial issue especially for those flying frequently and for those who have been treated with radiation.
Like, for example, most breast cancer patients who have opted for breast-conserving surgery, since it's usual practice to irradiate the tumor bed to be sure of having killed any stray cancer cells. Or like any breast cancer patients who've had mastectomies but whose tumors had high-risk characteristics, where best practices often call for chest wall radiation. After these treatments people are advised not to even allow the affected area to get any sun, like, ever again in their lives; they (we) carry tiny tattoos so that medical personnel know where to make sure they avoid hitting us with any further radiation; changes in the skin from the treatment are obvious to those in the know. (I do not look forward to explaining all of this to the nice ladies and gentlemen of the TSA next time I fly. And I'm good at explaining these things without irritating security people.)
And these safety problems are only the ones that come up if the machines work as intended, and if there's never an accident with the operating software. If and when there is, all bets are off. It's enough that on balance, I'm more pleased than not to have a medical issue that would and will force me to opt out of the backscatter machines, no matter how dreadful the alternative becomes.