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by snarkconjecture
972 days ago
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You did it wrong. One Sv increases your absolute risk of fatal cancer by an added 5% or so. It doesn't multiply it by 1.05. Quoting Wikipedia: "According to the International Commission on Radiological Protection (ICRP), one sievert results in a 5.5% probability of eventually developing fatal cancer based on the disputed linear no-threshold model of ionizing radiation exposure." Also, where on earth did you get 1% as a "depressing" upper bound from? For lifetime risk of dying of cancer? It's over 15% in the US. |
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It's the use of effective whole body dose to estimate the risk associated with a dose to part of the body. Exactly zero radiation biology organizations recommend this. Most explicitly caution against using effective whole body dose to estimate radiation risk. Effective whole body dose is only used for population-level estimates.
For example, one of the most radiosensitive (wrt cancer) organs is the thyroid. But his thyroid is not in the beam. Also the skin is exposed more than the interior on CT, which increases the risk of skin cancer. These corrections are standard, while alternatives to LNTM are not standard.
Then there is the effect of age. Most radiation related cancers are delayed by a long time, and the faster that cells are dividing, the greater the risk of DNA damage. But Scott is old, which is also why older workers were preferred for cleanup at Fukushima.
D_eff can get you within an order of magnitude I suppose, but you shouldn't express it with two significant figures — it's misleading precision. You could say 1/1000 or maybe 1/700? But you really need more detail for any kind of meaningful medical decision.
Anyway, that's my rant as someone studying for the board exam.