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The greater weight assigned to alpha emissions is justified by the fact that alpha particles are really, really messy - they have both higher charge and higher momentum than beta, by a couple of orders of magnitude.

I don't know how the dose weighing by body part is done, but if I were doing it I would base it partly on the sensitivity of the tissue type hit, partly on how much I'd like to keep the organ in question and partly on how much any future kids would like me to keep the organ in question (so reproductive organs would get a comparatively higher weight due to the risk of germ line mutations).

External sources would be expected to hit salvage workers equally, while inhaled and ingested pollution hits your stomach, gut, lungs and chest first, then probably your liver and kidneys.

As an aside, I would not find "one extra CT scan a day" at all reassuring. CT scans are not harmless - they're just a lot less harmful than the stuff they are used to find.

- Jake

Friends come and go. Enemies accumulate.

by JakeS (JangoSierra 'at' gmail 'dot' com) on Mon Apr 4th, 2011 at 06:07:39 AM EST
[ Parent ]
JakeS:
I don't know how the dose weighing by body part is done, but if I were doing it I would base it partly on the sensitivity of the tissue type hit, partly on how much I'd like to keep the organ in question and partly on how much any future kids would like me to keep the organ in question (so reproductive organs would get a comparatively higher weight due to the risk of germ line mutations).
In addition, different cell types are more or less differentiated and therefore at different risk of cancer and mutation.

Very undifferentiated cells (stem cells) are the most sensitive to genetic damage and the most able to mutate into cancerous cells. This is why the bone marrow is so sensitive and low radiation to it causes leukemia (high radiation simply destroys the tissue). The same gows for the gonads. Highly differentiated cells are less susceptible to mutating into cancer cells - they are more likely to just die because of mutations than to survive as a cancer cell. Also, the ability to metasthasize is linked to how undifferentiated a cancer cell is, because a cell cannot just migrate and survive in the midst of another tissue. The closer a cell is to a stem cell, the easier it is.

Whether this can be captured by a multiplicative factor for committed equivalent dose is a different question...

Economics is politics by other means

by Migeru (migeru at eurotrib dot com) on Mon Apr 4th, 2011 at 06:13:10 AM EST
[ Parent ]
Sievert - Wikipedia, the free encyclopedia
Tissue type Factor
 
bone surface, skin 0.01
bladder, breast, liver, esophagus, thyroid, other 0.05
bone marrow, colon, lung, stomach 0.12
gonads 0.20


Economics is politics by other means
by Migeru (migeru at eurotrib dot com) on Mon Apr 4th, 2011 at 06:29:45 AM EST
[ Parent ]

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