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0 pointssemi-extrinsic6y ago0 comments

A CT has a pretty high radiation dose. As far as I understand, for every 2000 people given a chest CT we expect 1 person to get a fatal form of cancer due to the CT.

Compared to the natural incidence of getting a fatal cancer in your lifetime (about 400 in 2000), this is a very low. And for serious conditions, a CT can literally be a life saver.

But if you apply chest CTs to screen for a disease with (let's say) a 0.1% fatality rate, the side effects of your screening increases the fatality rate by 50%.

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anonsivalley6526y ago

It's ~29000 deaths / 70M CT scans per year.

That's 414 micromorts, which is almost exactly as risky as skydiving once on average.

https://en.wikipedia.org/wiki/Micromort

Source: US NCI 2007

semi-extrinsicOP6y ago

Yeah, 1 in 2000 is 500 micromorts, somewhere in the 400-500 micromorts region.

jonas216y ago

The wikipedia article says skydiving is 8 micromorts per jump. So more like skydiving 50 times?

medymed6y ago

I don’t think biologic math always works combinatorially like multiple sky dives.

This sometime troubles me with radiation dosing comparisons. Another is time distribution, when a radiologic imaging study is equated with exposure from X amount of time in an airplane at high altitude. The time frames are different—- drinking 1 liter of water in an hour is usually safe, and drinking 50 liters of water is fine spaced out over a longer time period—-but not 50 liters over an hour. Radiation doses are often quite time dense.

antognini6y ago

Yes, the rule of thumb I know is that you can get about 25 CT scans in your lifetime before having a significantly increased risk of cancer. By contrast you can get about 25,000 chest X-rays.

eganist6y ago

From what we can tell, SARS-CoV-2 has a 2% mortality rate among those diagnosed. That seems like a pretty decent trade in odds if it accelerates early stage treatment.

scottlocklin6y ago

Considering you just read an article on how the CDC has told people to not test people who aren't obviously going to die, you may want to revise that figure downward some out of sample bias.

kalipsosu6y ago

2% within confirmed cases. There is a part of the iceberg which we cannot see because mild cases will not seek care. Actual mortality rate is far lower than that. You should check mortality rate for outside wuhan population. It is 0.08%

ciceryadam6y ago

Italy's 52 deaths vs 1900 cases is higher than 2% - https://www.theguardian.com/world/2020/mar/02/italys-coronav...

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