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%.

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

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.

https://www.newyorker.com/news/our-columnists/how-iran-becam...