How does the risk from medical radiation compare to background radiation exposure?
Natural background radiation exposure accounts for an average of 3.1 mSv/yr with variations depending on where you live. In the US, the average person is exposed to an additional 3.0 mSv/yr from medical sources (predominantly CT scans). Of course, some people receive no radiation and others much, much more. The average US total radiation exposure (all sources) is 6.2 mSv/yr which is an increase from 20 years ago (3.6 mSv/year) when CT scans were much less common. For comparison, the dose for a standard Chest CT is 7 mSv. A standard Chest x-ray is 0.1 mSv. There are fundamental differences between a continuous dose over a year (background radiation) and a dose that occurs over a few seconds like in CT, but these are helpful comparisons.
