CoreFull access
Background Radiation and Typical Exam Doses
Americans average about 6 mSv a year, half natural and half medical. A chest x-ray is about 0.1 mSv, roughly 10 days of background.
Where it comes from
Everyone receives radiation every day. NCRP Report 160, using 2006 data, put the average US effective dose at about 6.2 mSv per person per year. About half, 3.1 mSv, is natural background. The other half is man-made, and nearly all of that is medical imaging, about 3 mSv, with CT the largest share. Consumer sources such as building materials, tobacco and air travel add only about 0.1 mSv. NCRP Report 184 (2019) found that medical dose fell to about 2.3 mSv per person by 2016, so today's total is closer to 5.5 mSv. Medical imaging is still the largest man-made source. For the registry, remember about 6 mSv in total and about 3 mSv from nature.