Answer to Question #11712 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I was at the dental office the other day, and they did a panoramic x ray and three dental cone beam computed tomography (CT) scans, as the first two got the wrong area. Should I be worried about too much radiation at one time?
If you look at the answer to Question 11138, it gives cone beam CT doses for various machines. The average effective dose for cone beam CT scans is given as 130 microsieverts (µSv), which is 0.13 millisievert (mSv). The average effective dose for panoramic procedures is about a tenth of this. Since they did the cone beam CT three times, your effective dose would be around 0.4 mSv from the cone beam CT, and your dose from the panoramic x-ray procedure is 0.014 mSv, barely more than the rounding error. So your total dose is about (3 × 0.13) + 0.014 = 0.44 mSv.
These are very small doses. Below 100 mSv above background, the observed radiation effects in people are not statistically different from zero. In other words, the risks of health effects from these and other diagnostic imaging procedures are either too small to be observed or are nonexistent. And, of course, you benefited from the procedure. The benefits from properly performed, clinically indicated, diagnostic imaging procedures far outweigh any hypothetical cancer risk.
Kent Lambert, CHP