Answer to Question #12730 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I had to take my eight-week-old child with me to the dentist. I did not receive x rays but the patient next to me received bitewings. The office uses an open-bay design with a half wall between each patient. My child was in his car seat against the half wall. I believe there was at least 2 m between my child and the other patient. Would my child have been exposed to scatter radiation, or would the distance and half wall have protected him? I am worried about any radiation my child may have received.
The amount of radiation would be very low and of no risk. By law the maximum annual radiation dose that a member of the public (i.e., not a worker at the facility) is permitted to receive is 1 millisievert (mSv). Dental offices are designed with this limit in mind. To ensure that the limit is never exceeded, room design is based on the maximum possible use of the x-ray machine. Room design also uses a very conservative assumption that a single member of the public is present half of the maximum time the x-ray unit may be used. Your child was there only once during one x-ray procedure.
To determine the maximum dose your son may have received, let's assume the x-ray unit is used only once each day, for 250 days per year. Taking these occupancy frequencies into account, your child's maximum radiation exposure would at most be 1/125 of the public dose limit, or 0.008 mSv. For perspective, the radiation dose, 0.008 mSv, is about the same as the radiation dose from naturally occurring radiation in the environment that we all receive each day.
Kent Lambert, CHP, FHPS