Answer to Question #12730 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Pediatric Issues

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

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 5 February 2019. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.