Answer to Question #13098 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Dental

The following question was answered by an expert in the appropriate field:


When my dental appointment was over, I was at the desk making my next appointment when I heard some loud clicking and beeping down the hall. I saw the dental hygienist pushing the x-ray buttons which were mounted on the wall. She was clearly giving x rays to another patient. The dental hygienist went in and out of the patient's room and pushed the x-ray buttons four or five times. All this occurred while I was just standing 3–5 meters (m) away from her. I am concerned there were x rays that may have hit me where I was standing.


X rays are generated in the housing at the end of the articulated support arm in the exam room and are shielded in all directions except through the tube that is pointed towards the patient's mouth. Only a tiny fraction escapes through the housing or bounces (scatters) off of the patient.

Also, the amount of radiation drops off rapidly with distance. The radiation level if you were standing 5 m away is 400 times lower than at the patient, say 25 cm from the device. That's before considering intervening materials that would absorb x rays, such as the patient's body, walls, doors, and cabinetry.

Think about this—the dental technologist stands at the button and takes maybe 30 x rays a day, five days a week, 50 weeks a year. I monitor the radiation doses of the dental technologists at a hospital's dental clinic, and their radiation doses are too small to be recorded on the radiation dosimeters they wear. So, you needn't be concerned.  

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 31 October 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.