Answer to Question #14961 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues

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

Q

I have a medical condition that is sensitive to radiation. I want to understand how risky it is to be in a building that has x rays? So often, professional medical office buildings have at least one office with x-ray equipment. Therefore, if I needed to see a doctor on the seventh floor that does not have x-ray machines but there are other offices in the same building that have x-ray machines, how many floors away would be a safe distance if we did not know the protection used on the ceiling or floor of the x-ray room? Would two floors distance be enough? Would this distance be different if the x-ray machine was on a floor above versus a floor below? Finally, how about a very safe distance if the x-ray machine was in another office on the same floor of the same building?

A

I want to begin by reassuring you that there is no risk from being in the same building with medical x-ray equipment. 

The use of medical x rays is very well regulated, and facilities are required to ensure that there is sufficient shielding to prevent any member of the public from receiving a radiation dose above 1 milliSievert (mSv) more than ubiquitous background in a year. This limit applies to the receptionist in the office with the x-ray machine, as well as anyone who would have an office directly above or below the machine. For regulatory purposes, it is assumed that those individuals are present 40 hours per week every week. Even if you spent an entire day on the same floor as the x-ray machine, your dose would not be enough to cause any harm. The average background radiation dose in the United States is 3 mSv per year, and the average background radiation dose is closer to 4.5 mSv per year in Colorado.

Deirdre H. Elder, MS, CHP, CMLSO

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 20 June 2023. 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.