What is the approximate amount of radiation exposure to someone if that person was present in a computerized tomography (CT) room while a CT scan was taking place? I was standing in a corner of the room facing the opening of the scanner but not directly in its path, between 2.1 m and 2.4 m in front of the scanner and behind a mobile lead glass shield (without an apron).
The total radiation dose to a person standing behind a lead glass shield inside the CT room during a procedure would be very low, likely around 0.1 milliSievert (mSv). In order to get a more accurate result, one would need measurement data for that room, the technique factors for that particular scan, and at the location where you were standing behind the shield. As a reference, the average person in the United States gets about 0.01 mSv of natural background radiation dose per day. The amount that you received is likely on the order of a few days of background radiation dose and, thus, very low. If you still have concerns, you can ask the facility to contact their medical physicist or radiation safety officer for a more detailed result based on their survey of that unit.
Kenith “Duke” Lovins, CHP
Answer posted on 10 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.