Answer to Question #15024 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

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

Q

I took a relative for computed tomography (CT) scans of the abdomen, with and without contrast. I was in the CT room while she was being prepared for the procedure. I cannot remember, but I am worried that I may have been in the room during the CT exam. If I was in the room during the CT exam how much radiation would I have received if I was not wearing a lead apron?

A

I hope your relative is doing well now. It is standard practice for the CT technologist to make sure everyone is outside the room or wearing lead if inside the room during imaging. However, we know procedures are not always followed. If you were in the room without lead during the imaging, your radiation exposure would have been very low.

It is not possible to accurately estimate your dose without knowing the dose metrics from the CT scanner and where you were standing in the room. The approximate effective dose to the patient who has a CT abdomen/pelvis with and without contrast is approximately 15.4 milliSievert (mSv). The risk to the patient from the radiation is either too low to measure or doesn't exist. Anyone else in the room during imaging is only exposed to scatter radiation, which is a small fraction of the patient dose. Your dose was likely around 1 microSievert (µSv) or less, depending on where you were standing. Average natural background radiation exposures in the United States are approximately 3 mSv per year or 8.2 microSievert per day.

You don't need to worry about your radiation exposure if you were in the room during the CT scan. The dose would have been very low. 

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 7 July 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.