Answer to Question #13235 Submitted to "Ask the Experts"

Category: Pregnancy and Radiation — Radiation effects to embryo/fetus

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


I am eight weeks pregnant, and I have to go with my father to a different city for his positron emission tomography/computed tomography (PET/CT) scan of his abdomen with fluorodeoxyglucose (FDG). Should I stay in the same room after the scan? What other precautions do I take?


You and your baby will not be at risk from your father's scan. You may follow some simple precautions to keep you and your baby's exposure to radiation very, very low. For a standard PET/CT scan using FDG, your father will be injected with a small amount of fluorine 18 (18F), which is radioactive. It has a very short half-life, meaning it does not remain radioactive for very long. First, he will receive an injection, which includes the radioactive material. At that point, he will be a source of radiation over the next 24 hours, but even so the exposure to you and your baby will be very low.

If you stay at least one meter away for the first 24 hours after the injection, your exposure would be about the same as three weeks of the radiation exposure we all receive from the natural radioactive materials in our environment, and about 4% (or 1/25th) of the exposure that is allowed to pregnant workers who routinely work with radiation. Brief hugs during that period, or helping him into the car, will not significantly increase that exposure. If you have a long drive after the scan is over, one of you should sit in the driver's seat and the other on the passenger side in the back seat of the car.

After the injection, and while he is waiting for the scan is when he will have the highest amount of radioactive material. There may be other patients in the waiting area who are also radioactive, so during that period, you may want to wait two meters or more from him and the other patients in the area.

I hope this answer helps to put your mind at ease. My best wishes to you, your baby, and your father.

Barbara Hamrick, CHP

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 9 December 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.