Answer to Question #11187 Submitted to "Ask the Experts"

Category: Pregnancy and Radiation — Proximity to radioactive persons

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


My wife accompanied her mother while she had a parathyroid scintigraphy using 99mTc. There were five other patients having cardiac scintigraphies with 99mTc in the same room for four hours. My wife was sitting next to her mother and about 1 m away from other patients. After the scan, my wife and mother spent the whole day together. We later learned that my wife was four or five weeks pregnant during this scan. Is it possible to calculate the dose to the embryo?


Thank you for coming to the Health Physics Society "Ask the Expert" website to get some additional information on radiation exposure during early pregnancy. I trust that you shared these concerns with your doctor. This inadvertent exposure of the embryo to radiation understandably can cause some fear and uncertainty. There is a slightly increased exposure to radiation when sitting near one or more persons for a whole day who are having nuclear medicine procedures like parathyroid scintigraphy. The exposure is slightly more than what is thought of as "background." Background radiation is what we receive day to day just living here on the naturally radioactive planet Earth.

Your wife was probably exposed to something on the order of an extra five days of background. The good news: At this very low exposure there is no evidence of deleterious effects such as birth defects or cancer. In fact, up until the eighth week of pregnancy, early embryonic development is not affected by birth defects, pregnancy loss, or growth retardation unless the exposure is substantially higher.

I hope this information alleviates worry and allows you to enjoy this special time with your wife and family.

Dawn Banghart, CHP

Answer posted on 2 April 2015. 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.