Answer to Question #7840 Submitted to "Ask the Experts"

Category: Nuclear Medicine Patient Issues — Therapeutic Nuclear Medicine

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


For treatment of papillary thyroid cancer, I received a dose of 5550 MBq of 131I to destroy the thyroid tissue that remained after surgery. The doctor sent me home right away and told me that for the first two days I should keep a distance of about one body length away from others, sleep alone, and use my own bathroom.

After I came home on the day of my 131I treatment, I spent much of the day watching TV with my wife, who sat at the other end of the room (about 3 meters). At one point, while talking on my phone, I accidentally walked within two feet of her without thinking, then backed away. My questions are (1) Is this level of exposure okay? and (2) What are the possible consequences for someone who is exposed to an 131I patient?


Walking within two feet of your wife exposed her to very little radiation, even on the first day after receiving your therapy, and there will be no consequences to her from that brief exposure. The "extra" radiation exposure to your wife was much less than the amount of exposure we get from one day of living on the earth. (See an explanation of radiation exposures on our Web site.) So you and your wife should not be concerned about that very brief exposure as you walked by her.

You sound like you are a very compliant patient and take your doctor's orders seriously. That is very good for you and your family. It is easy to forget for a moment and not follow it to the letter. In this case, there will be no harm done.

Marcia Hartman, MS

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 13 October 2008. 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.