Answer to Question #1556 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:

I am getting a dose of ¹³¹I this morning. Can you tell me after I take this capsule and go home, what are the precautions I need to follow? My doctor told me some, but I am really worried about my family. Could I make them sterile? I have a small dog. What do I do with him?

This response presumes that you received a therapeutic dose of radioiodine for treatment of hyperthyroidism. If that is not the case, then this response does not apply. You will be measurably radioactive for some time after your treatment. However, the dose rate of gamma rays emanating from you will be very low. Further, it falls off rapidly with distance—actually with the square of the distance. For example, doubling the distance from you will reduce the dose rate to one fourth. The dose rate also falls off rapidly with time because of the short half-life of ¹³¹I.The dose to anyone else, even with close, continuous contact, will not be sufficient to cause deterministic effects such as sterility. There is no real reason to be concerned about effects on your family, pets, etc. However, it should be simple to avoid close, prolonged contact for the first couple of weeks. The rule is to eliminate radiation exposure if it can be simply done and is cost effective. Avoiding personal contact fits those criteria.

S. Julian Gibbs, DDS, PhD

Answer posted on January 16, 2002. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of 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 specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.