Answer to Question #14337 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:

Q

I will be having iodine-131 (I131) radioactive iodine therapy. Does the radiation harm or have any negative effect on the function of PhonakTM behind-the-ear hearing aids? I am concerned as they lay on the top/back of the ears.

A

Your Phonak hearing aids are complex electronic instruments and require good care. I checked the User Guide for your hearing aids, and on page 58 it says that "special medical or dental examination including radiation described below, may adversely affect the correct functioning of your hearing aids. Remove and keep them outside the examination room/area before undergoing medical or dental examination with x ray (also CT scan)." Because your treatment with I131will expose your hearing aids to radiation that is similar to x rays, your concern is understandable. Fortunately, I am not aware of any reports of hearing aid malfunction during or after radioactive iodine treatments. I believe you can continue to safely wear your hearing aids during your treatment. I base my conclusion on the following considerations.

First, the hearing aid manufacturer's recommendation was likely based upon a 2008 Food and Drug Administration (FDA) advisory that recommended caution when exposing cardiac pacemakers or implanted defibrillators to x rays during chest CT scans. A search of the FDA website did not yield the advisory, so it may have been withdrawn. Since that time, studies on cardiac devices exposed to x rays have shown that transient changes in cardiac device function may occur during the actual CT scan, but they cause no medical issues and no permanent damage to the electronics. However, to "err on the side of caution," manufacturers of all sorts of other medical devices have extended the FDA recommendation to include exposure to any x-ray exams.

Second, the amount of radiation absorbed (so-called "dose") by devices during CT scans and other x-ray exams is delivered at very high dose rates, but the extremely low dose rate to your hearing aids from your I131 treatment would not cause any problems at all. I did some calculations to ensure myself that this assumption was correct. I found that the total dose delivered to your hearing aids from your I131 would be similar to that from a head CT scan. However, it is delivered at a rate equal to about one one-thousandth of 1% of that from a CT scan, and so would be very unlikely to cause your hearing aids to fail.

In conclusion, I recommend that you continue to wear your hearing aids during your I131 treatment, unless advised otherwise by your nuclear medicine care provider. After all, there are significant safety risks associated with not being able to hear!

I hope this helps.

Robert E. Reiman, MSPH, MD

Answer posted on 2 February 2022. 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.