Answer to Question #9425 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:


My question is similar to question #7138, except in my case I have an eight-month-old baby at home. I want to know what precautions I need to take to protect my baby.

I had a total thyroidectomy due to papillary carcinoma. Five months later (I waited to finish nursing the baby), I received 3,700 MBq of 131I. When I was discharged from the hospital three days later, the nuclear medicine technologist measured the remaining amount of radiation in my body. He said the dose right next to my neck was much higher. That is the area that is close to the baby when I hold him, to rock him to sleep, carry him around, give him a bottle, etc. The only advice he could give me was to "not touch the baby much" for 14 days. However, 14 days is a very long time, as I am the principal caregiver right now.  What do I need to do to protect the baby? No touching at all? Sleep in a separate room? We are sharing the same bathroom right now (the baby only is in there for his bath time). I am confused and obviously concerned about the risk to my baby. Would it be better for me to be in a hotel instead of in the same home (a two-bedroom apartment).

I have received a lot of mixed information before, during, and after my treatment, and I want to be sure that I am doing the best thing for my baby.


Assuming that you have normal kidney function and that you went naturally hypothyroid before getting your 3,700 MBq, the amount of 131I in your body after leaving the hospital after three days was about 1/64 of the initial dose. This is because generally less than 1 percent of the 131I goes to your thyroid remnant and/or residual cancer, and your kidneys get rid of half of what is in your body about every 12 hours.  

If you received Thyrogen, the kidneys get rid of half of what is in your body about every eight hours. That being the case, it is perfectly safe for you to take care of your baby. No further precautions are necessary.

Carol S. Marcus, PhD, MD
Professor of Radiation Oncology and of Radiological Sciences, UCLA

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 17 December 2010. 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.