Distance is min of 6 feet -- should not be a problem unless very small rooms....
I am worried because my son sleeps nextdoor and the only distance will be less than 6 feet. Will radiation pass through the walls. It is not a concrete but a standard wall.
You can ask the lab that handles the RAI treatment. I think might depend on the dose they give you. I think issues with physical contact, handling food and bathrooms is more important. To make sure none of the radioactive iodine in you don't end up in him.
You could have him spend the night at a friends house the first night. Or have him sleep on the couch.
The lab people who handle the treatment will go over this with you.