Paul, I assume you are talking about the spacer for the brachytherapy ONLY?
My RO told me they cannot use the spacer for EBRT/salvage radiation because there is always the possibility that there are cancer cells closer to the rectum that the radiation won’t get.
That being the case, you can still have the spacer for the single high dose part of treatment but will have to wait for it to dissolve before you can have your other doses.
You really have to get this clarified!