Mike,
If your radiation fields included your throat, which from your description,I am assuming they did. The minor salivary and mucous glands that are present in your soft palate and back of the throat probably haven't recovered. This leads to less lubrication and the dry, hoarse felling that you are experiencing.
If I had amagic wand I would send it to you to elliviate this, but I don't.
In my experience with my OC patients it is a common problem after radiation treatment.
Try and stay hydrated and drink lots of water when you are eating. I have found that many patients say it gets better with time. I'm not convinced that it does I think they learn how to cope/deal with it.

Hope this is useful.

Mike