I had radiation therapy to the lower half of my head about three years ago, in much different (more optimistic) circumstances, and it's not at all pleasant.

Based on what I know from personal experience, I wouldn't want radiotherapy for a brain tumor that will only grow back, not for myself or for anyone else.

My tumor was in the neck (right tonsil), and I was relatively young (mid-50s) and otherwise quite healthy. The prognosis was good for elminating the tumor once and for all, and I was told up front that the treatment would be extremely debilitating, but that it would very likely result in complete remission. So, in may case, it was well worth 6-8 months of misery.

At a more advanced age, and with no hope of real recovery, I think I'd say no thanks. Of course, it's up to the person whose life is in the balance, as long as he's able to express himself.

I know this will be a tough time for you and your dad and everyone else in your family. God bless.