I'll add my two cents:
From what
I've recently learned about this disease & the various treatment options, radiation seems to be mainly used for dogs who are not good candidates for amputation (ie:
Two affected limbs, HD, ED, arthritis, etc.) In these cases, they use the radiation to treat the tumor for pain management only, as it has no curing effects. I believe chemo is started right after the radiation therapy is complete, as it's usually used in conjunction with chemotherapy as an alternative to amputation. (?)
With that said, I see no good reason NOT to do it, providing you have access to a veterinary radiation facility........and of course, the $$$!! I don't know how much it costs, but I imagine it's up there. And believe me, I fully understand the desire to 'do whatever it takes'. But personally, I thought the medicinal route was the obvious choice for my girl, as it was likely to be much more cost effective & would yield approximately the same result, since I elected not to 'treat'.
Good luck with whatever you decide to do, as only
you know what's 'right' for your dog.
And welcome to our little 'club'.....

MK