hi
Just wondered if the doctors have put you in touch with any support groups? You would be asuprised at how many people have fought cancer or are in the fight and have set up websites and meeting groups where they talk about their treatments...they are also very knowledgable about these sort of things too. It may be worth speaking to them about their experiences
As for whether radiation treatment is appropriate, have you thought about seeking a second opinion? either by reccomendation by your current doctors or otherwise? I can;t think of any reason medical why they would object, no one on here can really definitivly know whats going on with your father until they have seen him or his notes ultimately...the lesions/little tumours spreading to the brain etc mean the tumour has 'moved' presumably?
it may be worth asking the doctor about what this exactly means and whether this is 'metastatic spread' through his 'lymphatic system' and just whatg that is. And finally what each treatment actually is, with its possible and probable (i.e. likely % wise success) benefits and side effects. No matter how busy a doctor may appear, there is always someone within that team who will be willing to talk to you provided you make an appointment with them to talk
I'd also just echo growth&courages post....its sage advice IMO