when can or can't radiation be used

Hi All

My dad, who was diagnosed in November with stageIV nsclc, has been handling his first 3 chemo treatments very well. He has the 4th tomorrow. His cancer marker (CEA?) was a 229 in the beginning & is now 185.His last PET, after 1 treatment showed some tumors have shrunk while others have not. He just had another PET on Monday & we are looking forward to receiving the results.His main concern is the pain. I still don't think he takes his oxycontin correctly along with the oxycodone.Oxycontin being slow release isn't being taken regularly & mostly taken when the pain is bad. I have been my dad's "research scientist, doctor & chemo driver" since the he reeived his diagnosis. I sit with him in the office to be another set of ears and to ask questions that he might forget. My mom said that he might want to have a solo meeting with the doctor to discuss this last PET (b/c he thinks, correctly, that I might get upset if they discuss a poor prognosis). She thinks that he might want to do something "drastic" as she puts it, either surgery or radiation. I told her that I don't believe he will be a candidtae for either due where the tumors are in his lungs (I believe close to his heart), also the fact that he has "a bit of emphysema" getting out of breath after slight exertion.
I heard of a kind of radiation called TOMO therapy, which is a more targeted therapy. I am wondering if anyone knows whether or not patients at this stage are candidates for this or is every case different? I know that he hates the pain & this is the main reason for wanting to take this next step. I would imagine that he would have to finish this first round of chemo before the next step is taken???
Any knowledge in this area would be greatly appreciated.
Can someone give me some good questions for us to ask the doctor regarding any other treatmnet options?