proton bean for lung CA with emphysema

My mom is starting SBRT for a stage 1 upper lobe NSC lung CA tumor very soon – the mold is being created (?) on Monday. The markers were placed on Friday. This has all happened quite fast and I am interested if anybody knows if proton beam can spare significant lung tissue damage relative to SBRT which is important because of her emphysema. Does the fact that markers have been placed already change any of this. She is supposed to start something with the mold on Monday so we are running out of time to make a change which she really doesn't want to make because it involves a 5 hour trip to the proton center, etc... THANKS!