I had radiation twice in my life to the same area, usually that doesn't happen. Both times, I can say that I didn't feel anything, oddly one time I swear I smelled something. But it's a quick procedure, takes longer to take my shirt off and get strapped down to the table. For me, they strapped my head down with one of those radiation masks. For you, I doubt it, simple in and out thing. The side effects build up over the first two or three weeks, then I started getting droopy, needed a nap. 4 and 5 weeks in, I was very brown, to almost black in that area, like a severe suntan on steroids. My mouth was hit, so I lost all my teeth, and am in the process of having them removed and dentures put in.
As always, your results may vary, but all in all, it's easier than chemo.