@lisaj63 good morning. Gamma knife is a procedure using a one time radiation treatment. I went in around 6:30am and walked out at 3:30pm. Feeling fine. The most important thing is finding a really good surgeon at a good teaching hospital. Forget community hospitals because they are closer. Fortunately I’m an hour away from Univ. of Pa. I was given anesthesia to put a halo on my head, so when I went through the procedure my head would be perfectly still. No problem. I believe that there are 180 rays shot into one spot to target the tumor. Recovery was easy. They took the halo off after I woke up. It was easy, no pain (I’m glad that they knocked me out to put it on). Like I said I walked out feeling good. Had several checkups afterwards. Now I am on a 1 year MRI to see the progress. They told me within the first year it might be a smidgen bigger, than it starts to shrink slowly and or the Gamma Ray stops it from growing. That’s why they do it before it reaches a certain size. Again, I would think that there are other factors involved with what procedure is to be done. The size, placement etc. good luck, the worry was worse than the procedure.