Acibadem hospital in Maslak (Istanbul)

A friend of mine is considering bringing his father to Istanbul in order to receive a particular form of treatment for cancer at the Acibadem hospital in Maslak. He has asked me whether I had any feedback to give him regarding the hospital. I said, I didn't, but that I would make inquiries. Is there anyone on this forum who might have some insight or personal experience with the type of care my friend could expect to find there for his father? He is apparently interested in something called "radiation knife therapy" and is trying to decide whether to go to London or Istanbul. Any input would be greatly appreciated.