I sometimes visit Duke's medical school library. And they have cases in the hallways that display a collection of early neurosurgical tools, including several handmade head frames with various verniered angle scales, etc, for accurately reaching some part of the brain. It would be easy to mistake some of them for medieval torture devices. This video describes a next evolution in the goal to be able to treat some problematic part of the brain accurately with the most minimal impact on surrounding structures.
Regards,
Rob
PS: My favorite new technology for treating brain tumors involves training the body's immune system to attack the tumor cell-- no intrusive treatment required. This is done by identifying a structure on the surface of the tumor cell that is not found on the normal cells, and then training immune cells with a "vaccination" to attack only the tumor cells.