One of the hardest parts of removing brain a tumor is taking out the right amount of matter. You don’t want to take out too much brain matter, because ever piece is vital, but if you don’t take out enough of the tumor, then you risk having it grow back. Scientists have recently developed a way to use a laser guided robotic arm that enters the brain through a tiny hole in the skull, then use nanoparticles to remove the cancerous tumor, leaving the healthy cells untouched. The process is still go through clinical trials, but initial results are promising and could revolutionize cancer treatment.