Brain surgery is one of the most dangerous operations carried out in hospitals today. Some tumours can be removed non-invasively with gamma rays, but the removal of larger tumours still requires an operation on the brain. As more precise instruments have become available, doctors have used ultrasound or blade- based instruments to remove tumours. But such techniques can easily destroy healthy as well as damaged tissue and, moreover, are very expensive to buy. Now Leon Turjanski from Argentina and Carl Fabian from Florida have patented an inexpensive surgical device that could help doctors distinguish between healthy and damaged tissue as they operate. (Patent 5779713).