A dose of gamma rays from Elekta won't turn you into the Incredible Hulk, but it could make you feel like him. The company manufactures the Gamma Knife -- which isn't a knife at all but a chamber that delivers radiation therapy to treat tumors and cancer in the brain. The Gamma Knife was invented in 1968 by Elekta's founder, Dr. Lars Leksell, the father of radiosurgery. Elekta manufactures other non-invasive treatment systems, such as image-guided radiation therapy (IRGT) and particle therapy, used to treat cancer elsewhere in the body. Elekta was founded in 1972. Its products are used in more than 5,000 hospitals around the world.