MODEL RELEASED. Gamma knife radiation therapy. This Leksell Gamma Knife machine was invented in 1967 by Lars Leksell, a Swedish neurosurgeon. It is used to treat brain tumours with radiation therapy by precisely focusing 201 beams of gamma radiation on a particular point. The head is held in place by a box-shaped frame, attached to the head with four pins. The frame keeps the head still and acts as a reference point in determining exactly where the beams of radiation should converge. The radiation consequently has a minimal effect on surrounding areas. It is non-invasive and provides access to areas of the brain that cannot be reached by other techniques. Photographed at Tokyo Women's Medical University (TWMU), Japan.