Immobilization by the Gill-Thomas-Cosman frame in proton radiosurgery

A) The Gill-Thomas-Cosman (GTC) frame consists of three parts: 1) an impression of the patient's upper dentition mounted to the anterior aspect of the head ring, 2) a mold of the patient's occiput mounted onto the posterior frame, and 3) a biasing strap holding these two components firmly in place. B) The occipital mold from the original GTC frame. (b) Application of the Gill-Thomas-Cosman frame. During treatment, the GTC frame is rigidly fixed to the treatment couch in order to achieve patient immobilization.