A non-sterile device intended to be used to position and immobilize a patient’s head for reproducible positioning during radiation treatment planning, stereotactic radiotherapy (SRT), and stereotactic radiosurgery (SRS), on all parts of the brain, head, and neck. It is in the form of an arched frame to which can be attached various components (e.g., mouthpiece, nasion cushion) that non-invasively contact the patient to serve as points of reference, and which is typically attached to a base plate, couch top, or overlay. This is a reusable device.