Head Mask (RG421W) — Thermoplastic Positioning Mask for Radiotherapy Immobilization The Head Mask (RG421W) is a specialized thermoplastic head immobilization device used in radiation oncology to support precise positioning and stabilization of a patient’s head and neck during radiation therapy sessions. Manufactured from medical-grade thermoplastics that soften when heated and harden into a custom contour, the RG421W mask helps clinicians deliver radiation accurately to tumors while protecting healthy tissue. These masks are standard equipment in cancer treatment centers and radiotherapy departments. Patients are fitted by trained radiation therapists, and the mask remains part of their treatment setup to ensure reproducible positioning for every session. Because this is a clinical medical device, RG421W masks are obtained through medical equipment suppliers or facility procurement for professional healthcare use. Name: Head Mask (RG421W) Type: Radiotherapy Positioning Head Mask Material: Thermoplastic medical mask material Primary Use: Immobilization during radiotherapy / radiation treatment Prescription Required: Yes — clinical/professional use only