This is an immobilization device used during radiation therapy for head and neck cancer to control the movement of the tongue and ensure reproducibility. It is made from Ethylene Vinyl Acetate (EVA) and polycarbonate (PC), posing no harm to the human body, and does not require CT HU calibration. Through patient customizing, it enables the immobilization of the upper and lower jaw, teeth, and tongue positioning for the optimization of treatment conditions. Tongue fixation can be adjusted at various angles, including left/right, up/down, and posterior positions.