A oral device for use in radiotherapy is disclosed. The device is a two piece adjustable mouthpiece for use during radiotherapy of the head and neck. The device provides immobilization of the tongue for accurate reproducible administration of radiation therapy. The device fits within the oral cavity of a patient and is maintained in position by a bite-member that fits over the maxillary teeth of the patient. The adjustable feature of the device allows the device to fit the mouth to accommodate differences in mouth cavities and bite profile.
