[Usefulness of a radiolucent spacer in radiation therapy for cancer of the tongue].

A radiolucent silicone spacer was developed for use in interstitial irradiation for cancer of the tongue. It keeps about eight millimeters of distance between the lower gingiva and the lesion of the tongue, and the average radiation dose (TDF) to the lower gingiva was 45% of the minimal tumor dose in the lingular lesion. The total TDF value of the lower gingiva by both external and interstitial irradiation was between 66 and 114, which is not considered to be responsible for the occurrence of osteoradionecrosis of the mandible.