Effectiveness of Newly Developed Water-Equivalent Mouthpiece during External Beam Radiotherapy for Oral Cancer

The objective of this study was to research the effectiveness of newly developed water-equivalent mouthpiece during external beam radiotherapy for oral cancer. In external beam radiotherapy for cancer of the tongue, floor of the mouth, and lower gingiva, it is possible to prescribe a low dose to the upper gingiva and hard palate at an open mouth position using a mouthpiece. However, the inhomogeneity correction resulting from the air cavity and the mobility of the tongue produced by an open mouth position should be considered. Therefore, a new mouthpiece was designed to be fixed by the dental arch, and the air cavity of the mouth can be filled with water-equivalent material. In 30 patients with previously treated oral cancer, the simulated homogeneity index of the calculated water-equivalent mouthpiece by a treatment-planning system was significantly better than that of a conventional mouthpiece (p = 0.004). This new mouthpiece facilitates excellent dose distribution while attaining immobilization of the tongue in patients with oral cancer.

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