Dosimetric and reproducibility assessment of intraoral immobilizers for oral radiotherapy

Radiotherapy is a standard treatment for oral cavity cancers, but it often induces toxicities that compromise quality of life. Intraoral immobilization devices help mitigate these effects by minimizing patient movement and reducing unnecessary radiation dose to organs at risk and improving the reproducibility of fractionated radiotherapy sessions. Currently, intraoral prostheses are commonly fabricated from polystyrene or polymethyl methacrylate (PMMA), each with limitations: polystyrene deforms easily during treatment sessions, while PMMA, although more rigid, has high production costs, restricting access for many patients. Polyethylene terephthalate glycol (PETG), a material widely used in dental appliances, represents a promising alternative for the fabrication of intraoral prostheses. This study simulated a head and neck radiotherapy treatment using a prototype skull irradiated with a 6 MV photon beam. Three immobilizers were fabricated from polystyrene, PMMA, and PETG. The performance of the PETG device was evaluated using dose–volume histogram (DVH) analysis and by comparing doses calculated with the treatment planning system (TPS) to those measured experimentally with EBT3 radiochromic films. The PETG immobilizer produced less dose scattering than PMMA and, unlike polystyrene, provided sufficient positional stability to enable accurate reproduction of the anatomical position from computed tomography. This precision supports improved target volume delineation, reduces treatment-related toxicities, and ultimately enhances patient quality of life. Consequently, PETG emerges as a viable alternative to the traditionally used materials, PMMA and polystyrene. • PETG intraoral immobilizer ensures precise anatomical reproducibility and reduces radiation dose scattering compared to PMMA and polystyrene. • Experimental validation with DVHs and radiochromic films confirms immobilizer stability and effectiveness in head and neck radiotherapy. • PETG offers an alternative material for intraoral prostheses, improving patient quality of life.