Comparative evaluation of intraoral stent materials: dosimetric response analysis.

Abstract

Purpose. To evaluate and compare the dosimetric properties of various materials used in intraoral stents, with a particular focus on their interaction with a 6 MV photon beam in head and neck cancer radiotherapy.Materials and Methods. Experimental irradiation and computational simulation methods were employed to analyze the interaction of various materials with a 6 MV photon beam used in an intraoral procedure. A head phantom, cylindrical in shape and divided into 1 cm plates, was used along with circular PMMA plates and polystyrene to simulate an intraoral procedure. Radiochromic film (EBT3) was used to evaluate the dose-response of PMMA and PET-G materials with thicknesses of 1, 2, and 3 mm, irradiated under a 10 × 10 cm²field size at a 100 cm source-to-skin distance (SSD). The PENELOPE code was used to simulate the dosimetric properties of PMMA, PET-G, EVA, PDMS, and PVDF based on their chemical compositions.Results. A maximum divergence of 4.2% was observed between PET-G and PMMA at a thickness of 3 mm during the experimental procedure. Additionally, a maximum difference of 1.2% was noted when comparing the simulated percentage depth dose curves. Discrepancies of up to 10% were found between experimental irradiation and simulations in polystyrene regions, likely due to the sensitivity of the film to incident fluence. When comparing the simulated materials (PMMA, PET-G, EVA, PDMS, and PVDF), the largest divergence observed was 20% at the surface of the phantom and did not exceed 15% at depths under 10 cm, specifically between PVDF and PMMA. For all other materials, the divergence remained below 10% across all regions.Conclusions. The results suggest that all the materials evaluated for intraoral stent fabrication can be effectively analyzed using the simulation code. PET-G, EVA, and PDMS showed dose-response variations of less than 10%, which should be considered when calculating doses in the treatment system planning, as stents made from these materials may increase the dose to nearby organs.