A newly developed patient fixation system using a dedicated mouthpiece and dental impression materials for head and neck radiotherapy: a preliminary study

Abstract

We evaluated the basic characteristics and efficacy of our newly developed patient fixation system for head and neck radiotherapy that uses a dedicated mouthpiece and dental impression materials. The present investigation demonstrated that with this system, the changes in the absorbed dose to water depending on the material of the mouthpiece were small, with a maximum of 0.32% for a 10-MV photon beam. For the dental impression material, we selected a silicone material with the lowest Hounsfield unit (HU) value that had little effect on the generation of artifacts and the quality of the X-ray beam. Multiphase magnetic resonance imaging (MRI) revealed that the head-up and -down motions in the thermoplastic shell without the mouthpiece were 5.76 ± 1.54 mm, whereas the motion with the mouthpiece decreased significantly to 1.72 ± 0.92 mm (P = 0.006). Similarly, the head-left and -right motion displacement decreased from 6.32 ± 1.86 mm without the mouthpiece to 1.80 ± 0.42 mm with the mouthpiece (P = 0.003). Regarding the tongue depressor function of the mouthpiece, the median distance from the hard palate to the surface of the tongue was 28.42 mm. The present results indicate that the new immobilization device developed herein that uses a mouthpiece and a thermoplastic shell is useful for suppressing patients’ head motions and tongue positions.

Novel tongue-positioning device to reduce tongue motions during radiation therapy for head and neck cancer: Geometric and dosimetric evaluation

“…In 2022, the interfractional head-up and–down motions in the thermoplastic mask with and without 3D printed tongue-positioning devices were investigated using magnetic resonance imaging [ 14 ]. It was revealed that head motions with the tongue-positioning devices decreased significantly compared to the motions without tongue-positioning devices [ 14 ]. In 2021, dosimetric characteristics and setup stability of a patient-specific semi-customized tongue-positioning device were compared with those of a standard mouthpiece.…”

“…In 2022, it was reported that the use of positioning stent to reduce the irradiation dose to the palate resulted in a reduction of radiation-induced oral mucositis on the palate [10]. Several three-dimensional (3D) printed customized tongue devices were suggested to take the patient-specific structures into account, and dosimetric efficacies were also reported [6][7][8][9][12][13][14][15][16]. In 2022, the interfractional head-up and-down motions in the thermoplastic mask with and without 3D printed tongue-positioning devices were investigated using magnetic resonance imaging [14].…”

“…Several three-dimensional (3D) printed customized tongue devices were suggested to take the patient-specific structures into account, and dosimetric efficacies were also reported [6][7][8][9][12][13][14][15][16]. In 2022, the interfractional head-up and-down motions in the thermoplastic mask with and without 3D printed tongue-positioning devices were investigated using magnetic resonance imaging [14]. It was revealed that head motions with the tongue-positioning devices decreased significantly compared to the motions without tongue-positioning devices [14].…”