Head and Neck Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_33_2771 - Use of 3-D Printed Custom Oral Stents to Improve Positioning and Reproducibility for Patients Treated for Head and Neck Cancer

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Use of 3-D Printed Custom Oral Stents to Improve Positioning and Reproducibility for Patients Treated for Head and Neck Cancer
R. Liang1, J. Lehnhardt2, C. Chang2, G. Roberts2, D. Gaudilliere2, W. Hara1, Q. T. Le1, and B. M. Beadle1; 1Department of Radiation Oncology, Stanford University, Stanford, CA, 2Plastic & Reconstructive Surgery, Stanford University, Stanford, CA

Purpose/Objective(s): The use of external beam radiation therapy (RT) to treat head and neck cancers (HNC) can induce significant short- and long-term toxicity. Immobilizing the region of treatment can greatly reduce the number and severity of these toxicities. By isolating the field of radiation, physicians can optimally and precisely irradiate the target tissues and spare adjacent healthy tissues. Custom intraoral stents can separate the maxilla from the mandible and immobilize targets to protect normal tissues. The primary purpose of this study is to explore the extent and reproducibility of immobilization using a custom 3-D printed mouth-opening stent by comparing reproducibility of dental metrics of patients that did and did not use custom stents throughout RT.

Materials/Methods: The cohort includes 20 patients with HNC (4 nasopharynx/nasal cavity and 16 oropharynx) treated with a custom 3-D printed mouth-opening tongue-depressing (MOTD) stents for simulation and RT. An additional 5 patients (all oropharynx) treated without any oral device were included as controls. The MOTD custom stents are made from dental impressions of the patient’s teeth, designed and manufactured to order by using a 3-D printing laboratory (RadTec Medical Devices, San Carlos, CA), and adjusted for tolerance prior to simulation. Anterior and posterior separation measurements were taken during the patient’s initial simulation and compared to those from weekly cone-beam CTs. The distance between the top and bottom teeth at midplane constitutes the anterior point. The distance between the posterior hard palate to the superior aspect of the base of tongue at midplane constitutes the posterior measurement. For each patient, the mean separation (cm), standard deviation (cm), and percentage variability was calculated for each of the timepoints through treatment.

Results: The MOTD group of 20 patients had a mean anterior separation of 1.98 cm with a standard deviation of 0.07 cm (range 0.03-0.12), representing a mean percent deviation of 3.7%. The mean posterior separation was 2.92 cm with a standard deviation of 0.1 cm (range 0.04-0.18), representing a mean percent deviation of 3.4%. The control group of 5 patients who had no intraoral devices had a mean anterior displacement of 0.3 cm with a standard deviation of 0.09 cm (range 0.05-0.14), representing a mean percent deviation of 24.9%. The mean posterior separation was 1.0 cm with a standard deviation of 0.25 cm (range 0.07-0.6), representing a mean percent deviation of 23.0%.

Conclusion: Our results suggest custom 3-D printed MOTD stents result in significantly increased and reproducible physical separations between the tumor target, within the PTV, and adjacent normal tissues that should be spared. This work suggests that there is a benefit in separation and immobilization for patients treated with a 3-D printed custom stent; future work will investigate the dosimetric significance of this intervention as well as its potential effect on acute and late toxicity in the two groups.

Author Disclosure: R. Liang: None. J. Lehnhardt: None. G. Roberts: None. D. Gaudilliere: None. W. Hara: Member; NCI Metastatic and Recurrent Head & Neck Task Forc. Q. Le: Research Grant; Amgen, NIH, Redhill. Travel Expenses; BMS. Stock; Aldea. president elect; American Radium Society. Head and Neck Committee Chair; RTOG NRG Cooperative group. B.M. Beadle: Research Grant; NIH.

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