UBC Theses and Dissertations
The fabrication of an acrylic repositioning stent for use during intensity modulated radiation therapy (IMRT) : a feasibility study Lee, Vincent Sung Kin
Objectives: Radiation therapy is one of the main treatment modalities for malignant head and neck cancers. To minimize the damage to normal tissues during radiation therapy, various methods of stabilization have been utilized, including thermoplastic facemasks and bite blocks. Our goal is to assess the feasibility of a customized oral repositioning stent and its potential benefits. Methods: Ethics Approval: Approval for this project was obtained through the BC Cancer Agency Research Ethics Board. Participants: 10 consecutive patients scheduled to undergo Intensity Modulated Radiation Therapy (IMRT) for cancers of the maxillary sinus, nasal cavity or oral cavity were recruited and consented to participate in the study. Radiation stent fabrication: Hard baseplate wax was used to create a customized wax pattern of the proposed acrylic stent at chair side and the customized wax pattern was processed in heat-cured clear hard acrylic overnight. Measuring the Stability of the Patient Position: Utilizing data from the daily KeV images, the relative stability of the patient setup was assessed. Monitoring of side effects: Participants completed a questionnaire to evaluate side effects. Assessments were performed at four time points at: baseline; 3 weeks (mid-treatment); last day of radiation (6-weeks); and 3-months post-IMRT. Results: A new workflow protocol has been developed and implemented at the BCCA. Patient stability data demonstrated mean vertical, longitudinal and lateral variations that were not statistically different when compared to two retrospective cohorts. Descriptive analysis of the questionnaire data seems to indicate a similar trend for self-reported oral symptoms as described in the literature. Conclusion: It is possible to fabricate customized repositioning stents for HN cancer patients without affecting their IMRT treatment timeline. In addition, while utilizing the customized repositioning stent we were also able to maintain patient stability comparable to prior protocols and within a range of clinical guidelines as no patients’ treatments were aborted. Acknowledgement: This project was supported by the American College of Prosthodontics’ (ACP) Education Foundation and ACP Research Committee.
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