Purpose: Head and neck (HN) radiation therapy patients are typically immobilized with closed thermoplastic masks that cover the face and may cause discomfort. In this work, we examine the use of open masks for HN radiation therapy.
Methods and materials: Fifty HN patients were prospectively randomized into 2 groups (25 closed masks, 25 open masks). The open-mask group was monitored with surface imaging to evaluate intrafraction motion. Both groups underwent daily volumetric imaging. All daily images were rigidly registered to their respective planning images to evaluate spinal canal and mandible position as a check for interfraction posture change. Posture changes were determined by the amount the spinal canal and mandible contours from the planning images had to be expanded to cover the structures on each daily image set. The vector length (VL) of the intrafraction linear translations, spine, and mandible positions for each open-mask patient were checked for correlation with fraction number using the Pearson r value. All patients were given a weekly survey ranking anxiety and claustrophobia from 0 to 10 (0 = no issue, 10 = extreme issue).
Results: The mean VL for all open-mask patients was 0.9 ± 0.5 mm (1 standard deviation). Only 1 patient showed significant correlation between VL and fraction number. The mean contour expansions to cover the spine and mandible were 1.5 ± 0.9 mm and 1.8 ± 1.3 mm for the closed-mask group, and 1.6 ± 0.8 mm and 1.8 ± 1.1 mm for the open-mask group. Both groups showed similar behavior relative to fraction number. The mean anxiety and claustrophobia scores were 1.63 and 1.44 for the closed-mask group, and 0.81 and 0.63 for the open-mask group. The groups were not significantly different.
Conclusions: Open masks provide comparable immobilization and posture preservation to closed masks for HN radiation therapy.
Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.