Unmasking anxiety: a head-to-head comparison of open and closed masks in head and neck cancer radiotherapy

Background: Facemasks accurately immobilise patients with head and neck cancer (HNC) receiving radiotherapy (RT). However, such masks are associated with treatment related distress, a prognostic factor for poorer survival. Open masks offer increased comfort and patient satisfaction. We investigated whether open masks could immobilise patients without affecting treatment accuracy. Materials and methods: Over an 18-month period, all HNC RT patients with anxiety were offered open masks. Once 30 patients had completed treatment, set-up data was compared to patients in closed masks. The mean displacement and one-dimensional standard deviations (SD) of the mean, systematic and random set-up errors were calculated for translational directions: anterior-posterior (x), superior-inferior (y), medial-lateral (z). The mean and SD of the mean was calculated for rotational displacements. Mann-Whitney U was used to determine any significant differences between set- up data. Results: Sixty patients were included (30 open & 30 closed masks). There was no statistically significant difference found in the x (p = 0.701), y (p = 0.246) or z (p = 0.535) direction for the SD of the mean displacements between both masks. No statistically significant difference was found in the SD of means for rotational displacements. The calculated planning target volume (PTV) margin requirements were minimally less for the closed masks 3.5, 2.6, and 2.7 mm (x, y, z, respectively) versus 4.2, 3.2, and 3.7 mm, respectively, for open masks. Conclusion: Our study demonstrates that open masks maintain accuracy at levels comparable to closed masks in patients with anxiety. The minor difference in the calculated PTV margin could be rectified with daily on-line imaging or surface guided imaging.