Changing the Face of Head and Neck Radiotherapy

Abstract

<h3>Purpose/Objective(s)</h3> Radiotherapy plays a key role in the of the management of head and neck cancer patients with approximately 80% of patients receiving RT at least once during their cancer journey. Immobilization of patients during radiotherapy treatment, is essential to ensure treatment accuracy, and requires the use of a facemask. However, masks are associated with significant treatment related distress and a phenomenon called "mask anxiety". Many patients have difficulty swallowing and breathing which makes a closed facemask even less tolerable. In order to improve patients' radiotherapy treatment experience, we piloted a "faceless" open mask in our department to investigate whether such masks could be used, to reduce patients' distress without impacting on treatment accuracy, by comparing set up data for full versus open masks. <h3>Materials/Methods</h3> Over an 18-month period, all head and neck cancer patients undergoing radical radiotherapy, with a history of anxiety or claustrophobia, were offered open masks. Once 30 patients had completed radiotherapy treatment with the open mask, we analyzed the set-up data by comparing this consecutive cohort of patients, to patients in standard closed masks treated during the same time period. Our standard institutional IGRT protocol includes daily CBCT for first 3 fractions, followed by weekly CBCT. The one-dimensional standard deviations (SD) of the systematic and random set-up errors were calculated for all three orthogonal directions (<i>x, y, z</i>). Mann-Whitney U and independent t-test were used to determine any significant differences between rotational set up data for open and closed masks. <h3>Results</h3> Sixty patients were included. Thirty patients had closed masks and thirty had open masks. The SD of the systematic error (reproducibility of treatment position) in mm was slightly less for closed mask than for the open mask in all directions (vertical 0.079 vs 0.106, lateral 0.068 vs 0.101, longitudinal 0.054 vs 0.080). The SD of the random error was less for closed than for open mask in vertical, 0.219 vs 0.225, and lateral,0.144 vs 0.174, directions. It was slightly more in the longitudinal direction (0.176 compared to 0.171). The margin requirements for the faceless mask were greater than the full mask. Margins for set-up uncertainty were 3.5, 3, and 3mm (Ant Post, Sup Inf and Right Left, respectively) for closed mask, and 4, 3, and 4mm respectively for open mask. There was no significant difference in pitch, roll and yaw between open and closed masks. <h3>Conclusion</h3> In this study, we have shown that open masks are able to maintain accuracy at levels comparable to closed masks and may be offered to patients suffering mask anxiety. However, a slightly larger PTV margin may be required. For open masks to become the standard of care for all head and neck patients, a larger randomized study should be performed. Customized head rests and real time intrafraction monitoring using 3-dimensional surface imaging could also be an advantage for this cohort of patients.