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Standard immobilization for fractionated cranial radiotherapy is a closed thermoplastic mask, which allows for stable and reproducible patient positioning. This randomized trial investigated patient comfort and preference of open-faced masks compared to closed masks in patients undergoing partial or whole brain irradiation.

In this single-centre prospective randomized self-controlled trial, patients were treated sequentially with two immobilization masks and identical treatment plans, each used for 50% of the prescribed treatment. The order in which the masks were used was decided using crossover randomization.

The primary endpoint was patient comfort. Participants completed a Visual Analogue Scale (VAS) assessment after the first fraction and weekly thereafter, scoring separately their levels of each discomfort, anxiety and pain on a 10-point scale. Where present, patients indicated the anatomical location of pain on a diagram. On the last fraction, patients reported their mask of preference.

The secondary endpoint assessed inter- and intra-fraction stability between the masks. Inter-fraction set-up uncertainties were assessed using daily orthogonal kV imaging. An SGRT system was used with the open-face masks to report intra-fraction motion and aid patient positioning. Intra-fraction mask stability was assessed using kV imaging once weekly post-treatment.

A total 30 patients with primary or secondary brain tumors were registered to the trial, with 29 completing treatment to a median radiation dose 54Gy, range 30-60Gy. Discomfort VAS scores were significantly lower for open-face masks (mean VAS score 0.5, standard deviation [SD] 1.0) compared to closed (mean VAS score 3.3, SD 2.9), P<0.0001 (Fig.1.). Mean VAS score for anxiety (0.2 [SD, 0.6] vs. 1.2 [SD 1.8] for closed masks) and pain (0.2 [SD 0.6] vs. 1.7 [SD 2.5] for closed masks) were also significantly lower for open-face masks, P<0.0001. Closed masks were associated with significantly increased discomfort in infraorbital (P<0.001) and maxillary (P=0.02) areas. 18 of 20 (90%) participants indicated that they preferred the open-face mask over the closed mask. The remaining participants gave no indication of a preference. Mean inter-fractional longitudinal, roll and yaw shifts were significantly larger for open-face masks: 2.3±5.8 mm, 0.8±0.60 and 0.8±0.70, respectively versus 1.7±1.7 mm, 0.7±0.60 and 0.8±0.60 for closed masks (Table 1.). No significant difference in intra-fraction variability was observed.

This randomized trial showed significantly reduced patient discomfort, anxiety and pain for the use of open-face masks as compared to traditional closed-face masks. No significant difference in intra-fractional stability was observed. Open-face masks could be considered as the preferred method of immobilization for fractionated cranial radiotherapy.