S2217
Physics - Intra-fraction motion management and real-time adaptive radiotherapy
ESTRO 2026
Digital Poster Highlight 1190 Surface imaging to remove the mask - Results from the SMART1 clinical trial Youssef Ben Bouchta 1,2 , Chindhu Sundaram 3 , Daniel Truant 4 , Jonathan Sykes 4 , Mark Gardner 1 , Haryana Dhillon 3 , Purnima Sundaresan 4 , Paul Keall 1 1 Faculty of Medicine and Health, University of Sydney, Sydney, Australia. 2 The Adem Crosby Cancer Centre, Sunshine Coast University Hospital, Birtinya, Australia. 3 Psycho-Oncology Cooporative Research Group, University of Sydney, Sydney, Australia. 4 Radiation Oncology Network, Western Sydney Local Health District, Blacktown, Australia Purpose/Objective: Thermoplastic masks used for immobilisation during head and neck (H&N) cancer radiotherapy have been shown to negatively impact patient experience[1]. The SMART1 clinical trial aims to evaluate the feasibility and acceptance of surface-guided mask-free H&N radiotherapy. Material/Methods: Twenty-one patients were recruited as part of the SMART1 trial. Each participant was treated as per standard-of-care with addition of a 5-minute surface imaging session prior to the acquisition of the planning CT and a 20-minute surface imaging session conducted at the end of one of the final few treatment fractions. The imaging sessions were designed to simulate an SGRT-only clinical workflow and surface images were acquired using the Remove the Mask surface imaging system which has been shown to meet the international guidelines for accuracy[2]. Motion traces were analysed to count the number of gating events that would have occurred in an SGRT- only workflow. Gating threshold was set to 2mm/2deg for over 5 seconds. Participants completed the Depression, Anxiety and Stress Scale(DASS-14) questionnaire[3] and four study-specific questions before and after the imaging session.
Results: Principal patient motion during the imaging session could be characterised by a slow drift, however some patients exhibited periodic motion and others sudden shifts. Large sudden shifts occurred more frequently towards the end of the imaging session than near the beginning. The median number of gating events recorded per session was 3, ranging from 0 to 23. Overall, participants expressed a preference for the mask-free treatment option compared to treatment with 68% feeling comfortable during the mask-free session compared to 21% during treatment with the mask.
Conclusion: The results of the SMART1 trial demonstrates that surface-based motion gating for H&N radiotherapy treatment is feasible for most patients, and that the predominant motion for head-and-neck patients during RT treatments without the mask is a slow drift. The results from the SMART1 trial also indicated strong patient acceptance of mask-free treatment with most participants expressing lower stress and anxiety and being more comfortable during treatment with
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