Implementation of surface-guided radiotherapy for motion management in liver SBRT: A scoping review and clinical workflow development

Background: Stereotactic body radiotherapy (SBRT) is increasingly utilised for the management of primary and secondary liver cancers offering improved local control and survival outcomes. However, respiratory-induced liver motion presents significant challenges for accurate and safe treatment delivery. Surface-guided radiotherapy (SGRT) has emerged as a potential non-invasive motion management strategy, yet evidence supporting its use in this cohort is limited. Methods: A scoping literature review was conducted using PubMed, Scopus, and CINAHL Plus to identify studies describing liver SBRT motion management, excluding abdominal compression, fiducial markers, and MRI-linac approaches. Eligible studies were identified, with results categorised by motion management approach, breath-hold method, and image guidance modality. A multidisciplinary working group developed and implemented a liver SBRT workflow integrating SGRT for both free-breathing and end-expiration breath-hold (EEBH) techniques. Motion assessment, CT simulation, treatment planning, and delivery workflows were developed. Results: The literature review highlighted limited published data on the use of SGRT for liver SBRT. Motion assessment techniques varied between repeat 3D CT and 2D kV fluoroscopy, with assessment of reproducibility and consistency of breath-hold (BH) critical for identifying patients suitable for BH. Our centre adopted fluoroscopy-based motion assessment combined with SGRT, allowing real-time patient coaching and accurate positioning. SGRT provided streamlined workflow, and eliminated the need for additional motion management tools.Patients unable to maintain reproducible EEBH were treated with a free-breathing internal target volume approach. Conclusion: SGRT is a feasible and effective motion management strategy for liver SBRT, enabling reproducible EEBH leading to accurate and precise treatment delivery. It offers a non-invasive, integrated approach to patient positioning and intrafraction monitoring. Further prospective data is required to validate reproducibility of BH amplitude and clinical outcomes.