S2890
RTT - RTT education, training, and advanced practice
ESTRO 2026
HFS) and pelvis-to-knees (feet-first supine, FFS). Setup displacements were recorded, but not applied if within a 0.5cm threshols and if within the skin flash, prioritizing the thoracic region during registration. All treatments were delivered with Beam Hold activated to verify intra-fraction stability. kV images were acquired before each isocenter was treated.
Digital Poster Highlight 4445 Implementation of TBI-VMAT with SGRT: Workflow Optimization and Imaging Reduction Sonia Bermejo Martínez 1 , Cristina Ansón Marcos 2 , Jéssica Jiménez Sánchez 1 , Míriam Mancera Soto 2 , Ainoa Vizuete Pérez 2 , Guillermo Gómez de Segura Melcón 2 , Noé Ventosa Lli 1 , Albert Clols Fuentes 1 , Helena Vivancos Bargalló 2 , Ana María Soto Cambres 1 , Eugènia Otero Pla 1 , Núria Farré Bernadó 1 , Gemma Sancho- Pardo 1 1 Radiation Oncology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 2 Radiation Physics and Radiation Protection, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain Purpose/Objective: To evaluate setup accuracy and workflow optimization in total body irradiation (TBI) delivered with volumetric modulated arc therapy (VMAT) using a surface-guided radiotherapy (SGRT) system, aiming to reduce imaging procedures while maintaining treatment precision. Material/Methods: We report the evolution of the workflow for the first seven patients (five pediatric and two adult) treated with myeloablative TBI-VMAT on a TrueBeam linear accelerator (Varian). Patients were treated with either a standard regimen of 12 Gy in six fractions of 2 Gy, administered twice daily, or within a reduced-intensity platform delivering 8 Gy in four fractions over two days. Treatment planning in Eclipse v15.6 (Varian) included 7–8 isocenters per plan and a 1.5 cm skin flash.Patients were positioned supine on a rotational board and immobilized with a vacuum cushion and thermoplastic mask. Initial setup was performed with the AlignRT (VisionRT) SGRT system, using a 3 mm / 2° tolerance. The Postural Video module was employed to ensure accurate positioning, with particular attention to the hands and feet (Figure 1).Setup verification initially (3 patients) included two extended CBCT acquisitions: chin-to-pelvis (head-first supine,
Results: Extended CBCT registrations showed discrepancies below the established threshold, allowing image- guided radiotherapy (IGRT) to be reduced to a single thoracic CBCT and a second CBCT at the pelvis junction (transition from HFS to FFS) while maintaining accurate multi-isocenter treatment delivery. This resulted in fewer imaging acquisitions per fraction compared with standard TBI-VMAT workflows.Registration shifts for all patients are shown in Figure 2. In both the thoracic and pelvic regions, displacements were within the predefined tolerance thresholds across all patients. No intra-fraction movement was detected with the SGRT system which was consistent with the kV images. Conclusion: In TBI-VMAT treatments, the SGRT workflow enables a decrease in CBCT acquisitions while maintaining precise and reproducible patient positioning, including challenging areas such as the hands and feet. It also provides intra-fraction motion monitoring. This ensures accurate dose delivery across multiple isocenters in both pediatric and adult patients. Keywords: TBI-VMAT, SGRT, Intra-fraction Motion References: Sandt M, Marcet S, Guesnel N, Claude L, Martel I, Biston MC. Implementation of Linac-based VMAT total body irradiation technique on Elekta platform using surface-guided radiation therapy. Phys Med. 2025 Mar;131:104940. doi: 10.1016/j.ejmp.2025.104940. Epub 2025 Feb 20. PMID: 39983594.
Made with FlippingBook - Share PDF online