S2746
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
efficient data structure. Phys Med Biol. Aug 30 2022;67(17)3Oosterhof F, Guterres Marmitt G, Langendijk JA, Both S. O029 / #73 - TOWARDS AUTOMATED DOSE-GUIDED PATIENT TREATMENT ALIGNMENT QUALITY ASSURANCE AT CLINICAL TIMESCALE. International Journal of Particle Therapy. Jun 2024;12:100142. Keywords: dose-guided patient positioning, proton therapy Electronic Portal Imaging Devices (EPID)-Based In Vivo Dosimetry for VMAT Total Body Irradiation: Feasibility and Accuracy Francesca Greco 1 , Matteo Galetto 1 , Maria Vaccaro 1 , Gerardina Stimato 1 , Stefania Teodoli 1 , Andrea Fidanzio 1 , Elisa Placidi 1 , Enrico Rosa 1,2 , Patrizia Ranaldi 3 , Elisa Marconi 3 , Vincenzo Frascino 3 , Silvia Chiesa 3 , Elisa Meldolesi 3 , Maria Antonietta Gambacorta 3 , Marco De Spirito 1 1 Department of Radiology and Oncological Radiotherapy, UOC Fisica per le Scienze della vita, Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy. 2 Department of Theoretical and Applied Sciences, Università Telematica eCampus, Novedrate, Italy. Proffered Paper 4327 3 Department of Radiology and Oncological Radiotherapy, UOC Radioterapia Oncologica, Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy Purpose/Objective: This work establishes and clinically validates an in-vivo dosimetry (IVD) workflow using electronic portal imaging devices (EPIDs) integrated into VMAT total body irradiation (VMAT-TBI). Feasibility, accuracy, reproducibility and the capability of EPID- based IVD to identify anatomy-related deviations requiring adaptive review was evaluated. Material/Methods: Patients underwent VMAT-TBI in our institution, using multi-isocenter head-first arcs and static feet-first fields. Image guided employed cone-beam CT (CBCT) at every isocenter; six-degrees-of-freedom corrections were applied prior to delivery. During each VMAT arc, EPID transmission images were acquired and reconstructed in SunCheck PerFRACTION (Sun Nuclear) compared to treatment planning system predictions, using a global gamma analysis (7%/3 mm, threshold 10%) [1]. Region-wise IVD metrics (Head, Thorax, Lumbar, Pelvis) were compared with an institutional acceptance band of 95–105% . For patients outside tolerance, CBCTs were reviewed and planning CTs were modified to mimic observed anatomical changes; the original beams were recalculated to quantify dosimetric impact in delivery treatment.
References: 1Thummerer A, Zaffino P, Meijers A, et al. Comparison of CBCT based synthetic CT methods suitable for proton dose calculations in adaptive proton therapy. Phys Med Biol. Apr 28 2020;65(9):0950022Lee H, Shin J, Verburg JM, et al. MOQUI: an open-source GPU-based Monte Carlo code for proton dose calculation with
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