ESTRO 2025 - Abstract Book

S3256

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2025

2412

Digital Poster Automated Deep Inspiration Breath-Hold (DIBH) in Breast Radiotherapy: A Comprehensive Assessment of the VitalHold System on the Radixact Platform Paul RETIF 1,2 , Abdourahamane DJIBO SIDIKOU 1 , Julien GRIBELBAUER 1 , Anwar AL SALAH 1 , Estelle PFLETSCHINGER 1 , Xavier MICHEL 3 1 Medical Physics Unit, CHR Metz-Thionville, Metz, France. 2 CRAN, CNRS, Université de Lorraine, Nancy, France. 3 Radiotherapy-Brachytherapy Department, CHR Metz-Thionville, Metz, France Purpose/Objective: To evaluate the performance of the VitalHold module for automated Deep Inspiration Breath-Hold (DIBH) treatment on the Radixact platform, focusing on its dosimetric accuracy and responsiveness to respiratory motion. Material/Methods: A Delta4 Phantom+ system with customized 3D-printed breast add-ons was used to simulate a clinically relevant setup for DIBH. A treatment plan was created with 40 Gy in 15 fractions using TomoDirect. The Phantom was coupled with the HexaMotion motion platform to replicate a breath-hold pattern with 2 cm amplitude and 8.84 seconds duration. The Radixact treatment unit with the VitalHold module was employed for automated beam delivery, using gating thresholds ranging from 2 to 25 mm (non-gated delivery). Respiratory motion was monitored with the Catalyst+ HD SGRT system. Dose distributions were measured with the Delta4 Phantom+ and analyzed using various gamma criteria. Results: The measured respiratory curve closely matched the simulated motion, with amplitude differences under 0.1 mm and cycle variations of 0.1 seconds. Minor artifacts affected gating accuracy by less than 0.7 mm. Gamma pass rates for 2 to 5 mm gating tolerances were ≥ 95%, indicating high system accuracy (Figure 1). Gating thresholds over 5 mm showed decreased but acceptable performance, while non-gated delivery yielded unacceptable gamma pass rates.

Figure 1 Values of the local gamma pass rates measured with the Delta4 Phantom+ detector for various dose thresholds (2% to 5%), DTA values (2 mm to 5 mm) and gating tolerances.