ESTRO 2025 - Abstract Book

S3635

Physics - Quality assurance and auditing

ESTRO 2025

Conclusion: Quality assurance methods for SBRT/STAR remain heterogeneous among queried centres. Agreement was reached for ≈80% of the best practise recommendation statements. We anticipate that this consensus will contribute towards standardization and harmonization of radiotherapy machines and procedures for STAR treatments.

Keywords: STAR, Ventricular Tachycardia, Quality Assurance

References: [1] Grehn et al. STereotactic Arrhythmia Radioablation (STAR): the Standardized Treatment and Outcome Platform for Stereotactic Therapy Of Re-entrant tachycardia by a Multidisciplinary consortium (STOPSTORM.eu) and review of current patterns of STAR practice in Europe, Europace, April 2023

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Digital Poster Development of a remote dosimetric auditing method for single-isocentre multi-target stereotactic radiosurgery: the ESPRESSO multi-centre study Peter B Greer 1,2 , Andrew Dipuglia 1 , Benjamin Zwan 3 , Andrew Cousins 4 , Ashley Cullen 5 , Shih-Chi Lin 6 , Michael Lovelock 7 , Conor K. McGarry 8 , Juan Francisco Calvo Ortega 9 , Victoria Robinson 8 , Cameron Stanton 3 , Baozhou Sun 10 , Ching-Ling Ting 7 , Gemma Warner 4 , Seng-Boh Lim 6 1 Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, Australia. 2 School of Physical and Information Sciences, University of Newcastle, Newcastle, Australia. 3 Radiation Oncology, Central Coast Cancer Centre, Gosford, Australia. 4 Medical Physics, Christchurch Hospital, Christchurch, New Zealand. 5 Radiation Oncology, Lifehouse, Sydney, Australia. 6 Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA. 7 Radiation Oncology, Mount Sinai Hospital, New York, USA. 8 Radiation Oncology, Northern Ireland Cancer Centre, Belfast, United Kingdom. 9 Servicio de Oncología Radioterápica, Hospital Quirónsalud Barcelona, Barcelona, Spain. 10 Radiation Oncology, Baylor College of Medicine, Houston, USA Purpose/Objective: A remote dosimetric auditing method could assist with safe implementation of multi-target single-isocentre (MTSI) stereotactic radiosurgery (SRS) for low and middle-income countries. MTSI SRS delivers small high dose targets around the cranium. Dosimetric auditing of this high risk technique presents unique challenges as measurement techniques are time-consuming, resource intensive and require an onsite auditor with specialised equipment. This work involves an international consortium investigating measured dose-in-water, EPID images and treatment planning system (TPS) calculations to optimise an EPID-based method to audit SRS. Material/Methods: Output factors (OFs) for a set of jaw and MLC defined fields from 0.5x0.5 cm 2 up to 20x20 cm 2 were measured in water-phantom at 10 cm depth, 90 cm SSD at 8 institutions on TrueBeam HDMLC equipped linear accelerators at 6FFF energy. The dosimeters used for dose in water were either Razor diode or Microdiamond detectors for <= 4x4 cm 2 daisy-chained to CC13 ionisation chamber measurements for larger fields using corrections from IAEA TRS-483. The same fields were imaged with aS1200 EPID and converted to dose-in-water at the same depth and SSD as the measured data using the current auditing EPID-to-dose conversion model derived at a single centre 1 . TPS calculated doses for the fields were also obtained, all from Eclipse (V15.6.8 to 17.0.0). The OFs for water-tank and EPID were corrected taking into account the actual field-size determined from the EPID images.