ESTRO 2025 - Abstract Book

S3691

Physics - Quality assurance and auditing

ESTRO 2025

Conclusion: This funding initiative has proven highly effective in boosting trial participation, development, and collaboration. This success provides a framework for future grant applications that will aim to secure funding for additional dedicated physicist time. The establishment of a national RTQA programme, with increased medical physics funding should allow improved equity of access to clinical trials in Ireland by supporting more radiotherapy departments across the island in their endeavours to open IIT’s and international trials in their clinics.

Keywords: Clinical Trials, National Collaboration, IRROG

References: Abbott et al. The role of medical physics experts in clinical trials: A guideline from the European Federation of Organisations for Medical Physics. Phys Med 2024;126:104821 E.Miles et al. The National Radiotherapy Trials Quality Assurance Group- Driving up Quality in Clinical Research and Clinical Care J Clin Oncol 2024;36:273-277 J M Moran et al. Executive Summary of AAPM Report Task Group 113: Guidance for the physics aspects of clinical trials J Appl Clin Med Phys 2018;19:335-46

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Proffered Paper A virtual audit of dose to medium radiotherapy TPS calculations in the UK Joe R Whitbourn 1 , Nick Harding 2 , Usman Lula 3 , Chris South 4 , Vanya Staykova 5 , Catharine H Clark 6 , Mohammad Hussein 7 1 Medical Physics, South Tees Hospitals NHS Foundation Trust, Middlesbrough, United Kingdom. 2 Radiation Physics, Hull University Teaching Hospitals NHS Trust, Hull, United Kingdom. 3 Medical Physics, University Hospitals Birmingham, Birmingham, United Kingdom. 4 Radiation Physics, Royal Cornwall Hospitals NHS Trust, Truro, United Kingdom. 5 Medical Physics, Guys and St Thomas' NHS Foundation Trust, London, United Kingdom. 6 Radiotherapy Physics, University College London Hospitals NHS Foundation Trust, London, United Kingdom. 7 Chemical, Medical & Environmental Science, National Physical Laboratory, London, United Kingdom Purpose/Objective: Most treatment planning systems now offer Type C dose calculation algorithms that can transport and score dose in-medium (Dm) and many centres are now switching from dose-to-water calculations. As part of the development of national guidelines for the verification of Dm calculations we have undertaken a virtual dose audit of the calculation of Dm in different TPSs implemented in UK centres. Material/Methods: A synthetic DICOM dataset was distributed to radiotherapy centres in the UK. The resulting virtual phantom (Fig. 1) consists of a 30x30x30cm outer region with an inner 5x5x5cm centred at 10cm depth. For scoring average dose at 10cm depth, a 0.125cm 3 scoring region-of-interest was included. Centres followed standardised instructions to change the outer region and inner insert material with density assignments for water and different biological tissues (as defined in ICRU-44) and calculate the dose for a 10x10cm 2 field with isocentre set at 10cm depth for 6MV (optional data was collected for other beam energies). For reference, the first permutation assigned water to the full phantom. Corresponding Monte-Carlo (MC) calculations at 6MV were performed using EGSnrc as a comparison. To account for differences regarding MU definition, calculated doses for different material permutations were normalised to the dose calculated in the full water phantom.