ESTRO 2024 - Abstract Book

S4902

Physics - Quality assurance and auditing

ESTRO 2024

There was a large dose variation for OARs with either the lowest optimal constraints which did not have a high priority, or mandatory constraints but had scope to reduce dose further. There was less variation for constraints that were either very low and achievable, or very high and could not be reduced further due to target proximity. For the photon plans there was a 3-5 mm range in CTV-PTV margins, however this did not have an effect on the dose to OARs overlapping with PTVs as may be expected 2 .

Conclusion:

All centres were able to produce acceptable benchmark plans achieving the mandatory requirements of the trial. Compared to previous UK trials there was extensive OAR dose optimisation, in particular the contralateral parotid mean dose constraint was 20 Gy, lower than previous trials and achieved by all plans. Variation in OAR doses achieved by centres was observed. This may result from differences in techniques, treatment planning systems and algorithms, uncertainty margins and subjectivity in interpreting constraints.

Keywords: Radiotherapy trial QA, head and neck, proton

References:

[1] Thomson DJ, Cruickshank C, Baines H, Banner R, Beasley M, Betts G et al. TORPEdO: A phase III trial of intensity modulated proton beam therapy versus intensity-modulated radiotherapy for multi-toxicity reduction in oropharyngeal cancer. Clinical and Translational Radiation Oncology. 2023;38:147-154. https://doi.org/10.1016/j.ctro.2022.11.010 [2] Tyler JM, Bernstein D, Seithel M, Rooney K, Petkar I, Miles E et al. Quality assurance of dysphagia-optimised intensity modulated treatment planning for head and neck cancer. Phys Imaging Radiat Oncol. 2021;20:46 50. https://doi.org/10.1016/j.phro.2021.10.003

2500

Proffered Paper

Interim results of the prospective RTQA procedures for HALT (CRUK/16/020, EORTC 1702-LCG-ROG)

Daniel Portik 1 , Raguprakash Ratnakumaran 2,3 , Patricia Diez 4 , Rushil Patel 4 , Coreen Corning 1 , Gerard G Hanna 5,6 , Katharine Aitken 7 , Kevin Franks 8 , Matthew Hatton 9 , Veni Ezhil 10 , Rebecca Muirhead 11 , Charlotte Billiet 12 , Kate Elliott 4 , Mariana Kroiss 4 , Christy Toms 13 , Matthias Guckenberger 14 , Nicolaus Andratschke 14 , Fiona McDonald 2 1 European Organisation for Research and Treatment of Cancer (EORTC) Headquarters, Medical Department, Brussels, Belgium. 2 The Royal Marsden NHS Foundation Trust, The Lung Unit, London, United Kingdom. 3 The Institute of Cancer Research, Radiotherapy and Imaging Department, London, United Kingdom. 4 National Radiotherapy Trials Quality Assurance Group, Mount Vernon Cancer Centre, Radiotherapy Physics, London, United Kingdom. 5 Northern Ireland Cancer Centre, Department of Oncology, Belfast, United Kingdom. 6 Patrick G Johnson Centre for Cancer Research,