ESTRO 2025 Congress report
By the ESTRO dosimetry and quality assurance focus group
Results of several multicentric studies were presented during this year’s ESTRO congress either in a dedicated session entitled “Advancing quality by multicentre collaboration” or spread across the congress.
A multi-centre analysis of patterns of practice, treatment plan quality and dose delivery accuracy was presented for single-isocentre/multi-target (SIMT) radiotherapy by Benedikt Thomann (University Medical Center Freiburg, Germany). Results of end-to-end tests and surveys showed that experience and quality assurance were the key drivers of high treatment accuracy. His detailed study is a foundation for guidelines to support centres as they start SIMT treatments.
Presenting on behalf of the Institute of Physics and Engineering in Medicine, the UK medical physics professional body, and the National Physical Laboratory, Joe Whitbourn (The James Cook University Hospital, Middlesbrough, UK) described a described a virtual audit of dose to medium radiotherapy treatment planning system calculations in the UK. By assigning various material types to a 5x5x5 cm3 volume inserted in a larger cube, he showed that for most configurations, calculations were within ± 2% agreement with Monte Carlo. His presentation highlighted the need to establish best practice in how dose-to-medium algorithms should be commissioned, calibrated and audited. This topic is on the road map of the ESTRO dosimetry and quality assurance focus group for 2025!
The Italian Association of Medical Physicists, which is very active in small field dosimetry, was represented by Serenella Russo (Azienda USL Toscana Centro, Florence, Iraly), who reported results from a large multicentre intercomparison of small field dosimetry using a new plastic scintillator detector. She determined benchmark data by fitting the variation of field output factor against effective field size and showed high inter-centre consistency through the use of the plastic scintillator .
Following preliminary results presented last year (https://bit.ly/3WhaZam), Sabeena Beveridge (Australian Radiation Protection And Nuclear Safety Agency, Australia) showed the impact of suboptimal process steps in film dosimetry. Her group had designed an audit that evaluated the accuracy of film dosimetry processes, and the group tested it through an international pilot study. A large variability (>10%) was observed among centres, but this was reduced when all films were processed using the same software. A residual variation of 2.3% was observed when films were scanned on a single scanner. The findings highlighted the importance of quality assurance throughout the film process.
Finally, promising results from the multicentric evaluation synthetic CT ready for clinics (MESCAL) project were presented by Davide Cusumano (Mater Olbia Hospital, Italy) for pelvis and brain MR-only workflows. His team aims to provide tolerances in terms of image analysis, dose accuracy and shift estimation to support physicists to implement new synthetic CT solutions safely in their clinical practice. Final results are expected at the end of the year!
Stephane Dufreneix
Medical physicist, Institut de Cancerologie de l’Ouest (Cancer Institute of the West), Angers, France
Member of ESTRO dosimetry and quality assurance focus group