ESTRO 2024 Congress report

Dosimetry and quality assurance (QA) for brachytherapy were well-represented at the ESTRO conference again this year. The brachytherapy track was initiated with a QA teaching lecture on the commissioning of TG43 and model-based treatment planning. Here Marisol De Brabandere presented the new guidelines that are currently in preparation from the brachytherapy physics QA system (Braphyqs) working group for the commissioning of TG43-based treatment planning systems. The guidelines are to replace the current guidelines, which are more than 20 years old and were introduced before 3D treatment planning was performed in brachytherapy. The guidelines will contain a series of tests to be performed during commissioning; these were presented by Dr De Brabandere. Then Javier Vijande presented new recommendations on how model-based dose calculation algorithms should be tested. This testing included a comparison with both TG43 dose distributions and Monte Carlo simulations, and Dr Vijande presented some test cases that had been designed by the group.

Furthermore, there were two presentations on brachytherapy QA services during the conference, one from the International Atomic Energy Agency/World Health Organization (IAEA/WHO) and another from the German Metrology Insititute, PTB. Alexis Dimitriadis presented a new postal dosimetry audit service for high-dose-rate brachytherapy. The audit was developed by the IAEA/WHO with the aim of providing an auditing service for low- and middle-income countries. Dr Dimitriadis presented results from a test of the methodology, which showed high accuracy that would enable detection of dosimetric errors of >2% and positional errors of >1mm. Thorsten Schneider (PTB) highlighted the importance of using spectrometry to account for low-energy photons during calibration of low-dose-rate seeds, and he explained how they performed spectrometry measurements at PTB.

There were also two presentations on in-vivo QA. Christoph Bert gave an overview of ongoing in-vivo QA studies. The talk was separated into in-vivo dosimetry and electromagnetic tracking for in-vivo QA. The focus in both cases was on the tracking of the source and the detection of positional errors. Studies in which the brachytherapy source was tracked with either a point dosimeter, a flat panel detector or electromagnetic tracking were presented. In all cases, the positional accuracy was in the order of 1mm. All presented studies were post-treatment analyses and Dr Bert finished by discussing the options for real-time in-vivo QA. In line with this, Teun Van Wagenberg gave the ESTRO-Elekta Brachytherapy award presentation on in-vivo tracked source positions with a flat panel detector. He showed how the tracked source positions might be used to determine deviations in dose-volume histogram parameters in real time, which would enable a direct comparison of clinically relevant parameters during treatment.

Jacob G. Johansen

Aarhus University Hospital

Aarhus, Denmark
ESTRO dosimetry and quality assurance focus group

Email: jacjoa@rm.dk

LinkedIn: www.linkedin.com/in/jgjohansen