ESTRO 2024 - Abstract Book

S114

Invited Speaker

ESTRO 2024

University Hospital Gasthuisberg, Dept. of Radiation Oncology, Leuven, Belgium

Abstract:

Brachytherapy (BT) treatment planning systems (TPS) are indispensable tools for computing the dose distribution and treatment time of brachytherapy patient plans. For a safe treatment it is essential that source data, calculation parameters, and planning functionalities affecting the TPS output are modelled and validated properly. Calculations can be based on either the TG-43 model (assuming dose absorption in water) or on the TG-186 model (taking into account a heterogeneous environment). The first part of the teaching lecture will focus on the commissioning of a brachytherapy TPS using the TG-43 based dose calculation algorithm. An overview will be given of the societal reports available to the users and the repositories where reference source data can be found. Several aspects of the commissioning process will be discussed, such as the verification of image sets and geometry aspects, source specification, dose calculation and applicator reconstruction.

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What every physicist should know about commissioning TG-43- and model-based treatment planning systems in brachytherapy

Javier Vijande

University of Valencia, Atomic, molecular, and nuclear physics department, Valencia, Spain

Abstract:

The integration of model-based dose calculation algorithms (MBDCAs) into brachytherapy offers an opportunity to improve dose accuracy and explore innovative treatment approaches. The collaborative efforts of AAPM, ESTRO, and ABG Task Group 186 (TG-186) provided guidance to early adopters. However, the commissioning details of these algorithms were broadly outlined, lacking specific quantitative objectives. Building upon their work, the Working Group on Model-Based Dose Calculation Algorithms in Brachytherapy was established by AAPM, ESTRO, ABS, and ABG with the specific goal of streamlining the commissioning process for incorporating MBDCAs into clinical treatment planning systems. Additionally, it empowers users to independently evaluate potential differences when transitioning from the current TG-43-based standard of clinical practice in treatment planning dosimetry to the utilization of an MBDCA. In 2023, a report titled "AAPM WGDCAB Report 372: A Joint AAPM, ESTRO, ABG, and ABS Report on Commissioning of Model-Based Dose Calculation Algorithms in Brachytherapy" by Beaulieu L et al. was published in Med Phys (2023; 50: e946–e960). This report introduces a field-tested approach to MBDCA commissioning, based on a set of well characterized test cases with reference Monte Carlo and vendor-specific MBDCA dose distributions available to clinical users. Several Test Cases are now freely accessible in the well-known IROC-Houston Brachytherapy Source Registry (https://doi.org/10.52519/00005). In this teaching lecture, we will provide the main elements for the commissioning of TG-186-based treatment planning systems in a clinical environment, using the different Test Cases available as illustrations.

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Technical advancements tailoring dose and volume