ESTRO 2024 - Abstract Book

S378

Beachytherapy - Physics

ESTRO 2024

The developed phantom methodology for HDR brachytherapy audit has been tested and it’s sensitivity to detecting deliberate positional and dosimetric errors has been verified and will be further investigated to determine an uncertainty budget. Future work aims to employ this methodology in an international multi-centre pilot study, before rolling it out as a regular service of the IAEA/WHO dosimetry audit program.

Keywords: Brachytherapy, Dosimetry, Audit

References:

1. Dimitriadis, A., Chelminski, K., Granizo-Roman, E., Abdulrahim, R., Azangwe, G., & Swamidas, J. (2023). PO-2167 Determining a universal reference plan geometry for high dose rate brachytherapy dosimetry audits. Radiotherapy and Oncology, 182, S1950-S1952.

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Digital Poster

Dosimetric impact of a model-based dose calculation algorithm in skin interventional radiotherapy

Elisa Placidi 1 , Bruno Fionda 2 , Enrico Rosa 3 , Valentina Lancellotta 2 , Antonio Napolitano 4 , Martina De Angeli 2 , Francesco Pastore 2 , Maria Antonietta Gambacorta 2 , Luca Indovina 1 , Luca Tagliaferri 2 , Marco De Spirito 1,3 1 UOC Physics for Life Sciences, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy. 2 UOC Oncologic Radiotherapy, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy. 3 Institute of Physics, Catholic University of Sacred Heart, Rome, Italy. 4 Medical Physics, Children's Hospital Bambino Gesu', Rome, Italy

Purpose/Objective:

Interventional radiotherapy (IRT) is a well-established radiotherapy technique capable of delivering high doses to tumors while sparing organs at risk (OARs). Currently, the certified dose calculation algorithm used is TG-43 [1]. New model-based dose calculation algorithms (MBDCA), such as Elekta’s advanced collapsed cone engine (ACE), have been introduced [2,3], although their clinical application is yet to be fully realized. This study aims to investigate two aspects of ACE: firstly, a comparison of dose distributions calculated with TG-43 and ACE for skin tumors, and secondly, an exploration of the impact of using a water bolus on the coverage of the clinical target volume (CTV) and OARs.

Material/Methods:

Ten treatment plans for high-dose-rate IRT were developed. All plans were initially calculated using the TG-43 algorithm and were subsequently recalculated using ACE. In addition, one of the treatment plans was assessed with both TG-43 and ACE, using ten different water bolus thicknesses ranging from 0 to 5 cm. To assess dose variations, the following dose-volume histogram (DVH) parameters were compared: D2cc for OARs and D100, D95, D50, V100, and V95 for CTV coverage.

Results: