Evaluation of cubic voxel effects on dose calculation for Iridium-192 high dose rate using TOPAS particle simulation

BACKGROUND: This study investigates the impact of voxel size on dose calculations for the FlexiSource iridium-192 (¹⁹²Ir) high-dose-rate brachytherapy source using the TOol for PArticle Simulation (TOPAS) Monte Carlo code. It aims to establish a new dataset for future research by determining TG-43 p...

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Bibliographic Details
Main Authors: Yacine El Attaoui, Zouhair Airouss, Aziz Oustous, Lhoucine Oufni
Format: Article
Language:English
Published: Via Medica 2025-01-01
Series:Reports of Practical Oncology and Radiotherapy
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Online Access:https://journals.viamedica.pl/rpor/article/view/106078
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Summary:BACKGROUND: This study investigates the impact of voxel size on dose calculations for the FlexiSource iridium-192 (¹⁹²Ir) high-dose-rate brachytherapy source using the TOol for PArticle Simulation (TOPAS) Monte Carlo code. It aims to establish a new dataset for future research by determining TG-43 parameters. MATERIALS AND METHODS: TG-43 parameters (radial function and anisotropy function) were calculated using 0.5 mm³ and 1 mm³ voxel sizes. Mean dose calculations were performed at various distances from the source. The ¹⁹²Ir spectrum from the National Nuclear Data Center (NNDC) was utilized. RESULTS: The measured air-kerma strength per unit source activity differed by 2.34% from consensus data. Radial function analysis showed consistent results, with 0.5 mm³ voxels deviating up to 1.78% near the source and 7% at greater distances. The 1 mm³ voxels showed similarities at greater distances (up to 1.52% deviation) but significant differences near the source (up to 20% deviation). Anisotropy function analysis revealed variations of 3–4% for angles < 7° and > 175° with 1 mm³ voxels, and 10–20% for angles < 12° and > 177° with 0.5 mm³ voxels compared to Carleton Laboratory for Radiotherapy Physics (CLRP) reference values. CONCLUSIONS: These findings validate the TOPAS Monte Carlo code's accuracy for dose calculation and emphasize the importance of voxel size selection. The generated dataset shows promise for future research efforts in brachytherapy dose calculations.
ISSN:1507-1367
2083-4640