Analysis of TG-43 dosimetric parameters for an Ir-192 HDR brachytherapy source using with the Geant4 toolkit

Alice Albuquerque; Luiz Antônio Ribeiro da Rosa; Denison Souza-Santos

doi:10.15392/2319-0612.2025.2974

Autores/as

Alice Albuquerque Instituto de Radioproteção e Dosimetria
Luiz Antônio Ribeiro da Rosa Instituto de Radioproteção e Dosimetria
Denison Souza-Santos Instituto de Radioproteção e Dosimetria

DOI:

https://doi.org/10.15392/2319-0612.2025.2974

Palabras clave:

Geant4, Ir-192 source, Brachytherapy, TG-43, formalism

Resumen

This study evaluated the dosimetric parameters of the Buchler G089 ¹⁹²Ir high-dose-rate brachytherapy source using the TG-43 formalism and Monte Carlo simulations with the Geant4 toolkit. The radial dose function and the anisotropy function were obtained for this source. For the radial dose function, a small discrepancy could be observed for larger radii. The dose rate constant (Λ) was also calculated in this study (1.114 cGy·h⁻¹·U⁻¹) showing a maximum relative difference of 0.45% when compared with reference values (1.119 and 1.115 cGy·h⁻¹·U⁻¹). The absorbed doses were obtained by positioning the source in the lowest voxel of the ICRP male phantom prostate and benchmarked against previous studies. For comparison criteria, the Amersham 6711-Oncoseed ¹²⁵I source was also modeled and inserted in the same position of the prostate. Additionally, the dose enhancement effect due to the presence of gold nanoparticles (GNPs) was analyzed for the ¹⁹²Ir source, considering a homogeneous concentration of 30 mg·g⁻¹ in a tumor region simulated in the peripheral zone of the prostate. An approximately 18.5% increase in the absorbed dose was observed in this region, in agreement with results from previous studies.

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