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

Authors

Alice Albuquerque Institute of Radiation Protection and Dosimetry
Dr. Luiz Antônio Ribeiro da Rosa Institute of Radiation Protection and Dosimetry
Dr. Denison S. Santos Institute of Radiation Protection and Dosimetry

DOI:

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

Keywords:

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

Abstract

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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