Validation of dosimetric characteristics of the GammaMed Plus ¹⁹²Ir HDR brachytherapy source using the GATE Monte Carlo code

This study aimed to validate the dosimetric parameters of the ¹⁹²Ir GammaMed Plus source used in high-dose-rate (HDR) brachytherapy, using the Monte Carlo simulation code GATE (version 9.3), in accordance with the American Association of Physics in Medicine (AAPM) TG-43 protocol recommendations. The source was modelled inside a 40 cm diameter water-filled spherical phantom to accurately replicate clinical conditions. The dose rate constant, radial dose function g(r), anisotropy function \(F(r,\theta )\) , and the two-dimensional dose rate distribution matrix were calculated using the DoseActors modules. The results showed excellent agreement with reference data: the dose rate constant was \((1.1064 \pm 0.0003)\times 10^{-2}~\text {Gy}\cdot \text {h}^{-1}\cdot \text {U}^{-1}\) , with a maximum difference from values reported in the literature of 0.76%, and average deviations of 1.2% and 1.4% for g(r) and \(F(r,\theta )\) , respectively. These findings suggest that GATE provides reliable and accurate dosimetric estimations and may be a useful tool for dosimetric validation in research settings, particularly in heterogeneous media.