Simulation Study on the Dosimetric Parameters of Domestically Produced High-Dose-Rate Brachytherapy Ir-192 Source

[Background]: High dose rate (HDR) brachytherapy is a widely utilized treatment modality in modern clinical brachytherapy. In clinical practice, accurate dosimetric parameters for Ir-192 HDR brachytherapy sources are essential. Due to the variation in source designs, each model requires specific dosimetric parameters. Although there is extensive international research on the dosimetric parameters of Ir-192 sources, simulation studies focusing on the dosimetric parameters of HDR Ir-192 brachytherapy sources produced by the HTA Co., Ltd are relatively scarce in China.  [Purpose]:  This study aims to calculate the dosimetric parameters of a domestically produced HDR Ir-192 source by constructing a detailed structural model of the source using Monte Carlo simulation software, based on the dosimetric calculation methods recommended in the TG-43U1 report by the American Association of Physicists in Medicine (AAPM), and performing simulation calculations.  [Methods]: In this study, Monte Carlo software was used to simulate the Ir-192 brachytherapy source. To accurately conduct the simulation, a detailed structural model of the domestically produced high dose rate Ir-192 brachytherapy source was established within the Monte Carlo software. The dosimetric parameters calculated in the simulation include the dose rate constant, air kerma strength per unit activity, radial dose function, and anisotropy function.  [Results]: In this study, the simulated dose rate constant was found to be 1.105 cGy·h-1·U-1, with a difference of less than 1.2% compared to values reported in the literature. Additionally, the air kerma strength per unit activity was calculated to be 9.788×10-8 U·Bq-1, with a discrepancy of 0.23% compared to the literature values. Furthermore, the dosimetric parameters for the radial dose function and anisotropy function obtained in this study showed a high degree of consistency with corresponding data from existing literature.  [Conclusions]: The domestically produced Ir-192 source model established using the Monte Carlo software shows good consistency with the literature-reported dosimetric parameters, indicating that this model can be used for clinical practice applications of domestically produced Ir-192 sources and has certain guiding significance.