Background: The purpose of this project was to derive the brachytherapy dosimetric functions described by American Association of Physicists in Medicine (AAPM) TG-43 U1 based on high dose rate ¹⁹²I sources. Materials and Methods: The method utilized included both simulation of the designed Polymethyl methacrylate (PMMA) phantom using the Monte Carlo of MCNP4C and benchmarking of the simulation with thermoluminescent (TL) dosimeters. Results: The obtained results for the radial dose function and anisotropy function showed nominal errors of less than 3% between TL measurements and the MCNP4C results. Conclusion: It may be concluded that due to small observed errors and the large uncertainty associated with the high dose gradients near the source point the simulation results can be used for dose estimation.