A Monte Carlo-based dosimetric study of the GZP ⁶⁰Co source

Objective: To simulate and calculate the dosimetric parameters of the GZP ⁶⁰Co source that has been clinically used in high-dose-rate brachytherapy. Methods: The EGSnrc Monte Carlo software was used to simulate and calculate the dosimetric parameters of a well known BEBIG ⁶⁰Co source (Co0.A86). The results were compared with the actual parameters to verify the feasibility of this method. A Monte Carlo model of the GZP ⁶⁰Co source for high-dose-rate brachytherapy was established to simulate and calculate its dosimetric parameters in the same way. Results: For the BEBIG ⁶⁰Co source, the results were well accorded with the standard. The air-kerma strength per unit activity (S_K/A) and dose rate constant (A) deviated from the standard by 0.2% and 1.0%, respectively. The curves of the radial dose function g_L(r) and the anisotropy function F(r, θ) fit well. For the GZP ⁶⁰Co source, the S_K/A and Λ values were calculated as 3.011 × 10^-7 cGycm²h^-1Bq^-1 and 1.118 cGyh^-1U^-1 in channel 1&2 and 3.002 × 10^-7 cGycm²h^-1Bq^-1 and 1.110 cGyh^-1U^-1 in channel 3. The g_L(r), F (r, 0θ), and dose rate per unit air-kerma strength in a liquid water phantom were listed as the American Association of Physicists in Medicine recommended. Conclusions: The results can be used in planning system and quality control for the GZP ⁶⁰Co source. (authors)