GZP型^60Co源剂量学参数的蒙特卡洛模拟

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

目的GZP型^60Co源高剂量率后装机在临床中已有应用，模拟计算GZP型^60Co源的剂量学参数。方法使用EGSnrc蒙特卡洛软件模拟计算已知的BEBIG ^60Co源（Co0．A86）剂量学参数，与其结果进行对比，验证方法的可行性。对GZP型高剂量率后装机^60Co源进行建模，用同样方法模拟计算GZP型^60Co源剂量学参数。结果对BEBIG ^60Co源，结果与标准数据吻合很好，单位活度空气比释动能强度SK／A相差0．2％，剂量率常数A相差1．0％，径向剂量函数gL（r）和各向异性函数F（r，θ））曲线吻合。计算得到的GZP型^60Co源（1、2）号通道的SK／A和A分别是3．011×10^-7 cGycm^2h^-1Bq^-1和1．118cGyh^-1U^-1，GZP（3）号通道^60Co源的SK／A和A分别是3．002×10^-7cGycm^2h^-1Bq^-1和1．110cGyh^-1U^-1，gL（r）、F（r，θ）和水模中单位空气比释动能强度的剂量率参照AAPM推荐列出。结论研究结果可用于GZP型^60Co源的计划系统中，也可以作为GZP型^60Co源的质量控制。

Objective To simulate and calculate the dosimetric parameters of the GZP ^60Co source that has been clinically used in high-dose-rate brachytberapy. 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 （SK/A） and dose rate constant （A） deviated from the standard by 0. 2% and 1.0%, respectively. The curves of the radial dose function gL（r） and the anisotropy function F （r, θ） fit well. For the GZP 6oCo source, the SK/A and Avalues were calculated as 3.011 × 10^-7 cGyem2h^-1Bq^-1 and 1.118 cGyh^-1U^-1 in channel 1＆2 and 3. 002×10^-7 cGycm^2h^-1 Bq^-1 and 1. 110 cGyb^-1U^-1 in channel 3. The gL（r） , F （r,θ） , 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.