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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BEBIG60Co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∧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∧分别是3.011×10-7 cGycm2h-1Bq-1和1.118 cGyh-1U-1,GZP (3)号通道60Co源的SK/A和∧分别是3.002× 10-7 cGycm2h-1Bq-1和1.110 cGyh-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 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 resuhs were well accorded with the standard.The air-kerma strength per unit activity (SK/A) and dose rate constant (∧)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 60Co source,the SK/A and ∧values were calculated as 3.011 × 10-7 cGycm2h-1Bq-1 and 1.118 cGyh-1 U-1 in channel l&2 and 3.002× 10-7 cGycm2h-1 Bq-1 and 1.110 cGyh-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.