125I粒子源剂量计算参数模拟研究  

Monte Carlo Simulation of Dose Calculation Parameter of Radioactive 125I Brachytherapy Source

作　　者：刘川凤 宋明哲[1] 王红玉[1] 倪宁[1] 魏可新[1] 刘蕴韬[1] LIU Chuanfeng;SONG Mingzhe;WANG Hongyu;NI Ning;WEI Kexin;LIU Yuntao(Radiation Metrology Division,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院计量测试部,北京102413

出　　处：《原子能科学技术》2020年第11期2217-2222,共6页Atomic Energy Science and Technology

基　　金：中国原子能科学研究院基础科研项目资助(BJ19001112);中国原子能科学研究院院长基金-青年英才培育基金资助项目(YC201914)。

摘　　要：国产125I粒子源的银棒末端结构为直角型,与典型的6711型粒子源结构略有不同,结构不同会对剂量计算参数产生一定影响。本文针对国产粒子源结构,利用蒙特卡罗方法计算美国医学物理学家协会(AAPM)在TG43-U1报告中推荐的剂量计算参数,并分析研究银棒末端结构对剂量计算参数的影响。模拟得到国产125I粒子源剂量率常数为0.955 cGy·h^-1·U^-1(空气比释动能强度基于点探测器计算得到),与TG43-U1推荐值较接近,两者仅相差1.03%,更加精细地计算了在源中垂线0.05~10 cm(1 cm间隔)范围内的径向剂量函数,拟合得到较好的经验公式,得到在0°~90°(5°间隔)、距源中心0.25~7 cm(2 cm间隔)范围内的二维各向异性函数,通过对比分析得到银棒末端为直角型结构时的二维各向异性函数在r=0.25 cm处会引起驼峰区。The end of silver rod of the domestic 125I brachytherapy source is right angle type,which is slightly different from the typical model of 6711 125I brachytherapy source.And it can have influence on the dose calculation parameters.Based on the structure of domestic 125I brachytherapy source,dose calculation parameters which are recommended by AAPM TG43-U1 were calculated by Monte Carlo method.The influence of the end of silver rod on the dose calculation parameters was studied.The simulation result of dose rate constant is 0.955 cGy·h^-1·U^-1 when the air kerma strength was calculated by the point detector,and the difference with the result of the TG43-U1 is within 1.03%.The radial dose function g(r)in the range of 0.05-10 cm at the transverse axis was calculated precisely.Then empiric equation was acquired by curve fitting.2D anisotropy function F(r,θ)was calculated in 0°-90°and 0.25-7 cm.The source of the right angle structure of the end of the silver rod would cause a hump area of 2D anisotropy function when r equals 0.25 cm.

关 键 词：125 I粒子源 剂量 MCNP5 

分 类 号：TL84[核科学技术—核技术及应用] TB98[一般工业技术—计量学]