摘要
目的通过测量Varian IX和23EX医用直线加速器60对和40对动态多叶准直器(dynamic multileaf collimator,DMLC)的叶片透射因子、叶片间漏射因子、叶片位置校正因子及内、外半影,探讨DMLC参数是否受X射线能量和叶片数目的影响,并探讨DMLC参数在治疗计划系统(treatment planning system,TPS)的必要性和重要性。方法采用Kodak X-Omat V胶片分析仪测量工具,分别对Varian医用直线加速器60对和40对的DMLC叶片透射因子、叶片间漏射因子、叶片位置校正因子及内、外半影这5种参数测量。并将测得的DMLC参数结果引入到TPS的原始机器数据中。在TPS中针对模体设计逆向调强计划,并在加速器上对夹有胶片的模体进行照射,对比分析胶片实测的剂量分布结果和TPS计算得到的剂量分布结果。结果对于相同叶片数目的 DMLC,X射线能量越大,参数值越大。对于相同的X射线能量,DMLC叶片数目越多,参数值越大。在TPS中引入测得DMLC参数后,TPS计算得到以及胶片实测得到的80%等剂量线面积重合度均大于95%,曲线的分离度均小于3 mm。结论DMLC参数均会受叶片数目以及加速器X射线能量大小的影响,但只要将测得的DMLC参数正确引入到TPS中进行,则实测得到的剂量分布与TPS计算得到的剂量分布均能满足高重合度和低分离度,从而满足临床治疗要求。
Objective To measure the parameters of dynamic multileaf collimator（ DMLC） including leaf transmission factor, between-leaf leakage factor, leaf position correction factor,inner and outer penumbra for 60 pairs of leaves in Varian IX medical linac accelerator and40 in Varian 23 EX,respectively,to analyze the effects of X-ray energy and leaf numbers on the DLMC parameters,whose importance is also analyzed in treatment planning system（ TPS）. Methods The five parameters of DLMC：leaf transmission factor,between-leaf leakage factor,leaf position correction factor,inner and outer penumbra are measured,and the results are imported into TPS. The inverse intensity-modulated radiation therapy（ IMRT） is designed for phantom in TPS,and the phantom with a film is irradiated on the accelerator couch,then the dose distribution is comparatively analyzed between the measured results on the film and TPS. Results As to the same number of DMLC leaves,the higher the X-ray energy,the bigger the parameters. As to the same X-ray energy,the more the DMLC leaves,the bigger the parameters. The area contact ratios of 80%isodose line got from both actual measurement on the film and TPS are higher than 95%,and the separation degree of the curves are both lower than 3 mm. Conclusions Although each DMLC parameter can be influenced by the leaf number and X-ray energy,the dose distributions of both actual measurement and TPS are capable of satisfying higher contact ratio and lower separation degree by guiding the measured DMLC parameters into TPS,which meet the clinical application requirement.
出处
《北京生物医学工程》
2015年第5期509-513,共5页
Beijing Biomedical Engineering
基金
国家自然科学基金(11475087)
江苏省博士后科研资助计划(1002012C)
中央高校基本科研业务费
青年科技创新基金(NS2014060)资助
关键词
加速器
DMLC
物理参数
测量
验证
accelerator
DMLC
physical parameter
measurement
verification
