多叶准直器重力效应对调强放射治疗剂量的影响研究  

Study of dose variations induced by MLC weight effect for IMRT delivery

作　　者：卢晓光[1] 王峻峰[1] 刘飞[1] 李定宇[1] 梅齐[1] 胡广原[1] 

机构地区：[1]华中科技大学同济医学院附属同济医院肿瘤科,武汉430030

出　　处：《医疗卫生装备》2017年第3期90-93,共4页Chinese Medical Equipment Journal

基　　金：湖北省自然基金面上项目(2014CFB366)

摘　　要：目的:研究多叶准直器重力效应对调强放射治疗(intensity-modulated radiation therapy,IMRT)剂量的影响,为临床治疗提供参考。方法:利用MatriX X二维电离室矩阵测量IMRT射野在不同机架和准直器角度下等中心平面的剂量,以3%/3 mm和1%/1 mm为γ通过率分析标准,比较机架角度G=270和0°下相同射野的剂量分布。结果:10 cm×10 cm射野下,3%/3 mm的γ通过率均超过99%,1%/1 mm的γ通过率接近95%。在3%/3 mm标准下,当准直器角度C=0°时,静态调强射野的平均γ通过率为(96.46±0.33)%,动态调强射野的平均γ通过率为(94.67±0.54)%;当C=90°时,静态调强射野的平均γ通过率为(94.59±0.47)%,动态调强射野的平均γ通过率为(92.60±0.52)%。在1%/1 mm标准下,当C=0°时,静态调强射野的平均γ通过率为(89.83±1.06)%,动态调强射野的平均γ通过率为(85.84±0.57)%;当C=90°时,静态调强射野的平均γ通过率为(86.91±1.71)%,动态调强射野的平均γ通过率为(83.89±0.69)%。结论:重力效应会影响IMRT剂量,而且对动态调强射野的影响比静态调强射野更大。Objective To evaluate dose variations induced by gravity of multi-leaf collimator to provide references for clinical intensity-modulated radiotherapy.Methods Two-dimensional dose distributions in the central plane of IMRT fields were measured by use of a 2D ion chamber array.All measurements were repeated at two collimator angles（C=0 and 90°）,for each of the following gantry angles：G=0 and 270°.Comparisons were made to dose distributions generated at G=0°and their differences were analyzed using gamma index analysis（3%/3 mm and 1%/1 mm）.Results Under the radiation field of 10 cm×10 cm,the gamma passing rate was higher than 99%for 3%3 mm anch close to 95%for 1%/1mm Under a 3%/3mm error standard,the average matching rate for stepshoot fields was（96.46±0.33）%and for DMLC fields was（94.67±0.54）%at C=0°;The average matching rate for stepshoot fields was（94.59±0.47）%and for DMLC fields was（92.60±0.52）%at C=90°.Under a1%/1mm error standard,the average matching rate for stepshoot fields was（89.83±1.06）%and for DMLC fields was（85.84±0.57）%at C=0°;The average matching rate for stepshoot fields was（86.91±1.71）%and for DMLC fields was（83.89±0.69）%at C=90°.Conclusion MLC weight effect affects IMRT delivery dose,and DMLC fields are more sensitive to gravity than stepshoot fields.

关 键 词：多叶准直器 重力效应 调强放射治疗 剂量 γ通过率 

分 类 号：R730.55[医药卫生—肿瘤]