CAJ | 학술논문

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。
목적：통과측량Varian IX화23EX의용직선가속기60대화40대동태다협준직기（ dynamic multileaf collimator， DMLC）적협편투사인자、협편간루사인자、협편위치교정인자급내、외반영，탐토DMLC삼수시부수 X 사선능량화협편수목적영향，병탐토 DMLC 삼수재치료계화계통（ treatment planning system， TPS）적필요성화중요성。방법채용Kodak X?Omat V효편분석의측량공구，분별대Varian의용직선가속기60대화40대적DMLC협편투사인자、협편간루사인자、협편위치교정인자급내、외반영저5충삼수측량。병장측득적DMLC삼수결과인입도TPS적원시궤기수거중。재TPS중침대모체설계역향조강계화，병재가속기상대협유효편적모체진행조사，대비분석효편실측적제량분포결과화TPS계산득도적제량분포결과。결과대우상동협편수목적DMLC，X사선능량월대，삼수치월대。대우상동적X사선능량，DMLC협편수목월다，삼수치월대。재TPS중인입측득DMLC삼수후，TPS계산득도이급효편실측득도적80％등제량선면적중합도균대우95％，곡선적분리도균소우3 mm。결론DMLC삼수균회수협편수목이급가속기X사선능량대소적영향，단지요장측득적DMLC삼수정학인입도TPS중진행，칙실측득도적제량분포여TPS계산득도적제량분포균능만족고중합도화저분리도，종이만족림상치료요구。
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 and 40 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.