3DCRT计划中不同肺定义对肺癌放疗的影响

Differences and radiation pneumonitis prediction of lung dosimetric parameters based on three normal lung definitions in 3DCRT treatment planning

目的 探讨3DCRT计划中双肺-GTV、CTV、PTV三种定义下正常肺DVH参数差异及对RP的预测价值.方法 对2006-2010年间行3DCRT的147例NSCLC患者分别定义双肺-GTV、CTV、PTV正常肺并收集相关DVH剂量学信息,比较参数值差异及其对RP的预测价值.剂量学参数间差异采用成组t检验,用ROC曲线分析各剂量学因素的预测价值.结果 以MLD为例,双肺-GTV定义下与双肺-CTV、PTV的差值分别为（1.16±0.96）、（3.45 ±1.43） Gy.同一患者不同定义下MLD最大差值为8.73 Gy.双肺-GTV下MLD对≥2、3级RP预测价值优于双肺-CTV、PTV的,表现为ROC曲线下面积较大,分别为0.614和0.678、0.566和0.602、0.551和0.616（P=0.024和0.056、0.269和0.226、0.317和0.167）.对肺V5-V50的分析也得出类似结论.结论 基于不同定义下所得的剂量学参数存在较大差异,临床不能忽视;基于双肺-GTV所得相关剂量学参数对RP预测价值最佳,建议采用.

Objective To compare lung dose-volume histogram （DVH） parameters based on commonly used normal lung definitions,i.e.,lungs-gross tumor volume （GTV）,lungs-clinical target volume （CTV）,and lungs-planning target volume （PTV）,in three-dimensional conformal radiotherapy （3 DCRT） and to determine to what extent they differ in predicting radiation pneumonitis （RP）.Methods A total of 147 non-small cell lung cancer patients treated with concurrent chemotherapy and 3DCRT from 2006 to 2010 were collected.RP was diagnosed according to RTOG criteria.Lung DVHs were generated with exclusion of GTV,CTV,or PTV.Independent-samples t test was used to compare DVH parameters based on different normal lung definitions,and the predictive values of these parameters for RP were evaluated with the receiver operating characteristic （ROC） curve.Results There were significant differences in minimum lethal dose （MLD） between lungs-GTV and lungs-CTV/lungs-PTV （（1.16 ± 0.96） Gy vs.（3.45 ± 1.43） Gy）.The biggest difference in MLD for the same patient based on different definitions was 8.73 Gy.MLD based on lungs-GTV had a better predictive value for grades ≥2 and ≥3 RP than MLD based on lungs-CTV and lungs-PTV,with larger areas under the ROC curve （lungs-GTV ∶ area =0.614,P=0.024;area =0.678,P=0.056;lungs-CTV∶area =0.556,P=0.269;area =0.602,P=0.226 ; lungs-PTV ∶ area =0.551,P =0.317 ; area =0.616,P =0.167）.We drew a similar conclusion when analyzing lung V5-V50.Conclusions There are significant differences between DVH parameters based on various normal lung definitions,which cannot be neglected in the clinical setting.DVH parameters based on lungs-GTV may be the most accurate in predicting RP.