The Effect Of Tumor Volume,Tumor Shape And Tumor Location On Lung Volume-dose Parameter Of Imrt For Non-small Cell Lung Cancer

Objective The aim of this study was to explore the effect of tumor volume?tumor shape and tumor location on lung volume-dose parameter after intensity-modulated radiation therapy for non-small cell lung cancer(NSCLC),and to provide a reference basis for lung dose parameters confine.Methods From June 2009 to June 2016,208 patients with NSCLC were treated with IMRT.The prescribed dose was 60-66Gy/2.0-2.25Gy/27-33 f.Analysis the association between tumor size and V5,V20(Vdose= fractional volume percent of the lung receiving a dose >XGy),mean lung dose,spared volume like AVS5 ?AVS20(AVSdose = absolute volume of lung spared from receiving a dose >XGy).Using regression model Curve fitting to analyze them along with the change of primary tumor volume.According to tumor shape?location and normal lung volume,208 cases is divided into the vertical bar group(127 cases)and the cross bar group(81 cases),the upper lung group(103 cases)and the lower lung group(105 cases),the large volume group(90 cases)and the small volume group(118 cases),respectively.Using regression model Curve fitting to analyze the differences influence of each group to lung dose volume parameter(V5?V20?MLD?AVS5?AVS20).Results V5?V20?MLD,presents quadratic equation curve along with the change of tumor volume,and AVS5?AVS20 presents logarithmic equation.When the tumor volume,respectively,less than a certain value(288.07cm3?341.69cm3?326.83cm3),V5?V20?MLD increases with tumor size presents a quadratic curve increases,and when the tumor volume,respectively,higher than a certain value(288.07cm3?341.69cm3?326.83cm3),V5?V20?MLD decline.The lung AVS5 ?AVS20 decline in a logarithmic curve along with the increase of tumor volume.The V5?V20?MLD of the vertical bar group and the cross bar group ?the upper lung group and the lower lung group ?the large volume group and the small volume group,presents quadratic equation curve along with the change of tumor volume,and AVS5?AVS20 presents logarithmic equation.The V5?V20?MLD of the vertical bar group is higher than the cross bar group(P=0.015,0.047,0.012),however AVS5?AVS20 of the vertical bar group is lower than the cross bar group(P=0.044,0.490).The V5?V20?MLD of the large volume group is higher than the small volume group(P<0.001,P=0.004,0.002),however AVS5?AVS20of the large volume group is lower than the small volume group(P<0.001).The upper lung group and the lower lung group in the influence of lung volume parameter difference only have statistical significance in V5.Conclusions Lung tumor volume have association with V5?V20?MLD and AVS5?AVS20 in a different extent,when the tumor volume exceeds a certain boundary value(about 300 cubic centimeter),radiotherapy planning only qualify common lung volume-dose parameter(V5,V20,MLD)may be not enough,should pay more attention to absolute volume of lung spared from receiving a dose >5Gy(AVS5).When the tumor is the vertical bar or lung volume is small,the limitation on the common lung dose parameters should be more strict than the vertical bar or the large volume group.