ABSTRACT
Objective@#To evaluate the effect of tumor shape and location on pulmonary dose-volume parameters by intensity-modulated radiation therapy (IMRT) in patients with non-small cell lung cancer (NSCLC), aiming to provide a reference basis for establishing limits of the pulmonary dose-volume parameters during IMRT.@*Methods@#Clinical data of 208 NSCLC patients undergoing radical IMRT from June 2009 to June 2016 were retrospectively analyzed. According to the tumor shape and location, 208 cases were divided into the vertical bar group (n=127) and the horizontal bar group (n=81), the superior lung group (n=103) and the inferior lung group (n=105). Regression model curve was used to evaluate the effect of tumor shape and location upon the common pulmonary dose-volume parameters(V5, V20, MLD, AVS5 and AVS20).@*Results@#In all groups, the fitting curves of V5, V20 and MLD were manifested in the quadratic equation pattern, and AVS5 and AVS20 in the logarithmic equation manner. In the vertical bar group, the V5(P=0.015), V20(P=0.047) and MLD (P=0.012) were significantly higher, whereas the AVS5(P=0.044) was significantly lower compared with those in the horizontal bar group. No statistical significance was observed in AVS20 between two groups (P=0.490). The tumor location exerted significant effect upon V5 alone (P=0.009).@*Conclusions@#When the tumors presents in the vertical bar shape, the limits of the common lung dose-volume parameters are likely to exceed those of tumors in the vertical bar shape. Lung tumors located in the inferior lobe exerts a more significant effect upon the low-dose region volume compared with the tumors in the superior lobe.