Abstract: Objective To explore the values of fused DWI-T₂WI imaging in target delineation for central-type lung cancer (CTLC) combined with pulmonary atelectasis. Methods Total 60 cases of central-type lung cancer confirmed by bronchoscopy or biopsy in our hospital from May,2015 to October,2016 were recruited.CT and MRI images were positioning,and we use T₂WI and DWI technology to fusion the images by to by Pinnacle³9.6 radiotherapy planning system.We can compared the the tumor target (GTV),and we analysis the enhanced CT and DWI-T₂WI image fusion images and distinguished the border,and we check out the lymph node,the result of the analysis with pulmonary merger or no merger with atelectasis,GTVt differences in quantitative analysis,the matching pair four tables χ² test.The GTVt differences influence factors we used logistic regression analysis. Results DWI-T₂WI fusion images were more easily to distinguish the borderline between pulmonary atelectasis and tumor differentiated as compared with contrast-enhanced CT (χ²=8.47,P<0.05);Both DWI-T₂WI fusion images and enhanced CT showed positive lymph nodes in 32 cases,the difference was not statistically significant (χ²=0.40,P=0.53).The cumulative GTV of central-type lung cancer combined with pulmonary atelectasis differed greatly,the difference was significant (t=7.22,P<0.05),the factors including the combining atelectasis (Wald=12.58,P<0.05) and tumor pathologic type (Wald=5.22,P<0.05). Conclusion DWI-T₂WI image fusion can differentiate pulmonary atelectasis from tumor boundary in target delineation for central-type lung cancer combined with pulmonary atelectasis during the radiotherapy.