Objective To investigate the accuracy of CTVision image-guided stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC).Methods 10 lung SBRT patients were imaged with CTVision before and after irradiation for acquiring and analyzing the three-dimensional set-up error data sets in our department from October 2010 to May 2012.Gross tumor volumes (GTVs) were contoured on pre-and post-SBRT CT sets and combined for generating internal gross tumor volumes (IGTVs).Planning target volume (PTV) margin was calculated,and IGTVs and PTVs were compared for off-line verification of accuracy of SBRT.A paired t-test statistical analysis was conducted with the datasets using SPSS 17.0.Results 80 CT image sets were totally obtained.Setup errors was significant difference before and after radiotherapy in the left-right,superior-inferior and anterior-posterior directions,that were (-0.10±1.30) mmand (-0.15±1.31) mm (P=0.720),(0.18±1.32) mm and (0.18±1.43) mm (P =1.000) and (-0.08 ± 1.19) mm and (-0.13 ± 1.18) mm (P =0.750),respectively.IGTVs of ten patients were smaller than corresponding PTVs (13.53 cm3 and 37.84 cm3,P =0.000).Conclusion Accuracy and safety of SBRT could be verified by imaging with CTVision before and after delivery for non-small cell lung cancer.