Objective To discuss impacts of 18 F-FDG PET/CT over lung tumour radiotherapy plan.Methods After the regular lung tumour patient does 18 F-FDG PET/CT examination to 167, the measurement standard absorbs value(SUV) , nidus area SUV≥2. 5 was masculine gender. The detecting parting from PET/CT for according to CT carries out TNM periodization on the tumour, the different radiotherapy section years of service doctor makes use of CMS to cure the anastomosing software planning the systematic image above organizing 5, volume value getting patient GTV with the tumour volume (Gross Tumor Volume, GTVCT and GTVPET/CT) being independent on PET/CT Sanwei image drawing the outline of cardinal principle in CT, composes in reply respectively a mutant modulus. Results Bear fruit:Examine that the queen, 19. 8% (33/167 example's) patient tumour TNM had happened by stages after PET/CT change, 167 regular patient CT were not same as PET/CT examination GTV result equally. Conclusion Clinical TNM of change PET/CT lung tumour periodization, the difference making radiotherapy section not draw the outline of GTV with years of service doctor is diminished obviously, and then is makes the lung cancer patient entire curing a plan happening change.