RESUMO
Objective Under different standard uptake value(SUV),to assess gross tumor volume (GTV) definition for non-small cell lung cancer(NSCLC) with 18-fluoro-deoxy-glucose positron emission tomography (~(18)FDG PET) both under definite threshold (42 percent threshold) and various relative threshold (threshold SUV/maximum SUV) derived from the linear regressive function,threshold SUV=0.307?(mean target SUV)+0.588,with computer tomography (CT).Methods Of 20 patients with non-small cell lung cancer,the CT GTV (GTV_(?)).PET GTV with 42 percents threshold (GTV_(42%)) and PET GTV with relative threshold (GTV_(?)) were obtained and compared.Results The mean GTV_(42%),,mean GTV_(?) and mean GTV_(CT) was (13 812.5?13 841.4),(24 325.3?22 454.7) and (28 350.9?26 079.8)mm~3,respectively,with the difference in mean GTV among these three methods significant (F =10,P＜0.01).The GTV_(42%) was smaller than the GTV_(?) and the GTV_(CT)(P＜0.01),with i(?)significant difference between GTV_(?) and GTV_(CT)(P=0.125).Conclusion The relative threshold is more suitable to define the gross tumor volume than the definite threshold.