Objective To assess PET-CT scanning limited to involved sites in postchemotherapy lymphoma and explore possible radiation dose reductions.Methods Fifty-three lymphoma patients with prechemotherapy and postchemotherapy whole-body PET-CT were analyzed retrospectively.The involved sites were determined on prechemotherapy PET-CT scanning.Whole-body PET-CT scanning and hypothetical PET-CT limited to involved sites were compared in assessing clinical response to chemotherapy.The potential reductions in effective dose and total acquisition time achieved with PET-CT scanning limited to involved sites were calculated.Results Whole-body PET-CT scanning revealed CR in 37 cases,PR in 13 cases and PD in 3 cases in postchemotherapy lymphoma patients,while PET-CT scanning limited to involved sites revealed CR in 37 cases,PR in 14 cases and PD in 2 cases.The mean effective dose was(15.0 ± 1.7)mSv for per patients of CR with whole-body PET-CT scanning,and was (12.0 ± 2.5)mSv for per patients of CR with PET-CT scanning limited in involved sites(Z=-5.307,P＜0.05).The mean acquisition time was(19.5 ±2.6)s for per patients of CR with whole-body PET-CT scanning,and(11.3 ± 4.4)s for per patient of CR with PET-CT scanning limited in involved sites(Z=-5.324,P＜0.05).Conclusions Response assessment with PET-CT scanning limited in involved sites has good agreement with whole-body PET-CT scanning in postchemotherapy lymphoma patients with CR.Lymphoma patients with CR may benefit from reduced radiation dose and total acquisition time.PET-CT scanning limited in involved sites is not advisable in patients with PR or PD for poor agreement with whole-body PET-CT scanning in response assessment.