Objective To explore the value of non-spiral mode of low-dose chest scan in diagnosis of pulmonary nodules.Methods Thirty patients with chest X-ray suspected pulmonary nodules underwent spiral low-dose and non-spiral low-dose CT scan under Toshiba 4 row multi-slice spiral CT (Asteion 4).The parameters were defaulted as 35.5 mAs,20 mm/ round (pitch=l),0.75 s/rot in spiral scan,while in non-spiral scan wree defaulted as 24 mAs,20 mm/round (thickness = layer distance),0.48 s/rot.Other parameters including 120 kV,collimator 0.5×4,DFOV 300 mm,reconstruction slice thickness 5 mm were chosen in both scans.CT imaging quality was evaluated according to the degreex of image artifacts and the distinguishment of nodule,and the pulmonary nodules were counted,then the differences of finding the pulmonary nodules and effective radiation dose of both mode were analyzed.Results The images were good in one patient in both scanning mode,and excellent in 29 patients in spiral scanning mode,28 patients in non-spiral scanning mode.A total of 108 nodules were found with two modes.The effective radiation dose in non-spiral scan was lower than that in spiral scan.No significant difference was found between non-spiral mode scanning and spiral scanning mode in the low-dose chest examination in the discovery and diagnosis of pulmonary nodules.Conclusion Lower dose of non-spiral scanning mode is feasible in diagnosis of pulmonary nodules.