Abstract：Objective To evaluate the effect of scanning method on low-dose chest CT image quality and radiation dose. Methods A
total of 160 patients who underwent chest CT examination were randomly divided into two groups. Group A underwent spiral scan
and group B underwent axial scan. Scanning time, volume CT dose index (CTDIvol) and dose length product (DLP) were
recorded. The noise and signal-to-noise ratio (SNR) of the apex, middle and bottom regions of the lung were compared between
the two groups. Two doctors with more than ten years of radiation experience scored the quality of CT images by double-blind
method. Results There were significant differences in noise value and SNR between the two scanning modes in apex and bottom
of lung (P<0.05). There was no significant difference in noise value and SNR between the two scanning modes in the central lung
region (P>0.05). The exposure time of spiral scan and axial scan were 2.22±0.24 s and 4.23±1.19 s, respectively, with significant
difference (P<0.05). The effective doses of the two groups were 0.51±0.12 mSv and 0.46±0.10 mSv, respectively, with significant
difference (P<0.05). There was no significant difference in subjective evaluation of image quality between the two groups (P>0.05).
Conclusion For low-dose chest CT scanning, the axial scan mode of wide-body detector CT is able to improve the utilization rate of
radiation and reduce radiation dose on the premise of ensuring image quality.
