Objective To assess radiation exposure and image quality during chest CT by using orthogonal and lateral topography based on the figure of merit.Methods From December 2020 to May 2021,240 outpatients who underwent chest CT scan were randomly divided into three groups by digital table method.Group 1 had 0° topography,group 2 had(0° and 90°)topography,and group 3 had(180° and 90°)topography.Two senior radiologists who blind the scanning parameters evaluated the image quality of cross-sectional chest CT,including subjective image quality score,signal-to-noise ratio(SNR),and contrast-to-noise ratio(CNR).Volume CT dose index(CTDIvol),dose-length multiplier(DLP),effective dose(ED)and body-specific dose estimation(SSDE)were recorded and calculated,and image quality-radiation dose risk-benefit ratios of several positioning methods were evaluated based on the figure of merit(FOM).Results All 240 patients successfully completed the chest CT examination,and the subjective image quality scores of the three groups were≥4 points in the four levels of images,and there was no statistical significance between the groups(P>0.05).There were significant differences in CTDIvol,DLP,ED and SSDE among the three groups(F=60.871,75.747,75.747,132.18,P<0.001).Compared with group 1,ED and SSDE in group 2 were decreased by 29.1%and 27.4%respectively.In group 3,ED decreased by 33.9%and SSDE decreased by 28%.Compared with FOM group in the three groups,there were statistical differences in the other three levels except the tracheal bifurcation level(P<0.05).Group 3 had a higher FOM.Conclusion Compared with conventional 0° topography,orthogonal topography can significantly reduce the radiation dose of patients,and the image quality can meet the clinical diagnostic requirements.The image quality-radiation dose risk-benefit ratio with(180° and 90°)topography was higher.
Chest CTScout imageThe figure of merit Image qualityRadiation dose
万方数据
维普
