Low-dose Spiral CT Scan of Chest:Parameter's Optimization

Objective To probe into the optimization of scanning parameters of chest with low-dose spiral CT.Methods The phantom was scanned with different scanning parameters.The image quality obtained with the standard dose parameters and the low-dose technique were compared to evaluate the spatial resolution,low contrast resolution,noise level field uniformity and radiation dose,then the optimal scan parameters were defined.The scanning parameters were 120 kV,0.75 s,Pitch 1.0,FOV 360,RF3 reconstruction model(standard filter).Different thickness and tube electricity were used and the data were analyzed with the statistical method.Results There was significant difference about the data of the CTDI between the 160 mA conventional spiral CT and the low dose groups(30 mA,50 mA,70 mA,90 mA).There was no significant difference about the CTDI between 30 mA and 50 mA,and between 50 mA and 70 mA.There was obviously significant difference about the image noise on 1 mm slice and 10mA with other groups.The spatial resolution and low contrast resolution increased along with the increase of tube electricity,and 50mA was a inflexion of low contrast resolution.Conclusion 50mA and 5mm slice are the best scanning parameters in low-dose lung scanning and adapt to routine screening and early lung cancer screening.