The influence of multi-slice spiral CT low-dose scan on image quality

Objective:To explore the feasibility of multi-slice spiral CT low-dose scan in knee joint and it's influence on image quality.Methods:According to the tube voltage of the scan,divide 100 cases receiving knee-joint CT scan during may,2009 to oct,2009 into two groups,each group contain 50 cases,the tube voltage of A group and B group were 110 kV and 80 kV.Measure the CT values of the fixed ROI that the muscles and soft tissue behind the upper edge of patella,use standard deviation(SD) of CT values as the image noise.Mean volume CT dose index(CTDIvol) that zutomatically got through CT,then calculate the dose-length product(DLP).Use double-blind method to evaluate CT image.Use t test to compare two group's CTDIvol values,DLP values,image noise and image quality score.Results:The CTDIvol values of A group and B group were(5.29±0.23) and(2.08±0.15) mGy,DLP values were(61.26±11.64) and(24.21±4.64) mGy.cm,group Bdcreased by about 60.68% than group A,the differences between the two were statistically significant t values were 82.4 and 20.91,pvalues are 0.01,the mean noise value of B group was slightly higher than A group(12.22±2.97 and 16.55±2.96),t=-7.299,P=0.000,but the mean image quality score((4.86±0.40) points and(4.82±0.44) points),have no statistically significant difference(t=0.475,P0.05).Conclusion:When multi-slice low-dose CT technology 80 kV was correctly applied that may availably protect the patients and guarantee image quality.