The evaluation in clinical application of 16-slice helical CT low-dose scan in lung general investigation

Objective:To assess the value of clinical application in lung general investigation with 16-slice helical CT low-dose scan.Methods:Thoracic 16-slice helical CT low-dose scanning was separately performed in each of 1206 asymptomatic volunteers with the scan parameters as follows: 120kV,25mA,thickness 7.5mm,pitch 1.35 and table speed 27.5mm/rotation.15 cases with small nodules were examined repeatedly rising to standard-dose of 180 mA and compared the results with the former.The cases with definite nodule or questionable nodule underwent 1.25mm reconstruction slice and 1.25mm reconstruction interval.The volume and the density of small nodules were analyzed by the Advance Lung Analysis.Results:Different diseases in lung were detected in 265 cases totally and the positive rate was 21.97%.97 cases with non-calcification pulmonary nodules from 3～30mm were examined and the positive rate was 8.04%.The volume of the nodules were successfully measured with two kinds of doses in 15 cases and the figures with low-dose scan were larger than those with standard-dose scan but without statistically significant differences(t=1.747,0.2P0.1).Before 1.25mm reconstruction interval the highest density CT values-571～61HU were measured from 3～4mm calcification pulmonary nodules in 12 patients and the values became 399～1880HU after 1.25mm reconstruction interval.There was statistically significant difference between the two methods(t=12.95,P0.001).Conclusion:Low-dose helical CT is expected to detect the lung nodules larger than 3mm.Due to the low dose,the negative influences of radio can be reduced significantly.It may be appropriate on the healthful examination for the lung cancer detection on early stage and make the diagnosis.