Clinical comparison of low-dose and standard-dose helical CT in the detection of pulmonary nodules

Objective:To investigate the sensitivity of low-dose helical CT for pulmonary nodules (≤10mm) detection.Methods:As pulmonary nodules (≤10mm) were detected in 27 patients at standard-dose helical CT, we repeated low-dose helical CT after the patients' agreement. Nodules were assessed by size: the size of the nodules was measured electronically and categorized as ≤5mm and 6～10mm.This term, low-dose helical CT were performed to screen for early lung cancer in 120 asymptomatic people, scanning with 15mA or 30mA according to sex and weight. They subjectively rated the lung window images on a four-point scale (0:poor;1:fair;2:good;3: excellent) according to noise and artifacts.Results:In 27patients. 632 nodules (≤10mm) were detected at standard-dose helical CT(130mA).whereas 603 nodules were observed at low-dose helical CT(30mA). There were no statistically significant differences in the number of nodules detected at standard-or low-dose helical CT (P0.05). 48(7.4%) nodules were observed only at standard-dose helical CT, and 19(2.9%) nodules were seen only at low-dose helical CT. The sensitivity of standard-dose helical CT (130mA) was 97.1% for all nodules(≤10mm),96.1% for nodules ≤5mm, and 98.8% for nodules 6～10mm; 92.6%,90.5%,96.3% respectively by the low-dose helical CT(30mA) scan. In 120 asymptomatic people,the lung window average score was 2.31 and 2.43 respectively by the 15mA and 30mA scan. Image noise and grain artifacts were present in lung apexes above the level of the aortic arch and lung bottom below the midriff.Conclusion:The sensitivity had no difference between low-dose helical CT(30mA) and standard-dose helical CT (130mA) for pulmonary nodules (≤10mm)detection .Screening early lung cancer was a feasible method with 15mA or 30mA according to sex and weight.