Optimal tube current for lung cancer screening with low-dose spiral CT.

To determine the optimal tube current for spiral CT for lung cancer screening.Low-dose spiral CT images from 20 subjects were obtained with 50 mA, 25 mA, 10 mA and 5 mA tube currents. The accuracy in detecting 21 nodules measuring 3 to 14 mm in diameter was tested using receiver operating characteristics (ROC) to determine the diagnostic accuracy and statistical significance.Compared with 50 mA, 25 mA showed no statistical difference. A significant difference was seen between 50 mA and 5 mA images and between 25 mA and 10 mA images, in the detection of lung parenchymal nodular lesions.Approximately 25 mA is the optimal tube current for the detection of pulmonary nodules as it allows a reduction of the radiation dose without sacrificing diagnostic accuracy.