The density of lung tumors on the true non contrast (TNC) and virtual non contrast (VNC) images is 37.2 ± 5.2 and 37.5 ± 5.5 (p=0.118), the contrast-noise ratio of TNC and VNC images are 3.02 ± 1.36 and 2.98 ± 1.35 (p = 0.066), the image quality score of TNC and VNC images is 4.56 ± 0.61 and 4.01 ± 0.67 (p<0.05).