The artificial intelegence – system has outstanding perfomance in the detection of subtle GGO, which is the most easily missed typical CT feature of COVID-19. Also, it can precisely segment the lesion region, calculate the lesion volume, volume rates of lesions to total/left/right lung, and each in lung lobe. Comparing CT scans of the same patients at several time points, the radiologist can use the system to measuire changes in each lesion and track the progression of the disease.