If the chest x-ray is normal, whether the patient needs to undergo CT again depends on whether the patient is a young person or an elderly person. If the patient is a young person, the chest X-ray is normal, and people are now paying attention to health care and awareness of health precautions is increasing, the patient can be reviewed regularly without the need for another CT examination. However, in elderly people, due to their age and the fact that the X-ray image is an overlapping image of the front and back tissues and organs, the three-dimensional structure is overlapped on a two-dimensional plane, and the overlapping of tissues and organs due to the overlapping of images may cause microscopic lesions that are not easily displayed. Therefore, for the elderly, it is recommended to perform CT plain scan again.