The purpose of chest CT examination is mainly the following: First, the CT scan of the chest can roughly see the shape of the thorax, and can see whether there are deformities in the thorax, the most common are funnel chest and chicken chest, through CT can see what the relationship between the front and back diameter and left and right diameter ratio, and can determine what deformity belongs to. Secondly, we can also see if there is a tumor on the chest wall, and we can also see if there is a tumor on the pleura, so that we can determine the size of the tumor and the relationship between the surrounding tissues. Thirdly, the common purpose of CT of the chest is to see the disease of the lung, if there is infection in the lung can be seen from the CT, and also to find out whether there are nodules in the lung, and initially determine the nature of the nodules in the lung, whether they are benign tumors or malignant tumors, or pulmonary tuberculosis, etc. Fourth, to see if there are diseases in the mediastinum, because mediastinum can also appear tumors, mediastinum is divided into upper mediastinum, middle mediastinum, lower mediastinum, anterior mediastinum, posterior mediastinum, anterior mediastinum is more common is thymoma, posterior mediastinum is more common neuronal tumors. Fifthly, a chest scan can be done to see if there is gas or fluid in the chest cavity, so that we can know what to do next after looking directly at it. Finally, patients with chest trauma can be detected by chest scan to determine whether there are fractures of the sternum and ribs.