X-ray chest examination is an important method to diagnose fluid pneumothorax, which can show the degree of lung compression, intrapulmonary lesions and the presence of pleural adhesions, pleural effusion and mediastinal displacement. The typical X-ray presentation of pneumothorax is a thin line shaped shadow of convex arc, called pneumothorax line, with increased translucency outside the line, no lung texture, and compressed lung tissue inside the line. In massive pneumothorax, the lung retracts toward the lung door and appears as a round spherical shadow. A large number of pneumothorax or tension pneumothorax often shows a shift of the mediastinum and heart to the healthy side. In combination with mediastinal emphysema, transilluminated bands are seen next to the mediastinum and next to the cardiac border. Tuberculosis or chronic inflammation of the lung causes multiple adhesions of the pleura, and when pneumothorax occurs, it is mostly confined and sometimes the pneumothorax is interconnected. If the pneumothorax extends to the lower thoracic cavity, the angle of the rib diaphragm becomes sharper. When combined with pleural effusion, the pneumo-liquid plane is shown, and the fluid surface can be seen to move under fluoroscopic change of body position. CT is more sensitive and accurate than X-ray chest radiograph in differentiating small pneumothorax, limited pneumothorax and pulmonary blister from liquid pneumothorax. The size of pneumothorax volume can be judged based on x-ray chest radiographs. Since the pneumothorax volume approximates the ratio of the cubic lung diameter to the cubic unilateral chest diameter [(Unilateral chest diameter. a lung diameter.) /unilateral thoracic cavity diameter.)] , the distance from the lateral chest wall to the edge of the lung is about 25% of the unilateral thoracic volume at 1 cm and about 50% at 2 cm. Therefore, the distance from the lateral chest wall to the edge of the lung ≥ 2 cm is a large amount of pneumothorax, and < 2 cm is a small amount of pneumothorax. If the size of the pneumothorax is estimated from the apical pneumothorax line to the top of the chest cavity, the distance ≥3cm is a large amount of pneumothorax, and <3cm is a small amount of pneumothorax.