The typical x-ray presentation of pneumothorax is a curved line with lung texture inside the curved line and no lung texture outside. The curved line is the surface of the lung formed by the compression of the lung due to the presence of gas in the pleural cavity, and the amount of pneumothorax can be determined by the position of the curved line. Generally, when there is 1 intercostal line in the arc, it is 10% pneumothorax, 2 intercostal line is 20% pneumothorax, and so on, if there are 3 and 4 intercostal lines, it is 30% and 40% pneumothorax respectively, that is, for each additional intercostal line, the amount of pneumothorax will increase by 10%.