1.Pleural effusion: Chest X-ray: blunted rib septum angle: 300~500ML, small amount (below the level of the 4th anterior rib), moderate amount (above the level of the 4th anterior rib to below the level of the 2nd anterior rib), large amount (above the level of the 2nd anterior rib). Pleural effusion pleural film manifestation Small amount of effusion: blunted angle of the affected side of the rib diaphragm, more than 300ml Medium amount of effusion: the edge of the line of effusion shows a high external and low internal arc, and the lower lung field (below the level of the 4th anterior rib) becomes a dense shadow, more than 2000ml Large amount of effusion: the mediastinum shifts to the healthy side, the diaphragm shifts downward, and the rib space widens, chest CT: “small amount” : watery density arcuate band shadow parallel to the pleura; “medium amount” : crescentic low density area, arcuate line depressed posteriorly and medially, local lung tissue mildly compressed; “large amount” : lung tissue obviously compressed, volume reduced, close to the hilum, mediastinum shifted to the contralateral side also It is believed that there is a roughly linear relationship between the CT measurement of lung volume and the amount of pleural fluid Of course, the patient’s medical history, physical examination can also help in the diagnosis. In the case of massive pleural fluid, patients tend to have respiratory distress. On physical examination, for moderate pleural fluid, the percussion is turbid, and for massive pleural fluid, the percussion is solid. Ultrasound: If the sitting ultrasound fluid is at the angle of the rib diaphragm 500 ml, increase one intercostal more 500 ml. Ultrasound is very inaccurate for the quantification of pleural effusion, and is generally used as a basis for the localization of restricted pleural effusion puncture or pendulum. About pneumothorax: 1 Pneumothorax compression area calculation method When the width of the pneumothorax accounts for 1/4 of the total width, compression 35%, when the width of the pneumothorax accounts for 1/3 of the total width, compression 50%, when the width of the pneumothorax accounts for 1/2 of the total width, compression 65%, this method may not be very accurate, but clinicians are more commonly used, relatively simple. The maximum depth of pleural fluid measured by ultrasound is significantly and positively correlated with the total amount of pleural fluid drained, and the equation is estimated pleural volume = 284.75 x (maximum depth of pleural fluid by ultrasound – 3.2 cm).