X-ray is one of the most basic examination methods in radiology, which is mainly used to examine the following: 1. lung diseases, which can determine whether the patient has inflammation, tuberculosis, lung tumor, lung abscess, pleural effusion, pneumothorax, bronchiectasis, pleural thickening, etc.; 2. to determine whether there is mediastinal enlargement, or mediastinal occupying disease; 3. to determine the location of ureteral stones, or the location of birth control ring in patients; 4. To determine whether the patient has skeletal system diseases, such as fracture, bone tumor; 5. For examining gastrointestinal system diseases, such as barium meal fluoroscopy under X-ray can be done.