Early stage of lung cancer is usually detected by CT. Although many people have chest X-ray during physical examination, chest X-ray is often unable to show up for early stage lung cancer on chest X-ray because it is an image overlapping the front and back of the body. If you want to detect early lung cancer, you need to do chest CT examination, especially the current low-dose spiral CT, which is increasingly used to screen lung cancer because of the low radiation to human body. When a nodule or ground glass shadow on the lung is detected by chest CT, surgical resection is needed if lung cancer is highly suspected. If the rapid intraoperative pathology confirms lung cancer, radical lung cancer resection is required, which requires mediastinal lymph node dissection in addition to removal of the tumor on the lung.