X-ray diagnosis is the most common means to diagnose lung cancer, and its positive detection rate can reach over 90%. The X-ray manifestations of early lung cancer include: 1. isolated spherical shadow or irregular small infiltrate. 2. 2. Unilateral poor ventilation during deep inspiration under fluoroscopy and mild mediastinal shift to the affected side. 3. Restricted emphysema during expiratory phase. 4.Mediastinal oscillation appears during deep breathing. 5.If the lung cancer progresses and blocks the segment or lobe bronchus, the distal part of the blockage will gradually absorb gas and develop segmental atelectasis. More advanced lung cancer can be seen as follows: 1. Huge mass nodules in lung fields or hilum: non-calcified, lobulated, generally uniform in density, with burr at the edges, distorted vascular texture around the periphery, sometimes liquefied in the center, appearing as thick-walled, eccentric, and uneven hollow inside. The doubling time is short. When the mass blocks the lobe or the total bronchus, there is lobar or whole lung atelectasis, and a large amount of pleural fluid is seen when the pleura is involved, and rib destruction is seen when the chest wall is invaded. 2.CT examination: CT examination is the most valuable non-invasive examination means in the diagnosis and staging of lung cancer; CT can detect the location and cumulative range of tumor, and also can roughly distinguish its benign and malignant. CT can also clearly show the hilum, mediastinum, chest wall and pleural infiltrates, which can be used for staging of lung cancer. CT abdomen is very helpful to observe whether there are metastases in intra-abdominal organs such as liver, kidney and adrenal gland. 3.Magnetic resonance imaging (MRI): MRI has certain value in the diagnosis and staging of lung cancer. Its advantage is that it can show the anatomy of mediastinum in sagittal and coronal planes, and clearly show the relationship between central tumor and surrounding organs and blood vessels without imaging, so as to determine whether the tumor has invaded blood vessels or compressed and encircled blood vessels. If the tumor is more than 1/2 of the circumference, it will be difficult to resect; if it is more than 3/4 of the circumference, it is not necessary to operate. MRI can also show clearly when the tumor invades soft tissues, and is most valuable for the evaluation of supraglottic sulcus tumor. MRI is similar to CT in the examination of hilar and mediastinal lymph nodes, and can clearly show the enlarged lymph nodes, but the specificity is poor. 4.Bronchoscopy: The positive detection rate is 60% to 80%, and changes in bronchi of grade 4 to 5 such as swelling, stenosis and ulceration can generally be observed, and smear cytology, bite biopsy and local lavage can be performed. This examination, which is generally safe, has also been reported to be complicated by bleeding after 9% to 29% of biopsies. Tumors suspected of carcinoid tumors and rich in intuitive blood flow should be encountered with caution, and it is best to avoid biopsy trauma. 5.ECT examination: ECT bone imaging detects lesions 3-6 months earlier than ordinary X-ray, and can detect bone metastases earlier. If the lesion has reached the middle stage of the bone lesion decalcification reaches more than 30% to 50% of its content, both X-ray and bone imaging have positive findings, if the osteogenic reaction of the lesion is quiescent and metabolism is not active, the bone imaging is negative and X-ray is positive, the two complement each other, which can improve the diagnosis rate. 6.Mediastinoscopy: When the enlarged lymph nodes in the pre-tracheal, parasternal and inferior ramus (2, 4, 7) groups are seen in CT, mediastinoscopy should be performed under general anesthesia. A transverse incision is made in the superior sternal recess, the anterior cervical soft tissue is bluntly separated to reach the anterior tracheal space, the anterior tracheal passage is bluntly freed, and the observation scope is placed to slowly pass behind the innominate artery to observe the enlarged lymph nodes in the paratracheal, tracheobronchial angles and inferior ramus. Clinical data show that the overall positive rate is 39%, the mortality rate is about 0.04%, and 1.2% have complications such as pneumothorax, laryngeal nerve paralysis, hemorrhage, fever, etc. 7.PET can detect unexpected extrathoracic metastases and make the preoperative period more accurate. There is no false-positive rate in cases of extrathoracic metastases, but false-positive findings in PET in mediastinal granulomas or other inflammatory lymphadenopathy need to be confirmed by cytology or biopsy.