Clinically used imaging examinations for lung cancer diagnosis mainly include the following five categories: 1. chest radiography: mainly used for screening, lung tumor can be shown on chest radiography in terms of general location and size; 2. CT scan and enhanced CT examination: from CT images, the site and size of lung cancer, as well as whether it has metastasized and metastatic sites can be seen; 3. nuclear magnetic (MRI) scan: rarely used, the lung cancer can also be seen on MRI images The MRI image can also show the location and size of lung cancer, as well as whether it has metastasized and metastatic sites. MRI is not precise enough for moving structures, such as the lungs, which move up and down with each breath. Therefore, MRI is rarely used for the diagnosis of lung diseases; 4. Positron emission tomography (PET) scan: PET scan can construct images of organ tissues in the body. Small amounts of radioactive substances are injected into the body, and these substances can be absorbed by the organs and tissues with the highest energy metabolism in the body. Cancerous tissues are metabolically active and thus can absorb higher amounts of radioactive material. The scanner can detect the radioactive elements and thus form an image of the body. For the diagnosis of lung cancer, it has semi-quantitative significance; 5. Bone scan (SPECT): Bone scan is to observe the bone tissue by using tracer. Tracer is also injected through a vein. The tracer is concentrated in certain areas of the bone and can be detected by a special camera. Normal bone tissue images become gray, while areas with damage become black, such as areas with cancer infiltration. Bone scan and PET scan diagnosis often requires a combination of information from CT, MRI, routine X-rays and physical examination.