A normal chest X-ray does not completely rule out the possibility of lung cancer. Generally, chest radiographs can only check the general condition of the lung structure, while small lung changes may be missed. Moreover, early lung cancer patients usually have insignificant lung changes. In addition, apical lung cancer chest radiographs are easy to miss the diagnosis. Therefore, a normal chest X-ray does not mean that there is no possibility of cancer in the lungs. Chest X-ray is only the most basic lung examination, which can roughly observe the structural condition of the lungs and cannot observe the detailed disease development. If lung cancer can be detected by chest X-ray, usually the mass is already present and relatively large, and at this time, the patient usually has entered the middle to late stage of lung cancer. Therefore, in order to completely exclude the possibility of lung cancer, it is necessary for the patient to go to the hospital for a series of detailed examinations such as CT, bronchoscopy and lung puncture biopsy, so as to avoid delaying the condition.