Lung CT is normal half a year ago, and nodules appear half a year later. Lung diseases such as tuberculosis, lung cancer, pneumonia, etc. should be considered. 1. Tuberculosis: tuberculosis lung CT lesions are polymorphic, i.e. infiltrating shadow, nodular shadow and calcified shadow can be seen. If coughing and sputum are present for more than 2 weeks and accompanied by low-grade fever, night sweating, chest pain, hemoptysis and other symptoms, then it should be considered as tuberculosis. 2. Lung cancer: lung cancer can also have the manifestation of lung nodules on CT. The edges of nodule shadow of lung cancer are relatively rough, often with burrs, lobes and cut marks, and the nodules may keep increasing in the course of follow-up. If there are symptoms such as unexplained emaciation, low fever, fatigue, cough, sputum, hemoptysis, etc., the patient should consult the hospital in time for investigation. 3. Pneumonia: Lung infections caused by various pathogens such as bacteria, viruses, fungi, etc., will also appear lung nodules or lung nodule shadows of varying sizes, generally smooth edges, clear boundaries, nodule size, stable nature, especially with bacterial pneumonia. Lung CT six months ago is normal six months after the appearance of nodules, should go to the local hospital, clear diagnosis, symptomatic treatment.