CT shows small patchy infiltrating shadows in the lungs, indicating that the lungs are diseased, usually related to pneumonia, pneumoconiosis, pulmonary vasculitis and other diseases. 1. Pneumonia: mainly due to inflammatory stimulation of the lungs, when it causes inflammatory exudate fluid, small patchy infiltration shadows will be found through examination. 2. Pneumoconiosis: related to the living environment, patients will have symptoms such as coughing, coughing up sputum, dyspnea and shortness of breath. When the disease gradually aggravates, there will be inflammatory exudate fluid, so the infiltration shadow will be found in the examination. 3. Pulmonary vasculitis: inflammatory lesions occurring in the blood vessels of the lungs, when the blood vessels are blocked, causing occlusive vasculopathy and fibrinoid necrosis, and small slice-like infiltration shadows will be found through imaging. In addition to these factors, it may also be due to diseases such as lipoid pneumonia, diffuse lung injury, and lung cancer. Pathologic biopsy can be done to rule out malignant lesions if abnormalities are found.