Typical pulmonary tuberculosis CT has certain characteristics, which can be summarized as three more and three less, i.e., multi-focal, multi-morphology, multi-calcification, fewer lumps, fewer nodule accumulations, and fewer enhancements. The diagnosis of tuberculosis is based on the following: 1, site of prevalence: tuberculosis is prevalent in the apical posterior segment of the upper lobe and the dorsal segment of the lower lobe, which is the most basic feature of tuberculosis; 2, morphology: the lesions are coexisting in various forms, often with striated shadows, nodules of different sizes, cavities, solid changes, patchy shadows of different sizes, etc., and the lesions of various forms are mixed together; 3, multiple sites: many typical tuberculosis often violates multiple lobes or lung segments; 4, there are often nodules, masses, and less enhancement. 4. Frequent nodules: TB often has multiple nodules of different sizes on CT, and the nodules of TB are generally small; if the nodules are large and unevenly distributed, metastatic tumors, such as lung cancer, should be considered; 5. Fewer nodules are clustered together: TB nodules are generally not clustered together, but scattered; 6. Fewer lumps: TB seldom forms lumps, and once a lump is formed, the formation of tumor should be considered; 7. Fewer enhancements: TB is rarely seen as a tumor, but it is not a tumor. Less enhancement: TB enhancement is generally not obvious; 8, more calcification: TB grows more slowly and is easy to form calcification; 9, lesion change is very slow: if the lesion absorbs half of it in 3-5 days after anti-infection treatment, TB can be almost excluded; 10, satellite foci: TB nodules are often multiple, and there is only one nodule, which often has satellite foci as well; 11, the inner wall of TB is smooth, and the wall is thin, while the wall of lung cancer cavity is thin, and the wall of lung cancer cavity is thicker. and the wall of lung cancer cavity is thicker; 12, tuberculosis destructive lung, destructive lung that is, the lung is almost no function; 13, tuberculosis is very easy to spread along the bronchial tube, most of the foci are distributed in the peribronchial area.