CT can be used as an adjunctive test for secondary TB, but not as a definitive diagnostic tool. The clinical presentation of secondary TB is similar to that of primary TB, but the pattern is seldom homogeneous, with multiple patterns such as infiltrative, fibrotic cavities, and caseous pneumonitis coexisting. Generally, CT chest is useful in the differential diagnosis of occult lesions and isolated nodules, as opposed to conventional X-rays, which can help in the diagnosis and differential diagnosis of the disease. When the CT test results show abnormalities, it can also be used as a test for secondary tuberculosis, but the basis for a definitive diagnosis is multifaceted and cannot be generalized. For example, a combination of the patient’s medical history, clinical presentation, and other tests are needed. Currently, the most common way to confirm the diagnosis of a case is when two sputum specimens are positive on microscopic examination of bacillus resistant sputum by direct smear, or one sputum specimen is positive on microscopic examination of bacillus resistant sputum by direct smear, and the diagnosis is confirmed when the lung imaging is consistent with the imaging manifestations of active pulmonary tuberculosis. For this reason, the results of CT testing have an auxiliary diagnostic value, but cannot be used as the key to confirm the diagnosis.