I. Pulmonary nodules need regular follow-up, what is the content of the follow-up? Surgical management is required when pulmonary nodules have the following changes 1. For solid pulmonary nodules on review the nodule diameter increases, appearing lobar, burr sign, etc. 2. Pure ground glass-like nodules increase significantly or increase in density 3. Pure ground glass-like nodules appear to have a real component 4. Some solid ground glass-like nodules have an increased solid component or appear burr sign, vacuole sign, etc. 5. New intrapulmonary nodules appear II. The model estimation method of the Mayo Hospital on pulmonary nodules is based on six independent risk factors: age, smoking history, history of extrathoracic tumor, nodule diameter, burr sign and nodule site localization, and the probability of malignancy of pulmonary nodules is calculated by the formula Probability of malignancy=ex/(1+ex) X=-6.8272+(0.039Ix age)+(0.7917x history of smoking)+(1.3388x history of tumors at other sites)+(0.1274x nodule diameter)+(1.0407x burr sign)+(0.7838x site localization). Formula description: e is the natural logarithm (2.71828); age is calculated numerically; 1 if there is a history of previous smoking (whether or not quit) and 0 otherwise; 1 if there is a history of extrathoracic tumor within 5 years (including 5 years) and 0 otherwise; nodule diameter is calculated in millimeters; 1 if there is a burr at the nodule margin and 0 otherwise; 1 if the lung nodule is localized in the upper lobe and 0 otherwise. For example, in a 60-year-old patient with a history of previous smoking and no history of extrathoracic tumor, a CT finding of a pulmonary nodule of 20.0 mm in size with positive marginal burr is localized in the upper lobe of the right lung. The X calculated according to the formula was 0.683, and the probability of malignancy of the pulmonary nodule was 66.4% when brought into the formula. Low probability of malignancy: less than 5% Medium probability of malignancy: 5%-65% High probability of malignancy: 65% or more