Timing of lung nodule review: (1) Management of solid lung nodules ≤10 mm in length: 1. For single solid nodule ≤10 mm in length without risk factors for lung cancer, it is recommended that the frequency and duration of CT follow-up be selected according to the size of the nodule: (1) Nodule <4 mm in length should be followed up selectively, but patients should be informed of the potential hazards of not following up; (2) Nodule 4-6 mm in length should be reassessed after 12 months, and if there is no change (stable), it should then be transferred to regular annual follow-up; (3) Nodule 7-10 mm in length should be followed up at 3, 6, and 12 months. (2) Those with nodules 4-6 mm in diameter should be reassessed at 12 months, and if there is no change (stable), then the patient should be referred to regular annual follow-up; (3) Those with nodules 7-10 mm in diameter should be followed up at 3, 6, and 12 months, and if there is no change (stable), then the patient should be referred to regular annual follow-up. 2. Individuals with a single solid nodule ≤10 mm in length and the presence of one or more risk factors for lung cancer: it is recommended that the frequency and duration of CT follow-up be selected according to the size of the nodule: (1) those with a nodule <4 mm in length should be reevaluated at 12 months, and then converted to regular annual follow-up if there is no change (stable); (2) those with a nodule 4-6 mm in length should be followed up at 6 and 12 months, and then converted to regular annual follow-up if there is no change (stable); (3) those with a nodule 7-10 mm in length should be followed up at 3, 6, and 12 months, and then converted to regular annual follow-up if there is no change (stable). (2) Nodule lengths of 4-6 mm should be followed up after 6 or 12 months, and if there is no change (stable), then they should be transferred to regular annual follow-up; (3) Nodule lengths of 7-10 mm should be followed up initially after 3, 6, or 12 months, and then at 9-12 months, and if there is no change (stable), then they should be transferred to regular annual follow-up. (ii) Management and diagnosis of solid lung nodules >10 mm in diameter: 1. Single solid nodule >10 mm in diameter: clinicians are advised to assess the probability of malignancy of the lung nodule by qualitatively using clinical judgment (morphology) and quantitatively using a validated model (Mayo model). 2. Single solid nodules >10 mm in diameter with a low (<5%) predictive probability of malignancy: it is recommended that they be entered into follow-up, with reassessment after 3 months for 10-20 mm in diameter and after 1 month for 20-30 mm in diameter. 3. Those with a single solid nodule >10 mm in length and a moderate predictive probability of malignancy (5%-65%): further investigations including PET-CT, percutaneous lung aspiration biopsy, navigation bronchoscopy, ultrasonic bronchoscopy, etc. are recommended to clarify the nature of the nodule, or diagnostic anti-infective therapy is repeated after 1-3 months. Surgery is recommended for lung nodules diagnosed as malignant by biopsy, while those diagnosed as benign by biopsy are recommended to enter follow-up management. 4. Individuals with a single solid nodule >10 mm in length and a high predictive probability of malignancy (>65%), or those with a high morphological suspicion of lung cancer: the MDT evaluates the options of surgical or non-surgical treatment (stereotactic radiotherapy or radiofrequency ablation). Sub-solid lung nodule management and diagnosis and treatment principles (1) For single sub-solid nodule with high morphological suspicion of lung cancer at the initial diagnosis, MDT is recommended to decide the next diagnosis and treatment plan (follow-up, biopsy, surgical treatment or non-surgical treatment). (2) If there is a single sub-solid nodule with previous imaging data (more than 3 months apart), the images will be compared and evaluated, and the next diagnosis and treatment plan will be based on the evaluation results. (3) For a single sub-solid nodule without previous imaging data (or previous imaging interval <3 months), it is recommended that the 1st follow-up visit be performed after 3 months, with comparative evaluation of the imaging changes, and based on the results of the evaluation, the patient will proceed to the next diagnosis and treatment plan. (4) Those who have a single sub-solid nodule and are evaluated for pulmonary nodule resorption by comparison with previous imaging are entered into routine annual follow-up. (5) If a single sub-solid nodule is assessed to be shrinking by comparison with previous images, the patient should be re-evaluated after 6 months, and if pseudo-shrinkage is ruled out, annual follow-up is recommended; if pseudo-shrinkage is recognized (shrinkage of the nodule in length and diameter but an increase in the solid component), MDT is recommended to decide the next diagnostic and treatment plan. (6) For a single sub-solid nodule that is assessed to be stable on comparison with previous imaging, clinicians are advised to assess the probability of malignancy of the nodule both qualitatively by clinical judgment (morphology) and quantitatively by using a validated model (Brock model). Those with a low probability of malignancy (<10%), or those who are stable on long-term follow-up, are recommended to enter routine annual follow-up; those with a high probability of malignancy (>10%), or those with a high degree of morphological suspicion of lung cancer, are recommended to take MDT to decide on the next diagnostic and treatment options (follow-up, biopsy, surgical or non-surgical treatment). (7) A single sub-solid nodule, which is evaluated as growing, pseudo-shrinking, or progressing after stabilization on previous imaging: MDT is recommended to decide the next diagnosis and treatment plan (follow-up, biopsy, surgical or non-surgical treatment).