Differentiating between benign and malignant lung nodules has always been a challenge in medical imaging. Especially for early-stage tiny lung nodules, it's difficult to directly determine their benign or malignant nature just from the imaging manifestations. In large-scale clinical studies on lung cancer screening, we've found that for small lung nodules: 1. If the diameter is less than 0.2 inches (5 millimeters), the probability of lung cancer is less than 1%. 2. For lung nodules with a diameter between 0.2 and 0.4 inches (5 - 10 millimeters), the probability of lung cancer is below 5%. 3. For lung nodules larger than 0.4 inches (10 millimeters), the probability of lung cancer is between 10% and 25%. Therefore, for a lung nodule with a diameter of 0.16 inches (4 millimeters), the likelihood of it being a tumor is relatively low. For such nodules, it's usually recommended to conduct follow-up observations for about 6 months or a year. Recheck the chest CT to observe the changes and development of the nodule. If there's an obvious growth trend when comparing the previous and current results, the probability of it being a malignant tumor increases, and surgical resection is recommended. If there's no change when comparing the results, long-term observation can be continued.