Nodules in the dorsal segment of the lower lobe of the right lung may be caused by diseases such as pneumonia, tuberculosis and lung tumor. 1. Pneumonia: Pneumonia may be triggered when the lungs are infected by pathogens, and there will be inflammatory exudation when inflammation occurs in the lung tissues, and nodules may be observed in the lungs when chest CT examination is done. 2. Tuberculosis: Tuberculosis is mainly caused by the infection of lung tissues by Mycobacterium tuberculosis, and it can be triggered by the decline of autoimmune function and close contact with patients with tuberculosis, and patients with tuberculosis may have nodules in the lungs when they do imaging examination. 3. Lung tumors: for example, the etiology of lung cancer is unknown, but smoking, ionizing radiation and other factors are the high-risk factors for lung malignant tumors, and long-term exposures can suffer from lung cancer, and when tumors appear in the lungs, it may lead to the appearance of lung nodules. It is recommended that patients go to the hospital to improve the relevant examination, clarify the cause of the disease, and carry out corresponding treatment according to the specific condition under the guidance of the doctor.