The hilum pulmonis is wider than the normal standard, and there is an oval depression in the middle of the medial surface of the lung called hilus of lung,hilum pulmonis, where the main bronchi, pulmonary arteries, pulmonary veins, and bronchial arteries, veins, lymphatics and nerves enter and exit. There is an oblong depression in the middle of the mediastinal surface, called the hilum pulmonis. The upper part of the right pulmonary hilar is composed of the right upper pulmonary artery and branches of the pulmonary veins, and the lower part is composed of the right lower pulmonary artery. On posteroanterior chest images, the left pulmonary hilar is slightly higher than the right pulmonary hilar, and on lateral chest images, the right pulmonary hilar is mostly located anteriorly and the left pulmonary hilar is located posteriorly. The abnormal changes such as enlargement and decrease in size suggest lesions. Prevention of widened hilum caused by lung cancer: 1. Prohibition and control of smoking Foreign studies have proved that quitting smoking can significantly reduce the incidence of lung cancer, and the earlier you quit smoking, the more obvious the reduction of lung cancer incidence. Therefore, smoking cessation is the most effective way to prevent lung cancer. 2.Protection of environment It has been proved that the exposure dose of air pollution, deposition index, smoke index, benzo(a)pyrene, etc. is positively correlated with the incidence of lung cancer, so protecting the environment and reducing air pollution are important measures to reduce the incidence of lung cancer. 3.Prevention of occupational factors Many occupational carcinogens have been recognized to increase the incidence of lung cancer, and reducing the exposure to occupational carcinogens can reduce the incidence of lung cancer. 4.Scientific diet Increasing vegetables and fruits in the diet can prevent lung cancer.