To observe the effect of Mucosolvan on the prevention and treatment of radiation pneumonitis and pulmonary fibrosis after radiation therapy. Methods: 104 chest tumor patients were randomly divided into treatment group and control group, 52 cases in each group, all cases received radical radiotherapy, and Mucosolvan injection 60-90mg was added into 5% glucose injection and dripped intravenously at the same time starting from the second week of radiotherapy in the treatment group, 1 time/day×15-30 days. Results: The incidence rates of radiation pneumonitis and pulmonary fibrosis in the treatment group were 17.2% and 19.8%, respectively; the incidence rates in the control group were 36.3% and 38.4%, respectively, and the differences between the two groups were significant (P<0.05). Conclusion:Chest radiotherapy can cause the decline of alveolar surface active substances and increase protein exudation.Mucosolvan stimulates the formation and secretion of lung surface active substances,antioxidant,and anti-inflammatory reaction,which can reduce the incidence of radioactive lung injury. Radiation lung injury; prevention and treatment; alveolar surface-active substances; Mucosolvan Radiotherapy is one of the important measures in the comprehensive treatment of tumors, and radiation pneumonitis and pulmonary fibrosis are common complications of radiotherapy for thoracic tumors. The clinical manifestations of radiation pneumonitis low fever, irritating cough, chest tightness, chest pain, dyspnea and so on appear in radiotherapy or 1-3 months after radiotherapy, which seriously affects the quality of survival of patients. If it is not detected early, controlled with drugs and active nursing measures early, for patients with more serious injury, their condition will be aggravated and developed, and even complicate respiratory and cardiac failure and death. Therefore, from October 2001 to December 2003, our department used Mucosolvan injection to prevent and treat radioactive lung injury and achieved obvious efficacy, which improved the survival quality of patients. 1. Clinical data 1.1 General data 104 cases in this group, 82 male, 22 female, age 31-72 years old, average 54 years old. There were 8 cases of esophageal cancer, 86 cases of lung cancer and 10 cases of malignant lymphoma. Randomly divided into treatment group and control group,52 cases in each group. General condition KS score of 60 points or more, not accompanied by serious heart and lung diseases. 1.2 Treatment methods All cases were treated with 6MV X-ray or 15MV X-ray, conventional split dose of 2.0 Gy/times, 5 times/week, tumor cumulative dose of 40-72 Gy, radiating area of 90-140M2, the control group completed the conventional radiotherapy, and the treatment group started to apply Mucosolvan injection of 60-90mg added to 5% dextrose injection intravenously at the same time from the second week of radiotherapy, 1 time/day×15-30 days. times/day×15～30 days. 1.3 Diagnostic criteria of radiation pneumonitis 1) history of lung radiotherapy; 2) clinical presentation of irritating dry cough, chest pain, shortness of breath and fever; 3) X-ray film showing a large dense shadow consistent with the radiation area. 1.4 Diagnostic criteria for radiographic pulmonary fibrosis 1) History of pulmonary radiotherapy, mostly occurring 6 months to 1 year after the end of radiotherapy; 2) Patients may be asymptomatic or only show shortness of breath, and chronic pulmonary insufficiency may occur in patients with large field irradiation; 3) Radiographs show elevation of one side of the transverse septum, thickening of the lung apices, mediastinal shift, striated and patchy shadows accompanied by pulmonary tug and compensated emphysema, and so on. Chronic pulling can cause pulmonary atelectasis, mediastinal shift, pleural and pericardial adhesions, curtain hanging, and in severe cases, tracheal stenosis and scarring of the late septum that prevents movement. Several years after receiving radiotherapy, encapsulated effusions may still occur in the area of lung injury, forming pleural calcifications. It is rare for radiologic changes to occur in the non-irradiated area, as well as in the contralateral lung field. 1.5 Tests and results The test of significance was performed using the χ² test. The incidence rates of radiation pneumonitis and pulmonary fibrosis in the treatment group were 17.2% and 19.8%, respectively; the incidence rates in the control group were 36.3% and 38.4%, respectively, and the difference was significant when comparing the two groups (P<0.05) There were no serious adverse reactions when Mucosolvan Injection was administered intravenously, and there were occasional nausea, drowsiness, and fatigue. 2, Discussion Radiation pneumonia and pulmonary fibrosis are common complications of radiotherapy for chest tumors. They are mainly manifested as acute radiation pneumonitis and chronic pulmonary fibrosis, both of which are two stages of 1 course. Acute cases often occur within 1 month after radiotherapy, and most chronic cases occur 6 months to 1 year after the end of radiotherapy. Most of the drugs used in the treatment of radiation pneumonitis are hormone plus antibiotic therapy, although there is a certain degree of efficacy, but hormone therapy is easy to lead to tumor recurrence and the occurrence of some complications. Patients with radiation pneumonitis have different degrees of pulmonary fibrosis from 6 months to 1 year after radiotherapy. In mild cases, there are no symptoms, or only a slight irritating cough, and in severe cases, cardiac and pulmonary insufficiency may occur. There is no special treatment for radiological pulmonary fibrosis. Therefore. The emphasis is on preventing the occurrence. Radiation pneumonitis is characterized by a loss of balance at the alveolar capillary wall interface, resulting in incomplete alveolar expansion and blood leakage into the alveolar lumen resulting in hemorrhage, which is the result of the loss of two key components of lung function, namely, production of alveolar surface-active substances and barrier activity. The main target cells are type II alveolar cells and endothelial cells. Mucosolvan is chemically known as ambroxol hydrochloride, also known as bromocycloheximide. Mucosolvan can stimulate the formation and secretion of lung surface active substances, with high specificity for lung tissues. Surface active substances have the ability to promote phagocytosis of pathogenic bacteria by macrophages; reduce the degree of sputum mucus and promote excretion; inhibit the adhesion of pathogenic bacteria; isolate the mucosal epithelium from the air and form a protective layer; reduce airway resistance and reduce respiratory effort; and promote the excretion of foreign particles in cilium-free areas. In our department, from October 2001 to December 2003, 104 patients with thoracic tumors receiving radical radiotherapy were randomly divided into treatment group and control group, and the treatment group used Mucosolvan injection, whose incidence of radiation pneumonitis and pulmonary fibrosis was significantly reduced compared with that of the control group, and the quality of life was significantly improved, and there were no serious adverse reactions under clinical observation.