Endobronchial brachytherapy is a radiation therapy technique in which a miniature radiation source (Ir-192 is commonly used in China) is placed at a close distance to the lesion through the source tube, and the ionizing radiation generated by its decay is used to kill tumor cells directly or indirectly or to disable their proliferation ability. I. Indications: 1. Patients with early-stage intracavitary non-small cell lung cancer who are not suitable for surgery or refuse surgery for various reasons. 2. Supplementary treatment to radical or palliative external radiotherapy for patients with inoperable non-small cell lung cancer, i.e. as a complementary treatment to external radiotherapy. 3. When tumor obstruction causes obstructive pneumonia or pulmonary atelectasis, the method can be used to open the obstructed bronchus so as to relieve the obstruction. 4. Adjuvant treatment of micro-residual lesions after surgery. 5.Previously received sufficient dose of extracorporeal radiotherapy, and again intracavitary recurrence. 6.Palliative treatment for patients who cannot tolerate extracorporeal radiotherapy, which can relieve patients’ cough, blood in sputum and/or hemoptysis symptoms. II. Clinical application 1. Lifting bronchial obstruction and improving symptoms Malignant tumors growing into the bronchial lumen and obstructing the bronchi often cause obstructive pneumonia or pulmonary atelectasis. In this case, endobronchial radiotherapy becomes a good choice to relieve obstruction, relieve symptoms and improve patients’ survival quality. Compared with other treatments, endobronchial radiotherapy can relieve the symptoms of obstruction faster and safer. As one of the important treatments for lung cancer, radiotherapy provides a chance for patients who cannot be operated to be cured, and even for those who cannot be cured, a significant number of them can benefit from palliative radiotherapy. However, even with the widespread use of 3D/intensity modulated technology, conventional external irradiation is still severely limited by the “bottleneck” of normal tissue exposure, often requiring a difficult choice between protecting normal tissue and pushing up the tumor dose. The emergence of endobronchial radiotherapy has opened a new way to solve this contradiction, and as an important supplement to external radiotherapy, it has shown considerable application value in improving the local control rate of tumors. 3. Other cases that meet the indications 3. A small amount of blood and blood clots are usually present in the sputum, and large hemoptysis is rare. A small amount of hemoptysis does not require special treatment, and when the bleeding is large, it is treated according to normal procedures.3. Tissue necrosis (low incidence) requires a rational plan based on a comprehensive assessment of the patient to avoid tissue necrosis as much as possible.4. Pneumothorax and mediastinal emphysema (rare)