The essence of iodine 125 particle therapy is to use radionuclide to achieve brachytherapy, which can effectively kill the tumor cells within the range of action and minimize the damage to the surrounding normal tissues. It is safe, easy to operate, effective and fast. It is mainly applied to primary tumors or metastatic tumors that cannot be treated surgically, such as: head and facial tumors: nasopharyngeal cancer, orbital tumors, tongue cancer, maxillary sinus cancer. Chest tumors: lung cancer, breast cancer, etc. Abdominal tumors: liver cancer, pancreatic cancer, bile duct cancer, gastric cancer, rectal colon cancer, etc. Bone and soft tissue tumors: malignant fibrous histiocytoma, various sarcomas, etc. Pelvic tumor: prostate cancer, gynecological tumor, etc. Metastatic tumors: liver metastatic cancer, lung metastatic cancer, retroperitoneal metastatic cancer, pelvic metastatic cancer, etc.