According to the World Health Organization, 70% of tumors need radiotherapy; nearly half of the cured tumors are the contribution of radiotherapy. 1) Tumors that can be cured by radiotherapy include esophageal cancer, lung cancer, cervical cancer, gastric cancer, liver cancer, nasopharyngeal cancer, lymphoma, oral cancer, oropharyngeal cancer, laryngeal cancer, etc.; 2) Radiotherapy is the best alternative treatment to surgery, such as gastric cancer, lung cancer, pancreatic cancer, rectal cancer, etc.; 3) Many postoperative tumors can be significantly improved by applying radiotherapy, such as gastric cancer, intestinal cancer, breast cancer, soft tissue tumors, thymoma, etc.; 4) Radiotherapy can also cure some postoperative recurrent tumors. (5) For tumors with brain metastasis and bone metastasis, radiotherapy is the preferred palliative treatment method. 6) Radiotherapy can also protect the function of important organs when curing tumors, such as esophagus, larynx, anus, breast, etc. With the emergence of more advanced radiotherapy equipment and the clinical application of cutting-edge radiotherapy technology, the role of radiotherapy in tumor treatment will become greater and greater.