Radiation therapy methods are broadly divided into the following two types: first, external radiation. Also known as distant radiation therapy, it is the more traditional radiation therapy method. Radiation therapy is administered by simply irradiating from outside the body. This method has some limitations, even with sufficient irradiation, some of the tumors may recur locally. Second, internal irradiation. Also called brachytherapy, it is a relatively new radiation therapy technique. By delivering a high-intensity, miniature radiation source into the human body cavity or inserting it into the tumor tissue in conjunction with surgery for brachytherapy, tumor cells can be effectively killed. This technique has achieved relatively good results in its application.