Radiation therapy (radiotherapy for short), together with surgery and chemotherapy, is known as the three major treatments for malignant tumors. About 85% of tumor patients need radiotherapy in the treatment process, and about 70% of patients who receive radiotherapy can implement radical radiotherapy. So what exactly is radiotherapy? Radiotherapy is a treatment method that uses the selective radiation of X-rays or other ionizing radiation and the radioactivity of radioactive elements to destroy cells and tissues for therapeutic purposes. The disadvantage is that while the radioactivity destroys and kills the tumor cells, it also has a destructive effect on the surrounding normal tissue cells. At present, the more perfect and practical radiotherapy techniques are: conventional irradiation technique, X(Y) knife technique, 3D conformal irradiation technique, 3D intensity modulation irradiation technique.