The latest statistics from the Chinese Center for Disease Control and Prevention (CDC) in 2014 show that cancer has become the leading cause of death that jeopardizes the health of the nation. Every year, there are about 3.5 million new cancer cases and 2.5 million deaths due to cancer. It is expected that by 2020, the total number of cancer deaths in China will reach about 3 million per year, and the total number of diseases will reach 6 million. Radiation therapy is one of the most important treatments for tumors, and nearly more than half of malignant tumor patients need radiation therapy. Taking lung cancer as an example, 70% of lung cancer patients need radiotherapy during the disease process, involving preoperative and postoperative adjuvant radiotherapy, localized advanced radiotherapy and palliative radiotherapy. In recent years, with the development of stereotactic body radiotherapy (SBRT), patients with inoperable or unwilling early stage lung cancer have a new choice. Body stereotactic radiotherapy (SBRT) technology usually refers to the precise radiotherapy technology with short treatment course and large fractionated dose, which is realized by three-dimensional conformal radiotherapy (3D-CRT), volumetric arc intensity tuning therapy (VMAT), and Cyberknife omnidirectional rotary tracking therapy (Cyber-knife). With the continuous development and improvement of radiophysics technology and radiobiology theory, as well as the continuous improvement of body positioning technology and target organ movement or respiration control technology, SBRT technology has become a mature tumor radiation therapy technology and has been widely used in clinics.The most important feature of SBRT technology is to give the maximum irradiation dose to the target area under the premise of guaranteeing the precision of each treatment. Usually, a course of treatment requires 3-5 irradiations, and each time the dose to the target area is 12-18 Gy. 3 x 18?Gy or 5 x 12?Gy is the most commonly used irradiation segmentation method of SBRT, which can deliver a much higher bioequivalent dose (80-100 Gy) than that achieved by conventional radiotherapy in a shorter treatment time (1-2 weeks). Currently, SBRT technology is mainly applied to patients with clinically inoperable early stage lung cancer (or lung metastatic lesions from other tumors), liver cancer, pancreatic cancer, brain tumors, gynecological and gastrointestinal tumors with local recurrence after surgery. Compared with conventional segmental radiotherapy, the local control rate of SBRT can be increased from 60% to 90%, and the overall survival is significantly improved with fewer adverse effects.