Surgery has been the standard treatment modality for early-stage lung cancer, but for patients with poor lung function who cannot be operated or refuse surgery, radiotherapy is the treatment of choice, but conventional radiotherapy techniques are less effective because of the respiratory motion of the lung, which easily causes the lesion to be detached from the target area during actual radiotherapy. As a new radiotherapy technique emerged in recent years, stereotactic tumor ablative radiotherapy (SBRT) can achieve higher tumor local control rate and survival rate. Stereotactic radiotherapy (SBRT) for early-stage non-small cell lung cancer uses the image guidance technique of spiral tomotherapy (Tomotherapy), combined with the use of 4-dimensional CT, to ensure that the lesion does not leave the target area during SBRT and to reduce the target motion and positional errors. The dose drop curve of surrounding normal tissues is very steep, which is conducive to the increase of dose in the target area and the protection of surrounding normal tissues, so as to strike the tumor precisely, accurately and viciously and to reduce the treatment volume, increase the treatment dose and reduce the treatment time significantly, generally 5-10 days can be completed, which improves the local control rate and survival rate of tumor. In recent years, data from nearly 30 research centers in Japan and the United States show that the local tumor control rate of SBRT for early-stage lung cancer is between 74% and 100%, and the survival rate of 3-5 years is 83-91%, with mild complications, achieving almost equal efficacy to surgery, and SBRT is gradually becoming the standard treatment for patients with inoperable early-stage NSCLC,. SBRT has the advantages of non-invasive, short treatment time, can be treated as an outpatient, and avoids postoperative complications. Therefore, SBRT is an effective and safe treatment option for patients with inoperable and reluctant early-stage lung cancer. Figure 1 Spiral tomography radiotherapy under 4D CT, radiotherapy dose distribution and dose volume histogram (DVH) of the tumor showed that the planned target area (PTV) reached 99% at 50 Gy, 22% at V5 and 3.5% at V20, suggesting a low probability of radiation pneumonia. Figure 2 Comparison of tumor before and after radiotherapy: A. CT before radiotherapy showed tumor maximum diameter of 2.1 cm and emphysema; B. PET showed SUV 11.8 g/ml; C. CT after radiotherapy showed lesion maximum diameter of 1.0 cm; D. PET showed SUV 0.9 g/ml.