Modern three-dimensional conformal radiotherapy techniques (3DCRT) and intensity-modulated radiotherapy (IMRT) are the most advanced radiotherapy techniques available. In hospitals where 3DCRT techniques have been established, they should be used for all lung cancer patients and CT or CT/PET should be used for radiotherapy planning. Dose volume histograms (DVH) for lung, esophagus, heart, liver, kidney and spinal cord should be used to minimize toxicity to normal tissues. If feasible, respiratory control techniques (e.g., 4-D CT and respiratory gating) should be integrated into the radiotherapy setup. Radiotherapy planning should be based on the same CT images as the radiotherapy body position. Whenever possible, diagnostic CT examinations or CT simulated positioning should be performed with intravenous contrast to better outline the radiation target area and normal tissue. When outlining large tumor target areas (GTV), PET/CT is superior to CT alone in cases where the tumor is associated with significant pulmonary atelectasis. Photon rays of 4 to 10 MV energy are generally used. If the patient has a large mediastinal mass, or if the primary tumor is a large proximal lesion and the anteroposterior diameter of the patient’s chest cavity exceeds 20 cm, photon rays of 15 or 18 MV may also be used. IMRT should be considered if the tumor invades the vertebral body, is located in the superior pulmonary sulcus, or involves the mediastinum bilaterally to avoid over-irradiating normal tissue. Radiotherapy that gives only high doses to the involved fields without selective lymph node irradiation has been shown to be less toxic and more likely to prolong survival and reduce the risk of isolated lymph node recurrence. For patients receiving radical radiotherapy or radiochemotherapy, recommended dose volume limits should be followed to avoid treatment interruption or dose reduction due to manageable acute toxic reactions. For hospitals where the advanced techniques described above are not yet available, conventional radiotherapy techniques may be used, but great care must be taken to protect the lungs, heart and spinal cord to avoid radiological damage to them. For preoperative chemoradiotherapy, a total of 45-50 Gy, 1.8-2 Gy per session, is used to treat the full volume of the bulk tumor. Some institutions report that it is also safe to give doses greater than 50 Gy for preoperative radiotherapy patients, however this is still experimental. If lung resection is required, preoperative chemoradiotherapy should be avoided to prevent postoperative pulmonary toxicity. There are difficulties in performing surgery in a radiation field that has already received 60 Gy irradiation because the borders are already poorly defined at high doses. Therefore, surgeons are often very cautious when performing resections in areas that have received prior radiation therapy above 45 Gy, especially above 60 Gy (e.g., in patients receiving radical synchronized chemoradiotherapy). Therefore, the dose of radiotherapy should be carefully considered for patients who are potentially eligible for surgery. If the patient is not eligible for surgery, he or she should receive uninterrupted radiotherapy up to the full dose. Postoperative radiotherapy should include the tracheal stump and mediastinal region. If the margins are negative, the total dose of 50 Gy should be divided into 1.8-2 Gy per session. for patients with extra-peritoneal lymph node invasion or positive microscopic margins, the total dose should be 54-60 Gy (1.8-2 Gy per session). For those with sarcoid residual tumor, the total dose can be as high as 70 Gy. Due to the high rate of local recurrence, adjuvant synchronized chemoradiotherapy should be administered if the patient can tolerate it. For radical synchronized radiotherapy, a total radiotherapy dose of up to 74 Gy is applied, divided into 2 Gy to treat the full volume of the bulk tumor. Three-dimensional conformal radiotherapy planning must be used together with a dose volume histogram assessment of lung function to determine the risk of radiation pneumonitis. Selective lymph node irradiation is not mandatory. Studies have shown that stereotactic whole-body radiotherapy (SBRT) and radiofrequency ablation (RFA) can be treatment options for lymph node-negative patients who refuse surgery or who cannot tolerate surgery because of poor physical status, significant cardiovascular risk, poor lung function, and/or comorbidities. One study used stereotactic radiosurgery in 245 patients (T1 to 2) with a local control rate of 85% at 2 and 5 years. The Radiation Therapy Oncology Group (RTOG) 0236 trial is currently evaluating the effectiveness of SBRT. Patients best suited for SBRT are those with peripheral lung cancer with tumors <5 cm and negative lymph nodes. Patients best suited for RFA are those with isolated peripheral lesions <3 cm, and RFA can be used for previously irradiated tissue as well as for palliative treatment. A recent study found that 33 patients with NSCLC who underwent RFA had an overall survival rate of 70% (95% CI, 51%-83%) and 48% (30%-65%) at 1 and 2 years, respectively. stage I NSCLC patients (n=13) had an overall survival rate of 75% (45%-92%) at 2 years. Radiotherapy with or without chemotherapy should be offered as a possible cure for patients with stage I and II NSCLC who cannot be treated surgically for medical reasons but are in good physical condition and have a long life expectancy.