Elimination of PTV Margins Based on Online Adaptive Stereotactic Radiotherapy for Centrally Located Early-stage Non-small Cell Lung Cancer

Inclusion Criteria: * Histologically confirmed untreated early-stage non-small cell lung cancer (T1-2N0M0), or recurrent disease (rT1-2N0M0) that is inoperable or where the patient is unwilling to undergo surgery. * Centrally located lung cancer. * Age 18 years or older, regardless of gender. * ECOG performance status score of 0-2. * Serum hemoglobin ≥ 80 g/L, platelets ≥ 100,000/μL, absolute neutrophil count ≥ 1,500/μL. * Serum creatinine ≤ 1.25 times the upper normal limit (UNL) or creatinine clearance ≥ 60 ml/min. * Serum bilirubin ≤ 1.5 times UNL, AST (SGOT) and ALT (SGPT) ≤ 2.5 times UNL, alkaline phosphatase ≤ 5 times UNL. * FEV1 ≥ 0.5 L. * Normal CB6 range. * The patient and their family agree and sign the informed consent form. Exclusion Criteria: * Any other disease or condition that contraindicates radiotherapy (e.g., active infections, within 6 months post-myocardial infarction, symptomatic heart disease including unstable angina, congestive heart failure, or uncontrolled arrhythmias). * Pregnant or breastfeeding women, women who have not undergone pregnancy testing, and pregnant individuals. * Individuals with substance abuse issues, chronic alcoholism, or AIDS. * Individuals with uncontrollable seizures or loss of self-control due to psychiatric disorders. * Individuals with a history of severe allergies or specific sensitivities.