Personalized SBRT in Early-Stage Peripheral NSCLC

Inclusion Criteria * Participant or legal guardian provides written informed consent. * Age ≥18 years; no upper age limit; male or female. * Pathologically confirmed non-small-cell lung cancer (NSCLC) staged T1-2N0M0 (IA-IIA, AJCC 8th ed.). * Peripheral tumor location: ≥2 cm from the proximal bronchial tree or any mediastinal structure. * Medically inoperable (e.g., FEV1 \<40 % predicted, DLCO \<40 % predicted, NYHA class III-IV heart failure) or refusal of surgery. * ECOG performance status 0-2. * Life expectancy ≥6 months per investigator judgment. * Measurable disease by RECIST 1.1. * Adequate organ function (blood counts, liver and renal indices) per institutional standards. * Willing and able to comply with all study procedures, imaging schedules, and follow-up visits. * Effective contraception for women of child-bearing potential and fertile men for 12 months after SBRT completion. Exclusion Criteria * Previous thoracic radiotherapy, chemotherapy, targeted therapy, or surgery for lung cancer. * Evidence of regional or distant metastases. * Concurrent or prior malignancy within 5 years (except adequately treated basal-cell carcinoma of skin or carcinoma in situ of cervix). * Active interstitial pneumonitis, radiation pneumonitis, drug-induced pneumonitis, or clinically significant pulmonary fibrosis. * Pregnancy, lactation, or planned pregnancy. * Participation in another interventional clinical trial with an unmet primary endpoint. * Known psychiatric disorder, substance abuse, or other condition that would impair compliance. * Contraindication to contrast-enhanced CT or PET-CT imaging. * Investigator-determined medical, social, or psychological contraindications that could compromise safety or data integrity.