Stereotactic Body Radiotherapy for Stage I Lung Cancer With a New Real-time Tumor Tracking System

Background/Aim: Suppression of respiratory movement is crucial for safe and effective stereotactic body radiotherapy (SBRT). SyncTraX FX4 is a novel device for synchronous respiratory irradiation. The purpose of this study was to evaluate the efficacy and toxicity of SBRT using SyncTraX FX4 for patients with lung cancer. Patients and Methods: Patients treated with SBRT using SyncTraX FX4 between November 2017 and August 2020 were included. In all cases, fiducial markers were inserted into the lung, and the total dose administered was 55 or 60 Gy, depending on the distance from the central region of the lung. Acute and late toxicities were reported, and local control, progression-free survival, cancer-specific survival, and overall survival were analyzed. Results: We evaluated 16 patients and 17 sites. The median follow-up period was 14.4 months. In both the acute and late phases, one patient experienced grade 3 radiation pneumonitis; however, grade 4 or higher toxicities were not observed. There was no local recurrence during the observation period, and the overall survival, cancer-specific survival, and progression-free