Abstract: [Abstract] Objective:To explore the clinical value of the thin-section CT scanning in all links of 125I seed implantation in treating non-small cell lung cancer.Methods:137 patients comfired NSCLC,the preoperative target was delineated by CT scanning,and the implantation plan was accomplished according to the TPS; Intraoperative 125I seeds were implanted under guidance of CT, and then seeds were scanned by CT layer-by-layer to validate and correct position in real time ;Postimplantation dosimetry was validated with help of CT scanning.If necessary, seed distribution and seed number were adjusted to make dose distribution conform with the principle of available and micro-invasive; Following up and evaluating termly also needed to be accomplished by CT scanning. Results: The DVHs showed the dose line in targets could meet the requirement of prescription dose, the surrounding organs at risk were within the scope of its tolerance dose.129 patients in all 137 patients implantation seeds were the same to seeds of TPS planning,the coincidence rate was 94%.CT scanning showed the local control efficient rate was91.9% after 6 months.The 1-year and 2-year survival rates were 91.2% and 50.4% respectively.During treatment none of them had serious operation-related complication. Conclusion:The thin-section CT was applied in all key links of 125I seed implantation in treating non-small cell lung cancer, especially the clinical value was significant and irreplaceable in quality assurance and quality control of seed implantation treatment.

Key words: non-small cell lung cancer, 125 Iodine seeds, brachytherapy, tomography, quality assurance, quality control