Detection and Size Quantification of Pulmonary Nodules Using Ultra-Low-Dose CT with Tin Filtration: A Prospective Comparative Study

Abstract Background To evaluate the diagnostic performance of tin-filtered 150 kV ultra-low dose CT (ULDCT) for pulmonary nodule detection and size measurement compared with standard-dose CT (SDCT). Methods This prospective study enrolled 261 patients who underwent both SDCT (120 kV) and ULDCT (150 kV with 0.6 mm tin filtration) during a single visit. Radiation dose parameters, subjective and objective image quality, and diagnostic performance were assessed using SDCT as the reference standard. Nodules were classified as solid, pure ground-glass (pGGNs), or mixed ground-glass nodules (mGGNs), and nodule diameters were compared between the two protocols. Results ULDCT reduced radiation dose by 83% compared to SDCT (1.10 ± 0.22 mSv vs 6.55 ± 1.51 mSv, P < 0.001) while maintaining excellent image quality. SDCT detected 856 nodules, with ULDCT identifying 779 true-positive nodules. Subtype analysis revealed sensitivities of 99.65% for solid nodules, 100% for mixed ground-glass nodules, and 70.12% for pure ground-glass nodules. No significant differences were observed in nodule diameter measurements between ULDCT and SDCT (P > 0.05). Conclusions Tin-filtered 150 kV ULDCT achieves high sensitivity for pulmonary nodule detection with significantly reduced radiation dose and maintain clinically acceptable image quality. Advances in knowledge This study provides clinical validation of tin-filtered 150 kV ULDCT in a heterogeneous outpatient population, demonstrating its feasibility for accurate pulmonary nodule detection beyond screening settings and highlighting its subtype-specific performance.