Reducing contrast media and radiation dose in CT angiography at low tube voltage: animal study with photon-counting detector CT

Background Reducing radiation and contrast media (CM) doses in computed tomography angiography (CTA) is especially relevant for potentially vulnerable populations. Low tube voltage photon-counting detector CT (PCD-CT) offers an improved iodine contrast-to-noise ratio (CNR) as compared to conventional CT scanners. We investigated optimized radiation and CM doses of PCD-CT angiography at low tube voltage in an animal model. Methods Six minipigs (median weight: 32.5 kg; IQR: 29.8-34.6 kg) underwent thoracoabdominal CTA using a clinical dual-source PCD-CT at 70 kVp with three scan protocols: (A) reference (100% CM and radiation dose), (B) increased radiation (233%) and reduced CM (56%) dose, and (C) reduced radiation (50%) and increased CM (141%) dose. CNR, subjective image quality, and radiation doses were assessed, with statistical analysis including Mann-Whitney U-test and Kruskal-Wallis tests. Results CTDIvol was 1.7 mGy (IQR: 1.5-1.8) for scan A, 4.3 mGy (IQR: 3.8-4.7) for scan B, and 0.9 mGy (IQR: 0.8-1.0) for scan C (p < 0.001). CM volumes were 16 mL (IQR: 15-17) for scan A, 10 mL (IQR: 8-10) for scan B, and 23 mL (IQR: 21-24) for scan C. No significant differences in CNR were found between scans, with medians of 26 (IQR: 24-28) for scan A, 23 (IQR: 22-26) for scan B, and 26 (IQR: 24-30) for scan C (p = 0.276). Subjective image quality was similar across scans (p = 0.342). Conclusion Low tube voltage PCD-CT angiography allows substantial reductions in radiation and CM dose while maintaining stable and improved CNR, which allows further dose flexibility for individualized CTA protocols. Relevance statement PCD-CT at low tube voltage provides a high CNR and great flexibility in dose optimization, making it particularly effective for applications where minimizing radiation and CM exposure is a priority.