Indirect Computed Tomography Venography With a Low-Tube-Voltage Technique: Reduction in the Radiation and Contrast Material Dose-A Prospective Randomized Study

Objective: The objective of the study was to investigate the effects of low-tube-voltage computed tomography (CT) venography on qualitative and quantitative image parameters and the radiation dose. Methods: Eighty-eight studies on 84 patients underwent pelvic and lower-extremity CT venography under protocol A (standard 120 kV with 150 mL of contrast material, n = 44) or protocol B (80 kV with 100 mL of contrast material, n = 44) on a 64-detector CT scanner. We compared the dose length product in the 2 protocols. Two blinded observers measured CT attenuation in the veins, the image noise, contrast-to-noise ratio, and figure of merit. Results: The mean dose length product was significantly lower under protocol B than A (603.2 [SD, 67.2] vs 1131.7 [SD, 67.0] mGy x cm) (P < 0.01). Mean CT attenuation of the veins was significantly greater with protocol B (125.3 [SD, 16.2] vs 106.1 [SD, 16.0] Hounsfield units) (P < 0.01), and the mean image noise was also significantly higher under protocol B (6.6 [SD, 0.8] vs 4.9 [SD, 0.7] Hounsfield units) (P < 0.01). There was no difference in contrast-to-noise ratio (P = 0.46). Figure of merit was significantly higher under protocol B (P < 0.01). Conclusions: Computed tomography venography with a low-tube-voltage technique allows reducing the radiation dose and the amount of contrast material without image quality degradation.