Room: AAPM ePoster Library
Purpose: Peak velocity is an essential Doppler ultrasound quality control measurement; however, the effects of varying acquisition parameters is poorly understood. The purpose of this work was to quantify how acquisition parameters and phantom setup affect peak velocity measurements.
Methods: A CIRS Model 069 Doppler ultrasound flow phantom was used in continuous flow mode to simulate blood flow through a vessel. The pulse-wave velocity profiles were acquired in multiple phantom setup and acquisition scenarios. Acquisition parameters considered included brightness gain, data acquisition rate, and wall filter strength. Phantom set up parameters including the depth of the vessel and the flow rate were also considered. Each of these was independently modified to isolate their effect on the peak velocity measurement. For each acquisition and depth setting, the velocity profile was analyzed using in-house MATLAB software to calculate peak velocity.
Results: Our experimental results suggest that peak velocity measurements are most strongly affected by pulsed-wave Doppler gain and the depth of the vessel. Other factors had relatively smaller effect. As the gain was increased, the velocity spectrum increased in pixel brightness and broadened. Our data demonstrates a 20% variation in measured peak velocity when comparing high-gain to low-gain measurements. As the depth of acquisition was increased, we measured a decrease in peak velocity. Relative to the peak velocity at the most superficial position, the peak velocity decreased by 16.1% per cm, 10.6% per cm, and 9.0% per cm for L12-5, L12-3, and C5-1 transducers respectively.
Conclusion: Parameter consistency is essential to reliable Doppler ultrasound quality control. Our experimental characterization of a Doppler flow phantom can be used to define clinically-acceptable uncertainty ranges of peak velocity measurements at specific flow rates, acquisition parameters, and flow depth.