Analysis of Effects of Nonuniform Beam Profile on Doppler Power Spectrum and Mean Velocity

In this paper we present a detailed simulation method to estimate the accuracy of Doppler power spectrum and mean blood velocity, using real CW Doppler transducers with twin-crystal arrangement. The method is based on dividing the sample volume into small cells using the statistics of the total power of Doppler spectrum with the same Doppler shift frequency, and from total power, which predicts errors in the mean blood velocity. Results show that the Doppler angle, vessel depth, and sample volume length are not sensitive functions for both the Doppler power spectrum and error in the mean blood velocity. However vessel diameter, displacement distance and blood velocity profiles have significant effects. Finally, comparisons between simulation and experiment results illustrated a good agreement for parabolic flow profile. These results will contribute to an improved understanding of Doppler power spectrum and error in mean blood velocity in medical ultrasound diagnostics. Keywords-continuous-wave, semicircle transducer, Doppler power spectrum, blood velocity, spectral broadening