Quantitative flow measurements were assessed in laboratory model using pulsed doppler ultrasonography. A hydrodynamic model consisting of a water bath, tubing, water reservoir was used to obtain absolute volumetric flow measurements. Parameters including angle of incidence, size of tubing and transducer frequency being fixed, the effect of varying sample volume on the measurement of quantitative flow and relationship between the actual flow rate and Doppler measured flow was studied.
Doppler measurements of flow in tube were shown to vary linearly with the absolute measurements of flow and correlation coefficient, r, approached 1.0, meaning high degree of linear relationship between the two. The ratio of the Doppler-measured flow to the actual flow was about 1.0, probably due to turbulent flow. Variation of the sample volume had slight effect on the calculated flow, with greater sample volume giving slightly larger calculated flow, which could not be explained by the analysis of the flow profile, and so needed further study.
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