IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
In order to reduce the fluctuations in the velocity magnitude estimate, we propose a modification... more In order to reduce the fluctuations in the velocity magnitude estimate, we propose a modification to the standard algorithm for reconstructing the (two component) vector velocity from the measured Doppler shifts in two directions. This uses the standard dual-beam algorithm, combined with temporal smoothing, to find only the velocity angle, then uses the single-beam algorithm to estimate the velocity magnitude. We present initial data showing the significant reduction in velocity estimate fluctuation that this hybrid method achieves compared to the standard algorithm.
The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its s... more The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
In order to reduce the fluctuations in the velocity magnitude estimate, we propose a modification... more In order to reduce the fluctuations in the velocity magnitude estimate, we propose a modification to the standard algorithm for reconstructing the (two component) vector velocity from the measured Doppler shifts in two directions. This uses the standard dual-beam algorithm, combined with temporal smoothing, to find only the velocity angle, then uses the single-beam algorithm to estimate the velocity magnitude. We present initial data showing the significant reduction in velocity estimate fluctuation that this hybrid method achieves compared to the standard algorithm.
The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its s... more The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.
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Papers by Helen Routh