Journal ArticleDOI
Analysis of Transit Time Effects on Doppler Flow Measurement
TLDR
It is shown that random or pseudorandom Dopplers will give the same output spectrum as pulsed RF Doppler, provided that the transmitted spectral density of the RF system has the same envelope as that of the noise system.Abstract:
A relation is derived between the transmitted spectral density and the output spectral density of broad bandwidth, random signal, Doppler flow measurement systems operating under conditions where the fluid transit time is limited by the transmitted signal bandwidth and not by beam geometry. The fact that this result is already known to hold for pulsed radio frequency (RF) Doppler proves that random or pseudorandom Dopplers will give the same output spectrum as pulsed RF Dopplers, provided that the transmitted spectral density of the RF system has the same envelope as that of the noise system.read more
Citations
More filters
Journal ArticleDOI
Measurement of blood flow by ultrasound: accuracy and sources of error.
TL;DR: The Doppler methods are capable of good absolute accuracy when suitably designed equipment is used in appropriate situations, with systematic errors of 6% of less; there are, however, considerable random errors.
Journal ArticleDOI
Clutter filter design for ultrasound color flow imaging
TL;DR: The best filters from each of the three classes of filters gave comparable bias and variance of the mean blood velocity estimates, however, polynomial regression filters and projection-initialized IIR filters had a slightly better frequency response than could be obtained with FIR filters.
Journal ArticleDOI
A Theoretical Study of the Scattering of Ultrasound from Blood
TL;DR: An expression for the received signal in ultrasonic blood velocity measurements is given and the stochastic properties of the signal are discussed with reference to the information content about the velocity field of the blood.
Journal ArticleDOI
High-frequency color flow imaging of the microcirculation
David E. Goertz,David E. Goertz,Joanne L. Yu,Robert S. Kerbel,Peter N. Burns,F. Stuart Foster +5 more
TL;DR: In this article, a slow-scan color flow imaging (CFI) system operating in the 20-100-MHz range has been optimized to image the microcirculation of a murine ear model.
Journal ArticleDOI
The Dependence of Ultrasound Doppler Bandwidth on Beam Geometry
TL;DR: In this article, the authors derived the Doppler output signal bandwidth caused by constant velocity flow through the waist of focused transducers and through the intermediate and far field of unfocused transducers.
References
More filters
Journal ArticleDOI
Theoretical Analysis of the CW Doppler Ultrasonic Flowmeter
William R. Brody,James D. Meindl +1 more
TL;DR: A general model for the Doppler flowmeter based upon stochastic considerations of the scattering of ultrasound by blood is introduced, which characterizes the back- scattered ultrasound as a Gaussian random process and the expression for the autocovariance function is derived.
Journal ArticleDOI
Ultrasonic Doppler technique for imaging blood vessels.
John M. Reid,Merrill P. Spencer +1 more
TL;DR: Present ultrasonic Doppler flow detectors that use the Dopplers effect on waves scattered from moving blood have provided useful information when directed by hand to trace the circulation of animals and man.
Journal ArticleDOI
On the instantaneous measurement of bloodflow by ultrasonic means.
TL;DR: A new method is described to estimate that velocity from the received signal of a Doppler flowmeter using continuous ultrasound based on the determination of the frequency shift averaged over the power density spectrum of that signal.
Journal ArticleDOI
Ultrasonic random‐signal flow measurement system
P. J. Bendick,V. L. Newhouse +1 more
TL;DR: In this article, an ultrasonic random-signal flow measurement system is described which is shown to have no range ambiguity and to be able to transmit continuously, thus having a low peak to average power ratio.