Gain setting in doppler haemodynamic monitors
First Claim
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1. A method of automatically setting a signal gain in a Doppler ultrasound haemodynamic monitor comprising the acts of:
- setting a signal gain in a Doppler ultrasound haemodynamic monitor;
acquiring ultrasound data, by the Doppler ultrasound haemodynamic monitor, by scanning a region of interest;
identifying an acceptable number of velocity components in an instantaneous blood velocity spectrum of the ultrasound data that exceeds a pre-defined minimum value;
comparing the acceptable number of velocity components to a predetermined threshold;
increasing a control variable when the acceptable number of velocity components is above said predetermined threshold;
decreasing the control variable when the acceptable number of velocity components is below said predetermined threshold;
comparing the control variable to a predetermined band; and
automatically adjusting the signal gain when the control variable is outside the predetermined band.
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Abstract
This invention relates to a method of automatically setting the gain of an echo signal in a Doppler ultrasound haemodynamic monitor. In essence the invention comprises monitoring the strength of velocity components measured by the apparatus, and identifying a group of such components occupying a particular band within the overall velocity spectrum. The signal gain is then adjusted so that the perceived width of the band falls within predetermined limits. The monitoring or assessment of the velocity components is preferably undertaken when the overall flow velocity is high e.g. during systole.
49 Citations
19 Claims
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1. A method of automatically setting a signal gain in a Doppler ultrasound haemodynamic monitor comprising the acts of:
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setting a signal gain in a Doppler ultrasound haemodynamic monitor; acquiring ultrasound data, by the Doppler ultrasound haemodynamic monitor, by scanning a region of interest; identifying an acceptable number of velocity components in an instantaneous blood velocity spectrum of the ultrasound data that exceeds a pre-defined minimum value; comparing the acceptable number of velocity components to a predetermined threshold; increasing a control variable when the acceptable number of velocity components is above said predetermined threshold; decreasing the control variable when the acceptable number of velocity components is below said predetermined threshold; comparing the control variable to a predetermined band; and automatically adjusting the signal gain when the control variable is outside the predetermined band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of adjusting signal gain in a Doppler ultrasound haemodynamic monitor comprising the acts of:
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acquiring ultrasound data, by the Doppler ultrasound haemodynamic monitor, by scanning a region of interest; setting a signal gain in the Doppler ultrasound haemodynamic monitor; assessing the strength of each of a plurality of individual velocity components of an instantaneous blood velocity spectrum of the ultrasound data; identifying an acceptable number of velocity components from the plurality of individual velocity components, wherein the strength of the acceptable number of velocity components is above a pre-defined minimum value; comparing the acceptable number of velocity components to predetermined upper and lower limits; and automatically adjusting the signal gain such that the acceptable number of velocity components falls within the predetermined upper and lower limits. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification