METHODS AND APPARATUS FOR ULTRASOUND IMAGING
First Claim
Patent Images
1. A method for automatically controlling the gain from a Doppler signal processor during ultrasound imaging comprising:
- inputting returned ultrasound signals;
demodulating the returned ultrasound signals;
wall-filtering the returned ultrasound signals producing Doppler flow signals;
performing spectral analysis on the Doppler flow signals producing a Doppler spectrum;
setting a high level signal threshold;
setting a low level signal threshold;
setting a noise floor level threshold;
detecting a peak Doppler spectrum level and a Doppler spectrum maximum noise floor from the Doppler flow signals;
increasing Doppler flow signal gain if the peak Doppler spectrum amplitude is less than the low level signal threshold until the peak Doppler spectrum amplitude equals the high level signal threshold or the maximum noise floor is equal to the noise floor level threshold; and
decreasing the Doppler flow signal gain if the peak Doppler spectrum amplitude is greater than the high level signal threshold until the peak Doppler spectrum amplitude equals the high level signal threshold or the maximum noise floor is equal to the noise floor level threshold.
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Abstract
A system and method is disclosed that examines Doppler spectrum signals output by an ultrasound system when measuring blood flow velocity to determine a proper Doppler gain and to suppress noise manifest in the Doppler spectrum. Noise present in the Doppler spectrum is examined and used as a criterion for optimal gain. If the Doppler gain is too high or too low in accordance with predetermined levels, overall gain is adjusted accordingly.
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Citations
21 Claims
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1. A method for automatically controlling the gain from a Doppler signal processor during ultrasound imaging comprising:
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inputting returned ultrasound signals; demodulating the returned ultrasound signals; wall-filtering the returned ultrasound signals producing Doppler flow signals; performing spectral analysis on the Doppler flow signals producing a Doppler spectrum; setting a high level signal threshold; setting a low level signal threshold; setting a noise floor level threshold; detecting a peak Doppler spectrum level and a Doppler spectrum maximum noise floor from the Doppler flow signals; increasing Doppler flow signal gain if the peak Doppler spectrum amplitude is less than the low level signal threshold until the peak Doppler spectrum amplitude equals the high level signal threshold or the maximum noise floor is equal to the noise floor level threshold; and decreasing the Doppler flow signal gain if the peak Doppler spectrum amplitude is greater than the high level signal threshold until the peak Doppler spectrum amplitude equals the high level signal threshold or the maximum noise floor is equal to the noise floor level threshold. - View Dependent Claims (2, 3, 4, 5)
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6. A system for automatically controlling the gain of a Doppler spectrum processor during ultrasound imaging comprising:
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a receiver configured to receive returned ultrasound signals and having an output; a Doppler signal processor having an input coupled to the receiver output and an output, the Doppler signal processor configured to demodulate and wall-filter the returned ultrasound signals and output Doppler flow signals; a variable gain amplifier having an input coupled to the Doppler signal processor output, a gain control signal input and an output, the variable gain amplifier configured to vary the gain of the Doppler flow signals; a spectrum analyzer having an input coupled to the variable gain amplifier output and an output, the spectrum analyzer configured to convert the Doppler flow signals into their corresponding frequency spectrum; and an automatic gain engine coupled to the spectrum analyzer output, the automatic gain engine configured to receive the Doppler spectrum and detect a peak Doppler spectrum amplitude and a maximum noise floor wherein a gain control signal is calculated and coupled to the variable gain amplifier gain control signal input based on the maximum noise floor present in the Doppler flow signals spectrum and predetermined high, low and noise floor signal level thresholds wherein if the peak Doppler spectrum amplitude is greater than the high level signal threshold, or less than the low level signal threshold, overall gain is adjusted to maintain the peak Doppler spectrum amplitude greater than the low level signal threshold and less than the high level signal threshold. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method for suppressing noise manifest on Doppler spectrum signals comprising:
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inputting the Doppler spectrum signals; receiving a Doppler gain control signal; using a noise suppression gain curve g(p) corresponding to the Doppler gain control signal; and processing the Doppler spectrum amplitudes with the noise suppression gain curve g(p) wherein each frequency of the Doppler spectrum amplitude is adjusted according to a response of the noise suppression gain curve. - View Dependent Claims (14, 15)
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16. A noise suppressor for suppressing noise manifest on Doppler spectrum signals comprising:
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an input configured to receive gain adjusted Doppler spectrum signals; a gain control signal input configured to receive a gain control signal that is used to adjust the gain for the gain adjusted Doppler spectrum signals to generate a noise suppression gain curve g(p); a gain function processor configured to process the gain adjusted Doppler flow signals with the noise suppression gain curve g(p), wherein each spectrum component of the Doppler spectrum signal input is adjusted in amplitude according to the response of the noise suppression gain curve g(p); and an output configured to output noise suppressed, gain adjusted Doppler flow signals. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification