Ultrasonic imaging system and method with ringdown reduction
First Claim
1. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
- providing a ringdown reference signal;
modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and
subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts.
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Accused Products
Abstract
Ultrasonic imaging method and apparatus in which a reference waveform which is substantially free of echoes is modified to be equal to a weighted sum of the reference waveform and filtered signals from the transducing elements which transmit the ultrasonic waves and receive the reflected echoes. The modified waveform is then subtracted from the transducer signals to remove ringdown signals and provide a displayed image which is substantially free of ringdown artifacts.
96 Citations
49 Claims
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1. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and is determined in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andthe modified reference signal Rn is determined in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =γ
I.sub.n +(1-γ
)R.sub.n-1,where Rn-1 is a previous reference signal and γ
is a second weighting factor.
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13. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; determining a weighted tissue sum for the current transducer signal and the previous transducer signal; determining a weighted tissue difference for the current transducer signal and the previous transducer signal; determining a motion weight based on the weighted tissue sum and the weighted tissue difference; modifying the ringdown reference signal on the basis of the motion weight to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts. - View Dependent Claims (14)
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15. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and is determined in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andthe modified reference signal Rn is determined in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1 ·
W1)/(1+W1)where Rn-1 is a previous reference signal and W1 is another weighting factor. - View Dependent Claims (16)
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17. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and is determined in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andthe modified reference signal Rn is determined in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1)/2where Rn-1 is a previous reference signal.
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18. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and is determined in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =S.sub.n +I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals and is a sum of n-1 previous transducer signals; and the modified reference signal Rn is determined in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =I.sub.n /n,where n is the number of transducer signals included in the sum In. - View Dependent Claims (19)
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20. In a system for reducing ringdown artifacts which arise in ultrasonic imaging when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component; and means subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts. - View Dependent Claims (21, 22, 23, 24)
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25. In a system for reducing ringdown artifacts which arise in ultrasonic imaging when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component; and means subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and the means for modifying determines In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andmodifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =γ
I.sub.n +(1-γ
)R.sub.n-1,where Rn-1 is a previous reference signal and γ
is a second weighting factor.
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26. In a system for reducing ringdown artifacts which arise in ultrasonic imaging when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component; and means subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and the means for modifying determines In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor, andmodifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1 ·
W1)/(1+W1)where Rn-1 is a previous reference signal and W1 is another weighting factor. - View Dependent Claims (27)
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28. In a system for reducing ringdown artifacts which arise in ultrasonic imaging when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component; and means subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and the means for modifying determines In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andmodifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1)/2where Rn-1 is a previous ringdown reference signal.
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29. In a system for reducing ringdown artifacts which arise in ultrasonic imaging when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component; and means subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and the means for modifying determines In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =S.sub.n +I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered transducer signals and is a sum of n-1 previous transducer signals; and modifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =I.sub.n /n,where n is the number of transducer signals included in the sum In. - View Dependent Claims (30)
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31. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; detecting tissue motion in one of the transducer signals from the transducer elements which contains an echo component and a ringdown component; modifying the ringdown reference signal to provide a modified reference signal based on the detected tissue motion; and subtracting the modified reference signal from one of the signals from the transducer elements to provide an output signal which is substantially free of ringdown artifacts.
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32. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; detecting tissue motion in one of the transducer signals from the transducer elements which contains an echo component and a ringdown component; modifying the ringdown reference signal to provide a modified reference signal based on the detected tissue motion; and subtracting the modified reference signal from one of the signals from the transducer elements to provide an output signal which is substantially free of ringdown artifacts; wherein the tissue motion is detected and the reference signal is modified by; determining a weighted tissue sum for a current transducer signal and a previous transducer signal; determining a weighted tissue difference for the current transducer signal and the previous transducer signal; determining a motion weight based on the weighted tissue sum and the weighted tissue difference; and modifying the reference signal on the basis of the motion weight. - View Dependent Claims (33)
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34. In a system for reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means for detecting tissue motion in one of the transducer signals from the transducer elements which contains an echo component and a ringdown component; means for modifying the ringdown reference signal to provide a modified reference signal based on the detected tissue motion; and means for subtracting the modified reference signal from one of the signals from the transducer elements to provide an output signal which is substantially free of ringdown artifacts.
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35. In a system for reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals:
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means for providing a ringdown reference signal; means responsive to signals from the transducer elements for detecting tissue motion which contains an echo component and a ringdown component by generating a weighted tissue sum from a weighted sum of a current transducer signal and a previous transducer signal, generating a weighted tissue difference from a weighted difference of the current transducer signal and the previous transducer signal, and determining a motion weight based on the weighted tissue sum and the weighted tissue difference; means for modifying the ringdown reference signal on the basis of the motion weight to provide a modified reference signal based on the detected tissue motion; and means for subtracting the modified reference signal from one of the signals from the transducer elements to provide an output signal which is substantially free of ringdown artifacts. - View Dependent Claims (36)
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37. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; selecting one weighting factor of a plurality of weighting factors based on a characterization signal for one of the transducer elements; modifying the reference signal by applying the weighting factor to transducer signals and to the reference signal; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts.
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38. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; selecting one weighting factor of a plurality of weighting factors based on a characterization signal for one of the transducer elements; modifying the reference signal by applying the weighting factor to transducer signals and to the reference signal; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts; wherein the tissue motion is detected and the reference signal is modified by; generating a weighted tissue sum from a weighted sum of a current transducer signal and a previous transducer signal; generating a weighted tissue difference from a weighted difference of the current transducer signal and the previous transducer signal; determining a motion weight based on the weighted tissue sum and the weighted tissue difference; and modifying the reference signal on the basis of the motion weight. - View Dependent Claims (39, 40)
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41. An ultrasonic imaging system comprising:
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a probe assembly having a plurality of elements for transmitting ultrasonic signals and receiving echo signals in response thereto; at least one amplifier for amplifying signals from the elements, the signals having a ringdown component arising from continued vibration of the elements after the ultrasonic signals are transmitted and a tissue component corresponding to the echo signals; an analog-to-digital converter for converting the amplified signals to digital signals; a beam former for transforming the digital signals from a plurality of elements into beams having both a ringdown component and a tissue component; a filter for reducing noise in the beams; a ringdown reference generator for generating a ringdown reference signal, and modifying the reference signal to provide a modified reference signal comprising a weighted sum of the reference signal and the filtered beams; a subtractor for subtracting the modified reference signal from one of the beams to provide an output signal which is substantially free of ringdown artifacts; a scan converter for converting the output signal to a display signal; and a display responsive to the display signal for providing a visual image. - View Dependent Claims (42, 43, 44)
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45. An ultrasonic imaging system comprising:
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a probe assembly having a plurality of elements for transmitting ultrasonic signals and receiving echo signals in response thereto; at least one amplifier for amplifying signals from the elements, the signals having a ringdown component arising from continued vibration of the elements after the ultrasonic signals are transmitted and a tissue component corresponding to the echo signals; an analog-to-digital converter for converting the amplified signals to digital signals; a beam former for transforming the digital signals from a plurality of elements into beams having both a ringdown component and a tissue component; a filter for reducing noise in the beams; a ringdown reference generator for generating a ringdown reference signal, and modifying the reference signal to provide a modified reference signal comprising a weighted sum of the reference signal and the filtered beams; a subtractor for subtracting the modified reference signal from one of the beams to provide an output signal which is substantially free of ringdown artifacts; a scan converter for converting the output signal to a display signal; and a display responsive to the display signal for providing a visual image; wherein the ringdown reference generator provides filtered beams In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered beams, and β
is a first weighting factor; andthe ringdown reference generator modifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =γ
I.sub.n +(1-γ
)R.sub.n-1,where Rn-1 is a previous reference signal and γ
is a second weighting factor.
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46. An ultrasonic imaging system comprising:
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a probe assembly having a plurality of elements for transmitting ultrasonic signals and receiving echo signals in response thereto; at least one amplifier for amplifying signals from the elements, the signals having a ringdown component arising from continued vibration of the elements after the ultrasonic signals are transmitted and a tissue component corresponding to the echo signals; an analog-to-digital converter for converting the amplified signals to digital signals; a beam former for transforming the digital signals from a plurality of elements into beams having both a ringdown component and a tissue component; a filter for reducing noise in the beams; a ringdown reference generator for generating a ringdown reference signal, and modifying the reference signal to provide a modified reference signal comprising a weighted sum of the reference signal and the filtered beams; a subtractor for subtracting the modified reference signal from one of the beams to provide an output signal which is substantially free of ringdown artifacts; a scan converter for converting the output signal to a display signal; and a display responsive to the display signal for providing a visual image; wherein the ringdown reference generator provides filtered beams In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered beams, and β
is a first weighting factor, andthe ringdown reference generator modifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1 ·
W.sub.1)/(1+W1)where Rn-1 is a previous reference signal and W1 is another weighting factor.
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47. An ultrasonic imaging system comprising:
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a probe assembly having a plurality of elements for transmitting ultrasonic signals and receiving echo signals in response thereto; at least one amplifier for amplifying signals from the elements, the signals having a ringdown component arising from continued vibration of the elements after the ultrasonic signals are transmitted and a tissue component corresponding to the echo signals; an analog-to-digital converter for converting the amplified signals to digital signals; a beam former for transforming the digital signals from a plurality of elements into beams having both a ringdown component and a tissue component; a filter for reducing noise in the beams; a ringdown reference generator for generating a ringdown reference signal, and modifying the reference signal to provide a modified reference signal comprising a weighted sum of the reference signal and the filtered beams; a subtractor for subtracting the modified reference signal from one of the beams to provide an output signal which is substantially free of ringdown artifacts; a scan converter for converting the output signal to a display signal; and a display responsive to the display signal for providing a visual image; wherein the ringdown reference generator provides filtered beams In in accordance with the relationship;
space="preserve" listing-type="equation">I.sub.n =β
S.sub.n +(1-β
)I.sub.n-1,where Sn is the current transducer signal, In-1 represents previous filtered beams, and β
is a first weighting factor; andthe ringdown reference generator modifies the ringdown reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =(I.sub.n +R.sub.n-1)/2where Rn-1 is a previous ringdown reference signal.
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48. In a method of reducing ringdown artifacts which arise in an ultrasonic imaging system when transducer elements which transmit ultrasonic signals and receive echo signals continue to vibrate after being stimulated to transmit the ultrasonic signals, the steps of:
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providing a ringdown reference signal; modifying the ringdown reference signal to provide a modified reference signal comprising a weighted sum of the ringdown reference signal and filtered transducer signals which contain an echo component and a ringdown component from the transducer elements; and subtracting the modified reference signal from one of the transducer signals to provide an output signal which is substantially free of ringdown artifacts, where In represents the filtered transducer signals and is determined in accordance with the relationship;
##EQU2## where Sn is the current transducer signal, In-1 represents previous filtered transducer signals, and β
is a first weighting factor; andthe modified reference signal Rn is determined in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =γ
I.sub.n +(1-γ
)R.sub.n-1,where Rn-1 is a previous reference signal and γ
is a second weighting factor.
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49. A method of generating a modified reference signal, comprising the steps of:
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providing a reference signal (Rn-1); and calculating a modified reference signal Rn in accordance with the relationship;
space="preserve" listing-type="equation">R.sub.n =γ
I.sub.n +(1-γ
)R.sub.n-1,where In represents filtered transducer signals and γ
is a weighting factor.
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Specification