JP2018019869A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify an object to be subjected to suppression processing from signals of a plurality of channels acquired by transmitting and receiving an ultrasonic wave.SOLUTION: A weighting processing part 30 acquires a processing signal after weighting processing for each channel by subjecting signals of a plurality of channels to weighting processing. The weighting processing part 30 executes apodization for the purpose of side lobe suppression or the like. A suppression processing part 40 identifies a processing signal to be subjected to suppression processing from the processing signals of the plurality of channels by comparing the processing signal of at least one representative channel of the plurality of channels with the processing signal of each channel. By the comparison in the suppression processing part 40, an exceptional processing signal affected, for example, by the multiple reflection of an ultrasonic wave is identified as an object to be subjected to the suppression processing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic diagnostic apparatus.

  Apodization is known as a technique for suppressing side lobes contained in a reception signal obtained by transmitting and receiving ultrasonic waves. In general, in apodization, at least one of a transmission signal and a reception signal is weighted by a larger weight as it is closer to the center of an opening composed of a plurality of vibration elements (see Patent Document 1).

JP 2010-263936 A

  In particular, in transmission / reception in the vicinity of the ultrasonic probe, a huge echo tends to be generated near the end of the opening, for example, near the center of the aperture due to the influence of multiple reflection of ultrasonic waves. If a huge echo is generated near the edge, the huge echo cannot be suppressed despite the weighting process (apodization). For example, a large signal due to the influence of multiple reflections is obtained near the edge. In some cases, the image quality of the sound wave image is deteriorated.

  It is an object of the present invention to specify a target for suppression processing from a plurality of channels of signals obtained by transmitting and receiving ultrasonic waves.

  An ultrasonic diagnostic apparatus suitable for the above-described object includes a weighting processing unit that obtains a processing signal for each channel by weighting a signal of a plurality of channels obtained by transmitting and receiving ultrasonic waves, A suppression processing unit that identifies a processing signal to be subjected to suppression processing from among the processing signals of the plurality of channels by comparison with the processing signal of at least one representative channel.

  In the above configuration, a plurality of channels of signals can be obtained using a plurality of vibration elements that transmit and receive ultrasonic waves. For example, one vibration element is associated with one channel, and a signal obtained from each vibration element is a signal of each channel. For example, a plurality of channels may be associated with one vibration element, or a signal of one channel may be formed based on signals obtained from the plurality of vibration elements.

  In the above configuration, the weighting processing unit obtains a processed signal after the weighting process for each channel by weighting the signals of the plurality of channels. The weighting processing unit performs apodization for the purpose of suppressing side lobes, for example. For example, a weighting function is used in which the weighting in the vicinity of the end of the opening is smaller than in the vicinity of the center of the opening. Depending on the deflection angle of the ultrasonic beam, for example, the weighting peak position may be moved near the center of the aperture, or the weighting peak position is fixed at the center of the aperture regardless of the deflection angle of the ultrasonic beam. May be.

  Further, in the above configuration, the suppression processing unit specifies a processing signal to be subjected to suppression processing from the processing signals of the plurality of channels by comparison with the processing signal of at least one representative channel of the plurality of channels. For example, the suppression processing unit compares the processing signal of the representative channel and the processing signal of each channel to identify the processing signal to be subjected to the suppression processing from the processing signals of the plurality of channels. The processed signal of the representative channel and the processed signal of each channel may be directly compared. For example, a reference value (for example, an amplitude reference value) obtained from the processed signal of the representative channel and a signal of the processed signal of each channel An indirect comparison comparing a value (for example, an amplitude value) may be used.

  Then, by comparison in the suppression processing unit, that is, relative comparison within a plurality of channels by setting at least one of the plurality of channels as a representative channel, for example, multiplexing of ultrasonic waves from among the processing signals of the plurality of channels. An exceptional processing signal affected by reflection or the like can be specified as a target of suppression processing. Note that the processing signal to be subjected to the suppression process is suppressed to a level that does not degrade the image quality of the ultrasonic image, for example. The processing signal to be subjected to the suppression processing is desirably replaced with, for example, the processing signal of the representative channel, but may be discarded so as not to be used for forming an ultrasonic image, for example.

  In a preferred embodiment, the suppression processing unit sets at least one channel corresponding to a central position of an ultrasonic reception aperture or the vicinity thereof as the representative channel.

  In a preferred embodiment, the suppression processing unit compares the reference amplitude based on the processing signal of the representative channel and the amplitude of the processing signal of each channel, and the amplitude of the processing signals of the plurality of channels exceeds the reference amplitude. The processing signal is a target of suppression processing.

  In a preferred embodiment, the suppression processing unit changes at least one of the position of the representative channel and the number of channels in the ultrasonic wave reception aperture according to the deflection angle of the ultrasonic beam.

  According to the present invention, the target of the suppression process is specified from the signals of a plurality of channels obtained by transmitting and receiving ultrasonic waves. For example, according to a preferred aspect of the present invention, an exceptional processing signal affected by multiple reflections of ultrasonic waves can be identified as a target of suppression processing from among a plurality of channel processing signals.

It is a figure which shows the specific example of a suitable ultrasonic diagnostic apparatus in implementation of this invention. It is a figure for demonstrating the specific example of a weighting process. It is a figure which shows the specific example of the internal structure of a suppression process part.

  FIG. 1 is a diagram showing a specific example of an ultrasonic diagnostic apparatus suitable for implementing the present invention. The ultrasonic diagnostic apparatus 100 includes a plurality of components indicated by reference numerals in FIG.

  The plurality of vibration elements 10 are ultrasonic vibration elements that each transmit and receive ultrasonic waves. For example, a linear scanning linear probe, a sector scanning sector probe, a convex scanning convex probe, and the like are realized by the plurality of vibration elements 10 arranged one-dimensionally.

  The plurality of vibration elements 10 transmit ultrasonic waves corresponding to the transmission signals. As a result, an ultrasonic transmission beam is formed and scanned. For example, a plurality of transmission beams are formed one after another in the scanning plane. In addition, a plurality of reception beams corresponding to the plurality of transmission beams are sequentially formed in the scanning plane. In FIG. 1, the components of the transmission system included in the ultrasonic diagnostic apparatus 100, that is, the components of the transmission system that outputs a transmission signal to each vibration element 10 to form an ultrasonic transmission beam are not shown. Yes.

  In FIG. 1, components of the reception system included in the ultrasonic diagnostic apparatus 100 are illustrated at the subsequent stage of the plurality of vibration elements 10. Signals (received signals) obtained from the plurality of vibration elements 10 by transmitting and receiving ultrasonic waves are processed by the plurality of reception processing units 12. Each reception processing unit 12 includes, for example, a preamplifier, a gain controller, an analog-digital converter, and the like, and receives and processes a signal obtained from each corresponding vibration element 10.

  In the specific example shown in FIG. 1, one vibration element 10 is associated with one channel (ch). That is, N vibration elements 10 are associated with N channels (N is a natural number) from channel 0 “ch0” to channel (N−1) “ch (N−1)”. Further, N reception processing units 12 are associated with the N channel.

  The phasing processing unit 20 performs phasing processing on signals after reception processing (for example, digitized signals) obtained from the plurality of reception processing units 12. The phasing processing unit 20 executes a phasing process that is a part of the function (phasing addition process) as a reception beamformer. For example, the phasing processing unit 20 performs delay processing corresponding to the channel on the signal of each channel in accordance with the delay data determined for each reception beam and for each depth. Thus, a delayed signal (for example, a digitized signal after delay processing) is output from the phasing processing unit 20 from each of a plurality of channels, for example, for each reception beam and for each depth.

  The weighting processing unit 30 performs weighting processing on the delayed signal obtained from the phasing processing unit 20 for each channel. The weighting processing unit 30 executes a weighting process known as apodization. That is, the weighting processing unit 30 performs weighting processing on the post-delay processing signal obtained from each vibration element 10 by using a larger weight as the distance from the center of the reception aperture configured by the plurality of vibration elements 10 increases, for example. By the weighting process in the weighting processing unit 30, for example, side lobes included in the processing signals obtained from the plurality of vibration elements 10 are suppressed. Thus, the weighting processing unit 30 outputs a processing signal after weighting processing (for example, a digitized signal after weighting processing) from each channel of the plurality of channels, for example, for each reception beam and for each depth.

  FIG. 2 is a diagram for explaining a specific example of the weighting process. FIG. 2A shows a specific example of a weighting function used in the weighting processing unit 30 (FIG. 1). In FIG. 2A, the horizontal axis corresponds to a plurality of channels (ch), and the magnitude of the weighting coefficient for the signal obtained from each channel corresponds to the vertical axis.

  In the specific example shown in FIG. 2A, the weighting function is such that the weighting coefficient has the maximum value (peak) in the channel corresponding to the center position of the reception aperture indicated by the broken line, and as the distance from the center position increases, that is, the end of the reception aperture. As the position gets closer, the weighting coefficient becomes smaller.

  Therefore, for example, if the magnitudes (amplitudes) of the signals of the plurality of channels (the signals obtained from the phasing processing unit 20 in FIG. 1) are all the same, the plurality of channels after the weighting processing by the weighting function in FIG. The size (amplitude) of the signal is also the same shape as the weighting function of FIG.

  However, in transmission / reception in the vicinity of the ultrasonic probe, for example, a huge echo may be generated at a position away from the center of the reception aperture due to the influence of multiple reflection of ultrasonic waves. The magnitude (amplitude) of the signal obtained from the vibration element 10 (FIG. 1) that receives the huge echo also becomes huge. Therefore, in the channel corresponding to the vibration element 10, even after the weighting process (apodization), the huge amplitude associated with the huge echo may not be suppressed as in the specific example shown in FIG.

  FIG. 2B shows a specific example of the amplitude after the weighting process by the weighting function of FIG. In FIG. 2B, the horizontal axis corresponds to a plurality of channels (ch), and the magnitude of the amplitude after weighting processing of signals obtained from each channel corresponds to the vertical axis. In the specific example shown in FIG. 2B, since a huge amplitude is obtained in the channel corresponding to the position M in the reception aperture as compared with the other channels, the channel corresponding to the position M even after the weighting process is obtained. The signal amplitude is extremely large. For example, if a reception beam is formed with the amplitude of the signal shown in FIG. 2B, the image quality of an ultrasonic image based on the reception beam may be deteriorated.

  Returning to FIG. 1, the suppression processing unit 40 specifies a signal having a large amplitude that cannot be suppressed by the weighting process from the processing signals of the plurality of channels obtained from the weighting processing unit 30, and suppresses the amplitude. The suppression processing unit 40 compares the processing signal (the signal after the weighting process) of at least one representative channel among the plurality of channels from the processing signal (the signal after the weighting process) of the plurality of channels. Identify the target processing signal.

  Further, the addition processing unit 50 performs addition processing on the signals of a plurality of channels after the suppression processing obtained from the suppression processing unit 40. The addition processing unit 50 executes addition processing that is a part of the function (phased addition processing) as a reception beamformer. The processing from the phasing processing unit 20 to the addition processing unit 50 is executed for each reception beam with respect to a plurality of reception beams. In the addition processing unit 50, for example, for each reception beam of the plurality of reception beams constituting the scanning plane. Beam data composed of received data corresponding to a plurality of depths is formed.

  Then, the image forming unit 60 forms image data such as a B-mode image based on beam data corresponding to a plurality of reception beams. An ultrasonic image corresponding to the image data is displayed on a monitor or the like.

  FIG. 3 is a diagram illustrating a specific example of the internal configuration of the suppression processing unit 40. In the specific example illustrated in FIG. 3, the suppression processing unit 40 includes a reference amplitude generation unit 42 and a plurality of comparison suppression units 44.

  The reference amplitude generation unit 42 determines the reference amplitude based on the processing signal of at least one representative channel among the plurality of channels. As the representative channel, it is desirable to use at least one channel corresponding to the center position of the reception aperture or the vicinity thereof.

  In the specific example shown in FIG. 3, a reception aperture is formed by N vibrating elements 10 (FIG. 1) corresponding to N channels from channel 0 “ch0” to channel (N−1) “ch (N−1)”. Has been. That is, N vibrating elements 10 are used as receiving elements. The two channels of the channel (N / 2-1) “ch (N / 2-1)” and the channel (N / 2) “ch (N / 2)” corresponding to the center of the reception aperture are representative channels. It's being used.

  The reference amplitude generation unit 42 is an amplitude related to two processing signals obtained from the channel (N / 2-1) and the channel (N / 2) which are representative channels, that is, two processing signals after weighting processing by the weighting processing unit 30. Is the reference amplitude R (the amplitude of the reference signal R).

  In the specific example shown in FIG. 3, the suppression processing unit 40 includes N comparison suppression units 44 corresponding to N channels. Each comparison and suppression unit 44 compares the amplitude of the processing signal A of the corresponding channel (ch) with the amplitude of the reference signal R (reference amplitude R). Each comparison suppression unit 44 determines that the processed signal A is a target of the suppression process when the amplitude of the processed signal A of the corresponding channel exceeds the amplitude of the reference signal R (A> R). Each comparison suppression unit 44 determines that the processed signal A is not a target of the suppression process when the amplitude of the processed signal A of the corresponding channel is equal to or smaller than the amplitude of the reference signal R (A ≦ R).

  Each comparison suppression unit 44 outputs the amplitude of the reference signal R (reference amplitude R) as a result of the suppression processing when the processing signal A of the corresponding channel is the target of the suppression processing, and the processing signal of the corresponding channel If A is not an object of suppression processing, the amplitude of the processing signal A is output as it is. For the representative channel, the amplitude of the processed signal A may be always output to the addition processing unit 50 without comparison with the reference amplitude R, that is, without performing the suppression process.

  In this way, the amplitude of the processed signal A of each channel (no suppression) or the amplitude of the reference signal R (with suppression) is output from each of the N comparison suppression units 44, and the amplitude of the N channel signal in the addition processing unit 50. Are added. The processing in the suppression processing unit 40 is executed, for example, for each reception beam of the plurality of reception beams and for each depth. As a result, the amplitude of the processing signal A (without suppression) or the amplitude of the reference signal R (with suppression) is output from the suppression processing unit 40 from each channel of the plurality of channels, for example, for each reception beam and for each depth. The

  The suppression processing unit 40 may change at least one of the position of the representative channel and the number of channels in the ultrasonic wave reception opening according to the deflection angle of the ultrasonic beam. When an ultrasonic beam (received beam) is deflected, a large echo is likely to occur on the side with a smaller deflection angle than on the side with a larger deflection angle. May be moved, or the number of representative channels may be increased on the side with a smaller deflection angle.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  DESCRIPTION OF SYMBOLS 10 vibration element, 12 reception process part, 20 phasing process part, 30 weighting process part, 40 suppression process part, 50 addition process part, 60 image formation part, 100 ultrasonic diagnostic apparatus.

Claims (4)

A weighting processing unit that obtains a processing signal for each channel by weighting a signal of a plurality of channels obtained by transmitting and receiving ultrasonic waves;
A suppression processing unit that identifies a processing signal to be subjected to suppression processing from among the processing signals of the plurality of channels by comparison with a processing signal of at least one representative channel of the plurality of channels;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The suppression processing unit uses at least one channel corresponding to the central position of the ultrasonic reception aperture or the vicinity thereof as the representative channel,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The suppression processing unit compares the reference amplitude based on the processing signal of the representative channel with the amplitude of the processing signal of each channel, and suppresses the processing signal whose amplitude exceeds the reference amplitude among the processing signals of the plurality of channels. Subject to
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The suppression processing unit changes at least one of the position of the representative channel and the number of channels in the ultrasonic reception aperture according to the deflection angle of the ultrasonic beam.
An ultrasonic diagnostic apparatus.

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