JP2013000351A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect apparatus-derived harmonic components caused by a signal waveform distortion and to prevent or reduce the generation of the apparatus-derived harmonic components in an ultrasonic diagnostic apparatus that displays harmonic images.SOLUTION: A harmonic extracting section 36 extracts a third-order harmonic component (3fO) as a specific harmonic component and also extracts a reference component (a fundamental wave component (fO) or a second-order harmonic component (2fO)). A state signal generating section 44 generates a state signal by comparing the specific harmonic component with the reference component. When a waveform is distorted due to amplitude becoming excessive in analog receive signal processing, an odd-order harmonic component (particularly the third-order harmonic component) relatively appears strong. The state signal shows the presence/absence and degree of the apparatus-derived harmonic component. Based on the state signal, a predetermined display is made on a display screen, or a gain in the analog receive signal processing is adjusted.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that displays an ultrasonic image such as a harmonic image.

  An ultrasonic diagnostic apparatus is an apparatus that forms an ultrasonic image by transmitting and receiving ultrasonic waves to and from a living body. In an ultrasonic diagnostic apparatus having a harmonic component display function, reflected waves from a living body are received by a plurality of vibration elements, thereby generating a plurality of received signals. Beam data is formed by phasing addition processing for a plurality of received signals. Harmonic components included in the beam data are extracted, thereby generating a harmonic image. When the harmonic component generated at the time of reflection in the living tissue is imaged, and when the harmonic component generated by reflection or destruction of the contrast agent injected into the living body is imaged, There is. The former is tissue-harmonic imaging and the latter is contrast harmonic imaging. As a method for extracting harmonic components, a filter method, a pulse modulation method, a pulse inversion method, and the like are known.

  Since the level of the harmonic component contained in the received signal is generally about several tens of dB lower than the level of the fundamental component, it is necessary to significantly increase the gain of the entire received signal in order to form a harmonic image. is there. However, when a reflected wave from a strong reflector such as an organ surface in a living body is received, the amplitude of the received signal is locally excessive and the amplitude of the received signal is saturated, that is, the received signal is distorted. For example, if the amplitude of the amplified received signal exceeds the input range of the A / D converter or exceeds the linear operating range of the amplifier, the received signal is distorted there, and a harmonic component is generated in the apparatus. Such a harmonic component is an extra harmonic component that should be distinguished from a biologically derived harmonic component generated in a tissue in a living body or a contrast medium, and can be referred to as a device-derived harmonic component.

  When the device-derived harmonic component is generated, the device-derived harmonic component is also reflected on the harmonic image together with the living body-derived harmonic component, thereby causing misidentification and the like. For example, when imaging a contrast agent, it is desirable that the biological tissue is not imaged or highlighted, but if there is a strong reflection site such as a tissue boundary, it will appear on the harmonic image, Or there is a problem that it is highlighted. As a result, there is a possibility that a contrast agent is present there. In the receiving unit, since a plurality of received signals are phased and added, unnecessary harmonic components generated in individual channels are also added and appear as artifacts on the harmonic image. In order to prevent this, if the gain in each channel is kept low uniformly, the biologically derived harmonic component cannot be imaged sufficiently.

  The above problem is particularly problematic when displaying a harmonic image. However, even when displaying a normal ultrasonic image (fundamental wave component image), saturation of the received signal in the apparatus should be avoided. When the received signal is saturated, each mountain waveform is clipped, and the received signal approaches a rectangular wave. If this is seen on the frequency axis, it can be regarded as an increase in odd harmonic components.

JP 2004-135705 A Japanese Patent No. 4557579 JP 2010-274111 A JP 2008-188266 A Japanese Patent No. 4597491

  Patent Document 1 discloses an ultrasonic diagnostic apparatus that calculates a ratio between a fundamental wave component and a harmonic component included in a received signal and adjusts a gain based on the ratio. This apparatus does not generate a harmonic image, and the ratio between the fundamental wave component and the harmonic component is used to reduce side lobes. Patent Document 2 discloses a technique for attenuating a received signal by attenuating a fundamental wave component by providing a filter (HPF) for reducing a low frequency component in an upstream stage of an amplifier in an ultrasonic diagnostic apparatus. ing. Patent Documents 1 and 2 do not describe the concept of detecting information that indicates the possibility of the occurrence of in-device harmonic components and utilizing it. Patent Literature 3-5 does not describe such a concept.

  An object of the present invention is to enable accurate detection of the occurrence of harmonic components other than the harmonic components generated in a living body. Alternatively, such an unnecessary harmonic component is suppressed.

  Preferably, the ultrasonic diagnostic apparatus extracts an ultrasonic image forming unit that forms an ultrasonic image based on reception data obtained by transmission and reception of ultrasonic waves, and a specific harmonic component included in the reception data. 1 extraction means, second extraction means for extracting a reference component included in the received data, and comparing the specific harmonic component with the reference component, thereby including a device-derived harmonic component in the received data. Comparing means for generating a status signal indicating whether or not there is a possibility of being present.

  According to the above configuration, from the comparison between the specific harmonic component included in the received data and the reference component, a state signal indicating the possibility or the extent of the apparatus-derived harmonic component being included in the received data is generated, The status signal can be used for operation control and display processing. That is, focusing on the unique characteristics of the device-derived harmonic component, the extraction conditions are determined so that the presence of the device-derived harmonic component can be accurately identified even in the presence of the biological-derived harmonic component, Also, a reference signal as a comparison target is determined, and further comparison processing is performed. The generated state signal is preferably used for at least one of operation control and display processing.

  Preferably, the ultrasonic image is a harmonic image reflecting a biologically derived harmonic component included in the reception data, the specific harmonic component is an odd-order harmonic component, and the reference component is a fundamental wave component and At least one of even harmonic components. Preferably, the specific harmonic component is a third harmonic component. When the received signal waveform is distorted in analog signal processing, it has been found that odd harmonic components are strongly generated, unlike biologically derived harmonic components. Can be evaluated, that is, the degree of signal distortion. As the odd harmonic components, the third harmonic component, the fifth harmonic component, the seventh harmonic component, etc. can be raised, but usually the third harmonic component has the highest power and is observed. Desirable. The reference component is preferably a second harmonic component, but may be a fundamental component. You can mix them. Prior to the comparison, normalization processing such as coefficient multiplication may be applied to both components or one component as necessary. For example, the third harmonic component and the second harmonic component that have undergone such pre-processing are compared, the number of times the difference or ratio of both exceeds a predetermined value, and the count value is constant in a predetermined unit such as a frame When the number becomes more than the number, the display process and the operation condition may be changed. In addition, it is possible to evaluate only the specific harmonic component alone, but in that case, it is determined whether the observed specific harmonic component is a device-derived harmonic component or a biological-derived harmonic component. Since it becomes difficult, it is desirable to extract a comparison object from the same received signal. Such a comparison may be performed on a part of the frame instead of the comparison.

  Preferably, display processing means for displaying an indicator visually indicating whether or not there is a possibility that the apparatus harmonic component is included based on the state signal. According to this configuration, convenience in image observation can be achieved, and gain adjustment, beam deflection angle adjustment, and the like can be urged to the user.

  Preferably, gain control means for controlling a gain of an analog reception signal that is a source of the reception data based on the state signal is included. It is desirable to reduce the gain automatically when there is a possibility of amplitude saturation, that is, signal waveform distortion. Of course, control for increasing the gain may be performed in accordance with how the specific harmonic component is generated. The conventional AGC (automatic gain adjustment function) is basically a gain adjustment based on the signal amplitude itself, but the above configuration is a gain adjustment according to the magnitude of a specific harmonic component, and is unnecessary in the apparatus. This is different from the prior art in that it aims to reduce harmonics.

  Preferably, the gain control means further controls the gain of the analog reception signal in accordance with the depth of the reception point. According to this, gain adjustment can be performed according to the depth and according to the occurrence of distortion. The status signal is used for TGC control or STC control.

  Desirably, a compensation control means is provided for performing gain compensation for compensating for the suppression of the gain of the analog reception signal with respect to the digital reception signal as the reception data obtained by conversion of the analog reception signal. According to this configuration, when the gain is reduced on the upstream side, which is analog processing, the reduction can be compensated for on the downstream side, so that fluctuations in image brightness can be suppressed.

  Preferably, means for controlling a beam deflection angle based on the status signal is included. Also with this configuration, it is possible to suppress the occurrence of distortion. In particular, it is effective in suppressing distortion occurring on the boundary. The indicator displayed together with the ultrasonic image may be a character display, a graph display, or the like.

  According to the present invention, it is possible to accurately detect that a harmonic component other than the harmonic component generated in the living body is generated in the received signal. Alternatively, such unnecessary harmonic components can be suppressed.

It is explanatory drawing for demonstrating the principle of embodiment which concerns on this invention. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a figure which shows the example of a display in embodiment. It is a figure which shows some scanning systems. It is a figure for demonstrating the production | generation of a status signal, and its utilization. It is a figure which shows the gain curve which changes according to depth. It is a figure for demonstrating the setting of a region of interest. It is a figure which shows the gain curve according to the region of interest. It is a figure which shows the combination of several deflection | deviation scanning. It is a figure which shows several deflection | deviation scanning with respect to the region of interest.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 conceptually shows the principle of an embodiment according to the present invention. In FIG. 1, reference numeral 10 represents a received signal. This received signal is obtained by transmitting an ultrasonic wave to the living body and receiving a reflected wave from within the living body. The received signal contains harmonic components (biologically derived harmonic components). Specifically, the harmonic component is generated at the time of reflection of the ultrasonic wave in the living tissue, or is generated at the time of reflection by the ultrasonic contrast agent placed in the living body or at the time of destruction. is there. Analog signal processing is applied to the received signal as indicated by reference numeral 12. In this case, when the amplitude of the received signal becomes excessive and exceeds the signal processing range or the input range of each circuit, the signal is distorted on each circuit, that is, a harmonic component derived from the device is generated. . Therefore, the received signal that has undergone the analog signal processing may include a device-derived harmonic component in addition to the biological-derived harmonic component. A digital conversion process is applied to such a received signal, and various digital signal processes are applied.

  A harmonic component is extracted from the digital received signal that has undergone the signal processing as described above, as indicated by reference numeral 14. As indicated by reference numeral 16, a harmonic image is formed on the basis of the extracted harmonic component and displayed. A normal ultrasonic image (B-mode tomographic image) based on the fundamental wave component may be displayed.

  In the present embodiment, when the harmonic component indicated by reference numeral 14 is extracted, the second harmonic component and the third harmonic are extracted. The third harmonic component is used as a specific harmonic component 15A, and the second harmonic component is used as a reference component 15B that is a comparison target with the specific harmonic component 15A. It is also possible to use a fundamental wave component as a reference component. When the signal waveform is distorted in the device, it has been found that the odd-order harmonic components increase instead of the even-order harmonic components. It specifies the device-derived harmonic components. Therefore, in the case of odd-order harmonic components, harmonic components of orders other than the third order can be used. However, since the power generally decreases as the order increases, the third harmonic component is usually used. A plurality of odd-order harmonic components may be used. Similarly, as a reference component, a combination of a fundamental wave component and a second harmonic component, a combination of another even-order component, and the like can be used. For example, harmonic components of a predetermined order are individually extracted using a band pass filter. Harmonic components (especially second harmonic components) are extracted by the pulse modulation method and the pulse inversion method, and such a technique can be applied.

  The specific harmonic component and the reference component are compared with each other as indicated by reference numeral 15C. Prior to that, pretreatment is applied to each component (or one component) as necessary. For example, the third harmonic component (or second harmonic component) is multiplied by a coefficient corresponding to the difference between the second harmonic peak and the third harmonic peak observed when only the biological component is generated. However, the ratio between the two can be calculated, and the presence and extent of the apparatus-derived harmonic component can be specified from the magnitude of the ratio. In any case, the comparison operation is performed so that only the harmonics generated in the apparatus can be detected with high accuracy. Although it is possible to perform control based only on the absolute amount of the third harmonic component, the biological harmonic component also includes the third harmonic component, so that the identification accuracy of the device-derived harmonic component is increased. It is desirable to compare the third harmonic component with other components.

  The displayed harmonic image may contain device-derived harmonic components in addition to living body-derived harmonic components, which may be an obstacle to diagnostic imaging or cause misidentification. is there. Therefore, in the present embodiment, it is detected that a signal having an excessive amplitude is generated in the analog signal processing circuit, and a signal indicating the fact of the possibility of occurrence of the apparatus-derived harmonic component and the degree thereof is generated. ing. Hereinafter, this is referred to as a status signal.

  The status signal is used for display processing (status display 18) and also for operation control (condition change 20). That is, a display showing such a situation is provided to the user so that the user who has observed the image can recognize the situation where the apparatus-derived harmonic component is generated. In order to prevent or reduce the generation of device-derived harmonic components, that is, the distortion of the signal waveform itself, the user adjusts the gain and changes the deflection angle of the linearly scanned beam. On the other hand, in automating such control, transmission / reception conditions and signal processing conditions are automatically changed based on the state signal. For example, when the gain is varied according to the depth (TGC technique, STC technique), the gain at each depth is adjusted so that the third harmonic component does not occur in the apparatus. Alternatively, the beam deflection angle is adjusted so that the third harmonic component is relatively reduced over the entire frame. In addition, signal distortion can be prevented or improved by changing various conditions.

  Normally, when an ultrasonic beam is set at a right angle with respect to the living tissue boundary surface, the reflection intensity at that point becomes maximum, and distortion of the signal waveform tends to occur there. In other words, if the incident angle of the ultrasonic beam with respect to the living tissue boundary surface is changed, the reflection intensity can be weakened and the signal waveform distortion can be improved. From such a viewpoint, the beam deflection angle is varied.

  FIG. 2 shows a block diagram of the ultrasonic diagnostic apparatus according to the embodiment. This ultrasonic diagnostic apparatus performs ultrasonic diagnosis of a living body and is installed in a medical institution such as a hospital. In the present embodiment, as described above, a harmonic image representing a biological tissue or an in-vivo contrast agent is displayed.

  The array transducer 22 is disposed in an ultrasonic probe (not shown). The array transducer 22 includes a plurality of vibration elements 24 arranged linearly in the present embodiment. In the present embodiment, electronic linear scanning is applied, and the ultrasonic beam formed by the array transducer 22 is electronically linearly scanned. Thereby, a two-dimensional data capturing area (beam scanning surface) is formed. Of course, in this embodiment, an ultrasonic beam may be scanned in a three-dimensional space. Also, other electronic scanning methods may be applied.

  The transmission unit 26 is a transmission beam former, and supplies a plurality of transmission signals subjected to delay processing to the plurality of vibration elements 24. As a result, a transmission beam is formed, a reflection signal (echo) is generated from each depth in the living body, and is received by the plurality of vibration elements 24 again. Thereby, a plurality of reception signals (analog reception signals) are generated.

  The reception unit 28 is a reception beam former, and performs phasing addition processing on a plurality of reception signals. Specifically, the reception unit 28 includes a plurality of reception channel processing circuits 30. Each reception channel processing circuit 30 includes a preamplifier (first stage amplifier) 30A, a variable gain amplifier (TGC amplifier) 30B, a filter (high cut filter) 30C, an A / D converter 30D, a delay unit 30E, and the like provided from upstream to downstream. It has. Here, the filter 30C is provided as necessary, and other circuits may be provided. For example, a filter that suppresses the fundamental wave component may be provided. The A / D converter 30D is a circuit that converts an analog reception signal into a digital reception signal, which may be provided in front of the filter 30C. The delay device 30E is configured by a FIFO memory. The configuration of such a reception channel circuit is general. The adder 32 is a circuit that adds a plurality of digital reception signals after delay processing, and thereby obtains beam data as digital signals. The beam data is output to the signal processing unit 34. The variable gain amplifier 30B is an amplifier whose gain can be varied according to the reception point depth. In the present embodiment, the gain curve forming a function in the depth direction is variably set according to the degree of generation of the third harmonic component in the depth direction. This will be described later.

  The signal processing unit 34 includes various signal processing circuits such as a detector, a gain adjuster, and a logarithmic converter. The beam data after the signal processing is output to the extraction unit 36. In the illustrated example, the extraction unit 36 includes a band pass filter (BPF) 36A that extracts a third harmonic component and a band pass filter (BPF) 36B that extracts a second harmonic component. That is, in the illustrated example, the third harmonic component is used as the specific harmonic component, and the second harmonic component is used as the reference component. It is also possible to use a fundamental wave component as a reference component. When extracting the harmonic component, a pulse modulation method or a pulse inversion method may be applied. In that case, a predetermined calculation is executed between the plurality of beam data acquired in time division, and thereby harmonic components are extracted.

  The image forming unit 38 includes a digital scan converter (DSC), and forms an ultrasonic image from a plurality of beam data. If the input information is a harmonic component, a harmonic image obtained by imaging it is formed. In that case, an image representing the second harmonic component may be formed, an image representing the third harmonic component may be formed, or an image representing both of these components may be formed. . A normal ultrasonic image representing the fundamental wave component may be formed. Data of the formed image is sent to the display unit 42 via the display processing unit 40, and an ultrasonic image is displayed on the display unit 42. The display processing unit 40 has a function of combining graphic images and the like, and displays a graphic image (particularly, an indicator described later) together with the ultrasonic image.

  In the present embodiment, a state signal generation unit 44 is provided. The state signal generation unit 44 is a module that generates a state signal based on a comparison between a specific harmonic component (for example, third harmonic component) and a reference component (for example, second harmonic component). The status signal is a signal indicating whether or not there is a possibility that signal waveform distortion has occurred in the apparatus due to excessive amplitude or the like, and the degree thereof. Although it is possible to directly compare the specific harmonic component and the reference component as they are, it is also possible to compare them after preprocessing such as multiplying both or one of them by a coefficient for level adjustment. . It is also possible to determine the ratio by dividing the specific harmonic component by the reference component and evaluate the state based on the ratio. Desirably, the occurrence of distortion may be recognized when the ratio or difference between the two components exceeds a predetermined value, and the degree of distortion may be recognized from the degree of exceeding the predetermined value. For example, by counting the number of times (frequency) that the ratio exceeds a predetermined value in frame units, beam units, depth division units or region of interest, and certifying the occurrence of distortion that cannot be overlooked when the count value exceeds a certain value Alternatively, the count value itself can be used as a status signal. If the count value is used, it is possible to catch the excessive amplitude that is spread to some extent on the image (displayed with a certain area) ignoring the instantaneous excessive amplitude. It is desirable to individually set a predetermined value to be compared with the ratio and a constant value (threshold value) to be compared with the count value for each depth division.

  The state signal generated as described above is output to the display processing unit 40 as indicated by reference numeral 48, and the display processing unit 40 generates a graphic image based on the state signal and synthesizes it with the ultrasonic image. Generate a composite image. The graphic image includes an indicator shown later in FIG. Further, the state signal generated as described above is sent to the control unit 50 as indicated by reference numeral 46, and is used for operation control in control (particularly, variable gain for relaxing and eliminating excessive amplitude).

  The control unit 50 is a control unit that performs operation control of each configuration illustrated in FIG. 2, and is configured by a CPU and an operation program. An input unit 52 configured by an operation panel or the like is connected to the control unit 50. The user can adjust the beam deflection angle by adjusting the beam deflection angle while observing the indicator, that is, the over-amplitude on the indicator is minimized or disappears by using the input unit 52. It is. Further, other parameters may be operated. By changing the contact position and the contact angle of the ultrasonic probe, it is possible to eliminate or reduce the state in which the excessive amplitude is generated.

  The control unit 50 has a function of controlling the gain of the reception signal for each reception channel based on the status signal. Specifically, a gain value corresponding to the depth and corresponding to the state signal is given to the TGC amplifier 30B. Although a common gain value is set for the plurality of amplifiers 30B, it is also possible to change the gain value according to the position in the opening or the like. By such variable gain control, it is possible to eliminate or reduce the occurrence of excessive amplitude in the analog signal processing system, in particular, the generation of unnecessary harmonic components that cause misperception in harmonic image observation. After performing amplitude suppression for each reception channel, for example, gain compensation may be performed at the stage of processing a digital reception signal (beam data) after phasing addition. A control signal for gain compensation from the control unit 50 is input to the signal processing unit 34. According to such a configuration, since the amount narrowed down at the input stage can be compensated at the subsequent stage, the problem that the luminance of the entire image fluctuates unnecessarily can be solved or reduced.

  The operation of the display processing unit will be described with reference to FIG. In the display screen 100, a harmonic image 102 as an ultrasonic image is displayed. Reference numeral 104 represents an ultrasonic beam. Since electronic linear scanning is applied in the present embodiment, the ultrasonic beam 104 is scanned in parallel translation in the horizontal direction in FIG. In the example shown in FIG. 3, the harmonic image 102 is, for example, an image representing one of the blood vessels (such as the carotid artery) 105, in which the front wall boundary 106 </ b> A and the rear wall boundary 106 </ b> B for the blood vessel 105 appear. ing. Incidentally, the front wall is displayed with higher brightness here. There, an excessive amplitude is likely to occur.

  The display processing unit displays an indicator based on the status signal along with the ultrasonic image 102 on the display screen 100. In the present embodiment, the indicator is composed of a graph 110 and a character display 108, where the character display 108 is composed of characters representing the generation of device-derived harmonic components. Such a character display 108 appears when the above-mentioned count value exceeds a certain value. In such a state, a level exceeding a certain value, that is, the degree, is displayed as the graph 110. It corresponds to a bar graph, and an excessive state is expressed as the number of light emitting cells.

  Therefore, the user can refer to the indicator as shown in FIG. 3 to observe the harmonic image, and the fact that the harmonic component derived from the device other than the original tissue-derived harmonic component is mixed, and It is possible to intuitively understand the degree of mixing and use it for image diagnosis. In this way, if the display based on the status signal is performed, it is possible to quantitatively recognize whether the harmonic is an original harmonic or a harmonic due to other factors, and the convenience of the user can be achieved. . The excessive amplitude can be suppressed by the user, but in the configuration shown in FIG. 2, the excessive amplitude is automatically suppressed by the action of the control unit. You may make it display a state value as an indicator for every depth division.

  In the present embodiment, different conditions can be set for each depth section in detecting the apparatus-derived harmonic components. For example, it is possible to individually set a threshold value to be compared with the count value for each depth section. it can. Alternatively, the gain or gain change can be made different for each depth section.

  A plurality of sections arranged in the depth direction will be described with reference to FIG. (A) shows a scanning surface (frame) in electronic linear scanning. The scanning surface is formed by linearly scanning the ultrasonic beam 104 in the electronic scanning direction, and a plurality of rectangular subareas 200 to 206 are set as a plurality of sections in the depth direction. (B) shows a scanning plane in convex scanning. The scanning plane is formed by linearly scanning the ultrasonic beam 104 in the arc direction. The scanning surface has a fan-like shape having an arcuate apex, and a plurality of curved sub-areas 208-212 are set in the depth direction. Similarly, (C) shows a scanning plane in electronic sector scanning. The scanning surface is formed by sector scanning of the ultrasonic beam 104. It has a fan-like shape, and a plurality of curved sub-areas 214 and 216 are set in the depth direction. In any scanning method, a different threshold can be set for each section, and a different gain can be set for each section. That is, the gain curve along the depth direction can be customized based on the state signal. The gain curve will be described later with reference to FIG.

  FIG. 5 shows a gain control based on the status signal as a block diagram. The specific harmonic component (3f0) and the reference component (f0 or 2f0) are input to the state signal generation unit 44. The comparator 54 compares them and generates a comparison result signal. For example, the difference or ratio between the two components is output as a comparison result signal. The signal generator 56 counts the comparison result signal, and when the count value exceeds a certain value (threshold value), changes the value of the state signal to indicate that an excessive amplitude has occurred. Further, the magnitude of the value of the state signal is determined according to the degree to which the count value exceeds a certain value. In this way, the state signal generation unit 44 generates the state signal and outputs it to the display processing unit and the control unit 50 (see reference numerals 46 and 48). The controller 50 varies the gain of the TGC amplifier 34 based on the state signal. Conventionally, the gain of the amplifier 34 is varied according to the depth. However, in this embodiment, the gain is varied according to the state of occurrence of the excessive amplitude along with the variation, that is, the signal amplitude is analog in the analog reception signal processing. Control is performed so as not to exceed the signal processing range and input range of the circuit.

  FIG. 6 shows a gain curve. The horizontal axis is the depth axis, and the vertical axis indicates the gain of the TGC amplifier. According to the present embodiment, a suppression curve 228 indicating the possibility of excessive amplitude is generated by the state signal with respect to the illustrated general gain curve 226, and by subtracting the suppression curve 228 from the gain curve 226, A gain curve 230 to be used is generated. Of course, each curve shown in FIG. 6 is an example.

  It is also possible to apply variable control of gain based on the third harmonic component only within the region of interest. When a rectangular region of interest 234 is set on the scanning plane 230 so as to surround the tissue cross section 232 as shown in FIG. 7, the gain as shown in FIG. 8 on the beam line passing through such a region of interest. The gain is adjusted according to the curve 246. In the illustrated example, the section 238 corresponds to the region of interest, and the sections 236 and 240 correspond to the front and back of the region of interest. A gain curve 246 to be actually used is generated by applying a partial suppression curve 244 indicated by the state signal to the original gain curve 242. According to this configuration, special gain control can be applied only within the region of interest.

  In order to prevent the occurrence of excessive amplitude, it is also possible to vary the beam deflection angle in order to prevent the occurrence of waveform distortion due to a strong echo generated at the time of reflection at the tissue boundary. In this case, the beam deflection angle may be changed on a trial basis while referring to the status signal in the control unit, and linear scanning may be performed at the beam deflection angle at which the status signal is the best. In that case, a plurality of frames having different beam deflection angles may be generated in a time-sharing manner and synthesized to form one ultrasonic image. In FIG. 9, reference numeral 112 denotes a frame formed by normal linear scanning without tilting the ultrasonic beam, and reference numerals 114 and 116 denote frames when the beam deflection angles are set to the plus side and the minus side, respectively. ing. They may be combined to form an ultrasonic image. As shown in FIG. 10, the scanning conditions may be determined so that the region of interest 118 is included in setting each frame, and image composition and image display may be performed only for the region of interest 118.

22 array transducers, 28 receiving unit, 30 receiving channel processing circuit, 32 adder, 34 signal processing unit, 36 harmonic extraction unit, 40 display processing unit, 44 state signal generating unit.

Claims (8)

An ultrasonic image forming unit that forms an ultrasonic image based on reception data obtained by transmission and reception of ultrasonic waves;
First extraction means for extracting a specific harmonic component contained in the received data;
Second extraction means for extracting a reference component included in the received data;
Comparing means for generating a state signal indicating whether or not there is a possibility that a device-derived harmonic component is included in the received data by comparing the specific harmonic component and the reference component;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The ultrasonic image is a harmonic image that reflects a biological harmonic component contained in the received data,
The specific harmonic component is an odd-order harmonic component,
The ultrasonic diagnostic apparatus, wherein the reference component is at least one of a fundamental wave component and an even-order harmonic component. The apparatus of claim 2.
The ultrasonic diagnostic apparatus, wherein the specific harmonic component is a third harmonic component. The apparatus of claim 2.
An ultrasonic diagnostic apparatus comprising: display processing means for displaying an indicator visually indicating whether or not the apparatus harmonic component may be included based on the state signal. The apparatus of claim 2.
An ultrasonic diagnostic apparatus comprising gain control means for controlling a gain of an analog reception signal that is a source of the reception data based on the state signal. The apparatus of claim 5.
The ultrasonic diagnostic apparatus, wherein the gain control means further controls the gain of the analog reception signal in accordance with the depth of the reception point. The apparatus of claim 5.
Ultrasound diagnosis, comprising: compensation control means for performing gain compensation for compensating for the suppression of the gain of the analog reception signal with respect to the digital reception signal as the reception data obtained by conversion of the analog reception signal apparatus. The apparatus of claim 2.
An ultrasonic diagnostic apparatus comprising: means for controlling a beam deflection angle based on the state signal.

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