JP6089741B2 - Ultrasonic measuring device, ultrasonic imaging device, and ultrasonic measuring method - Google Patents

Description

  The present invention relates to an ultrasonic measurement device, an ultrasonic imaging device, an ultrasonic measurement method, and the like.

  As an apparatus used to inspect the inside of a human body that is a subject, an ultrasonic measurement apparatus that emits ultrasonic waves toward an object and receives reflected waves from interfaces with different acoustic impedances inside the object is attracting attention. ing. Furthermore, the ultrasonic measurement apparatus is also applied to image diagnosis of the surface layer of a subject such as measurement of visceral fat and blood flow.

  When performing image diagnosis using such an ultrasonic measurement apparatus, it is necessary to increase the resolution of image processing of ultrasonic echoes, and for example, harmonic imaging (harmonic imaging method) is used.

  Here, in harmonic imaging, it is necessary to extract a harmonic component of an ultrasonic echo. As a harmonic component extraction method for this purpose, there are a filter method and a phase inversion method described in Patent Document 1 or the like.

JP 2004-113818 A

  When the above phase inversion method is used for an actual living body in which the movement of an organ represented by the heart exists, the fundamental wave in the received ultrasonic wave remains unerased due to the influence of the movement of the organ. May cause motion artifacts on the image.

  According to some aspects of the present invention, an ultrasonic measurement device, an ultrasonic imaging device, and an ultrasonic imaging device that can generate an image with high resolution and little artifact (false image noise) even when the object moves. An ultrasonic measurement method and the like can be provided.

  One aspect of the present invention includes: a transmission processing unit that performs processing of transmitting ultrasonic waves to an object; a reception processing unit that performs reception processing of ultrasonic echoes for the transmitted ultrasonic waves; and A processing unit that performs processing on the received signal, wherein the transmission processing unit is a first phase of the first transmission signal and a second phase that is 180 degrees different in phase from the first transmission signal. The second transmission signal is output, and the reception processing unit outputs the first reception signal by the reception process of the first ultrasonic echo with respect to the first transmission signal, and the second transmission signal is output. A second reception signal is output by the reception process of the second ultrasonic echo with respect to the signal, and the processing unit is configured to output the second object based on the first reception signal and the second reception signal. Perform a process for detecting a change in the positional relationship with the ultrasonic probe, and It is determined whether to use a filter method or a phase inversion method as a method for extracting the harmonic component of the ultrasonic echo based on the result of the extraction process, and when it is determined that the filter method is used, the first reception When the signal or the second received signal is filtered to extract the harmonic component of the ultrasonic echo and the phase inversion method is determined to be used, the first received signal and the second received signal This is related to an ultrasonic measurement apparatus that performs addition processing or subtraction processing on the received signal to extract the harmonic component of the ultrasonic echo.

  In one aspect of the present invention, ultrasonic waves that are 180 degrees out of phase with each other are transmitted to the object once, and based on two ultrasonic echoes for the transmitted ultrasonic waves, between the object and the ultrasonic probe. The process of detecting a change in the positional relationship is performed. Normally, the harmonic component is extracted using the phase inversion method. However, when it is detected that the position of the object is changed, the harmonic component is extracted using the filter method.

  Thereby, even when the object moves, it is possible to generate a high-quality image with high resolution and little artifact (false image noise).

  In one aspect of the present invention, the processing unit performs a process of detecting a phase or amplitude shift amount between the first reception signal and the second reception signal as the detection process, Based on the result of the detection process, it may be determined whether to use the filter method or the phase inversion method as the harmonic component extraction method of the ultrasonic echo.

  This makes it possible to select a harmonic component extraction method according to the phase or amplitude shift amount.

  In the aspect of the invention, the transmission processing unit outputs a third transmission signal when the processing unit determines that the filter method is used as the harmonic component extraction method, and the reception processing The unit outputs a third reception signal by the reception process of the third ultrasonic echo with respect to the third transmission signal, and the processing unit performs the filtering process on the third reception signal. The harmonic component of the ultrasonic echo may be extracted.

  This makes it possible to improve the frame rate, etc., compared to the case where ultrasonic waves are always transmitted and received twice.

  In one aspect of the present invention, the processing unit determines the harmonic component extraction method to be used based on the first reception signal and the second reception signal in the determination period for determining the harmonic component extraction method to be used. And the phase inversion is performed using the filter method as the harmonic component extraction method of the ultrasonic echo based on the detection processing result. And when it is determined that the filter method is used as the harmonic component extraction method, in the measurement period of the harmonic component of the ultrasonic echo, with respect to the third received signal The filtering process may be performed to extract the harmonic component of the ultrasonic echo.

  Thus, for example, when the positional relationship between the ultrasonic probe and the object keeps changing for a predetermined period, the filter method is always used instead of the phase inversion method as the harmonic component extraction method. It becomes possible.

  In the aspect of the invention, the processing unit may detect a phase or amplitude shift amount between the first reception signal and the second reception signal by a cross-correlation method.

  This makes it possible to accurately detect the amount of phase or amplitude deviation.

  According to another aspect of the present invention, the present invention relates to an ultrasonic imaging apparatus including an ultrasonic measurement apparatus and a display unit that displays display image data generated based on the harmonic component of the ultrasonic echo. .

  In another aspect of the present invention, as a process of transmitting an ultrasonic wave to an object, a first transmission signal having a first phase is different from a phase of the first transmission signal by 180 degrees. The first transmission signal is output by the reception process of the first ultrasonic echo with respect to the first transmission signal, and the second transmission signal is output with respect to the second transmission signal. By the reception process of the second ultrasonic echo, a second reception signal is output, and between the object and the ultrasonic probe based on the first reception signal and the second reception signal. When a detection process of a change in positional relationship is performed, based on the result of the detection process, it is determined whether to use a filter method or a phase inversion method as the harmonic component extraction method of the ultrasonic echo, and the filter method is used. If it is determined, When the received signal or the second received signal is filtered, the harmonic component of the ultrasonic echo is extracted, and it is determined that the phase inversion method is used, the first received signal and the second received signal The present invention relates to an ultrasonic measurement method for extracting the harmonic component of the ultrasonic echo by performing addition processing or subtraction processing with a second received signal.

Explanatory drawing of the filter method. Explanatory drawing of a phase inversion method. Explanatory drawing at the time of performing a harmonic extraction using a phase inversion method, when a target object moves. The system configuration example of this embodiment. 2 is a detailed system configuration example of the ultrasonic imaging apparatus according to the present embodiment. FIGS. 6A to 6C are examples of a specific device configuration of the ultrasonic measurement apparatus. Explanatory drawing of the harmonic extraction method of this embodiment. The flowchart explaining the flow of a process of this embodiment. The flowchart explaining the flow of the harmonic extraction process of this embodiment. FIG. 10A to FIG. 10C are configuration examples of ultrasonic transducer elements. The structural example of an ultrasonic transducer device. FIGS. 12A and 12B are configuration examples of ultrasonic transducer element groups provided corresponding to the respective channels.

  Hereinafter, this embodiment will be described. First, an outline of the present embodiment will be described, and then a system configuration example of the present embodiment will be described. Then, the method of the present embodiment will be described in detail with specific examples, and then the flow of processing of the present embodiment will be described using a flowchart. Then, configuration examples of the ultrasonic transducer element and the ultrasonic transducer device will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Outline An ultrasonic measurement device that emits ultrasonic waves toward an object and receives reflected waves from interfaces with different acoustic impedances inside the object is known as an apparatus used to examine the inside of the human body that is the subject. It has been. Furthermore, as an application example of an ultrasonic measurement device, there is a pocket-type ultrasonic viewer that performs image diagnosis of the surface layer of a subject, such as measurement of visceral fat and blood flow, and is expected to expand into the healthcare field. ing.

  As described above, when image diagnosis is performed using an ultrasonic measurement apparatus, it is necessary to increase the resolution of image processing of ultrasonic echoes. As an image processing technique for realizing high resolution, there is harmonic imaging (harmonic imaging method).

  Harmonic imaging refers to a technique for visualizing a harmonic component described later. Here, the speed of the ultrasonic wave (coherent wave) propagating in the medium has a property that the part where the sound pressure is high is high and the part where the sound pressure is low is low. Therefore, even a simple sine wave is gradually distorted in the propagation process and the waveform changes, and a harmonic component that is an integral multiple of the fundamental frequency that is not included in the fundamental wave (this is referred to as a harmonic component or nonlinear component). Say) will be included. Such a nonlinear effect increases in proportion to the square of the sound pressure of the ultrasonic wave and accumulates in proportion to the propagation distance.

  In harmonic imaging, tissue harmonic imaging that visualizes harmonic components generated from the tissue itself when ultrasound propagates through the tissue, and harmonic components that are generated when the microbubbles of the ultrasonic shaping agent resonate and collapse. There are two types of contrast harmonic imaging. In this embodiment, tissue harmonic imaging is used.

  In addition, harmonic imaging has two advantages. First, since the amplitude of the harmonic component is proportional to the square of the amplitude of the transmitted ultrasound, the amplitude of the harmonic component is strong at the center of the transmitted beam where the sound pressure is high, but suddenly increases from the center of the beam to the end. become weak. Thereby, in the harmonic imaging, the range in which the nonlinear effect occurs is limited to the center of the beam, and as a result, the azimuth resolution is improved as compared with other methods. This is the first advantage.

  In addition, as main noise on the ultrasonic image, there are noise due to multiple reflections and noise due to side lobes. Here, the reflected ultrasonic echo has a low sound pressure, and the harmonic component itself does not occur. Therefore, noise due to multiple reflection is reduced. Furthermore, the side lobe has a low sound pressure, and the harmonic component itself does not occur even in the side lobe. Therefore, noise due to side lobes is also reduced. Thus, in harmonic imaging, noise due to multiple reflections and noise due to side lobes can be reduced. This is the second advantage.

  Here, in harmonic imaging, it is necessary to extract a harmonic component of an ultrasonic echo. As a harmonic component extraction method therefor, there are a filter method and a phase inversion method.

First, the filter method is a method of separating a fundamental wave component and a second harmonic component by a frequency filter (high pass filter), extracting only the second harmonic component, and imaging. For example, as a diagram for explaining the filter method, a received signal whose center frequency in the fundamental band is f ₀ and whose center frequency in the second harmonic band is 2f ₀ , the vertical axis is the signal intensity, and the horizontal axis is the frequency. This is shown in the graph of FIG. Actually, as shown in FIG. 1, since the received fundamental wave component and the second harmonic component have a certain bandwidth, the fundamental wave component and the second harmonic component overlap and are separated. It becomes impossible to cause image degradation. In order to reduce this overlap, it is necessary to increase the pulse width. However, as the pulse width increases, the distance resolution decreases.

  On the other hand, the phase inversion method is a method developed to improve the drawbacks of the filter method. In this method, ultrasonic waves are transmitted twice in the same direction. As shown in FIG. 2, the second transmission wave has a feature that the phase is 180 degrees different from that of the first transmission wave. The received wave that is reflected back from the living body or the contrast agent includes a harmonic component due to its nonlinear propagation characteristics, and thus has a distorted waveform. Between the two received waves, there is a relationship that the fundamental wave component is inverted because the transmitted wave is inverted at the first time and the second time, but the harmonic component is not inverted. That is, in the two received waves with respect to the two transmitted waves, the fundamental wave components are phase-inverted with each other, but the second harmonic components are in phase. As a result, when the two received waves are added, the fundamental wave component is removed and the second harmonic component remains with its amplitude doubled, so that only the second harmonic component can be imaged. . In addition, since the transmission / reception method can perform wide-band transmission / reception, the reduction in distance resolution, which is a drawback of the filter method, can also be improved.

  As described above, it seems that the phase inversion method is superior to the filter method as a harmonic component extraction method. However, when the above phase inversion method is used for an actual living body in which the movement of an organ represented by the heart exists, due to the influence of the movement of the organ, each portion between the first and second received waves is affected. Displacement can occur, resulting in the fundamental wave remaining and causing motion artifacts on the image. A specific example is shown in FIG. When there is movement of the object, the reception process for the second transmission wave is to receive a reception wave that includes a Δt time shift corresponding to the displacement of the position of the object as compared to the first time. Become. As a result, even if the first received wave and the second received wave are added, the fundamental wave remains without canceling, while the second harmonic is not amplified in amplitude and the original waveform is corrupted. End up. Thus, it is better to use the filter method than the phase inversion method for a moving object.

  Therefore, in the ultrasonic measurement apparatus, ultrasonic image apparatus, and ultrasonic measurement method of the present embodiment, the phase inversion method is normally used as the harmonic component extraction method, but if there is a change in the position of the object, the harmonic A filter method is used as a component extraction method. Thereby, even when the object moves, a high-quality image with high resolution and little artifact (false image noise) can be generated.

2. System Configuration Example Next, FIG. 4 shows a configuration example of the ultrasonic measurement apparatus of the present embodiment. The ultrasonic measurement apparatus 100 includes a transmission processing unit 110, a reception processing unit 120, and a processing unit 130.

  Furthermore, a specific configuration example of the ultrasonic imaging apparatus of the present embodiment is shown in FIG. The ultrasonic imaging apparatus includes an ultrasonic measurement device 100, an ultrasonic probe 200, and a display unit 300. 5 includes a transmission processing unit 110, a reception processing unit 120, a processing unit 130, a transmission / reception changeover switch 140, a DSC (Digital Scan Converter) 150, and a control circuit 160. Including.

  Note that the ultrasonic measurement apparatus 100 and the ultrasonic imaging apparatus including the ultrasonic measurement apparatus 100 are not limited to the configurations shown in FIGS. 4 and 5, and some of these components are omitted or other components are added. Various modifications such as these are possible. Further, some or all of the functions of the ultrasonic measurement apparatus 100 and the ultrasonic image apparatus including the ultrasonic measurement apparatus 100 according to the present embodiment may be realized by a server connected by communication.

  Next, processing performed in each unit will be described.

  The ultrasonic probe 200 includes an ultrasonic transducer device.

  The ultrasonic transducer device transmits an ultrasonic beam to the target while scanning the target along the scanning plane, and receives an ultrasonic echo from the ultrasonic beam. Taking the type using a piezoelectric element as an example, the ultrasonic transducer device has a plurality of ultrasonic transducer elements (ultrasonic element array) and a substrate on which a plurality of openings are arranged in an array. And as an ultrasonic transducer element, the thing using the monomorph (unimorph) structure which bonded the thin piezoelectric element and the metal plate (vibration film) is used. An ultrasonic transducer element (vibration element) converts electrical vibration into mechanical vibration. In this case, a bonded metal plate (vibration film) when the piezoelectric element expands and contracts in the plane. ) Warping occurs because the dimensions of) remain the same.

  In the ultrasonic transducer device, a single channel is composed of several ultrasonic transducer elements arranged in the vicinity, and the ultrasonic beam is sequentially moved while driving a plurality of channels at a time. There may be.

  Note that, as the ultrasonic transducer device, a type of transducer using a piezoelectric element (thin film piezoelectric element) can be adopted, but the present embodiment is not limited to this. For example, a transducer of a type using a capacitive element such as c-MUT (Capacitive Micro-machined Ultrasonic Transducers) may be adopted, or a bulk type transducer may be adopted. A more detailed description of the ultrasonic transducer element and the ultrasonic transducer device will be described later.

  Next, the transmission process part 110 performs the process which transmits an ultrasonic wave with respect to a target object. For example, the transmission processing unit 110 illustrated in FIG. 5 includes a transmission pulse generator 111 and a transmission delay circuit 113.

  Specifically, the transmission pulse generator 111 applies a transmission pulse voltage and drives the ultrasonic probe 200.

  The transmission delay circuit 113 focuses the transmission beam. Therefore, the transmission delay circuit 113 gives a time difference between the channels with respect to the application timing of the transmission pulse voltage, and focuses the ultrasonic waves generated from the plurality of vibration elements. Thus, the focal length can be arbitrarily changed by changing the delay time.

  The transmission / reception changeover switch 140 performs processing for switching between transmission and reception of ultrasonic waves. The transmission / reception selector switch 140 protects the amplitude pulse at the time of transmission from being input to the reception circuit, and passes the signal at the time of reception through the reception circuit.

  On the other hand, the reception processing unit 120 performs an ultrasonic echo reception process on the transmitted ultrasonic waves. For example, the reception processing unit 120 illustrated in FIG. 5 includes a reception delay circuit 121, a filter circuit 123, and a memory 125.

  The reception delay circuit 121 focuses the received beam. Since the reflected wave from a certain reflector spreads on the spherical surface, the reception delay circuit 121 gives a delay time so that the time to reach each transducer is the same, and adds the reflected waves in consideration of the delay time.

  Then, the filter circuit 123 performs filter processing on the received signal with a band pass filter to remove noise.

  The memory 125 stores the received signal output from the filter circuit 123, and its function can be realized by a memory such as a RAM, an HDD, or the like.

  The processing unit 130 performs processing on the reception signal from the reception processing unit 120. For example, the processing unit 130 illustrated in FIG. 5 includes a harmonic processing unit 131, a detection processing unit 133, a logarithmic conversion processing unit 135, a gain / dynamic range adjustment unit 137, and an STC (Sensitivity Time Control) 139.

  Specifically, the harmonic processing unit 131 performs a harmonic component extraction process, which will be described in detail later.

  The detection processing unit 133 extracts a non-modulated signal by applying a low-pass filter after the absolute value (rectification) processing.

  Further, the logarithmic conversion processing unit 135 performs log compression and converts the expression format so that the maximum and minimum portions of the received signal strength can be easily confirmed at the same time.

  The gain / dynamic range adjustment unit 137 adjusts the signal intensity and the region of interest. Specifically, in the gain adjustment process, a DC component is added to the input signal after Log compression. In the dynamic range adjustment process, the input signal after Log compression is multiplied by an arbitrary number.

  Further, the STC 139 corrects the amplification degree (brightness) according to the depth, and acquires an image having uniform brightness over the entire screen.

  The function of the processing unit 130 can be realized by hardware such as various processors (CPU or the like), ASIC (gate array or the like), a program, or the like.

  Then, the DSC 150 performs scan conversion processing on the B-mode image data. For example, the DSC 150 converts a line signal into an image signal by an interpolation process such as bilinear.

  The control circuit 160 controls the transmission pulse generator 111, the transmission delay circuit 113, the reception delay circuit 121, the transmission / reception selector switch 140, and the harmonic processing unit 131.

  The display unit 300 displays display image data generated based on the harmonic component of the ultrasonic echo. The display unit 300 can be realized by, for example, a liquid crystal display, an organic EL display, electronic paper, or the like.

  Here, an example of a specific device configuration of the ultrasonic measurement apparatus (electronic device in a broad sense) of the present embodiment is shown in FIGS. 6 (A) to 6 (C). 6A shows an example of a handy type ultrasonic measuring apparatus 100, and FIG. 6B shows an example of a stationary type ultrasonic measuring apparatus 100. FIG. 6C shows an example of an integrated ultrasonic measurement apparatus 100 in which the ultrasonic probe 200 is built in the main body.

  6A and 6B includes an ultrasonic probe 200 and an ultrasonic measurement device main body 101 (electronic device main body in a broad sense), and the ultrasonic probe 200 and the ultrasonic measurement device. The main body 101 is connected by a cable 210. A probe head 220 is provided at the distal end portion of the ultrasonic probe 200, and a display unit 300 for displaying an image is provided in the ultrasonic measurement apparatus main body 101. In FIG. 6C, the ultrasonic probe 220 is built in the ultrasonic measurement apparatus 100 having the display unit 300. In the case of FIG. 6C, the ultrasonic measurement apparatus 100 can be realized by a general-purpose portable information terminal such as a smartphone.

3. Next, the method of this embodiment will be described.

  The ultrasonic measurement apparatus 100 according to the present embodiment described above includes a transmission processing unit 110 that performs processing of transmitting ultrasonic waves to an object, and a reception processing unit 120 that performs reception processing of ultrasonic echoes for the transmitted ultrasonic waves. And a processing unit 130 that performs processing on a reception signal from the reception processing unit 120. The transmission processing unit 110 outputs a first transmission signal having a first phase and a second transmission signal having a second phase that is 180 degrees different in phase from the first transmission signal. Then, the reception processing unit 120 outputs the first reception signal by the reception process of the first ultrasonic echo with respect to the first transmission signal, and performs the reception process of the second ultrasonic echo with respect to the second transmission signal. The second received signal is output. Further, the processing unit 130 performs a detection process of a change in the positional relationship between the object and the ultrasonic probe based on the first reception signal and the second reception signal, and based on the result of the detection process. If it is determined whether the filtering method or the phase inversion method is used as the harmonic echo harmonic component extraction method, and if it is determined that the filtering method is used, the first received signal or the second received signal is When the filtering process is performed, the harmonic component of the ultrasonic echo is extracted, and it is determined that the phase inversion method is used, an addition process or a subtraction process between the first reception signal and the second reception signal is performed, Extract the harmonic component of the acoustic echo.

  This will be specifically described with reference to FIG. First, in this embodiment, the transmission process part 110 performs the process which outputs a 1st transmission signal and a 2nd transmission signal as a process which transmits an ultrasonic wave with respect to a target object.

  Here, the first transmission signal is a transmission signal having a first phase, and the second transmission signal is a transmission signal having a second phase that is 180 degrees different in phase from the first transmission signal. FIG. 7 shows a state in which the transmission wave TXP1 is emitted based on the first transmission signal and the transmission wave TXP2 is emitted based on the second transmission signal.

  Then, the reception processing unit 120 outputs the first reception signal by the reception process of the first ultrasonic echo, and outputs the second reception signal by the reception process of the second ultrasonic echo.

  Here, the first ultrasonic echo is an ultrasonic echo for the first transmission signal, and the ultrasonic beam emitted from the ultrasonic probe 200 based on the first transmission signal is reflected on the object, It was returned as an ultrasonic echo. The same applies to the second ultrasonic echo. In FIG. 7, the first ultrasonic echo including the fundamental wave BS1 and the second harmonic (harmonic component) HM1 is received for the transmission wave TXP1. For the transmission wave TXP2 in FIG. 7, a second ultrasonic echo including either the fundamental wave BS2 and the second harmonic HM2 or the fundamental wave BS3 and the second harmonic HM3 is received.

  The reception processing refers to, for example, focusing processing of a received beam (ultrasonic echo) by the reception delay circuit 121, filter processing by the filter circuit 123, and the like. The received signal is a signal obtained after such reception processing is performed.

  Further, the processing unit 130 performs a detection process of a change in the positional relationship between the object and the ultrasonic probe based on the first reception signal and the second reception signal. For example, when the object pulsates like a heart, the positional relationship between the object and the ultrasonic probe changes due to the movement of the object. Even if the object does not move, the positional relationship between the object and the ultrasonic probe can change even when the user moves the position of the ultrasonic probe. Although these are detected here, a specific example of the detection process will be described later.

  Then, the processing unit 130 determines whether to use the filter method or the phase inversion method as the harmonic component extraction method of the ultrasonic echo based on the detection processing result. A specific example of this determination process will be described later.

  Further, when it is determined that the filter method is used as the harmonic component extraction method, the processing unit 130 performs a filtering process on the first reception signal or the second reception signal and extracts the harmonic component of the ultrasonic echo. To do. In the example of FIG. 7, when the filter method is selected as the harmonic component extraction method, the second harmonic DP2 is extracted. Note that the magnitude of the amplitude of the second harmonic DP2 is not different from the magnitude of the amplitude of the original second harmonics HM1 and HM3.

  On the other hand, when it is determined that the phase inversion method is used as the harmonic component extraction method, the processing unit 130 performs an addition process or a subtraction process between the first reception signal and the second reception signal, thereby performing an ultrasonic echo. Extract the harmonic components of. In the example of FIG. 7, when the phase inversion method is selected as the harmonic component extraction method, the second received signal is added to the first received signal in order to extract the second harmonic as the harmonic component. As in FIG. 2, the fundamental wave cancels and disappears, and the second harmonic DP1 is extracted. Note that the magnitude of the amplitude of the second harmonic DP1 is twice the magnitude of the amplitude of the original second harmonic HM1 or HM2.

  When extracting harmonic components of the third order or higher, a subtraction process is performed between the first received signal and the second received signal. However, since the fundamental wave is not canceled when the subtraction process is performed, it is necessary to perform a filtering process on the signal after the subtraction process to separate the fundamental wave and the third and higher harmonics. At this time, the third and higher order odd harmonics are extracted.

  By performing the above processing, even when the object moves, for example, like an organ, it is possible to cancel the fundamental wave in the received ultrasonic wave and extract only the harmonics. Therefore, even when the object moves, it is possible to generate a high-quality image with high resolution and little artifact (false image noise).

  Further, when the positional relationship between the object and the ultrasonic probe changes, a shift occurs in the phase or amplitude between the first reception signal and the second reception signal.

  Therefore, the processing unit 130 performs a process of detecting a phase or amplitude shift amount between the first received signal and the second received signal as the above detection process, and based on the result of the detection process, It may be determined whether the filter method or the phase inversion method is used as the harmonic component extraction method of the sound wave echo.

  For example, when the phase or amplitude deviation amount is larger than a given threshold value, it is determined that the filter method is used as the harmonic component extraction method, and when the phase or amplitude deviation amount is equal to or less than the given threshold value. It may be determined that the phase inversion method is used.

  In that case, in the example of FIG. 7, when a given threshold value is 0, the second received signal corresponds to the second ultrasonic echo including the fundamental wave BS2 and the second harmonic HM2. Determines that the phase inversion method is used because the amount of phase or amplitude deviation is zero.

  On the other hand, when the second received signal in the example of FIG. 7 corresponds to the second ultrasonic echo including the fundamental wave BS3 and the second harmonic HM3, the phase or amplitude deviation amount is d. Since (d> 0), it is determined that the phase inversion method is used.

  This makes it possible to select a harmonic component extraction method according to the phase or amplitude shift amount. As described above with reference to FIG. 3, the phase inversion method cannot cancel out the fundamental wave and cannot extract the harmonic component well when there is a shift in phase or amplitude. However, according to this, the phase inversion method can be used only when the phase inversion method is effective, and the filter method can be used in other cases.

  For example, if the target is a heart and is pulsating, and it turns out that the positional relationship between the ultrasonic probe and the target changes, the phase inversion method is not used as the harmonic component extraction method thereafter. In addition, the filter method may always be used.

  Therefore, the transmission processing unit 110 may output the third transmission signal when the processing unit 130 determines that the filter method is used as the harmonic component extraction method. And the reception process part 120 may output a 3rd received signal by the receiving process of the 3rd ultrasonic echo with respect to a 3rd transmitted signal. Further, the processing unit 130 may perform a filtering process on the third received signal to extract a harmonic component of the ultrasonic echo.

  Here, the third transmission signal may be the same transmission signal as the first transmission signal or the second transmission signal, or may be a different transmission signal. In the above-described example, the first transmission signal and the second transmission signal are always output, but in this example, the ultrasonic wave after it is determined that the positional relationship between the ultrasonic probe and the object changes. In the transmission / reception processing, only the third transmission signal is output.

  This makes it possible to reduce the number of times of ultrasonic transmission / reception processing to one in one measurement process, and improve the frame rate compared to the case where ultrasonic waves are always transmitted and received twice. Is possible.

  In addition, the positional relationship between the object and the ultrasonic probe has changed due to factors such as the user's hand shake, but if the position of the object itself has not changed, the positional relationship has only temporarily changed. I can say that. Therefore, in such a case, it is better to extract the harmonic component again using the phase inversion method after camera shake, and say that the positional relationship has changed once, and then the harmonic component using only the filter method. It is not desirable to extract.

  Therefore, a determination period for determining whether or not the positional relationship between the ultrasonic probe and the object changes may be provided.

  That is, the processing unit 130 determines the positional relationship between the object and the ultrasonic probe based on the first reception signal and the second reception signal in the determination period for determining the harmonic component extraction method to be used. Performs change detection processing, determines whether to use the filter method or the phase inversion method as the harmonic component extraction method of the ultrasonic echo based on the detection processing result, and determines that the filter method is used as the harmonic component extraction method In this case, in the measurement period of the harmonic component of the ultrasonic echo, the third received signal may be filtered to extract the harmonic component of the ultrasonic echo.

  Thus, for example, when the positional relationship between the ultrasonic probe and the object keeps changing for a predetermined period, the filter method is always used instead of the phase inversion method as the harmonic component extraction method. It becomes possible.

  In addition, the processing unit 130 may detect a phase or amplitude shift amount between the first reception signal or the second reception signal by a cross correlation method.

  This makes it possible to accurately detect the amount of phase or amplitude deviation.

  Note that the ultrasonic measurement apparatus 100, the ultrasonic imaging apparatus, and the like of the present embodiment may realize part or most of the processing by a program. In this case, a processor such as a CPU executes the program, thereby realizing the ultrasonic measurement apparatus 100, the ultrasonic image apparatus, and the like according to the present embodiment. Specifically, a program stored in the information storage medium is read, and a processor such as a CPU executes the read program. Here, the information storage medium (computer-readable medium) stores programs, data, and the like, and functions as an optical disk (DVD, CD, etc.), HDD (hard disk drive), or memory (card type). It can be realized by memory, ROM, etc. A processor such as a CPU performs various processes according to the present embodiment based on a program (data) stored in the information storage medium. That is, in the information storage medium, a program for causing a computer (an apparatus including an operation unit, a processing unit, a storage unit, and an output unit) to function as each unit of the present embodiment (a program for causing the computer to execute processing of each unit) Is memorized.

4). Processing Flow Hereinafter, the processing flow of this embodiment will be described with reference to the flowchart of FIG.

  First, the initial value of the scanning line number n is set to 1 (S101).

  Next, the transmission pulse generator 111 generates a pulse voltage having a phase of 0 degree (S102).

  Then, the transmission delay circuit 113 performs transmission focus control (S103), and the ultrasonic probe 200 emits an ultrasonic beam corresponding to a pulse voltage having a phase of 0 degree to the object (S104). Furthermore, the ultrasonic probe 200 receives the ultrasonic echo that is returned from the reflected ultrasonic beam reflected by the object (S104).

  On the other hand, the reception delay circuit 121 performs reception focus control (S105), and the filter circuit 123 performs BPF (band pass filter) processing on the reception signal after reception focus control (S106), and after BPF processing. The received signal is stored in the memory 125 (S107).

  Next, with respect to the transmission wave whose phase is inverted by 180 degrees, processing similar to that in steps S102 to S107 is performed, and ultrasonic transmission / reception processing is performed (S108 to S113).

  Then, it is determined whether or not the processing of steps S102 to S113 has been performed for all the scanning lines (S114). Specifically, it is determined whether or not the current scanning line number n is smaller than the total scanning line number N.

  If it is determined that the processing of steps S102 to S113 has not been performed for all the scanning lines, that is, if it is determined that the current scanning line number n is smaller than the total scanning line number N, the current scanning line number n 1 is added to (S115), and the processing of steps S102 to S114 is performed again.

  On the other hand, if it is determined in step S114 that the processing in steps S102 to S113 has been performed for all the scanning lines, that is, if it is determined that the current scanning line number n is equal to the total scanning line number N, the harmonic processing is performed. The unit 131 performs a harmonic (harmonic component) extraction process (S116).

  Here, the flow of a specific harmonic extraction process is shown in the flowchart of FIG. First, a phase or amplitude deviation amount X is estimated for a received wave corresponding to a transmitted wave having a phase of 0 degrees and a received wave corresponding to a transmitted wave having a phase of 180 degrees (S201). For example, a cross-correlation method is used to estimate the deviation amount X.

  Next, the amount of deviation X is compared with a given threshold A (S202).

  If it is determined that the deviation amount X is smaller than the given threshold A, harmonics are extracted by the phase inversion method (S203).

  On the other hand, if it is determined that the deviation amount X is greater than or equal to the given threshold A, harmonic extraction processing is performed by the filter method (S204).

  Then, after the absolute value (rectification) processing is performed on the extracted harmonics, the detection processing unit 133 applies a low-pass filter to extract a non-modulated signal (S117), and the logarithmic conversion processing unit 135 detects the logarithm. Conversion processing is performed (S118).

  Then, the gain / dynamic range adjustment unit 137 adjusts the signal intensity and the region of interest (S119), and the STC 139 corrects the amplification degree (brightness) according to the depth (S120).

  Further, the DSC 150 performs scan conversion processing to generate B-mode image data (display image data) (S121), the display unit 300 displays the generated display image data (S122), and the processing ends. To do.

5. Ultrasonic Transducer Element FIGS. 10A to 10C show a configuration example of the ultrasonic transducer element 10 of the ultrasonic transducer device. The ultrasonic transducer element 10 includes a vibration film (membrane, support member) 50 and a piezoelectric element part. The piezoelectric element section includes a first electrode layer (lower electrode) 21, a piezoelectric layer (piezoelectric film) 30, and a second electrode layer (upper electrode) 22.

  FIG. 10A is a plan view of the ultrasonic transducer element 10 formed on the substrate (silicon substrate) 60 as viewed from the direction perpendicular to the substrate 60 on the element formation surface side. FIG. 10B is a cross-sectional view showing a cross section along A-A ′ of FIG. FIG. 10C is a cross-sectional view showing a cross section along B-B ′ of FIG.

  The first electrode layer 21 is formed on the vibration film 50 as a metal thin film, for example. The first electrode layer 21 may be a wiring that extends to the outside of the element formation region and is connected to the adjacent ultrasonic transducer element 10 as shown in FIG.

  The piezoelectric layer 30 is formed of, for example, a PZT (lead zirconate titanate) thin film, and is provided so as to cover at least a part of the first electrode layer 21. The material of the piezoelectric layer 30 is not limited to PZT. For example, lead titanate (PbTiO3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb, La) TiO3) or the like is used. Also good.

  The second electrode layer 22 is formed of a metal thin film, for example, and is provided so as to cover at least a part of the piezoelectric layer 30. The second electrode layer 22 may be a wiring that extends to the outside of the element formation region and is connected to the adjacent ultrasonic transducer element 10 as shown in FIG.

  The vibration film (membrane) 50 is provided so as to close the opening 40 by, for example, a two-layer structure of a SiO2 thin film and a ZrO2 thin film. The vibration film 50 supports the piezoelectric layer 30 and the first and second electrode layers 21 and 22 and can vibrate according to the expansion and contraction of the piezoelectric layer 30 to generate ultrasonic waves.

  The opening 40 is formed by etching by reactive ion etching (RIE) or the like from the back surface (surface on which no element is formed) side of the substrate 60 (silicon substrate). The resonance frequency of the ultrasonic wave is determined by the size of the opening 45 of the opening 40, and the ultrasonic wave is radiated to the piezoelectric layer 30 side (from the back to the front in FIG. 10A).

  The lower electrode (first electrode) of the ultrasonic transducer element 10 is formed by the first electrode layer 21, and the upper electrode (second electrode) is formed by the second electrode layer 22. Specifically, a portion of the first electrode layer 21 covered with the piezoelectric layer 30 forms a lower electrode, and a portion of the second electrode layer 22 covering the piezoelectric layer 30 forms an upper electrode. . That is, the piezoelectric layer 30 is provided between the lower electrode and the upper electrode.

6). Ultrasonic Transducer Device FIG. 11 shows a configuration example of an ultrasonic transducer device (element chip). The ultrasonic transducer device of this configuration example includes a plurality of ultrasonic transducer element groups UG1 to UG64, drive electrode lines DL1 to DL64 (first to nth drive electrode lines in a broad sense, n is an integer of 2 or more). , Common electrode lines CL1 to CL8 (first to mth common electrode lines in a broad sense. M is an integer of 2 or more). Note that the number of drive electrode lines (n) and the number of common electrode lines (m) are not limited to the numbers shown in FIG.

  The plurality of ultrasonic transducer element groups UG1 to UG64 are arranged in 64 rows along the second direction D2 (scanning direction). Each of the ultrasonic transducer element groups UG1 to UG64 has a plurality of ultrasonic transducer elements arranged along the first direction D1 (slice direction).

  FIG. 12A shows an example of the ultrasonic transducer element group UG (UG1 to UG64). In FIG. 12A, the ultrasonic transducer element group UG is composed of first to fourth element arrays. The first element row is configured by ultrasonic transducer elements UE11 to UE18 arranged along the first direction D1, and the second element row is an ultrasonic wave arranged along the first direction D1. It is constituted by transducer elements UE21 to UE28. The same applies to the third element row (UE31 to UE38) and the fourth element row (UE41 to UE48). Drive electrode lines DL (DL1 to DL64) are commonly connected to these first to fourth element rows. Further, common electrode lines CL1 to CL8 are connected to the ultrasonic transducer elements of the first to fourth element rows.

  Then, the ultrasonic transducer element group UG in FIG. 12A constitutes one channel of the ultrasonic transducer device. That is, the drive electrode line DL corresponds to a 1-channel drive electrode line, and a 1-channel transmission signal from the transmission circuit is input to the drive electrode line DL. In addition, a one-channel reception signal from the drive electrode line DL is output from the drive electrode line DL. Note that the number of element rows constituting one channel is not limited to four rows as shown in FIG. 12A, and may be less than four rows or more than four rows. For example, as shown in FIG. 12B, the number of element rows may be one.

  As shown in FIG. 11, the drive electrode lines DL1 to DL64 (first to nth drive electrode lines) are wired along the first direction D1. Of the drive electrode lines DL1 to DL64, the jth drive electrode line DLj (jth channel) where j is an integer satisfying 1 ≦ j ≦ n is an ultrasonic transformer of the jth ultrasonic transducer element group UGj. It is connected to a first electrode (for example, a lower electrode) of the reducer element.

  In a transmission period in which ultrasonic waves are emitted, transmission signals VT1 to VT64 are supplied to the ultrasonic transducer elements via the drive electrode lines DL1 to DL64. In the reception period for receiving the ultrasonic echo signal, the reception signals VR1 to VR64 from the ultrasonic transducer elements are output via the drive electrode lines DL1 to DL64.

  The common electrode lines CL1 to CL8 (first to mth common electrode lines) are wired along the second direction D2. The second electrode of the ultrasonic transducer element is connected to any one of the common electrode lines CL1 to CL8. Specifically, for example, as illustrated in FIG. 11, the i-th common electrode line CLi (i is an integer satisfying 1 ≦ i ≦ m) among the common electrode lines CL1 to CL8 is arranged in the i-th row. The ultrasonic transducer element is connected to a second electrode (for example, an upper electrode).

  A common voltage VCOM is supplied to the common electrode lines CL1 to CL8. The common voltage VCOM may be a constant DC voltage and may not be 0 V, that is, the ground potential (ground potential).

  In the transmission period, a voltage difference between the transmission signal voltage and the common voltage is applied to the ultrasonic transducer element, and ultrasonic waves having a predetermined frequency are emitted.

  The arrangement of the ultrasonic transducer elements is not limited to the matrix arrangement shown in FIG. 11, but may be a so-called staggered arrangement.

  10A to 12B show the case where one ultrasonic transducer element is used as both a transmitting element and a receiving element, the present embodiment is not limited to this. For example, ultrasonic transducer elements for transmitting elements and ultrasonic transducer elements for receiving elements may be provided separately and arranged in an array.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. The configurations and operations of the ultrasonic measurement device, the ultrasonic image device, and the ultrasonic measurement method are not limited to those described in the present embodiment, and various modifications can be made.

100 ultrasonic measurement device, 110 transmission processing unit, 111 transmission pulse generator,
113 transmission delay circuit, 120 reception processing unit, 121 reception delay circuit,
123 filter circuit, 125 memory, 130 processing unit,
131 harmonic processing unit, 133 detection processing unit, 135 logarithmic conversion processing unit,
137 Gain / dynamic range adjustment unit, 139 STC,
140 transmission / reception changeover switch, 150 DSC, 160 control circuit,
200 Ultrasonic probe, 300 Display unit

Claims (7)

A transmission processing unit that performs processing of transmitting ultrasonic waves to the object;
A reception processing unit that performs reception processing of ultrasonic echoes for the transmitted ultrasonic waves;
A processing unit for processing a received signal from the reception processing unit;
Including
The transmission processing unit
Outputting a first transmission signal of a first phase and a second transmission signal of a second phase that is 180 degrees different in phase from the first transmission signal;
The reception processing unit
The first reception signal is output by the reception process of the first ultrasonic echo with respect to the first transmission signal, and the second reception process of the second ultrasonic echo with respect to the second transmission signal is performed by the second process. Output the received signal
The processor is
Based on the first reception signal and the second reception signal, a change process of a positional relationship between the object and the ultrasonic probe is performed, and based on a result of the detection process, the super Determine whether to use the filter method or the phase inversion method to extract the harmonic component of the acoustic echo,
If it is determined that the filter method is used, the first received signal or the second received signal is filtered, and the harmonic component of the ultrasonic echo is extracted.
When it is determined that the phase inversion method is used, the harmonic component of the ultrasonic echo is extracted by performing an addition process or a subtraction process on the first reception signal and the second reception signal. A characteristic ultrasonic measuring device. In claim 1,
The processor is
As the detection process, a process of detecting a phase or amplitude shift amount between the first reception signal and the second reception signal is performed, and the ultrasonic echo based on a result of the detection process An ultrasonic measurement apparatus that determines whether to use the filter method or the phase inversion method as a harmonic component extraction method. In claim 1 or 2,
The transmission processing unit
When it is determined by the processing unit that the filter method is used as the harmonic component extraction method, a third transmission signal is output,
The reception processing unit
According to the reception process of the third ultrasonic echo for the third transmission signal, a third reception signal is output,
The processor is
An ultrasonic measurement apparatus, wherein the filtering process is performed on the third reception signal to extract the harmonic component of the ultrasonic echo. In claim 3,
The processor is
In the determination period for determining the harmonic component extraction method to be used, the positional relationship between the object and the ultrasonic probe is changed based on the first reception signal and the second reception signal. Determining whether to use the filter method or the phase inversion method as the harmonic component extraction method of the ultrasonic echo based on the result of the detection processing,
When it is determined that the filter method is used as the harmonic component extraction method, the filtering process is performed on the third received signal in the measurement period of the harmonic component of the ultrasonic echo, and the super An ultrasonic measurement apparatus that extracts the harmonic component of a sound wave echo. In any one of Claims 1 thru | or 4,
The processor is
An ultrasonic measurement apparatus, wherein a phase or amplitude shift amount between the first reception signal and the second reception signal is detected by a cross-correlation method. An ultrasonic measurement apparatus according to any one of claims 1 to 5;
A display unit for displaying display image data generated based on the harmonic component of the ultrasonic echo;
An ultrasonic imaging apparatus comprising: As a process of transmitting an ultrasonic wave to an object, a first transmission signal having a first phase and a second transmission signal having a second phase that is 180 degrees different from the first transmission signal are obtained. Process to output,
By receiving the first ultrasonic echo with respect to the first transmission signal, the first reception signal is output,
By the reception process of the second ultrasonic echo with respect to the second transmission signal, a second reception signal is output,
Based on the first reception signal and the second reception signal, a detection process of a change in the positional relationship between the object and the ultrasonic probe is performed,
Based on the result of the detection process, it is determined whether to use a filter method or a phase inversion method as a harmonic component extraction method of the ultrasonic echo,
If it is determined that the filter method is used, the first received signal or the second received signal is filtered, and the harmonic component of the ultrasonic echo is extracted.
When it is determined that the phase inversion method is used, the harmonic component of the ultrasonic echo is extracted by performing an addition process or a subtraction process on the first reception signal and the second reception signal. A characteristic ultrasonic measurement method.