JP6058368B2 - Ultrasonic diagnostic apparatus and control program - Google Patents

Description

  Embodiments described herein relate generally to an ultrasonic diagnostic apparatus and a control program.

  Conventionally, the tissue harmonic imaging (THI) method is used as a method for obtaining a B-mode image with high spatial resolution. The THI method is a method of performing imaging using a harmonic component (for example, a second harmonic component) included in a received signal. In the THI method, since the bandwidth of the harmonic component is narrower than the bandwidth of the fundamental component, the azimuth resolution is improved. However, since the bandwidth of the harmonic component is narrow or “penetration” in the deep region is insufficient due to the harmonic reception, the distance resolution may not be improved by the THI method.

  Therefore, in recent years, as a THI method for obtaining a B-mode image with high azimuth resolution and distance resolution, a method of performing imaging using a second harmonic component and a difference sound component included in a received signal has been put into practical use. Hereinafter, this method is referred to as an imaging method using a difference sound component. In the imaging method using the difference sound component, an ultrasonic wave having a waveform obtained by synthesizing two fundamental waves having different center frequencies is transmitted a plurality of times while inverting the phase of each scanning line, and these received signals are synthesized. This synthesized signal becomes a synthesized harmonic signal including a second harmonic component and a difference sound component on the lower frequency side, and becomes a harmonic echo having a wider band than the signal obtained by the conventional THI method. In the imaging method using the difference sound component, a B-mode image with high spatial resolution (azimuth resolution and distance resolution) can be obtained by imaging using this synthesized harmonic signal.

  Here, in order to obtain a B-mode image with high distance resolution by the imaging method using the difference sound component, the amplitude of each of the two fundamental waves having different center frequencies so that the frequency characteristic of the synthesized harmonic signal becomes a wide band. It is necessary to adjust the level. The ultrasonic wave transmitted from the ultrasonic probe attenuates as the distance from the transducer surface of the ultrasonic probe increases and the center frequency increases. In the imaging method using the difference sound component, since two fundamental waves having different center frequencies are used, the intensity of the received signal from the deep portion differs between the fundamental waves. For this reason, in the imaging method using the difference sound component, it is necessary to adjust the amplitude level of each of the two fundamental waves according to the frequency attenuation characteristics of each of the two fundamental waves used for imaging.

  Furthermore, the frequency attenuation characteristic differs for each scanning target. The level adjustment described above needs to consider not only the frequency attenuation characteristics of each of the two fundamental waves used for imaging, but also the frequency attenuation characteristics of the scanning target. For this reason, the level adjustment described above is not easy, and in the imaging method using the difference sound component, the image quality may be deteriorated due to the difference in frequency attenuation characteristics.

Japanese Patent No. 4557573

  The problem to be solved by the present invention is an ultrasonic diagnostic apparatus and control program capable of stabilizing the image quality of an image obtained by using the difference sound component and the second harmonic regardless of the difference in frequency attenuation characteristics. Is to provide.

The ultrasonic diagnostic apparatus according to the embodiment includes an acquisition unit, an adjustment unit, a transmission / reception unit, a synthesis unit, an image generation unit, and a storage unit . The acquisition unit acquires related information related to the frequency attenuation characteristics of the imaging region. The adjustment unit changes a ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave according to the related information, and The waveform of the synthesized ultrasonic wave with the second fundamental wave is adjusted. The transmission / reception unit generates the plurality of reflected wave data by transmitting the synthetic ultrasonic wave a plurality of times while inverting the phase. A synthesis unit that synthesizes the plurality of reflected wave data and extracts a difference sound component between the first fundamental wave and the second fundamental wave and a second harmonic component of the first fundamental wave; Is generated. The image generation unit generates ultrasonic image data using the synthesized data. The storage unit is configured to obtain a ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave, or the ratio of the first fundamental wave and the second fundamental wave, from which combined data with a maximum bandwidth is obtained. Are stored in association with the frequency attenuation coefficient. The acquisition unit acquires a frequency attenuation coefficient of the imaging region as the related information. The adjustment unit specifies a ratio corresponding to the frequency attenuation coefficient acquired by the acquisition unit or a waveform corresponding to the frequency attenuation coefficient acquired by the acquisition unit from the storage unit. The transmission / reception unit transmits transmission ultrasonic waves obtained by synthesizing the first fundamental wave and the second fundamental wave at a ratio specified by the adjustment unit, or transmission ultrasonic waves having a waveform specified by the adjustment unit.

FIG. 1 is a block diagram illustrating a configuration example of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 2 is a schematic diagram for explaining an imaging method using a difference sound component. FIG. 3 is a diagram for explaining a problem of a conventional imaging method using a difference sound component. FIG. 4 is a diagram illustrating an example of information stored in the internal storage unit according to the first embodiment. FIG. 5 is a diagram illustrating an example of a first method performed by the acquisition unit according to the first embodiment. FIG. 6 is a diagram illustrating an example of a second method performed by the acquisition unit according to the first embodiment. FIG. 7 is a diagram illustrating an example of frequency characteristics of the synthesized harmonic signal obtained by the processing of the adjustment unit according to the first embodiment. FIG. 8 is a flowchart illustrating an example of processing of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 9 is a diagram (1) for explaining the second embodiment. FIG. 10 is a diagram (2) for explaining the second embodiment. FIG. 11 is a diagram (3) for explaining the second embodiment. FIG. 12 is a flowchart illustrating an example of processing of the ultrasonic diagnostic apparatus according to the second embodiment. FIG. 13 is a diagram (1) for explaining a modification according to the first and second embodiments. FIG. 14 is a diagram (2) for explaining a modification according to the first and second embodiments.

  Hereinafter, embodiments of an ultrasonic diagnostic apparatus will be described in detail with reference to the accompanying drawings.

(First embodiment)
First, the configuration of the ultrasonic diagnostic apparatus according to the first embodiment will be described. FIG. 1 is a block diagram illustrating a configuration example of the ultrasonic diagnostic apparatus according to the first embodiment. As illustrated in FIG. 1, the ultrasonic diagnostic apparatus according to the first embodiment includes an ultrasonic probe 1, a monitor 2, an input device 3, and an apparatus main body 10.

  The ultrasonic probe 1 includes a plurality of piezoelectric vibrators, and the plurality of piezoelectric vibrators generate ultrasonic waves based on a drive signal supplied from a transmission / reception unit 11 included in the apparatus main body 10 described later. The plurality of piezoelectric vibrators included in the ultrasonic probe 1 receives reflected waves from the subject P and converts them into electrical signals. The ultrasonic probe 1 includes a matching layer provided in the piezoelectric vibrator, a backing material that prevents propagation of ultrasonic waves from the piezoelectric vibrator to the rear, and the like. The ultrasonic probe 1 is detachably connected to the apparatus main body 10.

  When ultrasonic waves are transmitted from the ultrasonic probe 1 to the subject P, the transmitted ultrasonic waves are reflected one after another at the discontinuous surface of the acoustic impedance in the body tissue of the subject P, and the ultrasonic probe is used as a reflected wave signal. 1 is received by a plurality of piezoelectric vibrators. The amplitude of the received reflected wave signal depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic wave is reflected. Note that the reflected wave signal when the transmitted ultrasonic pulse is reflected by the moving blood flow or the surface of the heart wall depends on the velocity component of the moving object in the ultrasonic transmission direction due to the Doppler effect. And undergoes a frequency shift.

  In the first embodiment, even if the ultrasonic probe 1 is a 1D array probe that scans the subject P in two dimensions, the ultrasonic probe 1 is a mechanical 4D probe or 2D array probe that scans the subject P in three dimensions. Is applicable.

  The input device 3 includes a mouse, a keyboard, a button, a panel switch, a touch command screen, a foot switch, a trackball, a joystick, and the like. The input device 3 accepts various setting requests from an operator of the ultrasonic diagnostic apparatus, and transfers the accepted various setting requests to the apparatus main body 10.

  The monitor 2 displays a GUI (Graphical User Interface) for an operator of the ultrasonic diagnostic apparatus to input various setting requests using the input device 3, and displays ultrasonic image data generated in the apparatus main body 10. Or display.

  The apparatus main body 10 is an apparatus that generates ultrasonic image data based on a reflected wave signal received by the ultrasonic probe 1. The apparatus main body 10 shown in FIG. 1 can generate two-dimensional ultrasound image data based on a two-dimensional reflected wave signal, and can generate three-dimensional ultrasound image data based on a three-dimensional reflected wave signal. Device. However, the first embodiment is applicable even when the apparatus main body 10 is an apparatus dedicated to two-dimensional data.

  As illustrated in FIG. 1, the apparatus main body 10 includes a transmission / reception unit 11, a B-mode processing unit 12, a Doppler processing unit 13, an image generation unit 14, an image memory 15, an internal storage unit 16, and a control unit. 17.

  The transmission / reception unit 11 controls ultrasonic transmission / reception performed by the ultrasonic probe 1 based on an instruction from the control unit 17 described later. The transmission / reception unit 11 includes a pulse generator, a transmission delay unit, a pulser, and the like, and supplies a drive signal to the ultrasonic probe 1. The pulse generator repeatedly generates rate pulses for forming transmission ultrasonic waves at a predetermined rate frequency. The transmission delay unit generates a delay time for each piezoelectric vibrator necessary for focusing the ultrasonic wave generated from the ultrasonic probe 1 into a beam and determining transmission directivity. Give for each rate pulse. The pulser applies a drive signal (drive pulse) to the ultrasonic probe 1 at a timing based on the rate pulse.

  That is, the transmission delay unit arbitrarily adjusts the transmission direction of the ultrasonic wave transmitted from the piezoelectric vibrator surface by changing the delay time given to each rate pulse. The transmission delay unit controls the position of the focal point (transmission focus) in the depth direction of ultrasonic transmission by changing the delay time given to each rate pulse. The transmission / reception unit 11 according to the first embodiment performs multi-focusing (multi-focusing) in which an ultrasonic beam is transmitted a plurality of times while changing the depth of the transmission focus point on the same scan line at a predetermined focus rate. It may be executable. When performing multistage focusing, the transmission delay unit included in the transmission / reception unit 11 calculates a transmission delay time according to the depth of each transmission focus point, and supplies the transmission delay time to the pulsar circuit.

  The transmission / reception unit 11 has a function capable of instantaneously changing a transmission frequency, a transmission drive voltage, and the like in order to execute a predetermined scan sequence based on an instruction from the control unit 17 described later. In particular, the change of the transmission drive voltage is realized by a linear amplifier type transmission circuit capable of instantaneously switching the value or a mechanism for electrically switching a plurality of power supply units.

  For example, the transmission / reception unit 11 according to the first embodiment controls the transmission ultrasonic wave having a waveform notified from the control unit 17 described later to be transmitted from the ultrasonic probe 1. Alternatively, for example, the transmission / reception unit 11 according to the first embodiment calculates a transmission waveform from information notified from the control unit 17 to be described later, and the transmission ultrasonic wave having the calculated waveform is transmitted from the ultrasonic probe 1. To control.

  The transmission / reception unit 11 includes an amplifier circuit, an A / D (Analog / Digital) converter, a reception delay circuit, an adder, a quadrature detection circuit, and the like. Various types of reflected wave signals received by the ultrasonic probe 1 are used. Processing is performed to generate reflected wave data. The amplifier circuit amplifies the reflected wave signal for each channel and performs gain correction processing. The A / D converter A / D converts the reflected wave signal whose gain is corrected. The reception delay circuit gives a reception delay time necessary for determining the reception directivity to the digital data. The adder performs addition processing of the reflected wave signal given the reception delay time by the reception delay circuit. By the addition processing of the adder, the reflection component from the direction corresponding to the reception directivity of the reflected wave signal is emphasized. Then, the quadrature detection circuit converts the output signal of the adder into a baseband in-phase signal (I signal, I: In-pahse) and a quadrature signal (Q signal, Q: Quadrature-phase). Then, the quadrature detection circuit stores the I signal and the Q signal (hereinafter referred to as IQ signal) as reflected wave data in a frame buffer (not shown). The quadrature detection circuit may convert the output signal of the adder into an RF (Radio Frequency) signal and store it in a frame buffer (not shown).

  The transmitter / receiver 11 transmits a two-dimensional ultrasonic beam from the ultrasonic probe 1 when the subject P is two-dimensionally scanned. Then, the transmission / reception unit 11 generates two-dimensional reflected wave data from the two-dimensional reflected wave signal received by the ultrasonic probe 1. In addition, when the subject P is three-dimensionally scanned, the transmission / reception unit 11 transmits a three-dimensional ultrasonic beam from the ultrasonic probe 1. Then, the transmission / reception unit 11 generates three-dimensional reflected wave data from the three-dimensional reflected wave signal received by the ultrasonic probe 1.

  The B-mode processing unit 12 and the Doppler processing unit 13 are signal processing units that perform various types of signal processing on the reflected wave data generated from the reflected wave signal by the transmission / reception unit 11. The B-mode processing unit 12 receives the reflected wave data from the transmission / reception unit 11, performs logarithmic amplification, envelope detection processing, and the like, and generates data (B-mode data) in which the signal intensity is expressed by brightness. . Further, the Doppler processing unit 13 performs frequency analysis on velocity information from the reflected wave data received from the transmission / reception unit 11 and extracts data (Doppler data) obtained by extracting moving body information such as velocity, dispersion, and power due to the Doppler effect at multiple points. Generate. Here, the moving body is, for example, a blood flow, a tissue such as a heart wall, or a contrast agent. The B-mode processing unit 12 and the Doppler processing unit 13 acquire reflected wave data via the frame buffer described above.

  Note that the B-mode processing unit 12 and the Doppler processing unit 13 illustrated in FIG. 1 can process both two-dimensional reflected wave data and three-dimensional reflected wave data. That is, the B-mode processing unit 12 generates two-dimensional B-mode data from the two-dimensional reflected wave data, and generates three-dimensional B-mode data from the three-dimensional reflected wave data. The Doppler processing unit 13 generates two-dimensional Doppler data from the two-dimensional reflected wave data, and generates three-dimensional Doppler data from the three-dimensional reflected wave data.

  Here, as illustrated in FIG. 1, the B-mode processing unit 12 includes a synthesis unit 121 and a B-mode data generation unit 122. The B mode data generation unit 122 performs logarithmic amplification, envelope detection processing, and the like on the reflected wave data to generate B mode data. When normal B-mode imaging is performed, the processing by the combining unit 121 is not executed, and the B-mode data generation unit 122 generates B-mode data from the reflected wave data received from the transmission / reception unit 11.

  On the other hand, when harmonic imaging is performed by phase modulation (PM), amplitude modulation (AM), or phase amplitude modulation (AMPM), the B-mode data generation unit 122 is a synthesis unit. B-mode data is generated from the data output from 121. Note that the processing of the combining unit 121 will be described in detail later.

  The image generation unit 14 generates ultrasonic image data from the data generated by the B mode processing unit 12 and the Doppler processing unit 13. The image generation unit 14 generates two-dimensional B-mode image data in which the intensity of the reflected wave is represented by luminance from the two-dimensional B-mode data generated by the B-mode processing unit 12. Further, the image generation unit 14 generates two-dimensional Doppler image data representing moving body information from the two-dimensional Doppler data generated by the Doppler processing unit 13. The two-dimensional Doppler image data is velocity image data, distributed image data, power image data, or image data obtained by combining these.

  Here, the image generation unit 14 generally converts (scan converts) a scanning line signal sequence of ultrasonic scanning into a scanning line signal sequence of a video format represented by a television or the like, and displays ultrasonic waves for display. Generate image data. Specifically, the image generation unit 14 generates ultrasonic image data for display by performing coordinate conversion in accordance with the ultrasonic scanning mode of the ultrasonic probe 1. In addition to scan conversion, the image generation unit 14 performs various image processing, such as image processing (smoothing processing) for regenerating an average value image of luminance using a plurality of image frames after scan conversion, for example. Then, image processing (edge enhancement processing) using a differential filter is performed in the image. In addition, the image generation unit 14 synthesizes character information, scales, body marks, and the like of various parameters with the ultrasound image data.

  B-mode data and Doppler data are ultrasonic image data before the scan conversion process, and data generated by the image generation unit 14 is ultrasonic image data for display after the scan conversion process. The B-mode data and the Doppler data are also called raw data (Raw Data). The image generation unit 14 generates two-dimensional ultrasonic image data for display from the two-dimensional ultrasonic image data before the scan conversion process.

  Further, the image generation unit 14 generates three-dimensional B-mode image data by performing coordinate conversion on the three-dimensional B-mode data generated by the B-mode processing unit 12. Further, the image generation unit 14 generates three-dimensional Doppler image data by performing coordinate conversion on the three-dimensional Doppler data generated by the Doppler processing unit 13. The image generation unit 14 generates “3D B-mode image data or 3D Doppler image data” as “3D ultrasound image data (volume data)”.

  Further, the image generation unit 14 performs various rendering processes on the volume data in order to generate two-dimensional image data for displaying the volume data on the monitor 2. The rendering process performed by the image generation unit 14 includes, for example, a process of generating MPR image data from volume data by performing a multi-planar reconstruction (MPR). The rendering processing performed by the image generation unit 14 includes, for example, volume rendering (VR) processing that generates two-dimensional image data reflecting three-dimensional information.

  The image memory 15 is a memory for storing image data for display generated by the image generation unit 14. The image memory 15 can also store data generated by the B-mode processing unit 12 and the Doppler processing unit 13. The B-mode data and Doppler data stored in the image memory 15 can be called by an operator after diagnosis, for example, and become ultrasonic image data for display via the image generation unit 14. The image memory 15 can also store the reflected wave data output from the transmission / reception unit 11.

  The internal storage unit 16 stores a control program for performing ultrasonic transmission / reception, image processing and display processing, diagnostic information (for example, patient ID, doctor's findings, etc.), various data such as a diagnostic protocol and various body marks. To do. The internal storage unit 16 is also used for storing image data stored in the image memory 15 as necessary. Data stored in the internal storage unit 16 can be transferred to an external device via an interface (not shown). The internal storage unit 16 can also store data transferred from an external device via an interface (not shown). Information stored in the internal storage unit 16 according to the first embodiment will be described in detail later.

  The control unit 17 controls the entire processing of the ultrasonic diagnostic apparatus. Specifically, the control unit 17 is based on various setting requests input from the operator via the input device 3 and various control programs and various data read from the internal storage unit 16. The processing of the processing unit 12, the Doppler processing unit 13, and the image generation unit 14 is controlled. Further, the control unit 17 controls the display 2 to display ultrasonic image data for display stored in the image memory 15 or the internal storage unit 16. Here, the control part 17 which concerns on 1st Embodiment has the acquisition part 171 and the adjustment part 172 so that it may illustrate in FIG. The acquisition unit 171 and the adjustment unit 172 are installed in the control unit 17 in order to control the transmission / reception unit 11 when an imaging method using a difference sound component, which will be described later, is performed. The acquisition unit 171 and the adjustment unit 172 will be described in detail later.

  The transmission / reception unit 11 and the like built in the apparatus main body 10 may be configured by hardware such as an integrated circuit, but may be a program modularized in software.

  The overall configuration of the ultrasonic diagnostic apparatus according to the first embodiment has been described above. With this configuration, the ultrasonic diagnostic apparatus according to the first embodiment performs, for example, a tissue harmonic imaging (THI) method using a PM method that is a pulse inversion method. The THI method is a method of performing imaging using a harmonic component (for example, a second harmonic component) included in a received signal.

  For example, the transmission / reception unit 11 transmits the ultrasonic wave of the fundamental wave having the center frequency “f” twice on each scanning line while inverting the phase by the scan sequence set by the control unit 17. For example, when transmitting / receiving the ultrasonic wave having the center frequency “f” twice with one scanning line, the transmission / reception unit 11 determines the polarity of the first transmission ultrasonic wave and the second transmission ultrasonic wave. Invert the polarity. Thereby, the transmission / reception unit 11 generates two reflected wave data with one scanning line. Here, the reflected wave data obtained by the first transmission “+1” is “r (+1)”, and the reflected wave data obtained by the second transmission “−1” is “r (−1)”.

  In such a case, the polarity of the fundamental wave component derived from the fundamental wave is inverted between “r (+1)” and “r (−1)”. On the other hand, the polarities of the second harmonic components derived from the second harmonic whose center frequency is “2f” are the same as “r (+1)” and “r (−1)”. Therefore, the synthesis unit 121 adds “r (+1)” and “r (−1)” to generate a synthesized signal (synthesized data). In this synthesized signal (synthesized data), the fundamental wave component is removed, and a harmonic signal in which the second harmonic component remains mainly remains. The B mode data generation unit 122 generates B mode data from the combined data generated by the combining unit 121, and the image generation unit 14 generates ultrasonic image data (B mode image data) from the B mode data. Since the bandwidth of the harmonic component is narrower than the bandwidth of the fundamental component, the azimuth resolution of B-mode image data obtained by the above method is higher than that of normal B-mode image data.

  However, since the bandwidth of the harmonic component is narrow or “penetration” in the deep region is insufficient due to harmonic reception, the above method may not improve the distance resolution.

  Therefore, in recent years, as a THI method for obtaining B-mode image data having a high azimuth resolution and distance resolution, a method for imaging using a second harmonic component and a difference sound component included in a received signal has been put into practical use. . Hereinafter, this method is referred to as an imaging method using a difference sound component. In the imaging method using the difference sound component, an ultrasonic wave having a waveform obtained by synthesizing two fundamental waves having different center frequencies is transmitted a plurality of times while inverting the phase of each scanning line, and these received signals are synthesized. FIG. 2 is a schematic diagram for explaining the THI method using a difference sound component. 2 indicates the frequency (unit: MHz), and the vertical axis in FIG. 2 indicates the signal intensity (unit: dB).

  For example, two fundamental waves used in an imaging method using a difference sound component are divided into a first fundamental wave having a center frequency “f1” and a second fundamental wave having a center frequency “f2” greater than “f1”. To do. The transmission / reception unit 11 causes the ultrasonic probe 1 to transmit a transmission ultrasonic wave having a combined waveform obtained by combining the waveform of the first fundamental wave and the waveform of the second fundamental wave. This synthesized waveform is a waveform obtained by synthesizing the waveform of the first fundamental wave and the waveform of the second fundamental wave whose phases are adjusted so that a differential sound component having the same polarity as the second harmonic component is generated. It is. This phase condition is adjusted by the control unit 17. Hereinafter, the phase condition for generating the difference sound component having the same polarity as the second harmonic component is referred to as the same polarity phase condition.

  As schematically shown in FIG. 2, the received signal by the transmission ultrasonic wave having the combined waveform of the first fundamental wave and the second fundamental wave is a first signal derived from the first fundamental wave having the center frequency “f1”. The fundamental wave component and the second fundamental wave component derived from the second fundamental wave having the center frequency “f2” are included. Further, as schematically shown in FIG. 2, the received signal includes a second harmonic component derived from a second harmonic having a center frequency of “2f1” and a second harmonic having a center frequency of “2f2”. And second harmonic components derived from waves.

  When two fundamental waves having different center frequencies are used, the received signal is derived from a difference sound “f2-f1” between the second fundamental wave and the first fundamental wave as schematically shown in FIG. Difference sound component to be included. Note that “DC” schematically shown in FIG. 2 is a component corresponding to the term “0th order” among the nonlinear components (harmonic components) of the received signal.

  Here, the transmission / reception unit 11 transmits the transmission ultrasonic wave of the composite waveform a plurality of times (for example, twice) while inverting the phase. For example, the transmission / reception unit 11 reverses the polarity of the first transmission ultrasonic wave and the polarity of the second transmission ultrasonic wave when transmitting the transmission ultrasonic wave of the composite waveform twice with one scanning line. Thereby, the transmission / reception unit 11 generates two reflected wave data with one scanning line. Here, the reflected wave data obtained by the first transmission “+1” is “R (+1)”, and the reflected wave data obtained by the second transmission “−1” is “R (−1)”.

  In such a case, the polarity of the first fundamental wave component and the polarity of the second fundamental wave component are inverted between “R (+1)” and “R (−1)”. On the other hand, the polarity of the second harmonic component derived from the second harmonic “2f1”, the polarity of the second harmonic component derived from the second harmonic “2f2”, and the difference sound “f2-f1” The polarity of the difference sound component is the same for “R (+1)” and “R (−1)”. Therefore, the synthesis unit 121 adds “R (+1)” and “R (−1)” to generate a synthesized signal (synthesized data). In this synthesized signal (synthesized data), the fundamental wave component is removed, and a harmonic signal in which the difference sound component and the second harmonic component mainly remain is obtained.

  Further, the synthesis unit 121 removes the second harmonic component and “DC” derived from the second harmonic “2f2” from the synthesized signal (synthetic data) by filtering. Alternatively, for example, the control unit 17 sets the frequency band of the second harmonic component derived from the second harmonic “2f2” to be outside the frequency band that can be received by the ultrasonic probe 1. In such a case, since the second harmonic component derived from “2f1” is not included in the reflected wave data, the synthesizer 121 removes “DC” from the synthesized signal (synthesized data) by filtering. As a result, the synthesis unit 121 extracts synthesis data (synthetic harmonic signal) obtained by extracting the difference sound component of “f2−f1” and the second harmonic component of “2f1”.

  And B mode data is produced | generated from the synthetic | combination data which the synthetic | combination part 121 output, and the image generation part 14 produces | generates ultrasonic image data (B mode image data) from this B mode data.

  The synthesized data output from the synthesizing unit 121 becomes a synthesized harmonic signal including a second harmonic component and a difference sound component on the lower frequency side, and becomes a harmonic echo having a wider band than a signal obtained by the conventional THI method. In the imaging method using the difference sound component, B-mode image data having high spatial resolution (azimuth resolution and distance resolution) can be obtained by performing imaging using this synthesized harmonic signal.

  In the imaging method using the difference sound component, the values of “f1” and “f2” are adjusted by the control unit 17 according to the frequency band to be visualized. For example, when “f1 = f” is set and imaging is performed in a wide frequency band centered on “2f”, the value of “f2” is adjusted to “f2 = 3 × f”. Further, for example, when “f1 = f” is set and imaging is performed in a wide frequency band centered on a frequency higher than “2f”, the value of “f2” is larger than “3 × f”. For example, “f2 = 3.5 × f” is adjusted. Also, for example, when “f1 = f” is set and imaging is performed in a wide frequency band centered on a frequency lower than “2f”, the value of “f2” is smaller than “3 × f”. The value is adjusted to, for example, “f2 = 2.5 × f”.

  Here, in order to obtain a B-mode image with high distance resolution by the imaging method using the difference sound component, the amplitude of each of the two fundamental waves having different center frequencies so that the frequency characteristic of the synthesized harmonic signal becomes a wide band. It is necessary to adjust the level. The ultrasonic wave transmitted from the ultrasonic probe 1 attenuates as the distance from the transducer surface of the ultrasonic probe 1 increases and the center frequency increases. In the imaging method using the difference sound component, since two fundamental waves having different center frequencies are used, the intensity of the received signal from the deep portion differs between the fundamental waves. For this reason, in the imaging method using the difference sound component, it is necessary to adjust the amplitude level of each of the two fundamental waves according to the frequency attenuation characteristics of each of the two fundamental waves used for imaging.

  Furthermore, the frequency attenuation characteristic differs for each imaging region of the subject P. Further, the frequency attenuation characteristic varies among patients even in the same imaging region. Further, the frequency attenuation characteristics may vary depending on the imaging time even in the imaging region of the same subject P. As described above, the frequency attenuation characteristic is different for each imaging region. The level adjustment described above needs to consider not only the frequency attenuation characteristics of each of the two fundamental waves used for imaging, but also the frequency attenuation characteristics of the scanning target.

  Temporarily, under the same polarity phase condition, transmit ultrasonic waves having a composite waveform in which the amplitude of the first fundamental wave of “f1” and the amplitude of the second fundamental wave of “f2” are “1: 1” Assume that transmission is performed twice while inversion. In this case, the frequency characteristic of the synthesized harmonic signal output from the synthesis unit 121 varies depending on the frequency reduction coefficient to be scanned. This will be specifically described with reference to FIG. FIG. 3 is a diagram for explaining a problem of a conventional imaging method using a difference sound component.

  The horizontal axes in FIGS. 3A and 3B indicate the frequency (unit: MHz), and the vertical axes in FIGS. 3A and 3B indicate the signal intensity (unit: dB). In FIGS. 3A and 3B, the frequency characteristics of the synthesized harmonic signal are indicated by solid lines. 3A and 3B, the frequency characteristics of the subtraction data when the synthesis unit 121 subtracts “R (−1)” from “R (+1)” are indicated by dotted lines. The subtraction data is data in which the difference component and the second harmonic component are removed, and the first fundamental wave component and the second fundamental wave component mainly remain.

  When the frequency attenuation coefficient is as low as “−0.5 dB / MHz / cm”, the synthesized harmonic signal has a broadband frequency characteristic ranging from 1 MHz to 4.5 MHz, as illustrated by the solid line in FIG. . In such a case, the image generation unit 14 can generate ultrasonic image data with high spatial resolution.

  On the other hand, when the frequency attenuation coefficient is higher than “−0.5 dB / MHz / cm”, the synthesized harmonic signal has a low second-order harmonic component in the vicinity of 4 MHz as illustrated by the solid line in FIG. In addition, the center frequency is low and the frequency band is narrow. In such a case, the spatial resolution of the ultrasonic image data generated by the image generation unit 14 is reduced.

  Further, when the ratio “A (f1) / A (f2)” of the amplitude “A (f1)” of the first fundamental wave to the amplitude “A (f2)” of the second fundamental wave is increased, the composite harmonic signal has 2 The second harmonic component increases. Further, when the ratio “A (f2) / A (f1)” of the amplitude of the second fundamental wave to the amplitude of the first fundamental wave is increased, the difference sound component increases. As described above, the level adjustment is not easy, and in the conventional imaging method using the difference sound component, the image quality may be deteriorated due to the difference in frequency attenuation characteristics.

  Therefore, in the first embodiment, the acquisition unit 171 illustrated in FIG. 1 is used to stabilize the image quality of the image obtained using the difference sound component and the second harmonic regardless of the difference in frequency attenuation characteristics. And the adjustment part 172 performs the process demonstrated below.

  That is, the acquisition unit 171 acquires related information related to the frequency attenuation characteristics of the imaging region. Then, the adjusting unit 172 changes the ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave according to the related information. Thereby, the adjustment part 172 adjusts the waveform of the synthetic | combination ultrasonic wave of a 1st fundamental wave and a 2nd fundamental wave.

  And the transmission / reception part 11 is made to transmit a synthetic | combination ultrasonic wave (transmission ultrasonic wave of the waveform after adjustment) in multiple times, reversing a phase, and produces | generates several reflected wave data. Then, the synthesizer 121 synthesizes the plurality of reflected wave data, and extracts the synthesized data in which the difference sound component between the first fundamental wave and the second fundamental wave and the second harmonic component of the first fundamental wave are extracted. Generate.

  Specifically, the transmission / reception unit 11 transmits the transmission ultrasonic wave of the composite waveform twice on each scanning line. At this time, the transmission / reception unit 11 reverses the polarity of the first transmission ultrasonic wave and the polarity of the second transmission ultrasonic wave. Thereby, the transmission / reception unit 11 generates two reflected wave data in each scanning line. Then, the combining unit 121 adds the two reflected wave data to generate combined data that is a combined harmonic signal. Then, the image generation unit 14 generates ultrasonic image data using the composite data.

  In order to perform the above processing, the internal storage unit 16 according to the first embodiment stores one of the two pieces of information described below. For example, the internal storage unit 16 stores the ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave in association with the frequency attenuation coefficient. This ratio is an optimum ratio for obtaining combined data with the maximum bandwidth, and the optimum ratio is a value calculated in advance using a phantom or the like having a different frequency attenuation coefficient.

  Alternatively, as the second information, the internal storage unit 16 stores a waveform (optimal waveform) obtained by synthesizing the first fundamental wave and the second fundamental wave at the optimum ratio in association with the frequency attenuation coefficient. As described above, the internal storage unit 16 according to the first embodiment stores the optimum ratio according to the frequency attenuation coefficient or the optimum waveform according to the frequency attenuation coefficient. The internal storage unit 16 stores, for example, an optimum ratio or an optimum waveform for each combination of the value of the center frequency “f1” of the first fundamental wave and the value of the center frequency “f2” of the second fundamental wave. . Alternatively, for example, a plurality of sections are set for the value of the center frequency, and the internal storage unit 16 stores the optimum ratio or the optimum waveform calculated under the same polarity phase condition for each combination of these sections. It may be the case.

  FIG. 4 is a diagram illustrating an example of information stored in the internal storage unit according to the first embodiment. An example shown in FIG. 4A is a table of optimum ratios according to the frequency attenuation coefficient with values “f1” and “f2” adjusted according to the frequency band to be imaged. Also, an example shown in FIG. 4B is an optimum waveform table corresponding to the frequency attenuation coefficient at values “f1” and “f2” adjusted according to the frequency band to be imaged.

  FIG. 4A illustrates a case where the amplitude of the first fundamental wave is “A1”, the amplitude of the second fundamental wave is “A2”, and the optimal ratio is defined as “A1 / A2”. In such a case, for example, as shown in FIG. 4A, the internal storage unit 16 stores “R1” as the optimum ratio when the frequency attenuation coefficient “P” is “P ≦ P1”. For example, as shown in FIG. 4A, the internal storage unit 16 stores “R2” as the optimum ratio when the frequency attenuation coefficient “P” is “P1 <P ≦ P2”. Further, for example, as shown in FIG. 4A, the internal storage unit 16 stores “R3” as the optimal ratio when the frequency attenuation coefficient “P” is “P2 <P ≦ P3”. For example, as shown in FIG. 4A, the internal storage unit 16 stores “R4” as the optimum ratio when the frequency attenuation coefficient “P” is “P3 <P ≦ P4”. Further, for example, as shown in FIG. 4A, the internal storage unit 16 stores “R5” as the optimal ratio when the frequency attenuation coefficient “P” is “P4 <P ≦ P5”. When the optimum ratio is defined as “A1 / A2”, the value of the optimum ratio becomes smaller as the frequency attenuation coefficient becomes higher.

  Alternatively, for example, as shown in FIG. 4B, the internal storage unit 16 changes the optimum waveform “WF” when the frequency attenuation coefficient “P” is “P ≦ P1” to the optimum ratio “R1”. Based on “WF (R1)”. Further, for example, as shown in FIG. 4B, the internal storage unit 16 uses the optimum waveform “WF” when the frequency attenuation coefficient “P” is “P1 <P ≦ P2” as the optimum ratio “R2”. "WF (R2)" based on ". Further, for example, as shown in FIG. 4B, the internal storage unit 16 sets the optimum waveform “WF” when the frequency attenuation coefficient “P” is “P2 <P ≦ P3” to the optimum ratio “R3”. "WF (R3)" based on ". Further, for example, as shown in FIG. 4B, the internal storage unit 16 uses the optimum waveform “WF” when the frequency attenuation coefficient “P” is “P3 <P ≦ P4” as the optimum ratio “R4”. "WF (R4)" based on ". Further, for example, as shown in FIG. 4B, the internal storage unit 16 uses the optimum waveform “WF” when the frequency attenuation coefficient “P” is “P4 <P ≦ P5” as the optimum ratio “R5”. "WF (R5)" based on ".

  The above-mentioned optimum waveform “WF” is a waveform based on the center frequencies of the first fundamental wave and the second fundamental wave, the same polarity phase condition, and the optimum ratio. The optimum waveform is a case where the optimum waveform is automatically generated by the adjustment unit 172 and stored in the internal storage unit 16 before photographing based on the center frequency of the first fundamental wave and the second fundamental wave and the same polarity phase condition from the optimum ratio. May be.

  And the acquisition part 171 which concerns on 1st Embodiment acquires the frequency attenuation coefficient of the said imaging | photography site | part as related information relevant to the frequency attenuation characteristic of an imaging | photography site | part. Here, the acquisition unit 171 according to the first embodiment acquires the frequency attenuation coefficient of the imaging region by the two methods described below.

  In the first method, the acquisition unit 171 receives the designation of the frequency attenuation coefficient of the imaging region from the operator. That is, in the first method, the operator inputs the frequency attenuation coefficient of the imaging region of the subject P via the input device 3. In the first method, the frequency attenuation coefficient is manually set. FIG. 5 is a diagram illustrating an example of a first method performed by the acquisition unit according to the first embodiment. For example, the operator inputs the frequency attenuation coefficient “P5” via the input device 3. Thereby, the acquisition unit 171 acquires the frequency attenuation coefficient “P5” as illustrated in FIG. 5.

  On the other hand, in the second method, the frequency attenuation coefficient of the imaging region of the subject P is automatically set. That is, in the second method, the acquisition unit 171 transmits the first fundamental wave and the second fundamental wave to the imaging region, and calculates the frequency attenuation coefficient of the imaging region based on the obtained reflected wave data. get. As an example, the acquisition unit 171 acquires the frequency attenuation coefficient of the imaging region based on the reflected wave data of the first fundamental wave and the second fundamental wave transmitted to the imaging region before imaging of the subject P. . For example, under the control of the acquisition unit 171, the transmission / reception unit 11 causes the amplitude of the first fundamental wave of “f1” and the amplitude of the second fundamental wave of “f2” to be “1: 1” under the same polarity phase condition. The transmission ultrasonic wave having the synthesized waveform is transmitted twice while inverting the phase. Thereby, the transmission / reception part 11 produces | generates two reflected wave data with each scanning line. Then, the synthesis unit 121 generates subtraction data obtained by subtracting the two reflected wave data.

  As described above, the subtraction data is data obtained by extracting the first fundamental wave component and the second fundamental wave component. Therefore, the acquisition unit 171 can acquire the signal intensity of the first fundamental wave component and the signal intensity of the second fundamental wave component by analyzing the frequency characteristics of the subtraction data. That is, in the second method, a pulse inversion method using a composite waveform in which the amplitude ratio of two fundamental waves is set to “1: 1” under the same polarity phase condition is performed, and two fundamental wave components are extracted. Data is generated by the synthesis unit 121.

  FIG. 6 is a diagram illustrating an example of a second method performed by the acquisition unit according to the first embodiment. In FIG. 6, the frequency characteristics of the subtraction data of two sample points having different depth directions are indicated by a solid line and a dotted line. The sample point corresponding to the frequency characteristic of the dotted line illustrated in FIG. 6 is located deeper than the sample point corresponding to the frequency characteristic of the solid line illustrated in FIG. As illustrated in FIG. 6, the signal intensity of the first fundamental wave component “f1” is lower as it is deeper, and the signal intensity of the second fundamental wave component “f2” is lower as it is deeper. On the other hand, as illustrated in FIG. 6, the attenuation of the signal intensity of the first fundamental wave component “f1” in the depth direction is smaller than the attenuation of the signal intensity of the second fundamental wave component “f2” in the depth direction. .

  The acquisition unit 171 determines the attenuation factor of the signal intensity of the first fundamental wave component “f1” and the signal of the second fundamental wave component “f2” from the frequency characteristics of the subtraction data of each of the plurality of sample points along the depth direction. Collect intensity decay rate. Thereby, the acquisition unit 171 acquires the frequency attenuation coefficient of the imaging region when the center frequency of the first fundamental wave is “f1” and the center frequency of the second fundamental wave is “f2”.

  Note that the acquisition unit 171 uses, for example, a single scanning line located at the center of the imaging region to perform frequency transmission of the imaging region from one subtraction data generated by performing ultrasonic transmission / reception for acquiring the frequency attenuation coefficient. Get the damping factor. Alternatively, the acquisition unit 171 executes, for example, ultrasonic transmission / reception for acquiring a frequency attenuation coefficient on a plurality of scanning lines that are a part of all the scanning lines used for scanning the entire imaging region in the main imaging. To generate subtraction data. For example, the acquisition unit 171 acquires the frequency attenuation coefficient for each scanning line from each of the plurality of subtraction data, and acquires the frequency attenuation coefficient of the imaging region by averaging the acquired plurality of frequency attenuation coefficients. Or the acquisition part 171 may perform the ultrasonic transmission / reception for frequency attenuation coefficient acquisition, for example with all the scanning lines.

  Then, the adjustment unit 172 specifies a ratio (optimum ratio) corresponding to the frequency attenuation coefficient acquired by the acquisition unit 171 from the internal storage unit 16. And the transmission / reception part 11 transmits the transmission ultrasonic wave which synthesize | combined the 1st fundamental wave and the 2nd fundamental wave with the ratio (optimum ratio) which the adjustment part 172 specified. The above processing is performed when the transmission / reception unit 11 can calculate a transmission waveform from information such as frequency, phase, and amplitude.

  For example, when the frequency attenuation coefficient acquired by the acquisition unit 171 is “P5”, the adjustment unit 172 specifies that the optimum ratio is “R5” from the internal storage unit 16 illustrated in FIG. To do. Then, the adjustment unit 172 notifies the transmission / reception unit 11 of the optimum ratio “R5”. The transmission / reception unit 11 calculates a transmission waveform from the center frequency of the first fundamental wave and the second fundamental wave, the same polarity phase condition, and the optimum ratio “R5”, and transmits the transmission ultrasonic wave of the calculated transmission waveform (synthetic waveform). Transmit twice while reversing the phase.

  Alternatively, the adjustment unit 172 specifies a waveform (optimal waveform) corresponding to the frequency attenuation coefficient acquired by the acquisition unit 171 from the internal storage unit 16. And the transmission / reception part 11 transmits the transmission ultrasonic wave of the waveform (optimal waveform) which the adjustment part 172 specified. The above processing is performed when the transmission / reception unit 11 cannot calculate the transmission waveform.

  For example, when the frequency attenuation coefficient acquired by the acquisition unit 171 is “P5”, the adjustment unit 172 determines that the optimum waveform is “WF (R5)” from the internal storage unit 16 illustrated in FIG. Identifies it. Then, the adjustment unit 172 notifies the transmission / reception unit 11 of the optimum waveform “WF (R5)”. As a result, the transmission / reception unit 11 transmits the transmission ultrasonic wave having the optimum waveform “WF (R5)” twice while inverting the phase.

  And the synthetic | combination part 121 produces | generates synthetic | combination data by adding the two reflected wave data which the transmission / reception part 11 produced | generated. The B mode data generation unit 122 generates B frame data for one frame from the combined data of each scanning line, and the image generation unit 14 generates B mode image data from the B mode data for one frame.

  FIG. 7 is a diagram illustrating an example of frequency characteristics of the synthesized harmonic signal obtained by the processing of the adjustment unit according to the first embodiment. FIG. 7 shows the frequency characteristics of the synthesized harmonic signal (synthetic data, added data) in a solid line when the above processing is performed on the imaging part having the frequency attenuation coefficient shown in FIG. Yes. In FIG. 7, the frequency characteristic of the subtraction data is indicated by a dotted line.

  As shown in FIG. 7, the frequency characteristic of the synthesized harmonic signal has a wide band compared to the frequency characteristic of the synthesized harmonic signal shown in FIG. By using the B-mode data generated from the synthesized harmonic signal shown in FIG. 7, the image generation unit 14 can generate B-mode image data with high spatial resolution.

  Next, an example of processing of the ultrasonic diagnostic apparatus according to the first embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of processing of the ultrasonic diagnostic apparatus according to the first embodiment. In FIG. 8, the processing performed when the acquisition unit 171 executes the second method, that is, ultrasonic transmission / reception for acquiring the frequency attenuation coefficient, and the adjustment unit 172 specifies the optimum waveform from the internal storage unit 16. Illustrated.

  As illustrated in FIG. 8, the acquisition unit 171 of the ultrasonic diagnostic apparatus according to the first embodiment determines whether an imaging request by an imaging method using a difference sound component has been received (step S <b> 101). Here, when the imaging request is not accepted (No at Step S101), the acquisition unit 171 waits until the request is accepted.

  On the other hand, when the imaging request using the imaging method using the difference sound component is received (Yes in Step S101), the acquisition unit 171 performs ultrasonic transmission / reception for acquiring the frequency attenuation coefficient (Step S102). In addition, before step S102, the control unit 17 sets the center frequency and the same polarity phase condition of the first fundamental wave and the second fundamental wave, for example, according to the imaging frequency band set by the operator.

  And the acquisition part 171 acquires the frequency attenuation coefficient of an imaging | photography site | part by analyzing the frequency characteristic of subtraction data (step S103). And the adjustment part 172 specifies the waveform corresponding to the frequency attenuation coefficient acquired by the acquisition part 171 (step S104). The adjustment unit 172 notifies the transmission / reception unit 11 of the identified waveform (specific waveform).

  Then, under the control of the transmission / reception unit 11, the ultrasonic probe 1 performs ultrasonic transmission / reception using transmission waves of a specific waveform, that is, an optimal waveform (step S <b> 105). For example, the ultrasonic probe 1 executes ultrasonic transmission / reception by transmission ultrasonic waves having a specific waveform twice while inverting the phase. Thereby, the transmission / reception unit 11 generates two reflected wave data.

  Then, the synthesis unit 121 generates synthesized data (Step S106). The B mode data generation unit 122 generates B mode data from the combined data, and the image generation unit 14 generates ultrasonic image data (B mode image data) (step S107).

  Then, under the control of the control unit 17, the monitor 2 displays the ultrasonic image data (Step S108) and ends the process.

  As described above, in the first embodiment, the internal storage unit 16 holds the optimum ratio and the optimum waveform corresponding to the value of the frequency attenuation coefficient. In the first embodiment, the acquisition unit 171 acquires the frequency attenuation coefficient of the imaging region manually or automatically. In the first embodiment, the adjustment unit 172 specifies an optimum ratio or optimum waveform corresponding to the acquired frequency attenuation coefficient of the imaging region and feeds back to the transmission / reception unit 11. The transmission / reception unit 11 causes the ultrasonic probe 1 to perform transmission / reception of ultrasonic waves from which the differential sound component and the second harmonic component can be extracted in a wide band from the ultrasonic probe 1. Thereby, even if the frequency attenuation characteristics of the imaging region are different, the image generation unit 14 can always generate ultrasonic image data with high azimuth resolution and distance resolution. Therefore, in the first embodiment, the image quality of an image obtained using the difference sound component and the second harmonic can be stabilized regardless of the difference in frequency attenuation characteristics.

(Second Embodiment)
In the second embodiment, the case where information other than the frequency attenuation coefficient is used as related information related to the frequency attenuation characteristic of the imaging region will be described with reference to FIGS. 9 to 11. 9 to 11 are diagrams for explaining the second embodiment.

  The ultrasonic diagnostic apparatus according to the second embodiment is configured similarly to the ultrasonic diagnostic apparatus according to the first embodiment shown in FIG. However, in the second embodiment, information stored in the internal storage unit 16 and control processing performed by the acquisition unit 171 and the adjustment unit 172 are different from those in the first embodiment as described below.

  The control unit 17 (acquisition unit 171 or adjustment unit 172) according to the second embodiment causes the transmission / reception unit 11 to execute the following processing before imaging of the subject P. For example, according to an instruction from the adjustment unit 172, the transmission / reception unit 11 combines each of a plurality of waveforms obtained by combining the first fundamental wave and the second fundamental wave with different amplitude ratios before imaging the subject P. The ultrasonic probe 1 is caused to execute the used ultrasonic transmission / reception.

  For example, the internal storage unit 16 according to the second embodiment stores a plurality of ratios. For example, the internal storage unit 16 stores ten ratios “R1, R2,..., R9, R10” as “A1 / A2”. These ratio values and numbers can be changed to arbitrary values.

  The adjustment unit 172 acquires a plurality of ratios from the internal storage unit 16 before imaging the subject P. Here, the values of “f1” and “f2” and the same polarity phase condition have been adjusted by the adjustment unit 172 according to the imaging frequency band. The adjustment unit 172 notifies the transmission / reception unit 11 of the values of “f1” and “f2”, the same polarity phase condition, and the ratio of ten. From the information notified from the adjustment part 172, the transmission / reception part 11 is, as shown in FIG. 9, ten synthetic waveforms "WF (R1), WF (R2), ..., WF (R9), WF (R10). ) ”. Alternatively, the adjustment unit 172 calculates 10 composite waveforms “WF (R1), WF (R2),..., WF (R9), WF (R10)” and notifies the transmission / reception unit 11 of them.

  The transmission / reception unit 11 performs the transmission ultrasonic wave of WF (R1) twice while inverting the phase. Thereby, the transmission / reception unit 11 generates two reflected wave data corresponding to WF (R1), and the combining unit 121 generates combined data (R1) corresponding to WF (R1). By similar processing, the synthesis unit 121 generates “synthesis data (R2) corresponding to WF (R2) to synthesis data (R10) corresponding to WF (R10)”.

  Thus, the synthesis unit 121 generates a plurality of synthesized data corresponding to each of the plurality of waveforms. Then, the acquisition unit 171 performs frequency analysis on each of the plurality of combined data, and acquires the bandwidth of each combined data as related information related to the frequency attenuation characteristics of the imaging region.

  For example, the acquisition unit 171 detects the peak signal intensity from the combined data, and detects the minimum value and the maximum value of the frequency at which the signal intensity is 3 dB lower than the peak signal intensity. Then, the acquisition unit 171 acquires the difference between the maximum value and the minimum value as the bandwidth (BW) of the combined data.

  Accordingly, as illustrated in FIG. 10, the acquisition unit 171 performs “BW (R1)” corresponding to “WF (R1), WF (R2),..., WF (R9), WF (R10)”. , BW (R2),..., BW (R9), BW (R10) ”.

  And the adjustment part 172 specifies the waveform corresponding to the synthetic | combination data from which the bandwidth becomes the maximum among the bandwidth of each of several synthetic | combination data. For example, as illustrated in FIG. 11, the adjustment unit 172 specifies that BW (R6) has the maximum bandwidth, and specifies the combined waveform “WF (R6)” corresponding to BW (R6).

  Then, the adjustment unit 172 notifies the transmission / reception unit 11 of the identified waveform as a waveform of a transmission ultrasonic wave for imaging the subject P. When the transmission / reception unit 11 can calculate a waveform, the adjustment unit 172 notifies the transmission / reception unit 11 of a ratio corresponding to the identified waveform.

  Thereby, the ultrasound probe 1 transmits the transmission ultrasound of “WF (R6)” twice on each scanning line while inverting the phase under the control of the transmission / reception unit 11. Also in the second embodiment, ultrasonic image data is generated by the same processing described in the first embodiment.

  Note that, even when ultrasonic transmission / reception for obtaining a bandwidth for each amplitude ratio is executed by, for example, one scanning line located at the center of the imaging region, the entire imaging region is scanned by the main imaging. Among all the scanning lines used for this, it may be executed by some scanning lines or may be executed by all scanning lines. When executed with one scanning line, the acquisition unit 171 acquires a bandwidth for each amplitude ratio from one composite data for each amplitude ratio. When executed by a plurality of scanning lines, the acquisition unit 171 acquires an average bandwidth for each amplitude ratio from a plurality of combined data for each amplitude ratio. In such a case, the adjustment unit 172 identifies the waveform that has the maximum average amplitude width.

  In the second embodiment, the acquisition unit 171 acquires a specific band calculated from the bandwidth and the reception center frequency as related information, and the adjustment unit 172 specifies a waveform having the maximum specific band. It may be.

  Next, an example of processing of the ultrasonic diagnostic apparatus according to the second embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating an example of processing of the ultrasonic diagnostic apparatus according to the first embodiment.

  As illustrated in FIG. 12, the acquisition unit 171 of the ultrasonic diagnostic apparatus according to the second embodiment determines whether an imaging request based on an imaging method using a difference sound component has been received (Step S <b> 201). Here, when the imaging request is not accepted (No at Step S201), the acquisition unit 171 waits until the request is accepted.

  On the other hand, when the imaging request using the imaging method using the difference sound component is received (Yes in step S201), the adjustment unit 172 notified from the acquisition unit 171 that the imaging request has been received controls the transmission / reception unit 11. Then, ultrasonic transmission / reception is executed for each of the plurality of waveforms (step S202). In addition, before step S202, the control unit 17 sets the center frequency and the same polarity phase condition of the first fundamental wave and the second fundamental wave, for example, according to the imaging frequency band set by the operator.

  Then, the synthesis unit 121 generates synthesized data for each of the plurality of waveforms (step S203), and the acquisition unit 171 performs frequency analysis for each of the plurality of synthesized data to acquire a bandwidth (step S204). .

  Then, the adjustment unit 172 specifies a waveform having the maximum bandwidth (step S205), and notifies the transmission / reception unit 11 of the specified waveform (specific waveform).

  Then, under the control of the transmission / reception unit 11, the ultrasonic probe 1 performs ultrasonic transmission / reception using transmission ultrasonic waves having a specific waveform (step S206). For example, the ultrasonic probe 1 executes ultrasonic transmission / reception by transmission ultrasonic waves having a specific waveform twice while inverting the phase. Thereby, the transmission / reception unit 11 generates two reflected wave data.

  Then, the synthesizer 121 generates synthesized data (step S207). The B mode data generation unit 122 generates B mode data from the combined data, and the image generation unit 14 generates ultrasonic image data (B mode image data) (step S208).

  Then, under the control of the control unit 17, the monitor 2 displays the ultrasonic image data (step S209) and ends the process.

  As described above, in the second embodiment, a plurality of patterns of amplitude ratios for synthesizing the first fundamental wave and the second fundamental wave are prepared in advance, and a plurality of patterns of transmission waveforms using these ratios are used. A plurality of synthesized harmonic signals from which the second harmonic component and the difference sound component of the first fundamental wave are extracted are obtained. In the second embodiment, these signals are subjected to frequency analysis, a transmission waveform that provides the widest bandwidth is identified, and the identified transmission waveform is fed back to the transmission / reception unit 11. Thereby, even in the second embodiment, the image generation unit 14 can always generate ultrasonic image data with high azimuth resolution and distance resolution even when the frequency attenuation characteristics of the imaging regions are different.

  In the first and second embodiments, the case where the acquisition unit 171 acquires related information regarding the frequency attenuation characteristics of the entire imaging region has been described. However, the first and second embodiments described above may be cases where the imaging region is divided into a plurality of sections, and the acquisition unit 171 acquires related information for each of the plurality of sections. Hereinafter, modified examples according to the first and second embodiments will be described with reference to FIGS. 13 and 14. FIG. 13 and FIG. 14 are diagrams for explaining modifications according to the first and second embodiments.

  First, the first modification will be described. In the first modification, the imaging region is divided by one or a plurality of scanning lines. For example, in the first modified example, as shown in FIG. 13, the imaging region is divided into six sections in units of a plurality of scanning lines. In the first embodiment, when “six sections” illustrated in FIG. 13 are set, the operator inputs the frequency attenuation coefficient of each of “six sections”.

  Alternatively, in the first embodiment, when “six sections” illustrated in FIG. 13 are set, the acquisition unit 171 performs ultrasonic transmission / reception for acquiring a frequency attenuation coefficient in each of “six sections”. Let it run. Even when ultrasonic transmission / reception for acquiring the frequency attenuation coefficient is executed by one scanning line located at the center of each of the “six sections”, all the scanning lines in each of the “six sections” are transmitted. Among them, even when executed by a plurality of scanning lines, it may be executed by all the scanning lines of each of “six sections”. Thereby, the acquisition unit 171 acquires the frequency attenuation coefficient or the average frequency attenuation coefficient of each of “six sections”.

  Further, in the second embodiment, when “six sections” illustrated in FIG. 13 are set, the transmission / reception unit 11 performs “six ultrasonic transmission / reception for acquiring a bandwidth for each amplitude ratio”. Execute in each “section”. Even when ultrasonic transmission / reception for obtaining a bandwidth for each amplitude ratio is executed by one scanning line located at the center of each of the “six sections” as described above, “6 It may be executed by a plurality of scanning lines among all the scanning lines in each of the “sections” or may be executed in all the scanning lines in each of the “six sections”. Thereby, the acquisition unit 171 specifies the bandwidth or the average bandwidth of each of “six sections”.

  Then, the adjustment unit 172 adjusts the ultrasonic waveform in each of “6 sections” based on the related information of each of “6 sections”. The transmission / reception unit 11 performs ultrasonic transmission / reception using transmission ultrasonic waves having a corresponding ultrasonic waveform in each of “six sections”. The combining unit 121 generates combined data for each of “six sections”. Then, the image generation unit 14 generates ultrasonic image data using the combined data of each of “6 sections”.

  Next, a second modification will be described. The second modification is applied when the transmission / reception unit 11 can execute multi-stage focus in which the depth of transmission focus is changed at a predetermined focus rate in each scanning line. For example, as shown in FIG. 14A, when three transmission focus “F1, F2, F3” having different depths are set, the transmission / reception unit 11 scans the area including F1 in the first transmission / reception. , The region including F2 is scanned by the second transmission / reception, and the region including F3 is scanned by the third transmission / reception. As a result, the image generation unit 14 generates three ultrasonic image data focused for each of the three regions, and generates the ultrasonic image data of the entire imaging region by synthesizing the three ultrasonic image data. be able to.

  Therefore, in the second modification, the acquisition unit 171 acquires related information for each of a plurality of sections obtained by dividing the imaging region at a plurality of depths as related information related to the frequency attenuation characteristics of the imaging region. Then, the adjustment unit 172 adjusts the ultrasonic waveform in each of the plurality of sections based on the related information of each of the plurality of sections. And the transmission / reception part 11 performs the ultrasonic transmission / reception using the transmission ultrasonic wave which has an applicable ultrasonic waveform in each of several area at a predetermined focus rate. The synthesizing unit 121 generates combined data for each of the plurality of sections, and the image generating unit 14 generates ultrasonic image data using the combined data for each of the plurality of sections.

  For example, in the second modified example, as shown in FIG. 14B, the imaging region is divided into three sections in the depth direction. In the first embodiment, when “three sections” illustrated in FIG. 14B are set, the operator inputs the frequency attenuation coefficient of each of the “three sections”.

  Alternatively, in the first embodiment, when “three sections” illustrated in FIG. 14B is set, the acquisition unit 171 performs ultrasonic transmission / reception for acquiring the frequency attenuation coefficient by multi-stage focusing. It is executed in each of “three sections”. Even when ultrasonic transmission / reception for acquiring the frequency attenuation coefficient is executed by one scanning line located at the center of each of the “three sections”, all of the scanning lines in each of the “three sections” are transmitted. Among them, even when executed with a plurality of scanning lines, it may be executed with all the scanning lines of each of the “three sections”. Thereby, the acquisition unit 171 acquires the frequency attenuation coefficient or the average frequency attenuation coefficient of each of “three sections”.

  Further, in the second embodiment, when “three sections” illustrated in FIG. 14B is set, ultrasonic transmission / reception for acquiring a bandwidth for each amplitude ratio is performed by multistage focusing. It is executed in each of “three sections”. Even when ultrasonic transmission / reception for obtaining a bandwidth for each amplitude ratio is executed by one scanning line located at the center of each of the “three sections” as described above, “3 It may be executed by a plurality of scanning lines among all the scanning lines in each of the “sections”, or may be executed by all the scanning lines in each of the “three sections”. Thereby, the acquisition unit 171 specifies the bandwidth or the average bandwidth of each of “three sections”.

  Then, the adjustment unit 172 adjusts the ultrasonic waveform in each of “three sections” based on the related information of each of “three sections”. The transmission / reception unit 11 performs ultrasonic transmission / reception using transmission ultrasonic waves having a corresponding ultrasonic waveform at each of the “three sections” at a predetermined focus rate. The combining unit 121 generates combined data for each of “three sections”. Then, the image generation unit 14 generates ultrasonic image data by using the combined data of “three sections”.

  Further, in the case where multistage focusing can be performed, a third modified example in which the first modified example and the second modified example are combined may be performed. In the third modification, for example, as shown in FIG. 14C, the imaging region is divided into six sections in units of a plurality of scanning lines, and further divided into three sections in the depth direction. By being divided, it is divided into “18 sections”. In the third modification, related information is acquired in each of “18 sections” and the ultrasonic waveform is adjusted in each of “18 sections” by the processing described with reference to FIGS. 13 and 14B. Is done.

  By performing the first modification, the second modification, or the third modification, the spatial resolution of the ultrasonic image data generated by the imaging method using the difference sound component can be further improved.

  The control method executed by the ultrasonic diagnostic apparatus described in the first and second embodiments and the first to third modifications is a control program prepared in advance such as a personal computer or a workstation. It can be realized by executing on a computer. This control program can be distributed via a network such as the Internet. The control program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, or a DVD, and being read from the recording medium by the computer.

  As described above, according to the first and second embodiments and the first to third modifications, the image quality of an image obtained using the difference sound component and the second harmonic is expressed by the frequency. Stabilization can be achieved regardless of the difference in attenuation characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 Transmission / reception part 121 Synthesis | combination part 14 Image generation part 171 Acquisition part 172 Adjustment part

Claims (7)

An acquisition unit for acquiring related information related to the frequency attenuation characteristics of the imaging region;
The ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave is changed according to the related information, and the first fundamental wave and the second fundamental wave are changed. An adjustment unit for adjusting the waveform of the synthesized ultrasonic wave with the wave;
A transmission / reception unit that generates a plurality of reflected wave data by transmitting the synthesized ultrasonic wave a plurality of times while inverting the phase;
Combining the plurality of reflected wave data to generate synthesized data in which a difference sound component between the first fundamental wave and the second fundamental wave and a second harmonic component of the first fundamental wave are extracted. And
An image generation unit that generates ultrasonic image data using the synthesized data;
The ratio of the amplitude of the first fundamental wave and the amplitude of the second fundamental wave, or the ratio of the first fundamental wave and the second fundamental wave, with which the combined data with the maximum bandwidth is obtained is synthesized. A storage unit that stores a waveform in association with a frequency attenuation coefficient;
The acquisition unit acquires a frequency attenuation coefficient of the imaging region as the related information,
The adjustment unit specifies a ratio corresponding to the frequency attenuation coefficient acquired by the acquisition unit, or a waveform corresponding to the frequency attenuation coefficient acquired by the acquisition unit from the storage unit,
The transceiver unit, synthesized transmitted ultrasonic wave and the second fundamental wave and the first fundamental wave by the ratio of the adjusting unit has identified, or, and this to transmit the transmission ultrasound wave that the adjusting unit has identified An ultrasonic diagnostic apparatus characterized by the above. The ultrasonic diagnostic apparatus according to claim 1 , wherein the acquisition unit receives designation of a frequency attenuation coefficient of the imaging region from an operator. The acquisition unit transmits the first fundamental wave and the second fundamental wave to the imaging region, and acquires a frequency attenuation coefficient of the imaging region based on each obtained reflected wave data The ultrasonic diagnostic apparatus according to claim 1 . An acquisition unit for acquiring related information related to the frequency attenuation characteristics of the imaging region;
The ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave is changed according to the related information, and the first fundamental wave and the second fundamental wave are changed. An adjustment unit for adjusting the waveform of the synthesized ultrasonic wave with the wave;
A transmission / reception unit that generates a plurality of reflected wave data by transmitting the synthesized ultrasonic wave a plurality of times while inverting the phase;
Combining the plurality of reflected wave data to generate synthesized data in which a difference sound component between the first fundamental wave and the second fundamental wave and a second harmonic component of the first fundamental wave are extracted. And
An image generation unit that generates ultrasonic image data using the synthesized data,
The transmission / reception unit performs ultrasonic transmission / reception using each of a plurality of waveforms obtained by synthesizing the first fundamental wave and the second fundamental wave with different amplitude ratios before imaging the subject. ,
The synthesis unit generates a plurality of synthesized data corresponding to each of the plurality of waveforms,
The acquisition unit performs frequency analysis on each of the plurality of combined data, acquires a bandwidth of each combined data as the related information,
The adjustment unit transmits, to the transmission / reception unit, a waveform corresponding to the combined data having the maximum bandwidth among the bandwidths of the plurality of combined data, as a waveform of a transmission ultrasonic wave for imaging the subject. An ultrasonic diagnostic apparatus characterized by notifying. In the case where the transmission / reception unit is capable of performing multi-stage focusing for changing the depth of transmission focus at each scanning line at a predetermined focus rate,
The acquisition unit acquires, as the related information, related information of each of a plurality of sections obtained by dividing the imaging region at a plurality of depths,
The adjustment unit adjusts an ultrasonic waveform in each of the plurality of sections based on related information of each of the plurality of sections,
The transmission / reception unit performs ultrasonic transmission / reception using transmission ultrasonic waves having a corresponding ultrasonic waveform at each of the plurality of sections at the predetermined focus rate;
The combining unit generates combined data for each of the plurality of sections;
The image generation section uses the combined data of each of the plurality of sections, the ultrasonic diagnostic apparatus according to any one of claims 1-4, characterized in that to generate ultrasonic image data. An acquisition procedure for acquiring related information related to the frequency attenuation characteristics of the imaging region;
The ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave is changed according to the related information, and the first fundamental wave and the second fundamental wave are changed. Adjustment procedure to adjust the waveform of the synthesized ultrasound with the wave,
A transmission / reception procedure for generating a plurality of reflected wave data by transmitting the synthesized ultrasonic wave a plurality of times while inverting the phase;
Combining the plurality of reflected wave data to generate synthesized data in which a difference sound component between the first fundamental wave and the second fundamental wave and a second harmonic component of the first fundamental wave are extracted. Procedure and
An image generation procedure for generating ultrasonic image data using the synthesized data;
The ratio of the amplitude of the first fundamental wave and the amplitude of the second fundamental wave, or the ratio of the first fundamental wave and the second fundamental wave, with which the combined data with the maximum bandwidth is obtained is synthesized. Causing the computer to execute a storage procedure for storing the waveform in the storage unit in association with the frequency attenuation coefficient ;
The acquisition procedure acquires a frequency attenuation coefficient of the imaging region as the related information,
The adjustment procedure specifies a ratio corresponding to the frequency attenuation coefficient acquired by the acquisition procedure, or a waveform corresponding to the frequency attenuation coefficient acquired by the acquisition procedure from the storage unit,
The transceiver procedure, transmits ultrasonic waves obtained by synthesizing the second fundamental wave and the first fundamental wave by the ratio identified by the adjustment procedure, or a call to send a transmission ultrasonic wave identified by said adjustment procedure A control program characterized by An acquisition procedure for acquiring related information related to the frequency attenuation characteristics of the imaging region;
The ratio between the amplitude of the first fundamental wave and the amplitude of the second fundamental wave having a center frequency larger than the center frequency of the first fundamental wave is changed according to the related information, and the first fundamental wave and the second fundamental wave are changed. Adjustment procedure to adjust the waveform of the synthesized ultrasound with the wave,
A transmission / reception procedure for generating a plurality of reflected wave data by transmitting the synthesized ultrasonic wave a plurality of times while inverting the phase;
Combining the plurality of reflected wave data to generate synthesized data in which a difference sound component between the first fundamental wave and the second fundamental wave and a second harmonic component of the first fundamental wave are extracted. Procedure and
An image generation procedure for generating ultrasonic image data using the composite data;
To the computer,
The transmission / reception procedure includes ultrasonic transmission / reception using a plurality of waveforms obtained by synthesizing the first fundamental wave and the second fundamental wave with different amplitude ratios before imaging the subject. Let the probe run,
The synthesis procedure generates a plurality of synthesized data corresponding to each of the plurality of waveforms,
The acquisition procedure performs frequency analysis for each of the plurality of combined data, and acquires the bandwidth of each combined data as the related information,
In the adjustment procedure, the ultrasonic probe uses a waveform corresponding to the synthetic data having the maximum bandwidth among the bandwidths of the plurality of synthetic data as a waveform of a transmission ultrasonic wave for imaging the subject. A control program characterized by causing a computer to transmit.

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