Ultrasonic diagnostic apparatus

Abstract

To improve image quality while suppressing degrading of a frame rate.SOLUTION: An ultrasonic diagnosis device of an embodiment includes: a transmission unit; a beam forming processing unit; and an extraction unit. The transmission unit performs transmission of ultrasonic pulses having different polarities for a plurality of times to analyte or transmission positions with different contrast mediums administrated to the analyte. The beam forming processing unit performs received beam forming processing to a plurality of received signals acquired by transmission of a plurality of ultrasonic pulses having the same polarity. The extraction unit extracts a non-linear signal by adding received signals at the same receiving position after received beam forming processing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to an ultrasonic diagnostic apparatus.

Background Art

[0002] In an ultrasonic diagnostic apparatus, as an imaging method used when generating B-mode image data, in recent years, an imaging method using a non-linear phenomenon of ultrasonic propagation in a living body called tissue harmonic imaging (THI) has become mainstream. In addition, contrast harmonic imaging (CHI) that depicts blood vessels by utilizing the non-linear phenomenon of an ultrasonic contrast agent injected into blood vessels is also used. As a method for obtaining a non-linear signal in these THI and CHI, the pulse inversion method is common. In the pulse inversion method, at the same position, a first ultrasonic pulse with a positive-pole leading (a first ultrasonic pulse with a positive polarity) and a second ultrasonic pulse with a negative-pole leading (a second ultrasonic pulse with a negative polarity) obtained by inverting the polarity of the first ultrasonic pulse are transmitted, and by adding the two received signals obtained by transmitting these two ultrasonic pulses, the fundamental wave component is suppressed and the non-linear component is extracted. However, since the ultrasonic pulse is transmitted twice at the same position, there is a problem that the frame rate is reduced to half (1 / 2) compared to the case where the ultrasonic pulse is transmitted once at the same position. If the density of transmission scan lines (transmission raster) is reduced to increase the parallel simultaneous reception number in order to increase the frame rate, a problem occurs that streaks appear in the ultrasonic image. The reason for such a problem is, for example, that the azimuth resolution is high, that is, the spatial frequency is high, near the transmission focus, so the spatial sampling theorem cannot be satisfied when the density of the transmission scan lines is small.

[0003] Here, a method is known in which the first ultrasonic pulse and the second ultrasonic pulse are transmitted to different positions instead of the same position, and two received signals at the same received position (same position) obtained by two-direction parallel simultaneous reception are added. The problem of the above-described decrease in the frame rate is solved by this method. Here, among the two received signals at the same position, it is preferable that the component obtained by inverting the fundamental wave component included in one received signal coincides with the fundamental wave component included in the other received signal. This is because the fundamental wave component is suppressed by adding the other received signal to one received signal. However, since the position where the positive-polarity ultrasonic pulse is transmitted is different from the position where the negative-polarity ultrasonic pulse is transmitted, the component obtained by inverting the fundamental wave component included in one received signal may not coincide with the fundamental wave component included in the other received signal. In this case, the fundamental wave component remains.

[0004] Therefore, not only non-linear signals but also linear signals are extracted by addition, and there is a problem that it is not preferable as THI and CHI. That is, there is a problem that the image quality is not good.

[0005] Note that a method of applying transmission focus also at points other than the transmission focus by a transmission aperture synthesis technique using a virtual sound source is known, using a plurality of received data obtained by a plurality of ultrasonic pulses transmitted to different positions.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0007] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the image quality while suppressing the decrease in the frame rate. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of each configuration shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0008] The ultrasonic diagnostic apparatus according to the embodiment includes a transmission unit, a beamforming processing unit, and an extraction unit. The transmission unit transmits ultrasonic pulses having different polarities a plurality of times to different transmission positions of the subject or a contrast agent administered to the subject. The beamforming processing unit performs reception beamforming processing on a plurality of reception signals obtained by transmitting ultrasonic pulses having the same polarity. The extraction unit extracts a non-linear signal by adding the reception signals at the same reception position after reception beamforming.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0010] Hereinafter, the ultrasonic diagnostic apparatus according to the embodiment will be described with reference to the drawings. Note that the embodiment can be combined with the prior art, other embodiments, or other modified examples as long as there is no contradiction in the content. Similarly, the modified examples can be combined with the prior art, other embodiments, or other modified examples as long as there is no contradiction in the content. In the following description, the same components may be given common reference numerals, and redundant descriptions may be omitted.

[0011] (First Embodiment) FIG. 1 is a block diagram showing a configuration example of an ultrasonic diagnostic apparatus 10 according to the first embodiment. As illustrated in FIG. 1, the ultrasonic diagnostic apparatus 10 according to the first embodiment includes an apparatus main body 100, an ultrasonic probe 101, an input device 102, and a display 103.

[0012] The ultrasonic probe 101 has, for example, a plurality of vibrators (piezoelectric elements). These plurality of vibrators generate ultrasonic waves based on a drive signal supplied from a transmission circuit 111 of a transmission / reception circuit 110 included in the apparatus main body 100. Specifically, the plurality of vibrators generate ultrasonic waves having a waveform corresponding to a transmission drive voltage when a voltage (transmission drive voltage) is applied by the transmission circuit 111. Further, the ultrasonic probe 101 receives a reflected wave from the subject P, converts the reflected wave into a reflected wave signal which is an electrical signal, and outputs (transmits) the reflected wave signal to the apparatus main body 100. The reflected wave signal is an example of a received signal. In addition, the ultrasonic probe 101 has, for example, a matching layer provided on the vibrator and a backing material or the like that prevents the propagation of ultrasonic waves rearward from the vibrator. Note that the ultrasonic probe 101 is detachably connected to the apparatus main body 100.

[0013] When ultrasonic waves (transmitted ultrasonic waves, ultrasonic pulses) are transmitted from the ultrasonic probe 101 to the subject P, the transmitted ultrasonic waves are successively reflected at the discontinuous surfaces of the acoustic impedance in the body tissues of the subject P, and are received by a plurality of vibrators included in the ultrasonic probe 101 as reflected waves. The amplitude of the received reflected waves depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic waves are reflected. When the transmitted ultrasonic pulse is reflected from the surface of a moving blood flow or a heart wall, etc., the reflected wave undergoes a frequency shift depending on the velocity component of the moving object with respect to the ultrasonic transmission direction due to the Doppler effect. Then, the ultrasonic probe 101 transmits the reflected wave signal to the receiving circuit 112 of the transmission / reception circuit 110 described later.

[0014] The ultrasonic probe 101 is detachably provided to the apparatus main body 100. When performing a two-dimensional scan (2D scan) of a two-dimensional region within the subject P, the operator connects, for example, a 1D array probe in which a plurality of vibrators are arranged in a row to the apparatus main body 100 as the ultrasonic probe 101. Examples of the types of 1D array probes include linear ultrasonic probes, convex ultrasonic probes, sector ultrasonic probes, etc. When performing a three-dimensional scan (3D scan) of a three-dimensional region within the subject P, the operator connects, for example, a mechanical 4D probe or a 2D array probe to the apparatus main body 100 as the ultrasonic probe 101. The mechanical 4D probe can perform a two-dimensional scan using a plurality of vibrators arranged in a row like a 1D array probe, and can perform a three-dimensional scan by swinging a plurality of vibrators at a predetermined angle (swing angle). Also, the 2D array probe can perform a three-dimensional scan with a plurality of vibrators arranged in a matrix, and can perform a two-dimensional scan by focusing and transmitting ultrasonic waves.

[0015] The input device 102 is realized by input means such as, for example, a mouse, a keyboard, a button, a panel switch, a touch command screen, a foot switch, a trackball, a joystick, etc. The input device 102 receives various setting requests from the operator of the ultrasonic diagnostic apparatus 10, and transfers the received various setting requests to the apparatus main body 100.

[0016] The display 103 displays, for example, a GUI (Graphical User Interface) for an operator of the ultrasonic diagnostic apparatus 10 to input various setting requests using the input device 102, or displays an ultrasonic image or the like based on the ultrasonic image data generated in the apparatus main body 100. The display 103 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, or the like.

[0017] The apparatus main body 100 generates ultrasonic image data based on the reflected wave signal transmitted from the ultrasonic probe 101. Note that the ultrasonic image data is an example of image data. The apparatus main body 100 can generate two-dimensional ultrasonic image data based on the reflected wave signal corresponding to the two-dimensional region of the subject P transmitted from the ultrasonic probe 101. Further, the apparatus main body 100 can generate three-dimensional ultrasonic image data based on the reflected wave signal corresponding to the three-dimensional region of the subject P transmitted from the ultrasonic probe 101. As shown in FIG. 1, the apparatus main body 100 includes a transmission / reception circuit 110, a beamformer 120, a signal processing circuit 130, an image generation circuit 140, an image memory 150, a storage circuit 160, and a control circuit 170.

[0018] The transmission / reception circuit 110, under the control of the control circuit 170, causes the ultrasonic probe 101 to transmit ultrasonic waves and causes the ultrasonic probe 101 to receive the reflected waves of the ultrasonic waves. That is, the transmission / reception circuit 110 executes scanning via the ultrasonic probe 101. Note that the scanning is also referred to as scan, ultrasonic scan, or ultrasonic scanning. The transmission / reception circuit 110 is an example of a transmission / reception unit. The transmission / reception circuit 110 includes a transmission circuit 111 and a reception circuit 112.

[0019] The transmission circuit 111 receives control from the control circuit 170, supplies a drive signal to the ultrasonic probe 101, and causes the ultrasonic probe 101 to transmit ultrasonic waves. The transmission circuit 111 includes a rate pulsar generation circuit, a transmission delay circuit, and a transmission pulsar. When scanning a two-dimensional region within the subject P, the transmission circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the two-dimensional region. Also, when scanning a three-dimensional region within the subject P, the transmission circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the three-dimensional region.

[0020] The rate pulsar generation circuit receives control from the control circuit 170 and repeatedly generates rate pulses for forming transmitted ultrasonic waves (transmission beams) at a predetermined rate frequency (PRF: Pulse Repetition Frequency). By passing through the transmission delay circuit, the rate pulses have different transmission delay times and a voltage is applied to the transmission pulsar. For example, the transmission delay circuit provides, for each rate pulse generated by the rate pulsar generation circuit, the transmission delay time for each vibrator necessary for focusing the ultrasonic waves generated from the ultrasonic probe 101 into a beam shape to determine the transmission directivity. The transmission pulsar supplies a drive signal (drive pulse) to the ultrasonic probe 101 at the timing based on the rate pulse. Note that the transmission delay circuit arbitrarily adjusts the transmission direction of the ultrasonic waves from the vibrator surface by changing the transmission delay time given to each rate pulse.

[0021] After the drive pulse is transmitted from the transmission pulsar to the vibrators in the ultrasonic probe 101 via a cable, the vibrators convert the electrical signal into mechanical vibrations at the vibrators. That is, when a voltage is applied to the vibrators, the vibrators vibrate mechanically. The ultrasonic waves generated by this mechanical vibration are transmitted into the living body. Here, the ultrasonic waves having different transmission delay times for each vibrator are focused and propagate in a predetermined direction.

[0022] Note that the transmission circuit 111 has a function that can instantaneously change the transmission frequency, transmission drive voltage, etc. in order to execute a predetermined scanning sequence under the control of the control circuit 170. In particular, the change in the transmission drive voltage is realized by a linear amplifier type transmission circuit that can instantaneously switch the value of the transmission drive voltage, or by a mechanism that electrically switches a plurality of power supply units.

[0023] The reflected wave of the ultrasonic wave transmitted by the ultrasonic probe 101 reaches the vibrator inside the ultrasonic probe 101, and then at the vibrator, it is converted from mechanical vibration into an electrical signal (reflected wave signal), and the converted reflected wave signal is input to the receiving circuit 112. That is, an analog-form reflected wave signal is input to the receiving circuit 112. The receiving circuit 112 includes an LNA (Low Noise Amplifier), an ATGC (Analog Time Gain Compensation) processing circuit, an ADC (Analog to Digital Convertor), a demodulator, etc., and performs various processes on the reflected wave signal transmitted from the ultrasonic probe 101 to generate a reflected wave signal in digital form, that is, a baseband band in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase). The I signal and the Q signal are called IQ signals. Then, the receiving circuit 112 transmits the generated IQ signals as reflected wave signals (received signals) to the beamformer 120.

[0024] Here, the transmission circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam from a predetermined transmission position (transmission scanning line). The reception circuit 112 receives, from the ultrasonic probe 101, a reflected wave signal caused by the reflected wave of the ultrasonic beam transmitted by the transmission circuit 111 at a predetermined reception position (reception scanning line). When parallel simultaneous reception is not performed, the transmission scanning line and the reception scanning line are the same scanning line. On the other hand, when parallel simultaneous reception is performed, when the transmission circuit 111 causes the ultrasonic probe 101 to transmit one ultrasonic beam on one transmission scanning line, the reception circuit 112 simultaneously receives, as a plurality of reception beams, the reflected wave signals caused by the reflected waves of the ultrasonic beam transmitted by the transmission circuit 111 to the ultrasonic probe 101 at a plurality of predetermined reception positions (reception scanning lines) through the ultrasonic probe 101.

[0025] The beamformer 120 generates reflected wave data by performing reception beamforming (receiving beamforming) and transmission beamforming (transmission beamforming) on the reflected wave signal transmitted by the reception circuit 112. As described above, although the reflected wave signal is an example of a received signal, the reflected wave data is also an example of a received signal. The beamformer 120 transmits the generated reflected wave data to the signal processing circuit 130. The beamformer 120 is realized, for example, by a processor. Details of the beamformer 120 will be described later.

[0026] The signal processing circuit 130 receives the reflected wave data transmitted by the beamformer 120, performs various signal processes on the received reflected wave data, and transmits the reflected wave data subjected to various signal processes to the image generation circuit 140 as B-mode data or Doppler data. The signal processing circuit 130 is realized, for example, by a processor. The signal processing circuit 130 is an example of a signal processing unit. Hereinafter, an example of various signal processes executed by the signal processing circuit 130 will be described.

[0027] For example, the signal processing circuit 130 performs various processes such as envelope detection processing and logarithmic compression on the reflected wave data to generate B-mode data in which the signal intensity (amplitude intensity) for each sample point is expressed by the brightness of the luminance. For example, the signal processing circuit 130 includes an envelope detector and a logarithmic compressor. For example, the envelope detector performs envelope detection on the reflected wave data, and the logarithmic compressor logarithmically compresses the data related to the envelope obtained by the envelope detection (for example, data indicating the amplitude). Thereby, B-mode data is generated. The signal processing circuit 130 transmits the generated B-mode data to the image generation circuit 140.

[0028] Also, the signal processing circuit 130 executes signal processing for performing harmonic imaging that visualizes harmonic components. Examples of harmonic imaging include CHI and THI. Also, in CHI and THI, as a scanning method, for example, phase modulation (PM: Phase Modulation) called the pulse inversion method is known.

[0029] Also, the signal processing circuit 130 extracts motion information of a moving object (such as blood flow, tissue, contrast agent echo components, etc.) based on the Doppler effect from the reflected wave data by performing frequency analysis on the reflected wave data, and generates Doppler data indicating the extracted motion information. For example, the signal processing circuit 130 extracts, at multiple points, the average velocity, average variance value, average power value, etc. as the motion information of the moving object, and generates Doppler data indicating the extracted motion information of the moving object. The signal processing circuit 130 transmits the generated Doppler data to the image generation circuit 140.

[0030] Using the functions of the signal processing circuit 130 described above, the ultrasonic diagnostic apparatus 10 according to the embodiment can execute a color Doppler method, also called a color flow mapping (CFM) method. In the color flow mapping method, ultrasonic transmission and reception are performed multiple times on a plurality of scanning lines. Then, in the color flow mapping method, by applying an MTI (Moving Target Indicator) filter to the data series at the same position, signals (clutter signals) derived from stationary tissues or tissues with slow movement are suppressed from the data series at the same position, and signals (blood flow signals) derived from blood flow are extracted. Then, in the color flow mapping method, blood flow information such as the velocity of blood flow, the dispersion of blood flow, and the power of blood flow is estimated from this blood flow signal. The signal processing circuit 130 transmits color image data indicating the blood flow information estimated by the color flow mapping method to the image generation circuit 140. Note that the color image data is an example of Doppler data.

[0031] The signal processing circuit 130 can process both two-dimensional reflected wave data and three-dimensional reflected wave data.

[0032] The image generation circuit 140 generates ultrasonic image data from the B-mode data or Doppler data transmitted by the signal processing circuit 130. The image generation circuit 140 is realized by a processor.

[0033] For example, the image generation circuit 140 generates two-dimensional B-mode image data representing the intensity of the reflected wave as luminance from the two-dimensional B-mode data generated by the signal processing circuit 130. Also, the image generation circuit 140 generates two-dimensional Doppler image data in which motion information or blood flow information is visualized from the two-dimensional Doppler data generated by the signal processing circuit 130. Note that the two-dimensional Doppler image data in which motion information is visualized is velocity image data, dispersion image data, power image data, or image data combining these.

[0034] Here, the image generation circuit 140 generally converts (scan-converts) the scan line signal sequence of the ultrasonic scan into a scan line signal sequence in a video format typified by a television or the like, and generates ultrasonic image data for display. For example, the image generation circuit 140 performs coordinate conversion on the data transmitted by the signal processing circuit 130 according to the scanning form of the ultrasonic waves by the ultrasonic probe 101, thereby generating ultrasonic image data for display. In addition, as various image processes other than scan conversion, the image generation circuit 140 performs, for example, an image process (smoothing process) of regenerating an average value image of luminance using a plurality of image frames after scan conversion, and an image process (edge enhancement process) using a differential filter within the image. Further, the image generation circuit 140 synthesizes character information, scales, body marks, and the like of various parameters with the ultrasonic image data.

[0035] Furthermore, the image generation circuit 140 performs coordinate conversion on the three-dimensional B-mode data generated by the signal processing circuit 130 to generate three-dimensional B-mode image data. Also, the image generation circuit 140 performs coordinate conversion on the three-dimensional Doppler data generated by the signal processing circuit 130 to generate three-dimensional Doppler image data. That is, the image generation circuit 140 generates "three-dimensional B-mode image data and three-dimensional Doppler image data" as "three-dimensional ultrasonic image data (volume data)". Then, the image generation circuit 140 performs various rendering processes on the volume data in order to generate various two-dimensional image data for displaying the volume data on the display 103.

[0036] Examples of the rendering processes performed by the image generation circuit 140 include a process of generating MPR image data from volume data using a cross-sectional reconstruction method (MPR: Multi Planer Reconstruction). Also, examples of the rendering processes performed by the image generation circuit 140 include a volume rendering (VR: Volume Rendering) process of generating two-dimensional image data reflecting three-dimensional information. The image generation circuit 140 is an example of an image generation unit.

[0037] The B-mode data and Doppler data are ultrasonic image data before the scan conversion process, and the data generated by the image generation circuit 140 is the ultrasonic image data for display after the scan conversion process. Note that the B-mode data and Doppler data are also called raw data.

[0038] The image memory 150 is a memory that stores various image data generated by the image generation circuit 140. The image memory 150 also stores the data generated by the signal processing circuit 130. The B-mode data and Doppler data stored in the image memory 150 can be called up by the operator, for example, after diagnosis, and become the ultrasonic image data for display via the image generation circuit 140. For example, the image memory 150 is realized by a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, or an optical disk.

[0039] The storage circuit 160 stores control programs for performing scanning (ultrasonic transmission and reception), image processing, and display processing, diagnostic information (for example, patient ID, doctor's findings, etc.), diagnostic protocols, and various data such as various body marks. The storage circuit 160 is also used for storing the data stored in the image memory 150 as needed. For example, the storage circuit 160 is realized by a semiconductor memory element such as a flash memory, a hard disk, or an optical disk.

[0040] The control circuit 170 controls the overall processing of the ultrasonic diagnostic apparatus 10. Specifically, based on various setting requests input from the operator via the input device 102, and various control programs and various data read from the memory circuit 160, the control circuit 170 controls the processing of the transmission / reception circuit 110, the beam former 120, the signal processing circuit 130, and the image generation circuit 140. Further, the control circuit 170 controls the display 103 to display an ultrasonic image based on the ultrasonic image data for display stored in the image memory 150. For example, the control circuit 170 controls the display 103 to display a B-mode image based on B-mode image data or a color image based on color image data. Further, the control circuit 170 controls the display 103 to display a color image superimposed on the B-mode image. The control circuit 170 is an example of a display control unit or a control unit. The control circuit 170 is realized by, for example, a processor. The ultrasonic image is an example of an image.

[0041] Further, the control circuit 170 controls the ultrasonic probe 101 via the transmission / reception circuit 110 to control the ultrasonic scanning.

[0042] The overall configuration of the ultrasonic diagnostic apparatus 10 according to the first embodiment has been described above. Here, an example of the processing executed by a conventional ultrasonic diagnostic apparatus will be described with reference to FIG. 2. FIG. 2 is a diagram for explaining an example of the processing executed by a conventional ultrasonic diagnostic apparatus.

[0043] As shown in FIG. 2, a conventional ultrasonic diagnostic apparatus transmits a first ultrasonic pulse (transmitted ultrasonic wave) 21 with a positive-pole leading and a second ultrasonic pulse 22 with a negative-pole leading obtained by inverting the polarity of the first ultrasonic pulse 21 to different transmission positions (transmission scanning lines). Then, the conventional ultrasonic diagnostic apparatus adds the signals at the same reception position obtained by parallel simultaneous reception. A specific example will be described below.

[0044] For example, as shown in FIG. 2, a conventional ultrasonic diagnostic apparatus transmits a first ultrasonic pulse 21 to each of transmission scan lines (1), (3), ···, (n - 3), and (n - 1). Here, "n" is a natural number and is an even number. Also, the conventional ultrasonic diagnostic apparatus transmits a second ultrasonic pulse 22 to each of transmission scan lines (2), (4), ···, (n - 2), and (n).

[0045] Then, as shown in FIG. 2 for example, the conventional ultrasonic diagnostic apparatus generates reflected wave data of a plurality of reception positions (reception scan lines) as reflected wave data based on the reflected wave derived from the first ultrasonic pulse 21 transmitted to the transmission scan line (1). Specifically, the conventional ultrasonic diagnostic apparatus generates eight reflected wave data 1_1 to 1_8 of eight reception scan lines (1) to (8) as reflected wave data based on the reflected wave derived from the first ultrasonic pulse 21 transmitted to the transmission scan line (1). Here, the reflected wave data d_k (d and k are natural numbers) is the reflected wave data of the reception scan line (k) based on the reflected wave derived from the ultrasonic pulse transmitted to the transmission scan line (d). Note that "d" and "k" are natural numbers.

[0046] Similarly for each of the other transmission scan lines (3), ···, (n - 1), the conventional ultrasonic diagnostic apparatus generates eight reflected wave data d_k based on the reflected wave derived from the first ultrasonic pulse 21. That is, the conventional ultrasonic diagnostic apparatus generates eight reflected wave data s_(4s - 3) to s_(4s + 4) of eight reception scan lines (4s - 3) to (4s + 4) as reflected wave data based on the reflected wave derived from the first ultrasonic pulse 21 transmitted to the transmission scan line (s). Here, "s" is a natural number and is an odd number.

[0047] In addition, as shown in FIG. 2 for example, a conventional ultrasonic diagnostic apparatus generates reflected wave data at a plurality of reception positions (reception scanning lines) as reflected wave data based on reflected waves derived from a second ultrasonic pulse 22 transmitted to a transmission scanning line (2). Specifically, the conventional ultrasonic diagnostic apparatus generates eight pieces of reflected wave data 2_5 to 2_12 of eight reception scanning lines (5) to (12) as reflected wave data based on reflected waves derived from the second ultrasonic pulse 22 transmitted to the transmission scanning line (2).

[0048] Similarly for each of the other transmission scanning lines (4), ···, (n), the conventional ultrasonic diagnostic apparatus generates eight pieces of reflected wave data d_k based on reflected waves derived from the second ultrasonic pulse 22. That is, the conventional ultrasonic diagnostic apparatus generates eight pieces of reflected wave data w_(4w - 3) to w_(4w + 4) of eight reception scanning lines (4w - 3) to (4w + 4) as reflected wave data based on reflected waves derived from the second ultrasonic pulse 22 transmitted to the transmission scanning line (w). Here, "w" is a natural number and is an even number.

[0049] Then, the conventional ultrasonic diagnostic apparatus adds two pieces of reflected wave data s_h, w_h at the same reception position. That is, the conventional ultrasonic diagnostic apparatus adds the reflected wave data w_h to the reflected wave data s_h to generate reflected wave data 25_h (THI signal 25_h) which is a non-linear signal with the fundamental wave component suppressed. Here, "h" is a natural number. For example, the conventional ultrasonic diagnostic apparatus adds the reflected wave data 2_5 to the reflected wave data 1_5 to generate the reflected wave data 25_5. In this way, every time two pieces of reflected wave data s_h, w_h are generated at one reception position, the conventional ultrasonic diagnostic apparatus generates the reflected wave data 25_h. Specifically, the conventional ultrasonic diagnostic apparatus generates (4n - 4) pieces of reflected wave data 25_5 to 25_p. However, "p" is 4n.

[0050] Here, among the two reflected wave data s_h and w_h at the same position, it is preferable that the component obtained by inverting the fundamental wave component included in one of the reflected wave data s_h coincides with the fundamental wave component included in the other reflected wave data w_h. This is because the fundamental wave component is suppressed by adding the other reflected wave data w_h to one of the reflected wave data s_h. However, since the position where the positive-polarity ultrasonic pulse is transmitted is different from the position where the negative-polarity ultrasonic pulse is transmitted, the component obtained by inverting the fundamental wave component included in one of the reflected wave data s_h may not coincide with the fundamental wave component included in the other reflected wave data w_h. In this case, the fundamental wave component remains.

[0051] Therefore, in order to suppress the fundamental wave component from remaining in the THI signal, the ultrasonic diagnostic apparatus 10 according to the first embodiment executes the following-described processing. FIG. 3 is a diagram for explaining an example of the processing executed by the ultrasonic diagnostic apparatus 10 according to the first embodiment.

[0052] As shown in FIG. 3, the ultrasonic probe 101 of the ultrasonic diagnostic apparatus 10 according to the first embodiment transmits the first ultrasonic pulse 21 to each of the transmission scan lines (1), (3), ···, (n - 3), and (n - 1) in the same manner as the conventional ultrasonic diagnostic apparatus described with reference to FIG. 2. Further, the ultrasonic probe 101 transmits the second ultrasonic pulse 22 to each of the transmission scan lines (2), (4), ···, (n - 2), and (n).

[0053] In this way, the ultrasonic probe 101 performs multiple times the operation of transmitting ultrasonic pulses with different polarities to different transmission positions of the subject P or the contrast agent administered to the subject P. For example, the ultrasonic probe 101 is an example of a transmission unit.

[0054] Then, the receiving circuit 112 of the ultrasonic diagnostic apparatus 10 performs parallel simultaneous reception. That is, the receiving circuit 112 simultaneously receives, through the ultrasonic probe 101 at a plurality of reception positions, as a plurality of reception beams, the reflected wave signals caused by the reflected waves from the first ultrasonic pulse 21 (ultrasonic beam) transmitted by the transmitting circuit 111 to the ultrasonic probe 101 with respect to the transmission scanning line (1). For example, the receiving circuit 112 generates reflected wave signals at a plurality of reception positions as the reflected wave signals (received signals) based on the reflected waves from the first ultrasonic pulse 21 transmitted to the transmission scanning line (1). Specifically, the receiving circuit 112 generates eight reflected wave signals 1_1 to 1_8 (not shown) of eight reception scanning lines (1) to (8) as the reflected wave signals based on the reflected waves from the first ultrasonic pulse 21 transmitted to the transmission scanning line (1). Here, the reflected wave signal d_k is the reflected wave signal of the reception scanning line (k) based on the reflected wave from the ultrasonic pulse transmitted to the transmission scanning line (d).

[0055] Similarly for each of the other transmission scanning lines (3), ···, (n - 1), the receiving circuit 112 generates eight reflected wave signals d_k based on the reflected waves from the first ultrasonic pulse 21. That is, the receiving circuit 112 generates eight reflected wave signals s_(4s - 3) to s_(4s + 4) (not shown) of eight reception scanning lines (4s - 3) to (4s + 4) as the reflected wave signals based on the reflected waves from the first ultrasonic pulse 21 transmitted to the transmission scanning line (s). Hereinafter, when explaining without distinguishing such reflected wave signals from the first ultrasonic pulse 21, the reflected wave signals from the first ultrasonic pulse 21 may be simply denoted as "reflected wave signal s".

[0056] In this way, the receiving circuit 112 generates m (= 4n) reflected wave signals s.

[0057] Further, the receiving circuit 112 generates reflected wave signals at a plurality of receiving positions as reflected wave signals based on reflected waves derived from the second ultrasonic pulse 22 transmitted to the transmission scanning line (2), for example. Specifically, the receiving circuit 112 generates eight reflected wave signals 2_5 to 2_12 (not shown) of eight receiving scanning lines (5) to (12) as reflected wave signals based on reflected waves derived from the second ultrasonic pulse 22 transmitted to the transmission scanning line (2).

[0058] Similarly for each of the other transmission scanning lines (4), ···, (n), the receiving circuit 112 generates eight reflected wave signals d_k based on reflected waves derived from the second ultrasonic pulse 22. That is, the receiving circuit 112 generates eight reflected wave signals w_(4w - 3) to w_(4w + 4) (not shown) of eight receiving scanning lines (4w - 3) to (4w + 4) as reflected wave signals based on reflected waves derived from the second ultrasonic pulse 22 transmitted to the transmission scanning line (w). Hereinafter, when explaining without distinguishing such reflected wave signals derived from the second ultrasonic pulse 22, the reflected wave signals derived from the second ultrasonic pulse 22 may be simply referred to as "reflected wave signal w".

[0059] In this way, the receiving circuit 112 generates m (= 4n) reflected wave signals w.

[0060] Then, the beamformer 120 of the ultrasonic diagnostic apparatus 10 uses the transmission aperture synthesis method using virtual sound sources (transmission aperture synthesis method using virtual sound sources) to generate m reflected wave data 30_1 to 30_m from the m reflected wave signals s generated by the receiving circuit 112, as shown in FIG. 3. That is, the beamformer 120 performs transmission aperture synthesis using virtual sound sources on the m reflected wave signals s generated by the receiving circuit 112 to generate m reflected wave data 30_1 to 30_m. Note that the reflected wave data 30_k is the reflected wave data of the receiving scanning line (k). The m reflected wave data 30_1 to 30_m are the reflected wave data used when generating one frame of B-mode image data and are the reflected wave data derived from the first ultrasonic pulse 21.

[0061] Here, the transmission aperture synthesis method using virtual sound sources, also known as the virtual sound source method, is a well-known technique. For example, the virtual sound source method is a technique described in Japanese Patent No. 3401199 (Patent Document 1), Japanese Patent Application Laid-Open No. 2009-240700 (Patent Document 5), Japanese Patent No. 6014643 (Patent Document 6), and the like. In the virtual sound source method, the transmission focus point (transmission convergence point) is regarded as a virtual sound source (virtual sound source). In the virtual sound source method, a sound field is formed such that transmission focus is applied not only at the transmission focus point but also at other points.

[0062] Also, the beamformer 120 uses the transmission aperture synthesis method using virtual sound sources to generate m reflected wave data 31_1 to 31_m from the m reflected wave signals w generated by the receiving circuit 112, as shown in FIG. 3. That is, the beamformer 120 performs transmission aperture synthesis using virtual sound sources on the m reflected wave signals w generated by the receiving circuit 112 to generate m reflected wave data 31_1 to 31_m. Note that the reflected wave data 31_k is the reflected wave data of the receiving scan line (k). The m reflected wave data 31_1 to 31_m are data used for generating one-frame B-mode image data and are reflected wave data derived from the second ultrasonic pulse 22.

[0063] That is, since the beamformer 120 uses the virtual sound source method, reception beamforming processing is performed on a plurality of reception signals obtained by transmitting a plurality of ultrasonic pulses having the same polarity. For example, the beamformer 120 is an example of a beamforming processing unit.

[0064] Further, the beamformer 120 corrects the shift generated by different transmission positions at which ultrasonic waves with different polarities are transmitted in the reception beamforming process. Here, the "shift" refers to, for example, the shift between the position of the non-linear signal obtained by pulse inversion and the transmission position of the first ultrasonic pulse 21 transmitted to obtain this non-linear signal, and the shift between the position of the non-linear signal obtained by pulse inversion and the transmission position of the second ultrasonic pulse 22 transmitted to obtain this non-linear signal. This shift also varies depending on the depth. This shift is also referred to as a positional shift. Further, the beamformer 120 corrects such a shift using a plurality of received signals obtained by transmitting a plurality of ultrasonic pulses by the virtual sound source method.

[0065] Then, the signal processing circuit 130 of the ultrasonic diagnostic apparatus 10 adds two pieces of reflected wave data 30_k and 31_k at the same reception position. That is, the signal processing circuit 130 adds the reflected wave data 31_k to the reflected wave data 30_k to generate reflected wave data 35_k (THI signal 35_k) in which the fundamental wave component is suppressed and the non-linear component is emphasized, as shown in FIG. 3. In this way, the signal processing circuit 130 generates m pieces of reflected wave data 35_1 to 35_m. Note that the reflected wave data 35_k is the reflected wave data of the reception scanning line (k). The m pieces of reflected wave data 35_1 to 35_m are the reflected wave data used when generating one-frame B-mode image data.

[0066] In this way, the signal processing circuit 130 extracts the reflected wave data 35_k by adding the reflected wave data 30_k and 31_k at the same reception position after reception beamforming. The reflected wave data 35_k is a non-linear signal. Further, the function of the signal processing circuit 130 to extract the reflected wave data 35_k is an example of an extraction unit.

[0067] Then, the signal processing circuit 130 generates B-mode data for one frame using the m reflected wave data 35_1 to 35_m. Then, the image generation circuit 140 generates B-mode image data for one frame from the B-mode data for one frame. Then, the control circuit 170 causes the display 103 to display a B-mode image based on the generated B-mode image data. The ultrasonic diagnostic apparatus 10 repeats such processing to display B-mode images one after another on the display 103, thereby displaying a B-mode moving image on the display 103.

[0068] Here, the m reflected wave data 30_1 to 30_m and the m reflected wave data 31_1 to 31_m are data generated by the virtual sound source method. Therefore, even if the transmission position where the first ultrasonic pulse 21 is transmitted is different from the transmission position where the second ultrasonic pulse 22 is transmitted, data without positional deviation can be obtained, and reflected wave data of only a non-linear signal with the fundamental wave component suppressed can be obtained. Thus, according to the ultrasonic diagnostic apparatus 10 according to the first embodiment, the image quality can be improved.

[0069] Also, as described above, the ultrasonic diagnostic apparatus 10 reduces the density of the transmission scanning lines and performs parallel simultaneous reception. Therefore, according to the ultrasonic diagnostic apparatus 10 according to the first embodiment, a decrease in the frame rate can be suppressed.

[0070] From the above, according to the ultrasonic diagnostic apparatus 10 according to the first embodiment, it is possible to improve the image quality of the B-mode image data while suppressing a decrease in the frame rate.

[0071] Here, an example of the problem of a conventional ultrasonic diagnostic apparatus will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram for explaining an example of the problem of a conventional ultrasonic diagnostic apparatus. FIG. 5 is an enlarged view of the region 40 in FIG. 4.

[0072] As shown in FIG. 4, the transmission beam transmitted from the transmission aperture 1 converges at the transmission focus point F1 on the transmission scanning line T1. On the other hand, in the shallower and deeper parts that are shallower than the transmission focus point F1 in the depth direction, the transmission beam spreads. However, in the reception beam forming, it is assumed that the transmission wavefront propagates as a plane wave. Therefore, at the transmission aperture 1 of a conventional ultrasonic diagnostic apparatus, the reflected wave signal (reflected wave data) generated by performing reception beam forming at the position Q0 on the reception scanning line R3 shown in FIG. 5 is actually the reflected wave signal (reflected wave data) at the position Q1 on the reception scanning line R3 shifted to the shallower side with respect to the position Q0.

[0073] Similarly, the transmission beam transmitted from the transmission aperture 2 converges at the transmission focus point F2 on the transmission scanning line T2, but in the shallower and deeper parts that are shallower than the transmission focus point F2 in the depth direction, the transmission beam spreads. For this reason, at the transmission aperture 2 of a conventional ultrasonic diagnostic apparatus, the reflected wave signal (reflected wave data) generated by performing reception beam forming at the position Q0 on the reception scanning line R3 shown in FIG. 5 is actually the reflected wave signal at the position Q2 on the reception scanning line R3 shifted to the shallower side with respect to the position Q0. For this reason, a conventional ultrasonic diagnostic apparatus that performs conventional pulse inversion adds the reflected wave signal at the position Q2 to the reflected wave signal at the position Q1 to generate the reflected wave signal at the position Q0. The reflected wave signal at the position Q0 generated in this way is generated by adding signals at positions different from the position Q0, so the fundamental wave component remains. For this reason, it is difficult for a conventional ultrasonic diagnostic apparatus to correctly extract only the non-linear signal.

[0074] To solve this problem, the ultrasonic diagnostic apparatus 10 according to the first embodiment uses the virtual sound source method as described above. The position Q0 at the transmission aperture 1 is shallower than the position P1 on the transmission scanning line T1 by F1Q0 - F1P1. Note that F1Q0 indicates the distance between the transmission focus point F1 and the position Q0. F1P1 indicates the distance between the transmission focus point F1 and the position P1. This is because there is a virtual point sound source at the transmission focus point F1, and it is the same as when ultrasonic waves propagate from the point sound source, so it is called the virtual sound source method described above. Specifically, in the reception beam forming at the conventional position Q0, the value obtained by adding OQ0 (where OQ0 indicates the distance between the point O and the position Q0) as the transmission distance and the distances from each channel to the position Q0 as the reception distances is used. In contrast, in the virtual sound source method, a signal with a distance obtained by adding F1Q0 - F1P1 to the total value for the transmission aperture 1 is used. In the virtual sound source method, a signal with a distance obtained by adding F2Q0 - F2P2 to the total value for the transmission aperture 2 is used. Note that F2Q0 indicates the distance between the transmission focus point F2 and the position Q0. F2P2 indicates the distance between the transmission focus point F2 and the position P2. This means that the transmission apertures 1 and 2 are combined, so it is a kind of transmission aperture synthesis method. This method can be extended to all transmission scanning lines (all transmission apertures). However, this method is effective only when there is an effective range of the transmission beam at the reception position. Therefore, the number of reflected wave signals (reflected wave data) for each transmission scan that can be added is small near the transmission focus, and the number of reflected wave signals (reflected wave data) for each transmission scan that can be added increases as the distance from the transmission focus point increases. That is, the number of data from different transmission positions added is small near the transmission focus, and the number of data from different transmission positions added increases as the distance from the transmission focus point increases.

[0075] FIG. 6 is a flowchart showing an example of the flow of processing executed by the ultrasonic diagnostic apparatus 10 according to the first embodiment. The processing shown in FIG. 6 is processing for generating reflected wave data with the fundamental wave component suppressed.

[0076] As shown in FIG. 6, the beamformer 120 performs transmission aperture synthesis using virtual sound sources on the m reflected wave signals s generated by the receiving circuit 112 to generate m reflected wave data 30_1 to 30_m (step S101).

[0077] The beamformer 120 performs transmission aperture synthesis using virtual sound sources on the m reflected wave signals w generated by the receiving circuit 112 to generate m reflected wave data 31_1 to 31_m (step S102).

[0078] The signal processing circuit 130 generates reflected wave data 35_k (THI signal 35_k) in which the fundamental wave component is suppressed and the non-linear component is emphasized by adding the reflected wave data 31_k to the reflected wave data 30_k (step S103), and ends the process shown in FIG. 6. In this way, the signal processing circuit 130 generates m reflected wave data 35_1 to 35_m.

[0079] The ultrasonic diagnostic apparatus 10 according to the first embodiment has been described above. According to the ultrasonic diagnostic apparatus 10 according to the first embodiment, as described above, it is possible to improve the image quality of the B-mode image data while suppressing a decrease in the frame rate.

[0080] (Modification of the First Embodiment) The ultrasonic diagnostic apparatus 10 according to a modification of the first embodiment will be described. For example, in the modification of the first embodiment, the above-mentioned deviation may be obtained in advance by actual measurement. Also, the beamformer 120 may obtain the above-mentioned deviation by calculating the above-mentioned deviation by simulation (for example, sound field simulation). And in the modification of the first embodiment, the beamformer 120 corrects the deviation obtained by actual measurement or simulation using a plurality of received signals obtained by transmitting a plurality of ultrasonic pulses in the same manner as in the first embodiment.

[0081] The ultrasonic diagnostic apparatus 10 according to the modification of the first embodiment has been described above. According to the ultrasonic diagnostic apparatus 10 according to the modification of the first embodiment, the same effects as those of the ultrasonic diagnostic apparatus 10 according to the first embodiment can be achieved.

[0082] In the above description, the term "processor" means, for example, a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), or a programmable logic device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor realizes its functions by reading out the program stored in the storage circuit 160 and executing the read program. Instead of storing the program in the storage circuit 160, the program may be directly incorporated into the circuit of the processor. In this case, the processor realizes its functions by reading out and executing the program incorporated in the circuit. Each processor in the present embodiment is not limited to being configured as a single circuit for each processor, and a plurality of independent circuits may be combined to form one processor to realize its functions. Further, a plurality of circuits in FIG. 1 may be integrated into one processor to realize its functions.

[0083] Incidentally, the control program may be provided by being recorded on a non-transitory computer-readable storage medium such as a CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk), etc. in a file in a form installable or executable on a computer. Further, this control program may be stored on a computer connected to a network such as the Internet and provided or distributed by being downloaded via the network. For example, this control program is composed of modules including the above-described respective processing functions. As actual hardware, a processor reads a program from a storage medium such as a ROM and executes it, whereby each module is loaded onto the main storage device and generated on the main storage device.

[0084] According to at least one of the embodiments or modifications described above, it is possible to improve the image quality of B-mode image data while suppressing a decrease in the frame rate.

[0085] Although several embodiments have been described, these embodiments are presented as examples 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 gist 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 equivalent scope thereof.

Explanation of Reference Numerals

[0086] 10 Ultrasonic diagnostic apparatus 101 Ultrasonic probe 120 Beamformer 130 Signal processing circuit

Claims

1. A transmitting unit that transmits a plurality of ultrasonic pulses having positive and negative polarities and different transmission positions with respect to a subject or a contrast agent administered to the subject; By performing reception beamforming processing on the reception signal of the positive polarity obtained by transmitting the ultrasonic pulse of the positive polarity, first reception data at a predetermined reception position is generated, and the negative polarity ultrasonic pulse is transmitted. A beamforming processing unit that generates second reception data at the predetermined reception position by performing reception beamforming processing on the obtained reception signal of the negative polarity; An extraction unit that extracts a non-linear signal by performing pulse inversion processing based on the first reception data and the second reception data after the reception beamforming processing; comprising The beamforming processing unit corrects the reception positions of the reception signals of the positive and negative polarities by performing transmission aperture synthesis using a virtual sound source, and generates the first reception data and the second reception data. An ultrasonic diagnostic apparatus.

2. The ultrasonic diagnostic apparatus according to claim 1, wherein the extraction unit extracts the non-linear signal for the reception position by adding the first reception data and the second reception data at the same reception position.

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