JP2016107080A - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate information for generating an elastography image within the time required for the minimum number of a transmission sequence, in an ultrasonic probe and an ultrasonic diagnostic apparatus.SOLUTION: An ultrasonic probe includes: at least one first oscillator which functions as an oscillator only for vibration which performs vibration by acoustic radiation pressure in an elastography mode; and a plurality of second oscillators which function as oscillators only for detection which detects shear waves generated by the vibration in the elastography mode.SELECTED DRAWING: Figure 4

Description

  The present embodiment as one aspect of the present invention relates to an ultrasound probe and an ultrasound diagnostic apparatus that transmit and receive ultrasound.

  As a diagnostic method for breast cancer, cirrhosis, and vascular disorder, there is a method (elastography) that quantifies and visualizes the hardness of a tissue such as an in vivo organ from an ultrasonic echo signal instead of a doctor's palpation. . Elastography is roughly classified into strain detection type elastography and acoustic irradiation type elastography. Strain detection type elastography compresses and releases the body surface from outside the body, and determines the relative hardness with surrounding tissues from the deformation (distortion) of the organ caused by the movement of the organ such as the heart that moves spontaneously. Quantified and visualized.

  The acoustic irradiation type elastography transmits an ultrasonic wave for excitation having a relatively large energy that generates an acoustic radiation pressure from outside the body to a tissue such as an organ in a living body. The acoustic irradiation type elastography quantifies and visualizes the hardness (elastic modulus) of the tissue by calculating the sound velocity of the shear wave generated as a transverse wave around the tissue due to the displacement (vibration) of the tissue. .

  Among these, in the acoustic irradiation type elastography, first, an excitation position (excitation beam) is formed by forming an ultrasonic beam (excitation beam) for excitation using an ultrasonic transducer unit for B mode of an ultrasonic probe. The tissue present in the body is displaced. Subsequently, the ultrasonic wave for detection (detection beam) is formed at a detection position around the excitation position using the same ultrasonic transducer unit, so that the wave front of the shear wave caused by the tissue displacement is generated in the tissue. It is detected by the Doppler method or the like.

  In acoustic irradiation type elastography, the arrival time from the transmission time of the excitation beam to the arrival time of the wavefront detection position of the shear wave is measured, so that the shear wave from the excitation position to the detection position is measured. The speed of sound is calculated. Further, the average sound speed of the shear wave from the vibration position to the plurality of detection positions is calculated, and the relative value of each sound speed with respect to the average sound speed is calculated as information indicating the hardness of the tissue.

JP 2007-44231 A Japanese Patent Application Laid-Open No. 2014-260

  Since the living body is viscous, the wave front of the shear wave becomes dull as it moves away from the excitation position. Thus, according to the conventional technique, the detection accuracy of the shear wave at the detection position away from the excitation position is lowered, so that the uniformity of the image quality of the entire elastography image is lowered.

  Therefore, in the conventional technique, a display range is divided into a plurality of blocks, and a plurality of detection positions (blocks) with high shear wave detection accuracy are connected to generate a single elastography image. For this purpose, it is necessary to perform a plurality of transmission sequences (a combination of a series of excitation pulse transmissions and a series of detection pulse transmissions) corresponding to a plurality of detection positions. The frame rate of the elastography image or the like is lowered by that amount. On the other hand, if the number of detection positions is reduced in order to maintain the frame rate, the uniformity of the image quality of the elastography image is lowered.

  Further, when the frame rate of an elastography image or the like is lowered, real-time property is impaired, and an adverse effect that artifacts are generated in the image due to the movement of the tissue in the living body occurs.

  The problem to be solved by the present invention is to provide an ultrasonic probe and an ultrasonic diagnostic apparatus capable of generating information for generating an elastography image in a time required for a minimum number of transmission sequences.

  The ultrasonic probe according to the present embodiment includes at least one first vibrator that functions as a vibrator dedicated to vibration that performs vibration by acoustic radiation pressure in the elastography mode, and the vibration in the elastography mode. A plurality of second vibrators functioning as a vibrator exclusively for detection for detecting the generated shear wave.

Schematic which shows the structure of the ultrasonic probe and ultrasonic diagnostic apparatus which concern on this embodiment. The perspective view which shows the external appearance structure in the conventional ultrasonic probe. The figure which shows the structure by the side of the acoustic radiation surface in the conventional ultrasonic probe. The perspective view which shows the external appearance structure in a 1st ultrasonic probe among the ultrasonic probes which concern on this embodiment. The figure which shows the structure by the side of the acoustic radiation surface in a 1st ultrasonic probe. The block diagram which shows the control system of the ultrasonic probe which concerns on this embodiment. FIG. 2 is a structural diagram showing a control system of an ultrasonic probe according to the present embodiment. The figure for demonstrating the calculation method of the sound speed of a shear wave in the case of using the conventional ultrasonic probe shown in FIG.2 and FIG.3. The figure which shows an example of the time waveform of the shear wave in a detection position. The figure for demonstrating the calculation method of the sound speed of a shear wave in the case of using the 1st ultrasonic probe shown in FIG.4 and FIG.5. FIG. 3 is an external view showing a structure of a head part. The perspective view which shows the external appearance structure in a 2nd ultrasonic probe among the ultrasonic probes which concern on this embodiment. The figure which shows the structure by the side of the acoustic radiation surface in a 2nd ultrasonic probe. The figure for demonstrating the calculation method of the sound speed of a shear wave in the case of using the 2nd ultrasonic probe shown in FIG.12 and FIG.13. The perspective view which shows the external appearance structure in a 3rd ultrasonic probe among the ultrasonic probes which concern on this embodiment. The figure which shows the structure by the side of the acoustic radiation surface in a 3rd ultrasonic probe. The figure for demonstrating the calculation method of the sound speed of a shear wave in the case of using the 3rd ultrasonic probe shown in FIG.15 and FIG.16. The perspective view which shows the external appearance structure in a 4th ultrasonic probe among the ultrasonic probes which concern on this embodiment. The figure which shows the structure by the side of the acoustic radiation surface in a 4th ultrasonic probe. The figure for demonstrating the calculation method of the sound speed of a shear wave in the case of using the 4th ultrasonic probe shown in FIG.18 and FIG.19. The figure which shows the structure by the side of the acoustic radiation surface in a 5th ultrasonic probe. The perspective view which shows the external appearance structure in the 6th ultrasonic probe among the ultrasonic probes which concern on this embodiment. The figure which shows the structure by the side of the acoustic radiation surface in a 6th ultrasonic probe. The perspective view which shows the external appearance structure in the 7th ultrasonic probe among the ultrasonic probes which concern on this embodiment.

  An ultrasonic probe and an ultrasonic diagnostic apparatus according to this embodiment will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram illustrating a configuration of an ultrasonic probe and an ultrasonic diagnostic apparatus according to the present embodiment.

  FIG. 1 shows an ultrasonic diagnostic apparatus 10 according to this embodiment. The ultrasonic diagnostic apparatus 10 includes an ultrasonic probe 11 and an apparatus main body 12.

  The ultrasonic probe 11 is detachably connected to the apparatus main body 12. The ultrasonic probe 11 includes an ultrasonic transducer unit 20 for excitation (push) in the elastography (acoustic irradiation type elastography) mode (hereinafter referred to as “vibration unit exclusively for excitation”) 20 and an elastography mode. And an ultrasonic transducer unit (hereinafter referred to as “dedicated transducer unit for detection”) 30. The transducer unit 30 dedicated to detection is also used for transmission / reception of ultrasonic waves in the B mode and the Doppler mode.

  Here, structural examples in the case where the ultrasonic probe 11 is provided with a single vibrator unit 20 for excitation are shown in FIGS. 4 and 5, FIGS. 12 and 13, FIGS. 18 and 19, and FIG. 21. And show. Further, FIGS. 15 and 16 show structural examples in the case where the ultrasonic probe 11 is provided with two vibrator units 20 (201, 202) dedicated to vibration. When one direction of the acoustic radiation surface of the ultrasonic probe 11 is defined as a first direction (azimuth direction) and the other direction is defined as a second direction (elevation direction), the transducer unit 30 dedicated to detection is dedicated to excitation. Of the vibrator unit 20 along the second direction.

  FIG. 2 is a perspective view showing an external structure of a conventional ultrasonic probe. FIG. 3 is a diagram showing a structure on the acoustic radiation surface side in a conventional ultrasonic probe.

  FIG. 2 shows an external structure of a conventional ultrasonic probe 911. A conventional ultrasonic probe 911 includes one ultrasonic transducer unit (hereinafter referred to as “vibrator unit for both excitation and detection”) 930 that is used for excitation and detection in an elastography mode, and an apparatus. A cable (not shown) for transmitting signals to and from the main body. The vibrator unit 930 for both excitation and detection is also used for transmitting and receiving ultrasonic waves in the B mode and the Doppler mode.

  As shown in FIG. 3, the vibrator unit 930 for both excitation and detection includes a plurality of vibrators 931s along the first direction (azimuth direction). The vibrator unit 930 for both excitation and detection also includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIGS.

  Each of the plurality of vibrators 931s transmits an ultrasonic wave for exciting relatively high energy (sound pressure) that generates an acoustic radiation pressure, and ultrasonic waves for detecting relatively smaller energy than the ultrasonic wave for exciting. Send and receive.

  In addition to the elastography mode, the plurality of vibrators 931s are also used in the B mode and the like. In the B mode, a still image can be obtained by sequentially switching the position of the ultrasonic beam (scanning line) for the B mode in the first direction. The plurality of vibrators 931s can also obtain a moving image by obtaining still images in a plurality of frames in the B mode.

  FIG. 4 is a perspective view showing an external structure of the first ultrasonic probe among the ultrasonic probes 11 according to the present embodiment. FIG. 5 is a diagram showing the structure on the acoustic radiation surface side of the first ultrasonic probe.

  FIG. 4 shows an external structure of the first ultrasonic probe 11A among the ultrasonic probes 11 according to the present embodiment. The first ultrasonic probe 11A includes one transducer unit 20 dedicated to excitation, one transducer unit 30 dedicated to detection, a head portion (exterior component) 40, and the apparatus main body 12 (see FIG. 1). And a cable (not shown) for transmitting signals to and from the figure. The transducer unit 30 for detection is provided on one side along the second direction of the transducer unit 20 for excitation.

  The vibrator-dedicated vibrator unit 20 includes at least one first vibrator that functions as a vibrator dedicated to vibration that performs vibration using acoustic radiation pressure in the elastography mode. In the example shown in FIG. 5, the vibrator dedicated vibrator unit 20 includes one large-diameter first vibrator 21. Hereinafter, the large-diameter first vibrator is referred to as a “large-diameter vibrator”. The large-diameter vibrator 21 has a longer width in the first direction than each vibrator provided in the vibrator unit 30 dedicated to detection, and the width in the second direction is not limited.

  The large-diameter vibrator 21 transmits ultrasonic waves for excitation with relatively large energy that generate acoustic radiation pressure. The large-diameter vibrator 21 is a plane wave Fp having a width in the first direction (not shown) through an acoustic lens (not shown) that focuses the excitation ultrasonic waves transmitted from the large-diameter vibrator 21 in the second direction. 10) and has a certain width in the first direction. The vibrator unit 20 dedicated for excitation includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIGS. 4 and 5.

  On the other hand, the transducer unit 30 dedicated to detection includes a plurality of second transducers that function as transducers dedicated to detection that detect shear waves generated by vibration in the elastography mode. In the example shown in FIG. 5, the transducer unit 30 dedicated to detection includes a plurality of second transducers 31 s along the first direction. Each of the multiple second transducers 31 s transmits and receives ultrasonic waves for detection with relatively lower energy than the ultrasonic waves for excitation. The transducer unit 30 dedicated to detection also includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIGS. 4 and 5.

  In addition to the elastography mode, the plurality of second vibrators 31s are used in the B mode and the like. In the B mode, a still image can be obtained by sequentially switching the position of the ultrasonic beam (scanning line) for the B mode in the first direction in the first direction. The plurality of second vibrators 31s can also obtain moving images by obtaining still images in a plurality of frames in the B mode.

  Returning to the description of FIG. 1, the apparatus main body 12 includes a processing circuit 51, a storage circuit 52, an input circuit 53, a display 54, a transmission / reception unit (transmission / reception circuit) 55, a waveform analysis unit (waveform analysis circuit) 56, and hardness estimation. Part (hardness estimation circuit) 57 is provided. The apparatus main body 12 shown in FIG. 1 shows only the configuration necessary for performing acoustic irradiation type elastography, but functions provided in a general ultrasonic diagnostic apparatus such as a B-mode image and a Doppler image are provided. A configuration for generating and displaying may also be provided. Further, the hardness estimation unit 57 may be realized as a function by the processing circuit 51 executing a program.

  The processing circuit 51 includes a CPU (central processing unit) and a memory. The processing circuit 51 comprehensively controls each unit of the apparatus main body 12. The processing circuit 51 receives the output of the transmission / reception unit 55 and controls the waveform analysis unit 56 and the hardness estimation unit 57 that perform waveform analysis to generate information indicating the hardness of a tissue such as an organ in a living body. it can.

  The processing circuit 51 means a processing circuit such as a dedicated or general-purpose CPU (central processing unit) or MPU (micro processor unit), an application specific integrated circuit (ASIC), and a programmable logic device. To do. Examples of the programmable logic device include a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). Circuit. The processing circuit 51 reads and executes a program stored in the storage circuit 52 or directly incorporated in the processing circuit 51.

  The processing circuit 51 may be configured by a single circuit or may be configured by combining a plurality of independent circuits. In the latter case, the storage circuit 52 that stores the program may be provided individually for each circuit, or one storage circuit 52 may store a program corresponding to the functions of a plurality of circuits.

  The storage circuit 52 is a recording medium such as a magnetic disk (hard disk or the like), an optical disk (CD-ROM, DVD, or the like), a semiconductor memory, or the like, and a device that reads information recorded on these media. The storage circuit 52 stores transmission / reception conditions, a predetermined scan sequence, a control program for executing image generation and display processing, various signal data and image data, and other data. Data in the memory circuit 52 can be transferred to an external device (not shown).

  The input circuit 53 includes various switches, buttons, a trackball, a mouse, and a keyboard for taking various instructions, conditions, a region of interest (ROI) setting instruction, various image quality condition setting instructions, and the like from the operator into the apparatus main body 12. Is a circuit for inputting a signal from the above. Here, the input device itself is also included in the input circuit 53. When the input device is operated by the operator, the input circuit 53 generates an input signal corresponding to the operation and outputs it to the processing circuit 51. The apparatus main body 12 may include a touch panel in which an input device is configured integrally with the display 54.

  The display 54 displays the elastography image generated by the hardness estimation unit 57 according to the control signal from the processing circuit 51. The display 54 is a display device such as a liquid crystal display panel, a plasma display panel, and an organic EL panel.

  The transmission / reception unit 55 controls transmission of ultrasonic waves for excitation in the ultrasonic probe 11. The transmission / reception unit 55 includes an excitation waveform generation unit 551, an excitation transmission unit 552, and a frequency setting unit 553. The vibration transmitting unit 552 transmits a transmission signal based on the waveform generated by the vibration waveform generating unit 551 to the vibration-dedicated transducer unit 20 under the control of the processing circuit 51.

  The transmission signal from the vibration transmitting unit 552 is converted into an ultrasonic signal and transmitted by the large-diameter vibrator 21 (shown in FIG. 5) of the vibrator unit 20 dedicated for vibration. Thereby, a vibration surface Fp (shown in FIG. 10) is formed from the vibrator unit 20 dedicated to vibration toward the tissue. The transmission start time and transmission end time of the ultrasonic waves for vibration are set by the frequency setting unit 553. Here, the frequency indicates a repetition frequency of transmission of ultrasonic waves for vibration.

  The transmission / reception unit 55 controls transmission / reception of ultrasonic waves for detection in the ultrasonic probe 11. The transmission / reception unit 55 includes a detection waveform generation unit 554, a detection transmission unit 555, a detection beam calculation unit 556, and a detection unit 557. Under the control of the processing circuit 51, the detection transmission unit 555 transmits detection beams Ft1 and Ft2 (shown in FIG. 10) based on the waveform generated by the detection waveform generation unit 554 after transmission of the ultrasonic waves for excitation. A transmission signal that is electronically focused (transmission delay time and / or reception delay time) in the first direction so as to be formed is transmitted to the transducer unit 30 dedicated to detection.

  The transmission signal from the detection transmission unit 555 is converted into an ultrasonic signal and transmitted by a plurality of second transducers 31s (shown in FIG. 5) of the transducer unit 30 dedicated to detection. Accordingly, detection beams Ft1 and Ft2 (shown in FIG. 10) focused in the second direction by the acoustic lens 23 are transmitted and received from the transducer unit 30 dedicated to detection.

  In addition, the plurality of second transducers 31s of the transducer unit 30 dedicated to detection receive an echo signal caused by a shear wave W (shown in FIG. 10) propagating in the second direction due to the displacement of the tissue, and convert it into an electrical signal. Convert. The transducer unit 30 dedicated to detection sends an electric signal to the detection beam calculation unit 556. The output of the detection beam calculation unit 556 is subjected to signal processing such as envelope detection, log compression, bandpass filter processing, gain control, and the like in the detection unit 557, and then the waveform analysis unit 56 receives a change in tissue due to shear wave propagation. Is output as a signal indicating.

  The waveform analysis unit 56 analyzes the shear wave based on the signal input from the detection unit 557 of the transmission / reception unit 55. As an analysis regarding the shear wave, for example, an operation for detecting a peak from a time waveform of the shear wave (corresponding to the graph shown in FIG. 9) and measuring a time when the peak occurs (corresponding to “t” shown in FIG. 9) can be given. It is done. The output of the waveform analysis unit 56 is output to the hardness estimation unit 57 as a signal indicating the detection position of the shear wave and the analysis result. This analysis result is, for example, a signal indicating the time when the displacement of the tissue due to the shear wave becomes a peak.

  The hardness estimation unit 57 calculates the sound speed of the shear wave for each detection position based on the signal input from the waveform analysis unit 56, and calculates the average sound speed at a plurality of sound speeds at the plurality of detection positions. The hardness estimation unit 57 estimates the relative value of each sound speed with respect to the average sound speed as the tissue hardness (elastic modulus). The hardness estimation unit 57 converts a signal indicating tissue hardness into an image signal, and expresses attribute information (hue information, hue information) according to the numerical value indicating the tissue hardness and the numerical value indicating the tissue hardness. An elastography image showing the distribution of lightness information and saturation information (including at least one piece of information) is displayed on the display 54.

  In addition, the hardness estimation unit 57 can superimpose an elastography image on the B mode image in the B mode that is alternately performed with the elastography mode, and can display the superimposed image on the display 54. Furthermore, the hardness estimation unit 57 can also display a plurality of frames of elastography images on the display 54.

  FIG. 6 is a block diagram showing a control system of the ultrasonic probe according to the present embodiment. FIG. 7 is a structural diagram showing a control system of the ultrasonic probe according to the present embodiment.

  6 and 7 show the first ultrasonic probe 11A of the ultrasonic diagnostic apparatus 10 and the apparatus main body 12. FIG. In order to switch the timing of transmission of ultrasonic waves for excitation and transmission / reception of ultrasonic waves for detection, the transducer units 20 and 30 of the ultrasonic probe 11A are connected in parallel via a high-voltage switch (HV-SW) circuit. Connected. The HV-SW circuit is driven by the transmission / reception unit 55 of the apparatus main body 12. The processing circuit 51 of the apparatus main body 12 selectively controls ON / OFF of the HV-SW circuit. As shown in FIG. 7, the HV-SW circuit is built in the handle portion of the ultrasonic probe 11A.

  Subsequently, the calculation method of the sound velocity of the shear wave using the conventional ultrasonic probe 911 (shown in FIGS. 2 and 3) and the shear using the first ultrasonic probe 11A (shown in FIGS. 4 and 5). The difference from the calculation method of the wave sound speed will be described.

  FIG. 8 is a diagram for explaining a method for calculating the sound velocity of the shear wave when the conventional ultrasonic probe 911 shown in FIGS. 2 and 3 is used.

  FIG. 8 is a cross-sectional view of a conventional ultrasonic probe 911 in two orthogonal directions. The conventional ultrasonic probe 911 is provided with a vibrator unit 930 for both excitation and detection. The vibrator unit 930 for both excitation and detection includes a plurality of vibrators 931s along the first direction, a backing 932, and an acoustic lens 933.

  The case where the wavefront of a shear wave is detected at two detection positions H1 and H2 along the first direction will be described with reference to FIG.

  First, the plurality of vibrators 931s of the vibrator unit 930 for both vibration and detection use an ultrasonic pulse for excitation (excitation pulse) that is electronically focused in the first direction so as to be focused at the excitation position G1. Send. The excitation pulse is focused on the excitation position G1 by the acoustic lens 933 that focuses in the second direction. Thereby, the vibrator unit 930 for both excitation and detection forms an ultrasonic beam (excitation beam) Bp1 for excitation at the excitation position G1. Further, by repeatedly transmitting a series of excitation pulses from the plurality of transducers 931s, the transducer unit 930 for both excitation and detection repeatedly forms the excitation beam Bp1 with respect to the excitation position G1.

  When the excitation beam Bp1 is repeatedly formed with respect to the excitation position G1, shear waves are generated due to the displacement of the tissue existing at the excitation position G1. Here, the shear wave propagating in the first direction due to the excitation beam Bp1 is defined as V1.

  Subsequently, after repeated formation of the vibration beam Bp1 with respect to the vibration position G1, the plurality of vibrators 931s of the vibrator unit 930 for both vibration and detection use the preset detection positions H1 (excitation positions in the first direction). An ultrasonic pulse (detection pulse) for detection that is electronically focused in the first direction so as to be focused on (around G1) is transmitted and received. The detection pulse is focused on the detection position H1 by the acoustic lens 933 that is focused in the second direction. Accordingly, the vibrator unit 930 for both excitation and detection forms a detection ultrasonic beam (detection beam) Bt1 with respect to the detection position H1. In addition, by repeatedly transmitting and receiving a series of detection pulses from the plurality of transducers 931s, the transducer unit 930 for both excitation and detection repeatedly forms the detection beam Bt1 with respect to the detection position H1.

  When the detection beam Bt1 is repeatedly formed at the detection position H1, the shear wave V1 propagating in the first direction is detected. Note that the electronic focus in the first direction for forming the detection beam Bt1 is based on the transmission delay time and / or the reception delay time.

  Subsequently, after repeatedly forming the detection beam Bt1 with respect to the detection position H1, the vibrator unit 930 for both excitation and detection repeatedly forms the excitation beam Bp2 with respect to the excitation position G2. When the excitation beam Bp2 is repeatedly formed with respect to the excitation position G2, shear waves are generated due to the displacement of the tissue existing at the excitation position G2. Here, the shear wave propagating in the first direction due to the excitation beam Bp2 is defined as V2.

  Subsequently, after repeated formation of the vibration beam Bp2 with respect to the vibration position G2, the vibrator unit 930 for both vibration and detection repeatedly forms the detection beam Bt2 at the detection position H2. When the detection beam Bt2 is repeatedly formed with respect to the detection position H2, the shear wave V2 propagating in the first direction is detected. The electronic focus in the first direction for forming the detection beam Bt2 is based on the transmission delay time and / or the reception delay time.

  When the wave head of the shear wave V1 generated by the excitation beam Bp1 is detected at the detection position H1 and the arrival time of the shear wave V1 is measured, the sound velocity of the shear wave V1 at the detection position H1 is “t” by the tissue Doppler method or the like. / D ". Here, “t” is the arrival time (time difference) from the transmission time of the excitation beam Bp1 to the arrival time of the wave wave detection position H1 of the shear wave V1. “D” is the distance from the vibration position G1 to the detection position H1. An example of the time waveform of the shear wave at the detection position H1 is shown in FIG. Further, after calculating the sound speed of the shear wave V1 at the detection position H1, the sound speed of the shear wave V2 generated by the excitation beam Bp2 at the detection position H2 is calculated in the same manner. Further, the average sound speed at the two detection positions H1 and H2 is calculated.

  As described above, the conventional ultrasonic probe 911 detects the wave fronts of the shear waves V1 and V2 propagating in the first direction at the two detection positions H1 and H2 along the first direction. Therefore, when measuring the arrival times of the wave fronts of the shear waves at the two detection positions H1 and H2 along the first direction using the conventional ultrasonic probe 911, transmission of a series of excitation pulses (repetitive transmission) ) And a series of detection pulse transmissions (repetitive transmissions) require a time for performing a transmission sequence twice.

  When the arrival times of the shear wave fronts are measured at three or more detection positions H1, H2,... Along the first direction, time is required for performing the transmission sequence by the number of detection positions. .

  FIG. 10 is a diagram for explaining a method for calculating the sound velocity of the shear wave when the first ultrasonic probe 11A shown in FIGS. 4 and 5 is used.

  FIG. 10 is a cross-sectional view of the first ultrasonic probe 11A in two orthogonal directions. The first ultrasonic probe 11 </ b> A includes transducer units 20 and 30 and a head unit 40. The vibrator unit 20 dedicated for excitation includes a large-diameter vibrator 21, a backing 22, and an acoustic lens 23. The detection-dedicated vibrator unit 30 includes a plurality of second vibrators 31s along the first direction, a backing 32, and an acoustic lens 33.

  As a material for the acoustic lenses 23 and 33, generally, a resin, for example, silicone rubber, having an acoustic impedance close to that of the head portion 40 and a different sound speed is selected. However, the acoustic lenses 23 and 33 can be formed of a rubber member that is in close contact with the recess formed on the inner surface of the head portion 40, or an adhesive for bonding the vibrator units 20 and 30 to the head portion 40. It can also be formed.

  The head unit 40 has a shape that matches the shape of the transducer units 20 and 30 in order to fix the transducer units 20 and 30 to the main body of the first ultrasonic probe 11A. The head part 40 has a structure as shown in FIG. 11, and the contact surface with the body surface of a living body is smooth. As the material of the head portion 40, a resin having a good acoustic matching with the body surface, for example, polymethylpentene is selected.

  A case where the wavefront of a shear wave is detected at two detection positions J1 and J2 along the first direction will be described with reference to FIG.

  First, the large-diameter vibrator 21 of the vibrator unit 20 dedicated for vibration transmits a vibration pulse. The excitation pulse is focused on the excitation region I (a set of a plurality of excitation positions extending in the first direction) by the acoustic lens 23 that is focused in the second direction. Thereby, the vibrator unit 20 dedicated for vibration forms an ultrasonic surface (vibration surface) Fp for vibration in the vibration region I. Further, a series of excitation pulses are repeatedly transmitted from the large-diameter vibrator 21, so that the vibrator unit 20 dedicated to vibration repeatedly forms the vibration surface Fp in the vibration region I.

  When the vibration surface Fp is repeatedly formed with respect to the vibration region I, shear waves are generated due to the displacement of the tissue existing in the vibration region I. Here, the shear wave propagating in the second direction due to the excitation surface Fp is defined as W.

  The excitation surface Fp formed by the transducer unit 20 dedicated for excitation is focused by the acoustic lens 23 in the second direction, but has no focusing effect in the first direction, and therefore maintains a substantially planar wavefront. . A linear excitation region I extending in the first direction at a certain depth is formed, and the shear wave W generated by the displacement of the tissue existing in the excitation region I propagates in the second direction.

  Subsequently, after repeated formation of the vibration surface Fp for the vibration region I, the plurality of second vibrators 31s of the transducer unit 30 dedicated for detection are located at the detection position J1 (around the vibration region I in the second direction). A detection pulse electronically focused in the first direction so as to be focused is transmitted and received. The detection pulse is focused at the detection position J1 by the acoustic lens 33 that is focused in the second direction. As a result, the transducer unit 30 dedicated to detection forms a detection beam Ft1 with respect to the detection position J1. Further, a series of detection pulses are repeatedly transmitted and received from the plurality of second transducers 31s, so that the transducer unit 30 dedicated to detection repeatedly forms the detection beam Ft1 at the detection position J1.

  When the detection beam Ft1 is repeatedly formed with respect to the detection position J1, the shear wave W propagating in the second direction is detected. Note that the electronic focus in the first direction for forming the detection beam Ft1 is based on the transmission delay time and / or the reception delay time.

  In addition, after the formation of the excitation surface Fp for the excitation region I, in parallel (simultaneously) with the repeated formation of the detection beam Ft1 for the detection position J1, the detection-dedicated transducer unit 30 detects the detection position J2. The beam Ft2 is repeatedly formed. When the detection beam Ft2 is repeatedly formed with respect to the detection position J2, the shear wave W propagating in the second direction is detected. The electronic focus in the first direction for forming the detection beam Ft2 is based on the transmission delay time and / or the reception delay time.

  When the wave front of the shear wave W generated by the vibration surface Fp is detected at the detection position J1 and the arrival time of the shear wave W is measured, the sound velocity of the shear wave W at the detection position J1 is calculated by a tissue Doppler method or the like. . In parallel with the calculation of the sound speed of the shear wave W at the detection position J1, the sound speed of the shear wave W generated by the vibration surface Fp at the detection position J2 is calculated in the same manner. Also, the average sound speed at the two detection positions J1 and J2 is calculated.

  As described above, in the first ultrasonic probe 11A, the wavefronts of the shear waves W propagating in the second direction orthogonal to each other are detected at the two detection positions J1 and J2 along the first direction. Therefore, when the arrival times of the fronts of the shear waves W are respectively measured at the two detection positions J1 and J2 along the first direction using the first ultrasonic probe 11A, a series of excitation pulses are transmitted. One detection is required, and the detection operations at the two detection positions J1 and J2 are performed in parallel. Therefore, in the first ultrasonic probe 11A, even when the arrival times of the wave fronts of the shear waves W are measured at the two detection positions J1 and J2, it is sufficient if there is enough time to perform one transmission sequence. It is.

  The first ultrasonic probe 11A performs one transmission sequence even when the arrival times of the shear wave fronts are measured at three or more detection positions J1, J2,... Along the first direction. Only one time is enough. Therefore, according to the first ultrasonic probe 11A, the frame rate of the elastography image and the frame rate of the B mode image in the B mode performed alternately with the elastography mode are improved.

  Furthermore, as shown in FIG. 8, when the conventional ultrasonic probe 911 is used, the interval between the excitation position G and the detection position H1 is different from the interval between the excitation position G and the detection position H2. At the detection position H2 where the interval is large, there is a problem that the shear wave V becomes dull due to propagation. In that case, since the detection accuracy of the wavefront of the shear wave V is lowered, the uniformity of the image quality of the entire elastography image is lowered. On the other hand, as shown in FIG. 10, when the first ultrasonic probe 11A is used, the interval (shortest distance) D between the vibration region I and the plurality of detection positions J1, J2 is a constant value. Therefore, when the first ultrasonic probe 11A is used, the uniformity of the image quality of the entire elastography image is improved.

  Here, the B-mode image is transmitted from the plurality of second transducers 31s of the transducer unit 30 dedicated to detection before and after the formation of the excitation surface Fp and the formation of the detection beams Ft1 and Ft2. It is generated based on ultrasonic waves for mode.

  Further, according to the conventional ultrasonic probe 911 shown in FIG. 8, the repetition frequency of a series of excitation pulses is limited by the frequency characteristics of the vibrator unit 930 for both excitation and detection. On the other hand, according to the first ultrasonic probe 11 </ b> A shown in FIG. 10, the vibrator-dedicated transducer unit 20 that transmits the excitation pulse independently from the transducer unit 30 dedicated to detection is provided. Therefore, as the large-diameter vibrator 21 provided in the vibrator-dedicated vibrator unit 20, one having an optimal frequency characteristic for effectively generating acoustic radiation pressure or one capable of outputting an optimal sound is selected. Is possible.

  In the ultrasonic probe 11, the case where the transducer unit 30 dedicated to detection has a 1D structure including a plurality of second transducers 31s along the first direction will be described as an example. However, the transducer unit 30 dedicated to detection may have a 2D structure including a plurality of transducers along the first direction and the second direction. In this case, the acoustic lens 33 is not required for the transducer unit 30 for detection, and electronic focusing is performed not only in the first direction but also in the second direction.

(Second ultrasonic probe)
FIG. 12 is a perspective view showing an external structure of the second ultrasonic probe among the ultrasonic probes 11 according to the present embodiment. FIG. 13 is a diagram showing a structure on the acoustic radiation surface side in the second ultrasonic probe.

  FIG. 12 shows an appearance structure of the second ultrasonic probe 11B among the ultrasonic probes 11 according to the present embodiment. The second ultrasonic probe 11B includes one transducer unit 20 dedicated to excitation, one transducer unit 30 dedicated to detection, a head unit 40, and the apparatus main body 12 (shown in FIG. 1). And a cable (not shown) for transmitting signals between them. The transducer unit 30 for detection is provided on one side along the second direction of the transducer unit 20 for excitation.

  As shown in FIG. 13, the transducer unit 20 dedicated for excitation includes one large-diameter transducer (a plurality of transducers respectively corresponding to the plurality of regions) divided into a plurality of regions divided along the first direction. A large-diameter vibrator 21s). Each vibrator of the large-diameter vibrator 21s transmits a relatively large energy excitation ultrasonic wave that generates an acoustic radiation pressure. Each transducer of the large-diameter transducer 21s has a plane wave Fp1 having a width in the first direction via an acoustic lens (not shown) that focuses the excitation ultrasonic waves transmitted from each transducer in the second direction. , Fp2 (shown in FIG. 14) has a certain width in the first direction. In addition, although the vibrator unit 20 dedicated for excitation includes an acoustic matching layer, a backing, an acoustic lens, and the like, the illustration thereof is omitted in FIGS.

  The structure and function of the transducer unit 30 for detection shown in FIGS. 12 and 13 are the same as those shown in FIGS.

  FIG. 14 is a diagram for explaining a method for calculating the sound speed of a shear wave when the second ultrasonic probe 11B shown in FIGS. 12 and 13 is used.

  FIG. 14 is a cross-sectional view of the second ultrasonic probe 11B in two orthogonal directions. The second ultrasonic probe 11B includes transducer units 20 and 30 and a head unit 40. The vibrator unit 20 for excitation includes a large-diameter vibrator 21s, a backing 22, and an acoustic lens 23. The detection-dedicated vibrator unit 30 includes a plurality of second vibrators 31s along the first direction, a backing 32, and an acoustic lens 33.

  A case where the wavefront of a shear wave is detected at two detection positions J1 and J2 along the first direction will be described with reference to FIG.

  First, one vibrator among the plurality of large-diameter vibrators 21s of the vibrator-dedicated vibrator unit 20 transmits a vibration pulse. The excitation pulse is focused on the excitation region I1 by the acoustic lens 23 that is focused in the second direction. Thereby, the vibrator unit 20 dedicated to vibration forms a vibration surface Fp1 with respect to the vibration region I1. Further, when a series of vibration pulses are repeatedly transmitted from the vibrator, the vibrator unit 20 dedicated for vibration repeatedly forms the vibration surface Fp1 in the vibration region I1.

  When the vibration surface Fp1 is repeatedly formed with respect to the vibration region I1, shear waves are generated due to the displacement of the tissue existing in the vibration region I1. Here, the shear wave propagating in the second direction due to the excitation surface Fp1 is defined as W1.

  In parallel (simultaneously) with the repeated formation of the vibration surface Fp1 for the vibration region I1, the vibrator unit 20 dedicated for vibration repeatedly forms the vibration surface Fp2 for the vibration region I2.

  When the vibration surface Fp2 is repeatedly formed with respect to the vibration region I2, shear waves are generated due to the displacement of the tissue existing in the vibration region I2. Here, the shear wave propagating in the second direction due to the excitation surface Fp2 is defined as W2.

  Excitation surfaces Fp1 and Fp2 formed by the transducer unit 20 dedicated for excitation are focused by the acoustic lens 23 in the second direction, but have no focusing effect in the first direction, so a substantially planar wavefront. Keep. Linear excitation regions I1 and I2 extending in the first direction at a certain depth are formed, and shear waves W1 and W2 generated by displacement of tissue existing in the excitation regions I1 and I2 propagate in the second direction.

  Subsequently, after the formation of the excitation surface Fp1 for the excitation region I1, the plurality of second transducers 31s of the transducer unit 30 dedicated for detection are focused on the detection position J1 (around the excitation region I1 in the second direction). Thus, the detection pulse that is electronically focused in the first direction is transmitted and received. The detection pulse is focused at the detection position J1 by the acoustic lens 33 that is focused in the second direction. As a result, the transducer unit 30 dedicated to detection forms a detection beam Ft1 with respect to the detection position J1. Further, a series of detection pulses are repeatedly transmitted and received from the plurality of second transducers 31s, so that the transducer unit 30 dedicated to detection repeatedly forms the detection beam Ft1 at the detection position J1.

  When the detection beam Ft1 is repeatedly formed with respect to the detection position J1, the shear wave W1 propagating in the second direction is detected. Note that the electronic focus in the first direction for forming the detection beam Ft1 is based on the transmission delay time and / or the reception delay time.

  In addition, after the formation of the excitation surface Fp2 with respect to the excitation region I2, in parallel (simultaneously) with the repeated formation of the detection beam Ft1 with respect to the detection position J1, the detection-dedicated transducer unit 30 detects the detection position J2. The beam Ft2 is repeatedly formed. When the detection beam Ft2 is repeatedly formed with respect to the detection position J2, the shear wave W2 propagating in the second direction is detected. The electronic focus in the first direction for forming the detection beam Ft2 is based on the transmission delay time and / or the reception delay time.

  When the wave front of the shear wave W1 generated by the vibration surface Fp1 is detected at the detection position J1 and the arrival time of the shear wave W1 is measured, the sound velocity of the shear wave W1 at the detection position J1 is calculated by a tissue Doppler method or the like. . In parallel with the calculation of the sound speed of the shear wave W1 at the detection position J1, the sound speed of the shear wave W2 generated by the excitation surface Fp2 at the detection position J2 is calculated in the same manner. Also, the average sound speed at the two detection positions J1 and J2 is calculated.

  As described above, in the second ultrasonic probe 11B, the wave fronts of the shear waves W1 and W2 propagating in the orthogonal second direction are detected at the two detection positions J1 and J2 along the first direction, respectively. Therefore, when the arrival times of the wave fronts of the shear waves W1, W2 are respectively measured at the two detection positions J1, J2 along the first direction using the second ultrasonic probe 11B, two excitation regions are used. Excitation operations for I1 and I2 are performed in parallel, and detection operations at the two detection positions J1 and J2 are performed in parallel. Therefore, in the second ultrasonic probe 11B, even when the arrival times of the wave fronts of the shear waves W1 and W2 are measured at the two detection positions J1 and J2, there is enough time to perform one transmission sequence. It is enough.

  The second ultrasonic probe 11B performs a single transmission sequence even when the arrival times of the shear wave fronts are measured at three or more detection positions J1, J2,... Along the first direction. Only one time is enough. Therefore, according to the second ultrasonic probe 11B, the frame rate of the elastography image and the frame rate of the B mode image in the B mode performed alternately with the elastography mode are improved.

  Further, when the second ultrasonic probe 11B is used, the interval D between the excitation region I1 and the detection position J1 and the interval D between the excitation region I2 and the detection position J2 are constant values. Therefore, when the second ultrasonic probe 11B is used, the uniformity of the image quality of the elastography image is improved.

  Further, according to the second ultrasonic probe 11B, the transducer unit 20 for excitation that transmits the excitation pulse independently from the transducer unit 30 for detection is provided. Therefore, as the plurality of large-diameter vibrators 21 s provided in the vibrator dedicated vibrator unit 20, those having the optimum frequency characteristics for effectively generating acoustic radiation pressure and those capable of outputting the optimum sound are selected. Is possible.

  In addition, in the case of the second ultrasonic probe 11B, a required region is selected from a plurality of regions along the first direction, so that the limitation is not along the entire range along the first direction but along the first direction. It is possible to form the excitation surface Fp1 (Fp2) in the range, and it is possible to reduce energy consumption that is wasted in transmitting the excitation pulse. In that case, the processing circuit 51 (illustrated in FIG. 1) selects a required region for transmitting the ultrasonic waves for excitation, from among a plurality of regions of the transducer unit 20 dedicated for excitation. Then, under the control of the processing circuit 51, the vibrator unit 20 dedicated to vibration transmits a vibration pulse from a large diameter vibrator provided in a required region of the large diameter vibrator 21s.

(Third ultrasonic probe)
FIG. 15 is a perspective view showing an external structure of a third ultrasonic probe among the ultrasonic probes 11 according to the present embodiment. FIG. 16 is a diagram showing a structure on the acoustic radiation surface side in the third ultrasonic probe.

  FIG. 15 shows an external structure of a third ultrasonic probe 11C among the ultrasonic probes 11 according to the present embodiment. The third ultrasonic probe 11C includes two vibrator units 20 (201, 202) dedicated to excitation along the second direction, one transducer unit 30 dedicated to detection, a head unit 40, and a device. A cable (not shown) for transmitting signals to and from the main body 12 (shown in FIG. 1) is provided. The transducer unit 30 dedicated to detection is provided so as to be sandwiched between transducer units 201 and 202 dedicated to excitation.

  As shown in FIG. 16, the vibrator units 201 and 202 dedicated to vibration include large-diameter vibrators 211 and 212, respectively. Each of the large-diameter vibrators 211 and 212 transmits a relatively large energy excitation ultrasonic wave that generates acoustic radiation pressure. The large-diameter vibrators 211 and 212 are plane waves Fp1 having a width in the first direction via an acoustic lens (not shown) that focuses the excitation ultrasonic waves transmitted from the large-diameter vibrators in the second direction. , Fp2 (shown in FIG. 17) has a certain width in the first direction. Each of the vibrator units 201 and 202 dedicated to excitation includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIGS. 15 and 16.

  The structure and function of the transducer unit 30 for detection shown in FIGS. 15 and 16 are the same as those shown in FIGS.

  FIG. 17 is a diagram for explaining a method for calculating the sound speed of a shear wave when the third ultrasonic probe 11C shown in FIGS. 15 and 16 is used.

  FIG. 17 is a cross-sectional view of the third ultrasonic probe 11C in two orthogonal directions. The third ultrasonic probe 11C includes transducer units 201, 202, and 30 and a head unit 40. The vibrator unit 201 for excitation includes a large-diameter vibrator 211, a backing 221, and an acoustic lens 231. The vibrator-dedicated vibrator unit 202 includes a large-diameter vibrator 212, a backing 222, and an acoustic lens 232. The detection-dedicated vibrator unit 30 includes a plurality of second vibrators 31s along the first direction, a backing 32, and an acoustic lens 33.

  The case where the wavefront of a shear wave is detected at two detection positions J1 and J2 along the first direction will be described with reference to FIG.

  First, the large-diameter vibrator 211 of the vibrator unit 201 dedicated for vibration transmits a vibration pulse. The excitation pulse is focused on the excitation area I1 by the acoustic lens 231 that is focused in the second direction. Accordingly, the vibrator unit 201 dedicated for vibration forms a vibration surface Fp1 with respect to the vibration region I1. In addition, when a series of vibration pulses are repeatedly transmitted from the large-diameter vibrator 211, the vibrator unit 201 dedicated to vibration repeatedly forms the vibration surface Fp1 in the vibration region I1.

  When the vibration surface Fp1 is repeatedly formed with respect to the vibration region I1, shear waves are generated due to the displacement of the tissue existing in the vibration region I1. Here, the shear wave propagating in the second direction due to the excitation surface Fp1 is defined as W1.

  In parallel (simultaneously) with the repeated formation of the vibration surface Fp1 for the vibration region I1, the vibrator unit 202 dedicated for vibration repeatedly forms the vibration surface Fp2 for the vibration region I2. When the vibration surface Fp2 is repeatedly formed with respect to the vibration region I2, shear waves are generated due to the displacement of the tissue existing in the vibration region I2. Here, the shear wave propagating in the second direction due to the excitation surface Fp2 is defined as W2.

  The excitation surfaces Fp1 and Fp2 formed by the vibrator dedicated transducer units 201 and 202 are focused by the acoustic lenses 231 and 232 in the second direction, but have no focusing effect in the first direction. Maintain a flat wavefront. Linear excitation regions I1 and I2 extending in the first direction at a certain depth are formed, and shear waves W1 and W2 generated by displacement of tissue existing in the excitation regions I1 and I2 propagate in the second direction.

  Although the positions of the vibration regions I1 and I2 in the depth direction are the same, FIG. 17 illustrates them at different positions in the depth direction for convenience.

  Subsequently, after repeatedly forming the vibration surfaces Fp1 and Fp2 for the vibration regions I1 and I2, the plurality of second transducers 31s of the transducer unit 30 dedicated for detection are detected at the detection position J1 (excitation region I1 in the second direction). , I2 is transmitted and received in the first direction so as to be focused on the periphery of I2. The detection pulse is focused at the detection position J1 by the acoustic lens 33 that is focused in the second direction. As a result, the transducer unit 30 dedicated to detection forms a detection beam Ft1 with respect to the detection position J1. Further, a series of detection pulses are repeatedly transmitted and received from the plurality of second transducers 31s, so that the transducer unit 30 dedicated to detection repeatedly forms the detection beam Ft1 at the detection position J1.

  When the detection beam Ft1 is repeatedly formed with respect to the detection position J1, shear waves W1 and W2 propagating in the second direction are detected. Note that the electronic focus in the first direction for forming the detection beam Ft1 is based on the transmission delay time and / or the reception delay time.

  In addition, after the repeated formation of the excitation surfaces Fp1 and Fp2 for the excitation regions I1 and I2, in parallel (simultaneously) with the repeated formation of the detection beam Ft1 for the detection position J1, the transducer unit 30 dedicated for detection is detected at the detection position J2. The detection beam Ft2 is repeatedly formed. When the detection beam Ft2 is repeatedly formed with respect to the detection position J2, shear waves W1 and W2 propagating in the second direction are detected. The electronic focus in the first direction for forming the detection beam Ft2 is based on the transmission delay time and / or the reception delay time.

  When the wave fronts of the shear waves W1 and W2 generated by the vibration surfaces Fp1 and Fp2 are detected at the detection position J1 and the arrival times (average values) of the shear waves W1 and W2 are measured, the detection positions are detected by a tissue Doppler method or the like. The sound speed (average value) of the shear waves W1 and W2 at J1 is calculated. In parallel with the calculation of the sound speeds of the shear waves W1 and W2 at the detection position J1, the sound speeds of the shear waves W1 and W2 generated by the excitation surfaces Fp1 and Fp2 at the detection position J2 are calculated in the same manner. Also, the average sound speed at the two detection positions J1 and J2 is calculated.

  As described above, in the third ultrasonic probe 11C, the wave fronts of the shear waves W1 and W2 propagating in the orthogonal second direction are detected at each of the two detection positions J1 and J2 along the first direction. . Therefore, in order to measure the arrival times of the wave fronts of the shear waves W1 and W2 at the two detection positions J1 and J2 along the first direction using the third ultrasonic probe 11C, two excitation regions are used. Excitation operations for I1 and I2 are performed in parallel, and detection operations at the two detection positions J1 and J2 are performed in parallel. Therefore, in the third ultrasonic probe 11C, even when the arrival times of the wave fronts of the shear waves W1 and W2 are measured at the two detection positions J1 and J2, respectively, there is enough time to perform one transmission sequence. It is enough.

  The third ultrasonic probe 11C performs a single transmission sequence even when the arrival times of the shear wave fronts are measured at three or more detection positions J1, J2,... Along the first direction. Only one time is enough. Therefore, according to the third ultrasonic probe 11C, the frame rate of the elastography image and the frame rate of the B mode image in the B mode performed alternately with the elastography mode are improved.

  Further, when the third ultrasonic probe 11C is used, the interval D between the excitation region I1 and the detection position J1, the interval D between the excitation region I1 and the detection position J2, the excitation region I2, and the detection position J1 And the interval D between the vibration region I2 and the detection position J2 are constant values. Therefore, when the third ultrasonic probe 11C is used, the uniformity of the image quality of the elastography image is improved.

  In addition, according to the third ultrasonic probe 11C, the transducer units 201 and 202 dedicated to excitation that transmit the excitation pulse independently from the transducer unit 30 dedicated to detection are provided. Therefore, it is possible to select the large-diameter vibrators 211 and 212 provided in the vibrator-exclusive vibrator units 201 and 202 that have optimum frequency characteristics for effectively generating acoustic radiation pressure.

  In addition, when displaying an elastography image superimposed on a normal B-mode image obtained using the transducer unit 30 dedicated to detection, the first ultrasonic probe 11A (shown in FIGS. 4 and 5) or In the second ultrasonic probe 11B (shown in FIGS. 12 and 13), the cross section of the B-mode image is slightly different from the cross section of the elastography image. However, in the third ultrasonic probe 11C, the transducer units 201 and 202 dedicated for excitation are arranged on both sides along the second direction of the transducer unit 30 dedicated for detection, so that the transducer unit dedicated for detection is used. It is possible to match the center axis of 30 with the center of the cross section of the elastography image.

  Note that the structure of the second ultrasonic probe 11B may be combined with the third ultrasonic probe 11C. That is, each of the transducer units 201 and 202 dedicated to the excitation of the third ultrasonic probe 11C has one large-diameter transducer (a plurality of transducers) in each of the plurality of regions divided along the first direction. A plurality of large-diameter vibrators each corresponding to a region may be provided.

(Fourth ultrasonic probe)
FIG. 18 is a perspective view showing an external structure of a fourth ultrasonic probe among the ultrasonic probes 11 according to the present embodiment. FIG. 19 is a diagram showing a structure on the acoustic radiation surface side in the fourth ultrasonic probe.

  FIG. 18 shows an appearance structure of a fourth ultrasonic probe 11D among the ultrasonic probes 11 according to the present embodiment. The fourth ultrasonic probe 11D includes one transducer unit 20 dedicated to excitation, one transducer unit 30 dedicated to detection, a head unit 40, and the apparatus main body 12 (shown in FIG. 1). And a cable (not shown) for transmitting signals between them. The transducer unit 30 for detection is provided on one side along the second direction of the transducer unit 20 for excitation.

  As shown in FIG. 19, the width in the second direction of the transducer unit 20 dedicated to excitation is larger than the width in the second direction of the transducer unit 30 dedicated to detection. Further, the vibrator dedicated vibrator unit 20 includes a plurality of first vibrators 21s along the second direction. Each transducer of the plurality of first transducers 21s shown in FIG. 19 transmits ultrasonic waves for exciting with relatively large energy that generate acoustic radiation pressure. The vibrator unit 20 dedicated for excitation includes an acoustic matching layer, a backing, and the like, which are not shown in FIGS. 15 and 16.

  The structure and function of the transducer unit 30 for detection shown in FIGS. 18 and 19 are the same as those shown in FIGS.

  FIG. 20 is a diagram for explaining a method of calculating the sound speed of the shear wave when the fourth ultrasonic probe 11D shown in FIGS. 18 and 19 is used.

  FIG. 20 is a cross-sectional view of the fourth ultrasonic probe 11D in two orthogonal directions. The fourth ultrasonic probe 11D includes transducer units 20 and 30 and a head unit 40. The vibrator-dedicated vibrator unit 20 includes a plurality of first vibrators 21s and a backing 22 along the second direction, and does not need to include an acoustic lens. The detection-dedicated vibrator unit 30 includes a plurality of second vibrators 31s along the first direction, a backing 32, and an acoustic lens 33.

  A case where the wavefront of a shear wave is detected at two detection positions J1 and J2 along the first direction will be described with reference to FIG.

  First, the plurality of first vibrators 21s of the vibrator-dedicated vibrator unit 20 transmit the vibration surface Fp that is electronically focused in the second direction so as to be focused on the vibration region I. Accordingly, the vibrator unit 20 dedicated to vibration forms a vibration surface Fp with respect to the vibration region I. In addition, a series of excitation pulses are repeatedly transmitted from the plurality of first vibrators 21 s, so that the vibrator unit 20 dedicated to vibration repeatedly forms the vibration surface Fp in the vibration region I.

  When the vibration surface Fp is repeatedly formed with respect to the vibration region I, shear waves are generated due to the displacement of the tissue existing in the vibration region I. Here, the shear wave propagating in the second direction due to the excitation surface Fp is defined as W.

  The vibration surface Fp formed by the vibrator unit 20 dedicated for vibration is focused by the electronic focus in the second direction, but has no focusing effect in the first direction, and therefore maintains a substantially planar wavefront. A linear excitation region I extending in the first direction at a certain depth is formed, and the shear wave W generated by the displacement of the tissue existing in the excitation region I propagates in the second direction.

  Subsequently, after repeated formation of the vibration surface Fp for the vibration region I, the plurality of second vibrators 31s of the transducer unit 30 dedicated for detection are located at the detection position J1 (around the vibration region I in the second direction). A detection pulse electronically focused in the first direction so as to be focused is transmitted and received. The detection pulse is focused at the detection position J1 by the acoustic lens 33 that is focused in the second direction. As a result, the transducer unit 30 dedicated to detection forms a detection beam Ft1 with respect to the detection position J1. In addition, the detection pulse is repeatedly transmitted and received from the plurality of second transducers 31s, so that the transducer unit 30 dedicated to detection repeatedly forms the detection beam Ft1 at the detection position J1.

  When the detection beam Ft1 is repeatedly formed with respect to the detection position J1, the shear wave W propagating in the second direction is detected. Note that the electronic focus in the first direction for forming the detection beam Ft1 is based on the transmission delay time and / or the reception delay time.

  In addition, after the formation of the excitation surface Fp for the excitation region I, in parallel (simultaneously) with the repeated formation of the detection beam Ft1 for the detection position J1, the detection-dedicated transducer unit 30 detects the detection position J2. The beam Ft2 is repeatedly formed. When the detection beam Ft2 is repeatedly formed with respect to the detection position J2, the shear wave W propagating in the second direction is detected. The electronic focus in the first direction for forming the detection beam Ft2 is based on the transmission delay time and / or the reception delay time.

  When the wave front of the shear wave W generated by the vibration surface Fp is detected at the detection position J1 and the arrival time of the shear wave W is measured, the sound velocity of the shear wave W at the detection position J1 is calculated by a tissue Doppler method or the like. . In parallel with the calculation of the sound speed of the shear wave W at the detection position J1, the sound speed of the shear wave W generated by the vibration surface Fp at the detection position J2 is calculated in the same manner. Also, the average sound speed at the two detection positions J1 and J2 is calculated.

  As described above, in the fourth ultrasonic probe 11D, the wave fronts of the shear waves W propagating in the orthogonal second direction are detected at the two detection positions J1 and J2 along the first direction. Therefore, when the arrival times of the wave fronts of the shear waves W are measured at the two detection positions J1 and J2 along the first direction using the fourth ultrasonic probe 11D, a series of excitation pulses are transmitted. One detection is required, and the detection operations at the two detection positions J1 and J2 are performed in parallel. Therefore, in the fourth ultrasonic probe 11D, even when the arrival times of the wave fronts of the shear waves W are respectively measured at the two detection positions J1 and J2, it is sufficient to have time for only one transmission sequence. It is.

  The fourth ultrasonic probe 11D performs one transmission sequence even when the arrival times of the shear wave fronts are measured at three or more detection positions J1, J2,... Along the first direction. Only one time is enough. Therefore, according to the fourth ultrasonic probe 11D, the frame rate of the elastography image and the frame rate of the B mode image in the B mode performed alternately with the elastography mode are improved.

  Further, when the fourth ultrasonic probe 11D is used, the interval D between the vibration region I and the plurality of detection positions J1, J2 is a constant value. Therefore, when the fourth ultrasonic probe 11D is used, the uniformity of the image quality of the elastography image is improved.

  In addition, according to the fourth ultrasonic probe 11D, the transducer unit 20 for excitation that transmits the excitation pulse independently from the transducer unit 30 for detection is provided. Therefore, as the plurality of first vibrators 21 s provided in the vibrator dedicated vibrator unit 20, those having the optimum frequency characteristics for effectively generating acoustic radiation pressure and those capable of outputting the optimum sound are selected. Is possible.

  In addition, when the fourth ultrasonic probe 11D is used, electronic focusing is performed in the second direction so that the vibration surface Fp is focused on a desired vibration region I (a transmission delay time is given). When the fourth ultrasonic probe 11D is used, it is possible to form the excitation surface Fp with a large diameter compared to the case where the first ultrasonic probe 11A (shown in FIGS. 4 and 5) is used. Further, in the first ultrasonic probe 11A, the excitation surface Fp is fixedly formed according to the sound field determined by the acoustic lens 23 (shown in FIG. 10), but in the fourth ultrasonic probe 11D, the second direction By controlling the electronic focus, it is possible to form an optimal sound field for the depth at which an elastography image is desired.

(Fifth ultrasonic probe)
FIG. 21 is a diagram illustrating a structure on the acoustic radiation surface side in the fifth ultrasonic probe.

  FIG. 21 shows a fifth ultrasonic probe 11E having a structure in which the second ultrasonic probe 11B shown in FIGS. 12 and 13 and the structure of the fourth ultrasonic probe 11D shown in FIGS. 18 and 19 are combined. Show.

  As shown in FIG. 21, the vibrator unit 20 dedicated for excitation includes a plurality of first vibrators 21 s along the second direction in each of a plurality of areas divided along the first direction. Each transducer of the plurality of first transducers 21s shown in FIG. 21 transmits ultrasonic waves for excitation with relatively large energy that generate acoustic radiation pressure.

  In the case of the fifth ultrasonic probe 11E, as described using the second ultrasonic probe 11B in FIG. 14, it is possible to form the excitation surface Fp in a limited range along the first direction. It is possible to reduce energy consumption that is wasted in transmitting the excitation pulse. In this case, the processing circuit 51 (illustrated in FIG. 1) selects a required region for transmitting the excitation pulse from the plurality of regions of the vibrator unit 20 dedicated for excitation. Then, the transducer unit 20 dedicated to excitation transmits excitation pulses from the plurality of first transducers 21 s provided in a required region under the control of the processing circuit 51.

  Further, in the case of the fifth ultrasonic probe 11E, the same effect as in the case of the fourth ultrasonic probe 11D shown in FIG. 20 is obtained.

(Sixth ultrasonic probe)
FIG. 22 is a perspective view showing an external structure of a sixth ultrasonic probe in the ultrasonic probe 11 according to the present embodiment. FIG. 23 is a diagram illustrating a structure on the acoustic radiation surface side of the sixth ultrasonic probe.

  FIG. 22 shows an appearance structure of a sixth ultrasonic probe 11F among the ultrasonic probes 11 according to the present embodiment. The sixth ultrasonic probe 11F includes one vibrator unit 20 dedicated to vibration, one vibrator unit 30 dedicated to detection, a head portion (exterior part) 40, and the apparatus main body 12 (see FIG. 1). And a cable (not shown) for transmitting signals to and from the figure. The transducer unit 30 for detection is provided on one side along the second direction of the transducer unit 20 for excitation.

  As shown in FIG. 23, the vibrator dedicated vibrator unit 20 includes a plurality of first vibrators 21s along the first direction. Each of the plurality of first vibrators 21s transmits ultrasonic waves for excitation with relatively large energy that generate acoustic radiation pressure. The plurality of first transducers 21s have a width in the first direction via an acoustic lens (not shown) that focuses the excitation ultrasonic waves transmitted from the plurality of first transducers 21s in the second direction. It has a certain width in the first direction so as to be a plane wave Fp (shown in FIG. 10). The vibrator unit 20 dedicated for excitation includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIGS.

  The structure and function of the transducer unit 30 for detection shown in FIGS. 22 and 23 are the same as those shown in FIGS.

  By transmitting ultrasonic waves for excitation from all of the plurality of first transducers 21s, a plane wave Fp is formed as in the case of the first ultrasonic probe 11A shown in FIG. 10, and a shear wave related to the plane wave Fp is formed. Is calculated. Further, by transmitting ultrasonic waves for excitation from a part of the plurality of first transducers 21s, a plane wave whose width is limited from the plane wave Fp in the case of the first ultrasonic probe 11A shown in FIG. 10 is formed. Then, the sound velocity of the shear wave related to the plane wave is calculated.

  In the case of the sixth ultrasonic probe 11F, it is possible to form an excitation surface in a limited range along the first direction, and it is possible to reduce energy consumption that is wasted in transmitting the excitation pulse. In that case, the vibrator unit 20 dedicated to vibration transmits a vibration pulse from a part of the plurality of first vibrators 21 s under the control of the processing circuit 51.

  Furthermore, in the case of the sixth ultrasonic probe 11F, the same effect as in the case of the first ultrasonic probe 11A shown in FIG. 10 can be obtained. In that case, the vibrator unit 20 dedicated to vibration transmits a vibration pulse from all of the plurality of first vibrators 21s under the control of the processing circuit 51.

(Seventh ultrasonic probe)
FIG. 24 is a perspective view showing an external structure of a seventh ultrasonic probe in the ultrasonic probe 11 according to the present embodiment.

  FIG. 24 shows an external structure of a seventh ultrasonic probe 11G among the ultrasonic probes 11 according to the present embodiment. While the first to sixth ultrasonic probes described above are external ultrasonic probes, the seventh ultrasonic probe 11G is an internal ultrasonic probe. The seventh ultrasonic probe 11G has a structure in which the structure of the sixth ultrasonic probe 11F shown in FIG. 22 is applied to the extracorporeal ultrasonic probe. The seventh ultrasonic probe 11G includes the first to fifth ultrasonic probes 11A to 11E. The structure may have a structure applied to an external ultrasonic probe.

  The seventh ultrasonic probe 11G includes an insertion portion 111 that can be inserted into the subject. The insertion unit 111 includes one vibrator unit 20 dedicated for excitation along the second direction and one vibrator unit 30 dedicated for detection. The transducer unit 30 for detection is provided on one side along the second direction of the transducer unit 20 for excitation. The second direction is along the axis R of the sixth ultrasonic probe 11F.

  As shown in FIG. 24, the vibrator unit 20 dedicated for excitation includes a plurality of first vibrators 21s along the third direction (circumferential direction) centering on the axis R of the sixth ultrasonic probe 11F. . The plurality of first vibrators 21s are convex arrays.

  Each of the plurality of first vibrators 21s transmits ultrasonic waves for excitation with relatively large energy that generate acoustic radiation pressure. The vibrator unit 20 dedicated for excitation includes an acoustic matching layer, a backing, an acoustic lens, and the like, which are not shown in FIG.

  On the other hand, the transducer unit 30 for detection includes a plurality of second transducers 31s along the third direction. The multiple second transducers 31s are convex arrays. The example of the transducer unit 30 for detection is provided on the tip side of the transducer unit 20 for excitation, but the present invention is not limited to this case.

  Each of the multiple second transducers 31 s transmits and receives ultrasonic waves for detection with relatively lower energy than the ultrasonic waves for excitation. Note that the transducer unit 30 dedicated to detection includes an acoustic matching layer, a backing, an acoustic lens, and the like, but the illustration thereof is omitted in FIG.

  In addition to the elastography mode, the plurality of second vibrators 31s are used in the B mode and the like. In the B mode, a still image can be obtained by sequentially switching the position of the ultrasonic beam (scanning line) for the B mode in the third direction in the third direction. The plurality of second vibrators 31s can also obtain moving images by obtaining still images in a plurality of frames in the B mode.

  By transmitting ultrasonic waves for excitation from all of the plurality of first transducers 21s, a plane wave Fp is formed as in the case of the first ultrasonic probe 11A shown in FIG. 10, and a shear wave related to the plane wave Fp is formed. Is calculated. Further, by transmitting ultrasonic waves for excitation from a part of the plurality of first transducers 21s, a plane wave whose width is limited from the plane wave Fp in the case of the first ultrasonic probe 11A shown in FIG. 10 is formed. Then, the sound velocity of the shear wave related to the plane wave is calculated.

  In the case of the seventh ultrasonic probe 11G, it is possible to form an excitation surface in a limited range along the first direction, and it is possible to reduce energy consumption that is wasted in transmitting the excitation pulse. In that case, the vibrator unit 20 dedicated to vibration transmits a vibration pulse from a part of the plurality of first vibrators 21 s under the control of the processing circuit 51.

  Further, in the case of the seventh ultrasonic probe 11G, the same effect as in the case of the first ultrasonic probe 11A shown in FIG. 10 can be obtained. In that case, the vibrator unit 20 dedicated to vibration transmits a vibration pulse from all of the plurality of first vibrators 21s under the control of the processing circuit 51.

  The ultrasonic probe according to at least one embodiment described above can generate information for generating an elastography image in the time required for the minimum number of transmission sequences. According to the ultrasonic diagnostic apparatus according to at least one embodiment described above, an elastography image can be generated in the time required for the minimum number of transmission sequences, and the uniformity of the image quality of the entire elastography image can be improved. However, an elastography image can be obtained at a high frame rate.

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

DESCRIPTION OF SYMBOLS 10 ... Ultrasonic diagnostic apparatus 11, 11A, 11B, 11C, 11D, 11E, 11F, 11G ... Ultrasonic probe 12 ... Apparatus main body 20, 201, 202 ... Vibrating transducer units 21, 211, 212 ... Large diameter A plurality of first vibrators, a plurality of large-diameter vibrators 23, 231, 232, an acoustic lens 30, a transducer unit 31s dedicated to detection, a plurality of second vibrators 51, a control unit 56, a waveform analysis unit. 57 ... Hardness estimation part

Claims (20)

At least one first vibrator that functions as a vibrator dedicated to vibration that performs vibration by acoustic radiation pressure in an elastography mode;
A plurality of second vibrators functioning as a vibrator exclusively for detection for detecting a shear wave generated by the vibration in the elastography mode;
Ultrasonic probe equipped with. At least one first vibrator dedicated to excitation that performs excitation by acoustic radiation pressure on the subject;
A plurality of second transducers for detecting shear waves generated by the excitation by transmitting and receiving ultrasonic waves to the subject;
Ultrasonic probe equipped with. At least one first vibrator for performing excitation by acoustic radiation pressure on the subject;
A plurality of second vibrators having a size different from that of the first vibrator and detecting shear waves generated by the vibration by transmitting and receiving ultrasonic waves;
Ultrasonic probe equipped with.   The ultrasound probe according to any one of claims 1 to 3, further comprising an insertion portion that includes the at least one first transducer and the plurality of second transducers and is inserted into a subject. The plurality of second vibrators are arranged along at least the azimuth direction,
The plurality of first vibrators as the at least one first vibrator and the plurality of second vibrators are arranged side by side in an elevation direction orthogonal to the azimuth direction. The ultrasonic probe according to claim 1. An ultrasonic transducer dedicated to vibration that includes the at least one first transducer and has the width along the azimuth direction and focuses the ultrasonic waves along the elevation direction orthogonal to the azimuth direction Unit,
An ultrasonic transducer unit dedicated to detection provided on the side along the elevation direction of the ultrasonic transducer unit dedicated to excitation, comprising the plurality of second transducers;
The ultrasonic probe according to claim 1, wherein the ultrasonic probe is provided. One ultrasonic transducer unit dedicated to excitation as the ultrasonic transducer unit dedicated to excitation includes one first transducer and the excitation transmitted from the one first transducer. An acoustic lens for focusing the ultrasonic wave for use along the elevation direction,
The ultrasonic probe according to claim 6, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction. One ultrasonic transducer unit dedicated to vibration as the ultrasonic transducer unit dedicated to excitation is one first arranged in each of a plurality of regions divided along the azimuth direction. An oscillator, and an acoustic lens that focuses the ultrasonic wave for excitation transmitted from the one first oscillator in each region along the elevation direction,
The ultrasonic probe according to claim 6, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction. Each of the two ultrasonic transducer units dedicated to the vibration as the ultrasonic transducer unit dedicated to the excitation is transmitted from one transducer and the one transducer. An acoustic lens for focusing the exciting ultrasonic waves along the elevation direction,
The ultrasonic probe according to claim 6, wherein the ultrasonic transducer unit dedicated to detection is provided so as to be sandwiched between the two ultrasonic transducer units dedicated to excitation. One ultrasonic transducer unit dedicated to excitation as the ultrasonic transducer unit dedicated to excitation includes a plurality of first transducers along the elevation direction,
The ultrasonic probe according to claim 6, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction. One ultrasonic transducer unit dedicated to excitation as the ultrasonic transducer unit dedicated to excitation includes a plurality of regions along the elevation direction in each region of the plurality of regions divided along the azimuth direction. The first vibrator
The ultrasonic probe according to claim 6, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction.   In order to switch the timing between transmission of the ultrasonic wave for excitation and transmission / reception of the ultrasonic wave for detection, the ultrasonic transducer unit dedicated for excitation and the ultrasonic transducer unit dedicated for detection are turned on / off. The ultrasonic probe according to claim 6, which is connected in parallel via a high voltage switch that selectively performs OFF control. The ultrasonic probe according to any one of claims 1 to 12, and
Controlling transmission of ultrasonic waves for excitation in the at least one first transducer, controlling transmission / reception of ultrasonic waves for detection in the plurality of second transducers, and receiving signals related to the ultrasonic waves for detection A control unit for calculating the sound speed of the shear wave based on the control and estimating the hardness of the tissue existing in the excitation region based on the sound speed;
An ultrasonic diagnostic apparatus. The ultrasonic probe is
An ultrasonic transducer dedicated to vibration that includes the at least one first transducer and has the width along the azimuth direction and focuses the ultrasonic waves along the elevation direction orthogonal to the azimuth direction Unit,
An ultrasonic transducer unit dedicated to detection provided on the side along the elevation direction of the ultrasonic transducer unit dedicated to excitation, comprising the plurality of second transducers;
The ultrasonic diagnostic apparatus according to claim 13, wherein: One ultrasonic transducer unit dedicated to vibration as the ultrasonic transducer unit dedicated to excitation is one first arranged in each of a plurality of regions divided along the azimuth direction. An oscillator, and an acoustic lens that focuses the ultrasonic wave for excitation transmitted from the one first oscillator in each region along the elevation direction,
The ultrasonic diagnostic apparatus according to claim 14, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction. The control unit performs control so as to select a required region for transmitting the ultrasonic waves for excitation among the plurality of regions of the ultrasonic transducer unit dedicated to the excitation,
The ultrasonic diagnostic apparatus according to claim 15, wherein the ultrasonic transducer unit dedicated to vibration transmits the ultrasonic waves for vibration from one first transducer provided in the required region. The single ultrasonic transducer unit dedicated to excitation includes a plurality of first transducers along the elevation direction in each region of the plurality of regions divided along the azimuth direction,
The ultrasonic diagnostic apparatus according to claim 14, wherein the ultrasonic transducer unit dedicated to detection is provided on one side of the one ultrasonic transducer unit dedicated to excitation along the elevation direction. The control unit performs control so as to select a required region for transmitting the ultrasonic waves for excitation among the plurality of regions of the ultrasonic transducer unit dedicated to the excitation,
The ultrasonic diagnostic apparatus according to claim 17, wherein the vibration dedicated ultrasonic transducer unit transmits the vibration ultrasonic waves from a plurality of first transducers provided in the required region. The controller is
Controlling the ultrasonic probe to focus the ultrasonic waves for detection in parallel with respect to a plurality of detection positions along the azimuth direction,
Control is performed so as to calculate in parallel the sound velocity of the shear wave at the plurality of detection positions based on reception signals relating to the ultrasonic waves for detection corresponding to the plurality of detection positions from the ultrasonic probe. Item 15. The ultrasonic diagnostic apparatus according to Item 14.   The control unit superimposes information indicating the hardness of the tissue on a B-mode image generated based on transmission of ultrasonic waves from the plurality of second transducers of the ultrasonic transducer unit dedicated to detection. The ultrasonic diagnostic apparatus according to claim 14, which is displayed on a display.

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