JP2005253751A - Ultrasonic probe and ultrasonic diagnosis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnosis apparatus transmitting ultrasonic beam with appropriate frequency according to the depth of a subject and imaging the shape and tissue property of the subject based on the obtained ultrasonic echo signals. <P>SOLUTION: This ultrasonic diagnosis apparatus is provided with an ultrasonic transducer array including a first group vibrator having a first resonant frequency, and a second group vibrator disposed its outside and having a second resonant frequency; a first acoustic lens focusing ultrasonic waves transmitted from the first group vibrator on a first focal length, and a second acoustic lens focusing the ultrasonic waves transmitted from the second vibrator on a second focal length longer than the first focal length. The first group and the second group vibrator groups are driven at different frequencies respectively to generate the first and the second ultrasonic beams, detect and compose them, thus attaining the imaging at the appropriate frequency according to the depth of the subject. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus that generates an ultrasonic image used for diagnosis by transmitting and receiving ultrasonic waves and imaging an organ, bone, and the like in a living body.

  In an ultrasonic imaging apparatus used for medical diagnosis, an ultrasonic probe (probe) including a plurality of ultrasonic transducers having an ultrasonic transmission / reception function is used. From such an ultrasonic probe, an ultrasonic beam formed by combining a plurality of ultrasonic waves is transmitted, and an ultrasonic echo reflected inside the subject is received. By constructing an image based on the intensity of those ultrasonic echoes, the state inside the subject can be reproduced on the screen.

  However, in practice, an appropriate ultrasonic echo intensity and resolution cannot be obtained over the entire area to be imaged. Since the propagation characteristics of ultrasonic waves in an object vary depending on the frequency of the ultrasonic waves, the image quality of the obtained ultrasonic image varies greatly depending on the frequency of the ultrasonic waves used. For example, a high-resolution ultrasonic image can be obtained by using high-frequency ultrasonic waves. However, since such ultrasonic waves are easily scattered, they are greatly attenuated in the deep part of the subject. On the contrary, low-frequency ultrasonic waves have good propagation characteristics, but it is difficult to increase the resolution.

  As a general property, ultrasonic waves are strongly reflected in a region where the difference in acoustic impedance is large. Therefore, in the human body, the intensity of the ultrasonic echo reflected at the boundary between the soft tissue such as muscle and the hard tissue such as bone increases. Therefore, in the ultrasonic image, such a boundary is displayed with high luminance. On the other hand, since the intensity of the ultrasonic wave transmitted through such a boundary is greatly reduced, the intensity of the ultrasonic echo reflected behind or inside the hard tissue is also reduced. Therefore, it is extremely difficult to visually recognize soft tissue such as muscles separately from hard tissue such as bones, tendons and nucleus pulposus in an ultrasonic image. Therefore, it has been studied to use elements other than the intensity of the ultrasonic echo when generating the ultrasonic image. For example, in Patent Document 1, in order to observe non-invasively deeper than the epidermis of the skin and perform various discriminations on the skin, at least one or more types of frequencies selected from a predetermined range are used. It is disclosed that ultrasonic waves are emitted from the surface of the skin toward the inside of the skin, and the reflected waves are received and imaged.

  As a related technique, Patent Document 2 discloses an ultrasonic probe in which a plurality of transducers are two-dimensionally arranged along two directions orthogonal to each other, and an opening width / thickness at the center of the arrangement> It is disclosed that a vibrator satisfying the relationship 3 is disposed, and a vibrator satisfying an opening width / thickness ≦ 0.3 is disposed outside the vibrator. By defining the shape of the two types of vibrators in this way, the thickness vibration mode is set in the central portion of the vibrator arrangement and the longitudinal vibration mode is set in the outer portion, so the thickness of each vibrator is changed. Without changing the resonance frequency of the ultrasonic wave, it is possible to transmit a broadband ultrasonic wave. Therefore, it is possible to obtain high directivity and high resolution from a short distance to a long distance by using one ultrasonic probe by properly using the region of the transducer to be used according to the imaging distance. Become. However, in this ultrasonic diagnostic apparatus, since any frequency is selected and used according to the application, it is not possible to acquire image information regarding the entire region to be imaged at a time.

  Patent Document 3 discloses an ultrasonic probe in which a plurality of transducer elements that transmit and receive ultrasonic waves are arranged two-dimensionally, and the plurality of transducer elements arranged in two dimensions have frequency characteristics. An ultrasonic probe is disclosed which is composed of a plurality of different types of transducer elements and is provided so as to be mixed in a two-dimensional array. By using such an ultrasonic probe, it is possible to transmit and receive broadband ultrasonic waves covering frequency components of fundamental waves and harmonic components used for harmonic imaging. However, when such an ultrasonic probe is used, appropriate directivity and resolution in the depth direction cannot be obtained, and thus the tissue characteristics of the subject cannot be imaged.

  Japanese Patent Application Laid-Open No. H10-260260 discloses a central vibrator element that is a target for generating a focused sound field that is focused on a predetermined point, and an annular ring that is coaxial with the central vibrator element and has a confocal point. A split-type transducer including the peripheral vibrator element, and a synthesized sound field of the central vibrator element and the peripheral vibrator element is focused at a position different from a predetermined focus of the split-type transducer, An ultrasonic diagnostic apparatus including a transmission unit that delays and drives a central transducer element and a peripheral transducer element is disclosed. By using such an ultrasonic diagnostic apparatus, it is possible to obtain a transmission sound field characteristic or a reception sound field characteristic having a deep focal depth and a thin ultrasonic beam. However, in this ultrasonic diagnostic apparatus, since single-frequency ultrasonic waves are used, for example, a sufficient ultrasonic echo intensity cannot be obtained at the deep part of the subject, and the subject is shallow. As for the part, since the beam diameter becomes thick, there is a problem that the azimuth resolution is lowered.

  In Patent Document 5, an ultrasonic probe having a broadband ultrasonic transducer for transmitting and receiving ultrasonic waves and a drive frequency applied to the broadband ultrasonic transducer are supplied while being changed, and the broadband ultrasonic transducer emits the ultrasonic probe. A transmission / reception unit that receives echo signals of the received ultrasonic waves to obtain echo data, storage means for storing the echo data obtained by the transmission / reception unit, and control of changes in drive frequency generated by the transmission / reception unit; Based on the control means for controlling the storage means to store the echo data corresponding to the change in the drive frequency, and the echo data stored in the storage control means corresponding to the drive frequency, an ultrasonic tomographic image is obtained. An ultrasonic diagnostic apparatus including an image processing means for generating is disclosed. According to this ultrasonic diagnostic apparatus, ultrasonic waves having different driving frequencies are sequentially transmitted and received from one ultrasonic probe according to the distance from the ultrasonic probe to the test portion, and echo data obtained thereby is used. An ultrasonic tomographic image can be constructed. However, in order to manufacture such an ultrasonic probe, a vibrator having a broadband resonance frequency is required. In addition, since an image is constructed by repeatedly transmitting and receiving one type of ultrasonic wave, the frame rate is lowered.

  Patent Document 6 discloses an ultrasonic probe in which a plurality of ultrasonic transducers are arranged on a two-dimensional plane or a three-dimensional curved surface, and a vibration for selecting a plurality of transducer groups at different positions on the transducer arrangement surface. An echo signal is generated by supplying a transmission signal having different characteristics to each of the transducer group selection circuit and the transducer group selected by the transducer group selection circuit, and simultaneously transmitting an ultrasonic beam from each transducer group into the subject. The subject is moved by controlling the selection circuit and moving the position of the transducer group selected for each repetition of ultrasound transmission / reception and controlling the transmission / reception means to transmit / receive ultrasound beams. An ultrasonic diagnostic apparatus including a means for three-dimensionally scanning the inside with an ultrasonic beam is disclosed. In this ultrasonic diagnostic apparatus, ultrasonic beams having different characteristics are simultaneously transmitted from a plurality of transducer groups, and the received ultrasonic echo signals are separated according to the frequency. However, the frequency of the ultrasonic beam is not changed according to the depth of the subject, and an optimal image cannot be obtained in the depth direction.

  Patent Document 7 discloses ultrasonic transmission / reception means having different frequency characteristics, control means for driving the plurality of ultrasonic transmission / reception means, and reception signals output from the plurality of ultrasonic transmission / reception means in the screen. There is disclosed an ultrasonic image processing apparatus that includes a display unit that performs weighting according to a distance from a position corresponding to a transmission / reception unit and displays the synthesized and displayed on one screen. By using such an ultrasonic image processing apparatus, a plurality of ultrasonic images having different frequency characteristics can be combined and displayed as smooth images on the same image. However, in the method of mechanically scanning the ultrasonic probe, it is difficult to acquire an ultrasonic image with good image quality at high speed. In addition, the tissue properties of the subject cannot be imaged.

In Patent Document 8, in order to be able to simultaneously image from the shallow part to the deep part of the subject, the resonance frequency is converted to 1/2 wavelength into a piezoelectric vibrator having a resonance frequency of several tens of MHz. An ultrasonic probe is manufactured by pasting a resonance plate of an integer of the resonance frequency of the child, and the probe, transmission / reception circuit, signal processing circuit, signal separation circuit, image processing circuit, image readout circuit, and display It is disclosed that an ultrasonic inspection apparatus is configured with the apparatus. By using such an ultrasonic inspection apparatus, it is possible to generate an image using a low frequency for a shallow region and using a lower frequency as the depth increases. However, in that case, a special ultrasonic probe is required. Further, there is no mention of imaging the tissue properties of the subject.
Japanese Patent Laid-Open No. 11-290312 JP-A-6-121390 JP 2003-169800 A JP-A-8-289889 JP 2001-333902 A Republished WO01 / 085031 JP-A-8-173420 Japanese Patent Laid-Open No. 9-281093

  Accordingly, in view of the above points, the present invention can transmit an ultrasonic beam having an appropriate frequency according to the depth of the subject, and based on the ultrasonic echo signal of such an ultrasonic beam, the subject An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of imaging not only the shape but also the tissue properties.

  In order to solve the above problems, an ultrasonic diagnostic apparatus according to a first aspect of the present invention is an ultrasonic transducer array including a plurality of ultrasonic transducer groups having different resonance frequencies, and has a predetermined resonance frequency. An ultrasonic transducer array in which an ultrasonic transducer group having a resonance frequency lower than the predetermined resonance frequency is arranged outside the ultrasonic transducer group, and ultrasonic waves transmitted from a plurality of ultrasonic transducer groups, Beam forming means for forming a plurality of ultrasonic beams by focusing to different focal lengths for each of the ultrasonic transducer groups, the focal length of the ultrasonic beams transmitted from the ultrasonic transducer group having a predetermined resonance frequency. On the other hand, an ultrasonic transducer having a resonance frequency lower than the predetermined resonance frequency. Beam forming means for focusing the ultrasonic wave so that the focal length of the ultrasonic beam transmitted from the transducer group becomes longer, and driving for generating a plurality of drive signals for driving each of the plurality of ultrasonic transducer groups Signal generating means, control means for controlling the drive signal generating means so that a plurality of ultrasonic beams are transmitted within a predetermined period, and detection generated by receiving a plurality of ultrasonic transducer groups Signal processing means for outputting a plurality of types of detection signals by performing predetermined signal processing on the signals, and image data for generating image data based on the intensities of the plurality of types of detection signals output from the signal processing means Generating means.

  An ultrasonic diagnostic apparatus according to a second aspect of the present invention is disposed on the outside of the first group of ultrasonic transducers having the first resonance frequency and the first group of ultrasonic transducers. An ultrasonic transducer array including a second group of ultrasonic transducers having a second resonance frequency lower than the first resonance frequency; and ultrasonic waves transmitted from the first group of ultrasonic transducers at a first focal length. The first acoustic lens that forms the first ultrasonic beam by focusing and the ultrasonic waves transmitted from the second group of ultrasonic transducers are focused on a second focal length longer than the first focal length. And a drive signal for generating a plurality of drive signals for driving the second acoustic lens for forming the second ultrasonic beam and the first and second group of ultrasonic transducers. The generating means, the control means for controlling the driving signal generating means so that the first and second ultrasonic beams are transmitted within a predetermined period, and the ultrasonic transducers of the first group and the second group are ultrasonic waves. The signal processing means for outputting the first and second detection signals by performing predetermined signal processing on the detection signal generated by receiving the signal, and the first and second output from the signal processing means Image data generating means for generating image data based on the intensity of the detection signal.

  Furthermore, an ultrasonic diagnostic apparatus according to a third aspect of the present invention is disposed on the outside of the first group of ultrasonic transducers having the first resonance frequency and the first group of ultrasonic transducers, An ultrasonic transducer array including a second group of ultrasonic transducers having a second resonance frequency lower than one resonance frequency, and a plurality of drive signals for driving the first group and the second group of ultrasonic transducers Drive signal generating means for generating a first ultrasonic beam focused on a first focal length, and each of a plurality of drive signals for driving a first group of ultrasonic transducers is predetermined. A compound for driving the second group of ultrasonic transducers to provide a delay time and form a second ultrasonic beam that converges to a second focal length that is longer than the first focal length. A control means for controlling the drive signal generating means so as to give a predetermined delay time to each of the drive signals and to transmit the first and second ultrasonic beams within a predetermined period; Signal processing means for outputting first and second detection signals by performing predetermined signal processing on a plurality of detection signals generated by receiving ultrasonic waves by the second group of ultrasonic transducers; Image data generating means for generating image data based on the intensities of the first and second detection signals output from the processing means.

  According to the present invention, the second ultrasonic transducer having the low resonance frequency is disposed outside the first ultrasonic transducer having the high resonance frequency, and the high frequency ultrasonic wave is focused on the shallow portion of the subject. Since the ultrasonic wave of low frequency is focused on the deep part of the subject, high-resolution ultrasonic image information can be obtained for the shallow part by one transmission / reception of the ultrasonic wave, and sufficient signal is also given for the deep part. Ultrasonic image information having intensity can be obtained. Further, by using echo signals of two types of ultrasonic beams, it is possible to generate frequency image information representing the tissue characteristics of the subject.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. This ultrasonic diagnostic apparatus transmits two types of ultrasonic waves each having two different frequency bands (center frequencies f _H and f _L ) and receives reflected waves (ultrasonic echoes) of those ultrasonic waves. A B-mode image based on the intensity of each detection signal obtained by doing this and a frequency image based on the frequency component of those detection signals are generated.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus according to the present embodiment includes an ultrasonic probe 10, a transmission / reception position determination unit 21, a transmission waveform generation unit 22, and drive signal generation units 23H and 23L. Contains. The ultrasonic probe 10 has an ultrasonic transducer array 1 shown in FIG. 2A is a plan view showing the ultrasonic transducer array 1, and FIG. 2B is a side view showing an ultrasonic probe 10 including the ultrasonic transducer array 1. 2 (c) is a cross-sectional view taken along one-dot chain line II-II shown in FIG.

  As shown in FIG. 2A, the ultrasonic transducer array 1 includes two types of ultrasonic transducers 11 and 12 having different resonance frequencies. Each of these ultrasonic transducers 11 and 12 transmits an ultrasonic beam based on an applied drive signal, receives a propagating ultrasonic echo, and outputs a detection signal. In the present embodiment, a 1.5-dimensional ultrasonic transducer is arranged by arranging a plurality of ultrasonic transducers 12 arranged in a one-dimensional manner outside the plural ultrasonic transducers 11 arranged in a one-dimensional manner. An array 1 is configured. In the present application, the 1.5-dimensional array refers to a one-dimensional array arranged in about several rows (for example, 3 to 5 rows).

  Each of the ultrasonic transducers (also referred to as vibrators) 11 and 12 is, for example, a piezoelectric ceramic represented by PZT (lead zirconate titanate) or PVDF (polyvinylidene difluoride). It is configured by forming electrodes on both ends of a piezoelectric material (piezoelectric body) such as a polymer piezoelectric element represented by When a voltage is applied by sending a pulsed electric signal or a continuous wave electric signal to the electrodes of such a vibrator, the piezoelectric body expands and contracts, and the pulsed ultrasonic wave or continuous wave ultrasonic wave from each vibrator. Is sent. Therefore, as shown in FIG. 2B, by driving each of a plurality of transducers included in a transducer group 101 with a predetermined delay, the ultrasonic waves transmitted from those transducers are driven. By the synthesis, an ultrasonic beam US propagating in a desired direction is formed. Similarly, by sequentially driving the transducer groups 101, 102,... Set by shifting the position, the transmission position of the ultrasonic beam moves in the direction of the arrow. Thereby, the subject can be scanned linearly. Each transducer 11 and 12 expands and contracts by receiving propagating ultrasonic waves and generates an electrical signal. These electric signals are output as ultrasonic detection signals.

As shown in FIG. 2C, in this embodiment, the resonance frequency of the vibrators 11 and 12 is changed by changing the lengths of the vibrators 11 and 12 in the electric field direction. That is, the vibrator 11 of the length L _H has a first resonant frequency, transmitting and receiving ultrasonic waves of a frequency band including the frequency f _H. Moreover, the vibrator 12 having a length L _L (L _L > L _H ) has a second resonance frequency lower than the first resonance frequency, and includes a frequency f _L (f _L <f _H ). Send and receive ultrasonic waves in the frequency band. More preferably, if f _L × 1.5 <f _H <f _L × 10, these frequency bands can be easily separated. In addition, the resonance frequency may be changed by changing the material and width of the vibrator.

  The frequency bands of the ultrasonic waves transmitted from the vibrator 11 and the vibrator 12 are preferably separated from each other, and further, the frequency bands are preferably separated by 2 times or more. For example, when the frequency band of the vibrator 12 is 0.5 MHz to 5 MHz, the frequency band of the vibrator 11 is 10 MHz to 30 MHz. As a result, the sensitivity of the other transducer becomes lower than the ultrasonic wave transmitted from one transducer, so even if echoes with spatially overlapped different types of ultrasound are received, unnecessary signals can be transmitted. It can be easily separated.

Further, as shown in FIG. 2C, a backing layer 13 is disposed on the back surface of the ultrasonic transducer array 1, and an acoustic lens 14 is disposed on the front surface of the ultrasonic transducer array 1. .
The backing layer 13 is formed of a material having a large acoustic attenuation, such as a material in which ferrite or metal powder or ceramic powder is mixed with epoxy resin or rubber, and is generated from the ultrasonic transducer array 1. Attenuate unnecessary ultrasonic waves quickly.

The acoustic lens 14 includes regions 14a to 14c. These regions are each formed into a predetermined shape using silicon rubber or the like. The region 14b of the acoustic lens 14 focuses the ultrasonic wave transmitted from the transducer 11 (aperture width D _H ) on the focal length F _H. In addition, the regions 14a and 14c of the acoustic lens 14 are configured so that the ultrasonic waves transmitted from the two transducers 12 (opening width D _L ) disposed on both outer sides of the transducer 11 are converted into focal lengths F _L (F _L > Focus to F _H ). Here, the acoustic lens 14 may be formed so that the regions 14a to 14c are integrated, as in the present embodiment, or the acoustic lens composed of the region 14b and the acoustic lens composed of the regions 14a and 14c. May be used in combination.

As described above, the acoustic lens 14 is designed to focus the ultrasonic wave with the high frequency f _H on the shallow part of the subject and focus the ultrasonic wave with the low frequency f _L on the deep part of the subject. The frequencies f _H and f _L , focal lengths F _H and F _L , and aperture widths D _H and D _L are defined as follows.

Two vibrators 12 arranged on both outer sides of the vibrator 11, when transmitting only the ultrasonic beam US _L is the inside of the ultrasonic beam US _L immediately after the transmitted sound pressure intensity distribution It becomes a low area. In such a region (hollow region) 15 where the sound pressure intensity distribution is hollow, the ultrasonic beam US _H and the ultrasonic beam US _L are focused by focusing the ultrasonic beam US _H transmitted from the transducer 10. Can be separated spatially.

The radius of the ultrasonic beam is expressed by the following equation (1) using the ultrasonic sound velocity v, the frequency f, the focal length F, and the aperture width D.
Beam radius = 1.22 × (v / f) × F / D (1)
Therefore, the focal lengths F _H and F _L , and so that the beam diameter at the focal point F _H of the ultrasonic beam US _H represented by the equation (1) falls within the hollow region 15 of the ultrasonic beam US _L , and The opening widths _DH and _DL may be set. The range of the hollow region 15, by simulation using a focal length F _L and the opening width D _H and D _L, may be determined.

The ultrasonic beam US _H are once focused at a focal length F _H, then it diverges again, diverging ultrasonic beam US _H is, it is desirable that sufficiently attenuated in the focal length F _L. Thereby, since it is possible to reduce crosstalk between the ultrasonic beam US _L and the ultrasonic beam US _H near focal length F _L. Accordingly, it is necessary to define the focal lengths F _H and F _L from such a viewpoint.

By transmitting such two types of ultrasonic beams, regions R _H , R _HL and R _L having different characteristics according to the distance from the subject are formed on the sound ray. The ultrasonic echo signal acquired from the region _RH mainly includes a high frequency component and has a high distance resolution. Further, since the ultrasonic beam is sufficiently narrowed at a short distance by being transmitted from the central aperture, a high azimuth resolution can be obtained from the region _RH . On the other hand, the echo signal acquired from the region _RL mainly includes a low frequency component and has a sufficient signal strength even when the propagation distance is long. In addition, since the ultrasonic beam is narrowed in the deep part, a good azimuth resolution can be obtained from the region _RL . Furthermore, the ultrasonic echo signal acquired from the region R _HL includes both a high frequency component and a low frequency component. A signal including such a broadband component can be used when generating a frequency image to be described later.

The lengths of these regions R _H , R _HL and R _L can be adjusted by the focal lengths F _H and F _L. For example, the focal lengths F _H and F _L may be set so as to satisfy F _H × 1.5 ≦ F _L ≦ F _H × 3. In this case, an ultrasonic beam suitable for the diagnostic purpose can be formed in a wide region in the depth direction in the subject, and the resolution and reach distance of each ultrasonic beam can be optimized.

Specific examples of the frequencies f _H and f _L and the focal lengths F _H and F _L will be given below. For example, when imaging limbs, an ultrasonic focal length F _H with a frequency f _H ≧ 15 MHz is set in a region about 3 cm deep from the surface, which is skin tissue, and the depth at which bones and tendons are present. the 3cm~7cm about in the area, setting the focal length _{F L} of the ultrasonic frequencies _f L = _0.5MHz~4MHz. In addition, when imaging the torso, etc., an ultrasonic focal length F _H of a frequency f _H = 5 MHz to 15 MHz is set in a region having a depth of about 5 cm to 10 cm where a mammary gland, a thyroid gland, a carotid artery, and the like exist. , about 10cm or more in the region depth exists abdomen, heart, setting the focal length _{F L} of the ultrasonic frequencies _f L = _2MHz~4MHz.

Referring to FIG. 1 again, the transmission / reception position determination unit 21 sequentially sets the transmission position of the ultrasonic beam and the reception direction of the ultrasonic echo.
As shown in FIGS. 2A and 2C, the transmission waveform creation unit 22 sets driven transducer groups 101, 102,... According to the transmission position set in the transmission / reception position determination unit 21. In addition, a delay time given to each of the plurality of transducers 11 and 12 included in the set transducer group is set. The transmission waveform generator 22 sets the frequencies of drive signals generated by drive signal generators 23H and 23L, which will be described later, in order to transmit ultrasonic waves in a predetermined frequency band from the plurality of transducers 11 and 12, respectively. .

  Each of the drive signal generators 23H and 23L includes a plurality of drive signal generation circuits that respectively generate drive signals applied to the plurality of vibrators, and a plurality of delays that give a desired delay to the drive signals generated by the drive signal generation circuit. Circuit. These delay circuits delay the drive signal based on the delay time set in the transmission waveform creation unit 22.

The drive signal generation unit 23H and the drive signal generation unit 23L include drive signal generation circuits that generate drive signals in different bands. That is, the drive signal generation unit 23H is to drive each transducer 11, it generates a driving signal including a component of the frequency f _H. On the other hand, the drive signal generation unit 23L, in order to drive each vibrator 12 generates a driving signal including a component of the frequency f _L.
Under the control of the control unit 25, the drive signal generators 23H and 23L generate drive signals within a predetermined period (for example, simultaneously), so that the ultrasonic beam US _H and the ultrasonic beam US _H and US _L is transmitted simultaneously or nearly simultaneously.

  In addition, the ultrasonic diagnostic apparatus according to the present embodiment includes an operation console 24, a control unit 25 configured by a CPU, and a recording unit 26 such as a hard disk. The control unit 25 controls each unit of the ultrasonic diagnostic apparatus based on the operation of the operator using the console 24. The recording unit 26 records a program for causing the CPU constituting the control unit 25 to execute various operations, a frequency characteristic in transmission / reception of the ultrasonic transducer, and the like.

  Furthermore, the ultrasonic diagnostic apparatus according to the present embodiment includes signal processing units 31H and 31L, reception focus processing units 32H and 32L, A / D converters 33H and 33L, primary storage units 34H and 34L, B Mode image data generation units 35H and 35L, frequency analysis units 36H and 36L, an extracted frequency calculation unit 37, an automatic frequency determination unit 38, a frequency image data generation unit 39, a frequency image display region determination unit 40, An image composition unit 41, a secondary storage unit 42, an image processing unit 43, a display unit 44, and a transmission beam automatic changing unit 45 are included.

The signal processing unit 31H has a plurality of channels corresponding to the plurality of ultrasonic transducers 11, and the signal processing unit 31L has a plurality of channels corresponding to the plurality of ultrasonic transducers 12, respectively. Each channel of the signal processing units 31H and 31L takes in a detection signal output from the corresponding ultrasonic transducer at a predetermined timing under the control of the control unit 25. For example, the signal processing unit 31H captures a signal from the start of reception until a time corresponding to a predetermined depth (for example, up to the region _{RHL in} FIG. 2). On the other hand, the signal processing unit 31L captures a signal from a time corresponding to the depth F _L × 0.5 to a time corresponding to a predetermined depth (for example, up to the region R _{L in} FIG. 2). In this manner, by controlling the detection signal capture timing, it is possible to acquire a signal representing an ultrasonic echo reflected at a predetermined depth of the subject. Further, each of the channels of the signal processing units 31H and 31L amplifies the captured detection signal and corrects attenuation by distance using an STC (sensitivity time control) amplifier.

  The reception focus processing units 32H and 32L perform reception focus processing by giving predetermined delays to the plurality of detection signals processed in the signal processing units 31H and 31L and adding them to each other. By this reception focus processing, a sound ray signal in which the focus of the ultrasonic echo is narrowed is formed. Note that the reception focus process may be performed before correction by the STC amplifier.

  The A / D converters 33H and 33L generate sound ray data by digitally converting the sound ray signals subjected to reception focus processing. The sampling frequency of the A / D converters 33H and 33L is required to be at least about 10 times the ultrasonic frequency, and is preferably 16 times the ultrasonic frequency or more. The resolution of the A / D converter is preferably 10 bits or more. In order to reduce or eliminate aliasing (folding distortion), it is desirable to perform anti-aliasing filter processing such as low-pass filter processing on the sound ray signal before performing A / D conversion. The A / D conversion may be performed on the detection signal before the reception focus process is performed.

The primary storage units 34H and 34L store sound ray data generated by the A / D converters 33H and 33L.
B-mode image data generating unit 35H performs envelope detection processing on the sound ray data stored in the primary storage unit 34H, a high frequency f _H of the B-mode image obtained based on the ultrasound (B Image data representing the mode image H) is generated. On the other hand, the B-mode image data generation unit 35L performs envelope detection processing on the sound ray data stored in the primary storage unit 34L, and is obtained on the basis of the ultrasound of the low frequency f _L. Image data representing (B-mode image L) is generated.

On the other hand, the frequency analysis units 36H and 36L are provided for each region included in the waveform represented by the sound ray data stored in the primary storage units 34H and 34L (that is, each region representing the depth direction of the subject). A plurality of frequency components included in the broadband detection signal are calculated by Fourier transform. In the case of performing fast Fourier transform (FFT) in the frequency analysis units 36H and 36L, the number of data constituting the sound ray data is 2 ^N pieces (N is an integer) before the frequency analysis units 36H and 36L. An interpolation processing unit for performing interpolation is provided.

  The extracted frequency calculation unit 37 extracts a frequency component used for displaying the frequency image based on the plurality of frequency components calculated by the frequency analysis units 36H and 36L, and uses the extracted frequency component to perform predetermined processing. The arithmetic processing is performed. As a result, a feature value representing information specific to the tissue in each region in the depth direction of the subject is obtained. For example, the extracted frequency calculation unit 37 may extract and output one frequency component having a high intensity from among a plurality of frequency components, or extract a plurality of frequency components, and the difference or ratio between them. As described above, the relative relationship of intensity may be calculated and output. In this way, when focusing on a portion where the ultrasonic echo intensity is high, the specific tissue is emphasized and displayed by determining the frequency component based on the characteristics of the frequency characteristics of the specific tissue in that portion. can do. On the contrary, it is possible to reduce the speckle component generated as a result of adding and interfering with many weak echoes by determining the frequency component by paying attention to the portion where the ultrasonic echo intensity is small. In any case, the SN ratio can be improved. Further, when calculating the relative values of a plurality of frequency components, a two-dimensional distribution of a specific tissue can be accurately obtained based on the relative values.

  The attention frequency automatic determination unit 38 automatically determines a notable frequency used in the extraction frequency calculation unit 37. At that time, the attention frequency automatic determination unit 38 may automatically determine a plurality of predetermined frequencies. For example, the attention frequency automatic determination unit 38 has at least a large peak or dip in all or a part of the region in the depth direction of the subject among the plurality of frequency components calculated by the frequency analysis units 36H and 36L. One frequency may be automatically determined, or a combination of frequency components separated by a predetermined value may be used.

  Further, the frequency characteristic in transmission / reception of the ultrasonic transducer is recorded in the recording unit 26, and under the control of the control unit 25, the amplitude of the drive signal and the amplitude of the detection signal are corresponding to the frequency characteristic of the ultrasonic transducer. If the correction is made, the frequency component can be extracted more accurately. Further, more information can be obtained by extracting not only the frequency component of the detection signal but also the phase component and using it for generating an ultrasonic image.

  The frequency image data generation unit 39 generates frequency image data based on the feature amount output from the extraction frequency calculation unit 37. In that case, the region on the frequency image corresponding to each region in the depth direction of the subject may be displayed by color or luminance depending on the output value from the extraction frequency calculator 37.

  The frequency image display region determination unit 40 determines a region (display region) of a frequency image that is combined with the B-mode image and displayed based on the calculation result in the extraction frequency calculation unit 37. For example, when the feature amount obtained by the extracted frequency calculation unit 37 is a difference between a plurality of frequency components, an area where the difference is a predetermined value or more is set as a display area. Thereby, a tissue having a specific property can be displayed superimposed on the B-mode image.

  The image composition unit 41 is generated by the B mode image data generated by the B mode image data generation unit 35H, the B mode image data generated by the B mode image data generation unit 35L, and the frequency image data generation unit 39. Composite image data is generated by performing predetermined arithmetic processing on the frequency image data. This composite image data represents, for example, an image obtained by joining a B-mode image H and a B-mode image L and overlaying a frequency image thereon. The areas for displaying these three types of images may be manually designated by the operator using the console 24, or may be automatically designated based on predetermined conditions. For the frequency image, the display area determined by the frequency image display area determination unit 40 may be used. When designating the display area of the B-mode image H and the B-mode image L, the following method can be considered. For example, the B-mode image H and the B-mode image L may be specified to be connected with a predetermined depth as a boundary, or specified to be connected with an area having a predetermined signal value or more as a boundary. Also good. Alternatively, an area where the B-mode image H and the B-mode image L overlap may be specified so that the image data with the larger signal value is used.

  The secondary storage unit 42 stores the image data output from the image composition unit 41. The image processing unit 43 performs various types of image processing on the image data stored in the secondary storage unit 42. The display unit 44 includes, for example, a display device such as a CRT or LCD, and displays an ultrasonic image based on the image data subjected to image processing by the image processing unit 43.

Based on the determination result in the frequency image display area determination unit 40, the transmission beam automatic change unit 45, if necessary, information for changing the frequencies of the ultrasonic beams US _H and US _L to be transmitted next, The data is output to the transmission / reception position determination unit 21.

FIG. 3 schematically shows an ultrasonic image generated by the ultrasonic diagnostic apparatus according to the present embodiment. This ultrasonic image is obtained by ultrasonic imaging of the upper limb including the joint. Such a region is often an imaging target mainly in the shaping field.
In FIG. 3, a B mode image H representing the region R ₁ from the surface of the subject 110 to the surface of the bone portion 112 and a B mode image L representing the region R ₂ deeper than the surface of the bone portion 120 are combined. ing. This makes it possible to clearly define both a shallow region where high resolution is required, such as skin tissue and muscle tissue 111, and a region where ultrasound is generally difficult to transmit, such as the inside of the bone portion 112. Can be imaged. Furthermore, by superimposing the frequency images obtained using the ultrasonic waves with the frequency f _{H and} the ultrasonic waves with the frequency f _L (region R ₃ ), the tissue properties of the tendon and ligament 113, the cartilage 114, and the like are clearly defined. Can be displayed separately.

  As described above, according to the present embodiment, two types of ultrasonic beams are transmitted at the same time while shifting the focal length, so that an ultrasonic echo signal having an appropriate frequency can be obtained according to the depth in the subject. it can. That is, an ultrasonic echo signal having a high distance resolution and azimuth resolution regarding the shallow portion in the subject and an ultrasonic echo signal having a sufficient signal intensity and azimuth resolution regarding the deep portion in the subject can be acquired in a short time. Therefore, it is possible to generate an ultrasonic image with good image quality over the entire imaging region without reducing the frame rate. In addition, by using different frequencies, it is possible to image tissue properties that cannot be distinguished when using a single frequency.

In the first embodiment of the present invention described above, two types of ultrasonic waves having different frequency bands are used, but three or more types of ultrasonic waves may be used. In this case, for example, as shown in FIG. 4A, the third transducer 16 that transmits the ultrasonic wave US _LL having a frequency lower than the frequency f _{L is provided} on both outer sides of the plurality of transducers 12. The arranged ultrasonic transducer array 2 is manufactured, and as shown in FIG. 4B, the ultrasonic wave US _LL transmitted from the third transducer 16 is placed on the front surface of the ultrasonic transducer array 2 and the focal length. An acoustic lens 17 that converges farther than F _L (focal length F _LL ) is provided. In addition, a transmission system and reception system processing unit corresponding to the third transducer 16 may be further provided in the main body of the ultrasonic diagnostic apparatus.

  In this embodiment, a linear array is used, but other types of arrays may be used. For example, an annular array in which a plurality of circular or annular transducers having different radii are arranged concentrically may be used. In that case, a circular or annular vibrator that transmits high-frequency ultrasonic waves is disposed inside the concentric circle, and an annular vibrator that transmits low-frequency ultrasonic waves is disposed outside the concentric circle. At the same time, an acoustic lens for focusing the ultrasonic beams having the respective frequencies at different distances is provided. Alternatively, a convex array in which a plurality of vibrators are arranged in a concave shape may be used.

In the present embodiment, since the sensitivity to a certain frequency differs depending on the type of the vibrator, the ultrasonic wave with the frequency f _H is detected by the vibrator 11, and the ultrasonic wave with the frequency f _L is detected by the vibrator 12. However, an ultrasonic wave having a frequency f _L may be transmitted from the vibrator 12 and the vibrator 11 may detect a harmonic signal (harmonic signal) generated in a deep part such as the inside of a bone. By extending the acquisition of the detection signal from the transducer 11 to the arrival timing of the ultrasonic echo from the deep part, it is possible to separate the fundamental wave and the harmonics without using a filter or the like. A harmonic image may be generated based on the harmonic signal acquired in this manner, and displayed on the corresponding display area on the B-mode image.

Next, an ultrasonic diagnostic apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram showing the ultrasonic diagnostic apparatus according to this embodiment.
The ultrasonic diagnostic apparatus according to this embodiment is shown in FIG. 5 in place of the ultrasonic probe 10, the transmission / reception position determination unit 21, the transmission waveform creation unit 22, and the transmission beam automatic change unit 45 shown in FIG. An ultrasonic probe 50, a transmission / reception position determination unit 61, a transmission waveform creation unit 62, and a transmission beam automatic change unit 65, and a transmission delay pattern storage unit 63 and a reception delay pattern control unit. 64. Other configurations are the same as those described in the first embodiment of the present invention.

The ultrasonic probe 50 has an ultrasonic transducer array 3 shown in FIG. FIG. 6A is a plan view showing the ultrasonic transducer array 3, and FIG. 6B is a side view showing an ultrasonic probe 50 including the ultrasonic transducer array 3.
As shown in FIG. 6A, the ultrasonic transducer array 3 includes a plurality of transducers 51 arranged in 1.5 dimensions and a plurality of transducers arranged in 1.5 dimensions on both outer sides thereof. 52. Each transducer 51 transmits ultrasonic waves in a frequency band including the frequency f _H , and each transducer 52 transmits ultrasonic waves in a band including the frequency f _L (f _L <f _H ).

As shown in FIG. 6B, in this embodiment, instead of providing an acoustic lens on the front surface of the ultrasonic transducer array 3, the ultrasonic beam is focused by controlling each transducer electronically. Forming. That is, as shown in (c) of FIG. 6, by driving giving a predetermined delay time to a plurality of transducers 52a~52j T1, T2, ..., respectively, include a hollow region 54, focused at the distance _{F L} it is possible to form an ultrasonic beam US _L to. Similarly, by giving predetermined delay times T1 ′, T2 ′,... To each of the plurality of vibrators 51a to 51e arranged at the center, and driving them, the super-focusing to the distance F _H in the hollow region 54 is achieved. it is possible to form the acoustic beam US _H. Note that the relationship between the frequency of the two types of ultrasonic waves to be transmitted, the focal length, and the aperture of the ultrasonic transducer array is the same as that described in the first embodiment of the present invention.

In the ultrasonic transducer array 3, the vibrators 51 and 52 may be arranged so that the ultrasonic transmission surfaces are aligned as shown in FIG. 6B, or as shown in FIG. The transducers 51 and 52 may be arranged so that the ultrasonic transmission surface of the transducer 51 is lower than the ultrasonic transmission surface of the transducer 52. In the latter case, the focal point _{F H} of the ultrasonic beam US _H, easily formed into a hollow region 54 of the ultrasound beam US _L. A backing layer 53 is disposed on the back surface of the ultrasonic transducer array 3.

Referring to FIG. 5 again, the transmission / reception position determination unit 61 sequentially sets the transmission position and focal length of the ultrasonic beam and the reception direction of the ultrasonic echo.
The transmission delay pattern storage unit 63 stores a plurality of transmission delay patterns used when forming an ultrasonic beam. The transmission waveform creation unit 62 sets the transducer groups 201, 202,... To be driven according to the transmission position set in the transmission / reception position determination unit 61 and sets the focal length set in the transmission / reception position determination unit 61. Based on this, a predetermined pattern is selected from the plurality of delay patterns stored in the transmission delay pattern storage unit 63, and the plurality of transducers 51 and 52 included in the set transducer group based on the pattern is selected. The delay time given to each is set.

The reception delay pattern control unit 64 controls the delay patterns given to the plurality of detection signals in the reception focus processing units 32H and 32L based on the reception direction and focal length of the ultrasonic waves set in the transmission / reception position determination unit 61.
Based on the determination result in the frequency image display area determination unit 40, the transmission beam automatic change unit 65 next changes the frequency and focal length of the ultrasonic beams US _H and US _L to be transmitted if necessary. Is sent to the transmission / reception position determination unit 61. For example, in the case where the display area of the frequency image is narrow and the information obtained by the frequency image is small, in order to widen the range of the B-mode image obtained by the ultrasonic beam of one frequency, FIG. Adjust the distance between the focal lengths F _H and F _L shown.

  As described above, according to the present embodiment, since the focal lengths of the two types of ultrasonic beams can be changed, the ultrasonic waves having an appropriate frequency are irradiated to each depth in the subject. It becomes possible to generate an ultrasonic image and a frequency image based on the ultrasonic echo obtained thereby.

Here, again, referring to FIG. 6 (b), in the present embodiment may be double impact ultrasonic beam US _H. That is, transmitted first ultrasonic beam US _H and ultrasonic beam US _L at the same time, the ultrasonic beam US _L or ultrasonic echo (i.e., ultrasound echo from deep) is propagated within the object during the ultrasonic beam US _H, transmits again shifting the focal length. As described above, it is possible to further improve the resolution by performing dynamic focusing on the shallow portion in the subject with a short drive signal generation interval (for example, 1/2).

Also in this embodiment, three or more types of ultrasonic waves having different frequencies may be used. In that case, third, fourth, and fourth ultrasonic waves having a center frequency lower than the frequency f _L are transmitted to both outer sides of the plurality of 1.5-dimensionally arranged transducers 52 shown in FIG. Are arranged in a 1.5-dimensional manner, and the drive timing of each transducer may be electronically controlled so that the focal length of the ultrasonic beam becomes longer as the transducer is placed outside the array. .

Next, a modification of the ultrasonic diagnostic apparatus according to the second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 7A, the ultrasonic transducer array 4 may be manufactured by arranging a plurality of ultrasonic transducer arrays 3 shown in FIG. In this case, as shown in FIG. 7B, the number of ultrasonic beams transmitted at a time can be increased. Therefore, since ultrasonic information regarding a wide area can be acquired by transmitting and receiving ultrasonic waves once, it is possible to scan a three-dimensional area in the subject at high speed.

Alternatively, a two-dimensional ultrasonic transducer array 5 shown in FIG. 8 may be used instead of the ultrasonic transducer array 3 shown in FIG. The ultrasonic transducer array includes a plurality of transducers 71 to transmit ultrasonic waves having a center frequency f _H, and a plurality of transducers 72 to transmit ultrasonic waves having a center frequency f _L. A transducer group 73 is formed by a plurality of transducers 71 arranged in a small region having an ultrasonic transmission surface and a transducer 72 arranged so as to surround the transducers 71.

By electronically controlling the drive signal applied to each of the plurality of transducer groups 73, two types of ultrasonic beams having different frequencies can be transmitted simultaneously so as to be focused at different distances. At that time, the focal length of each ultrasonic beam can be changed by changing the delay pattern of the drive signal.
In the case of using this modification, it is possible to increase the number of ultrasonic beams transmitted at a time and scan the three-dimensional region in the subject at higher speed.

  Furthermore, an ultrasonic beam propagating in a desired direction may be formed by changing the delay pattern of the drive signal applied to each of the transducers 71 and 72. When changing the transmission direction of the ultrasonic beam, it is possible to scan a three-dimensional region in the subject without mechanically moving the ultrasonic probe.

  An annular array may be fabricated by concentrically arranging a plurality of circular or annular vibrators having different radii. In that case, a plurality of circular or annular transducers transmitting high frequency ultrasonic waves are arranged inside the concentric circles, and a plurality of annular vibrations transmitting low frequency ultrasonic waves outside the concentric circles. Place a child. And by controlling these vibrators electronically, the focal length of the ultrasonic beam transmitted therefrom can be changed.

  Alternatively, a two-dimensional array in which a plurality of types of transducers that transmit a plurality of different frequencies may be randomly arranged two-dimensionally. Even in this case, the focal length of the transmitted ultrasonic beam can be changed for each frequency of the ultrasonic beam by electronically controlling the drive timing for each type of transducer. In this way, by transmitting the ultrasonic beam with multiple stages of focus, it is possible to irradiate the entire imaging region with a plurality of ultrasonic beams having different frequencies.

  INDUSTRIAL APPLICABILITY The present invention can be used in an ultrasonic diagnostic apparatus that generates an ultrasonic image used for diagnosis by transmitting and receiving ultrasonic waves and imaging an organ, bone, and the like in a living body.

1 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. It is a figure for demonstrating the structure of the probe for ultrasonic waves shown in FIG. It is a schematic diagram showing the ultrasonic image produced | generated by the ultrasonic diagnosing device shown in FIG. It is a figure for demonstrating the modification of the probe for ultrasonic waves shown in FIG. It is a block diagram which shows the structure of the ultrasonic diagnosing device which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the structure of the probe for ultrasonic waves shown in FIG. It is a figure for demonstrating the modification of the probe for ultrasonic waves shown in FIG. It is a figure for demonstrating the 2nd modification of the probe for ultrasonic waves shown in FIG.

Explanation of symbols

1-5 Ultrasonic transducer array 10, 50 Ultrasonic probe 11, 12, 16, 51, 52, 71, 72 Ultrasonic transducer (vibrator)
13, 53 Backing layers 14, 17 Acoustic lenses 14a to 14c Regions 15, 54 Hollow regions 21, 61 Transmission / reception position determination units 22, 62 Transmission waveform generation units 23H, 23L Drive signal generation unit 24 Console 25 Control unit 26 Recording unit 31H , 31L Signal processing unit 32H, 32L Reception focus processing unit 33H, 33L A / D converter 34H, 34L Primary storage unit 35H, 35L B-mode image data generation unit 36H, 36L Frequency analysis unit 37 Extraction frequency calculation unit 38 Frequency of interest Automatic determination unit 39 Frequency image data generation unit 40 Frequency image display area determination unit 41 Image composition unit 42 Secondary storage unit 43 Image processing unit 44 Display units 45 and 65 Transmission beam automatic change unit 63 Transmission delay pattern storage unit 64 Reception delay pattern Control units 73, 101, 102,..., 201, 202,. Subject 111 Skin tissue and muscle tissue 112 Bone 113 Tendon and ligament 114 Cartilage

Claims (13)

An ultrasonic transducer array including a plurality of ultrasonic transducer groups having different resonance frequencies, and an ultrasonic wave having a resonance frequency lower than the predetermined resonance frequency outside the ultrasonic transducer group having the predetermined resonance frequency An ultrasonic transducer array in which transducer groups are arranged;
Beam forming means for forming a plurality of ultrasonic beams by focusing the ultrasonic waves transmitted from the plurality of ultrasonic transducer groups at different focal lengths for each ultrasonic transducer group, and having a predetermined resonance frequency. The focal length of the ultrasonic beam transmitted from the ultrasonic transducer group having a resonance frequency lower than the predetermined resonance frequency is longer than the focal length of the ultrasonic beam transmitted from the ultrasonic transducer group having Beam forming means for focusing the ultrasonic wave,
Drive signal generating means for generating a plurality of drive signals for driving each of the plurality of ultrasonic transducer groups;
Control means for controlling the drive signal generating means so that the plurality of ultrasonic beams are transmitted within a predetermined period;
Signal processing means for outputting a plurality of types of detection signals by performing predetermined signal processing on detection signals generated when the plurality of ultrasonic transducer groups receive ultrasonic waves, and
Image data generating means for generating image data based on the intensity of a plurality of types of detection signals output from the signal processing means;
An ultrasonic diagnostic apparatus comprising: A first group of ultrasonic transducers having a first resonance frequency, and a second group having a second resonance frequency lower than the first resonance frequency, disposed outside the first group of ultrasonic transducers. An ultrasonic transducer array comprising:
A first acoustic lens that forms a first ultrasonic beam by focusing ultrasonic waves transmitted from the first group of ultrasonic transducers to a first focal length;
A second acoustic lens that forms a second ultrasonic beam by focusing the ultrasonic waves transmitted from the second group of ultrasonic transducers to a second focal length longer than the first focal length;
Drive signal generating means for generating a plurality of drive signals for driving the ultrasonic transducers of the first group and the second group;
Control means for controlling the drive signal generating means so that the first and second ultrasonic beams are transmitted within a predetermined period;
Signal processing means for outputting first and second detection signals by performing predetermined signal processing on detection signals generated when the ultrasonic transducers of the first group and second group receive ultrasonic waves, respectively; ,
Image data generating means for generating image data based on the intensities of the first and second detection signals output from the signal processing means;
An ultrasonic diagnostic apparatus comprising: A first group of ultrasonic transducers having a first resonance frequency, and a second group having a second resonance frequency lower than the first resonance frequency, disposed outside the first group of ultrasonic transducers. An ultrasonic transducer array comprising:
Drive signal generating means for generating a plurality of drive signals for driving the ultrasonic transducers of the first group and the second group;
In order to form a first ultrasonic beam focused at a first focal length, a predetermined delay time is given to each of a plurality of drive signals for driving the first group of ultrasonic transducers, In order to form a second ultrasonic beam that is focused to a second focal length that is longer than the focal length, a predetermined delay time is applied to each of a plurality of drive signals for driving the second group of ultrasonic transducers. And a control means for controlling the drive signal generating means so that the first and second ultrasonic beams are transmitted within a predetermined period;
Signal processing for outputting first and second detection signals by performing predetermined signal processing on a plurality of detection signals generated when the ultrasonic transducers of the first group and the second group receive ultrasonic waves, respectively. Means,
Image data generating means for generating image data based on the intensities of the first and second detection signals output from the signal processing means;
An ultrasonic diagnostic apparatus comprising:   The control means is different from the first focal length depending on the ultrasonic wave transmitted from the first group of ultrasonic transducers within a predetermined period from the time when the first and second ultrasonic beams are transmitted. The ultrasonic diagnostic apparatus according to claim 3, wherein the drive signal generation unit is controlled so that an ultrasonic beam focused on a distance is formed.   The first group of ultrasonic transducers transmits and receives ultrasonic waves in a first frequency band including the first resonance frequency, and the second group of ultrasonic transducers includes a second frequency including the second resonance frequency. The ultrasonic diagnostic apparatus of any one of Claims 2-4 which transmits / receives the ultrasonic wave of this frequency band.   The ultrasonic diagnostic apparatus according to claim 5, wherein the first frequency band and the second frequency band are separated from each other.   The ultrasonic diagnostic apparatus according to claim 2, wherein the first resonance frequency is greater than twice the second resonance frequency.   The ultrasonic diagnostic apparatus according to claim 2, wherein the second focal length is 1.5 times or more and 3 times or less of the first focal length.   3. The image processing apparatus according to claim 2, further comprising second image data generation means for generating second image data based on a plurality of frequency components included in the first and second detection signals output from the signal processing means. The ultrasonic diagnostic apparatus of any one of -8.   The second image data generating means generates a plurality of frequency components included in the first and second detection signals relating to a region where the first ultrasonic beam and the second ultrasonic beam overlap spatially. The ultrasonic diagnostic apparatus according to claim 9, wherein the second image data is generated based on the second image data.   The said 2nd image data production | generation means selects the at least 1 frequency component which has a peak or a dip from the several frequency component contained in the said 1st and 2nd detection signal. Ultrasound diagnostic equipment.   The second image data generation unit generates second image data based on a relative relationship between intensities of a plurality of predetermined frequency components included in the first and second detection signals. The ultrasonic diagnostic apparatus according to any one of the above.   The ultrasonic diagnostic apparatus according to claim 9, further comprising a composite image data generation unit configured to generate composite image data based on the first image data and the second image data.

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