JP2012161448A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus capable of providing an ultrasonic image based on tertiary waves by extracting the tertiary waves while removing basic waves in reflected waves from a subject to be tested.SOLUTION: The ultrasonic diagnostic apparatus includes: a piezoelectric part for receiving and converting reflected ultrasonic waves to electric signals, the reflected ultrasonic waves generated from the ultrasonic waves transmitted to and reflected from the subject to be tested; a harmonics extracting part; and an image processing part. The ultrasonic diagnostic apparatus prepares a first reflected wave being the electric signal converted by the piezoelectric part from the reflected ultrasonic wave corresponding to the single transmission of the ultrasonic wave, and having phase changed by delay means, and a second reflected wave being the electric signal converted by the piezoelectric part from the reflected ultrasonic wave corresponding to the single transmission of the ultrasonic wave, and having a phase changed by delay means for providing identical phase change regardless of its degree. The ultrasonic diagnostic apparatus extracts harmonic components by adding the first reflected wave and the second reflected wave so as to balance basic wave components thereof wherein the first reflected wave is shifted from the second reflected wave at 180 degrees in phase.

Description

  The present invention relates to an ultrasonic diagnostic apparatus that generates ultrasonic images by transmitting and receiving ultrasonic waves in a subject.

  Ultrasound generally refers to sound waves of 16000 Hz or higher, and can be examined non-destructively, harmlessly and in substantially real time, and thus is applied to various fields such as defect inspection and disease diagnosis. For example, an ultrasound that scans the inside of the subject with ultrasound and images the internal state of the subject based on a reception signal generated from the reflected wave (echo) of the ultrasound coming from inside the subject. There is a diagnostic device. This ultrasonic diagnostic apparatus is smaller and less expensive for medical use than other medical imaging apparatuses, has no radiation exposure such as X-rays, is highly safe, and has a blood flow utilizing the Doppler effect. It has various features such as display capability. For this reason, an ultrasonic diagnostic apparatus includes a circulatory system (eg, coronary artery of the heart), a digestive system (eg, gastrointestinal), an internal system (eg, liver, pancreas, and spleen), and a urinary system (eg, kidney and bladder). Widely used in obstetrics and gynecology.

  An ultrasonic probe that transmits and receives ultrasonic waves to and from a subject is used in the ultrasonic diagnostic apparatus. An ultrasonic probe uses a piezoelectric phenomenon to generate an ultrasonic wave by mechanical vibration based on an electric signal transmitted, and receives an ultrasonic reflected wave caused by an acoustic impedance mismatch inside the subject. A plurality of piezoelectric elements that generate received electrical signals are provided, and the plurality of piezoelectric elements are two-dimensionally arranged in an array, for example.

  In recent years, research has been conducted on harmonic imaging (Harmonic Imaging) technology that forms an image of the internal state of a subject by using harmonic components instead of the fundamental component of the ultrasound transmitted from the ultrasound probe into the subject. Have been developed. In the harmonic imaging technology, the side lobe level is smaller than the fundamental wave component level, the S / N ratio (Signal to Noise ratio) is improved, the contrast is improved, and the beam width is narrowed by increasing the frequency. The lateral resolution is improved, the sound pressure is small and the fluctuation of the sound pressure is small at short distances, so that multiple reflections are suppressed. Compared to the case, it has various advantages such as a large depth speed. (For example, refer to Patent Documents 1 and 2).

  In the harmonic imaging technology, there is a demand for removing a fundamental wave component and extracting a harmonic component. In response to this requirement, for example, a technique is disclosed in which a secondary wave is extracted by forming two transmission waves whose fundamental waves are 180 degrees out of phase and adding these reflected waves to remove the fundamental wave component. (For example, see Patent Document 3)

Japanese Patent Laid-Open No. 10-118065 JP 2007-185525 A JP 2010-017406 A

  With the technique disclosed in Patent Document 3, a secondary wave can be extracted, but a more preferable tertiary wave cannot be extracted in ultrasonic diagnosis.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus that realizes an ultrasonic image based on a tertiary wave by extracting a tertiary wave while removing a fundamental wave from a reflected wave from a subject.

  The above object is achieved by the invention described below.

1. A piezoelectric unit that transmits ultrasonic waves to a subject and receives reflected ultrasonic waves generated by the reflection of the ultrasonic waves at the subject and converts them into electrical signals; and
A harmonic extraction unit for extracting at least an electric signal of a harmonic component contained in the electric signal;
An image processing unit for generating an ultrasonic image in the subject from the electrical signal of the harmonic component;
An ultrasonic diagnostic apparatus comprising:
An electrical signal converted by the piezoelectric unit from reflected ultrasound corresponding to one transmission of ultrasonic waves, corresponding to a first reflected wave whose phase has been changed by a delay means, and corresponding to one transmission of ultrasonic waves A second reflected wave that is an electrical signal converted from the reflected ultrasonic wave by the piezoelectric unit, the phase of which is changed by phase-shifting means that causes the same phase change regardless of the order, and
A harmonic component is extracted by offsetting the fundamental component by adding the first reflected wave and the second reflected wave by making the phases of the first reflected wave and the second reflected wave 180 degrees different from each other. An ultrasonic diagnostic apparatus characterized by the above.

2. A piezoelectric unit that transmits ultrasonic waves to a subject and receives reflected ultrasonic waves generated by the reflection of the ultrasonic waves at the subject and converts them into electrical signals; and
A harmonic extraction unit for extracting at least an electric signal of a harmonic component contained in the electric signal;
An image processing unit for generating an ultrasonic image in the subject from the electrical signal of the harmonic component;
An ultrasonic diagnostic apparatus comprising:
A first reflected wave that is an electric signal converted by the piezoelectric unit from a reflected ultrasonic wave corresponding to the transmission of the first transmission wave, and an electric signal converted by the piezoelectric unit from a reflected ultrasonic wave corresponding to the transmission of the second transmission wave And a second reflected wave that is
The phase of the second reflected wave is changed by phase shifting means that brings about the same phase change regardless of the order,
By matching the timings of the first transmission wave and the second transmission wave to a predetermined timing, the fundamental waves of the first reflected wave and the second reflected wave are different from each other by 180 degrees. An ultrasonic diagnostic apparatus, wherein a harmonic component is extracted by adding a second reflected wave to cancel a fundamental wave component.

  3. 3. The ultrasonic diagnostic apparatus according to 1 or 2, wherein the phase shift means is a digital filter.

  4). 4. The ultrasonic diagnostic apparatus according to 3 above, wherein the digital filter is an FIR filter.

  5). 5. The ultrasonic diagnostic apparatus according to 3 or 4, wherein the digital filter changes a phase by 90 degrees.

  6). 6. The ultrasonic diagnostic apparatus according to any one of 1 to 5, wherein the extracted harmonic component is a third harmonic.

  By extracting the tertiary wave while removing the fundamental wave from the reflected wave from the subject, it is possible to provide an ultrasonic diagnostic apparatus that realizes an ultrasonic image based on the tertiary wave.

1 is a schematic diagram showing an external configuration of an ultrasonic diagnostic apparatus S according to an embodiment. 1 is a block diagram showing an electrical configuration of an ultrasonic diagnostic apparatus S according to an embodiment. 1 is a schematic diagram illustrating a configuration of an ultrasound probe 2 of an ultrasound diagnostic apparatus S according to an embodiment. It is a schematic diagram which shows the relationship of the phase of the harmonic generate | occur | produced in the measurement location of the subject H which transmitted the ultrasonic wave. It is a figure which shows the phase relationship of the fundamental wave of a synthetic | combination wave and the 3rd-order wave which added the 1st reflected wave, the 2nd reflected wave, and synthesize | combined these. It is a block diagram of the part which concerns on reception of the ultrasonic diagnosing device for implement | achieving the phase relationship shown in FIG. It is a flowchart of operation | movement of the part which concerns on reception of the ultrasonic diagnosing device of 1st Embodiment. It is a schematic diagram which shows the phase relationship from the fundamental wave of the synthetic | combination wave which combined the 1st reflected wave and the 2nd reflected wave, and these, and the tertiary wave. It is a block diagram of the part which concerns on reception of the ultrasonic diagnosing device of 2nd Embodiment. It is a flowchart of operation | movement of the part which concerns on reception of the ultrasonic diagnosing device of 2nd Embodiment. It is a schematic diagram which shows the phase relationship of the fundamental wave of a synthetic | combination wave and the 3rd-order wave which combined the 1st reflected wave and the 2nd reflected wave, and these.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments described below. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. In addition, the piezoelectric part in this invention points out the part which shows the piezoelectric behavior between the two electrodes which oppose.

  FIG. 1 is a schematic diagram showing an external configuration of an ultrasonic diagnostic apparatus S according to the embodiment. FIG. 2 is a block diagram showing an electrical configuration of the ultrasonic diagnostic apparatus S according to the embodiment. FIG. 3 is a schematic diagram illustrating a configuration of the vibration unit 20 of the ultrasonic probe 2 of the ultrasonic diagnostic apparatus S according to the embodiment.

  As shown in FIGS. 1 and 2, the ultrasonic diagnostic apparatus S transmits ultrasonic waves to a subject H such as a living body (not shown) and receives reflected ultrasonic waves reflected by the subject H. The ultrasonic probe 2 is connected to the ultrasonic probe 2 via the cable 3, and an ultrasonic probe is transmitted by transmitting a transmission signal of an electrical signal to the ultrasonic probe 2 via the cable 3. The child 2 transmits an ultrasonic wave to the subject H, and an electrical signal generated by the ultrasonic probe 2 in response to the reflected ultrasonic wave from the subject H received by the ultrasonic probe 2 And an ultrasonic diagnostic apparatus body 1 that images the internal state of the subject H as an ultrasonic image into a medical image based on the received signal.

  The ultrasonic diagnostic apparatus main body 1 is provided with an ultrasonic probe folder 4 for holding the ultrasonic probe 2 when the ultrasonic probe 2 is not used.

  For example, as illustrated in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes an operation input unit 11, a transmission unit 12, a reception unit 13, an image processing unit 15, a display unit 16, a control unit 17, and a storage. And a portion 19.

  The operation input unit 11 inputs data such as a command instructing the start of diagnosis and personal information of the subject H, for example, and is an operation panel or a keyboard provided with a plurality of input switches, for example.

  The transmission unit 12 has a circuit having a function of generating a transmission signal of an electric signal for driving the piezoelectric unit 22 to be described later under the control of the control unit 17, and amplifies the electric signal to generate a piezoelectric in the ultrasonic probe 2. A transmission signal is supplied to the unit 32 via the cable 3 to cause the ultrasonic probe 2 to generate ultrasonic waves. The transmission unit 12 includes, for example, a high voltage pulse generator that generates a high voltage pulse.

  The receiving unit 13 receives an electrical signal reception signal from the ultrasonic probe 2 via the cable 3 under the control of the control unit 17. A harmonic component is extracted from the electrical signal, and a circuit as a harmonic extraction unit that performs predetermined signal processing is provided. Details will be described later.

  The image processing unit 15 is a circuit that generates an ultrasonic image of the internal state in the subject H using a harmonic imaging technique or the like based on the reflected reception signal signal-processed by the receiving unit 13 according to the control of the control unit 17. It is. Further, for example, by performing envelope detection processing on the reflected reception signal, a B-mode signal corresponding to the amplitude intensity of the reflected ultrasonic wave is generated.

  The storage unit 19 includes a RAM and a ROM, and stores a program used for the control unit 17 and also records various image templates to be displayed on the display unit 16.

  The control unit 17 includes, for example, a microprocessor, a storage element, a peripheral circuit thereof, and the like. The operation input unit 11, the transmission unit 12, the reception unit 13, the image processing unit 15, the display unit 16, and the storage unit 19 are included. It is a circuit that performs overall control of the ultrasonic diagnostic apparatus S by controlling each according to the function.

  The display unit 16 is a device that displays the ultrasonic image generated by the image processing unit 15 under the control of the control unit 17. The display unit 16 is, for example, a display device such as a CRT display, LCD, EL display, or plasma display, or a printing device such as a printer.

  On the other hand, the ultrasonic probe 2 includes a vibration unit 20. The vibration unit 20 transmits ultrasonic waves to the subject H such as a living body (not shown) and receives reflected ultrasonic waves from the subject H.

  FIG. 3 is a schematic diagram illustrating a configuration of the vibration unit 20 of the ultrasonic probe 2 according to the embodiment. The vibration unit 20 includes a piezoelectric unit 22, an acoustic matching layer 23, an acoustic lens 24, a backing layer 25, and a fixed plate 26.

  The piezoelectric unit 22 converts signals between electrical signals and ultrasonic waves by using the piezoelectric phenomenon in the plurality of piezoelectric elements 221.

  The piezoelectric unit 22 converts an electric signal of a transmission signal input from the transmission unit 12 of the ultrasonic diagnostic apparatus main body 1 via the cable 3 into an ultrasonic wave, transmits the ultrasonic wave, and converts the received reflected ultrasonic wave into an electric wave. The signal is converted into a signal, and the received signal, which is an electrical signal, is output to the receiving unit 13 of the ultrasonic diagnostic apparatus body 1 via the cable 3.

  When the ultrasound probe 2 is brought into contact with the subject H, the ultrasound generated by the piezoelectric unit 22 is transmitted into the subject H, and the reflected ultrasound from the subject H is received by the piezoelectric unit 22. Is done. An inorganic material or an organic material is used as the piezoelectric material.

  The acoustic matching layer 23 includes an acoustic impedance having a value between the acoustic impedance of the piezoelectric unit 22 and the acoustic impedance of the subject H, so that when transmitting the ultrasonic wave transmitted from the piezoelectric unit 22 to the subject H, It has a function of reducing reflected ultrasonic waves generated according to the difference in acoustic impedance between the piezoelectric unit 22 and the subject H, and the ultrasonic waves generated by the piezoelectric unit 22 are reflected to and within the subject H. Ultrasonic waves can be efficiently transmitted to the piezoelectric unit 22. If two or more acoustic matching layers are formed so that the acoustic impedance gradually approaches the subject H from the piezoelectric portion 22, reflection of ultrasonic waves between the piezoelectric portion 22 and the subject H can be reduced. Can do.

  The acoustic lens 24 has a function of focusing the ultrasonic wave transmitted from the piezoelectric unit 22 toward the measurement location.

  The backing layer 25 is a member made of a material that absorbs ultrasonic waves, and is an ultrasonic absorber that can absorb unnecessary ultrasonic waves emitted from the piezoelectric portion 22 toward the backing layer 25. A preferable backing material is made of a rubber-based composite material and / or an epoxy resin composite material, and the shape thereof can be appropriately selected according to the shape of the piezoelectric body or the probe head including the piezoelectric body.

  The fixing plate 26 has a function of fixing the backing layer 25 and imparting rigidity to the ultrasonic probe 2 or fixing at the time of processing.

  Next, an operation for extracting a harmonic frequency component using the ultrasonic diagnostic apparatus S will be described.

  FIG. 4 is a schematic diagram showing the phase relationship of the harmonics generated at the measurement location of the subject H to which ultrasonic waves are transmitted.

  When an ultrasonic wave is transmitted from the ultrasonic probe 2 to a measurement location, a reflected wave is generated due to a distribution of differences in acoustic impedance at the measurement location. In particular, when the ultrasonic wave is focused on the measurement location, the intensity of the ultrasonic wave increases, thereby increasing non-linearity and increasing the harmonic frequency component in the reflected wave. It is known that the initial phase of the reflected wave generated at the measurement location differs depending on the order. As shown in FIG. 4, if the initial phase of the fundamental wave generated at the measurement location is 0 degree, the secondary wave is 45 degrees, the tertiary wave is 90 degrees, that is, if the order is m, 45 × The phase is delayed by (m−1) (degrees). In the present embodiment, the harmonic frequency component is extracted by utilizing the property that the delayed phase differs depending on the order as described above. For this purpose, two reflected waves having a phase relationship as shown in FIG. 5, a first reflected wave and a second reflected wave are generated. In addition, the calculation of the reflected wave performed below shall be performed based on the electrical signal which the ultrasonic wave which is a reflected wave was converted in the piezoelectric part 22. FIG. FIG. 5 is a diagram showing the phase relationship between the fundamental wave and the tertiary wave of the synthesized wave obtained by adding and synthesizing the first reflected wave and the second reflected wave.

  In the first reflected wave, the phase of the fundamental wave is 0 degree and the phase of the tertiary wave is 180 degrees. In the second reflected wave, the phase of the fundamental wave is 270 degrees and the phase of the tertiary wave is 180 degrees. When the first reflected wave and the second reflected wave are added and synthesized, as shown in the figure, the fundamental wave is canceled out and the third-order wave has twice the intensity. Thus, by generating the first reflected wave and the second reflected wave, the fundamental wave can be canceled and the tertiary wave can be amplified.

  Next, means for generating a first reflected wave and a second reflected wave having a phase relationship as shown in FIG. 5 will be described.

  In the first embodiment, the first reflected wave and the second reflected wave are separated from the reflected wave corresponding to one transmission, and the phase of the first reflected wave is changed by the delay means. It is characterized by that.

  The phase of the second reflected wave is changed by a digital filter.

  FIG. 6 is a block diagram of a portion related to reception of the ultrasonic diagnostic apparatus S for realizing such a phase relationship.

  The piezoelectric unit 22 of the vibration unit 20 includes a plurality of piezoelectric elements 221.

  In the receiving unit 13, an amplifier 131, a switch 132, a delay unit 133, an AD converter 134, a phasing adder 135, a switch 136, an FIR (Finite Impulse Response Filter) filter 137, and a memory 138 are sequentially provided in the direction in which the electric signal propagates. , An adder 139 is provided. The amplifier 131 to the AD converter 134 are provided corresponding to each piezoelectric element 221. The FIR filter 137 functions as a phase shift unit that causes the same phase change regardless of the order.

  The image processing unit 15 includes a signal processor 151 and a DSC (digital scan converter) 152.

  FIG. 7 is a flowchart of the operation of the part related to reception of the ultrasonic diagnostic apparatus S of the present embodiment.

  The operation of the part related to reception of the ultrasonic diagnostic apparatus S of the present embodiment will be described with reference to FIG.

  First, in step S <b> 1, the control unit 17 controls the transmission unit 12 and the vibration unit 20 to transmit ultrasonic waves to the subject H. The phase of each piezoelectric element 221 is controlled so that the ultrasonic wave is focused on the measurement location of the subject H by a beam former (not shown) in the transmission unit 12. The first reflected wave, which is a reflected wave generated in the subject H, includes harmonic components in addition to the fundamental wave component due to the acoustic nonlinearity of the human body.

  Next, in step S2, the piezoelectric element 221 in the ultrasonic probe 2 receives the first reflected wave, which is a reflected wave, and converts it into an electrical signal. The electric signal generated by the conversion propagates through the cable 3 and is input to the amplifier 131 of the receiving unit 13, and the electric signal is amplified. The amplifier 131 may be provided in the ultrasonic probe 2. The electric signal amplified by the amplifier 131 is input to the switch 132.

  Next, in step S <b> 3, the switch 132 outputs the electric signal to the delay unit 133 under the control of the control unit 17. The delay unit 133 is a delay unit that delays the phase of the input electric signal, and gives a phase change proportional to the order of the input wave.

  The switch 132 may be a general switch such as a transistor circuit. For example, a delay line having a length corresponding to the delay time can be adopted as the delay unit 133.

  As described with reference to FIG. 5, the delay time is set to 90 degrees for the fundamental wave component. If the fundamental wave component is 90 degrees, the secondary wave is 180 degrees and the tertiary wave is 270 degrees.

  Next, in step S4, the electrical signal of the first reflected wave is processed and stored as follows.

  The electrical signal output from the delay unit 133 is converted from an analog value to a digital value by the AD converter 134. The electrical signal output from the AD converter 134 is input to the phasing adder 135, and the phase for each output of each piezoelectric element 221 is adjusted and phasing is added.

  The electric signal subjected to the phasing addition is input to the switch 136. The switch 136 switches so that an electric signal corresponding to the first reflected wave is input to the memory 138 without passing through the FIR 137 under the control of the control unit 17. The memory 138 stores the electric signal of the first reflected wave subjected to the phasing addition. A memory that can be rewritten by a command from the control unit 17 is employed as the memory 138.

  Next, in step S5, the piezoelectric element 221 in the ultrasonic probe 2 receives the second reflected wave from the ultrasonic wave transmitted in step S1 using the first reflected wave as a reference, and converts it into an electrical signal. The converted electrical signal is input to the switch 132 through the amplifier 131 as described above.

  Next, in step S6, the electric signal of the second reflected wave is processed and stored as follows.

  The switch 132 inputs the electric signal under the control of the control unit 17 to the switch 136 via the AD converter 134 and the phasing adder 135 without passing through the delay unit 133. The switch 136 outputs the electric signal to the FIR 137 under the control of the control unit 17.

  The FIR 137 is a 90 degree phase shift type FIR. Since it is a 90-degree phase shift type, each frequency component is uniformly phase-shifted by 90 degrees regardless of the magnitude of the frequency included in the electrical signal.

  Note that the filter type is not limited as long as it is a digital filter that uniformly shifts the phase of each frequency component by 90 degrees regardless of the magnitude of the frequency included in the input electrical signal, not limited to FIR137. Thus, the second reflected wave has a phase relationship as shown in FIG. The electric signal of the second reflected wave having such a phase relationship is stored in the memory 138.

  Next, in step S7, the adder 139 adds the electric signal of the first reflected wave and the electric signal of the second reflected wave. The electric signal of the first reflected wave and the electric signal of the second reflected wave have a phase relationship as shown in FIG. Specifically, it is as shown in FIG. FIG. 8 is a schematic diagram showing a phase relationship from a fundamental wave to a tertiary wave of a synthesized wave obtained by adding and synthesizing the first reflected wave and the second reflected wave. As shown in FIG. 8, in the composite wave, the fundamental wave is canceled, the third order wave is doubled, and the secondary wave is 2 × sin (45 °) = 1.414 times.

  Next, in step S <b> 8, the electrical signal output from the adder 139 is input to the image processing unit 15. The image processing unit 15 includes a signal processor 151 and a DSC 152. In the signal processor 151, envelope detection, amplitude luminance conversion, and LOG compression are performed. In the DSC 152, image data of a B-mode image is generated by arranging the data from the piezoelectric elements 221 in the sound ray direction. The image data output from the image processing unit 15 is output to the display unit 16, and an ultrasonic image is displayed on the display unit 16.

  As described above, according to the present embodiment, the fundamental wave included in the reflected ultrasonic wave from the subject H can be canceled and the third-order wave can be doubled. An image can be obtained.

(Second Embodiment)
Next, a second embodiment will be described. In the second embodiment, the first reflected wave and the second reflected wave are reflected waves corresponding to the transmission performed twice with different phases.

  FIG. 9 is a block diagram of a portion related to reception of the ultrasonic diagnostic apparatus S of the second embodiment. The difference from the block diagram in the first embodiment is that the switch 132 and the delay unit 133 are not provided, and the output of the amplifier 131 is directly input to the AD converter 134.

  FIG. 10 is a flowchart of the operation of the part related to reception of the ultrasonic diagnostic apparatus S of the present embodiment. The operation of the part related to reception of the ultrasonic diagnostic apparatus S of the present embodiment will be described with reference to FIG.

  First, in step S <b> 21, the control unit 17 controls the transmission unit 12 and the vibration unit 20 to transmit the first transmission wave to the subject H. The phase of each piezoelectric element 221 is controlled so that the ultrasonic wave is focused on the measurement location of the subject H by a beam former (not shown) in the transmission unit 12. The first reflected wave generated in the subject H includes harmonic components in addition to the fundamental wave component due to the acoustic nonlinearity of the human body.

  Next, in step S22, the piezoelectric element 221 in the ultrasonic probe 2 receives the first reflected wave and converts it into an electrical signal. The electric signal generated by the conversion propagates through the cable 3 and is input to the amplifier 131 of the receiving unit 13, and the electric signal is amplified. The amplifier 131 may be provided in the ultrasonic probe 2.

  Next, in step S23, the electrical signal of the first reflected wave is processed and stored as follows.

  The electric signal output from the amplifier 131 is converted from an analog value to a digital value by the AD converter 134. The electrical signal output from the AD converter 134 is input to the phasing adder 135, and the phase for each output of each piezoelectric element 221 is adjusted and phasing is added.

  The electric signal subjected to the phasing addition is input to the switch 136. The switch 136 switches so that an electric signal corresponding to the first reflected wave is input to the memory 138 without passing through the FIR 137 under the control of the control unit 17. The memory 138 stores the electric signal of the first reflected wave subjected to the phasing addition. A memory that can be rewritten by a command from the control unit 17 is employed as the memory 138.

  Next, in step S24, the control unit 17 determines that the phase of the second reflected wave generated by the second transmission wave to be transmitted next is shifted by 180 degrees with respect to the phase of the first reflected wave as shown in FIG. Until the second transmission wave is transmitted.

  Next, in step S <b> 25, the control unit 17 controls the transmission unit 12 and the vibration unit 20 to transmit the second transmission wave to the subject H.

  Next, in step S26, the piezoelectric element 221 in the ultrasonic probe 2 receives the second reflected wave and converts it into an electrical signal. The electric signal generated by the conversion propagates through the cable 3 and is input to the amplifier 131 of the receiving unit 13, and the electric signal is amplified.

  Next, in step S27, the electric signal of the second reflected wave is processed and stored as follows.

  The converted electrical signal is input to the switch 136 through the amplifier 131, the AD converter 134, and the phasing adder 135 in the same manner as described above. The switch 136 outputs the electric signal to the FIR 137 under the control of the control unit 17. The FIR 137 is a 90 degree phase shift type FIR. Since it is a 90-degree phase shift type, each frequency component is uniformly phase-shifted by 90 degrees regardless of the magnitude of the frequency included in the electrical signal. That is, the second reflected wave has a phase relationship as shown in FIG. The electric signal of the second reflected wave having such a phase relationship is stored in the memory 138.

  In step S28, the adder 139 adds the electric signal of the first reflected wave and the electric signal of the second reflected wave. The electric signal of the first reflected wave and the electric signal of the second reflected wave have a phase relationship as shown in FIG. Specifically, it is as shown in FIG. As shown in FIG. 8, in the composite wave, the fundamental wave is canceled, the third order wave is doubled, and the secondary wave is 2 × sin (45 °) = 1.414 times.

  Next, in step S29, the electrical signal output from the adder 139 is input to the image processing unit 15. The image processing unit 15 includes a signal processor 151 and a DSC 152. In the signal processor 151, envelope detection, amplitude luminance conversion, and LOG compression are performed. In the DSC 152, image data of a B-mode image is generated by arranging the data from the piezoelectric elements 221 in the sound ray direction. The image data output from the image processing unit 15 is output to the display unit 16, and an ultrasonic image is displayed on the display unit 16.

  As described above, according to the present embodiment, the fundamental wave included in the reflected ultrasonic wave from the subject H can be canceled and the third-order wave can be doubled. An image can be obtained.

  Note that two reflected waves having a phase relationship as shown in FIG. 11, a first reflected wave and a second reflected wave may be generated. The difference from FIG. 5 is that the phases of the first reflected wave and the second reflected wave are opposite. The first reflected wave is advanced by 90 degrees from the phase of the fundamental wave of the transmission wave shown in FIG. 4, and the second reflected wave is delayed by 90 degrees. By adopting such a phase relationship, the fundamental wave component can be canceled and the third-order wave can be doubled.

  As described above, according to the present invention, a piezoelectric unit that transmits ultrasonic waves to a subject and receives reflected ultrasonic waves generated by reflection of the ultrasonic waves at the subject and converts them into electrical signals; and the electrical signals An ultrasonic diagnosis comprising: a harmonic extraction unit for extracting at least an electric signal of a harmonic component contained in the image; and an image processing unit for generating an ultrasonic image in the subject from the electric signal of the harmonic component An electrical signal converted by the piezoelectric unit from reflected ultrasonic waves corresponding to transmission of one ultrasonic wave, the first reflected wave whose phase is changed by a delay unit, and the one ultrasonic wave An electrical signal converted from the reflected ultrasonic wave corresponding to the transmission of the sound wave by the piezoelectric unit, and a second reflected wave whose phase is changed by phase-shifting means that brings about the same phase change regardless of the order. And the position of the first reflected wave and the second reflected wave. Since the harmonic component is extracted by offsetting the fundamental wave component by adding the first reflected wave and the second reflected wave with 180 degrees different from each other, the fundamental wave is removed from the reflected wave from the subject. While extracting a harmonic component, an ultrasonic diagnostic apparatus that can provide an ultrasonic image based on the harmonic component can be provided.

  Further, according to the present invention, a piezoelectric unit that transmits an ultrasonic wave to a subject and receives the reflected ultrasonic wave generated by the reflection of the ultrasonic wave at the subject and converts it into an electric signal, and the electric signal includes An ultrasonic diagnostic apparatus comprising: a harmonic extraction unit for extracting at least a harmonic component electrical signal; and an image processing unit for generating an ultrasound image in the subject from the harmonic component electrical signal. The piezoelectric unit converts the first reflected wave, which is an electrical signal converted by the piezoelectric unit from the reflected ultrasonic wave corresponding to the transmission of the first transmission wave, and the reflected ultrasonic wave corresponding to the transmission of the second transmission wave. The second reflected wave, which is an electrical signal, is generated, and the phase of the second reflected wave is changed by phase-shifting means that causes the same phase change regardless of the order, so that the first transmission wave and the second transmission wave are transmitted. Match the timing of the wave to the predetermined timing The fundamental component of the first reflected wave and the second reflected wave is made to be 180 degrees different from each other, and the fundamental wave component is canceled by adding the first reflected wave and the second reflected wave. Therefore, by extracting the harmonic component while removing the fundamental wave from the reflected wave from the subject, an ultrasonic diagnostic apparatus that can provide an ultrasonic image based on the harmonic component can be provided.

  In addition, according to the present invention, since the phase shift means is a digital filter, it is possible to easily realize a function of uniformly shifting the phase of each frequency component regardless of the magnitude of the frequency included in the electrical signal. Therefore, by extracting the harmonic component while removing the fundamental wave, it is possible to provide an ultrasonic diagnostic apparatus that can provide an ultrasonic image based on the harmonic component.

  In addition, according to the present invention, since the digital filter is an FIR filter, it is possible to easily realize a function of uniformly shifting the phase of each frequency component regardless of the magnitude of the frequency included in the electrical signal. .

  In addition, according to the present invention, the digital filter changes the phase by 90 degrees, so that the fundamental frequency component can be completely removed.

  Further, according to the present invention, since the extracted harmonic component is the third harmonic, an ultrasonic diagnostic apparatus that realizes a high-definition ultrasonic image based on the third wave can be provided.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus main body 2 Ultrasonic probe 3 Cable 4 Ultrasonic probe folder 11 Operation input part 12 Transmission part 13 Reception part 15 Image processing part 16 Display part 17 Control part 19 Storage part 20 Vibration part 22 Piezoelectric part DESCRIPTION OF SYMBOLS 23 Acoustic matching layer 24 Acoustic lens 25 Backing layer 26 Fixed plate 32 Piezoelectric part 131 Amplifier 132 Switch 133 Delayer 134 AD converter 135 Phased adder 136 Switch 137 FIR filter 138 Memory 139 Adder 151 Signal processor 152 DSC
221 Piezoelectric element S Ultrasonic diagnostic equipment

Claims (6)

A piezoelectric unit that transmits ultrasonic waves to a subject and receives reflected ultrasonic waves generated by the reflection of the ultrasonic waves at the subject and converts them into electrical signals; and
A harmonic extraction unit for extracting at least an electric signal of a harmonic component contained in the electric signal;
An image processing unit for generating an ultrasonic image in the subject from the electrical signal of the harmonic component;
An ultrasonic diagnostic apparatus comprising:
An electrical signal converted by the piezoelectric unit from reflected ultrasound corresponding to one transmission of ultrasonic waves, corresponding to a first reflected wave whose phase has been changed by a delay means, and corresponding to one transmission of ultrasonic waves A second reflected wave that is an electrical signal converted from the reflected ultrasonic wave by the piezoelectric unit, the phase of which is changed by phase-shifting means that causes the same phase change regardless of the order, and
A harmonic component is extracted by offsetting the fundamental component by adding the first reflected wave and the second reflected wave by making the phases of the first reflected wave and the second reflected wave 180 degrees different from each other. An ultrasonic diagnostic apparatus characterized by the above. A piezoelectric unit that transmits ultrasonic waves to a subject and receives reflected ultrasonic waves generated by the reflection of the ultrasonic waves at the subject and converts them into electrical signals; and
A harmonic extraction unit for extracting at least an electric signal of a harmonic component contained in the electric signal;
An image processing unit for generating an ultrasonic image in the subject from the electrical signal of the harmonic component;
An ultrasonic diagnostic apparatus comprising:
A first reflected wave that is an electric signal converted by the piezoelectric unit from a reflected ultrasonic wave corresponding to the transmission of the first transmission wave, and an electric signal converted by the piezoelectric unit from a reflected ultrasonic wave corresponding to the transmission of the second transmission wave And a second reflected wave that is
The phase of the second reflected wave is changed by phase shifting means that brings about the same phase change regardless of the order,
By matching the timings of the first transmission wave and the second transmission wave to a predetermined timing, the fundamental waves of the first reflected wave and the second reflected wave are different from each other by 180 degrees. An ultrasonic diagnostic apparatus, wherein a harmonic component is extracted by adding a second reflected wave to cancel a fundamental wave component.   The ultrasonic diagnostic apparatus according to claim 1, wherein the phase shift means is a digital filter.   The ultrasonic diagnostic apparatus according to claim 3, wherein the digital filter is an FIR filter.   The ultrasonic diagnostic apparatus according to claim 3 or 4, wherein the digital filter changes a phase by 90 degrees.   The ultrasonic diagnostic apparatus according to claim 1, wherein the extracted harmonic component is a third harmonic.

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