JP3966966B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus that transmits and receives ultrasonic waves in a subject and obtains an ultrasonic image of the diagnostic part using an echo signal by a reflected wave from the diagnostic part, and more particularly, in the long axis direction of a probe. The present invention relates to an ultrasonic diagnostic apparatus capable of improving the azimuth resolution in the major axis direction by finely processing information from an ultrasonic beam.
[0002]
[Prior art]
A conventional ultrasonic diagnostic apparatus of this type has a probe in which a plurality of transducer elements are arranged and transmits / receives ultrasonic waves in a subject, and drives the probe to emit ultrasonic waves and receive received reflections. An ultrasonic transmission / reception unit for phasing and adding the waves, an image memory unit for recording a reception signal from the ultrasonic transmission / reception unit in a storage unit and generating a read image signal, and reading out the image signal from the image memory unit And a display device for displaying as a sound wave image.
[0003]
FIG. 4 shows how an ultrasonic beam is formed by transmitting and receiving ultrasonic waves in such an electronic scanning ultrasonic diagnostic apparatus. That is, each transducer element E _1, E ₂ of the probe 1, ..., the E _5, a delay circuit 3 _1, 3 ₂ of the ultrasonic transmitting and receiving unit 2, ..., ultrasonic giving delay time 3 ₅ In addition to transmitting within the subject, the delay circuits 3 ₁ , 3 ₂ ,..., 3 ₅ are also given delay times when receiving reflected waves from within the subject. At this time, an ultrasonic wave is emitted from each of the transducer elements E ₁ , E ₂ ,..., E ₅ with a predetermined time difference and a reflected wave is received, and is specified according to Huygens's well-known physical phenomenon. The ultrasonic beam 4 is formed so as to converge to the position (focal point F). This ultrasonic beam has been conventionally considered and processed as one beam forming the transducer elements E _{1 to} E _{5 as} a whole. In FIG. 4, five transducer elements (E _{1 to} E ₅ ) and _five delay circuits (3 _{1 to} 3 ₅ ) are shown. The transducer elements are arranged.
[0004]
[Problems to be solved by the invention]
However, in such a conventional ultrasonic diagnostic apparatus, since the plurality of transducer elements E _{1 to} E ₅ are treated as one forming a single beam, the beam width of the ultrasonic beam 4 remains as it is. The azimuth resolution in the major axis direction of the probe 1 along the one-row arrangement direction of the transducer elements E _{1 to} E ₅ is determined. In this case, if the beam width of the ultrasonic beam 4 is reduced, the azimuth resolution in the major axis direction of the probe 1 is improved. However, there is a limitation in reducing the beam width of the ultrasonic beam 4.
[0005]
Therefore, the present invention addresses such a problem, and by ultrasonically processing the information from the ultrasonic beam in the long axis direction of the probe, the azimuth resolution in the long axis direction can be improved. An object is to provide a diagnostic apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention includes a probe in which a plurality of transducer elements are arranged and which transmits and receives ultrasonic waves in a subject, and driving the probe to generate ultrasonic waves. An ultrasonic transmission / reception unit for phasing and adding the received reflected wave, an image memory unit for recording a reception signal from the ultrasonic transmission / reception unit in a storage unit and generating a read image signal, and an image memory unit In an ultrasonic diagnostic apparatus having a display device that reads out an image signal and displays it as an ultrasonic image, the ultrasonic beam received by the receiving circuit of the ultrasonic transmission / reception unit is shifted to the left and right along a center line passing through the focal point. Divided or divided into multiple parts, and the signals of the received beams divided into a plurality of parts are added separately, and the signals of the received beams added separately are point-symmetric at shallow and deep points with the above-mentioned focus as a boundary. State in those that be recorded in the image memory unit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus obtains an ultrasonic image of a diagnostic part by using an echo signal by a reflected wave from the diagnostic part by transmitting / receiving an ultrasonic wave in a subject. As shown in FIG. 1, an ultrasonic transmission / reception unit 2, an image memory unit 5, and a display device 6.
[0008]
The probe 1 emits an ultrasonic wave into a subject and receives a reflected wave thereof. The transducer 1 is a source of ultrasonic waves and receives a plurality of transducer elements E ₁ , E ₂ ,. , Em, Em + 1,..., En are arranged in a line. The ultrasonic transmission / reception unit 2 drives the probe 1 to emit ultrasonic waves and phase-adds the received reflected waves, and includes a transmission circuit, a reception circuit, and control circuits thereof. have. In FIG. 1, only the receiving circuit portion of the above is shown, and the reflection returns with the time difference received by each of the transducer elements E ₁ , E ₂ ,..., Em, Em + 1,. , 3n for receiving a delay signal 3 ₁ , 3 ₂ ,..., 3m + 1,..., 3n for giving a predetermined delay time to each of the wave signals and receiving from these delay circuits 3 ₁ to 3n Adders 7a and 7b for adding signals are provided.
[0009]
The image memory unit 5 records the reception signal output from the ultrasonic transmission / reception unit 2 in a storage unit and generates a read image signal. The image memory unit 5 includes a selector 8 and an analog reception signal as a digital signal. An A / D converter 9 for conversion, a memory 10 serving as storage means for recording image data, and a D / A converter 11 for converting image data into an analog image signal are provided. The display device 6 reads an image signal from the image memory unit 5 and displays it as an ultrasonic image, and is composed of, for example, a television monitor.
[0010]
The state of formation of an ultrasonic beam in such an ultrasonic diagnostic apparatus will be described with reference to FIG. Here, for the sake of simplicity, a case in which five transducer elements E _{1 to} E ₅ and five delay circuits 3 _{1 to} 3 ₅ are provided is illustrated as in FIG. Depending on the delay time set in the delay circuits 3 _{1 to} 3 ₅ , the time for driving the transducer elements E _{1 to} E ₅ varies. In this case, in order to set the focal point F at a certain position, the transducer elements E ₁ and E _{5 at} both ends emit ultrasonic waves at the earliest time, and the middle vibrator element E ₃ emits ultrasonic waves at the latest time. The transducer elements E ₂ and E _{4 at} the intermediate positions emit ultrasonic waves at an intermediate time. From the transducer elements E _{1 to} E ₅ , elementary waves C ₁ , C ₂ , C ₃ (in this example, still in a point state) where the speed of sound is v, the time is t, and the radius is vt. , C ₄ and C ₅ propagate.
[0011]
At this time, according to Huygens' principle, an envelope (surface) formed by connecting a common tangent to each of the elementary waves C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ is the next wavefront W _1. . This surface becomes arcuate because of the difference in delay time set in the delay circuits 3 _{1 to} 3 ₅ . Then, at the next moment, consider the elementary wave that is generated simultaneously with the points D ₁ , D ₂ , D ₃ , D ₄ , and D ₅ on the wavefront W ₁ as the wave source, and again by the Huygens principle, An envelope (surface) formed by connecting a common tangent to the elementary wave of the first wave becomes the wavefront W _{2 of the} next moment. In this way, the process proceeds so as to converge to a point where wavefronts W ₁ , W ₂ ,... Having successively smaller radii are formed, and this point becomes the focal point F of the ultrasonic beam.
[0012]
After that, what happens to the wavefront that has passed through the focal point F is to consider a source wave having a wave source on the wavefront centered on the focal point F in FIG. Eventually, the ultrasonic waves emitted from the transducer elements E _{1 to} E ₅ proceed so as to go straight in a state where the ultrasonic waves are exchanged so as to be symmetric with respect to the focal point F after passing through the focal point F. That is, the ultrasonic waves emitted from the transducer elements E ₁ and E ₂ and the ultrasonic waves emitted from the transducer elements E ₄ and E ₅ are changed in the directions of the arrows G and H with the focus F as a boundary. Proceed to go straight ahead. In this way, one ultrasonic beam 4 having a focal point at the point F as a whole is formed.
[0013]
Here, in the present invention, the ultrasonic beam 4 received by the wave receiving circuit of the ultrasonic transmission / reception unit 2 is divided into two or more parts left and right along the center line passing through the focal point F. The received beam signals are added separately, and the separately added received beam signals are recorded in the image memory unit 5 in a state of point symmetry at the shallow and deep locations with the focus F as a boundary. It has become.
[0014]
For example, as shown in FIG. 1, when the vibrator element with n number using the E ₁ ～En forms a one ultrasonic beam, the two in the middle of the transducer element E ₁ ～En The delay circuits 3 _{1 to} 3n are also divided into two groups in the middle as well as being divided into groups, and the first adder is phased by the first delay circuits 3 _{1 to} 3m for the group of the first half transducer elements E _{1 to} Em. 7a is added to form one beam, and the latter group of transducer elements Em + 1 to En is phased by the latter delay circuits 3m + 1 to 3n and added by the second adder 7b. A book beam. As a result, as shown in FIG. 3, the ultrasonic beam 4 received by the receiving circuit of the ultrasonic transmission / reception unit 2 is divided into two parts on the left and right with the center line 12 passing through the focal point F as the boundary, and the two parts are divided. The received beam signals can be added separately. For simplicity, FIG. 3 shows a case where five transducer elements E _{1 to} E ₅ and five delay circuits 3 _{1 to} 3 ₅ are provided as in FIG.
[0015]
The ultrasonic beam signal divided into left and right in this way is input to the image memory unit 5 in FIG. The input ultrasonic beam signal is switched by the selector 8 to be in a state of point symmetry at a shallow place and a deep place with the focus F shown in FIG. At this time, the selector 8 receives focal depth position information representing the depth position of the focus F shown in FIG. 3 from a control circuit unit (not shown), and the center line 12 shown in FIG. The signal of the received beam divided into left and right at the boundary is switched to a point-symmetric state. As a result, as shown in FIG. 3, one ultrasonic beam 4 described in FIG. 2 is divided into a region A ₁ , a region B ₂ , a region B _1, with the center line 12 and the position of the focal point F as a boundary. And region A ₂ .
[0016]
As is clear from FIG. 3, the region A ₁ and the region A ₂ are symmetric with respect to the focal point F, and the region B ₁ and the region B ₂ are symmetric with respect to the focal point F. As can be seen from the description of FIG. 2 described above, the ultrasonic waves emitted from the transducer elements E _{1 to} E ₅ are switched so as to be symmetric with respect to the focal point F after passing through the focal point F. Since the region A ₁ and the region A ₂ are the same system ultrasonic information source, and the region B ₁ and the region B ₂ are the same system ultrasonic information source. That is, in the case of FIG. 3, two pieces of ultrasonic information are included in one ultrasonic beam 4 with the center line 12 as a boundary. This has an effect similar to the result that the beam width of the ultrasonic beam is narrowed as a result.
[0017]
The received signal output from the selector 8 is converted into a digital signal by the A / D converter 9 and then sent to the memory 10 for writing. In this memory 10, as shown in FIG. 1, there is a certain ultrasonic wave according to the areas A ₁ -A ₂ and B ₁ -B ₂ as ultrasonic information sources of the same system of the ultrasonic beam 4 shown in FIG. In the beam, the regions A ₁ and B ₂ are arranged on the left and the regions B ₁ and A ₂ are arranged on the left side and the right side of the region B ₁ and the region A ₂ , respectively. Record. In this state, the ultrasonic reception signal data is repeatedly recorded in the memory 10 in the same manner as described above for each ultrasonic beam.
[0018]
Thereafter, the received signal data is read out from the memory 10 in accordance with the TV scanning direction of the display device 6. At this time, the received signal data recorded as described above is read in the horizontal direction in accordance with the direction of television scanning. Next, the image data read from the memory 10 is converted into an analog image signal by the D / A converter 11 and sent to the display device 6.
[0019]
The display device 6 displays the input image signal as it is as usual. At this time, as shown in FIG. 1, in the memory 10, the region A ₁ and the region B ₂ are, for example, on the left side and the region B ₁ and the region A ₂ are on the right side in the shallow part and deep part with the focus F as a boundary. The images are displayed as they are in the areas A ₁ and B ₂ ; the areas B ₁ and A ₂ , and the images of the two ultrasonic information sources are displayed on the line corresponding to one conventional ultrasonic beam 4. Will be displayed. Therefore, as a result, the azimuth resolution in the long axis direction of the probe 1 is improved.
[0020]
1 and 3, the ultrasonic beam 4 received by the receiving circuit of the ultrasonic transmission / reception unit 2 has been described as being divided into left and right parts with a center line 12 passing through the focal point F as a boundary. The present invention is not limited to this, and the ultrasonic beam 4 may be divided into a plurality of parts along the center line 12 passing through the focal point F, and the signals of the divided reception beams may be added separately. That is, the ultrasonic beam 4 is divided into three parts, four parts, five parts,... And added separately, and the signals of the received beams added separately are point-symmetrical at a shallow place and a deep place with the focus F as a boundary. In this state, it may be recorded in the image memory unit 5. In this case, the azimuth resolution in the major axis direction of the probe 1 may be further improved. In addition, although the above-mentioned multiple divisions are actually often divided into even numbers, theoretically, they can be realized even with odd divisions.
[0021]
In the above description, the case of single focus has been described. However, the present invention is not limited to this and can be applied to the case of multistage focus. Furthermore, in the above description, the ultrasonic image mainly describes the case where the B-mode image is visualized. However, the present invention is not limited to this. The present invention can also be applied to the case where the D-mode image, the M-mode image, or the CFM mode image is visualized. .
[0022]
【The invention's effect】
Since the present invention is configured as described above, the ultrasonic beam received by the receiving circuit of the ultrasonic transmission / reception unit is divided into two or more parts to the left and right along the center line passing through the focal point, and the plural parts are divided. The received beam signals are added separately, and the separately added received beam signals are recorded in the image memory unit in a state of point symmetry at shallow and deep points with the focus as the boundary. As a result, the azimuth resolution in the major axis direction can be improved by finely processing the information from the ultrasonic beam in the major axis direction of the probe. Therefore, the image quality of the finally obtained ultrasonic image can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is an explanatory diagram showing how an ultrasonic beam is formed in the ultrasonic diagnostic apparatus.
FIG. 3 is an explanatory view showing that one ultrasonic beam emitted from a probe in which a plurality of transducer elements are arranged contains two pieces of ultrasonic information with a center line as a boundary. is there.
FIG. 4 is an explanatory diagram showing a state in which one ultrasonic beam is formed by transmission / reception of ultrasonic waves in a conventional ultrasonic diagnostic apparatus.
[Explanation of symbols]
1 ... probe 2 ... ultrasonic transmitting and receiving unit 3 ₁ 3n ... delay circuit 4 ... ultrasonic beams 5 ... image memory 6 ... display 7a, 7b ... adder 8 ... selector 9 ... A / D converter 10 ... Memory 11 ... D / A converter 12 ... Center line E _{1 to} En of ultrasonic beam ... Transducer element F ... Focus

Claims (1)

A probe in which a plurality of transducer elements are arranged to transmit and receive ultrasonic waves in a subject; an ultrasonic transmission and reception unit that drives the probe to emit ultrasonic waves and phase-adds the received reflected waves; And an image memory unit that records a reception signal from the ultrasonic transmission / reception unit in a storage unit and generates a read image signal, and a display device that reads the image signal from the image memory unit and displays the image signal as an ultrasonic image. In the ultrasonic diagnostic apparatus, the ultrasonic beam received by the reception circuit of the ultrasonic transmission / reception unit is divided into two or more parts left and right along the center line passing through the focal point, and the signal of the divided reception beam is divided into two or more. The reception beam signals added separately are recorded in the image memory unit in a state of point symmetry at shallow and deep points with the focus as a boundary. The ultrasonic diagnostic apparatus.

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