JPS6346694B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ultrasonic diagnostic apparatus in which a plurality of transducers are rotatably provided in a probe. Conventionally, this type of ultrasound diagnostic equipment has been unable to accurately (clearly) diagnose a wide range of specimens because the characteristics of the ultrasound beam emitted from each transducer, that is, the frequency characteristics and sound field characteristics, have been constant. Furthermore, it was difficult to perform tissue characterization, which is expected medically. In other words, regarding the sound field characteristics, the sound pattern of the ultrasound beam is determined by the frequency characteristics of the oscillated ultrasound and the shape and size of the transducer, but generally used for medical purposes is 1 to 10MHz, and the diameter of the transducer is 5mmφ. It is said that it is difficult to diagnose the human body with a diameter of ~20 mmφ and to achieve a narrowly focused ultrasound beam over the entire field of view.For example, if the center frequency is 3.5 MHz, the diameter is 13 mmφ, and the R = 40 mm (focal length) is designed. No. 1 for depths of 70mm or more
As shown in Figure A, there was a drawback that the azimuth resolution was extremely poor, the received wave signal was also extremely low, and the S/N ratio was also extremely low. Similarly, when the focal length was designed to be R=80 mm, there was a drawback that the vicinity of the surface of the specimen could not be clearly seen, as shown in FIG. 1B. The same applies to the frequency characteristics of the transducer; if the specimen is a human body, the attenuation rate is proportional to f, so deep areas cannot be seen at high frequencies, and deep areas can be seen at low frequencies, but the overall image is clear. There was a drawback that it was not possible to obtain In addition, from the perspective of tissue discrimination, there is research in which ultrasound waves of different frequencies are applied to the same tissue in a specimen, the received wave signals are observed, and the tissues are discriminated based on the difference in frequency characteristics and the correlation between the images. This diagnosis is frequently performed among medical scientists, and medical scientists also have high demands for ultrasonic diagnostic equipment that can perform this diagnosis.
For this reason, the method proposed by the inventors of transmitting and receiving ultrasonic beams with different frequency characteristics from different directions for diagnosis (Japanese Patent Application No. 11027-1983) may be applied, but this method Since the ultrasound beams are irradiated from different directions, image changes caused by the different directions cause errors due to image changes due to different frequency characteristics, making it difficult to distinguish the original tissue of the specimen. Therefore, it is an object of the present invention to provide a new ultrasonic diagnostic apparatus that eliminates the above-mentioned drawbacks, and this object is achieved by transmitting and receiving ultrasonic waves from the same position and direction in different sound fields. More specifically, it has a probe equipped with a plurality of rotationally moving ultrasonic transmitting/receiving transducers, and the ultrasonic wave is emitted from the probe and the received signal is captured as a reflected wave. In an ultrasonic diagnostic apparatus that stores or displays images based on The sound field characteristics are composed of combinations that complement each other, and furthermore, each of the plurality of transducers transmits and receives ultrasonic waves with at least two or more different sound field characteristics, and ultrasonic waves with different frequency characteristics. Each of the plurality of transducers is configured to transmit and receive sound waves, and each of the plurality of transducers is configured to have at least a combination of frequency characteristics and/or sound field characteristics that complement each other. The received wave signals obtained from the transducer are each stored in an image memory, and the received wave signals stored in the image memory are sequentially read out asynchronously with the timing at which the received wave signals are stored in the image memory. , is configured to be displayed on a display, and furthermore is the received wave signal from the transducer displayed on the display in a different color depending on the sound field characteristics, and This can be achieved by displaying the received wave signals from the transducer on the display in different colors depending on their frequency characteristics and/or sound field characteristics. Hereinafter, the present invention will be specifically explained based on an embodiment shown in the drawings. As shown in FIG. 2, the ultrasonic diagnostic apparatus 1 has a probe 2, and a shielding cover 3 having an opening 3a in a portion is provided on the outer periphery of the probe 2. There is. Inside the probe 2 is an anti-attenuation liquid 5 such as water or oil.
The rotor 6 is shown in the arrow A in the liquid 5.
It is provided so that it can be rotated freely in the direction. Rotor 5
Two ultrasonic transmitting/receiving transducers 7A, 7C made of piezoelectric elements, etc. are installed at a pitch of 180°, and each transducer 7A, 7C
As shown in Figure 3, the oscillation frequencies are fa, fb
Both focal lengths are l ₁ . On the other hand, as shown in FIG. 1, the probe 2 is connected to a timing control circuit 10, sector memories 11 and 12, a receiving circuit 13, and a driver 15.
6 and a display control circuit 17 are connected. A receiving circuit 13 and sector memories 11 and 12 are connected to the switch 16.
A cathode ray tube 19 is connected to the display control circuit 17 via a display control circuit 17. Since the present invention has the above configuration, when diagnosing a specimen 20 such as a human body using the ultrasonic diagnostic apparatus 1, the rotor 6 is connected to the transducer 7.
A and 7C are rotated to bring the probe 2 into pressure contact with the specimen 20. As shown in FIG. 4, the probe 2 transmits the identification signal S1 of the transducer 7A facing the opening 3a to the timing control circuit 10.
At the same time, the angle θ at which the center of the transducer 7A is with respect to the radiation center line X is output as an angle signal S2 to the control circuit 10 and sector memories 11 and 12. On the other hand, the control circuit 10 drives the changeover switch 16 using the signal S1 to connect the receiving circuit 13 to the memory 11, and also uses the signal S2 to connect the receiving circuit 13 to the memory 11 at fixed angles θ ₁ , θ ₂ , θ ₃ . As shown, the driver 15 is driven and a pulsed drive signal S3 is output to the probe 2, and the probe 2 instantaneously drives the transducer 7A using the signal S3. Then, the transducer 7A emits an ultrasonic wave having a frequency a, and as shown in FIG. 3, a sound field 9A having a focal length _l1 is created within the specimen 20. The ultrasonic wave is reflected within the specimen 20, the reflected wave is captured by the transducer 7A, and a received signal S4 as shown in FIG. 4 is output to the receiving circuit 13. The circuit 13 connects the memory 11 via the changeover switch 16.
The memory 11 outputs the signal S4 within the memory 11.
is recorded together with the angle signal S2. In this way, the transducer 7A creates a sound field 9A at every fixed angle and records the signal S4 reflected and received from the specimen 20, but the transducer 7A rotates in the direction A, and the transducer 7A When the portions 3a no longer face each other, the probe 2 outputs an identification signal S1 and switches the changeover switch 16 via the control circuit 10.
Switch to the memory 12 side. During this time, a new transducer 7C faces the opening 3a, similarly creates a sound field 9C for each angle θ ₁ , θ _{2 .} . . , and records the received signal S4 in the memory 12. The contents of the received wave signals S4 over the entire angular range of the aperture 3a by the transducers 7A and 7C in the memories 11 and 12 obtained in this manner are transferred to the memories 11 and 12 by the display control circuit 17. Asynchronously with writing, the image displayed on the cathode ray tube 19 is read out from the memories 11 and 12 and displayed on the cathode ray tube 19 at a timing when the image is not flickering. At this time, a color cathode ray tube is used as the cathode ray tube 19, and the memories 11 and 12
By displaying the contents in different colors, the frequency characteristics and/or sound field characteristics of the transducers 7A and 7C can be displayed in different colors to facilitate tissue discrimination. In addition, in general, the lower the oscillation frequency, the deeper the ultrasound can reach the specimen 20. Therefore, by setting the oscillation frequencies to a and a (assuming a>b), the memory 11 stores the specimen 20.
The received wave signal S4 from the shallow part to the deep part is recorded in the memory 12, and as a result, a fan-shaped area 22 centered around the opening 3a of the specimen 20 is displayed on the cathode ray tube 19.
Images are clearly displayed from shallow to deep areas. In addition, in order to display clearly and continuously from the shallow part to the deep part of the specimen 20, the frequency characteristics and/or sound field characteristics of each transducer may be complemented with each other. As already mentioned, the height of the oscillation frequency is
Changing the focal length for each transducer improves the resolution, since it affects the depth and depth of the ultrasonic range, but images near the focal point are captured more clearly in any case. This is extremely important. Therefore, in the above embodiment, two transducers 7A and 7C with the same focal length are provided, but as shown in FIG. 4 different transducers 7A, 7
By combining B, 7C, and 7D, it is also possible to display a clearer and higher resolution image. Table 1 shows some examples of combinations of focal lengths and oscillation frequencies of the transducers 7A, 7B, 7C, and 7D of the probe 2 shown in FIG. 5. Furthermore, as shown in FIG. 6, the transducers 7A, 7B, .
It is also possible to emit ultrasonic waves from A, 7B, . . . .

[Table] As explained above, according to the present invention, transducers with different sound field characteristics are combined in the transducer of the probe, so that clear and high-resolution images can be obtained from the shallow to the deep parts of the specimen. By changing not only the sound field characteristics of the transducer but also the frequency characteristics, it is possible to capture and display clear and high-resolution images from shallow to deep areas. Therefore, it becomes possible to provide an ultrasonic diagnostic device that can also discriminate tissues.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the distance from the transducer and the beam diameter according to the present invention, and FIG.
The figure is a block diagram showing one embodiment of the ultrasonic diagnostic device according to the present invention, FIG. 3 is a diagram showing the sound field of a transducer, FIG. 4 is a time chart showing the operation of the diagnostic device of FIG. FIG. 5 is a front view showing another example of the probe, and FIG. 6 is a front view showing still another example of the probe. 1... Ultrasonic diagnostic device, 2... Probe, 7A,
7B, 7C, 7D...Transducer, 9
A, 9B, 9C, 9D...Sound field, S4...Received wave signal.

Claims (1)

[Claims] 1. A probe equipped with a plurality of rotationally moving ultrasonic transmitting/receiving transducers is provided, and an ultrasonic wave is emitted from the probe and is based on a received signal captured as a reflected wave. an ultrasonic diagnostic apparatus that stores or displays images, wherein each of the plurality of transducers transmits and receives ultrasound having at least two or more different sound field characteristics; An ultrasonic diagnostic device characterized in that sound field characteristics are composed of combinations that complement each other. 2. The transducer according to claim 1, wherein each of the plurality of transducers transmits and receives ultrasonic waves having at least two or more different sound field characteristics, and also transmits and receives ultrasonic waves having different frequency characteristics. Ultrasound diagnostic equipment. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein each of the plurality of transducers has at least a combination of complementary frequency characteristics and/or sound field characteristics. . 4. The received wave signals obtained from the plurality of transducers are each stored in an image memory, and the received wave signals stored in the image memory are stored in the image memory at what timing. The ultrasonic diagnostic apparatus according to claims 1, 2, and 3, characterized in that the information is sequentially read out asynchronously and displayed on a display. 5. The invention as set forth in claims 1 and 4, characterized in that the received wave signals from the transducer displayed on the display are each displayed in different colors depending on the sound field characteristics. Sonic diagnostic equipment. 6. Claims 2 and 3, characterized in that the received wave signals from the transducer displayed on the display are each displayed in different colors depending on frequency characteristics and/or sound field characteristics. The ultrasonic diagnostic apparatus according to Items 3 and 4.