JPS5937969B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that utilizes the transmission characteristics of ultrasonic waves.

Most conventional ultrasound devices emit ultrasound beams,
For example, a tomographic image of the inside of the living body is obtained by detecting reflected signals of this ultrasonic beam at various parts of the living body. In such means using reflection of ultrasound, it has been difficult to obtain a homogeneous diagnostic image with good resolution because the sound field of the ultrasound varies depending on the distance from the sound source. In addition, the reflection of the obtained ultrasonic wave is caused by the area where the acoustic impedance changes in the living body,
In other words, it indicated the boundaries of each organization. Therefore, even when observing the internal conditions of a living body, although it is possible to know the shape of the tissue, it is not possible to obtain information regarding the substance of the tissue. By the way, there is a method of obtaining a perspective view of a living body using holography as a device that uses ultrasound, but it has many drawbacks such as low detection sensitivity and inconvenience in handling the device, so it is far from practical use. It's summery.

Additionally, there are methods that use X-rays as a means of obtaining a perspective view of a living body, but this method is inappropriate as a means of obtaining a perspective view of all parts due to factors such as the amount of exposure to X-rays. Furthermore, X-rays cannot be applied at all to fluoroscopy of soft parts of living bodies, such as mammary glands. The present invention has been made in view of the above circumstances, and its purpose is to provide an ultrasonic diagnostic apparatus that has high resolution, high speed, and can easily obtain tomographic images of living tissues. It is to provide. The details of the present invention will be explained below with appropriate reference to the drawings.

FIGS. 1a and 1b are external views of a container equipped with an ultrasonic transducer according to an embodiment of the present invention, where a is a plan view and FIG. 1b is a sectional view seen from the front. A container 1 whose upper surface A has a flat edge is injected with water or a liquid 2 which is harmless to living organisms and has an acoustic impedance close to that of living tissue and a small ultrasonic absorption coefficient. Inside this container 1, a shaft 3 is provided in the vertical direction, and along this shaft 3, a support base 4 formed in an annular shape of an ultrasonic absorber or the like is provided so as to be movable back and forth in the direction of arrow B. A plurality of ultrasonic transducers 5, such as piezoelectric vibrators, are arranged at equal intervals on the inner peripheral surface of the support base 4. An ultrasonic transmitter (not shown) is selectively connected to these ultrasonic transducers 5 by a control circuit (not shown) that sequentially switches and controls the transducers (not shown), and a plurality of ultrasonic waves (not shown) are selectively connected to these ultrasonic transducers 5. The receiving device is individually connected to the ultrasonic transducer 5 facing the ultrasonic transducer 5 connected to the ultrasonic transmitting device described above, and to the ultrasonic transducer 5 in the vicinity thereof. Further, a computer system (not shown) is connected to the output end of the ultrasonic receiving device.
Reference numeral 6 in the figure indicates the biological tissue of the part to be measured of the subject. In such a configuration, when a biological tissue 6 is placed in the container 1 and an ultrasonic signal is emitted from the identified ultrasonic transducer 5a, this ultrasonic signal is transmitted via the fluid 2 and the biological tissue 6 to the ultrasonic transducer 5a. A total of 1 ultrasonic transducer 5n facing the transducer 5a and 5n-5 to 5n+5 in the vicinity of the ultrasonic transducer 5n.
Input to one ultrasonic transducer 5n-5 to 5n+5.

The ultrasonic signals input to these ultrasonic transducers 5n-5 to 5n-5 have different transmitted pulse intensities In-5 to In+5 as they pass through the living tissue 4, and these intensities 1n-5 to In+5 differ. In+, respectively, are stored in the computer system. Next, an ultrasonic signal is emitted from the ultrasonic transducer 5b disposed beside the identified ultrasonic transducer 5a, and as described above, the opposing ultrasonic transducer 5n+1 and its neighboring ultrasonic transducer 5n- 4
~5n+6 ultrasonic transducers, each with a transmitted pulse intensity of VO-4~''. +6 is received and stored. This is repeated sequentially, and the transmitted pulse intensity at each position is stored. The number of stored transmitted pulse intensities is 2n×11, where 2n is the number of ultrasonic transducers 5 disposed in the ultrasonic absorber. These stored values of transmitted pulse intensities are processed by a computer system to calculate the distribution of the absorption coefficient of the ultrasonic signal of the living tissue 6, and the distribution is displayed on a display device, so that the cross-section of the living tissue 6 is calculated. You can get the image. For example, as shown in Figure 2, the observed area is All~Amn.
is quantized into small regions, and let the ultrasonic absorption coefficients of each of these quantized regions be α11 to αMn.

Here, the transmitted pulse intensity of the ultrasound signal is detected as , and by calculating these it is easy to calculate the absorption coefficient α1
1 to αMn can be obtained, and the distribution of the ultrasonic absorption coefficient can be seen.

By the way, selection and switching of the ultrasonic transducer 5 connected to the ultrasonic transmitting device and the ultrasonic receiving device described above can be performed electronically using, for example, an analog switch.

Therefore, the time T required for one scanning of ultrasonic signal emission is as follows. Here, L is the distance between the opposing ultrasonic transducers 5, and C is the sound speed of the ultrasonic signal.
For example, L-200m7! L,. C=1.5×106m1
/SeClN=200, time T is approximately 27 mSec
Therefore, signals can be detected in an extremely short time. After obtaining a tomographic image of the living tissue 6 in this manner, the ultrasound absorber 3 is moved in the direction of arrow B and operated in the same manner as described above to obtain tomographic images of different parts of the living tissue 6. By sequentially repeating this process, biological tissue 6
We can obtain information about the entire solid of . By processing this information, tomographic images from all angles can be easily created in a short time. Further, the liquid 2 allows the ultrasonic signals to pass through without adversely affecting the ultrasonic signals, and is also used to calibrate variations in the characteristics of the individual ultrasonic transducers 5 before measuring the biological tissue 6. This contributes to improving the reliability of the transmitted pulse intensity value as the detection signal. As described above, in this device, an ultrasonic signal is emitted to the living tissue 6, and the transmitted pulse intensity of the transmitted ultrasonic signal is measured.

According to such means, the internal condition of the living tissue 6 can be detected in a very short time, and the internal situation can be detected based on the distribution of the ultrasonic absorption coefficient of the living tissue 6. Therefore, it is not limited to just detecting the state of different boundaries of tissues inside a living body as in the past. Furthermore, since the transmitted intensity of the ultrasonic signal is measured, it is possible to obtain a clear and homogeneous signal with high detection sensitivity compared to conventional means using reflection, and the device is easy to operate. Therefore, a tomographic image with high resolution can be easily obtained. Furthermore, since a liquid is injected between the ultrasound transducer 5 and the living tissue 6, which is close to the acoustic impedance of the living body and has a low ultrasound absorption coefficient, the conditions for the ultrasound signal to the living tissue 6 are always constant. In addition, since there is no pressure of the probe consisting of the ultrasonic transducer 5 on the biological tissue 6 as in the conventional method, it is possible to maintain the shape of the biological tissue 6 constant during the measurement period. . Furthermore, since this device is designed to measure the transmission characteristics of ultrasound signals in living tissue 6, it is possible to measure the internal state of soft tissues of living bodies such as mammary glands, which could not be measured using conventional X-rays. can be detected.

Therefore, it can be extremely effectively applied to early detection of breast cancer, etc., and can play a useful role in diagnosis and treatment. Note that the transmission characteristics of the ultrasonic signal may be measured not only by measuring the ultrasonic absorption coefficient but also by measuring the sound velocity of the ultrasonic signal, or by measuring the ultrasound absorption coefficient and the sound velocity simultaneously.
FIGS. 3 and 4 are diagrams each showing an example of an ultrasonic transmitting/receiving circuit according to another embodiment of the present invention. In FIG. 3, a clock pulse CP is input to a pulser 12 via a gate circuit 11 controlled by a control circuit not shown. The pulser 12 is activated by the input of this clock pulse CP, and emits an ultrasonic signal via the ultrasonic transducer 5. On the other hand, the ultrasonic signal input via the ultrasonic transducer 5 is input to a limiter circuit 13, and the signal from the limiter circuit 13 is sent to a computer system (not shown) via an analog switch 14 controlled by the control circuit. It is configured so that it is output to . Therefore, by individually connecting such an ultrasonic transmitting/receiving circuit to each ultrasonic transducer 5, the selection of the ultrasonic transducer 5 can be changed only by controlling the opening/closing of the gate circuit 11 and analog switch 14 by the control circuit. It can be performed. In addition, in FIG. 4, the clock pulse CP
The output of the pulser 21, which is activated by is input to a limiter circuit 23, and the signal from the limiter circuit 23 is output to a computer system (not shown) via an analog switch 24 controlled by a control circuit. Therefore, by individually connecting such an ultrasonic transmitting/receiving circuit to each ultrasonic transducer 5, it is possible to easily operate the ultrasonic transducer 5 at high speed as in the embodiment shown in FIG. Selection switching can be performed. In addition, in the embodiment shown in FIGS. 3 and 4 as well, it is possible to obtain a tomographic image of the biological tissue 6 with high resolution, similarly to the first embodiment described above. In the embodiment shown in FIG. 3, a pulse with a wide band may be emitted as a transmission pulse of an ultrasonic signal, and a filter circuit may be provided on the receiving device side to detect signals of different frequencies. In this case, information regarding the frequency dependence of the absorption of ultrasound signals in the living tissue 6 can also be obtained, and the internal situation of the living tissue 6 can be observed more accurately. Furthermore, in the embodiment shown in FIG. 4, by changing the burst frequency of the ultrasonic signal, the transmitted intensity of the ultrasonic signal at different frequencies may be detected. In this case as well, it becomes possible to more accurately observe the internal situation of the living tissue. Furthermore, by using pulses as the ultrasonic signal in this way, it is possible to almost eliminate the adverse effects of standing waves or diffraction of the ultrasonic signal, thereby making it possible to obtain highly reliable information. Furthermore, according to the present invention, as shown in FIG. 5, the first ultrasonic pulse signal is emitted from the ultrasonic transducer 5a, and before this ultrasonic pulse signal reaches the opposing ultrasonic transducer 5n, etc. Additionally, the second ultrasonic pulse signal may be emitted from the ultrasonic transducer 5b.

For example, the first ultrasonic pulse signal is set at time Tl. t, and this ultrasonic pulse signal is transmitted to the opposing ultrasonic transducer 5n after T seconds, that is, at time Tl.t. When reaching r,
The second ultrasonic pulse signal is transmitted at time Tl. t, a time shorter than time T, that is, time T2. Fire at t. This time T
2. The ultrasonic pulse signal emitted at time t is transmitted after time T', that is, time T2. Reach rK ultrasonic transuser 5n 7th grade. By repeating this process one after another, the time required for detecting the internal state of the living body using ultrasonic signals can be shortened more than in the above embodiments. Here, if the emission time interval of the ultrasonic pulse signal is divided into the time required from emission to arrival by an integer as described above, then at the arrival time of the ultrasonic pulse signal, another ultrasonic pulse signal from another ultrasonic transducer 5 is generated. is emitted, and electrically induced noise accompanying the emission of this emitted pulse may mix into the received ultrasonic signal. In order to avoid this contamination, for example, if the arrival time and the launch time coincide, the launch time can be slightly delayed. As explained above, the present invention arranges a plurality of ultrasonic transducers at regular intervals on the circumference, and connects an ultrasonic transmitter and an ultrasonic receiver to a control circuit for these ultrasonic transducers. Therefore, the ultrasound signal is selectively connected, the ultrasound signal is passed through the living tissue, the transmission characteristics of this ultrasound signal are sequentially detected, and the transmission characteristics of the detected ultrasound signal are processed to create a tomographic image of the living body. This is what I did to get it.

In particular, the ultrasonic transducer is installed in a container filled with a liquid that has an acoustic impedance close to that of a living body and a small ultrasonic absorption coefficient. Therefore, according to the present invention, ultrasonic waves have various special advantages such as being able to obtain homogeneous and high resolution tomographic images of biological tissue easily and at high speed, and are extremely useful for diagnosis of living organisms. A diagnostic device can be provided.

[Brief explanation of drawings]

Figures 1A and 1B show the shape of a device according to an embodiment of the present invention, where a is a cross-sectional view seen from the top, b is a cross-sectional view seen from the side, and Figure 2 is a detection signal processing according to the present invention. 3 and 4 are configuration diagrams of an ultrasonic transmitting/receiving circuit showing another embodiment of the present invention, and FIG. 5 is a diagram showing the emission time of an ultrasonic pulse signal in yet another embodiment of the present invention. This is a timing chart showing the following. 1...container, 2...liquid, 3...
...Axis, 4...Ultrasonic absorber, 5...
Ultrasonic transducer, 6... Living tissue, 1
1... Gate circuit, 12゛, 21...
Pulsar, 13, 23...Limiter circuit, 14
, 22, 24... Analog switch, 5a, 5
b...5n-5...5n...5n+5...
・Ultrasonic transducer.

Claims (1)

[Claims] 1 A plurality of ultrasonic transducers arranged at regular intervals on the circumference, an ultrasonic transmitter that is selectively connected to one of these ultrasonic transducers, and this ultrasonic transmitter are connected. a plurality of ultrasonic receiving devices each individually connected to another ultrasonic transducer facing the ultrasonic transducer and a plurality of ultrasonic transducers disposed near the ultrasonic transducer; means for sequentially switching the connection relationship between the sonic wave transmitting device and the ultrasonic receiving device; a means for sequentially storing the signals detected by the ultrasonic receiving device; and processing the signals stored by the means to obtain an image signal. The ultrasonic transducer is provided in a container that houses a part to be measured and is filled with a liquid having an acoustic impedance close to that of a living body and a small ultrasound absorption coefficient between the part to be measured and the part to be measured. An ultrasonic diagnostic device characterized by: