JPS6332454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus that scans an object to be diagnosed with a directional ultrasonic beam, emits ultrasonic pulses, and receives reflected waves thereof.

Conventional ultrasonic diagnostic equipment emits ultrasonic pulses, receives the reflected waves, and detects the distance from the transmitting point to the reflecting point. According to this conventional device, it was not possible to detect the qualitative state of the medium of the living body to be diagnosed, such as the attenuation rate. A diagnostic device that uses X-rays is a so-called X-ray tomography, which measures and displays the attenuation state of X-rays inside a living body, and thereby measures and displays the qualitative state of the medium with respect to X-rays in each part of the inside of the living body. Yes, this is a very good device. However, when using X-rays, it can only be applied to a part of the living body. In other words, it is not possible to diagnose parts that cannot be exposed to X-rays.

On the other hand, similar to X-ray tomography, ultrasound tomography is also being considered, but this involves emitting ultrasound waves and detecting the ultrasound waves that have passed through the living body. Because ultrasonic tomography cannot be transmitted through the body, only a small portion of the body can be used for this type of ultrasound tomography.

An object of the present invention is to make it possible to detect not only the shape inside a living body but also its qualitative characteristics by utilizing the reflection characteristics of ultrasound waves.

According to this invention, ultrasonic pulses are emitted into the living body by a transmitter with sharp directivity, and instead of detecting the direct radiated waves, the ultrasound pulses are scattered in various parts of the living body as they travel through the living body. However, the scattered waves at each part are detected, and the reflected points of the received scattered waves are determined from each position of the ultrasonic transmitter and receiver, and the intersection of these directional directions, and the ultrasonic pulse is detected. The time required for the ultrasonic wave to propagate through the ultrasonic path from the emission of the wave to its reflection point and reception is measured. By moving two-dimensionally through such intersections of ultrasound direction directions, we can measure the elapsed time of ultrasound pulses corresponding to each part of the living body.
For example, it is possible to determine the speed of ultrasonic waves in each part of the living body, and thus display the speed of sound in each part of the living body.For example, the speed of sound is high in malignant tumors, etc., and such places can be easily discovered. becomes possible.

For example, as shown in FIG. 1, an opening 12 is formed in the upper plate of a container 11, and an object to be diagnosed 13 is placed in a portion of and above the container 11 so as to close the opening 12. Inside the container 11 is an ultrasonic coupling medium, for example water 1.
4 is filled, and ultrasonic pulses are incident on the object to be diagnosed 13 from the ultrasonic transmitter 15 via the coupling medium 14 in the container 11 . The transmitter 15 has sharp directivity, and the ultrasonic pulses emitted from the transmitter 15 along this ultrasonic directional beam 16 travel without reflection in the coupling medium 14 and reach the object. 13, and propagates inside the object 13 while being scattered at each point.

In this invention, the scattered waves are received by a receiver with sharp directivity. That is, transmission beam 1
A receiver 18 having a directivity direction 17 that intersects with the directivity direction 17 is provided, and the receiver 18 is configured to receive ultrasonic waves from the directivity direction 17 and avoid receiving ultrasonic waves from directions other than this direction as much as possible. . For example, as shown in this example, a horn 19 for blocking ultrasonic waves is provided in front of the receiver 18, and this horn 19 has an ultrasonic absorbing or attenuating layer 20 formed on its inner peripheral surface as shown in FIG. It is preferable. In this way, the transmitting beam 1
6 and the directional direction 17 of the receiver, the reflected pulse toward the directional direction 17 in the scattered waves is received by the receiver 18.

The intersection point 21 of the two directivity directions can be determined from the position of the transmitter 15 and the angle of the directivity direction of the beam 16, and the position of the receiver 18 and the angle of the directivity direction 17 thereof. Therefore, it is scattered from the transmitter 15 at the intersection 21,
It is possible to know the path leading to the receiver 18, to know the time it takes for the ultrasonic wave to be transmitted through this path until it is received, and from this, to know the average speed along that path. .

While the direction of the transmitted beam 16 is kept constant, the angle or position of the pointing direction 17 of the receiver 18 is sequentially shifted to receive the scattered waves at each point on the transmitted beam 16, and the transmitted pulse and its reception are Measure the time required to reach the wave. Furthermore, the angle or position of the transmitted beam 16 is shifted and the scattered waves at each point on the transmitted beam are received in the same manner, and the same process is performed thereafter, so that the object 13 is shaped like a checkerboard, for example, as shown in the figure. divided into each microregion 22, and each microregion 2
When point 2 is used as a reflection point, the time required for the ultrasonic wave to be received by the receiver is measured.

For example, the position on the xy coordinates of the transmitter 15 and the angle of the radiation beam 16 can be controlled by the mechanism section 31 and the control section 32.
The data x ₁ y ₁ θ ₁ indicating the position of the transmitter 15 from the control unit 32 is controlled and set by the coordinate calculation unit 33 .
Enter. Similarly, the position on the xy coordinates and the angle of the pointing direction of the wave receiver 18 are controlled by the control unit 35 of the mechanism unit 34, and the data indicating the position of the wave receiver 18 is controlled by the control unit 35.
x ₂ y ₂ θ ₂ is input from the control unit 35 to the coordinate calculation unit 33 . The coordinate calculation unit 33 calculates the coordinates to which each small region 22 of the object 13 from which the received pulse is obtained belongs from the data on the positions of the transmitter and receiver and their pointing directions from the control units 32 and 35. Calculate the position,
The address generator 36 generates an address corresponding to the coordinate position. In other words, the coordinate calculation section 33 calculates each coordinate position of the intersection 21 between the directional beam 16 and the directional direction 17 of the receiver.

The transmitter 15 is excited by the transmitter 37 to emit ultrasonic pulses, and the output from the receiver 18 is received and amplified by the receiver 38. At step 38, the time measuring section 39 measures the time until the received pulse is obtained.
This measurement time T is designated by the address of the address generation section 36 and stored in the storage section 41.

The storage unit 41 stores the average time of the path of the ultrasonic waves from the transmitter 15 to the receiver 18 corresponding to each point when the object 13 is broken down into its small regions 22. If the length of each micro region (more precisely, the length in the ultrasound path direction) is Si, and the sound speed of the ultrasound in that region is Vi, then the time it takes to pass through each micro region is Si/Vi = τi. . If 1/vi=xi, the waveform passes from the transmitter 15 through the intersection 21 to the receiver 1.
The value Σxisi obtained by adding the product of the length Si of each minute region on the path leading to point 8 and xi at each point becomes the average time Ti measured for that region point. Therefore, by solving linear simultaneous equations in which the time xi in each microregion 2 is an unknown, each microregion 2
We can know the speed of sound vi at 2. Such calculations are taken out from the storage unit 41 and stored in the calculation unit 42.
Then, the velocity in each minute region 22 is determined.
The velocity of the two-dimensional minute region 22 of the object 13 and the transit time at each point are displayed on the display section 43. Such calculations in the calculation section 42, display on the display section 43, and storage in the storage section 41 may be performed in a remote section separate from this device.

As described above, the ultrasonic diagnostic apparatus according to the present invention uses the reflection method, that is, by receiving the scattered ultrasound waves at each point on the path of the ultrasound waves, by using the reflection method instead of the transmission method. Therefore, it is possible to detect the qualitative state of the medium rather than the shape of a minute region inside the living body.
In the case based on the transmission method, parts that cannot be measured due to bone or gas can be measured by the apparatus of the present invention, and, of course, problems such as exposure to X-rays do not occur. In this way, it is possible to detect the qualitative states of various organs, which was previously impossible.

In addition, as shown in FIG. 1, each two-dimensional minute area in a certain cross section of the object 13 is scanned by moving the intersection of the transmitting beam and the receiving direction. This is performed by rotating and moving the receiver 18 as necessary, or by rotating as necessary. For this purpose, for example, the transducer beam scanning means in conventional ultrasonic diagnostic equipment can be used as is, such as the one shown in Japanese Patent Application Laid-Open No. 52-484. be able to. In addition, not only one but a plurality of receivers 18 are operated at the same time. For example, in FIG. Two-dimensional scanning of an intersection can be performed at high speed by transmitting sound waves as radio waves, that is, by transmitting one ultrasound pulse and receiving ultrasound waves from a plurality of scattering points in the direction of travel.

As mentioned above, it is preferable to use a horn-shaped shield 19 in order to obtain very sharp directivity so that the receiver 18 does not receive unnecessary waves. As shown in FIG. 1, when an object 18 and a coupling medium 14 are used to make ultrasonic waves incident on the object 13, there is almost no scattering in the coupling medium 14, and the sound velocity of the coupling medium is constant and Since this is known, reflection can be obtained at the interface between the coupling medium 14 and the object 13, and the interface can be known. Accordingly, the configuration is such that calculations on this coupling medium 14 are omitted. , the amount of calculation can be reduced accordingly, and the storage capacity of the storage section 41 can be reduced accordingly.

Furthermore, in order to improve the reliability of the data, the transmitter and receiver are of the same type, and in the ultrasonic path, one emits ultrasonic pulses, the other receives them, and then the other emits ultrasonic pulses. It is also possible to transmit the same data and receive it on the other hand, and if the same data is obtained for both, that data may be used as correct data.

Generally, ultrasonic diagnostic equipment uses carrier waves of 3 MHz, for example, but frequency components lower than 3 MHz are also generated, so for example,
By using reflected and scattered waves with low components such as 1 MHz for reception, it is also possible to receive scattered waves that are not attenuated as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is a sectional view showing means for sharpening the directivity of a wave receiver. 15: Transmitter, 13: Object to be diagnosed, 16: Ultrasonic transmission beam, 17: Receiving direction, 18: Receiver, 21: Intersection, 22: Microscopic region of object, 31:
Transmitter drive mechanism section, 32: Control section, 33: Coordinate calculation section, 34: Receiver drive mechanism section, 35: Control section, 36: Address signal generation section, 37: Ultrasonic pulse transmission section, 38 :Ultrasonic pulse receiving section, 39:
Time measurement section, 41: Storage section, 42: Arithmetic section, 4
3: Display section.

Claims (1)

[Claims] 1. A transmitter with beam-like directivity, an ultrasonic pulse transmitter that excites the transmitter to emit ultrasonic pulses, and a receiver with sharp directivity that intersects with the directivity direction of the transmitter. an ultrasonic pulse receiver that receives and amplifies the received output of the receiver, and a scattered wave of the ultrasonic pulse at the intersection of the pointing directions of the transmitter and receiver from the transmission of the ultrasonic pulse. an ultrasonic diagnostic apparatus, comprising: a time measuring section that measures the time until the ultrasonic pulse receiving section receives the ultrasonic pulse.