JPS61290938A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ultrasonic diagnostic device that obtains information inside a living body using ultrasonic waves. The present invention relates to an ultrasonic diagnostic device having a measurement function.

[Technical background of the invention and its problems]

Diagnostic methods using ultrasound have the advantage of being able to diagnose soft tissue without placing any burden on the examinee, and are non-invasive, and are rapidly becoming more popular due to recent advances in high-speed scanning equipment. It has become popular. Since this ultrasonic diagnostic method is a pulse reflection method, it is easier to operate than the transmission method, and the diagnostic sites to which it can be applied are not limited in any way, which is another reason for its widespread use.

Recently, there has been an increasing demand for quantification of image quality in such ultrasonic diagnostic methods. Quantification of images is considered to be particularly effective in differential diagnosis of benign and malignant organ diseases. However, in the conventional pulse reflection method, the reflected wave intensity is determined by the acoustic impedance (density and sound velocity) between tissues in the body.
The difference depends not only on the shape of the reflecting surface, the angle of incidence of the ultrasound beam on the reflecting surface, the ultrasound beam inside the living body, etc., and it is difficult to separate and detect these pieces of information. Therefore, it was extremely difficult to quantify the speed of sound.On the other hand, the conventional method of measuring only the speed of sound was transmission-type ultrasonic C.
Although it is still in the research stage, its performance is gradually improving (Reference: Greenlea
f, J, F, et, al, “Acousttcal Holograph
May vol, 6 1975). However, the transmission method cannot be applied to areas where there is bone or gas in the ultrasound propagation path.

It has a major drawback in that it can only be used in very limited areas such as mammary gland examinations.

On the other hand, a method has been devised in recent years to measure the sound velocity inside the Ii@ vessel using the pulse reflection method. Figure 5 shows the intrahepatic sound velocity measurement method reported by Akamatsu et al.

This is used for transmission and reception by two ultrasonic transducers 51 and 52 with strong directivity, respectively, and the ultrasonic waves transmitted from the transmitting ultrasonic transducer 51 are transmitted to each transducer 51 and 52. The central axis PP', QQ
Near the intersection O of
This time and the distance between each transducer 51.52
This method calculates the average sound speed in the liver from the predicted propagation distance calculated from the angle θ and the expected propagation distance.

This method is considered to be effective in diagnosing diffuse diseases such as liver cirrhosis, in which the intrahepatic metal has uniform acoustic characteristics, but the sound velocity obtained is the average sound velocity within the frost transmission path.
This method cannot be applied to localized diseases, and there is a problem in that there is a large error in measuring the sound speed because the ultrasound propagates through the epidermis or fat layer, which has a different sound speed than the inside of the liver.

Moreover, when refraction occurs as shown in FIG. 3, the error becomes even larger because the beam passes through a portion different from the preset propagation path.

For example, the thickness of the fat layer and the speed of sound are d and c, respectively, and the angle of incidence is θ.
If the transducer interval is X, then the sound velocity in the liver is C! The estimated value of C! is denoted by , and if dl<<X, then . If surrounded, C snow-157Qm/sec c, ”1400rQ/
If it is sec, there will be an error of about 10 yen.
Quantitative measurement becomes difficult.

[Purpose of the invention]

An object of the present invention is to provide an ultrasonic diagnostic apparatus that can more accurately measure the average or local sound velocity of deep internal organs in a living body.

[Summary of the invention]

In order to achieve the above object, the present invention arranges a transmitting ultrasonic transducer and a receiving ultrasonic wave so that their respective transmitting areas and receiving areas intersect with each other. The ultrasound waves were reflected at two different points inside the living body.

It is designed to measure the difference in time until the ultrasonic wave is received by the receiving ultrasonic transducer, and calculate the average or local ultrasonic sound speed in a desired region within the living body from this time difference. Sound waves are transmitted and received via a coupling material with a known speed of sound placed on the body surface. Note that the calculation for determining the ultrasonic sound velocity from the time difference may be performed using a yL open circuit, or may be performed by a doctor or the like.

〔Effect of the invention〕

According to the present invention, since sound waves are transmitted and received through a coupling material with a known sound velocity, it is possible to reduce measurement errors caused by refraction of the sound velocity near the body surface, and to reduce the measurement error caused by the refraction of the sound velocity near the body surface. Since the local sound velocity can be estimated quantitatively, it is extremely effective in differential diagnosis.

[Embodiment of the Invention] FIG. 1 shows the configuration of essential parts of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. As shown in the figure, one transmitting piece ultrasonic transducer 11 and two reception avoidance acoustic transducers 12 and 13 are prepared as lff1 acoustic transducers, and a living body 14 is transmitted through a coupling material 24. The surface is cloudy.

The transmitting ultrasonic transducer 11 is driven by an electric drive pulse supplied from the transmitting circuit 15.
Ultrasonic pulses are transmitted into the living body 14. This ultrasonic pulse is reflected within the living body 14, and the ultrasonic waves reflected at points A and B are the first. The second receiving ultrasonic transducers 12 and 13 each receive the signals and convert them into miss signals, resulting in one reflected wave signal. These reflected wave signals are each amplified by an amplifier 16°F, and then sent to the broom 1. The signal is supplied to a second edge detection circuit 18, 19, and its front edge is detected. 1st. Second F') detection circuit 18.
The detection pulses obtained from the counter 19 are supplied to the set input S and the reset input R of the counter 20, respectively. At the timing of the detection pulse from the first edge detection circuit 18, the counter 20 starts the high frequency oscillator controlled by the control circuit 21. Counting of O-clock pulses is stopped at the timing of the detection pulse. The count value of the counter 20 is input to the arithmetic circuit 23.

Here, if the count value of the counter 20 is N and the oscillation frequency of the high frequency oscillator 22 is fx, then the ultrasound transmitted from the transmitting ultrasound transducer 11 is reflected at two different points within the living body 14. After that, 1st. The difference in time Δt until each reception is received by the second reception ultrasonic transducer 12 and 13 is Δt n N / f x −
=-” It can be obtained by (1). Arithmetic circuit 23
performs the calculation expressed by this equation (1), and further measures the ultrasonic sound velocity within the living body 14 from this time difference Δt, if necessary.

Next, the principle of ultrasonic sound velocity in this embodiment will be explained in detail with reference to FIG. As shown in FIG. The central axes of the transmitting ultrasonic transducer 12 and 13 are parallel to each other.On the other hand, the central axis of the transmitting ultrasonic transducer 12 and the receiving ultrasonic transducer 12 and 13 are at an incident angle of θ· with respect to the CIJ central axis. However, a coupling material 24 (for example, water) with a known sound velocity is placed between the transducers 11 to 13 and the living body 14.Now, the sound velocity in the coupling material 24 is expressed as Lee's body surface. The speed of sound in the vicinity 25 (for example, a fat layer) is C1, and the speed of sound in the organ to be measured 14 is C!.Also, AB is the intersection point of the beams of the ultrasonic transducers 11 to 13, and AB is the point of intersection of the beams of the receiving transducers 12 and 13. The position is EF, the intersection of the critical center from point A to the line segment and the radius n is D, and the region AD-BD' is the region of interest (ROI) where the ultrasonic sound velocity is to be measured (however, AD// BD')
. The ultrasonic waves transmitted from the transmitting ultrasonic transducer 11 are transmitted to the coupling material 242 on the body surface 25. Measured organ 14
After each boundary surface i is refracted as shown in the figure, it is reflected at point A and point B within the region of interest, and is transmitted to the receiving transducer 12.13.
received at

If the propagation time at this time is t1m11 respectively, then dQ, d, are the thickness of the coupling material and the body surface, and d! is the distance from point A to the surface of the leg organ. Also, 10 s'l ll! is expressed as .The time difference △t1. between t and t! is △t□-t, -t1
--; (AB1BD)C3. (ΔX indicates the spacing of the transducers 12.13). That is, the distance ΔX, the beam of the transmitting ultrasonic transducer 11 and the receiving ultrasonic transducer 1
The ultrasonic sound speed C1 within the region of interest can be determined from the angle (reciprocal angle) θ between the central axes of 2.13 and the propagation time difference Δt□.

On the other hand, it is shown by Snell's law. In (6), α and △t are known and △
Since ttz can be determined by measurement, C! can be calculated. In this embodiment, the receiving transducers 12 and 13 are arranged so that their beam directions are substantially perpendicular to the body surface, but there is no need to limit this.
FIG. 3 shows another embodiment of the present invention, in which a part of the ultrasonic transducer of the array used to obtain in-vivo tomographic images (B mode t!) by electronic scanning is shown. This is an example in which the sound speed of a sound wave is measured.In other words, among the many arrayed cutters that make up the array micro-ultrasonic transducer 30, 31 areas indicated by diagonal lines are used during transmission, and areas similarly indicated by diagonal lines are used during reception. Areas 32 and 33 shown in the figure are used.The number of vibrators in each area 31 to 33 is plural in the figure, but may be one depending on the case.Array m, ultra-shinbo transformer Area 31 of deuser 30
When transmitting ultrasonic waves, the ultrasonic beam is deflected, for example, as shown in FIG. can be done. As a specific driving method for performing such electronic deflection, for example, the method described in Japanese Patent Publication No. 56-10058 can be used.

In the 31st embodiment, in order to perform the same processing as in the embodiment shown in FIG. Although a system is required, if it is possible to temporally separate and extract the two reflector signals,
After adding these reflected wave signals, υ edge detection can be performed using the same edge detection circuit. On-the-spot meeting, 7
It is sufficient to start counting the counter at the front edge of the first signal of the reflected wave signals calculated by 70, and to end counting at the front edge of the temporary signal.

This implementation is capable of measuring ultrasonic sound velocity using a single 114-piece ultrasonic transducer, so it has excellent scanning performance and can also provide real-time display of B-mode iron. This has the advantage that it is easy to accurately set the force on the head for which the ultrasonic sound velocity is to be measured. In addition, by electronically changing the position of the transmitting/receiving group acoustic transducer (positions of regions 31 to 33) and the internal angle of the transmitting ultrasonic beam easily and quickly, the ultrasonic transmitting area and receiving area can be easily and quickly changed. Since the crossover region can be changed, it is possible to measure the local ultrasonic sound velocity in the entire region of the living body, and it is also possible to display a two-dimensional sound velocity distribution. That is, it is possible to obtain the in-vivo ultrasonic sound velocity distribution using the pulse reflection method, which was previously impossible.

FIG. 4 shows still another embodiment of the present invention, in which two transmitting ultrasonic transducers 11 and 11' are used to transmit ultrasonic waves transmitted from the first transmitting ultrasonic transducer 11. is reflected at two different points within the living body 14 until it is received by the receiving ultrasonic transducers 12 and 13, and the added second transmitting ultrasonic transducer 11 Similarly, after the ultrasonic waves transmitted from The ultrasonic sound speed is determined by measuring the difference between the two time differences. The present invention is also applicable to such cases.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, #! Figure 2 is a diagram for explaining the principle of in-vivo ultrasonic sound velocity measurement during the same procedure, Figure 8g3. FIG. 4 is a diagram showing another example of the present invention, and FIG. 5 is a diagram illustrating the principle of measuring the speed of ultrasound in the body by the conventional pulse reflection method. 11.11': Ultrasonic transducer for transmission, 12.13... Ultrasonic transducer for reception, 1
4... Biological body, 15... Transmission circuit, 16.17-...
Amplifier, 18.19... Edge detection circuit, 20...
Counter, 21... Control circuit, 22... High frequency oscillator, 23... Arithmetic circuit, 30... Array type ultrasonic transducer, 31... Transmission area, 32.
33...Receiving area. Representative Patent Attorney Noriyuki Chika (and 1 other person)
Figure 4

Claims (1)

[Claims] A transmitting ultrasonic transducer that transmits ultrasonic waves into the living body and a receiving ultrasonic transducer that receives ultrasound reflected within the living body are arranged so that their respective transmitting regions and receiving regions intersect with each other, and After the ultrasonic waves transmitted from the trusted ultrasonic transducer are reflected at two different points in the living body, the difference in time until the ultrasound waves are received by the receiving ultrasonic transducer is measured, and from this time difference, the desired position in the living body can be determined. An in-body sound velocity measuring device configured to determine the average or local ultrasonic sound velocity in a region, wherein a coupling material with a known sound velocity is attached between the transmitting and receiving ultrasonic transducer and the living body. An ultrasonic diagnostic device featuring: