JPS61228841A - Ultrasonic measuring 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 Field of the Invention The present invention relates to an ultrasonic measuring device, and particularly to an ultrasonic measuring device for measuring acoustic nonlinear parameters of a subject.

BACKGROUND ART The speed of sound of an ultrasonic wave propagating in an acoustic medium depends on its sound pressure, and generally increases as the sound pressure increases.

Therefore, when a verification wave having a predetermined amplitude propagates in the sound I medium, the propagation speed is faster in the positive sound pressure part of the ultrasonic wave than in the negative sound pressure part. Therefore, ultrasound is sound's*
As the wave propagates through the medium, harmonic components gradually increase, causing waveform distortion.

Such a phenomenon means that the acoustic medium has nonlinear characteristics with respect to the propagation speed of ultrasonic waves.

This acoustic nonlinear characteristic is unique to each acoustic medium; for example, various organs in the body and cancer cell tissues each have their own unique acoustic nonlinear parameters. By measuring nonlinear parameters, it becomes possible to accurately perform various diagnoses of the subject.

For this reason, conventional ultrasonic measuring devices measure acoustic parameters of a subject by transmitting and receiving ultrasound toward the subject and detecting harmonic components contained in the resulting reflected echoes. , was making the diagnosis.

However, with such conventional devices, when ultrasonic waves propagate through an acoustic medium that has large attenuation characteristics with respect to frequency, such as biological tissue, harmonic components contained in reflected echoes are greatly attenuated along the way. The drawback is that it is difficult to detect harmonic components from reflected echoes and accurately measure the acoustic nonlinear parameters of the object.

In particular, when the test site is located deep within the body,
This has the drawback that the attenuation of harmonic components contained in reflected echoes becomes extremely large, making it even more difficult to measure the acoustic nonlinear parameters thereof.

Purpose of the Invention The present invention has been made in view of such conventional problems, and its purpose is to accurately measure the acoustic nonlinear parameters of a subject, regardless of the attenuation characteristics of the subject with respect to ultrasonic waves. The object of the present invention is to provide an ultrasonic measuring device that can perform

11 Sad LL In order to achieve the above object, the apparatus of the present invention includes a low frequency ultrasound transmitter that transmits a low frequency ultrasound beam toward a subject, and a positive sound pressure part and a negative sound pressure part of the low frequency ultrasound beam. It includes a high-frequency ultrasonic transducer that repeatedly transmits and receives high-frequency ultrasonic pulses while superimposing them on the pressure section.

The high-frequency ultrasound pulses transmitted and received in this way, that is, the positive sound pressure ultrasound pulses and the negative sound pressure ultrasound pulses, have different sound pressures and thus have different propagation velocities within the subject. Then, based on the high-frequency ultrasound pulses received by the high-frequency ultrasound transducer, the propagation time difference between the positive sound pressure high-frequency ultrasound pulse and the negative sound pressure high-frequency ultrasound pulse is calculated, and the influence of the attenuation characteristics within the subject is calculated. This method measures the acoustic nonlinear parameters of a subject without being subjected to

Yi J11 Next, preferred embodiments of the present invention will be described based on the drawings.

First Embodiment FIG. 1 shows a preferred first embodiment of the ultrasonic measuring device according to the present invention. and high frequency ultrasonic transducer 1
4 are placed adjacent to each other.

A characteristic feature of the present invention is that a low-frequency ultrasound beam 10 is directed from a low-frequency ultrasound transmitter 12 toward a desired region of the subject 10.
0, and repeatedly transmit and receive high-frequency ultrasonic pulses from the high-frequency ultrasonic transducer 14 superimposed on the positive and negative sound pressure parts of the low-frequency ultrasonic beam 100.

Therefore, in the device of the embodiment, a part of the oscillation output output from the reference signal oscillator 16 is supplied to the low frequency oscillator 20 via the frequency divider 18, and a part of the oscillation output is supplied as it is to the high frequency oscillator 22. is supplied to.

By doing so, the low frequency oscillator 20 drives the low frequency ultrasonic wave transmitter 12, and as shown in FIG. A low frequency ultrasound beam 100 consisting of:

Further, the control circuit 24 detects the positive sound pressure peak time and the negative sound pressure peak time of the low frequency ultrasonic beam 100 transmitted in this way based on the oscillation output output from the reference signal oscillator 16, and A drive signal is supplied to the high frequency oscillator 22 in synchronization with the positive sound pressure peak and the negative sound pressure peak detected.

Therefore, in the embodiment, the high-frequency oscillator 22 drives the high-frequency ultrasonic transducer 14 based on the drive signal input in this way, and transmits the ultrasonic pulse beam 200 toward the subject 10 . Therefore, as shown in FIG. 2(a), the ultrasonic transducer 14 emits a low frequency ultrasonic beam 10.
The high frequency ultrasonic pulses 200a and 200b are repeatedly output superimposed on the positive sound pressure section and the negative sound pressure section of 0.

In this way, the ultrasonic waves shown in FIG. 2(a) are transmitted from the low-frequency ultrasonic transmitter 12 and the high-frequency ultrasonic transducer 14 to the desired test site within the subject 10. ,
This ultrasonic wave is reflected at the desired test site of the subject, and the high-frequency ultrasonic pulse echo included in this reflected echo is transmitted to the high-frequency ultrasonic transducer 14 as signals 300a and 300b shown in FIG. The signal is received by the detector and supplied to the arithmetic circuit 28 via the detection amplifier 26.

As mentioned above, the sound speed of ultrasound propagating within the subject 10 increases as the sound pressure increases. For example, as shown in FIG. 2, positive sound pressure high frequency ultrasound pulses 20 with high sound pressure
The time t1 from when 0a is transmitted until its reflected echo 3008 is received is the time from when the low sound pressure negative sound pressure high frequency ultrasonic pulse 200b is transmitted until its echo 300b is received. It is shorter than time t2.

Here, for example, a high-frequency ultrasonic pulse 2 is transmitted and received while being superimposed on the sound pressure O portion of the low-frequency ultrasonic beam 100.
Assuming that the propagation time of 00 is to, the propagation time t1 of the positive sound pressure high frequency ultrasonic pulse 200a can be expressed by the following equation.

t 1 =tO−Δt1 (1) where to≧t1, Δt1≧0° On the other hand, the propagation time t2 of the negative sound pressure high frequency ultrasonic pulse 200b with low sound pressure can be expressed by the following equation.

t2=tO+Δt2 (2) However, if t2≧to, Δt2≧0° and the waveform of the low-frequency ultrasound beam 100 is symmetrical in positive and negative directions, the following equation holds between Δt1 and Δt2.

Δt1 x Δt2...(3) Then, Δt1 obtained in this way or △
t1+Δt2 is a quantity proportional to the acoustic nonlinear parameter of the subject 10, and therefore, by measuring these quantities, the acoustic nonlinear parameter of the subject 10 can be accurately measured.

Therefore, in the apparatus of the present invention, the arithmetic circuit 28 calculates the positive sound pressure high frequency ultrasound pulse 200a and the negative sound pressure ultrasound pulse 200a in the subject 10 based on the received wave signal 300 inputted as shown in FIG. 2(b). The propagation time difference of the high-frequency ultrasound pulse 200b is calculated, and the acoustic nonlinear parameter of the subject 10 is measured based on the calculation result. The acoustic nonlinear parameters thus determined are then displayed on the display 30.

Thus, according to the invention, the low frequency ultrasound beam 10
Positive sound pressure high frequency ultrasonic pulse 20 outputted superimposed on 0
Reflection of 0a and negative sound pressure high frequency ultrasonic pulse 200b:
) - 300a and 300b and measure the acoustic nonlinear parameters of the object 10 based on these waves, the ultrasonic waves are
It is possible to sufficiently detect the echoes 300a and 300b even when
Compared to a device that detects high-frequency components caused by distortion of the waveform during propagation within the object 10, it is possible to accurately measure this acoustic nonlinear parameter without being affected by the attenuation characteristics of the object 10. Become.

FIG. fj13 shows a detailed configuration of the arithmetic circuit 28 of the device shown in FIG. 1, and FIG. 4 shows a timing chart of signals in each part of the device shown in FIG. 3.

In the embodiment, this arithmetic circuit 28 includes a detection amplifier 26.
The above-mentioned echo signal 300 is supplied via. At the same time, the signal output from the reference signal oscillator 16 is frequency-divided by the frequency divider 24a included in the control circuit 24, and this frequency-divided signal is synchronized with the timing of zero amplitude of the low-frequency ultrasound beam 100. It is supplied to the arithmetic circuit 28 as a reference pulse signal 400.

This arithmetic circuit 28 receives each of these input signals at 300° and 400°.
1/2 frequency divider 32 whose output is inverted every time
a, 32b, and low-pass filters 34a, 34 that output a signal representing the duty ratio of these frequency dividers 32a, 32b, that is, the ratio of the H level signal to the L level signal.
b, and each of these low pass filters 34a.

The output 320.420 of 34b is outputted via the absolute value amplification circuit 36.

Here, when the echo signal 300a of the positive sound pressure high frequency ultrasonic pulse 200a is input, the 1/2 frequency divider 32a inverts its output to H level, and the echo signal 300b of the negative sound pressure high frequency ultrasonic pulse 200b is input. When input, the output is inverted to L level. Therefore, the low-pass filter 34 to which the output 310 of the 1/2 frequency divider 32a is supplied
a is the time from when the echo signal 300a is input until when the echo signal 300b is input, that is, T+(Δt
1+Δt2) is output as a signal 320.

Further, the other 1/2 frequency divider 32b receives the reference pulse signal M40.
Every time 0 is input, the output 410 is inverted to H level or [- level. Therefore, the low-pass filter 34b to which this output 410 is supplied converts the voltage VR corresponding to the half period T of the low frequency ultrasound beam 100 into the signal 420.
It will be output as

Therefore, the absolute value amplification circuit 36 calculates the difference between the voltages VS and VR output in this way, and the resulting signal 500, VS-VRI I, i, positive sound pressure high frequency ultrasonic pulse 200a, and negative sound pressure. This corresponds to the propagation time difference (Δt1+t2) of the high-frequency ultrasound pulse 200b within the subject 10, and the signal 500 obtained in this way
If these are supplied to the display 30, the acoustic nonlinear parameters corresponding to these propagation time differences (Δt1+Δt2) will be displayed on the display 30.

In this way, according to the arithmetic circuit 28 of this embodiment, by comparing and calculating the received signal 300 and the reference pulse signal 400, the received signal 300 and the reference pulse signal 400 are subjected to the positive sound pressure high frequency ultrasonic pulse 200a and the negative sound pressure high frequency ultrasonic pulse 200b. It becomes possible to calculate the propagation time difference within the specimen 10 and accurately measure the acoustic nonlinear parameters of the specimen 10 based on this.

In this embodiment, a reference pulse signal 400 is supplied as one input signal 420 of the absolute value amplification circuit 36 via a 1/2 frequency divider 32b and a low-pass filter 34b. Such a signal 420 can originally be obtained by directly supplying a constant DC voltage, but by configuring it as in this embodiment, it is possible to reliably obtain a value intermediate between logic level high and low. It is possible and preferable.

-ml FIG. 5 shows a second preferred embodiment of the ultrasonic measuring device of the present invention, and the characteristics of this embodiment include a low-frequency ultrasonic transmitter 12 and a high-frequency ultrasonic transmitter/receiver. In the same manner as described above, a low frequency ultrasonic beam and a high frequency ultrasonic pulse superimposed thereon are transmitted and received.

Here, in order to integrally form the low frequency ultrasonic wave transmitter 12 and the high frequency ultrasonic wave transmitter/receiver 14, for example, the ultrasonic vibrator for low frequency and the ultrasonic vibrator for high frequency are combined. It can be easily formed by arranging the ultrasonic wave transmitting/receiving surfaces alternately adjacent to each other.

A third preferred embodiment of the present invention is shown in FIG.
The characteristic features of the embodiment are that the high frequency ultrasonic transducer 14 is
Transmitter 14a of the ultrasonic wave transmitter and receiver 1 for ultrasonic wave reception
4b, and furthermore, the high frequency transmitter 14a and the low frequency ultrasonic transmitter 12 are integrally formed in the same manner as described above.

Therefore, the ultrasonic transmission wave 114a formed in this way
and the ultrasonic wave receiver 14b are arranged opposite to each other with the subject 10 in between, and transmit and receive ultrasonic waves in the same manner as described above.

In addition, in the apparatus shown in FIG. 6, the case where the high-frequency ultrasonic transmitter 14a is integrally formed with the low-frequency ultrasonic transmitter 12 has been described as an example, but the present invention is not limited to this. It is also possible to form both transmitters 12, 14a separately.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, it is possible to accurately measure the acoustic nonlinear parameters of a test object without being affected by the attenuation characteristics of the test object. It becomes possible to perform various diagnoses accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a preferred first embodiment of the present invention, FIG. 2 is a waveform explanatory diagram of the device shown in FIG. 1, and FIG.
4 is a timing chart diagram of the circuit shown in FIG. 3; FIG. 5 is an explanatory diagram showing a preferred M2 embodiment of the present invention; FIG. 6 is an explanatory diagram showing a third preferred embodiment of the present invention. 10... Subject 12... Low frequency ultrasound transmitter 14... High frequency ultrasound transducer 28... Arithmetic circuit 100... Low frequency ultrasound beam 200a... Positive sound pressure high frequency ultrasound sonic pulse 200
b... Negative sound pressure high frequency ultrasonic pulse.

Claims (3)

[Claims] (1) A low-frequency ultrasound transmitter that sends a low-frequency ultrasound beam toward the subject, and a high-frequency ultrasound pulse that is repeated by superimposing the positive and negative sound pressure parts of the low-frequency ultrasound beam. Calculates the propagation time difference between a positive sound pressure high frequency ultrasound pulse and a negative sound pressure high frequency ultrasound pulse within the subject based on the high frequency ultrasound transducer that transmits and receives waves and the received signal obtained by the high frequency ultrasound transmitter and receiver. An ultrasonic measuring device comprising: an arithmetic circuit; and measuring an acoustic nonlinear parameter of a subject based on a propagation time difference between the respective high-frequency ultrasonic pulses. (2) An ultrasonic measuring device according to claim (1), wherein the low frequency ultrasonic transmitter and the high frequency ultrasonic transducer are integrally formed. (3) In the device according to claim (1) or (2), the high-frequency ultrasonic transducer includes a transmitter that transmits high-frequency ultrasonic pulses and a transmitter that receives high-frequency ultrasonic pulses. What is claimed is: 1. An ultrasonic measuring device comprising: a transmitter and a receiver arranged to face each other with a subject in between;