JPH0564059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an acoustic property measuring method for measuring the acoustic properties of in-vivo tissue by receiving ultrasonic waves transmitted into a living body, for example, and a method for measuring acoustic properties in which the measured acoustic properties are temperature-dependent. The present invention relates to a measurement method and apparatus for measuring temperature changes within a living body by utilizing the

BACKGROUND OF THE INVENTION An ultrasonic diagnostic apparatus is a method for obtaining information inside a living body using ultrasonic waves. The mainstream of these ultrasonic diagnostic devices is one that uses a pulse reflection method that transmits ultrasonic waves into a living body and obtains information about the inside of the living body from waves reflected from the living body. This pulse reflection method displays tomographic images by collecting in-vivo information two-dimensionally from the reflected echo intensity from interfaces with different acoustic impedances, that is, amplitude values and ultrasound propagation times. It's becoming like that.
In recent years, there has been an increasing demand for ultrasonic diagnostic apparatuses that mainly diagnose the properties of living tissues to obtain information other than the properties of living tissues. An example of such information is in-vivo temperature. If temperature information inside the body can be obtained, temperature monitoring during thermotherapy for cancer will become possible. The temperature inside a living body can be determined by, for example, measuring the acoustic characteristics of ultrasonic attenuation, sound velocity, or nonlinear parameter B/A when the temperature changes inside the living body, and comparing the acoustic characteristics with the temperature-dependent characteristics of these acoustic characteristics that have been investigated in advance. It is possible to estimate by Among these methods, a method described in, for example, Japanese Patent Application Laid-open No. 119926/1983 is known as a method for obtaining information regarding nonlinear parameters. The method will be briefly explained below.

This method utilizes the nonlinearity that the propagation speed of a sound wave depends on the particle speed and sound pressure of the sound wave. Therefore, a relatively high-frequency probe wave pulse is transmitted from a probe wave transducer that is used for both transmission and reception, and a relatively low-frequency pump wave pulse for pumping is delivered into the living body from almost the same location as this probe wave pulse in the same direction. Set it to send,
In addition, as shown in Figure 8a, the probe wave vibrator is set so that the measurement probe wave is superimposed on the part of the pump wave where the particle velocity is positive (or the part where the particle velocity is negative as shown in Figure 8b). Adjust the drive timing of the pump wave transducer and the phase of the received signal of the probe wave pulse that is largely reflected when the pump wave pulse and probe wave pulse are transmitted, and the measurement pulse only. The received signal of the probe wave pulse that was reflected and returned when it was transmitted, or the received signal obtained by sending out the pump wave pulse and the probe wave pulse together so that they are in reverse phase compared to the first time they were transmitted. By finding the difference from the phase,
The purpose is to detect the phase modulation of the measurement pulse due only to the influence of the pump wave using a pulse reflection method, and to obtain the acoustic nonlinear parameter B/A in the living body. In other words, when focusing on a traveling probe wave pulse, the travel distance is the product of the pump wave amplitude and the nonlinear parameter of the region that the probe wave pulse passes through before reaching the reflector (however, it is a function of the location). Taking advantage of the phase modulation determined by the integral value between By doing so, the distribution of the nonlinear parameter B/A is obtained.

Problems to be Solved by the Invention However, in the conventional nonlinear parameter measurement method described above, since the probe wave pulse is superimposed on the positive or negative peak portion of the particle velocity of the pump wave pulse,
At the moment when the particle velocities of both pulses are added in the increasing direction, the particle velocity becomes extremely large, resulting in abnormal distortion of the probe wave pulse, which adversely affects measurement and also poses a threat to the safety of living organisms. There was a risk of harm. In addition, the acoustic characteristics obtained are only those related to nonlinear parameters,
Since other information, such as attenuation characteristics, etc., cannot be obtained at the same time, there are also problems such as the inability to perform highly reliable temperature measurements.

The present invention solves the above-mentioned problems of the prior art, and improves attenuation characteristics and nonlinear parameters that do not cause abnormal distortion to probe wave pulses and ensure the safety of living organisms. Provides a method and device for measuring acoustic properties including:
It is an object of the present invention to provide a temperature measurement method and a device thereof that can improve the reliability of temperature measurement.

Means for Solving the Problems In order to achieve the above object, the acoustic characteristic measuring method of the present invention uses a probe wave pulse, which is an ultrasonic pulse, and a position of the waveform center of gravity of the probe wave pulse, which has a frequency higher than that of the probe wave pulse. A pulse superimposed on the peak part of the particle acceleration of a low pump wave pulse is transmitted into the subject, and this transmitted signal is reflected and received at two or more reflection points at different depths within the subject. Frequency analysis of the signal is performed to obtain the spectral ratio, and from this spectral ratio, the distribution of the crossing frequency and spectral separation degree within the subject is measured, and these crossing frequency fx(x), spectral separation degree DSS(x), From the dispersion value σ ₀ ² of the probe wave pulse and the propagation distance x, the attenuation coefficient α _o (x) proportional to the n(x) power of the frequency is calculated by the following formula or the following approximate formula:
This is to measure the distribution of within the subject.

αn(x)=−fx(x) ^1-n(x) /σ ₀ ² n(x) d/dx [d/dx{
Kx(x)fx(x)}/d/dxKx(x)〕 Kx(x)≡DSS(x)/fx(x) Or the above crossover frequency fx(x), spectral separation degree
From DSS(x), the dispersion value σ ₀ ² of the probe wave pulse, and the propagation distance x, the attenuation coefficient α(x), which is assumed to be proportional to frequency, is calculated by the following formula or the following approximate formula:
This is to measure the distribution of within the subject.

Or the above crossover frequency fx(x), spectral separation degree
From DSS(x), pump wave pulse frequency fp, pump wave particle velocity amplitude value u(x), sound speed Co, probe wave pulse dispersion value σ ₀ ² and propagation distance x, the following formula or the following approximate formula is obtained. Therefore, the nonlinear coefficient β(x). Alternatively, it measures the distribution of the bio-nonlinear coefficient β'(x) within the subject.

β(x)=−C ₀ ² σ ₀ ² /4πfpu(x) d/dxKx(x) Kx(x)−DSS(x)/fx(x) Or the above damping coefficient α _o (x) and nonlinear coefficient β
(x), or the distribution of the bi-nonlinear coefficient β′(x) within the subject, or the above-mentioned attenuation coefficient α(x) and nonlinear coefficient β(x), or the distribution of the bi-nonlinear coefficient β′(x) within the subject. It measures the distribution of both.

Then, the pump wave particle velocity amplitude value u(x) is converted into the measured value of the pump wave intensity distribution by the attenuation coefficient α _o (x) of the object.
Alternatively, it is determined from a value corrected using the actually measured value of α(x).

In addition, in order to achieve the above object, the temperature measurement method of the present invention calculates the temperature inside the subject before and after heating from the acoustic property measurement value obtained by the acoustic property measurement method and the temperature dependence of the acoustic property value. It is designed to measure changes.

Furthermore, the temperature change within the subject before and after heating is measured based on the temperature dependence characteristic of the attenuation coefficient.

Further, in order to achieve the above object, the acoustic characteristic measuring device of the present invention includes an ultrasonic converter that sends out an ultrasonic probe wave pulse and a pump wave pulse having a lower frequency than the probe wave pulse; and means for controlling the phase relationship between the pump wave pulse and the pump wave pulse, means for frequency analyzing the received signal of the ultrasonic converter, and calculating a spectral ratio, a crossing frequency, and a degree of spectral separation based on the output of the frequency analysis means. It also has a signal processing means for calculating an attenuation coefficient from these crossover frequencies and spectrum separation.

Alternatively, the signal processing means calculates a spectral ratio, a crossing frequency, and a degree of spectral separation based on the output of the frequency analysis means, and also calculates a nonlinear coefficient or a binonlinear coefficient from these crossing frequencies and degree of spectral separation. It is something.

Alternatively, the signal processing means calculates a spectral ratio, a crossing frequency, and a degree of spectral separation based on the output of the frequency analysis means, and also calculates an attenuation coefficient from these crossing frequencies and a degree of spectral separation, and calculates a nonlinear coefficient or a binonlinear coefficient. It is designed to calculate.

Furthermore, in order to achieve the above object, the temperature measuring device of the present invention includes, in addition to the acoustic characteristic measuring device, a data reference section that refers to the temperature-dependent characteristics of the acoustic characteristic, and a data reference section that refers to the temperature-dependent characteristic of the acoustic characteristic; The apparatus includes a temperature calculation section that measures a temperature change based on the measured acoustic characteristics of the subject before and after heating and the temperature dependent characteristics obtained by referring to the data reference section.

Effects The present invention has the following effects due to the above configuration.

By superimposing the waveform center of gravity of the probe wave pulse on the intermediate part between the positive and negative peaks of the pump wave pulse particle velocity, that is, the peak part of particle acceleration, the peak of the particle velocity caused by the addition of both pulses is the pump wave pulse. It can be comparable to the particle velocity of the wave pulse itself. In addition, the driving timing of the transducer is adjusted so that the probe wave pulse is superimposed on the positive peak part of the particle acceleration of the pump wave pulse. The pump wave pulse and the probe wave pulse are arranged so that the spectrum of the received signal that has returned and the pump wave pulse are in opposite phase, that is, the probe wave pulse is superimposed on the negative peak part of the particle acceleration of the pump wave. Measure the spectral ratio, which is the ratio of the spectra of the received signal obtained by transmission, the crossover frequency obtained from the spectral ratio, and the slope of the spectral ratio, and calculate based on a predetermined relational expression from these crossover frequencies and spectral ratio slope. Determine the damping coefficient, nonlinear coefficient, or binonlinear coefficient using an algorithm.

Furthermore, the temperature inside the subject is determined by utilizing the fact that the acoustic characteristics change with temperature.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the principle of the measurement method used in the present invention will be explained with reference to FIG.

The sound velocity in the propagating medium of an infinitesimal amplitude sound wave is Co,
Let density ρo be the acoustic nonlinear parameter, and B/A be the acoustic nonlinear parameter. At that time, the propagation velocity of a finite amplitude sound wave is as follows (1), where the particle velocity in each part of the waveform is u and the sound pressure is Pp, the sound velocity C in each part is as follows (1),
It is obtained from equations (2) and (3).

C=Co+u+B/2A・Pp/ρoCo...(1) Co+(1+B/2A)u...(2) Co+βu...(3) Usually (1+B/2A) is called the coefficient of nonlinearity β. ing.

In addition, various acoustic properties β/Co ² , β/Co, β/
ρoCo ² , etc., but the acoustic characteristics related to these nonlinear coefficients β are collectively called binonlinear coefficients (associated
coefficient of nonlinearity) β′, which can be calculated from the nonlinearity coefficient β.

As is clear from the above relational expression, the speed of sound increases in the portion where the particle velocity of the pump wave is positive, and the speed of sound decreases in the portion where the particle velocity of the pump wave is negative.
Therefore, in the waveform of the pump wave, in the intermediate part where the particle velocity changes from negative to positive, that is, in the part where the particle acceleration is positive, the waveform in that part is compressed as it propagates, and vice versa. At the part, the waveform of that part is expanded. Therefore, Figure 1a
As shown in Figure 1b, the particle acceleration of the pump wave is compressed and the amplitude increases as the probe waveform superimposed on the positive part propagates, that is, its spectrum expands toward the high frequency side, and the pump wave The pulse of the probe wave superimposed on the part where the particle acceleration is negative is conversely stretched, its amplitude decreases, and the spectrum contracts toward the lower frequency side. The spectrum modulation characteristics based on the propagation of the probe wave pulse as described above can be analytically determined in the attenuation medium as follows.

First, for ease of understanding, it is assumed that acoustic attenuation, which is generally proportional to the n(x) power of frequency, is proportional to frequency. That is, it is assumed that n(x)=1 (the general case of the n(x) power will be described later).

Let the propagation direction of the probe wave be the x-axis, and let the power spectrum of the probe wave be p(f, x). When an RF pulse with a Gaussian envelope is used as the probe wave pulse, and it is assumed that acoustic attenuation is proportional to the first power of frequency, the power spectrum p(f, x) of the probe wave is equal to the propagation distance x (The attenuation coefficient and nonlinear coefficient are expressed as α(x) and β(x) as functions of propagation distance x.) .

p(f,x)=EXP[A ₀ −h(x)f−{g(x)f−f ₀ } ² /
2σ ₀ ² ...(4) where f ₀ is the center frequency of the RF pulse, σ ₀ ² is the dispersion of the probe wave pulse, and A ₀ is a constant.

The power spectrum p(f, x+△x) at the position x+△x, which is a short distance from the distance Z, has a frequency shift on the high frequency side or low frequency side due to attenuation proportional to the frequency and modulation by the pump wave superimposed on the probe wave. Considering the change, it can be expressed by the following equation (5).

p(f, x+△x)=EXP[A ₀ −h(x+△x)f −{g(x+△x)f−f ₀ } ² /2σ ₀ ² ] =e ^- 〓 ^(x)f △ ^x p(f/1+μ(x)△x,x) ...(5) Here, α(x) is the attenuation constant per unit frequency and unit length, and μ(x) is a function of the nonlinear coefficient β(x). Yes, next
It is given by equation (6).

μ(x)=2πfp(1+B(x)/2A(x))u(x)/Co ² =2πfp
β(x)u(x)/Co ² ...(6) where fp is the pump frequency and u(x) is the distribution of the amplitude value (peak value) of the particle velocity.

By comparing the above equations (4) and (5), a differential equation regarding the functions h(x) and g(x) of the propagation distance x is obtained as shown in the following equation (7).

d/dxh(x)=α(x)−μ(x)h(x) d/dxg(x)=−μ(x)g(x) ……(7) This differential equation can be expressed as equation (4) above. When solved under the initial condition (8), it is expressed as the following equation (9).

h(o)=O, g(h)=1 ……(8) h(x)=EXP{−∫ ^x _p μ(x)dx}・∫ ^x _p EXP{∫ ^x _p μ
(x)dx}α(x)dx g(x)=EXP{−∫ ^x _p μ(x)dx} ……(9) Substituting the above equation (9) into the above equation (4), any distance The power spectrum p(f, x) at x is obtained.

Here, the particle velocity amplitude value u(x) in equation (6) above takes both positive and negative values, and a positive value corresponds to the probe wave frequency being modulated to the high frequency side, as shown in Figure 1a. corresponds to Further, a negative value corresponds to modulation of the probe wave frequency image to the low frequency side, and corresponds to FIG. 1b. In other words, the fact that the pump wave is at the positions a and b in Figure 1 corresponds to u(x) = μo(x) and μ(x) = -μo(x), so the function h±(x) at that time is If g±(x) is the following equation (10), the power spectrum of the probe wave p+
(f, x) and p-(f, x) are expressed by the following equation (11).

h±(x)＝EXP{〓∫ ^x _p μ ₀ (x)dx}・∫ ^x _p EXP{±
∫ ^x _p μ ₀ (x)dx) α(x)dx g±(x)=EXP{〓∫ ^x _p μ ₀ (x)dx ……(10) p+(f,x)=EXP〔A ₀ − h+(x)f-
{g+(x)f−fo} ² /2σ ₀ ² ] p−(f, x)=EXP[A ₀ −h−(x)f−
{g-(x)f-fo} ² /2σ ₀ ² ] ...(11) The spectral ratio R(f, x) is the logarithmic ratio of the power spectra p+(f, x) and p-(f, x) Next(12)
It is expressed by the formula.

R(f, x) ≡log {P-(f, x)/P+(f, x)} ...(12) Here, when the energy density of the pump wave is small enough not to cause cavitation, |
∫ ^x _p μo(x)dx|≪1, so the following equation (13), which is an approximate equation, holds true.

EXP {±∫ ^x _p μo(x)dx}≒1±∫ ^x _p μo(x)dx ……(13) Based on the approximation of this equation (13), the above (10), (12), ( From equation 13), the spectral ratio R(f, x) is expressed by the following equation (14).

R (f, x) = 2f・∫ ^x _p μo(x)dx・[f _p −f/σ _p ²
−∫ ^x ／ _p {μo(x)∫ ^x ／ _p α(x)dx}dx／∫ ^x ／ _p μo(x)dx
]...(14) Since the crossover frequency fx is the frequency where the power spectra p+(f, x) and p-(f, x) of the probe wave are equal, the spectral ratio R(f _x , x) = 0 holds. It is the frequency. Therefore, from the above equation (14), it is expressed by the following equation (15).

f _x (x) = f _p −σ _p ² ／∫ ^x ／ _p μo(x)dx∫ ^x _p {μo(x)∫ ^x _p
α(x)dx}dx ...(15) Here, the crossing frequency f _x is regarded as a function of x and is expressed as f _x (x).

Next, the value at the intersection frequency of the slope of the spectral ratio R(f,

DSS(x)≡ [∂/∂fR( _f , is expressed by the following equation (17).

DSS(x)=−2f _x (x)/σ _p ² ∫ ^x _p μo(x)dx ……(17) Expressing this equation (17) in terms of μo(x) and using the above equation (16), we get The nonlinear coefficient β(x) is obtained using the following equation (18).

β(x)=−C _p ² σ _p ² ／4πfpu(x) d／dxK _x (x)……(
18) K _x (x)≡DSS(x)／f _x (x) ……(19) In other words, if the pump wave intensity distribution is known as a function of x, the pump wave particle velocity amplitude value u(x) is obtained, the crossover frequency f _x (x) and the spectral separation DSS(x)
From the measured value of , the nonlinear coefficient β(x) is given by the above equations (18) and (19). The intensity distribution of the pump wave is determined by measuring the intensity distribution underwater in advance, and then correcting the attenuation by using the measured value α(x) of the attenuation coefficient of the object, which is determined by the method described later. It can be obtained by doing .

Or, the attenuation coefficient is approximately /neper/M in living organisms.
Since it is Hz/cm, this value may be used for estimation. In any case, if the particle velocity amplitude value u(x) of the pump wave can be obtained by some method, the nonlinear coefficient β(x)
is required. Also, the bi-nonlinear coefficient β'(x) can be found in the same way from β(x).

Next, the damping coefficient α(x) can be obtained by displaying the above equation (15) for the α(x) equation and substituting the above equations (18) and (19).
It is obtained using the following equation (20).

d(x)=-1/σ _p ² d/dx [d/dx {K _x (x)f _x (x)}/
d/dxK _x (x)]...(20) K _x (x)≡DSS(x)/f _x (x)...(19) In other words, the cross frequency f _x (x) and the degree of spectral separation
The damping coefficient α(x) is determined from the measured value of DSS(x).

To summarize the above results, the spectral ratio R (f, x) can be obtained from the measured values of the probe wave power spectra p + (f, x) and p - (f, x) using the above equation (12), and from this The crossing frequency f _x (x) of the actual measurement value is R(f _x ,
It is obtained from x)=0. Furthermore, the measured value of spectral separation DSS(x) can also be obtained from the above equation (16). From these, the damping coefficient α(x) can be obtained using equations (19) and (20) above. If the pump wave velocity amplitude value u(x) in the test object is known, the nonlinear coefficient β(x) can be calculated using the spectral separation degree DSS.
(x) and the crossover frequency f _x (x), it is given by the above equations (18) and (19). However, Co ² , σo ² , fp, etc. are naturally known quantities.
Furthermore, the bi-nonlinear coefficient β'(x) can also be obtained from the nonlinear coefficient β(x).

As mentioned above, by actually measuring the crossover frequency f _x (x) and spectral separation degree DSS(x) of the object using the device described later, the attenuation coefficient α(x) and nonlinear coefficient β(x) can be obtained. Become.

The explanation up to now is based on the assumption that attenuation is proportional to frequency, that is, n(x)=1, but the following describes the case of acoustic attenuation that is proportional to the n(x) power of the general frequency.

Acoustic attenuation is αn(x)f ⁿ (x) at the n(x) power of the frequency, but considering only the vicinity of the cross frequency f _x (x), it expands at the frequency f near f _x (x). Approximate it as follows.

α _o (x)f ^n(x) ≒ [α _o (x)f ^n(x) ] f=f _x + [∂/∂fα _o (x)f ^n(x) ] f=f _x・_f = α (xo) f + α _c (xo) ... (21) α _c (x)≡ [α _o (x)f ^n(x) ] f=f _x = α _o (x)f _x (x) ^{n(x )}
...(22) α(x)≡ [∂／∂fα _o (x)f ^n(x) ] f=f _x =α _o (x)n(x)f _x (x) ^n(x)-1 ...(23) When the coefficients α(x) and αc(x) are defined by the above equations (21) and (22), the damping coefficient α(x) is proportional to the frequency f near the attenuation f _x (x). In the part, αc(x) means a constant component. With this approximation, the paraspectrum p(f, x) corresponding to the above equation (4) can be obtained using the following equation (24).

p (f, x) = EXP [Ao−h _c (x)−h(x)f−{
g(x)f−f _p } ² /2σ _p ² ]...(24) In the above equation (24), hc(x) is added to the above equation (4). Here, if the change in the power spectrum due to the propagation of Δx is considered in the same way as above, the following equation (25) holds true.

p(f, x+△x)=EXP[Ao−hc(x+△x) −h(x+△x)f−
{g(x+△x)f−fo} ² /2σo ² ] =e ^- { ^d(x)f+ 〓 ^c(x) }△ ^x p(f/1+μ(x)△x, ) As a result, corresponding to equation (7) above, hc(x), (x),
When a differential equation regarding g(x) is created, the following equation (26) is obtained.

d/dxhc(x)=α _c (x) d/dxh(x)=α(x)−β(x)h(x) d/dxg(x)=−β(x)g(x) …… (26) Here, the differential equation of hc(x) has been added to equation (26) above. Solving this using the initial condition and equation (27) yields equation (28).

hc(o), h(o)=0, g(o)=1 ...(27) hc(x)=∫ ^x _p αc(x)dx h(x) h(x) =EXP{−∫ ^x _p μ(x)dx}・∫ ^x _p EXP{∫ ^x _p μ(x)dx}α
(x)dx g(x)=EXP{−∫ ^x _p μ(x)dx} ...(28) Substituting the above equation (28) into the above equation (24), p
(f, x) is obtained, and depending on the position of the probe wave and pump wave, p±(f, x) corresponds to μ(x) = ±μo(x).
is determined, and its logarithmic ratio is determined using equation (12) above.

^p ±( ^f , ) does not depend on μ(x), so there is no change in ±.

R( ^{f ,} g−(x)f−fo) ² ] …(30) In the above equation (30), the term hc(x) is eliminated by division, so it disappears, and R(f, The exact same formula as x) is obtained. That is, hc(x) is μ
Since (x) does not change by changing μ(x) = ±μo(x), it is eliminated by division, and R(f, x) becomes exactly the same formula as the above formula (14). . As a result, R(f,
The above (17), (18), obtained by calculating from x)
DSS(x), β(x), Kx(x), α(x), etc. in equations (19) and (20) are determined by exactly the same equation. As shown in equation (13) above, if |∫ ^x _p μo(x)dx| You may do so. As a result, by solving the above equation (23) for αn(x) and substituting the above equation (21), the following equation (31) can be obtained: can get.

αn(x)=1/n(x)fx(x) ^1-n(x) α(x) =-fx(x) ^1-n(x) /σo ² n(x) d/dx[d/ dx{Kx(x)f
x(x)}／d／dxKx(x)〕
...(31) Here, n(x) is generally an unknown function. However, in the case of a living body, n(x) is considered to be about 1 to 1.5, and it may be set to an appropriate average value, for example, h(x) = 1.2, or more precisely, various tissues of the living body (fat, muscle, (bones, etc.) and maintain it in advance as a database and refer to it for each promotion location x to generate n(x)
It is also possible to determine. Also, in a simple approximation, if n(x) = 1, the above equation (31) matches the above equation (20), and αn(x) = α(x), which of course is the above result. This results in attenuation proportional to frequency. That is, if n(x) is determined according to the required accuracy, the attenuation coefficient αn(x) can be obtained from the above equation (31).

A method for specifically measuring the various acoustic characteristics for which the above analytical relationships have been clarified, and a method for determining temperature changes within the subject using these measured acoustic characteristics, along with the equipment and drawings. This will be explained with reference to.

FIG. 2 is a functional block diagram showing an ultrasonic temperature measuring device in one embodiment of the present invention. The basic principle of the present invention is an ultrasonic pulse reflection method for receiving so-called echo signals. In FIG. 2, 1 indicates the transmission of pump wave pulses, the transmission of probe wave pulses,
2 is a pulse driver that applies drive pulses for pump waves to ultrasonic converter 1; 3 is a pulse drive that applies drive pulses for probe waves to ultrasonic converter 1; 4 is an amplifier that amplifies the received output of the ultrasonic converter 1, 5 is a waveform storage unit that stores the output of the amplifier 4, and 6 is a timing that controls the operation timing of the pulse drivers 2, 3 and the waveform storage unit 5. 7 is a clock generation unit that supplies clocks to the waveform storage unit 5 and timing control unit 6; 8 is a frequency analysis unit that performs Fourier transform on the waveform stored in the waveform storage unit 5; 9 is a frequency analysis unit A signal processing unit performs signal processing on the output of 8 to obtain acoustic characteristics; 10 is a temperature calculation unit that calculates the temperature based on the output of the signal processing unit 9; and 11 provides temperature dependence information of acoustic characteristics to the temperature calculation unit 10. 12 is a detection unit that detects the output of the amplifier 4; 13 is the output of the signal processing unit 9 to generate an acoustic characteristic distribution image, the output of the temperature calculation unit 10 to generate a temperature distribution image, and the output of the detection unit 12 to generate an acoustic characteristic distribution image; A scan conversion unit creates a B-mode tomographic image; 14 is a display unit that displays the output of the scan conversion unit 13; and 16 is a subject (living body).

FIG. 3 is a configuration diagram showing a preferred example of the ultrasonic converter 1. As shown in FIG. As shown in FIG. 3, the ultrasonic converter 1 is composed of a pump wave transducer 101 and a probe wave transducer 102. The pump wave vibrator 101 has, for example, a center wave number of 300 KHz, an outer diameter of 60 mm,
The probe wave vibrator 102 is composed of an annular piezoelectric vibrator with an inner diameter of 20 mm, and has a center frequency of 3M, for example.
It consists of a convergence type piezoelectric vibrator with a frequency of 20 mm and an outer diameter of 20 mm. The output level of the pump wave transducer 101 is approximately 250 mm/s in terms of particle velocity amplitude, and approximately 4 W/cm ³ as a peak output in water, and the output level of the probe wave transducer 102 is approximately 250 mm/s in particle velocity amplitude, and the output level of the probe wave transducer 102 is approximately 250 mm/s in particle velocity amplitude. It should be at the level used or a little lower than that. It is desirable that the spectrum characteristics of the probe wave pulse have a Gaussian shape, and therefore the frequency characteristics of the probe wave transducer 102 and the frequency characteristics of the drive pulse of the pulse driver 3 are adjusted. On the other hand, in order to avoid mixing the high-frequency side components of the frequency characteristics of the pump wave pulse into the band of the frequency characteristics of the probe wave pulse,
In the pulse driver 2, high frequency components in the output are suppressed.

The pump wave pulse transmitted from the pump wave vibrator 101 and the probe wave vibrator 1 as described above.
The probe wave pulses transmitted from 02 cross and overlap in the coupling medium 161 to become a superimposed pulse, and then enter the subject 16. For example, a liquid such as water is suitable as the coupling medium 161, and its depth, that is, the distance between the sound wave emitting surface of the probe wave transducer 102 and the subject 16, is, for example,
Approximately 100mm is selected. While this superimposed pulse propagates through the subject 16, the probe wave pulse is modulated. This modulation characteristic depends on which part of the pump wave pulse the center of gravity of the waveform of the probe wave pulse is superimposed on. If the superimposed part has a positive peak particle velocity of the pump wave as shown in Figure 8a, the phase relationship is A, and if the particle velocity has a negative peak as shown in Figure 8b, the phase relationship is A. Relationship B, phase relationship C when the particle acceleration is at a positive peak as shown in Figure 1a, and phase relationship D when the particle acceleration is at a negative peak as shown in Figure 1b. Distinguish between states of superposition. The control of the phase relationship as described above is performed by controlling the mutual timing of drive pulse generation of the pulse drivers 2 and 3 by the timing control section 6. In reality, the time relationship between the operations of the pulse driver 3 for the probe wave and the waveform storage section 5 is fixed, and the pulse generation timing of the pulse driver 2 for the pump wave is controlled, or the polarity of the drive pulse is reversed. What is done is done. The time resolution of timing control is, for example, approximately 1/64 of one wavelength of the pump wave, which in this case is approximately 50 ns.
becomes. 50ns for such time control
This can be realized using digital delay technology using a (20MHs) clock signal and a preset counter. This clock signal is supplied from the clock generator 7.

In this way, the probe wave pulse whose superimposed phase relationship is controlled propagates through the object 16 while undergoing modulation corresponding to each phase state, and further
Due to the sound wave scattering properties of the probe wave transducer 6, the waves are scattered one after another, and the probe wave transducer 1 is reflected as a reflected signal.
02 and is converted into a received signal. Although not shown, the entire ultrasonic modulator 1 may be oscillated by a mechanical scanning mechanism to perform sector scanning, for example. After the received signal is amplified by the amplifier 4, it is stored in the waveform storage section 5. The waveform storage section 5 is composed of, for example, an A/D converter, a high-speed memory, and the like.
The frequency of the sampling clock of the A/D converter is the frequency of the received signal, in this case 4MHz of 3MHz.
It is desirable that the frequency be at least twice that, and 20MHz is an appropriate frequency. This sampling clock is also supplied from the clock generator 7. A portion of the received signal stored in the waveform storage unit 5 at a required position and length is extracted by a data window, and is subjected to Fourier transformation in a frequency analysis unit 8. The length of this extracted portion, that is, the data window, is about 40 waves of the frequency of the received signal, which is about 13 μs here. The number of data points within the data window is equal to the product of the length of the data window and the frequency of the sampling clock, so in this example there are 260 points. This extracted data string may be multiplied by a window function such as a Hamming window, or the number of data points may be changed to a power of 2, such as 256 points, in order to adapt it to the fast Fourier transform algorithm. good. This Fourier transform is
The data window is repeatedly moved in the depth direction of 6, that is, in the depth direction of the data string, and in this example, the movement pitch is, for example, a minute distance of 1.25 mm within the subject 16. The minute time △t _p required for the sound wave to travel back and forth over this minute distance is the subject 1
If the sound speed in 6 is 1500m/s, approx.
It becomes 1.6μs. In the manner described above, the received signal is extracted while moving through the data window at minute intervals of time Δt _p , and Fourier transform is performed one after another. The result of Fourier transform is a complex number, whose real part Re(f,
Further, the power spectrum P(f, x) or the phase angle φ(f, x) is calculated from the imaginary part Im(f, x) using the following equations (32) and (33), respectively.

P (f, x) = Re ² (f, x) + Im ² (f, x)
...(32) φ(f, x) = arctan {Im(f, x)/Re(f,
x)} ...(33) The pump wave pulse and probe wave pulse are shown in Figure 1a.
The portion of the received signal obtained by being superimposed with the phase relationship C shown in FIG. 1 or the phase relationship D shown in FIG. The power spectrum for a data sequence extracted by a data window located at a depth corresponding to the ROI can be expressed as in the following equation (34) using a simple propagation model.

P±(f, x) | {H±(f, x)・S±(f, x)・
G(f, x)・T(f)}W(f)｜ ² ...(34) However, H±(f, x); probe wave pulse spectrum after modulation S±(f, x); of ROI Sound wave scattering characteristics G(f, x); Linear propagation attenuation on return path T(f); Receiving system frequency characteristics W(f); Convolution by window function ±; +...Sound wave transmission by phase function C -...Phase Sound wave transmission according to relationship D In such a propagation model, first, a sound wave is transmitted to a specific ROI within the subject 16 according to the phase relationship C shown in FIG. 1a, and the power spectrum P +
(f, x), then set the transmission interval T ₀ and set the first
A sound wave is transmitted with the phase relationship D shown in FIG. b, the power spectrum P-(f, x) is determined, and the ratio of both power spectra is evaluated logarithmically. In addition, the transmission interval T ₀
The time is normally a value used in ultrasonic diagnostic equipment, for example, from several hundred μs to about 1 ms. In the following equation, the sound wave scattering characteristics S+ (f, x) and S-
If the difference in (f, x) and the influence on the window function are small, S±(f, x), G(f, x), T(f), W(f)
All terms in are eliminated, and the left side becomes the above equation (12), (30)
It is equal to 1/2 of the spectral ratio R(f, x) shown in the formula.

R(f,x)=log{P-(f,x)/P+(f,x)
}=2log{|H−(f,x)/H+(f,x)|}
...(35) The relationship between the spectral ratio R(f, x) and various acoustic characteristics is already shown in equations (18), (19), (20), and (31) above, and In this section, various acoustic characteristics are calculated based on these relational expressions.

Figure 4 shows the power spectrum P±(f, x) and spectral ratio R when an ultrasound test phantom made to resemble a liver is used as the subject 16.
This is an example of an actual measured value of (f, x), but a considerable ripple component is added as noise to the spectral ratio R(f, x), which has a negative impact on the determination of the crossing frequency fx(x). . In order to reduce this influence, the signal processing section 9 performs
In this example, in the range of about 2 to 3 MHz, the obtained spectral ratio R(f, Determine the frequency fx(x). The method of least squares or the like can be used to select the approximate function. Next, the spectral ratio R(f,
x), that is, the spectral separation degree DSS(x) of equation (16) above. Spectral separation DSS
(x) is also actually found from the differentiation of the approximation function. the above
In equations (18) and (19), DSS(x) and fx(x) are measurable quantities,
The pump wave frequency fp, the spectral dispersion σ ₀₂ of the probe wave pulse, the sound speed Co, etc. are known quantities. Here, the particle velocity amplitude value u(x) of the pump wave is given by the following equation (36) if the sound pressure amplitude value Pp(x) of the pump wave is known.

u(x)=1/ρoCoPp(x) (36) where ρ ₀ is the density of the propagation medium.

The sound pressure amplitude value Pp(x) of the pump wave may be a value measured in advance with an ultrasonic transducer using a pseudo medium such as water, but it is appropriate to take into account the acoustic attenuation of the actual object. decay rate, for example in living organisms
Either estimate and correct the acoustic attenuation at around 1neper/MHz cm, or use the method described later to adjust the acoustic attenuation coefficient α _o
(x) or α(x) is measured as an actual value, and the particle velocity u(x) is calculated using the sound pressure with the attenuation corrected using that value.
Determine the particle velocity amplitude value u(x) by a method such as calculating.

Since all the quantities in equations (18) and (19) above can be determined from these, the nonlinear coefficient β(x) and the binonlinear coefficient β'(x) can be calculated. Attenuation coefficient α _o (x), or α(x) is the nonlinear coefficient β(x)
It can be found by simple calculation by comparing. That is, it is determined by the above equations (19) and (31) from the actually measured values of the cross frequency f _x (x), the spectral separation degree DSS(x), and the known amount of dispersion value ρ ₀₂ . However, an appropriately assumed value is used for n(x).

As mentioned above, the signal processing section 9 in FIG. 2, which has the software programmed with the contents explained in detail from equation (21) onwards, performs computer processing as digital data, so that the signal processing section 9 can calculate the frequency From the data of the analysis unit 8, acoustic characteristic values such as attenuation coefficient α _o (x), α(x), nonlinear coefficient β(x), binonlinear coefficient β(x), etc. are calculated.

Further, in order to speed up the above calculation, the above calculation process may be configured by dedicated hardware.

As described above, the attenuation characteristic α _o (x) on the acoustic scanning line, that is, on the propagation path of the probe wave pulse,
The distribution of α(x) nonlinear coefficient β(x) can be obtained.
These acoustic characteristic values can be regarded as average acoustic characteristic values at a portion of the subject 16 shown in FIG. 3 that corresponds to the data window. Normally, when investigating acoustic characteristic values at a specific location on a tomographic image, a virtual region called a region of interest (ROI) is set on the tomographic image, and the average acoustic characteristic value within that ROI is calculated. set to target. FIG. 5 shows an example of boundaries of a plurality of ROIs 52 displayed on a fan-shaped scanning tomographic image 51. As is clear from this, the shape of the boundary line is part of a sector. ROI52
The dimensions are selected to be, for example, about 1 cm in the direction of the propagation depth and about 1 cm in the direction orthogonal thereto. Therefore, in reality, a large number of acoustic scanning lines pass through the inside of the ROI 52, and the data windows on these acoustic scanning lines are also
There are many things that overlap with ROI52. ROI5 is obtained from a large number of acoustic characteristic values corresponding to these many data windows.
2, for example, the acoustic characteristic value corresponding to the acoustic scanning line passing through the center of the ROI 52, or the acoustic characteristic value corresponding to the data window that overlaps with the ROI 52 in many parts. It is also possible to weight them and find the average.
In the signal processing section 9, acoustic characteristic values are determined from the power spectrum of the received signal as described above. The temperature calculation unit 10 calculates a temperature change for each ROI based on the temperature dependence characteristics of the attenuation coefficient and the bi-nonlinear coefficient. FIG. 6 is a typical example showing the temperature dependence of the attenuation coefficient and the speed of sound in biological soft tissues. As is clear from the figure, the temperature dependence of the attenuation coefficient is relatively large, while that of the sound velocity is small.Furthermore, the trends of these temperature-dependent characteristics are quite different between adipose tissue and non-adipose tissue. Moreover, these temperature dependences can be expressed by the simple temperature T
It can be seen that it is not expressed by a linear function, and approximation by a high-order polynomial is more desirable. Note that the temperature dependence of the nonlinear parameter B/A is considered to be quite small, and therefore, the temperature dependence of the biononlinear coefficient β' is considered to be dominated by the temperature dependence of the sound speed in its denominator.

FIG. 7 is a functional block diagram showing an example of the temperature calculation section 10. In the figure, 1001 is a memory (IDM) prepared for each ROI, which stores acoustic characteristic values in an initial state. In this case, the initial state means, in applications such as hyperthermia, the state of normal body temperature before heating the living body. Next, RIO
Each time, the data reference unit 11 is referred to using the values of the attenuation coefficient and bi-nonlinear coefficient stored in the memory 1001. These attenuation coefficients and bi-nonlinear coefficients are effective as parameters for tissue diagnosis, and for example, these values differ significantly between adipose tissue and non-adipose tissue. Therefore, the data reference unit 11 can determine the tissue properties based on the references to these attenuation coefficients and bi-nonlinear coefficients, and the data reference unit 11 can determine the tissue properties based on the references from the memory 1001.
Temperature-dependent properties of tissue acoustic properties in the ROI can be specified. When the temperature characteristic is γ(T),
γ(T) is a first-order or higher-order polynomial that satisfies the following equation (37).

a(T)=a _p・γ(T)...(37) However, a _p is the acoustic characteristic in the initial state.

a(T): Acoustic characteristics when changed by T°C from the initial state.

As a method of specifying γ(T), it is sufficient to use only the coefficient values of each degree of the polynomial, and it is stored in the data reference unit 11 in the form of coefficients. The coefficient value of the temperature characteristic γ(T) referenced for each ROI is stored in the memory (TCM) 1002.
is memorized. In this case, it is assumed that only the damping coefficient is specified for the temperature characteristic γ(T). Arithmetic unit (TD) 1
In 003, an appropriate temperature range, for example, 35°C to 50°C, is set based on the coefficient value stored in the memory 1002 and the damping coefficient in the initial state stored in the memory 1001.
The attenuation coefficient at a suitable temperature pitch, for example 1° C., is calculated for each ROI and stored in the memory (RDM) 1004. Next, the attenuation coefficient after heating is stored in the memory (CDM) 1005.
The data stored in memory 1005 is stored in memory 1
A calculation unit (CDM) 1006 compares which of the data stored in 004 corresponds, that is, how many changes corresponds to the data. Comparison is performed for each ROI by this calculation 1006, and the value of temperature change is stored in a memory (TOR) 1007.
The value of the temperature change T determined as described above is sent to the scan converter 13, and it becomes possible to obtain a two-dimensional temperature distribution image.

In addition, in the above example, an example was explained in which the temperature change is calculated for all ROIs and displayed as an image, but the temperature change may be calculated only for a specific ROI, or the calculation result can be displayed as a numerical value. It's okay. Furthermore, simply displaying acoustic characteristic values such as the distribution of attenuation coefficients and the distribution of bi-nonlinear coefficients obtained during signal processing as images is highly useful in terms of tissue diagnosis. Further, the obtained acoustic characteristic values including the value of the frequency-dependent characteristic n of ultrasonic attenuation may be displayed as numerical values. Further, the dependence of the cross frequency and the degree of spectral separation in the direction of propagation depth itself is also an indicator of the acoustic characteristics of the propagation medium, and may therefore be displayed. In addition, in the case of a homogeneous specimen with known temperature-dependent characteristics, highly accurate temperature measurement is possible even if the known temperature-dependent characteristics are prepared in advance and applied to all ROIs for temperature calculation. .

Effects of the Invention As described above, according to the present invention, by superimposing the center of gravity of the probe wave pulse on the peak part of the particle acceleration of the pump wave pulse, the peak of the particle velocity caused by the addition of both pulses is The particle velocity can be made comparable to the particle velocity of the pump wave pulse itself, so there is no concern that abnormal distortion will be caused to the probe wave pulse, and it is highly safe for living organisms.

Further, it is possible to obtain the ultrasonic attenuation characteristic and the bio-nonlinear coefficient at the same time, and it is possible to perform tissue diagnosis or temperature measurement with higher accuracy based on these two acoustic characteristic values.

[Brief explanation of drawings]

Figures 1a and b are for explaining the principle of the acoustic characteristic measuring method according to an embodiment of the present invention, and are diagrams showing a state in which a pump wave pulse and a probe wave pulse are superimposed, and Figure 2 is an embodiment of the present invention. FIG. 3 is a functional block diagram of an ultrasonic temperature measuring device according to the present invention, and FIG.
FIG. 4 is a diagram showing the spectral ratio of the received signal obtained in one embodiment of the present invention, FIG. 5 is a diagram showing an example of the boundary line of the region of interest (ROI), and FIGS. FIG. 7 is a functional block diagram showing details of an example of the temperature calculation unit used in the ultrasonic temperature measuring device of the present invention, and FIG. 8a, b is a diagram showing a state in which pump wave pulses and probe wave pulses are superimposed in a conventional acoustic characteristic measuring method. 1...Ultrasonic conversion section, 2, 3...Pulse driver, 8...Frequency analysis section, 9...Signal processing section, 1
0...Temperature calculation section, 11...Data reference section, 13
...Scan converter, 14...Display section, 101...Pump wave transducer, 102...Probe wave transducer.

Claims (1)

[Claims] 1. A probe wave pulse which is an ultrasonic pulse, and a pulse in which the waveform center of gravity of this probe wave pulse is superimposed on the part where the particle acceleration of a pump wave pulse having a lower frequency than this probe wave pulse is at its peak. This signal is sent to two inside the subject.
Receive by reflecting at reflection points at different depths,
Frequency analysis of this received signal is performed to obtain a spectral ratio, and from this spectral ratio, the distribution of the cross frequency fx(x) and spectral separation degree DSS(x) within the subject is measured, and these cross frequencies fx(x) , the spectral separation degree DSS(x) and the dispersion value of the probe wave pulse σ ₀ ²
and an acoustic characteristic characterized by measuring the distribution within the subject of an attenuation coefficient αn(x) proportional to the n(x) power of the frequency using the following equation or an approximation of the following equation from the propagation distance x. Measuring method. αn(x)=−fx(x) ^1-n(x) /σ ₀ ² n(x) d/dx [d/dx{
Kx(x)fx(x)}/d/dxKx(x)〕 Kx(x)≡DSS(x)/fx(x) 2 Probe wave pulse, which is an ultrasonic pulse, and the waveform center of gravity position of this probe wave pulse A pulse superimposed on the peak part of the particle acceleration of a pump wave pulse having a lower frequency than this probe wave pulse is transmitted into the subject, and this transmitted signal is transmitted to two pulses within the subject.
Receive by reflecting at reflection points at different depths,
Frequency analysis of this received signal is performed to obtain a spectral ratio, and from this spectral ratio, the distribution of the cross frequency fx(x) and spectral separation degree DSS(x) within the subject is measured, and these cross frequencies fx(x) , the spectral separation degree DSS(x) and the dispersion value of the probe wave pulse σ ₀ ²
and propagation distance x, using the following equation or an approximation of the following equation to measure the distribution within the subject of the attenuation coefficient α(x), which is assumed to be proportional to frequency. α(x)=-1/σ ₀ ² d/dx [d/dx {Kx(x)fx(x)}/
d/dxKx(x)〕 Kx(x)≡DSS(x)/fx(x) 3 The probe wave pulse, which is an ultrasonic pulse, and the waveform center of gravity of this probe wave pulse are set by a pump with a lower frequency than this probe wave pulse. A pulse superimposed on the part of the wave pulse where the particle acceleration is at its peak is transmitted into the subject, and this transmitted signal is transmitted to two pulses within the subject.
Receive by reflecting at reflection points at different depths,
Frequency analysis of this received signal is performed to obtain a spectral ratio, and from this spectral ratio, the distribution of the cross frequency fx(x) and spectral separation degree DSS(x) within the subject is measured, and these cross frequencies fx(x) , spectral separation degree DSS(x), pump wave pulse frequency fp, pump wave particle velocity amplitude value u(x), sound speed C ₀ , probe wave pulse dispersion value σ ₀ ² and propagation distance x, the following equation is obtained.
Alternatively, the nonlinear coefficient β(x),
Alternatively, an acoustic characteristic measuring method characterized by measuring the distribution of the binonlinear shape coefficient β'(x) within the subject. β(x)=−C ₀ ² σ ₀ ² /4πfpu(x) d/dxKx(x) Kx(x)≡DSS(x)/fx(x) 4 Probe wave pulse, which is an ultrasonic pulse, and this probe A pulse in which the center of gravity of the wave pulse is superimposed on the part where the particle acceleration of the pump wave pulse having a lower frequency than the probe wave pulse is at its peak is transmitted into the subject, and this transmitted signal is transmitted to two points within the subject.
Receive by reflecting at reflection points at different depths,
Frequency analysis of this received signal is performed to obtain a spectral ratio, and from this spectral ratio, the distribution of the cross frequency fx(x) and spectral separation degree DSS(x) within the subject is measured, and these cross frequencies fx(x) , the spectral separation degree DSS(x) and the dispersion value of the probe wave pulse σ ₀ ²
Then, from the propagation distance From the crossover frequency fx(x), spectral separation degree DSS(x), pump wave pulse frequency fp, pump wave particle velocity amplitude value u(x), sound speed C ₀ , probe wave pulse dispersion σ ₀ ² and propagation distance x An acoustic characteristic measurement method characterized by measuring the distribution of the nonlinear coefficient β(x) or the binonlinear coefficient β′(x) within the subject using the following equation () or an approximate equation of the following equation () . αn(x)=−fx(x) ^1-n(x) /σ ₀ ² n(x) d/dx [d/dx{Kx
(x)fx(x)}／d／dxKx(x)〕 Kx(x)≡DSS(x)／fx(x) …() β(x)＝−C ₀ ² σ ₀ ² ／4πfpu(x) d/dxKx(x) Kx(x)≡DSS(x)/fx(x) …() 5 The probe wave pulse, which is an ultrasonic pulse, and the waveform center of gravity position of this probe wave pulse are set at a frequency higher than this probe wave pulse. A pulse superimposed on the peak part of the particle acceleration of the low pump wave pulse is transmitted into the subject, and this transmitted signal is transmitted to two pulses within the subject.
Receive by reflecting at reflection points at different depths,
Frequency analysis of this received signal is performed to obtain a spectral ratio, and from this spectral ratio, the distribution of the cross frequency fx(x) and spectral separation degree DSS(x) within the subject is measured, and these cross frequencies fx(x) , the spectral separation degree DSS(x) and the dispersion value of the probe wave pulse σ ₀ ²
Then, from the propagation distance x), spectral separation degree DSS(x), pump wave pulse fp, pump wave particle velocity amplitude value u(x), sound speed C ₀ , probe wave pulse dispersion σ ₀ ² and propagation distance x, the following formula (), Alternatively, the nonlinear coefficient β can be calculated using the following approximate expression ()
1. An acoustic characteristic measuring method characterized by measuring the distribution of (x) or the bi-nonlinear coefficient β'(x) within a subject. d(x)=-1/σ ₀ ² d/dx [d/dx{Kx(x)fx(x)}/
d／dxKx(x)〕 Kx(x)≡DSS(x)／fx(x) …() β(x)＝−C ₀ ² σ ₀ ² ／4πfpu(x) d／dxKx(x) Kx(x )≡DSS(x)/fx(x) …() 6 Correct the pump wave particle velocity amplitude value u(x) using the measured value of the pump wave intensity distribution using the measured value of the attenuation coefficient αn(x) of the test object 5. The method for measuring acoustic characteristics according to claim 3, wherein the acoustic characteristics are determined from the calculated values. 7. Claim 3 or 4, characterized in that the pump wave particle velocity amplitude value u(x) is determined from a value obtained by correcting the measured value of the pump wave intensity distribution using the measured value of the attenuation coefficient α(x) of the object. Acoustic property measurement method described. 8. A measurement characterized in that the temperature change before and after heating is measured from the acoustic property measurement value obtained by the acoustic property measurement method according to any one of claims 1 to 7 and the temperature dependence characteristic of the acoustic property value. Warm method. 9. The temperature measurement method according to claim 8, characterized in that temperature changes within the subject before and after heating are measured based on the temperature dependence characteristic of the attenuation coefficient. 10 an ultrasonic converter that sends out an ultrasonic probe wave pulse and a pump wave pulse having a lower frequency than the probe wave pulse; and means for controlling the phase relationship between the probe wave pulse and the pump wave pulse;
Means for frequency analysis of the received signal of the ultrasonic converter, calculating a spectral ratio, cross frequency and degree of spectral separation based on the output of the frequency analysis means, and calculating an attenuation coefficient from these cross frequencies and degree of spectral separation. 1. An acoustic characteristic measuring device comprising a signal processing means for calculating. 11. An ultrasonic conversion unit that sends out an ultrasonic probe wave pulse and a pump wave pulse having a lower frequency than the probe wave pulse, and means for controlling the phase relationship between the probe wave pulse and the pump wave pulse;
Means for performing frequency analysis of the received signal of the ultrasonic converter, calculating a spectral ratio, cross frequency, and degree of spectral separation based on the output of the frequency analysis means, and calculating a nonlinear coefficient from these cross frequencies and degree of spectral separation; or a signal processing means for calculating bi-nonlinear coefficients. 12. An ultrasonic conversion unit that sends out an ultrasonic probe wave pulse and a pump wave pulse having a lower frequency than the probe wave pulse, and means for controlling the phase relationship between the probe wave pulse and the pump wave pulse;
Means for frequency analysis of the received signal of the ultrasonic converter, calculating a spectral ratio, cross frequency and degree of spectral separation based on the output of the frequency analysis means, and calculating an attenuation coefficient from these cross frequencies and degree of spectral separation. 1. An acoustic characteristic measuring device comprising: signal processing means for calculating nonlinear coefficients or binonlinear coefficients. 13. The acoustic property measuring device according to any one of claims 10 to 12, further comprising: a data reference unit that refers to the temperature dependent property of the acoustic property; and a data reference unit that refers to the temperature dependent property of the acoustic property, and a temperature dependent property obtained from the data reference unit and the acoustic property measuring device. 1. A temperature measuring device, further comprising a temperature calculation unit that measures a temperature change based on the obtained measured values of acoustic properties of a subject before and after heating.