JPH06109709A - Apparatus and method for judging dynamic property of solid material and apparatus and method for judging scanning and dynamic property of solid material - Google Patents

Abstract

PURPOSE: To measure the dynamic property of a bone by transmitting ultrasonic waves through a soft tissue around the bone by transmitting the waves through an interposed object and, at the same time, through a solid object in nearly parallel with the surface of the bone. CONSTITUTION: The dynamic property of a solid object (a bone in a living body) 16 having a surface is judged through an interposed medium 20. An ultrasonic transmitter 10 positioned to a first position transmits ultrasonic waves through the medium 20 and, at the same time, through a solid object 16 in nearly parallel with the surface. Ultrasonic receivers 12a and 12b are positioned to second and third positions which are provided on the same line as the first position to which the transmitter 10 is positioned at distances S1 and S2 so that the traveling time of the waves from the surface to the receiver 12a can become nearly equal to that from the surface to the receiver 12b. When the receiving time of the receiver 12a becomes nearly equal to that of the receiver 12b, the dynamic property of the solid object 16 is calculated from the ultrasonic waves transmitted from the transmitter 10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention generally relates to instrumentation for nondestructive measurement of mechanical properties of materials.
In relation to the mechanical properties of bone and bone quality (non-inva
sive) Instrumentation for measurement.

[0002]

It is well known in the art that the velocity of sound waves in a substance depends on the mechanical properties of the substance. This summary is available from C.I. H. Hastings and S.H. W. C
by arter, "Inspection of metal by ultrasonic method,
Inspection, Processing and M
anufacturing Control of Metal by Ultrasonic Method
s) ”(American Society for Testing and Materials (American Soc
"Symposium on Ultrasonic" at the 52nd anniversary conference
Testing) ", June 28, 1949, pp. 16-47).

US Pat. Nos. 3,720,098 and 3,
228,232, 3,288,241, 3,3
72,163, 3,127,950, 3,51
No. 2,400, No. 4,640,132, No. 4,59
No. 7,292, and No. 4,752,917 describe the state of the art of non-destructive testing.

Generally, a sound wave that reaches a semi-infinite solid or solid at an angle passes through this solid as three waves having different velocities for each wave, namely, a longitudinal wave, a transverse wave, and a surface wave. Propagate. The speed of these three waves is Ha
As described by stings and Carter, it is defined as:

[0005]

[Equation 1]

Here, V _L , V _T , and V _S are respectively
Velocity of longitudinal wave, velocity of transverse wave, and velocity of Rayleigh surface wave, E, σ, and ρ are Young's modulus, Poisson's ratio of lateral contraction and longitudinal extension, and mass of substance, respectively. Is the density. Formula (3b) is published by Karl F.L., published by Clarendon Press, Oxford, England in 1975. Graff, "WaveMotion in Elastic Solids"
Empirical relationship, as specified on page 326 of.

Normally, only ultrasonic wave velocities are used in ultrasonic measurements of bone conditions. R. P. Heaney et al., “Osteoporotic Bone Fragility: Detection by Bone Vulnerability of Osteoporosis.
Ultrasound Transmission Velocity) ", JAMA, V
ol. 261, No. 261. 20, May 26, 1989, 2
The Young's modulus E of the bone, as defined in pages 986 to 2990, is empirically given by equation (4a). Further, the speed of the sound passing through the bone is a function of E as in Expression (4b). Here, the sound velocity is usually the longitudinal velocity.

[0008]

[Equation 2]

Here, K is a constant that includes many factors such as the spatial orientation of the bone structure, the inherent properties of the bone substance, and fatigue damage. Therefore, the longitudinal wave velocity is a function of mass density and can be used as an indicator of bone quality.

Further, the following paper discusses ultrasonic measurement of bone condition both in vivo and in vitro.

[Measurement of the Velocity of Ultrasoun in Human Cortical Bone in vivo]
d in Human Cortical Bone In vivo) ", M.A. A. G
reenfield et al., Radiology (Radiology), Vol. 138, March 1981, 701-71.
0 pages.

[Combined 2.25 MHz ultrasound velocity and bone m method for simultaneous measurement of 2.25 MHz ultrasonic velocity and bone mineral concentration in horse's palmar bone]
ineral density measurements in the equine metacarp
us and their in vivo application), "R. N. M
cCartney and L.C. B. Jeffcott, Medical and Biologic Engineering and Computation (Medical and Biologic)
al Engineering and compuitation), Vol. 25,
1987, November 1877, 620-626.

[0013]

In order to make in vivo ultrasonic measurements of the mechanical properties of bone, it is necessary to transmit the ultrasonic waves through the soft tissue around the bone. Unfortunately, the thickness of soft tissue varies along the length of bone. This affects the accuracy of ultrasonic transit time measurements through bone. In the above-mentioned papers, attempts are made to ignore the thickness of soft tissue or eliminate the influence of soft tissue. In the paper describing in vitro experiments, soft tissue is removed from bone.

USSR Patent Nos. 1,420,383, 1,
No. 308,319, No.1,175,435, No.1,3
No. 24,479, No. 1,159,556, and No. 1,
172,534 and U.S. Pat. No. 4,926,8
70, 4,361,154, 4,774,95
No. 9, 4,421, 119, 4,941, 474
No. 3, No. 847, 141, No. 4, 913, 157
And No. 4,930,511 describe various systems for measuring bone strength based on velocity V _L. Generally, these systems have one ultrasound signal transmitter and at least one ultrasound signal receiver.

USSR Patent Nos. 1,420,383, 1,
No. 308,319, No. 1,175,435 estimates the value of the thickness of soft tissue in the measurement region, or there is little thickness variation over the distance between the two ultrasonic signal receivers. By assuming that, the problem of unknown thickness of soft tissue is solved.

In USSR Patent No. 1,342,279, 2
One receiver and a single transmitter are utilized and an average group velocity through the bone is calculated based on the known distance between the two receivers.

In Soviet Patent No. 1,159,556, the extent of the bone is defined and the condition of the bone is determined by the difference between the maximum and minimum amplitude of the measured ultrasonic signal. It will be clear that this measurement is performed on excised bone.

US Pat. No. 1,172,534 discloses a system in which the ultrasonic signal of healthy bone is compared with the ultrasonic signal of unhealthy bone and from this comparison the degree of disease in unhealthy bone is diagnosed. Is explained.

US Pat. Nos. 4,926,870 and 4,
421,119 and 3,847,141 describe systems for placing one receiver and one transmitter on either side of the bone. Also, in US Pat. No. 4,926,870, the resulting signal is compared to a standard waveform, which identifies bone health.

US Pat. Nos. 4,913,157, 4,
Nos. 774,959 and 4,941,474 describe systems for transmitting ultrasonic signals in the frequency spectrum.

US Pat. No. 4,930,511 describes a system that is placed around a standard, non-living, homogeneous material with known acoustic properties prior to being placed around the bone. .

[0022]

SUMMARY OF THE INVENTION The present invention is an ultrasonic measurement of mechanical properties of a hard material, the ultrasonic signal traveling from the transmitter through the thickness of the intervening medium, Proceed through the hard material to be tested, such as solids. Ultrasound waves propagate through a hard material as three waves, a longitudinal wave, a transverse wave, and a surface wave. The ultrasonic wave travels from the solid material to the first receiver through the second thickness, and travels to the second receiver disposed at a predetermined distance from the first receiver through the third thickness. .

Therefore, according to an embodiment of the present invention, there is provided an apparatus for determining the mechanical properties of a solid object having a surface via an intervening medium. This device:
An ultrasonic transmission device arranged at a first position for transmitting through the solid medium while transmitting through the intervening medium, and b) collinear along the first position and the surface; At least one ultrasonic receiver unit for receiving ultrasonic waves, arranged at each of the second position and the third position; and c) the first reception time of ultrasonic waves from the surface to the receiver unit at the second position. A device for positioning the receiver unit so as to be substantially equal to a second reception time from the surface to the receiver unit at a third position, and d) once the first reception time and the second reception time are And a device for calculating mechanical properties from the ultrasonic waves transmitted by the ultrasonic transmission device.

Furthermore, according to an embodiment of the present invention, the positioning device adjusts the position of the at least one receiver unit such that the first reception time and the second reception time are substantially equal. Further, the positioning device includes a device that determines the first reception time and the second reception time.

Further, according to an embodiment of the present invention, the determination device includes a device for pulsating the transmission device, so that it is possible to prevent the first reception time and the second reception time from being substantially the same. Sound waves are transmitted.

Furthermore, according to an embodiment of the present invention, the solid material is bone in a living body. Alternatively, the solid material is selected from metal, plastic, and wood.

Further, according to an embodiment of the present invention, the velocity of the ultrasonic wave passing through the intervening medium is lower than the velocity of the ultrasonic wave passing through the solid object.

Further, according to an embodiment of the present invention, the at least one ultrasonic receiver unit is mounted on the surface of the intervening medium without any coupling medium.

Furthermore, according to an embodiment of the present invention, there is provided a device for determining the mechanical properties of a solid body via an intervening medium. This device comprises: a) an ultrasonic transmission device that transmits ultrasonic waves through the intervening medium and the solid object having a surface; and b) at least first and second ultrasonic receivers that receive the ultrasonic waves. A unit, and c) the first reception time of ultrasonic waves from the surface to the first ultrasonic receiver unit is substantially equal to the second reception time of the surface to the second ultrasonic receiver unit. A device for positioning the ultrasonic receiver unit, which includes a rocking unit that presses the ultrasonic receiver unit into the intervening medium while rocking the ultrasonic receiver unit. The positioning device adjusts the positions of the first and second receiver units so that the first reception time and the second reception time are substantially equal to each other. Usually, the rocking unit includes a sound wave blocking unit.

Furthermore, according to an embodiment of the present invention, the ultrasonic transmission device includes a device for transmitting ultrasonic waves within a wide angle range, the ultrasonic waves including longitudinal waves, surface waves, and transverse waves. Is generated in the solid material.

Furthermore, according to an embodiment of the present invention, the device comprises a processing device for processing the signal from the receiver unit and for identifying the reception time of the longitudinal wave. The processing device includes a device for discriminating the reception time of the surface wave and the reception time of the shear wave.

Furthermore, according to an embodiment of the present invention, the processing device comprises a device for determining the mechanical property at least from the reception time of the longitudinal wave. Alternatively or additionally, the processing device includes a device for determining the mechanical property from the surface wave reception time and the shear wave reception time.

Further, according to an embodiment of the present invention, the transmission device transmits ultrasonic waves within a substantially small range of a predetermined angle.

Furthermore, according to an embodiment of the present invention, the transmission surface of the transmission device and the effective reception position of the reception device are on the same plane.

Furthermore, according to an embodiment of the present invention, the device requires little knowledge of the characteristics of the intervening medium.

According to an embodiment of the present invention, there is also provided a method for determining the mechanical properties of a solid object having a surface via an intervening medium. The method transmits ultrasonic waves from a first location through the intervening medium and through the solid body substantially parallel to a surface,
A second position and a third position which are collinear with the first position along the surface
Receiving ultrasonic waves with at least one ultrasonic receiver unit arranged at each of the positions, and a first reception time of the ultrasonic waves from the surface to the receiver unit at the second position, To be approximately equal to the second reception time to the receiver unit at the position,
Positioning the receiver unit, and once the first reception time and the second reception time are approximately equal, calculating mechanical properties from the ultrasonic waves transmitted by the ultrasonic transmission device. Including.

Further, according to an embodiment of the present invention, the positioning step includes a step of adjusting the position of the receiver unit so that the first reception time and the second reception time are substantially equal to each other.

Further, according to an embodiment of the present invention, the positioning step includes a step of determining the first reception time and the second reception time. In addition, the determining step includes a step of pulsating the transmission device, whereby an ultrasonic wave is transmitted when the first reception time and the second reception time are substantially the same.

Furthermore, according to an embodiment of the present invention, the solid material is bone in a living body. Alternatively, the solid material is selected from metal, plastic, and wood.

Further, according to the embodiment of the present invention, the velocity of the ultrasonic wave passing through the intervening medium is lower than the velocity of the ultrasonic wave passing through the solid object.

Further, according to an embodiment of the present invention, the ultrasonic receiver unit is mounted on the surface of the intervening medium without any coupling medium.

Further, according to an embodiment of the present invention, there is provided a method of determining the mechanical properties of a solid material through an intervening medium. The method comprises the steps of a) transmitting ultrasonic waves through the intervening medium and through the solid body having a surface, and b) at least first and second.
Receiving an ultrasonic wave with the ultrasonic receiver unit, and c) the first receiving time of the ultrasonic wave from the surface to the first receiver unit is substantially equal to the second receiving time of the surface to the second receiver unit. Positioning the receiver units so that they are equal. The positioning step includes a step of pressing the ultrasonic receiver unit into the intervening medium while rocking the ultrasonic receiver unit by using a rocking unit, whereby the first reception time and the second reception time are substantially equal to each other. The position of the receiver unit is adjusted so that

Further, according to an embodiment of the present invention, the method comprises the step of transmitting the ultrasonic waves in a wide area pattern,
This ultrasonic wave produces a longitudinal wave, a surface wave, and a transverse wave in the solid material.

Furthermore, according to an embodiment of the present invention, the method comprises the steps of processing the signal from the receiver device and identifying the time of reception of the longitudinal wave.

Further, according to an embodiment of the present invention, the processing step includes a step of identifying a reception time of the surface wave and a reception time of the transverse wave. It is preferable that the processing step includes a step of determining the mechanical property from at least the reception time of the longitudinal wave. Alternatively or additionally, the processing step includes the step of determining the mechanical property from the reception time of the surface wave and the reception time of the transverse wave.

Furthermore, according to an embodiment of the present invention, the solid body is composed of two or more substances, and the calculating device receives the time-based output signal from each of the at least one ultrasonic receiver unit. A device for converting at least two of the output signals into a frequency domain and thereby generating a frequency domain signal, a frequency value from the frequency domain signal and a corresponding velocity of propagation, And a device for judging each substance in the real thing.

Furthermore, according to an embodiment of the present invention, the device further includes a device for determining a degree of attenuation for each substance in the solid material from a difference between the frequency domain signals. Also alternatively or additionally, the apparatus receives a time-based output signal from each of the at least one ultrasound receiver unit, and
An apparatus for determining a first peak of each of the output signals and an apparatus for calculating a degree of attenuation of ultrasonic waves by the solid object from the first peak are included.

Further, according to an embodiment of the present invention, the calculating device includes a device for estimating the thickness of the solid object.

Further, according to an embodiment of the present invention, when the solid material is composed of two or more substances, the calculating step receives a time-based output signal from each of the at least one ultrasonic receiver unit. Transforming at least two output signals of the output signals into a frequency domain and thereby generating a frequency domain signal, the frequency value and the corresponding propagation velocity from the frequency domain signal Determining for each substance in the solid.

Further, according to an embodiment of the present invention, the method further comprises the step of determining the degree of attenuation for each substance in the solid from the difference between the frequency domain signals. Also, alternatively or additionally, the method receives a time-based output signal from each of the at least one ultrasound receiver unit,
The method includes the steps of determining a first peak of each of the output signals, and calculating a degree of attenuation of ultrasonic waves by the solid object from the first peak.

Further, according to an embodiment of the present invention, the calculating step includes a step of estimating the thickness of the solid object.

Further, according to an embodiment of the present invention, or alternatively, the apparatus of the present invention may include a housing and a sonic barrier, wherein the ultrasonic transmission device is mounted on the first side of the sonic barrier. And at least one ultrasonic receiver unit is mounted on the second side of the acoustic barrier.

Further, according to an embodiment of the present invention, the positioning device forms a housing in which the at least one ultrasonic receiver unit is installed, one end of which is attached to the housing and a sealing portion and an opening portion. And a soft film that does. The sealing portion is filled with a coupling material, and a vacuum hole is provided at the second end of the soft film. When the device is placed on the human skin and the air in the vacuum holes is decompressed and exhausted, the device is brought into close contact with the human skin.

Furthermore, according to an embodiment of the present invention, there is provided an apparatus for determining the mechanical properties of a solid object having a surface via an intervening medium. The apparatus comprises a soft array of piezoelectric cells formable into at least one ultrasonic transmitter and at least one ultrasonic receiver and a first plurality of piezoelectric cells in a first position, the at least one ultrasonic cell. A device for partitioning as a transmitter and partitioning at least a second plurality and a third plurality of piezoelectric cells respectively at a second position and a third position as the at least one ultrasonic receiver. The first position, the second position, and the third position are collinear along the surface, and the ultrasonic transmitter transmits ultrasonic waves through the intervening medium and in a direction substantially parallel to the surface. To be transmitted through the solid material. The device also includes a device for calculating mechanical properties from the ultrasonic waves transmitted by the ultrasonic transmitter. Also, the device is
A first reception time of ultrasonic waves from the surface to the at least one ultrasonic receiver unit at a second position is approximately equal to a second reception time of the ultrasonic waves from the surface to the at least one ultrasonic receiver unit at a third position. So that
It is desirable to include a device for partitioning the at least one receiver unit.

Finally, according to an embodiment of the present invention, a solid object having a surface is scanned through an intervening medium, and
A method is provided for determining the mechanical properties of the solid from this scan. The method comprises: a) partitioning a first plurality of transducer cells in a first position as at least one ultrasonic transmitter and at least a second plurality and a third plurality in a second position and a third position, respectively. Partitioning the transducer cell of the at least one ultrasonic receiver into a first position and a second position.
A position and a third position are collinear along the surface and the ultrasonic transmitter transmits ultrasonic waves through the intervening medium and through the solid body in a direction substantially parallel to the surface. Transmitting the dividing step, b) calculating the mechanical property from the ultrasonic waves transmitted by the ultrasonic transmitter, and c) the dividing step and the calculating step at different positions on the solid object. Repeating each step.

In the method, the first reception time of the ultrasonic wave from the surface to the at least one ultrasonic receiver unit at the second position is the same as the at least one ultrasonic receiver unit from the surface to the third position. It is desirable to include the step of partitioning the at least one receiver unit so as to be approximately equal to the second reception time of the ultrasonic waves up to, and the repeating step is performed at a randomly selected position.

Alternatively, according to an embodiment of the present invention, the iterative step is carried out at sequentially selected positions, and the calculating step comprises the mechanical property from knowledge of the velocity of the ultrasonic wave passing through the intervening medium. And determining.

[0058]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood and appreciated in the detailed description which follows with reference to the drawings.

Referring now to FIG. 1, a method for measuring the mechanical properties of a solid material such as solid 16 using ultrasonic waves, and an apparatus for carrying out an effective method constructed in accordance with the present invention. , Are schematically illustrated. This device is an ultrasonic transmitter 1 such as an ultrasonic transducer made of piezoelectric ceramic, which is capable of transmitting ultrasonic signals at frequencies typically in the range of 20 KHz to 10 MHz.
0 and a receiver unit 5 for receiving the transmitted signal
And, including. Unit 5 typically includes at least two ultrasonic receivers 12, such as ultrasonic transducers made of piezoceramic.

The unit 5 and the transmitter 10 are generally arranged in the direction of the major axis 14 of the solid body 16, but are preferably arranged parallel to the surface 18 of the solid body 16.
Usually, the solid 16 is a metal, and the mechanical properties of this metal such as Young's modulus (E), density (ρ), Poisson's ratio (σ) are measured. Further, the solid body 16 may be skeletal bone.

Usually, along the surface 18 of the solid material 16, an intervening medium 20 such as gel or water is used for the metal solid material 16, or an intervening medium 2 such as soft tissue usually surrounding skeletal bone.
There is 0. Usually transmitter 10 and receiver 12
Are placed on the upper surface 22 of the intervening medium 20 and each receiver 12 is located a distance S ₁ and S ₂ from the transmitter 10. According to the present invention, the thicknesses L ₁ and L ₂ of the intervening medium 20 under each receiver 12 are preferably substantially equal.

According to another embodiment of the present invention, the intermediary medium 2
0 is not used, transmitter 10 and receiver 12
Are placed directly on the surface 18 of the solid 16.

Generally, the transmitter 10 transmits an ultrasonic wave 29 that propagates through the intervening medium 20 as longitudinal waves until it reaches the surface 18. A portion of the wave 29, indicated by arrow 30, reaches surface 18 at an angle θ, which is a Brewster's angle with respect to surface 18. As known in the art, the wave 29
Three kinds of waves are generated in the solid material 16, namely, a longitudinal wave, a transverse wave, and a surface wave schematically marked by an arrow 32. If the hard material is not solid 16, only longitudinal waves will propagate, as is well known in the art.

These three kinds of waves propagate through the solid material 16 and generate longitudinal waves 35 received by the receiver 12 in the intervening medium 20.

The portions 34 and 36 of the wave 35 propagate through the intervening medium 20 at an angle θ with respect to the surface 18. Route 3
As is known in the art, 0, 32, and 34 are the shortest paths through which ultrasonic waves can reach the first receiver 12a of the receivers 12. Receiver 12
The shortest path to reach the second receiver 12b is the arrow 3
Marked with 0, 32, 33, and 36. Each route 3
A wave propagating along 0, 32, 34 or 30, 32, 33, and 36 is received first, followed by another wave propagating along the other path.

Brewster's angle θ is calculated as in equation (5).

[0067]

[Equation 3]

Here, V _L 'is the longitudinal wave velocity in the intervening medium 20, and V _L is the longitudinal wave velocity in the hard material 16. In the case of soft tissue, V _L 'is 1540 m / on average
s, and for bones, V _L averages 3500 m / s
And forms a Brewster's angle θ of about 65 °.

The first ultrasonic wave reaching the receiver 12a is
A longitudinal wave exiting solid 16 at Brewster's angle θ after passing a distance d ₁ through solid 16. The first ultrasonic wave that reaches the receiver 12b is a longitudinal wave that passes through the solid body 16 at a distance d ₁ + d ₂ .

It will be appreciated that the three waves do not arrive at the receiver 12 at the same time because of their different velocities. This is shown in FIGS. 2A and 2B, with brief reference to these figures. In FIG. 2A, a signal 40 representative of the ultrasonic waves transmitted by transmitter 10
And signals 42 and 4 which are received by the receiver 12a and respectively represent longitudinal waves, transverse waves, and surface waves.
4, 46 are shown.

The signal 40 is generated during a time τ, which is typically a very small time, so that the longitudinal, transverse and surface waves can be separated. For example, 5 cycles of 1 MHz signal is 5
Produces a microsecond τ.

Each of the signals 42, 44, 46 corresponds to the low energy part 41, which corresponds to the first wave reaching the receiver 12.
43, 45, which typically have much less energy than the subsequent signal. According to the invention, in contrast to the prior art, the propagation times t _L1 , t _T1 and t _S1 are the first wave reaching the receiver 12 from the start of the signal 40 (ie the start of transmission of the ultrasound 29). It is measured until the moment you do it. In the conventional technology, the signal 4 is started from the start of the signal 40.
Propagation time t _P measured until the moment 2 reaches the effective amplitude
Is a measure. Propagation time t _P measures the propagation time of the reflected signal rather than the signal propagated through solid 16.

As is well known in the art, transmitter 10
As the distance between the receiver and the receiver 12 increases, the time t
_L1 , t _T1 , t _S1 become longer and the signals 42, 44,
And 46 are further separated. Signals 42, 44, 4
The dimension of the distance d ₁ required to cause separation between 6 depends on the mechanical properties of the solid body 16, but for bone it is usually at least 5 cm.

Since the minimum value of S ₁ is determined by the thicknesses L ₁ and L ₂ , S ₁ becomes d ₁ as L ₁ and L ₂ increase.
It will be appreciated that it needs to be increased to ensure that is above zero. In other words, there must be some propagation through the solid 16. Also, d
₂ must be large enough to give an accurate measurement, while this d ₂ is equal to the signals 52, 54,
And it will be appreciated that the output of 56 must be so small that it is absolutely impossible for it to drop excessively due to the absorption of signal energy by the solid 16. Usually d ₂ is a few centimeters.

FIG. 2B is similar to FIG. 2A and shows signals 52, 54, and 56 received by receiver 12b. Each of the signals 52, 54, 56 includes a low energy portion 51, 53, 55. Each of the low energy parts 51, 53, 55 includes a low energy part 41,
It will be appreciated that each is received slightly later than each of 43 and 45. The propagation time is
_Denoted by t _L2 , t _T2 , and t _S2 .

The propagation velocities of longitudinal wave, transverse wave and surface wave are
It can be calculated by obtaining s ₃ = s ₂ −s ₁ from known distances such as the distances from the receivers 12a and 12b, and dividing by s ₃ = s ₂ −s ₁ . The propagation time through s ₃ is calculated as follows for a longitudinal wave.

The propagation time t _L1 is a combination of the propagation times t ₃₀ , t ₃₂ , t ₃₄ corresponding to each of the waves ₃₀ , ₃₂ , ₃₄ , and the propagation time t _L2 is the combination of the waves ₃₀ , ₃₂ , ₃₃ , 36. It is a combination of propagation times t ₃₀ , t ₃₂ , t ₃₃ , and t ₃₆ corresponding to each. This is mathematically described by formula (6a).
Equation (6b) is obtained.

[0078]

[Equation 4]

The thickness L ₁ of the intervening medium 20 below the receiver 12
And L ₂ are substantially equal to each other, the angles with respect to the two receivers 12 are θ, so that the propagation times reaching the receiver 12 via the intervening medium 20 are equal. That is, it is shown by the equation (7).

[0080]

[Equation 5]

When the difference between Expression (6b) and Expression (6a) is taken and Expression (7) is included, Expression (8) is obtained.

[0082]

[Equation 6]

From a simple geometry, when the thicknesses L ₁ and L ₂ are approximately equal, the propagation angles of the waves 34 and 36 are equal, so
It can be said that the distance d ₂ and the distance s ₃ are almost equal. Therefore, the equation (9) is obtained. Similarly, the equation (10)
And equation (11) is obtained.

[0084]

[Equation 7]

Therefore, equations (1) and (2) can be solved so that the ratio of Poisson's ratio σ and E / ρ is as follows.

[0086]

[Equation 8]

Next, referring to FIG. 3, there is shown an apparatus for measuring the mechanical properties of a solid body such as a bone in vivo, which is surrounded by an intervening medium such as soft tissue and whose thickness is unknown and is not constant. This device is constructed and functions according to the preferred embodiment of the present invention.

Normally, an ultrasonic wave 71 is used for the in-vivo measurement device.
In order to estimate the thickness of the ultrasonic transmitter 60, which normally transmits in the range of 20 KHz to 10 MHz, and the intervening medium 20 surrounding the solid material 16,
Transmit at least 2 from KHz to 10MHz
One ultrasonic transceiver 62, a plurality of ultrasonic receivers 64 for receiving the ultrasonic signals transmitted by the transmitter 60, and a processing unit 61 are included. A preferred embodiment of transmitter 60 and receiver 64 is shown in FIGS. 9A-9C.

Usually, the two transceivers 62 and the plurality of receivers 64 are integrated in one unit arranged such that the distance between the transmitter 60 and the first receiver 64 is s ₁ . Usually these receivers 64
Is interposed between the two transceivers 62. Therefore, if the thickness of the intervening medium 20 surrounding the solid 16 is substantially equal under the transceiver 62, the thickness is equal under the plurality of receivers 64.

According to the preferred embodiment of the present invention, the two transceivers 62 serve to transmit ultrasonic waves in a direction substantially orthogonal to the surface 22 of the intervening medium 20 and to reflect the transmitted waves from the surface 18. To receive the. Transceiver 62 and receiver 64 are pressed into intervening medium 20 to change their respective positions with respect to solid 16 until each received signal propagates through intervening medium 20 for the same length of time.

Furthermore, the transceiver 62 serves to estimate the thickness L ₁ . The estimated value of L ₁ is useful in estimating the distance s ₁ and in determining the position of transmitter 60. s ₁ is given by the equation (1
It is estimated as in 6).

[0092]

[Equation 9]

Since the distance d ₁ needs to be larger than zero as described above, s ₁ is calculated to be larger than 2L ₁ / tan θ by 30% to 40%. Alternatively, s ₁ may be a fixed distance from receiver 64.

In order to change the position of the transceiver 62 and the receiver 64, the elements 62 and 64 are connected to a single rockable unit 68, as shown in FIG. Now briefly refer to FIG. Each element 6
2 and 64 are connected to a unit 70 which includes a rocking unit 72 such as a handle for rockingly pressing each element 62 and 64 into the intermediary medium 20. It is installed. “Pivotally pressing” means that the rocking unit 72 is gently rocked right and left while being pressed into the intervening medium 20. A cable 69 that connects the swingable unit 68 to the processing unit 61 is attached to the swingable unit 68.

It will be appreciated that the swingable unit 68 may be any suitable unit, whether manual or automatic.

It will also be appreciated that the swingable unit 68 can slide along the surface 22 while a measurement is being taken, as will be described below. Therefore,
It is possible to take a measurement value along the solid material 16 while pointing out the change or discontinuous position of the material of the solid material 16 to the operator.

While the swingable unit 68 is swinging, the transceiver 62 continuously transmits and receives ultrasonic waves. The received signals are sent to a processing unit 61, by which the reception times of the two received signals are measured continuously. Here, the reception time is the thickness L ₁ and L ₂
Is the time to measure. If the difference between the reception times of the two received signals is almost zero, it indicates that the thickness of the intervening medium 20 between the two transceivers 60 and the solid 16 is substantially equal. The processing unit 61 causes the transmitter 60 to transmit an ultrasonic wave 71.

The ultrasonic waves generate arrows 73, 75, 77, and
As shown by 79, the intermediary medium 20 and the solid 1
After passing through 6 and 6, the receiver 64 receives this ultrasonic wave. The processing unit 61 receives the received signal, calculates at least t _L1 and t _L2, and calculates these t _L1 and t _{L2.
From L2} , V _L, which is correlated with the mechanical properties of the bone, is calculated as defined in equation (4b). Further, the processing unit 61 has the following formulas (12) to (1).
The ratio E / ρ and σ can be calculated from 5).

Since the transmission and reception of ultrasonic signals are normally performed within the range of 200 microseconds, the swingable unit 6
Any changes due to the rocking of 8
It will be appreciated that it has little effect on the thickness of the underlying media 20.

Referring again to FIG. processing·
The unit 61 includes driving devices 80 and 82 that drive the ultrasonic transceiver 62 and the transmitter 60, respectively, and signal processor units 84 and 86 that process received signals from the transceiver 62 and the receiver 64, respectively. Including.

In addition, the processing unit 61 controls the device by sending drive signals to the drive devices 80 and 82 and receives and processes signals from the signal processor units 84 and 86.
A main processing unit (MPU) 92 such as a microcontroller is included. Furthermore, MPU92
Interface with the operator of the apparatus of the present invention via keyboard 94 and display 95.

If s ₁ is indefinite, at the start of the measurement, s ₁ is estimated as Swingable unit 6
8 is swingably pressed into the intervening medium 20, and at the same time, MP
The U 92 pulsates the transceiver 62 and receives the signal from the transceiver 62 via the signal processor unit 84 using a relatively high threshold level T ₂ . If the time difference Δt between the reception times of each received signal is approximately zero, the MPU 92 determines the time between the transmission and reception of each of the signals transmitted by and reflected by each transceiver 62. Calculate t _tr . MP
U92, by multiplying the known average speed of sound in soft tissue t _tr, calculates the L _1, then the L ₁ is the distance s ₁ is used in Equation (16) is determined.

The swingable unit 68 is again swingably pressed into the intervening medium 20 to take a measurement value, and at the same time, the MPU 92 raises one transceiver 62a and the other transceiver 62b. Pulsate alternately with frequency. MPU9
2 receives the processed signal from the signal processor unit 84 and calculates the time difference Δt between the reception times of each received signal from the transceiver 62. When Δt is substantially zero, the MPU 92 causes the drive device 82 to pulsate to generate the ultrasonic wave 71 and stops pulsating the drive device 80.

This ultrasonic wave generates ultrasonic waves 75 and 79, which are received by the receiver 64. This received signal is processed by the signal processor 86 and the output is sent to the MPU 92 to determine at least the time difference t _L2- t _L1 and at least the speed V
_L' is calculated according to the equation (9).

It will also be appreciated that the apparatus of the present invention serves to calculate V _S and V _T using the method outlined above with reference to FIGS. 1 and 2. . The ratio E / ρ and σ can be calculated from the calculated values of V _L ′, V _S , and V _T. However, to compare the performance of the device of the present invention with the performance of other devices of the prior art,
It will be appreciated that a calculated value for V _L is needed.

Referring now to FIGS. 7 and 8A-8D, each figure illustrates each element of the signal processor unit 84 or 86 and the operation of that element.

In order to measure the instant when the first wave arrives at the receiver 64, the signal processor unit 84 or 86 includes a sensitive and low noise / signal for exponentially amplifying the signals 42 and 52. Ratio automatic gain control amplifier 2
10 is included to measure the onset of low energy portions 41 and 51 and to compensate for the characteristic exponential decay of the ultrasonic signal. FIG. 8B shows the output of the amplifier 210 corresponding to the input signal 42 of FIG. 8A including the low energy portion 41.

In addition, the signal processor unit 84 or 86 includes a bandpass filter 212 which completely filters all signals outside the range of frequencies transmitted by the transmitter 60, which filtering results in amplification or something else. The noise of the received signal is reduced. In FIG. 8C, the output of this bandpass filter 212 is
It is shown corresponding to the input signal of FIG. 8B.

In addition, each of the signal processor units 84 and 86 includes a threshold detector 214 that identifies the start of each of the signals 42 and 52, or each of the low energy portions 41 and 51. Thus, the threshold levels T ₁ and T ₂ shown in FIG. 8C are set. T ₁ identifies the low energy parts 41 and 51, and T ₂ the signals 42 and 52.
Identify. In FIG. 8D, the output of threshold detector 214 is shown corresponding to the input signal of FIG. 8C.

Referring now to FIG. 5, there is shown another embodiment of the apparatus of FIG. In this example, instead of two transceivers 62, a single transmitter 100, which is described in more detail below with reference to FIGS. 9A-9C, is used, and there is an even number of receivers 64. Are placed exactly equidistant to each other. Transmitter 1
00 and at least two receivers 64 are connected via a sound wave blocking unit 101. Unit 101
Are shown in detail in FIGS. 6A-6C.

The transmitter 100 has a non-zero angle gamma (γ) with respect to the orthogonal axis (not shown) of the surface 22.
At least two ultrasonic waves are transmitted in a general direction having (FIGS. 9A to 9C). Portions 102 and 104 of these two waves having an angle β as shown in FIG.
Are reflected from solid 16 to receiver 64 as waves 106 and 108. The angle β is unknown and depends on the thicknesses L ₁ and L ₂ .

The receiver 64 receives the reflected wave 10 from the surface 18.
6 and 108 are received and the received signal is sent to a signal processor 110 similar to the signal processors 84 and 86 of the embodiment of FIG. 3 and processed at two threshold levels T ₁ and T _2. It is like this. The processed signal is then an MPU similar to the MPU 92 of the embodiment of FIG.
Sent to 112.

If s ₁ is indeterminate, then at the start of the measurement s ₁ is estimated as follows: Unit 101 is
It is swingably pressed into the intervening medium 20, and at the same time, the MPU 1
12 pulsates the transmitter 100,
The signal from receiver 64 is received via signal processor unit 110 using a relatively high threshold T ₂ . The time difference Δt between the reception times of the respective reception signals is
If near zero, MPU 112
00 between the transmission and reception of each signal transmitted by 00 and received by receiver 64
Calculate _tr (similar to time t _{P in} FIG. 2A).

Once t _tr is calculated, the thickness L ₁ is roughly calculated by the equation (17).

[0115]

[Equation 10]

Here, s ₄ is the distance between the transmitter 100 and the receiver 64. Since the distance d ₁ needs to be larger than zero as described above, s
_According to the equation (16), ₁ is calculated to be larger than 2L ₁ / tan θ by usually 30% to 40%.

The unit 101 is oscillated again into the intervening medium 20 during measurement, and at the same time, the MPU 112 is pressed.
Pulsates the transmitter 100 and uses a relatively high threshold level T ₂ to receive the signal from the receiver 64 via the signal processor unit 110. When Δt is almost zero, the MPU 112
The drive device 82 is pulsated to generate the ultrasonic wave 71, and the pulsation of the drive device 83 is stopped.

This ultrasonic wave generates ultrasonic waves 75 and 79, which are received by the receiver 64. This received signal is processed by the signal processor 110 using a threshold level T ₁ and the output is
At least the time difference t _L2 −t is transmitted to the MPU 112.
_{In addition to obtaining L1} , at least the velocity V _L 'is calculated according to the equation (9).

Referring now to FIGS. 6A-6C,
A side view, a plan view, and an end view of the sound wave blocking unit 101 are shown. Transducers 64 and 10 of FIG.
0 is two rigid frames 120 and 12 usually made of metal
2, a sound wave absorbing material 124 such as elastic rubber is provided between the frames. The receiver 64 is the frame 12
The transmitter 100 is mounted on the frame 122 while being mounted on the frame 122. This frame 120
Has a hole 126 into which the transmitter 100 is inserted, and the frame 122 has holes 128 and 130 into which the receiver 64 is inserted.

The sound wave absorbing material 124 is used for the transmitter 10
0 serves to absorb the ultrasonic waves transmitted by the receiver 0, and the receiver 64 does not receive the ultrasonic waves transmitted from the transmitter 100 before receiving the ultrasonic waves propagated through the solid body 16. The frames 120 and 122 serve to shape the sound wave absorbing material 124 into a stable shape. Each frame holds only one type of ultrasonic transducer, for example frame 120 holds only receiver 64.

The unit 101 is required to ensure that the ultrasonic waves transmitted by the transmitter 100 are received by the receiver 64 only after propagating through the solid 16. In the absence of the acoustic block provided by unit 101, it may happen that the first signal received by receiver 64 is from a wave propagated through frames 120 and 122.

Referring now to FIGS. 9A-9C,
A preferred embodiment of an ultrasound transceiver 216 that functions as transmitters 60 and 100 and receiver 64 is shown. The transceiver 216 transmits the ultrasonic wave 71 to the angle γ.
In addition to the function of transmitting energy in the low energy portions 41 and 51, the amount of energy available to the low energy portions 41 and 51 is increased.

The ultrasonic transceiver 216 is constructed so as to generate ultrasonic waves in two directions indicated by the angle γ and to generate almost no waves in a direction orthogonal to the surface 22 on which the transceiver 216 is mounted. Has been done.
Usually, γ = 90−θ.

In FIG. 9A, transceiver 216 includes two standard ultrasonic transducers 220 having positive and negative terminals, respectively indicated by + and-signs. The positive terminals are connected to each other. The transducer 220 includes a housing 222 that includes two bends 224.
And the transducer 220 is mounted on the curved portion. Generally, the curved portion 224 is
It is composed of a sound wave transmitting material such as gel. In this embodiment, the negative terminal is grounded and the positive terminal is connected to the drive.

In FIG. 9B, a second embodiment of transceiver 216 is shown. Transceiver 216 includes two standard transducers 220 defined in housing 226, as in the previous embodiment. In this example, the positive terminal of one transducer 220 is connected to the negative terminal of the other transducer 220, and conversely, the negative terminal of one transducer 220 is connected to the positive terminal of the other transducer 220. As is well known in the art, this produces waves with opposite phases, and therefore only waves of angle γ overall. 1
The set of positive and negative terminals are mounted on one electrode 228, which is typically located along surface 22. Another set of positive and negative terminals connected to the driving device is installed in the housing 226. This housing 226 is grounded.

In FIG. 9C is shown a third embodiment of a transceiver 216 contained within a housing 229 and consisting of a single ultrasonic transducer 230, which transducer 230 is at least partially in two sections. It is divided into 232 and 233.
Typically, each negative terminal of sections 232 and 233 is attached to one electrode 236 and
The positive terminals of 2 and 233 are connected to the reverse polarity driving devices 241 and 24, respectively.
2 is connected to section 2, so that section 233 receives a negative signal and section 232 receives a positive signal, and conversely, section 233 receives a positive signal and section 232 receives a negative signal. ing.

It will be appreciated that what has been described is merely exemplary of the method and apparatus of the present invention. The present invention includes other ways of achieving the same goal. For example, another method of defining s ₁ is as follows.

In FIG. 2A, signal 42 is typically solid 1
The low energy part 41 is generated by the ultrasonic waves reflected from the surface 18 of 6, and the low energy part 41 is generated by the wave propagating through the solid body 16 by the distance d ₁ . Therefore, the reception time t _L1 of the low energy portion 41, the reception time t _P of the signal 42,
If there is a difference between, then d ₁ is greater than zero, as required. The measurement of t _L1 and t _P simply requires that signal processors 86 and 110 have two threshold levels T
It only has ₁ and T ₂ .

It will be appreciated that the device of the present invention, although less accurate in results, is effective when the thickness of the intervening medium 20 is not equal. Referring again to FIG. 1, if the reception times t _L1 and t _L2 differ by the measured value Δt, equations (6) to (8) are given by
8) can be rewritten as equation (20).

[0130]

[Equation 11]

Further, Δt can be positive or negative. Therefore,

[0132]

[Equation 12]

Due to geometric considerations, d ₂ is not necessarily equal to s ₃ if L ₁ is not equal to L ₂ .
However,

[0134]

[Equation 13]

Furthermore, it will be appreciated that the apparatus of the present invention will function without the intervening medium 20. In such a case, the unit 5 (FIG. 1) includes only one receiver 12a, and equations (9) to (11)
Is as follows:

[0136]

[Equation 14]

Hereinafter, still another method and apparatus for carrying out the present invention will be described.

Reference is now made to FIG. 10, which shows in flow chart form another method of signal processing performed by either MPU 92 or 112, and FIGS. 11 to 13 useful for understanding this method. . The method is described on the basis of FIG. 3, but it will be appreciated that the elements of FIG. 5 can also carry out the method.

The two signal processors 86 each receive a signal from the receiver 64. The first received signal 300, shown in FIG. 11A, is received at time τ ₁ after the transmitter 60 provides its input signal, while the second received signal 302, shown in FIG. 11B, is at time τ ₂ . To reach.

In this method, the signal processor 86 further informs the MPU 92 of the signals 300 and 302.
Portions 304 and 306 are provided respectively. Part 30
The length of each of 4 and 306 is typically τ ₀ seconds. Normal,
The portions 304 and 306 correspond to the initial wave reaching each receiver 64.

The MPU 92 or 112 is the portion 304
And 306 (F1 and F2, respectively, shown in FIG. 10) are stored and the MPU 92 or 112 does a Fast Fourier Transform (FFT) on each of F1 and F2 if nothing else is done to drive the system. Perform the signals SF1 and SF
2 is generated. Therefore, τ ₀ depends on the sampling rate and the number of samples required for use in the FFT.

The signals SF1 and SF2 are shown in FIG. Each of the signals has a plurality of peaks 310 and 312.
It can be seen that the signal SF2 is attenuated relative to the signal SF1. The peak indicates the natural filtering frequency of each of the materials that make up the solid, and this frequency corresponds to the velocity of propagation of the ultrasonic waves transmitted by the transmitter 60 through the solid.

As shown in FIG. 13, in the case of the solid 16 composed of two or more substances 314 and 316, the signal SF1
And SF2 each contain more than one peak. The maximum frequency peak 312 corresponds to the “fastest” substance (that is, the substance through which the transmitted wave passes at the maximum velocity), and the velocity corresponding to this is the velocity V calculated by the MPU 92 based on the above equation (9). It is _L.

Due to the relationship between frequency and speed, FIG.
The horizontal axis of can be scaled to represent velocity. The speed scale is represented by reference numeral 313,
The frequency scale is represented by reference numeral 315. The values obtained are valid for a solid 16 consisting of the following materials: epoxy and perspex.

Since the portion where the signal 302 passes through the solid 16 is longer than that in the case of the signal 300, attenuation occurs between the signal SF1 and the signal SF2. Therefore, this damping corresponds to the damping that occurs during the d ₂ portion of solid 16.

The method shown in FIG. 10 identifies the velocity of each peak and the attenuation due to the passage of the d ₂ portion.

This method discriminates the peaks 310 and 312 in SF1 and SF2, respectively, and determines the value of the velocity V _L 'obtained from equation (9) to the final peak 312.
To match. Furthermore, since the scale of the horizontal axis can be changed, other peaks 31 from the speed scale 313 can be changed.
The velocity corresponding to 0 can be calculated. Peak 31
2 corresponds to the fastest substance, eg substance 314.

Furthermore, this method uses the signals SF1 and SF2.
The logarithmic function of each of the amplitudes (low is 10) is calculated, and log (SF1) is subtracted from log (SF2) to generate the differential signal 320 shown in FIG. Typically, the differential signal 320 includes one or more peaks 32 that correspond to peaks 310 and 312 of signals SF1 and SF2.
2 and 324 are included.

The amplitudes of peaks 322 and 324 are the attenuation caused by the d ₂ portion of each of materials 316 and 314, respectively.

According to another embodiment of the present invention, the MPU 92
Approximates the thickness of solid 16 by utilizing the empirically obtained dimensionless curve of normalized velocity vs. normalized thickness, as shown in FIG. Now refer to this figure. For the creation of the curve in FIG. 15, see “Stress Waves in Solids” in the book “H. Kolsky
Written by Oxford and Clarendon Pr
ess, 1953.

The precise shape of this curve depends on the type of substance being measured. However, the inventors of the present invention determined that the curved shape is substantially constant with respect to the human bone.

The velocity V _L of the curve of FIG. 15 is normalized by the velocity V ₀ obtained in the infinite solid, and the thickness is normalized by the input wavelength λ of the signal from the transmitter 60. According to the inventors of the present invention, the curve shows that the thickness is the thickness D (FIG. 13) of the solid body 16,
Alternatively, it was determined to be approximately the same regardless of the outer cylindrical material thickness D-d (FIG. 13).

This curve shows a slight velocity ratio and a small diameter /
It can be seen that it has a wavelength ratio region 330 and a diameter / wavelength ratio region 332 that is asymptotic to 1.0 and greater than about 1.5.

To estimate the thickness (D-d) of the solid 16 the transmitter 60 is operated twice, the first time with the high frequency input signal and the second time with the low frequency input signal. Signal processor 84 and MPU 92 operate on each measurement to determine the received speed, as described above with reference to FIG.

Due to the response to the high frequency input signal having the low wavelength λ, the velocity data point 334 will have a velocity V
Somewhere along the region 332 where ₀ can be determined. However, the exact location of the data point 334 is unknown because the thickness is unknown.

The response to a low frequency input signal is
Velocity data points 336 are obtained somewhere within region 330. The velocity V _L is known from this measurement and
Since the velocity V ₀ is known from the previous measurement, the position of the data point 336 on the curve is known. Therefore, (D-
The ratio d) / λ can be determined. Since λ can be known from the frequency of the transmitter 60, the thickness D or (D−d) of the solid 16 can be obtained.

Also, the attenuation in the case of only relatively high-velocity material is the first of the signals 300 and 302 (FIGS. 11A and 11B).
By estimating the timing of the peaks, the signal 30
It can be determined directly from 0 and 302. Referring now to FIG. 16, a unit 350 for determining damping is shown in block diagram form. The features of the signal 300 are discussed below, but it can be seen that both the signal 300 and the signal 302 have the feature.

Unit 350 detects a first threshold U ₀ , defined as the voltage above the expected noise level, in a manner similar to the device shown in FIG. Therefore, usually
Unit 350 includes an amplifier, such as amplifier 210, a filter 212, and a U ₀ detector 352 similar to threshold detector 214.

The first peak 354 is known to continue after the voltage reaches the threshold level U ₀ , so U ₀
The detector 352 sends a signal to the timer 356 as soon as it detects a voltage above U ₀ , causing the analog switch 358 to be turned on for a predetermined length of time τ ₄ at which the first peak 354 is expected to appear.

The analog switch 358 receives the output of the amplifier 210, and while the switch 358 is on, the output of the amplifier 210 is provided to the analog peak detector 360, which then detects the peak 354. The amplitude u _{1 of} is detected.

The amplitude u ₁ is provided to an analog-to-digital converter (ADC) 362 for conversion into a digital value.

A unit 350 is provided for the output of each receiver 64 such that the value of u ₁ of the first receiver 64 (denoted A) is the value of u ₁ of the second receiver 64 (B
Indicated)). Two values A in decibels
The ratio between B and B is the attenuation of the solid 16 at the distance d ₂ (FIG. 1). In other words, the attenuation is as follows.

[0163]

[Equation 15]

Referring now to FIG. 17, the apparatus of FIG. 3 integrated into a single unit 400 is illustrated. Elements that are similar to elements of the previous embodiment have been given similar reference numerals.

The unit 400 includes a transmitter 6
0, a transceiver 62, and a holding frame 402 shaped to support the receiver 64 at a desired angle. This angle is usually the average of Brewster's angles commensurate with the substance to be measured. In the case of a human bone, the Brewster's angle varies from 22 ° to 30 °, so that the angle of the receiver 64 is, for example, about 26 °.

The ultrasonic elements 60 to 64 are connected to the surface 22 of the intervening medium 20 via a coupling material 406 such as water, oil or sonic gel, and the coupling material 406 is made of rubber or the like. Flexible cover 40
It is held at a predetermined position via 8. Generally, the flexible cover 408 is in close contact with the holding frame 402.

The unit 400 also includes acoustic waves interposed between the transmitter 60 and the elements 62 and 64 to ensure that little cross-coupling occurs between the transmitter 60 and the transceiver 62. A barrier 404 is included. The acoustic barrier 404 can be constructed of any suitable material, such as rubber, and also extends through the coupling material 406 to the flexible cover 408, as shown in FIG. In general, the ultrasound of transmitter 60 is due to acoustic barrier 404,
There is no choice but to reach the receiver 64 after passing through the intervening medium 20.

The holding frame 402 is used for the transmitter 6
The 0 is arranged to be located at a distance s ₁ shown in FIG. 1 from its nearest receiver 64. As described above, s ₁ needs to be large enough so that d ₁ can never be negative, and small enough that the received signal is always large enough for measurement.

It will be appreciated that the unit 400 is operable with a range of thickness media 20. The maximum value of this range is from the receiver 64 to the surface 18 of the solid 16.
To H. _{Here, H = (s 1/2} ) ctg
θ.

Normally, the unit 400 is first placed on the surface 22 of the intervening medium 20, on which another coupling material (not shown) is also placed. The unit is then actuated by rocking, as in the previous embodiment. By this swing, the coupling material 40
6 and one or both of the intervening media 20 are pressed. The coupling material ensures that the entire ultrasonic element 60-64 remains acoustically coupled to the intervening medium 20 during rocking.

18A and 18B, there are shown a side view and a front view, respectively, of another embodiment of the swingable unit 68 of FIG.

In this alternative embodiment, the receiver 64 and the transceiver 62 are coupled to the intervening medium 20 via a "half-bath" 420, which "half-bus" 420 is sealed. It is composed of a rubber frame 422 which is composed of two sections 424 and an opening 426.

The sealing portion 424 includes a coupling material such as sonic gel, which is permanently defined therein.

The portion of the rubber frame 422 forming the opening 426 reaches the circular vacuum hole 428. This hole 4
When the air in 28 is removed, the half bath 420 is inserted into the intermediary medium 2
A suction force that adheres to the surface 22 of 0 is generated, thereby forming a closed tank into which a coupling material such as water can be injected.

This suction force is generated through the first pump 430 having the intake / exhaust tube 432, and the second pump 43
4 injects water through the pipe 436 into the opening 426. The pipe 436 is attached to a circular hole 438 arranged on the vacuum hole 428 in the rubber frame 422.

The second pump 434 supplies the water stored in the container 440, and the temperature of this water can be adjusted by the temperature regulator composed of the heater 442 and the thermostat 444. Generally, temperature regulation is incorporated when the present embodiment is placed on the skin of a person and operated such that the water is always at a comfortable temperature for the person.

The device shown in FIGS. 18A and 18B is swung to find the equilibrium point, as in the previous embodiment.

Referring now to FIGS. 19 and 20, another embodiment aspect useful for scanning across a section 448 of a human body, such as an arm, is illustrated.

In this embodiment, Atochem Sen
sors Inc. of Valley Forg
E., Kyn manufactured by Pennsylvania, USA
A material composed of an array of piezoelectric cells 450, such as an arPiezo Film, is placed on or wrapped around section 448 or molded into a sock-like element. Usually this array 450
Are acoustically coupled to section 448 in a standard manner.

Normally, each input / output wire of each piezoelectric cell 450 is connected to an analog matrix multiplexer 451 as shown in FIG. 20, which in turn drives the driver 452 and the signal processing. -It is connected to the unit 454 and.
Typically, drive 452 and unit 454 are controlled via microprocessor 455.

The multiplexer 451, the cell 45
Each of the 0's can be individually accessed and the multiplexer 451 serves to define each cell as a receiver, transmitter, transceiver, or non-active.

Generally, the individual piezoelectric cells 450 are too small to form an ultrasonic transducer.
Therefore, the plurality of cell groups 450 at the required positions are
Electronically to become ultrasonic elements 60-64, and
Divided freely.

The device shown in this example can be operated in numerous ways. For example, a roller 460 or other suitable device can be rotated across the array and rocked against the human skin.

While the rollers 460 are being rotated, a plurality of single cells or groups of cells 450 are operated as the transceiver 62. Since the reception time outputs of the plurality of transceivers 62 are continuously compared with each other, when the two reception times coincide with each other, another cell group 450 temporarily receives the transmitter 60.
And the newly partitioned transmitter 60 transmits ultrasonic waves to the newly partitioned receiver 64. The newly partitioned transmitter 60 and receiver 64 are composed of a group of cells collinear with the cell 450 whose reception time is the same.

The operation described herein typically occurs within microseconds, and the operation is continuously repeated while the activated roller 460 rotates across the area under test. It will be appreciated that this check is not done serially. Measurements are made whenever two equilibrium points are known, which is a somewhat random method of "scanning" the area under examination.

Alternatively, section 448 includes roller 4
It can be tested without using 60. In this example, the cells 450 are partitioned serially across the section 448 as the transmitter 60 and the receiver 64, and the speed of passage through the section of the solid 16 so partitioned is described below. Is calculated based on FIG.

The heights h ₁ and h ₀ are measured by the cell 450 defined as the transceiver 62, the surface 18
At different heights above, L is the distance between these centers. Considering the fact that the average velocity V _L 'of the longitudinal ultrasonic waves passing through the soft tissue is 1540 m / s, the value of the velocity V _L of the longitudinal waves passing through the solid body 16 is described as follows. be able to.

[0188]

[Equation 16]

Since the equation (28) can be solved according to the Brewster angle θ on the premise of the relationship between the equations (29) and (30), the value of V _L can be obtained from the equation (5). You can As described above, the result of the above calculation is less accurate than the result obtained by ensuring that the reception times of the two transceivers 62 are equal.

Those skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention is defined only by the claims.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a method for measuring the mechanical properties of a substance using ultrasonic waves, which is effective according to the present invention.

2A and 2B are graphical illustrations of ultrasonic signals transmitted and received by an ultrasonic transducer using the method of FIG.

FIG. 3 is a partial block diagram and partial schematic diagram of an in-vivo ultrasound apparatus for measuring mechanical properties utilizing the method of FIG. 1.

4 is a pictorial view of an apparatus useful in the apparatus of FIG. 3 to ensure that the ultrasonic transducer is parallel to the surface of the substance to be measured.

5 is a partial block diagram and partial schematic view of another embodiment of the apparatus of FIG.

FIG. 6 is a schematic view of a sound blocking element useful in the device of FIG.

FIG. 7 is a block diagram of a signal processor useful in the embodiments of FIGS. 3 and 5;

8A-8D are graphs showing output signals from each element of the signal processor of FIG.

9A-9C are schematic diagrams of transmitters useful in the embodiments of FIGS. 3 and 5. FIG.

FIG. 10 is a flow chart diagram of a method of determining attenuation of an ultrasonic signal due to passage through a substance.

11A and 11B are a part of the device of FIG.
It is a graph figure which shows the output signal from two ultrasonic receivers.

FIG. 12 is a graph of Fourier transform of each output signal of FIGS. 11A and 11B.

FIG. 13 is a schematic view of a portion made of two substances.

FIG. 14 is a graph showing a difference between the Fourier transforms shown in FIG.

FIG. 15 is a graphical representation of the relationship between the thickness of a section and the velocity of ultrasonic waves passing through this section.

FIG. 16 is a block diagram of a unit for determining attenuation from the signals shown in FIGS. 11A and 11B.

FIG. 17 is a schematic side view of one transmitter and multiple receivers integrated in a single unit.

18A is a schematic side view of another embodiment of a portion of the apparatus of FIG. B is a schematic front view of another embodiment of a portion of the apparatus of FIG.

FIG. 19 utilizes an array of piezoelectric transducers,
FIG. 7 is a schematic view of another embodiment of the present invention.

20 is a schematic diagram of the array of FIG. 19, showing the connection of transducers to each control element.

FIG. 21 is a schematic diagram of the non-parallel positions of two receivers useful in understanding the calculations made based on FIGS. 19 and 20.

[Explanation of symbols]

 5 Ultrasonic Receiver Unit 10 Ultrasonic Transmitter 12 Ultrasonic Receiver 16 Solid Object 20 Intermediary Medium 60 Ultrasonic Transmitter 61 Processing Unit 62 Transceiver 64 Ultrasonic Receiver 68 Swingable Unit 72 Swinging Unit 100 Transmitter 101 Sound Wave Blocking Unit 124 Sound wave absorber 212 Band filter 214 Threshold detector 216 Ultrasonic transceiver

Claims (50)

[Claims] 1. An apparatus for determining the mechanical properties of a solid object having a surface through an intervening medium, wherein ultrasonic waves are transmitted through the intervening medium,
Transmitting through the solid substantially parallel to the surface,
An ultrasonic transmission means arranged at a first position, and at least one ultrasonic wave receiving means arranged at each of a second position and a third position which are collinear with the first position along the surface. An ultrasonic receiver unit, and a first reception time of ultrasonic waves from the surface to the at least one ultrasonic receiver unit at the second position is from the surface to the at least one ultrasonic receiver unit at the third position. Means for positioning the at least one receiver unit so as to be substantially equal to the second reception time of, and once the first reception time and the second reception time are substantially equal, the ultrasonic transmission means transmits And a means for calculating the mechanical properties from the generated ultrasonic waves. 2. The solid object according to claim 1, wherein the positioning unit adjusts the position of the at least one receiver unit such that the first reception time and the second reception time are substantially equal to each other. Mechanical property determination device. 3. The mechanical property determination device according to claim 2, wherein the positioning means includes means for determining the first reception time and the second reception time. 4. The determination means includes means for pulsating the transmission means, whereby ultrasonic waves are transmitted when the first reception time and the second reception time are substantially the same. 3. A device for determining mechanical properties of a solid according to item 3. 5. The mechanical property determination device according to claim 1, wherein the solid object is bone in a living body. 6. The mechanical property determination device according to claim 1, wherein the solid material is selected from metal, plastic, and wood. 7. The mechanical property determination device according to claim 1, wherein the velocity of the ultrasonic wave passing through the intervening medium is lower than the velocity of the ultrasonic wave passing through the solid substance. 8. The solid mechanical property characterization device of claim 1, wherein the at least one ultrasonic receiver unit is mounted entirely on the surface of the intervening medium without a coupling medium. . 9. An apparatus for determining the mechanical properties of a solid through an intervening medium, the ultrasonic transmitting means transmitting ultrasonic waves through the intervening medium and the solid having a surface. At least first and second ultrasonic receiver units for receiving the ultrasonic waves, and a first reception time of the ultrasonic waves from the surface to the first ultrasonic receiver unit, A oscillating unit that urges the ultrasonic receiver unit into the intervening medium while oscillating the ultrasonic receiver unit so as to be substantially equal to the second reception time up to the acoustic wave receiver unit,
Positioning means for positioning the first and second ultrasonic receiver units, wherein the positioning means adjusts the position of the receiver unit so that the first reception time and the second reception time are substantially equal to each other. An apparatus for determining the mechanical properties of solid objects including. 10. The mechanical property determination device according to claim 9, wherein the swing unit includes a sound wave blocking unit. 11. The ultrasonic wave transmission means comprises means for transmitting the ultrasonic wave within a wide angle range, and the ultrasonic wave transmits longitudinal waves, surface waves, and transverse waves into the solid object. The mechanical property determination device according to claim 1, which is generated. 12. The mechanical property determination device according to claim 11, further comprising processing means for processing a signal from the at least one ultrasonic receiver unit and for identifying a reception time of the longitudinal wave. . 13. The processing means comprises means for identifying a reception time of the surface wave and a reception time of the transverse wave.
The mechanical property determination device according to claim 12, 14. The processing means includes:
13. The mechanical property determination device according to claim 12, further comprising means for determining at least the reception time of the longitudinal wave. 15. The processing means includes:
14. The mechanical property determination device according to claim 13, further comprising means for determining from the reception time of the surface wave and the reception time of the transverse wave. 16. The mechanical property determining apparatus according to claim 1, wherein the transmitting means transmits the ultrasonic waves within a range of a slight predetermined angle. 17. The transmission surface of the transmission means and the effective reception position of the reception means are on the same plane.
An apparatus for determining mechanical properties of a solid object described in. 18. The mechanical property determining apparatus according to claim 1, wherein knowledge of characteristics of the intervening medium is hardly required. 19. The mechanical properties of a solid object having a surface,
A method of determining through an intervening medium, the method comprising: transmitting an ultrasonic wave from a first position through the intervening medium and through the solid object substantially parallel to the surface; and the first position. And receiving the ultrasonic waves with at least one ultrasonic receiver unit arranged at each of a second position and a third position which are collinear along the surface, and the at least the second position from the surface. The at least one receiver unit such that a first reception time of ultrasonic waves to one ultrasonic receiver unit is approximately equal to a second reception time of the surface to the at least one receiver unit at the third position. Locating, and once the first reception time and the second reception time become substantially equal, the ultrasonic transmission means And a step of calculating the mechanical properties from the transmitted ultrasonic waves, the method for determining the mechanical properties of a solid object. 20. In the positioning step, the first reception time and the second reception time are substantially equal to each other,
20. The method of determining the mechanical properties of a solid object of claim 19, including adjusting the position of the at least one receiver unit. 21. The method for determining mechanical properties of a solid object according to claim 20, wherein the positioning step includes a step of determining the first reception time and the second reception time. 22. The determining step includes the step of pulsating the transmitting means, whereby ultrasonic waves are transmitted when the first reception time and the second reception time are substantially the same. 19. The method for determining the mechanical properties of the solid object according to 19. 23. The method for determining mechanical properties of a solid body according to claim 19, wherein the solid body is bone in a living body. 24. The solid material is metal, plastic,
The method for determining the mechanical properties of a solid material according to claim 19, which is selected from the group consisting of wood and wood. 25. The method for determining mechanical properties of a solid object according to claim 19, wherein the velocity of the ultrasonic wave passing through the intervening medium is lower than the velocity of the ultrasonic wave passing through the solid object. 26. The determination of mechanical properties of a solid according to claim 19, wherein the at least one ultrasonic receiver unit is mounted on the surface of the intervening medium, entirely without a coupling medium. Method. 27. A method of determining mechanical properties of a solid through an intervening medium, the method comprising: transmitting ultrasonic waves through the intervening medium and the solid having a surface; Receiving sound waves at least in first and second ultrasonic receiver units; a first reception time of the ultrasonic waves from the surface to the first receiver unit is from the surface to the second receiver unit; Positioning the receiver unit so as to be approximately equal to the second reception time, the oscillating unit is used to press the ultrasonic receiver unit into the intervening medium while oscillating, and thereby, The step of adjusting the position of the receiver unit such that the first reception time and the second reception time are substantially equal. Method of determining mechanical properties of the real in including a-decided Me step. 28. The method for determining the mechanical properties of a solid object according to claim 19, including the step of transmitting the ultrasonic waves that generate longitudinal waves, surface waves, and transverse waves in the solid object in a wide-area pattern. . 29. The solid mechanical properties of claim 28, comprising: processing a signal from the at least one ultrasonic receiver unit; and identifying a reception time of the longitudinal wave. Judgment method. 30. The method for determining the mechanical properties of a solid object according to claim 29, wherein the processing step includes a step of identifying a reception time of the surface wave and a reception time of the transverse wave. 31. The method for determining the mechanical properties of a solid object according to claim 29, wherein the processing step includes a step of determining the mechanical properties from at least the reception time of the longitudinal wave. 32. The mechanical property of the solid object according to claim 30, wherein the processing step includes a step of determining the mechanical property from the reception time of the surface wave and the reception time of the transverse wave. Judgment method. 33. The mechanical property determination device according to claim 2, wherein the positioning means includes a swing unit that pushes the receiver unit into the intervening medium while swinging the receiver unit. 34. The mechanical property determination device according to claim 33, wherein the swing unit includes a sound wave blocking unit. 35. The solid object of claim 20, wherein the positioning step includes the step of rocking the at least one ultrasonic receiver unit into the intervening medium using a rocking unit. Method for determining mechanical properties. 36. The solid material is composed of two or more substances, and the calculating means includes means for receiving a time-based output signal from each of the at least one ultrasonic receiver unit; A means for converting at least two output signals into a frequency domain and generating a frequency domain signal thereby, a frequency value and a corresponding propagation velocity from the frequency domain signal are determined for each substance in the solid object. The means for determining the mechanical properties of the solid object according to claim 1, further comprising: 37. The mechanical property determining apparatus according to claim 36, further comprising means for determining a degree of attenuation of each substance in the solid object from a difference between the frequency domain signals. . 38. Means for receiving a time-based output signal from each of the at least one ultrasonic receiver unit and determining a first peak of each of the output signals; and from the first peak, the solid object. Means for calculating the degree of attenuation of the ultrasonic waves.
An apparatus for determining mechanical properties of a solid object described in. 39. The mechanical property determining apparatus according to claim 1, wherein the calculating means comprises means for roughly estimating the thickness of the solid material. 40. A housing and a sound wave barrier are further provided, wherein the ultrasonic wave transmission means is mounted on the first side surface of the sound wave barrier, and the at least one ultrasonic wave receiver unit is the sound wave barrier. The mechanical property determination device according to claim 1, which is mounted on the second side face of the solid object. 41. The positioning means includes a housing in which the at least one ultrasonic receiver unit is provided, one end of which is attached to the housing, a sealing portion filled with a coupling material, and an opening portion. And a soft membrane having a vacuum hole at a second end thereof, the device being placed on the skin of a person and the air in the vacuum hole being decompressed and exhausted by the apparatus. The mechanical property determination device according to claim 1, which is in close contact with the skin. 42. A device for scanning a solid object having a surface through an intervening medium and determining the mechanical properties of the solid object from the scan, the device comprising at least one ultrasonic transmitter and at least one ultrasonic wave transmitter. An ultrasonic receiver, a soft array of piezoelectric cells formable into the ultrasonic cell, and a first plurality of the piezoelectric cells in a first position are partitioned as the at least one ultrasonic transmitter, and in a second position and a third position. Means for partitioning at least a second plurality of piezoelectric cells and a third plurality of piezoelectric cells as the at least one ultrasonic receiver, wherein the first position, the second position, and the third position are on the surface. Collinear along the same, the ultrasonic transmitter transmits ultrasonic waves through the intervening medium and in a direction substantially parallel to the surface. A solid object scanning and mechanical property determination device comprising: the partitioning means for transmitting through the solid object; and means for calculating the mechanical property from the ultrasonic waves transmitted by the ultrasonic transmitter. 43. Further, the first reception time of ultrasonic waves from the surface to the at least one ultrasonic receiver unit at the second position is equal to the at least one ultrasonic receiver unit at the third position from the surface. Up to the second
43. The solid scanning and mechanical characterization device of claim 42, comprising means for partitioning the at least one receiver unit so as to be approximately equal to the reception time. 44. A method of scanning a solid object having a surface through an intervening medium and determining the mechanical properties of the solid object from the scan, the first plurality of transducers in a first position. Cell
Partitioning as at least one ultrasound transmitter and partitioning at least a second plurality and a third plurality of transducer cells at a second position and a third position, respectively, as at least one ultrasound receiver, The first position, the second position, and the third position are collinear along the surface, and the ultrasonic transmitter transmits ultrasonic waves through the intervening medium and is substantially in contact with the surface. The partition step of transmitting through the solid object in a parallel direction, the step of calculating the mechanical properties from the ultrasonic waves transmitted by the ultrasonic transmitter, the partition step and the calculating step, the solid object A method of scanning and mechanical characterization of a solid object, comprising: repeating each of the above different positions. 45. The first reception time of ultrasonic waves from the surface to the at least one ultrasonic receiver unit at the second position is from the surface to the at least one ultrasonic receiver unit at the three positions. Partitioning the at least one receiver unit so as to be approximately equal to the second reception time of, the repeating step being performed at a randomly selected position,
The method for scanning and determining the mechanical properties of the solid object according to claim 44. 46. The repeating step is performed at sequentially selected positions, and the calculating step includes a step of determining the mechanical property from knowledge of a velocity of the ultrasonic wave passing through the intervening medium. The method for scanning and determining the mechanical properties of the solid object according to claim 44. 47. The solid object comprises two or more substances, the calculating step receiving a time-based output signal from each of the at least one ultrasonic receiver unit; Transforming at least two output signals of the material into a frequency domain, thereby generating a frequency domain signal, the frequency value and the corresponding velocity of propagation from the frequency domain signal, the substance in the solid material. The method for determining mechanical properties of a solid object according to claim 19, further comprising: 48. The method for determining the mechanical properties of a solid object according to claim 47, further comprising the step of determining the degree of attenuation for each substance in the solid object from the difference between the frequency domain signals. 49. Receiving a time-based output signal from each of said at least one ultrasonic receiver unit, determining a first peak of each of said output signals, and from said first peak to said solid object. 20. The method of determining the mechanical properties of a solid object according to claim 19, further comprising: 50. The method for determining the mechanical properties of a solid object according to claim 19, wherein the calculating step includes a step of estimating the thickness of the solid object.