JPH05184569A - Ultrasonic wave transmission inspection device - Google Patents

Abstract

PURPOSE:To improve measurement sensitivity by controlling a matching degree changing means in such a manner as to maximize the intensity of the ultrasonic waves detected by an ultrasonic detector. CONSTITUTION:A matching degree control section 17 emits an instruction signal so as to change the temp. of the matching liquid within a measuring cell 20 to a matching liquid temp. control section 12 to gradually change the temp. of the matching liquid in a matching liquid injecting and discharging section 11 and to inject the matching liquid changed in temp. by as much as the same volume from an injection port 24 into the measuring cell 20. The control section 17 detects the temp. at which the reflectivity is minimized within the prescribed temp. range in accordance with the ultrasonic intensity detected by an ultrasonic measuring section 14 while the temp. of the matching liquid is changed. The control section 17, then, emits an instruction signal to the control section 12 in such a manner that the temp. of the matching liquid in the measuring cell 20 attains this temp. The matching liquid regulated to the optimum temp. is then injected from the discharge section 11 into the measuring cell 20. The speed, attenuation rate, etc., in the testee body in the measuring cell 20 are measured after the matching degree of the matching liquid is optimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transmission inspection device or a bone mineral quantification device used for diagnosing osteoporosis.

[0002]

2. Description of the Related Art Osteoporosis is a condition in which the density of bone tissue decreases due to lack of calcium, etc., but for the purpose of diagnosis, ultrasonic waves are passed through the bone to determine the speed (sound velocity) and attenuation of the ultrasonic waves in the bone. A method of quantitatively measuring the characteristics of bone (bone mineral density, stiffness, etc.) by measuring the above has been devised. Such ultrasonography is usually performed on the heel of a thin soft tissue foot.

A conventional device for measuring the characteristics of bone (called a bone mineral quantification device) is a container (measuring tank) in which an ultrasonic generator and an ultrasonic detector are mounted on the inner wall so as to face each other. use. For the ultrasonic generator and the ultrasonic detector, a device called an ultrasonic transducer that can generate and detect ultrasonic waves with one unit is usually used. In this measuring tank, put your feet so that the heel may block the ultrasonic wave generation / detection device, and also for matching when the ultrasonic wave is incident on the heel (that is, the ultrasonic waves reflected on the surface of the heel should be Add water as a matching liquid (so that the sound waves are as low as possible). When ultrasonic waves are emitted from the generator in that state,
When ultrasonic waves pass through the calcaneus, they propagate at a speed corresponding to the amount of bone mineral and are attenuated. Therefore, the amount corresponding to the amount of bone mineral in the calcaneus, which is the subject, can be measured by measuring the velocity or the amount of attenuation of the ultrasonic wave with the detector.

Since the degree of matching between water and the subject changes depending on the temperature of the water, a device for keeping the temperature of the water constant (for example, 37 ° C. which is the same as the body temperature) is provided in the conventional device. ing.

[0005]

As described above, in the ultrasonic bone mineral quantifying device, since the soft tissue is usually thin and the heel which occupies most of the bone tissue is the subject, the bone mineral quantifying device The matching between water and the subject is ultrasonic matching between the water and the calcaneus. The best match of the ultrasonic waves at the boundary between the two media (that is, the minimum reflection of the ultrasonic waves at the boundary surface) is when the ultrasonic impedances of both media are equal. Here, since the ultrasonic impedance of the bone tissue varies depending on the bone density, it varies depending on the subject (person). Therefore, if the temperature of water as the matching liquid is kept constant as in the conventional apparatus, there are cases where the matching cannot be sufficiently achieved depending on the subject. As a result, there arises a problem that the amount of ultrasonic waves passing through the subject decreases and the measurement sensitivity decreases. Also, if the ultrasonic impedance of the medium on both sides of the boundary is different, the ultrasonic wave will be refracted at the boundary, impairing the straightness of the ultrasonic wave, and the ultrasonic wave generated by the ultrasonic wave generator will be detected efficiently by the detector. There is also the problem of not being done.

The present invention has been made to solve these problems, and an object of the present invention is to make it possible to always maintain the best ultrasonic matching between a matching liquid and a subject. An object is to provide an ultrasonic bone mineral quantification device (generally, an ultrasonic transmission inspection device).

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an ultrasonic wave for inspecting the characteristics of an object by measuring the speed and attenuation of the ultrasonic wave passing through the object. In the transmission inspection apparatus, a) a measuring tank for containing a test liquid inside and a matching liquid for reducing ultrasonic reflection on the surface of the test object, and b) provided on the same side of the inner wall of the measuring tank with respect to the test object Ultrasonic generator and ultrasonic detector, c) matching degree changing means for changing the matching degree of the matching liquid, and d) detection of the ultrasonic detector with respect to the intensity of the ultrasonic wave generated by the ultrasonic generator. So that the intensity of the ultrasonic waves to be maximized
And a matching degree adjusting means for controlling the matching degree changing means.

[0008]

Operation: First, the subject is placed in the measuring tank, and the periphery thereof is filled with the matching liquid. The matching degree adjusting means controls the matching degree changing means so that the intensity of the ultrasonic wave detected by the ultrasonic detector is maximized when the intensity of the ultrasonic wave generated by the ultrasonic generator is constant. .. The matching degree changing means is, for example,
The matching degree of the matching liquid in the measuring tank is changed by changing the temperature of the matching liquid or changing the mixing ratio of two or more matching liquids having different matching degrees. In this way, after the matching liquid is best matched, the ultrasonic wave is passed through the subject, and the velocity, the attenuation amount, etc. in the subject are measured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic bone mineral quantifying device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the present apparatus includes a measuring unit 10, a matching liquid injection / discharge unit 11, a matching liquid temperature control unit (matching degree changing unit) 12, an ultrasonic oscillation control unit 1.
3, an ultrasonic measurement unit 14, a control unit 15, and a display unit 16. The measurement unit 10 includes a measurement tank 20 in which a subject's foot (heel) is placed, and two pairs of ultrasonic transducers 21 and 22 provided to face the inner wall of the measurement tank 20. Further, the control unit 15 includes a matching degree control unit (matching degree adjusting means) 1 for adjusting the matching degree between the matching liquid and the subject.
7, a sound velocity / attenuation amount calculation unit 18 that calculates the sound velocity and attenuation amount of ultrasonic waves, and a bone mineral salt amount equivalent amount conversion unit 19 that converts these calculated values into bone mineral amount equivalent amounts. In each ultrasonic transducer pair 21, 22, the transducer 2
1a and 21b face each other, and transducers 22a and 22b face each other.

The bone mineral content is measured by the ultrasonic bone mineral content measuring apparatus as follows. First, the heel of the subject is placed in the measurement tank 20 at a position where only one transducer pair 22 is blocked and the other transducer pair 21 is not blocked. Next, a matching liquid (for example, water) whose temperature is controlled to a predetermined temperature is injected from the matching liquid injecting / discharging portion 11 to the injection port 23
It is poured into the measuring tank 20 from. When the liquid level meter 25 provided on the inner wall of the measuring tank 20 detects that the liquid level in the measuring tank 20 has reached a predetermined level, the matching liquid injecting / discharging unit 1
1 stops the injection of the matching liquid. After that, after the state of the matching liquid is stabilized, the matching adjustment between the heel as the subject and the matching liquid is performed as follows.

First, as shown in FIG. 3 (a), the ultrasonic oscillation control section 13 has one transducer 22a (or 2) of the transducer pair 22 which is shielded by the heel.
The ultrasonic pulse is emitted from 2b) toward the heel. A part of this ultrasonic wave is reflected at the boundary between the matching liquid 26 and the heel 27, and the transducer 22a (or 2) that emitted the ultrasonic wave.
2b), the ultrasonic measurement unit 14 uses the same transducer 22a (or 22b) as the ultrasonic intensity.
To detect.

The reflectance of ultrasonic waves at the boundary between the matching liquid and the subject generally changes depending on the temperature of the matching liquid, as shown in FIG. 2 (a) or (b). For example, FIG. 2 (a)
In the combination of the matching liquid of this type and the test object, the reflectance is the lowest when the temperature of the matching liquid is T3, and the amount of reflected ultrasonic waves regardless of whether the temperature of the matching liquid is lower or higher. Will increase. Further, in another combination of the matching liquid and the subject, as shown in FIG. 2B, the reflectance may simply increase or decrease in the adjustable temperature range.
Here, the adjustable temperature range is usually a temperature that a human body as a subject can tolerate.

In any case, the matching degree control unit 17 issues a command signal to the matching liquid temperature control unit 12 so as to change the temperature of the matching liquid, so that the matching liquid in the matching liquid injection / discharge unit 11 can be controlled. While the temperature is gradually changed, the matching liquid 26 whose temperature has changed is injected into the measuring tank 20 through the inlet 23 (at the same time, the matching liquid 26 in the measuring tank 20 is discharged from the outlet 24 by the same amount. To). In this way, the matching liquid 26
While changing the temperature, the matching degree control unit 17 detects the point where the reflectance becomes the lowest in a predetermined temperature range (between T1 and T2) while observing the ultrasonic intensity detected by the ultrasonic measurement unit 14. To do. In this way, the temperature at which the reflectance becomes the lowest (Fig. 2
After detecting the temperature T3 in (a) and the temperature T1 in FIG. 2 (b), the matching degree control unit 17 sends a command signal to the matching liquid temperature control unit 12 so as to set the temperature of the matching liquid 26 to that temperature. Out and inject the matching liquid 26 adjusted to the optimum temperature.
It is injected into the measuring tank 20 by the discharge part 11.

Note that the temperature of the matching liquid is not adjusted outside the measuring tank 20 (matching liquid injecting / discharging portion 11) as described above, but a temperature sensor, a heater, and a cooler are provided in the measuring tank 20 for measurement. The temperature of the matching liquid may be directly controlled in the tank 20. Further, in order to change the matching degree between the matching liquid and the subject, the temperature of the matching liquid is changed in the above example, but the matching degree of the matching liquid is changed by changing the mixing ratio of the two liquids having different acoustic impedances. May be changed. For example, water (acoustic impedance z ≈
It is also possible to use a mixture of 1.5 × 10 ⁶ kg / m ² ) and glycerin (z≈2.5 × 10 ⁶ kg / m ² ) as the matching solution, and change the mixing ratio of both when adjusting the matching. it can.

After the matching degree between the matching liquid and the subject (the heel) is optimized as described above, quantitative measurement of bone mineral is started.
The control unit 15 first measures the velocity vw of the ultrasonic waves in the water and the attenuation amount rw (per unit distance) by the transducer pair 21 having no heel. First, the ultrasonic oscillation control unit 13 emits an ultrasonic pulse from one transducer 21a and the other transducer 21b.
Then, the ultrasonic measuring unit 14 receives the time tw during that period.
To measure. Since the distance L between the two transducers 21a and 21b is known, the velocity vw of the ultrasonic waves in the water under the present conditions can be obtained as vw = L / tw. Further, the attenuation amount rw is obtained by measuring the intensity of the ultrasonic wave detected by the transducer 21b on the receiving side by the ultrasonic wave measuring unit 14 and comparing this with the intensity of the ultrasonic wave generated by the transducer 21a on the generating side. be able to. These are the control unit 15
The sound velocity / attenuation amount calculation unit 18 therein calculates.

On the other hand, the thickness of the heel 27 is measured by the transducer pair 22 with the heel 27 interposed. Figure 3
As shown in (a), each transducer 22a, 22a
An ultrasonic pulse is emitted from b, and the ultrasonic wave reflected by the surface of the heel 27 and returning is emitted from the transducer 22.
a, 22b itself detects. The ultrasonic measurement unit 14 measures the times t1 and t2 from the emission of the ultrasonic pulse to the detection for each of the transducers 22a and 22b. Based on the measured values t1 and t2, the control unit 15 determines the distances L1 and L2 between the transducers 22a and 22b and the surface of the heel 27.
Is calculated as L1 = vw · t1 / 2 and L2 = vw · t2 / 2. Further, the thickness Lb of the heel 27 is calculated as Lb = L-L1-L2.

Finally, the ultrasonic velocity vb and the attenuation amount rb in the calcaneus are measured by the transducer pair 22 in which the heel 27 is also interposed. That is, one transducer 22a emits an ultrasonic pulse, and the other transducer 22b detects it (or vice versa), and measures the time twb and the intensity of the detected ultrasonic wave during that period. From this measured value, the ultrasonic velocity vb in the calcaneus can be calculated as vb = Lb / (Lb / vw + Δt) Δt = twb−tw. Alternatively, as shown in FIG. 3B, it can be calculated as vb = Lb / (tw-t1 / 2-t2 / 2). Further, the attenuation amount rb of the ultrasonic wave in the calcaneus can also be calculated by substituting the detected ultrasonic intensity value into a predetermined formula. The value of the thickness Lb of the calcaneus is also required in the calculation of the attenuation amount, but by substituting the value Lb calculated as described above, it is possible to measure the attenuation amount with good reproducibility. Based on the velocity or the attenuation amount of the ultrasonic wave calculated in this way, the bone mineral content equivalent conversion unit 19 calculates the bone mineral equivalent amount, and the result is displayed on the display unit 16.

Next, as another embodiment of the present invention, an expandable bag (bolus) containing the matching solution is used instead of dipping the sample (heel) in the matching solution, and matching with the sample is performed. An example of fixing the subject will be described as well. As shown in FIG. 4, in the measuring unit 10 of the bone mineral quantification device of the present embodiment,
A bolus 41 is provided inside the frame 40, and the matching liquid is filled inside the frame 40 so that the heel 27, which is the subject, is surrounded by the matching liquid without any gap. Therefore, the control unit 1 of the present embodiment
5 and the matching liquid injecting / discharging unit 11 monitor the pressure sensor 43 provided in the bolus 41, and
The matching liquid is injected and discharged through the inlet 44 and the outlet 45 so that the pressure of the matching liquid in 1 becomes constant. As a result, the bolus 41 always fixes the heel 27 with a constant pressure, prevents movement of the heel 27 during measurement, performs accurate bone mineral quantitative measurement, and guarantees reproducibility of measurement.

After fixing the heel 27 in this way, the temperature of the matching liquid in the bolus 41 is changed by the matching degree control unit 17 to change the temperature between the heel 27 and the bolus 41 as in the case of the above embodiment. The temperature of the matching liquid that provides the best matching is detected (in this embodiment, the temperature sensor 42 provided in the bolus 41 is used), and the matching liquid in the bolus 41 is heated to that temperature. Alternatively, the measurement is performed after cooling. That is, ultrasonic waves are passed through the calcaneus by ultrasonic transducer pairs 46 provided on the inner walls on both sides of the frame 40 with the heel 27 interposed therebetween, and the velocity and attenuation of the ultrasonic waves in the calcaneus are measured (FIG. 5). (A)). It should be noted that, as shown in FIG. 5B, the velocity and the attenuation amount of the ultrasonic wave in the matching liquid are such that the bolus 41 is expanded without sandwiching the heel 27, and the matching liquid in the bolus 41 is placed between the transducer pair 46. It is possible to measure by using only.

Also in this embodiment, as shown in FIG. 6 (a), the transducer pairs 46 and 47 are arranged at a place where the heel is not interposed and a place where the heel is interposed so that the measurement can be performed only once. You can also In addition, FIG.
As shown in (b), a plurality of boluses 41 (on the both sides of the heel in the figure) 48 and 49 may be provided.
Although the bone mineral quantification device using the calcaneus as the subject is illustrated in each of the above-described examples, the present invention may be applied to ultrasonic transmission measuring devices in general, such as those using soft tissue as the subject, in addition to bone. it can.

[0021]

According to the ultrasonic transmission inspection apparatus of the present invention,
Since the ultrasonic matching between the matching liquid and the subject is always kept optimal, the amount of ultrasonic waves passing through the subject increases and the measurement sensitivity improves. Further, since the refraction on the surface of the subject is reduced, the ultrasonic path is less likely to be bent, and the decrease in the ultrasonic detection intensity due to the path deviation is minimized. As a result, the sensitivity of the ultrasonic transmission measuring device can be improved, and more accurate bone mineral content (equivalent amount) can be measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a bone mineral quantification device that is an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the temperature of the matching liquid and the ultrasonic reflectance of the boundary between the matching liquid and the subject.

FIG. 3 is a cross-sectional view of a state in which a heel, which is a subject, is placed in the measurement tank.

FIG. 4 is a configuration diagram including a perspective view and a block diagram of a bone mineral quantification device having a measurement unit using a bolus that is another embodiment of the present invention.

FIG. 5 is a plan view of the measurement unit when the ultrasonic measurement is performed by fixing the heel with a bolus (a) and when the ultrasonic measurement is performed only by the bolus (b).

FIG. 6 is a plan view showing a modified example of a measurement unit using a bolus.

[Explanation of symbols]

 10 ... Measuring unit 12 ... Matching liquid temperature control unit (matching degree changing unit) 17 ... Matching degree control unit (matching degree adjusting unit) 26 ... Matching liquid 27 ... Heel 40 ... Frame 41 ... Bolus

Claims (1)

[Claims] 1. An ultrasonic transmission inspection apparatus for inspecting the characteristics of an object by measuring the velocity, attenuation, etc. of the ultrasonic wave passing through the object, comprising: a) ultrasonic waves inside the object and the surface of the object. A matching tank for reducing the reflection of the light, b) an ultrasonic generator and an ultrasonic detector provided on the same side of the inner wall of the measuring tank with respect to the subject, and c) matching the matching liquid A matching degree changing means for changing the degree, and d) so that the intensity of the ultrasonic wave detected by the ultrasonic detector becomes maximum with respect to the intensity of the ultrasonic wave generated by the ultrasonic wave generator.
An ultrasonic transmission inspection apparatus comprising: a matching degree adjusting means for controlling the matching degree changing means.