JPH05237108A - Ultrasonic transmission inspecting instrument - Google Patents

Abstract

PURPOSE:To always keep a measuring condition constant, and to obtain measuring data having reproducibility, and also, being comparable thereby by detecting an ultrasonic wave reflected by a subject, or allowed to transmit through the subject, and moreover, comparing a two-dimensional distribution of the ultrasonic wave with a prescribed reference. CONSTITUTION:In the inside of a measuring tank 20, a subject 18 of a feel (foot), etc., and an ultrasonic matching liquid are contained. Also, on one inner wall in the measuring tank 20, a pair of ultrasonic transducer arrays 21, 22 are provided. That is, for instance, in one transducer array, an ultrasonic wave emitted from an emitting transducer 211, and also, reflected by the subject 18, or allowed to transmit through the subject 18 is detected by a detecting transducer 212. Moreover, a two-dimensional distribution of the detected ultrasonic wave is compared with a prescribed reference, and whether or not their difference is separated above a prescribed value is checked. In such a way, a measuring condition is always kept constant, by which measuring data which has reproducibility, and can be compared strictly with each other.

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 an ultrasonic bone mineral quantification device used for diagnosis of osteoporosis.

[0002]

2. Description of the Related Art Osteoporosis is a condition in which the density of bone tissue decreases due to calcium deficiency or the like. For the diagnosis, ultrasonic waves are transmitted through the bone, and the speed (sound velocity) and the amount of the ultrasonic waves transmitted through 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 an ultrasonic 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. ) Is used. 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 an ultrasonic wave is emitted from the generator in that state, the ultrasonic wave propagates at a speed corresponding to the amount of bone mineral and is attenuated when passing through the calcaneus. Therefore, by measuring the velocity or the amount of transmission of ultrasonic waves with a detector, the amount corresponding to the amount of bone mineral in the calcaneus, which is the subject, can be measured.

[0004]

The measurement value of bone mineral content is meaningless unless the measurement points are constant. In other words, if the measurement points differ from person to person, it will not be possible to compare these data, and even if the same person has different measurement points from each measurement, secular changes cannot be accurately traced and accurate diagnosis cannot be made. .. Therefore, it is desirable that the location of the subject to be subjected to the ultrasonic transmission inspection is always constant. Here, the measurement location can be made constant to some extent by drawing the position where the foot (subject) is placed on the bottom of the measurement tank. However, since the amount of ultrasonic waves reflected by the surface of the subject depends on the angle (with respect to the propagation direction of the ultrasonic waves) of the surface of the subject, the measurement result of the amount of transmission shows that the difference in the surface angle of the subject (that is, ,
It is also affected by the orientation of the subject or the difference in the surface shape of the subject. Therefore, it is difficult to obtain sufficiently reproducible and mutually comparable data by simply drawing the position where the foot is placed.

[0005]

SUMMARY OF THE INVENTION In the present invention made to solve such a problem, the ultrasonic wave reflected on the surface of the object and the ultrasonic wave transmitted through the object are measured to measure the object. An ultrasonic transmission inspection apparatus for inspecting ultrasonic transmission characteristics, comprising: a) a measuring tank in which a test object and an ultrasonic matching liquid are placed, and b) a plurality of ultrasonic sensors arranged two-dimensionally on one inner wall of the measuring tank. A detection element array composed of sound wave detection elements, and c) Two-dimensional distribution of ultrasonic waves reflected by a subject or transmitted through the subject to reach the above-mentioned detection element array and detected by each ultrasound detection element. And a check means for comparing with a predetermined standard.

[0006]

By detecting the ultrasonic waves reflected on the surface of the subject with each ultrasonic detecting element of the detecting element array (in this case, the ultrasonic generating element is provided on the inner wall surface on the same side as the detecting element array). It is possible to obtain the two-dimensional intensity distribution of the reflected wave. When the angle of the surface of the subject in front of the ultrasonic wave generating element is different from the angle defined as the predetermined reference inspection state, the two-dimensional distribution of this reflected wave deviates from the reference distribution form. In such a case, it is difficult to obtain data that can be compared with other data even if an ultrasonic transmission test is performed.
Prompt appropriate measures such as re-measurement and issuing an alarm (to change the orientation or position of the subject).

Similarly, for the ultrasonic waves transmitted through the subject (in this case, the ultrasonic wave generating element is provided on the inner wall surface opposite to the detecting element array), the two-dimensional intensity is detected by the detecting element array. Although a distribution is obtained, this distribution shape also depends on the angle of the surface (on the ultrasonic wave incident side) of the subject, so the checking means compares this with a predetermined reference, and if the difference from the reference is greater than a predetermined value, Check if there is. As a result, as in the case of the reflected wave, the surface angle of the subject at the ultrasonic wave incident position can be made substantially constant.

[0008]

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. 2, the apparatus includes a measurement unit 10, a matching liquid control unit 11, an ultrasonic wave generation control unit 12, an ultrasonic wave detection unit 13, a frequency control unit 14, a time difference measurement unit 15, an intensity measurement unit 16, and a main control. It consists of part 17. The main control unit 17 is composed of a microcomputer including a CPU, a ROM, a RAM and the like (not shown), and performs a bone mineral quantification process described below according to a program stored in the ROM in advance. As shown in FIG. 1, the measurement unit 10 includes a measurement tank 20 for receiving a heel (foot) that is a subject, and
A pair of ultrasonic transducer arrays 21 and 22 provided to face the inner wall of the measuring tank 20 is included. Each of the ultrasonic transducer arrays 21 and 22 has a large number of ultrasonic transducers two-dimensionally arranged, and each transducer generates ultrasonic waves and
It can also be detected.

The procedure for measuring the amount of bone mineral with this ultrasonic bone mineral amount measuring apparatus will be described with reference to the flow chart of FIG. 3 and FIGS. First, a predetermined amount of ultrasonic matching liquid (for example, water) whose temperature is controlled by the matching liquid control unit 11 to a predetermined temperature is measured in the measuring tank 2
0 is injected into the measurement tank 20, and the foot of the subject is put into the measurement tank 20 to prepare for measurement (step S1).

Next, it is checked whether or not the subject is correctly placed at a predetermined reference position and orientation. Therefore, an ultrasonic pulse is emitted from a predetermined transducer 211 in one transducer array 21 (for example, the transducer in the center of the transducer array 21). Then, all the transducers 212 (including the emitted transducer 211) of the transducer array 21 detect the ultrasonic waves reflected on the surface of the subject almost in front of the transducer 21. The main controller 17 collects these data,
A two-dimensional intensity distribution of the reflected wave is obtained (step S2). Here, it is desirable to use ultrasonic waves having a spatial resolution as high as possible. Therefore, the frequency of the ultrasonic wave emitted here is higher than the frequency of the ultrasonic wave used in the later-described attenuation measurement (for example, about 3 MHz). The frequency of the emitted ultrasonic waves is set by the frequency control unit 1
4 does.

When the surface of the subject is almost parallel to the inner wall surface of the measuring tank 20, the intensity of the ultrasonic wave emitted by the transducer 211 is the highest. ) Is obtained, but when the surface of the subject is inclined with respect to the inner wall surface, the peak position of the two-dimensional detected intensity distribution is the transducer 21
It is a different place from 1. Therefore, as shown in FIG. 6A, the two-dimensional detected intensity distribution 31 of the reflected wave of the ultrasonic wave emitted from the transducer 211 at a predetermined position has a predetermined range (lower limit value 32, upper limit value 33, median value 34). It is possible to check whether or not the flat surface portion of the subject is in front of the transducer (or whether or not the angle is a predetermined angle) by determining whether or not the inside of the transducer enters (step S3). it can. In addition to the above, the two-dimensional detection intensity distribution 31 is checked by checking whether the peak height of the distribution is within a predetermined range (FIG. 6 (b)). Whether it is within a predetermined neighborhood (FIG. 6C), or whether there are multiple peaks in the distribution or whether the shape is abnormal (FIG. 6C).
(D)) or the like may be determined.

By performing such a check with respect to a plurality of transducers of the transducer array 21, it is possible to determine whether or not the position and angle of the subject are the predetermined reference position and reference angle. Figure 6
If the detected two-dimensional intensity distribution 31 does not fall within the predetermined range 32 to 33, an alarm is issued to the operator or the subject, remeasurement is performed, or the subject (foot) is Ask them to change the way they are placed. In this case, the above process is repeated from step S1.

After it is confirmed that the position and orientation of the subject are within a certain allowable range, the distance from each inner wall of the measuring tank 20 to the subject is measured by each transducer array 21, 22 (step S4). ). A procedure for measuring the distance on that side by one transducer array 21 will be described with reference to FIG. First, the ultrasonic wave generation control unit 12 is used to emit an ultrasonic wave pulse from one transducer 211 in the transducer array 21. Then, similarly to the above, all the transducers of the transducer array 21 (including the emitted transducer 211) detect the ultrasonic waves reflected on the surface of the subject 18. Since it is desirable to use an ultrasonic wave having a spatial resolution as high as possible, an ultrasonic wave having a frequency (for example, about 3 MHz) higher than the frequency of the ultrasonic wave used in the attenuation measurement described later is used.

The time difference measuring unit 15 measures the time difference between the ultrasonic pulse being emitted by the transducer 211 and the reflected pulse being detected by each transducer 212, and the emission transducer 211 is measured based on the time difference.
-The distance L1 + L11 between the surface of the subject 18 and the detection transducer 212 is calculated (the speed of the ultrasonic wave in the ultrasonic matching liquid is separately detected as described later). Since the distance d between the firing transducer 211 and the detection transducer 212 is known, the wall on this side and the subject 1
The distance L1 from the surface of 8 can be calculated from the measured value L1 + L11. Similarly, for the transducer array 22 on the inner wall on the opposite side, the distance L2 between each transducer and the subject 18 is measured. Since the distance L between both inner walls of the measuring tank 20 is known, the thickness Lb (in the ultrasonic wave transmitting direction) of the subject 18 is subtracted by subtracting the measured values L1 and L2 by the corresponding transducers from this distance L.
Can be detected for each point of the transducer arrays 21, 22.

Based on the distance data, a point or a region for ultrasonic transmission measurement is determined according to a predetermined standard (step S5). For example, it can be defined as a point having the largest thickness Lb of the subject 18 or a region of a predetermined number of transducers around the point.

When the subject 18 is a foot (heel), the ultrasonic waves returning to the transducer array 21 are those reflected on the surface (skin) of the foot, and the soft tissue and bone tissue inside the foot. Some are reflected at the boundary with. That is,
The “surface of the subject 18” may be skin or the surface of bone tissue. However, the arrival time of the ultrasonic pulse that is reflected by these surfaces and returns is different from each other in time, so that they can be detected separately. Which one is adopted can be selected according to the purpose of measurement, but when quantifying bone mineral, the distance to the surface of the bone tissue is measured.

The intensity distribution of the ultrasonic waves detected by each transducer of the transducer array 21 is such that the reflecting surface (the surface of the foot 18 or the boundary between the soft tissue and the bone tissue inside the foot 18) is parallel to the surface of the transducer 211. In some cases, as shown in FIG. 4, it has the highest peak at the location where it is fired, but this is not always the case when the reflecting surface is tilted, and the emitted transducer 21
It is possible that 1 may detect only a small amount of ultrasonic waves. The ultrasonic bone mineral quantification device of this embodiment has an advantage that the distance can be reliably measured even in such a case.

Next, ultrasonic transmission measurement is performed using the transducer of the point or area selected in the above distance measurement. This will be described with reference to FIG. First, in order to reduce the attenuation of ultrasonic waves in the subject 18, the frequency control unit 14
Thus, the frequency of the ultrasonic wave used is set to a lower frequency (for example, about 500 kHz) than that used for distance measurement. Then, the ultrasonic wave generation control unit 12 emits ultrasonic waves from the selected transducer 213 in the one transducer array 21 (step S6), and each transducer 21 of the opposing transducer array 22.
It is detected in step 4 (step S7). Since the ultrasonic waves emitted from the transducer 213 are refracted and spread on the surface of the subject 18 (calcaneus), the ultrasonic waves are detected by the transducer 214 in a wide range in the opposing transducer array 22. The intensity values of the detected ultrasonic waves are sent from the ultrasonic wave detection unit 13 to the intensity measurement unit 16 where they are all added (step S8). This added value (sum) is St
And (amount of transmitted component).

Next, the subject 18 is taken out of the measuring tank 20 (step S9), and ultrasonic waves are emitted from the same transducer 213 without the subject being interposed (step S1).
0), all the transducers 214 of the transducer array 22 detect it (step S11). The added value (sum) of all the ultrasonic detection amounts at this time is set to Wt (reference amount, step S12). At this time, the speed of ultrasonic waves in the ultrasonic matching liquid (water) is also measured.

In the case of a simple inspection, St / Wt can be used as the inspection value as the ultrasonic attenuation by the subject 18. The attenuation degree St / Wt here is obtained as follows. Now, assuming that the intensity of the ultrasonic wave emitted from the transducer 213 in steps S6 and S10 is I0, the sum St, Wt of the respective ultrasonic wave detection amounts is expressed as follows. St = I0 · exp {−μw · (L−Lb) −μb · Lb} Wt = I0 · exp {−μw · L} where μw and μb are the ultrasonic matching liquid (water) and the object 18 respectively. Attenuation rate (coefficient), L is the distance between the transducers, and Lb is the thickness of the subject 18. From these equations, the attenuation degree St / Wt is St / Wt = exp {(μw−μb) · Lb}.

However, since the Wt measured here includes the amount of light reflected by the surface of the object 18, the more accurate measurement is reflected by the surface of the object 18. The ultrasonic component Sr must be removed from Wt. Therefore, in the ultrasonic bone mineral quantification device of this embodiment, the transducer array 21 on the side that emits ultrasonic waves is used.
Also, in each of the transducers 215 (including the firing transducer 213), ultrasonic waves reflected by the surface of the subject 18 (here, including the surface of the calcaneus as well as the surface of the foot (skin)) and returning are returned. It is detected (step S7).
Then, the reflection component amount Sr can be obtained by obtaining the sum of the amounts of ultrasonic waves detected by the respective transducers 215 (step S8). In this way, the ultrasonic attenuation of the subject (calcaneus) 18 is St / (Wt-Sr)
It can be obtained more (step S13). The bone mineral content of the calcaneus, which is the subject, is obtained by substituting this attenuation degree into a relational expression (or conversion table) that has been obtained in advance.

Although the inspection of the ultrasonic transmission characteristics of the subject 18 is completed for the time being, the same procedure is performed in the opposite direction, that is, ultrasonic waves are transmitted from the transducer array 22 to the transducer array 21 and the same procedure is performed. Alternatively, the attenuation may be measured, and the value obtained by averaging the attenuations obtained by the both measurements may be used as the attenuation of the subject 18. Further, the attenuation value per unit distance may be calculated using the value Lb of the thickness of the subject 18 calculated in advance.

For the attenuation measurement, the attenuation may be measured for each frequency in a certain range (for example, 200 kHz to 1 MHz), and the physical characteristics of bone may be evaluated by the slope of the change in the attenuation with respect to the frequency. In the above example,
The frequency of the ultrasonic wave reflected on the surface of the object 18 is increased to measure the thickness of the object 18, and the frequency of the ultrasonic wave transmitted to the object 18 is decreased to inspect the ultrasonic transmission characteristics of the object 18. However, instead of switching the frequency of the ultrasonic wave to be emitted in this way, an ultrasonic wave of a wide band frequency is emitted and the target frequency (the reflected wave is measured) on the receiving side (ultrasonic wave detecting section 13). In this case, only the high frequency side and the low frequency side when the transmitted wave is measured may be taken out by the filter. In addition, the reflected wave is used in the above-described embodiment to check whether or not the angle of the surface of the subject (that is, the position and the orientation of the subject) is predetermined, but as shown in FIG. Alternatively, the two-dimensional intensity distribution of the transmitted wave may be checked by comparing it with a predetermined reference distribution.

[0024]

In the ultrasonic transmission inspection apparatus of the present invention, the checking means compares the two-dimensional distribution of the ultrasonic waves reflected on the surface of the subject or the ultrasonic waves transmitted through the subject with a predetermined reference. Then, it is checked whether or not the difference is more than a predetermined value. Therefore, the measurement conditions can be kept almost constant at all times, and reproducible measurement data that can be strictly compared with each other can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a measurement unit of an ultrasonic bone mineral quantification device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an ultrasonic bone mineral quantification device according to an embodiment.

FIG. 3 is a flowchart showing a process performed by a main control unit when quantifying bone mineral.

FIG. 4 is an explanatory diagram showing the principle of measuring a distance to a subject by a transducer array on one inner wall surface.

FIG. 5 is an explanatory diagram showing the principle when measuring the ultrasonic transmission characteristics of a subject.

FIG. 6 is a graph showing a relationship between a two-dimensional detected intensity distribution and a check standard.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Measurement part 11 ... Matching liquid control part 12 ... Ultrasonic wave generation control part 13 ... Ultrasonic wave detection part 14 ... Frequency control part 15 ... Time difference measurement part 16 ... Intensity measurement part 17 ... Main control part 18 ... Subject (foot) 20 ... Measuring tank 21, 22 ... Transducer array 211, 213 ... Emitting transducer 212, 214, 215 ... Detection transducer 31 ... Two-dimensional detection intensity distribution 32, 33, 34 ... Lower limit, upper limit, median of standard distribution range

Claims (1)

[Claims] 1. An ultrasonic transmission inspection apparatus for inspecting ultrasonic transmission characteristics of a subject by measuring ultrasonic waves reflected on the surface of the subject and ultrasonic waves transmitted through the subject, wherein: a) the subject inside And a measurement tank containing an ultrasonic matching liquid, b) a detection element array including a plurality of ultrasonic detection elements arranged two-dimensionally on one inner wall of the measurement tank, and c) reflected by a subject, or An ultrasonic wave transmitting device, comprising: a check means for transmitting a two-dimensional distribution of ultrasonic waves that have passed through a subject to reach the detection element array and detected by each ultrasonic detection element and a predetermined reference. Inspection equipment.