KR101643104B1 - Method and apparatus for estimating cortical bone mineral density using time-reversed lamb waves - Google Patents

Abstract

As the SGW can be accurately measured by irradiating a time-reversed lamb wave to the cortical bone of the tibia, the cortical bone using the time reversing lamb wave which predicts the bone density of the cortical bone through the propagation velocity of the lamb wave propagating along the cortical bone of the tibia, And a method for predicting bone mineral density.
According to the present invention, since cortical bone mineral density is predicted using harmless ultrasound to the human body, there is no damage such as radiation exposure due to measurement using conventional radiation, so that the human body is relatively safe, It is possible to calculate the propagation speed of a slow guided wave (SGW) signal closely related to the bone density of the cortical bone, and thus it is possible to predict a reliable cortical bone density.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a method and apparatus for predicting bone density of a cortical bone using a time reversal lamb wave,

The present invention relates to an apparatus and a method for predicting cortical bone density using a time reversal Lamb wave.

Recently, the number of patients with degenerative osteoporosis is also increasing as the standard of living improves, medicine develops, life expectancy increases, and the elderly population increases.

Degenerative osteoporosis is reported to be caused by osteoporosis in skeletal volume reduced by 10% of the total population in the United States. The annual incidence of osteoporosis-related fractures increases and the annual medical expenses are increasing.

This is because osteoporosis is a very important disease because bone fracture can be caused by a decrease in bone mineral density below the fracture threshold and fracture can be caused even with a small impact and fracture is a major cause of death in the elderly. Therefore, development of a device for measuring the risk of fracture This is a required situation.

To this end, in Korean Patent Registration No. 10-1053438 (filed on August 22, 2009, registered on July 27, 2011, hereinafter referred to as "prior art"), a radioisotope emitting two or more gamma- To measure bone mineral density.

However, since the prior art is required to irradiate high-energy radiation to measure the bone density per unit area, it is inevitable that the patient is exposed to radiation, and a method of accurately measuring the bone density of the cortical bone during the conventional method of diagnosing osteoporosis has not been disclosed There is a problem that accurate diagnosis of osteoporosis is difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique for predicting an accurate cortical bone density without using radiation in the diagnosis of osteoporosis.

To achieve this object, there is provided a lamb wave generator for generating a lamb wave from an electrical signal; A lamb wave transmitter for irradiating the tibia with a lamb wave generated by the ram derivative; A lamb wave receiving unit for receiving the lamb wave irradiated by the lamb wave transmitting unit; A converter for converting the Lamb wave received by the Lamb wave receiver into an electrical signal; A signal processing unit for detecting an electrical signal converted by the converting unit, the signal inverting unit inverting a time of the electrical signal received by the converting unit; And an operation unit for calculating the propagation speed of the lamb wave propagated along the cortical bone by analyzing the electrical signal detected by the signal processor and for predicting the bone density of the cortical bone through the propagation speed of the lamb wave propagated along the calculated cortical bone The Lamb wave transmitting unit transmits the time-reversed electric signal to the Lamb wave generating unit by the time inverting unit to generate time-inverted Lamb waves. The Lamb wave transmitting unit irradiates the time-reversed Lamb waves, The bone density of the cortical bone is predicted using the linear relationship between the propagation velocity value of the time-reversed lamb wave propagated along the cortical bone and the bone density value of the cortical bone in proportion to and increasing in amount, The propagation velocity of a first arriving signal (FAS) or the slow guided wave (SGW) Of the propagation velocity.

delete

delete

delete

The apparatus for predicting cortical bone density using the time reversing lamb wave further includes an output unit for outputting a result calculated by the arithmetic unit.

And the lamb wave irradiated from the lamb wave transmitting unit is a single mode lamb wave having a single frequency in the range of 180 to 220 kHz.

On the other hand, a method of predicting cortical bone density includes: an initial lamb wave irradiation step of irradiating a lamb wave generated by a lamb wave generator to a tibia; A first conversion step of receiving a Lamb wave from the Lamb wave receiving unit in the initial Lamb wave irradiation step and converting the Lamb wave into an electrical signal; A time reversing step of receiving the Lamb wave first irradiated to the tibia from the Lamb wave receiving unit and converting the received Lamb wave into an electrical signal, receiving the electrical signal converted by the time reversing unit, and inverting the time; A time reversing Lamb wave generating step of generating the Lamb waves of time reversal from the electrical signals obtained by time-inverting the Lamb wave generator in the time inverting unit; A time inverted lamb wave irradiation step of irradiating the tibia with the time-reversed lamb wave generated by the lamb wave transmitter in the lamb wave generator; A second conversion step of receiving the time reversal Lamb wave from the Lamb wave reception unit and converting the Lamb wave into the electrical signal in the time reversing Lamb wave irradiation step; And a calculation step of calculating a propagation speed of a lamb wave propagated along the cortical bone through the electrical signal converted in the second conversion step, wherein the calculation step comprises: Calculating a propagation speed of the lamb wave propagated along the cortical bone by the calculation unit; And a prediction step of predicting a bone density of the cortical bone using a correlation between the propagation velocity of the lamb wave propagated along the cortical bone calculated in the propagation speed calculation step and the bone density of the cortical bone, Predicting a bone mineral density of the cortical bone using a linear relationship between a propagation velocity value of a time-reversed lamb wave propagated along a cortical bone and a bone mineral density value of the cortical bone in an increasing amount, A propagation velocity of a first arriving signal (FAS) or a slow guided wave (SGW) that first reaches the receiving unit.

In this case, the lamb wave irradiated by the Lamb wave transmitting unit in the initial lamb wave irradiating step may be a single mode lamb wave having a single frequency in the range of 180 to 220 kHz.

delete

delete

The method of predicting cortical bone density using the time reversed lamb wave further includes an output step of outputting a propagation speed of the lamb wave propagated along the cortical bone calculated in the calculating step and a bone density prediction result of the cortical bone.

As described above, the present invention has the following effects.

First, since the cortical bone mineral density is predicted by using the harmless ultrasound to the human body, the human body is comparatively safe because no damage such as radiation exposure is caused by the measurement using the conventional radiation.

Second, by irradiating time-reversed lambs to the tibia, it is possible to calculate the propagation speed of a slow guided wave (SGW) signal, which is closely related to the cortical bone density of the tibia, so that reliable cortical bone density can be predicted.

FIG. 1 is a schematic view of an apparatus for predicting a cortical bone density using a time reversing lamb wave according to an embodiment of the present invention.
FIG. 2 is a time-inverted Lamb wave signal generated by the time inverting unit and the Lamb wave generating unit of the present invention.
3 is a graph showing the propagation speed of a lamb wave propagated along the cortical bone of a tibia sample at different distances between the lamb wave transmitter and the lamb wave receiver.
FIG. 4 is a graph showing the correlation between the propagation speed of the Lamb wave and the bone density of the cortical bone sample, which are time-reversed through the tibia sample.
FIG. 5 is a flowchart illustrating a method of predicting bone density of cortical bone using a time reversal Lamb wave in an embodiment of the present invention.

The preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which the technical parts already known will be omitted or compressed for simplicity of explanation.

<Construction of Prediction Tool for Bone Mineral Density of Cortical bone using time reversal Lamb wave>

FIG. 1 schematically shows an apparatus for predicting a cortical bone density of a cortical bone using a time reversal lamb wave according to an embodiment of the present invention, and FIG. 2 shows a time-reversed Lamb wave signal generated by the time reversal unit and the lamb wave generator of the present invention FIG. 3 is a graph showing the correlation between the propagation velocity of Lamb waves through the tibia sample and the bone density of the cortical bone sample.

The apparatus 100 for predicting cortical bone density of a cortical bone using a time reversal Lamb wave according to an embodiment of the present invention includes a lamb wave generator 110, a lamb wave transmitter 120, a lamb wave receiver 130, a converter 140, 150, a signal processing unit 160, an operation unit 170, and an output unit 180.

The lamb wave generator 110 can generate a lamb wave based on the received electric signal.

Here, a lamb wave is a waveguide in which a structure propagates along a structure when generating a seismic wave in the structure, and is called a lamb wave or guided ultrasonic wave.

Therefore, the lamb wave generator 110 can generate a lamb wave to propagate the lamb wave to the tibia in which the bone density is to be measured.

The Lamb wave transmitting unit 120 radiates the Lamb waves generated by the Lamb wave generating unit 110 to the tibia.

Here, the lamb wave irradiated from the lamb wave transmitter 120 is a single mode lamb wave having a center frequency of any one of 180 to 220 kHz, and the center frequency of the lamb wave according to the embodiment of the present invention is 200 kHz .

At this time, the above range may be variously changed according to the kind of bone to be examined (for example, spongy bone).

The Lamb wave receiver 130 can receive the Lamb waves transmitted by the Lamb wave transmitter 120 and transmitted through the tibia B and provide the Lamb waves to the converter 140.

The converting unit 140 may convert the Lamb waves received by the Lamb wave receiving unit 120 into electrical signals and provide the converted electrical signals to the time inverting unit 150 or the signal processing unit 160.

The time inverting unit 150 may time-reverses the electrical signal received from the converting unit 140. [

The time reversing unit 150 may receive the lamb wave first irradiated to the tibia B by the lamb wave transmitting unit 120 from the converting unit 140 and provide the lamb wave generating unit 110 with the electric signal have.

2, a graph of FIG. 2 (a) is a Lamb wave not inverted in time, which is checked by the best lamb wave transmitting unit 120, and shows a first arriving signal (FAS) and a SGW (slow guided wave) can be observed.

Here, the SGW, which is closely related to the bone density of the cortical bone, is easily modulated due to other signals received after the FAS and SGW, which makes it difficult to accurately measure the bone density.

Accordingly, the converting unit 140 converts the signal of the graph (a) first received by the Lamb wave receiving unit 120 into an electrical signal, and the time inverting unit 150 converts the signal of (a) The signal of the graph is inverted in time (that is, the flow of time is reversed).

Thereafter, the lamb wave generator 110 receives the time-reversed electrical signal to generate a time-reversed lamb wave, and the generated lamb wave is irradiated to the tibia B through the lamb wave transmitter 120.

The graph of FIG. 2 (c) shows that the conversion unit 140 converts the time-inverted Lamb waves received from the Lamb wave receiver 130 into electrical signals, and can confirm that the Lamb waves are focused in a temporal / spatial manner. At this time, the SGW appears as a peak signal.

(d) The graph is a frequency spectrum obtained by Fourier transform of the graph. The time reversal ramp has a single frequency of 200 kHz, so that a single-mode Lambertian can be obtained.

That is, the time inverting unit 150 inverts the electrical signal of the first irradiated lamb wave by time so that the lamb wave generator 110 can generate the lamb wave inverted from the lamb wave irradiated through the first tibia B, (110). &Lt; / RTI &gt;

The signal processing unit 160 can detect the electrical signal converted by the converting unit 140 and can detect the electrical signal of the time-inverted Lamb wave among the Lamb waves propagated along the tibia.

Here, the signal processor 160 can detect the SGW signal closely related to the peak of the electrical signal converted from the time-reversed Lamb wave, that is, the bone density of the cortical bone.

The calculating unit 170 calculates the propagation speed of the lamb wave propagated along the tibia through the electrical signal detected by the signal processor 160 and predicts the bone density of the cortical bone through the calculated propagation velocity.

Here, the propagation speed is a first arriving signal (FAS) or a slow guided wave (SGW).

In the embodiment of the present invention, the operation unit 170 can calculate the propagation speed of the Lamb wave inverted in time through the SGW signal detected by the signal processor 160.

In addition, the operation unit 170 can predict the cortical bone density of the tibia B through data on the cementum bone density of the pre-stored tibial sample (BS) and the propagation speed of the Lamb wave according to the bone density of the cortical bone.

At this time, the operation unit 170 may be a PC such as a desktop or laptop equipped with an application capable of inputting and outputting data and calculating and comparing and analyzing the stored data with the measured data.

The output unit 180 may output the bone density predicted value of the cortical bone according to the propagation speed and the propagation speed of the lamb wave measured by the calculation unit 170. The output unit 180 may output the bone density of the cortical bone to a display device such as a monitor connected to the operation unit 170, The device can be used.

<Method of Predicting Bone Mineral Density of Cortical Bones Using Time Inverted Lamb Wave>

FIG. 5 is a flowchart illustrating a method of predicting bone density of cortical bone using a time reversal Lamb wave in an embodiment of the present invention.

The method of predicting cortical bone density using a time reversal Lamb wave according to an embodiment of the present invention may include an initial Lamb wave irradiation step S510, a first transformation step S520, an operation step S530, and an output step S540 have.

1. Initial Lamb wave irradiation step <S510>

In the initial lamb wave irradiation step S510, the lamb wave transmitting unit 120 transmits the initial lamb wave generated by the lamb wave generating unit 110 to the tibia to irradiate the time-inverted lamb wave to the tibia B to specify the cortical bone density. .

2. First conversion step < S520 >

The first conversion step S520 is a step in which the conversion unit 140 converts the initial investigation lamb wave detected in the initial lamb wave irradiation step S510 into an electrical signal and provides the electric signal to the time reversal unit 150. [

3. Time reversal step < S530 >

In the time reversal step S530, the time inverting unit 150 inverts the electrical signal obtained by converting the first radio wave propagated along the tibia B in the conversion unit 140.

4. Time reversing lamb wave generation step (S540)

The time reversal lamb wave generation step S540 is a step in which the lamb wave generation unit 110 generates a time reversing lamb wave from the electrical signal time-inverted by the time inverting unit 150 and provides the time reversing lamb wave to the lamb wave transmission unit 120. [

5. Time reversing Lamb wave irradiation step (S550)

The time reversal lamb wave irradiation step S550 is a step in which the lamb wave transmitting unit 120 irradiates the time-reversed lamb wave generated in the lamb wave generating unit 110 to the tibia B.

That is, in the initial lamb wave irradiation step S510, an electrical signal obtained from the lamb wave irradiated on the initial tibia B is time-reversed to generate a time-reversed lamb wave, and the generated time-reversed lamb wave is irradiated to the tibia B After the completion of the one-time operation, the position of the Lamb wave receiving unit 130 is displaced by a predetermined distance, and the time inverted Lamb wave irradiation step S550 is repeated to irradiate the time reversed Lamb waves for each distance.

6. Second conversion step < S560 >

The second conversion step S560 is a step in which the conversion unit 140 converts the Lamb waves inspected in the time inverted lamb wave irradiation step S550 into electrical signals and provides the electrical signals to the signal processing unit 160. [

7. Operation step <S570>

The calculation step S570 detects the SGW signal from the electrical signal of the time inverted lamb wave converted by the signal processing unit 160 in the conversion unit 140 and the arithmetic unit 170 calculates the propagation speed to predict the bone density of the cortical bone , And may include a propagation speed calculation step S571 and a prediction step S572.

The propagation speed calculation step S571 calculates the propagation speed of the time inverted lamb wave propagated along the axial direction of the tibia B by measuring the time at which the arithmetic section 170 receives the SGW signal detected by the signal processing section 160 And will be described with reference to Figs. 2 to 3. Fig.

2 to 3, it can be seen that the electrical signal of the time inverted Lamb wave forms a peak of the SGW signal, and the reception of the SGW signal according to the difference in distance between the Lamb wave transmitter 120 and the Lamb wave receiver 130 It can be seen that the time is measured differently.

The prediction step S572 compares the propagation speed of the lamb wave calculated in the propagation velocity calculation step S571 with the cemented bone density data of the pre-stored tibia sample BS and the propagation velocity data of the lamb wave according to the cortical bone density, ) Of the cortical bone.

Here, the Lamb wave propagation velocity data according to the measured cortical bone density data (that is, the bone density data of the pre-stored tibial sample (BS)) and the cortical bone mineral density are obtained from the cortical bone mineral density of 18 small tibial bone samples (BS) ), Which is measured by irradiating a Lamb wave inverted in time, and will be described with reference to FIG.

4, 18 small tibial bone samples (BS) were prepared, bone mineral density of each cranial bone sample (BS) was measured, and each of the tibial bone samples (BS) was irradiated with a time reversed lamb wave to measure the lamb wave propagation velocity Quot; * " in the graph.

In this case, there is a positive (+) linear correlation between the propagation velocity of the time reversed Lamb wave and the bone density of cortical bone, and the Pearson correlation coefficient r value obtained by the linear regression method is 0.76, It can be seen that the propagation velocity of Lamb waves has a very high linear correlation with the bone density of the cortical bone and the phase velocity of the A0 mode lamb wave indicated by the solid line and the time reversed lamb wave propagated along the tibial axis direction of 18 tibial samples , It can be confirmed that the time reversed lamb wave propagated along the tibial bone sample BS is an A0 mode lamb wave.

That is, the propagation speed of the time reversal lamb wave propagated along the tibia B calculated from the propagation speed calculation step S572 in the estimation step S572 is calculated by multiplying the propagation speed of the time reversal lamb wave with respect to the measured tibia sample BS The bone density of the cortical bone (B) can be predicted by comparing the bone density of the cortical bone with that of the cortical bone.

In other words, it means that it is possible to derive a predetermined regression equation from the correlation between the propagation velocity of the time reversal Lem's wave and the bone density value of the cortical bone in the prediction step S572. Therefore, by measuring the propagation velocity of the time- It is possible to predict the bone density value of the cortical bone.

8. Output step < S580 >

The outputting step S580 is a step of outputting the cortical bone density prediction result value according to the propagation speed value of the time inverted lamb wave propagated along the tibia B in the calculation step S570 and the propagation speed of the output unit 180 to the display device and the printing device And outputting the result through a visual display.

As a result, the present invention uses an induction ultrasound harmless to the human body, unlike the method of measuring bone density, which irradiates high-energy radiation to a patient's measurement site, It is possible to minimize the patient's discomfort and physical damage when measuring the risk of occurrence, and it is possible to calculate the propagation speed of the SGW signal which is closely related to the bone density of the cortical bone of the tibia by irradiating the tibia with a time-

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. And the scope of the present invention should be understood as the following claims and their equivalents.

100: Prediction of bone density of cortical bone using time reversal Lamb wave
110: Lamb wave generating unit
120: Lamb wave transmitter
130: Lamb wave receiver
140:
150: half an hour
160: Signal processor
170:
180: Output section
B: Tibia
BS: Tibia sample

Claims (11)

A lamb wave generator for generating a lamb wave from an electrical signal;
A lamb wave transmitter for irradiating the tibia with a lamb wave generated by the ram derivative;
A lamb wave receiving unit for receiving the lamb wave irradiated by the lamb wave transmitting unit;
A converter for converting the Lamb wave received by the Lamb wave receiver into an electrical signal;
A time inverting unit for inverting the time of the electric signal received by the converting unit;
A signal processing unit for detecting an electrical signal converted by the conversion unit; And
And an operation unit for analyzing the electrical signal detected by the signal processing unit to calculate the propagation speed of the lamb wave propagated along the cortical bone and for predicting the bone density of the cortical bone through the propagation speed of the lamb wave propagated along the calculated cortical bone, ,
The Lamb wave transmitter transmits a time inverted electrical signal to the Lamb wave generator to generate time-inverted Lamb waves. The Lamb wave transmitter examines the time-reversed Lamb waves in the Lamb wave transmitter,
Wherein the calculation unit estimates the bone density of the cortical bone by using a linear relationship between a propagation velocity value of the time reversed lamb wave propagated along the cortical bone and a bone density value of the cortical bone in proportion to and increasing in amount,
Wherein the propagation velocity is a propagation velocity of a first arriving signal (FAS) or a slow guided wave (SGW) that first arrives at the lamb wave receiving unit. Prediction device. delete delete delete The method according to claim 1,
The apparatus for predicting cortical bone density using the time reversing Lamb wave includes:
And an output unit for outputting a result calculated by the calculation unit. The apparatus for predicting bone density of cortical bone using time reversal Lamb wave. The method according to claim 1,
Wherein the lamb wave irradiated from the lamb wave transmitting unit is a single mode lamb wave having a single frequency in the range of 180 to 220 kHz. An initial lamb wave irradiation step in which the lamb wave transmitting unit irradiates the lamb wave generated by the lamb wave generating unit to the tibia;
A first conversion step of receiving a Lamb wave from the Lamb wave receiving unit in the initial Lamb wave irradiation step and converting the Lamb wave into an electrical signal;
A time reversing step of receiving the Lamb wave first irradiated to the tibia from the Lamb wave receiving unit and converting the received Lamb wave into an electrical signal, receiving the electrical signal converted by the time reversing unit, and inverting the time;
A time reversing Lamb wave generating step of generating the Lamb waves of time reversal from the electrical signals obtained by time-inverting the Lamb wave generator in the time inverting unit;
A time inverted lamb wave irradiation step of irradiating the tibia with the time-reversed lamb wave generated by the lamb wave transmitter in the lamb wave generator;
A second conversion step of receiving the time reversal Lamb wave from the Lamb wave reception unit and converting the Lamb wave into the electrical signal in the time reversing Lamb wave irradiation step; And
And a calculation step of calculating a propagation speed of the lamb wave propagated along the cortical bone through the electrical signal converted by the calculation unit in the second conversion step,
Wherein,
A propagation speed calculation step of the signal processing unit detecting the electrical signal converted in the first conversion step and calculating the propagation speed of the lamb wave propagated along the cortical bone by the calculation unit; And
And a prediction step of predicting the bone density of the cortical bone using a correlation between the propagation velocity of the lamb wave propagated along the cortical bone calculated in the propagation speed calculation step and the bone density of the cortical bone,
Wherein the calculating step is a step of predicting a bone density of the cortical bone using a linear relationship between a propagation velocity value of the time reversed lamb wave propagated along the cortical bone and a bone density value of the cortical bone in proportion to and increasing in amount,
Wherein the propagation velocity is a propagation velocity of a first arriving signal (FAS) or a slow guided wave (SGW) that first arrives at the lamb wave receiving unit. Prediction method. 8. The method of claim 7,
Wherein the lamb wave irradiated from the lamb wave transmitting unit in the initial lamb wave irradiating step is a single mode lamb wave having a single frequency in the range of 180 to 220 kHz. delete delete 8. The method of claim 7,
The method of claim 1, further comprising: an output step of outputting a propagation velocity of a lamb wave propagated along the cortical bone calculated in the calculating step and a bone density prediction result of the cortical bone using the time reversing lamb wave. A Method for Predicting Bone Mineral Density of Cortical Bones Using Inverted.

Images