KR20020082378A - A osteoporosis apparatus and method by ultrasound longitudinal transmission - Google Patents

Abstract

PURPOSE: An apparatus and a method for diagnosing an osteoporosis using an ultra wave are provided to diagnose an initial progressive step of the osteoporosis by utilizing the ultrasonic wave to measure density of bone. CONSTITUTION: A transmitting ultrasonic converter(1) converts an electric signal to an ultrasonic wave by using a piezoelectric phenomenon. A receiving ultrasonic converter(2) converts the ultrasonic wave to the electric signal by using a piezoelectric phenomenon. The transmitting ultrasonic converter(1) and the receiving ultrasonic converter(2) are combined with the first and the second wedges(3,4). The first and the second wedges(3,4) are adhered to interval shaft(6). An interval control handle(7) is adhered to the interval shaft(6). A wedge fixing portion(8) maintains an interval between the first and the second wedges(3,4).

Description

Osteoporosis Diagnosis Device Using Ultrasound and Its Method {A OSTEOPOROSIS APPARATUS AND METHOD BY ULTRASOUND LONGITUDINAL TRANSMISSION}

The present invention relates to a diagnostic apparatus and method for diagnosing osteoporosis by measuring bone density using ultrasonic waves, in more detail, the ultrasonic wave is transmitted in the longitudinal direction of the tibia of the human body, and the sound wave is transmitted according to the density of the bone. The present invention relates to an apparatus and method for diagnosing osteoporosis using ultrasound, in which bone density is measured by measuring a change in attenuation coefficient of each band according to the characteristics of the speed of the ultrasound, the structure of the bone, and the nonlinear degree due to the distortion of the transmission waveform.

Osteoporosis refers to a condition in which bone to be hardened is weakened by various causes and can be easily damaged or broken.In the area where osteoporosis fracture can occur, all parts of the body where the bone is present, and in the case of severe osteoporosis, gum Scenic spots also occur. Estrogen, which increases calcium absorption and prevents calcium from escaping from bone, is particularly acute in women because the hormone suddenly decreases after a woman's menopause, and in recent years, even young women who are not menopause have a desire to thin. Excessively reduce the physiological interruption is caused by hormonal abnormalities. Only a few years ago, the diagnosis of osteoporosis was very difficult, but recent advances in technology have made it possible to diagnose osteoporosis by measuring bone density. Bone density refers to the strength of bones. The higher the bone density, the harder the bones. In the definition of WHO, the World Health Organization, osteoporosis is called osteoporosis (OSTEOPOROSIS) when less than 25% of the bone density of healthy young people is called. Being explained. Therefore, osteoporosis can be determined by measuring bone density.

As described above, there is a method of diagnosing osteoporosis by measuring bone density, and a method of predicting and evaluating the risk of fracture by measuring bone density using radiation. In this way, general X-ray imaging and single photon absorption method (Single Photon Absorpitometry: SPA), Dual Photon Absorpito-metry (DPA), Dual Energy X-ray Absorpitometry (DEXA), and Quantative Computed Tomography (QCT) using Computed Tomography (CT). This is harmful to the human body, and particularly fatal for pregnant women and requires significant expensive costs. In addition, there is a significant difference when considering the risk and frequency of fractures when comparing children or adolescents with older adults having the same bone density. Therefore, assessing the risk of fracture with bone density alone has limitations because bone density does not reflect both structural and physical characteristics of bone.

Due to the problem of radiation, research on bone density measurement method using ultrasonic waves has been actively conducted. However, as a method of measuring bone density using ultrasound, a diagnosis method using ultrasound may be a transmission method that penetrates a measurement part of a human body. The transmission method of ultrasound measurement penetrates a calcaneus (heel bone) of a human body. In this way, water is used as a medium to utilize the permeability of ultrasonic waves. However, the transmission method that penetrates the measuring part of the ultrasound varies depending on the thickness of the calcaneus and soft tissue, the heterogeneity of the calcaneus, the anatomical position between individuals and the error of foot position and angle during measurement. Because of the lack of reproducibility due to changes in the temperature of the water, the apparatus is complicated to overcome this, and there are many difficulties in quantitative diagnosis.

Accordingly, an object of the present invention is derived to solve the above problems, in order to identify the osteoporosis at an early stage to help the treatment, to provide an osteoporosis diagnostic apparatus by measuring the accurate bone density using ultrasound.

Another object of the present invention is to provide a method for diagnosing osteoporosis using ultrasound.

In order to achieve the above object, the present invention provides an apparatus for diagnosing osteoporosis using ultrasonic waves, comprising: ultrasonic wave transmitting means for transmitting ultrasonic waves and generating ultrasonic waves after measuring the density of the medium; Ultrasonic receiving means for receiving ultrasonic waves transmitted from the ultrasonic transmitting means; A first wedge for allowing the ultrasonic wave transmitted from the ultrasonic wave transmitting means to be incident at a predetermined tilt angle with a medium to be measured for density; A second wedge for causing the ultrasonic receiving means to have a predetermined inclination angle with the medium; And it provides a density measuring apparatus using the ultrasonic wave, characterized in that the first wedge and the second wedge is configured to have a fixed interval.

In addition, the present invention is a method for diagnosing osteoporosis using ultrasound, the method of measuring the density by using ultrasound to measure the density of the medium by transmitting the ultrasound, the step of injecting the ultrasonic wave into the medium at a predetermined angle; Provided is a density diagnosis method using ultrasonic waves, characterized in that the step of receiving the ultrasonic wave passed through the medium is a ultrasonic wave incident at a predetermined angle.

1 is a cross-sectional view showing a cross section of the probe assembly used in the apparatus for diagnosing osteoporosis using ultrasound of the present invention.

2 is a diagram illustrating a wedge for attaching a transmitting or receiving ultrasonic transducer so that ultrasonic waves are obliquely incident.

3 is a diagram showing that the ultrasound proceeds in the tibia in the probe assembly.

4 is a diagram showing that the ultrasonic wave is refracted at an angle of 90 degrees at the interface of the medium.

FIG. 5 illustrates a model in which ultrasonic transducers and biological soft tissues are placed in a straight line and ultrasonic waves are perpendicularly incident on tissues to measure the degree of attenuation of ultrasonic waves among density variables.

6 is a diagram showing waveforms of reflected waves reflected from a medium.

7 is a diagram illustrating a spectrum of reflected waves reflected from a medium.

8 is a diagram illustrating a process in which a continuous standing wave is attenuated by a nonlinear effect.

9 is an ultrasound waveform obtained from a receiving ultrasound transducer using a longitudinal transmission method.

10 shows the frequency response of the filter used.

11 shows an example of the result of performing the FFT using the Hamming Window after filtering.

12 and 13 are the results of frequency shift analysis by chemical reactions of pig and bovine tibia.

14 is an ultrasonic wave waveform obtained by a receiving ultrasonic transducer using a longitudinal transmission method.

Figure 15, Figure 16 is a diagram showing the ultrasound delivery rate in the tibia of pigs and cattle.

17 shows in block diagram the principle of the second harmonic amplitude method.

18 is a diagram showing that the amplitude of the second harmonic increases as osteoporosis increases.

FIG. 19 is a chart of the cumulative distribution of expected and observed distributions for standardized residuals when multiple regression analysis is performed using all of the frequency shift, transmission speed, and nonlinear phenomenon parameters.

20 is a structural diagram of a bone density measuring apparatus connected to the probe assembly to measure bone density.

21 is a view showing a memory area of the DSP unit used in the osteoporosis diagnosis apparatus using the ultrasound of the present invention.

The present invention will be more clearly understood from the following description, in comparison with the prior art, with reference to the accompanying drawings.

1 is a cross-sectional view showing a cross section of the probe assembly used in the apparatus for diagnosing osteoporosis using ultrasound of the present invention. Referring to Figure 1, the probe assembly (Lee 10 is largely an ultrasonic transducer for transmitting (1) for transmitting ultrasonic waves, ultrasonic transducer for receiving (2) for receiving ultrasonic waves, distance separation axis (6), wedge fixing The means 8, the distance adjusting handle 7, the BNC connector 5, the transmitting ultrasonic transducer 1 and the receiving ultrasonic transducer 2 are constituted by wedges 3 and 4.

The transmitting ultrasonic transducer 1 is a means for transmitting ultrasonic waves, which is a means for converting an electrical signal into ultrasonic waves using a piezoelectric phenomenon, and the transmitting ultrasonic transducer 2 is a means for receiving ultrasonic waves. On the contrary, it is a means for converting the received ultrasonic waves into electrical signals using the reverse piezoelectric phenomenon. Then, the transmitting ultrasonic transducer 1 and the receiving ultrasonic transducer 2 are combined with the wedges 3 and 4 and the wedge 3 has a constant angle so that the ultrasonic waves transmitted from the transmitting ultrasonic transducer 3 are constant. Allow the angle of incidence to be transferred to the medium. The wedge 4 is also attached to the receiving ultrasonic transducer 2 so as to have a constant angle toward the medium. FIG. 2 shows wedges 3 and 4 for attaching transmission or reception ultrasonic transducers 1 and 2 so that ultrasonic waves are obliquely incident. As shown in Fig. 2, the wedges 3 and 4 have a transducer mounting hole to which the transducer is mounted and a rear face for sound absorption, so that the ultrasonic transducers 1 and 2 for transmission or reception are attached to the transducer mounting hole. The ultrasonic wave transmitted by the transmitting ultrasonic transducer 1 by the wedge 3 is incident on the medium at a predetermined angle.

Then, the wedges 3 and 4 attached to the transmitting ultrasound transducer 1 and the receiving ultrasound transducer 2 are attached to the distance-distance axis so that the wedges 3 and 4 can move in the horizontal direction. The attached ultrasonic transducer 1 and the ultrasonic receiver 2 can be moved in the horizontal direction. In addition, it has two screw grooves with different directions with respect to the center of the distance separation axis, so that the distance adjustment handle 7 is attached to the distance separation axis 6 to rotate the distance adjustment handle 7 so that each wedge has a distance separation axis ( 6) to move in the opposite direction. Then, a cable for supplying an electrical signal to the transmitting ultrasonic transducer 1 using the BNC connector 5 is connected, and a cable for outputting an electrical signal output from the receiving ultrasonic transducer 2 is connected. do.

Ultrasound propagates only through the medium, and when the ultrasound propagates through the medium, it carries histological information in the medium. Therefore, the state of the medium can be analyzed by analyzing the propagation characteristics parameter of the ultrasonic waves. In general, the characteristic parameters of ultrasonic waves in living tissues include reflection, refraction, attenuation, velocity, and nonlinear phenomena. The bone mineral density of the tibia is measured using the property of the ultrasound. In general, about 90% or more of the tibia is composed of cortical bone, and the remainder is composed of trabecular bone. And, the part related to the strength of the bone is cortical bone to diagnose osteoporosis by measuring the bone density of the cortical bone.

When the ultrasonic waves pass through two media having different densities, the ultrasonic waves are refracted according to Snell's law according to the density of the media at the interface of the media.

In Snell's Law Is the angle of incidence of the ultrasound Is the refraction angle of the ultrasonic wave, Is the velocity of ultrasound in the first medium Is the velocity of the ultrasonic waves in the second medium. And, Is the density of the first medium, Is the density of the second medium.

3 is a diagram showing that the ultrasound is refracted at the interface of the tibia. Referring to FIG. 3, when the ultrasound is inclined into the cortical bone, the ultrasound is refracted at the interface between the cortical bone and the cancellous bone. The spongy bone is similar in density to the skin of the human body, so the change in the direction of ultrasound can be ignored at the interface between the skin and the spongy bone. In addition, since the velocity of the ultrasonic wave in the medium has a constant value, the size of the refraction angle can be changed by adjusting the angle of incidence incident on the cortical bone. By adjusting the size of the angle of incidence, the angle of refraction can be 90 degrees. have. The angle at which the angle of refraction is 90 degrees is called the critical angle. In order to inject the ultrasonic wave at such a critical angle, the wedge 3 is attached to the transmitting ultrasonic transducer to adjust the incident angle of the ultrasonic wave transmitted by the transmitting ultrasonic transducer. Wedge (3) may be composed of a Teflon similar to the skin tissue and sound velocity and acoustic impedance of the human body. When the angle of refraction is 90 degrees, ultrasound is transmitted along the tibia, and the direction of travel along the tibia is defined as the longitudinal direction. When the ultrasonic waves are transmitted in the longitudinal direction, the intensity of the ultrasonic waves received by the receiving ultrasonic transducer is maximized. According to Snell's law, the angle of the wedge 3 may be determined by using the velocity and the incident angle of the ultrasonic wave in the medium according to Snell's law.

Table 1 shows the rate at which ultrasound proceeds in living tissues and metals.

Medium Speed (m / s) Air water (20 ° c) Lead Pb Aluminum Fat tissue Soft tissue Brain Blood Blood Eye Skull Teflon 33014802400640014501540154115491570162040801340

By using the table and Snell's law, the angle of incidence can be adjusted so that the angle of refraction of the ultrasonic wave is 90 degrees so that the ultrasonic wave can travel along the surface of the tibia.

In addition, the receiving ultrasonic transducer 2 includes ultrasonic waves transmitted by the transmitting ultrasonic transducer 1 as the medium progresses in the medium, and the intensity of the sound wave decreases due to the change in velocity, absorption, scattering and reflection, and the like, and nonlinearity. Is received. Therefore, the density of the medium can be used for the measurement by using the speed change, the intensity reduction degree, the nonlinearity, etc. of the ultrasonic wave in the receiving ultrasonic transducer 2 as the density variable for the density measurement. In order to use the density parameter, the ultrasonic wave received by the receiving ultrasonic transducer 2 is converted into an electrical signal, and the density is measured by analyzing the electrical signal.

FIG. 5 is a diagram illustrating a model in which an ultrasonic transducer and a living tissue are placed in a straight line and ultrasonic waves are perpendicularly incident on the tissue in order to measure the degree of attenuation of ultrasonic waves among density variables. As shown in FIG. 5, the incident ultrasound is reflected at the interface between the medium and the medium, so that PN (f) reflection occurs once in front of the living soft tissue and PF (f) reflection occurs again in the rear of the living soft tissue. Burn reflection will occur. The waveform of the reflected wave is shown in FIG. When the signal reflected from the A part is called PN (t) and the signal reflected from the B part is called PF (t), the following relationship is established between the amplitudes.

Where is the acoustic attenuation coefficient and the unit is [Np / cm]. But 1 [Np] is 8.686 [dB], so if you write it again,

If the power spectra of the reflected wave P _n ( f) in the A part and the reflected wave P _F (f) in the B part are S _N (f) and S _F (f), respectively, these relations are established.

here Represents an energy transfer function within the tissue through which the ultrasound passes, and can be expressed by Equation 4.

Attenuation Coefficient from Equation 4 Can be obtained as

Attenuation Coefficient Slope The spectral difference method and the spectral shift method are mainly used. The dual frequency shift method uses the following method. If S _N (f) reflected from A is expressed in Gaussian form, it can be expressed as in Equation 6.

In Equation 6, C _N is a constant, B is a measure of the pulse bandwidth, f _N is the center of the spectrum, that is, the center frequency. This spectrum will be simplified like a sine pulse modulated as a Gaussian distribution. At this time, the energy transfer function is shown in Equation 7.

here Is the slope of the attenuation coefficient with nefer units per cm · MHz. 4 is caused because the propagation distance for the reflected signal is equal to 2D. In order to determine the spectrum of the reflected wave reflected at the point B, and calculated by substituting Equation 6 and Equation 7 into Equation 3,

Where C _F is a constant associated with frequency,

In other words, the spectrum maintains the same Gaussian distribution in a slightly smaller form as shown in FIG. However, as shown in FIG. 7, the lower center frequency f _F fmf is shifted. The value can be determined using the shift of the center frequency.

Therefore, the effect of attenuation according to the progression of osteoporosis can be analyzed by using the shift of the center frequency, and the attenuation characteristics can be examined as a valid parameter of bone density measurement.

In general, when considering the propagation of ultrasonic waves, it is assumed that the amplitude of the ultrasonic waves is very small, so that the nonlinear terms of the wave equation are ignored and considered as a linear wave equation. However, when the amplitude of the ultrasonic wave is large, this nonlinear term becomes a wave equation that cannot be ignored. Therefore, the nonlinear phenomenon must be considered. Ultrasonic waves that cannot be regarded as infinitely infinite are defined as finite amplitude ultrasonic waves. In the present invention, the apparatus for diagnosing osteoporosis by the ultrasonic longitudinal transmission method is required to predict the bone density including the nonlinear phenomenon because the intensity of the ultrasonic wave received by the receiving ultrasound transducer is much larger than when the horizontal axis transmission method is used.

It is conceivable that the process of ultrasound propagating in a constant medium is a state of isentropy. The density of the medium And particle velocity Equation 11 is established in between.

Here, if the sound pressure is P, the state equation in which the medium ignores viscosity can be expressed by Equation 12 by Euler's continuous equation.

Sound pressure P and density The state equation representing the relationship with In terms of), it can be expressed by Taylor's series expansion as shown in Equation 13.

Where P is the sound pressure, Is the density of the medium, P ₀ and Represents the value at static pressure, respectively. The coefficients A, B, and C are defined as follows.

Where C is the speed of sound and C ₀ is the speed of sound at constant pressure, that is, the speed of sound of sound waves with infinite small amplitude. Accordingly, B / A is a measure of the quadratic term of the state equation and can be represented by Equation 15.

Here, B / A is referred to as a nonlinear parameter, and when Equation 15 is integrated to examine the process of distorting as the ultrasonic wave propagates, it becomes as follows.

Equation 16 means that the sound velocity C of the finite amplitude sound wave becomes a function of the sound pressure P. In the propagation process, the sound pressure P is positive (+), and the speed is faster than C ₀ , and the sound pressure P is negative (-). Because of slowing down at, the sound pressure wave is distorted and harmonics are generated. Therefore, Equation 16 is an important equation related to the nonlinear parameter of the medium and the distortion of the waveform. When continuous sinusoidal waves propagate, the waveform changes into a stationary phase wave due to this effect. As the ultrasonic waves propagate in the medium as described above, distortion occurs due to nonlinear effects, and attenuation occurs and finally disappears. 8 is a diagram illustrating a process in which a continuous standing wave is attenuated by a nonlinear effect. Referring to FIG. 8, the clean sinusoidal wave a generated from the sound source is crushed as shown in (b) as it propagates. In this process, the harmonic components increase and the fundamental components decrease. If the sound wave further propagates, a wavefront perpendicular to the time axis is formed as shown in (c), and the propagation distance at this time is called a critical distance or a shock wave formation distance. This phenomenon becomes apparent as in (d), and the wavefront is completely perpendicular in (e). In (f) and (g), the stationary wave attenuates nonlinearly and finally disappears.

When finite-amplitude ultrasonic waves propagate in a medium, the waveform distorts and disappears as the propagation distance increases. In the process, the fundamental wave component is attenuated and the harmonic component increases. Herein, the increase and decrease of the second harmonic component are expressed by Equation 17.

Where x is the propagation distance, f ₁ is the fundamental wave frequency, α is the attenuation coefficient, and P ₁ (x) and P ₂ (x) are the fundamental wave sound pressure and the second harmonic sound pressure at the propagation distance x, respectively. Therefore, when the ultrasonic waves propagate into the tissue, the second harmonic component increases and the waveform is distorted. The change of the second harmonic component when the ultrasonic wave propagates by the distance x by the equations (17) and (18) is expressed by the equation (19). However, the wave used at this time is a planar pie, and there is no phase change.

Accordingly, when the nonlinear parameter B / A is obtained from Equation 19, it is as follows.

In addition, when the ultrasonic wave propagates in the medium, the phase shift occurs with attenuation and distortion. The phase shift parameter N indicating this may be expressed as Equation 21.

In addition, the following relationship holds between the phase shift parameter N and the nonlinear parameter B / A.

9 is an ultrasound waveform obtained from a receiving ultrasound transducer using a longitudinal transmission method. When the ultrasonic wave propagates from the transmitting ultrasound wave, it propagates the signal waveform having the center frequency of 1MHz and uses the ultrasonic signal wave acquired from the receiving ultrasonic transducer on the opposite side through the specimen to perform Fast Fourier Transform (FFT). ) Was performed. FFT transmits the data stored in the oscilloscope to a computer offline using a diskette, and analyzes the frequency using AcqKnowledge 3.2.6. The sampling frequency when stored in the oscilloscope was 10 MHz / sample. 1,000 were stored. The frequency analysis was first performed using a Hamming FIR highpass filter with an M value of 39 with a cutoff frequency of 300 kHz. 10 shows the frequency response of the filter used. 11 is an example of the result of performing FFT using a Hamming Window after filtering. In FIG. 11, the part indicated by the arrow is the center frequency of the received ultrasonic signal and has a center frequency of about 850 Hz.

Frequency analysis of each waveform showed that the shift of the center frequency occurred according to the specimen and chemical reaction time before processing. 12 and 13 are the results of frequency shift analysis by chemical reactions of pig and bovine tibia. As the chemical reaction progresses, the movement width of the center frequency changes rapidly, which means that the attenuation becomes more severe as osteoporosis progresses. This means that the frequency attenuation or center frequency shift is a useful parameter for diagnosing severe osteoporosis. .

14 is an ultrasonic wave waveform obtained by a receiving ultrasonic transducer using a longitudinal transmission method. The total propagation time was measured from the beginning of the transmitted signal to the beginning of the received signal using an oscilloscope indicator. Referring to FIG. 14, in order to measure the ultrasonic velocity in the tibia from the measured total time, it is necessary to compensate for the propagation time and length in the wedge, and through this compensation, the propagation time in the actual tibia was calculated. The total propagation time between the transmitting ultrasound transducer and the receiving ultrasound transducer may be expressed as the sum of the propagation time in the wedge and the propagation time in the tibia and may be expressed as follows.

Where V _{b is the} rate of ultrasound delivery in the tibia

D _b : Distance traveled by ultrasound in tibia

T _t : total delivery time

D _w : street of wedge

V _w : speed of ultrasound transmission in the wedge

By dividing the length of the wedge by the ultrasonic delivery speed of the wedge, the propagation time through which the ultrasonic waves pass through the wedge can be obtained. By subtracting the time when the wedge propagates from the total delivery time, the transmission time through which only the tibia passes through the tibia can be obtained. By using this to divide the measurement distance of the tibia by the ultrasonic delivery time it is possible to obtain the ultrasonic delivery speed in the tibia, Figure 15, Figure 16 is a diagram showing the delivery time of ultrasound in the tibia of pigs and cattle. The lengths of the wedges 3 and 4 used in FIGS. 15 and 16 were 0.7 cm, and the total length of the wedges 3 and 4 passed through the ultrasonic transducers 1 and 2 for transmission and reception. Wedges (3,4) using acrylic, the ultrasonic wave transmission rate of acrylic is 2680m / s.

Ultrasonic nonlinear phenomena include non-linear parameter B / A, such as static pressure method, thermodynamic method, pumping wave method, parametric array method, and second harmonic amplitude method. Among them, the second harmonic amplitude method can measure the B / A value with a relatively simple device, and the intensity of the ultrasonic wave (a few mw) and the frequency limit that can be used for the measurement of a living body can be applied to the in vivo measurement. The second harmonic amplitude method is used because it is most likely. 17 shows in block diagram the principle of the second harmonic amplitude method. When the ultrasonic waves are propagated into the medium by the ultrasonic transducer, the signals received by the ultrasonic transducer are passed through a band pass filter (BPF) to obtain fundamental and second harmonic amplitudes. In this process, the second harmonic generated by the nonlinear effect of the tissue is measured to measure the value of the nonlinear parameter B / A. In the present invention, the value of the nonlinear parameter B / A by the second harmonic amplitude method was measured by using the received data obtained from the bovine tibia. As a result, as the bone porosity of the bone progresses as shown in FIG. 18, the amplitude of the second harmonic increases, indicating that the ratio of the second harmonic to the fundamental wave gradually increases. Such nonlinear phenomena have been largely neglected in the case of medical diagnostics using the pulse-echo method or horizontal oscillation type ultrasound osteoporosis diagnostics using the transmission method because of the large attenuation of the reflected wave and the small amplitude. However, in the case of the longitudinal transmission method, since most of the signals propagating the tibia are transmitted to the received ultrasound, considering the nonlinear phenomenon can measure the density of the tibia more accurately.

Although the propagation velocity, attenuation and nonlinearity density parameters of the ultrasonic waves measured above are useful parameters, these density parameters show only qualitative changes. Therefore, the quantitative bone density data is collected by using the density parameter measured through the experiment and other density measuring equipment (eg, CTCT), and the correlation between the density parameter and the data collected by QCT and the density parameter Analyze and establish a longitudinal transmission-type ultrasound bone density diagnosis algorithm.

Using the SPSS 9.0 program, SPSS's statistical analysis program, the algorithm formula extracted through the simple regression analysis of the change in the center frequency of ultrasound and bone density through QCT imaging is as shown in Equation 29. The imaging data and the ultrasonic propagation velocity, Equation 26 used QCT imaging data and ultrasonic nonlinear coefficients.

Where BMD stands for Bone Mineral Density.

Each variable was confirmed to have a certain trend according to the change in bone density. Existing bone density analysis method consists of attenuation and ultrasonic velocity among these three parameters. Here, by performing multiple regression analysis using the same program using only the ultrasonic velocity and the frequency shift parameter, a bone density measurement algorithm as shown in Equation 27 can be obtained. In the present invention, the apparatus for diagnosing bone density by longitudinal transmission of ultrasound was subjected to multiple regression analysis by adding a nonlinear parameter thereto. As a result, an algorithm as shown in Equation 28 was obtained.

Where F _C = center frequency, UV = velocity, and B / A = nonlinear coefficient.

FIG. 19 is a chart of the cumulative distribution of expected and observed distributions for standardized residuals when multiple regression analysis is performed using all of the frequency shift, transmission speed, and nonlinear phenomenon parameters. 19 shows a straight line if two values are equal, the two distributions can be compared by observing how the standardized residual is distributed over the expected straight line.

20 is a structural diagram of a bone density measuring apparatus connected to the probe assembly to measure bone density. Referring to FIG. 20, the bone density measuring apparatus 100 may output the output signals of the A / D converter 20 and the A / D converter 20 to convert analog signals output from the probe assembly 10 into digital signals. DSP 41 for signal processing and internal memory 42 for storing data processed in DSP 41 and ROM 44 for storing data for performing bone density measurement algorithms. And the DSP unit 40 and the digital signal composed of an external memory 43 and an I / O space 46 configured to include a RAM 45 for storing the ultrasonic data inputted through the A / D converter 20. It consists of a central processing unit 30 for loading the signal converted into the memory. In addition, by connecting the PC interface unit 50 that can be connected to the PC (Personal Computer), the osteoporosis diagnostic device using ultrasound is connected to the PC so that anyone can easily use. Then, the display unit 60 is further configured to output information about the measured tibia.

The bone density measuring apparatus 100 converts the ultrasonic waves passing through the tibia into the electrical signal after receiving the ultrasonic transducer 2 for receiving the probe assembly 10. Since the electrical signal is an analog signal, the A / D converter 20 converts the analog signal into a digital signal. In addition, since the frequency of the ultrasonic waves generated by the ultrasonic transducers 1 and 2 used in the osteoporosis diagnosis apparatus using the ultrasonic waves of the present invention is 1 MHz to 2.25 MHz, the sampling time is designed to be twice or more.

The data output from the A / D converter 20 is loaded into the data memory of the FPGA, but logically configured as an interface between the DSP and the FPGA to store data in the DSP memory map area. In some cases, the system can be designed to load directly into the DSP's data memory. 21 is a view showing a memory area of the DSP unit used in the osteoporosis diagnosis apparatus using the ultrasound of the present invention. Referring to FIG. 22, the memory area of the DSP unit is divided into three areas: a program memory area allocated to the internal memory area 42, a data memory area allocated to the external memory 43, and an I / O area 46. Divided. First, use program memory from 0x0080 to 0x4000. The program memory stores data about the DSP's operation so that the DSP can perform its desired operation. The data memory area (0x4000 to 0x8000) contains the values of variables initially belonging to the code and data obtained from the external RAM 45. In the external ROM region (0x8000 to 0xC000), data for allowing the DSP 41 to perform a certain role is stored as a compiled Hex value. This Hex value is moved to the program memory area and executed at boot time. In the external ROM region 44, information of various systems can be written and read. In addition, the external RAM area 45 is an area allocated to an address less than or equal to 0xC000, and stores external data. The external RAM area 45 stores all data converted from the A / D converter into digital signals and stores the data in the data memory. Move to the area. I / O area arranges UART (Universal Asychronous Receiver / Transmitter). When the operation signal is input, the measuring device 100 transmits the system information of the ROM area to the internal memory of the DSP unit. The reason for storing in the internal memory of DSP unit is to make the program operation speed as fast as possible. As the program is executed, data stored in the data area is transferred to the data memory area allocated to the external memory, and the data in the data memory area is accessed by the DSP unit 40. The DSP unit processes the data stored in the internal memory of the DSP unit and sends it to the area allocated to the UART to display the result. In addition, the PC interface is configured to connect to the PC so that the system can be used using the PC. USB is used as the PC interface.

In the present invention, the osteoporosis diagnosis apparatus using ultrasonic waves makes bone density measurement by inclining ultrasonic waves at a density, and measures the time when the ultrasonic waves are transmitted from the ultrasonic transmitter to the ultrasonic receiver, and measures the thickness of the soft tissues of the human body such as skin. By measuring the time that the ultrasound passes, it is possible to know the time when the ultrasound passes through only the tibial part, so that the bone density can be measured without being affected by the soft tissues of the human body, and the ultrasound is transmitted in the longitudinal direction of the tibia. Since the intensity is much larger than that of the transverse transmission method, the prediction of bone density including nonlinear phenomena seems to be more valid. In addition, bone density can be measured without being affected by individual anatomical characteristics such as the thickness of soft tissues of the human body.Bone density can be accurately measured using the speed, attenuation, and nonlinearity of ultrasonic waves as density measurement parameters. Simple measurement and device can easily measure the bone density, anyone can measure the bone density.

In addition, the bone density measuring device can be extended to use throughout the industry, and can be used for nondestructive testing.

While the preferred embodiments of the present invention have been described using specific terms, such descriptions are for illustrative purposes only, and it is understood that various changes and modifications may be made without departing from the spirit and scope of the following claims. Should be done.

Claims (9)

Density measuring device using ultrasonic waves to transmit the ultrasonic waves to measure the density of the medium, Ultrasonic transmitting means for transmitting the generated ultrasonic waves; Ultrasonic receiving means for receiving ultrasonic waves transmitted from the ultrasonic transmitting means; A first wedge for allowing the ultrasonic wave transmitted from the ultrasonic wave transmitting means to be incident with a medium to measure density with a predetermined angle of inclination; A second wedge such that the ultrasonic receiving means has a predetermined inclination angle with the medium; And Density measurement apparatus using ultrasonic waves, characterized in that the first wedge and the second wedge is composed of a fixing means having a predetermined interval. The method of claim 1, And a moving shaft attached to the fixing means to move the first wedge and the second wedge horizontally so that the size of the gap between the first wedge and the second wedge can be adjusted. Density measuring device used. The method according to claim 1 or 2, And a signal analysis device connected to the ultrasonic wave receiving means and analyzing the output signal converted by the ultrasonic wave receiving means. The method of claim 3, wherein The signal analyzing apparatus includes: means for measuring the density parameter using the speed, attenuation degree, and nonlinearity of the ultrasonic wave as the density parameter representing the density of the medium; And a means for calculating the density of the medium using the density parameter. The method of claim 4, wherein And a display device on the signal analysis device to display the bone density of the patient. The method of claim 5, Density measurement apparatus using the ultrasonic wave, characterized in that the signal analysis device further comprises a personal computer interface. The method of claim 1, And the angle of the first wedge is determined so that obliquely incident ultrasonic waves are refracted at the interface of the medium to proceed in the longitudinal direction of the medium. Density measurement using ultrasonic waves to transmit the ultrasonic waves to measure the density of the medium, Injecting the ultrasonic wave into the medium at a predetermined angle; And the ultrasonic wave incident at the predetermined angle is refracted at the interface of the medium, and proceeds in the longitudinal direction of the medium, and receives the advanced ultrasonic wave. The method of claim 8, After the receiving step, measuring the density parameter using a velocity parameter, attenuation degree, and nonlinearity in the medium of the received ultrasonic wave as the density parameter representing the density of the medium; Density measurement apparatus using the ultrasonic wave, characterized in that further comprising the step of measuring the density of the medium using the density parameter.