JPH11221212A - Ultrasonic osteometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic osteometer capable of obtaining an index to which bone information greatly contributes, by utilizing a part to which a signal component permeating into a bone and getting from a transmitting side ultrasonic converter directly to a receiving side ultrasonic converter greatly contributes. SOLUTION: In a bone index calculation means 4, firstly a part which permeated from a received signal through a tested body on a shortest course is extracted by a waveform extraction means 8, a frequency analysis means 9 calculates the frequency distribution of the extracted received signal, and a frequency region extraction means 10 extracts such a frequency region including a frequency which becomes the maximum in the frequency distribution of amplitude and with little influence of a noise. An attenuation index calculation means 11 calculates an index on attenuation of bone properties from the frequency distribution of the extracted region, whereby an index on the bone properties where the bone component greatly contributed can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic bone measuring apparatus which makes an ultrasonic wave incident on the inside of a body and calculates an index related to the property of a bone from a transmitted or reflected signal.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic bone measuring apparatus is disclosed in
One described in Japanese Patent No. 332774 is known.
FIG. 7 shows a configuration of a conventional ultrasonic bone measuring apparatus, and FIG.
And 2 are ultrasonic conversion means for mutually converting ultrasonic waves and electric signals, 3 is a transmitting / receiving circuit for driving the ultrasonic conversion means, 5
Is a display means for displaying an analysis result, 6 is a subject including a bone to be measured, 7 is a propagation medium that mediates the propagation of ultrasonic waves, and 15 is a propagation time measured from a received signal transmitted through the subject 6. The propagation time measuring means 16 is an attenuation measuring means for measuring an attenuation characteristic.

[0003] The operation of the ultrasonic bone measuring apparatus configured as described above will be described. First, the transmission / reception circuit 3
Drives the ultrasonic converter 1 to emit a sound wave. The sound wave emitted by the ultrasonic wave conversion means 1 propagates through the propagation medium 7 and enters the subject 6. The sound wave incident on the subject 6 is divided into a component mainly reflected on the skin surface and the bone surface, and a component mainly transmitted through the subcutaneous tissue and the bone.
The signals are received by the ultrasonic converters 1 and 2, respectively. The transmission component received by the ultrasonic converter 2 is amplified by the transmission / reception circuit 3 and converted into digital data, and then sent to the propagation time measuring unit 15 and the attenuation measuring unit 16. The propagation time measuring means 15 obtains the time at which the amplitude of the transmitted signal takes the maximum value, and calculates the ultrasonic wave propagation time dt as the difference between the time and the time of the ultrasonic emission of the ultrasonic wave converting means 1. Further, the propagation time measuring means 15 determines the time for the sound wave to propagate through the propagation medium
In addition to the measurement of the transmission component, the time when the sound waves emitted from the ultrasonic transducers 1 and 2 are reflected on the surface of the subject and return to the ultrasonic transducers 1 and 2 respectively is measured. From the time dt that passes through the subject 6 and the propagation medium 7, the propagation medium 7
By subtracting the time for transmitting light, the time dt for transmitting only the subject 6 is obtained. Further, the thickness L of the subject 6
Is calculated, and the thickness L of the subject 6 is divided by the propagation time dt as in the following equation (1) to calculate the propagation speed v of the sound wave in the subject 6. v = dt '/ L ... (1)

The attenuation measuring means 16 measures the frequency distribution of the transmission component of the reference medium, and obtains the difference between the amplitudes at the same frequency at two points from the frequency distribution of the transmission component of the subject 6 and the transmission component of the reference medium. Assuming that the differences between the amplitudes of the transmission components between the subject 6 and the reference medium at the two frequencies f1 and f2 and f1 and f2 are A1 and A2, the coefficient A of the frequency-dependent attenuation is obtained by the following equation (2). A = (A1-A2) / (f1-f2) (2) However, when calculating the expression (1), A1, A2
Is determined in dB. Further, water is usually used as the reference medium. The display means 5 displays the obtained propagation velocity v and frequency-dependent attenuation A as indices representing the properties of the bone.

[0005]

However, in the above-mentioned conventional ultrasonic bone measuring apparatus, the transmission signal transmitted through the inside of the bone is not included in the transmission signal of the subject used for calculating the index indicating the characteristic of the bone. There is a problem that signal components propagated along paths other than those directly reaching the receiving-side ultrasonic transducer from the ultrasonic transducer are included, and it is difficult to obtain only bone information in some cases.

The present invention solves the above-mentioned conventional problems, and utilizes a portion where a signal component which penetrates through the inside of a bone and directly reaches from a transmitting ultrasonic transducer to a receiving ultrasonic transducer greatly contributes. Accordingly, it is an object of the present invention to provide an excellent ultrasonic bone measurement device capable of obtaining an index greatly contributed by bone information.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a waveform extracting means for extracting a portion transmitted through a shortest path in a subject from a received signal, and a receiving signal extracted by the waveform extracting means. Frequency analysis means for calculating the frequency distribution of the signal, and frequency domain extraction means for extracting the frequency distribution area based on the shape of the frequency distribution. The component transmitted from the received signal through the subject through the shortest path greatly contributes. The frequency distribution of a part can be obtained.

Further, in order to solve the above-mentioned problem, the present invention obtains the maximum frequency in the frequency distribution of the amplitude with respect to the transmission waveform of the subject and the reference medium, and obtains the bone attenuation characteristic by the frequency difference between the two. An attenuation calculating means for calculating an index is provided so that an index relating to bone attenuation can be obtained from a frequency shift.

Further, in order to solve the above problem, the present invention comprises a group delay amount calculating means for obtaining a group delay amount from a phase frequency distribution, and calculates a group delay time or a group speed to obtain a bone propagation speed. An index can be obtained.

As described above, an index representing the characteristic of the bone is calculated by utilizing the portion where the signal component that passes through the inside of the bone and directly arrives from the transmitting ultrasonic transducer to the receiving ultrasonic transducer greatly contributes. Therefore, it is possible to obtain an excellent ultrasonic bone measurement device in which it is easy to obtain an index greatly contributed by the information of the bone.

[0011]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, there is provided an ultrasonic converting means for converting an ultrasonic wave into an electric signal;
An ultrasonic transmission / reception unit for driving the ultrasonic conversion unit; a waveform extraction unit for extracting a portion transmitted through the shortest path in the subject from the reception signal; and calculating a frequency distribution of the reception signal extracted by the waveform extraction unit. Frequency analysis means, and a frequency domain extraction means for extracting a frequency distribution area based on the shape of the frequency distribution. Has the effect of extracting the frequency distribution of

The invention described in claim 2 is the first invention.
In the ultrasonic bone measurement device described above, attenuation calculation means for determining the maximum frequency in the frequency distribution of the amplitude with respect to the transmission waveforms of the subject and the reference medium, and calculating an index of the attenuation characteristic of the bone based on the frequency shift between the two. And has an effect that an index relating to bone attenuation can be obtained from a signal to which a component that has passed through bone greatly contributes.

[0013] The invention described in claim 3 is the first invention.
The ultrasonic bone measuring apparatus according to the above, further comprising a group delay amount calculating means for obtaining a group delay amount from a phase frequency distribution, and obtaining an index relating to a bone propagation velocity from a signal to which a component transmitted through the bone greatly contributes. It has the effect of being able to.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 shows a configuration of an ultrasonic bone measuring apparatus according to Embodiment 1, wherein 1 and 2 are ultrasonic conversion means for mutually converting ultrasonic waves and electric signals, and 3 is ultrasonic conversion. A transmitting / receiving circuit for driving the means, 4 is a bone index calculating means for calculating an index of bone properties in the subject, 5 is a display means for displaying an analysis result, 6 is a subject including a bone to be measured, 7
Is a propagation medium that mediates the propagation of ultrasonic waves. Further, in the bone index calculating means 4, 8 is a waveform extracting means for extracting a portion transmitted through the subject in the shortest path from the received signal, 9 is a frequency analyzing means for calculating a frequency distribution of the received signal, and 10 is a shape of the frequency distribution. Frequency domain extracting means for extracting a frequency distribution area based on the above, and an attenuation index calculating means 11 for calculating an index relating to attenuation of a received signal. The ultrasonic converters 1 and 2 have the same performance. Also,
In the first embodiment, it is assumed that the ultrasonic wave conversion means 1 receives the radiation of the ultrasonic wave and the reflected wave from the subject 6,
It is assumed that the ultrasonic converter 2 receives a transmitted wave of the subject 6. For the subject 6, a heel having a greater proportion of bone tissue than a proportion of subcutaneous tissue in the propagation path when transmitting sound waves is used, and water is usually used as the propagation medium 7.

The operation of the ultrasonic bone measuring apparatus configured as described above will be described. First, the transmission / reception circuit 3
Drives the ultrasonic converter 1 to emit a sound wave. The sound wave emitted by the ultrasonic wave converting means 1 propagates through the propagation medium 7 and enters the subject 6. The sound wave incident on the subject is
The components are mainly divided into the components reflected on the skin surface and the bone surface, and the components mainly transmitted through the subcutaneous tissue and the bone, and are received by the ultrasonic wave converting means 1 and 2, respectively. The transmitted wave received by the ultrasonic wave converter 2 is amplified by the transmission / reception circuit 3 and converted into digital data, and then sent to the bone index calculator 4. In the bone index calculating means 4, first, a signal component having a long arrival time, for example, a multiple reflection component in the propagation medium 7 and the inside 9 of the subject and a shortest path as a longitudinal wave between the ultrasonic transducers 1 and 2 are obtained by the waveform extracting means 8. The components that have not propagated are removed, and the portion transmitted through the shortest path in the subject is extracted from the received signal. The frequency analysis means 9 calculates a frequency distribution of the extracted received signal. The frequency distribution obtained by the frequency analysis means 9 is extracted by the frequency domain extraction means 10 to include a frequency having a maximum in the frequency distribution of the amplitude, and to extract a frequency domain which is less affected by noise. The attenuation index calculating means 11 includes the frequency domain extracting means 1
An index relating to the attenuation of the bone property is calculated from the frequency distribution of the region extracted by 0. The display means 5 displays the index obtained by the bone index calculation means 4.

Next, the waveform extracting means 8 in the first embodiment
Will be described in more detail with reference to FIG.
2A and 2B are diagrams showing a state of waveform extraction. FIG. 2A shows a received waveform, and FIG. 2B shows an extracted waveform. Also, 2
0 is the received signal transmitted through the subject, 21 is the time when the maximum amplitude of the received waveform is reached, 22 is the first zero cross point appearing after the maximum amplitude, and 23 is the range from which the received signal is extracted.

The component of the sound wave radiated from the ultrasonic wave converting means 1 and incident on the subject 6 which has passed through the bone in the subject 6 and directly reached the ultrasonic wave converting means 2 is converted into the ultrasonic wave by the shortest path. 2 is received early to reach 2. Since it is difficult to obtain bone information other than the component transmitted through the shortest path, of the waveform received by the ultrasonic probe 2, a signal component having a long arrival time, for example, a component transmitted through another path or The characteristic of the bone is analyzed by removing the multiple reflection components and extracting the components transmitted through the shortest path that arrived earlier. However, it is difficult to extract only the components that have passed through the shortest path, because the components that have passed through the shortest path overlap with other components, or the signal durations vary depending on the measurement environment or individual differences between the subjects. . Therefore, an area which is considered to most remarkably reflect the characteristic of the bone is extracted as follows, and an index is obtained.

First, the leading time to be extracted is set as early as possible unless the leading part of the transmitted component is higher than the noise level and other waveforms exist. The rear end obtains a time 21 at which the maximum amplitude of the received waveform is obtained, and obtains an intersection with the first 0 level after that time, that is, a zero cross point 22,
The end of the extracted waveform. A waveform is extracted from the received signal limited to the above range 23 to obtain a waveform as shown in FIG. The same operation is performed on a reference signal which is a reception signal transmitted through only water. In the above description, a signal is extracted using a rectangular window, but a cosine window represented by a Hanning window may be used.

Next, the calculation of the bone property index in the first embodiment will be described in more detail with reference to FIGS. FIG. 3 is a diagram illustrating a difference in a transmission waveform due to a frequency attenuation of a bone. 4A and 4B are diagrams showing a manner of calculating an index of the attenuation characteristic of the bone. FIG. 4A shows the transmission waveform of the subject extracted by the waveform extracting means 8, and FIG. (C) is the frequency distribution of the amplitude, and (d) is the frequency distribution extracted by the frequency domain extracting means 10. Also, 401 is the frequency distribution of the extracted transmitted waveform, 402 is the frequency distribution of the reference signal, 40
Reference numeral 3 denotes a frequency domain to be extracted, 404 denotes a frequency distribution from which components of the measurement system have been removed, and 405 denotes a straight line approximating the frequency distribution 404.

The component transmitted through the shortest path is transmitted through various media such as a subcutaneous tissue and a propagation medium other than the bone, and thus is affected by other components than the bone. By the way, the change of the attenuation with respect to the frequency, that is, the frequency attenuation, is different from the received signal because the frequency-dependent attenuation of water and skin is small and negligible at the ultrasonic frequency of several hundred kHz to several MHz used for calculating the index. If an index related to the frequency-dependent attenuation is obtained, it can be used as an index reflecting the properties of the bone. The magnitude of the frequency-dependent attenuation significantly appears in the received signal at the leading edge of the received signal. Assuming that the bone attenuation increases linearly with frequency,
As shown in FIG. 3, as the frequency-dependent attenuation becomes larger, a low-frequency component appears at the head and the zero-cross interval w1 becomes larger.
The smaller the distance, the closer to the center frequency of the ultrasonic wave used for the measurement, and the shorter the interval w1. The easiest way to get metrics is
It is sufficient to measure the zero-cross interval w1, but it is difficult to accurately determine the rising because the rising portion is gradual or the rising portion may be buried by noise. Therefore, a frequency distribution is obtained by Fourier transform for the waveform near the head of the transmission component, and an index relating to the properties of the bone is calculated from the displacement of the center frequency.

First, the waveform extracted by the waveform extracting means 8 is subjected to Fourier transform by the frequency analyzing means 5 to obtain a frequency distribution 401. The frequency distribution is obtained in units of dB,
The maximum value is normalized as 0 dB. The frequency domain extraction means 9 includes a frequency distribution 401 and a frequency distribution 402 of a reference waveform.
The frequency region 406 is extracted as a region that includes both local maxima and does not fall to the noise level, for example, a range that is 10 dB lower than the local maxima of the frequency distributions 401 and 402. In the frequency domain 406, the frequency distribution 401
And the frequency distribution 40 of the reference waveform
The frequency fc2 of the maximum value of 2 is obtained. Maximum frequency f
The difference (fc1-fc2) between c1 and fc2 is determined and used as an index of the bone properties.

Further, another index relating to the properties of the bone can be obtained as follows. First, the frequency analysis unit 5 performs a Fourier transform on the waveform extracted by the waveform extraction unit 8 to obtain a frequency distribution 401. The frequency distribution is obtained in units of dB, and the maximum value is normalized as 0 dB. The frequency domain extraction means 9 determines a region where both the frequency distribution 401 and the frequency distribution 402 of the reference waveform do not fall to the noise level, for example, the frequency distributions 401 and 402.
A frequency region 403 that overlaps in a range that is 10 dB lower than the maximum value of is extracted. Next, the extracted frequency domain 403
In, the components of the measurement system are removed by subtracting the frequency distribution 402 of the reference waveform from the frequency distribution 401 to obtain the frequency distribution 404. The attenuation index calculating means 11 is provided. A straight line 405 approximating the frequency distribution 404 is obtained by the least squares method, and the inclination of the straight line is used as an index of the bone property. The index determined in this way does not exactly match the frequency-dependent attenuation of the subject, but reflects the frequency-dependent attenuation of the bone. As the reference waveform, the measuring apparatus uses a received signal measured by transmitting only water under the same and same conditions.

In the above description, as a method of extracting a transmitted signal, the zero cross point appearing next to the maximum value of the transmitted signal is set as the time at the rear end of the extracted waveform. The transmission signal may be extracted by multiplying the transmission signal by the cosine window by matching the points that take the maximum value of the cosine window.

In the above description, the difference in the frequency distribution between the received signal and the reference signal of the subject is calculated for calculating the index of the bone property, and the gradient is used as the index. However, the attenuation of the bone is proportional to the frequency. Frequency distributions 401 and 402
The coefficient of the frequency-dependent attenuation that minimizes the difference between the frequencies of the local maximum values may be obtained by the least square method.

As described above, according to the first embodiment of the present invention, the bone index calculating means 4 provides the waveform extracting means 8 for extracting the portion transmitted through the shortest path from the received signal through the subject, By providing frequency analysis means 9 for calculating a frequency distribution, frequency domain extraction means 10 for extracting a frequency distribution area based on the shape of the frequency distribution, and attenuation index calculation means 11 for calculating an index relating to attenuation of a received signal, By extracting, from the received signal, a portion where the component transmitted through the shortest path in the subject greatly contributes, it is possible to obtain an index relating to the attenuation largely contributed by the bone component.

(Embodiment 2) FIG. 5 shows the configuration of an ultrasonic bone measuring apparatus according to Embodiment 2 of the present invention. Reference numeral 12 denotes a bone index calculating means 4 for calculating the group delay and speed of a received signal. The other components are the same as those of the first embodiment.

The operation of the ultrasonic bone measuring apparatus configured as described above will be described. First, the transmission / reception circuit 3
Drives the ultrasonic converter 1 to emit a sound wave. The sound wave emitted by the ultrasonic wave conversion means 1 propagates through the propagation medium 7 and enters the subject 6. The sound wave incident on the subject 6 is divided into a component mainly reflected on the skin surface and the bone surface, and a component mainly transmitted through the subcutaneous tissue and the bone.
The signals are received by the ultrasonic converters 1 and 2, respectively. The transmitted wave received by the ultrasonic wave converting means 2 is transmitted to the transmitting / receiving circuit 3
After being amplified by and converted into digital data, it is sent to the bone index calculating means 4. In the bone index calculating means 4, first, a portion transmitted through the shortest path in the subject is extracted from the received signal by the waveform extracting means 8 in the same manner as in the first embodiment. The frequency analysis means 9 calculates a frequency distribution of the extracted received signal. The frequency distribution obtained by the frequency analysis means 9 is extracted by the frequency domain extraction means 10 to include a frequency having a maximum in the amplitude frequency distribution, and to extract a frequency domain which is less affected by noise. The group delay amount calculating unit 12 calculates the group delay amount and the speed from the frequency distribution of the phase in the region extracted by the frequency region extracting unit 10. The display means 5 displays the speed obtained by the bone index calculation means 4. The extraction of the waveform by the waveform extracting means 8 and the extraction of the frequency distribution by the frequency domain extracting means 9 are performed in the same manner as in the first embodiment.

Next, the method of calculating the group delay amount and the speed in the second embodiment will be described in more detail with reference to FIG. FIG. 6 shows the frequency distribution of the extracted phase. FIG. 6A shows the transmission waveform of the subject 6 generated by the waveform extracting unit 8, FIG. 6B shows the reference waveform generated by the waveform extracting unit 8, and FIG. c) is the frequency distribution of the phase change of the extracted transmitted signal, (d) is the frequency distribution of the phase change of the extracted reference signal, (e) is the frequency distribution of the phase change of the corrected transmitted signal, (f). Is the frequency distribution of the phase change of the corrected reference signal, and (g) is the frequency distribution representing the phase change of the difference between the transmitted signal and the reference signal. 601 is a frequency distribution of the extracted and corrected phase, and 602 is a frequency distribution 60
1, 603 is a part extracted from the transmission waveform of the subject, and 604 is a part extracted from the transmission waveform of the reference medium.

First, zero is added to the waveform extracted by the waveform extracting means 8 using the same method as in the first embodiment, from the transmission start time to the beginning of the extracted waveform, and the transmission waveform is extracted from the transmission start time. A waveform having a length up to the time at the trailing end is generated. The transmission waveform and the reference waveform of the subject 6 generated by the waveform extracting means 8 are, for example, as shown in FIGS. 6A and 6B, and the areas represented by 603 and 604 are different from the actual measurement waveform. The extracted part, and the other parts are 0 parts. The frequency analysis means 5 performs a Fourier transform on the waveform to obtain a phase frequency distribution. The frequency domain extraction means 10 obtains the frequency distribution of the phase change, and FIGS. 6C and 6D by the same method as in the first embodiment. The frequency distribution of the phase change can be obtained in a range of -pi to pi in units of radians with pi being the pi. The group delay amount calculating means 12 corrects this phase change so as to change linearly at a discontinuous change near −pi or pi, for example, at a point where −pi changes to pi, and changes the frequency distribution of the corrected phase change. Find (e) and (f). Next, a frequency distribution 601 representing a difference in phase change between the transmitted signal and the reference signal is obtained. The group delay amount calculation means 12 assumes that the phase linearly changes in accordance with the frequency in the extracted frequency domain, and approximates a straight line 602 to the frequency distribution 601 by the least square method. Assuming that the difference between the group delay amounts of the subject 6 and the propagation medium 7 is dt, dt can be obtained from the slope of the approximated straight line 602. Further, the thickness L of the object pi is obtained by another method, for example, by actual measurement using a ruler or by measuring the delay time of the reflected signal of the ultrasonic wave from the surface of the object pi.
The group velocity of a signal passing through is obtained. v = 1 / (dt / L + 1 / vw) (3) (v: group velocity of the subject pi, dt: difference in group delay time between the subject pi and the propagation medium, vw: velocity of the propagation medium, L: thickness of subject pi)

In the above description, the amount of group delay was determined from the phase change of the difference between the transmitted signal and the reference signal as an index of the bone properties, but only the phase change of the transmitted signal was approximated by a straight line to obtain the bone delay. An index of the property may be obtained.

In the above description, the thickness of the subject pi is used to determine the group velocity. However, the thickness of the bone is determined by measuring the delay time of the ultrasonic reflected signal from the bone surface. May be used.

As described above, according to the second embodiment of the present invention, the bone index calculating means 4 includes the waveform extracting means 8 for extracting a portion transmitted through the shortest path in the subject from the received signal, A frequency analysis unit for calculating a frequency distribution; a frequency domain extraction unit for extracting a frequency distribution region based on a shape of the frequency distribution; and a group delay amount calculation unit for calculating a group delay and a speed of a received signal. By extracting from the received signal a portion to which the component transmitted through the shortest path in the subject greatly contributes, it is possible to obtain an index relating to the speed at which the bone component greatly contributed.

[0033]

As described above, according to the present invention, there is provided a waveform extracting means for extracting a portion transmitted through a shortest path in a subject from a received signal, and a frequency for calculating a frequency distribution of the received signal extracted by the waveform extracting means. By providing the analyzing means and the frequency domain extracting means for extracting the frequency distribution area based on the shape of the frequency distribution, it is possible to extract from the received signal a portion to which the component transmitted through the shortest path in the subject greatly contributes. The effect is obtained.

Further, as described above, according to the present invention, with respect to the transmission waveforms of the subject and the reference medium, the maximum frequency in the frequency distribution of the amplitude is determined, and the index of the bone attenuation characteristic is calculated based on the frequency shift between the two. By providing the attenuation calculating means, the portion where the component transmitted through the shortest path in the subject greatly contributes from the received signal is extracted, so that an index relating to the attenuation greatly contributed by the bone component can be obtained. Is obtained.

As described above, according to the present invention, by providing the group delay amount calculating means for obtaining the group delay amount from the phase frequency distribution, the component transmitted from the received signal through the subject through the shortest path greatly contributes. By extracting the portion, it is possible to obtain an effect that an index relating to the speed to which the bone component has greatly contributed can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an ultrasonic bone measurement device according to a first embodiment of the present invention.

FIG. 2A is a waveform diagram illustrating a received waveform according to the first embodiment of the present invention; FIG. 2B is a waveform diagram illustrating an extracted waveform according to the first embodiment of the present invention;

FIG. 3 is a waveform chart showing a difference in a transmission waveform due to a frequency attenuation of a bone according to the first embodiment of the present invention.

FIG. 4 (a) is a transmission waveform diagram of an extracted subject according to the first embodiment of the present invention; FIG. 4 (b) is an extracted reference waveform diagram according to the first embodiment of the present invention; (D) is an extracted frequency distribution diagram according to the first embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of an ultrasonic bone measurement device according to a second embodiment of the present invention.

6A is a transmission waveform diagram of a subject generated by a waveform extracting unit according to the second embodiment of the present invention; FIG. 6B is a reference waveform generated by the waveform extracting unit according to the second embodiment of the present invention; (C) is a frequency distribution diagram of the phase change of the extracted transmitted signal in the second embodiment of the present invention. (D) is a frequency distribution diagram of the phase change of the extracted reference signal in the second embodiment of the present invention. e) is a frequency distribution diagram of the phase change of the corrected transmitted signal according to the second embodiment of the present invention. (f) is a frequency distribution diagram of the phase change of the extracted reference signal according to the second embodiment of the present invention. Is a frequency distribution diagram showing a phase change of a difference between a transmitted signal and a reference signal according to Embodiment 2 of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional ultrasonic bone measuring device.

[Explanation of symbols]

 1, 2 ultrasonic conversion means 3 transmission / reception circuit 4 bone index calculation means 5 display means 6 subject 7 propagation medium 8 waveform extraction means 9 frequency analysis means 10 frequency domain extraction means 11 attenuation index calculation means 12 group delay amount calculation means 15 propagation Time measuring means 16 Attenuation measuring means 21 Time when the maximum amplitude of the received waveform is reached 22 First zero-cross point appearing after the maximum amplitude 23 Range for extracting the received signal 401 Frequency distribution of the extracted transmitted waveform 402 Frequency distribution of the reference signal 403 Extraction Frequency domain 404 from which the components of the measurement system are removed 405 frequency distribution 405 a straight line approximating the frequency distribution 404 406 extracted frequency domain 601 frequency distribution of the extracted and corrected phase 602 straight line approximating the frequency distribution 601

Claims (3)

[Claims] 1. An ultrasonic wave converting means for converting an ultrasonic wave into an electric signal, an ultrasonic wave transmitting / receiving means for driving the ultrasonic wave converting means, and a portion transmitted through a shortest path in a subject from a received signal is extracted. An ultrasonic wave comprising: a waveform extracting unit; a frequency analyzing unit that calculates a frequency distribution of a received signal extracted by the waveform extracting unit; and a frequency domain extracting unit that extracts a frequency distribution region based on a shape of the frequency distribution. Bone measurement device. 2. An attenuation index calculating means for determining a maximum frequency in an amplitude frequency distribution for a transmission waveform of a subject and a reference medium, and calculating an index of a bone attenuation characteristic based on a frequency shift between the two. The ultrasonic bone measuring apparatus according to claim 1, wherein: 3. The ultrasonic bone measuring apparatus according to claim 1, further comprising a group delay amount calculating means for obtaining a group delay amount from a phase frequency distribution.