JP3830650B2 - Ultrasonic bone measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic bone measuring apparatus that calculates an index related to bone properties from a transmitted or reflected signal by causing ultrasonic waves to enter the body.
[0002]
[Prior art]
Conventionally, an ultrasonic bone measuring apparatus described in Japanese Patent Laid-Open No. 6-327664 is known. FIG. 7 shows the configuration of a conventional ultrasonic bone measuring apparatus. Reference numerals 1 and 2 denote ultrasonic conversion means for performing mutual conversion between ultrasonic waves and electrical signals, 3 denotes a transmission / reception circuit for driving the ultrasonic conversion means, and 5 denotes Display means for displaying the 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. A propagation time measuring means 16 is an attenuation measuring means for measuring attenuation characteristics.
[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 conversion means 1 to emit sound waves. The sound wave radiated 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 mainly divided into a component reflected on the skin surface and the bone surface and a component transmitted mainly through the subcutaneous tissue and the bone, and is received by the ultrasonic conversion means 1 and 2, respectively. The transmission component received by the ultrasonic wave conversion means 2 is amplified by the transmission / reception circuit 3 and converted into digital data, and then sent to the propagation time measurement means 15 and the attenuation measurement means 16. The propagation time measuring means 15 obtains the time when the amplitude of the transmitted signal takes the maximum value, and obtains the ultrasonic propagation time dt as the difference between the time and the time of ultrasonic radiation of the ultrasonic conversion means 1. In addition, the propagation time measuring means 15 receives the sound waves emitted from the ultrasonic transducers 1 and 2 separately from the measurement of the transmission component of the subject 6 in order to obtain the time for the sound waves to propagate through the propagation medium 7. Times of reflection on the sample surface and returning to the ultrasonic transducers 1 and 2 are measured. By subtracting the time of transmission through the propagation medium 7 from the time dt of transmission through the subject 6 and the propagation medium 7, the time dt of transmission through only the subject 6 is obtained. Further, the thickness L of the subject 6 is measured, and the propagation velocity v of the sound wave in the subject 6 is calculated by dividing the thickness L of the subject 6 by the propagation time dt as shown in the following equation (1). To do.
v = dt ′ / L (1)
[0004]
The attenuation measuring means 16 measures the frequency distribution of the transmission component of the reference medium, and obtains the difference in amplitude at the same frequency from two points from the frequency distribution of the transmission component of the subject 6 and the reference medium. Assuming that the difference in amplitude of the transmitted component between the subject 6 and the reference medium at the two frequencies f1, f2 and f1, f2 is A1, A2, a frequency-dependent attenuation coefficient A is obtained by the following equation (2).
A = (A1-A2) / (f1-f2) (2)
However, in calculating equation (1), A1 and A2 are determined in dB units. Also, 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 indicating the bone properties.
[0005]
[Problems to be solved by the invention]
However, in the conventional ultrasonic bone measuring apparatus, the subject transmission signal used to calculate the index representing the bone characteristics is transmitted through the bone and transmitted from the transmission-side ultrasonic transducer to the reception-side ultrasonic wave. There is a problem in that it may be difficult to obtain only bone information because a signal component propagated through a path other than directly reaching the converter is included.
[0006]
The present invention solves the above-mentioned conventional problem, by utilizing a part that the signal component that directly penetrates the bone and reaches directly from the transmission-side ultrasonic transducer to the reception-side ultrasonic transducer greatly contributes, It is an object of the present invention to provide an excellent ultrasonic bone measuring apparatus capable of obtaining an index greatly contributed by bone information.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a waveform extracting means for extracting a portion that has passed through a subject through a shortest path from a received signal, and a frequency analyzing means for calculating a frequency distribution of the received signal extracted by the waveform extracting means. And frequency domain extraction means for extracting a frequency distribution area based on the shape of the frequency distribution, and the frequency distribution of the portion to which the component transmitted through the subject through the shortest path greatly contributes from the received signal can be obtained. It is what I did.
[0008]
In order to solve the above problems, the present invention obtains the maximum frequency in the amplitude frequency distribution for the transmission waveform of the subject and the reference medium, and calculates an index of the bone attenuation characteristic by the frequency deviation between the two. An attenuation calculation means is provided, and an index relating to bone attenuation can be obtained from a frequency shift.
[0009]
Further, in order to solve the above problem, the present invention includes a group delay amount calculation means for obtaining a group delay amount from the phase frequency distribution, and obtains an index relating to the bone propagation velocity by calculating the group delay time or the group velocity. It is something that can be done.
[0010]
As described above, in order to calculate an index that represents the characteristics of the bone, using the part that the signal component that directly penetrates the bone and directly reaches the receiving-side ultrasonic transducer from the transmitting-side ultrasonic transducer contributes greatly. It is possible to obtain an excellent ultrasonic bone measuring device that it is easy to obtain an index greatly contributed by bone information.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, the ultrasonic transducer means for converting ultrasonic electrical signals, the ultrasonic transmitting and receiving means for driving the ultrasonic transducer means, the subject of the received signal shortest extracting a waveform extracting means for extracting a transmitted portion in the path, a frequency analysis means for calculating a frequency distribution of the received signal extracted by the waveform extracting means, the area of the frequency distribution based on the shape of the frequency distribution A frequency domain extracting means , wherein the waveform extracting means is characterized in that a point at which the signal becomes zero immediately after the maximum peak of the transmission signal is set as a rear end of the extraction , By extracting the portion to which the component transmitted through the shortest path greatly contributes , it is possible to obtain an index relating to attenuation to which the bone component has greatly contributed .
[0014]
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
(Embodiment 1)
FIG. 1 shows the configuration of an ultrasonic bone measuring apparatus according to Embodiment 1, wherein 1 and 2 are ultrasonic conversion means for performing mutual conversion between ultrasonic waves and electrical signals, and 3 is a transmission / reception circuit for driving the ultrasonic conversion means. 4 is a bone index calculating means for calculating a bone property index in the subject, 5 is a display means for displaying the analysis result, 6 is a subject including a bone to be measured, and 7 is a medium for propagation of ultrasonic waves. It is a propagation medium. In the bone index calculating means 4, 8 is a waveform extracting means for extracting a portion that has passed through the subject through the shortest path from the received signal, 9 is a frequency analyzing means for calculating the frequency distribution of the received signal, and 10 is the shape of the frequency distribution. The frequency domain extracting means 11 extracts a frequency distribution area based on the above, and 11 is an attenuation index calculating means for calculating an index relating to attenuation of the received signal. The ultrasonic conversion means 1 and 2 shall use the thing of the same performance. In the first embodiment, the ultrasonic wave conversion means 1 receives the ultrasonic wave radiation and the reflected wave from the subject 6, and the ultrasonic wave conversion means 2 receives the transmitted wave of the subject 6. Shall. For the subject 6, a heel having a bone tissue ratio larger than a subcutaneous tissue ratio in the propagation path when sound waves are transmitted is used, and water is usually used as the propagation medium 7.
[0015]
The operation of the ultrasonic bone measuring apparatus configured as described above will be described. First, the transmission / reception circuit 3 drives the ultrasonic conversion means 1 to emit sound waves. The sound wave radiated 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 is divided into a component reflected mainly on the skin surface and the bone surface and a component transmitted mainly through the subcutaneous tissue and the bone, and is received by the ultrasonic conversion means 1 and 2, respectively. The transmitted wave received by the ultrasonic wave conversion means 2 is amplified by the transmission / reception circuit 3 and converted into digital data, and then sent to the bone index calculation means 4. In the bone index calculating means 4, first, a signal component having a long arrival time by the waveform extracting means 8, for example, a multiple reflection component in the propagation medium 7 and the inside of the subject 9, or a shortest path between the ultrasonic transducers 1 and 2 as a longitudinal wave. The component that has not propagated in step 1 is removed, and the portion of the received signal that has passed through the subject through the shortest path is extracted. The frequency analysis means 9 calculates the frequency distribution of the extracted received signal. The frequency distribution obtained by the frequency analyzing unit 9 includes a frequency that is maximized in the frequency distribution of the amplitude by the frequency region extracting unit 10 and extracts a frequency region that is less affected by noise. The attenuation index calculation unit 11 calculates an index related to the bone property attenuation from the frequency distribution of the region extracted by the frequency region extraction unit 10. The display means 5 displays the index obtained by the bone index calculation means 4.
[0016]
Next, the operation of 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 how waveforms are extracted. FIG. 2A shows a received waveform, and FIG. 2B shows an extracted waveform. Further, 20 is a received signal that has passed through the subject, 21 is the time when the received waveform has the maximum amplitude, 22 is the first zero cross point that appears after the maximum amplitude, and 23 is the range from which the received signal is extracted.
[0017]
Among the sound waves radiated from the ultrasound conversion means 1 and incident on the subject 6, the components that have passed through the bone in the subject 6 and reached the ultrasound conversion means 2 directly reach the ultrasound transducer 2 through the shortest path. To be received at an early time. Since it is difficult to obtain bone information other than the component transmitted through the shortest path, a signal component having a long arrival time, such as a component propagated through another path, among the waveforms received by the ultrasonic probe 2 or The characteristic of bone is analyzed by removing the multiple reflection component and extracting the component that has passed through the shortest path that arrived early. However, it is difficult to extract all the components that have been transmitted through the shortest path because the components that have been transmitted through the shortest path overlap with other components or the duration of the signal varies depending on the measurement environment or individual differences in the subject. . Therefore, an area that seems to reflect the characteristics of the bone most significantly is extracted as follows to obtain an index.
[0018]
First, the leading time to be extracted is set to the earliest possible time as long as the leading part of the transmission component is equal to or higher than the noise level and no other waveform exists. The rear end obtains a time 21 at which the maximum amplitude of the received waveform is obtained, obtains an intersection with the first zero level after that time, that is, a zero cross point 22, and serves as the rear end of the extracted waveform. The waveform is extracted from the received signal within the above range 23 to obtain a waveform as shown in FIG. The same operation is performed on a reference signal that is a received signal that has passed through only water. In the above description, a signal is extracted by a rectangular window, but a cosine window represented by a Hanning window may be used.
[0019]
Next, 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 showing a difference in transmission waveform due to bone frequency attenuation. FIGS. 4A and 4B are diagrams showing a state in which an index of bone attenuation characteristics is calculated. FIG. 4A shows a transmission waveform of the subject extracted by the waveform extracting unit 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. In addition, 401 is the frequency distribution of the extracted transmission waveform, 402 is the frequency distribution of the reference signal, 403 is the extracted frequency region, 404 is the frequency distribution from which the components of the measurement system are removed, and 405 is a straight line approximating the frequency distribution 404. It is.
[0020]
The component transmitted through the shortest path is transmitted through various media such as the subcutaneous tissue and the propagation medium in addition to the bone, and thus is affected by the effects other than the bone. By the way, the change in attenuation with respect to frequency, that is, frequency attenuation, is less than the frequency dependent attenuation of water and skin compared with bone at the ultrasonic frequency of several hundred kHz to several MHz used for calculating the index. If an index related to frequency-dependent attenuation is obtained, the index can reflect the bone properties. The magnitude of the frequency-dependent attenuation is noticeable in the received signal at the leading edge of the received signal. Assuming that the bone attenuation increases linearly in proportion to the frequency, as the frequency-dependent attenuation increases as shown in FIG. 3, the low-frequency component appears at the leading portion and the zero cross interval w1 increases, and the smaller the frequency, the more used the measurement. The interval w1 decreases as it approaches the center frequency of the ultrasonic wave. In order to obtain the index in the simplest manner, the zero-cross interval w1 may be measured. However, it is difficult to obtain the index accurately because the rise may be slow or the rise 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 bone property is calculated from the displacement of the center frequency.
[0021]
First, the frequency analysis means 5 performs a Fourier transform on the waveform extracted by the waveform extraction means 8 to obtain a frequency distribution 401. The frequency distribution is obtained with dB as a unit, and is normalized with the maximum value being 0 dB. The frequency domain extracting means 9 includes the maximum values of both the frequency distribution 401 and the frequency distribution 402 of the reference waveform, and the frequency does not fall to the noise level, for example, a range that is 10 dB lower than the maximum values of the frequency distributions 401 and 402. A region 406 is extracted. In the frequency region 406, a maximum value frequency fc1 of the frequency distribution 401 and a maximum value frequency fc2 of the frequency distribution 402 of the reference waveform are obtained. The difference (fc1-fc2) between the maximum frequencies fc1 and fc2 is obtained and used as an index of bone properties.
[0022]
Further, as another index relating to the properties of bone, it can also be obtained as follows. First, the frequency analysis unit 5 performs Fourier transform on the waveform extracted by the waveform extraction unit 8 to obtain a frequency distribution 401. The frequency distribution is obtained with dB as a unit, and is normalized with the maximum value being 0 dB. The frequency domain extracting unit 9 extracts a frequency domain 403 that overlaps in a range where both the frequency distribution 401 and the frequency distribution 402 of the reference waveform do not fall to the noise level, for example, a range 10 dB lower than the maximum value of the frequency distributions 401 and 402. To do. Next, in the extracted frequency region 403, the frequency distribution 404 is obtained by subtracting the frequency distribution 402 of the reference waveform from the frequency distribution 401 to remove the components of the measurement system. The attenuation index calculation means 11 is. A straight line 405 that approximates the frequency distribution 404 is obtained by the method of least squares, and the slope of the straight line is used as an index of bone properties. The index obtained in this way does not exactly match the frequency-dependent attenuation of the subject, but reflects the frequency-dependent attenuation of the bone. As a reference waveform, the measurement apparatus uses a reception signal measured by transmitting only water under the same and the same conditions.
[0023]
In the above description, as a method of extracting the transmission signal, the zero cross point that appears next to the maximum value of the transmission signal is set as the time at the rear end of the extraction waveform. The transmission signal may be extracted by matching the points having the maximum values and multiplying the transmission signal by a cosine window.
[0024]
In the above description, the difference in frequency distribution between the received signal of the subject and the reference signal is obtained in calculating the bone property index, and the gradient is used as an index. However, the bone attenuation increases in proportion to the frequency. As a result, a frequency-dependent attenuation coefficient that minimizes the frequency difference between the maximum values of the frequency distributions 401 and 402 may be obtained by the method of least squares.
[0025]
As described above, according to the first embodiment of the present invention, the bone index calculating unit 4 extracts the waveform extraction unit 8 that extracts the portion that has passed through the subject from the received signal through the shortest path, and the frequency distribution of the received signal. By providing a frequency analyzing means 9 for calculating, a frequency domain extracting means 10 for extracting a frequency distribution area based on the shape of the frequency distribution, and an attenuation index calculating means 11 for calculating an index relating to the attenuation of the received signal, the received signal can be obtained. By extracting a portion where the component transmitted through the subject through the shortest path greatly contributes, it is possible to obtain an index relating to attenuation greatly contributed by the bone component.
[0026]
(Embodiment 2)
FIG. 5 shows the configuration of the ultrasonic bone measuring apparatus according to the second embodiment. Reference numeral 12 denotes a bone index calculating unit 4 which is a group delay amount calculating unit for calculating a group delay and a speed of a received signal. These components are the same as those in the first embodiment.
[0027]
The operation of the ultrasonic bone measuring apparatus configured as described above will be described. First, the transmission / reception circuit 3 drives the ultrasonic conversion means 1 to emit sound waves. The sound wave radiated 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 mainly divided into a component reflected on the skin surface and the bone surface and a component transmitted mainly through the subcutaneous tissue and the bone, and is received by the ultrasonic conversion means 1 and 2, respectively. The transmitted wave received by the ultrasonic wave conversion means 2 is amplified by the transmission / reception circuit 3 and converted into digital data, and then sent to the bone index calculation means 4. In the bone index calculation means 4, first, the waveform extraction means 8 extracts the portion that has passed through the subject through the shortest path from the received signal by the same method as in the first embodiment. The frequency analysis means 9 calculates the frequency distribution of the extracted received signal. The frequency distribution obtained by the frequency analysis means 9 includes a frequency that has a maximum in the frequency distribution of amplitude by the frequency domain extraction means 10 and extracts a frequency domain that is less affected by noise. The group delay amount calculation unit 12 calculates the group delay amount and the speed from the frequency distribution of the phase of the region extracted by the frequency region extraction unit 10. The display means 5 displays the speed obtained by the bone index calculation means 4. The waveform extraction by the waveform extraction unit 8 and the frequency distribution extraction by the frequency domain extraction unit 9 are performed by the same method as in the first embodiment.
[0028]
Next, the group delay amount and speed calculation method according to the second embodiment will be described in more detail with reference to FIG. 6 shows the frequency distribution of the extracted phase, FIG. 6A shows the transmission waveform of the subject 6 generated by the waveform extraction means 8, FIG. 6B shows the reference waveform generated by the waveform extraction means 8, c) is the frequency distribution of the phase change of the extracted transmission 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 transmission signal, and (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. Reference numeral 601 denotes a frequency distribution of the extracted and corrected phase, 602 denotes a straight line approximating the frequency distribution 601, 603 denotes a portion extracted from the transmission waveform of the subject, and 604 denotes a portion extracted from the transmission waveform of the reference medium.
[0029]
First, 0 of the length from the transmission start time to the beginning of the extracted waveform is added to the waveform extracted by the waveform extraction means 8 using the same method as in the first embodiment, and the trailing end of the extracted waveform from the transmission start time. A waveform having a length up to the time is generated. The transmission waveform and the reference waveform of the subject 6 generated by the waveform extracting means 8 are as shown in FIGS. 6A and 6B, for example, and the regions represented by 603 and 604 are obtained from the actual measurement waveform. The extracted part and the other parts are set to 0. The frequency analysis means 5 performs a Fourier transform on the waveform to obtain a frequency distribution of the phase. The frequency domain extraction means 10 obtains the frequency distribution of phase change, FIGS. 6C and 6D, by the same method as in the first embodiment. The frequency distribution of the phase change is obtained in the range of -pi to pi with pi as the circumference and radians as the unit. The group delay amount calculating means 12 corrects this phase change so as to change linearly at a point where -pi or pi is discontinuous, for example, from -pi to pi, and the frequency distribution of the corrected phase change (E) and (f) are obtained. Next, a frequency distribution 601 representing the difference in phase change between the transmission signal and the reference signal is obtained. The group delay amount calculation means 12 assumes that the phase linearly changes according to the frequency within the extracted frequency domain, and approximates the straight line 602 to the frequency distribution 601 by the least square method. If the difference in the group delay between the subject 6 and the propagation medium 7 is dt, dt can be obtained from the slope of the approximate straight line 602. Further, the thickness L of the subject pi is obtained by another method, for example, measurement by a ruler or measurement of the delay time of the reflected signal of the ultrasonic wave from the surface of the subject pi, so that the subject 6 is transmitted by the following equation (3). The group velocity of the signal to be obtained can be obtained.
v = 1 / (dt / L + 1 / vw) (3)
(V: group velocity of subject pi, dt: difference in group delay time of subject pi from propagation medium, vw: velocity of propagation medium, L: thickness of subject pi)
[0030]
In the above description, the group delay amount is obtained from the phase change of the difference between the transmission signal and the reference signal as an index of the bone property. However, the bone property index is obtained by approximating only the phase change of the transmission signal with a straight line. You may ask for.
[0031]
In the above description, the thickness of the subject pi is used to obtain the group velocity. However, the bone thickness is obtained by measuring the delay time of the reflected signal from the bone surface of the ultrasonic wave and used. Also good.
[0032]
As described above, according to the second embodiment of the present invention, the bone index calculating unit 4 extracts the waveform extracting unit 8 that extracts the portion that has passed through the subject from the received signal through the shortest path, and the frequency distribution of the received signal. By providing the frequency analysis means 9 for calculating, the frequency domain extracting means 10 for extracting the frequency distribution area based on the shape of the frequency distribution, and the group delay amount calculating means 12 for calculating the group delay and speed of the received signal, reception is achieved. By extracting a portion where the component transmitted through the subject through the shortest path greatly contributes from the signal, it is possible to obtain an index related to the velocity greatly contributed by the bone component.
[0033]
【The invention's effect】
As described above, according to the present invention, ultrasonic conversion means for converting ultrasonic waves and electrical signals, ultrasonic transmission / reception means for driving the ultrasonic conversion means, and transmission from the received signal through the subject through the shortest path. a waveform extracting means for extracting a portion, and frequency analysis means for calculating a frequency distribution of the received signal extracted by the waveform extraction means, the frequency region extracting means for extracting a region of the frequency distribution based on the shape of the frequency distribution The waveform extraction means is characterized in that a point at which the signal becomes zero immediately after the maximum peak of the transmission signal is set as a rear end of the extraction, and from the received signal through the subject through the shortest path. By extracting a portion to which the transmitted component greatly contributes , an effect of obtaining an index relating to attenuation greatly contributed by the bone component can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of an ultrasonic bone measuring apparatus according to Embodiment 1 of the present invention. FIG. 2 (a) is a waveform diagram showing a received waveform according to Embodiment 1 of the present invention. FIG. 3 is a waveform diagram showing the extracted waveform in the first embodiment of the invention. FIG. 3 is a waveform diagram showing a difference in transmission waveform due to bone frequency attenuation in the first embodiment of the invention. The transmission waveform diagram (b) of the extracted subject in the first embodiment is the reference waveform diagram (c) extracted in the first embodiment of the present invention, and the frequency distribution diagram of the amplitude in the first embodiment of the present invention FIG. 5D is a frequency distribution diagram extracted in the first embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of the ultrasonic bone measuring apparatus in the second embodiment of the present invention. Generated by the waveform extracting means in the second embodiment of the invention. The transmission waveform diagram (b) of the subject is the reference waveform diagram (c) generated by the waveform extracting means in the second embodiment of the present invention, and the phase change frequency of the extracted transmission signal in the second embodiment of the present invention. The distribution diagram (d) is the frequency distribution diagram of the phase change of the extracted reference signal in the second embodiment of the present invention, and (e) is the frequency distribution diagram of the phase change of the corrected transmission signal in the second embodiment of the present invention. (F) is a frequency distribution diagram of the phase change of the extracted reference signal in Embodiment 2 of the present invention, and (g) represents the phase change of the difference between the transmitted signal and the reference signal in Embodiment 2 of the present invention. Frequency distribution diagram [Fig. 7] Block diagram showing the configuration of a conventional ultrasonic bone measuring device [Explanation of symbols]
DESCRIPTION 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 measurement means 16 Attenuation measurement means 21 Time 22 that is the maximum amplitude of the received waveform First zero cross point 23 that appears after the maximum amplitude Range that the received signal is extracted 401 Frequency distribution of the extracted transmitted waveform 402 Frequency distribution 403 of the reference signal Extraction The frequency distribution 404 obtained by removing the components of the measurement system 405 The straight line 406 approximating the frequency distribution 404 The extracted frequency domain 601 The frequency distribution 602 of the extracted and corrected phase The straight line approximating the frequency distribution 601

Claims (1)

  Ultrasonic wave conversion means for converting ultrasonic waves and electrical signals; ultrasonic wave transmission / reception means for driving the ultrasonic wave conversion means; and waveform extraction means for extracting a portion that has passed through the subject through the shortest path from the received signal; A frequency analysis unit that calculates a frequency distribution of the received signal extracted by the waveform extraction unit; and a frequency domain extraction unit that extracts a region of the frequency distribution based on a shape of the frequency distribution, the waveform extraction unit Then, an ultrasonic bone measuring apparatus characterized in that a point at which the signal becomes zero immediately after the maximum peak of the transmission signal is set as a rear end of the extraction.

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