JP4521584B2 - Sonic velocity measuring method using ultrasonic microscope, sonic velocity measuring device, sonic velocity image acquiring method using ultrasonic microscope, and diagnostic imaging device thereof - Google Patents

Description

The present invention relates to a sound velocity measuring method using an ultrasonic microscope, a sound velocity measuring device thereof, a sound velocity image acquiring method using an ultrasonic microscope, and an image diagnostic device thereof. Specifically, when measuring the speed of sound of an object to be measured such as a living tissue using a wide-band pulse excitation type ultrasonic microscope, the mechanical tilt of the sample mounting plate directly facing the ultrasonic transducer Correcting the amount by signal processing eliminates the need for mechanical pre-adjustment with respect to the amount of inclination of the sample mounting plate, greatly shortening the measurement time and eliminating the effect of measurement errors due to mechanical adjustment errors It is a thing.

  Furthermore, when acquiring the properties of biological tissue as a sonic image, the mechanical tilt amount of the sample mounting plate is electrically corrected, thereby reducing the processing time of the sonic image and producing a highly accurate sonic image. It is intended to be obtained.

  A technique for observing the surface state of a sample using an ultrasonic microscope and measuring the speed of sound has been known (for example, Non-Patent Document 1).

  On the other hand, this ultrasonic microscope has been applied to the observation and diagnosis of living tissue. For example, when a malignant tumor is excised, biological tissue diagnosis is performed in which the tissue at the excision site is removed or the biological tissue near the excision site is excised and observed.

  Conventionally, an optical microscope has been used as a diagnostic apparatus (observation apparatus) used for this biological tissue diagnosis. In this state, the excised surface is observed with an optical microscope in a state where the extracted living tissue is stained. However, in order to perform complete staining, it is necessary to wait for one day or more. Later.

  In addition, an intraoperative rapid diagnosis method has been developed so that observation can be performed during surgery even when staining is performed. In this case, in the case of normal staining, the tissue outline should be “colored by staining”. It has been reported that the tissue information is lost by intraoperative rapid diagnosis.

  For this reason, development of an intraoperative diagnostic method and an intraoperative diagnostic apparatus capable of diagnosing a living tissue extracted during surgery without using a conventional staining method is eagerly desired. In response to this demand, research and development of a diagnostic apparatus using an ultrasonic microscope has been conducted.

  An ultrasonic microscope is a method of diagnosing a living tissue by irradiating the living tissue with ultrasonic waves and observing the reflected wave intensity and phase while performing a calculation process and visualizing it (non-patent document). Reference 1).

  FIG. 7 is a conceptual diagram schematically showing this, and the ultrasonic microscope 1 has a wave transmitting / receiving unit 10. An ultrasonic transducer 11 is built in the wave transmitting / receiving unit 10 on the tip side. A preparation (sample mounting plate) 12 using a glass plate or the like is placed so as to face the transmission / reception unit 10, and an object to be measured (for example, a biological tissue section) 13 is placed on the preparation 12.

  Then, ultrasonic waves are applied to the surface of the object to be measured through the medium 17 such as water so as to target the object 13 to be measured. The ultrasonic wave emission surface 10a is curved as shown in the figure, and the ultrasonic wave reaches the surface of the object to be measured 13 in a state of being narrowed down into a beam shape. The resolution is determined by how the beam is narrowed down.

  In this example, a two-dimensional scanning unit 16 is provided so that the surface of the measurement target 13 can be two-dimensionally scanned, and the above-described preparation 12 is placed on the two-dimensional scanning unit 16. In the example of FIG. 7, a case where an XY stage is used as the two-dimensional scanning unit 16 is shown. The XY stage 16 includes an X stage 16X and a Y stage 16Y.

  Therefore, the plan view from the ultrasonic wave emission side is as shown in FIG. 8, and as shown in FIG. 9, the measurement is performed by performing reciprocal scanning in the x and x ′ directions (horizontal direction) and scanning in the y direction. The object 13 can be scanned two-dimensionally with ultrasonic waves.

  The acoustic microscope 1 is characterized by handling physical parameters that are easy to quantify such as propagation of sound waves. Specifically, the intensity and phase of the reflected wave (reflected wave signal) are handled as parameters. In order to observe the reflected wave as a visible image, the reflected ultrasonic wave signal (reference reflected wave signal) Sr irradiated on the surface of the preparation 12 and the surface of the object to be measured 13 are irradiated as shown in FIG. The reflected ultrasonic wave signal So is used.

  Here, the reflected wave signal So is an interference wave between the reflected wave signal Ss reflected from the surface of the DUT 13 and the reflected wave signal Sd reflected from the back side thereof, that is, the surface of the preparation 12.

  FIG. 11 shows respective waveforms when the ultrasonic transducer 11 is not excited with a burst signal as in the prior art, but is excited with a broadband pulse signal for convenience of explanation.

  FIG. 11A shows a waveform of an excitation pulse Si that excites the ultrasonic transducer 11. FIG. 12 shows the frequency characteristics of a pulse waveform of almost one cycle. In this example, an excitation pulse having a center frequency of about 80 MHz and a band of about 40 to 150 MHz is used. FIG. 11B shows the waveform of the reference reflected wave signal Sr obtained at that time. FIG. 11C shows the waveform of the interference reflected wave signal So in which the reflected wave signals Ss and Sd interfere.

  The interference reflected wave signal So shown in the figure is a waveform when a biological tissue section is used as the object 13 to be measured, and a reflected wave signal Su is obtained in addition to the waveform (Si ′) of the excitation pulse Si itself. Since the ultrasonic wave is repeatedly reflected between the ultrasonic transducer 11 and the object 13 to be measured, if the reflected wave signal obtained first is the primary reflected wave signal Su1, the reflected wave signal reaching several orders. Su2, Su3,... Are obtained.

  Here, in the ultrasonic microscope having such a configuration, the sound velocity of the object to be measured, which is a sample, is obtained using the intensity (reflected wave intensity) and phase of the obtained reflected wave signals Sr and So. . In order to increase the measurement accuracy at this time, it is desirable that the measurement method or the measurement apparatus be not affected by the inclination of the preparation 12. When the ultrasonic microscope 1 is used for image diagnosis of a living body, the object to be measured 13 is an extracted living tissue section.

  Image diagnosis will be described below. By evaluating the living tissue based on the intensity and phase of the reflected wave from the living tissue section, it is possible to evaluate the acoustic attenuation in the living tissue.

  As shown in Non-Patent Document 2, the diagnosis based on the acoustic microscope using the burst signal is mainly based on the evaluation based on the acoustic attenuation as described above. Therefore, the sound velocity of the living tissue has not been evaluated at all.

  It is known that when ultrasonic waves are irradiated into a living tissue, the ultrasonic waves have different sound speeds depending on the properties of the living tissue.

  In other words, there is a high correlation between living tissue and sound velocity, and the difference in physical properties between the case where the living tissue is a normal tissue and the case where the tissue is altered like a lesion, in other words, the living tissue. Differences in elasticity can be detected as differences in sound speed.

  In the case of using ultrasonic waves, it has been confirmed by various kinds of recent experiments that it can be “painted” as a difference in biological tissue from a difference in acoustic characteristics. Therefore, in order to perform a property diagnosis of a living tissue using ultrasonic waves, it is necessary to measure the acoustic characteristics of the living tissue at a micron level.

On the other hand, to enable intraoperative diagnosis,
(1) It is possible to quickly generate a visible image of an excised living tissue section (2) If possible, it is possible to carry a diagnostic device using an ultrasonic microscope into an operating room (3) For diagnosis It is necessary to clear various problems such as simple operation of the apparatus (4) being visible.

  Furthermore, considering a commercial base, it is also necessary to be able to provide it at a relatively low cost. This is because if the cost is too high, the burden on the apparatus installer is large, and a part of the burden is reduced to the medical cost burden on the patient.

  A diagnostic device using a conventional ultrasonic microscope uses a burst signal of a single frequency as an ultrasonic signal as described above, and analyzes the intensity and phase of the reflected ultrasonic signal, so that the properties of biological tissue can be determined. Observe.

  Using the reference reflected wave signal Sr directly reflected from the preparation 12 and the reflected wave signal So from the biological tissue section 13, the thickness d of the biological tissue section 13 and the sound speed of the biological tissue can be calculated. Details thereof will be described later.

  By the way, since it is difficult to shorten the duration of the burst signal applied to the ultrasonic transducer 11 rather than the time difference between the surface reflected wave signal Ss and the back surface reflected wave signal Sd described above, the surface reflected wave signal Ss and the back surface are usually used. It must be analyzed using the interference reflected wave signal So in which the reflected wave signal Sd interferes with each other.

  In order to eliminate the influence of interference, the burst signal frequency is sequentially changed so that the interference wave can be separated, and the intensity and phase spectrum of the reflected wave at that time are analyzed to calculate the thickness and sound speed of the living tissue. Yes.

  In the diagnostic apparatus using the ultrasonic microscope, which is under research and development at the laboratory level, the phase detection method using the burst signal is adopted as described above. Analyzing the intensity and phase spectrum of the reflected wave obtained as described above, calculating the thickness and speed of sound of the living tissue, and diagnosing the properties of the living tissue from the obtained acoustic characteristics, so a visible image It takes a very long time to process.

  For example, even when a 2 mm × 2 mm biological tissue section is measured as 100 × 100 pixels, it takes 10 minutes or more. Therefore, in order to increase the measurement accuracy up to about 300 × 300 pixels, it takes about 90 minutes of processing time, which is not sufficient as an intraoperative diagnostic apparatus for performing pathological judgment.

  The long measurement time further involves the scanning speed of the biological tissue section. In the conventional apparatus, a biological tissue section is placed on the XY stage 16 and is moved intermittently in the x and y directions to obtain a biological image of, for example, 100 × 100 pixels. Acquisition of a biological image by this intermittent scanning is a major factor that delays the measurement time. In addition, the slow signal processing speed for obtaining sound speed information by processing the reflected wave obtained from a slice of biological tissue is also a factor.

  As an image diagnostic apparatus using an ultrasonic microscope for solving such a problem, research on an image diagnostic apparatus using an ultrasonic microscope based on pulse excitation has recently been advanced.

  As described above, this is a method of exciting an ultrasonic transducer using a broadband pulse for approximately one cycle. By using this pulse excitation type ultrasonic microscope, the scanning speed in the x and y directions of the XY stage 16 is increased, and the signal processing system is further devised to irradiate the ultrasonic wave before final diagnostic images are obtained. It was confirmed that the time required for drawing as a visible image can be significantly reduced as compared with a conventional ultrasonic microscope using a burst signal.

  According to the experiments by the present applicants, it was found that even when an image of 300 × 300 pixels including the preparation 12 as a reference surface is drawn as shown in FIG. Of course, such a reduction in image processing time greatly contributes to the use of an ultrasonic beam that simultaneously converges and irradiates the ultrasonic wave, and the selection of the ultrasonic excitation frequency (approximately the center frequency) to about 80 MHz. Obviously.

  FIG. 14 shows an example of a biological tissue image (biological image) created using an ultrasonic microscope. The surface of the preparation 12 becomes the reference image 20 and the biological tissue section becomes the biological image 21. The biological image can be an attenuated image or a sound velocity image.

  Patent Documents 1 to 3 are known as pulse excitation type ultrasonic microscopes and ultrasonic treatment apparatuses.

  Patent Document 1 discloses an ultrasonic microscope provided with a switch circuit for blocking noise from a pulse amplifier. Therefore, the present invention is not directly related to the present invention.

  Patent Document 2 is a technique related to a pulse excitation type ultrasonic therapeutic apparatus, and particularly relates to a therapeutic apparatus in which the focal position of a pulse is not shifted, and is not directly related to the contents of the present invention.

  Patent Document 3 discloses a technique related to a three-dimensional ultrasonic microscope. This is a technique in which an object can be observed three-dimensionally by spherical ultrasonic waves, and the technique is different from that of the present invention which is intended for two-dimensional observation.

"Ultrasonic technology and its application: Latest results of ultrasonic microscope" ("Electronic materials" November 1992 issue (pp. 102-107), published by Industrial Research Council) “Medical Ultrasound: Pulse-excitation Ultrasound Microscope” (“Ultrasonic TECHNO” VOL.15 No.6 (November 11-12, 2003) (101-105 pages), published by Nihon Kogyo Shuppansha) JP 2001-46370 A Japanese Patent Laid-Open No. 7-303657 Special Table 2000-517414

  By the way, in such a sound speed measurement that can be processed at high speed using an ultrasonic microscope by pulse excitation, the sound speed of the object to be measured must be accurately measured from the reflected wave when the ultrasonic wave is irradiated. In the diagnostic imaging apparatus, the speed of sound of the living tissue at the irradiation point (measurement point) must be accurately calculated. For this purpose, the object to be measured and the ultrasonic transducer (transducer) 11 face each other, and ultrasonic waves are radiated at right angles to the preparation 12 and the object to be measured 13 which are reference substrates as shown in FIG. is necessary.

  Since the object to be measured 13 is placed on the preparation 12, and this preparation 12 is further placed on the XY stage 16, the ultrasonic transducer 11, the preparation 12, and the object 13 to be measured are respectively correct. The pair is not necessarily in a pair relationship, and although it is very small, it is almost the case where it faces directly with a slight inclination. If the inclination is not zero, the thickness and sound speed cannot be accurately calculated from the reference reflected wave signal Sr and the interference reflected wave signal So, and a slight measurement error occurs.

  For example, as shown in FIG. 15, when the plane 12 a of the preparation 12 has an inclination θ with respect to the reference plane ref, the relationship between the reference point Po and the measurement point Pp where the DUT 13 is placed is The measurement point Pp is shifted by Δd from the reference point Po with respect to the z-axis direction (ultrasound emission direction).

  The measured thickness changes due to the deviation of the measurement point Pp in the z-axis direction. In addition, if the thickness changes, a sound speed calculation error occurs, and the influence of this error may hinder more precise and detailed image diagnosis.

  In particular, when observing a living tissue as an object to be measured, the living tissue is cut out extremely thinly and used. Usually, it slices so that it may become a thickness of about 4-10 micrometers. On the other hand, the inclination of the preparation 12 usually has an adjustment error (tilt error) of about 1 μm even after fine adjustment. However, since this adjustment error is a value that cannot be overlooked from the thickness of the living tissue, it must be adjusted with extremely high accuracy and the inclination must be as close to zero as possible.

  In the conventional measurement, this deviation Δd is mechanically corrected. For example, as shown in FIG. 16, an arbitrary point Po on the plane 12a of the preparation 12 on which the biological tissue section 13 is not placed is used as a reference point, and an arbitrary point P1 in the x-axis direction and an arbitrary point in the y-axis direction. The tilt of the X-axis direction of the preparation 12 as viewed from the reference point Po (Δθx) is finely adjusted from the preparation 12, more specifically, the X-stage tilt of the X stage 16X. . Similarly, the tilt of the Y stage 16Y is finely adjusted so that the tilt (Δθy) in the y-axis direction becomes zero.

  By repeatedly performing such mechanical fine adjustment, the ultrasonic wave emission direction and each of the preparation 12 and the biological tissue section 13 are orthogonal to each other, so that the calculation accuracy of the sound speed is increased.

  However, since the inclination θ of the XY stage 16 with respect to the ultrasonic wave emission direction is extremely small as described above, considerable skill is required to accurately fine-tune this, so Pre-adjustment is cumbersome and spends considerable time on pre-adjustment time. As a result, it is a factor that impedes rapid and highly accurate biological tissue diagnosis. In addition, this mechanical fine adjustment requires skill and must be carried out every time a living tissue is diagnosed, which causes problems such as being very troublesome.

  For this reason, when measuring the speed of sound using an ultrasonic microscope, it is extremely important to correct the inclination of the object to be measured with respect to the ultrasonic transducer in a short time and with high accuracy. This greatly affects the accuracy of image diagnosis for an image diagnosis apparatus using an ultrasonic microscope.

  Therefore, the present invention solves such a conventional problem, and is not particularly based on mechanical adjustment, in other words, a sound speed measuring method using an ultrasonic microscope capable of correcting an inclination only by electrical processing. The present invention proposes a sound speed measuring device, an image diagnostic method applying the tilt correction, and an image diagnostic device thereof.

In order to solve the above-mentioned problem, a sound speed measuring method using an ultrasonic microscope according to the present invention described in claim 1 is a pulse excitation type that measures the sound speed of an object to be measured by pulse exciting an ultrasonic transducer. the speed-of-sound measurement method using the ultrasonic microscope, a trigger signal generating step of generating a trigger signal for pulse excitation with a predetermined interval, and a trigger signal is supplied, the interval than the trigger signal narrow I励 electromotive a centralized pulsed excitation step of intensively excited ultrasonic transducer in pulse, a step of averaging the reflected wave signal from the obtained that excitation pulses during the intensive pulsed excitation period, facing the ultrasonic vibrator The step of detecting the amount of inclination of the sample mounting plate, the step of calculating the thickness of the object to be measured based on the detected amount of inclination and the averaged reflected wave signal, and the amount of inclination Characterized by a step of calculating the sound speed of the object to be measured based on the thickness of the gas-to corrected DUT.

The sound speed measuring apparatus using the ultrasonic microscope according to the present invention described in claim 6 is a sound speed measurement using a pulse excitation type ultrasonic microscope that measures the sound speed of the object to be measured by pulse exciting the ultrasonic vibrator. there device, a trigger signal generator for generating a trigger signal for pulse excitation with a predetermined interval, is supplied with the trigger signal generated by trigger signal generator, the interval than the trigger signal narrow I励 electromotive pulse in signal calculation for averaging a pulser unit having a centralized pulsed excitation function to focus exciting the ultrasonic transducer, a reflected wave signal from the excited excitation pulse pulser portion obtained during intensive pulsed excitation period Means, an inclination amount detecting means for detecting the inclination amount of the sample mounting plate facing the ultrasonic transducer, the detected inclination amount, and the reflected wave signal averaged by the signal calculating means. A thickness calculating means for calculating the thickness of the object to be measured, and a sound speed measuring means for measuring the sound speed of the object to be measured based on the thickness of the object to be measured electrically corrected by the amount of inclination. Features.

According to another aspect of the present invention, there is provided a sonic image acquisition method using an ultrasonic microscope according to the present invention. the speed-of-sound image acquisition method using a microscope, and a trigger signal generating step of generating a trigger signal for pulse excitation with a predetermined interval, and a trigger signal is supplied, the interval than the trigger signal narrow I励 electromotive pulse in a centralized pulsed excitation step of intensively excited ultrasonic transducer, comprising the steps of averaging the reflected wave signal from the obtained that excitation pulses during the intensive pulsed excitation period, the sample facing the ultrasonic vibrator A step of detecting the amount of inclination of the mounting plate, a step of calculating the thickness of the object to be measured based on the detected amount of inclination and the averaged reflected wave signal, and based on the reflected wave signal The step of electrically correcting the thickness of the measured object by the amount of inclination, the step of calculating the sound speed of the measured object from the thickness information of the measured object, and the sound speed image of the measured object from the sound speed And generating.

Furthermore, in the diagnostic imaging apparatus using the ultrasonic microscope according to the present invention as set forth in claim 17, a pulse excitation type ultrasonic microscope which acquires the property of the object to be measured as a sound velocity image by pulse exciting the ultrasonic transducer. , A trigger signal generation unit that generates a trigger signal for pulse excitation having a predetermined interval, and a trigger signal generated by the trigger signal generation unit is supplied, and the interval is longer than the trigger signal. narrow I励 and pulser unit having a centralized pulsed excitation function to focus exciting the ultrasonic transducers in force pulse, the reflected wave signal from the excited excitation pulse pulser portion obtained during intensive pulsed excitation period The signal calculation means for averaging, the inclination amount detection means for detecting the inclination amount of the sample mounting plate facing the ultrasonic transducer, and the detected inclination amount are averaged by the signal calculation means. A thickness calculating means for calculating the thickness of the object to be measured based on the reflected wave signal, a correcting means for electrically correcting the thickness of the object to be measured calculated based on the reflected wave signal by the amount of inclination, It has a sound speed calculating means for calculating the sound speed of the object to be measured from the thickness information of the object to be measured, and a sound speed image generating means for generating a sound speed image of the object to be measured from the sound speed.

  In this invention, before measuring the sound velocity of the object to be measured, the coefficients a, b, and c used in the plane equation Z of the preparation as the sample mounting plate are calculated. In order to calculate the plane equation, at least three arbitrary points on the plane of the preparation are taken. Of course, multipoint measurement of three or more points is possible, and the accuracy is improved accordingly, but three points are exemplified in the embodiment.

  These three points are all points on the surface where the sample (object to be measured) is not placed. One of the three points, for example, Po is set as a reference point. The value (slope) Zo in the z-axis direction at the reference point Po is zero. The z-axis direction values Z1 and Z2 at the remaining two points are calculated using the reflected wave signal Sr obtained by actually irradiating the sample with ultrasonic waves. Specifically, the reflected wave signals Sro, Sr1, Sr2 obtained from the three measurement points Po, P1, P2 are decomposed into frequency components, and values Z1, Z2 in the z-axis direction are calculated from the frequency component ratio. Finally, the coefficients a, b, and c can be obtained.

  If the coefficients a, b, and c are known, the value Zp in the z-axis direction at an arbitrary point in the plane of the preparation on which the sample is placed, that is, the amount of inclination can be calculated. This z-axis direction value Zp is used as a correction value when calculating the thickness d of the sample, so that even if the preparation is tilted with respect to the ultrasonic wave emission direction, the measurement point is taken into account while taking this tilt into account. The sound speed of the sample can be accurately calculated. That is, the sound speed of the object to be measured, which is a sample, can be obtained in a state where the inclination is electrically corrected.

  Accordingly, even when the object to be measured is acquired as an image for diagnosis, the actual image (sonic image) is obtained after the above-described coefficients a, b, and c are obtained with the object to be measured placed on the slide. Work to ask for is done. If the thickness of the living tissue can be calculated with high accuracy, the sound velocity at the measurement point can also be calculated accurately. If the value of the sound velocity is drawn as an isosonic line for each measurement point, a sound velocity image of the living tissue can be obtained. Therefore, the accuracy of the sound velocity image is also greatly improved, and it becomes possible to diagnose the living tissue more precisely.

  According to the present invention, the inclination of the placement surface on which the living tissue is placed with respect to the emission direction of the ultrasonic wave can be corrected by signal processing.

  According to this, since the thickness and sound speed of the object to be measured can be calculated in a state in which the inclination of the placement surface is corrected by signal processing, the preprocessing time for sound speed measurement and image diagnosis can be greatly shortened compared to the conventional case. Furthermore, since the sound speed of the object to be measured is calculated by electrically correcting the inclination of the mounting surface, there is no error due to misadjustment like mechanical adjustment. Each time, the obtained data has almost no variation, and the accuracy of the calculated sound speed is remarkably improved. Therefore, the sound velocity of the object to be measured can be measured with high accuracy and in a very short time, and the sound velocity image reflecting the object to be measured can be obtained more accurately.

  In the sound speed measurement according to the present invention, the sound speed of the object to be measured can be measured with extremely high accuracy. Therefore, it is extremely important to apply this idea to the image diagnosis according to the present invention. This is because a slice of a living tissue to be subjected to image diagnosis has a very thin thickness of about 10 μm, and even a slight inclination of several μm has a great influence on the sound velocity image calculation result.

  Subsequently, preferred embodiments of a sound speed measuring method, a sound speed measuring apparatus, an image diagnostic method and an image diagnostic apparatus using the ultrasonic microscope according to the present invention will be described in detail with reference to the drawings. As an example described below, an example will be described in which a slice of a living tissue is used as an object to be measured and its thickness and sound speed are measured to obtain a sound velocity image of the living tissue.

The object to be measured is a biological tissue section. FIG. 17 is a diagram for explaining the principle for electrically performing tilt correction.
Rather than adjusting the inclination of the preparation 12 by mechanical adjustment, in order to correct this mechanical inclination by electrical processing, it is necessary to first solve the plane equation of the preparation 12. Since the inclination of the XY stage 16 is reflected in the inclination of the preparation 12, it is only necessary to correct the inclination of the preparation 12 on which the biological tissue section 13 is placed.

  If the plane equation at an arbitrary point in the state where the preparation 12 is tilted can be calculated, the z-axis value itself represented by the plane equation is a value including the tilt. Is calculated using this plane equation, and the thickness is calculated in consideration of the inclination. That is, the thickness is calculated excluding the influence of the inclination.

  Therefore, arbitrary three points Po, P1, and P2 on the plane 12a of the preparation 12 on which the biological tissue section 13 is not placed are designated as shown in FIG. One of them, for example, Po (xo, yo) is used as a reference point. The coordinates of the remaining two points P1 and P2 are (x1, y1) and (x2, y2).

As is well known, the plane equation is
Z = ax + by + c (1)
(Where a, b, and c are coefficients)
It is. Therefore, the plane equations Zo, Z1, Z2 of the three points Po, P1, P2 are: Zo = axo + byo + c (2)
Z1 = ax1 + by1 + c (3)
Z2 = ax2 + by2 + c (4)
The inclination of the reference point Po is zero (Zo = 0) because it is a reference point.
From the equations (2) to (4), the coefficients a, b, and c are

It becomes.

Accordingly, the plane equation at an arbitrary measurement point Px (xp, yp) of the preparation 12 on which the biological tissue section 13 is placed is expressed by the following equations from the coefficients a, b, c: Zp = axp + byp + c (6 )
It becomes. Using the value Zp in the z-axis direction, that is, the distance difference Zp in the z-axis direction between the reference point Po and the measurement point Px, the thickness dp at the measurement point Px is calculated.

  The plane equations Z1 and Z2 at the measurement points P1 and P2 described above can be calculated as follows. First, the reflected wave signals Sro, Sr1, Sr2 at the points Po, P1, P2 are obtained.

  Next, in order to obtain frequency components of these reflected wave signals Sro, Sr1, and Sr2, a Fourier transform (for example, a fast Fourier transform FFT) process is performed. Ratios (F1 / Fo) and (F2 / Fo) of Fourier transform outputs based on the reference point Po are obtained from the respective Fourier transform outputs Fo, F1, and F2. The ratio of the Fourier transform output is a normalized spectrum.

  Next, φ / 2πf (f is the center frequency of the ultrasonic signal) is obtained from a complex plane (phase relationship with respect to frequency) related to the normalized spectrum. This φ / 2πf eventually becomes the time difference Δto1 caused by the inclination between the reference point Po and the measurement point P1. Similarly, a time difference Δto2 caused by the inclination between the reference point Po and the measurement point P2 is obtained.

Accordingly, the value in the z-axis direction from the reference point Po to the measurement point P1, that is, the plane equation Z1, is the sound velocity of the medium (usually water) interposed between the ultrasonic transducer 10 and the preparation 12. When Co is
Z1 = Co · Δto1 (7)
Can be obtained as Co is a known value (= 1600 m / s). Similarly, the plane equation Z2 at the measurement point P2 is
Z2 = Co · Δto2 (8)
Thus, the above-described coefficients a, b, c can be calculated from these values Z1, Z2 and the above-described reference value Zo (= 0) (formula (5)). The calculated coefficients a, b, and c are stored in a memory means (such as a RAM) for reference when measuring the thickness of the biological tissue section 13.

  As described above, when an ultrasonic signal is applied to the biological tissue section 13, an interference reflected wave signal So in which reflected waves from the front and back surfaces of the biological tissue section 13 interfere is obtained. Therefore, the reference reflected wave signal Sr and the interference reflected wave signal So from the surface of the preparation 12 are Fourier transformed, respectively, and the reference reflected wave signal Sr and the interference reflected wave signal So (specifically, the primary reflected wave signal Su1) and By comparison, a normalized phase spectrum can be obtained as well as a normalized intensity spectrum. Examples of this spectrum are shown in FIGS. 18A and 18B.

  If the frequency of the signal intensity minimum point or maximum point is fm, and the phase at that time is φm, the reflected waves from the front and back surfaces of the biological tissue section 13 are opposite in phase at the minimum point and in phase at the maximum point. ing. That is, at the minimum point, the reflected wave from the surface of the biological tissue section 13 is advanced by (2n−1) π from the reflected wave from the back surface, and becomes {φm + (2n−1) π} (n is a natural number). If the thickness of the biological tissue section 13 is d and the sound speed of water is Co,

Since this phase difference is 2nπ at the maximum point,

Is established. On the other hand, the phase difference between the reflected wave that has passed through the distance of 2d at the sound velocity C in the biological tissue slice 13 and the reflected wave that has passed at the reference sound velocity Co is φm.

Solving equations (9) and (11) simultaneously,
d = {φm + (2n−1) π} Co / 4πfm (12)
Thus, the thickness d of the biological tissue section 13 can be obtained. Also, solving (10) and (11) together,

Thus, the sound velocity C of the living tissue is obtained.

  On the other hand, the minimum value fm (98 MHz in this case) of the normalized intensity spectrum shown in FIG. 18A is adopted as the frequency fa when calculating the thickness d and the sound velocity C of the biological tissue section 13. The phase φm at the minimum value fm is 92 deg from the normalized phase spectrum curve of FIG. 18B.

  When calculating the thickness d and the sound velocity C, fm = fa is substituted, but the phase at that time is in the z-axis direction (ultrasonic emission direction) generated by the inclination from the reference point Po on the preparation 12 serving as the reference point. The phase is shifted by a phase corresponding to the distance difference Zp. Therefore, it is necessary to correct the phase corresponding to the distance difference Zp. The distance difference Zp can be calculated by equation (6).

  Therefore, the phase φm corrected by the distance difference Zp is calculated as follows.

  By substituting the phase φm calculated in this way and the frequency fm (= fa) at the minimum value into the equations (12) and (13), the final thickness d and the sound velocity corrected for the distance difference Zp. C can be obtained.

  Next, an example of an image diagnostic apparatus 100 to which the sound velocity measuring apparatus using the ultrasonic microscope according to the present invention is further applied will be described with reference to FIG.

  The diagnostic imaging apparatus 100 is roughly composed of a main body 1A of the ultrasonic microscope 1, a first signal processing unit 1B, and a second signal processing unit 1C. Naturally, the diagnostic imaging apparatus 100 also functions as a sound velocity measuring apparatus. The difference is that, when used as a sound velocity measuring device, the sound velocity image calculation processing unit 57 which is the final step in image diagnosis is not included.

  Here, the diagnostic imaging apparatus 100 includes an inclination amount detection unit that detects an inclination amount of the sample mounting plate 12 facing the ultrasonic transducer 11, the detected inclination amount, and the ultrasonic transducer 11 Thickness calculating means for calculating the thickness of the object to be measured 13 based on the reflected wave signal So, and correcting means for electrically correcting the thickness of the object to be measured 13 calculated based on the reflected wave signal So by the amount of inclination. The sound velocity calculating means for calculating the sound velocity of the object to be measured 13 from the thickness information of the object to be measured 13 and the sound velocity image generating means for generating the sound velocity image of the object to be measured 13 from this sound velocity. .

  The inclination amount detection means, the thickness calculation means, the inclination amount correction means, and the sonic image generation means are mainly composed of the main body 1A and the second signal processing part 1C.

  In this example, which is the object to be measured as described above, the microscope main body 1A has an XY stage 16 used as a two-dimensional scanning means to move the biological tissue section 13 two-dimensionally with the ultrasonic transducer 11. Face up. The XY stage 16 is provided with motors 31X and 33Y for driving the stages 16X and 16Y. A stepping motor or a linear motor can be used as the drive motors 31X and 33Y, and a high-speed and low-vibration linear motor is preferable.

  By using a stepping motor, particularly a linear motor, the X stage 16X can be continuously scanned (continuous feed), and by controlling the Y stage 16Y to be intermittent feed, the XY stage 16 can be controlled. High speed scanning becomes possible.

  The drive motors 31X and 33Y are provided with controllers 30X and 32Y for generating drive signals for them, respectively, and the drive control signal (pulse signal) generated by the second signal processing unit 1C is provided in one controller 30X. Supplied.

  In this example, an encoder 34 is provided in association with the X stage 16X, and the scanning position of the X stage 16X is detected by the encoder 34. For example, when divided into 300 × 300 measurement points (pixels) including the preparation 12 as shown in FIG. 13, one scan in the x direction is divided into 300, so that the position of each pixel is A drive control signal is generated in synchronization with the encoder output detected by the encoder 34.

  Therefore, the encoder output is supplied as a synchronization signal to the CPU 55 provided in the second signal processing unit 1C, and the pulse generation unit 56 is associated with the CPU 55. Therefore, the pulse generation unit 56 is synchronized with the encoder output. A drive control signal is generated.

  A trigger signal St synchronized with the drive control signal is further generated from the controller 30X for the X stage 16X, and this is supplied to the pulsar section 36. In the pulsar unit 36, an excitation pulse is generated at a timing synchronized with the trigger signal St.

  The pulsar unit 36 is for generating an excitation pulse for the ultrasonic transducer 11, and this excitation pulse is supplied to the ultrasonic transducer 11 via the transmission / reception wave separation unit 37. The excitation pulse Si from the pulsar unit 36 is a broadband pulse signal (see FIG. 12). In this example, as shown in FIG. 11A, a pulse signal having a sine wave shape of one cycle is output. Yes.

  As will be described later, the pulsar unit 36 is intermittently driven by the trigger signal St, and is configured so that a plurality of excitation pulses can be output more intensively in this unit intermittent period in a short time. .

  As the ultrasonic transducer 11, a transducer for both transmission and reception is used, and when excited by an excitation pulse, an ultrasonic signal Si narrowed in a beam shape is emitted. Of the reflected wave signals Sr and So received by the same ultrasonic transducer 11, the reflected wave signal So obtained from the biological tissue section 13 is an interference waveform. These reflected wave signals Sr and So are supplied to the first signal processing unit 1B functioning as a signal calculation unit via the transmission / reception wave separation unit 37 and the reception unit 38.

  The first signal processing unit 1B includes a gate circuit 40 and a gate pulse generation circuit 42. The gate pulse generation circuit 42 is supplied with a pulse signal synchronized with the excitation pulse. Therefore, a resistance voltage dividing unit 41 is provided at the output stage of the pulsar unit 36, and the excitation pulse Si divided by the resistance voltage dividing unit 41 is supplied to the gate pulse generation circuit 42 and delayed by a predetermined time from the excitation pulse Si. A gate pulse Sg is generated.

  On the other hand, the reference reflected wave signal Sr and the interference reflected wave signal So are supplied to the gate circuit 40, and only the desired signal portion of the interference reflected wave signal So is gated by the gate pulse Sg described above.

  Here, as shown in FIG. 11C, the interference reflected wave signal So is a combination of the reflected wave signal Si ′ related to the excitation pulse Si for exciting the ultrasonic transducer 11 and the reflected wave signal Su. Since the reflected ultrasonic wave is repeatedly reflected between the ultrasonic transducer 11 and the biological tissue section 13, the nth-order reflected wave signal Su is originally obtained as a multiplexed signal.

  In the embodiment, in order to extract only the reflected wave signal that is reflected first (referred to as the primary reflected wave signal Su1), the gate pulse Sg delayed by a predetermined time from the excitation pulse Si is used.

  The gated primary reflected wave signal Su1 is supplied to the A / D conversion circuit 43 and subjected to A / D conversion processing, and the processed A / D conversion output is temporarily stored in the memory means 44. As will be described later, the ultrasonic transducer 11 is intermittently excited in a predetermined cycle, and a plurality of excitation pulses are excited in a short time in a more concentrated manner in this unit intermittent cycle. As will be described in detail later, in this example, high-speed excitation is performed about 7 to 10 times. In the following, a case where high-speed excitation is performed eight times is shown.

  Each of them is stored in the memory means 44, and after the eighth primary reflected wave signal Su (8) is acquired, the primary reflected wave signals Su1 (1) and Su2 (2) are obtained by the averaging circuit 45 in the subsequent stage. ),..., And averaged using Su8 (8). Such an averaging process is performed because a sufficient S / N (that is, C / N) cannot be obtained with only one primary reflected wave signal Su1, and the main purpose is to improve the S / N. is there.

  In addition, as described above, the gate pulse Sg is generated using the excitation pulse Si divided by the resistance voltage dividing unit 41 provided on the output stage side of the pulsar unit 38. This is to avoid the jitter of the gate pulse Sg when the primary reflected wave signal Su1 is obtained. This is because if there is no jitter in the gate pulse Sg, the synchronization jitter component when the primary reflected wave signal Su1 is averaged becomes zero, and a stable averaged output can be obtained.

  Note that a general-purpose high-speed A / D board (for example, an A / D board such as model number 741025 sold by Yokogawa Seisakusho) is used as an A / D board with a gate function capable of high-speed processing that can be used for such purposes. it can.

  The averaged primary reflected wave signal Su is supplied to the second signal processing unit 1C. In the second signal processing unit 1C, as preprocessing for obtaining a sound velocity image, Z calculation processing of a plane equation and correction value calculation processing for calculating coefficients a, b, and c are performed. In addition, sound speed calculation processing and sound speed image generation processing are performed.

  Therefore, in the second signal processing unit 1C, the fast Fourier transform processing unit 51 to which the primary reflected wave signal Su1 is supplied, the computing unit 52 that computes the Fourier transform output, and the time difference Δt from the computed normalized spectrum. A Δt calculating unit 53 for calculating, a working memory means 54 for performing these processes, and the like are provided.

  Further, a sound speed calculation and sound speed image generation processing unit 57 to which data of the time difference Δt and Fourier transform output are respectively supplied are provided. The sound speed calculation and sound speed image generation processing unit 57 functions as an image drawing unit. The time difference Δt is data supplied when calculating the coefficients a, b, and c, and the Fourier transform output is data supplied when generating a normal sound velocity image.

  Then, by executing a processing program for calculating the z value, a processing program for calculating the sound speed, and a processing program for calculating the sound speed stored in the ROM 60 (see FIG. 2) in the CPU 55, the above-described z value calculating process is executed. Etc. will be performed.

  The CPU 55 is further associated with a pulse generation unit 56 for supplying to the controller 30X, and the pulse generation unit 56 is driven in synchronization with the synchronization pulse from the CPU 55. The CPU 55 is further supplied with the encoder output of the encoder 34 provided in the microscope main body 1A. A synchronization pulse is output from the CPU 55 in synchronization with the encoder output.

  Therefore, since the trigger signal St is finally generated in synchronization with the encoder output of the encoder 34, the pulsar unit 36 is excited in synchronization with each pixel of the biological tissue section 13, so that each pixel is reliably detected. An ultrasonic signal can be irradiated.

  The relationship between the components of the second signal processing unit 1C can be rewritten as shown in FIG. The working memory means 54 uses the RAM shown in FIG. The primary reflected wave signal (digital signal) Su1 is taken in via the interface 61.

  In the sonic image calculation processing unit 57 that also functions as an image drawing unit, the tissue of the biological tissue section 13 is drawn in units of microns by drawing with isosonic lines. A visible image (sonic image) of a living tissue can be obtained by drawing on a monitor (not shown) an isosonic line obtained by connecting the same sound velocities. A biological tissue can be observed and diagnosed from this sound velocity image.

  By displaying the area surrounded by the isosonic line in the same color, color display becomes possible, and this makes it possible to clearly identify the altered biological tissue. By applying gradation to the display color, the boundary transition of the organization becomes smooth. Of course, when drawing is performed based on the attenuation (intensity) of the primary reflected wave signal Su1, an attenuation image is obtained as a living body image.

  In FIG. 2, the CPU 55 has been described for the second signal processing unit 1 </ b> C. However, it is a matter of course that the CPU 55 can also be used as a CPU for controlling the entire apparatus, in addition to providing a separate CPU for controlling the entire apparatus. .

Next, the operation of the diagnostic imaging apparatus 100 shown in FIG. 1 will be described with reference to FIG.
FIG. 3 is an explanatory diagram of S / N of the primary reflected wave signal Su1. As described above, in order to be able to draw a sound velocity image within 5 minutes, especially 2 minutes or less after the biological tissue section 13 is two-dimensionally scanned at high speed and finally starts measurement, in the x direction. It is necessary to increase the scanning time of one line by performing high-speed continuous scanning.

  In this example, since the measurement time for one pixel is about 80 μsec, the interval of the trigger signal St is also 80 μsec (FIG. 3A).

  An excitation pulse Si is obtained in synchronization with the trigger signal St (FIG. 3B). The reflected wave is as shown in FIG. 3C. The primary reflected wave signal Su1 is obtained with a delay of about 2 μsec with respect to the reflected wave signal Si ′ related to the excitation pulse Si, and the secondary reflected wave signal Su2 is obtained with a delay of 2 μsec. The width of the reflected wave signal So is about 100 nsec.

The simplest signal processing is processing for extracting the primary reflected wave signal Su1 using the gate pulse Sg of FIG. 3D, but this does not provide sufficient S / N.
In order to improve the S / N, the ultrasonic transducer 11 may be excited a plurality of times to obtain the same signal and averaged. However, in order to do so, excitation processing must be performed a plurality of times at the same scanning position, so that it takes a multiple of times before the start of measurement for the next pixel. With this, high-speed image processing cannot be realized.

  Therefore, while maintaining a time interval for intermittently exciting the ultrasonic transducer 11, a plurality of excitation pulses are intensively excited within a short period of time within the intermittent excitation time. The primary reflected wave signal is acquired, and the averaged signal is used as the reflected wave signal. A specific example will be described with reference to FIG.

  As described above, the time until the primary reflected wave signal Su1 is obtained from the reflected wave signal Si ′ with respect to the excitation pulse Si is about 2 μsec, and this primary reflected wave signal Su1 has the best S / N, and the secondary and subsequent reflections. Since the wave signal Su2,... Is a multiple reflection signal between the ultrasonic transducer 11 and the biological tissue section 13, the S / N is poor.

  Therefore, the intermittent excitation time is made the same as in FIG. 3 in order to realize high-speed image processing as shown in FIG. 4A. Next, the primary reflected wave signal Su1 is the only reflected wave signal to be used. In order to dispose of the reflected wave signal, the ultrasonic transducer 11 is excited continuously several times (2 times or more), preferably 7 to 10 times, for example, 8 times at intervals of about 2 μsec. That is, as shown in FIG. 4A, for the trigger signal St, the pulsar unit 36 continuously generates eight excitation pulses at intervals of 2 μsec as shown in FIG. 4B.

  The ultrasonic transducer 11 is excited by the excitation pulses Si at intervals of 2 μsec. As a result, a reflected wave signal as shown in FIG. 4C is obtained.

  On the other hand, a gate pulse Sg (FIG. 4D) synchronized with the excitation pulse Si is generated. If only the primary reflected wave signal Su1 is gated by this continuous gate pulse Sg, eight primary reflected wave signals Su1 are obtained (FIG. 4E). FIG. 4E is shown side by side for convenience. It is clear that the signals are not actually arranged in such a time series.

  These eight primary reflected wave signals Su1 (1) to Su8 (8) are averaged to generate a final primary reflected wave signal Su (FIG. 4F). This process improves the S / N of the primary reflected wave signal Su and enables high-speed image processing.

  Next, a processing example for realizing the image diagnostic method according to the present invention will be described with reference to the flowcharts of FIGS.

  FIG. 5 is a flowchart showing a processing example for calculating the coefficients a, b, and c in the plane equation, and this calculation processing program is programmed as a part of the generation processing program for generating the sound velocity image. Sometimes it is programmed as a subroutine alone.

  The following is an example of processing when programmed as a subroutine. When this calculation program is started, first, the XY table 16 is scanned and an arbitrary measurement point (measurement point) Pi (i = 0, 1, 1) on the slide 12 is scanned. 2 and Po, P1, P2) coordinate data (xi, yi) {i = 0, 1, 2 (x0, y0), (x1, y1), (x2, y2)}. Obtain (step 71).

  Next, the reflected wave signals Sri (i = 0, 1, 2 and Sro, Sr1, Sr2) at these measurement points Pi are acquired (step 72), and the obtained reflected wave signals Sri are respectively transmitted at high speed. Fourier transform is performed to obtain a Fourier transform output Fi (step 73).

  Subsequently, a normalized spectrum is obtained by calculating a ratio (Fr1 / Fro and Fr2 / Fro) with the reference Fourier transform output Fro from these Fourier transform outputs Fi (step 74).

From the frequency component f and the phase component φ of the normalized spectrum thus obtained,
A time difference Δti (i = 1, 2) at φ / 2πf is calculated (step 75).

  From the time differences Δt1, Δt2 from the reference point Po at the measurement point Pi (i = 1, 2) and the known sound velocity Co (the sound velocity of water in this example), the plane equation Zi (i = 1, 1) at the measurement points P1, P2. 2 and Z1 and Z2) are obtained (step 76). This plane equation Zi becomes the z value (inclination amount) at the measurement points P1 and P2 with respect to the reference point Po.

  Coefficients a, b and c are calculated from the three plane equations Zo, Z1 and Z2 calculated through such processing, and the calculated coefficients a, b and c are stored in the memory means 54 (step 77). Therefore, the plane equation Zp at all the measurement points Pp (xp, yp) of these biological tissue sections 13, that is, the z value Zp at the measurement point Pp based on the reference point Po can be calculated. This coefficient calculation process is executed every time a biological tissue that is an object to be measured is observed as a pre-process for generating a sonic image.

FIG. 6 is a flowchart showing an example of sound speed calculation including inclination correction, and it is assumed that the coefficients a, b, and c are already stored.
When the sonic image generation processing program is started, the XY stage 16 is driven based on an instruction from the CPU 55 to start scanning in the x direction, and drive control is performed in synchronization with the encoder output from the encoder 34. A signal is supplied to the controller 30X.

  In synchronization with this drive control signal, a trigger signal St is supplied to the pulsar unit 36, and the ultrasonic transducer 11 is excited. The coordinates (xi, yi) (i = 1 to 300) of the measurement point (pixel) Pi on the scanning line in the x direction obtained by this series of processing are acquired (step 81) and the reflected wave at the measurement point Pi. The signal Soi is acquired (step 82). As the reflected wave signal Soi, a signal obtained by averaging a plurality of, in this example, eight primary reflected wave signals Su1 obtained from substantially the same measurement point Pi is used.

  Subsequently, the plane equation at the measurement point Pi, in other words, the z value (inclination amount) Zp at the measurement point Pi is calculated from the reflected wave signal Soi, and stored (step 83).

  Thereafter, the thickness di of the living tissue at the measurement point Pi is calculated from the time difference between the reflected wave signal Soi and the reflected wave signal Sr to be referred to, the intensity of the reflected wave signal Soi, the phase difference, and the like (step 84). The z value Zp is referred to in this thickness calculation process. That is, in step 84, the thickness di including the inclination of the preparation 12 is obtained, and the thickness di is obtained by removing the influence of the inclination.

  Next, the sound velocity Ci at the measurement point Pi is calculated from the calculated thickness di, and the value is stored in the memory means 54 functioning as a drawing plane (frame) (step 85). The sound speed Ci is drawn on the screen as isosonic line data, and is further saved as drawing information in another area of the memory means 54 (step 86).

  Since such a sound speed calculation process is executed for all pixels (for example, 300 × 300 pixels) (step 87), by obtaining sound speed data for all pixels, an isosonic line of biological tissue is drawn. it can. A color sound speed line can be obtained by distinguishing the isosonic speed line by color display. A sonic image of a living tissue can be obtained by drawing an isosonic line. Further, an attenuation image of the biological tissue can be obtained by obtaining the reflection intensity (attenuation amount) from the reflected wave signal Soi at each measurement point Pi.

  In the above-described embodiment, the plane equation is obtained by designating any three points with respect to the preparation 12, but the plane equation is obtained using more points and the coefficient of the plane equation is calculated from this. You may do it. The more points (four or more), the more accurate the calculated coefficient value.

  Furthermore, if the plane equation is calculated in consideration of the unevenness and warpage of the preparation 12 and the living tissue 13 itself, the thickness d and sound speed of the living tissue section 13 can be calculated more accurately. Others are the same as in the first embodiment.

  In the above-described embodiment, the sound velocity measurement when using a biological tissue section as the object to be measured is obtained by correcting electrically (in a signal manner), and the sound velocity image of the biological tissue is obtained from the calculated sound velocity. However, it is obvious that the measurement of the sound velocity of the object to be measured and the generation of the sound velocity image are not limited to the living tissue, and various objects to be measured can be the measurement object. Others are the same as in the first embodiment.

  The present invention can be applied to a sound velocity measuring device that measures the sound velocity of a sample using an ultrasonic microscope, an image diagnostic device that observes and diagnoses the surface state of a biological tissue and other objects to be measured.

It is a systematic diagram of the principal part which shows the Example of the image diagnostic apparatus using the ultrasonic microscope which concerns on this invention. It is a systematic diagram of the principal part which shows the Example of a 2nd signal processing part. It is a wave form diagram which shows the relationship between excitation of an ultrasonic transducer | vibrator and a primary reflected wave signal. It is a wave form diagram which shows concentrated pulse excitation. It is a flowchart which shows the coefficient calculation example of a plane equation required when implement | achieving the image diagnostic method which concerns on this invention. It is a flowchart which shows the process example in the case of processing the inclination correction of a preparation by signal processing. It is a conceptual diagram of an ultrasonic microscope. It is a figure which shows the relationship between a to-be-measured object and a two-dimensional scanning means. It is a figure which shows the example of continuous scanning. It is explanatory drawing of the reflected wave of an ultrasonic wave. It is a figure which shows the relationship between the excitation pulse and reflected wave at that time. It is a figure which shows the zone | band of an ultrasonic wave. It is a figure which shows a scanning area | region. It is a figure which shows the example of an image obtained by the ultrasonic wave. It is a figure which shows the relationship between the inclination of a preparation, and a biological tissue. It is explanatory drawing when performing the conventional inclination correction mechanically. It is explanatory drawing when correcting the inclination of a preparation by signal processing. It is a curve figure of a normalized spectrum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic microscope 11 ... Ultrasonic vibrator 12 ... Preparation 13 ... Object to be measured (living tissue section)
16 ... X-Y stage 16X ... X stage 16Y ... Y stage 17 ... medium (water)
21 ... sound velocity image 1A ... microscope main body 1B ... first signal processing unit 1C ... second signal processing unit 36 ... pulsar unit 40 ... gate circuit 42 ... gate Pulse generation circuit 45 ... averaging circuit 51 ... FFT processing unit 55 ... CPU
57 ... Sound velocity image generation processing unit

Claims (22)

A sound velocity measurement method using a pulse excitation type ultrasonic microscope that measures the sound velocity of an object to be measured by pulse exciting an ultrasonic transducer,
A trigger signal generating step for generating a trigger signal for pulse excitation having a predetermined interval ;
And the trigger signal is supplied, and concentrated pulsed excitation step of intensively excite the ultrasonic transducer with narrow I励 cause pulse intervals than the trigger signal,
A step of averaging the reflected wave signal from Ki励 force pulse on obtained during the intensive pulsed excitation period,
Detecting the amount of inclination of the sample mounting plate facing the ultrasonic transducer;
Calculating the thickness of the object to be measured based on the detected amount of inclination and the averaged reflected wave signal;
And a step of calculating a sound speed of the object to be measured based on a thickness of the object to be electrically corrected by the tilt amount. A method of measuring a sound speed using an ultrasonic microscope. The step of detecting the amount of inclination includes calculating a coefficient of a plane equation of the sample mounting surface;
The method for measuring the speed of sound using an ultrasonic microscope according to claim 1, further comprising a step of calculating an inclination amount at an arbitrary measurement point with respect to the measurement object based on a coefficient of the plane equation. 2. The sound speed measuring method using an ultrasonic microscope according to claim 1, wherein the step of calculating the coefficient of the plane equation is performed using reflected wave signals from at least three measurement points of the sample mounting plate. . 4. The sound speed measuring method using an ultrasonic microscope according to claim 3, wherein the measurement point is a plane of the sample mounting plate and a non-mounting surface of the object to be measured is used. Upper Ki励 causing pulses, speed-of-sound measurement method using the ultrasonic microscope according to claim 1, characterized in that the wide-band pulse signals. There is a sound velocity measuring device using a pulse excitation type ultrasonic microscope that measures the sound velocity of an object to be measured by pulse exciting an ultrasonic transducer,
A trigger signal generator for generating a trigger signal for pulse excitation having a predetermined interval ;
The trigger signal the trigger signal generated by the generator is supplied, pulser unit having a centralized pulsed excitation function of centrally excite the ultrasonic transducer with narrow I励 cause pulse intervals than the triggering signal When,
And signal calculation means for averaging the reflected wave signal from Ki励 electromotive pulse after being excited by the pulser unit obtained during intensive pulsed excitation period,
A tilt amount detecting means for detecting a tilt amount of the sample mounting plate facing the ultrasonic transducer;
Thickness calculating means for calculating the thickness of the object to be measured based on the detected amount of inclination and the reflected wave signal averaged by the signal calculating means;
Sound velocity measurement using an ultrasonic microscope characterized by comprising a sound velocity measuring means for measuring the sound velocity of the object to be measured based on the thickness of the object to be measured electrically corrected by the tilt amount. apparatus. The inclination amount detection has a calculation means for calculating a plane equation of the sample mounting plate,
The sound velocity measuring apparatus using an ultrasonic microscope according to claim 6, wherein an inclination amount at an arbitrary measured point with respect to the measured object is calculated based on a coefficient of the plane equation. The ultrasonic microscope according to claim 6, wherein the plane equation calculation means calculates the coefficient of the plane equation using reflected wave signals from at least three measurement points of the sample mounting plate. Used sound speed measurement device. 9. The sound velocity measuring apparatus using an ultrasonic microscope according to claim 8, wherein the measurement point is a flat surface of the sample mounting plate and a non-mounting surface of the object to be measured is used. Upper Ki励 electromotive pulse, acoustic velocity measuring apparatus using an acoustic microscope according to claim 6, characterized in that the wide-band pulse signals. A sound velocity image acquisition method using a pulse excitation type ultrasonic microscope that acquires a property of an object to be measured as a sound velocity image by pulse exciting an ultrasonic transducer,
A trigger signal generating step for generating a trigger signal for pulse excitation having a predetermined interval ;
And the trigger signal is supplied, and concentrated pulsed excitation step of intensively excite the ultrasonic transducer with narrow I励 cause pulse intervals than the trigger signal,
A step of averaging the reflected wave signal from Ki励 force pulse on obtained during the intensive pulsed excitation period,
Detecting the amount of inclination of the sample mounting plate facing the ultrasonic transducer;
Calculating the thickness of the object to be measured based on the detected amount of inclination and the averaged reflected wave signal;
Electrically correcting the thickness of the measurement object calculated based on the reflected wave signal by the amount of inclination;
Calculating the sound velocity of the device under test from the thickness information of the device under test;
Generating a sound speed image of the object to be measured from the sound speed, and a sound speed image acquiring method using an ultrasonic microscope. The step of detecting the amount of inclination includes calculating a coefficient of a plane equation of the sample mounting surface;
The method according to claim 11, further comprising: calculating an inclination amount at an arbitrary measurement point with respect to the measurement object based on a coefficient of the plane equation. . The sound velocity image acquisition using an ultrasonic microscope according to claim 11, wherein the step of calculating the coefficient of the plane equation is performed using reflected wave signals from at least three measurement points of the sample mounting plate. Method. The method according to claim 13, wherein the measurement point is a plane of the sample mounting plate and a non-mounting surface of the object to be measured is used. Upper Ki励 electromotive pulse, acoustic velocity image acquisition method using an ultrasonic microscope according to claim 11, wherein it is a wide-band pulse signals. The method according to claim 11, wherein the object to be measured is a biological tissue section. An image diagnostic apparatus using a pulse excitation type ultrasonic microscope that acquires a property of an object to be measured as a sound velocity image by pulse exciting an ultrasonic transducer,
A trigger signal generator for generating a trigger signal for pulse excitation having a predetermined interval ;
The trigger signal the trigger signal generated by the generator is supplied, pulser unit having a centralized pulsed excitation function of centrally excite the ultrasonic transducer with narrow I励 cause pulse intervals than the triggering signal When,
And signal calculation means for averaging the reflected wave signal from Ki励 electromotive pulse after being excited by the pulser unit obtained during intensive pulsed excitation period,
A tilt amount detecting means for detecting a tilt amount of the sample mounting plate facing the ultrasonic transducer;
Thickness calculating means for calculating the thickness of the object to be measured based on the detected amount of inclination and the reflected wave signal averaged by the signal calculating means;
Correction means for electrically correcting the thickness of the measurement object calculated based on the reflected wave signal by the amount of inclination;
A sound velocity calculating means for calculating the sound velocity of the object to be measured from the thickness information of the object to be measured;
An image diagnostic apparatus using an ultrasonic microscope, comprising: a sound velocity image generating means for generating a sound velocity image of the object to be measured from the sound velocity. The inclination amount detection has a calculation means for calculating a plane equation of the sample mounting plate,
18. The diagnostic imaging apparatus using an ultrasonic microscope according to claim 17, wherein an inclination amount at an arbitrary measurement point with respect to the measurement object is calculated based on a coefficient of the plane equation. The ultrasonic microscope according to claim 17, wherein the plane equation calculating means calculates the coefficient of the plane equation using reflected wave signals from at least three measurement points of the sample mounting plate. Used diagnostic imaging equipment. 20. The diagnostic imaging apparatus using an ultrasonic microscope according to claim 19, wherein the measurement point is a plane of the sample mounting plate and a non-mounting surface of the object to be measured is used. Upper Ki励 causing pulses, image diagnosis apparatus using an ultrasonic microscope according to claim 17, wherein it is a wide-band pulse signals. 18. The diagnostic imaging apparatus using an ultrasonic microscope according to claim 17, wherein the object to be measured is a biological tissue section.

Images