JPS6018159A - Ultrasonic tomographic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (5) Background of the Invention A, Technical Field The present invention relates to an ultrasonic tomography apparatus, and particularly to an ultrasonic tomography apparatus for superficial tissues of a living body.

B. Prior art and its problems Ultrasonic tomography devices are used for various parts of objects, such as living bodies, using various ultrasound scanner methods such as linear electronic scanners, sector electronic scanners, and contact compound scanners. There is. For example, liver,
It is used clinically in a wide range of areas, including the abdomen, including the pancreas and kidneys, obstetrics and gynecology, including the fetus, and the heart, and provides useful diagnostic information.

It is applicable not only to the deep parts of living tissues but also to superficial tissues. At the current state of the art, the focus is on the thyroid, mammary glands, and neck (arteries).

Ordinary ultrasonic tomography devices are designed to take tomographic images of relatively deep parts of living bodies, and such devices are used to diagnose areas relatively close to the body surface (several cIl or less). However, the resolution tends to be lower than when depicting deep areas. This uses the 3.5 MHz band, where ultrasonic waves are less absorbed in the living body, for deep observation, and uses a large ultrasound transmitting aperture to ensure good directivity even in the deep parts of the living body. Depends on where you are. For this reason, the distance resolution and azimuth resolution in the shallow parts of the body are sacrificed.

Referring to FIG. 1, consider an approximate sound field of a planar circular vibrator lO of a transmitting aperture vibrating at a frequency f. If the sound speed of ultrasound propagating in a living body is C, its wavelength input is c/f. As shown in the figure, the area from the vibrator 10 to the distance #D/2 people is called a Fresnel area FN, and the beam diameter is equal to the aperture. In other words, Y=D. This creates a near-field sound field.

Beyond this distance is the Fraunhofer region FH where the beam diameter expands at an angle λ/D. That is, y=2(in/D)・
It is X.

As we will see, if the aperture is constant, the frequency f
The higher the value, the better the directivity. Also, if the frequency is constant,
The larger the aperture, the better the directivity, but naturally the beam diameter also becomes larger.

Recently, as an ultrasonic tomography device for superficial tissues, 5
Development and commercialization of products using frequency bands of MHz, 7.5 MHz, and 10 MHz are being actively conducted.

This improves distance resolution by using high frequencies, and improves azimuth resolution by making the transmission aperture smaller.

Electronic scanning is an excellent method for obtaining real-time tomographic images. Mechanical or manual scanners for superficial tissue have already been commercialized, but they lack real-time performance, so there is a desire to develop an ultrasonic tomography apparatus exclusively for real-time use.

There are several technical and manufacturing issues in constructing high frequency probes for electronic scanners.

That is, the first problem is the material of the electroacoustic conversion transducer, and the second problem is the manufacturing technology.

For example, as shown in Fig. 2, in the case of a rectangular parallelepiped transducer array 12 in which ultrasonic waves propagate in the direction of arrow A, the thickness vibration of the transducer is utilized, so in order to use high frequencies, the thickness The t must be made thinner.

In addition, in order to approximate the sound source as a bis I/N sound source, the width W can be made larger than the thickness t by comparing the width W and the thickness t, but the latter can be converted compared to the former. The problem is that it is inefficient.

When driving multiple elements on the array 12 as a set during transmission, in order to suppress grating lobes, it is necessary to reduce the pinch P of each element compared to the wavelength input of the ultrasonic wave. be.

In summary, as the frequency increases, the thickness of the vibrating body becomes thinner, and the width must be correspondingly narrower in order to get closer to the piston sound source, but it is difficult to configure such vibrating bodies in an array. is accompanied by difficulties in manufacturing technology. In addition, in order to improve the azimuth resolution and also increase the scanning line density, it is possible to configure one acoustic aperture with multiple vibrators, but in order to suppress the grating lobes that occur at this time, the spacing between the elements of the vibrator must be adjusted. It is necessary to make it less than the wavelength of ultrasonic waves, which also involves difficulties in manufacturing technology-1. Furthermore, electronic focusing to further improve azimuth resolution is
This produces woody quantization sidelobes.

In order to realize such a high-frequency superficial tissue scanner, it is necessary to appropriately select the electroacoustic transducer material and to solve problems in microfabrication technology.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an ultrasonic tomography apparatus for superficial tissues that can eliminate the drawbacks of the prior art and can obtain high-resolution tomographic images.

According to the present invention, there is provided an electroacoustic transducer for mutually converting an electrical signal and an ultrasonic wave, and an electroacoustic transducer that is driven to transmit an ultrasonic wave that is reflected from a subject and detected by the electroacoustic converter. A transmitting/receiving circuit that receives an electrical signal corresponding to the ultrasound, a visual hydraulic means that visually displays an image corresponding to the received electrical signal, an electroacoustic transducer, a transmitting/receiving circuit, and a visual hydraulic means that control the ultrasound of the subject. In an ultrasonic tomography apparatus including a control circuit for performing acoustic tomography, the electroacoustic transducer includes a transducer array including a plurality of vibrating bodies that transmit and receive ultrasound, each vibrating body transmitting and receiving ultrasound. The thickness in the direction is smaller than the length in the direction perpendicular to the direction, the ultrasonic wave is output at a relatively high frequency, and the control circuit performs linear scanning of ultrasonic transmission and reception by sequentially driving a plurality of vibrating bodies.

According to one feature of the present invention, the frequency of the ultrasound is determined by the near-field sound field in the superficial tissue of the living body when the ultrasound is output from the surface of the living body as an object into it by the electroacoustic transducer. The frequency is set high enough to form a

According to one feature of the present invention, the vibrator array includes two rows of arrays in which vibrating bodies are linearly arranged, and the vibrating bodies of both arrays vibrate at 7j intervals in each of the 7 rays between the two arrays. The arrays are shifted by a length equal to substantially half the array pitch of the bodies.

According to one feature of the invention, the electroacoustic transducing means includes acoustic lens means for focusing the ultrasound waves in front of the vibrating body.

According to one feature of the invention, the two arrays are arranged such that the directivity centers of both arrays in the slice direction intersect with each other within the near field.

According to one feature of the present invention, the video output means displays the video in real time at a predetermined frame rate, and the control circuit controls the electroacoustic conversion means, the transmission/reception circuit, and the video output means at the frame rate, and The vibrating body is sequentially scanned at a speed such that the ultrasonic waves reflected by the superficial tissues are detected by the electroacoustic transducer, and the image transmission means performs signal processing on the image.

According to one feature of the invention, the signal processing includes video S/
Includes processing to increase the N ratio.

According to one feature of the invention, the signal processing includes processing to increase the number of scan lines of the video.

According to one feature of the present invention, the transducer array includes a plurality of arrays arranged to slice the subject and obtain a plurality of slice tomographic images in the azimuth direction.

(Nnn, 1,41 mita) IIl. Embodiments of the ultrasonic tomography apparatus according to the present invention will be described in detail with reference to the drawings accompanying the detailed description of the invention and method of operation.

Referring to FIG. 3, in an embodiment of an ultrasonic tomography apparatus according to the present invention, a high frequency probe 100 for superficial tissue includes an array 104 of 16 transducers 102 of electroacoustic transducer material and a corresponding A switch 106 provided as
and has.

The switch circuit 10f1 is a transmitting/receiving circuit 1 that transmits ultrasonic waves of a predetermined frequency and receives echoes reflected from the subject.
10. This transmitting/receiving circuit 110 has functions for one channel in this embodiment. Transmission/reception circuit 1
The signal received at 10 undergoes necessary signal processing at a received signal processing circuit +12, and is converted into a video signal at a video circuit 114. This video signal is displayed as a visible image on a video display device such as a cathode ray tube (CRT), that is, a monitor 1 18 .

The operation of each of these circuits is controlled by control circuit 118.

The entire operation of this apparatus is based on so-called B-mode tomography using normal ultrasound pulses. In order to obtain a tomographic image in a relatively deep part of a living body, a transducer usually has an acoustic aperture of 10 to 15 mm to improve the directivity of transmitted and received ultrasound waves. However, such a large aperture is not necessary in order to obtain ultrasonic tomographic images of shallow parts of a living body, that is, superficial tissues. For example, even if it is limited to areas such as the thyroid and carotid artery,
It is sufficient that the target diagnostic depth can be photographed to a depth of about 3CI11 from the human body surface, and it is considered that the target tissue exists approximately at a depth of 1 to 2 cm from the epidermis. Further, it is considered that a scanning width of about 3 to 5 cm is sufficient.

As described above, in the case of a circular ultrasonic transducer, the diameter of the ultrasonic beam is approximately equal to the acoustic aperture in the range of distance D 72 from the vibrating body, which is approximately a near-field sound field. Therefore, the wavelength of the ultrasonic wave, that is, the frequency f, and the diameter of the aperture may be selected so that this distance is about 2 to 3 cm.

0 people 1C & white) Yes. In this way, it is possible to select the optimum f and D according to the aforementioned diagnostic depth D/2λ.・First time, ＾I East 2 (71↓Kite J Yugako Riki ゛1Q gate drunken party).

The azimuth resolution depends on the beam diameter due to the nature of the near-field sound field, so the smaller the aperture diameter, the better it becomes. Further, the distance resolution becomes better as the frequency f becomes higher. therefore,
If D is made smaller and f is made higher, both resolutions will improve.

However, the near-field sound field, that is, the depth of diagnosis, becomes shorter as D becomes smaller and f becomes higher, so there are limits to the values of D and f from this point of view. In addition, at high frequencies, the attenuation of ultrasonic waves in the living body increases, and furthermore, due to the limitations of the dynamic range of the electronic circuits connected to this, the depth of diagnosis is reduced by 1. limited.

For example, as shown in Figure 5, if the attenuation in the soft tissue of a living body is approximately 1 dB/cm MHz, the higher the frequency f, the greater the amount of attenuation inside the living body.If the dynamic range is 100 dB, the frequency of ultrasound f is approximately 18 MHz at a diagnostic depth of 3 cm and approximately 25 M at a diagnostic depth of 2 cm)
z is the limit. Conversely, at 20MHz, the depth is about 2.
Diagnosis is possible up to 5 cm.

- For example, when f is 15 MHz and the aperture diameter is 2 mm, the beam diameter is 2-mm up to a depth of 2 cm, and even at a depth of 3 cm, the beam diameter is only 3 mm. The half width is 1.4mm for a circular aperture and 1.2+nm for a rectangular aperture.
It is. For example, if 16 such vibrators are arranged in an array, an array with a total length of 32 mm can be constructed, and about 3 c
A scanning width of about n+ can be achieved.

Returning to FIG. 3, the control circuit 118 sequentially energizes the switches 106 and turns on the switches S1 to SI8 in sequence at the timing shown in FIG. 6. As a result, the 16 transducers 102 in FIG. 3 are sequentially scanned from left to right, and at each timing, ultrasound is transmitted and its echoes reflected inside the living body are received.

In conventional linear scanning, a plurality of transducers for eight channels, for example, are driven at the same time, and the driving is shifted one channel at a time to perform scanning. Only one transducer 102 is driven, and the transducers 102 are sequentially shifted one channel at a time. If it is driven up to the IB channel, it will be driven again from channel 1,
Scans can be repeated. For example, scan depth 3
0 mm, the scanning width is 32 mm with 16 channels, and the sound velocity CM in the living body is 1.500 tn/sec, the time required to scan one frame is 640 microseconds. Generally, real-time display of tomographic images is performed at a rate of about 6 frames per second, so the time required to scan 17 frames is about 16.7 milliseconds. Therefore, in this embodiment, scanning is completed in the required time of approximately 1/26.

The remaining time in this 1-frame period can be used for various signal processing in the signal processing circuit 112. This will be detailed later. The received signal image-processed by the signal processing circuit 112 in this way is converted into a video signal in the video circuit 114, and the display device 1
By performing brightness modulation at 18, the image is displayed as a visible image in so-called B mode in Table 4. Furthermore, since this embodiment does not provide an electronic focus function, one of the features is that there is no need for a delay circuit to provide a phase delay to the transmitted and received signals, which was required in the conventional linear electronic scanning method. be.

Various signal processing may be performed at times other than the scanning in one frame period described above. For example, by averaging the received signals for multiple frames, the S/N
The ratio can be improved. For example, in the above example, if the averaging operation is performed 28 times within l frame period, S
/N ratio is improved by about 5 times. Further, even if the scanning interpolation method described later is performed in parallel during the averaging operation, the averaging operation can be performed 13 times within one frame period.

In the surplus time of scanning at a high frame rate, real-time scanning of a plurality of cross sections may be performed. This includes a plurality of transducer arrays A1. as shown in FIG. A
2 and A3. This probe 20'O has a switching circuit 202, and the eighth
As shown in the timing diagram of the figure, under the control of the control circuit 110, the signal J-lines So 1 , SO 2 ,
An energizing signal is sequentially supplied to So and So3. Therefore, from switches Sl of array A1 to S16 . Switches S1 to S18. of array A2. Switches S1 to S of array A3
The switches 10B are activated in order such as IB, and the corresponding vibrators 102 are sequentially driven. Note that although three columns of arrays A1 to A3 are shown in this example, this is just an example and does not limit the present invention. It is clear that it is possible.

The arrays A1 to A3 are arranged in the azimuth direction indicated by arrow B, that is, in the direction perpendicular to the slice direction, as shown in FIG. Therefore, when driven sequentially as described above, three scanning slices 210, 2
Tomography can be performed on 12,214.

In the example above, this required time is 1,920 microseconds. Therefore, the average calculation is performed 8 times in one frame period.
It can be done twice. Furthermore, even if a scanning line interpolation operation is performed that interpolates the scanning line every two slices, the result is 2,5
Since the process is completed in f(0 microseconds), the averaging can be performed six times.

By applying this method, it is basically possible to display multiple cross sections simultaneously in real time. In addition, so-called C mode display is also possible, and by combining these,
It is also possible to display tomographic images three-dimensionally.

As shown in FIG. 10, such signal processing may be performed by providing a digital memory 300 for temporarily storing video signals on the output side of the video circuit. This may realize a freeze function that temporarily freezes the scanned image.

FIG. 11 shows an example of a probe 400 that has an array 104 of 18 transducers 102 and is not provided with a switch circuit. In this embodiment, the transmitter/receiver circuit 40
2, each vibrator 102 is connected to the transmitter/receiver circuit 40 with multiple wires.
2 has a transmission function for 1B channel and a reception function for 1B channel. This allows a scan similar to that described for the embodiment of FIG. 3 to be performed.

As described above, the ultrasonic tomography apparatus according to the present invention does not use electronic focusing, so the circuit configuration is simple and site lobes do not occur due to this.
stomach. In other words, it basically has the same effect as a B-mode scanner using a single probe.

In such an ultrasonic tomography apparatus, in order to further improve the resolution, it is advantageous to increase the number of scanning lines and focus the ultrasonic beam.

Unless the number of scanning lines is increased, the number of scanning lines is generally equal to the number of transducers, and their spacing is equal to the transducer spacing P (Figure 2). The scanning line density is 5 trees/cm. Incidentally, the conventional linear electronic scanner has a rate of about 12 wood/cm.

Such sparse scanning line density may be interpolated using a data interpolation method. This is to interpolate intermediate pixel data between scanning lines of adjacent °2 trees by, for example, linear interpolation using signal processing operations in the signal processing circuit 112. According to this, as shown in FIG. 12, if the data of the k-th scanning line (indicated by the solid line 500) is Nk, then k
Data Nk (indicated by a dotted line 502) on the interpolated scanning line between the 1st scanning line and the 1st scanning line.
' is obtained by (Nk+Nk+1)/2.

Further, scanning lines may be increased by the following scanning interpolation method. According to this, scanning can be performed at intervals that are half the transducer pitch P.

Referring to FIGS. 13 and 14, arrays A1 and A
2, both arrays are arranged at relative positions shifted from each other by P/2 in the array direction, that is, in a direction perpendicular to arrow B, and are supported by a support 504. That is, the scanning line 506 output from array A] and the scanning line 506 output from array F, A
The scanning lines 510 outputted from the scanning lines 510 and 2 are arranged shifted by P/2 in the array direction. Moreover, as shown in FIGS. 15 and 16, the directivity of the v4 arrays A1 and A2 is such that the centers of the ultrasound beams intersect each other in the slice direction at, for example, about half of the diagnostic depth. Granted. Therefore, as can be seen from FIG. 16, the diameter of the beam is equal to the diameter of the aperture at position F. In this way, the resolution in the slice direction is made comparable to that in the azimuth direction B. This position F is the array AI and A2
It can be set arbitrarily by adjusting the orientation.

Furthermore, as shown in FIG. 17, acoustic lenses 600 may be provided in arrays ^1 and A2 to further improve resolution. The beam width in the slice direction is focused by this lens 6θO as shown in FIG. 18, and the region where the slice width is less than the aperture diameter is expanded as shown by Ll in the same figure. If this scanning interpolation method is combined with the scanning line increasing method described above, the scanning line density will be further doubled. Overall, therefore, the scan line density can be increased by a factor of 2 to 4.

Note that in these figures, the acoustic matching layer in the vibrator array is not directly related to the understanding of the present invention, and is therefore omitted to avoid complicating the figures.

The beam focusing method using such an acoustic lens is advantageously applied to the frozen flux of the ultrasonic beam.

As shown in FIG. 18, the ultrasonic small lobe
(on which the vibrator 102 is supported) an acoustic matching layer 700
is formed. In this embodiment, the single vibrator 102 is in the form of a rectangular parallelepiped with an aperture and a slice width, as shown in FIG. 20 ('A). The slice width may be equal to the aperture, as shown in FIG. 2(B). In this way, the ultrasonic tomography apparatus according to the present invention can have the same resolution in the slice direction and in the azimuth direction.

In conventional linear electronic scanners, an acoustic lens can only be applied in the slice direction due to the scanning method, but in the ultrasonic tomography apparatus according to the present invention, an acoustic lens can be provided for each individual transducer. . Therefore, the focused sound field is superior in quality compared to the electronic focusing method.

The acoustic lens 600 shown in FIG. 21 is of a convex type,
The acoustic lens 610 shown in FIG. 22 is of a concave type.

These have a circular planar shape as shown in (B) of these figures, but may also be rectangular in the azimuth direction B and semicylindrical shape as shown in FIG. Of course, this may be concave.

Those corresponding to FIG. 21 or 23 are as shown in FIG. 24, and those corresponding to FIG. 22 are as shown in FIG. 25.
As shown in the figure, let the radius of curvature of the convex surface 620 and concave surface 622 be rl and r2, respectively, and the sound velocity in the lens material be vl and v2, respectively, then rl=F・(1
−n) = F −(1−c/vl) r2= F・(1−n) =F・(1−c/v2). However, C is the speed of sound in the living body 710.

In addition, in the concave type, n<1(v>c) and r is II mi,
In the convex type, n>1 (v<c) and r is negative. -For example, C for about 1,500 meters in 7 seconds and F for 10 mm.
As a convex lens material! is 1, and using silicone rubber at 100 m/s, n = 1.38.1
= 3.8mm, and v2 is 1 for the concave lens material.
1 when using polycarbonate at 800 meters/sec.
1 = 0.83, r = 1.7mm.

An acoustic lens having such a shape can be easily manufactured by molding or the like, and it is advantageous to manufacture a lens that is integrally molded with the number of elements required for the vibrator array.

IV. Specific Effects of the Invention The ultrasonic tomography apparatus according to the present invention can obtain tomographic images of superficial tissues with high resolution without using electronic focusing.

More specifically, since no electronic focusing is used, sidelobes due to quantization do not occur, and a concave transducer and acoustic lens form a focused sound field.
The transducer material can approximately constitute a piston sound source by making the width larger than the thickness. Therefore, excellent ultrasonic sound field characteristics can be created.

In particular, since ultrasonic waves can be transmitted and received with good directivity in a high frequency region of about 10N)12 or more, it can be particularly effectively applied to tomography of superficial tissues.

In addition, compared to conventional linear electronic scanners, there is no need to cut each vibrator material into small pieces; in other words, the width of the vibrator is wide and the number of vibrators is small, making it easier to process probes and wire electrodes. Manufacturing advantages are also significant. Furthermore, no circuit is required to form electronic focus;
Since the number of channels for transmission and reception is small, the circuit configuration is simple, and the number of cables connecting the device main body and the probe can be connected to a small number, which simplifies the device configuration.

Furthermore, because of the high scanning rate, there is a considerable margin in the scanning period of one frame, so various signal processing such as averaging pixel signals over multiple frames and simultaneous scanning of multiple cross sections can be performed in real time. I can do it.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams for explaining the basic principle of the ultrasonic tomography apparatus according to the present invention, FIG. 3 is a block diagram showing an embodiment of the ultrasonic tomography apparatus according to the present invention, and FIG. 5 is a graph for explaining the ultrasonic propagation characteristics of the ultrasonic probe used in the embodiment shown in FIG. 3, and FIG. 6 is a timing diagram showing the operation of the embodiment shown in FIG. 3. 7 and 8 are block diagrams and timing diagrams showing other embodiments of the present invention, respectively; FIG. 9 is a perspective view showing an example of a probe used in the embodiment of FIG. 7; FIG. 11 is a block diagram showing another embodiment of the present invention. FIG. 12 is an explanatory diagram for explaining the increase in scanning lines by the data interpolation method applied to the ultrasonic tomography apparatus according to the present invention. 25 are explanatory diagrams for explaining the configurations of various probes applied to the ultrasonic tomography apparatus according to the present invention. Color = 1 100, Ultrasonic probe 102, Transducer 104, Transducer array 110, Transmitting/receiving circuit ■+2. ．． ．． +2. ．． ．． Reception path 1ift...Video monitor 118...Control circuit eoo...Acoustic lens Patent applicant Chillsen Co., Ltd.Figure 22Figure 23(B)Figure 24Figure 25

Claims (1)

[Scope of Claims] (1) An electroacoustic transducer that performs mutual conversion between an electrical signal and an ultrasonic wave, and an electroacoustic transducer that drives the electroacoustic transducer to transmit an ultrasonic wave and transmit the electroacoustic wave reflected from a subject. a transmitting/receiving circuit that receives an electrical signal according to the ultrasonic wave detected by the converting means; An ultrasonic device comprising: a video means for visually displaying an image according to the received electric signal; and a control circuit for controlling the electroacoustic conversion means, the transmitting/receiving circuit, and the video hydraulic means to perform ultrasonic tomography of the subject. In the acoustic tomography apparatus, the electroacoustic transducer includes a transducer array consisting of a plurality of vibrating bodies that transmit and receive ultrasonic waves, and the vibrating bodies have a thickness in a direction perpendicular to the direction in which the ultrasonic waves are transmitted and received. Ultrasonic tomography, characterized in that the ultrasonic wave is smaller than the length of the ultrasonic wave and has a relatively high frequency, and the control circuit sequentially drives the plurality of vibrating bodies to perform linear scanning of ultrasonic wave transmission and reception. Device. (2) The frequency of the ultrasonic wave is such that when the electroacoustic transducer outputs the ultrasonic wave from the surface of the living body as the subject into the body, a near-field sound field is formed in the superficial tissues of the living body. The ultrasonic tomography apparatus according to claim 1, wherein the ultrasonic tomography apparatus is set to a reasonably high frequency. (3) The vibrator array includes two rows of arrays in which vibrating bodies are linearly arranged, and the vibrating bodies in one array are mutually arranged between both arrays at a substantial pitch of the vibrating bodies in each array. The ultrasonic tomography apparatus according to claim 2, wherein the ultrasonic tomography apparatus is arranged so as to be shifted by a length equal to half. (4) The ultrasonic tomography according to claim 2 or 3, wherein the electroacoustic conversion means includes an acoustic lens means for focusing the ultrasonic waves in front of the vibrating body. Photography equipment. (5) The two rows of arrays are arranged so that the directivity centers of both arrays in the slice direction intersect within the range of the near sound field. The ultrasonic tomography apparatus η according to scope 3. (The video output means displays the video in real time at a predetermined frame rate, and the control circuit controls the electroacoustic conversion means, the transmission/reception circuit, and the video output means at the frame rate, and A patent claim characterized in that the vibrating body is sequentially scanned at a speed such that the ultrasonic waves reflected by the tissue are detected by the electroacoustic converting means, and the image outputting means performs signal processing on the image. (7) The ultrasonic tomography apparatus according to claim 2, wherein the signal processing includes processing to increase the S/N ratio of the image. Sonic tomography apparatus. (a) The ultrasonic tomography apparatus according to claim 6, wherein the signal processing includes processing to increase the number of scanning lines of the image. (9 ), the transducer array includes a plurality of arrays arranged so as to slice the subject and obtain a plurality of slice tomographic images in the azimuth direction. Sonic tomography device.