JPH0332372B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a convex type ultrasound diagnostic device, and in particular, a convex type ultrasound diagnostic device, which is capable of reducing multiple reflections when displaying a tomographic image of the heart on a display using ultrasound. The high-quality, wide observation field of view relates to a convex type ultrasonic diagnostic device configured to obtain ultrasonic tomographic images, etc.

[Problems to be solved by conventional technology and invention]

Conventionally, as a cardiac ultrasound diagnostic apparatus, a phased array type probe is used as shown in FIG. 6, and the drive and reception phase of each transducer 1-1 is controlled in the scanning direction indicated by the arrow in the figure using a delay circuit 2. There were some that performed so-called sector scans, which controlled the direction of the object and determined the observation direction as a result. When observing a tomographic image of the heart using the cardiac ultrasound diagnostic apparatus having the above configuration, for example, the ultrasound reflected from the transducer 1-1 in the direction of the reflector 3-1 in FIG. As shown by the dotted line, the ultrasonic wave returned in a so-called reflected form is detected using the transducer 1-1 and displayed on the display. Therefore, if there is a reflector 3-2 located parallel to the flat-shaped vibrator 1-2 placed at the tip of the probe as shown in FIG. The ultrasonic waves reflected by the transducer 1-2 and the reflector 3-2 are repeatedly reflected between the two, and the corresponding ultrasonic waves are reflected at positions twice, three times, etc. There was a problem in that the reflector 3-2 was displayed on the display as if it existed as a virtual image.

Specifically, a heart with a right ventricle and a left ventricle covered by the pericardium as shown in FIG. 8 is inserted into a flat vibrator 1-1 as shown in FIG. , 1-2 is used to emit ultrasonic waves, and the reflected signals are detected as shown in FIG. In FIG. 9, the vertical axis represents the amplitude (intensity) of the ultrasonic waves detected by the transducers 1-1 and 1-2, and the horizontal axis represents time. Vibrator 1-
Ultrasonic waves emitted from 1 and 1-2 toward the heart are strongly reflected in the area where the central membrane is located in FIG. 9. In the right ventricle shown below, there should be almost no reflections due to the presence of blood, but there is a virtual image (reflected between the pericardium and transducers 1-1 and 1-2) shown using the dotted line in the figure. ) may be detected.
Similarly, since there is blood in the left ventricle, there should be almost no reflection, but a virtual image indicated by the dotted line in the figure may be detected. In this way, when conventional flat transducers 1-1 and 1-2 were used, the transducers 1-1 and 1-2 were connected to a reflector that caused a strong reflection that existed in or near the heart. There was a problem in that a virtual image was generated due to repeated reflections between the two.

On the other hand, a so-called convex type probe in which a transducer 1-3 is disposed in a part of a cylinder as shown in FIG. 10 has come to be used for observing tomographic images of the abdomen. The purpose of this is that the linear probe 1-4 conventionally used for the abdomen has a wider field of view near the body surface 4, as shown by the solid line in Figure 12, compared to the sector scan shown by the dashed line. Although an image can be obtained, the disadvantage is that even if you move away from the body surface 4 in the depth direction, you can only obtain a field of view of a certain width. The objective is to secure a wide field of view at a distance in the direction shown by the dotted line in the figure. Therefore, the ultrasonic diagnostic equipment used to observe tomographic images of the abdomen, etc., is, by its nature, capable of observing the heart, which is protected like a bird in a cage by the ribs, which is the object of the present invention. Unlike conventional devices, there are generally fewer restrictions on the position of the transducers 1-3 in contact with the object to be observed (abdomen), and moreover, it is possible to obtain a tomographic image with a wide field of view at a position close to the body surface 4 and a wider field at a deeper position. Since it is desirable to observe a tomographic image of the field of view, the radiation center "O" from which the ultrasonic waves are emitted is located at the transducer 1 as shown in FIG.
It is located above -3. Therefore, when used to observe a tomographic image of the heart, which is the object of the present invention, the radiation center of the ultrasonic wave is located at the upper part of the body surface, for example, at the radiation center "O ₂ ", as shown in FIG. However, since the radiation center "O ₀ " cannot be approached close to the body surface 4, the field of view is restricted by the ribs 5 shown using diagonal lines in the diagram, making it difficult to observe. .

In addition, the conventional convex probe for the abdomen has a sufficiently small curvature to prevent repeated reflections as shown in Figure 7.
This is not done because it conflicts with the purpose of obtaining a tomographic image with a wide field of view at a position close to the curvature of several tens of millimeters. This degree of curvature is not sufficient to diffuse the reflected waves and minimize multiple reflections as indicated by the arrows in FIG. However, since the abdomen does not have a reflector near the body surface that produces a strong reflection like the pericardium that covers the heart, there is no practical problem even if the abdomen has the current curvature.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention has provided that when displaying a tomographic image of the heart etc. on a display using ultrasound, a vibrator for emitting and detecting ultrasound is spread around approximately half the circumference of a cylindrical surface. By arranging the transducers in parallel, the center of ultrasonic radiation is lowered, the probe is made smaller, the field of view is not limited by the ribs, and high-quality tomographic images of the heart can be obtained without multiple reflections. Therefore, the convex-type ultrasonic diagnostic apparatus of the present invention is a convex-type ultrasonic diagnostic apparatus that displays an image on a display using a convex-type probe in which a transducer is arranged on the outer surface of a cylindrical surface. A probe in which each element piece is arranged approximately halfway around the outer surface of a cylindrical surface, and a probe with the center of the cylindrical surface as the scanning center.
a selection circuit that selects the element pieces within a range of 90° as one group and sequentially selects predetermined element pieces to perform odd/even scanning and supplies power for emitting ultrasonic waves; It is characterized by being configured to obtain a scanning angle of approximately 90°.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a block diagram of one embodiment of the present invention, Fig. 2 is a block diagram of main parts of the vibrator shown in Fig. 1, and Figs.
The figure is an explanatory view for explaining the manufacturing method of the vibrator shown in FIG. 1, and FIG. 5 is a diagram showing the configuration of another essential part of the vibrator shown in FIG.

In the figure, 6 is a vibrator, 7 is a display, 8 is a display circuit, 9 is a phase control circuit, 9-1, 9-3 are drivers, 9-2, 9-4 are receivers, 9-5 is a switch, 10 11 is a scanning selection circuit, 11 is a control circuit,
12 is an electrode, 13-1, 13-2 are relay electrode plates,
14 is an adhesive layer, 15 is a connection film, 16 is a Teflon frame, 17 is a matching layer, 18 is a front matching layer, 19 is a back matching layer, 20 is wax, 21 is a sound absorber, 22
is a support, 22-1 is an electrode pattern, 23, 23
-1 represents an adhesive, 24 represents a support type, and 25 represents a lens.

FIG. 1 shows the configuration of a convex-type cardiac ultrasound diagnostic apparatus that displays tomographic images of the heart, and the transducer 6 in the figure is related to the present invention. The vibrator 6
As will be described later, they are arranged to cover approximately half the circumference of the cylindrical surface, and each element (element piece) constituting the vibrator 6 is connected to a scan selection circuit 10, respectively.
The scan selection circuit 10 receives the illustrated gate signal from the control circuit 11 and the driver 9 in the phase control circuit 9.
-1, 9-3, etc. The so-called odd/even element groups located within an angle of approximately 90 degrees that constitute the vibrator 6 are arranged in the order of element groups 1 to n as shown in the figure. Scanning is in progress. In this way, in order to display a tomographic image of the heart, etc., the transducer 6 is used, which is arranged to cover approximately half the circumference of the cylindrical surface. The generation of virtual images is prevented,
In addition, by lowering the emission center of the ultrasonic waves emitted from the transducer 6 and making it smaller, it is possible to display high-quality tomographic images of the heart with a wide field of view even when inserted between the narrow ribs. It can be displayed.

Further, among the ultrasonic waves emitted toward the heart from the transducer 6, those that are reflected and returned are detected by the transducer 6 and sent to the receivers 9-2, 9- in the phase control circuit 9. After passing through a delay circuit selected by a predetermined tap to determine a desired focus, the received ultrasonic signal is subjected to known predetermined processing such as amplification, addition, detection, and TGC using switches 4 and 9-5. be exposed. Then, the signal subjected to the predetermined processing is supplied to the display circuit 8. The display circuit 8 receiving the supply displays a tomographic image of the heart, etc. on the display 7. At this time, from the control circuit 11
Odd/even signals, transmission timing signals, etc. are notified to the phase control circuit 9, and signals are supplied to each element constituting the transducer 6 to generate a predetermined ultrasonic wave so as to perform odd/even scanning. Detection, etc. are controlled in a so-called synchronous manner. Further, the scanning line number signal is notified to the display circuit 8, and control is performed so that a predetermined tomographic image of the heart or the like is displayed. A detailed explanation will be given below.

First, the aforementioned odd/even scanning will be explained using FIG. 1. In the odd/even scan, first, as shown, a signal is sent to a group of elements 1 corresponding to an angle of approximately 90°, for example, to generate ultrasonic waves.
Second, a signal is sent to the element group 2, which is formed by adding one extra element piece in the scanning direction of the element group 1, to generate ultrasonic waves. Third, a signal is sent to the element group 3, which is obtained by cutting off one element piece at the rear end in the direction opposite to the scanning direction in the element group 2 used during the second step, to generate an ultrasonic wave. Thereafter, the first to third steps are repeated in sequence. Almost as above
Since signals for generating ultrasonic waves are sequentially supplied to element groups 1 to n, each consisting of element pieces within 90°, the minimum scanning step width obtained by the odd/even scanning is is half the minimum step width of each element, and the normal number of scanning lines can be obtained with the half circumference of the cylindrical surface, which is limited to observing the heart from the ribs. This makes it possible to satisfy the essential conditions for optimizing the grating lobe of the ultrasonic beam.

FIG. 2 shows a configuration diagram of the essential parts of the vibrator 6 in FIG. 1, and the element pieces constituting the vibrator 6 are arranged over half the circumference of the cylindrical surface. As described above, the element pieces are supplied with signals for emitting ultrasonic waves for each element group corresponding to approximately 90 degrees. For example, when a signal for emitting ultrasonic waves is supplied to a group of element pieces indicated by S ₊₄₅ in the figure, an ultrasonic wave having an envelope indicated by P ₊₄₅ in the figure is generated. Similarly, when signals for emitting ultrasonic waves are supplied to a group of element pieces indicated by S ₀ and S _-45 in the figure, P ₀ and P _-45 in the figure are respectively supplied.
Ultrasonic waves are generated having envelopes shown using . Therefore, if the known odd/even scanning is performed sequentially over the range of +45° to -45° in FIG.・Scan angle +
It can be performed over a range of 45° to -45°.
In other words, the number of sectors is twice the number of element pieces that make up the vibrator 6. Scan from +45° to -
It can be performed over a 45° range (90°), achieving a cardiac sector scan with a normal number of scan lines, and an ultrasound beam with good temporal resolution and no grating lobes. In addition, since the element pieces constituting the transducer 6 are arranged approximately half the circumference of the cylindrical surface, it is small enough to be inserted between the ribs to display a tomographic image of the heart, etc. In addition, since the ultrasonic radiation center O is located near the body surface, a high field of view of approximately 90° is not obstructed by the ribs. Further, according to this configuration, the curvature is reduced and a high-quality image without multiple reflections can be obtained, as will be specifically shown below with numerical values.

For example, the center frequency is 3.5MHz, the aperture l is 10mm,
The number of scanning lines is approximately 110, and grating/
Optimize on the condition that the probe hardly appears in the image. First, the radius a (curvature) of the vibrator is approximately 7 mm from l=2πa/4 (1). In addition, due to the condition that the grating probe does not appear in the image, the aperture
It is desirable to divide the image by 40 to 70, and since we want to obtain about 110 scanning lines, 48 to 64 divisions are appropriate. The number of scanning lines n at this time is determined by n=m×2 (m: number of divisions) (2), and is approximately 96 to 128 lines. On this occasion,
It uses the known odd/even scan. With the above configuration, a compact convex probe with a small size (probe radius of approximately 7 mm) and a wide field of view (approximately 90 degrees) that is sufficient to be inserted between the ribs of an adult and display a tomographic image of the heart, etc. can be created. can get. In addition, when displaying tomographic images of children's hearts, etc., an even smaller device is required, but the diagnostic depth is 50 mm or more.
Since the depth can be as shallow as about 100 mm and the center frequency can be set to 5 to 7 MHz, the aperture can be narrowed and the probe can be made even more compact.

3 and 4 respectively show methods of manufacturing the vibrator 6, the former shows a method in which a front matching layer is used as a support for the vibrator 6, and the latter shows a method in which a back matching layer is used as a support for the vibrator 6. Show what you used. This will be explained below.

FIG. 3A shows a plan view, and FIG. 3B shows a front view.

In the figure, a vibrator (for example, PZT) 6 has a flat plate shape, and electrodes 12 are provided on both sides of the flat plate shape. At both ends of the vibrator 6, there are relay electrode plates 13- made of ceramic, glass, epoxy, etc.
1 and 13-2 are bonded together by an adhesive layer (epoxy or the like) 14. Then, from the surface, a third
An electrically conductive connecting film 15 is formed so as to have a shape (staggered shape) as shown by diagonal lines in FIG. The connection film 15 is formed by sputtering, vapor deposition, plating, or the like.

FIG. 3C shows the front matching layer 18 and the back matching layer 1.
9 is shown.

In the figure, the Teflon frame 16 is connected to the relay electrode 13 as shown.
-1 and 13-2, and in order to form a matching layer 17 in the middle, a matching material made by mixing metal powder with epoxy and adjusting the acoustic impedance to an appropriate level is poured. After the epoxy is cured, it is cut and polished at a position indicated by a dotted line in the figure, that is, at a distance d corresponding to 1/4 of the wavelength λ of the ultrasonic wave to be generated. This produces a front matching layer 18. Similarly, a back matching layer 19 is formed on the back surface of the vibrator 6.

FIG. 3D shows how the vibrator 6 is separated into each element (element piece).

The front matching layer 18 of the generated vibrator 6 is fixed to a workbench using wax 20 in the figure. Then, a die sink machine is used to make a cut from the upper part of the figure, that is, from the side of the back matching layer 19 to the position of the front matching layer 18 shown by the dotted line in the figure. The incisions are made at the positions indicated by the arrows in FIG. 3A, and the connecting films 15 are also separated in a staggered manner. As a result, by connecting the lead wires to the staggered separated positions and connecting them to the scan selection circuit 10 in FIG.
Even scanning can be done.

FIG. 3E shows the completed probe housed in the support mold 24. The probe is made by bending the vibrator 6 produced as shown in FIG. included,
It is hardened. The amount of adhesive 23 is minimized so as not to get between the elements. In the above manufacturing process, the front matching layer 18 left uncut in the operation shown in FIG. 3D is placed on the outer surface of the cylindrical surface as shown in FIG. The element is held by the front matching layer 18 and does not fall apart, resulting in high workability.

FIG. 4A shows how the vibrator 6 is separated into each element (element piece), and corresponds to that shown in FIG. The difference is that it is fixed to . Others are third
This is the same as the case in Figure D.

Figure 4b shows the completed probe. Also the fourth
Figure C is a sectional view taken along line A-A' in Figure 4B. The probe includes each element piece constituting the vibrator 6 produced as shown in FIG. Solder by bending it according to the shape. The soldering is performed on the previously soldered parts of the relay electrode plates 13-1 and 13-2 of the vibrator 6 and on the cylindrical support frame 22 that holds the vibrator 6. Hold the electrode pattern 22-1 in a state that matches the relay electrode plate 13.
-1, 13-2 and the support frame 22 are heated to a temperature higher than the melting temperature of the solder. The vibrator 6 is fixed to the support frame 22 by the soldering. Next, a sound absorber 21 made of a mixture of epoxy, metal oxide, etc. is poured and hardened.
At this time, before pouring the sound absorber 21,
It is preferable to seal it using an adhesive 23 such as epoxy so that 1 does not leak. As described above, since the back matching layer 19 left uncut in the operation shown in FIG. 4A is placed on the inner surface as shown in FIG. 4B,
During the manufacturing process, each element piece constituting the vibrator 6 is held by the back matching layer 19 and does not come apart, resulting in good workability.

The resulting probes shown in FIGS. 3E and 4B are made into practical probes by bonding a lens 25 for focusing the ultrasonic beam in the so-called thickness direction perpendicular to the scanning direction. At this time, adhesive 2
3, 23-1 is desirably applied as thinly as possible. In particular, in the case shown in FIG. 4B, the adhesive 23-1 is prevented from entering between the elements.

FIG. 5 shows the characteristics of a probe configured so that an air gap exists without filling the area around the vibrator 6 with a sound absorber 21 or the like. By employing this configuration, interference between the elements constituting the vibrator 6, particularly interference due to the influence of lateral vibration of adjacent elements, is reduced. For this reason, conventionally, when the space between the vibrators 6 is filled with the sound absorber 21, the directional characteristic has a discontinuous part as shown by the solid line in FIG.
So-called side lobes (produced by the directivity of individual elements) were likely to occur. but,
In this embodiment, air is used to acoustically isolate each element constituting the vibrator 6.
Since the gap is provided, the side lobes are not generated as shown by the dotted line in FIG. 5, so a smooth continuous curve is obtained, and the side lobes are not generated.
High-resolution images can be obtained using ultrasound beams that are not located in the lobes.

〔Effect of the invention〕

As explained above, according to the present invention, when displaying a tomographic image of the heart on a display using ultrasound, the transducer that emits and detects the ultrasound is arranged over approximately half the circumference of the cylindrical surface. Therefore, it is possible to lower the radiation center of the ultrasound emitted from the transducer and downsize the transducer to obtain high-quality tomographic images of the heart that have a wide field of view and do not cause multiple reflections. can.

[Brief explanation of drawings]

Fig. 1 is a block diagram of one embodiment of the present invention, Fig. 2 is a block diagram of main parts of the vibrator shown in Fig. 1, and Figs.
The figures are an explanatory diagram for explaining the manufacturing method of the transducer shown in Fig. 1, Fig. 5 is a configuration diagram of other main parts of the transducer shown in Fig. 1, and Fig. 6 is a diagram of a conventional convex type cardiac ultrasound diagnostic apparatus. FIGS. 7 to 9 are explanatory diagrams for capturing the operation of the configuration shown in FIG. 6. FIG. 10 is an explanatory diagram for explaining the operation of another conventional convex type cardiac ultrasound diagnostic apparatus. Figure, 11th
The figure is an explanatory diagram capturing the operation of the configuration shown in FIG. 10,
FIGS. 12 and 13 are explanatory diagrams illustrating the operation of a conventional convex-type ultrasound diagnostic apparatus for the abdomen. In the figure, 6 is a vibrator, 7 is a display, 8 is a display circuit, 9 is a phase control circuit, 9-1, 9-3 are drivers, 9-2, 9-4 are receivers, 9-5 is a switch, 10 11 is a scanning selection circuit, 11 is a control circuit,
12 is an electrode, 13-1, 13-2 are relay electrode plates,
14 is an adhesive layer, 15 is a connection film, 16 is a Teflon frame, 17 is a matching layer, 18 is a front matching layer, 19 is a back matching layer, 20 is wax, 21 is a sound absorber, 22
is a support frame, 22-1 is an electrode pattern, 23, 23
-1 represents an adhesive, 24 represents a support type, and 25 represents a lens.

Claims (1)

[Claims] 1. In a convex-type ultrasound diagnostic device that displays images on a display using a convex-type probe in which a transducer is placed on the outer surface of a cylindrical surface,
A probe in which each element piece constituting the vibrator is arranged approximately halfway around the outer surface of a cylindrical surface, and the element pieces within a range of approximately 90° with the center of the cylindrical surface as a scanning center are selected as one group. with odd/even
A convex type ultrasonic device comprising a selection circuit that sequentially selects predetermined element pieces for scanning and supplies power for emitting ultrasonic waves, and is configured to obtain a scanning angle of approximately 90°. Sonic diagnostic equipment.