JPH10248842A - Ultrasonograph device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-resolution tomogram using an aperture combining method using an ultrasonic probe by enabling the ultrasonic probe to be constructed at relatively low cost. SOLUTION: An ultrasonic probe main body 1 has a plurality of piezoelectric transducers 5-1 to 5-3 placed around an outer periphery inside a columnar, ratable piezoelectric transducer protection case 4, and transmits and receives ultrasonic waves as the piezoelectric transducers 5-1 to 5-3 are rotary driven by a rotary driving part 7. Imaging at a rotary cross section is effected by an aperture combination observing device 2 using an aperture combing method based on the input signals of the ultrasonic waves obtained from the piezoelectric transducers 5-1 to 5-3, to obtain a high-resolution ultrasonic tomogram, with a convex type B-mode tomogram displayed on a monitor display 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus for obtaining a tomographic image of a living body by transmitting and receiving ultrasonic waves, and more particularly, to an ultrasonic diagnostic apparatus using an aperture synthesis method.

[0002]

2. Description of the Related Art Conventionally, in the medical field, an ultrasonic pulse has been repeatedly transmitted from an ultrasonic transducer into a living tissue.
The echoes of the ultrasonic pulse reflected from the living tissue are received by the same or separate ultrasonic transducers, and by gradually shifting the direction of transmitting and receiving the ultrasonic pulse, a plurality of There have been proposed various ultrasonic diagnostic apparatuses which obtain an ultrasonic tomographic image of a visible image based on information collected from a computer and display the image.

In an ultrasonic diagnostic apparatus, an aperture synthesis method is one of the methods for improving the resolution of an ultrasonic tomographic image. As an apparatus using the aperture synthesis method, for example, US Pat.
No. 325,257 and Japanese Patent Laid-Open No. 5-92002 disclose the configuration.

[0004]

In the above-described ultrasonic diagnostic apparatus using the conventional aperture synthesizing method, the vibrating elements arranged in an array are electrically switched to move the transmitting / receiving vibrating elements. Had a configuration. Then, after storing a reflection signal captured at a spatial position in each tomography in a memory, a tomographic image is generated from the reflection signal by a synthesis process based on an aperture synthesis algorithm.

In such a conventional configuration, the use of an array of vibrating elements causes the number of signal lines from each of the vibrating elements to increase to, for example, 128, making it difficult to connect the vibrating elements to the signal lines. Since the configuration of the element switching means is complicated, there is a problem that the cost of the ultrasonic probe is increased. Further, there is a problem that the array-shaped vibrating element itself is expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to configure an ultrasonic probe at a relatively low cost, and to obtain a high-resolution tomographic image using the aperture synthesis method using the ultrasonic probe. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing the above.

[0007]

According to the present invention, there is provided an ultrasonic diagnostic apparatus, comprising: at least one vibrator disposed on a rotatable rotating body and having an emitted ultrasonic beam spread in a rotational direction; A rotation drive unit that rotates a rotating body including: a transmission / reception control unit that transmits / receives ultrasonic waves by driving a vibrator in accordance with a rotational position of the vibrator; And a tomographic image generating means for performing imaging in a rotational section by aperture synthesis based on the received signal.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

An ultrasonic diagnostic apparatus includes an ultrasonic probe main body 1 for transmitting and receiving ultrasonic waves for diagnosis, and an ultrasonic probe main body 1.
Aperture observation device 2 as tomographic image generation means connected to the aperture synthesis observation device 2 for generating a tomographic image by an aperture synthesis method based on the received ultrasonic signal, and a monitor display connected to the aperture synthesis observation device 2 for displaying the tomographic image And a container 3.

The ultrasonic probe main body 1 includes a vibrator protection case 4 as a cylindrical and rotatable rotator, and a plurality of ultrasonic probe bodies (herein, provided at an outer peripheral portion inside the vibrator protection case 4) for transmitting and receiving ultrasonic waves. 3) vibrators 5-1, 5-2, 5-3
A slip ring 6 connected to signal lines from the transducers 5-1 to 5-3 to transmit an ultrasonic signal;
-1 to 5-3.

In the conventional ultrasonic diagnostic apparatus based on the aperture synthesis method, the vibrators to be transmitted and received are switched and moved by using an array of vibrating elements, whereas in the present embodiment, the vibrating elements are mechanically rotated. It is configured to move the transducer for transmission and reception.

At the time of diagnosis, the exterior of the vibrator protection case 4 is brought into contact with the living tissue 8 at the site to be diagnosed, and the vibrators 5-1 to
An ultrasonic beam 9 is emitted from each of the transducers 5-1 to 5-3 while rotating the 5-3, and a reception signal by an ultrasonic echo from the living tissue 8 is obtained and output to the aperture synthesis observation device 2. At this time, the vibrator protection case 4 is pressed against the living tissue 8 to partially adhere to the living tissue 8, and the ultrasonic beam 9 propagates in the living body within this range. A tomographic image is generated by the aperture synthesizing observation device 2 based on the reception signal of the ultrasonic wave which has propagated back into the living body and is displayed on the monitor display 3. The tomographic image displayed on the monitor display 3 is an image of only a portion that is in close contact with the living tissue 8, and is therefore a convex B-mode tomographic image.

The transducers 5-1 to 5-3 have small dimensions in the rotation direction, and the ultrasonic beam 9 generated by the transducer becomes a fan beam spread in the rotation direction. on the other hand,
The ultrasonic beam 9 is narrowed down because it has a length of, for example, about 1 cm in the rotation axis direction. Vibrator 5 rotating
Performing a synthesis operation by the aperture synthesis method in the aperture synthesis observation device 2 based on the ultrasonic reception signal obtained by repeatedly transmitting / receiving the ultrasonic beam 9 according to the rotation positions of -1 to 5-3. Then, an ultrasonic tomographic image of the inside of the living body at the rotational section of the transducer is generated.

FIG. 2 shows the configuration of the ultrasonic diagnostic apparatus according to the present embodiment in more detail. The ultrasonic probe body 1 includes a plurality of transducers 5-1 to 5-3 described above.
, A slip ring 6 having a plurality of channels, and a motor 10 serving as a rotation drive unit 7.

A signal line from the slip ring 6 is connected to a transmitting pulsar 12 and a receiving amplifier 13 via a switch 11, and the vibrators 5-1 to 5 are connected by the switch 11.
The oscillator to be driven is selected from -3. For example, a pulse signal is transmitted by the transmission pulsar 12 and the vibrator 5-1 is transmitted.
To transmit the ultrasonic beam 9 by the ultrasonic pulse into the living body. Then, the ultrasonic pulse reflected in the living body is received by the transducer 5-1 and input to the reception amplifier 13 as a reception signal, amplified by the reception amplifier 13 to a required size, and then converted to an A / D converter. At 14, the signal is converted into a digital signal and stored in a memory in the aperture synthesis operation circuit 15.

At this time, the vibrators 5-1 to 5-3 are rotationally driven by the motor 10 at, for example, about 30 revolutions per second (1800 RPM). Further, assuming that the transmission interval of the ultrasonic pulse is 150 μsec and one quarter of the circumference of the vibrator is in contact with the living tissue 8, 55 effective reception signals can be obtained by the following equation (1). become. Number of valid reception signals n = (1/30) / 150 μsec / 4 = 55 (1)

The motor 10 is driven and controlled by a motor drive circuit 16. The motor drive circuit 16 and the transmission pulsar 12 are controlled by a timing control circuit 17.
The timing of the rotation of the transducers 5-1 to 5-3 and the transmission of the ultrasonic pulse is controlled by a timing control circuit 17.
Is controlled by An adjuster 18 is connected to the timing control circuit 17, which will be described in detail later.
The image quality can be adjusted by finely adjusting the rotation speeds and transmission intervals of the vibrators 5-1 to 5-3 by the adjuster 18.

Since the vibrators 5-1 to 5-3 perform transmission / reception while rotating, the received signals obtained for each transmission are signals obtained in slightly different spaces. Vibrator 5-1
When .about.5-3 has made one rotation, the aperture synthesis operation circuit 15 performs a synthesis operation by an algorithm using a well-known aperture synthesis method as in the conventional example, thereby obtaining a reflection image of the tomographic plane. This reflected image is input to a digital scan converter (DSC) 19, coordinate conversion and interpolation are performed by the DSC 19 to adjust the display format, and output to the monitor display 3. A fan-shaped tomographic image is displayed on the monitor display 3 as an ultrasonic tomographic image of the diagnosis target site. At this time, the operation timing of the aperture synthesis operation circuit 15 and the DSC 19 is controlled by the timing control circuit 17.

By repeating transmission and reception using a plurality of transducers 5-1 to 5-3 using transducers having exactly the same characteristics, it is possible to obtain three frames of reflected images while the entire transducer makes one rotation. If the number of rotations is the same, the frame rate of the ultrasonic tomographic image can be improved according to the number of transducers.

As described above, according to the present embodiment, transmission and reception of ultrasonic waves are repeatedly performed while rotating a plurality of transducers having the same characteristics, and a reception signal of the ultrasonic waves is obtained. By setting the frame period, reflected images corresponding to the number of transducers can be obtained within one frame period, so that substantially the same operation as in the case of scanning using an array of vibration elements can be obtained. Thus, a tomographic image with higher resolution can be obtained.

Therefore, in the ultrasonic diagnostic apparatus using the aperture synthesizing method, even with the configuration using the mechanical vibrator switching / moving means as in this embodiment, one or more vibrators are rotated. By transmitting and receiving ultrasonic waves and performing imaging on a rotating cross section based on the aperture synthesis method based on multiple received signals in different scanning spaces, a high-resolution tomographic image can be obtained and at the same time, the ultrasonic probe can be simplified With a simple structure, it can be configured at a relatively low cost.

FIGS. 3 and 4 relate to a second embodiment of the present invention. FIG. 3 is an explanatory diagram showing the focal depth and beam characteristics of a plurality of transducers in the direction of the rotation axis, and FIG. It is an operation explanatory view showing an ultrasonic tomographic image combined with a reflection image.

In the ultrasonic diagnosis using the aperture synthesis method, focusing can be performed with high resolution on the scanning section of the transducer, but on a section perpendicular to the scanning section, the resolution is determined by the beam shape created by the acoustic lens of the transducer. It has been determined that high resolution cannot be maintained over a short distance to a long distance. Therefore, a configuration example for solving such a problem will be described below.

In the second embodiment, a plurality of transducers 5-1 to 5-3 in the configuration shown in FIG. An example of a configuration for obtaining an image is shown. The configuration of each unit of the ultrasonic diagnostic apparatus is the same as that of the first embodiment, and a description thereof will not be repeated.

The depth of focus f1 of the vibrator 5-1 in the rotation axis direction
Is set to, for example, 30 mm, and the focal depth f2 of the vibrator 5-2 is set to 50 m.
m, the depth of focus f3 of the transducer 5-3 is set to 70 mm, and a rotationally driven ultrasonic probe using a plurality of transducers having different focal depths in the rotation axis direction is configured. FIG. 3 shows the beam characteristics of these transducers 5-1 to 5-3 in an overlapping manner. Here, A1 indicates the opening length of the vibrator 5-1 in the rotation axis direction, A2 indicates the opening length of the vibrator 5-2, and A3 indicates the opening length of the vibrator 5-3. As the depth increases, the opening length increases.

While rotating the vibrators 5-1 to 5-3 having such a configuration, the vibrators having different focal depths are switched by the switch 11, and the aperture synthesizing operation circuit 15 performs the aperture synthesizing operation on each of the portions near the focal point. For a reflective image. Then, as shown in FIG. 4, in the DSC 19, reflection images of a plurality of depth ranges by the transducers are joined to create a final ultrasonic tomographic image.

As described above, by using a plurality of transducers having different focal depths, it is possible to switch the transducers in the direction of the rotation axis to obtain a more precise reflection image in a wide depth range, and to synthesize the aperture in the direction of the rotation section. Thereby, a high-resolution tomographic image can be synthesized. Therefore, imaging with excellent spatial resolution is possible not only in the rotational section of the vibrator but also in the rotational axis section.

As a modified example of the second embodiment, the center frequency of the ultrasonic waves transmitted from the plurality of transducers 5-1 to 5-3 is made different, for example, to set the center frequency of the transducer 5-1 to 7. 5 MHz, the center frequency of the vibrator 5-2 is 5.0 MH
z, the center frequency of the vibrator 5-3 is 3.5 MHz,
If each transducer is switched by the switch 11, one ultrasonic probe main body can easily cope with many frequency bands.

In the ultrasonic diagnostic apparatus, the ultrasonic probe is replaced according to the site to be observed, and a frequency of 3.5 MHz is used for deep observation of the liver and the like, and a frequency of 7.5 MHz is used for shallow observation of the thyroid and the like. It is common. For this reason, in order to perform a wide range of diagnosis, it is necessary to prepare several probes, and there is a problem that replacement thereof is troublesome and a holder for accommodating the probes is required.

Therefore, by using a plurality of transducers 5-1 to 5-3 having different frequency characteristics as described above, the center frequency can be switched by one ultrasonic probe to cope with multiple frequencies, and therefore, a part to be diagnosed can be used. Frequency can be easily selected according to the above, the operability can be improved by eliminating complicated operations such as replacement of the ultrasonic probe at the time of diagnosis, and an ultrasonic probe capable of performing a wide range of diagnosis with an inexpensive configuration can be realized.

FIG. 5 is an operation explanatory view showing a change in beam characteristics of an ultrasonic wave due to a change in the rotation speed of the transducer according to the third embodiment of the present invention.

In the conventional ultrasonic diagnostic apparatus, if the distance between the array-shaped vibrating elements is large, unnecessary beams called grating lobes are generated in a direction other than the desired direction even if the beam is synthesized by aperture synthesis. It is visualized as a virtual image. In addition, if the interval between the array-shaped vibrating elements is small, the main beam in the desired direction becomes thick and the resolution deteriorates. Since the distance between the array-shaped vibrating elements is fixed, the beam characteristics of the ultrasonic wave cannot be changed according to the diagnosis site. Therefore, a configuration example for solving such a problem will be described below.

In the third embodiment, in the configuration of FIG.
A configuration example in which the rotation speed of the vibrator is made variable while the transmission interval of the ultrasonic pulse is kept constant by the adjuster 18 will be described. The configuration of each unit of the ultrasonic diagnostic apparatus is the same as that of the first embodiment, and a description thereof will not be repeated.

FIG. 5 is a table showing how beam characteristics in the plane of rotation of ultrasonic waves to be synthesized by the aperture synthesis method by changing the rotation speed of the vibrator are shown.

When the transmission and reception of ultrasonic waves are repeated while the vibrator is rotated, and the arithmetic processing of aperture synthesis is performed, it is almost equivalent to scanning at a pitch P indicated by the vibrator spacing of the vibrating elements in an array. At this time, if the rotation speed V of the vibrator is high, the pitch P becomes large as shown on the left side of FIG.
Generates grating lobes but narrows main lobes. Therefore, in this case, a high-resolution tomographic image is obtained although a virtual image is generated. On the other hand, when the rotation speed V is low, the pitch P becomes small as shown on the right side of FIG. Therefore, in this case, a high-quality tomographic image is obtained although the resolution is reduced.

Accordingly, by changing the rotation speed V of the vibrator and equivalently changing the pitch P of the vibrator, it is possible to change the beam characteristics of the ultrasonic waves to be synthesized by the aperture synthesis method.

The image quality of the generated tomographic image is adjusted by changing the rotational speed of the vibrator by the adjuster 18 in accordance with the part to be diagnosed in consideration of the ultrasonic beam characteristics as shown in FIG. Therefore, an optimal ultrasonic tomographic image according to the situation can be obtained, and a good diagnosis can be performed.

According to the present embodiment, by making the transmission interval of ultrasonic waves constant and making the rotation speed of the vibrator variable,
By changing the pitch of the transducers equivalently, the beam characteristics of the ultrasonic waves to be synthesized by the aperture synthesis method can be changed, and it is possible to perform optimal imaging according to the diagnosis site.

In the above embodiment, the configuration example in which three vibrators are incorporated in the rotating body has been described. However, the present invention is not limited to this, and can be similarly realized by one or more vibrators. Also, 1
A plurality of transducers having different depths of focus and a plurality of transducers having different frequencies can be incorporated in one ultrasonic probe.

Further, in the present embodiment, the configuration has been described in which the ultrasonic probe main body is pressed against the living tissue to generate a convex ultrasonic tomographic image. For example, it is possible to create an all-radial ultrasonic tomographic image.

[Supplementary Notes] (1) At least one vibrator disposed on a rotatable rotating body and having an emitted ultrasonic beam spread in a rotating direction, and a rotation drive for rotating the rotating body including the vibrator. Unit, transmission and reception control means for transmitting and receiving ultrasonic waves by driving the vibrator according to the rotational position of the vibrator, by aperture synthesis method based on the received signal of the ultrasonic wave obtained from the rotating vibrator An ultrasonic diagnostic apparatus comprising: a tomographic image generating unit that performs imaging on a rotating cross section.

(2) The vibrator is composed of a plurality of vibrators having different focal lengths arranged along the rotation direction of the rotator, and has a switch means for switching the plurality of vibrators. 7. The ultrasonic diagnostic apparatus according to claim 1, wherein

(3) The vibrator is composed of a plurality of vibrators having different frequency characteristics arranged along the rotation direction of the rotating body, and has a switch means for switching the plurality of vibrators. 7. The ultrasonic diagnostic apparatus according to claim 1, wherein

(4) A rotating speed varying means for changing a rotating speed of a rotating body provided with the vibrator and changing a beam characteristic of an ultrasonic wave to be synthesized by an aperture synthesizing method. 2. The ultrasonic diagnostic apparatus according to 1.

[0045]

As described above, according to the present invention, an ultrasonic probe can be constructed relatively inexpensively, and a high-resolution tomographic image utilizing the aperture synthesis method can be obtained with this ultrasonic probe. There is a possible effect.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to the embodiment in more detail;

FIG. 3 is an operation explanatory view showing a depth of focus and a beam characteristic in a rotation axis direction of a plurality of transducers according to a second embodiment of the present invention.

FIG. 4 is an operation explanatory view showing an ultrasonic tomographic image obtained by combining reflection images in a plurality of depth ranges;

FIG. 5 is an operation explanatory view showing a change in beam characteristics of an ultrasonic wave according to a change in a rotation speed of a transducer according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe main body 2 ... Synthetic aperture observation apparatus 3 ... Monitor display 4 ... Transducer protection case 5-1-5-3 ... Transducer 6 ... Slip ring 7 ... Rotation drive part 11 ... Switch 12 ... Transmission pulsar 15 ... Aperture synthesis operation circuit 17 ... Timing control circuit 18 ... Adjuster 19 ... Digital scan converter (DSC)

Claims (1)

[Claims] 1. An at least one vibrator disposed on a rotatable rotator and having an emitted ultrasonic beam spread in a rotational direction, a rotation drive unit configured to rotate a rotator including the vibrator, and Transmission / reception control means for transmitting / receiving ultrasonic waves by driving the vibrator in accordance with the rotational position of the vibrator, and a rotational cross-section by an aperture synthesis method based on a received ultrasonic signal obtained from the rotating vibrator. An ultrasonic diagnostic apparatus, comprising: a tomographic image generating unit that performs imaging.