JPS59218143A - Ultrasonic examining 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] [Technical Field of the Invention] The present invention emits ultrasonic waves into a living body, detects reflected waves from within the living body, and generates a tomographic image of the body for biopsy based on this detection output. The present invention relates to an ultrasonic testing device that displays images for diagnosis.

[Technical background of the invention]

In medical ultrasound diagnostic equipment, an ultrasonic transducer emits ultrasonic waves into a living body, and the reflected waves of the ultrasound waves from within the living body are detected again by the ultrasonic transducer to create a tomographic image of the inside of the living body. is displayed for diagnosis.

The resolution of this ultrasound tomographic image can be roughly divided into two types: distance resolution and azimuth resolution.

Among these, the distance resolution is the resolution in the direction in which the ultrasonic waves propagate, and this is approximately determined by the pulse width of the ultrasonic waves emitted in a pulsed manner.

On the other hand, lateral resolution is the resolution within a cross section perpendicular to the propagation direction of the ultrasound, and this is the resolution of the transmitted ultrasound. - The distance is determined by the thickness of the wave and the receiving directivity of the receiving ultrasonic transducer. The thickness of the transmitted ultrasonic beam is determined by the directivity of the transmitting ultrasonic transducer; in other words, the azimuth resolution is determined by the directivity of the transmitting ultrasonic transducer and the receiving ultrasonic transducer. It is safe to say that it will be done.

Incidentally, in order to obtain an ultrasound tomographic image of a living body, it is necessary to scan an ultrasound beam within the living body. and,
There are two methods for scanning an ultrasound beam: a mechanical scanning method that moves an ultrasound transducer mechanically to scan the ultrasound beam, and an ultrasound probe that consists of a large number of micro ultrasonic transducers arranged side by side. For example, among these micro-ultrasonic transducers, several adjacent transducers centered around the desired ultrasonic beam emission position are selected as a set, and the ultrasonic beam distribution for this set of micro-ultrasonic transducers is An excitation pulse is given to each ultrasonic transducer with an appropriate delay time determined according to the radiation direction, focal position, etc., and the ultrasonic wave is excited and released from each of the excited ultrasonic transducers. An electronic scanning system capable of linear and sector scanning of an ultrasound beam by electrical control, which uses interference due to a phase difference between the ultrasound waves to obtain an ultrasound beam having the desired radiation position, radiation direction, and focal position. There are two types.

The electronic scanning method consists of emitting ultrasonic waves by giving a desired delay time to tiny strip-shaped ultrasonic transducers arranged in order to obtain high resolution, and converging the ultrasonic beam at a desired distance. Also during reception, a method is used in which a desired reception directivity is obtained by giving a desired delay to the reception signal of each micro ultrasonic transducer and then adding and synthesizing the signals.

In this case, the resolution can be improved in the direction in which the ultrasonic transducers are arranged, since the spread of the ultrasonic waves can be electronically controlled. Although the ultrasonic transducers are arranged with their longitudinal sides adjacent to each other, since there is no ultrasonic transducer row in the direction along the longitudinal sides, it is not possible to electronically control the spread of the ultrasonic waves.

For this reason, the ultrasonic transducer is generally made of silicone rubber or the like in the shape of a hook, and is equipped with a honor lens in front of the rectangular array of ultrasonic transducers to adjust the propagation time of the ultrasonic waves. The ultrasonic beam is focused in a direction perpendicular to the arrangement direction.

However, since it is possible to electrically control the delay time in beam focusing using electrical delay focusing, it is possible to converge or focus at a desired distance.
The focal point of an acoustic lens is a problem unique to that lens, so the focal point cannot be moved arbitrarily. Therefore, even if the focus can be arbitrarily set for one, if the focus is fixed for the other, the resolution will decrease outside the range where both focal positions match.

One idea to solve this problem is to use an ultrasonic probe with a two-element array in which minute ultrasonic transducers are arranged in a matrix, that is, like the eyes of a base. In this case, the focus can be set at any distance by controlling the delay time given to each micro ultrasonic transducer. However, to realize this, the electronic circuit becomes quite complicated, and it is extremely difficult to manufacture an ultrasonic probe with a matrix array, so it has not been put to practical use at all.

Therefore, increasing the azimuth resolution at a given distance cannot be achieved by the method using an acoustic lens as described above.

For diagnostic purposes, seeing an image at a desired depth with high resolution is an essential requirement for making a correct diagnosis, so there is a strong demand for technology that can overcome the limitations of the fixed focus provided by acoustic lenses. ing.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic examination apparatus that can converge at an arbitrary distance and thus display a high-resolution tomographic image over a wide diagnostic field of view. purpose.

[Summary of the invention]

That is, in order to achieve the above object, the present invention uses an ultrasonic probe having a plurality of ultrasonic transducers arranged in parallel, and excites a desired plurality of these ultrasonic transducers to generate an ultrasonic beam. The ultrasonic device transmits and receives reflected ultrasonic waves using a desired plurality of beams, obtains a video signal of the reflected ultrasonic waves by the ultrasonic beam from the received signal, and displays an ultrasonic image from this. In the sonic FI device, the ultrasonic probe has a main and sub-ultrasonic transducer group arranged in different directions so as to have different reception directivities. means for delaying and adding the reception outputs of the ultrasonic transducer pots used for reception so that the ultrasonic beam is converged at a desired depth, which is provided corresponding to each ultrasonic transducer group, and each of these delays and additions; The ultrasonic probe has main and sub-ultrasonic transducer groups with different directivity arranged in different directions. The main ultrasonic transducer group is used to converge at a desired depth in the arrangement direction, and reception is performed using the main and sub ultrasonic transducer groups, and the main and sub ultrasonic transducers are Obtain a received signal converged at a desired depth in the transducer array direction of each group, thereby obtaining received ultrasonic signals with different directivity for both the main and auxiliary ultrasonic transducer groups, and thereby The ultrasonic beam can be focused at any depth position in the transducer arrangement direction of both the main and sub-ultrasonic transducer groups, and the directivity of the main and sub-ultrasonic transducer groups is different. By multiplying both received signals, signals other than those in the area where the directivity overlaps are significantly attenuated, and the signal in the limited area can be extracted.Using this, the positional resolution is achieved at a desired depth position. It is possible to obtain high-quality ultrasound images.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, the principle of the present invention will be explained using a half-part model.

As shown in Figure 1 (IJ), it has a width a in the X-axis direction, is infinitely long in the y-axis direction, and has a focal point in the X-axis direction at a distance zO in the two-axis direction. Consider ultrasonic transducer PB4.This ultrasonic transducer P
The reception sensitivity characteristic P (zo) at a distance zO with respect to B can be approximately expressed as follows.

　Up Here, k is the wave number of the ultrasonic wave.

This situation is shown in FIG. 1(b). In this figure, the reception sensitivity is expressed by I, and the relationship I='1PX12 is shown.

As shown in this figure, the receiving sensitivity is uniform in the y-axis direction, but it changes in the form of an ai1xc function in the x-axis direction.

On the other hand, as shown in FIG. 1(C), it is infinitely long in the X-axis direction, has a width b in the y-axis direction, and is focused (convergent) in the y-axis direction at a distance ZQ in the two-axis direction.
Considering an ultrasonic transducer with , the reception sensitivity characteristic Py (Zo ) at a distance zO to this ultrasonic transducer can be expressed as in the first equation.

This situation is shown in FIG. 1(d). In this case, the reception sensitivity is uniform in the X-axis direction and changes in the form of a 5ine function in the Y-axis direction.

Now, the ultrasonic transducer PI3+ in Fig. 1(a) and the ultrasonic transducer PI3+ in Fig. 1(e)
) are arranged so as to virtually intersect at the origin (XO17G) as shown in Fig. 1(e), and by multiplying their respective outputs, the reception sensitivity characteristic shown in the following formula is obtained. .

The receiving sensitivity characteristic shown by this third equation is the first one.
It is figure (f). As shown in this figure, even though each ultrasonic transducer FBI, PB has uniform receiving sensitivity in the y-axis direction or the x-axis direction, by multiplying the outputs of both of them! It is possible to obtain reception sensitivity characteristics that are two-dimensionally limited within the +7 plane.

The present invention is an application of the above-mentioned principle, and uses two or more types of imagers with different receiving directivity to obtain the receiving sensitivity characteristics that are virtually difficult to obtain with one or a set of transducers, and the output thereof The azimuth resolution of the ultrasonic diagnostic apparatus can be improved by multiplying the .

Next, examples of the present invention will be described. FIG. 2 is a perspective view showing the structure of the ultrasonic probe 20 of this device. As shown in the figure, the ultrasonic probe 20 is made up of a plurality of ultrasonic transducers arranged in parallel in one direction. The longitudinal side of the ultrasonic transducer group 21 is sandwiched between the array-type ultrasonic transducer group 21 (hereinafter referred to as the main ultrasonic vibration group), which is widely known as a linear or sector electronic scanning ultrasonic probe. Array-type ultrasonic transducer groups 22, 2 are arranged on both sides so that the arrangement direction is orthogonal to the arrangement direction of the array-type ultrasonic transducer groups.
3 (hereinafter referred to as sub-ultrasonic transducer group).

In an electronic scanning type ultrasound probe, it is possible to electronically control the ultrasound beam to be arbitrarily converged in the array direction of the ultrasound transducer group, and it is also possible to control the reception directivity. Therefore, the above-described configuration makes it possible to utilize the principle explained in FIG. 1.

FIG. 3 is a block diagram showing the configuration of the apparatus of the present invention, and 20 in the figure is the aforementioned ultrasonic probe.

Further, 31 is a transmission delay circuit that delays the trigger pulse, and this transmission delay circuit 31 is designed to excite two sets of at most N ultrasonic transducers of the plurality of ultrasonic transducers in the ultrasonic probe 20. Then, at least N delay lines are provided. Each delay line is controlled by a control circuit (not shown) to give a necessary delay time to the ultrasonic transducer to be excited corresponding to each delay line according to the beam direction and convergence (focal point) distance. be. Reference numeral 32 indicates a sensor which is provided corresponding to each delay line and generates an excitation pulse for ultrasonic excitation in response to a trigger pulse obtained through the corresponding delay line, and reference numeral 33 is a switching circuit. .

This switching circuit 33 provides the output of the pulser 32 to a desired number N of the main ultrasonic transducer group 21 in the ultrasonic probe 20 during ultrasonic transmission. A desired set (N) of ultrasonic transducers is selected, and the corresponding noclusars of the pulsers 32, which are divided into N systems, correspond to the relative positions of each set of ultrasonic transducers. /4'Luther's multi-output excitation/
It has a function of providing a 4' pulse and, at the time of reception, transmitting each output of the ultrasonic transducer used for this transmission to the reception system. This switching circuit 33 operates under the control of the control device (not shown) according to the ultrasonic scanning position of the ultrasonic probe 20. The switching circuit 33 is connected to the nine (Q>N) vibration warning signal lines of the main ultrasonic transducer group 21, the output lines of the N systems of the noise generator 32, and the signal lines of the M system of the receiving system. For example, in the case of linear scanning, the S/T, S, Teng circuit 33 sequentially scans the main ultrasonic transducers 2 in units of, for example, N adjacent ones in the main ultrasonic transducer group 2.
Select 9N of the positions of the one-way side ends of 1, give the output of each Nofrusar corresponding to the N of Yarusa 32, and apply the selected N main ultrasonic vibrations. The output of each detected reflected wave is sent to the receiving system separately via this switching circuit 33 (M may be equal to or different from N), and the switching The circuit 33 sequentially shifts its position, for example, by one main ultrasonic transducer, each time the transmission and reception of ultrasonic waves is completed.
By selecting each piece as a unit, the ultrasonic beam can be linearly scanned.

34 is a preamplifier that separately amplifies the outputs of M systems given from this switching circuit 33, and s'
In order to form a desired reception directivity for each of the amplified outputs of the 9M systems, a reception delay circuit having a delay line group each having an appropriate delay time and the output of each delay line group is used. This is a reception delay and addition circuit composed of an addition circuit that adds and synthesizes. Here, the delay time of the delay line group is set by the control circuit (not shown) in accordance with a reception directivity command issued in correspondence with a desired reception directivity.

32 is a preamplifier that separately amplifies the received output of each transducer of the sub-ultrasonic transducer group 22 and 23 in the ultrasonic probe 20, and 38 is the amplified received output outputted separately. In order to form the desired reception directivity, the reception delay and addition circuit are formed by an adder circuit that adds and synthesizes the outputs of this delay line group, each having an appropriate delay time, and is functionally explained above. This is similar to the reception delay and addition circuit 35. 38 is a multiplier that receives the added outputs of both reception delay and adder circuits 35 and 37 and multiplies them; 39 is an amplitude correction circuit that corrects the amplitude of the output obtained by this multiplication; 4
0 is a signal processing unit that converts this amplitude-corrected output into a video signal, and 41 is a display unit that receives this video signal and displays it as an ultrasonic tomographic image.

Next, the operation of this device having the above configuration will be explained. In this apparatus, ultrasonic waves are transmitted using the primary ultrasonic transducer group 2 of the ultrasonic probe 20, and received using this and the sub ultrasonic transducer groups 22 and 23.

In other words, ultrasonic waves are transmitted by transmitting a desired N number of Q number of transducers in the main wave transducer group 21 to the switching circuit 33.
A delay time is set to focus on the desired focal point. Then, the signal is delayed by a reception delay line corresponding to each signal set to focus at a desired distance, and added, and the output after this addition is sent to the multiplier 38.
is input. Then, the multiplier 38 multiplies the power of both people.

The two inputs of the multiplier 38 each have a 90° difference in the arrangement direction of the ultrasonic transducers, and each receive directivity is only in one direction, but the directions are 90° different.

Therefore, when these two signals are multiplied, the directivity of the ultrasound beam during transmission, the area of the transducer used for reception among the main and sub-ultrasonic transducer groups 21 to 23, and the main and sub-ultrasonic transducer groups A sharp reception directivity corresponding to the focal length etc. at the time of reception of 21 to 23 can be obtained.

The multiplied output is amplitude-adjusted by the amplitude correction circuit 39, and then converted into a video signal by the signal processing unit 40 and given to the display unit 41 as an ultrasonic tomographic image. It is displayed at the screen position corresponding to the ultrasound beam transmission position at 0.

The scanning of the ultrasonic beam is performed by the main ultrasonic transducer group 21 in response to clock pulses that are sequentially output at predetermined timings.
This is done by controlling the switching circuit 33 so as to select N adjacent ones among them while shifting them by one transducer every time the transmission/reception of one ultrasound pulse is completed, and the ultrasonic excitation pulse is Delay circuit 31 for transmitting clock and clock pulses
The trigger pulse can be delayed by an unset delay time to each delay line obtained by applying the trigger pulse to each delay line.

In this way the ultrasound beam is scanned and the main.

The reflected waves are detected by the sub-ultrasonic transducer groups 21 to 23, and reception focus processing is performed, and after addition, multiplication processing as described above is performed, and the output after this multiplication is used to display on the display unit. Sharp ultrasonic tomographic images with good lateral resolution can be obtained.

As mentioned above, in this installation, the overall directivity of transmitting and receiving consists of the transmitting directivity by a group of N ultrasonic transducers used for transmitting, and the main and sub-directivity used for receiving with the arrangement directions different by 90 degrees. Ultrasonic section - receiving directivity determined by the product of the transducer group, that is, the directivity of the N transducers used for reception in the main ultrasonic transducer group 21 and the directivity of the sub ultrasonic transducer group 22 and 23. It is determined by the product of

In this device, not only the main ultrasonic transducer group 21 but also the focus of the sub ultrasonic transducer groups 22 and 23 are
Since the delay time can be set arbitrarily by the delay time set in the reception delay circuit in 2.23, it does not have a fixed focus unlike the convergence method using the acoustic lens e in conventional array-type ultrasonic probes. Since it can be set arbitrarily, reception processing can be performed to focus at a desired depth, including the convergence direction of the conventional acoustic lens, and moreover, the main and sub-ultrasonic transducer groups 21 to 23 with different convergence directions can be used. By performing the multiplication of the received signals, a desired steep directivity can be obtained, and a high-resolution image of the desired observation target region can be obtained. -Moreover, the sub-ultrasonic transducer groups 22 and 23 are arranged on both sides of the main ultrasonic transducer group 21.
The probe 20 is structurally simple and can be realized easily and inexpensively.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications within the scope of the gist thereof.For example, in the above embodiments, an example of linear electronic scanning is used. As explained above, it can also be carried out in sector electronic scanning.In addition to diagnostic use, this device can also be applied to inspect objects other than living bodies, such as destructive inspection.

〔Effect of the invention〕

As described above in detail, the present invention uses an ultrasonic probe having a plurality of ultrasonic transducers arranged in parallel, excites a desired plurality of these ultrasonic beams, and transmits an ultrasonic beam. At the same time, the ultrasonic reflected wave is received using a desired plurality of beams, and the received signal is used to obtain a video signal of the ultrasonic reflected wave by the ultrasonic beam and the ultrasonic image is displayed. In the ultrasonic inspection apparatus, the ultrasonic probe has a main and sub-ultrasonic transducer group arranged in different directions so as to have different reception directivities, and each of the main and sub-ultrasonic vibrations means for delaying and adding the received outputs of the respective ultrasonic probes provided corresponding to each child group and used for reception so that the ultrasonic beams are converged at a desired depth;

These delays and means for multiplying the added received outputs are used to construct the ultrasonic probe, and the ultrasonic probe has main and sub ultrasonic transducer groups with different directivity arranged in different directions. Transmission is performed by using the main ultrasonic transducer group to converge at a desired depth in the array direction, and reception is performed using the main and sub ultrasonic transducer groups, and the main and sub ultrasonic transducers are separated by delay processing of the received signal. Obtain a received signal focused at a desired depth in the transducer array direction of each acoustic transducer group, and use this to obtain
Obtain ultrasonic reception signals with different directivity from both sub-ultrasonic transducer groups, and thereby converge the ultrasonic beam at an arbitrary depth position in the transducer arrangement direction of the main and sub-ultrasonic transducer groups. However, by multiplying the received signals with different directivity from both the main and sub ultrasonic transducer groups, signals other than those in the area where the directivity overlaps are significantly attenuated and the signal is limited. Utilizing the ability to extract area signals, it is now possible to obtain ultrasonic images with high positional resolution at desired depth positions, making it possible to obtain high-resolution ultrasonic tomographic images of the desired examination target area. Therefore, in addition to enabling more accurate diagnosis and testing, the ultrasonic probe also uses a sub-ultrasonic transducer group whose arrangement direction is different from the main ultrasonic transducer group. It is possible to provide an ultrasonic inspection apparatus that is easy to manufacture because of the structure in which they are arranged close to each other, and that the circuitry of the reception system required for the sub-ultrasonic transducer group does not need to be complicated. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the invention in detail. FIG. 2 is a perspective view showing the structure of an ultrasonic probe according to the present invention, and FIG. 3 is a block diagram showing an embodiment of the present invention. 20... Ultrasonic probe, 21... Main ultrasonic transducer group, 22.23... Sub-ultrasonic transducer group, 31... Transmission delay circuit, 32... Luther, 3I...Switching circuit, 34.36...Preamplifier, 35.37.
... Reception delay and addition circuit, 3B... Multiplier. 39... Amplitude correction circuit, 40... Signal processing section, 41
...Display section.

Claims (2)

[Claims] (1) Using an ultrasonic probe consisting of a plurality of ultrasonic transducers arranged in parallel, a desired plurality of these ultrasonic transducers are excited to transmit an ultrasonic beam, and a desired plurality is used. In the ultrasonic M device, the ultrasonic M device receives an ultrasonic reflected wave from the ultrasonic beam, uses the received signal to obtain a video signal of the ultrasonic reflected wave from the ultrasonic beam, and displays an ultrasonic image. The sonic probe has a main and auxiliary ultrasonic transducer group arranged in different directions so as to have different reception directivities,
In addition, the reception outputs of the ultrasonic probes used for reception are delayed and added so that the ultrasonic beam is converged at a desired depth, which is provided corresponding to each of the main and sub-ultrasonic transducer tolerances. and a means for multiplying the respective delayed and added reception outputs, and the output after the multiplication is used as a video signal to display an ultrasound image. (2) A plurality of micro short fence-shaped ultrasonic transducers are arranged side by side in one direction to form a main ultrasonic transducer group, and the main ultrasonic vibration is carried out in a direction intersecting the direction in which the main ultrasonic transducer group is arranged side by side. Claim 1 is characterized in that an ultrasonic probe is used in which a plurality of ultrasonic transducers having a width substantially the same as the distribution width of the child group are arranged in parallel to form a sub-ultrasonic transducer group. ultrasonic inspection equipment.