JPS6340974Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ultrasonic diagnostic apparatus using pulse echo method.

The operations of conventional ultrasonic diagnostic apparatuses can be broadly classified into sector scan type and linear scan type.

FIG. 1 is a diagram showing an example of scanning using the sector scan method. In FIG. 1, numeral 1 represents a transducer array for transmitting and receiving ultrasonic waves, 2 represents a subject such as a human body, and l ₁ to _lo represent ultrasound beams. The sector scan method performs sector scanning based on the principle of a phased array using a combination of electronic delay means, but this method usually requires a different delay for each scanning line, corresponding to each element of 16 to 64 elements. . Also, since wide-angle scanning requires a large amount of delay,
The disadvantage is that the electronic circuit becomes complicated. Furthermore, when using this sector scan method for abdominal diagnosis, the first
As shown in the figure, the field of view near the skin is narrow, making it unsuitable for abdominal diagnosis.

FIG. 2 is a diagram showing an example of scanning using the linear scan method. In FIG. 2, 1 is a transducer array, 2
is a human body, and l ₁ to _{l o} represent ultrasound beams. This linear scan method does not have the above-mentioned drawbacks, but has the drawback that the lateral field of view in the deep part is narrow because the field of view in the deep part is approximately equal to the width of the probe as shown in FIG. In addition, if the frequency of the ultrasound used to increase the resolution of images is increased, the pitch of the transducer array must be made finer.
In order to increase the frequency while maintaining the same field of view, the number of oscillators must be increased. Another drawback of the linear scan method is that when a long transducer array is used to widen the field of view, the contact with the human body becomes poor.

The present invention improves the drawbacks of the above conventional examples,
The present invention provides an ultrasonic diagnostic device that has a simple structure and is suitable for diagnosing the abdomen.

FIG. 3 is a diagram showing an example of an ultrasonic diagnostic apparatus according to the present invention. In FIG. 3, C is a clock generator, T ₁ and T ₂ are delay circuits, and M ₁ and M ₂ are selection switch circuits. This selection switch circuit M ₁ ,
_M2 is composed of something like a multiplexer, for example, and has a function of distributing drive pulses so that a group of vibrators can be selectively excited from the vibrator array described below. D is a transmitting/receiving circuit that excites the transducer, receives the ultrasonic echo received by the transducer, and transmits it to the next stage. H denotes a vibrator, and a plurality of vibrators are arranged in a convex shape to form a vibrator array. Details of this convex array of transducers will be described later. Although the transmitting/receiving circuit D is shown as one block in FIG. 3, it is actually a set of transmitting/receiving circuits corresponding to each vibrator H. A is an amplifier that has the function of adding and logarithmically amplifying the signals from the delay circuits. B is CRT
Display the ultrasound tomogram. A control circuit S controls the selection switch circuits M ₁ , M ₂ and CRT B. The output of clock generator C is introduced into selection switch circuit _M1 via delay circuit _T1 . The output of the selection switch circuit _M1 is connected to each vibrator H via a transmitter/receiver circuit D. Another output of the transmitter/receiver circuit D is introduced into a selection switch circuit _M2 , and the output of this selection switch circuit _M2 is introduced into the CRT B via a delay circuit _T2 and an amplifier A. A control circuit S into which the output of the clock generator C is introduced controls the selection switch circuits M ₁ , M ₂ and the CRT B.

The apparatus of FIG. 3 constructed in this way operates as follows. A clock pulse is generated from the clock generator C and input to the delay circuit _T1 . delay circuit
At T ₁ , pulses corresponding to the number of transducers in a group selected from the transducer array are output. That is, when one clock pulse is input, for example, N pulses are output in parallel from the delay circuit _T1 . In the selection switch circuit _M1 , a delay circuit is connected to N oscillators to be excited from the oscillator array.
A pulse from T ₁ is applied via the transmitter/receiver circuit D. Therefore, ultrasonic waves are transmitted from N transducers, but due to the principle of a phased array that is electronically delayed by a delay circuit _T1 , each of these N ultrasonic waves is transmitted to a certain point in front of the transducer array. It works to focus on one point. In addition, if we define the focused ultrasound beam as the ultrasound beam equivalent to the one oscillated from the mechanical center of the N excited vibrators as the central ultrasound beam, in this invention, the ultrasound beam at the center is A phased array is applied so that the sound wave beam is oriented in the normal direction of the transducer array.

The ultrasound transmitted in this manner is received by the transducer H as an echo signal from the subject, and is introduced into the selection switch circuit _M2 via the transmitting/receiving circuit D.
The configuration of the selection switch circuit _M2 is almost the same as that of the selection switch circuit _M1 . That is, only the echo signals received by the N transducers described above out of the large number of transducers constituting the transducer array are extracted and introduced into the next stage delay circuit _T2 . Further, this echo signal is added and logarithmically amplified in amplifier A, and displayed as a single scanning line on the CRT. Note that the echo signal is generally displayed on a CRT after being luminance-modulated depending on its magnitude.

The above operation is for one clock pulse, but the above operation is repeated every time this clock pulse is oscillated, and the excited transducer is shifted one after another and transmits an ultrasonic beam to complete one frame. A tomographic image of minutes is displayed on CRT B.

FIG. 4 is a perspective view showing an example of a vibrator array that can be used in the circuit of FIG. 3. Reference numeral 1 denotes a vibrator array, which has a structure in which a large number of vibrators are arranged and a general linear scan type vibrator array is curved into a convex shape, as shown in FIG. 3 is an ultrasonic absorber, which has the effect of absorbing ultrasonic waves directed toward the back side.

Figure 5 shows that using the transducer array of Figure 4,
FIG. 3 is a diagram showing the state of an ultrasonic beam when scanning according to the present invention described above is performed. In Figure 5, 1
is a transducer array, 2 is a human body, and l ₁ to _{l o} are central ultrasound beams. Note that the examples shown in FIGS. 5 to 8 show cases in which three vibrators are excited as a group of vibrators, and the ultrasonic absorber 3 shown in FIG. 4 is omitted. . As shown in FIG. 5, the ultrasonic beams l ₁ to _lo at each center are transmitted in the normal direction to the convex curved surface.

FIG. 6 shows an improved version of the vibrator array section shown in FIG. 4. That is, in order to improve contact with the body surface, a layer of a material having characteristics close to the sound speed and acoustic impedance of the human body is provided, so that it can be brought into close contact depending on the body surface. In FIG. 6, 1 and 2 are the same as in FIG. 4 is a case, the surface of which comes in contact with the human body is made of a thin film made of rubber, polyethylene, etc., and 5 is the above-mentioned substance (for example, water).

FIG. 7 shows an improved version of the vibrator array section shown in FIG. 4. In FIG. 7, 1 and 2 have been explained in FIG. 5, so their description will be omitted. 6 is a matching layer. This matching layer 6 is made of a material (such as silicone rubber) that has an acoustic impedance close to that of the human body and a sound velocity lower than that of the human body, and improves contact by making the contact portion nearly flat, and by refraction at the body surface. This allows for a wider field of view.

FIG. 8 is a diagram showing an example of the configuration of the vibrator array section of the device according to the present invention. FIG. 8 is an example in which the curvature of the convex vibrator array is not uniform, and the curvature of the peripheral portion is larger than that of the central portion. With such a configuration, as shown in FIG. 8, the scanning line density in the center of the ultrasound beams l ₁ to _lo is distributed to be higher than in the periphery. Therefore, high-resolution, high-quality images can be obtained in the central area, and in the peripheral area, where resolution is not required, a wide angular range, that is, the entire organ or its relative position to other parts, can be examined. It is very effective.

In FIG. 9, the vibrator array has a concave curved surface in the thickness direction, so that the beam in the thickness direction is focused as shown in FIG.

As explained above, according to the present invention, a wide range of images suitable for abdominal examination can be obtained with a simpler circuit configuration than the conventional sector scan method. Furthermore, it is possible to obtain images over a wider range in the depths of the examination than with the conventional linear scan method, and the convex shape of the transducer array allows close contact with the human body.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of scanning using the sector scan method, FIG. 2 is a diagram showing an example of scanning using the linear scan method, FIG. 3 is a diagram showing an example of an ultrasound diagnostic apparatus according to the present invention, and FIG. 4 is a diagram showing an example of scanning using the linear scan method. Fig. 3 is a perspective view showing an example of a transducer array that can be used in the circuit; Fig. 5 is a diagram showing the state of an ultrasonic beam when scanning according to the present invention is performed using the transducer array shown in Fig. 4; 6 and 7 are diagrams showing an improved version of the transducer array shown in FIG. 4, FIG. 8 is a diagram showing an example of the configuration of the transducer array section of the device according to the present invention, and FIG. This is a modification of FIG. 4. C...clock generator, _T1 , _T2 ...delay circuit,
_M1 , _M2 ...selection switch circuit, D...transmission/reception circuit, H...vibrator, A...amplifier, S...control circuit, B...CRT.

Claims (1)

[Claim for Utility Model Registration] A large number of tanzaku-shaped vibrators are arranged side by side so that the center part is more convex than the peripheral part, and the curvature of the peripheral part is larger than the curvature of the central part. a transducer array connected to each transducer; a selection switch circuit for selecting a group of transducers from the transducer array; a delay circuit configured to focus the ultrasonic beam and deflect the central ultrasonic beam so that the direction is normal to the convex curved surfaces of the group of transducers; and means for adding and logarithmically amplifying the received echo signals. , visualizing the output signal of the logarithmically amplifying means;
An ultrasound diagnostic device characterized by being equipped with a CRT.