JPH021246A - Ultrasonic tomographic examination apparatus - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a tomographic image by multiple reflection by arranging a phase arrangement piezoelectric vibrator group (PAL) and a linear arrangement piezoelectric vibrator group (LA) so as to relatively incline both of them in the plane crossing the scanning surface of ultrasonic beam at a right angle. CONSTITUTION:An LA 301 and a PAL 302 are arranged in mutually opposed relationship so as to have a predetermined angle theta relatively. As a result, for example, the ultrasonic beam 303 emitted from the LA 301 is received by the PAL 302 and a reflected signal 304 is absorbed by the sonic wave absorbing body 305 applied to the periphery of a variable delay apparatus to remove a multiple reflected signal. The PAL 302 is arranged so as to be inclined by the angle theta with respect to the LA 301 but, contrarily, even when the LA 301 is arranged so as to be inclined with respect to the PAL 302, the same effect is obtained. Further, it is unnecessary that the center 0 of the LA 301 ls present on the same line as the center AB of the PAL 382 and, after all, the return route of the reflected signal 304 to the LA 301 may be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic tomographic examination apparatus, and relates to an inexpensive and small fan-shaped electronic scanning type that scans an ultrasonic beam in a fan-shaped manner using simple means to obtain a fan-shaped ultrasonic tomographic image. We aim to provide an ultrasonic tomographic examination device (hereinafter abbreviated as ESU).

One method of constructing an ESU using simple means is disclosed in Japanese Patent Application Laid-Open No. 52-68492, which will be explained with reference to FIG. In FIG. 1, 101 is a subject such as a human body, 102 is a group of phased array piezoelectric vibrators for ESU (hereinafter abbreviated as PAL), and 103 is an analog variable delay line device, which is arranged in a concave shape with an acoustic propagation medium 105. Linear array piezoelectric vibrator group (hereinafter abbreviated as LA) 1Q
It consists of 6. A predetermined number of adjacent groups 107 of Li2O2 are excited by a selection switch connected to each piezoelectric vibrator, and the Li2O2 becomes an ultrasonic beam 108 that propagates through the propagation medium 105, and the PAL 104 and PA
An ultrasonic beam is sent into the subject 101 via L102. On the other hand, the reflected beam from the object 101 passes through the same route as in the case of transmission and returns to the group 10 of the L module 106.
7, and then undergoes normal signal processing and is then displayed as an image. Deflection of ultrasonic waves in the subject 101 is performed by element selection by five people 106.

In the above conventional configuration, the E
Compared to the SU, the variable delay section is significantly simplified as shown in FIG. Considering that the variable delay section was the main reason why conventional KSUs were expensive and had large equipment casings, it is possible to provide a smaller KSU at a lower price with the above configuration. It can be seen that it has

On the other hand, in the above configuration, the analog variable delay line device 103
Multiple reflections occur between Li2O2 and the PAL 104, and the multiple reflection signals are superimposed on the true signal, degrading the image. This multiple reflection occurs as follows. The transmitted ultrasound beam is transmitted from some adjacent transducer groups 107 of LA to PAL 10 at an angle θ.
If the ultrasound beam is expressed as person-0, a part of the ultrasound beam incident on the PAL will be
It is reflected at point 104, reaches point B diagonal to point A centered on point 0, is reflected again at point B, and returns to the entry point along the opposite path. That is, in the variable delay device in the device shown in FIG.
A multiple reflection system of eOeB exists, and the quality of the image has been degraded by this multiple reflection signal. The above explanation is
This is about the transmitted signal, but if the received signal is PA
The same thing occurs when the light is emitted from the L104 toward the L106. In the conventional case, the level of this multiple reflection signal is -adB and -27aB with respect to the true signal when θ=00 and θ=200, respectively, and only an image with an extremely narrow range can be obtained. do not have. The present invention aims to eliminate such multiple reflected signals.

The present invention takes advantage of the advantages of the variable delay device described above, and
In addition, the disadvantages seen in the conventional example, that is, the variable delay device 103
The purpose of the present invention is to provide a high-performance, small-sized, low-cost fan-shaped electronic scanning ultrasonic tomographic examination device that prevents multiple reflections within the device.

Figures 2a and 2b show the overall configuration of the tomographic inspection apparatus according to the present invention, where a shows 1 when five people are used for both transmission and reception, and b shows 1 when five people are used only for reception. This shows the overall configuration. First, a first embodiment of the overall configuration will be described with reference to FIG. In Figure 2 1,
201 is a subject such as a human body, and 202 is a variable delay device. 203 is a transmitter similar to that used in a linear electronic scanning ultrasonic tomography apparatus, 204 is a selection switch, 205 is a receiver, 206 is an image display device, and 207 is a PALT.

The drive pulses generated by the transmitter 203 are transmitted to a predetermined adjacent piezoelectric vibrator group of the LA constituting a variable delay device 2o2 having a structure to be described later, via a selection switch 204 that selects a predetermined vibrator group of the LA. applied. The ultrasonic beam emitted from this piezoelectric vibrator group passes through the propagation path explained based on FIG. 206
The image is displayed and used for diagnosis, etc.

Next, FIG. 2, which is the overall configuration when the LA is used only for reception, will be explained. The difference from Figure 2 (a) is that there is a fan-shaped electronic scanning ultrasonic tomography device transmitter 209 for emitting an ultrasonic beam from the pAL 207 in a fan shape as a transmitter, and a variable delay device 202 for transmitting a transmission signal.
It is equipped with a transmission/reception changeover switch 208 for not applying voltage to AL. The overall operation begins with transmitting a transmission signal corresponding to a predetermined deflection angle from the transmitter 209 to the PAL 207.
to be applied. At this time, the transmission/reception selector switch 208 is
It is in an open state, and no transmission signal is applied to the variable delay device 202. Note that this transmission/reception changeover switch 20B is in the state after sending out the transmission signal, and operates to guide the reception signal to the variable delay device 202. Subject 20
The echo signal obtained from 1 is sent to the transmission/reception selector switch 20.
8 to variable delay device 202 and PAL 20
The ultrasonic beam is received by a predetermined group of adjacent piezoelectric vibrators in the LA selected by the selection switch 204 in accordance with the deflection angle of the ultrasonic beam emitted from the ultrasonic beam 7, and is input to the receiver 206. After this received signal undergoes received signal processing such as detection and amplification,
The image is input to the image display device 206 and used for diagnosis.

Although the overall configuration shown in Figure 2 has a slightly more complicated transmitter than the device shown in Part B of the same figure, since the drive signal with a high signal level is not radiated to the variable delay device, multiple reflections of the transmitted signal can occur. In addition, only one PAL 207 exists in the propagation path of the transmitted signal to the subject, compared to the case where there is one LA and two PALs as in case a. It has the advantage of high synutem sensitivity. The variable delay device described below will be explained mainly in the case of having the overall configuration of B, but basically,
Needless to say, it can also be applied to those having the overall structure of

Next, the structure of the variable delay device 202, which is a feature of the present invention, will be explained based on a specific example.

The variable delay device in this embodiment can eliminate or suppress the occurrence of multiple reflections, which is a disadvantage of the conventional example.

FIG. 3 shows a variable delay device in a first embodiment of the invention. Figure 3 shows LA 301 and PAL
302 is shown in a cross section perpendicular to the scanning plane of the ultrasonic beam. The difference from conventional variable delay devices is that the LMU 301 and the PAL 302 are set at a relatively predetermined angle θ.
This means that they are placed facing each other with their hands. As a result, for example, the ultrasonic beam 303 emitted from the L beam 301
is received by the PAL 302, and the reflected signal 304 is absorbed by a sound wave absorber 305 provided around the variable delay device to remove multiple reflected signals. In the configuration shown in Figure 3, the PAL 302 is installed at an angle of θ with respect to the five people 301, but conversely, Li2O2
Similar effects can be obtained even when the device is tilted relative to L302. Also, the center 0 of Li2O2 and PAL302
There is no need for the centers λB of the five people to be on the same line; in short, it is sufficient that there is no path for the reflected signal 304 to return to the five people 301.

The relative installation angle of LMU 301 and PAL 302 is LMU 3.
01 and PAL302 transmitting and receiving aperture diameter and Lm3
The setting is made taking into consideration the distance between 01 and PAL 302, etc.

Although various embodiments have been described above, it is clear that the effects can be further improved by using a combination of these embodiments.

As explained above, according to the present invention, in addition to the basic advantages of the fan-shaped electronic scanning ultrasonic tomography apparatus, that is, the ability to transmit and receive ultrasonic beams in a fan-shaped manner with simple means, the present invention has the following advantages: This fatal disadvantage, namely the deterioration of tomographic images due to multiple reflections, can be prevented by installing the PAL and LA at relative inclinations in a plane perpendicular to the scanning plane of the ultrasound beam. It is possible to realize a fan-shaped electronic scanning ultrasonic tomographic inspection device that is high-quality, compact, and inexpensive.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a conventional variable delay device, Figure 2a,
3b is a block diagram showing the overall configuration of a fan-shaped electronic scanning ultrasonic tomography apparatus according to an embodiment of the present invention, and FIG. 3 is a sectional view showing an example of the configuration of a variable delay device used in the present invention. 101.201-----Test, 102,104°207.302... Phase array piezoelectric vibrator group, 1
03.202...Variable delay device, 106...
...Sound wave propagation medium, 106.107.301...
・Linear array piezoelectric vibrator group, 108.303.304・
...Ultrasonic beam, 203.205...
Transmitter/receiver, 204... Selection switch, 206.
... Display device, 305 ... Sound wave absorber. Name of agent: Patent attorney Shigetaka Awano and 1 other law firm

Claims (2)

[Claims] (1) A first piezoelectric vibrator group arranged in an arc shape, a second piezoelectric vibrator group arranged in a straight line, and a sound wave interposed between the two piezoelectric vibrator groups. a variable delay device having a propagation medium, the normal line of the first piezoelectric vibrator group and the normal line of the second piezoelectric vibrator group are at a predetermined angle in a plane orthogonal to the scanning plane of the ultrasound beam. The above first
and a second piezoelectric vibrator group, and a sound wave propagation medium is surrounded by a sound wave absorber. (2) A patent claim characterized in that a transmission/reception changeover switch and a transmitter for a fan-shaped electronic scanning ultrasonic tomographic examination device are provided between a variable delay device and a group of phased piezoelectric vibrators used in contact with a subject. The ultrasonic tomographic examination apparatus according to item 1.