JPH064071B2 - Ultrasonic tomography device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic tomography apparatus, which scans an ultrasonic beam in a fan shape by using a simple means, and outputs a fan-shaped ultrasonic tomographic image at a low cost and in a small fan-shaped electronic scanning type. An object of the present invention is to provide an ultrasonic tomography apparatus (hereinafter abbreviated as ESU).

As one of the methods of constructing an ESU by a simple means, there is one disclosed in Japanese Patent Laid-Open No. 52-68492, which will be described with reference to FIG. In FIG. 1, 101 is an object such as a human body, 102 is a phase array piezoelectric transducer group for ESU (hereinafter abbreviated as PAL), 103 is an analog variable delay line device, and the acoustic propagation medium 105 and concave surface are arranged. Group of linear array piezoelectric vibrators (hereinafter abbreviated as LA) 106
It consists of and. In the LA 106, a predetermined number of adjacent groups 107 are excited by a selection switch that is connected to each piezoelectric vibrator, become an ultrasonic beam and propagate in the propagation medium 105, and the PAL 104 and the PAL 102.
After that, an ultrasonic beam is sent into the subject 101. On the other hand, the reflected beam from the subject 101 is received by the original group 107 of the LA 106 via the same route as in the case of transmission, and thereafter, image display is performed through normal signal processing. The deflection of ultrasonic waves in the subject 101 is LA
This is performed by selecting 106 elements.

In the above conventional configuration, the E currently in practical use
Compared to the SU, the variable delay unit is significantly simplified as shown in FIG. Considering that the variable delay unit was the main cause of the conventional ESU being expensive and the device casing being large, the above configuration could provide a low-priced and miniaturized ESU. It turns out that it has.

On the other hand, in the above configuration, the analog variable delay line device 103
In the above, there is a drawback that multiple reflection occurs between the LA 106 and the PAL 104, and the multiple reflection signal is superposed on the true signal to deteriorate the image. This multiple reflection occurs as follows. The transmitted ultrasonic beam is transmitted from the group of transducers 107 adjacent to each other in LA at the angle PAL10 at the angle θ.
When the ultrasonic beam is radiated to A4, if the ultrasonic beam is expressed by AO, a part of the ultrasonic beam incident on the PAL is PAL.
It is reflected at 104, reaches the diagonal point B of the point A centering on the point O, is reflected again at the point B, and follows the reverse path to return to the point A. That is, in the variable delay device in the device of FIG.
There is an OB multiple reflection system, and the image quality is degraded by this multiple reflection signal. The above description is
As for the transmitted signal, the received signal is PA
The same occurs when the light is emitted from L104 toward LA106. In the case of the conventional example, the levels of the multiple reflection signals are -8db and -27dB with respect to the true signal when Χ = 0 ° and θ = 20 °, respectively, and only an image with an extremely narrow dynamic range can be obtained. Absent. The present invention aims to eliminate such multiple reflection signals.

The present invention utilizes the advantages of the variable delay device described above,
Also, the disadvantages of the conventional example, that is, the variable delay device 103
(EN) A fan-shaped electronic scanning ultrasonic tomography apparatus of high performance which is capable of preventing multiple reflections inside and is small in size and inexpensive.

2A and 2B show the overall configuration of the tomographic inspection apparatus according to the present invention, in which a shows the overall configuration when LA is used for both transmission and reception, and b shows the overall configuration when LA is used only for reception. It is shown. First, a description will be given of FIG. 1A which is a first embodiment relating to the overall configuration. 2a, 2
Reference numeral 01 is an object such as a human body, and 202 is a variable delay device. Reference numeral 203 is a transmitter similar to that used in the linear electronic scanning ultrasonic tomography apparatus, 204 is a selection switch, 205 is a receiver, 206 is an image display device, and 207 is PAL.

The drive pulse generated by the transmitter 203 is passed through a selection switch 204 for selecting a predetermined transducer group of LA to a predetermined piezoelectric transducer group of LA constituting a variable delay device 202 having a structure described later. Is applied. The ultrasonic beam emitted from this piezoelectric vibrator group is input to the receiver 205 through the propagation path described with reference to FIG. 1 and undergoes received signal processing such as amplification and detection, and then the image display device. An image is displayed on 206 and is used for diagnosis and the like.

Next, FIG. 2b, which is the overall configuration when the LA is used only for reception, will be described. 2A is different from that of FIG. 2B in that a fan-shaped electronic scanning ultrasonic tomography apparatus transmitter 209 for emitting an ultrasonic beam in a fan shape from a PAL 207 as a transmitter, and a transmission signal P of a variable delay device 202.
That is, the transmission / reception changeover switch 208 is provided so as not to apply the voltage to the AL. In the entire operation, first, the transmitter 209 transmits a transmission signal corresponding to a predetermined deflection angle to the PAL 207.
Apply to. At this time, the transmission / reception changeover switch 208 is
The open state is set so that the transmission signal is not applied to the variable delay device 202. The transmission / reception changeover switch 208 is closed after transmitting 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 the transmission / reception changeover switch 20.
8 to the variable delay device 202,
The signals are received by a predetermined group of piezoelectric vibrators of LA selected by the selection switch 204 corresponding to the deflection angle of the ultrasonic beam emitted from 7, and input to the receiver 205. This received signal is subjected to received signal processing such as detection and amplification, and then input to the image display device 206 and used for diagnosis. In the overall configuration shown in FIG. 2, the transmitter is slightly more complicated than the device shown in FIG. 2A, but since the drive signal having a high signal level is not radiated to the variable delay device, the multiple reflection of the transmitted signal is caused. And that only one PAL 207 exists in the propagation path of the transmission signal to the subject, as compared to the case where there is one LA and two PALs as in the case of a, It has the advantage of high system sensitivity. The variable delay device described below will be described focusing on the case having the overall configuration of a, but it goes without saying that it can be basically applied to the device having the overall configuration of b.

Next, the structure of the variable delay device 202, which is a feature of the present invention, will be described based on specific examples. The variable delay device in this embodiment can eliminate or suppress the occurrence of multiple reflection, which is a disadvantage of the conventional example.

FIG. 3 shows a variable delay device according to the first embodiment of the present invention. Figure 3 shows LA301 and PAL30.
The installation state of the transmitting / receiving surface of the ultrasonic beam 2 is LA301.
And a cross section of the PAL 302 orthogonal to the scanning plane of the ultrasonic beam, that is, a cross section in a plane orthogonal to the arrangement direction of the piezoelectric vibrators of the LA 301 and the PAL 302.

The difference from the conventional variable delay device is LA301 and PAL302.
Are installed to face each other with a predetermined angle θ. As a result, for example, the ultrasonic beam 303 emitted from the LA 301 is received by the PAL 302, and the reflected signal 304 is absorbed by the acoustic wave absorber 305 provided around the variable delay device to remove the multiple reflected signal. is there. In the configuration of FIG. 3, the PAL 302 is installed so as to be tilted by θ with respect to the LA 301, but conversely, when the LA 301 is tilted and installed with respect to the PAL 302, the same effect can be obtained. Also, the center of LA301 is 0
Then, the center AB of the PAL 302 does not have to be on the same line, and in short, there is no route for the reflected signal 304 to return to the LA 301. The relative installation angle of LA301 and PAL302 is set in consideration of the transmission and reception aperture diameters of LA301 and PAL302 and the distance between LA301 and PAL302.

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

As described above, according to the present invention, the basic advantage of the fan-shaped electronic scanning ultrasonic tomography apparatus, that is, the ultrasonic beam can be transmitted and received in a fan shape by simple means, and the conventional apparatus has A fatal disadvantage, that is, deterioration of a tomographic image due to multiple reflection, can be prevented by installing PAL and LA relatively inclined in a plane orthogonal to the scanning plane of the ultrasonic beam, and thus high quality is achieved. It is possible to realize a fan-shaped electronic scanning type ultrasonic tomography apparatus which is small and small in size.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a conventional variable delay device, FIG.
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 ... Subject, 102, 104, 207,
302 ... Phase array piezoelectric vibrator group, 103, 202 ...
Variable delay device, 105 ... Sound wave propagation medium, 106, 10
7, 301 ... Linear array piezoelectric vibrator group, 108, 30
3, 304 ... Ultrasonic beam, 203, 205 ... Transceiver, 204 ... Selection switch, 206 ... Display device, 3
05 ... Sound wave absorber.

Claims (2)

[Claims] 1. A first piezoelectric vibrator group arranged in a circular arc shape and scanning with an ultrasonic beam, and a plurality of linear piezoelectric elements arranged in the same direction as the first piezoelectric vibrator group on the concave side of the circular arc. A variable delay device having a second piezoelectric vibrator group arranged and scanning an ultrasonic beam, and a sound wave propagation medium interposed between the first and second piezoelectric vibrator groups is provided. Second
In the plane orthogonal to the scanning plane of the ultrasonic beam of the piezoelectric vibrator group, the transmission / reception surface of one of the first and second piezoelectric vibrator groups and the other piezoelectric vibrator group The transmitting and receiving surfaces are not parallel to each other, and the ultrasonic beam emitted from one of the piezoelectric transducer groups does not reach the piezoelectric transducer group that emitted the ultrasonic beam again after being reflected by the other piezoelectric transducer group. An ultrasonic tomography apparatus, wherein the first and second piezoelectric vibrator groups are installed at an angle, and the periphery of the sound wave propagation medium is covered with a sound wave absorber. 2. A transmission / reception changeover switch and a transmitter for a fan-shaped electronic scanning ultrasonic tomography apparatus are provided between the variable delay device and a phase array piezoelectric vibrator group used in contact with a subject. The ultrasonic tomography apparatus according to claim 1.