JPS5869538A - Ultrasonic diagnostic 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 The present invention relates to an ultrasonic diagnostic apparatus that performs in-vivo examinations using ultrasonic waves.

Ultrasonic pulses are emitted into the living body, and each fi! has different acoustic characteristics (acoustic impedance). The ultrasonic examination method obtains information inside the body by signals reflected from the boundaries of the human body.
Recently, with the development and practical use of high-speed scanning devices, it is rapidly becoming popular.

Conventional ultrasonic diagnostic equipment for conducting such examinations is one in which a probe equipped with a piezoelectric sensor as an electro-acoustic transducer is attached to the surface of the living body either directly or through an ice bag. Let me contact you.

The output of the pulse generator is supplied to the sensor, and the generated ultrasonic waves are emitted into the living body. At this time, there are living bodies and coarse textures with different acoustic impedances (!l: A part of the ultrasonic waves is reflected at the boundaries. This reflected signal is used during transmission and received by the piezoelectric sensor of the same door. , convert it into an electrical signal and display it on a cathode ray tube.

In such a device, it is generally impossible to make the beam width of the ultrasonic wave emitted from the piezoelectric vibrator sufficiently narrow compared to the fineness of the tissue in the living body.

In other words, the beam width limit is determined by the wavelength of the ultrasound used (
0.3 to 0.75 mm), and in such cases, speckle noise appears on the image, deteriorating the image quality. Moreover, such a phenomenon is often seen when high-speed scanning, particularly electronic scanning, is performed.

FIG. 1 is for explaining the situation in which a speckle pattern occurs. That is, if there are two targets T and TB within the range of the ultrasound beam width, and they are approximately equidistant from the surface of the imager with pressure 1, then ζ, from the targets T and TB. From the phase difference l of each reflected wave,
On the screen, these are displayed separately as shown in fa), or not separated as shown in fcl. (a) (cl) in the figure shows the case where the phase difference between the two reflected waves is 1800.90°00.

Such a phenomenon appears as interference fringes in a two-dimensional tomographic image, causing a virtual image and noise, and seriously impeding diagnosis.

This invention was made based on the above circumstances, and by adding and averaging a plurality of reflected signals obtained from adjacent scans, speckle noise is removed, a clear image is obtained, and an accurate image is obtained. The present invention aims to provide an ultrasonic diagnostic device that can perform examinations.

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

As shown in Figure 2 (while moving the probe 11 in the X direction along the surface of the living body, ultrasound is transmitted and received in the Z direction. In this way, a tomographic image in the XY plane is obtained. be able to.

For this probe 11, a transmission 4 as shown in FIG.
The probe 11 is driven by the probe 12 to generate ultrasonic waves.
The signal received by the receiver 13 is processed by the receiver 13. First, in the case of transmission, the output of the pulse generator 14 drives the pulser 15 to obtain pulses with a sufficient imaging width, which drives the piezoelectric vibrator in the probe 11 and is irradiated with ultrasound.

On the other hand, the ultrasound reflected within the living body is received by the probe 11, guided to the receiver 13, and supplied to the delay circuit 18 via the amplifier 16 and detector 17.

In the delay circuit 181C, the received signal is delayed by a time approximately equal to the period (TR) in which the ultrasonic pulse is emitted.
At step 9, the signal is added to the signal without delay from the wave detector 17 and displayed on a cathode ray tube 20 serving as a display means.

For example, the signal obtained in scan A' after the probe 11 is at position A is fPt, l, and is delayed by the time TR in the delay circuit 18 and sent to the adder 1, as shown in FIG.
Sent to 9th.

At this time, the probe 11 has moved to position B, so the received signal obtained by scanning B' in this case is transmitted to the amplifier 1.
6. The signal is sent to the other terminal of the adder 19 via the detector I7, where it is added to the above-mentioned signal.

In FIG. 4, (a) is the output of the detector 17, (bl
is the output of the delay circuit 18, (C) is the output of the adder 19 (
a).

The output of the adder 19 which added the outputs shown in lb), cd
) indicate the output of pulsar ]5, respectively.

In this way, speckle noise based on fluctuations in the reflected signal status can be reduced by averaging signals obtained from adjacent scans. Therefore, the displayed image becomes clear and accurate diagnosis becomes possible.

We have shown that this type of averaging can improve the azimuth resolution, especially if it is performed within a range where each scan interval is sufficiently small compared to the beam width. can be further increased as appropriate.

Figure 5 uses three delay circuits 18a to 18C and 4
This shows a case where averaging is performed between scanning lines of a book. Also, when the number of scanning lines is plural.

As shown in FIG. 6, a better image can be obtained by weighting each signal using weighting circuits 21a to 21d and then adding the signals. That is, by performing such weighting, deterioration in resolution is corrected and the outline of the image is displayed in a natural manner.

8. This invention is not limited to the above embodiments, and can be modified in various ways without changing the gist.

For example, in the above embodiment, a case was described in which one probe was used and it was mechanically scanned, but the present invention is configured to arrange the probes in an array and perform electronic scanning. You can also do that.

As described above, according to the present invention, speckle noise is removed by adding and averaging a plurality of reflected signals obtained from adjacent scans, and a clear image is obtained for accurate inspection. We are able to provide ultrasonic diagnostic equipment that can

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the situation in which speckle patterns occur.
FIG. 2 is an explanatory diagram of the scanning of the probe in one embodiment of the present invention, FIG. 3 is a block diagram showing the schematic configuration of the embodiment, and FIG. 4 is a diagram for explaining the operation of the actual example. FIG. 5 is a block diagram showing the schematic structure of another embodiment of the present invention, and FIG. 6 is a block diagram showing the schematic structure of still another embodiment of the present invention. 11... Probe 12... Transmitter 13...
Receiver 14...Pulse generator 15...CJ
L/Sa 16...Amplifier 17...Detector
18. 18a to 18c...Delay circuit 19...Adder 20...Cathode ray tubes 21a to 21d...Identification circuit

Claims (2)

[Claims] (1) An electric + acoustic conversion element, a scanning mechanism for mechanically or electrically scanning this conversion element, a transmitter that energizes the conversion element to generate ultrasonic waves, and an ultrasonic wave obtained by this conversion element. The receiver is equipped with a receiver for amplifying and detecting a received signal, and a display means for displaying the output of the receiver, and the receiver is configured to add and average a plurality of received signals obtained by adjacent scanning. Ultrasonic diagnosis 1@ device characterized by including a delay circuit and an adder. (2) The ultrasonic diagnostic apparatus according to claim 1, wherein the receiver has a weighting circuit for weighting at least a portion of the plurality of received signals.