JPS6022932B2 - Ultrasonic inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic testing apparatus in which the amplitude range of an ultrasonic diagnostic signal is variably set over time.

Ultrasonic examination devices can easily obtain tomographic images of living bodies, and are extremely useful in diagnostic medicine.

This type of ultrasonic inspection apparatus generally transmits an ultrasonic beam from an ultrasonic probe to an area to be inspected, and receives reflected waves of the ultrasonic beam from the area to be inspected by the ultrasonic probe.
This received signal, that is, the tomographic information signal, is subjected to predetermined signal processing and then displayed on a display to obtain a diagnostic layer image. However, the ultrasonic waves transmitted from the ultrasonic probe include side ropes in addition to the main rope, and the influence of these side ropes cannot be ignored. In particular, the influence of the sides and ropes at close range of the ultrasonic probe is very large, and there is a risk that a virtual image will appear on the display. For example, when examining the heart,
Since the ribs and lungs were located directly below the chest wall, a virtual image of these side ropes appeared on the display. For this reason, the conventional ultrasonic inspection apparatus has a drawback that the image on the display becomes difficult to see due to the virtual image caused by the side ropes of the ultrasonic probe, especially the virtual image caused by the side ropes of the ultrasonic probe at a short distance. This has the drawback of easily causing misdiagnosis. Therefore, the purpose of this invention is to eliminate the virtual image caused by the side rope of the ultrasound probe by limiting the amplitude range of the ultrasound reception signal according to the ultrasound reception time, and to provide an ultrasound inspection that makes the image on the display easier to see. The goal is to provide equipment. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing the same embodiment. In Fig. 1, la, ~, ln are piezoelectric ultrasonic transducers;
. Reference numeral 2 denotes a transmitting section consisting of a clock circuit, a pulser, a switching control circuit, and the like.

3a to 3n are switch circuits, which are ON/OFF controlled by a switching control signal from the transmitter 2.

Further, the synchronization circuit 4 generates a synchronization signal in response to the signal from the transmitter 2 and supplies this synchronization signal to the monitor 5 and the control circuit 9. Therefore, when a pulse signal is now output from the pulser of the transmitting section 2, the switch circuits 3a, . . . , 3n
operates in response to a switching control signal, and selectively applies the pulse signal to the ultrasonic transducers la, . . . , ln. An ultrasonic pulse signal is transmitted from the ultrasonic probe 1 according to this pulse signal. This transmitted ultrasonic pulse signal is reflected at points with different acoustic impedances in the living body of the subject to become ultrasound waves accompanied by tomographic information of the subject, and the ultrasonic transducer la, ~, ln
The waves are received at These ultrasonic transducers la
, ~ln each generate a voltage signal (tomographic information signal) proportional to the sound pressure of the received ultrasonic wave. This tomographic information signal is amplified via the front layer amplifier 6 and input to the detector 7. The detection circuit 7 is composed of, for example, a diode detector, and extracts or detects the envelope of the tomographic information signal (high frequency signal) to obtain a video signal. This video signal is connected to the control circuit 9 or input to the miter circuit 8.
The limiter circuit 8 is composed of a diode, a Jenner diode, etc., and is used to variably set the amplitude range of the video signal using a control voltage from the control circuit 9. The control circuit 9 is composed of an integrating circuit, etc., and is connected to the synchronous circuit 4.
The control voltage is generated in response to a one rate synchronization pulse from. This control voltage is, for example, one that gradually decreases over one rate period of time. The lower limit value of the limiter circuit 8 is variably set by such a control voltage. The video signal whose amplitude has been limited by the limiter circuit 8 is amplified via an amplifier 10 and supplied to the monitor 5. Monitor 5 is C
It is composed of an RT (cathode ray tube) or the like, and displays an image based on the video signal, that is, a diagnostic tomographic image. According to this apparatus configured in this way, the amplitude range of the video signal is variably set over time by the lower limit value variably set in the limiter circuit 8.

By this control, the virtual image due to the side ropes of the ultrasound probe 1 can be effectively removed as follows. That is, a signal due to the side lobe of the ultrasound probe 1 (virtual image signal) is generally input to the amplifier 6 together with a signal due to the main lobe of the ultrasound probe 1 (tomographic information signal). If these signals are directly supplied to the monitor 5 without speeding up the limiter circuit 8, a virtual image due to the side ropes will be mixed into the displayed image on the monitor 5. Particularly when examining the heart, since ribs, lungs, etc. with high acoustic impedance are present in close proximity to the ultrasound probe 1, virtual images of these are caused by the side ropes. Moreover, this virtual image signal becomes very large at the beginning of receiving the ultrasonic waves. Therefore, in this apparatus, a limiter circuit 8 is provided, and the lower limit value of this limiter circuit 8 is set high at the time of starting ultrasonic wave reception.
Then, as time passes, the lower limit value is gradually lowered to narrow the range of amplitude limitation by the limiter circuit 8. Second
The figure shows the state of the signal controlled by the limiter circuit 8 when the lower limit value of the limiter circuit 8 is controlled in this manner. In FIG. 2, the vertical axis Ei is the limiter circuit 8.
The horizontal axis t represents the elapsed time from the start of ultrasound reception over one rate time. a is the upper limit value of the limiter circuit 8, and is used to prevent excessive input V from being supplied to the monitor 5 and amplifier 10. b is the lower limit value of the limiter circuit 8, and signals with a level lower than this lower limit value b are removed by the limiter circuit 8'. By setting the lower limit value b of the limiter circuit 8 higher than the level of a particularly large signal among the virtual image signals d input to the limiter circuit 8, that is, setting it particularly high at the start of ultrasound reception, the virtual image signal d can be removed. At this time, the level of the tomographic image signal e input to the limiter circuit 8 is generally higher than the level of the virtual image signal d and higher than the lower limit value b, so the monitor 5 has almost no influence on the tomographic image being imaged. There is no. In addition, the lower limit darkness value b is set to gradually decrease over time over one rate.The tomographic image signal e at the end of ultrasound reception becomes smaller as the ultrasound attenuates. However, since the lower limit value b at this time is very small as described above, the tomographic image signal e is not affected by this lower limit value b. Since the virtual image signal d at the end of the wave is at an extremely low level, it will be removed even if the lower limit value b is small.In this way, the lower limit value b of the limiter circuit 8 is set to the virtual image signal d. By setting it high for a long time, that is, at the start of ultrasonic wave reception, the virtual image due to the side ropes can be removed from the image displayed on the monitor 5.

Therefore, there is an advantage that the diagnostic tomographic image displayed on the monitor 5 has increased accuracy and is extremely easy to view. In addition,
The invention is not limited to the embodiments described above.

The lower limit value b of the limiter circuit 8 does not need to be decreased linearly with time or distance, but may be changed in a curved manner, as shown in FIG. 3, for example. FIG. 3 shows the state of the signal controlled by the limiter circuit 8 when the control circuit 9 is provided with a lower limit value variable setting limiter and the lower limit value b is changed in a curved manner by this limiter. .
If the lower limit value b is set a little higher at the time when the virtual image signal due to the side rope is considered to be included in this way, it will be more effective in removing the virtual image due to the side rope. Further, the signal controlled by the limiter circuit 8 is not limited to a video signal, and the limiter circuit 8 can be set to control a tomographic information signal (high frequency signal) before passing through the detector 7. In short, the present invention can be implemented with various modifications without departing from the gist thereof. As explained above, according to the present invention, by variably setting the amplitude range of the ultrasonic reception signal over time using the limiter circuit, it is possible to remove the virtual image signal due to the side rope of the ultrasonic probe. Therefore, it is possible to provide an ultrasonic inspection apparatus that can obtain a clear image without displaying a virtual image due to the side ropes on the display.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the same embodiment, and FIG. 3 is a diagram for explaining the operation of another embodiment of the present invention. It is a diagram. 1... Ultrasonic probe, la, ~9 1n... Ultrasonic transducer, 2... Transmitter, 3a, ~, 3n
...Switching circuit, 4...Synchronization circuit, 5...
Monitor, 6... Front layer amplifier, 7... Detector, 8...
-Limiter circuit, 9...control circuit, 10...amplifier. 1 figure is 2 figures★3 figures

Claims (1)

[Scope of Claims] 1. An ultrasonic probe that transmits and receives ultrasonic waves to obtain tomographic information of the examined area, and removes minute amplitude components of the tomographic information signal of the examined area obtained by this ultrasonic probe. and a control circuit that increases the threshold value of the limiter circuit that removes the minute amplitude component at the start of ultrasonic reception and decreases it as time passes. 2. The ultrasonic inspection apparatus according to claim 1, wherein the control circuit monotonically decreases the threshold value of the limiter circuit. 3. The ultrasonic testing apparatus according to claim 1, wherein the control circuit sets the threshold value of the limiter circuit to a large value at a predetermined time and causes the threshold value to undergo damped oscillation.