JPH0496741A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To eliminate the offensive sight due to an abdominal wall, improve the uniformity of contrast of the whole image, and prevent the difficulty in observing a diaphragm by installing a gain variation point varying limitter means which possesses the large gain for the input signal smaller than the gain variation point and the small gain for the input signal larger than the gain variation point and can shift the gain variation point, in the posterior stage from a LOG compression part, and by installing a gain variation point shift control means for shifting the gain variation point in a prescribed timing. CONSTITUTION:In case of the timing for obtaining the ultrasonic wave echo signal of an abdominal wall (f) which is directly under a probe, the gain variation point of a limitter means is shifted to the side where the input signal reduces. Accordingly, the gain reduces for the strong reflection supplied from the abdominal wall (f), and the signal level is restricted to a small value. While, in case of the timing for obtaining the ultrasonic wave echo signal supplied from the part other than the abdominal wall (f), the gain variation of the limitter means is shifted to the side where the input signal increases. Accordingly, the gain increases for the reflection supplied from the soft tissues (g) and (h) and a diaphragm (y), and the sufficient signal level can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic device, and more specifically,
The present invention relates to an ultrasonic diagnostic apparatus that can improve the uniformity of contrast across an entire image.

[Prior Art] FIG. 13 is a block diagram showing an example of a conventional ultrasonic diagnostic apparatus.

This ultrasonic diagnostic device 51 includes a probe 2 connected to a driver T and a receiver R, a beam former 3, and a LOG
It is configured to include a detection section 5 for the compression/compression section, a DSC 6, and a CRT.

FIG. 14 is an example of an image displayed on a CRT.

A strong reflection of the abdominal wall f appears in a portion close to the probe 2. Then, a weak reflection of soft tissue g appears. Next, a strong reflection of the diaphragm y appears. moreover,
Weak reflexes of soft tissue are visible.

FIG. 15(a) shows the LOG compression unit power signal Sa on the sound ray La in this image, and FIG. 15(b) shows the output signal Sc of the detection unit 5.

Abdominal wall f and diaphragm y have high signal levels, soft tissue g,
h has a low signal level.

[Problems to be Solved by the Invention] In the conventional ultrasonic diagnostic apparatus 51, the difference between the signal level of the abdominal wall f and the signal level of the soft tissue g (φ in FIG. 15(b)) is very large. There is a problem that f becomes very unsightly on the image and the uniformity of the contrast of the entire image deteriorates.

For this reason, it is conceivable to limit the signal level with a limiter circuit, but in that case, although the unsightliness of the abdominal wall f is eliminated, a new problem arises in that the diaphragm y becomes difficult to see.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic diagnostic apparatus that eliminates the obtrusiveness of the abdominal wall f, improves the uniformity of the contrast of the entire image, and prevents the diaphragm y from becoming difficult to see.

[Means for Solving the Problems] An ultrasonic diagnostic apparatus of the present invention includes an ultrasonic diagnostic apparatus including a probe, a beam former, a LOG compression section, a detection section, one image processing section, and one image display section. In a diagnostic device, the gain change point has a large gain for an input signal smaller than the gain change point, has a small gain for an input signal larger than the gain change point, and is movable. The present invention is characterized in that variable limiter means is provided at a stage subsequent to the LOG compression section, and gain change point movement control means for moving the gain change point at a predetermined timing is provided.

[Function] In the ultrasonic diagnostic apparatus of the present invention, the abdominal wall f directly below the probe
At the timing when the ultrasonic echo signal is obtained, the gain change point of the limiter means is moved to the side where the input signal becomes smaller.

Therefore, the gain becomes small for strong reflection from the abdominal wall f, and the signal level is limited to a small value.

On the other hand, at the timing when an ultrasonic echo signal is obtained from a source other than the abdominal wall f, the gain change point of the limiter means is moved to the side where the input signal increases.

Therefore, the gain is increased for reflections from the soft tissues g, h and the diaphragm y, and a sufficient signal level can be obtained.

Therefore, the obtrusive appearance of the abdominal wall f is eliminated, and the uniformity of contrast across the image is improved. - On the other hand, the diaphragm y is also prevented from becoming difficult to see.

[Example] The present invention will be further described below with reference to Examples shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a block diagram showing an ultrasonic diagnostic apparatus 1 according to an embodiment of the present invention.

Driver T, receiver R, probe 2. Beamformer 3. LOG compression section 4. Detection section 5. DSC6 and CRT
has the same configuration as the conventional one.

A variable gain change point limiter section 7 is interposed between the LOG compression section 4 and the detection section 5.

Further, a gain change point movement control signal generating section 8 is provided which outputs a gain change point movement control signal Vc based on the trigger pulse P from the beam former 3.

FIG. 2 is a circuit diagram showing a specific circuit example of the variable gain change point limiter section 7. As shown in FIG. Moreover, FIG. 3 is a characteristic diagram thereof.

The voltage conversion circuits Ap and An output voltages Vs and -Vs based on the gain change point movement control signal Vc.

The input voltage Sa is small and the output voltage sb is -(■s+V
d) to +(Vs - Vd), the diode is not conductive, so the gain GN is determined by Rc/RE. The input signal Sa becomes larger and the output voltage sb becomes -
(Vs+Vd) or more than 10 (Vs+Vd), the diode becomes conductive and the gain Gs becomes RC-
Determined by RL/RE (RC+RL).

That is, the gain change point is moved by the gain change point movement control signal Vc, and the input signal Sa is moved from the gain change point.
When is small, the gain GN is relatively large, and when the input voltage Sa is greater than the gain change point, the gain Gs is relatively small.

As shown in FIG. 6, the gain change point movement control signal generator 8 becomes a small voltage immediately after the trigger pulse P output from the beamformer at the start of reception of one sound ray, and then maintains a voltage at a predetermined level. The gain change point movement control signal Vc is output so that

Therefore, the voltages Vs and -Vs become voltages close to O immediately after the trigger pulse P, and thereafter become voltages at a predetermined level.

Therefore, immediately after the trigger pulse P, as shown in FIG. 4, the gain change point moves to the side where the input voltage Sa becomes smaller. Further, thereafter, as shown in FIG. 5, the gain change point moves to the side where the input voltage Sa increases.

Therefore, as shown in FIG. 6, the input voltage Sa of the variable gain change point limiter section 7 is applied to a portion of the abdominal wall f having a large signal level, a portion of the soft tissue g having a small signal level, and a portion of the diaphragm y having a large signal level. and a soft tissue part with a small signal level, the output voltage sb of the variable gain change point limiter section 7 is limited only to the signal level of the abdominal wall f part (gain Gs), and the soft tissue g, The signal levels at the portions of h and y of the diaphragm are not limited (gain GN).

In this way, the output signal Sc of the detection unit 5 becomes as shown in FIG. 6, and the level difference α between the abdominal wall f part and the soft tissue g part is
Since this is small, the portion of the abdominal wall f is no longer obtrusive, and the uniformity of contrast is improved. On the other hand, since the level difference β between the soft tissues g and h and the diaphragm y is large, the diaphragm y does not become difficult to see.

Next, FIG. 7 is a block diagram of an ultrasonic diagnostic apparatus 11 according to another embodiment of the present invention.

In this ultrasonic diagnostic apparatus 11, the detection section 5 and the DSC
A gain change point variable limiter section 17 is interposed between the two.

FIG. 8 is a circuit diagram showing a specific circuit example of the variable gain change point limiter section 17. Moreover, FIG. 9 is a characteristic diagram thereof.

Vc is a gain change point movement control signal from the gain change point movement control signal generation section 18. Va is a compensation signal for compensating for changes in screen brightness due to changes in the gain change point movement control signal Vc.

FIG. 12 is a signal waveform diagram of each part in the ultrasonic diagnostic apparatus 11.

When the trigger pulse P is output from the beamformer 3 at the start of reception of sound rays, the gain change point movement control signal generator 1
8 outputs a gain change point movement control signal Vc which becomes close to O immediately after the trigger pulse P and thereafter becomes a predetermined level.

The input signal Sd of the variable gain change point limiter section 17 is divided into a portion of the abdominal wall f where the signal level is high, a portion of the soft tissue g where the signal level is low, a portion of the diaphragm y where the signal level is high, and a soft tissue portion where the signal level is low. It consists of two parts. In this input signal Sd, the level difference φ between the abdominal wall f portion and the soft tissue g portion is extremely large.

However, immediately after the trigger pulse P, the gain change point in the gain change point variable limiter section 17 moves to the side where the input voltage Sd becomes smaller, as shown in FIG. 10, and thereafter, as shown in FIG. , the input voltage Sd moves to the side where it increases.

Therefore, as shown in FIG. 12, in the output signal Se, only the signal level of the abdominal wall f portion is limited.

Therefore, the level difference α between the abdominal wall f and the soft tissue g
Since this is small, the abdominal wall f is no longer obtrusive on the screen, and the uniformity of contrast is improved. On the other hand, since the level difference β between the portion of the diaphragm y and the portions of the soft tissues g and h is large, the diaphragm appears stiff.

[Effects of the Invention] According to the ultrasonic diagnostic apparatus of the present invention, the abdominal wall is prevented from being emphasized and becomes an eyesore, and the uniformity of the contrast of the entire image is improved. Moreover, the diaphragm is also prevented from becoming difficult to see.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention, FIG. 2 is a circuit diagram of a specific example of the variable gain change point limiter section in the embodiment device of FIG. 1, and FIG. 2
Figure 4 shows the characteristics of the variable gain change point limiter section in Figure 2 immediately after the trigger pulse, Figure 5 shows the characteristics of the variable gain change point limiter unit in Figure 2 after a predetermined time has elapsed from the trigger pulse. 6 is a time chart of signals of each part of the embodiment shown in FIG. 1, and FIG. 7 is a block diagram of another embodiment of the ultrasonic diagnostic apparatus of the present invention. , FIG. 8 is a circuit diagram of a specific example of the variable gain change point limiter section in the embodiment device of FIG. 7, FIG. 9 is a characteristic diagram of the variable gain change point limiter section of FIG. 8,
Fig. 10 is a characteristic diagram immediately after the trigger pulse of the variable gain change point limiter section in Fig. 9, and Fig. 11 is a characteristic diagram after a predetermined time has elapsed from the trigger pulse of the variable gain change point limiter section in Fig. 9. FIG. 12 is a time chart of signals of each part in the embodiment shown in FIG. 7, FIG. 13 is a block diagram of an example of a conventional ultrasound diagnostic device, and FIG. 14 is a screen image of a conventional ultrasound diagnostic device. Illustrative diagram, 1st
5(a) and 5(b) are waveform diagrams of signals at various parts in the conventional ultrasonic diagnostic apparatus shown in FIG. 12. (Explanation of symbols) 1.11...Ultrasonic diagnostic device 7°8°17...Gain change point variable limiter section 18...Gain change point movement control signal generation section.

Claims (1)

[Claims] 1. A probe, a beamformer, a LOG compression section,
In an ultrasonic diagnostic apparatus that includes a detection section, an image processing section, and an image display section, it has a large gain for an input signal smaller than the gain change point, and has a large gain for an input signal larger than the gain change point. A gain change point variable limiter means having a small gain and capable of moving the gain change point is provided at a stage subsequent to the LOG compression section, and the gain change point is moved at a predetermined timing. An ultrasonic diagnostic apparatus characterized by being provided with a control means.