JPS63240842A - 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] [Object of the invention] (Industrial application field) The present invention adjusts the receiving sensitivity according to the depth of the object,
STC (Sensitivity Time Control) is used to make images uniform and easy to see from short distances (shallow areas) to deep areas.
The present invention relates to an ultrasonic diagnostic apparatus equipped with a control) waveform generation circuit.

(Prior art) When displaying a tomographic image of a living body, an ultrasound diagnostic device needs to correct the absorption attenuation of ultrasound in the living body to display a uniform image from shallow to deep parts. An STC circuit that adjusts reception sensitivity according to the depth inside the body is required.

Conventionally, in order to perform this adjustment, the steps shown in Fig. 7(a), (
As shown in b), STC volumes 10A to 10H are provided according to each depth within the body, and by adjusting the volume while looking at the displayed image so that the image is uniform and most visible, the STC volume can be adjusted according to the setting of the volume. STC waveform is generated.

In addition, there is a need for a method in which the STC waveform is stored in advance according to the frequency 2 diagnosis area of the probe used, so that a nearly uniform image can be obtained without adjusting the STC volume (preset src). 1 ability).

(Problems to be Solved by the Invention) Among the conventional techniques described above, in the case where the Preset SrC function is not provided, it is necessary to adjust the STC volume every time the probe used or the diagnostic site is changed, and this work is extremely complicated. Rarely.

On the other hand, even with a device having the Pr'eSet SrC function, it is impossible to cover all paired nine sites and individual differences between subjects. In other words, the absorption temperature of ultrasound in a living body increases as the frequency increases, and the living body average is approximately 2 (1B) at 28H2.
This is because an attenuation of 5 dB/cm is observed at 5 Htlz, and this attenuation varies considerably depending on the target organ and individual differences in the subject. Therefore, in order to cover all of these, it is rare at present that the STC volume must be finely adjusted.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and even if the probe 7 used, the diagnosis site, the subject, etc. change, the displayed image can be displayed without requiring the conventional STC volume. An object of the present invention is to provide an ultrasonic diagnostic apparatus that can obtain optimal images with uniform brightness.

[Four features of the invention (Means for solving the problem) The present invention provides a method provided in a received echo signal processing circuit that converts a received echo signal from an ultrasound probe into a luminance signal,
A gain control circuit that controls the gain of the luminance signal based on the S T'C waveform and an image display signal required by the output of the received echo signal processing circuit, at least for each section in the depth direction of the subject. an arithmetic circuit that calculates the difference between the average level of the signal and a reference signal level; and an STC waveform that generates an STC waveform that cancels the difference between both levels for each section based on the output of the arithmetic circuit, and feeds it back to the gain control section. A waveform generating circuit is provided to constitute an ultrasonic diagnostic apparatus.

(Function) In the present invention, the output of the received echo signal processing circuit is fed back and the 8-C waveform is controlled so that it becomes equal to the average level in the depth direction of the image display signal or a predetermined reference signal level. ing. As a result, even if the probe used is changed, it is possible to automatically generate the 8-C waveform so as to obtain an optimal image.

(Example) Hereinafter, the present invention will be explained in detail based on the illustrated example.

FIG. 1 is a block diagram of the basic configuration of the present invention.

In the figure, a received echo signal processing circuit 1 inputs ultrasound echo signals from an ultrasound probe (not shown),
This is a circuit that converts the luminance signal into a luminance signal to be displayed as an image on a TV screen or the like.

The gain controller section 2 is provided within the received echo signal processing circuit 1 and controls the gain of the luminance signal based on the S T''C waveform.

In this embodiment, while displaying an image on the TV screen using the image display brightness signal, a feedback loop is formed to control the STC waveform based on this brightness signal and feed it back to the gain controller circuit 2. There is.

For this purpose, the luminance signal is converted into a digital value by the A/D converter 3, and once stored in the line memory 4). (abbreviated as ) 5.

This) tora numbing circuit 5 calculates the average level of the luminance signal for each section in the depth direction of the living body, and roughly calculates the difference between this calculation result and a predetermined reference signal level regardless of the depth direction. This is a circuit that calculates and outputs for each section.

The STC waveform generation circuit 6 generates an STC waveform that cancels the difference based on the difference between the average level for each section and the reference signal level output from the arithmetic circuit 5,
It feeds back to the gain controller circuit 2.

In this embodiment, when the probe used, the diagnostic site, or the subject changes, the operation in the feedback loop is executed by pressing a switch (not shown).
It is assumed that the STC waveform at the time when the average luminance level becomes equal to the reference signal level is locked by the STC waveform generation circuit 6. This is to avoid adverse effects caused by STC waveform fluctuations due to movement of the target organ, etc. when operating at real term.

The operation of the device configured as above will be explained.

For example, an explanation will be given by taking as an example an operation in which the brightness level is made uniform by steps 1 to 3 corresponding to each of FIGS. 2 to 4.

Figures 2 (a), (b), and (c) are characteristic diagrams for explaining the operation of step 1. First, under a flat state where the STC waveform is not controlled in any way, Figure 2 (a) ), the brightness of the image signal is in a state where the maximum value limiter works in the shallow part and the minimum value limiter works in the deep part, and in the intermediate band, the brightness attenuates rapidly as the depth increases.

This luminance signal is sent to the A/D converter 3. The signal is input to the calculation circuit 5 via the line memory 4, and the average level is calculated for each section in the depth direction. The result is shown in FIG. 2(b). Incidentally, assuming that the level indicated by the broken line in FIG. 2(b) is the reference signal level mentioned above, the output of this arithmetic circuit 5 will be the difference between the average level (solid line) and the reference signal level (broken line) for each section. is the result obtained.

The STC waveform generating circuit 6 outputs a waveform that cancels the difference between the average level and the reference signal level for each section. FIG. 2(C) shows the STC waveform, which provides a negative gain on the shallow side and a positive gain on the deep side.

Step 1 is completed by the gain controller circuit 2 varying the gain of the luminance signal based on this STC waveform.

Figure 3 (a>, (b>, and c) is a characteristic diagram for explaining the operation of Step 2, and Figure 3 (a>) shows the luminance signal obtained by the gain control roller in Step 1. , the same figure (b) shows this WA degree low signal average level.

Here, the reason why there is a difference between the reference level in the shallow part and the deep part is because the image signal had reached the saturation level in step 1 and the limiter was activated. Therefore, in this step 2, the ST'C waveform determined by the difference between the average level and the reference level in step 1 is calculated as shown in Fig. 3 (b).
) is corrected based on the difference determined from the characteristics of The resulting STC waveform is as shown in FIG. 3(C). Then, step 2 is completed by performing a gain controller based on this STC waveform.

Next, the operation in step 3 will be explained based on FIGS. 4(a) to (C).

Figures 4(a) and 4(b) respectively show the image signal after gain adjustment using the STC waveform determined in step 2 and its average level for each section.As shown in Figure 4(b), the average level is the standard. Match the signal level. Therefore, it can be seen that 17 images with uniform brightness in the depth direction were created. still,
The STC waveform at this time is the same as the STC waveform in step 2 (see FIGS. 3(C) and 4(C)). That is, this is because the STC waveform at the time when the average luminance level becomes equal to the reference signal level is locked.

Through the operations described above, it is possible to obtain a display image with uniform brightness.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

What must be noted in the above calculation is the handling of echo signals from low reflectors such as blood vessels within the diagnosis target site and strong reflectors such as tissue boundaries.

As shown in Fig. 5, when an STC waveform is generated by simply averaging the image signals on the ultrasonic raster including the low reflector A and the strong reflector B, the STC waveform becomes uneven. , which has a negative effect on the image.

This problem can be solved by the arithmetic circuit 5 that takes such singularities into consideration. That is, due to the nature of ultrasonic waves, the average echo level normally attenuates monotonically in the depth direction.

Therefore, when calculating the average level, the calculated values of the calculated point and the points before and after are compared, and any point that does not match the monotonous decay is regarded as a singular point, and the true calculated value of that point is ignored.
This can be solved by using the interpolated value from the calculation results before and after this as the value at that point.

In addition, in the above embodiment, the average level was rarely calculated using one representative ultrasound raster, but if the displayed image contains various organs, one ultrasound raster to be length-amplified is used. It is necessary to generate an STC waveform by making a comprehensive judgment from multiple ultrasonic rasters.

FIG. 6 is a block diagram of an embodiment showing an example thereof, and the calculation circuit 5 is composed of a depth direction average signal level calculation circuit 5A and a raster direction average signal level calculation circuit 5B. Then, the difference between the average signal level in the raster direction and the reference signal level is determined by the arithmetic circuit 5B, and the < s - r c waveform is corrected based on the numbing result in the depth direction using this arithmetic result. There is.

As a result, it is possible to simultaneously correct differences in raster color sensitivity due to the transducer increase/decrease method of the electronic linear probe or sensitivity differences due to differences in the angle of incidence of the sector probe into the body.

[Effects of the Invention] As explained above, according to the present invention, the STC waveform that cancels the difference between the luminance average level for each section in the depth direction and the reference signal level is fed back to the gain adjustment. , use probe.

Even if the diagnosis site or subject changes, the brightness of the displayed image can be made uniform and an easy-to-see image can be displayed without requiring complicated STC volume adjustment as in the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a main block diagram of an apparatus according to an embodiment of the present invention, and FIG.
Figures (a), (b), (C) to Figure 4 (a), (b),
(c) is a characteristic diagram for explaining the operation of the example device;
Each figure (a) is a characteristic diagram of the image signal, each figure (b) is a characteristic diagram of the average level, each figure (C) is a characteristic diagram of the STC waveform, and Fig. An explanatory diagram when the invention is applied, FIG. 6 is a block diagram of a modified example that also performs sensitivity correction in the raster direction, and FIGS. 7(a) and (b) are conventional ST
It is an explanatory view explaining adjustment by C volume. 1... Reception echo signal processing circuit, 2... Gain control circuit, (b) Fig. 3 CG) Fig. 4

Claims (3)

[Claims] (1) The ST
A gain control circuit that controls the gain of the luminance signal based on the C waveform, and an image display signal that is the output of the received echo signal processing circuit, determine the average level of the signal at least for each section in the depth direction of the subject. an arithmetic circuit that calculates a difference from a reference signal level; and an STC waveform generation circuit that generates an STC waveform that cancels the difference between both levels in each section based on the output of the arithmetic circuit and feeds it back to the gain control section. An ultrasonic diagnostic device characterized by having the following. (2) The arithmetic circuit also calculates the difference between the average level for each section in the raster direction of the ultrasonic scan and the reference signal level, and the STC waveform generation circuit calculates the difference between the average level for each section in the raster direction of the ultrasonic scan, and the STC waveform generation circuit calculates the difference between the average level for each section in the raster direction of the ultrasonic scan, and the STC waveform generation circuit The ultrasonic diagnostic apparatus according to claim 1, which generates an STC waveform that cancels both differences. (3) The calculation circuit compares the calculated values of the average level calculation point and the points before and after, and interpolates the calculated value of the singular point that does not match the monotonous attenuation in the depth direction from the above calculated value of this singular point. An ultrasonic diagnostic apparatus according to claim 1 or 2, which is directed to the following.