JP2648771B2 - Ultrasound image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic image processing apparatus, and more particularly to an ultrasonic image processing apparatus capable of optimizing the degree of amplification of a received signal by feedback adjustment.

[0002]

2. Description of the Related Art There is known an ultrasonic image processing apparatus for displaying an in-vivo tomographic image or the like based on a reception signal obtained by transmitting an ultrasonic wave into a living body and receiving a reflected wave.
This ultrasonic image processing apparatus is, in other words, an ultrasonic diagnostic apparatus.

In a conventional ultrasonic image processing apparatus, a received signal is first passed through an amplifier, and after the received signal is amplified, a process such as image formation is performed. Was generally determined by artificial designation. That is, by operating a knob provided on an operation panel or the like of the ultrasonic image processing apparatus, the amplification degree of the amplifier is determined while monitoring a monitor on which an ultrasonic image is displayed.

[0004] Here, in order to obtain an optimal ultrasonic image, it is necessary to set an appropriate amplification degree in accordance with a part of a living body and an observation depth. Further, it is necessary to adjust the degree of amplification according to the weight, body shape, and the like of the subject.

[0005]

However, in the prior art, since the amplification of the amplifier has been artificially adjusted as described above, the operation is cumbersome, and a certain degree of optimization is required to optimize the amplification. There was a problem that skill was required. In particular, there is a strong demand to reduce the operation of the apparatus as much as possible when performing ultrasound diagnosis during surgery.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an ultrasonic image processing apparatus capable of automatically adjusting the amplification degree of a received signal to automatically set an optimum amplification degree. It is to provide a device.

[0007]

In order to achieve the above object, the present invention includes an amplifier for amplifying a received signal, and an amplifier for displaying an ultrasonic image corresponding to a luminance value of the level of the received signal. In the sound wave image processing apparatus, a histogram generating means for inputting the received signal after passing through the amplifier, graphing the number of pixels for each density value and generating a luminance distribution histogram, and a maximum of the generated luminance distribution histogram
A peak value retrieving means for retrieving the peak value of the preset reference peak value, the shift amount calculation means for calculating a shift amount of the luminance distribution histogram by subtracting the retrieved maximum peak value, the luminance distribution Amplification degree determination means for determining the amplification degree of the amplifier from the shift amount of the histogram,
And use the largest peak of the luminance distribution histogram.
In this method, the entire brightness distribution histogram is shifted to optimize the center brightness of the entire ultrasound image.

[0008]

Before describing the operation of the above configuration, the principle of the present invention will be described.

FIG. 6 shows a histogram in which the horizontal axis indicates the density value and the vertical axis indicates the number of pixels (the number of data). It is known from experience that when a histogram is created for an ultrasonic wave such as a tomographic image, generally a Gaussian distribution is generally obtained. This is the same for both the histogram 101 corresponding to the brighter image and the histogram 102 corresponding to the darker image, and the histogram is formed by a Gaussian distribution whose both ends are gradually reduced.
As is well known, for example, blood flow and muscle
When two parts are included, two peaks are generated.
Sometimes.

On the other hand, an image which is most easily seen from experience is about 80, with the maximum density value being, for example, 255, and a histogram in that case is shown by 103 in FIG.

Here, the reference value at which the peak of the histogram 103 exists is 80 as described above.

Therefore, in the present invention, a histogram corresponding to the ultrasonic image is created by utilizing such characteristics of the ultrasonic image, and how much the histogram is shifted from the reference histogram 103 is determined. Asked,
Feedback control is performed to further reduce the difference. In this case, the amount of movement of the histogram depends on the degree of amplification of the amplifier that amplifies the received signal.

Therefore, according to the above configuration, the histogram is created by the histogram creating means, and the peak of the histogram is searched by the peak value searching means. Thereafter, the shift amount calculating means subtracts the searched peak value from a preset reference peak value to obtain a shift amount of the histogram. The amplification degree determining means determines the amplification degree of the amplifier from the shift amount. In the present invention,
Since the histogram is based on the largest peak,
Brightness peak is affected by the brightness control
Never.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a preferred embodiment of an ultrasonic image processing apparatus according to the present invention, and FIG. 1 is an overall configuration diagram thereof. The ultrasonic probe and the like are not shown. The reception signal output from the ultrasonic probe is input to an amplifier 10 for amplifying the reception signal, and the output of the amplifier 10 is converted into a digital signal by an A / D converter 12 and then stored in a memory 14. Written. The memory 14 is constituted by, for example, a digital scan converter, and the read image data is displayed on the monitor 16 as an ultrasonic image.

In this embodiment, there is provided a gain control section 18 for inputting a reception signal output from the amplifier 10 and performing feedback control of the gain of the amplifier 10. Hereinafter, a specific configuration of the gain control unit 18 will be described.

The received signal output from the amplifier 10 is first input to an A / D converter 20 and converted into a digital signal. Here, the A / D converter 20 corresponds to the number of gradations of the image displayed on the monitor 16, and for example, a 6-bit A / D converter is used. Note that the number of gradations of an image displayed on the monitor 16 is specifically determined by the A / D converter 12, and in the present embodiment, the A / D converter 12 is also a 6-bit A / D converter. A converter is used. Therefore, the output of the A / D converter 12 may be input to the gain control unit 18.

The area setting circuit 22 sets an area to be referred to when creating a histogram.

For example, as shown in FIG. 2, an area 202 is set in a part of the ultrasonic image 200. In the example shown in FIG. 2, a fan-shaped ultrasonic image 200 by so-called sector scanning is shown, and an area 202 is set in a deep part of a living body at a certain distance from the ultrasonic probe.
This is because so-called echo noise is likely to occur near the ultrasonic probe and is inappropriate as a reference area. Of course, the area 202 may be configured to be variably set.

In FIG. 2, the received signal in the area extracted in area 202 is input to histogram circuit 24. The histogram circuit 24 forms a histogram in which the horizontal axis indicates the density value and the vertical axis indicates the number of data (pixel number) of each density value. The smoothing circuit 26 smoothes the histogram created by the histogram circuit 24, and has the function of smoothing the histogram. This is to accurately determine the peak of the entire histogram in a peak search performed later.

The peak search circuit 28 scans the smoothed histogram to determine the maximum peak density value.

The gain value judging circuit 30 subtracts the peak value from a preset reference peak value to calculate a shift amount of the histogram. The calculation result is output to the amplifier 10 via the D / A converter 32 as a gain value. Thereby, the amplifier 10 amplifies the received signal with the amplification degree set by the gain value.

Therefore, as shown in FIG. 3A, when the actual histogram 104 is higher than the reference histogram 103, control is performed so that the amplification degree of the amplifier 10 is reduced. As shown, if the actual histogram 105 is lower than the reference histogram 103, control is performed to increase the degree of amplification in the amplifier 10. As a result, if the reference value is finally 80, for example, the reference value 8
Amplifier 10 so that the histogram has a peak at 0.
Is subjected to feedback control.

FIG. 4 shows the gain control unit 18 shown in FIG.
Is shown in a block diagram. Note that the configuration of the gain control unit 18 illustrated in FIG. 1 is a schematic configuration, and thus includes a configuration that is not illustrated in FIG.

The reception signal A / D converted by the A / D converter 20 is extracted in a predetermined area by an area setting circuit 22, and the extracted reception signal is once written in a frame memory 40. It is. In creating the histogram, the selector 42 has selected the frame memory 40, and data is read one by one from the frame memory 40 and output to the histogram RAM 44. Specifically, the received signal input via the selector 42 is supplied to an address terminal of the histogram RAM 44.

In the histogram RAM 44, when the address is specified, the numerical value output from the latch circuit 46 is written to that address. Here, the increment circuit 48 adds “1” to the numerical value read out by the address designation of the histogram RAM 44 and outputs the numerical value.
It is latched by. Therefore, the histogram RA
If an address is specified in M44, the numerical value written to that address is read, and then the numerical value added by "1" is written to the same address.

Such processing is performed for each density value (0 to 255).
And a histogram is finally created in the histogram RAM 44.

After the creation of the histogram, the selector 42 is selected by the read counter 50, and the read counter 50 outputs a count signal for each step from 0 to 255. This count signal is supplied to the address terminal of the histogram RAM 44 via the selector 42, and the frequency data stored at the designated address is sent to the smoothing circuit 26.

More specifically, the frequency data read from the histogram RAM 44 is sent to a cyst register 52 comprising 16 storage elements in this embodiment, and the shift register 52 stores 16 frequency data. Will be. That is, the shift register 52 determines a window to be referred to when smoothing the histogram. First, the frequency data of 0 to 15 is processed, and then the numerical data of 1 to 16 is processed. , Such operations are sequentially repeated. Here, all 16 frequency data read from the shift register 52 are all added by the adder 54, and the result is temporarily held in the latch circuit 56 and supplied to the peak search circuit 28. That is, after the addition by the adder 54, it is normally necessary to divide the addition result by the number of frequency data.
There is no problem in calculation if the histogram after smoothing is taken as the multiplied value, so the division operation is omitted in this embodiment.

Therefore, the smoothed circuit 26 outputs smoothed frequency data of each density value. The frequency data is sent to one input terminal of a comparator 58 in the peak search circuit 28. On the other hand, the frequency data output from the latch circuit 60 is input to the other input terminal of the comparator 58. Here, the comparator 58 outputs the signal 203 when the frequency data input to one input terminal is larger than the frequency data input to the other input terminal. Here, the signal 203 is sent to the above-described latch circuit 60, and the latch circuit 62 for inputting the count signal of the read counter 50.
Has been sent to Therefore, the latch circuit 60 latches the largest frequency data among the frequency data of the respective density values sequentially output from the smoothing circuit 26, that is, the frequency data at the peak, while the latch circuit 62 latches the peak data at the peak. Is latched. As a result, the density value at which the peak exists is determined.

In the gain value determination circuit 30, the density value of the histogram peak output from the latch circuit 62 is
The signal is sent to one input terminal of the subtractor 64. A reference value is input to the other input terminal of the subtractor 64. This reference value indicates the position of the peak of the histogram serving as the reference, and is set to, for example, 80.

Therefore, the subtractor 64 subtracts the actual peak density value from the reference value and outputs the subtracted value. Here, the subtraction value indicates the shift amount up to the above-described reference spectrum. The subtraction value output from the subtractor 64 is input to a multiplier 66, where it is multiplied by a constant weight α. Here, as α, for example, 0.25
Is set. By this weighting, the density value can be gradually changed without rapidly changing the ultrasonic image. To the adder 68, a subtraction value from the subtractor 64 as a shift amount is input to one input terminal, and a signal latched by the latch circuit 70 is input to the other input terminal. That is, the shift amount is added to the current gain by the operation of the adder 68 and the latch circuit 70, and the gain value to be updated is calculated. This gain value is supplied via the D / A converter 32 to the amplifier 10 shown in FIG.
And the amplification degree is controlled.

As shown in FIG. 5, a configuration for adjusting the contrast according to the histogram pattern may be added. In this case, a circuit for recognizing the pattern of the histogram created by the histogram circuit 24 is provided, and the contrast on the monitor 16 is adjusted according to the amount of mismatch with the pattern.

[0034]

As described above, according to the ultrasonic image processing apparatus of the present invention, the maximum luminance distribution histogram can be obtained.
Of the luminance distribution histogram using the peak of
By performing the shift, the amplification degree of the amplifier that amplifies the received signal is feedback-controlled, so that an optimal ultrasonic image can always be automatically formed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an ultrasonic image processing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an area 202 to be referred to.

FIG. 3 is an explanatory diagram showing two histograms shifted from a reference histogram.

FIG. 4 is a block diagram illustrating a specific configuration of a gain control unit.

FIG. 5 is an explanatory diagram showing a histogram change due to contrast adjustment.

FIG. 6 is an explanatory diagram showing a lighter histogram and a darker histogram with respect to a reference histogram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Amplifier 18 Gain control part 24 Histogram circuit 28 Peak search circuit 30 Gain value judgment circuit

Continuation of the front page (56) References JP-A-62-117534 (JP, A) JP-A-60-206392 (JP, A) JP-A-64-62137 (JP, A) Television and image information engineering handbook Television Society of Japan, November 30, 1990, Ohmsha Publishing Co., Ltd., 397-402

Claims (1)

(57) [Claims] 1. An ultrasonic image processing apparatus that includes an amplifier that amplifies a received signal and displays an ultrasonic image in which the level of the received signal corresponds to a luminance value, wherein the received signal after passing through the amplifier is input. A histogram creating means for creating a luminance distribution histogram by graphing the number of pixels for each density value; a peak value searching means for searching for a maximum peak value of the created luminance distribution histogram; From the peak value, the searched maximum
A shift amount calculating unit that obtains a shift amount of the luminance distribution histogram by subtracting the peak value of; and an amplification degree determining unit that determines an amplification degree of the amplifier from the shift amount of the luminance distribution histogram. Using the largest peak,
An ultrasonic image processing apparatus, wherein the entire luminance distribution histogram is shifted to optimize the central luminance of the entire ultrasonic image.