JPS60259252A - 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 (Jl) Industrial Field of Application The present invention relates to an ultrasonic diagnostic apparatus, and particularly to an ultrasonic diagnostic apparatus having a freeze function, in which image processing is performed on a frozen ultrasonic image. In particular, the present invention relates to an ultrasonic diagnostic apparatus having a function of obtaining clear frozen images.

Conventionally, in ultrasonic diagnostic equipment, so-called speckle noise, which is thought to occur when multiple reflectors exist in a region below the resolution and the reflected waves from them interfere with each other, has affected the image quality of ultrasonic tomographic images. There is a problem that it deteriorates the

Such noise is not so noticeable in a moving image state because the ultrasound images are updated one after another, but it becomes noticeable in a frozen ultrasound image (frozen image).

Therefore, if a means for image processing is provided in order to remove the speckle noise mentioned above, an image processing means in the moving image state will be required, which will complicate the circuit configuration, and will require additional time in real time due to the image processing time. There was a problem in that ultrasonic tomographic images could not be displayed.

Focusing on the characteristic that the speckle noise is not very noticeable in a moving image, there has been a demand for a method that performs image processing only on still images (frozen images).

Conventional technology Figure 2 shows a block diagram of the main parts of a conventional ultrasound diagnostic system, and Figure 3 shows a one-dimensional ultrasound image and speckle noise in the conventional system. The vertical direction indicates the digital values of the one-dimensional image, and the horizontal direction indicates pixels in the X direction (or Y direction) on the display device.

(a) shows an ultrasound image, and (b) shows speckle noise.

In FIG. 1, 1 is a transducer, 2 is a transmitter,
3 is a receiving section, 4 is an analog/digital converter (^/D
), 5 is an image memory section, 6 is a digital/analog converter (D/A), 7 is a display device, 8 is a control section, and 9 is an image processing section.

Now, when an ultrasound signal is emitted from the transmitter 2 to a living body (not shown) through the transducer 1, ultrasound reflected signals from various parts of the living body are transmitted through the transducer 1 to the receiver 3. received and analog/digital converter (
A/D) 4, the signal is converted into, for example, an 8-bit digital signal, inputted to the image memory unit 5, and stored as frame information in the frame memory 52 via the input sofa memory 51.

The image information in the frame memory 52 is read out through the output Hanofa memory 53 according to the standard television method,
The signal is converted into an analog signal by a digital/analog converter (D/^) 6, and the display device 7 is controlled to display, for example, a B-mode image.

The control unit 8 is in charge of this overall control.

(C) Problems to be Solved by the Invention In such conventional systems, there is a problem in that the speckle noise deteriorates the image quality, and the speckle noise is particularly noticeable in frozen images.

FIG. 3 shows an example of a one-dimensional image on the display device 7, where (a) shows the digital value of each pixel of the ultrasonic tomographic image, and (b) shows the digital value of the speckle noise at any pixel. It shows the value.

Therefore, in a moving image state, even if the speckle noise is randomly placed on each pixel, the screen is updated one after another.
Although it is not so noticeable, in frozen images, the speckle noise shown in (b) above is also frozen and displayed in specific pixels, so there is a problem in that it significantly deteriorates the image quality of the frozen images.

Therefore, one possible method would be to install an image processing section 9 shown by a dotted line in the ultrasound diagnostic apparatus shown in Fig. 2 to remove the speckle noise, but this would require image processing in a moving image state. For example, each frame is subjected to image processing, and the relevant spec noise is removed before being input to the image memory unit 5, which complicates the circuit configuration and requires time for image processing. There was a problem that it became impossible to display in real time.

In view of the above-mentioned conventional drawbacks, the present invention focuses on the characteristic that even if the speckle noise is present in an ultrasound tomographic image, it is not very noticeable when the image is a moving image as described above, By applying image processing to the ultrasound image for one frame only when obtaining a high-quality ultrasound image, it is possible to reduce speckle noise, etc., and to obtain a high-quality ultrasound image that does not dull the edges of the ultrasound image. The purpose of this invention is to provide a method for obtaining a frozen image.

According to the present invention, the means for solving the fdl problem and the purpose thereof are as follows: (1) transmitting an ultrasound signal into a living body, receiving the ultrasound signal reflected from the living body, and An ultrasonic diagnostic apparatus having a function of freezing an ultrasonic tomographic image of a region, comprising an image processing means, and a method of performing image processing only on one frozen frame of the ultrasonic image.

(2) A method of using a median value detection circuit (median filter) in the image processing means.

This is achieved by providing

In other words, according to the present invention, attention is paid to the speckle noise that occurs on a still image of an ultrasonic tomogram, and as a means to reduce the noise, only one frozen frame image is used. Since it performs image processing and uses a median value detection circuit (median filter) as the image processing means, it is possible to reduce speckle noise that is noticeable in frozen images, and it also prevents the edges of ultrasound images from becoming dull. In addition to being able to obtain clear ultrasonic images, since image processing is performed only on frozen images, the image processing circuit does not become complicated.

(f) Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, (a) is a diagram showing the overall configuration, and (b) is a diagram showing the median value detection section included in the image processing section 9'. FIG. 2 is a block diagram showing the details of FIG.

In FIG. 1(A), 1 to 7 are the same as those explained in FIG. 2, and 8' has the same function as the control section 8 explained in FIG. The difference is that the image processing unit 9° is activated to perform image processing only when the ultrasound tomographic image is frozen.

It is now assumed that an ultrasonic tomographic image is being displayed on the display device 7 according to the procedure described in the conventional method.

At this point, when the freeze key is pressed at a desired timing, only one frame of information at that time passes through the image processing section 9' according to a control signal from the control section 8', and undergoes image processing (median value detection processing). ) will be displayed on the display device 7 as a frozen image.

The present invention will be described in detail using a one-dimensional image in the case where a median value detection circuit (median filter) is used as the image processing means.

FIG. 4 is a diagram conceptually explaining the effects of the present invention, and for comparison, the case where an average value detection circuit (not shown) is used as an image processing means is shown in (b), and the main focus of the present invention is shown in FIG. The case using a median detection circuit (median filter) is shown in (a).

Moreover, (a) shows an ultrasonic image signal, and (b) shows a speckle noise signal.

In each drawing, the upper diagram shows the case where no image processing is performed, and the lower diagram shows the case where image processing is performed.

It is now assumed that the one-dimensional image signals shown in the upper portions of (a) and (b) of FIG. 4 are input to the image processing section 9 as a frozen image.

When this image signal is displayed through a 'window 3' median detection circuit (median filter), it becomes as shown in the lower part of the figure (a).

The operation of the median value detection circuit (median filter) of "Wind 3" is to look at the digital values of adjacent pixels of 3 ([!it) and output the median value. An example of a specific circuit is shown in FIG. 1(b).

In this figure, reference numeral 10.11 is a launch circuit that holds n-bit digital information, and while shifting the n-bit digital information every clock, it always changes the digital information corresponding to three pixels to +'/ +2 is input to the median value detection circuit (median filter) 12.

And median value detection circuit (median filter) 12
The function is to check +3'+2 for the above three pieces of digital information every clock and output the median value among them.

For example, in (a) of FIG. 4(a), since the three pieces of digital information indicated by ■ are "003'," the median value at this time is "Oo." In the same way, 3 shown with ■
Since the digital information of 3 is 035°, the median value in this case is 3, and the 3 digital information in case 2 is 534°, so the median is 4.

Similarly, looking at the case (b) showing speckle noise, it can be seen that the median value is 0゛ in all cases ①, ②, and ②.

The image at the bottom of (a) shows the image processing results obtained in this way, and as you can see from this image, the processing of the ultrasound image does not become dull. In addition, regarding speckle noise, the median detection circuit (median
When the speckle noise is passed through a filter), the speckle noise disappears.

The case of FIG. 4(B) shows a case where an average value detection circuit is used as the image processing means, and the above three pieces of digital information X, y, Z are checked every clock, It functions to output the average value of all digital values.

For example, looking at case (a) showing an ultrasound image, in the case of ■゛, which corresponds to the case of ■ above, the three pieces of digital information are “003°, so the average value is 1
In the case of ゛ and ■'', the three pieces of digital information are ``0''.
35', the average value is 8/3.

Similarly, when looking at the case (b) showing speckle noise, it can be seen that the average value is "1" in any case of ■゛, ■゛, and ■゛.

It can be seen that in this image processing method, the edges of the ultrasonic image become dull, and although the noise level is reduced with respect to speckle noise, it becomes wider.

The above is an explanation of one-dimensional image information, but regarding two-dimensional frozen images as well, one-dimensional image information of the frozen image
By using the median value detection circuit (median filter) explained in Figure 4 (a) only for frame information as an image processing means, a clear frozen image can be obtained every 1M without complicating the circuit configuration. Become.

What) Effects of the Invention As explained in detail above, the ultrasonic diagnostic apparatus of the present invention focuses on the speckle noise that occurs on a still image of an ultrasonic tomogram, and serves as a means for reducing the noise. , image processing is performed only on one frame image with freeze,
Since it uses a median detection circuit (median filter) as the image processing means, it can reduce the speckle noise that is noticeable in frozen images, and it can also provide clear images without dulling the enon of ultrasound images. In addition to being able to obtain accurate ultrasound images, since the configuration is such that image processing is performed only on frozen images, there is an advantage that the image processing circuit does not become complicated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 shows the configuration of a conventional ultrasound diagnostic apparatus. FIG. 3 shows an ultrasound tomographic image and speckle noise as a one-dimensional image signal. FIG. 4 is a diagram conceptually explaining the effects of the present invention. It is. In the drawing, 1 is a transducer, and 2 is a transmitter. 3 is the receiving section. 4 is an analog/digital converter (A/D). 5 is an image memory section. 6 is a digital/analog converter (D/A). 7 is a display device, and 8, 8° is a control unit. 9.9° is the image processing section, 10.11 is the latch. 12 is a median value detection circuit. are shown respectively. Agent Patent Attorney Hiroshi Matsuoka Department 1 Figure

Claims (2)

[Claims] (1) An ultrasound diagnostic device having a function of transmitting ultrasound signals into a living body, receiving ultrasound signals reflected from the living body, and freezing an ultrasound tomographic image of a part of the living body, An ultrasound diagnostic apparatus comprising an image processing means and a function of performing image processing only on the frozen one-frame ultrasound image. (2) The ultrasonic diagnostic apparatus according to claim 1, wherein the image processing means uses a median value detection circuit.