JPH0231972B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a medical ultrasonic linear scan device, and more specifically, in a digital scan converter, a sound ray (a line of sight vector in the case of an aperture synthesis method) and a display scanning line are substantially perpendicular to each other. This invention relates to improvement of image quality or resolution in scan conversion.

(Prior Art) Conventionally, in medical ultrasonic linear scan devices, as shown in the schematic diagram of the display screen in FIG. This is converted into a digital signal and then stored in memory. After collecting the echo signal, the image is displayed in a direction (X) suitable for the display method of the monitor television, that is, in a direction (azimuth) that is approximately perpendicular to the sound ray direction (Y) shown in FIG. (direction) and performs appropriate processing. In this case, the echo data is read out in the memory in a different order from the order in which it was written, and a digital scan converter (hereinafter referred to as DSC) is used as such a device.

Smoothing processing is applied to the data read out from such DSCs to improve image quality, but in conventional devices, smoothing in the sound ray direction is performed by analog processing beforehand when writing to the frame memory for the display device. At the signal stage, the ultrasonic video signal is passed through a filter, and smoothing in the horizontal direction, that is, in the raster direction of television (hereinafter referred to as TV), is performed from the frame memory.
This was done by reading out at TV speed, converting it to analog, and passing the resulting TV video signal through a filter.

Incidentally, smoothing in this case is performed using a filter whose characteristics are fixed while one screen is being displayed, at least in the horizontal direction (azimuth direction), at least in the sound ray direction.

In linear scan or similar scanning methods, the azimuth resolution of deep areas (the lower part in Figure 1) is limited by the aperture ratio, so no matter how much you try to narrow the beam using an electronic focus or beam focusing lens, there is a limit. The problem is that it doesn't get better.

Conventional devices scan deep areas, intermediate areas, and close ranges with exactly the same sound ray density or data rate. There is a problem in that although the optimum degree of smoothing essentially depends on the depth, it is fixed and uniformly applied.

(Object of the Invention) The present invention has been made in view of the above-mentioned points, and its purpose is to change the degree of smoothing in the azimuth direction as a function of depth to obtain optimal smoothing for medical purposes. An object of the present invention is to provide an ultrasonic linear scan device.

(Structure of the Invention) The present invention achieves this object by vertically and horizontally converting image data obtained by ultrasonic linear scan through a digital scan converter to obtain a television system video signal. An ultrasonic linear scan device for displaying ultrasonic images using an ultrasonic linear scan device is equipped with a variable low-pass filter whose cutoff frequency is controlled by a vertical deflection signal, and the television system video signal is passed through the variable low-pass filter to The present invention is characterized in that the smoothing of the acoustic wave image in the azimuth direction is made variable in the depth direction.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram of main parts showing an embodiment of the present invention. In the figure, 1 is a frame memory, in which an echo video signal (digital signal) that has been sampled by linear scan or a similar method and has been subjected to appropriate signal processing is stored (1
frame). Frame memory 1 data is CRT
The signals are sequentially read out by addressing from the address generator 2 in synchronization with the display on the screen, converted into analog signals through the D/A converter 3, and then passed through the variable low-pass filter 4 where smoothing is performed.
After passing through filter 4, it passes through video amplifier 5.
The signal is applied to the CRT display tube 6. The band characteristics of the variable low-pass filter 4 are controlled by the vertical deflection signal from the vertical deflection circuit 7. The CRT display tube 6 is deflected and driven by outputs from a vertical deflection circuit 7 and a horizontal deflection circuit 8. Reference numeral 9 denotes a synchronization signal generation circuit, which provides necessary synchronization signals to the address generation circuit 2, vertical deflection circuit 7, and horizontal deflection circuit 8.

In such a configuration, the variable low-pass filter 4 is controlled by the vertical deflection signal, and suppresses the degree of smoothing for echo signals corresponding to shallow parts, and increases the degree of smoothing for echo signals corresponding to deep parts. and act to correct the deficiencies.

When this appropriately smoothed echo signal is displayed on the CRT display tube 6, flickering, glare, or roughness in the image can be removed.

(Effects of the Invention) As described above, according to the present invention, a video signal is passed through a low-pass filter whose cutoff frequency changes as a function of depth, and smoothing processing is performed in the azimuth direction of an ultrasound image. ,
It is possible to suppress flickering and glare in the displayed image.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the relationship between the sound ray direction and the television scanning direction, and FIG. 2 is a diagram showing the main part configuration of an embodiment of the present invention. 1... Frame memory, 2... Address generator, 3... D/A converter, 4... Variable low pass filter, 5... Video amplifier, 6... CRT display tube, 7... Vertical deflection circuit, 8 ...horizontal deflection circuit,
9...Synchronization signal generation circuit.

Claims (1)

[Claims] 1 An ultrasonic linear scan device that converts the image data obtained by ultrasonic linear scan vertically and horizontally through a digital scan converter to obtain a television system video signal, and displays an ultrasonic image using the television system video signal. is provided with a variable low-pass filter whose cut-off frequency is controlled by a vertical deflection signal, and by passing the television-type video signal through the variable low-pass filter, smoothing of the ultrasound image in the azimuth direction is performed with respect to its depth direction. An ultrasonic linear scan device having a variable video dynamic filter.