JP2590883B2 - Digital X-ray equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray apparatus, and more particularly, to a digital radiography (DR) for digitizing an X-ray image.
And a digital X-ray apparatus.

[Prior art]

The X-ray apparatus widely used at present is based on the X-ray imaging method using a film screen system. However, although the resolution is excellent, the gradation processing and the spatial frequency due to the fixed image of the film image are performed. There is a drawback that there is no adaptability to image processing such as processing. Therefore, in recent years, X-ray images are digitized and handled.
DR equipment has been developed. This adopts a film digital system in which an X-ray film is read and processed by a laser scanner, a system using an imaging plate, or the like.

[Problems to be solved by the invention]

However, all of these methods have a problem that a large amount of time is required mainly for reading an image, an image cannot be displayed immediately after photographing, and lack of immediacy. In addition, since these are exactly the same as the film-screen system in the process of exposure to X-rays, the speed of image capture is limited and the time resolution is low. SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and inexpensive digital X-ray apparatus capable of processing an X-ray image having a very high spatial resolution at high speed in real time.

[Means for solving the problems]

According to the present invention, an X-ray tube, an image intensifier, a television camera for photographing an output image of the image intensifier and outputting a video signal, In a digital X-ray apparatus including an A / D converter for sampling, A / D converting and outputting, and a digital image processing apparatus for processing and outputting the image data, m and n are each a natural number of 2 or more, k is a natural number of 2 or more smaller than n, and the television camera has a horizontal scanning number of m times the number of horizontal scanning lines of the standard video signal, and one horizontal scanning period is equal to the standard video signal. A television camera that performs horizontal / vertical scanning so as to output a video signal that is k times as long as one horizontal scanning period of the horizontal scanning period. An A / D converter that samples at the number of ring points n and stores and outputs (n / k) pixel data per word is stored in the digital image processing apparatus in one word (n / k). k) The pixel data is processed in parallel for each pixel, and the processed image data is
A digital image processing device that stores (n / k) pixel data in a word and outputs the data. Further, output data from the digital image processing device is input and written, and read out based on a different scanning method. And a scan conversion memory.

[Action]

In order to output a video signal of a high-definition image from a television camera, it is necessary to increase the number of horizontal scanning lines and lengthen one horizontal scanning period in order to increase the resolution of one horizontal scanning line. For example, in order to increase the resolution of an image by m times in the vertical direction and by n times in the horizontal direction (m and n are natural numbers of 2 or more) as compared with the standard system (NTSC system), the number of horizontal scanning lines is m. And one horizontal scanning period is n
You can double it. In this case, the transmission speed of the video signal is the same as that of the standard system, and the speed of the processing device for processing the video signal can be a normal speed. However, in this case, the frame rate becomes 1 / (mn), the image refresh rate becomes extremely slow, and the time resolution of the image deteriorates. On the other hand, if one horizontal scanning period is the same as the standard, the frame rate becomes 1 / m, which is not so slow. However, if one horizontal scanning period is the same as the standard, it is difficult to increase the resolution of the image in the horizontal direction. In other words, if one horizontal scanning line is sampled at a point n times the standard, it is possible to increase the horizontal resolution to n times the standard, but scanning was performed in the same one horizontal scanning period as the standard. This is because the analog resolution itself of the horizontal scanning line is originally inferior to that obtained when one horizontal scanning period is read as n times the standard period. In addition, since sampling is performed at n times the number of points in one standard horizontal scanning period, there is a difficulty that the A / D converter has to have a high sampling rate. Even if it is possible, the data of n times the pixels will be output during that period, so the transmission rate will be high, and the data transmission system and the digital image processing device for processing the data will be specially constructed with high speed. There is also the difficulty of having to use a proper one. Therefore, considering the balance between the resolution in the horizontal direction of the image, the time resolution of the image, and the speed of the A / D converter and the processing system, one horizontal scanning period is set to k times the standard (k is smaller than n. Although the image resolution in the horizontal direction is inferior to n times as the above (natural number), it is higher than the standard period, and after sampling n points in one horizontal scanning period of k times, Further, as the output of the A / D converter, 1
It is assumed that (n / k) pixel data is stored per word. As a result, the transmission speed per word can be the same as that for storing data of one pixel per word for a standard video signal. Therefore, a standard transmission system from the A / D converter to the digital image device can be used. Further, the digital image processing apparatus also outputs the processed image data by storing data of (n / k) pixels per word, so that a standard transmission system may be used. Further, the image data after this processing is transmitted to the scan conversion memory and written therein, and is read out based on a different scan method. For example, the image data is read out by a standard method such as an interlace method and sent to a standard method monitor television device. Can be displayed. The difficulty is that A / D converters and digital image processing devices are somewhat special. That is, the A / D converter stores and outputs (n / k) pixels of data per word, and the digital image processing apparatus stores (n / k) pixels of data stored in one word. Is processed in parallel for each pixel, and the processed image data is required to store and output (n / k) pixel data in one word. However, these specialities are also minimized, and are not expensive compared to the case where the transmission speed and processing speed are increased. For example, if the resolution of a standard image is 4
In order to obtain a high-definition image (approximately 2000 × 2000 pixels) that is four times larger and four times in the horizontal direction, if the horizontal scanning line is simply quadrupled (about 2,000 lines), one horizontal scanning period is quadrupled. For example, if the frame rate is 1/16 of the standard and it is less than 2 frames per second, if the horizontal scanning line is only quadrupled while the horizontal scanning period is the same, the frame rate will be every second
Although it is not late at 7.5 frames, the image resolution in the horizontal direction deteriorates. On the other hand, if k = 2,
With the above, the frame rate is 3.75 frames per second, which is not so slow, and the image resolution in the horizontal direction is reasonable. After all, the horizontal resolution of the image, the time resolution of the image, The best balance between the speed of the A / D converter, the transmission system and the digital image processing device, and the manufacturing cost can be obtained.

【Example】

In FIG. 1, an X-ray emitted from a minimum focus X-ray tube 1 toward a subject 2 passes through the subject 2 and is incident on a large-diameter image intensifier (II) 3. It is converted to a visible light image. This visible light image is input to the television camera 4, and a charge image corresponding to an X-ray transmission image is formed on the target surface of the imaging tube. At this time, in the television camera 4, the charge image reading scan of the imaging surface is performed by the non-interlace method, and a video signal is obtained. However, the horizontal length of the charge image reading horizontal scanning line is about four times that of the normal (NTSC method). The number of scans for one horizontal scanning line is set to about 2,000, and the scanning speed for one horizontal scanning line is set to half the normal speed, and the scanning time for one horizontal scanning line is doubled. Thus, a video signal is obtained at a rate of 3.75 frames per second. This video signal is sampled at a sampling frequency of 20 MHz by the A / D converter 6 of the image processing device 5, and A / D conversion is performed at 2,000 sampling points per horizontal scanning line. As described above, since the number of sampling points per horizontal scanning line is extremely large, the scanning speed in the horizontal direction is reduced as described above to secure the resolution in the horizontal direction. That is, while reducing the horizontal scanning speed,
In response to this, the sampling frequency is lowered, and as a result, the frequency band of the video signal is lowered, so that electrical degradation of the signal in a video signal amplification system or the like is prevented. In this way, digital image data of a high spatial resolution of a 2000 × 2000 image matrix is obtained at 3.75 frames / sec. When obtaining such high spatial resolution image data, the spatial resolution of the image intensifier is limited. However, as described above, the microfocus X-ray tube 1 and the large-diameter image intensifier 3 are combined. The X-ray magnified radiography is performed by arranging the subject 2 with difficulty from the input surface of the image intensifier 3 as shown by the solid line, thereby clearing the image. The large-diameter image intensifier 3 is indispensable for securing a visual field against substantial improvement of the MTF by enlargement and restriction of the visual field by enlargement. When the X-ray magnifying radiography is performed, the scattered radiation is removed by the Gredel effect, so the grid 13 is unnecessary. Mechanism) for effective use of X-rays.
When the subject 2 is brought into close contact with the input surface of the image intensifier 3 as shown by the dotted line, the grid 13 is drawn as shown by a solid line during the contact imaging.
To the input surface of This image data is obtained from the A / D converter 6 at a speed of 20 MHz. However, if this image data is sent to the next arithmetic processing device 7 at the same speed, it is extremely sophisticated due to the hardware capability of the arithmetic processing device 7. Therefore, as shown in FIG. 2, the 16-bit data of one word is divided into upper and lower parts, and the immediately preceding pixel data is stored above and the current pixel data is stored below. The data of two pixels to be processed are collectively handled, transmitted in units of two pixels, the transmission rate is reduced to 1/2 (10 MHz), and the data is processed in parallel within the processing unit 7 in units of two pixels. To reduce the hardware burden and reduce costs. In the arithmetic processing unit 7, for example, recording by a built-in frame memory, image processing such as gradation processing, spatial frequency processing, and inter-pixel calculation are performed in parallel in units of two pixels. The arithmetic processing unit 7 is controlled by a system controller 12 together with an X-ray generator 11 for applying a high voltage to the X-ray tube 1 and the like. The output of the arithmetic processing unit 7 is transferred to the scan conversion memory 8 at a transmission speed of 10 MHz in units of two pixels. The image data input to the scan conversion memory 8 is 3.75 frames / non-interlace scanning method.
Although the image is displayed at the second rate, if the image is displayed on the monitor television apparatus 10 as it is, the frame rate is too low and the image can be seen only by human eyes as a flickering image.
In view of this, the scan conversion memory 8 converts the scanning method and the frame rate so that the image can be seen as a stable image without flicker.
In this embodiment, non-interlaced scanning image data is written into the scan conversion memory 8 at a rate of 3.75 frames / second, and interlaced reading scanning is performed at a rate of 30 frames / second. Image data is read from the scan conversion memory 8 in units of 16 pixels in parallel, and the image data is sent to the D / A converter 9. At this time, despite the readout frame rate of 30 frames / second,
Since reading is performed in parallel in units of 16 pixels, the transmission speed of image data is 10 MHz. The D / A converter 9 converts the image data sent in units of 16 pixels from parallel to serial,
An analog video signal is obtained at a speed of 0 MHz to obtain an analog video signal, which is sent to the monitor television device 10. Therefore,
In this monitor television apparatus 10, an extremely high-definition X-ray image having 2,000 × 2000 pixels vertically and horizontally is displayed in real time at a frame rate of 30 frames / second by an interlaced scanning method.

【The invention's effect】

ADVANTAGE OF THE INVENTION According to the digital X-ray apparatus of this invention, the number of horizontal scanning lines read by a television camera is many times larger than that of the standard system, and the horizontal scanning speed is reduced, so that a high-definition image can be divided into a video signal. Is to obtain a slow video signal, and make sure that the A / D converter for A / D conversion is not required to be fast, and that the output of the A / D converter stores data of multiple pixels in one word. In addition, the digital image processing apparatus to which this image data is sent performs parallel processing on the data of a plurality of pixels stored in one word, and outputs the processed image data with the data of the plurality of pixels in one word. By storing the data, the data is output to the scan conversion memory at a reduced transmission speed, whereby the digital image processing device and the scan converter connected thereafter are stored. So high speed is not required to over John memory, as a whole, while it possible to easy and inexpensive construction, can be processed at high speed a very high high-resolution X-ray image spatial resolution in real time. In addition, since the number of horizontal scanning lines of the television camera is increased and one horizontal scanning period is lengthened, the frame rate of capturing the original image is slower than that of a normal television, but sufficiently faster than that of a film or the like. There is no problem in ordinary medical X-ray photography.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram schematically showing a data structure. DESCRIPTION OF SYMBOLS 1 ... Micro focus X-ray tube, 2 ... Subject, 3 ... Large diameter image intensifier, 4 ... Television camera, 5 ... Image processing device, 6 ... A / D converter, 7 ... ... arithmetic processing unit, 8 ... scan conversion memory, 9
… D / A converter, 10… Monitor television device, 11… X
Line generator, 12 ... System controller, 13 ... Grid.

Claims (2)

(57) [Claims] An X-ray tube, an image intensifier, a television camera for photographing an output image of the image intensifier and outputting a video signal, and the video signal is converted into a plurality of points for each scanning line. Sampling and A / D
In a digital X-ray apparatus including an A / D converter for converting and outputting and a digital image processing apparatus for processing and outputting the image data, m and n are each a natural number of 2 or more, and k is smaller than n. The television camera has two or more natural numbers and the number of horizontal scanning lines is m times the number of horizontal scanning lines of the standard video signal, and one horizontal scanning period is one horizontal scanning period of the standard video signal. The A / D converter comprises a television camera which performs horizontal and vertical scanning so as to output a video signal multiplied by k times. an A / D converter for storing and outputting data of (n / k) pixels, wherein the digital image processing device converts the data of (n / k) pixels stored in one word for each pixel. Parallel processing and after processing Image data, comprised of a digital image processing apparatus for outputting stored in one word of data (n / k) pieces of pixels, further, the output data from the digital image processing apparatus is written is input,
A digital X-ray apparatus, comprising: a scan conversion memory that is read based on a different scan method. 2. The digital X-ray apparatus according to claim 1, wherein an object is arranged away from an input surface of said image intensifier.