JPS63300743A - Digital x-ray apparatus - Google Patents

Abstract

PURPOSE:To stably display an X-ray image of high resolving power in real time, by obtaining the image of a predetermined frame rate of an interlace scanning system using a scanning converter. CONSTITUTION:The X-rays from a fine focus X-ray tube 1 irradiate an object 2 to be examined and the transmitted X-ray image thereof is taken up by a large caliber image intensifier 3 and a television camera 4. The video signal from the TV camera 4 is inputted to the A/D converter 6 of an image processor 5 and sampled at many points at every scanning line to be converted to a digital video signal by the A/D converter 6. The digitalized video signal is processed by an operational processor 7 to be stored in a scanning conversion memory 8 and subsequently read according to a predetermined interlace system and sent out to a monitor TV apparatus 10 through a D/A converter 9.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an X-ray device, and in particular to digital radiography (DR), which digitizes and handles X-ray images.
This invention relates to a digital X-ray device that performs.

[Conventional technology]

The currently widely used X-ray equipment uses a film-screen system for X-ray imaging, but while it has excellent resolution, the fixed film image makes it difficult to perform gradation processing and spatial frequency. The disadvantage is that it is not adaptable to image processing such as image processing. Therefore, in recent years, D
An R device has been developed. This method employs a film digital method in which X-ray film is read and processed with a laser scanner, or a method using an imaging plate.

[Problems to be solved by the invention]

However, all of these methods mainly require a large amount of time to read the image, and the image cannot be displayed immediately after being photographed, so there are problems in that immediacy is lacking. In addition, in the X-ray exposure process, these
Since it is exactly the same as the screen system, there is a limit to the image capture speed and the temporal resolution is low. An object of the present invention is to provide a digital X-ray device that has a high image capture speed, excellent temporal resolution, high immediacy, and is capable of stably displaying extremely high-resolution X-ray images in real time. With the goal.

[Means for Solving the Problems] ゛The digital X-ray device according to the present invention includes an X-ray tube, a large-diameter image intensifier, and a number of reading scanning lines for photographing an output image of the image intensifier. A large number of television cameras and video signals from these television cameras are sampled at multiple points for each scanning line.
The present invention is characterized by comprising an A/D converter that performs /D conversion, and a digital image processing device that has a scan converter that stores digitized video signals and reads them out at a predetermined rate in an interlaced scanning method.

[For production]

A television camera with a very large number of scanning lines to read,
By combining this with an A/'D converter that samples the video signal from the television camera at multiple points for each scanning line and converts it A/D, high-definition images with a very large number of pixels (for example, 2000 x 2000) are produced. However, if the number of pixels in one image is increased in this way, the frame rate cannot be increased due to hardware constraints at the imaging and data processing stages. Therefore, by using a scan converter, the image is converted into an interlaced scanning image at a predetermined frame rate, and an image that does not flicker to the human eye is displayed.

【Example】

In the figure, X-rays irradiated from a microfocus X-ray tube 1 toward a subject 2 pass through the subject 2 and enter a large-diameter image intensifier (1, 1,) 3, resulting in an X-ray transmission image. is converted into a visible light image. This visible light image is input to the television camera 4, and a charge image corresponding to an X-ray transmitted image is formed on the image pickup tube target surface. At this time, in this television camera 4, charge image readout scanning of the imaging surface is performed in a non-interlaced manner, and a video signal is obtained. The number of lines is about 2,000, and the scanning speed for one horizontal scanning line is 1/2 of the normal speed, and the scanning time for one horizontal scanning line is twice the normal speed. This results in a video signal 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 bag M5,
A at 2000 sampling points per horizontal scanning line
/D conversion is performed. Since there are a large number of sampling points per horizontal scanning line, the horizontal scanning speed is slowed down to ensure horizontal resolution as described above. In other words, the horizontal scanning speed is slowed down, and the sampling frequency is correspondingly lowered, thereby lowering the frequency band of the video signal and preventing electrical deterioration of the signal in the video signal amplification system, etc. . In this way, the high spatial resolution digital image data of the 2000×2000 image matrix is
Obtained at 5 frames/second. By the way, when obtaining such high spatial resolution image data, the limit of the spatial resolution of the image intensifier becomes a problem. This problem is cleared by placing the subject 2 away from the input surface of the image intensifier 3 as shown by the solid line and performing enlarged X-ray imaging. The large-diameter image intensifier 3 is indispensable to substantially improve MTF due to enlargement and to secure a field of view against field of view limitations caused by enlargement. When performing magnified X-ray imaging, the grid 13 is unnecessary because scattered rays are removed by the Gredel effect. mechanism) to make effective use of X-rays. Note that when close-up imaging is performed with the subject 2 brought into close contact with the input surface of the image intensifier 3 as shown by the dotted line, the grid 13 is attached to the input surface of the image intensifier 3 as shown by the solid line. This image data is obtained from the A/D converter 6 at a speed of 20 MHz, but if it were sent to the next processing unit 7 at the same speed, the hardware capability of the processing unit 7 would have to be extremely sophisticated. Here, we will send data in units of 2 pixels to increase the transmission speed to 1. / 2 (10MHz
), and parallel processing is performed in units of two pixels inside the arithmetic processing unit 7, thereby lightening the hardware burden on the arithmetic processing unit 7 and reducing costs. In this arithmetic processing device 7, image processing such as recording using a built-in frame memory, gradation processing, spatial frequency processing, and inter-pixel calculation is performed in parallel in units of two pixels. The arithmetic processing device 7 is
It is controlled by a system controller 12 together with an X-ray generator 11 that applies high voltage to the X-ray tube 1 and the like. The output of the arithmetic processing device 7 is transferred to the scan conversion memory 8 in units of two pixels at a transmission rate of 10 MHz. The image data input to the scan conversion memory 8 is non-interlaced scanning at a rate of 3°75 frames per second, but even if it is displayed as is on the monitor television device 10, the frame rate will be low. Because of this, the human eye sees only a flickering image. Therefore, the scan conversion memory 8
The scanning method and frame rate are converted using . In this embodiment, scan conversion memory 8
The image data of non-interlaced scanning method is 3.75.
It is written at a rate of 1 frame/sec, and interlaced read scanning is performed at a rate of 30 frames/sec. The image data read from the scan conversion memory 8 is sent to the D/A converter 9 in units of 166 pixels. At this time, the data transmission rate is 10 MHz. D
The /A converter 9 performs serial-to-parallel conversion on the image data sent with 166 pixels, converts it into analog data at a speed of 160 MHz, obtains an analog video signal, and sends this to the monitor television device 10. Therefore, in this monitor television device 10, an extremely high-definition X-ray image having 2000 x 2000 pixels vertically and horizontally is displayed in real time at a frame rate of 30 frames/second using the interlaced scanning method.

【Effect of the invention】

According to the digital X-ray apparatus of the present invention, a high-definition X-ray image with extremely high spatial resolution can be displayed in real time in a way that is easy to see for the human eye without flickering. Furthermore, since the scanning speed in the scanning line direction of the television camera is slowed down to eliminate deterioration of the video signal, the spatial resolution of the image can be improved.

[Brief explanation of drawings]

The figure is a block diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Microfocus 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... xi generator, 12... System controller, 13...grid.

Claims (2)

[Claims] (1) An X-ray tube, a large-diameter image intensifier, a television camera with a large number of scanning lines that captures the output image of the image intensifier, and a video signal from the television camera. A/D that samples at multiple points for each scanning line and performs A/D conversion
A digital X-ray apparatus comprising: a converter; and a digital image processing device having a scan converter that stores digitized video signals and reads them out at a predetermined rate in an interlaced scanning manner. (2) An X-ray tube, a large-diameter image intensifier, and a television that captures the output image of the image intensifier and has a very large number of scanning lines and a slow scanning speed for each scanning line. 1. A digital X-ray apparatus comprising: a television camera; and an A/D converter that samples a video signal from the television camera at multiple points for each scanning line and converts the video signal from analog to digital.