JPH03114443A - Digital x-ray television apparatus - Google Patents

Abstract

PURPOSE:To form an image suitable for diagnosis from the taken image due to an I.I.-TV camera system by removing shading or inherent noise therefrom by mounting an image data processing means performing division between image data taken in an object present state and image data taken in an object absent state or performing subtraction therebetween after the logarithmic conversion of the data. CONSTITUTION:A switch 23 is connected on an A-side and photographing is performed to store image data in the first image memory 24. The switch 23 is connected on a B-side and an examinee 4 is placed on a bed 5 to again perform photographing and image data is stored in the second image memory 25. The image data are converted to video signals by a A/D converter 21 to be subjected to logarithmic conversion by a logrithmic converter 22 and the subtraction between the first and second image memories 24, 25 is performed using an operator 26. The image data after operation is removed from shading or inherent noise. The image data is sent to a D/A converter 29 to be converted to a video signal which is, in turn, displayed on a display apparatus 12 as an image from which shading or inherent noise is removed.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a digital This invention relates to line television equipment.

[Conventional technology]

In digital X-ray television equipment, 1. I.

- TV camera system shading (a phenomenon in which the periphery of the image becomes darker than the center) and mainly 1.1. Image quality deteriorates due to noise (appears as roughness on the screen; this is called inherent noise) caused by non-uniformity on the input surface.

The problem of image quality deterioration is that conventionally, most of this type of digital X-ray television equipment is DSA (dfdigital).
It was used as a 5ubtraction angiography device, and it did not appear on the surface because the subtracted images of two images, such as before and after contrast agent injection, were used for diagnosis. This is because the above-mentioned shading and inherent noise are background, and can be eliminated by subtraction.

Also, 1.1. -Spot camera and 1.1. - For cine cameras, 1.1. shading and inherent noise. However, in this case, the image was not processed as an electrical signal, and the film used had a low contrast resolution, so this did not pose a major problem.

[Problem to be solved by the invention]

However, with conventional devices, when processing images by converting them into electrical signals, and when diagnosing a single photographed image as it is, rather than diagnosing a subtracted image, the shading and There was a problem in that the inherent noise appeared as it was and interfered with diagnosis.

The objects of the present invention are 1.1. - It is an object of the present invention to provide a digital X-ray television device that can remove shading and inherent noise from an image taken by a TV camera system and make the image suitable for one diagnosis.

[Means to solve the problem]

The above purpose is to provide a converter that converts an X-ray image obtained by X-ray irradiation into a visible light image, a television camera that converts the visible light image obtained by this converter into a video signal, and a video signal from this television camera. A converting a signal into a digital signal
In a digital X-ray television device comprising an A/D converter and an image processing device that processes a digital image signal from the A/D converter, the image processing device captures an image with a subject present. This is achieved by providing an image data processing means that performs division between data and image data photographed without a subject, or subtraction after logarithmic transformation.

[Effect]

The shading and inherent noise are multiplicative. Therefore, if you take images with and without the subject and then divide them.

The image data contains only the subject, and the shading and inherent noise mentioned above are removed.

Now, let the attenuation coefficient distribution of the object be ρ(x, y), the X-ray intensity distribution without the object be I(x, y), and the image data with the object be f (x+ y), and the object If the image data in the case of none is g (x + y), then f (x + y) = k (xyy) · exp (x, y) exp (
−p (x, y)) −(1) g(x, y)=k(x,
y) 4(x, y) −(2) where k(x, y
) is a conversion coefficient for each location on the image.

If we transform equations (1) and (2) above, -p(x, y)
=In(f(x,y))-In(g(x,y))...(
3) holds true.

From this equation (3), shading and 1.1.
It can be seen that the same noise on the right is removed.

The image data processing means is as described above.

Division is performed between image data photographed with a subject and image data photographed without a subject, or subtraction is performed after logarithmic transformation. As a result, 1. I.

Shading and inherent noise are removed from images captured by a TV camera system, making them suitable for diagnosis in the same way as screen/film images.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a digital X-ray television apparatus according to the present invention, in which 1 is a high voltage generator, 2 is an
The ray tube 3 is an X-ray aperture device, which is used to collimate the X-rays emitted from the X-ray tube 2 into a predetermined irradiation field. 4 is a subject, and 5 is a bed on which the subject 4 is placed. 6 is 1.1. This converts the Xi image into an optical image. 7 is an optical system consisting of an optical lens, a reflecting mirror, etc., and 8 is a television camera (TV camera), which converts the optical image into a video signal. 9 is a television camera controller that controls the television camera 8.

Reference numeral 10 denotes an image processing device, which is used for shading, inherent noise removal, and the like.

Reference numeral 11 denotes a system controller including a computer, which controls the high voltage generator 1, the television camera controller 9, and the image processing device 10.

As shown in the figure. In FIG. 2, 21 is an analog/digital converter (hereinafter referred to as an A/D converter),
It is used to convert video signals into digital signals. 22 is a logarithmic converter, which is used to obtain the logarithm of the linearly digitized value from the A/D converter 21. This is usually implemented using a lookup table.

24 and 25 are the first. A second image memory stores output data from the logarithmic converter 22 via a switch 23. 26 is an arithmetic unit (ALU) which together with the logarithmic converter 22 constitutes the main component of the image data processing means.

1st. The second image memories 24 and 25 are used as inputs, and throughput (outputting the input as is), subtraction, etc. on each side of the image memories 24 and 25 is performed. Reference numeral 27 denotes an exponential converter, which performs exponential conversion to return logarithmically converted data to its original state. 2
Reference numeral 8 denotes a switch for selecting whether or not to perform index conversion using the index converter 27, and whether or not to perform index conversion is selected based on differences in subsequent image data processing.

29 is a digital/analog converter (hereinafter referred to as a D/A converter), which converts digital data into a video signal and sends it to the display device 12.

Next, the operation of the above-mentioned device of the present invention will be explained.

First, photography is performed without the subject 4. At this time, the switch 23 is connected to the A side, and the first image memory 24
Store image data to. next.

The subject 4 is placed on the bed 5 and photographed again. At this time, connect the switch 23 to the B side.

Image data is stored in the second image memory 25. here,
The image data is obtained by converting a video signal from the television camera 8 to the television camera controller 9 by an A/D converter 21 and then logarithmically converting it by a logarithmic converter 22. After that, the first. Calculator 2 performs subtraction between the second image memory 24 and 25.
6.

The image data after this calculation is logarithmically transformed →
It has undergone subtraction, and shading and inherent noise have been removed. The image data after this calculation is transferred to the switch 28 due to differences in processing of the image data.
It is selected whether to perform index conversion and return to the original state (C side connection or D side connection) and sends it to the D/A converter 29. D
The image data sent to the /A converter 29 is converted into a video signal and displayed as an image on the display device 12. The displayed image has had shading and inherent noise removed.

In the above-mentioned embodiment, an image without the subject 4 is taken immediately before each time, but the image data without the subject 4 is, for example, 1.1. It is also possible to save the data for each size in advance and use it when the calculation unit 26 performs calculations after photographing the subject 4.

Further, in the above embodiment, the image data processing means is configured to perform logarithmic conversion of the image data and subtraction between the image data taken with a subject and the image data taken without a subject. As mentioned above, it is also possible to configure the division between the two image data.

〔Effect of the invention〕

According to the invention, 1.1. - Similar to film/screen images, TV camera photography has the effect of providing images suitable for diagnosis without shading or inherent noise. Image data without shading or inherent noise has the effect that contrast enhancement can be easily performed compared to film/screen images, and low contrast areas can be easily recognized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, and FIG.
FIG. 1 is a block diagram showing a specific example of the configuration of the image processing apparatus shown in FIG. 1...High voltage generator, 2...X-ray tube, 3...X
Line aperture device, 4...Subject, 5...Bed, 6...
・1.1. ．． 7...Optical system, 8...TV camera,
9... Television camera controller, 10... Image processing device, 11... System controller, 12...
Display device, 21... A/D converter, 22... Logarithmic converter, 23... Switch, 24... First image memory, 25... Second image memory, 26... Calculation vessel, 27
...Exponent converter, 28...Switch, 29...D
/A converter. Potato convict Kayame

Claims (1)

[Claims] 1. A converter that converts an X-ray image obtained by X-ray irradiation into a visible light image, a television camera that converts the visible light image obtained by this converter into a video signal, and a video signal from this television camera. In a digital X-ray television apparatus comprising an A/D converter that converts into a digital signal and an image processing device that processes the digital image signal from the A/D converter, the image processing device A digital X-ray television apparatus comprising image data processing means for dividing or subtracting after logarithmic conversion between image data photographed in a certain state and image data photographed in a state without a subject.