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What is X-ray digital imaging DR technology

Date:2023-08-20 13:14:12 Browsing: time

What is X-ray digital imaging DR technology
X-ray digital imaging technology, also known as DR technology, digital X-ray imaging technology, etc. The following will introduce the basic concepts, advantages and disadvantages of X-ray digital imaging technology.
Definition of the resolution of image grayscale
(1) Image grayscale and contrast
Correspondingly to the concept of blackness in film photography, X-ray digital imaging technology introduces the concept of grayscale. The degree of black and white in an image is described by grayscale, and the range of changes in black and white in the image is defined as 256 grayscale levels. The grayscale difference between the brighter parts of the image on the monitor and the adjacent darker parts is called image contrast.
(2) Image Resolution and Image Unclearness
Image resolution refers to the minimum distance that recognizable lines on the display can be separated, in units of line pairs per millimeter (LP/mm). A pair of lines consists of a line and a spacing, and the width of the spacing is equal to the width of the line, expressed as the logarithm of lines within a width range of one millimeter.
Image unsharpness: In the process of X-ray digital imaging, an image with sharp edges becomes blurry due to certain factors, and the blurry range expands into a region. The width of this region is the image unsharpness, measured in millimeters.
Obviously, image resolution and image unsharpness are actually two expressions of the same problem, reflecting the clarity of image boundaries. They can be objectively tested using the same image test card on the display screen. According to the definition, the amount of image opacity is equal to half of the reciprocal of the logarithm of the image resolution line.
According to the definition of video technology, resolution can be divided into temporal resolution and spatial resolution. Time resolution is often used for resolving instrument time base linearity. The video resolution caused by differences in geometric position or material density is called spatial resolution. Because X-ray digital imaging technology does not involve the issue of temporal resolution, the resolution referred to in X-ray digital imaging technology is spatial resolution.
Imaging technical indicators
From the experimental results, when the penetration thickness of the steel weld is 10-20mm, in order to ensure that the sensitivity of the image quality indicator meets the requirements of the standard, the gray level in the effective evaluation area of the image should be controlled between 130-230, the contrast should be controlled between 60-120, and the image should not be clearer than 0.25mm. According to the current technical level, these three indicators can be achieved.
Image amplification in imaging technology
The difference between X-ray digital imaging technology and film photography technology is that the image obtained by real-time imaging is enlarged, while the film photography technology basically does not enlarge the negative image obtained under the same conditions. In real-time imaging:
(1) The inevitability of image enlargement
Due to the impossibility of the flaw detection workpiece closely adhering to the surface of the input screen of the image intensifier, it can be inferred from the principle of geometric projection that the resulting image must be enlarged, with a magnification of M=L/L1=(L1+L2)/L1=1+(L2/L1).
(2) The necessity of image enlargement
Due to the different carriers of real-time imaging method and film photography method, in order to improve image quality, especially to improve image clarity, it is necessary to enlarge the image because:
The image is actually unclear.

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