The difference between x-ray and CT

First of all, the principle is different

CT uses X-ray beam to scan a certain thickness layer of human body. X-rays passing through this layer are received by the detector, converted into visible light, converted into electrical signals by photoelectric conversion, converted into digital by analog-digital converter, and input into a computer for processing.

The simplest way to generate X-rays is to hit a metal target with accelerated electrons. During the impact, the electrons suddenly decelerate, and their lost kinetic energy (1%) will be released in the form of photons, forming a continuous part of the X-ray spectrum, which is called braking radiation.

Second, the image quality is different.

CT images are made up of a certain number of pixels with different gray levels from black to white arranged in a matrix. These pixels reflect the X-ray absorption coefficient of the corresponding voxel. Different CT devices have different pixel sizes and numbers.

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X-ray photography is an intuitive physical quantity, which continuously displays images with another physical characteristic. It mainly uses the characteristics of X-ray penetration, which is characterized by convenient continuous and intuitive acquisition, strong versatility and real-time dynamic acquisition of the first image. However, the repeatability of the analog image is poor, and once the imaging cannot be changed or post-processed, the dynamic range of gray level connection is small.

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Third, the inspection focus is different.

X-rays are especially suitable for bone trauma. If bone injury is suspected, X-ray examination is the first choice.

Need multi-angle shooting, further examination, such as bone marrow examination, whether there is early cancer in the chest, all need CT.

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