Principle, system and mode of traditional X-ray imaging

Principle: 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. By increasing the accelerating voltage, the energy carried by electrons increases, which may knock out the internal electrons of metal atoms.

So the inner layer forms a hole, and the outer layer electrons jump back to the inner layer to fill the hole, and at the same time emit photons with a wavelength of about 0. 1 nm. Because the energy released by the outer electron transition is quantized, the wavelength of the released photons is also concentrated in some parts, forming a characteristic line in the X spectrum, which is called characteristic radiation.

System and mode:

The strong radiation of 1. electrons. The metal is bombarded by high-energy electrons, and the electrons decelerate sharply in the process of hitting the metal. According to electromagnetism, charged particles with acceleration will radiate electromagnetic waves. If the electron energy is large, such as tens of thousands of electron volts, X-rays can be generated. This is the method of generating X-rays used in laboratories, factories, hospitals and other places.

2. Electron transition inside atoms can also produce X-rays. According to the theory of quantum mechanics, electrons will emit photons when they jump from high energy level to low energy level. If the energy difference between energy levels is relatively large, photons in the X-ray band can be emitted.

Extended data

Radiation classification:

Bremsstrahlung: When the high-speed electron current hits the anode target and is braked, the speed and direction of the electron change sharply under the strong electric field of the nucleus, and some kinetic energy is converted into photon energy and radiated, which is bremsstrahlung.

When the tube voltage of the X-ray tube is low, the electron energy blocked by the target does not exceed a certain limit, and only continuous spectral radiation is emitted.

Characteristic radiation: a discontinuity with only a few special linear spectra. This linear spectrum of radiation is called characteristic radiation, and the characteristic spectrum is related to the target material.

Baidu encyclopedia -X-ray