X-ray detector is a kind of instrument that uses the difference of the local structure of the object to change the attenuation of the object to the ray, and then detect the intensity of the ray, and judge the internal defects and material distribution of the object. X - ray detector, widely used in industry to judge whether the workpiece is qualified.

X-ray machines and linear accelerators are commonly used as ray sources, collectively known as electron radiation generators. The peak ray energy and intensity of X-ray machine can be adjusted, and the peak ray energy range of practical application is from several thousand volts to 450 thousand volts. The peak ray energy of linear accelerators is generally not adjustable. In practice, the peak ray energy ranges from 1 to 16MEV. Although higher energies can be achieved, it is mainly used for experiments.

The common advantage of the electronic radiation generator is that it will not produce radiation after cutting off the power supply, which is very beneficial for the use of industrial sites. The focal size of the electron radiation generator is a few microns to a few millimeters. In the process of converting a high-energy electron beam into X-rays, only a small amount of energy is converted into X-rays, and most of the energy is converted into heat. The smaller the focal size, the higher the local power density and the higher the local temperature on the anode target. The actual applied power is determined by the power density at which the anode target can work for a long time.

As a result, the power or maximum voltage of a small or even microfocal ray source is lower than that of a large focal ray source. The common disadvantage of electron radiation generators is the polychromatism of the X-ray spectrum. Such continuous spectrum of X-rays will lead to hardening of the energy spectrum during the decay process, leading to various artifacts related to hardening.

The biggest advantage of isotope radiation source is simple energy spectrum, less power consumption, small equipment size, relatively simple, stable output characteristics. However, the disadvantage is the low intensity of the radiation source. To increase the strength of the source, the volume of the source must be increased, thereby increasing the size of the focal point. The practical application in industrial CT is less.

Synchrotron radiation is originally a continuous spectrum of almost unienergetic high-intensity X-rays that can be acquired with a monochromator, so it can be fabricated into a CT system with high spatial resolution. However, with ray energies ranging from 20KEV to 30KEV, it can actually only be used to detect small samples of about 1 mm on some special occasions.