Nowadays, X-ray security inspection machines at home and abroad can be divided into single-energy security inspection machines and dual-energy security inspection systems according to the types of radiation sources and detectors. The so-called single-energy system means that the x-ray emitted by the ray source has a single energy, and the single-energy ray source emits a fan-shaped single-energy ray. The penetrating object reaches the detector and is absorbed by the detector, and is converted into a digital signal and input into the PC through a series of The data processing is finally displayed on the computer screen of the security inspection machine in the form of a grayscale image, and the security inspector judges whether there is a dangerous product by the shape and contour of the image. Since the single-energy security inspection ray system does not have the ability to distinguish between substances, it is only through the shape to judge that the dangerous goods have high requirements for the security inspector's experience. The dual-energy security inspection system can be divided into a true dual-energy system and a pseudo-two-energy system according to the number of radiation sources used. The so-called true dual-energy system means that the security inspection machine has two single-energy ray sources, respectively emitting high-energy ray and low-energy ray, and at the receiving end, there are two sets of detectors, respectively receiving the attenuated high-energy ray and low-energy ray.
There is also a pseudo dual energy system. It means that the security inspection machine only has one ray source, which is a pluripotent ray source with a certain spectral width. The X-ray passes through the object to reach the detector, and is first received by the low-energy detector to obtain low-energy data, and then passes through a copper. A low-energy filter filters out the low-energy portion, and the remaining high-energy portion is received by the next-level high-energy detector to obtain high-energy data.
The dual-energy system inputs the high-low energy signals into the PC, and after a series of data processing and attribute calculations related to the material equivalent atomic number, finally presents a pseudo-color image with certain substance categories on the computer screen, which greatly reduces the security check. The judgment of the staff is difficult. The dual-energy security inspection system is more accurate and has the ability to classify substances than the single-energy security inspection system. It is a commonly used security inspection system.