Working Principle Of The X-Ray Security Inspection Machine

When it comes to the working principle of the X-ray security inspection machine, we must first understand why the display of the security inspection machine console shows different colors. The penetrating ability of X-rays is related to material density, size and composition. The material with high density absorbs more X-rays and transmits less; when the density is small, it absorbs less and transmits more. Thicker objects are less likely to penetrate, and objects with higher effective atomic numbers are less likely to penetrate. X-rays penetrate different objects differently, so there are differences in the color of the image. The X-ray security inspection machine is based on the difference in the absorption characteristics of the object to X-rays, by detecting the effective atomic number of the object, and presenting the X-ray image of the object according to its own image processing function and color configuration scheme.

Therefore, we divide the X-ray security inspection machine images into three categories according to the material of the items: orange, green and blue. Among them, orange represents light elements with an effective atomic number less than 10 and their constituent organic substances, such as food, water, etc. Green generally represents medium-mass elements with effective atomic numbers 10-18, such as sodium, potassium, sulfur, phosphorus, etc. And blue represents heavy metals with an effective atomic number above 18, such as iron, zinc, nickel, etc. However, in practical applications, objects are generally in a mixed and superimposed state, and at the same time, the sizes are different, and the absorption characteristics of X-rays are quite different. In fact, the above rules are not strictly followed. Therefore, if the density or size is too large in the inspection of the X-ray security inspection machine, the X-ray image of the item penetrated by the X-ray will appear black or black and red.

X-ray security inspection machine is an imaging system that can generate digital radiation images. Its purpose is to convert detailed image information that cannot be seen by the naked eye into visible images, mainly including radiation sources, radiation detectors, data acquisition and transmission. equipment and image processing equipment. Its working principle is shown in the figure:

The inspected item enters the inspection channel, which will cover the package detection sensor (light barrier), and the detection signal is sent to the control unit to generate an X-ray trigger signal, which triggers the X-ray emission source to emit X-rays. The X-rays pass through the collimator to form a very thin The fan-shaped X-ray beam passes through the object to be inspected and reaches the detector. The detector converts the X-ray optical signal into an electrical signal, and then reproduces the outline, composition and material properties of the items in the package through image processing software. When the inspected item passes through the detection area, the ray generator will stop generating rays. Because X-rays are harmful to the human body, lead rubber protective curtains are installed on both sides of the security inspection machine passage to prevent the overflow of X-rays and cause radiation damage to security personnel or passengers.

When the item is inspected, a very thin fan-shaped X-ray beam will sweep through the inspected object layer by layer, which is equivalent to slicing the inspected object. The image acquisition system collects and stores the image information of each layer of scan lines. After the conveyor belt transports the inspected item through the detection area, the entire image information of the inspected item will be obtained, forming its complete X-ray image. The image generated can be displayed on the monitor or stored in the digital storage unit for later use .

When the X-ray security inspection machine is working, the security personnel need to judge the type of the inspected object by observing the color and outline of the object presented by the X-ray image. Therefore, in order to ensure high monitoring accuracy and inspection efficiency, X-ray security inspection machine operators need relevant knowledge background, especially long-term accumulated rich work experience.