Q  How does X-ray baggage scanner work?

A  When the baggage enters the X-ray baggage scanner, it blocks the package detection sensor and sends the detection signal to the system control section to generate an X-ray trigger signal, emitting the X-ray from the source. As the X-ray beam penetrates every target object on the conveyor belt of X-ray baggage scanner, the radiation gets absorbed by the object, followed by the bombardment of the semiconductor detector mounted in the channel. The semiconductor detector converts the X-rays into signals, getting amplified, and transfers to the signal processing frame for more processing. These signals are finally processed and then displayed on the screen. Even if there are many layers in the baggage, X-rays can penetrate and show the contents of the baggage layer by layer.

A conveyor belt transfers each item towards X-ray baggage scanner. X-rays are electromagnetic waves with high energy, compared to light. Hence, they can penetrate through any material. The X-ray baggage scanner used in airports is usually based on a dual view X-ray system. This system has one X-ray source emitting X-rays in the range of 140 to 160kilovolt peak. KVP denotes the quantity of penetration an X-ray makes. The higher the KVP, the further will be the penetrating power of X-rays. After passing through the items under X-rays, the images are captured by a detector. This detector then transfers the X-rays onto a filter, which blocks the lower-energy X-rays. The resultant high-energy X-rays hit the second detector.

Q  What is the difference between single view X-ray baggage scanner and double view X-ray baggage scanner?

A  First of all, the size of the detection channel of single view and double view X-ray baggage scanners is the same, as well as the technical principle of detection. X-rays penetrate the scanned object and then display the shape and color of the object.

The first difference is that the core X-ray source is different. Single view X-ray baggage scanner has a ray power of 100KV, and double view X-ray baggage scanner is 160KV, which also represents the difference in penetration. The single view X-ray baggage scanner can only penetrate 20 to 30mm stainless steel plates, while the double view X-ray baggage scanner can penetrate stainless steel plates up to 30 to 40mm.

The second difference is based on the difference of the X-light source, the imaging angle and method are different. The single view X-ray baggage scanner is single-view imaging. Single-view X-ray imaging can only be imaged by different attenuation of rays, which cannot distinguish the difference in density. Therefore, the displayed image color is not so rich and obvious. The double view X-ray baggage scanner is dual-energy imaging. The pictures displayed are richer in color with a stronger sense of layering. The distinction between organics, in-organics, and mixtures is clearer. The spectrum produced by dual-energy X-rays has two bands with two central values respectively. In a single view, there is only one band and one center value.