How Do X-Ray Security Screening Systems Work? Can the Radiation from the X-Ray Screening System Cause Harm?

X-ray security screening systems scan the contents of handbags, luggage, large parcels or cargo with low-dose radiation. Lead is a material that prevents the penetration of radiation. Thus, the area surrounding the tunnel section of an x-ray screening system is covered with a lead shield to contain all x-ray beams inside the system and prevent any beams from exiting the system. Lead-impregnated curtains at the entrance and exit of the tunnel ensure that the levels of x-ray radiation at the entrance and exit of x-ray screening systems remain below those set by international institutions.  For example, with XRC systems, while x-rays are present in the tunnel, the leakage radiation value measured on the body of the device is less than 1µSv/h. For comparison, x-rays used in medical applications for taking a chest x-ray, for example, have a value of 300µSv/h.
 

X-Ray screening systems consist of an x-ray generator, which is the X-ray source that emits the beam, and a series of imaging detectors that receive that beam. Imaging detectors are also called photodiode cards. The objects to be scanned move between the X-ray source and the imaging detectors through the conveyor unit. The X-rays pass through the package and reach the photodiode cards. Due to their different atomic weights, organic, inorganic and mixed materials are displayed in different colors on the screen. XRC’s advanced image processing algorithms and technology allow for detailed investigation using different post-processing modes, such as perfect View, Edge Enhancement, Organic Materials, Inorganic Materials, Pseudo Color, Black & White, High Penetration, and Inverse Colors, all of which are easily selected using keys on the XRC keyboard.

 

The computer monitor of an x-ray screening system typically displays different kinds of objects in different colors and shades.  Images with a thickness exceeding certain set penetration values are shown in black; heavy elements such as iron, tin, metal and gold in an inorganic object are shown in blue.  Light elements such as organic solid or liquid explosives, plastics, textiles, food, paper, carbon, hydrogen are shown in orange. In general, explosives belong to the group of organic substances because they have a plastic material structure. Substances with mixed internal structures; e.g., objects such as glass, salt, leather, and aluminum which are neither organic nor inorganic are shown in green. These color distinctions enable the operator to distinguish the contents of inspected packages and identify any potentially dangerous elements quickly and easily.