CT Baggage Scanners
When a passenger puts their bags through an X-ray machine, they go through a type of electromagnetic energy. Unlike visible light, humans cannot see X-rays. In hospitals, these X-ray energy beams can see through skin tissue to detect broken bones, tumors or other injuries. In an airport, X-ray technology is used in CT (computer tomography) scanners. Suitcases from passengers ride along a conveyor belt and pass through the hollow CT scanning machines. The X-rays bounce off the objects inside the suitcases, measuring the density and mass of each object. All that data is immediately entered into a computer. CT scanners are more complex than metal detectors and can analyze chemical components in addition to metallic object. If the density and mass of items in the suitcase match items that are known to be dangerous, the objects are removed from the suitcase.
High-tech Scanners
One limitation of CT scanning technology is that bags are scanned too slowly. This means only bags from suspicious passengers are scanned. Since this is not that effective, newer high-tech systems have been developed that are capable of detecting chemical components in individual items. The X-ray scanners most people see in airport are for screening carry on bags. But these scanners are too small to scan all the luggage that goes into the cargo section of the plane. In busy airports, large trucks with built in X-ray scanners (up to 5-7 meters long) are used. These trucks pull up beside containers that hold the suitcases, bags and other cargo. The entire container is scanned at once.