When a passenger put their bags through an X-raymachine, 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, tumor 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 through the hollow CT scanning machines. The X-rays bounce off the object inside the suitcases, measuring the density and mass of each 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 objects. If the density and mass of items in the suitcasse match items that are known to be dangerous, the objects are removed from the suitcase.