Suitcases from passenger ride along a conveyor belt and pass through the hollow computer tomopraphy 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. Computer tomography sacnners are more complex than metal detectors and can analyze chemical components in addition to metallic object. If the density and mass of items un the suitcase match items that are known to be dangerous, the objects are removed from the suitcase.