Multi-Energy Radiography Against Terrorism. Theory and Experiments
  Multi-energy radiography is a new direction in non-destructive testing. Its specific feature is separate detection of penetrating radiation in several energy channels. Multi-energy radiography allows quantitative determination of the atomic composition of objects. This is its principal advantage over conventional radiography. In particular, dual-energy radiography allows determination of the effective atomic number of a material with an accuracy of up to 80-90%. Development of three-energy radiography and radiography of higher multiplicity makes it possible to further improve the reconstruction of an objects chemical composition. This presents the possibility, for example, of detection of explosives and other illegal objects in luggage with a reliability approaching 100%. These developments can find application not only in anti-terrorist activities, but also in areas such as industrial testing and nuclear medicine. 
Sergei V. Naydenov, Vladimir D. Ryzhikov, Craig F. Smith, Dennis Wood