Multi-energy techniques for radiographic monitoring of chemical   composition
  A theoretical model of multi-energy radiography (MER) are proposed. It is shown that, as distinct from the conventional radiography, MER allows identification of organic substances and control of their chemical composition. Broad prospects are noted for MER application, specifically, for detection of prohibited substances (explosives, drugs, etc.) during customs and anti-terrorist safety inspection. 
S.V. Naydenov, V.D. Ryzhikov