Concept of effective atomic number and effective mass density in dual-energy X-Ray computed tomography

Anne Bonnin (1, 2) , Philippe Duvauchelle (1) , Valerie Kaftandjian (1) , Pascal Ponard (3)

1 LVA - Laboratoire Vibrations Acoustique
2 ESRF - European Synchrotron Radiation Facility
3 Thales Research and Technology [Palaiseau]

This paper focuses on dual-energy X-ray computed tomography and especially the decomposition of the measured attenuation coefficient in a mass density and atomic number basis. In particular, the concept of effective atomic number is discussed. Although the atomic number is well defined for chemical elements, the definition of an effective atomic number for any compound is not an easy task. After reviewing different definitions available in literature, a definition related to the method of measurement and X-ray energy, is suggested. A new concept of effective mass density is then introduced in order to characterize material from dual-energy computed tomography. Finally, this new concept and definition are applied on a simulated case, focusing on explosives identification in luggage.

Mots clés: Effective atomic number; Effective mass density; Dual-energy; X-ray computed tomography; Explosives identification

Domaines: Sciences de l'ingénieur [physics]

Anne Bonnin, Philippe Duvauchelle, Valerie Kaftandjian, Pascal Ponard. Concept of effective atomic number and effective mass density in dual-energy X-Ray computed tomography. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014, 318, pp.223-231. ⟨10.1016/j.nimb.2013.09.012⟩. ⟨hal-01017367⟩