title: A new method to measure electron density and effective atomic number using dual-energy CT images.
abstract: The purpose of this work is to present a new method to extract the electron density ([Formula: see text]) and the effective atomic number (Z eff) from dual-energy CT images, based on a Karhunen-Loeve expansion (KLE) of the atomic cross section per electron. This method was used to calibrate a Siemens Definition CT using the CIRS phantom. The predicted electron density and effective atomic number using 80 kVp and 140 kVp were compared with a calibration phantom and an independent set of samples. The mean absolute deviations between the theoretical and calculated values for all the samples were 1.7 %  ±  0.1 % for [Formula: see text] and 4.1 %  ±  0.3 % for Z eff. Finally, these results were compared with other stoichiometric method. The application of the KLE to represent the atomic cross section per electron is a promising method for calculating [Formula: see text] and Z eff using dual-energy CT images.
authors.affiliation: Department of Oncology, Clínica Universidad de Navarra, University of Navarra, Av Pio XII s/n, Pamplona, Navarre, Spain.
authors.forename: Luis Isaac Ramos
authors.initials: LI
authors.lastname: Garcia
authors.forename: José Fernando Pérez
authors.initials: JF
authors.lastname: Azorin
authors.forename: Julio F
authors.initials: JF
authors.lastname: Almansa
mesh_terms: D002138:Calibration; D004583:Electrons; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards