Evaluation of Some Parameterization Models for Photon Cross Sections in Quantitative Dual‐Energy <scp>CT</scp>

ABSTRACT Using multienergy CT with energy‐dispersive detectors and dual‐energy CT (DECT), traditional CT images can be combined to extract material parameters such as electron density ( ρ e ) and effective atomic number ( Z eff ). This study evaluates parameterizations for deriving ρ e and Z eff from CT numbers (HU) to generate new CT images. Four parameterization models were analyzed: Electron Cross Section Parameterization (ECSP), Power Law Parameterization (PLP), Taylor Expansion Parameterization (TEP), and Basis Material Parameterization (BMP). Initially, the accuracy of these models in representing the linear attenuation of tissue‐equivalent materials was tested. After this initial analysis, this work focused on parameterizations that need only two energies to extract ρ e and Z eff of materials. Then, the energy dependence of the extracted parameters based on the theoretical linear attenuation coefficient of several tissue‐equivalent materials was assessed using photon energy combinations from 20 to 200 keV. Additionally, the dual‐energy models were used to generate ρ e and Z eff images based on HU images simulated with ImaSim software. Finally, a basis transformation technique was applied to the parameter CT images to enhance contrast by suppressing specific materials. Results show that most parameterizations accurately represent the attenuation properties of biological and dosimetric materials, with differences below 5% for photon energies above 20 keV, except for lower‐order TEP. Energy dependence analysis confirmed all dual‐energy parameterizations as robust to extract ρ e and Z eff , with variations under 5%. The generated ρ e and Z eff images provided valuable new material contrast, and the suppression technique further enhanced image differentiation, offering potential improvements for medical diagnostics.