Effective atomic number estimation by energy-resolved X-ray computed tomography with a current-mode detector system

Abstract

Abstract We have developed a current-mode detector system, called a “transXend” detector, consisting of several segmented detectors aligned along the direction of X-ray incidence, for energy-resolved computed tomography (CT). The transXend detector measures X-rays as electric currents and after analysis gives the energy spectrum of the incident X-ray. In previous work, we measured the linear attenuation coefficients of resins as a function of X-ray energy with the energy-resolved CT using the transXend detector. This paper shows a method to estimate the effective atomic number <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> </mml:msub> </mml:math> and electron density <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>ρ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> </mml:msub> </mml:math> of nine resins from the linear attenuation coefficients using a photon–atom cross-section lookup table. The estimated <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>ρ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> </mml:msub> </mml:math> agreed well with calibration lines with accuracies of about 2%.