title: Experimental validation of L-shell x-ray fluorescence computed tomography imaging: phantom study.
abstract: Thanks to the current advances in nanoscience, molecular biochemistry, and x-ray detector technology, x-ray fluorescence computed tomography (XFCT) has been considered for molecular imaging of probes containing high atomic number elements, such as gold nanoparticles. The commonly used XFCT imaging performed with K-shell x rays appears to have insufficient imaging sensitivity to detect the low gold concentrations observed in small animal studies. Low energy fluorescence L-shell x rays have exhibited higher signal-to-background ratio and appeared as a promising XFCT mode with greatly enhanced sensitivity. The aim of this work was to experimentally demonstrate the feasibility of L-shell XFCT imaging and to assess its achievable sensitivity. We built an experimental L-shell XFCT imaging system consisting of a miniature x-ray tube and two spectrometers, a silicon drift detector (SDD), and a CdTe detector placed at [Formula: see text] with respect to the excitation beam. We imaged a 28-mm-diameter water phantom with 4-mm-diameter Eppendorf tubes containing gold solutions with concentrations of 0.06 to 0.1% Au. While all Au vials were detectable in the SDD L-shell XFCT image, none of the vials were visible in the CdTe L-shell XFCT image. The detectability limit of the presented L-shell XFCT SDD imaging setup was 0.007% Au, a concentration observed in small animal studies.
authors.affiliation: Stanford University, Department of Radiation Oncology, 875 Blake Wilbur Dr, Stanford, California 94305, United States; University of Victoria, Department of Physics and Astronomy, Victoria, P.O. Box 1700 STN CSC, BC V8W 2Y2, Canada.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bazalova-Carter
authors.affiliation: Stanford University , Department of Radiation Oncology, 875 Blake Wilbur Dr, Stanford, California 94305, United States.
authors.forename: Moiz
authors.initials: M
authors.lastname: Ahmad
authors.affiliation: Stanford University, Department of Radiation Oncology, 875 Blake Wilbur Dr, Stanford, California 94305, United States; Stanford University, Department of Electrical Engineering, 350 Serra Mall, Stanford, California 94305, United States.
authors.forename: Lei
authors.initials: L
authors.lastname: Xing
authors.affiliation: Stanford University , Department of Radiology, 1201 Welch Rd, Stanford, California 94305, United States.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Fahrig
keywords: computed tomography, L-shell; gold contrast; molecular imaging; x-ray fluorescence
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