Abstract
X-ray fluorescence computed tomography (XFCT) is a high sensitivity imaging modality for high-atomic elements such as gadolinium (Gd) or gold (Au). In order to improve the contrast of x-ray fluorescent (XRF) signal in the raw projection data, common XFCT systems use the single-pixel x-ray spectrometer to record XRF photons stimulated by the pencil-beam x-ray source and achieve line-by-line scan of the whole object by translating the x-ray source or the object. However, this kind of design results in waiting time of translation device. One improvement would be to replace the traditional x-ray tube with the spatially distributed multi-beam x-ray source and scan the whole object by switching the exposure of each focus. In this study, we present a design of XFCT system using the spatially distributed multi-beam source and a XFCT imaging experiment was performed to investigate its feasibility. Each cold cathode of the x-ray source used in this study was made of carbon nanotubes and each focus was independently controlled by the electronic control system. The incident beam was collimated by a pinhole array to produce pencil-beam source. The object scanned by the system was a PMMA cylinder (8cm in diameter) with Gd (20mg/mL) and I (100mg/mL) insertions. Results show that the distribution of I and Gd in a PMMA phantom was successfully reconstructed but the imaging performance was limited by the collimation and exposure mode of current distributed x-ray source. The practicality of current distributed x-ray source used for XFCT scan and further optimization of the proposed system are discussed according to the experimental results.
Highlights
X-ray fluorescence computed tomography (XFCT), which detects the characteristic x-rays emitted from the target element, is a high-sensitivity imaging modality for high-atomic elements such as gadolinium (Gd) or gold (Au)
Synchrotron beam is the ideal source for XFCT, researchers focus more on the XFCT system based on conventional x-ray tubes in recent years [12,13,14,15]
In order to improve the contrast of x-ray fluorescence (XRF) signals in the raw projection data, common XFCT systems use single-pixel x-ray spectrometers to record XRF photons stimulated by the pencil-beam x-ray source and achieve line-by-line scan of the whole object by translating the incident beam or the rotation stage [16,17,18,19]
Summary
X-ray fluorescence computed tomography (XFCT), which detects the characteristic x-rays emitted from the target element, is a high-sensitivity imaging modality for high-atomic elements such as gadolinium (Gd) or gold (Au). Studies of XFCT experiments often use synchrotron beams to stimulate x-ray fluorescence (XRF) photons [8]. XFCT Using Spatially Distributed Source polarized so that the energy of incident photons can be adjusted to maximize the fluorescence field, and the Compton scattered background can be effectively reduced by optimizing the detection angle [9,10,11]. The research and application of XFCT based on synchrotron is limited by its requirement of space and cost. Synchrotron beam is the ideal source for XFCT, researchers focus more on the XFCT system based on conventional x-ray tubes in recent years [12,13,14,15]
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