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TH‐AB‐209‐01: Making Benchtop X‐Ray Fluorescence Computed Tomography (XFCT) Practical for in Vivo Imaging by Integration of a Dedicated High‐Performance X‐Ray Source in Conjunction with Micro‐CT Functionality
Author(s) -
Manohar N,
Reynoso F,
Cho S
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4958092
Subject(s) - imaging phantom , materials science , cadmium zinc telluride , x ray fluorescence , collimator , x ray tube , medical physics , detector , optics , medical imaging , biomedical engineering , physics , fluorescence , radiology , medicine , electrode , anode , quantum mechanics
Purpose: To make benchtop x‐ray fluorescence computed tomography (XFCT) practical for routine preclinical imaging tasks with gold nanoparticles (GNPs) by deploying, integrating, and characterizing a dedicated high‐performance x‐ray source and addition of simultaneous micro‐CT functionality. Methods: Considerable research effort is currently under way to develop a polychromatic benchtop cone‐beam XFCT system capable of imaging GNPs by stimulation and detection of gold K‐shell x‐ray fluorescence (XRF) photons. Recently, an ad hoc high‐power x‐ray source was incorporated and used to image the biodistribution of GNPs within a mouse, postmortem. In the current work, a dedicated x‐ray source system featuring a liquid‐cooled tungsten‐target x‐ray tube (max 160 kVp, ∼3 kW power) was deployed. The source was operated at 125 kVp, 24 mA. The tube's compact dimensions allowed greater flexibility for optimizing both the irradiation and detection geometries. Incident x‐rays were shaped by a conical collimator and filtered by 2 mm of tin. A compact “OEM” cadmium‐telluride x‐ray detector was implemented for detecting XRF/scatter spectra. Additionally, a flat panel detector was installed to allow simultaneous transmission CT imaging. The performance of the system was characterized by determining the detection limit (10‐second acquisition time) for inserts filled with water/GNPs at various concentrations (0 and 0.010–1.0 wt%) and embedded in a small‐animal‐sized phantom. The phantom was loaded with 0.5, 0.3, and 0.1 wt% inserts and imaged using XFCT and simultaneous micro‐CT. Results: An unprecedented detection limit of 0.030 wt% was experimentally demonstrated, with a 33% reduction in acquisition time. The reconstructed XFCT image accurately localized the imaging inserts. Micro‐CT imaging did not provide enough contrast to distinguish imaging inserts from the phantom under the current conditions. Conclusion: The system is immediately capable of in vivo preclinical XFCT imaging with GNPs. Micro‐CT imaging will require optimization of irradiation parameters to improve contrast. Supported by NIH/NCI grant R01CA155446; This investigation was supported by NIH/NCI grant R01CA155446