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Photon-counting detector technology has enabled the first experimental investigations of energy-resolved computed tomography (CT) imaging and the potential use for K-edge imaging. However, limitations in regards to detecter technology have been imposing a limit to effective count rates. As a consequence, this has resulted in high noise levels in the obtained images given scan time limitations in CT imaging applications. It has been well recognized in the area of low-dose imaging with conventional CT that iterative image reconstruction provides a superior signal to noise ratio compared to traditional filtered backprojection techniques. Furthermore, iterative reconstruction methods also allow for incorporation of a roughness penalty function in order to make a trade-off between noise and spatial resolution in the reconstructed images. In this work, we investigate statistically-principled iterative image reconstruction from material-decomposed sinograms in spectral CT. The proposed reconstruction algorithm seeks to minimize a penalized likelihood-based cost functional, where the parameters of the likelihood function are estimated by computing the Fisher information matrix associated with the material decomposition step. The performance of the proposed reconstruction method is quantitatively investigated by use of computer-simulated and experimental phantom data. The potential for improved K-edge imaging is also demonstrated in an animal experiment.
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http://dx.doi.org/10.1109/TMI.2013.2250991 | DOI Listing |
ACS Appl Mater Interfaces
December 2024
Department of Chemistry, University of Victoria, PO Box 1700 Stn CSC, Victoria, BC V8W 2Y2, Canada.
Gold nanoparticles (GNPs) encapsulated in amphiphilic block copolymers are a promising system for numerous biomedical applications, although critical information on the effects of various preparation variables on the structure and properties of this unique type of nanomaterial is currently missing from the literature. In this research, we synthesized GNPs functionalized with thiol-terminated polycaprolactone (PCL-GNPs) before encapsulating them into poly(ε-caprolactone)--poly(ethylene glycol) (PCL--PEG) micellar nanoparticles via nanoprecipitation to yield GNP-loaded polymeric nanoparticles (GNP-PNPs). We explored the role of different manufacturing variables (water volume, PCL--PEG to PCL-GNP ratio, and PEG block length) on the sizes, morphologies, GNP occupancies, colloidal gold concentrations, and time stability of GNP-PNPs.
View Article and Find Full Text PDFBr J Radiol
December 2024
Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Multienergy cardiovascular computed tomography (CT) imaging can be defined as data acquisition at two (dual-energy) or multiple x-ray energies. Multienergy cardiovascular CT imaging provides additional qualitative and quantitative information such as material maps or virtual monoenergetic images, which are supposed to further improve the quality and diagnostic yield of CT. Recently introduced photon-counting detector CT scanners further address some of the challenges and limitations of previous, conventional CT machines, hereby enhancing and extending the applications of CT for cardiovascular imaging.
View Article and Find Full Text PDFACS Nano
December 2024
Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Preclinical and clinical diagnostics depend greatly on medical imaging, which enables the identification of physiological and pathological processes in living subjects. It is often necessary to use contrast agents to complement anatomical data with functional information or to describe the disease phenotypically. Nanomaterials are used as contrast agents in many advanced bioimaging techniques and applications because of their high payload, physicochemical properties, improved sensitivity, and multimodality.
View Article and Find Full Text PDFAdv Funct Mater
October 2024
Department of Radiology, Michigan State University, East Lansing, MI 48824, USA.
3D printed biomaterial implants are revolutionizing personalized medicine for tissue repair, especially in orthopedics. In this study, a radiopaque bismuth oxide (BiO) doped polycaprolactone (PCL) composite is developed and implemented to enable the use of diagnostic X-ray technologies, especially spectral photon counting X-ray computed tomography (SPCCT), for comprehensive tissue engineering scaffold (TES) monitoring. PCL filament with homogeneous BiO nanoparticle (NP) dispersion (0.
View Article and Find Full Text PDFJ Med Phys
September 2024
Department of Surgery, School of Medicine, Iwate Medical University, Iwate, Japan.
Introduction: To perform energy-dispersive X-ray imaging, we constructed a photon-counting X-ray computed tomography (CT) scanner to perform enhanced K-edge CT.
Methods: X-ray photons penetrating through an object were detected using a cadmium telluride flat panel detector (FPD) with pixel dimensions of 100 × 100 mm, and 720 radiograms from the FPD were sent to the personal computer to reconstruct tomograms. Gadolinium (Gd) K-edge energy is 50.
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