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Spectral CT

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https://www.readbyqxmd.com/read/28099156/quasi-monochromatic-imaging-in-x-ray-ct-via-spectral-deconvolution-using-photon-counting-detectors
#1
Sen Wang, Li Zhang, Dufan Wu, Xiaofei Xu
Photon counting detectors can obtain the spectral information of incident x-ray spectrum while the detected counts may differ from the incident counts due to detector response. If uncorrected or uncompensated, the response will lead to distortion in CT reconstruction. With the intention of reducing the distortion and exploring the potential of photon counting detectors, a novel reconstruction strategy with spectral deconvolution is proposed in this paper which attempts to set itself apart from traditional material decomposition framework...
January 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28097460/synthesis-spectral-characterization-dna-protein-binding-dna-cleavage-cytotoxicity-antioxidative-and-molecular-docking-studies-of-cu-ii-complexes-containing-schiff-base-bpy-phen-ligands
#2
Berelli Anupama, Airva Aruna, Vijjulatha Manga, Sreekanth Sivan, Madamsetty Vijay Sagar, Ravula Chandrashekar
Ternary Cu(II) complexes [Cu(II)(L)(bpy)Cl] 1, [Cu(II)(L)(Phen)Cl] 2 [L = 2,3-dimethyl-1-phenyl-4(2 hydroxy-5-methyl benzylideneamino)-pyrazol-5-one, bpy = 2,2(') bipyridine, phen =1,10 phenanthroline) were synthesized and characterized by elemental analyses, UV-Visible, FT-IR, ESR, Mass, thermogravimetric and SEM EDAX techniques. The complexes exhibit octahedral geometry. The interaction of the Cu(II) with cailf thymus DNA (CT-DNA) was explored by using absorption and fluorescence spectroscopic methods...
January 17, 2017: Journal of Fluorescence
https://www.readbyqxmd.com/read/28096049/monoenergetic-reconstructions-for-imaging-of-coronary-artery-stents-using-spectral-detector-ct-in-vitro-experience-and-comparison-to-conventional-images
#3
Tilman Hickethier, Bettina Baeßler, Jan Robert Kroeger, Jonas Doerner, Gregor Pahn, David Maintz, Guido Michels, Alexander C Bunck
PURPOSE: Accurate assessment of coronary stents using non-invasive CT imaging remains challenging despite new stent materials and improvements in CT technology. Virtual monoenergetic (monoE) images reconstructed from dual energy CT acquisitions potentially decrease artifacts caused by coronary stents. A novel spectral detector technology provides monoE and conventional images simultaneously for all conducted scans. The purpose of our study was to systematically investigate the influence of different monoE reconstructions on the visualization of coronary stent lumen in comparison to conventional images...
January 3, 2017: Journal of Cardiovascular Computed Tomography
https://www.readbyqxmd.com/read/28093625/ultralow-dose-ct-for-pulmonary-nodule-detection-with-chest-x-ray-equivalent-dose-a-prospective-intra-individual-comparative-study
#4
Michael Messerli, Thomas Kluckert, Meinhard Knitel, Stephan Wälti, Lotus Desbiolles, Fabian Rengier, René Warschkow, Ralf W Bauer, Hatem Alkadhi, Sebastian Leschka, Simon Wildermuth
PURPOSE: To prospectively evaluate the accuracy of ultralow radiation dose CT of the chest with tin filtration at 100 kV for pulmonary nodule detection. MATERIALS AND METHODS: 202 consecutive patients undergoing clinically indicated chest CT (standard dose, 1.8 ± 0.7 mSv) were prospectively included and additionally scanned with an ultralow dose protocol (0.13 ± 0.01 mSv). Standard dose CT was read in consensus by two board-certified radiologists to determine the presence of lung nodules and served as standard of reference (SOR)...
January 16, 2017: European Radiology
https://www.readbyqxmd.com/read/28091696/radiation-dose-reduction-in-parasinus-ct-by-spectral-shaping
#5
Matthias S May, Michael Brand, Michael M Lell, Martin Sedlmair, Thomas Allmendinger, Michael Uder, Wolfgang Wuest
INTRODUCTION: Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT. METHODS: All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs)...
January 16, 2017: Neuroradiology
https://www.readbyqxmd.com/read/28090811/antibacterial-combination-therapy-using-co-3-cu-2-zn-2-and-pd-2-complexes-their-calf-thymus-dna-binding-studies
#6
Fatemeh Khosravi, Hassan Mansouri-Torshizi
Four Co(III)-, Cu(II)-, Zn(II)- and Pd(II)- based potent antibacterial complexes of formula K3[Co(ox)3].3H2O (I), [Cu(bpy)2Cl]Cl.5H2O (II), [Zn(bpy)3]Cl2 (III) and [Pd(bpy)2](NO3)2 (IV) (where ox is oxalate and bpy is 2,2'-bipyridine) were synthesized. They were characterized by elemental analyses, molar conductance measurements, UV-Vis, FT-IR, (1)H NMR and (13)C NMR spectra. These metal complexes were ordered in three combination series of I+II, I+II+III and I+II+III+IV. Antibacterial activity was tested for each of these four metal complexes and their combinations against gram positive and gram negative bacteria...
January 16, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28089491/satellite-and-central-transitions-selective-1-h-27-al-d-hmqc-experiments-at-very-fast-mas-for-quadrupolar-couplings-determination
#7
Nghia Tuan Duong, Yusuke Nishiyama
Recent study has demonstrated the application of the proton-detected heteronuclear multi-quantum coherence (HMQC) at ultrafast Magic Angle Spinning (MAS) to probe quadrupolar nuclei including (14)N and (35)Cl. In addition, for half-integer quadrupolar nucleus like (35)Cl, the quadrupolar product can be calculated based on the shift difference between the center band of satellite transition (ST) and the central transition (CT) peaks. The applicability of this technique is further investigated on spin I=5/2, namely (27)Al nucleus, and kaolin is chosen as the testing sample...
January 4, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28088690/electrochemical-studies-of-dna-interaction-and-antimicrobial-activities-of-mn-ii-fe-iii-co-ii-and-ni-ii-schiff-base-tetraazamacrocyclic-complexes
#8
Anuj Kumar, Vinod Kumar Vashistha, Prashant Tevatia, Randhir Singh
Tetraazamacrocyclic complexes of Mn(II), Fe(III), Co(II) and Ni(II) have been synthesized by template method. These tetraazamacrocycles have been analyzed with various techniques like molar conductance, IR, UV-vis, mass spectral and cyclic voltammetric studies. On the basis of all these studies, octahedral geometry has been assigned to these tetraazamacrocyclic complexes. The DNA binding properties of these macrocyclic complexes have been investigated by electronic absorption spectra, fluorescence spectra, cyclic voltammetric and differential pulse voltammetric studies...
January 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28070917/dual-energy-ct-quantitative-imaging-a-comparison-study-between-twin-beam-and-dual-source-ct-scanners
#9
Isabel P Almeida, Lotte E J R Schyns, Michel C Öllers, Wouter van Elmpt, Katia Parodi, Guillaume Landry, Frank Verhaegen
PURPOSE: To assess image quality and to quantify the accuracy of relative electron densities (ρe ) and effective atomic numbers (Zeff ) for three dual-energy computed tomography (DECT) scanners: a novel single-source split-filter (i.e., twin-beam) and two dual-source scanners. METHODS: Measurements were made with a second generation dual-source scanner at 80/140Sn kVp, a third-generation twin-beam single-source scanner at 120 kVp with gold (Au) and tin (Sn) filters, and a third-generation dual-source scanner at 90/150Sn kVp...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28057647/characterisation-of-choroidal-morphological-and-vascular-features-in-diabetes-and-diabetic-retinopathy
#10
Preeti Gupta, Sri Gowtham Thakku, Charumathi Sabanayagam, Gavin Tan, Chui Ming Gemmy Cheung, Ecosse L Lamoureux, Tien-Yin Wong, Ching-Yu Cheng
AIM: We aimed to characterise specific morphological and vascular features of the choroid in Indian adults with diabetes and diabetic retinopathy (DR). METHODS: Consecutive participants from the Singapore Indian Eye Study's 6-year follow-up examination underwent choroidal imaging using spectral domain optical coherence tomography (OCT) with enhanced depth imaging. Raw OCT images were loaded on a custom-written application on MATLAB that enabled delineation for detailed morphological and vascular analyses...
January 5, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28048876/we-fg-207b-05-iterative-reconstruction-via-prior-image-constrained-total-generalized-variation-for-spectral-ct
#11
S Niu, Y Zhang, J Ma, J Wang
PURPOSE: To investigate iterative reconstruction via prior image constrained total generalized variation (PICTGV) for spectral computed tomography (CT) using fewer projections while achieving greater image quality. METHODS: The proposed PICTGV method is formulated as an optimization problem, which balances the data fidelity and prior image constrained total generalized variation of reconstructed images in one framework. The PICTGV method is based on structure correlations among images in the energy domain and high-quality images to guide the reconstruction of energy-specific images...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048854/su-g-206-03-ctdi-per-kv-at-phantom-center-and-periphery-comparison-between-major-ct-manufacturers
#12
R Al-Senan, O Demirkaya
PURPOSE: The purpose of this study was to: 1) compare scanners output by measuring normalized CTDIw (mGy/100mAs) in different CT makes and models and at different kV's, and 2) quantify the relationship between kV and CTDI and compare this relationship between the different manufacturers. METHODS: Study included forty scanners of major CT manufacturers and of various models. Exposure was measured at center and 12 o'clock holes of head and body CTDI phantoms, at all available kV's, and with the largest or second largest available collimation in each scanner...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048802/tu-ab-brc-03-accurate-tissue-characterization-for-monte-carlo-dose-calculation-using-dual-and-multi-energy-ct-data
#13
A Lalonde, H Bouchard
PURPOSE: To develop a general method for human tissue characterization with dual-and multi-energy CT and evaluate its performance in determining elemental compositions and the associated proton stopping power relative to water (SPR) and photon mass absorption coefficients (EAC). METHODS: Principal component analysis is used to extract an optimal basis of virtual materials from a reference dataset of tissues. These principal components (PC) are used to perform two-material decomposition using simulated DECT data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048652/tu-d-brb-00-dual-energy-ct-in-radiation-therapy
#14
Zacariah Labby
: Dual-energy CT technology is becoming increasingly available to the medical imaging community. In addition, several models of CT simulators sold for use in radiation therapy departments now feature dual-energy technology. The images provided by dual-energy CT scanners add new information to the radiation treatment planning process; multiple spectral components can be used to separate and identify material composition as well as generate virtual monoenergetic images. In turn, this information could be used to investigate pathologic processes, separate the properties of contrast agents from soft tissues, assess tissue response to therapy, and other applications of therapeutic interest...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048512/th-cd-202-04-evaluation-of-virtual-non-contrast-images-from-a-novel-split-filter-dual-energy-ct-technique
#15
J Huang, T Szczykutowicz, J Bayouth, J Miller
PURPOSE: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. METHODS: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7-20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between the acquisition of low- and high-energy data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048430/we-fg-207b-03-multi-energy-ct-reconstruction-with-spatial-spectral-nonlocal-means-regularization
#16
B Li, C Shen, L Ouyang, M Yang, L Zhou, S Jiang, X Jia
PURPOSE: Multi-energy computed tomography (MECT) is an emerging application in medical imaging due to its ability of material differentiation and potential for molecular imaging. In MECT, image correlations at different spatial and channels exist. It is desirable to incorporate these correlations in reconstruction to improve image quality. For this purpose, this study proposes a MECT reconstruction technique that employes spatial spectral non-local means (ssNLM) regularization. METHODS: We consider a kVp-switching scanning method in which source energy is rapidly switched during data acquisition...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048112/mo-de-207a-05-dictionary-learning-based-reconstruction-with-low-rank-constraint-for-low-dose-spectral-ct
#17
Q Xu, H Liu, H Yu, G Wang, L Xing
PURPOSE: Spectral CT enabled by an energy-resolved photon-counting detector outperforms conventional CT in terms of material discrimination, contrast resolution, etc. One reconstruction method for spectral CT is to generate a color image from a reconstructed component in each energy channel. However, given the radiation dose, the number of photons in each channel is limited, which will result in strong noise in each channel and affect the final color reconstruction. Here we propose a novel dictionary learning method for spectral CT that combines dictionary-based sparse representation method and the patch based low-rank constraint to simultaneously improve the reconstruction in each channel and to address the inter-channel correlations to further improve the reconstruction...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047985/tu-d-brb-01-dual-energy-ct-techniques-in-acquisition-and-image-processing
#18
N Pelc
: Dual-energy CT technology is becoming increasingly available to the medical imaging community. In addition, several models of CT simulators sold for use in radiation therapy departments now feature dual-energy technology. The images provided by dual-energy CT scanners add new information to the radiation treatment planning process; multiple spectral components can be used to separate and identify material composition as well as generate virtual monoenergetic images. In turn, this information could be used to investigate pathologic processes, separate the properties of contrast agents from soft tissues, assess tissue response to therapy, and other applications of therapeutic interest...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047924/tu-fg-brb-01-dual-energy-ct-proton-stopping-power-ratio-calibration-and-validation-with-animal-tissues
#19
Y Xie, L Yin, C Ainsley, J McDonough, T Solberg, A Lin, B Teo
PURPOSE: The conversion of Hounsfield Unit (HU) to proton stopping power ratio (SPR) is a main source of uncertainty in proton therapy. In this study, the SPRs of animal tissues were measured and compared with prediction from dual energy CT (DECT) and single energy CT (SECT) calibrations. METHODS: A stoichiometric calibration method for DECT was applied to predict the SPR using CT images acquired at 80 kVp and 140 kVp. The dual energy index was derived based on the HUs of the paired spectral images and used to calculate the SPRs of the materials...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047780/we-fg-207b-04-noise-suppression-for-energy-resolved-ct-via-variance-weighted-non-local-filtration
#20
J Harms, L Zhu
PURPOSE: The photon starvation problem is exacerbated in energy-resolved CT, since the detected photons are shared by multiple energy channels. Using pixel similarity-based non-local filtration, we aim to produce accurate and high-resolution energy-resolved CT images with significantly reduced noise. METHODS: Averaging CT images reconstructed from different energy channels reduces noise at the price of losing spectral information, while conventional denoising techniques inevitably degrade image resolution...
June 2016: Medical Physics
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