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CT theory and use

Mangesh R Dharme, Abhaykumar M Kuthe, Tushar R Deshmukh
PURPOSE: Human activities generate stresses, which vary with time and may result in fatigue failure of the customized hip implant. This study aims to investigate fatigue testing of customized hip implants using the minimum number of experiments by the Taguchi method, for 147 patients. This study was also useful to determine the influential geometrical parameters on the fatigue safety factor of customized hip implants. METHODS: Horizontal offset (HO), vertical offset (VO) and neck shaft angle (NSA) of the hip joint of 147 patients were measured on computed tomography (CT) scanned images...
January 20, 2017: International Journal of Artificial Organs
Alvar-Ginés Legaz-Aparicio, Rafael Verdú-Monedero, Jorge Larrey-Ruiz, Juan Morales-Sánchez, Fernando López-Mir, Valery Naranjo, Ángela Bernabéu
This paper addresses the functional localization of intra-patient images of the brain. Functional images of the brain (fMRI and PET) provide information about brain function and metabolism whereas anatomical images (MRI and CT) supply the localization of structures with high spatial resolution. The goal is to find the geometric correspondence between functional and anatomical images in order to complement and fuse the information provided by each imaging modality. The proposed approach is based on a variational formulation of the image registration problem in the frequency domain...
November 29, 2016: International Journal of Neural Systems
L Buckley, R Webb, C Lambert, B Nyiri, L Gerig
PURPOSE: To standardize the tube calibration for Elekta XVI cone beam CT (CBCT) systems in order to provide a meaningful estimate of the daily imaging dose and reduce the variation between units in a large centre with multiple treatment units. METHODS: Initial measurements of the output from the CBCT systems were made using a Farmer chamber and standard CTDI phantom. The correlation between the measured CTDI and the tube current was confirmed using an Unfors Xi detector which was then used to perform a tube current calibration on each unit...
June 2016: Medical Physics
Y Chen, S Wu, H Qi, Y Xu, L Zhou
PURPOSE: Image artifacts are usually evaluated qualitatively via visual observation of the reconstructed images, which is susceptible to subjective factors due to the lack of an objective evaluation criterion. In this work, we propose a Helgason-Ludwig consistency condition (HLCC) based evaluation method to quantify the severity level of different image artifacts in dental CBCT. METHODS: Our evaluation method consists of four step: 1) Acquire Cone beam CT(CBCT) projection; 2) Convert 3D CBCT projection to fan-beam projection by extracting its central plane projection; 3) Convert fan-beam projection to parallel-beam projection utilizing sinogram-based rebinning algorithm or detail-based rebinning algorithm; 4) Obtain HLCC profile by integrating parallel-beam projection per view and calculate wave percentage and variance of the HLCC profile, which can be used to describe the severity level of image artifacts...
June 2016: Medical Physics
E Baer, K Jee, R Zhang, A Lalonde, K Yang, G Sharp, G Royle, B Liu, H Bouchard, H Lu
PURPOSE: To evaluate the clinical performance of dual-energy CT (DECT) in determining proton stopping power ratios (SPR) and demonstrate advantages over conventional single-energy CT (SECT). METHODS: SECT and DECT scans of tissue-equivalent plastics as well as animal meat samples are performed with a Siemens SOMATOM Definition Flash. The methods of Schneider et al. (1996) and Bourque et al. (2014) are used to determine proton SPR on SECT and DECT images, respectively...
June 2016: Medical Physics
Adam G Polak, Janusz Mroczka, Dariusz Wysoczański
Since computed tomography (CT) was developed over 35 years ago, new mathematical ideas and computational algorithms have been continuingly elaborated to improve the quality of reconstructed images. In recent years, a considerable effort can be noticed to apply the sparse solution of underdetermined system theory to the reconstruction of CT images from undersampled data. Its significance stems from the possibility of obtaining good quality CT images from low dose projections. Among diverse approaches, total variation (TV) minimizing 2D gradients of an image, seems to be the most popular method...
December 21, 2016: Computers in Biology and Medicine
María P Badenes, María E Tucceri, Carlos J Cobos
The kinetics of the gas phase recombination reaction HO + HO2 + He → HOOOH + He has been studied between 200 and 600 K by using the SACM/CT model and the unimolecular rate theory. The molecular properties of HOOOH were derived at the CCSD(T)/aug-cc-pVTZ ab initio level of theory, while relevant potential energy features of the reaction were calculated at the CCSD(T)/aug-cc-pVTZ//CCSD(T)/aug-cc-pVDZ level. The resulting high and low pressure limit rate coefficients are k∞ = 3.55 × 10(-12) (T/300)(0.20) cm(3) molecule(-1) s(-1) and k0 = [He] 1...
January 19, 2017: Journal of Physical Chemistry. A
Amanda K Fingarson, Maura E Ryan, Suzanne G McLone, Corey Bregman, Emalee G Flaherty
OBJECTIVE Benign external hydrocephalus (BEH) is an enlargement of the subarachnoid spaces (SASs) that can be seen in young children. It is controversial whether children with BEH are predisposed to developing subdural hemorrhage (SDH) with or without trauma. This issue is clinically relevant as a finding of unexplained SDH raises concerns about child abuse and often prompts child protection and law enforcement investigations. METHODS This retrospective study included children (1-24 months of age) who underwent head CT scanning after an accidental fall of less than 6 feet...
November 25, 2016: Journal of Neurosurgery. Pediatrics
Punam K Saha, Subhadip Basu, Eric A Hoffman
Theoretical properties of a multi-scale opening (MSO) algorithm for two conjoined fuzzy objects are established, and its extension to separating two conjoined fuzzy objects with different intensity properties is introduced. Also, its applications to artery/vein (A/V) separation in pulmonary CT imaging and carotid vessel segmentation in CT angiograms (CTAs) of patients with intracranial aneurysms are presented. The new algorithm accounts for distinct intensity properties of individual conjoined objects by combining fuzzy distance transform (FDT), a morphologic feature, with fuzzy connectivity, a topologic feature...
October 2016: IEEE Transactions on Fuzzy Systems: a Publication of the IEEE Neural Networks Council
Sarosh N Fatakia, Ishita S Mehta, Basuthkar J Rao
Forty-six chromosome territories (CTs) are positioned uniquely in human interphase nuclei, wherein each of their positions can range from the centre of the nucleus to its periphery. A non-empirical basis for their non-random arrangement remains unreported. Here, we derive a suprachromosomal basis of that overall arrangement (which we refer to as a CT constellation), and report a hierarchical nature of the same. Using matrix algebra, we unify intrinsic chromosomal parameters (e.g., chromosomal length, gene density, the number of genes per chromosome), to derive an extrinsic effective gene density matrix, the hierarchy of which is dominated largely by extrinsic mathematical coupling of HSA19, followed by HSA17 (human chromosome 19 and 17, both preferentially interior CTs) with all CTs...
November 15, 2016: Scientific Reports
Amir Kiperwas, Daniel Rosenfeld, Yonina C Eldar
We present an algorithm for resampling a function from its values on a non-Cartesian grid onto a Cartesian grid. This problem arises in many applications such as MRI, CT, radio astronomy and geophysics. Our algorithm, termed SParse Uniform ReSampling (SPURS), employs methods from modern sampling theory to achieve a small approximation error while maintaining low computational cost. The given non-Cartesian samples are projected onto a selected intermediate subspace, spanned by integer translations of a compactly supported kernel function...
November 1, 2016: IEEE Transactions on Medical Imaging
Kate L Durrant, Ian M Skicko, Craig Sturrock, Sophie L Mowles
Sperm competition theory predicts that animals face a trade-off between investment in weaponry and investment in ejaculate composition. Within the Madagascan giant hissing cockroaches (Tribe Gromphadorhini) differences in morphology exist that may indicate differing strategies of male-male competition. We compared relative pronotal horn length using high-resolution X-ray CT scanning data, relative testes mass, and male-male agonistic behaviour between two species of hissing cockroaches, Gromphadorhina oblongonota and Aeluropoda insignis...
November 7, 2016: Scientific Reports
Gábor Orosz, Péter Krekó, Benedek Paskuj, István Tóth-Király, Beáta Bőthe, Christine Roland-Lévy
Conspiracy theory (CT) beliefs can be harmful. How is it possible to reduce them effectively? Three reduction strategies were tested in an online experiment using general and well-known CT beliefs on a comprehensive randomly assigned Hungarian sample (N = 813): exposing rational counter CT arguments, ridiculing those who hold CT beliefs, and empathizing with the targets of CT beliefs. Several relevant individual differences were measured. Rational and ridiculing arguments were effective in reducing CT, whereas empathizing with the targets of CTs had no effect...
2016: Frontiers in Psychology
Arthur Lalonde, Hugo Bouchard
To develop a general method for human tissue characterization with dual- and multi-energy CT and evaluate its performance in determining elemental compositions and quantities relevant to radiotherapy Monte Carlo dose calculation. Ideal materials to describe human tissue are obtained applying principal component analysis on elemental weight and density data available in literature. The theory is adapted to elemental composition for solving tissue information from CT data. A novel stoichiometric calibration method is integrated to the technique to make it suitable for a clinical environment...
November 21, 2016: Physics in Medicine and Biology
Ling Xue, Nick Holford, Xiao-Liang Ding, Zhen-Ya Shen, Chen-Rong Huang, Hua Zhang, Jing-Jing Zhang, Zhe-Ning Guo, Cheng Xie, Ling Zhou, Zhi-Yao Chen, Lin-Sheng Liu, Li-Yan Miao
AIMS: The aims of this study are to apply a theory based mechanistic model to describe the pharmacokinetics (PK) and pharmacodynamics (PD) of S- and R-warfarin. METHODS: Clinical data were obtained from 264 patients. Total concentrations for S- and R-warfarin were measured by ultra-high performance liquid tandem mass spectrometry. Genotypes were measured using pyrosequencing. A sequential population pharmacokinetic parameter with data method was used to describe the international normalized ratio (INR) time course...
October 20, 2016: British Journal of Clinical Pharmacology
Silvio Danese, Stefanos Bonovas, Laurent Peyrin-Biroulet
Biologic agents have revolutionized the care management of many life-threatening and debilitating diseases. As patents for older biologic therapies have begun to expire, the market has opened to copy versions of the originators - commonly referred to as biosimilars, follow-on biologic agents or subsequent-entry biologic agents - which are expected to gain a portion of the market, reduce health-care spending and increase treatment access worldwide. Importantly for patients with IBD, CT-P13 was the first biosimilar to infliximab that obtained regulatory approval by the European Medicines Agency in September 2013 and by the FDA in April 2016...
January 2017: Nature Reviews. Gastroenterology & Hepatology
Yuezhi Mao, Omar Demerdash, Martin Head-Gordon, Teresa Head-Gordon
AMOEBA is a molecular mechanics force field that addresses some of the shortcomings of a fixed partial charge model, by including permanent atomic point multipoles through quadrupoles, as well as many-body polarization through the use of point inducible dipoles. In this work, we investigate how well AMOEBA formulates its non-bonded interactions, and how it implicitly incorporates quantum mechanical effects such as charge penetration (CP) and charge transfer (CT), for water-water and water-ion interactions. We find that AMOEBA's total interaction energies, as a function of distance and over angular scans for the water dimer and for a range of water-monovalent cations, agree well with an advanced density functional theory (DFT) model, whereas the water-halides and water-divalent cations show significant disagreement with the DFT result, especially in the compressed region when the two fragments overlap...
November 8, 2016: Journal of Chemical Theory and Computation
Luzhen Deng, Peng Feng, Mianyi Chen, Peng He, Biao Wei
Compressive Sensing (CS) theory has great potential for reconstructing Computed Tomography (CT) images from sparse-views projection data and Total Variation- (TV-) based CT reconstruction method is very popular. However, it does not directly incorporate prior images into the reconstruction. To improve the quality of reconstructed images, this paper proposed an improved TV minimization method using prior images and Split-Bregman method in CT reconstruction, which uses prior images to obtain valuable previous information and promote the subsequent imaging process...
2016: BioMed Research International
Amlan K Pal, David B Cordes, Alexandra M Z Slawin, Cristina Momblona, Enrique Ortı, Ifor D W Samuel, Henk J Bolink, Eli Zysman-Colman
The structure-property relationship study of a series of cationic Ir(III) complexes in the form of [Ir(C^N)2(dtBubpy)]PF6 [where dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine and C^N = cyclometallating ligand bearing an electron-withdrawing group (EWG) at C4 of the phenyl substituent, i.e., -CF3 (1), -OCF3 (2), -SCF3 (3), -SO2CF3 (4)] has been investigated. The physical and optoelectronic properties of the four complexes were comprehensively characterized, including by X-ray diffraction analysis. All the complexes exhibit quasireversible dtBubpy-based reductions from -1...
October 17, 2016: Inorganic Chemistry
Celal Tuğrul Zeyrek, Bahadir Boyacioğlu, Mustafa Yıldız, Hüseyin Ünver, Devrim Yolal, Neslihan Demir, Ayhan Elmali, Solomon Tadesse, Kadir Aslan
An amino acid based and bidentate Schiff base, (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate (ligand), was synthesized from the reaction of glycine-methyl ester hydrochloride with 2-hydroxy-1-naphthaldehyde. Characterization of the ligand was carried out using theoretical quantum-mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV-Visible spectroscopy, which were in good agreement with the structure predicted by the theoretical calculations using density functional theory (DFT)...
November 1, 2016: Bioorganic & Medicinal Chemistry
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