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CT theory and use

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https://www.readbyqxmd.com/read/28186469/blood-based-nucleic-acid-biomarkers-as-a-potential-tool-to-determine-radiation-therapy-response-in-non-small-cell-lung-cancer
#1
Christopher R Deig, Marc S Mendonca, Tim Lautenschlaeger
Lung cancer is the leading cause of cancer deaths worldwide, with smoking as the main risk factor. The use of low-dose computed tomography (LDCT) as a screening method has shown a 20% lung cancer specific mortality benefit; however, widespread implementation is estimated to add $1.3-$2.0 billion in annual national health care expenditures. Blood-based microRNAs (miRNAs), have been investigated in detail and found to be potentially useful biomarkers indicating the presence of lung cancer, especially when used as a companion test to LDCT...
February 10, 2017: Radiation Research
https://www.readbyqxmd.com/read/28149991/exciton-vibrational-resonance-and-dynamics-of-charge-separation-in-the-photosystem-ii-reaction-center
#2
Vladimir I Novoderezhkin, Elisabet Romero, Javier Prior, Rienk van Grondelle
The dynamics of charge separation in the photosystem II reaction center (PSII-RC) in the presence of intramolecular vibrations with their frequency matching the energy gap between the exciton state acting as the primary electron donor and the first charge-transfer (CT) state are investigated. A reduced PSII-RC 4-state model explicitly including a CT state is analyzed within Redfield relaxation theory in the multidimensional exciton-vibrational (vibronic) basis. This model is used to study coherent energy/electron transfers and their spectral signatures obtained by two-dimensional electronic spectroscopy (2DES)...
February 2, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28147535/simulating-the-absorption-spectra-of-helium-clusters-n%C3%A2-%C3%A2-70-150-231-300-using-a-charge-transfer-correction-to-superposition-of-fragment-single-excitations
#3
Qinghui Ge, Yuezhi Mao, Alec F White, Evgeny Epifanovsky, Kristina D Closser, Martin Head-Gordon
Simulations of the n = 2 absorption spectra of HeN (N = 70, 150, 231, 300) clusters are reported, with nuclear configurations sampled by path integral molecular dynamics. The electronic structure is treated by a new approach, ALMO-CIS+CT, which is a formulation of configuration interaction singles (CIS) based on absolutely localized molecular orbitals (ALMOs). The method generalizes the previously reported ALMO-CIS model [K. D. Closser et al. J. Chem. Theory Comput. 11, 5791 (2015)] to include spatially localized charge transfer (CT) effects...
January 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28129150/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#4
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
https://www.readbyqxmd.com/read/28117195/vomero-premaxillary-joint-a-marker-of-evolution-of-the-species
#5
S Botti, C Rumeau, P Gallet, R Jankowski
OBJECTIVE: According to evolutionary developmental (evo-devo) theory, the vomers are bones derived from the secondary palate. Growth of the palatine processes of the maxillae, including the precursors of vomer bones, results in midline fusion posteriorly to the primary palate, which forces the ascension of the vomer bones towards the primary nasal septum, formed by septal cartilage and the perpendicular plate of the ethmoid. According to this hypothesis, the anterior border of the vomer articulates with the posterior surface of the premaxilla in the incisive canal (IC)...
January 20, 2017: European Annals of Otorhinolaryngology, Head and Neck Diseases
https://www.readbyqxmd.com/read/28116309/analysis-of-the-osteogenic-effects-of-biomaterials-using-numerical-simulation
#6
Lan Wang, Jie Zhang, Wen Zhang, Hui-Lin Yang, Zong-Ping Luo
We describe the development of an optimization algorithm for determining the effects of different properties of implanted biomaterials on bone growth, based on the finite element method and bone self-optimization theory. The rate of osteogenesis and the bone density distribution of the implanted biomaterials were quantitatively analyzed. Using the proposed algorithm, a femur with implanted biodegradable biomaterials was simulated, and the osteogenic effects of different materials were measured. Simulation experiments mainly considered variations in the elastic modulus (20-3000 MPa) and degradation period (10, 20, and 30 days) for the implanted biodegradable biomaterials...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28109796/minimization-of-dental-implant-diameter-and-length-according-to-bone-quality-determined-by-finite-element-analysis-and-optimized-calculation
#7
Nana Ueda, Yoshiyuki Takayama, Atsuro Yokoyama
PURPOSE: The purpose of this study was to investigate the influences of bone quality and implant size on the maximum equivalent elastic strain (MES) in peri-implant bone using finite element (FE) analysis, and to minimize implant size via optimized calculation based on MES. METHODS: Three-dimensional FE models consisting of a mandible and a titanium implant with a superstructure were constructed and applied a vertical load or an oblique load of 60N. We investigated the effects of four variables: the thickness of the cortical bone (C), Young's modulus of the trabecular bone (T), and the diameter (D) and length (L) of the implant...
January 18, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28106226/applied-taguchi-method-for-fatigue-testing-of-customized-hip-implant
#8
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
https://www.readbyqxmd.com/read/28093049/efficient-variational-approach-to-multimodal-registration-of%C3%A2-anatomical%C3%A2-and%C3%A2-functional-intra-patient-tumorous-brain-data
#9
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
https://www.readbyqxmd.com/read/28048018/su-f-j-52-a-novel-approach-to-x-ray-tube-quality-assurance-for-cbct-systems-in-order-to-better-assess-the-patient-imaging-dose-in-a-large-multi-unit-treatment-facility
#10
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
https://www.readbyqxmd.com/read/28047867/we-ab-207a-12-hlcc-based-quantitative-evaluation-method-of-image-artifact-in-dental-cbct
#11
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
https://www.readbyqxmd.com/read/28047256/tu-fg-brb-02-the-impact-of-using-dual-energy-ct-for-determining-proton-stopping-powers-comparison-between-theory-and-experiments
#12
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
https://www.readbyqxmd.com/read/28027461/tomographic-image-reconstruction-via-estimation-of-sparse-unidirectional-gradients
#13
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...
February 1, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28005355/role-of-the-recombination-channel-in-the-reaction-between-the-ho-and-ho2-radicals
#14
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
https://www.readbyqxmd.com/read/27885942/enlarged-subarachnoid-spaces-and-intracranial-hemorrhage-in-children-with-accidental-head-trauma
#15
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...
February 2017: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/27885318/multiscale-opening-of-conjoined-fuzzy-objects-theory-and-applications
#16
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
https://www.readbyqxmd.com/read/27845379/systems-level-chromosomal-parameters-represent-a-suprachromosomal-basis-for-the-non-random-chromosomal-arrangement-in-human-interphase-nuclei
#17
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
https://www.readbyqxmd.com/read/27831865/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#18
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
https://www.readbyqxmd.com/read/27819321/comparative-morphological-trade-offs-between-pre-and-post-copulatory-sexual-selection-in-giant-hissing-cockroaches-tribe-gromphadorhini
#19
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
https://www.readbyqxmd.com/read/27790164/changing-conspiracy-beliefs-through-rationality-and-ridiculing
#20
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
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