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https://www.readbyqxmd.com/read/28064557/compact-self-grounded-bow-tie-antenna-design-for-an-uwb-phased-array-hyperthermia-applicator
#1
Pegah Takook, Mikael Persson, Johanna Gellermann, Hana Dobšíček Trefná
Using UWB hyperthermia systems has the potential to improve the heat delivery to deep seated tumours. In this paper, we present a novel self-grounded Bow-Tie antenna design which is to serve as the basis element in a phased-array applicator. The UWB operation in the frequency range of 0.43-1 GHz is achieved by immersing the antenna in a water bolus. The radiation characteristics are improved by appropriate shaping the water bolus and by inclusion of dielectric layers on the top of the radiating arms of the antenna...
January 8, 2017: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/28048844/su-f-j-70-monte-carlo-study-on-a-cone-beam-computed-tomography-using-a-cross-type-carbon-fiber-antiscatter-grid
#2
K Usui, T Inoue, C Kurokawa, S Sugimoto, K Sasai, K Ogawa
PURPOSE: If a cone-beam computed tomography (CBCT) image can be used for adaptive radiotherapy (ART), an irradiated actual dose distribution can be verified on every treatment day. However, a CBCT image is commonly degraded by scattered photons and thus cannot be directly used for dose calculation. The purpose of the present study is to evaluate whether a cross-type carbon fiber antiscatter grid improves CBCT image quality using a Monte Carlo (MC) method for achieving CBCT-based ART. METHODS: We designed a new carbon fiber (C6 H10 O5 ) interspaced grid, which allows the grid ratio to be increased while maintaining the transmission of primary photons...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048160/su-f-j-198-a-cross-platform-adaptation-of-an-a-priori-scatter-correction-algorithm-for-cone-beam-projections-to-enable-image-and-dose-guided-proton-therapy
#3
A Andersen, Y Park, O Casares-Magaz, U Elstroem, J Petersen, B Winey, L Muren
PURPOSE: Cone-beam CT (CBCT) imaging may enable image- and dose-guided proton therapy, but is challenged by image artefacts. The aim of this study was to demonstrate the general applicability of a previously developed a priori scatter correction algorithm to allow CBCT-based proton dose calculations. METHODS: The a priori scatter correction algorithm used a plan CT (pCT) and raw cone-beam projections acquired with the Varian On-Board Imager. The projections were initially corrected for bow-tie filtering and beam hardening and subsequently reconstructed using the Feldkamp-Davis-Kress algorithm (rawCBCT)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048073/su-f-j-16-planar-kv-imaging-dose-reduction-study
#4
E Gershkevitsh, D Zolotuhhin
PURPOSE: IGRT has become an indispensable tool in modern radiotherapy with kV imaging used in many departments due to superior image quality and lower dose when compared to MV imaging. Many departments use manufacturer supplied protocols for imaging which are not always optimised between image quality and radiation dose (ALARA). METHODS: Whole body phantom PBU-50 (Kyoto Kagaku ltd., Japan) for imaging in radiology has been imaged on Varian iX accelerator (Varian Medical Systems, USA) with OBI 1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047535/su-f-i-38-patient-organ-specific-dose-assessment-in-coronary-ct-angiograph-using-voxellaized-volume-dose-index-in-monte-carlo-simulation
#5
Mohammadi Gh Fallal, Alam N Riyahi, Gh Graily, R Paydar
PURPOSE: Clinical use of multi detector computed tomography(MDCT) in diagnosis of diseases due to high speed in data acquisition and high spatial resolution is significantly increased. Regarding to the high radiation dose in CT and necessity of patient specific radiation risk assessment, the adoption of new method in the calculation of organ dose is completely required and necessary. In this study by introducing a conversion factor, patient organ dose in thorax region based on CT image data using MC system was calculated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047497/th-cd-207b-05-measurement-of-ct-bow-tie-profiles-using-a-linear-array-detector
#6
K Yang, X Li, B Liu
PURPOSE: To accurately measure CT bow-tie profiles from various manufacturers and to provide non-proprietary information for CT system modeling. METHODS: A GOS-based linear detector (0.8 mm per pixel and 51.2 cm in length) with a fast data sampling speed (0.24 ms/sample) was used to measure the relative profiles of bow-tie filters from a collection of eight CT scanners by three different vendors, GE (LS Xtra, LS VCT, Discovery HD750), Siemens (Sensation 64, Edge, Flash, Force), and Philips (iBrilliance 256)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047455/su-f-j-39-dose-reduction-strategy-using-attenuation-based-tube-current-modulation-method-in-cbct-for-igrt
#7
K Son, H Lee, C Kim, J Kim, S Cho
PURPOSE: To reduce radiation dose to the patients, tube current modulation (TCM) method has been actively used in diagnostic CT systems. However, TCM method has not yet been applied to a kV-CBCT system on a LINAC machine. The purpose of this study is to investigate whether the use of TCM method is desirable in kV-CBCT system for IGRT. We have developed an attenuation-based tube current modulation (a-TCM) method using the prior knowledge of treatment CT image of a patient. METHODS: Patients go through a diagnostic CT scan for RT planning; therefore, using this prior information of CT images, one can estimate the total attenuation of an x-ray through the patient body in a CBCT setting for radiation therapy...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28039975/dynamics-of-bow-tie-shaped-bursting-forced-pendulum-with-dynamic-feedback
#8
Thotreithem Hongray, Janaki Balakrishnan
A detailed study is performed on the parameter space of the mechanical system of a driven pendulum with damping and constant torque under feedback control. We report an interesting bow-tie shaped bursting oscillatory behaviour, which is exhibited for small driving frequencies, in a certain parameter regime, which has not been reported earlier in this forced system with dynamic feedback. We show that the bursting oscillations are caused because of a transition of the quiescent state to the spiking state by a saddle-focus bifurcation, and because of another saddle-focus bifurcation, which leads to cessation of spiking, bringing the system back to the quiescent state...
December 2016: Chaos
https://www.readbyqxmd.com/read/27991677/a-longitudinal-four-dimensional-computed-tomography-and-cone-beam-computed-tomography-dataset-for-image-guided-radiation-therapy-research-in-lung-cancer
#9
Geoffrey D Hugo, Elisabeth Weiss, William C Sleeman, Salim Balik, Paul J Keall, Jun Lu, Jeffrey F Williamson
PURPOSE: To describe in detail a dataset consisting of serial four-dimensional computed tomography (4DCT) and 4D cone beam CT (4DCBCT) images acquired during chemoradiotherapy of 20 locally-advanced, non-small cell lung cancer patients we have collected at our institution and shared publicly with the research community. ACQUISITION AND VALIDATION METHODS: As part of an NCI-sponsored research study 82 4DCT and 507 4DCBCT images were acquired in a population of 20 locally advanced non-small cell lung cancer patients undergoing radiation therapy...
December 19, 2016: Medical Physics
https://www.readbyqxmd.com/read/27857146/high-flux-circularly-polarized-gamma-beam-factory-coupling-a-fabry-perot-optical-cavity-with-an-electron-storage-ring
#10
I Chaikovska, K Cassou, R Chiche, R Cizeron, P Cornebise, N Delerue, D Jehanno, F Labaye, R Marie, A Martens, Y Peinaud, V Soskov, A Variola, F Zomer, E Cormier, J Lhermite, V Dolique, R Flaminio, C Michel, L Pinard, B Sassolas, T Akagi, S Araki, Y Honda, T Omori, N Terunuma, J Urakawa, S Miyoshi, T Takahashi, H Yoshitama
We report and discuss high-flux generation of circularly polarized γ-rays by means of Compton scattering. The γ-ray beam results from the collision of an external-cavity-enhanced infrared laser beam and a low emittance relativistic electron beam. By operating a non-planar bow-tie high-finesse optical Fabry-Perot cavity coupled to a storage ring, we have recorded a flux of up to (3.5 ± 0.3) × 10(8) photons per second with a mean measured energy of 24 MeV. The γ-ray flux has been sustained for several hours...
November 18, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27851881/magnetic-resonance-safety-and-compatibility-of-tantalum-markers-used-in-proton-beam-therapy-for-intraocular-tumors-a-7-0-tesla-study
#11
Eva Oberacker, Katharina Paul, Till Huelnhagen, Celal Oezerdem, Lukas Winter, Andreas Pohlmann, Laura Boehmert, Oliver Stachs, Jens Heufelder, Andreas Weber, Matus Rehak, Ira Seibel, Thoralf Niendorf
PURPOSE: Proton radiation therapy (PRT) is a standard treatment of uveal melanoma. PRT patients undergo implantation of ocular tantalum markers (OTMs) for treatment planning. Ultra-high-field MRI is a promising technique for 3D tumor visualization and PRT planning. This work examines MR safety and compatibility of OTMs at 7.0 Tesla. METHODS: MR safety assessment included deflection angle measurements (DAMs), electromagnetic field (EMF) simulations for specific absorption rate (SAR) estimation, and temperature simulations for examining radiofrequency heating using a bow-tie dipole antenna for transmission...
November 10, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27832557/bow-tie-diagrams-for-risk-management-in-anaesthesia
#12
M D Culwick, A F Merry, D M Clarke, K J Taraporewalla, N M Gibbs
Bow-tie analysis is a risk analysis and management tool that has been readily adopted into routine practice in many high reliability industries such as engineering, aviation and emergency services. However, it has received little exposure so far in healthcare. Nevertheless, its simplicity, versatility, and pictorial display may have benefits for the analysis of a range of healthcare risks, including complex and multiple risks and their interactions. Bow-tie diagrams are a combination of a fault tree and an event tree, which when combined take the shape of a bow tie...
November 2016: Anaesthesia and Intensive Care
https://www.readbyqxmd.com/read/27806588/source-modeling-for-monte-carlo-dose-calculation-of-ct-examinations-with-a-radiotherapy-treatment-planning-system
#13
Hans-Erik Källman, Rickard Holmberg, Jonas Andersson, Love Kull, Erik Tranéus, Anders Ahnesjö
PURPOSE: Radiation dose to patients undergoing examinations with Multislice Computed Tomography (MSCT) as well as Cone Beam Computed Tomography (CBCT) is a matter of concern. Risk management could benefit from efficient replace rational dose calculation tools. The paper aims to verify MSCT dose calculations using a Treatment Planning System (TPS) for radiotherapy and to evaluate four different variations of bow-tie filter characterizations for the beam model used in the dose calculations...
November 2016: Medical Physics
https://www.readbyqxmd.com/read/27720467/dynamic-safety-assessment-of-natural-gas-stations-using-bayesian-network
#14
Esmaeil Zarei, Ali Azadeh, Nima Khakzad, Iraj Mohammadfam
Pipelines are one of the most popular and effective ways of transporting hazardous materials, especially natural gas. However, the rapid development of gas pipelines and stations in urban areas has introduced a serious threat to public safety and assets. Although different methods have been developed for risk analysis of gas transportation systems, a comprehensive methodology for risk analysis is still lacking, especially in natural gas stations. The present work is aimed at developing a dynamic and comprehensive quantitative risk analysis (DCQRA) approach for accident scenario and risk modeling of natural gas stations...
October 1, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27661881/distributed-measurement-of-hydrostatic-pressure-based-on-brillouin-dynamic-grating-in-polarization-maintaining-fibers
#15
Yong Hyun Kim, Hong Kwon, Jeongjun Kim, Kwang Yong Song
High-sensitivity distributed measurement of hydrostatic pressure is experimentally demonstrated by optical time-domain analysis of Brillouin dynamic grating (BDG) in polarization maintaining fibers (PMF's). The spectral shift of the BDG in four different types of PMF's are investigated under hydrostatic pressure variation from 14.5 psi (1 bar) to 884.7 psi (61 bar) with less than 2 m spatial resolution. The pressure sensitivity of BDG frequency is measured to be ‒1.69, + 0.65, + 0.78, and + 0.85 MHz/psi for a PM photonic crystal fiber (PM-PCF), two Bow-tie fibers, and a PANDA fiber, respectively, which is about 65 to 169 times larger than that of Brillouin frequency-based pressure sensing...
September 19, 2016: Optics Express
https://www.readbyqxmd.com/read/27659367/a-bow-tie-for-hand-trauma
#16
S Chegini, A De Leo, S Tucker
No abstract text is available yet for this article.
September 23, 2016: Annals of the Royal College of Surgeons of England
https://www.readbyqxmd.com/read/27628363/1-95%C3%A2-%C3%A2-%C3%AE-m-pumped-op-gaas-optical-parametric-oscillator-with-10-6%C3%A2-%C3%A2-%C3%AE-m-idler-wavelength
#17
Jochen Wueppen, Sebastian Nyga, Bernd Jungbluth, Dieter Hoffmann
We report on an optical parametric oscillator that generates output idler wavelengths around 10.6 μm. On the basis of orientation-patterned gallium arsenide (OP-GaAs) as a nonlinear medium and a 1.95 μm ns-pulsed pump laser, a signal-resonant bow-tie resonator was designed in order to maximize the output power at moderate intensities well below the damage threshold of the optical components. With this setup, the average idler output power at 50 kHz and 100 ns idler pulse length was more than 800 mW, which corresponds to a pulse energy of 16 μJ...
September 15, 2016: Optics Letters
https://www.readbyqxmd.com/read/27626155/differentiation-of-mild-keratoconus-from-corneal-warpage-according-to-topographic-inferior-steepening-based-on-corneal-tomography-data
#18
Lia Florim Patrão, Ana Laura Caiado Canedo, João Luiz Peixoto Braga de Azevedo, Rosane Correa, Renato Ambrósio
We report two cases of suspicious asymmetric bow tie and inferior steepening on topographic evaluations with reflection (Placido) and projection (Scheimpflug). Rotating Scheimpflug corneal and anterior segment tomography (Oculus Pentacam HR, Wetzlar, Germany)® was performed in the first case, with a maximal keratometric value (Kmax) of 43.2 D and an overall deviation value from the Belin/Ambrósio Enhanced Ectasia Display (BAD-D) of 1.76, which was observed in the study eye (OD). BAD-D was 6.59 in the fellow eye, which had clinical findings that were consistent with keratoconus stage 2...
July 2016: Arquivos Brasileiros de Oftalmologia
https://www.readbyqxmd.com/read/27607644/role-of-material-loss-and-mode-volume-of-plasmonic-nanocavities-for-strong-plasmon-exciton-interactions
#19
Zhong-Jian Yang, Tomasz J Antosiewicz, Timur Shegai
We investigate the role of material loss and mode volume of plasmonic nanostructures on strong plasmon-exciton coupling. We find that the field enhancement, and therefore loss, is not important for the magnitude of the Rabi splitting as such, but instead it is determined by the mode volume. Nevertheless, for reaching true strong coupling condition, that is, coupling greater than any dissipation, it is important to compromise losses. We also show that using such popular geometries as a dimer of two spheres or bow-tie nanoantennas, does not allow compressing the mode volume much in comparison to a single nanoparticle case, except for very narrow gaps, but rather it allows for efficient extraction of the mode out of the metal thus making it more accessible for excitons to interact with...
September 5, 2016: Optics Express
https://www.readbyqxmd.com/read/27473259/development-of-high-resolution-cathodoluminescence-system-for-stem-and-application-to-plasmonic-nanostructures
#20
REVIEW
Naoki Yamamoto
A high-resolution cathodoluminescence (CL) system for scanning transmission electron microscope (STEM) has been developed by employing a field emission gun and a spherical aberration corrector, which realizes a probe size of 1 nm even at an accelerating voltage of 80 kV and beam current of the order of 1 nA. Angle resolved measurement of light emission from a sample in the STEM is possible by combining a parabolic mirror and position-controlled pinhole. CL spectra are successively acquired by a highly sensitive charge-coupled device while scanning the incident electron beam or pinhole, which enables various detection modes, i...
August 2016: Microscopy
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