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https://www.readbyqxmd.com/read/29036647/investigation-of-secondary-mixed-radiation-field-around-a-medical-linear-accelerator
#1
Piotr Tulik, Monika Tulik, Maciej Maciak, Natalia Golnik, Damian Kabat, Tomasz Byrski, Jan Lesiak
The aim of this study is to investigate secondary mixed radiation field around linac, as the first part of an overall assessment of out-of-field contribution of neutron dose for new advanced radiation dose delivery techniques. All measurements were performed around Varian Clinic 2300 C/D accelerator at Maria Sklodowska-Curie Memorial, Cancer Center and Institute of Oncology, Krakow Branch. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination (as an estimate of quality factor Q), measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt...
September 29, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29036553/two-track-control-of-cellular-machinery-for-photomovement-in-spirogyra-varians-streptophyta-zygnematales
#2
Ji Woong Lee, Gwang Hoon Kim
Plants and freshwater algae devoid of flagella evolved various photomovements to optimize their photosynthetic efficiency. The filaments of Spirogyra varians exhibit complex swaying and undulating movement and form a compact mat which enables them to adjust their light exposure. Photomovement of filament fragments (1-10 cells) was analyzed using various photoreceptor and cytoskeleton inhibitors under monochromatic light. Different patterns of movement were observed under red and blue light. The filaments showed positive phototropism under blue light...
September 27, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/29035042/nmrml-a-community-supported-open-data-standard-for-the-description-storage-and-exchange-of-nmr-data
#3
Daniel Schober, Daniel Jacob, Michael Wilson, Joseph A Cruz, Ana Marcu, Jason R Grant, Annick Moing, Catherine Deborde, Luis F de Figueiredo, Kenneth Haug, Philippe Rocca-Serra, John M Easton, Timothy M D Ebbels, Jie Hao, Christian Ludwig, Ulrich L Günther, Antonio Rosato, Matthias S Klein, Ian Lewis, Claudio Luchinat, Andrew R Jones, Arturas Grauslys, Martin Larralde, Masashi Yokochi, Naohiro Kobayashi, Andrea Porzel, Julian Griffin, Mark R Viant, David S Wishart, Christoph Steinbeck, Reza M Salek, Steffen Neumann
NMR is a widely used analytical technique with a growing number of repositories available. As a result, demands for a vendor-agnostic, open data format for long-term archiving of NMR data have emerged with the aim to ease and encourage sharing, comparison and reuse of NMR data. Here we present nmrML, an open XML-based exchange and storage format for NMR spectral data. The nmrML format is intended to be fully compatible with existing NMR data for chemical, biochemical and metabolomics experiments. nmrML can capture raw NMR data, spectral data acquisition parameters and, where available, spectral metadata such as chemical structures associated with spectral assignments...
October 16, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29029145/blood-meal-source-characterization-using-illumina-sequencing-in-the-chagas-disease-vector-rhodnius-pallescens-hemiptera-reduviidae-in-panam%C3%A3
#4
Troy J Kieran, Nicole L Gottdenker, Christina P Varian, Azael Saldaña, Nicolas Means, Darlisha Owens, Jose E Calzada, Travis C Glenn
Accurate blood meal identification is critical to understand hematophagous vector-host relationships. This study describes a customizable Next-Generation Sequencing (NGS) approach to identify blood meals from Rhodnius pallescens (Hemiptera: Reduviidae) triatomines using multiple barcoded primers and existing software to pick operational taxonomic units and match sequences for blood meal identification. We precisely identified all positive control samples using this method and further examined 74 wild-caught R...
October 4, 2017: Journal of Medical Entomology
https://www.readbyqxmd.com/read/28978754/neutralizing-human-monoclonal-antibodies-prevent-zika-virus-infection-in-macaques
#5
Diogo M Magnani, Thomas F Rogers, Nathan Beutler, Michael J Ricciardi, Varian K Bailey, Lucas Gonzalez-Nieto, Bryan Briney, Devin Sok, Khoa Le, Alexander Strubel, Martin J Gutman, Núria Pedreño-Lopez, Nathan D Grubaugh, Cassia G T Silveira, Helen S Maxwell, Aline Domingues, Mauricio A Martins, David E Lee, Erica E Okwuazi, Sherrie Jean, Elizabeth A Strobert, Ann Chahroudi, Guido Silvestri, Thomas H Vanderford, Esper G Kallas, Ronald C Desrosiers, Myrna C Bonaldo, Stephen S Whitehead, Dennis R Burton, David I Watkins
Therapies to prevent maternal Zika virus (ZIKV) infection and its subsequent fetal developmental complications are urgently required. We isolated three potent ZIKV-neutralizing monoclonal antibodies (nmAbs) from the plasmablasts of a ZIKV-infected patient-SMZAb1, SMZAb2, and SMZAb5-directed against two different domains of the virus. We engineered these nmAbs with Fc LALA mutations that abrogate Fcγ receptor binding, thus eliminating potential therapy-mediated antibody-dependent enhancement. We administered a cocktail of these three nmAbs to nonhuman primates 1 day before challenge with ZIKV and demonstrated that the nmAbs completely prevented viremia in serum after challenge...
October 4, 2017: Science Translational Medicine
https://www.readbyqxmd.com/read/28978533/non-invasive-measurement-of-renal-blood-flow-by-magnetic-resonance-imaging-mri-in-rats
#6
Cesar A Romero, Glauber Cabral, Robert A Knight, Guangliang Ding, Edward L Peterson, Oscar A Carretero
Renal blood flow (RBF) provides important information regarding renal physiology and nephropathies. Arterial spin labeling-magnetic resonance imaging (ASL-MRI) is a non-invasive method of measuring blood flow without exogenous contrast media. However, low signal/noise ratio and respiratory motion artifacts are challenges for RBF measurements in small animals. Our objective was to evaluate the feasibility and reproducibility of RBF measures by ASL-MRI using respiratory-gating and navigator correction methods to reduce motion artifacts...
October 4, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28974859/choice-of-a-suitable-dosimeter-for-photon-percentage-depth-dose-measurements-in-flattening-filter-free-beams
#7
Silvia Vargas Castrillón, Francisco Cutanda Henríquez
The International Atomic Energy Agency Technical Reports Series-398 code of practice for dosimetry recommends measuring photon percentage depth dose (PDD) curves with parallel-plate chambers. This code of practice was published before flattening filter-free (FFF) beams were widely used in clinical linear accelerators. The choice of detector for PDD measurements needs to be reassessed for FFF beams given the physical differences between FFF beams and flattened ones. The present study compares PDD curves for FFF beams of nominal energies 6 MV, 6 FFF, 10 MV, and 10 FFF from a Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, USA) acquired with Scanditronix photon diodes, two scanning type chambers (both PTW 31010 Semiflex), two small volume chambers (Wellhofer CC04 and PTW 31016 PinPoint 3D), PTW 34001 Roos, Scanditronix Roos, and NACP 02 parallel-plate chambers...
July 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28971344/the-effect-of-beam-interruption-during-fff-vmat-plans-for-sbrt
#8
Seongjong Oh, Benjamin Lewis, Amy Watson, Siyong Kim, Taeho Kim
To investigate the dosimetric effect of intended beam interruption during volumetric modulated arc therapy (VMAT) with flattening filter free (FFF) beam for exploring the possibility of deep inspiration breath hold stereotactic body radiation therapy (SBRT). A total of ten SBRT plans with 6 and 10 MV FFF beams were retrospectively selected. All plans consisted of four partial arcs, except one plan with six partial arcs. We delivered the plans using a Varian Truebeam™ with three different scenarios; without interruption (0int), with one intentional interruption (1int), or with two intentional interruptions (2int), per each partial arc...
October 2, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28921931/technical-note-a-simple-algorithm-to-convert-epid-grey-values-into-absorbed-dose-to-water-without-prior-knowledge
#9
Christine Boutry, Aurélie Sors, Jimmy Fontaine, Nolwenn Delaby, Gregory Delpon
PURPOSE: Full integration of EPID-based dosimetry in a global quality control workflow is still complicated. All the actual solutions are based on a relation between image grey-level signal and total linac delivered dose. In this study, we propose a simple algorithm relying pixel grey-level of EPID image with average linac delivered dose per acquisition frame. METHODS: Calibration models are constructed for Varian and Elekta linacs including scattering conditions and EPID-arm backscatter specific corrections...
September 16, 2017: Medical Physics
https://www.readbyqxmd.com/read/28921564/machine-specific-quality-assurance-procedure-for-stereotactic-treatments-with-dynamic-couch-rotations
#10
Byron Wilson, Ermias Gete
OBJECTIVE: We present a method in which the treatment couch's accuracy is measured using the electronic portal imaging device (EPID) and a phantom of our own construction. Using this phantom, we were able to quantify the treatment couch walkout, and the rotation angle accuracy for both static and dynamic couch treatments. These measurements were used to provide an accurate measure of the treatment couch isocentre as well as to verify the couch rotation angle recorded in the trajectory log...
September 18, 2017: Medical Physics
https://www.readbyqxmd.com/read/28905394/neutron-damage-induced-in-cardiovascular-implantable-electronic-devices-from-a-clinical-18-mv-photon-beam-a-monte-carlo-study
#11
Ahad Ollah Ezzati, Matthew T Studenski
PURPOSE: To quantify the relative neutron damage induced in CIEDs from clinical 18 MV photon beams for varying field sizes, depths and off axis distances. METHODS AND MATERIALS: Damage was assessed using silicon damage response functions and ICRP neutron dose conversion factors in MCNPX. Particular attention was devoted to the modelling of the Varian 2100C/D linear accelerator to ensure accurate contamination neutron spectra. Neutron dose, fluence and relative damage to CIEDs was calculated...
September 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/28900326/the-relationship-between-serum-selenium-and-zinc-with-gastroesophageal-cancers-in-the-southeast-of-iran
#12
Seyed Mehdi Hashemi, Mohamadali Mashhadi, Alireza Ansari Moghaddam, Javad Yousefi, Ahmad Dizangian Mofrad, Masoud Sadeghi, Abolghasem Allahyari
BACKGROUND: Selenium (Se) and zinc (Zn) have antioxidant and anticancer properties. OBJECTIVE: The aim of this study was to evaluate the serum levels of Se and Zn and the correlation between the levels of these two elements with risk of incidence of esophageal cancer (EC) and gastric cancer (GC). MATERIALS AND METHODS: In a case-control study, we selected sixty patients with GC or EC as the intervention group and 120 age-matched individuals as the control group...
April 2017: Indian Journal of Medical and Paediatric Oncology
https://www.readbyqxmd.com/read/28899649/small-field-characterization-of-a-nanochamber-prototype-under-flattening-filter-free-photon-beams
#13
G Reggiori, A Stravato, P Mancosu, F Lobefalo, L Paganini, F Zucconi, V Palumbo, A Gaudino, M Scorsetti, S Tomatis
INTRODUCTION: Nanochambers present some advantages in terms of energy independence and absolute dose measurement for small field dosimetry in the SBRT scenario. Characterization of a micro-chamber prototype was carried out both under flattened and flattening-filter-free (FFF) beams with particular focus on stem effect. METHODS: The study included characterization of leakage and stem effects, dose rate and dose per pulse dependence, measurement of profiles, and percentage depth doses (PDDs)...
September 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28887770/optimization-of-1-h-decoupling-eliminates-sideband-artifacts-in-3d-trosy-based-triple-resonance-experiments
#14
Youlin Xia, Paolo Rossi, Marco Tonelli, Chengdong Huang, Charalampos G Kalodimos, Gianluigi Veglia
TROSY-based triple resonance experiments are essential for protein backbone assignment of large biomolecular systems by solution NMR spectroscopy. In a survey of the current Bruker pulse sequence library for TROSY-based experiments we found that several sequences were plagued by artifacts that affect spectral quality and hamper data analysis. Specifically, these experiments produce sidebands in the (13)C(t 1) dimension with inverted phase corresponding to (1)HN resonance frequencies, with approximately 5% intensity of the parent (13)C crosspeaks...
September 8, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28880843/a-novel-dual-gating-approach-using-joint-inertial-sensors-implications-for-cardiac-pet-imaging
#15
Mojtaba Jafari Tadi, Jarmo Teuho, Eero Lehtonen, Antti Saraste, Mikko Pänkäälä, Tero Koivisto, Mika Teräs
Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i...
October 4, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28878078/potent-plasmablast-derived-antibodies-elicited-by-the-nih-dengue-vaccine
#16
Diogo M Magnani, Cassia G T Silveira, Michael J Ricciardi, Lucas Gonzalez-Nieto, Núria Pedreño-Lopez, Varian K Bailey, Martin J Gutman, Helen S Maxwell, Aline Domingues, Priscilla R Costa, Lilian Ferrari, Raphaella Goulart, Mauricio A Martins, José M Martinez-Navio, Sebastian P Fuchs, Jorge Kalil, Maria do Carmo Timenetsky, Jens Wrammert, Stephen S Whitehead, Dennis R Burton, Ronald C Desrosiers, Esper G Kallas, David I Waktins
Exposure to dengue virus (DENV) is thought to elicit lifelong immunity, mediated by DENV-neutralizing antibodies (nAbs). However, Abs generated by primary infections confer serotype-specific protection, and immunity against other serotypes only develops after subsequent infections. Accordingly, the induction of these nAb responses acquired after serial DENV infections has been a long sought-after goal for vaccination. Nonetheless, it is still unclear if tetravalent vaccines can elicit or recall nAbs. Here, we have characterized the responses from a volunteer who had been previously exposed to DENV and was immunized with the live attenuated tetravalent vaccine Butantan-DV, developed by the NIH and Butantan...
September 6, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28871971/financial-relationships-with-industry-of-editorial-board-members-of-the-three-journals-of%C3%A2-the-american-society-for-radiation-oncology
#17
Vivek Verma
PURPOSE: To quantitate financial conflicts of interest (FCOIs) among radiation oncology peer-reviewers, specifically editorial board members of the 3 American Society for Radiation Oncology journals. METHODS AND MATERIALS: The public Centers for Medicare and Medicaid Services Open Payments database delineates payments in 3 categories (general payments, research funding, and company ownership). After excluding non-US and non-MDs, names of board members were searched...
October 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28864403/clinical-outcomes-of-several-imrt-techniques-for-patients-with-head-and-neck-cancer-a-propensity-score-weighted-analysis
#18
Jean-Emmanuel Bibault, Sophie Dussart, Pascal Pommier, Magali Morelle, Marius Huguet, Pierre Boisselier, Bernard Coche-Dequeant, Marc Alfonsi, Etienne Bardet, Michel Rives, Valentin Calugaru, Enrique Chajon, Georges Noel, Hinda Mecellem, Stephanie Servagi Vernat, Lionel Perrier, Philippe Giraud
PURPOSE: The Advanced Radiotherapy Oto-Rhino-Laryngologie (ART-ORL) study (NCT02024035) was performed to prospectively evaluate the clinical and economic aspects of helical TomoTherapy and volumetric modulated arc therapy (RapidArc, Varian Medical Systems, Palo Alto, CA) for patients with head and neck cancer. METHODS AND MATERIALS: Fourteen centers participated in this prospective comparative study. Randomization was not possible based on the availability of equipment...
June 27, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28834214/clinical-implementation-and-evaluation-of-the-acuros-dose-calculation-algorithm
#19
Chenyu Yan, Anthony G Combine, Greg Bednarz, Ronald J Lalonde, Bin Hu, Kathy Dickens, Raymond Wynn, Daniel C Pavord, M Saiful Huq
PURPOSE: The main aim of this study is to validate the Acuros XB dose calculation algorithm for a Varian Clinac iX linac in our clinics, and subsequently compare it with the wildely used AAA algorithm. METHODS AND MATERIALS: The source models for both Acuros XB and AAA were configured by importing the same measured beam data into Eclipse treatment planning system. Both algorithms were validated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6 cm × 6 cm to 40 cm × 40 cm...
August 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28834112/the-role-of-ct-myelography-in-sparing-the-spinal-cord-during-definitive-radiotherapy-in-vertebral-hemangioma
#20
S P Sudha, M S Gopalakrishnan, K Saravanan
INTRODUCTION: The spinal cord is poorly visualized on CT images but is well visualized in MRI images. However, implants used for spinal stabilization can produce artifacts on the MRI images which can interfere with identification of the cord. CT myelography in conjunction with CT simulation helps to clearly delineate the cord. MATERIALS AND METHODS: CT simulation was done in a patient with vertebral hemangioma. Pre- and post myelography images were obtained. Two plans were generated on pre and post myelography CT images using Eclipse™ treatment planning system (TPS) version 10...
August 18, 2017: Journal of Applied Clinical Medical Physics
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