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https://www.readbyqxmd.com/read/28516048/image-interpolation-improves-the-zonal-analysis-of-cartilage-t2-relaxation-in-mri
#1
Farid Badar, Yang Xia
BACKGROUND: This project aimed to investigate the improvement in the detection of osteoarthritis (OA) in cartilage by the interpolation of T2 images, in the situation when the native MRI resolution is insufficient to resolve the depth-dependent T2 characteristics in articular cartilage (AC). METHODS: Eighteen intact canine knee joints that were healthy or had mild (contralateral) or severe OA were T2-imaged in a 7T/20 cm MRI system at 200 µm/pixel resolution (macro-MRI)...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28513847/transmission-characteristics-of-a-two-dimensional-antiscatter-grid-prototype-for-cbct
#2
Cem Altunbas, Brian Kavanagh, Timur Alexeev, Moyed Miften
AIM: High fraction of scattered radiation in cone-beam CT (CBCT) imaging degrades CT number accuracy and visualization of low contrast objects. To suppress scatter in CBCT projections, we developed a focused, two-dimensional antiscatter grid (2DASG) prototype. In this work, we report on the primary and scatter transmission characteristics of the 2DASG prototype aimed for linac mounted, offset detector geometry CBCT systems in radiation therapy, and compared its performance to a conventional one-dimensional ASG (1DASG)...
May 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28508836/tabulated-square-shaped-source-model-for-linear-accelerator-electron-beam-simulation
#3
Navid Khaledi, Mahmood Reza Aghamiri, Hossein Aslian, Ahmad Ameri
CONTEXT: Using this source model, the Monte Carlo (MC) computation becomes much faster for electron beams. AIMS: The aim of this study was to present a source model that makes linear accelerator (LINAC) electron beam geometry simulation less complex. SETTINGS AND DESIGN: In this study, a tabulated square-shaped source with transversal and axial distribution biasing and semi-Gaussian spectrum was investigated. SUBJECTS AND METHODS: A low energy photon spectrum was added to the semi-Gaussian beam to correct the bremsstrahlung X-ray contamination...
January 2017: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/28503929/rare-control-of-sivmac239-infection-in-a-vaccinated-rhesus-macaque
#4
Mauricio de Aguiar Martins, Damien C Tully, Young C Shin, Lucas Gonzalez-Nieto, Kim Weisgrau, David J Bean, Rujuta Gadgil, Martin J Gutman, Aline Domingues, Helen Skye Maxwell, Diogo Magnani, Michael Ricciardi, Nuria Pedreño-Lopez, Varian Bailey, Michael Cruz, Noemia S Lima, Myrna Bonaldo, John Altman, Eva Rakasz, Saverio Capuano, Keith Reimann, Michael Piatak, Jeffrey Lifson, Ronald Desrosiers, Todd Allen, David Watkins
Effector memory T-cell (T<sub>EM</sub>) responses display potent antiviral properties and have been linked to stringent control of simian immunodeficiency virus (SIV) replication. Since recurrent antigen stimulation drives the differentiation of CD8<sup>+</sup> T-cells toward the T<sub>EM</sub> phenotype, here we incorporated a persistent herpesviral vector into a heterologous prime/boost/boost vaccine approach in order to maximize the induction of T<sub>EM</sub> responses...
May 13, 2017: AIDS Research and Human Retroviruses
https://www.readbyqxmd.com/read/28497383/form-of-dietary-methylmercury-does-not-affect-total-mercury-accumulation-in-the-tissues-of-zebra-finch
#5
Claire W Varian-Ramos, Margaret Whitney, Gary W Rice, Daniel A Cristol
Exposure to mercury in humans, other mammals, and birds is primarily dietary, with mercury in the methylated form and bound to cysteine in the tissues of prey items. Yet dosing studies are generally carried out using methylmercury chloride. Here we tested whether the accumulation of total mercury in zebra finch blood, egg, muscle, liver, kidney or brain differed depending on whether dietary mercury was complexed with chloride or cysteine. We found no effect of form of mercury on tissue accumulation. Some previous studies have found lower accumulation of mercury in tissues of animals fed complexed mercury...
May 11, 2017: Bulletin of Environmental Contamination and Toxicology
https://www.readbyqxmd.com/read/28494649/herbicidal-activity-of-pure-compound-isolated-from-rhizosphere-inhabiting-aspergillus-flavus
#6
Saeed Ullah Khattak, Ghosia Lutfullah, Zafar Iqbal, Irshad Ur Rehman, Jamshaid Ahmad, Abid Ali Khan
In the quest for bioactive natural products of fungal origin, Aspergillus flavus was isolated from rhizosphere of Mentha piperita using Potato Dextrose Agar (PDA) and Czapec Yeast Broth (CYB) nutrient media for metabolites production. In total, three different metabolites were purified using HPLC/LCMS and the structures were established using 500 Varian NMR experiments. Further the isolated metabolites in different concentrations (10, 100, 1000 μg/mL) were tested for herbicidal activity using Completely Randomized design (CRD) against the seeds of Silybum marianum and Avena fatua which are major threats to wheat crop in Pakistan...
May 11, 2017: Natural Product Research
https://www.readbyqxmd.com/read/28490985/imaged-guided-liver-stereotactic-body-radiotherapy-using-vmat-and-real-time-adaptive-tumor-gating-concerns-about-technique-and-preliminary-clinical-results
#7
Carmen Llacer-Moscardo, Olivier Riou, David Azria, Ludovic Bedos, Norbert Ailleres, Francois Quenet, Philippe Rouanet, Marc Ychou, Pascal Fenoglietto
BACKGROUND: Motion management is a major challenge in abdominal SBRT. We present our study of SBRT for liver tumors using intrafraction motion review (IMR) allowing simultaneous KV information and MV delivery to synchronize the beam during gated RapidArc treatment. MATERIALS AND METHODS: Between May 2012 and March 2015, 41 patients were treated by liver SBRT using gated RapidArc technique in a Varian Novalis Truebeam STx linear accelerator. PTV was created by expanding 5 mm from the ITV...
March 2017: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/28490984/evaluation-of-reproducibility-of-tumor-repositioning-during-multiple-breathing-cycles-for-liver-stereotactic-body-radiotherapy-treatment
#8
Ludovic Bedos, Olivier Riou, Norbert Aillères, Antoine Braccini, Jessica Molinier, Carmen Llacer Moscardo, David Azria, Pascal Fenoglietto
AIM: To evaluate the tumor repositioning during gated volumetric modulated arc therapy (VMAT) for liver stereotactic body radiotherapy(SBRT) treatment using implanted fiducial markers and intrafraction kilovoltage (kV) images acquired during dose delivery. MATERIALS AND METHODS: Since 2012, 47 liver cancer patients with implanted fiducial markers were treated using the gated VMAT technique with a Varian Truebeam STx linear accelerator. The fiducial markers were implanted inside or close to the tumor target before treatment simulation...
March 2017: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/28466444/a-pilot-study-on-geometrical-uncertainties-for-intra-ocular-cancers-in-radiotherapy
#9
Rachitha Antony, Alan Herschtal, Stephen Todd, Claire Phillips, Annette Haworth
A system for stabilising and monitoring eye movements for linac-based stereotactic radiotherapy associated with the mobile eye, the Eye Tracker, was developed. Whilst the Eye Tracker design is based on a previously reported system, the purpose of this study was to confirm that the modified version can be used with clinically acceptable treatment margins. We report the estimates of the margin required to account for inter- and intra-fraction eye motion based on data from 12 consecutive patients treated with the Eye Tracker system in place...
May 2, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28466154/spinal-cord-constraints-in-the-era-of-high-precision-radiotherapy-retrospective-analysis-of-62%C3%A2-spinal-paraspinal-lesions-with-possible-infringements-of-spinal-cord-constraints-within-a%C3%A2-minimal-volume
#10
Sebastian Zschaeck, Peter Wust, Reinhold Graf, Waldemar Wlodarczyk, Reinhard Schild, Alexander Henry Thieme, Mirko Weihrauch, Volker Budach, Pirus Ghadjar
OBJECTIVE: Current constraints aim to minimize the risk of radiation myelitis by the use of restrictive maximal spinal cord doses, commonly 50 Gy. However, several studies suggested that a dose-volume effect could exist. Based on these observations, we evaluated patients receiving potentially excessive doses to the spinal cord within minimal volumes. PATIENTS AND METHODS: Patients receiving radiotherapy between June 2010 and May 2015 using the Novalis(TM) (Varian, Palo Alto, CA, USA; Brainlab, Heimstetten, Germany) radiosurgery system were retrospectively analyzed...
May 2, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/28462867/monte-carlo-dose-calculation-in-presence-of-low-density-media-application-to-lung-sbrt-treated-during-dibh
#11
S Beilla, T Younes, L Vieillevigne, M Bardies, X Franceries, L Simon
PURPOSE: Commercial algorithms used in Radiotherapy include approximations that are generally acceptable. However their limits can be seen when confronted with small fields and low-density media. These conditions exist during the treatment of lung cancers with Stereotactic Body Radiation Therapy (SBRT) achieved with the "Deep Inspiration Breath Hold" (DIBH) technique. A Monte Carlo (MC) model of a linear accelerator was used to assess the performance of two algorithms (Varian Acuros and AAA) in these conditions...
April 24, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28462690/comparison-of-online-6-degree-of-freedom-image-registration-of-varian-truebeam-cone-beam-ct-and-brainlab-exactrac-x-ray-for-intracranial-radiosurgery
#12
Jun Li, Wenyin Shi, David Andrews, Maria Werner-Wasik, Bo Lu, Yan Yu, Adam Dicker, Haisong Liu
PURPOSE: The study was aimed to compare online 6 degree-of-freedom image registrations of TrueBeam cone-beam computed tomography and BrainLab ExacTrac X-ray imaging systems for intracranial radiosurgery. METHODS: Phantom and patient studies were performed on a Varian TrueBeam STx linear accelerator (version 2.5), which is integrated with a BrainLab ExacTrac imaging system (version 6.1.1). The phantom study was based on a Rando head phantom and was designed to evaluate isocenter location dependence of the image registrations...
June 2017: Technology in Cancer Research & Treatment
https://www.readbyqxmd.com/read/28436155/the-mobius-airo-mobile-ct-for-image-guided-proton-therapy-characterization-commissioning
#13
Jasmine A Oliver, Omar A Zeidan, Sanford L Meeks, Amish P Shah, Jason Pukala, Patrick Kelly, Naren R Ramakrishna, Twyla R Willoughby
PURPOSE: The purpose of this study was to characterize the Mobius AIRO Mobile CT System for localization and image-guided proton therapy. This is the first known application of the AIRO for proton therapy. METHODS: Five CT images of a Catphan(®) 504 phantom were acquired on the AIRO Mobile CT System, Varian EDGE radiosurgery system cone beam CT (CBCT), Philips Brilliance Big Bore 16 slice CT simulator, and Siemens SOMATOM Definition AS 20 slice CT simulator. DoseLAB software v...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28433524/an-analysis-of-knowledge-based-planning-for-stereotactic-body-radiation-therapy-of-the-spine
#14
Joseph J Foy, Robin Marsh, Randall K Ten Haken, Kelly C Younge, Matthew Schipper, Yilun Sun, Dawn Owen, Martha M Matuszak
PURPOSE: Planning for spine stereotactic body radiation therapy (SBRT) is time consuming, and differences in planner experience and technique result in discrepancies in plan quality between facilities. Here, knowledge-based planning is analyzed to determine if it may be effective in improving the quality and efficiency of spine SBRT planning. MATERIALS AND METHODS: Thirty-eight spine SBRT cases were collected from the University of Michigan database and inverse planned to deliver 3 10-Gy fractions to the planning target volume (PTV)...
March 2, 2017: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28432806/rapid-acceptance-testing-of-modern-linac-using-on-board-mv-and-kv-imaging-systems
#15
Sridhar Yaddanapudi, Bin Cai, Taylor Harry, Steven Dolly, Baozhou Sun, Hua Li, Keith Stinson, Camille Noel, Lakshmi Santanam, Todd Pawlicki, Sasa Mutic, S Murty Goddu
PURPOSE: The purpose of this study was to develop a novel process for using on-board MV and kV Electronic Portal Imaging Devices (EPIDs) to perform linac acceptance testing (AT) for two reasons: 1) to standardize the assessment of new equipment performance, and 2) to reduce the time to clinical use while reducing physicist workload. METHODS AND MATERIALS: In this study, Varian TrueBeam linacs equipped with amorphous silicon based EPID (aS1000) were used. The conventional set of AT tests and tolerances were used as a baseline guide...
April 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/28429391/technical-note-direct-measurement-of-continuous-tmr-data-with-a-1d-tank-and-automated-couch-movements
#16
Nels C Knutson, Matthew C Schmidt, Matthew D Belley, Ngoc Nguyen, H Harold Li, Erno Sajo, Michael Price
PURPOSE: Real-time dynamic control of the linear accelerator, couch, and imaging parameters during radiation delivery was investigated as a novel technique for acquiring tissue maximum ratio (TMR) data. METHODS: TrueBeam Developer Mode (Varian Medical Systems, Palo Alto, CA) was used to control the linear accelerator using the Extensible Markup Language (XML). A single XML file was used to dynamically manipulate the machine, couch, and imaging parameters during radiation delivery...
April 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28422421/results-of-a-10-year-survey-of-workload-for-10-treatment-vaults-at-a-high-throughput-comprehensive-cancer-center
#17
Ziad H Saleh, Jeho Jeong, Brian Quinn, James Mechalakos, Jean St Germain, Lawrence T Dauer
The workload for shielding purposes of modern linear accelerators (linacs) consists of primary and scatter radiation which depends on the dose delivered to isocenter (cGy) and leakage radiation which depends on the monitor units (MUs). In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays)...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28422381/comparison-of-multi-institutional-varian-probeam-pencil-beam-scanning-proton-beam-commissioning-data
#18
Ulrich W Langner, John G Eley, Lei Dong, Katja Langen
PURPOSE: Commissioning beam data for proton spot scanning beams are compared for the first two Varian ProBeam sites in the United States, at the Maryland Proton Treatment Center (MPTC) and Scripps Proton Therapy Center (SPTC). In addition, the extent to which beams can be matched between gantry rooms at MPTC is investigated. METHOD: Beam data for the two sites were acquired with independent dosimetry systems and compared. Integrated depth dose curves (IDDs) were acquired with Bragg peak ion chambers in a 3D water tank for pencil beams at both sites...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28410679/dual-energy-imaging-method-to-improve-the-image-quality-and-the-accuracy-of-dose-calculation-for-cone-beam-computed-tomography
#19
Kuo Men, Jianrong Dai, Xinyuan Chen, Minghui Li, Ke Zhang, Peng Huang
PURPOSE: To improve the image quality and accuracy of dose calculation for cone-beam computed tomography (CT) images through implementation of a dual-energy cone-beam computed tomography method (DE-CBCT), and evaluate the improvement quantitatively. METHODS: Two sets of CBCT projections were acquired using the X-ray volumetric imaging (XVI) system on a Synergy (Elekta, Stockholm, Sweden) system with 120kV (high) and 70kV (low) X-rays, respectively. Then, the electron density relative to water (relative electron density (RED)) of each voxel was calculated using a projection-based dual-energy decomposition method...
April 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28409334/investigation-of-x-ray-focal-spot-alignment-using-a-jig-of-novel-design
#20
Lockie Yuen, Cameron McLucas
The X-ray focal spot and the centre of the flattening filter should be placed as close as possible to the central axis (CAX) on a linear accelerator (linac) to produce a radially symmetric beam. The aim of this study is to devise a method to easily optimise the focal spot position of Varian linac photon beams generated with a flattening filter. A simple and robust jig was designed and built to be inserted into the largest electron applicator. Accessory and jaw position interlocks were overridden to enable photon beam operation...
April 13, 2017: Australasian Physical & Engineering Sciences in Medicine
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