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https://www.readbyqxmd.com/read/29223302/modeling-the-target-dose-fall-off-in-imrt-and-vmat-planning-techniques-for-cervical-sbrt
#1
A Brito Delgado, D Cohen, T Y Eng, D N Stanley, Z Shi, M Charlton, A N Gutiérrez
There has been growing interest in the use of stereotactic body radiotherapy (SBRT) technique for the treatment of cervical cancer. The purpose of this study was to characterize dose distributions as well as model the target dose fall-off for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques using 6 and 10 MV photon beam energies. Fifteen (n = 15) patients with non-bulky cervical tumors were planned in Pinnacle3 with a Varian Novalis Tx (HD120 MLC) using 6 and 10 MV photons with the following techniques: (1) IMRT with 10 non-coplanar beams (2) dual, coplanar 358° VMAT arcs (4° spacing), and (3) triple, non-coplanar VMAT arcs...
December 6, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/29214984/electron-beam-collimation-with-the-photon-mlc-for-standard-electron-treatments
#2
Silvan Mueller, Michael K Fix, Dominik Henzen, Daniel Frei, Daniel Frauchiger, Kristina Loessl, Marco F M Stampanoni, Peter Manser
Standard electron treatments are nowadays still performed using standard or molded patient-specific cut-outs placed in the electron applicator. Replacing cut-outs and electron applicators with the photon multileaf collimator (pMLC) for electron beam collimation would make standard electron treatments more efficient and would facilitate advanced treatment techniques like modulated electron radiotherapy (MERT) and mixed beam radiotherapy (MBRT). In this work, a multiple source Monte Carlo beam model for pMLC shaped electron beams commissioned at a source to surface distance (SSD) of 70 cm is extended for SSDs up to 100 cm and validated for several Varian treatment units with field sizes typically used for standard electron treatments...
December 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29211354/correlations-between-iron-content-in-knee-joint-tissues-and-chosen-indices-of-peripheral-blood-morphology
#3
Barbara Brodziak-Dopierała, Wojciech Roczniak, Agata Jakóbik-Kolon, Joanna Kluczka, Bogdan Koczy, Jerzy Kwapuliński, Magdalena Babuśka-Roczniak
BACKGROUND: Iron as a cofactor of enzymes takes part in the synthesis of the bone matrix. Severe deficiency of iron reduces the strength and mineral density of bones, whereas its excess may increase oxidative stress. In this context, it is essential to determine the iron content in knee joint tissues. OBJECTIVES: The study objective was to determine the level of iron in the tissues of the knee joint, i.e., in the femoral bone, tibia and meniscus. MATERIAL AND METHODS: Material for analysis was obtained during endoprosthetic surgery of the knee joint...
October 2017: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
https://www.readbyqxmd.com/read/29205177/evaluation-of-latent-variances-in-monte-carlo-dose-calculations-with-varian-truebeam-photon-phase-spaces-used-as-a-particle-source
#4
Eyad Ali Alhakeem, Sergei F Zavgorodni
<b>Purpose:</b> To evaluate the latent variance (LV) of Varian TrueBeam photon phase-space files (PSF) for open 10x10 cm<sup>2</sup> and small stereotactic fields and estimate the number of phase spaces required to be summed up in order to maintain sub-percent latent variance in Monte Carlo (MC) dose calculations. <b>Method:</b> BEAMnrc/DOSXYZnrc software was used to transport particles from Varian phase-space files (PSFA) through the secondary collimators. Transported particles were scored into another phase-space located under the jaws (PSFB), or transported further through the cone collimators and scored straight below, forming PSFC...
December 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29200920/a-monograph-of-the-australopacific-saprininae-coleoptera-histeridae
#5
Tomáš Lackner, Richard A B Leschen
The Australopacific Saprininae, containing twelve genera and forty species, are reviewed, illustrated and keyed to genera and species. Two new genera, Australopachylopusgen. n. (New Zealand, type species Saprinus lepidulus Broun, 1881) and Iridoprinusgen. n. (Australia, type species I. myrmecophilussp. n.) and four new species: Saprinus (Saprinus) rarus sp. n. (Australia), Saprinus (Saprinus) chathamensis sp. n. (Chatham Islands, New Zealand), Saprinus (Saprinus) pseudodetritus sp. n. (Chatham Islands, New Zealand) and Saprinus (Saprinus) pacificus sp...
2017: ZooKeys
https://www.readbyqxmd.com/read/29195142/quantification-of-glycerophospholipids-and-sphingomyelin-in-human-milk-and-infant-formula-by-high-performance-liquid-chromatography-coupled-with-mass-spectrometer-detector
#6
Isabelle Tavazzi, Patric Fontannaz, Le Ye Lee, Francesca Giuffrida
Phospholipids and sphingomyelin have a central role in infant nutrition, phospholipid acting as a nutrient carrier of long chain polyunsaturated fatty acids and sphingomyelin having an important role in cognitive function. However, analytical methods to precisely characterize and quantify these compounds in maternal milk are needed. Phospholipids and sphingomyelin were extracted using chloroform and methanol and separated on Polaris 3 Si column 250×2.0mm from Varian and analyzed by high performance liquid chromatography (HPLC) coupled with mass spectrometer detector (MS)...
November 7, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/29177897/attraction-of-three-mirid-predators-to-tomato-infested-by-both-the-tomato-leaf-mining-moth-tuta-absoluta-and-the-whitefly-bemisia-tabaci
#7
Diego B Silva, Vanda H P Bueno, Joop J A Van Loon, Maria Fernanda G V Peñaflor, José Maurício S Bento, Joop C Van Lenteren
Plants emit volatile compounds in response to insect herbivory, which may play multiple roles as defensive compounds and mediators of interactions with other plants, microorganisms and animals. Herbivore-induced plant volatiles (HIPVs) may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. We report here the first evidence of the attraction of three Neotropical mirid predators (Macrolophus basicornis, Engytatus varians and Campyloneuropsis infumatus) toward plants emitting volatiles induced upon feeding by two tomato pests, the leaf miner Tuta absoluta and the phloem feeder Bemisia tabaci, in olfactometer bioassays...
November 25, 2017: Journal of Chemical Ecology
https://www.readbyqxmd.com/read/29176059/multi-gpu-configuration-of-4d-intensity-modulated-radiation-therapy-inverse-planning-using-global-optimization
#8
Aaron Michael Hagan, Amit Sawant, Michael Folkerts, Arezoo Modiri
We report on the design, implementation and characterization of a multi-graphic processing unit (GPU) computational platform for higher-order optimization in radiotherapy treatment planning. In collaboration with a commercial vendor (Varian Medical Systems, Palo Alto, CA), a research prototype GPU-enabled Eclipse (V13.6) workstation was configured. The hardware consisted of dual 8-core xeon processors, 256 GB RAM and four NVIDIA Tesla K80 general purpose GPUs. We demonstrate the utility of this platform for large radiotherapy optimization problems through the development and characterization of a parallelized particle swarm optimization (PSO) four dimensional (4D) intensity modulated radiation therapy (IMRT) technique...
November 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29173922/on-the-re-calibration-process-in-radiochromic-film-dosimetry
#9
Carmen Ruiz-Morales, Juan Antonio Vera-Sánchez, Antonio González-López
PURPOSE: The accuracy and precision of the dose estimates obtained with radiochromic film dosimetry are investigated in a clinical environment. The improvement in the accuracy of dose estimates reached with corrective methods is analyzed. Two novel re-calibration algorithms for radiochromic film dosimetry are presented. METHODS: Two different EBT3 lots are evaluated in two different centres. They are calibrated in Varian linacs and read in two different EPSON scaners...
October 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29173907/a-software-platform-for-statistical-evaluation-of-patient-respiratory-patterns-in-radiation-therapy
#10
Leon Dunn, John Kenny
AIM: The aim of this work was to design and evaluate a software tool for analysis of a patient's respiration, with the goal of optimizing the effectiveness of motion management techniques during radiotherapy imaging and treatment. MATERIALS AND METHODS: A software tool which analyses patient respiratory data files (.vxp files) created by the Varian Real-Time Position Management System (RPM) was developed to analyse patient respiratory data. The software, called RespAnalysis, was created in MATLAB and provides four modules, one each for determining respiration characteristics, providing breathing coaching (biofeedback training), comparing pre and post-training characteristics and performing a fraction-by-fraction assessment...
October 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29172266/dosimetric-validation-of-volumetric-modulated-arc-therapy-vmat-using-aapm-tg-119-benchmark-plans-in-an-upgraded-clinac-2100cd-for-flattening-filter-free-fff-photon-beams
#11
Ashokkumar Sangaiah, K M Ganesh, K Ramalingam, K Karthikeyan, N Jagadheeskumar
Background: Recently we have upgraded our Varian Clinac 2100CD with a 6MV FFF beam, this upgrade being the first of its kind in our country. Even though the dosimetric characteristics of FFF beams have been reported both in experimental and Monte Carlo studies, application in planning and delivery is complex. The aim of this study was to validate the commissioning of upgraded FFF beams dosimetrically using AAPM TG-119 bench mark plans for VMAT and to make a comparison with IMRT plans for both flattened filtered and FFF beams...
November 26, 2017: Asian Pacific Journal of Cancer Prevention: APJCP
https://www.readbyqxmd.com/read/29164632/characterization-of-nanodot-optically-stimulated-luminescence-detectors-and-high-sensitivity-mcp-n-thermoluminescent-detectors-in-the-40-300-kvp-energy-range
#12
Yannick Poirier, Svetlana Kuznetsova, Jose Eduardo Villarreal-Barajas
PURPOSE: To investigate empirically the energy dependence of the detector response of two in-vivo luminescence detectors, LiF:Mg,Cu,P (MCP-N) high-sensitivity TLDs and Al2 O3 :C OSLDs, in the 40-300-kVp energy range in the context of in-vivo surface dose measurement. As these detectors become more prevalent in clinical and pre-clinical in-vivo measurements, knowledge of the variation of the empirical dependence of the measured response of these detectors across a wide spectrum of beam qualities is important...
November 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/29156098/technical-note-penumbral-width-trimming-in-solid-lung-dose-profiles-for-0-9-t-and-1-5-t-mri-linac-prototypes
#13
Sarah J Alnaghy, Jarrad Begg, Trent Causer, Thahabah Alharthi, Laura Glaubes, Bin Dong, Armia George, Lois Holloway, Peter Metcalfe
PURPOSE: Longitudinal magnetic fields narrow beam penumbra and tighten lateral spread of secondary electrons in air cavities, including lung tissue. Gafchromic(®) EBT3 film was used to investigate differences between penumbra in solid water and solid lung, without a magnetic field (0 T) and with two field strengths (0.9 T and 1.5 T). METHODS: The first prototype of the Australian MRI-linac consisted of a 1.5 T Siemens Sonata MRI and Varian industrial linatron (nominal 4 MV)...
November 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/29154259/evaluation-of-coefficients-to-derive-organ-and-effective-doses-from-cone-beam-ct-cbct-scans-a-monte-carlo-study
#14
Abdullah Abuhaimed, Colin J Martin
Regular imaging is used throughout image guided radiation therapy (IGRT) to improve treatment delivery. In order for treatment procedures to be optimized, the doses delivered by imaging exposures should be taken into account. CT dosimetry methods based on the CT dose index (CTDI), measured with a 100 mm long pencil ionization chamber (CTDI<sub>100</sub>) in standard phantoms, are not designed for the cone beam CT (CBCT) imaging systems used in radiotherapy, therefore a modified version has been proposed for CBCT by the International Electrotechnical Commission (CTDI<sub>IEC</sub>)...
November 20, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29152898/tolerance-levels-of-ct-number-to-electron-density-table-for-photon-beam-in-radiotherapy-treatment-planning-system
#15
Minoru Nakao, Shuichi Ozawa, Kiyoshi Yamada, Katsunori Yogo, Fumika Hosono, Masahiro Hayata, Akito Saito, Kentaro Miki, Takeo Nakashima, Yusuke Ochi, Daisuke Kawahara, Yoshiharu Morimoto, Toru Yoshizaki, Hiroshige Nozaki, Kosaku Habara, Yasushi Nagata
The accuracy of computed tomography number to electron density (CT-ED) calibration is a key component for dose calculations in an inhomogeneous medium. In a previous work, it was shown that the tolerance levels of CT-ED calibration became stricter with an increase in tissue thickness and decrease in the effective energy of a photon beam. For the last decade, a low effective energy photon beam (e.g., flattening-filter-free (FFF)) has been used in clinical sites. However, its tolerance level has not been established yet...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29152846/on-the-geud-biological-optimization-objective-for-organs-at-risk-in-photon-optimizer-of-eclipse-treatment-planning-system
#16
Antonella Fogliata, Stephen Thompson, Antonella Stravato, Stefano Tomatis, Marta Scorsetti, Luca Cozzi
Inverse planning optimization using biologically based objectives is becoming part of the intensity modulated optimization process. The performances and efficacy of the biologically based gEUD (generalized Equivalent Uniform Dose) objective implemented in the Photon Optimizer (PO) of Varian Eclipse treatment planning system have been here analyzed. gEUD is associated with the parameter a that accounts for the seriality of a structure, being higher for more serial organs. The PO was used to optimize volumetric modulated arc therapy (VMAT) plans on a virtual homogeneous cylindrical phantom presenting a target and an organ at risk (OAR)...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29134472/real-time-wireless-tumor-tracking-during-breast-conserving-surgery
#17
Natasja Janssen, Roeland Eppenga, Marie-Jeanne Vrancken Peeters, Frederieke van Duijnhoven, Hester Oldenburg, Jos van der Hage, Emiel Rutgers, Jan-Jakob Sonke, Koert Kuhlmann, Theo Ruers, Jasper Nijkamp
PURPOSE: To evaluate a novel surgical navigation system for breast conserving surgery (BCS), based on real-time tumor tracking using the Calypso[Formula: see text] 4D Localization System (Varian Medical Systems Inc., USA). Navigation-guided breast conserving surgery (Nav-BCS) was compared to conventional iodine seed-guided BCS ([Formula: see text]I-BCS). METHODS: Two breast phantom types were produced, containing spherical and complex tumors in which wireless transponders (Nav-BCS) or a iodine seed ([Formula: see text]I-BCS) were implanted...
November 13, 2017: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/29125224/normalize-the-response-of-epid-in-pursuit-of-linear-accelerator-dosimetry-standardization
#18
Bin Cai, S Murty Goddu, Sridhar Yaddanapudi, Douglas Caruthers, Jie Wen, Camille Noel, Sasa Mutic, Baozhou Sun
Normalize the response of electronic portal imaging device (EPID) is the first step toward an EPID-based standardization of Linear Accelerator (linac) dosimetry quality assurance. In this study, we described an approach to generate two-dimensional (2D) pixel sensitivity maps (PSM) for EPIDs response normalization utilizing an alternative beam and dark-field (ABDF) image acquisition technique and large overlapping field irradiations. The automated image acquisition was performed by XML-controlled machine operation and the PSM was generated based on a recursive calculation algorithm for Varian linacs equipped with aS1000 and aS1200 imager panels...
November 10, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29114618/orthogonal-image-pairs-coupled-with-osms-for-noncoplanar-beam-angle-intracranial-single-isocenter-srs-treatments-with-multiple-targets-on-the-varian-edge-radiosurgery-system
#19
Jasmine A Oliver, Patrick Kelly, Sanford L Meeks, Twyla R Willoughby, Amish P Shah
Purpose: To characterize the accuracy of noncoplanar image guided radiation therapy with the Varian Edge radiosurgery system for intracranial stereotactic radiosurgery (SRS) treatments by assessing the accuracy of kV/kV orthogonal pair registration with Optical Surface Monitoring System (OSMS) monitoring relative to cone beam computed tomography (CT). Methods and materials: A Computerized Imaging Reference System head phantom and Encompass SRS Immobilization System were used to determine collision-free space for orthogonal image pairs (kV/kV) for couch rotations (CRs) of 45°, 30°, 15°, 345°, 330°, and 315°...
July 2017: Advances in Radiation Oncology
https://www.readbyqxmd.com/read/29109817/diagnosis-of-the-diatom-community-upon-biofilm-development-on-stainless-steels-in-natural-freshwater
#20
Caroline Richard, Smita Mitbavkar, Jessem Landoulsi
This paper reports the development of biofilms on stainless steels (SS) upon exposure in a natural freshwater ecosystem for about six months and focuses on the composition of diatom populations. By using environmental scanning electron microscopy (ESEM) technique, we provide a detailed description regarding diatom identification at species level as well as their main characteristics, including type, morphology, ability to form colony, and motility. Results reveal the presence of both prostrate (initial colonizers) and stalked (late colonizers) forms...
2017: Scanning
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