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https://www.readbyqxmd.com/read/28797664/investigation-of-zinc-oxide-particles-in-cosmetic-products-by-means-of-centrifugal-and-asymmetrical-flow-field-flow-fractionation
#1
Vanessa Sogne, Florian Meier, Thorsten Klein, Catia Contado
The dimensional characterization of insoluble, inorganic particles, such as zinc oxide ZnO, dispersed in cosmetic or pharmaceutical formulations, is of great interest considering the current need of declaring the possible presence of nanomaterials on the label of commercial products. This work compares the separation abilities of Centrifugal- and Asymmetrical Flow Field-Flow Fractionation techniques (CF3 and AF4, respectively), equipped with UV-vis, MALS and DLS detectors, in size sorting ZnO particles, both as pristine powders and after their extraction from cosmetic matrices...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28771143/equivalent-uniform-square-field-sizes-of-flattening-filter-free-photon-beams
#2
Wolfgang Lechner, Peter Kuess, Dietmar Georg, Hugo Palmans
Various types of treatment units such as CyberKnife, TomoTherapy and C-arm linear accelerators (LINACs) are operated using flattening filter free (FFF) photon beams. Their reference dosimetry, however, is currently based on codes of practice that provide data which were primarily developed and tested for high-energy photon beams with flattering filter (WFF). The aim of this work was to introduce equivalent uniform square field sizes of FFF beams to serve as a basis of a unified reference dosimetry procedure applicable to all aforementioned FFF machines...
August 3, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28736809/dose-evaluation-of-grid-therapy-using-a-6-mv-flattening-filter-free-fff-photon-beam-a-monte-carlo-study
#3
Immaculada Martínez-Rovira, Josep Puxeu, Yolanda Prezado
PURPOSE: Spatially fractionated radiotherapy is a strategy to overcome the main limitation of radiotherapy, i.e., the restrained normal tissue tolerances. A well-known example is Grid Therapy, which is currently performed at some hospitals using megavoltage photon beams delivered by Linacs. Grid Therapy has been successfully used in the management of bulky abdominal tumors with low toxicity. The aim of this work is to evaluate whether an improvement in therapeutic index in Grid Therapy can be obtained by implementing it in a flattening filter-free (FFF) Linac...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28712715/split-vmat-technique-to-control-the-expiratory-breath-hold-time-in-liver-stereotactic-body-radiation-therapy
#4
Yen Hwa Lin, Shuichi Ozawa, Hideharu Miura, Katsunori Yogo, Takeo Nakashima, Kentaro Miki, Shintaro Tsuda, Yusuke Ochi, Daisuke Kawahara, Tomoki Kimura, Akito Saito, Yasushi Nagata
PURPOSE: In this study, we demonstrate the feasibility of using split-arcs in volumetric modulated arc therapy (VMAT), tailored for expiratory breath-hold in stereotactic body radiation therapy (SBRT) for liver tumors. We compare it with three-dimensional conformal radiation therapy (3D-CRT) and continuous-VMAT, for ten randomly selected hepatocellular carcinoma cases. METHODS: Four coplanar and four non-coplanar beams were used for the 3D-CRT plans. A pair of partial arcs, chosen using a back-and-forth rotating motion, were used for the continuous-VMAT plans...
July 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28711480/commissioning-of-small-field-size-radiosurgery-cones-in-a-6-mv-flattening-filter-free-beam
#5
Juan Diego Azcona, Benigno Barbés, Verónica Morán, Javier Burguete
This study aimed to describe the commissioning of small field size radiosurgery cones in a 6-MV flattening filter free (FFF) beam and report our measured values. Four radiosurgery cones of diameters 5, 10, 12.5, and 15 mm supplied by Elekta Medical were commissioned in a 6-MV FFF beam from an Elekta Versa linear accelerator. The extraction of a reference signal for measuring small fields in scanning mode is challenging. A transmission chamber was attached to the lower part of the collimators and used for percentage depth dose (PDD) and profile measurements in scanning mode with a stereotactic diode...
July 12, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28711479/identification-of-the-suitable-leaf-margin-for-liver-stereotactic-body-radiotherapy-with-flattening-filter-free-beams
#6
Toshiyuki Ogata, Hideki Nishimura, Hiroshi Mayahara, Kazuyuki Uehara, Takanobu Okayama
The purpose of this study is to identify the suitable leaf margin for liver stereotactic body radiotherapy (SBRT) with flattening filter-free (FFF) beams, as compared with that with flattening filter (FF) beams. SBRT treatment planning for 10 patients with liver cancer was performed using 10-MV FFF and FF beams obtained from a Varian TrueBeam (Varian Medical Systems, Palo Alto, CA) linear accelerator. Each plan was generated with the leaf margin to the planning target volume (PTV) ranging from -3 to 5 mm...
July 12, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28706351/beam-characterization-of-10-mv-photon-beam-from-medical-linear-accelerator-without-flattening-filter
#7
Tomohiro Shimozato, Yuichi Aoyama, Takuma Matsunaga, Katsuyoshi Tabushi
AIM: This work investigated the dosimetric properties of a 10-MV photon beam emitted from a medical linear accelerator (linac) with no flattening filter (FF). The aim of this study is to analyze the radiation fluence and energy emitted from the flattening filter free (FFF) linac using Monte Carlo (MC) simulations. MATERIALS AND METHODS: The FFF linac was created by removing the FF from a linac in clinical use. Measurements of the depth dose (DD) and the off-axis profile were performed using a three-dimensional water phantom with an ionization chamber...
April 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28688686/hardware-complications-in-oromandibular-defects-comparing-scapular-and-fibular-based-free-flap-reconstructions
#8
Gordon F Z Tsang, Han Zhang, Christopher Yao, Mirko Kolarski, Patrick J Gullane, Jonathan C Irish, Dale H Brown, Douglas B Chepeha, David P Goldstein, Ralph W Gilbert, John R de Almeida
BACKGROUND: Despite improvements in surgical technique and technology, hardware complications occur relatively frequently. This study analyzes hardware complications in patients undergoing oromandibular reconstruction using scapular (SFF) or fibular (FFF) free flaps. METHODS: Retrospective data for 178 patients was obtained (1999-2014) at University Hospital Network (Toronto, Canada). Univariable and multivariable analyses were performed to identify risk factors for hardware complications...
August 2017: Oral Oncology
https://www.readbyqxmd.com/read/28679448/simultaneous-integrated-boost-therapy-of-carcinoma-of-the-hypopharynx-larynx-with-and-without-flattening-filter-a-treatment-planning-and-dosimetry-study
#9
Barbara Dobler, Tina Obermeier, Matthias G Hautmann, Amine Khemissi, Oliver Koelbl
BACKGROUND: The aim of this study was to investigate if the flattening filter free (FFF) irradiation mode of a linear accelerator (linac) is advantageous as compared to the flat beam (FF) irradiation mode in intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for carcinoma of the hypopharynx / larynx. METHODS: Four treatment plans were created for each of 10 patients for an Elekta Synergy linac with Agility collimating device, a dual arc VMAT and a nine field step and shoot IMRT each with and without flattening filter...
July 5, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28657114/development-of-a-flattening-filter-free-multiple-source-model-for-use-as-an-independent-monte-carlo-dose-calculation-quality-assurance-tool-for-clinical-trials
#10
Austin M Faught, Scott E Davidson, Richard Popple, Stephen F Kry, Carol Etzel, Geoffrey S Ibbott, David S Followill
PURPOSE: The Imaging and Radiation Oncology Core - Houston (IROC-H) Quality Assurance Center (formerly the Radiological Physics Center) has reported varying levels of compliance from their anthropomorphic phantom auditing program. IROC-H studies have suggested that one source of disagreement between institution submitted calculated doses and measurement is the accuracy of the institution's treatment planning system dose calculations and heterogeneity corrections used. In order to audit this step of the radiation therapy treatment process, an independent dose calculation tool is needed...
June 28, 2017: Medical Physics
https://www.readbyqxmd.com/read/28610696/use-of-ptw-microdiamond-for-relative-dosimetry-of-unflattened-photon-beams
#11
Giacomo Reggiori, Antonella Stravato, Maria Pimpinella, Francesca Lobefalo, Vanessa De Coste, Antonella Fogliata, Pietro Mancosu, Fiorenza De Rose, Valentina Palumbo, Marta Scorsetti, Stefano Tomatis
PURPOSE: The increasing interest in SBRT treatments encourages the use of flattening filter free (FFF) beams. Aim of this work was to evaluate the performance of the PTW60019 microDiamond detector under 6MV and 10MVFFF beams delivered with the EDGE accelerator (Varian Medical System, Palo Alto, USA). A flattened 6MV beam was also considered for comparison. METHODS: Short term stability, dose linearity and dose rate dependence were evaluated. Dose per pulse dependence was investigated in the range 0...
June 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28601563/biophysical-characterization-of-influenza-a-virions
#12
Arun Parupudi, Flaviu Gruia, Samuel A Korman, Sonia Dragulin-Otto, Kuldip Sra, Richard L Remmele, Jared S Bee
Antigenic drift of the influenza A virus requires that vaccine production is targeted to the strains circulating each year. Live-attenuated influenza A vaccine manufacturing is used to produce intact virions with the surface antigens of the circulating strains. Influenza A typically contains a large percentage (>90%) of non-infective virions. The ribonucleoprotein (RNP) content, virion structure, and aggregation are factors that are thought to have an impact on infectivity. However, these factors are difficult to study because of the intrinsic variability in virion size, shape and overall structural integrity...
June 8, 2017: Journal of Virological Methods
https://www.readbyqxmd.com/read/28595775/surface-dose-measurements-in-and-out-of-field-implications-for-breast-radiotherapy-with-megavoltage-photon-beams
#13
Peta Lonski, Prabhakar Ramachandran, Rick Franich, Tomas Kron
This study examines the difference in surface dose between flat and flattening filter free (FFF) photon beams in the context of breast radiotherapy. The surface dose was measured for 6MV, 6MV FFF, 10MV, 10MV FFF and 18MV photon beams using a thin window ionisation chamber for various field sizes. Profiles were acquired to ascertain the change in surface dose off-axis. Out-of-field measurements were included in a clinically representative half beam block tangential breast field. In the field centres of FFF beams the surface dose was found to be increased for small fields and decreased for large fields compared to flat beams...
June 5, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28587007/clinical-outcomes-of-stereotactic-body-radiation-therapy-using-flattening-filter-free-fff-in-early-non-small-cell-lung-cancers-and-metastatic-lung-cancers
#14
S Kitpanit, A Songthong, C Chakkabat, N Amornwichet, P Alisanant, C Nantavithya, C Lertbutsayanukul, K Shotelersuk, C Khorprasert, D Kannarunimit
No abstract text is available yet for this article.
May 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28580621/functional-outcomes-of-fasciocutaneous-free-flap-and-pectoralis-major-flap-for-salvage-total-laryngectomy
#15
Sally Nguyen, François Thuot
BACKGROUND: Pectoralis major muscle flaps (PMMFs) and fasciocutaneous free flaps (FFFs) are commonly used for reconstruction of the surgical defect after salvage total laryngectomy. This study compared swallowing function in patients who underwent reconstruction with either PMMF or FFF. METHODS: This study was based on a retrospective cohort of patients treated at the CHU de Québec between January 2000 and March 2015. Demographics, chemoradiation data, surgical protocol, pathologic results, complications, evolution, esophageal dilation, diet intake, and feeding tube dependence were documented...
September 2017: Head & Neck
https://www.readbyqxmd.com/read/28574219/optimization-of-the-dosimetric-leaf-gap-for-use-in-planning-vmat-treatments-of-spine-sabr-cases
#16
Nigel D Middlebrook, Bess Sutherland, Tanya Kairn
The dosimetric leaf gap (DLG) is a beam configuration parameter used in the Varian Eclipse treatment planning system, to model the effects of rounded MLC leaf ends. Measuring the DLG using the conventional sliding-slit technique has been shown to be produce questionable results for some volumetric modulated arc therapy (VMAT) treatments. This study therefore investigated the use of radiochromic film measurements to optimize the DLG specifically for the purpose of producing accurate VMAT plans using a flattening-filter-free (FFF) beam, for use in treating vertebral targets using a stereotactic (SABR, also known as SBRT) fractionation schedule...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574211/comparison-of-the-recommendations-of-the-aapm-tg-51-and-tg-51-addendum-reference-dosimetry-protocols
#17
Travis J McCaw, Min-Sig Hwang, Si Young Jang, M Saiful Huq
This work quantified differences between recommendations of the TG-51 and TG-51 addendum reference dosimetry protocols. Reference dosimetry was performed for flattened photon beams with nominal energies of 6, 10, 15, and 23 MV, as well as flattening-filter free (FFF) beam energies of 6 and 10 MV, following the recommendations of both the TG-51 and TG-51 addendum protocols using both a Farmer(®) ionization chamber and a scanning ionization chamber with calibration coefficients traceable to absorbed dose-to-water (Dw ) standards...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28546105/ex-vivo-skin-permeation-and-penetration-of-nonivamide-from-and-in-vivo-skin-tolerability-of-film-forming-formulations-containing-porous-silica
#18
Rouven Heck, Milica Ž Lukić, Snežana D Savić, Rolf Daniels, Dominique J Lunter
AIM: The purpose of this study was to evaluate skin permeation and penetration of nonivamide which has been formulated in novel film-forming formulations (FFFs). These formulations aim to prolong the availability of capsaicinoids which are used in long-term treatment of chronic pruritus. METHODS: An oily solution of nonivamide was loaded into porous silica particles which then were suspended in an aqueous dispersion of a sustained release polymer. Permeation and penetration experiments were performed ex vivo with postauricular porcine skin using modified Franz diffusion cells...
August 30, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28529045/influence-of-preoperative-imaging-on-fibula-free-flap-harvesting
#19
R Gryseleyn, M Schlund, P Pigache, T Wojcik, G Raoul, J Ferri
INTRODUCTION: The fibula free flap (FFF) is the gold standard for the reconstruction of large maxillofacial defects. Magnetic resonance angiography (MRA) seems to supersede digital subtraction angiography (DSA) as the reference in preoperative evaluation, being non-invasive and having equivalent diagnostic results. The aim of this study was to assess the impact of preoperative MRA versus DSA on the viability of FFF and its success rate. MATERIAL AND METHODS: A total of 216 patients, who underwent mandibular or maxillary FFF reconstruction from January 1995 to January 2011, were retrospectively included in the study...
May 18, 2017: Journal of Stomatology, Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/28521451/dosimetric-comparison-of-intensity-modulated-radiation-therapy-and-volumetric-modulated-arc-therapy-plans-for-the-treatment-of-glioma-using-flattening-filter-free-and-flattening-filter-modes
#20
Dandan Xu, Fei Jia, Guowen Li, Hongfei Li
In the present study, the dose verification between 6X and 6X flattening filter-free (FFF) in intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) was compared, and the advantages and disadvantages of different radiotherapy plans were evaluated. All four plans achieved comparable heterogeneity and conformity indices. For frontal tumor, VMAT demonstrated more improved sparing of the brainstem compared with the IMRT (P=0.045); while in the model of FFF, the Dmax of eye lens was significantly reduced by 16-21% (P<0...
May 2017: Oncology Letters
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