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https://www.readbyqxmd.com/read/28610696/use-of-ptw-microdiamond-for-relative-dosimetry-of-unflattened-photon-beams
#1
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
#2
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
#3
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
#4
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
#5
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...
June 5, 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
#6
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
#7
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
#8
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...
May 22, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28529045/influence-of-preoperative-imaging-on-fibula-free-flap-harvesting
#9
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
#10
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
https://www.readbyqxmd.com/read/28489347/measurement-of-the-density-of-engineered-silver-nanoparticles-using-centrifugal-fff-tem-and-single-particle-icp-ms
#11
Soheyl Tadjiki, Manuel David Montaño, Shoeleh Assemi, Angela Barber, James Ranville, Ronald Beckett
A methodology has been developed to measure nanoparticle mass and density, by combining centrifugal field-flow fractionation (CeFFF; more commonly called sedimentation FFF or SdFFF) and transmission electron microscopy (TEM). Particle effective mass obtained from CeFFF retention data and particle size obtained from the TEM images were used to calculate the nanoparticle density. The method was initially applied to measure the density of monodispersed polystyrene latex nanoparticles. Measured densities for latex nanoparticles of 160-300 nm in diameter were in the range of 1041-1063 kg m(-3) with standard deviations of 0...
June 6, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28479873/comparison-of-surface-dose-delivered-by-7%C3%A2-mv-unflattened-and-6%C3%A2-mv-flattened-photon-beams
#12
Ashokkumar Sigamani, Arunai Nambiraj
AIM: The purpose of this study is to determine the central-axis dose in the buildup region and the surface dose delivered by a 6 MV flattened photon beam (6 MV-FB) and a higher energy unflattened (7 MV-FFF) therapeutic photon beam for different-sized square fields with open fields and modifying filters. MATERIALS AND METHODS: The beams are produced by a Siemens Artiste linear accelerator with a NACP-02 ionization chamber and the dose is measured by using GafChromic film and two different, commonly used, dosimeters: a p-type photon semiconductor dosimeter (PFD) and a cylindrical ionization chamber (CC13)...
May 2017: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/28453004/implant-utilization-and-time-to-prosthetic-rehabilitation-in-conventional-and-advanced-fibular-free-flap-reconstruction-of-the-maxilla-and-mandible
#13
Richelle Chuka, Wael Abdullah, Jana Rieger, Suresh Nayar, Hadi Seikaly, Martin Osswald, Johan Wolfaardt
PURPOSE: Precisely designed jaw reconstruction rehabilitation (JRR) is important to the integrity of the jaw structure and oral functions. Advanced three-dimensional (3D) digital surgical design and simulation (SDS) techniques have the potential to reduce time to reconstructive and dental treatment completion, thereby promoting early functional oral rehabilitation. This study investigated the use of SDS in JRR procedures. MATERIALS AND METHODS: A retrospective chart review was conducted on adult head and neck tumor (HNT) participants who completed JRR treatment with a fibular free flap (FFF) reconstruction...
May 2017: International Journal of Prosthodontics
https://www.readbyqxmd.com/read/28447313/stereotactic-ablative-radiation-therapy-for-brain-metastases-with-volumetric-modulated-arc-therapy-and-flattening-filter-free-delivery-feasibility-and-early-clinical-results
#14
Alba Fiorentino, Niccolò Giaj-Levra, Umberto Tebano, Rosario Mazzola, Francesco Ricchetti, Sergio Fersino, Gioacchino Di Paola, Dario Aiello, Ruggero Ruggieri, Filippo Alongi
AIM: For selected patients with brain metastases (BMs), the role of stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SFRT) is well recognized. The recent introduction of flattening filter free (FFF) delivery during linac-based SRS or SFRT allows shorter beam-on-time, improving patients' comfort and facility workflow. Nevertheless, limited experiences evaluated the impact of FFF linac-based SRS and SFRT in BMs treatment. Aim of the current study was to analyze SRS/SFRT linac-based FFF delivery for BMs in terms of dosimetric and early clinical results...
April 26, 2017: La Radiologia Medica
https://www.readbyqxmd.com/read/28405104/structural-shielding-design-of-a-6-mv-flattening-filter-free-linear-accelerator-indian-scenario
#15
Bibekananda Mishra, T Palani Selvam, P K Dash Sharma
Detailed structural shielding of primary and secondary barriers for a 6 MV medical linear accelerator (LINAC) operated with flattening filter (FF) and flattening filter free (FFF) modes are calculated. The calculations have been carried out by two methods, one using the approach given in National Council on Radiation Protection (NCRP) Report No. 151 and the other based on the monitor units (MUs) delivered in clinical practice. Radiation survey of the installations was also carried out. NCRP approach suggests that the primary and secondary barrier thicknesses are higher by 24% and 26%...
January 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28374591/diversity-and-hierarchy-in-supramolecular-assemblies-of-triphenylalanine-from-laminated-helical-ribbons-to-toroids
#16
Enric Mayans, Jordi Casanovas, Ana M Gil, Ana I Jiménez, Carlos Cativiela, Jordi Puiggalí, Carlos Alemán
Microstructures from small phenylalanine-based peptides have attracted great attention lately because these compounds are considered to be a new class of tunable materials. In spite of the extensive studies on uncapped diphenylalanine and tetraphenylalanine peptides, studies on the self-assembly of uncapped triphenylananine (FFF) are very scarce and nonsystematic. In this work, we demonstrate that FFF assemblies can organize in a wide number of well-defined supramolecular structures, which include laminated helical-ribbons, leaflike dendrimers, doughnut-, needle-, and flower-shapes...
April 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28336006/influence-of-the-integral-quality-monitor-transmission-detector-on-high-energy-photon-beams-a-multi-centre-study
#17
Bozidar Casar, Marlies Pasler, Sonja Wegener, David Hoffman, Cinzia Talamonti, Jianguo Qian, Ignasi Mendez, Denis Brojan, Bruce Perrin, Martijn Kusters, Richard Canters, Stefania Pallotta, Primoz Peterlin
PURPOSE: The influence of the Integral Quality Monitor (IQM) transmission detector on photon beam properties was evaluated in a preclinical phase, using data from nine participating centres: (i) the change of beam quality (beam hardening), (ii) the influence on surface dose, and (iii) the attenuation of the IQM detector. METHODS: For 6 different nominal photon energies (4 standard, 2 FFF) and square field sizes from 1×1cm(2) to 20×20cm(2), the effect of IQM on beam quality was assessed from the PDD20,10 values obtained from the percentage dose depth (PDD) curves, measured with and without IQM in the beam path...
March 20, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28300376/moving-gpu-opencl-based-monte-carlo-dose-calculation-toward-clinical-use-automatic-beam-commissioning-and-source-sampling-for-treatment-plan-dose-calculation
#18
Zhen Tian, Yongbao Li, Nima Hassan-Rezaeian, Steve B Jiang, Xun Jia
We have previously developed a GPU-based Monte Carlo (MC) dose engine on the OpenCL platform, named goMC, with a built-in analytical linear accelerator (linac) beam model. In this paper, we report our recent improvement on goMC to move it toward clinical use. First, we have adapted a previously developed automatic beam commissioning approach to our beam model. The commissioning was conducted through an optimization process, minimizing the discrepancies between calculated dose and measurement. We successfully commissioned six beam models built for Varian TrueBeam linac photon beams, including four beams of different energies (6 MV, 10 MV, 15 MV, and 18 MV) and two flattening-filter-free (FFF) beams of 6 MV and 10 MV...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300374/efficient-independent-planar-dose-calculation-for-fff-imrt-qa-with-a-bivariate-gaussian-source-model
#19
Feifei Li, Ji-Yeon Park, Brendan Barraclough, Bo Lu, Jonathan Li, Chihray Liu, Guanghua Yan
The aim of this study is to perform a direct comparison of the source model for photon beams with and without flattening filter (FF) and to develop an efficient independent algorithm for planar dose calculation for FF-free (FFF) intensity-modulated radiotherapy (IMRT) quality assurance (QA). The source model consisted of a point source modeling the primary photons and extrafocal bivariate Gaussian functions modeling the head scatter, monitor chamber backscatter, and collimator exchange effect. The model parameters were obtained by minimizing the difference between the calculated and measured in-air output factors (Sc )...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297462/surface-dose-variations-in-6-and-10-mv-flattened-and-flattening-filter-free-fff-photon-beams
#20
Jason Cashmore
As the use of linear accelerators operating in flattening filter-free (FFF) modes becomes more widespread, it is important to have an understanding of the surface doses delivered to patients with these beams. Flattening filter removal alters the beam quality and relative contributions of low-energy X-rays and contamination electrons in the beam. Having dosimetric data to describe the surface dose and buildup regions under a range of conditions for FFF beams is important if clinical decisions are to be made...
September 2016: Journal of Applied Clinical Medical Physics
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