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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
#1
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
#2
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
#3
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
#4
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...
May 17, 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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28297340/dosimetric-properties-of-equivalent-quality-flattening-filter-free-fff-and-flattened-photon-beams-of-versa-hd-linear-accelerator
#14
Mukesh N Meshram, Srimanta Pramanik, C P Ranjith, Saravana K Gopal, Rishabh Dobhal
This study presents the basic dosimetric properties of photon beams of a Versa HD linear accelerator (linac), which is capable of delivering flattening filter-free (FFF) beams with a beam quality equivalent to the corresponding flattened beams based on comprehensive beam data measurement. The analyzed data included the PDDs, profiles, penumbra, out-of-field doses, surface doses, output factors, head and phantom scatter factors, and MLC transmissions for both FFF and flattened beams of 6 MV and 10 MV energy from an Elekta Versa HD linac...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297327/small-field-detector-correction-factors-effects-of-the-flattening-filter-for-elekta-and-varian-linear-accelerators
#15
Madelaine K Tyler, Paul Z Y Liu, Christopher Lee, David R McKenzie, Natalka Suchowerska
Flattening filter-free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization chambers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297306/epid-based-dosimetry-to-verify-imrt-planar-dose-distribution-for-the-as1200-epid-and-fff-beams
#16
Narges Miri, Peter Keller, Benjamin J Zwan, Peter Greer
We proposed to perform a basic dosimetry commissioning on a new imager system, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter-free (FFF) beams, then to develop an image-based quality assurance (QA) model for verification of the system delivery accuracy for intensity-modulated radiation therapy (IMRT) treatments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297295/a-comparison-of-methods-for-monitoring-photon-beam-energy-constancy
#17
Song Gao, Peter A Balter, Mark Rose, William E Simon
In extension of a previous study, we compared several photon beam energy metrics to determine which was the most sensitive to energy change; in addition to those, we accounted for both the sensitivity of each metric and the uncertainty in determining that metric for both traditional flattening filter (FF) beams (4, 6, 8, and 10 MV) and for flattening filter-free (FFF) beams (6 and 10 MV) on a Varian TrueBeam. We examined changes in these energy metrics when photon energies were changed to ±5% and ±10% from their nominal energies: 1) an attenuation-based metric (the percent depth dose at 10 cm depth, PDD(10)) and, 2) profile-based metrics, including flatness (Flat) and off-axis ratios (OARs) measured on the orthogonal axes or on the diagonals (diagonal normalized flatness, FDN)...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297290/gafchromic-ebt-xd-film-dosimetry-characterization-in-high-dose-volumetric-modulated-arc-therapy
#18
Hideharu Miura, Shuichi Ozawa, Fumika Hosono, Naoki Sumida, Toshiya Okazue, Kiyoshi Yamada, Yasushi Nagata
Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT-XD films have been designed for optimal performance in the 40-4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose-response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high-dose volumetric-modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0-4,000 cGy range...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297285/deriving-detector-specific-correction-factors-for-rectangular-small-fields-using-a-scintillator-detector
#19
Yujiao Qin, Hualiang Zhong, Ning Wen, Karen Snyder, Yimei Huang, Indrin J Chetty
The goal of this study was to investigate small field output factors (OFs) for flattening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1)...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297283/clinically-relevant-investigation-of-flattening-filter-free-skin-dose
#20
Christopher L Guy, Kishor Karki, Manju Sharma, Siyong Kim
As flattening filter-free (FFF) photon beams become readily available for treatment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2×2,3×3,4×4,6×6,8×8,10×10,20×20, and 30×30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF)...
November 2016: Journal of Applied Clinical Medical Physics
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