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https://www.readbyqxmd.com/read/29450985/effect-of-secondary-electron-generation-on-dose-enhancement-in-lipiodol-with-and-without-a-flattening-filter
#1
Daisuke Kawahara, Shuichi Ozawa, Akito Saito, Tomoki Kimura, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Takeo Nakashima, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
PURPOSE: Lipiodol, which was used in transcatheter arterial chemoembolization before liver stereotactic body radiation therapy (SBRT), remains in SBRT. Previous we reported the dose enhancement in Lipiodol using 10 MV (10×) FFF beam. In this study, we compared the dose enhancement in Lipiodol and evaluated the probability of electron generation (PEG) for the dose enhancement using flattening filter (FF) and flattening filter free (FFF) beams. METHODS: FF and FFF for 6 MV (6×) and 10× beams were delivered by TrueBeam...
February 15, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29439415/current-application-of-capillary-electrophoresis-in-nanomaterial-characterisation-and-its-potential-to-characterise-the-protein-and-small-molecule-corona
#2
REVIEW
Andrew J Chetwynd, Emily J Guggenheim, Sophie M Briffa, James A Thorn, Iseult Lynch, Eugenia Valsami-Jones
Due to the increasing use and production of nanomaterials (NMs), the ability to characterise their physical/chemical properties quickly and reliably has never been so important. Proper characterisation allows a thorough understanding of the material and its stability, and is critical to establishing dose-response curves to ascertain risks to human and environmental health. Traditionally, methods such as Transmission Electron Microscopy (TEM), Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) have been favoured for size characterisation, due to their wide-availability and well-established protocols...
February 10, 2018: Nanomaterials
https://www.readbyqxmd.com/read/29431865/refinement-of-mlc-modelling-improves-comercial-qa-dosimetry-system-for-srs-and-sbrt-patient-specific-qa
#3
Yair Hillman, Josh Kim, Indrin Chetty, Ning Wen
PURPOSE: Mobius 3D (M3D) provides a volumetric dose verification of the treatment planning system's calculated dose using an independent beam model and a collapsed cone convolution superposition algorithm. However, there is a lack of investigation into M3D's accuracy and effectiveness for stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) quality assurance (QA). Here, we collaborated with the vendor to develop a revised M3D beam model for SRS/SBRT cases treated with a 6X Flattening Filter Free (FFF) beam and high definition multiple leaf collimator (HDMLC) on an Edge linear accelerator...
February 12, 2018: Medical Physics
https://www.readbyqxmd.com/read/29397986/experimental-verification-of-the-steric-entropic-mode-of-retention-in-centrifugal-field-flow-fractionation-using-illite-clay-plates
#4
Soheyl Tadjiki, Ronald Beckett
The commonly used theory to describe the normal Brownian mode of field-flow fractionation (FFF) assumes the particles to be point masses and hence the shape is ignored. Beckett and Giddings extended this theory to include the effect of thin rods and discs being forced very close to the accumulation wall. By including the decrease in the entropy this causes, they derived new expressions for the retention of such nonspherical particles in FFF. The steric-entropic theory predicts that when the sample cloud thickness is less than the major dimension of the rods or discs then particles elute earlier than predicted by the Brownian mode theory...
February 2, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29370238/the-existence-of-fertile-hybrids-of-closely-related-model-earthworm-species-eisenia-andrei-and-e-fetida
#5
Barbara Plytycz, Janusz Bigaj, Artur Osikowski, Sebastian Hofman, Andrzej Falniowski, Tomasz Panz, Pawel Grzmil, Franck Vandenbulcke
Lumbricid earthworms Eisenia andrei (Ea) and E. fetida (Ef) are simultaneous hermaphrodites with reciprocal insemination capable of self-fertilization while the existence of hybridization of these two species was still debatable. During the present investigation fertile hybrids of Ea and Ef were detected. Virgin specimens of Ea and Ef were laboratory crossed (Ea+Ef) and their progeny was doubly identified. 1 -identified by species-specific maternally derived haploid mitochondrial DNA sequences of the COI gene being either 'a' for worms hatched from Ea ova or 'f' for worms hatched from Ef ova...
2018: PloS One
https://www.readbyqxmd.com/read/29369049/comparison-of-i-k-i-sub-q-sub-factors-measured-with-a-water-calorimeter-in-flattening-filter-free-fff-and-conventional-flattening-filter-cff-photon-beams
#6
Leon Armand de Prez, Jacco A de Pooter, Bartel Joris Jansen, Thijs Jan Perik, Frits W Wittkämper
Recently flattening filter free (FFF) beams became available for application in modern radiotherapy. There are several advantages of FFF beams over conventional flattening filtered (cFF) beams, however differences in beam spectra at the point of interest in a phantom potentially affect the ion chamber response. Beams are also non-uniform over the length of a typical reference ion chamber and recombination is usually larger. Despite several studies describing FFF beam characteristics, only a limited number of studies investigated their effect on <i>k</i><sub>Q</sub> factors...
January 25, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29360151/compton-scatter-imaging-a-promising-modality-for-image-guidance-in-lung-stereotactic-body-radiation-therapy
#7
Gage Redler, Kevin C Jones, Alistair Templeton, Damian Bernard, Julius Turian, James C H Chu
PURPOSE: Lung stereotactic body radiation therapy (SBRT) requires delivering large radiation doses with millimeter accuracy, making image guidance essential. An approach to forming images of patient anatomy from photons Compton scattered during lung SBRT is presented. METHODS: To investigate the potential of scatter imaging, a pinhole collimator and flat-panel detector are used for spatial localization and detection of photons scattered during external beam therapy using lung SBRT treatment conditions (6MV FFF beam)...
January 23, 2018: Medical Physics
https://www.readbyqxmd.com/read/29357886/modelling-the-immunosuppressive-effect-of-liver-sbrt-by-simulating-the-dose-to-circulating-lymphocytes-an-in-silico-planning-study
#8
L Basler, N Andratschke, S Ehrbar, M Guckenberger, S Tanadini-Lang
BACKGROUND: Tumor immune-evasion and associated failure of immunotherapy can potentially be overcome by radiotherapy, which however also has detrimental effects on tumor-infiltrating and circulating lymphocytes (CL). We therefore established a model to simulate the radiation-dose delivered to CL. METHODS: A MATLAB-model was established to quantify the CL-dose during SBRT of liver metastases by considering the factors: hepatic blood-flow, -velocity and transition-time of individual hepatic segments, as well as probability-based recirculation...
January 22, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29348734/energy-spectrum-and-dose-enhancement-due-to-the-depth-of-the-lipiodol-position-using-flattened-and-unflattened-beams
#9
Daisuke Kawahara, Shuichi Ozawa, Akito Saito, Tomoki Kimura, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Kazunari Hioki, Takeo Nakashima, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
Aim: Lipiodol was used for stereotactic body radiotherapy combining trans arterial chemoembolization. Lipiodol used for tumour seeking in trans arterial chemoembolization remains in stereotactic body radiation therapy. In our previous study, we reported the dose enhancement effect in Lipiodol with 10× flattening-filter-free (FFF). The objective of our study was to evaluate the dose enhancement and energy spectrum of photons and electrons due to the Lipiodol depth with flattened (FF) and FFF beams...
January 2018: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/29343253/an-integrated-primary-care-approach-for-frail-community-dwelling-older-persons-a-step-forward-in-improving-the-quality-of-care
#10
Lotte Vestjens, Jane M Cramm, Anna P Nieboer
BACKGROUND: High-quality care delivery for frail older persons, many of whom have multiple complex needs, is among the greatest challenges faced by healthcare systems today. The Chronic Care Model (CCM) may guide quality improvement efforts for primary care delivery to frail older populations. Objectives of this study were to assess the implementation of interventions in CCM dimensions, and to investigate the quality of primary care as perceived by healthcare professionals, in practices following the Finding and Follow-up of Frail older persons (FFF) integrated care approach and those providing usual care...
January 17, 2018: BMC Health Services Research
https://www.readbyqxmd.com/read/29338305/safety-and-feasibility-of-prostate-stereotactic-ablative-radiotherapy-using-multimodality-imaging-and-flattening-filter-free
#11
Aileen Duffton, Azmat Sadozye, Lynsey Devlin, Nicholas MacLeod, Carolynn Lamb, Suzanne Currie, Philip McLoone, Marimuthu Sankaralingam, John Foster, Stephanie Paterson, Stefanie Keatings, David Dodds
OBJECTIVE: To investigate feasibility and safety of stereotactic ablative radiotherapy in the management of prostate cancer while employing MR/CT fusion for delineation, fiducial marker seeds for positioning and Varian RapidArc with flattening filter free (FFF) delivery. METHODS: 41 patients were treated for low-intermediate risk prostate cancer with initial prostate-specific antigen of ≤20 ng ml-1, Gleason score 6-7. Patients had MR/CT fusion for delineation of prostate ±seminal vesicles...
February 1, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29300182/a-novel-rapid-additive-manufacturing-concept-for-architectural-composite-shell-construction-inspired-by-the-shell-formation-in-land-snails
#12
Benjamin Felbrich, Frederik Wulle, Christoph Allgaier, Achim Menges, Alexander Verl, Karl-Heinz Wurst, James Nebelsick
State of the art rapid additive manufacturing (RAM), specifically Fused Filament Fabrication (FFF) has gained popularity among architects, engineers and designers for quick prototyping of technical devices, rapid production of small series and even construction scale fabrication of architectural elements. The spectrum of producible shapes and the resolution of detail, however, are determined and constrained by the layer-based nature of the fabrication process. These aspects significantly limit FFF-based approaches for the prefabrication and in-situ fabrication of freeform shells at the architectural scale...
January 4, 2018: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/29287640/precision-and-trueness-of-dental-models-manufactured-with-different-3-dimensional-printing-techniques
#13
Soo-Yeon Kim, Yoo-Seok Shin, Hwi-Dong Jung, Chung-Ju Hwang, Hyoung-Seon Baik, Jung-Yul Cha
INTRODUCTION: In this study, we assessed the precision and trueness of dental models printed with 3-dimensional (3D) printers via different printing techniques. METHODS: Digital reference models were printed 5 times using stereolithography apparatus (SLA), digital light processing (DLP), fused filament fabrication (FFF), and the PolyJet technique. The 3D printed models were scanned and evaluated for tooth, arch, and occlusion measurements. Precision and trueness were analyzed with root mean squares (RMS) for the differences in each measurement...
January 2018: American Journal of Orthodontics and Dentofacial Orthopedics
https://www.readbyqxmd.com/read/29220821/predictive-capabilities-of-various-constitutive-models-for-arterial-tissue
#14
Florian Schroeder, Stanislav Polzer, Martin Slažanský, Vojtěch Man, Pavel Skácel
INTRODUCTION: Aim of this study is to validate some constitutive models by assessing their capabilities in describing and predicting uniaxial and biaxial behavior of porcine aortic tissue. METHODS: 14 samples from porcine aortas were used to perform 2 uniaxial and 5 biaxial tensile tests. Transversal strains were furthermore stored for uniaxial data. The experimental data were fitted by four constitutive models: Holzapfel-Gasser-Ogden model (HGO), model based on generalized structure tensor (GST), Four-Fiber-Family model (FFF) and Microfiber model...
November 22, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/29218841/improvement-of-conformal-arc-plans-by-using-deformable-margin-delineation-method-for-stereotactic-lung-radiotherapy
#15
Görkem Güngör, Melek Demir, Gökhan Aydın, Bülent Yapıcı, Banu Atalar, Enis Özyar
PURPOSE: Stereotactic body radiotherapy (SBRT) is an established treatment technique in the management of medically inoperable early stage non-small cell lung cancer (NSCLC). Different techniques such as volumetric modulated arc (VMAT) and three-dimensional conformal arc (DCA) can be used in SBRT. Previously, it has been shown that VMAT is superior to DCA technique in terms of plan evaluation parameters. However, DCA technique has several advantages such as ease of use and considerable shortening of the treatment time...
December 7, 2017: Journal of Applied Clinical Medical Physics
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
#16
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/29181268/the-flip-flop-fungus-sign-an-fdg-pet-ct-sign-of-benignity
#17
Alex A Nagelschneider, Stephen M Broski, William P Holland, David E Midthun, Anne-Marie Sykes, Val J Lowe, Patrick J Peller, Geoffrey B Johnson
Benign granulomatous processes such as fungal infection may mimic metastatic lung cancer on FDG PET/CT. We found that these processes often have draining lymph node(s) with equal or greater FDG activity than associated lung nodule(s), a "flip-flop" of what is commonly seen in lung cancer. The aim of this study was to examine the utility of this "flip-flop fungus" (FFF) sign for diagnosing benign pulmonary disease. FDG PET/CT scans performed between 9/09-3/13 for the indications of pulmonary nodule or mass were reviewed...
2017: American Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/29174551/surgical-management-of-severe-osteoradionecrosis-of-the-mandibular-bone-by-using-double-free-flap-reconstruction
#18
Niklas Rommel, Marco Rainer Kesting, Nils Hagen Rohleder, Klaus-Dietrich Wolff, Jochen Weitz
PURPOSE: Osteoradionecrosis (ORN) of the jaws represents one of the most severe complications after primary or adjuvant radiation therapy (RT) of large head and neck tumors. In advanced ORN cases, surgical management is generally considered the therapy of choice. However, in several severe ORN patients with extensive bone and soft tissue defects, functional and aesthetic reconstruction represents a huge challenge for any surgeon, with an increased risk of post-operative wound healing disorders...
January 2018: Journal of Cranio-maxillo-facial Surgery
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
#19
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/29152898/tolerance-levels-of-ct-number-to-electron-density-table-for-photon-beam-in-radiotherapy-treatment-planning-system
#20
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
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