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https://www.readbyqxmd.com/read/29030203/characterization-and-clinical-evaluation-of-a-novel-2d-detector-array-for-conventional-and-flattening-filter-free-fff-imrt-pre-treatment-verification
#1
Yuvaraj Sekar, Johannes Thoelking, Miriam Eckl, Irakli Kalichava, Dwi Seno Kuncoro Sihono, Frank Lohr, Frederik Wenz, Hansjoerg Wertz
BACKGROUND AND PURPOSE: The novel MatriXX(FFF) (IBA Dosimetry, Germany) detector is a new 2D ionization chamber detector array designed for patient specific IMRT-plan verification including flattening-filter-free (FFF) beams. This study provides a detailed analysis of the characterization and clinical evaluation of the new detector array. MATERIAL AND METHODS: The verification of the MatriXX(FFF) was subdivided into (i) physical dosimetric tests including dose linearity, dose rate dependency and output factor measurements and (ii) patient specific IMRT pre-treatment plan verifications...
October 10, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29017804/nanomanufacturing-through-microfluidic-assisted-nanoprecipitation-advanced-analytics-and-structure-activity-relationships
#2
Roberto Donno, Arianna Gennari, Enrique Lallana, Julio M Rios De La Rosa, Richard d'Arcy, Kevin Treacher, Kathryn Hill, Marianne Ashford, Nicola Tirelli
We have employed microfluidics (cross-shaped chip) for the preparation of drug-loaded poly(lactic acid-co-glycolic acid) (PLGA) nanoparticles. The polymer precipitates from an acetone solution upon its controlled laminar mixing (flow focusing) with an aqueous solution of a surfactant, allowing for an operator-independent, up-scalable and reproducible preparative process of nanoformulations. Firstly, using PEGylated surfactants we have compared batch and microfluidic processes, and showed the superior reproducibility of the latter and its strong dependency on the acetone/water ratio (flow rate ratio)...
October 7, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/29017734/anatomy-of-the-vasculature-of-the-lower-leg-and-harvest-of-a-fibular-flap-a-systematic-review
#3
REVIEW
A K Abou-Foul, A Fasanmade, S Prabhu, F Borumandi
The fibular free flap (FFF) is based on the peroneal artery, which has a consistent anatomy and makes a minimal contribution to the pedal circulation. However, certain anatomical variations in the vasculature of the leg might leave the peroneal artery with a major role in the perfusion of the foot, and to raise a FFF could lead to ischaemic complications. Our aim was to review the implications of anatomical variants on planning and harvest of a FFF. We systematically reviewed all relevant publications, and included 28 cases that described a dominant peroneal artery and FFF...
October 7, 2017: British Journal of Oral & Maxillofacial Surgery
https://www.readbyqxmd.com/read/29016574/microvascular-free-flaps-in-oral-and-maxillofacial-reconstruction-following-cancer-ablation
#4
Santosh Kumar Yadav, Suraksha Shrestha
Microsurgical free flaps have become the first choice for reconstruction of oral and maxillofacial (OMF) defects after tumor resection. Till recently the pectoralis major myocutaneous flap (PMMC) was considered to be the benchmark for OMF reconstruction. This philosophy is changing fast with rapid advancement in reconstructive microsurgery. Years of innovation in reconstructive microsurgery has given us a reasonably good number of excellent flaps. Tremendous work has been put into producing some exceptionally brilliant research articles, sometimes contradicting each other...
September 8, 2017: Journal of Nepal Health Research Council
https://www.readbyqxmd.com/read/28990427/chew-on-this-not-all-first-finger-foods-are-created-equal
#5
Nicol Awadalla, Tammy Pham, Ruth Milanaik
The American Academy of Pediatrics (AAP) recommends when to start first finger foods (FFFs) and what types of foods to start with, but it is unclear whether products marketed as FFF comply with these recommendations. We evaluated FFF products for compliance with AAP recommendations and product safety using 41 adult product testers, who were asked to dissolve each product in their mouth. Product characteristics, comments pertaining to product safety, and time to dissolve each product were recorded. Only 2 products met all AAP criteria, and safety concerns were raised for an additional 2 products...
October 1, 2017: Clinical Pediatrics
https://www.readbyqxmd.com/read/28974859/choice-of-a-suitable-dosimeter-for-photon-percentage-depth-dose-measurements-in-flattening-filter-free-beams
#6
Silvia Vargas Castrillón, Francisco Cutanda Henríquez
The International Atomic Energy Agency Technical Reports Series-398 code of practice for dosimetry recommends measuring photon percentage depth dose (PDD) curves with parallel-plate chambers. This code of practice was published before flattening filter-free (FFF) beams were widely used in clinical linear accelerators. The choice of detector for PDD measurements needs to be reassessed for FFF beams given the physical differences between FFF beams and flattened ones. The present study compares PDD curves for FFF beams of nominal energies 6 MV, 6 FFF, 10 MV, and 10 FFF from a Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, USA) acquired with Scanditronix photon diodes, two scanning type chambers (both PTW 31010 Semiflex), two small volume chambers (Wellhofer CC04 and PTW 31016 PinPoint 3D), PTW 34001 Roos, Scanditronix Roos, and NACP 02 parallel-plate chambers...
July 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28971344/the-effect-of-beam-interruption-during-fff-vmat-plans-for-sbrt
#7
Seongjong Oh, Benjamin Lewis, Amy Watson, Siyong Kim, Taeho Kim
To investigate the dosimetric effect of intended beam interruption during volumetric modulated arc therapy (VMAT) with flattening filter free (FFF) beam for exploring the possibility of deep inspiration breath hold stereotactic body radiation therapy (SBRT). A total of ten SBRT plans with 6 and 10 MV FFF beams were retrospectively selected. All plans consisted of four partial arcs, except one plan with six partial arcs. We delivered the plans using a Varian Truebeam™ with three different scenarios; without interruption (0int), with one intentional interruption (1int), or with two intentional interruptions (2int), per each partial arc...
October 2, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28955776/insight-into-the-binding-of-a-non-toxic-self-assembling-aromatic-tripeptide-with-ct-dna-spectroscopic-and-viscositic-studies
#8
Soumi Biswas, Satyabrata Samui, Arpita Chakraborty, Sagar Biswas, Debapriya De, Utpal Ghosh, Apurba K Das, Jishu Naskar
The report describes the synthesis, self-association and DNA binding studies of an aromatic tripeptide H-Phe-Phe-Phe-OH (FFF). The peptide backbone adopts β-sheet conformation both in solid and solution. In aqueous solution, FFF self-assembles to form nanostructured aggregates. Interactions of this peptide with calf-thymus DNA (ct-DNA) have been studied using various biophysical techniques including ultraviolet (UV) absorption spectroscopy, fluorescence spectroscopy and circular dichroism (CD) spectroscopy...
September 2017: Biochemistry and Biophysics Reports
https://www.readbyqxmd.com/read/28951047/hippocampal-dose-during-linac-based-stereotactic-radiotherapy-for-brain-metastases-an-observational-study
#9
Alba Fiorentino, Umberto Tebano, Gianluisa Sicignano, Francesco Ricchetti, Gioacchino Di Paola, Dario Aiello, Niccolò Giaj-Levra, Rosario Mazzola, Sergio Fersino, Ruggero Ruggieri, Filippo Alongi
INTRODUCTION: Aim of the present study is to evaluate homolateral and contralateral hippocampus (H-H, C-H, respectively) dose during Fractionated Stereotactic Radiotherapy (FSRT) or Radiosurgery (SRS) for brain metastases (BM). MATERIALS & METHODS: Patients with BM<5, size≤30mm, KPS≥80 and a life expectancy>3months, were considered for SRS/FSRT (total dose 15-30Gy, 1-5 fractions). For each BM, a Flattening Filter Free (FFF) Volumetric Modulated Arc Therapy (VMAT) plan was generated with one or two arcs...
September 23, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28944979/dosimetric-validation-of-monaco-treatment-planning-system-on-an-elekta-versahd-linear-accelerator
#10
Ganesh Narayanasamy, Daniel L Saenz, Dewayne Defoor, Niko Papanikolaou, Sotirios Stathakis
The purpose of this study is to perform dosimetric validation of Monaco treatment planning system version 5.1. The Elekta VersaHD linear accelerator with high dose rate flattening filter-free photon modes and electron energies was used in this study. The dosimetric output of the new Agility head combined with the FFF photon modes warranted this investigation into the dosimetric accuracy prior to clinical usage. A model of the VersaHD linac was created in Monaco TPS by Elekta using commissioned beam data including percent depth dose curves, beam profiles, and output factors...
September 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28942253/cleavage-of-the-main-carbon-chain-backbone-of-high-molecular-weight-polyacrylamide-by-aerobic-and-anaerobic-biological-treatment
#11
Wenzhe Song, Yu Zhang, Yingxin Gao, Dong Chen, Min Yang
High molecular weight partially hydrolyzed polyacrylamide (PAM) can be bio-hydrolyzed on the amide side group, however, solid evidence regarding the biological cleavage of its main carbon chain backbone is limited. In this study, viscometry, flow field-flow fractionation multi-angle light scattering (FFF-MALS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis were used to investigate the biodegradability of PAM with a nominal molecular weight of 2 × 10(7) Da (Da) in two suspended aerobic (25 and 40 °C) and two upflow anaerobic blanket reactors (35 and 55 °C) operated for 470 d under a hydraulic residence time (HRT) of 2 d...
September 18, 2017: Chemosphere
https://www.readbyqxmd.com/read/28915893/dosimetric-comparison-of-different-treatment-modalities-for-stereotactic-radiotherapy
#12
Shih-Ming Hsu, Yuan-Chun Lai, Chien-Chung Jeng, Chia-Ying Tseng
BACKGROUND: The modalities for performing stereotactic radiotherapy (SRT) on the brain include the cone-based linear accelerator (linac), the flattening filter-free (FFF) volumetric modulated arc therapy (VMAT) linac, and tomotherapy. In this study, the cone-based linac, FFF-VMAT linac, and tomotherapy modalities were evaluated by measuring the differences in doses delivered during brain SRT and experimentally assessing the accuracy of the output radiation doses through clinical measurements...
September 16, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28899649/small-field-characterization-of-a-nanochamber-prototype-under-flattening-filter-free-photon-beams
#13
G Reggiori, A Stravato, P Mancosu, F Lobefalo, L Paganini, F Zucconi, V Palumbo, A Gaudino, M Scorsetti, S Tomatis
INTRODUCTION: Nanochambers present some advantages in terms of energy independence and absolute dose measurement for small field dosimetry in the SBRT scenario. Characterization of a micro-chamber prototype was carried out both under flattened and flattening-filter-free (FFF) beams with particular focus on stem effect. METHODS: The study included characterization of leakage and stem effects, dose rate and dose per pulse dependence, measurement of profiles, and percentage depth doses (PDDs)...
September 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28887827/a-universal-parameterized-gradient-based-method-for-photon-beam-field-size-determination
#14
Sharon Lebron, Guanghua Yan, Jonathan Li, Bo Lu, Chihray Liu
PURPOSE: To propose a universal, parameterized gradient-based method (PGM) for radiation field size determination. METHODS: The PGM locates the beam profile's edge by parameterizing its penumbra region with a modified sigmoid function where the inflection point can be determined in a closed form. The parametrization was validated with filter-flattened (FF), flattening-filter-free (FFF) and wedged profiles measured on two Elekta linac models (Synergy and Versa HD)...
September 9, 2017: Medical Physics
https://www.readbyqxmd.com/read/28886357/a-retrospective-volume-matched-analysis-of-the-submental-artery-island-pedicled-flap-as-compared-to-the-forearm-free-flap-is-it-a-good-alternative-choice-for-the-reconstruction-of-defects-of-the-oral-cavity-and-oropharynx
#15
Nawaf Aslam-Pervez, Steven J Caldroney, Amal Isaiah, Joshua E Lubek
PURPOSE: The submental artery island pedicled flap (SMIF) is an underused alternative for reconstruction of head and neck defects after tumor ablation. The purpose of this study was to perform a comparative evaluation of reconstructive outcomes based on surgical site and ablative defect volume in patients who underwent reconstruction with the SMIF versus the forearm free flap (FFF). MATERIALS AND METHODS: A retrospective cohort study of all patients with oral cavity and oropharyngeal defects reconstructed with the SMIF and a cohort of patients with similar volume defects reconstructed with the FFF were compared for oncologic safety and viability of equivalent reconstructive outcomes...
August 12, 2017: Journal of Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/28870945/flattening-filter-free-vs-flattened-beams-for-lung-stereotactic-body-radiation-therapy
#16
Pierre Annede, Julien Darreon, Ahcene Benkemouche, Simon Valdenaire, Marguerite Tyran, Bertrand Kaeppelin, Alban Macagno, Julien Barrou, Leonel Varela Cagetti, Veronique Favrel, Laurence Moureau-Zabotto, Laurence Gonzague, Pierre Fau, Cyrus Chargari, Agnes Tallet, Naji Salem
BACKGROUND/AIM: To assess the clinical impact of high dose rate stereotactic body radiation therapy (SBRT) in patients with lung neoplastic lesions. PATIENTS AND METHODS: From January 2014 to June 2016, a single-center retrospective analysis was performed including all patients treated by either flattening filter free (FFF) beams or flattening filter beams (FF) three-dimensional (3D) SBRT for lung neoplastic lesions. RESULTS: A total of 99 SBRT were performed on 75 patients...
September 2017: Anticancer Research
https://www.readbyqxmd.com/read/28857432/volumetric-modulated-arc-therapy-and-intensity-modulated-radiation-therapy-treatment-planning-for-prostate-cancer-with-flattened-beam-and-flattening-filter-free-linear-accelerators
#17
Marius Treutwein, Matthias Hipp, Oliver Koelbl, Barbara Dobler
This study on patients with localized prostate cancer was set up to investigate valuable differences using flattened beam (FB) and flattening filter free (FFF) mode in the application of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). For ten patients, four different plans were calculated with Oncentra planning system of Elekta, using Synergy machines: IMRT and VMAT, with and without flattening filter. Homogeneity and conformity indexes, dose to the organs at risk, and measurements of peripheral dose and dosimetric plan verification including record of the delivery times were analyzed and statistically evaluated...
August 30, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28834109/implementation-of-respiratory-gated-vmat-on-a-versa-hd-linear-accelerator
#18
Jeffrey E Snyder, Ryan T Flynn, Daniel E Hyer
The accurate delivery of respiratory-gated volumetric modulated arc therapy (VMAT) treatment plans presents a challenge since the gantry rotation and collimator leaves must be repeatedly stopped and set into motion during each breathing cycle. In this study, we present the commissioning process for an Anzai gating system (AZ-733VI) on an Elekta Versa HD linear accelerator and make recommendations for successful clinical implementation. The commissioning tests include central axis dose consistency, profile consistency, gating beam-on/off delay, and comparison of gated versus nongated gamma pass rates for patient-specific quality assurance using four clinically commissioned photon energies: 6 MV, 6 FFF, 10 MV, and 10 FFF...
August 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28797664/investigation-of-zinc-oxide-particles-in-cosmetic-products-by-means-of-centrifugal-and-asymmetrical-flow-field-flow-fractionation
#19
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
#20
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 flattening 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...
September 15, 2017: Physics in Medicine and Biology
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