keyword
MENU ▼
Read by QxMD icon Read
search

fff

keyword
https://www.readbyqxmd.com/read/29671410/motion-induced-interplay-effects-for-vmat-radiotherapy
#1
Anneli Edvardsson, Fredrik Nordström, Crister Ceberg, Sofie Ceberg
The purpose of this study was to develop a method to simulate breathing motion induced interplay effects for volumetric modulated arc therapy (VMAT), to verify the proposed method with measurements, and to use the method to investigate how interplay effects vary with different patient- and machine specific parameters. VMAT treatment plans were created on a virtual phantom in a treatment planning system (TPS). Interplay effects were simulated by dividing each plan into smaller sub-arcs using an in-house developed software and shifting the isocenter for each sub-arc to simulate a sin6 breathing motion in the superior-inferior direction...
April 19, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29580032/comparative-evaluation-of-a-6mv-flattened-beam-and-a-flattening-filter-free-beam-for-carcinoma-of-cervix-%C3%A2-imrt-planning-study
#2
Suresh Tamilarasu, Madeswaran Saminathan, S K Sharma, Anjali Pahuja, Abhinav Dewan
Purpose: Intensity modulated radiotherapy (IMRT) plan quality, beam on time and integral dose were compared using 6MV FB (Flattened Beam) and FFFB (Flattening filter free beam) for carcinoma of cervix. Materials and Methods: Ten patients with stage II–IIIB cervix cancer (Ca.Cx) were retrospectively identified from the department database. Target volume (TV) and organ at risk (OAR) were delineated as per Radiation Therapy Oncology Group (RTOG) cancer guidelines. Dose prescribed to planning target volume (PTV) was 50...
March 27, 2018: Asian Pacific Journal of Cancer Prevention: APJCP
https://www.readbyqxmd.com/read/29563993/flattening-filter-free-technique-in-volumetric-modulated-arc-therapy-for-lung-stereotactic-body-radiotherapy-a-clinical-comparison-with-the-flattening-filter-technique
#3
Shuri Aoki, Hideomi Yamashita, Akihiro Haga, Kanabu Nawa, Toshikazu Imae, Wataru Takahashi, Osamu Abe, Keiichi Nakagawa
The present study sought to evaluate the impact of the flattening filter-free (FFF) technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy. Its clinical safety and availability were compared with the flattening filter (FF) method. The cases of 65 patients who underwent lung volumetric modulated arc therapy-stereotactic body radiotherapy (VMAT-SBRT) using FF or FFF techniques were reviewed. A total of 55 Gy/4 fractions (fr) was prescribed for peripheral lesions or 56 Gy/7 fr for central lesions...
March 2018: Oncology Letters
https://www.readbyqxmd.com/read/29562568/monte-carlo-evaluation-of-the-potential-benefits-of-flattening-filter-free-beams-from-the-oncor%C3%A2-clinical-linear-accelerator
#4
Amin Asadi, SeidKazem Razavi-Ratki, Keyvan Jabbari, Milad Najafzadeh, Abolfazl Nickfarjam
OBJECTIVES: To evaluate the potential privileges of flattening filter-free (FFF) photon beams from Oncor® linac for 6 MV and 18 MV energies. METHODS: A Monte Carlo (MC) model of Oncor® linac was built using BEAMnrc MCCode and verified by the measured data using 6 MV and 18 MV energies. A comprehensive set of data was also characterized for MC model of Oncor® machine running with and without flattening filter (FF) for 6 MV and 18 MV beams in six field sizes...
March 15, 2018: Journal of X-ray Science and Technology
https://www.readbyqxmd.com/read/29558116/structural-polymorphism-in-a-self-assembled-tri-aromatic-peptide-system
#5
Noam Brown, Jiangtao Lei, Chendi Zhan, Linda J W Shimon, Lihi Adler-Abramovich, Guanghong Wei, Ehud Gazit
Self-assembly is a process of key importance in natural systems and in nanotechnology. Peptides are attractive building blocks due to their relative facile synthesis, biocompatibility and other unique properties. Diphenylalanine (FF) and its derivatives are known to form nanostructures of various architectures and remarkable characteristics. The larger triphenylalanine (FFF) was found to self-assemble as efficiently as FF, forming related but distinct architectures of plate-like and spherical nanostructures...
March 20, 2018: ACS Nano
https://www.readbyqxmd.com/read/29543930/evaluation-of-two-3d-printers-for-guided-implant-surgery
#6
Bruno Sommacal, Miodrag Savic, Andreas Filippi, Sebastian Kühl, Florian M Thieringer
PURPOSE: To compare the suitability of a fused filament fabrication (FFF) consumer 3D printer with a professional digital light processing (DLP) printer for the production of surgical templates for guided oral implant surgery. MATERIALS AND METHODS: Eight virtual templates were printed with two different 3D printers. These were optically scanned and the incongruences between virtual and printed templates were determined after alignment of the surface scans and the virtual data...
March 15, 2018: International Journal of Oral & Maxillofacial Implants
https://www.readbyqxmd.com/read/29528650/reproducing-quantum-probability-distributions-at-the-speed-of-classical-dynamics-a-new-approach-for-developing-force-field-functors
#7
Vikram Sundar, David Gelbwaser-Klimovsky, Alán Aspuru-Guzik
Modeling nuclear quantum effects is required for accurate molecular dynamics (MD) simulations of molecules. The community has paid special attention to water and other biomolecules that show hydrogen bonding. Standard methods of modeling nuclear quantum effects like Ring Polymer Molecular Dynamics (RPMD) are computationally costlier than running classical trajectories. A force-field functor (FFF) is an alternative method that computes an effective force field which replicates quantum properties of the original force field...
March 12, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29528035/the-impact-of-the-oxygen-scavenger-on-the-dose-rate-dependence-and-dose-sensitivity-of-magic-type-polymer-gels
#8
Muzafar Khan, Gerd Heilemann, Peter Kuess, Dietmar Georg, Andreas Berg
Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D) , which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates...
March 12, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29521762/does-a-vascularized-fibula-free-bone-grafted-immediately-after-hemimandibulectomy-in-a-child-grow-or-relapse-during-adolescence
#9
Kohei Okuyama, Masashi Yamashiro, Atsushi Kaida, Aya Kawamata, Miho Mizutani, Yasuyuki Michi, Narikazu Uzawa, Tomoyuki Yano, Rei Tohyama, Satoshi Yamaguchi
For young growing children before the end of skeletal maturity, the growth activity of the grafted bone after hemimandibulectomy is not well-known. After an adolescence, such a patient may have facial deformity because the anterior growth point of the mandible is in the condylar neck. A 13-year-old boy was performed hemimandibulectomy with immediate mandibular reconstruction by fibula free flap (FFF) because of a huge ameloblastic fibroma. The authors evaluated the length of FFF on the images of computed tomography (CT) at 5 and 60 months after the operation and compared them by calculating growth rates...
March 8, 2018: Journal of Craniofacial Surgery
https://www.readbyqxmd.com/read/29521280/beam-characterisation-of-the-1-5-t-mri-linac
#10
Simon J Woodings, J J Bluemink, J H Wilfred de Vries, Yury Niatsetski, Bob van Veelen, Joost Schillings, Jan G M Kok, Jochem W H Wolthaus, Sara L Hackett, Bram van Asselen, Helena Maria van Zijp, Stefan Pencea, David A Roberts, Jan J W Lagendijk, Bas W Raaymakers
As a prerequisite for clinical treatments it was necessary to characterize the Elekta 1.5 T MRI-linac 7 MV FFF radiation beam. Following acceptance testing, beam characterization data were acquired with Semiflex 3D (PTW 31021), microDiamond (PTW 60019), and Farmer-type (PTW 30013 and IBA FC65-G) detectors in an Elekta 3D scanning water phantom and a PTW 1D water phantom. EBT3 Gafchromic film and ion chamber measurements in a buildup cap were also used. Special consideration was given to scan offsets, detector effective points of measurement and avoiding air gaps...
March 9, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29519415/relative-biological-effectiveness-study-of-lipiodol-based-on-microdosimetric-kinetic-model
#11
Daisuke Kawahara, Hisashi Nakano, Shuichi Ozawa, Akito Saito, Tomoki Kimura, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
OBJECTIVES: We examine the contrast agent Lipiodol effect on the relative biological effectiveness (RBE) values for flattening filter free (FFF) and flattening filter (FF) beams of 6 MV-Xray (6 MVX) and 10 MVX. METHODS: Lipiodol was placed at 5 cm depth in water. According to the microdosimetric kinetic model, the RBE values for killing the human liver hepatocellular cells were calculated from dose and lineal energy (yd(y)) from Monte Carlo simulations. RBE200kVX and RBECo were defined as the ratios of dose using reference radiation (200 kVX, Co-ɤ) to the dose of test radiation (FFF and FF beams for 6 MV and 10 MV) to produce the same biological effects...
February 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29516908/dose-rate-and-energy-dependence-study-of-methacrylic-acid-gelatin-tetrakis-hydroxymethyl-phosphonium-chloride-gel-with-flattened-and-unflattened-photon-beams
#12
P Sathiyaraj, James Jebaseelan Samuel
Aims: The aim of this study is to evaluate the dose rate and energy dependency of methacrylic acid gelatin tetrakis (hydroxymethyl) phosphonium chloride (MAGAT) gel in unflattened photon beam using X-ray computed tomography (CT) and ultraviolet (UV)-visible spectroscopy. Materials and Methods: MAGAT gel was prepared and it was exposed to 6 MV flattened and unflattened beams. The dose selected for irradiation was ranging from 3 to 15 Gy with an increment of 3 Gy...
January 2018: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/29500001/flexible-flatfoot-of-6-13-year-old-children-a-cross-sectional-study
#13
Jichao Yin, Hongmou Zhao, Guihua Zhuang, Xiaojun Liang, Xinglv Hu, Yi Zhu, Rongqiang Zhang, Xiaochen Fan, Yi Cao
BACKGROUND: This cross-sectional study aims to investigate the flexible flatfoot (FFF) prevalence and related factors in school-aged children. METHODS: A total of 1059 children aged 6-13 years were included. Dynamic footprints according to the FootScan system were collected from both feet. The relationship of FFF with age, gender, side, and body mass index (BMI) was investigated. RESULTS: FFF percentage decreased from 39.5% at 6 years to 11...
February 27, 2018: Journal of Orthopaedic Science: Official Journal of the Japanese Orthopaedic Association
https://www.readbyqxmd.com/read/29499547/icp-ms-based-methods-to-characterize-nanoparticles-of-tio-2-and-zno-in-sunscreens-with-focus-on-regulatory-and-safety-issues
#14
Beatrice Bocca, Stefano Caimi, Oreste Senofonte, Alessandro Alimonti, Francesco Petrucci
This study sought to develop analytical methods to characterize titanium dioxide (TiO2 ) and zinc oxide (ZnO) nanoparticles (NPs), including the particle size distribution and concentration, in cream and spray sunscreens with different sun protection factor (SPF). The Single Particle Inductively Coupled Plasma-Mass Spectrometry (SP ICP-MS) was used as screening and fast method to determine particles size and number. The Asymmetric Flow-Field Flow Fractionation (AF4-FFF) as a pre-separation technique was on-line coupled to the Multi-Angle Light Scattering (MALS) and ICP-MS to determine particle size distributions and size dependent multi-elemental concentration...
February 27, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29472075/a-novel-high-resolution-2d-silicon-array-detector-for-small-field-dosimetry-with-fff-photon-beams
#15
G Biasi, M Petasecca, S Guatelli, N Hardcastle, M Carolan, V Perevertaylo, T Kron, A B Rosenfeld
PURPOSE: Flattening filter free (FFF) beams are increasingly being considered for stereotactic radiotherapy (SRT). For the first time, the performance of a monolithic silicon array detector under 6 and 10 MV FFF beams was evaluated. The dosimeter, named "Octa" and designed by the Centre for Medical Radiation Physics (CMRP), was tested also under flattened beams for comparison. METHODS: Output factors (OFs), percentage depth-dose (PDD), dose profiles (DPs) and dose per pulse (DPP) dependence were investigated...
January 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29461974/comparison-of-k-q-factors-measured-with-a-water-calorimeter-in-flattening-filter-free-fff-and-conventional-flattening-filter-cff-photon-beams
#16
Leon de Prez, Jacco de Pooter, Bartel Jansen, Thijs Perik, Frits 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 kQ factors...
February 20, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29450985/effect-of-secondary-electron-generation-on-dose-enhancement-in-lipiodol-with-and-without-a-flattening-filter
#17
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
#18
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
#19
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
#20
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
keyword
keyword
39368
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"