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Thu M Dang, Mitchell J Peters, Brigid Hickey, Adam Semciw
A linear accelerator with the flattening-filter removed generates a non-uniform dose profile beam. We aimed to analyse and compare plan quality and treatment time between flattened beam (FB) and flattening-filter-free (FFF) beam to assess the efficacy of FFF beam for stereotactic body radiation therapy (SBRT). The search strategy was based around 3 concepts; radiation therapy, flattening-filter-free and treatment delivery. The years searched were restricted from 2010 to date of review (October 2015). All plan quality comparisons were between FFF and FB plans from the same data sets...
January 24, 2017: Journal of Medical Imaging and Radiation Oncology
Catia Contado
Field flow fractionation (FFF) techniques are used to successfully characterize several nanomaterials by sizing nano-entities and producing information about the aggregation/agglomeration state of nanoparticles. By coupling FFF techniques to specific detectors, researchers can determine particle-size distributions (PSDs), expressed as mass-based or number-based PSDs. This review considers FFF applications in the food, biomedical, and environmental sectors, mostly drawn from the past 4 y. It thus underlines the prominent role of asymmetrical flow FFF within the FFF family...
January 23, 2017: Analytical and Bioanalytical Chemistry
Concetta Laliscia, Maria Grazia Fabrini, Durim Delishaj, Riccardo Morganti, Carlo Greco, Martina Cantarella, Roberta Tana, Fabiola Paiar, Angiolo Gadducci
OBJECTIVE: The objective of this study was to assess the role of stereotactic body radiotherapy (SBRT) in the treatment of distantly recurrent, oligometastatic gynecological cancer. METHODS: The hospital records of 45 patients with F-fluorodeoxyglucose (F-FDG) positron emission tomography positive, distantly recurrent, oligometastatic gynecological cancer were reviewed. All these patients had a number of target lesions less than 5, with largest diameter less than 6 cm...
February 2017: International Journal of Gynecological Cancer
Rachael E Warrington, Nathan S Hart, Ian C Potter, Shaun P Collin, Jan M Hemmi
Lampreys and hagfishes are the sole extant representatives of the early agnathan (jawless) vertebrates. We compared retinal function of fully-metamorphosed, immature Mordacia mordax (which are about to commence parasitic feeding) with those of sexually-mature individuals of its non-parasitic derivative M praecox We focused on elucidating the retinal adaptations to dim-light environments in these nocturnally-active lampreys, using electroretinography to determine the temporal resolution (flicker fusion frequency, FFF) and temporal contrast sensitivity (CS) of enucleated eyecups at different temperatures and light intensities...
January 20, 2017: Journal of Experimental Biology
Luis José Salazar-Serrano, Juan P Torres, Alejandra Valencia
In this article we present the development of a set of opto-mechanical components (a kinematic mount, a translation stage and an integrating sphere) that can be easily built using a 3D printer based on Fused Filament Fabrication (FFF) and parts that can be found in any hardware store. Here we provide a brief description of the 3D models used and some details on the fabrication process. Moreover, with the help of three simple experimental setups, we evaluate the performance of the opto-mechanical components developed by doing a quantitative comparison with its commercial counterparts...
2017: PloS One
D Dechambre, V Baart, S Cucchiaro, C Ernst, N Jansen, P Berkovic, C Mievis, P Coucke, A Gulyban
INTRODUCTION: To commission the Monte Carlo (MC) algorithm based model of CyberKnife robotic stereotactic system (CK) and evaluate the feasibility of patient specific QA using the ArcCHECK cylindrical 3D-array (AC) with Multiplug inserts (MP). RESULTS: Four configurations were used for simple beam setup and two for patient QA, replacing water equivalent inserts by lung. For twelve collimators (5-60mm) in simple setup, mean (SD) differences between MC and RayTracing algorithm (RT) of the number of points failing the 3%/1mmgamma criteria were 1(1), 1(3), 1(2) and 1(2) for the four MP configurations...
January 2017: Physica Medica: PM
Lu Liu, Guixin Shi, Ying Cui, Hui Li, Zhengchao Li, Qiangcheng Zeng, Yong Guo
The construction of engineered bone mostly focuses on simulating the extracellular matrix (ECM) for proper biological activity. However, the complexity of architecture and the variability of the mechanical properties of natural bones are related to individual differences in age, nutritional state, mechanical loading and disease status. Defect substitutions should be normed with the host natural bone, balancing architectural and mechanical adaption, as well as biological activity. Using a freeform fabrication (FFF) method, we prepared polycaprolactone (PCL) scaffolds with different architectures...
January 11, 2017: Biomedizinische Technik. Biomedical Engineering
J Roper
: Increased use of SBRT and hypofractionation in radiation oncology practice has posted a number of challenges to medical physicist, ranging from planning, image-guided patient setup and on-treatment monitoring, to quality assurance (QA) and dose delivery. This symposium is designed to provide current knowledge necessary for the safe and efficient implementation of SBRT in various linac platforms, including the emerging digital linacs equipped with high dose rate FFF beams. Issues related to 4D CT, PET and MRI simulations, 3D/4D CBCT guided patient setup, real-time image guidance during SBRT dose delivery using gated/un-gated VMAT/IMRT, and technical advancements in QA of SBRT (in particular, strategies dealing with high dose rate FFF beams) will be addressed...
June 2016: Medical Physics
P Galavis, D Barbee, G Jozsef
PURPOSE: Prone accelerated partial breast irradiation (APBI) results in dose reduction to the heart and lung. Flattening filter free beams (FFF) reduce out of field dose due to the reduced scatter from the removal of the flattening filter and reduce the buildup region. The aim of this work is to evaluate the dosimetric advantages of FFF beams to prone APBI target coverage and reduction in dose to organs at risk. METHODS: Fifteen clinical prone APBI cases using flattened photon beams were retrospectively re-planned in Eclipse-TPS using FFF beams...
June 2016: Medical Physics
M Kolar, R Szwedowski, J Greskovich, P Xia
PURPOSE: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. METHODS: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan...
June 2016: Medical Physics
J Adamson, A Faught, F Yin
PURPOSE: Flattening filter free photon energies are commonly used for high dose treatments such as SBRT, where localization accuracy is essential. Often, MV cine imaging may be employed to verify correct localization. TrueBeam Electronic Portal Imaging Devices (EPIDs) equipped with the 40×30cm(2) Image Detection Unit (IDU) are prone to image saturation at the image center especially for higher dose rates. While saturation often does not occur for cine imaging during treatment because the beam is attenuated by the patient, the flood field calibration is affected when the standard calibration procedure is followed...
June 2016: Medical Physics
T McCaw, M Hwang, S Jang, M Huq
PURPOSE: To quantify differences between the TG51 and TG51 addendum calibration protocols. METHODS: Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose-to-water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm(2) radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume-averaging correction was applied based on crossline and inline dose profiles...
June 2016: Medical Physics
K Samuvel, G Yadav, M Bhushan, S Tamilarasu, L Kumar, M Suhail
PURPOSE: To quantify the dosimetric accuracy of junction dose in double isocenter flattened and flatten filter free(FFF) intensity modulated radiation therapy(IMRT) and volumetric modulated arc therapy(VMAT) plan delivery using pelvis phantom. METHODS: Five large field pelvis patients were selected for this study. Double isocenter IMRT and VMAT treatment plans were generated in Eclipse Treatment planning System (V.11.0) using 6MV FB and FFF beams. For all the plans same distance 17...
June 2016: Medical Physics
B Casar, I Mendez Carot, P Peterlin
PURPOSE: Aim of the multi-centre study was to analyse beam hardening effect of the Integral Quality Monitor (IQM) for high energy photon beams used in radiotherapy with linear accelerators. Generic values for attenuation coefficient k(IQM) of IQM system were additionally investigated. METHODS: Beam hardening effect of the IQM system was studied for a set of standard nominal photon energies (6 MV-18 MV) and two flattening filter free (FFF) energies (6 MV FFF and 10 MV FFF)...
June 2016: Medical Physics
M Liu, N Wen, C Beyer, F Siddiqui, I Chetty, B Zhao
PURPOSE: Treating bulky tumors with grid therapy (GT) has demonstrated high response rates. Long delivery time (∼15min), with consequent increased risk of intrafraction motion, is a major disadvantage of conventional MLC-based GT (MLC-GT). The goal of this study was to develop and commission a MLC-GT technique with similar dosimetric characteristics, but more efficient delivery. METHODS: Grid plan was designed with 10X-FFF (2400MU/min) beam and MLC in a commercial treatment planning system (TPS)...
June 2016: Medical Physics
Y Na, P Black, J Adamovics, C Wuu
PURPOSE: With an increasing use of small field size and high dose rate irradiation in the advances of radiotherapy techniques, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), an in-depth quality assurance (QA) system is required. The purpose of this study is to investigate a high resolution optical CT-based 3D radiochromic dosimetry system for SBRT with intensity modulated radiotherapy (IMRT) and flattening filter free (FFF) volumetric modulated arc therapy (VMAT)...
June 2016: Medical Physics
B Barraclough, J Park, F Li, B Lu, J Li, C Liu, G Yan
PURPOSE: To report the development and characterization of the first in-house gating system implemented with an optical tracking system (OTS) and the Elekta Response™ interface. METHODS: The Response™ connects a patient tracking system with a linac, enabling the tracking system to control radiation delivery. The developed system uses an in-house OTS to monitor patient breathing. The OTS consists of two infrared-based cameras, tracking markers affixed on patient...
June 2016: Medical Physics
H T Lan, S H Lu, S H Kuo, Y C Tsai, L H Chen, S Y Wen, C W Wang
PURPOSE: When treating lung cancer patients with stereotactic body radiation therapy (SBRT), better immobilization is needed for accurate delivery of high-dose radiation. However, using a treatment couch (TrueBeamTM) and vacuum bag (BlueBAGTM) may increase the surface dose and skin toxicity. This study investigated the influence of couch and vacuum bag on the surface dose. METHODS: The relative surface dose (D0 /DMAX) was measured in an ion-chamber (Markus-type PTW, 0...
June 2016: Medical Physics
G Ding
PURPOSE: Recently a new 2.5 megavoltage imaging beam has become available in a TrueBeam linear accelerator for image guidance. There is limited information available related to the beam characteristics. Commissioning dosimetric data of the new imaging is necessary for configuration of the beam in a treatment planning system in order to calculate imaging doses to patients resulting from this new imaging beam. The purpose of this study is to provide measured commissioning data recommended for a beam configuration in a treatment planning system...
June 2016: Medical Physics
J D Azcona, J Burguete, B Barbes, J Aristu, M Moreno, A Zubiria, P Arce, J I Lagares
PURPOSE: To calculate the total planning dose on lung tumors (GTV) by accumulating the dose received in all respiration phases. METHODS: A patient 4D planning CT (phase-binned, from a Siemens Somatom CT) was used to locate the GTV of a lung tumor in all respiratory phases with Pinnacle (v9.10). GTV contours defined in all phases were projected to the reference phase, where the ITV was defined. Centroids were calculated for all the GTV projections. No deformation or rotation was taken into account...
June 2016: Medical Physics
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