Flattening filter free (FFF) beams are now commonly available with new standard linear accelerators. These beams have recognised clinical advantages in certain circumstances, most notably the reduced beam-on times for high dose per fraction stereotactic treatments. Therefore FFF techniques are quickly being introduced into clinical use. The purpose of this report is to provide practical implementation advice and references for centres implementing FFF beams clinically. In particular UK-specific guidance is given for reference dosimetry and radiation protection.
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http://dx.doi.org/10.1088/0031-9155/61/23/8360 | DOI Listing |
Radiat Environ Biophys
January 2025
Radiation Physics, Faculty of Science, Al -Azhar University, Cairo, Egypt.
This study aimed to evaluate the dosimetric and clinical outcomes of flattening filter (FF) versus flattening filter-free (FFF) beams in head and neck cancer (HNC) patients treated with volumetric modulated arc therapy (VMAT). Twenty-four patients with 70/59.4/54 Gy dose prescribed in 33 fractions with simultaneous integrated boost treatment were retrospectively analyzed to compare treatment delivery efficiency, target coverage, sparing of organs at risk (OARs), and remaining volume at risk (RVR) in two HNC groups (nasopharyngeal and oropharyngeal).
View Article and Find Full Text PDFBiomed Phys Eng Express
January 2025
Mindanao Radiation Physics Center, MSU-Iligan Institute of Technology, Andres Bonifacio Street Tibanga, Iligan City, Lanao Norte, 9200, PHILIPPINES.
To accurately model and validate the 6 MV Elekta Compactlinear accelerator using the Geant4 Application for Tomographic Emission (GATE). In particular, this study focuses on the precise calibration and validation of critical parameters, including jaw collimator positioning, electron source nominal energy, flattening filter geometry, and electron source spot size, which are often not provided in technical documentation. Methods: Simulation of the Elekta Compact6 MV linear accelerator was performed using the Geant4 Application for Tomographic Emission (GATE) v.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045.
Climate change is increasing the frequency of large-scale, extreme environmental events and flattening environmental gradients. Whether such changes will cause spatially synchronous, large-scale population declines depends on mechanisms that limit metapopulation synchrony, thereby promoting rescue effects and stability. Using long-term data and empirical dynamic models, we quantified spatial heterogeneity in density dependence, spatial heterogeneity in environmental responses, and environmental gradients to assess their role in inhibiting synchrony across 36 marine fish and invertebrate species.
View Article and Find Full Text PDFJ Appl Clin Med Phys
January 2025
Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands.
Introduction: This paper describes a method to improve gantry-dependent beam steering for Elekta traveling wave linear accelerators by applying the measured and filtered beam servo corrections to the existing lookup table (LUT). Beam steering has a direct influence on the treatment accuracy by affecting the beam symmetry and position. The presented method provides an improved LUT with respect to the default Elekta method to reduce treatment delivery interruptions.
View Article and Find Full Text PDFPituitary
December 2024
Dipartimento di Medicina Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy.
Introduction: Empty sella is characterized by a flattened profile of the pituitary gland that represents in most cases only a radiological incidental finding. When endocrine, ophthalmic, and neurological symptoms occur, this condition is described as empty sella syndrome.
Materials And Methods: We searched MEDLINE (PubMed database) with the data filter 2024-2009 using the keywords listed above.
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