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flattening filter free

Sarah O S Osman, Prakash Jeevanandam, Nithya Kanakavelu, Denise M Irvine, Ciara A Lyons, Suneil Jain, Alan R Hounsell, Conor K McGarry
BACKGROUND: The purpose of this study is to find the optimal planning settings for prostate SABR-VMAT for high-risk prostate cancer patients irradiated to prostate only (PO) or prostate and pelvic lymph nodes (PPLN). METHODS: For 10 patients, plans using 6MV flattened, flattening-filter-free (FFF) 6MV (6 F) and FFF 10MV (10 F) photon beams with full and partial arc arrangements were generated and compared. The prescribed dose was 40Gy to the prostate with 25Gy to the PLN in 5 fractions...
November 24, 2016: Radiation Oncology
Silvia Strolin, Silvia Minosse, Marco D'Andrea, Francesco Fracchiolla, Vicente Bruzzaniti, Stefano Luppino, Marcello Benassi, Lidia Strigari
PURPOSE: To investigate the applicability of the formalism described in BJR supplement n.25 for Flattening Filter Free (FFF) beams in determining the zero-field tissue maximum ratio (TMR) for an independent calculation method of Percentage Depth Doses (PDDs) and relative dose factors (RDFs) at different experimental setups. METHODS: Experimental PDDs for field size from 40×40cm(2) to 2×2cm(2) with Source Surface Distance (SSD) 100cm were acquired. The normalized peak scatter factor for each square field was obtained by fitting experimental RDFs in water and collimator factors (CFs) in air...
November 18, 2016: Physica Medica: PM
Youqun Lai, Shanyu Chen, Changdong Xu, Liwan Shi, Lirong Fu, Huiming Ha, Qin Lin, Zhen Zhang
For single-fraction stereotactic radiosurgery (SRS) using linac in brain metastases, more accurate treatment delivery with higher tumor absorbed doses and lower absorbed doses to normal tissues remains an enormous challenge. The purpose of this study was to investigate the dosimetric superiority in flattening filter free beams (FFF) for volumetric modulated arc therapy (VMAT) in single brain metastasis. 68 patients with single brain metastasis were included in this study. Every patient was subjected to VMAT treatment plans using 6 MV standard flattened (FF) beams (VMAT_FF) and 6 MV FFF beams (VMAT_FFF) with single fraction doses of 20 Gy...
November 3, 2016: Oncotarget
Geoff Budgell, Kirstie Brown, Jason Cashmore, Simon Duane, John Frame, Mark Hardy, David Paynter, Russell Thomas
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...
December 7, 2016: Physics in Medicine and Biology
Lalit Kumar, Girigesh Yadav, Kothanda Raman Samuvel, Manindra Bhushan, Pawan Kumar, Mahammood Suhail, Manoj Pal
AIM: To investigate the dosimetric influence of filtered and flattening filter free (FFF) photon beam of 6 and 10 MV energies on cervix RA radiotherapy planning and to find possibilities to develop the clinically acceptable RA plans with FFFB photon beam and explore their potential benefits to cervix cancer patients. BACKGROUND: FFF photon beams enhances the treatment delivery by increased dose rate which results in shorter treatment time, this shorter treatment time reduces intrafraction motion and enhance comfort to the patients...
January 2017: Reports of Practical Oncology and Radiotherapy
Chang Heon Choi, So-Yeon Park, Jung-In Kim, Jin Ho Kim, Kyubo Kim, Joel Carlson, Jong Min Park
OBJECTIVES: To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) plans for spine stereotactic ablative radiotherapy (SABR). METHODS: A total of 20 patients with spine metastasis were retrospectively selected. For each patient, a tri-Co-60 IMRT plan and a volumetric modulated arc therapy (VMAT) plan were generated. The spinal cords were defined based on magnetic resonance images for the tri-Co-60 IMRT, while isotropic 1 mm margins were added to the spinal cords for the VMAT plans...
October 26, 2016: British Journal of Radiology
Laure Vieillevigne, Sandra Bessieres, Monia Ouali, Christel Lanaspeze
PURPOSE: Flattening filter free (FFF) beams are frequently used for stereotactic body radiation therapy with various treatment modalities: conventional static fields, dynamic conformal arc (DCA) or Rapid Arc (RA). The goal of this study was to obtain some criteria to enable a conscious choice of the employment of FFF beams and of the DCA or RA technique, depending on the PTV size. METHODS AND MATERIALS: 24 PTVs from 1.52cm(3) to 445.24cm(3) were studied in various sites: virtual phantom, lung and liver...
November 2016: Physica Medica: PM
Sara Barbiero, Alexandra Rink, Fabrizio Matteucci, David Fedele, Fabiola Paiar, Francesco Pasqualetti, Michele Avanzo
PURPOSE: To report on single-fraction stereotactic body radiotherapy (RT) (SBRT) with flattening filter (FF)-free (FFF) volumetric modulated arc therapy (VMAT) for lung cancer and to compare dosimetric results with VMAT with FF. METHODS AND MATERIALS: Overall, 25 patients were treated with 6-MV FFF VMAT (Varian TrueBeam STx LINAC) to a prescribed dose of 24Gy in a single fraction. Treatment plans were recreated using FF VMAT. Dose-volume indices, monitor units (MU), and treatment times were compared between FFF and FF VMAT techniques...
October 14, 2016: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
Katharina Bell, Jochen Fleckenstein, Frank Nuesken, Norbert Licht, Christian Rübe, Yvonne Dzierma
BACKGROUND: The recently implemented mARC-rotation-technique is capable to deliver high dose rate bursts. For the case of hypopharynx cancer plans we evaluate whether the mARC can achieve an advantage in treatment time in comparison to IMRT. These plans consider two arcs with flat and flattening filter free (FFF) beam energies. MATERIALS AND METHODS: For 8 hypopharynx-cancer patients step-and-shoot-IMRT and mARC plans were created retrospectively using flat and FFF beam energy...
2016: PloS One
Jin Beom Chung, Sang Won Kang, Keun Yong Eom, Changhoon Song, Kyoung Sik Choi, Tae Suk Suh
The purpose of this study was to compare the performance of different commercial quality assurance (QA) systems for the pretreatment verification plan of stereotactic body radiotherapy (SBRT) with volumetric arc therapy (VMAT) technique using a flattening-filter-free beam. The verification for 20 pretreatment cancer patients (seven lung, six spine, and seven prostate cancers) were tested using three QA systems (EBT3 film, I'mRT MatriXX array, and MapCHECK). All the SBRT-VMAT plans were optimized in the Eclipse (version 11...
November 2016: Journal of Korean Medical Science
Ilma Xhaferllari, Omar El-Sherif, Stewart Gaede
Volumetric-modulated arc therapy (VMAT) is emerging as a leading technology in treating early-stage, non-small cell lung cancer (NSCLC) with stereotactic ablative radiotherapy (SABR). However, two other modalities capable of deliver-ing intensity-modulated radiation therapy (IMRT) include fixed-beam and helical TomoTherapy (HT). This study aims to provide an extensive dosimetric compari-son among these various IMRT techniques for treating early-stage NSCLC with SABR. Ten early-stage NSCLC patients were retrospectively optimized using three fixed-beam techniques via nine to eleven beams (high and low modulation step-and-shoot (SS), and sliding window (SW)), two VMAT techniques via two partial arcs (SmartArc (SA) and RapidArc (RA)), and three HT techniques via three different fan beam widths (1 cm, 2...
2016: Journal of Applied Clinical Medical Physics
Jason Cashmore
As the use of linear accelerators operating in flattening filter-free (FFF) modes becomes more widespread, it is important to have an understanding of the surface doses delivered to patients with these beams. Flattening filter removal alters the beam quality and relative contributions of low-energy X-rays and contamination electrons in the beam. Having dosimetric data to describe the surface dose and buildup regions under a range of conditions for FFF beams is important if clinical decisions are to be made...
2016: Journal of Applied Clinical Medical Physics
J M Park, J I Kim, S Y Park, H J Kim, H G Wu
No abstract text is available yet for this article.
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
Lei Wang, Benjamin Fahimian, Scott G Soltys, Paul Zei, Anthony Lo, Edward A Gardner, Patrick J Maguire, Billy W Loo
PURPOSE: The first stereotactic arrhythmia radioablation (STAR) of ventricular tachycardia (VT) was delivered at Stanford on a robotic radiosurgery system (CyberKnife® G4) in 2012. The results warranted further investigation of this treatment. Here we compare dosimetrically three possible treatment delivery platforms for STAR. METHODS: The anatomy and target volume of the first treated patient were used for this study. A dose of 25 Gy in one fraction was prescribed to the planning target volume (PTV)...
2016: Curēus
E Sterpin
In typical treatment planning of 3D IMRT, the incident energy fluence is optimized to achieve a homogeneous dose distribution to the PTV. The PTV includes the tumour but also healthy tissues that may have a different dose response for the same incident energy fluence, like bony structures included in the PTV (mandibles in head and neck tumours or femoral bones in sarcomas). Dose to medium optimization compensates for this heterogeneous response, leading to a non-homogeneous energy fluence in the PTV and a non-homogeneous dose in the CTV in the presence of geometric errors...
September 2016: Physica Medica: PM
Barbara Dobler, Johannes Maier, Bernadette Knott, Manuel Maerz, Rainer Loeschel, Oliver Koelbl
BACKGROUND: The aim of this study was to investigate if the flattening filter free mode (FFF) of a linear accelerator reduces the excess absolute risk (EAR) for second cancer as compared to the flat beam mode (FF) in simultaneous integrated boost (SIB) radiation therapy of right-sided breast cancer. PATIENTS AND METHODS: Six plans were generated treating the whole breast to 50.4 Gy and a SIB volume to 63 Gy on CT data of 10 patients: intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and a tangential arc VMAT (tVMAT), each with flattening filter and without...
October 2016: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
E L Covington, T A Ritter, J M Moran, A M Owrangi, J I Prisciandaro
PURPOSE: To develop a comprehensive peripheral dose (PD) dataset for the two unflattened beams of nominal energy 6 and 10 MV for use in clinical care. METHODS: Measurements were made in a 40 × 120 × 20 cm(3) (width × length × depth) stack of solid water using an ionization chamber at varying depths (dmax, 5, and 10 cm), field sizes (3 × 3 to 30 × 30 cm(2)), and distances from the field edge (5-40 cm). The effects of the multileaf collimator (MLC) and collimator rotation were also evaluated for a 10 × 10 cm(2) field...
August 2016: Medical Physics
Ruggero Ruggieri, Stefania Naccarato, Pavel Stavrev, Nadejda Stavreva, Stefano Pasetto, Ignazio Salamone, Filippo Alongi
PURPOSE: To estimate and correct for the volume averaging effect which results from the intra-chamber dose gradients when a Farmer ionization chamber (IC) is used for reference dosimetry in flattening-filter-free (FFF) MV photon beams. METHODS: An intra-chamber dose gradients correction factor (kicdg) to the charge reading of a Farmer IC is estimated by comparison to a small volume IC (∼0.1 cm(3)), in the FFF beams of a TrueBeam™ (Varian, Inc.) linear accelerators...
August 2016: Medical Physics
Ergun E Ahunbay, O Ates, X A Li
PURPOSE: In a situation where a couch shift for patient positioning is not preferred or prohibited (e.g., MR-linac), segment aperture morphing (SAM) can address target dislocation and deformation. For IMRT/VMAT with flattening-filter-free (FFF) beams, however, SAM method would lead to an adverse translational dose effect due to the beam unflattening. Here the authors propose a new two-step process to address both the translational effect of FFF beams and the target deformation. METHODS: The replanning method consists of an offline and an online step...
August 2016: Medical Physics
Peter Kuess, Dietmar Georg, Hugo Palmans, Wolfgang Lechner
PURPOSE: For commercially available linear accelerators (Linacs), the electron energies of flattening filter free (FFF) and flattened (FF) beams are either identical or the electron energy of the FFF beam is increased to match the percentage depth dose curve (PDD) of the FF beam (in reference geometry). This study focuses on the primary dose components of FFF beams for both kinds of settings, studied on the same Linac. METHODS: The measurements were conducted on a VersaHD Linac (Elekta, Crawley, UK) for both FF and FFF beams with nominal energies of 6 and 10 MV...
August 2016: Medical Physics
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