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flattening filter free

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...
October 15, 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
Eduardo Pardo, Juan Castro Novais, María Yolanda Molina López, Sheila Ruiz Maqueda
Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C-Arm linacs for intensity-modulated treatments. This mode, called flattening filter-free (FFF), offers the advantage of a greater dose rate. Varian's "Portal Dosimetry" is an electronic portal imager device (EPID)-based tool for IMRT verification. This tool lacks the capability of verifying flattening filter-free (FFF) modes due to saturation and lack of an image prediction algorithm. (Note: the latest versions of this software and EPID correct these issues...
2016: Journal of Applied Clinical Medical Physics
Juliane Rieber, Eric Tonndorf-Martini, Oliver Schramm, Bernhard Rhein, Laila König, Sebastian Adeberg, Eva Meyerhof, Angela Mohr, Jutta Kappes, Hans Hoffmann, Jürgen Debus, Stefan Rieken
BACKGROUND: Stereotactic body radiotherapy (SBRT) using flattening filter free (FFF)-techniques has been increasingly applied during the last years. However, clinical studies investigating this emerging technique are still rare. Hence, we analyzed toxicity and clinical outcome of pulmonary SBRT with FFF-techniques and performed dosimetric comparison to conventional techniques using flattening filters (FF). MATERIALS AND METHODS: Between 05/2014 and 06/2015, 56 consecutive patients with 61 pulmonary lesions were treated with SBRT in FFF-mode...
2016: Radiation Oncology
G D'Agostino, C Franzese, F De Rose, D Franceschini, T Comito, E Villa, F Alongi, R Liardo, S Tomatis, P Navarria, P Mancosu, G Reggiori, L Cozzi, M Scorsetti
AIMS: The aim of this phase II study was to evaluate the efficacy and toxicity of stereotactic body radiotherapy in patients with low or intermediate risk prostate cancer. MATERIALS AND METHODS: Biopsy-confirmed prostate cancer patients were enrolled, provided that they had the following characteristics: initial prostate-specific antigen (PSA) ≤ 20 ng/ml, Gleason Score < 7, International Prostate Symptom Score < 7. The treatment schedule was 35 Gy in five fractions, delivered with volumetric modulated arcs with flattening filter free beams...
July 4, 2016: Clinical Oncology: a Journal of the Royal College of Radiologists
J Rieber, E Tonndorf-Martini, O Schramm, B Rhein, S Stefanowicz, J Kappes, H Hoffmann, K Lindel, J Debus, S Rieken
BACKGROUND: Radiosurgical treatment of brain metastases is well established in daily clinical routine. Utilization of flattening-filter-free beams (FFF) may allow for more rapid delivery of treatment doses and improve clinical comfort. Hence, we compared plan quality and efficiency of radiosurgery in FFF mode to FF techniques. MATERIALS AND METHODS: Between November 2014 and June 2015, 21 consecutive patients with 25 brain metastases were treated with stereotactic radiosurgery (SRS) in FFF mode...
July 4, 2016: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
J E Lye, D J Butler, C P Oliver, A Alves, J Lehmann, F P Gibbons, I M Williams
Dosimetry protocols for external beam radiotherapy currently in use, such as the IAEA TRS-398 and AAPM TG-51, were written for conventional linear accelerators. In these accelerators, a flattening filter is used to produce a beam which is uniform at water depths where the ionization chamber is used to measure the absorbed dose. Recently, clinical linacs have been implemented without the flattening filter, and published theoretical analysis suggested that with these beams a dosimetric error of order 0.6% could be expected for IAEA TRS-398, because the TPR20,10 beam quality index does not accurately predict the stopping power ratio (water to air) for the softer flattening-filter-free (FFF) beam spectra...
July 21, 2016: Physics in Medicine and Biology
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