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https://www.readbyqxmd.com/read/28915893/dosimetric-comparison-of-different-treatment-modalities-for-stereotactic-radiotherapy
#1
Shih-Ming Hsu, Yuan-Chun Lai, Chien-Chung Jeng, Chia-Ying Tseng
BACKGROUND: The modalities for performing stereotactic radiotherapy (SRT) on the brain include the cone-based linear accelerator (linac), the flattening filter-free (FFF) volumetric modulated arc therapy (VMAT) linac, and tomotherapy. In this study, the cone-based linac, FFF-VMAT linac, and tomotherapy modalities were evaluated by measuring the differences in doses delivered during brain SRT and experimentally assessing the accuracy of the output radiation doses through clinical measurements...
September 16, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28899649/small-field-characterization-of-a-nanochamber-prototype-under-flattening-filter-free-photon-beams
#2
G Reggiori, A Stravato, P Mancosu, F Lobefalo, L Paganini, F Zucconi, V Palumbo, A Gaudino, M Scorsetti, S Tomatis
INTRODUCTION: Nanochambers present some advantages in terms of energy independence and absolute dose measurement for small field dosimetry in the SBRT scenario. Characterization of a micro-chamber prototype was carried out both under flattened and flattening-filter-free (FFF) beams with particular focus on stem effect. METHODS: The study included characterization of leakage and stem effects, dose rate and dose per pulse dependence, measurement of profiles, and percentage depth doses (PDDs)...
September 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28887827/a-universal-parameterized-gradient-based-method-for-photon-beam-field-size-determination
#3
Sharon Lebron, Guanghua Yan, Jonathan Li, Bo Lu, Chihray Liu
PURPOSE: To propose a universal, parameterized gradient-based method (PGM) for radiation field size determination. METHODS: The PGM locates the beam profile's edge by parameterizing its penumbra region with a modified sigmoid function where the inflection point can be determined in a closed form. The parametrization was validated with filter-flattened (FF), flattening-filter-free (FFF) and wedged profiles measured on two Elekta linac models (Synergy and Versa HD)...
September 9, 2017: Medical Physics
https://www.readbyqxmd.com/read/28870945/flattening-filter-free-vs-flattened-beams-for-lung-stereotactic-body-radiation-therapy
#4
Pierre Annede, Julien Darreon, Ahcene Benkemouche, Simon Valdenaire, Marguerite Tyran, Bertrand Kaeppelin, Alban Macagno, Julien Barrou, Leonel Varela Cagetti, Veronique Favrel, Laurence Moureau-Zabotto, Laurence Gonzague, Pierre Fau, Cyrus Chargari, Agnes Tallet, Naji Salem
BACKGROUND/AIM: To assess the clinical impact of high dose rate stereotactic body radiation therapy (SBRT) in patients with lung neoplastic lesions. PATIENTS AND METHODS: From January 2014 to June 2016, a single-center retrospective analysis was performed including all patients treated by either flattening filter free (FFF) beams or flattening filter beams (FF) three-dimensional (3D) SBRT for lung neoplastic lesions. RESULTS: A total of 99 SBRT were performed on 75 patients...
September 2017: Anticancer Research
https://www.readbyqxmd.com/read/28857432/volumetric-modulated-arc-therapy-and-intensity-modulated-radiation-therapy-treatment-planning-for-prostate-cancer-with-flattened-beam-and-flattening-filter-free-linear-accelerators
#5
Marius Treutwein, Matthias Hipp, Oliver Koelbl, Barbara Dobler
This study on patients with localized prostate cancer was set up to investigate valuable differences using flattened beam (FB) and flattening filter free (FFF) mode in the application of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). For ten patients, four different plans were calculated with Oncentra planning system of Elekta, using Synergy machines: IMRT and VMAT, with and without flattening filter. Homogeneity and conformity indexes, dose to the organs at risk, and measurements of peripheral dose and dosimetric plan verification including record of the delivery times were analyzed and statistically evaluated...
August 30, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28771143/equivalent-uniform-square-field-sizes-of-flattening-filter-free-photon-beams
#6
Wolfgang Lechner, Peter Kuess, Dietmar Georg, Hugo Palmans
Various types of treatment units, such as CyberKnife, TomoTherapy and C-arm linear accelerators (LINACs) are operated using flattening filter free (FFF) photon beams. Their reference dosimetry, however, is currently based on codes of practice that provide data which were primarily developed and tested for high-energy photon beams with flattening filter (WFF). The aim of this work was to introduce equivalent uniform square field sizes of FFF beams to serve as a basis of a unified reference dosimetry procedure applicable to all aforementioned FFF machines...
September 15, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28736809/dose-evaluation-of-grid-therapy-using-a-6-mv-flattening-filter-free-fff-photon-beam-a-monte-carlo-study
#7
Immaculada Martínez-Rovira, Josep Puxeu-Vaqué, Yolanda Prezado
PURPOSE: Spatially fractionated radiotherapy is a strategy to overcome the main limitation of radiotherapy, i.e., the restrained normal tissue tolerances. A well-known example is Grid Therapy, which is currently performed at some hospitals using megavoltage photon beams delivered by Linacs. Grid Therapy has been successfully used in the management of bulky abdominal tumors with low toxicity. The aim of this work was to evaluate whether an improvement in therapeutic index in Grid Therapy can be obtained by implementing it in a flattening filter-free (FFF) Linac...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28714067/evaluation-of-plastic-scintillator-detector-for-small-field-stereotactic-patient-specific-quality-assurance
#8
Yujiao Qin, Stephen J Gardner, Joshua Kim, Yimei Huang, Ning Wen, Anthony Doemer, Indrin J Chetty
PURPOSE: To evaluate the performance of a commercial plastic scintillator detector (PSD) for small-field stereotactic patient-specific quality assurance (QA) measurements using flattening-filter-free beam. METHODS: A total of ten spherical targets (volume range: [0.03cc-2cc]) were planned with two techniques: (1) Dynamic Conformal Arc (DCA-10 plans), and (2) Volumetric Modulated Arc Therapy (VMAT-10 plans). All plans were generated using Varian Eclipse treatment planning system, and AcurosXB v...
July 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28711480/commissioning-of-small-field-size-radiosurgery-cones-in-a-6-mv-flattening-filter-free-beam
#9
Juan Diego Azcona, Benigno Barbés, Verónica Morán, Javier Burguete
This study aimed to describe the commissioning of small field size radiosurgery cones in a 6-MV flattening filter free (FFF) beam and report our measured values. Four radiosurgery cones of diameters 5, 10, 12.5, and 15 mm supplied by Elekta Medical were commissioned in a 6-MV FFF beam from an Elekta Versa linear accelerator. The extraction of a reference signal for measuring small fields in scanning mode is challenging. A transmission chamber was attached to the lower part of the collimators and used for percentage depth dose (PDD) and profile measurements in scanning mode with a stereotactic diode...
July 12, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28711479/identification-of-the-suitable-leaf-margin-for-liver-stereotactic-body-radiotherapy-with-flattening-filter-free-beams
#10
Toshiyuki Ogata, Hideki Nishimura, Hiroshi Mayahara, Kazuyuki Uehara, Takanobu Okayama
The purpose of this study is to identify the suitable leaf margin for liver stereotactic body radiotherapy (SBRT) with flattening filter-free (FFF) beams, as compared with that with flattening filter (FF) beams. SBRT treatment planning for 10 patients with liver cancer was performed using 10-MV FFF and FF beams obtained from a Varian TrueBeam (Varian Medical Systems, Palo Alto, CA) linear accelerator. Each plan was generated with the leaf margin to the planning target volume (PTV) ranging from -3 to 5 mm...
July 12, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28706351/beam-characterization-of-10-mv-photon-beam-from-medical-linear-accelerator-without-flattening-filter
#11
Tomohiro Shimozato, Yuichi Aoyama, Takuma Matsunaga, Katsuyoshi Tabushi
AIM: This work investigated the dosimetric properties of a 10-MV photon beam emitted from a medical linear accelerator (linac) with no flattening filter (FF). The aim of this study is to analyze the radiation fluence and energy emitted from the flattening filter free (FFF) linac using Monte Carlo (MC) simulations. MATERIALS AND METHODS: The FFF linac was created by removing the FF from a linac in clinical use. Measurements of the depth dose (DD) and the off-axis profile were performed using a three-dimensional water phantom with an ionization chamber...
April 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28679448/simultaneous-integrated-boost-therapy-of-carcinoma-of-the-hypopharynx-larynx-with-and-without-flattening-filter-a-treatment-planning-and-dosimetry-study
#12
Barbara Dobler, Tina Obermeier, Matthias G Hautmann, Amine Khemissi, Oliver Koelbl
BACKGROUND: The aim of this study was to investigate if the flattening filter free (FFF) irradiation mode of a linear accelerator (linac) is advantageous as compared to the flat beam (FF) irradiation mode in intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for carcinoma of the hypopharynx / larynx. METHODS: Four treatment plans were created for each of 10 patients for an Elekta Synergy linac with Agility collimating device, a dual arc VMAT and a nine field step and shoot IMRT each with and without flattening filter...
July 5, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28666901/characterization-of-the-effect-of-a-new-commercial-transmission-detector-on-radiation-therapy-beams
#13
Joey P Cheung, Angelica Perez-Andujar, Olivier Morin
PURPOSE: To evaluate the influence of a new commercial transmission detector on radiation therapy beams. METHODS AND MATERIALS: A transmission detector designed for online treatment monitoring was characterized on a TrueBeam STx linear accelerator with 6-MV, 6-flattening filter free, 10-MV, and 10-flattening filter free beams. Measurements of percentage depth doses, in-plane and cross-plane off-axis profiles at different depths, transmission factors, and skin dose were acquired with 3 × 3, 5 × 5, 10 × 10, 20 × 20, and 40 × 40 cm(2) field sizes at 100 cm and 80 cm source-to-surface distance (SSD)...
April 9, 2017: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28657114/development-of-a-flattening-filter-free-multiple-source-model-for-use-as-an-independent-monte-carlo-dose-calculation-quality-assurance-tool-for-clinical-trials
#14
Austin M Faught, Scott E Davidson, Richard Popple, Stephen F Kry, Carol Etzel, Geoffrey S Ibbott, David S Followill
PURPOSE: The Imaging and Radiation Oncology Core - Houston (IROC-H) Quality Assurance Center (formerly the Radiological Physics Center) has reported varying levels of compliance from their anthropomorphic phantom auditing program. IROC-H studies have suggested that one source of disagreement between institution submitted calculated doses and measurement is the accuracy of the institution's treatment planning system dose calculations and heterogeneity corrections used. In order to audit this step of the radiation therapy treatment process, an independent dose calculation tool is needed...
June 28, 2017: Medical Physics
https://www.readbyqxmd.com/read/28610696/use-of-ptw-microdiamond-for-relative-dosimetry-of-unflattened-photon-beams
#15
Giacomo Reggiori, Antonella Stravato, Maria Pimpinella, Francesca Lobefalo, Vanessa De Coste, Antonella Fogliata, Pietro Mancosu, Fiorenza De Rose, Valentina Palumbo, Marta Scorsetti, Stefano Tomatis
PURPOSE: The increasing interest in SBRT treatments encourages the use of flattening filter free (FFF) beams. Aim of this work was to evaluate the performance of the PTW60019 microDiamond detector under 6MV and 10MVFFF beams delivered with the EDGE accelerator (Varian Medical System, Palo Alto, USA). A flattened 6MV beam was also considered for comparison. METHODS: Short term stability, dose linearity and dose rate dependence were evaluated. Dose per pulse dependence was investigated in the range 0...
June 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28595775/surface-dose-measurements-in-and-out-of-field-implications-for-breast-radiotherapy-with-megavoltage-photon-beams
#16
Peta Lonski, Prabhakar Ramachandran, Rick Franich, Tomas Kron
This study examines the difference in surface dose between flat and flattening filter free (FFF) photon beams in the context of breast radiotherapy. The surface dose was measured for 6MV, 6MV FFF, 10MV, 10MV FFF and 18MV photon beams using a thin window ionisation chamber for various field sizes. Profiles were acquired to ascertain the change in surface dose off-axis. Out-of-field measurements were included in a clinically representative half beam block tangential breast field. In the field centres of FFF beams the surface dose was found to be increased for small fields and decreased for large fields compared to flat beams...
June 5, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28587007/clinical-outcomes-of-stereotactic-body-radiation-therapy-using-flattening-filter-free-fff-in-early-non-small-cell-lung-cancers-and-metastatic-lung-cancers
#17
S Kitpanit, A Songthong, C Chakkabat, N Amornwichet, P Alisanant, C Nantavithya, C Lertbutsayanukul, K Shotelersuk, C Khorprasert, D Kannarunimit
No abstract text is available yet for this article.
May 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28574219/optimization-of-the-dosimetric-leaf-gap-for-use-in-planning-vmat-treatments-of-spine-sabr-cases
#18
Nigel D Middlebrook, Bess Sutherland, Tanya Kairn
The dosimetric leaf gap (DLG) is a beam configuration parameter used in the Varian Eclipse treatment planning system, to model the effects of rounded MLC leaf ends. Measuring the DLG using the conventional sliding-slit technique has been shown to be produce questionable results for some volumetric modulated arc therapy (VMAT) treatments. This study therefore investigated the use of radiochromic film measurements to optimize the DLG specifically for the purpose of producing accurate VMAT plans using a flattening-filter-free (FFF) beam, for use in treating vertebral targets using a stereotactic (SABR, also known as SBRT) fractionation schedule...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574211/comparison-of-the-recommendations-of-the-aapm-tg-51-and-tg-51-addendum-reference-dosimetry-protocols
#19
Travis J McCaw, Min-Sig Hwang, Si Young Jang, M Saiful Huq
This work quantified differences between recommendations of the TG-51 and TG-51 addendum reference dosimetry protocols. Reference dosimetry was performed for flattened photon beams with nominal energies of 6, 10, 15, and 23 MV, as well as flattening-filter free (FFF) beam energies of 6 and 10 MV, following the recommendations of both the TG-51 and TG-51 addendum protocols using both a Farmer(®) ionization chamber and a scanning ionization chamber with calibration coefficients traceable to absorbed dose-to-water (Dw ) standards...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28521451/dosimetric-comparison-of-intensity-modulated-radiation-therapy-and-volumetric-modulated-arc-therapy-plans-for-the-treatment-of-glioma-using-flattening-filter-free-and-flattening-filter-modes
#20
Dandan Xu, Fei Jia, Guowen Li, Hongfei Li
In the present study, the dose verification between 6X and 6X flattening filter-free (FFF) in intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) was compared, and the advantages and disadvantages of different radiotherapy plans were evaluated. All four plans achieved comparable heterogeneity and conformity indices. For frontal tumor, VMAT demonstrated more improved sparing of the brainstem compared with the IMRT (P=0.045); while in the model of FFF, the Dmax of eye lens was significantly reduced by 16-21% (P<0...
May 2017: Oncology Letters
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