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https://www.readbyqxmd.com/read/29338305/safety-and-feasibility-of-prostate-stereotactic-ablative-radiotherapy-using-multi-modality-imaging-and-flattening-filter-free
#1
Aileen Duffton, Azmat Sadozye, Lynsey Devlin, Nicholas MacLeod, Carolynn Lamb, Suzanne Smith, Philip McLoone, Muthu Sankaralingam, John Foster, Stephanie Paterson, Stefanie Keatings, David Dodds
PURPOSE: To investigate feasibility and safety of SABR in the management of prostate cancer while employing MR/CT fusion for delineation, fiducial markers seeds for positioning and Varian Rapidarc with FFF delivery. METHODS: Forty-one patients were treated for low-intermediate risk prostate cancer with initial PSA (iPSA) of ≤20ng/ml, Gleason score 6-7. Patients had MR/CT fusion for delineation of prostate +/-seminal vesicles. CT/MR fusion images were used for delineation and planned using flattening filter free modality...
January 17, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29258539/critical-appraisal-of-the-role-of-volumetric-modulated-arc-therapy-in-the-radiation-therapy-management-of-breast-cancer
#2
REVIEW
Luca Cozzi, Frank Lohr, Antonella Fogliata, Davide Franceschini, Fiorenza De Rose, A R Filippi, Gabriele Guidi, Valentina Vanoni, Marta Scorsetti
BACKGROUND: The aim of this review is the critical appraisal of the current use of volumetric modulated arc therapy for the radiation therapy management of breast cancer. Both clinical and treatment planning studies were investigated. MATERIAL AND METHODS: A Pubmed/MEDLINE search of the National Library of Medicine was performed to identify VMAT and breast related articles. After a first order rejection of the irrelevant findings, the remaining articles were grouped according to two main categories: clinical vs...
December 19, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/29243663/characterization-of-compton-scatter-imaging-with-an-analytical-simulation-method
#3
Kevin C Jones, Gage Redler, Alistair Templeton, Damian Bernard, Julius V Turian, James C H Chu
By collimating the photons scattered when a megavoltage therapy beam interacts with the patient, a Compton-scatter image may be formed without the delivery of extra dose. To characterize and assess the potential of the technique, an analytical model for simulating scatter images was developed and validated against Monte Carlo (MC). For three phantoms, the scatter images collected during irradiation with a 6 MV flattening-filter-free therapy beam were simulated. Images, profiles, and spectra were compared for different phantoms and different irradiation angles...
December 15, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29218841/improvement-of-conformal-arc-plans-by-using-deformable-margin-delineation-method-for-stereotactic-lung-radiotherapy
#4
Görkem Güngör, Melek Demir, Gökhan Aydın, Bülent Yapıcı, Banu Atalar, Enis Özyar
PURPOSE: Stereotactic body radiotherapy (SBRT) is an established treatment technique in the management of medically inoperable early stage non-small cell lung cancer (NSCLC). Different techniques such as volumetric modulated arc (VMAT) and three-dimensional conformal arc (DCA) can be used in SBRT. Previously, it has been shown that VMAT is superior to DCA technique in terms of plan evaluation parameters. However, DCA technique has several advantages such as ease of use and considerable shortening of the treatment time...
December 7, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29172266/dosimetric-validation-of-volumetric-modulated-arc-therapy-vmat-using-aapm-tg-119-benchmark-plans-in-an-upgraded-clinac-2100cd-for-flattening-filter-free-fff-photon-beams
#5
Ashokkumar Sangaiah, K M Ganesh, K Ramalingam, K Karthikeyan, N Jagadheeskumar
Background: Recently we have upgraded our Varian Clinac 2100CD with a 6MV FFF beam, this upgrade being the first of its kind in our country. Even though the dosimetric characteristics of FFF beams have been reported both in experimental and Monte Carlo studies, application in planning and delivery is complex. The aim of this study was to validate the commissioning of upgraded FFF beams dosimetrically using AAPM TG-119 bench mark plans for VMAT and to make a comparison with IMRT plans for both flattened filtered and FFF beams...
November 26, 2017: Asian Pacific Journal of Cancer Prevention: APJCP
https://www.readbyqxmd.com/read/29152898/tolerance-levels-of-ct-number-to-electron-density-table-for-photon-beam-in-radiotherapy-treatment-planning-system
#6
Minoru Nakao, Shuichi Ozawa, Kiyoshi Yamada, Katsunori Yogo, Fumika Hosono, Masahiro Hayata, Akito Saito, Kentaro Miki, Takeo Nakashima, Yusuke Ochi, Daisuke Kawahara, Yoshiharu Morimoto, Toru Yoshizaki, Hiroshige Nozaki, Kosaku Habara, Yasushi Nagata
The accuracy of computed tomography number to electron density (CT-ED) calibration is a key component for dose calculations in an inhomogeneous medium. In a previous work, it was shown that the tolerance levels of CT-ED calibration became stricter with an increase in tissue thickness and decrease in the effective energy of a photon beam. For the last decade, a low effective energy photon beam (e.g., flattening-filter-free (FFF)) has been used in clinical sites. However, its tolerance level has not been established yet...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29130896/characterisation-of-flattening-filter-free-fff-beam-properties-for-initial-beam-set-up-and-routine-qa-independent-of-flattened-beams
#7
David Paynter, Steve J Weston, Vivian P Cosgrove, David I Thwaites
Objectives Flattening filter free beams have reached widespread use for clinical treatment deliveries. The usual methods for FFF beam characterisation for their quality assurance require the use of associated conventional flattened beams (cFF). Methods for QA of FFF without the need to use an associated cFF beams are presented and evaluated against current methods for both FFF and cFF beams. Methods Inflection point normalisation is evaluated against conventional methods for the determination of field size and penumbra for field sizes from 3cm x 3cm to 40cm x40cm at depths from dmax to 20cm in water for matched and unmatched FFF beams and for cFF beams...
November 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29091675/fast-wide-field-and-distortion-free-telescope-with-curved-detectors-for-surveys-at-ultralow-surface-brightness
#8
Eduard Muslimov, David Valls-Gabaud, Gérard Lemaître, Emmanuel Hugot, Wilfred Jahn, Simona Lombardo, Xin Wang, Pascal Vola, Marc Ferrari
We present the design of an all-reflective, bifolded Schmidt telescope aimed at surveys of extended astronomical objects with extremely low surface brightness. The design leads to a high image quality without any diffracting spider, a large aperture and field of view (FoV), and a small central obstruction that barely alters the point spread function (PSF). As an example, we design a high-quality, 36 cm diameter, fast (f/2.5) telescope working in the visible with a large FoV (1.6°×2.6°). The telescope can operate with a curved detector (or with a flat detector with a field flattener) and a set of filters...
November 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/29053107/spectral-imaging-using-clinical-megavoltage-beams-and-a-novel-multi-layer-imager
#9
Marios E Myronakis, Rony Fueglistaller, Joerg Rottmann, Yue-Houng Hu, Adam Wang, Paul Baturin, Pascal Huber, Daniel Morf, Josh M Star-Lack, Ross I Berbeco
We assess the feasibility of clinical megavoltage (MV) spectral imaging for material and bone separation with a novel multi-layer imager (MLI) prototype. The MLI provides higher detective quantum efficiency and lower noise than conventional electronic portal imagers. Simulated experiments were performed using a validated Monte Carlo model of the MLI to estimate energy absorption and energy separation between the MLI components. Material separation was evaluated experimentally using solid water and aluminum (Al), copper (Cu) and gold (Au) for 2...
October 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29048329/measurement-and-modeling-of-out-of-field-doses-from-various-advanced-post-mastectomy-radiotherapy-techniques
#10
Jihyung Yoon, David Heins, Xiaodong Zhao, Mary Sanders, Rui Zhang
More and more advanced radiotherapy techniques have been adopted for post-mastectomy radiotherapies (PMRT). Patient dose reconstruction is challenging for these advanced techniques because they increase the low out-of-field dose area while the accuracy of out-of-field dose calculations by current commercial treatment planning systems (TPSs) is poor. We aim to measure and model the out-of-field radiation doses from various advanced PMRT techniques. PMRT treatment plans for an anthropomorphic phantom were generated, including volumetric modulated arc therapy (VMAT) with standard and flattening-filter-free (FFF) photon beams, mixed beam therapy, 4-field intensity modulated radiation therapy (IMRT), and Tomotherapy...
October 19, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29031915/experimental-and-monte-carlo-based-determination-of-the-beam-quality-specifier-for-tomotherapyhd-treatment-units
#11
S Howitz, M Schwedas, T Wiezorek, K Zink
Reference dosimetry by means of clinical linear accelerators in high-energy photon fields requires the determination of the beam quality specifier TPR20,10, which characterizes the relative particle flux density of the photon beam. The measurement of TPR20,10 has to be performed in homogenous photon beams of size 10×10cm(2) with a focus-detector distance of 100cm. These requirements cannot be fulfilled by TomoTherapy treatment units from Accuray. The TomoTherapy unit provides a flattening-filter-free photon fan beam with a maximum field width of 40cm and field lengths of 1...
October 11, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29031610/characteristics-of-2-5%C3%A2-mv-beam-and-imaging-dose-to-patients
#12
George X Ding, Peter Munro
PURPOSE: This work provides the beam characteristics and evaluates the imaging dose to patients for a 2.5 MV portal imaging beam. METHOD AND MATERIALS: The Monte Carlo technique has been used to simulate the 2.5 MV imaging beam. Beam characteristics have been analyzed including the energy spectra and the fluence distributions as a function of position away from the beam central axis. The accuracy of a simulated beam was validated through comparisons between the Monte Carlo calculated and measured dose distributions in a water phantom...
October 11, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29030203/characterization-and-clinical-evaluation-of-a-novel-2d-detector-array-for-conventional-and-flattening-filter-free-fff-imrt-pre-treatment-verification
#13
Yuvaraj Sekar, Johannes Thoelking, Miriam Eckl, Irakli Kalichava, Dwi Seno Kuncoro Sihono, Frank Lohr, Frederik Wenz, Hansjoerg Wertz
BACKGROUND AND PURPOSE: The novel MatriXX(FFF) (IBA Dosimetry, Germany) detector is a new 2D ionization chamber detector array designed for patient specific IMRT-plan verification including flattening-filter-free (FFF) beams. This study provides a detailed analysis of the characterization and clinical evaluation of the new detector array. MATERIAL AND METHODS: The verification of the MatriXX(FFF) was subdivided into (i) physical dosimetric tests including dose linearity, dose rate dependency and output factor measurements and (ii) patient specific IMRT pre-treatment plan verifications...
October 10, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28974859/choice-of-a-suitable-dosimeter-for-photon-percentage-depth-dose-measurements-in-flattening-filter-free-beams
#14
Silvia Vargas Castrillón, Francisco Cutanda Henríquez
The International Atomic Energy Agency Technical Reports Series-398 code of practice for dosimetry recommends measuring photon percentage depth dose (PDD) curves with parallel-plate chambers. This code of practice was published before flattening filter-free (FFF) beams were widely used in clinical linear accelerators. The choice of detector for PDD measurements needs to be reassessed for FFF beams given the physical differences between FFF beams and flattened ones. The present study compares PDD curves for FFF beams of nominal energies 6 MV, 6 FFF, 10 MV, and 10 FFF from a Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, USA) acquired with Scanditronix photon diodes, two scanning type chambers (both PTW 31010 Semiflex), two small volume chambers (Wellhofer CC04 and PTW 31016 PinPoint 3D), PTW 34001 Roos, Scanditronix Roos, and NACP 02 parallel-plate chambers...
July 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28971344/the-effect-of-beam-interruption-during-fff-vmat-plans-for-sbrt
#15
Seongjong Oh, Benjamin Lewis, Amy Watson, Siyong Kim, Taeho Kim
To investigate the dosimetric effect of intended beam interruption during volumetric modulated arc therapy (VMAT) with flattening filter free (FFF) beam for exploring the possibility of deep inspiration breath hold stereotactic body radiation therapy (SBRT). A total of ten SBRT plans with 6 and 10 MV FFF beams were retrospectively selected. All plans consisted of four partial arcs, except one plan with six partial arcs. We delivered the plans using a Varian Truebeam™ with three different scenarios; without interruption (0int), with one intentional interruption (1int), or with two intentional interruptions (2int), per each partial arc...
October 2, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28951047/hippocampal-dose-during-linac-based-stereotactic-radiotherapy-for-brain-metastases-an-observational-study
#16
Alba Fiorentino, Umberto Tebano, Gianluisa Sicignano, Francesco Ricchetti, Gioacchino Di Paola, Dario Aiello, Niccolò Giaj-Levra, Rosario Mazzola, Sergio Fersino, Ruggero Ruggieri, Filippo Alongi
INTRODUCTION: Aim of the present study is to evaluate homolateral and contralateral hippocampus (H-H, C-H, respectively) dose during Fractionated Stereotactic Radiotherapy (FSRT) or Radiosurgery (SRS) for brain metastases (BM). MATERIALS & METHODS: Patients with BM<5, size≤30mm, KPS≥80 and a life expectancy>3months, were considered for SRS/FSRT (total dose 15-30Gy, 1-5 fractions). For each BM, a Flattening Filter Free (FFF) Volumetric Modulated Arc Therapy (VMAT) plan was generated with one or two arcs...
September 23, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28944979/dosimetric-validation-of-monaco-treatment-planning-system-on-an-elekta-versahd-linear-accelerator
#17
Ganesh Narayanasamy, Daniel L Saenz, Dewayne Defoor, Niko Papanikolaou, Sotirios Stathakis
The purpose of this study is to perform dosimetric validation of Monaco treatment planning system version 5.1. The Elekta VersaHD linear accelerator with high dose rate flattening filter-free photon modes and electron energies was used in this study. The dosimetric output of the new Agility head combined with the FFF photon modes warranted this investigation into the dosimetric accuracy prior to clinical usage. A model of the VersaHD linac was created in Monaco TPS by Elekta using commissioned beam data including percent depth dose curves, beam profiles, and output factors...
September 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28915893/dosimetric-comparison-of-different-treatment-modalities-for-stereotactic-radiotherapy
#18
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
#19
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
#20
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
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