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James R Kerns, David Followill, Jessica Lowenstein, Andrea Molineu, Paola Alvarez, Paige A Taylor, Stephen F Kry
PURPOSE: Reference dosimetry data can provide an independent second check of acquired values when commissioning or validating a treatment planning system (TPS). The Imaging and Radiation Oncology Core at Houston (IROC-Houston) has measured numerous linear accelerators throughout its existence. The results of those measurements are given here, comparing accelerators and the agreement of measurement versus institutional TPS calculations. METHODS: Data from IROC-Houston on-site reviews from 2000 through 2014 were analyzed for all Elekta accelerators, approximately 50...
March 14, 2018: Medical Physics
David M Edmunds, Lone Gothard, Komel Khabra, Anna Kirby, Poonam Madhale, Helen McNair, David Roberts, K K Tang, Richard Symonds-Tayler, Fatemeh Tahavori, Kevin Wells, Ellen Donovan
Voluntary inspiration breath hold (VIBH) for left breast cancer patients has been shown to be a safe and effective method of reducing radiation dose to the heart. Currently, VIBH protocol compliance is monitored visually. In this work, we establish whether it is possible to gate the delivery of radiation from an Elekta linac using the Microsoft Kinect version 2 (Kinect v2) depth sensor to measure a patient breathing signal. This would allow contactless monitoring during VMAT treatment, as an alternative to equipment-assisted methods such as active breathing control (ABC)...
March 13, 2018: Journal of Applied Clinical Medical Physics
Simon J Woodings, J J Bluemink, J H Wilfred de Vries, Yury Niatsetski, Bob van Veelen, Joost Schillings, Jan G M Kok, Jochem W H Wolthaus, Sara L Hackett, Bram van Asselen, Helena Maria van Zijp, Stefan Pencea, David A Roberts, Jan J W Lagendijk, Bas W Raaymakers
As a prerequisite for clinical treatments it was necessary to characterize the Elekta 1.5 T MRI-linac 7 MV FFF radiation beam. Following acceptance testing, beam characterization data were acquired with Semiflex 3D (PTW 31021), microDiamond (PTW 60019), and Farmer-type (PTW 30013 and IBA FC65-G) detectors in an Elekta 3D scanning water phantom and a PTW 1D water phantom. EBT3 Gafchromic film and ion chamber measurements in a buildup cap were also used. Special consideration was given to scan offsets, detector effective points of measurement and avoiding air gaps...
March 9, 2018: Physics in Medicine and Biology
Dennis N Stanley, Karl Rasmussen, Neil Kirby, Nikos Papanikolaou, Alonso N Gutiérrez
INTRODUCTION: A robust image quality assurance and analysis methodology for image-guided localization systems is crucial to ensure the accurate localization and visualization of target tumors. In this study, the long-term stability of selected image parameters was assessed and evaluated for the cone-beam computed tomography (CBCT) mode, planar radiographic kV mode, and the radiographic MV mode of an Elekta VersaHD. MATERIALS AND METHODS: The CATPHAN, QckV-1, and QC-3 phantoms were used to evaluate the image quality parameters...
March 9, 2018: Journal of Applied Clinical Medical Physics
Ronny Kalash, Phillip M Pifer, Sushil Beriwal, Scott M Glaser, John A Vargo, Dwight E Heron
Breast cancer represents the second leading cause of brain metastases in women. Once diagnosed, brain metastases have been associated with a rapidly progressive and universally poor prognosis. Breast cancer patients, particularly those with advantageous disease characteristics, may achieve extended survival. This extended life expectancy highlights the importance of effective intracranial treatments that minimize treatment-related late toxicity. Whole brain radiation therapy (WBRT) remains a standard of care palliative option; however, concerns remain regarding the late neurocognitive effects...
December 29, 2017: Curēus
Hongyu Jiang, Rajeev Badkul, Damodar Pokhrel
PURPOSE: As an alternative to cylindrical applicators, air-inflated balloon applicators have been introduced into high-dose-rate (HDR) vaginal cuff brachytherapy to achieve sufficient dose to the vagina mucosa as well as to spare organs at risk, mainly the rectum and bladder. Commercial treatment planning systems which employ formulae in the AAPM Task Group No. 43 (TG 43) report do not take into account tissue inhomogeneity. Consequently, the low-density air in a balloon applicator induces different doses delivered to the mucosa from planned by these planning systems...
March 1, 2018: Journal of Applied Clinical Medical Physics
Tuomas Koivumäki, Antonella Fogliata, Michele Zeverino, Eeva Boman, Joanna Sierpowska, Raphaël Moeckli, Véronique Vallet, Luca Cozzi, Janne Heikkilä, Anssi Väänänen, Kristiina Vuolukka, Saara Sillanmäki, Jan Seppälä
PURPOSE: The dosimetric differences between four radiation therapy techniques for left sided whole breast irradiation were evaluated side by side in the same patient population. METHODS: Radiotherapy treatment plans were retrospectively created with Accuray TomoDirect (TD), Elekta Volumetric Modulated Arc Therapy (E-VMAT), Varian RapidArc (RA) and Field-in-field (FinF) technique for 20 patients, who had received left breast irradiation during deep-inspiration breath-hold...
January 2018: Physica Medica: PM
Leon de Prez, Jacco de Pooter, Bartel Jansen, Thijs Perik, Frits Wittkämper
Recently flattening filter free (FFF) beams became available for application in modern radiotherapy. There are several advantages of FFF beams over conventional flattening filtered (cFF) beams, however differences in beam spectra at the point of interest in a phantom potentially affect the ion chamber response. Beams are also non-uniform over the length of a typical reference ion chamber and recombination is usually larger. Despite several studies describing FFF beam characteristics, only a limited number of studies investigated their effect on kQ factors...
February 20, 2018: Physics in Medicine and Biology
David J Eaton, Jonathan Lee, Ian Paddick
PURPOSE: Stereotactic radiosurgery is indicated for treatment of multiple brain metastases. Various treatment platforms are available, but most comparisons are limited to single-center studies. As part of a national commissioning program, benchmark planning cases were completed by 21 clinical centers, providing a unique dataset of current practice across a large number of providers and equipment platforms. METHODS AND MATERIALS: Two brain metastases cases were provided, with images and structures predrawn, involving 3 and 7 lesions...
December 30, 2017: Practical Radiation Oncology
Luke K Webb, Emma K Inness, Paul H Charles
This paper examines the difference in patient specific dosimetry using three different detectors of varying active volume, density and composition, for quality assurance of stereotactic treatments. A PTW 60017 unshielded electron diode, an Exradin W1 scintillator, and a PTW 31014 PinPoint small volume ionisation chamber were setup in a Lucy 3D QA phantom, and were positioned at the isocentre of an Elekta Axesse, with beam modulator collimator, using Exactrac and a HexaPODTM couch. Dose measurements were acquired for 43 stereotactic arcs, and compared to BrainLAB iPlan version 3...
February 14, 2018: Australasian Physical & Engineering Sciences in Medicine
Mireille Conrad, Grégory Bolard, Marie Nowak, Berardino De Bari, Wendy Jeanneret-Sozzi, Jean Bourhis, Jean-François Germond, François Bochud, Raphaël Moeckli
PURPOSE: Image guided radiotherapy (IGRT) improves patient positioning for treatment delivery at the cost of an additional dose. This work aimed to calculate the effective dose (as an indicator of dose) for head & neck (H&N) and breast IGRT treatments by implementing dose calculation models to determine the dose distributions. METHODS: The kV dose-models were created for the IGRT systems of Elekta Synergy (XVI) and Varian Clinac (OBI) linear accelerators within Philips Pinnacle TPS...
February 6, 2018: Zeitschrift Für Medizinische Physik
von Voigts-Rhetz Philip, Vorwerk Hilke, Zink Klemens
The electron fluence inside a parallel-plate ionization chamber positioned in a water phantom and exposed to a clinical electron beam deviates from the unperturbed fluence in water in absence of the chamber. One reason for the fluence perturbation is the "in-scattering effect" as described in ICRU 35. Aim of this work is a detailed experimental and with Monte Carlo simulations investigation of this effect. The experiments and Monte Carlo Simulations, with EGSnrc [1], were performed in a solid-water phantom (RW3) sized 30 × 30 × 30 cm3...
January 2018: Physica Medica: PM
W M Abou-Taleb, M H Hassan, E A El Mallah, S M Kotb
Photoneutron production, and the dose equivalent, in the head assembly of the 15 MV Elekta Precise medical linac; operating in the faculty of Medicine at Alexandria University were estimated with the MCNP5 code. Photoneutron spectra were calculated in air and inside a water phantom to different depths as a function of the radiation field sizes. The maximum neutron fluence is 3.346×10-9 n/cm2-e for a 30×30 cm2 field size to 2-4 cm-depth in the phantom. The dose equivalent due to fast neutron increases as the field size increases, being a maximum of 0...
February 3, 2018: Applied Radiation and Isotopes
Stephen Zieminski, Melin Khandekar, Yi Wang
This study compared the dosimetric performance of (a) volumetric modulated arc therapy (VMAT) with standard optimization (STD) and (b) multi-criteria optimization (MCO) to (c) intensity modulated radiation therapy (IMRT) with MCO for hippocampal avoidance whole brain radiation therapy (HA-WBRT) in RayStation treatment planning system (TPS). Ten HA-WBRT patients previously treated with MCO-IMRT or MCO-VMAT on an Elekta Infinity accelerator with Agility multileaf collimators (5-mm leaves) were re-planned for the other two modalities...
February 7, 2018: Journal of Applied Clinical Medical Physics
Lau M Andersen
An important aim of an analysis pipeline for magnetoencephalographic data is that it allows for the researcher spending maximal effort on making the statistical comparisons that will answer the questions of the researcher, while in turn spending minimal effort on the intricacies and machinery of the pipeline. I here present a set of functions and scripts that allow for setting up a clear, reproducible structure for separating raw and processed data into folders and files such that minimal effort can be spend on: (1) double-checking that the right input goes into the right functions; (2) making sure that output and intermediate steps can be accessed meaningfully; (3) applying operations efficiently across groups of subjects; (4) re-processing data if changes to any intermediate step are desirable...
2018: Frontiers in Neuroscience
Filipa Costa, Simon J Doran, Ian Maddock Hanson, Simeon Nill, Ilias Billas, David R Shipley, Simon Duane, John Adamovics, Uwe Oelfke
Dosimetric quality assurance (QA) of the new Elekta Unity (MR-linac) will differ from the QA performed of a conventional linac due to the constant magnetic field, which creates an electron return effect (ERE). In this work we aim to validate PRESAGE(R) dosimetry in a transverse magnetic field, and assess its use to validate the research version of the Monaco TPS of the MR-linac. Cylindrical samples of PRESAGE(R) 3D dosimeter separated by an air gap were irradiated with a cobalt-60 unit, while placed between the poles of an electromagnet at 0...
February 2, 2018: Physics in Medicine and Biology
Kota Abe, Noriyuki Kadoya, Shinya Sato, Shimpei Hashimoto, Yujiro Nakajima, Yuya Miyasaka, Kengo Ito, Rei Umezawa, Takaya Yamamoto, Noriyoshi Takahashi, Ken Takeda, Keiichi Jingu
We evaluated the impact of model-based dose calculation algorithms (MBDCAs) on high-dose-rate brachytherapy (HDR-BT) treatment planning for patients with cervical cancer. Seven patients with cervical cancer treated using HDR-BT were studied. Tandem and ovoid applicators were used in four patients, a vaginal cylinder in one, and interstitial needles in the remaining two patients. MBDCAs were applied to the Advanced Collapsed cone Engine (ACE; Elekta, Stockholm, Sweden). All plans, which were originally calculated using TG-43, were re-calculated using both ACE and Monte Carlo (MC) simulations...
January 25, 2018: Journal of Radiation Research
Leon Armand de Prez, Jacco A de Pooter, Bartel Joris Jansen, Thijs Jan Perik, Frits W Wittkämper
Recently flattening filter free (FFF) beams became available for application in modern radiotherapy. There are several advantages of FFF beams over conventional flattening filtered (cFF) beams, however differences in beam spectra at the point of interest in a phantom potentially affect the ion chamber response. Beams are also non-uniform over the length of a typical reference ion chamber and recombination is usually larger. Despite several studies describing FFF beam characteristics, only a limited number of studies investigated their effect on <i>k</i><sub>Q</sub> factors...
January 25, 2018: Physics in Medicine and Biology
Christopher P Oliver, Duncan J Butler, Viliami Takau, Ivan Williams
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) held a comparison exercise in April 2016 where participants came to ARPANSA and measured the output factor of a nominal 5 mm cone attached to the ARPANSA Elekta Synergy (Elekta, Crawley, UK) linear accelerator. The goal of the exercise was to compare the consistency and methods used by independent medical physicists in measuring small-field output factors. ARPANSA provided a three-dimensional scanning tank for detector setup and positioning, but the participants were required to measure the output factor with their own detectors...
January 25, 2018: Journal of Applied Clinical Medical Physics
Kirsty Symons, Colm Morrison, Jason Parry, Simon Woodings, Yvonne Zissiadis
A study was undertaken to explore the use of volumetric modulated arc therapy (VMAT) for total body irradiation (TBI). Five patient plans were created in Pinnacle3 using nine 6 MV photon dynamic arcs. A dose of 12 Gy in six fractions was prescribed. The planning target volume (PTV) was split into four subsections for the head, chest, abdomen, and pelvis. The head and chest beams were optimized together, followed by the abdomen and pelvis beams. The last stage of the planning process involved turning all beams on and performing a final optimization to achieve a clinically acceptable plan...
January 24, 2018: Journal of Applied Clinical Medical Physics
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