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https://www.readbyqxmd.com/read/29135471/first-patients-treated-with-a-1-5-t-mri-linac-clinical-proof-of-concept-of-a-high-precision-high-field-mri-guided-radiotherapy-treatment
#1
B W Raaymakers, I M Jürgenliemk-Schulz, G H Bol, M Glitzner, A N T J Kotte, B van Asselen, J C J de Boer, J J Bluemink, S L Hackett, M A Moerland, S J Woodings, J W H Wolthaus, H M van Zijp, M E P Philippens, R Tijssen, J G M Kok, E N de Groot-van Breugel, I Kiekebosch, L T C Meijers, C N Nomden, G G Sikkes, P A H Doornaert, W S C Eppinga, N Kasperts, L G W Kerkmeijer, J H A Tersteeg, K J Brown, B Pais, P Woodhead, J J W Lagendijk
The integration of 1.5 T MRI functionality with a radiotherapy linear accelerator (linac) has been pursued since 1999 by the UMC Utrecht in close collaboration with Elekta and Philips. The idea behind this integrated device is to offer unrivalled, online and real-time, soft-tissue visualization of the tumour and the surroundings for more precise radiation delivery. The proof of concept of this device was given in 2009 by demonstrating simultaneous irradiation and MR imaging on phantoms, since then the device has been further developed and commercialized by Elekta...
November 14, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29131346/evaluation-of-the-latency-and-the-beam-characteristics-of-a-respiratory-gating-system-using-an-elekta-linear-accelerator-and-a-respiratory-indicator-device-abches
#2
Masahide Saito, Naoki Sano, Koji Ueda, Yuki Shibata, Kengo Kuriyama, Takafumi Komiyama, Kan Marino, Shinichi Aoki, Hiroshi Onishi
PURPOSE: To evaluate the basic performance of a respiratory gating system using an Elekta linac and an Abches respiratory monitoring device. METHODS: The gating system was comprised of an Elekta Synergy linac equipped with a Response(TM) gating interface module and an Abches respiratory monitoring device. The latencies from a reference respiratory signal to the resulting Abches gating output signal and the resulting monitor-ion-chamber output signal were measured...
November 13, 2017: 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
#3
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/29125328/automated-retrieval-of-radiotherapy-data-for-clinical-trials-audit-and-research
#4
Marina Romanchikova, Karl Harrison, Neil G Burnet, Andrew Fc Hoole, Michael Pf Sutcliffe, Michael Andrew Parker, Rajesh Jena, Simon J Thomas
OBJECTIVE: To enable fast and customisable automated collection of radiotherapy data from tomotherapy storage. METHODS: Human-readable data maps (TagMaps) were created to generate DICOM-RT data from tomotherapy archives, and provided access to "hidden" information comprising delivery sinograms, positional corrections and adaptive-RT doses. RESULTS: 797 datasets totalling 25,000 scans were batch-exported in 31.5 hours. All archived information was restored, including the data not available via commercial software...
November 10, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/29094802/quantification-and-comparison-the-dosimetric-impact-of-two-treatment-couch-model-in-vmat
#5
Ruohui Zhang, Yulan Gao, Wenwen Bai
The use of Monte Carlo treatment planning systems (TPS) in radiation therapy has increased the dosimetric accuracy of VMAT treatment sequences. However, this accuracy is compromised by not including the treatment couch into the treatment planning process. Therefore, the impact of the treatment couch on radiation delivery output was determined, and two different couch models (uniform couch model A vs two components model B) were included and tested in the Monaco TPS to investigate which model can better quantify the couch influence on radiation dose...
November 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29040773/treatment-outcomes-of-a-randomized-trial-of-unruptured-brain-arteriovenous-malformation-eligible-unruptured-brain-arteriovenous-malformation-patients
#6
Min Lang, Nina Z Moore, Peter A Rasmussen, Mark D Bain
BACKGROUND: The guideline for treating unruptured brain arteriovenous malformations (ubAVMs) remains controversial. A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) reported lower risk of stroke or death with conservative management compared to interventional treatment. There were numerous limitations to the study, including short follow-up period and disproportionate number of patients treated with surgery and embolization. OBJECTIVE: To evaluate whether treatment of ARUBA-eligible patients have acceptable outcomes at our institution...
October 10, 2017: Neurosurgery
https://www.readbyqxmd.com/read/29035875/a-20-channel-magnetoencephalography-system-based-on-optically-pumped-magnetometers
#7
Amir Borna, Tony R Carter, Josh D Goldberg, Anthony P Colombo, Yuan-Yu Jau, Christopher Berry, Jim McKay, Julia Stephen, Michael Weisend, Peter D D Schwindt
We describe a multichannel magnetoencephalography (MEG) system that uses optically pumped magnetometers (OPMs) to sense the magnetic fields of the human brain. The system consists of an array of 20 OPM channels conforming to the human subject's head, a person-sized magnetic shield containing the array and the human subject, a laser system to drive the OPM array, and various control and data acquisitions systems. We conducted two MEG experiments: auditory evoked magnetic field (AEF) and somatosensory evoked magnetic field (SEF), on three healthy male subjects, using both our OPM array and a 306-channel Elekta-Neuromag superconducting quantum interference device (SQUID) MEG system...
October 16, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28991693/magnetic-resonance-and-computed-tomography-image-fusion-technology-in-patients-with-parkinson-s-disease-after-deep-brain-stimulation
#8
Jun Xia, Pin He, Xiaodong Cai, Doudou Zhang, Ni Xie
Electrode position after deep brain stimulation (DBS) for Parkinson's disease (PD) needs to be confirmed, but there are concerns about the risk of postoperative magnetic resonance imaging (MRI) after DBS. These issues could be avoided by fusion images obtained from preoperative MRI and postoperative computed tomography (CT). This study aimed to investigate image fusion technology for displaying the position of the electrodes compared with postoperative MRI. This was a retrospective study of 32 patients with PD treated with bilateral subthalamic nucleus (STN) DBS between April 2015 and March 2016...
October 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28983447/surgical-management-and-outcome-experience-of-53-cerebellopontine-angle-meningiomas
#9
Xiaosheng He, Weiping Liu, Yangang Wang, Jun Zhang, Buqing Liang, Jason H Huang
Background Meningiomas follow schwannomas as the second most common cerebellopontine angle (CPA) tumors. We investigate the diagnosis, management, and prognosis of this disease. Methods We reviewed the cases with the CPA meningiomas in our institution in Shaanxi, China from January 2012 to December 2015. Charts were retrospectively examined and patients were divided into two groups: 1) surgical treatment with a retrosigmoid approach for tumor resection and 2) stereotactic radiosurgery treatment only. Patients were followed up and outpatient records were also reviewed...
August 3, 2017: Curēus
https://www.readbyqxmd.com/read/28973682/an-open-label-analgesic-efficacy-and-safety-of-pituitary-radiosurgery-for-patients-with-opioid-refractory-pain-study-protocol-for-a-randomized-controlled-trial
#10
Pierre-Yves Borius, Stéphanie Ranque Garnier, Karine Baumstarck, Frédéric Castinetti, Anne Donnet, Eric Guedj, Philippe Cornu, Serge Blond, Sébastien Salas, Jean Régis
BACKGROUND: Hypophysectomy performed by craniotomy or percutaneous techniques leads to complete pain relief in more than 70% to 80% of cases for opioid refractory cancer pain. Radiosurgery could be an interesting alternative approach to reduce complications. OBJECTIVE: To assess the analgesic efficacy compared with standard of care is the primary goal. The secondary objectives are to assess ophthalmic and endocrine tolerance, drug consumption, quality of life, and mechanisms of analgesic action...
August 2, 2017: Neurosurgery
https://www.readbyqxmd.com/read/28965894/intrafraction-monitoring-of-prostate-motion-during-radiotherapy-using-the-clarity-%C3%A2-autoscan-transperineal-ultrasound-tpus-system
#11
A K Richardson, P Jacobs
INTRODUCTION: Implementation of the Clarity(®) Autoscan (Elekta) Transperineal Ultrasound (TPUS) system in Bristol is the first of its kind in the UK and we have already shown its utility in interfractional Image Guided Radiotherapy (IGRT).(14) This study establishes the extent of intrafraction prostate motion as measured by Clarity and explores the potential benefits of TPUS for intrafraction monitoring. METHODS: Monitoring data was analysed for 526 fractions from 20 localised prostate cancer patients...
November 2017: Radiography
https://www.readbyqxmd.com/read/28944979/dosimetric-validation-of-monaco-treatment-planning-system-on-an-elekta-versahd-linear-accelerator
#12
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/28921931/technical-note-a-simple-algorithm-to-convert-epid-grey-values-into-absorbed-dose-to-water-without-prior-knowledge
#13
Christine Boutry, Aurélie Sors, Jimmy Fontaine, Nolwenn Delaby, Gregory Delpon
PURPOSE: Full integration of EPID-based dosimetry in a global quality control workflow is still complicated. All the actual solutions are based on a relation between image grey-level signal and total linac delivered dose. In this study, we propose a simple algorithm relying pixel grey-level of EPID image with average linac delivered dose per acquisition frame. METHODS: Calibration models are constructed for Varian and Elekta linacs including scattering conditions and EPID-arm backscatter specific corrections...
September 16, 2017: Medical Physics
https://www.readbyqxmd.com/read/28887827/a-universal-parameterized-gradient-based-method-for-photon-beam-field-size-determination
#14
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/28886048/a-single-source-photon-source-model-of-a-linear-accelerator-for-monte-carlo-dose-calculation
#15
Obioma Nwankwo, Gerhard Glatting, Frederik Wenz, Jens Fleckenstein
PURPOSE: To introduce a new method of deriving a virtual source model (VSM) of a linear accelerator photon beam from a phase space file (PSF) for Monte Carlo (MC) dose calculation. MATERIALS AND METHODS: A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden) and recording the particles that reach a plane 16 cm downstream the electron source...
2017: PloS One
https://www.readbyqxmd.com/read/28871971/financial-relationships-with-industry-of-editorial-board-members-of-the-three-journals-of%C3%A2-the-american-society-for-radiation-oncology
#16
Vivek Verma
PURPOSE: To quantitate financial conflicts of interest (FCOIs) among radiation oncology peer-reviewers, specifically editorial board members of the 3 American Society for Radiation Oncology journals. METHODS AND MATERIALS: The public Centers for Medicare and Medicaid Services Open Payments database delineates payments in 3 categories (general payments, research funding, and company ownership). After excluding non-US and non-MDs, names of board members were searched...
October 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28869651/technical-note-investigating-the-impact-of-field-size-on-patient-selection-for-the-1-5t-mr-linac
#17
Robert W Chuter, Philip Whitehurst, Ananya Choudhury, Marcel van Herk, Alan McWilliam
PURPOSE: The 1.5 T Elekta MR-Linac, due to the construction of the system will have a maximum radiation field size in the superior-inferior patient direction of 22 cm at isocentre. The field size may impact on the patient groups which can be treated on the system. This technical note aims to address the question of which treatment sites will be affected by field size limitations on the MR-Linac. METHODS: Using historical data for 11 595 cases over 2 yr treated at the authors' institution, the proportion of plans that would fit the MR-Linac's field size was determined for eleven patient groups...
September 4, 2017: Medical Physics
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
#18
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/28834109/implementation-of-respiratory-gated-vmat-on-a-versa-hd-linear-accelerator
#19
Jeffrey E Snyder, Ryan T Flynn, Daniel E Hyer
The accurate delivery of respiratory-gated volumetric modulated arc therapy (VMAT) treatment plans presents a challenge since the gantry rotation and collimator leaves must be repeatedly stopped and set into motion during each breathing cycle. In this study, we present the commissioning process for an Anzai gating system (AZ-733VI) on an Elekta Versa HD linear accelerator and make recommendations for successful clinical implementation. The commissioning tests include central axis dose consistency, profile consistency, gating beam-on/off delay, and comparison of gated versus nongated gamma pass rates for patient-specific quality assurance using four clinically commissioned photon energies: 6 MV, 6 FFF, 10 MV, and 10 FFF...
August 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28810243/evaluating-critical-brain-radiation-doses-in-the-treatment-of-multiple-brain-lesions-with-gamma-knife-radiosurgery
#20
Mustafa Aziz Hatiboglu, Kerime Akdur
BACKGROUND: Treatment of patients with multiple brain metastases has shifted to stereotactic radiosurgery, withholding whole-brain (WB) radiation therapy. However, radiation toxicity to the brain is a concern when treating multiple brain lesions with single-fraction stereotactic radiosurgery. OBJECTIVE: The purpose of this study was to determine the changes in brain radiation doses when treating various numbers of targets and lesion volumes. METHODS: We simulated different treatment plans with different combinations of varying tumor volumes including 0...
2017: Stereotactic and Functional Neurosurgery
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