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Yoshiyuki Katsuta, Noriyuki Kadoya, Yukio Fujita, Eiji Shimizu, Kenichi Matsunaga, Kinya Sawada, Haruo Matsushita, Kazuhiro Majima, Keiichi Jingu
Log file-based methods are attracting increasing interest owing to their ability to validate volumetric-modulated arc therapy outputs with high resolution in the leaf and gantry positions and in delivered dose. Cross-validation of these methods for comparison with measurement-based methods using the ionization chamber/ArcCHECK-3DVH software (version 3.2.0) under the same conditions of treatment anatomy and plan enables an efficient evaluation of this method. In this study, with the purpose of cross-validation, we evaluate the accuracy of a log file-based method using Elekta log files and an X-ray voxel Monte Carlo dose calculation technique in the case of leaf misalignment during prostate volumetric-modulated arc therapy...
December 2017: Technology in Cancer Research & Treatment
Ðeni Smilović Radojčić, Manda Švabić Kolacio, Milan Radojčić, David Rajlić, Božidar Casar, Dario Faj, Slaven Jurković
Advanced dose calculation algorithms for radiation therapy treatment planning can report external beam photon dose 2-sided, in terms of dose-to-medium (Dm) and dose-to-water (Dw). The purpose of our study was to determinate the effect of Dw and Dm reporting modes built in Elekta Monaco treatment planning system on intensity-modulated radiotherapy dose distributions for patients with nasopharyngeal cancer. For 13 patients involved in this retrospective study, 2 plans were created: 1 using Dw and another according to Dm reporting mode...
January 4, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
Pilar Garcés, David López-Sanz, Fernando Maestú, Ernesto Pereda
BACKGROUND: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer...
December 16, 2017: Sensors
Mayur Sharma, Antonio Meola, Sushma Bellamkonda, Xuefei Jia, Joshua Montgomery, Samuel T Chao, John H Suh, Lilyana Angelov, Gene H Barnett
BACKGROUND: Glomus jugulare tumors (GJTs) are rare benign tumors, which pose significant treatment challenges due to proximity to critical structures. OBJECTIVE: To evaluate the long-term clinical and radiological outcome in patients undergoing stereotactic radiosurgery (SRS) for GJTs through retrospective study. METHODS: Forty-two patients with 43 GJTs were treated using Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden) at our institute from 1997 to 2016...
December 4, 2017: Neurosurgery
Holger Joswig, Carolyn M Benson, Andrew G Parrent, Keith W MacDougall, David A Steven
Background: For intracranial electroencephalographic monitoring, stereotactically implanted depth electrodes are increasingly used at epilepsy centers around the world. Objective: To identify pearls and pitfalls from our experience with stereotactic Leksell (Elekta AB, Stockhom, Sweden) frame-based depth electrode implantation. Methods: An intraoperative video of the implantation technique was recorded. Results: A detailed description and a video on how to implant depth electrodes using the stereotactic Leksell frame is provided...
December 7, 2017: Operative Neurosurgery (Hagerstown, Md.)
Ali Jomehzadeh, Daryoush Shahbazi-Gahrouei, Vahid Jahanbakhsh
The head scatter factor (Sc ) is important to measurements radiation beam and beam modeling of treatment planning systems used for advanced radiation therapy techniques. This study aimed to investigate the design of a miniphantom to measurement variations in collimator Sc in the presence of shielding blocks for shaping the beam using different field sizes. Copper, Brass, and Perspex buildup caps were designed and fabricated locally as material with three different thicknesses for buildup caps (miniphantoms)...
October 2017: Journal of Medical Signals and Sensors
Shahad M Al-Ward, Anthony Kim, Claire McCann, Mark Ruschin, Patrick Cheung, Arjun Sahgal, Brian M Keller
PURPOSE: Targeting and tracking of central lung tumors may be feasible on the Elekta MRI-linac (MRL) due to the soft-tissue visualization capabilities of MRI. The purpose of this work is to develop a novel treatment planning methodology to simulate tracking of central lung tumors with the MRL and to quantify the benefits in OAR sparing compared with the ITV approach. METHODS: Full 4D-CT datasets for five central lung cancer patients were selected to simulate the condition of having 4D-pseudo-CTs derived from 4D-MRI data available on the MRL with real-time tracking capabilities...
December 1, 2017: Journal of Applied Clinical Medical Physics
Sonja Wegener, Otto A Sauer
PURPOSE: Different detector properties will heavily affect the results of off-axis measurements outside of radiation fields, where a different energy spectrum is encountered. While a diode detector would show a high spatial resolution, it contains high atomic number elements, which lead to perturbations and energy dependent response. An ionization chamber, on the other hand, has a much smaller energy-dependence, but shows dose averaging over its larger active volume. We suggest a way to obtain spatial energy-response corrections of a detector independent of its volume effect for profiles of arbitrary fields by using a combination of two detectors...
November 29, 2017: Medical Physics
Iban Torres-Xirau, Igor Olaciregui-Ruiz, Gauti Baldvinsson, Ben J Mijnheer, Uulke A van der Heide, Anton Mans
Electronic portal imaging devices (EPIDs) are frequently used in external beam radiation therapy for dose verification purposes. The aim of this study was to investigate the dose-response characteristics of the EPID in the Unity MR-linac (Elekta AB, Stockholm, Sweden) relevant for dosimetric applications under clinical conditions. EPID images and ionization chamber measurements were used to study the effects of the magnetic field, the scatter generated in the MR housing reaching the EPID, and inhomogeneous attenuation from the MR housing...
November 28, 2017: Physics in Medicine and Biology
Angela Steinmann, R Jason Stafford, Gabriel Sawakuchi, Zhifei Wen, Laurence Court, Clifton D Fuller, David Followill
PURPOSE: Synthetic tissue equivalent (STE) materials currently used to simulate tumor and surrounding tissues for IROC-Houston's anthropomorphic head and thorax QA phantoms cannot be visualized using magnetic resonance (MR) imaging. The purpose of this study was to characterize dual MR/CT visible STE materials that can be used in an end-to-end QA phantom for MR guided radiotherapy (MRgRT) modalities. METHODS: Over 80 materials' MR, CT, and dosimetric STE properties were investigated for use in MRgRT QA phantoms...
November 27, 2017: Medical Physics
Daniel J O'Brien, James Dolan, Stefan Pencea, Nicholas Schupp, Gabriel O Sawakuchi
PURPOSE: The purpose of this study was to acquire beam data for an MR-linac, with and without a 1.5 T magnetic field, by using a variety of commercially available detectors to assess their relative response in the magnetic field. The impact of the magnetic field on the measured dose distribution was also assessed. METHODS: An MR-safe 3D scanning water phantom was used to measure output factors, depth dose curves, and off-axis profiles for various depths and for field sizes between 2 × 2 cm2 and 22 × 22 cm2 for an Elekta MR-linac beam with the orthogonal 1...
November 27, 2017: Medical Physics
J H Wilfred de Vries, Enrica Seravalli, Antonetta Christina Houweling, Simon J Woodings, Rob van Rooij, Jochem W H Wolthaus, Jan J W Lagendijk, Bas W Raaymakers
To perform patient plan-quality assurance (QA) on the newly installed MR-Linac (MRL) there was a need for having an MR-compatible QA-device. An MR compatible device (MR-Delta4) was developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response such as short-term-reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency were investigated for the Clinical Delta4PT as well as for the MR compatible version...
November 26, 2017: Physics in Medicine and Biology
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
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
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
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
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
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
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
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
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