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https://www.readbyqxmd.com/read/28078405/-radiosurgery-and-fractionated-stereotactic-radiotherapy-of-vestibular-schwannoma
#1
K Hamm, H-U Herold, G Surber, S Rosahl
Management of vestibular schwannoma (VS) should always be interdisciplinary and results better than the natural course. Particularly in small VS, either microsurgical resection or radiosurgery (RS) can be employed. RS is a special method (initially only possible stereotactically) for delivering high-precision radiation from many directions to the target point (the isocenter) in a single high dose. With the development of three different systems-Gamma Knife (Elekta, Stockholm, Sweden), special linear accelerators, and CyberKnife (Accuray, Sunnyvale, CA, USA)-the options were extended to 1-5 fractions for RS and multisession RS (msRS), and to up to 6 weeks of conventional fractionation as stereotactic radiotherapy (SRT)...
January 11, 2017: HNO
https://www.readbyqxmd.com/read/28073637/variable-angle-stereo-imaging-for-rapid-patient-position-correction-in-an-in-house-real-time-position-monitoring-system
#2
Sankar Arumugam, Mark Sidhom, Daniel Truant, Aitang Xing, Mark Udovitch, Lois Holloway
PURPOSE: To develop and validate a variable angle stereo image based position correction methodology in an X-ray based in-house online position monitoring system. MATERIALS AND METHODS: A stereo imaging module that enables 3D position determination and couch correction of the patient based on images acquired at any arbitrary angle and arbitrary angular separation was developed and incorporated to the in-house SeedTracker real-time position monitoring system. The accuracy of the developed system was studied by imaging an anthropomorphic phantom implanted with radiopaque markers set to known offset positions from its reference position in an Elekta linear accelerator (LA) and associated XVI imaging system...
January 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28048890/su-g-tep1-05-development-and-clinical-introduction-of-automated-radiotherapy-treatment-planning-for-prostate-cancer
#3
D Winkel, G H Bol, B van Asselen, J Hes, V Scholten, Lgw Kerkmeijer, B W Raaymakers
PURPOSE: To develop an automated radiotherapy treatment planning and optimization workflow for prostate cancer in order to generate clinical treatment plans. METHODS: A fully automated radiotherapy treatment planning and optimization workflow was developed based on the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). To evaluate our method, a retrospective planning study (n=100) was performed on patients treated for prostate cancer with 5 field intensity modulated radiotherapy, receiving a dose of 35×2Gy to the prostate and vesicles and a simultaneous integrated boost of 35×0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048877/su-g-brb-08-investigation-on-the-magnetic-field-effect-on-tlds-oslds-and-gafchromic-films-using-an-mr-linac
#4
Z Wen, J Wang, W Jiang, D O'Brien, G Sawakuchi, G Ibbott
PURPOSE: To investigate whether a strong magnetic field (B=1.5 T) can affect dose responses of thermoluminescent dosimeters (TLDs), optically stimulated luminescence dosimeters (OSLDs) and Gafchromic films using an MR-Linac (Elekta) before and after the magnet was ramped down from 1.5 T to 0 T. METHODS: Three types of dosimeters (TLDs, OSLDs, EBT3 films) were divided into two groups. Group 1 was first irradiated in a phantom of Solid Water slabs (Standard Imaging) inside a B=1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048863/su-f-j-105-towards-a-novel-treatment-planning-pipeline-delivering-pareto-optimal-plans-while-enabling-inter-and-intrafraction-plan-adaptation
#5
C Kontaxis, S Breedveld, G Bol, A Sharfo, B Heijmen, J Lagendijk, B Raaymakers
PURPOSE: To develop a new IMRT treatment planning methodology suitable for the new generation of MR-linear accelerator machines. The pipeline is able to deliver Pareto-optimal plans and can be utilized for conventional treatments as well as for inter- and intrafraction plan adaptation based on real-time MR-data. METHODS: A Pareto-optimal plan is generated using the automated multicriterial optimization approach Erasmus-iCycle. The resulting dose distribution is used as input to the second part of the pipeline, an iterative process which generates deliverable segments that target the latest anatomical state and gradually converges to the prescribed dose...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048861/su-g-jep1-09-evaluation-of-transperineal-ultrasound-imaging-as-a-potential-solution-for-target-tracking-during-ablative-body-radiotherapy-for-prostate-cancer
#6
M Najafi, B Han, D Cooper, S Hancock, D Hristov
PURPOSE: Prostate SABR is emerging as a clinically viable, potentially cost effective alternative to prostate IMRT but its adoption is contingent on providing solutions for accurate tracking during beam delivery. Our goal is to evaluate the performance of the Clarity Autoscan ultrasound monitoring system for inter-fractional prostate motion tracking in both phantoms and in-vivo. METHODS: In-vivo evaluation was performed under IRB protocol to allow data collection in prostate patients treated with VMAT whereby prostate was imaged through the acoustic window of the perineum...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048859/su-g-jep4-12-real-time-organ-motion-monitoring-using-ultrasound-and-kv-fluoroscopy-during-lung-sbrt-delivery
#7
E Omari, A Tai, D Cooper, M Lachaine, X Li
PURPOSE: Real-time ultrasound monitoring during SBRT is advantageous in understanding and identifying motion irregularities which may cause geometric misses. In this work, we propose to utilize real-time ultrasound to track the diaphragm in conjunction with periodical kV fluoroscopy to monitor motion of tumor or landmarks during SBRT delivery. METHODS: Transabdominal Ultrasound (TAUS) b-mode images were collected from 10 healthy volunteers using the Clarity Autoscan System (Elekta)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048837/mo-de-202-01-image-guided-focused-ultrasound-surgery-and-therapy
#8
K Farahani
At least three major trends in surgical intervention have emerged over the last decade: a move toward more minimally invasive (or non-invasive) approach to the surgical target; the development of high-precision treatment delivery techniques; and the increasing role of multi-modality intraoperative imaging in support of such procedures. This symposium includes invited presentations on recent advances in each of these areas and the emerging role for medical physics research in the development and translation of high-precision interventional techniques...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048836/su-f-j-30-application-of-intra-fractional-imaging-for-pretreatment-cbct-of-breath-hold-lung-sbrt
#9
D Cao, M Jermoumi, V Mehta, D Shepard
PURPOSE: Clinical implementation of gated lung SBRT requires tools to verify the accuracy of the target positioning on a daily basis. This is a particular challenge on Elekta linacs where the XVI imaging system does not interface directly to any commercial gating solution. In this study, we used the Elekta's intra-fractional imaging functionality to perform the pretreatment CBCT verifications and evaluated both the image quality and gating accuracy. METHODS: To use intrafraction imaging tools for pretreatment verifications, we planned a 360-degree arc with 1mmx5mm MLC opening...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048793/su-f-t-72-experimental-determination-of-the-positionuncertainties-for-roos-ionization-chambers-in-clinical-electron-beams
#10
P von Voigts-Rhetz, T Pretzsch, D Czarnecki, H Vorwerk, K Zink
PURPOSE: National and international dosimetry protocols assume a position accuracy for ionization chambers of less than 0.2mm. To follow this precept the manufacturer PTW-Freiburg introduced a positioning assistance system (TRUFIX) for their particular ion chambers. Aim of this study is an experimental investigation of the positioning uncertainties for ROOS-type ionization chambers. METHODS: For all measurements a linear accelerator Elekta Synergie was used. The experiments were performed in a water-phantom...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048766/su-g-bra-16-target-dose-comparison-for-dynamic-mlc-tracking-and-mid-ventilation-planning-in-lung-radiotherapy-subject-to-intrafractional-baseline-drifts
#11
M J Menten, M F Fast, S Nill, U Oelfke
PURPOSE: Lung tumor motion during radiotherapy can be accounted for by expanded treatment margins, for example using a mid-ventilation planning approach, or by localizing the tumor in real-time and adapting the treatment beam with multileaf collimator (MLC) tracking. This study evaluates the effect of intrafractional changes in the average tumor position (baseline drifts) on these two treatment techniques. METHODS: Lung stereotactic treatment plans (9-beam IMRT, 54Gy/3 fractions, mean treatment time: 9...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048764/tu-d-202-00-rest-in-peace-itv
#12
Marcel van Herk
: Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048752/tu-a-brb-02-panel-member
#13
L Ma
: Brain stereotactic radiosurgery (SRS) and spine stereotactic body radiation therapy (SBRT) are commonly treated by a multidisciplinary team of neurosurgeons, radiation oncologists, and medical physicists. However the treatment objectives, constraints, and technical considerations involved can be quite different between the two techniques. In this interactive session an expert panel of speakers will present clinical brain SRS and spine SBRT cases in order to demonstrate real-world considerations for ensuring safe and accurate treatment delivery and to highlight the significant differences in approach for each treatment site...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048689/su-f-t-294-the-analysis-of-gamma-criteria-for-delta4-dosimetry-using-statistical-process-control
#14
S Cho, S Ahn, J Kim, K Park, W Choi, H Lee, E Lee, J Yoon, K Keum
PURPOSE: To evaluate the sensitivity of gamma criteria for patient-specific volumetric modulated arc therapy(VMAT) quality assurance of the Delta(4) dosimetry program using the statistical process control(SPC) methodology. METHODS: The authors selected 20 patient-specific VMAT QA cases which were undertaken MapCHECK and ArcCHECK with gamma pass rate better than 97%. The QAs data were collected Delta4 Phantom+ and Elekta Agility six megavolts without using an angle incrementer...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048681/mo-fg-campus-tep2-02-first-experiences-and-perspectives-in-using-direct-multicriteria-optimization-mco-on-volumetric-modulated-arc-therapy-vmat-for-head-and-neck-cancer
#15
Samantha Edgington, Christopher Cotter, Paul Busse, Bruce Crawford, Yi Wang
PURPOSE: To report the first experiences and perspectives in using direct multicriteria optimization (MCO) on volumetric-modulated arc therapy (VMAT) for head and neck (H&N) cancer. METHODS: Ten prior patients with tumors in representative H&N regions were selected to evaluate direct MCO-VMAT in RayStation v5.0 beta. The patients were previously treated by intensity-modulated radiation therapy (IMRT) with MCO on an Elekta linear accelerator with Agility multileaf collimator...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048664/tu-d-202-03-gating-is-the-best-itv-killer
#16
D Low
: Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048657/tu-ab-bra-02-an-efficient-atlas-based-synthetic-ct-generation-method
#17
X Han
PURPOSE: A major obstacle for MR-only radiotherapy is the need to generate an accurate synthetic CT (sCT) from MR image(s) of a patient for the purposes of dose calculation and DRR generation. We propose here an accurate and efficient atlas-based sCT generation method, which has a computation speed largely independent of the number of atlases used. METHODS: Atlas-based sCT generation requires a set of atlases with co-registered CT and MR images. Unlike existing methods that align each atlas to the new patient independently, we first create an average atlas and pre-align every atlas to the average atlas space...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048654/su-f-t-233-evaluation-of-treatment-delivery-parameters-using-high-resolution-elekta-log-files
#18
C Kabat, D Defoor, A Alexandrian, N Papanikolaou, S Stathakis
PURPOSE: As modern linacs have become more technologically advanced with the implementation of IGRT and IMRT with HDMLCs, a requirement for more elaborate tracking techniques to monitor components' integrity is paramount. ElektaLog files are generated every 40 milliseconds, which can be analyzed to track subtle changes and provide another aspect of quality assurance. This allows for constant monitoring of fraction consistency in addition to machine reliability. With this in mind, it was the aim of the study to evaluate if ElektaLog files can be utilized for linac consistency QA...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048611/su-f-t-297-quality-assurance-of-multiple-brain-metastases-with-single-isocenter-using-measurement-guided-dose-reconstruction
#19
R Leung, M Wong, V Lee, S Cheung, K Lee, G Law, M Chan
PURPOSE: To evaluate the use of measurement guided dose reconstruction (MGDR) in quality assurance (QA) of stereotactic radiosurgery (SRS) of multiple brain metastases (MBM) planned with single isocenter (SI). METHODS: Seven clinically approved multi-isocenter MBM (MI-MBM) plans were re-optimized using SI (SI-MBM) by coplanar volumetric arc therapy (VMAT) in Monaco v5.0 (Elekta CMS, Maryland Heights, MO, USA). These plans were delivered on an Elekta Agiltiy Linac and measured by OCTAVIUS 4D system with OCTAVIUS 1500 2D array (PTW, Freiburg, Germany)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048602/su-f-t-262-commissioning-varian-portal-dosimetry-for-epid-based-patient-specific-qa-in-a-non-aria-environment
#20
M Schmidt, N Knutson, J Herrington, M Price
PURPOSE: Development of an in-house program facilitates a workflow that allows Electronic Portal Imaging Device (EPID) patient specific quality assurance (QA) measurements to be acquired and analyzed in the Portal Dosimetry Application (Varian Medical Systems, Palo Alto, CA) using a non-Aria Record and Verify (R&V) system (MOSAIQ, Elekta, Crawley, UK) to deliver beams in standard clinical treatment mode. METHODS: Initial calibration of an in-house software tool includes characterization of EPID dosimetry parameters by importing DICOM images of varying delivered MUs to determine linear mapping factors in order to convert image pixel values to Varian-defined Calibrated Units (CU)...
June 2016: Medical Physics
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