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Varian developer mode

Brendan Whelan, Lois Holloway, Dragos Constantin, Brad Oborn, Magdalena Bazalova-Carter, Rebecca Fahrig, Paul Keall
PURPOSE: MRI-linac therapy is a rapidly growing field, and requires that conventional linear accelerators are operated with the fringe field of MRI magnets. One of the most sensitive accelerator components is the electron gun, which serves as the source of the beam. The purpose of this work was to develop a validated finite element model (FEM) model of a clinical triode (or gridded) electron gun, based on accurate geometric and electrical measurements, and to characterize the performance of this gun in magnetic fields...
November 2016: Medical Physics
Eduardo Pardo, Juan Castro Novais, María Yolanda Molina López, Sheila Ruiz Maqueda
Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C-Arm linacs for intensity-modulated treatments. This mode, called flattening filter-free (FFF), offers the advantage of a greater dose rate. Varian's "Portal Dosimetry" is an electronic portal imager device (EPID)-based tool for IMRT verification. This tool lacks the capability of verifying flattening filter-free (FFF) modes due to saturation and lack of an image prediction algorithm. (Note: the latest versions of this software and EPID correct these issues...
2016: Journal of Applied Clinical Medical Physics
Madelaine K Tyler, Paul Z Y Liu, Christopher Lee, David R McKenzie, Natalka Suchowerska
Flattening filter-free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization cham-bers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney...
2016: Journal of Applied Clinical Medical Physics
Ziyad A Alrowaili, Michael L F Lerch, Marco Petasecca, Martin G Carolan, Peter E Metcalfe, Anatoly B Rosenfeld
The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in trans-mission mode (MPTM). The MPTM is an essential component of a real-time QA system designed for operation during radiotherapy treatment. Of particular interest is a quantitative study into the influence of the MP on the radiation beam quality at several field sizes and linear accelerator potential differences. The impact is measured through beam perturbation effects such as changes in the skin dose and/or percentage depth dose (PDD) (both in and out of field)...
2016: Journal of Applied Clinical Medical Physics
Victoria Y Yu, Angelia Tran, Dan Nguyen, Minsong Cao, Dan Ruan, Daniel A Low, Ke Sheng
PURPOSE: Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. METHODS: A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model...
November 2015: Medical Physics
Robert Maglieri, Angel Licea, Michael Evans, Jan Seuntjens, John Kildea
PURPOSE: Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers...
November 2015: Medical Physics
Gilmer Valdes, Olivier Morin, Yanisley Valenciaga, Niel Kirby, Jean Pouliot, Cynthia Chuang
The purpose of this study was to automate regular Imaging QA procedures to become more efficient and accurate. Daily and monthly imaging QA for SRS and SBRT protocols were fully automated on a Varian linac. A three-step paradigm where the data are automatically acquired, processed, and analyzed was defined. XML scripts were written and used in developer mode in a TrueBeam linac to automatically acquire data. MATLAB R013B was used to develop an interface that could allow the data to be processed and analyzed...
2015: Journal of Applied Clinical Medical Physics
R O'Brien, J Lyon, J Ng, A Bergman, J Booth, P Keall
PURPOSE: Image quality from Four Dimensional Cone Beam Computed Tomography (4DCBCT) is poor due to projection clustering and under sampling. We have developed a novel method called respiratory motion guided 4DCBCT (RMG-4DCBCT) in which the gantry speed and projection frequency are varied in response to the patients real-time respiratory signal. The method has been shown theoretically to improve image quality by 63% on average. The purpose of this study was to implement RMG-4DCBCT on a linear accelerator for a variety of lung cancer patient breathing rates...
June 2015: Medical Physics
I Xhaferllari, O El-Sherif, S Gaede
PURPOSE: To determine the correlation between internal tumor motion and external surrogate motion and any potential phase shifts during respiratory-gated VMAT delivery using on-board kV imaging. METHODS: A respiratory motion phantom was used to trace the motion of an internal target, embedded with a 3 cm moving target, and an external surrogate. On-board kV projections were acquired at 11 frames per second during VMAT delivery on a TrueBeam v.1.6 (Varian Medical Systems, Palo Alto, CA) operating in developer mode...
June 2015: Medical Physics
Y Zhang, F Yin, R Mao, R Gao, L Ren
PURPOSE: To develop a dual-detector phase-matched DTS technique for continuous and fast intra-treatment lung tumor localization. METHODS: Tumor localization accuracy of limited-angle DTS imaging is affected by low inter-slice resolution. The dual-detector DTS technique aims to overcome this limitation through combining orthogonally acquired beam's eye view MV projections and kV projections for intra-treatment DTS reconstruction and localization. To aggregate the kV and MV projections for reconstruction, the MV projections were linearly converted to synthesize corresponding kV projections...
June 2015: Medical Physics
P Mishra, J Lewis, A Patankar, A Etmektzoglou, M Svatos
PURPOSE: We introduce Veritas 2.0, a cloud-based, non-clinical research portal, to facilitate translation of radiotherapy research ideas to new delivery techniques. The ecosystem of research tools includes web apps for a research beam builder for TrueBeam Developer Mode, an image reader for compressed and uncompressed XIM files, and a trajectory log file based QA/beam delivery analyzer. METHODS: The research beam builder can generate TrueBeam readable XML file either from scratch or from pre-existing DICOM-RT plans...
June 2015: Medical Physics
V Yu, D Nguyen, A Tran, D Ruan, M Cao, T Kaprealian, P Kupelian, D Low, K Sheng
PURPOSE: To develop and clinically implement 4π radiotherapy, an inverse optimization platform that maximally utilizes non-coplanar intensity modulated radiotherapy (IMRT) beams to significantly improve critical organ sparing. METHODS: A 3D scanner was used to digitize the human and phantom subject surfaces, which were positioned in the computer assisted design (CAD) model of a TrueBeam machine to create a virtual geometrical model, based on which, the feasible beam space was calculated for different tumor locations...
June 2015: Medical Physics
J Liang, D Hristov, K Otto, S Kim
PURPOSE: To assess the potential benefit of trajectory modulated arc therapy (TMAT) for treatments of small benign intracranial tumor, pituitary adenoma. METHODS: A TMAT planning platform that incorporates complex source motion trajectory involving synchronized gantry rotation with translational and rotational couch movement was used for the study. The platform couples an interactive trajectory generation tool with a VMAT algorithm that performs multi-resolution, progressive sampling MLC optimization on a user-designed trajectory...
June 2015: Medical Physics
E Chin, K Otto, R Hoppe, L Million, B Loo, A Koong, L Xing, A Hsu, B Fahimian
PURPOSE: Integration of coordinated robotic table motion with inversely-planned arc delivery has the potential to resolve table-top delivery limitations of large-field treatments such as Total Body Irradiation (TBI), Total Lymphoid Irradiation (TLI), and Cranial-Spinal Irradiation (CSI). We formulate the foundation for Trajectory Modulated Arc Therapy (TMAT), and using Varian Developer Mode capabilities, experimentally investigate its practical implementation for such techniques. METHODS: A MATLAB algorithm was developed for inverse planning optimization of the table motion, MLC positions, and gantry motion under extended-SSD geometry...
June 2015: Medical Physics
L Yuan, Y Ge, Y Sheng, F Yin, Q J Wu
PURPOSE: We present an implementation of the knowledge-based planning method utilizing a rapid learning approach which enables the accurate evolution of models as new data are collected during daily clinical practice. METHODS: The efficacy of knowledge-based planning depends on the accuracy of the knowledge models. Existing methods for knowledge modeling are all based on batch training approach using a static set of training cases. In this study, we investigate a rapid learning approach to train the models using plans from daily clinical practice...
June 2015: Medical Physics
A Etmektzoglou, P Mishra, M Svatos
PURPOSE: To automate creation and delivery of robotic linac trajectories with TrueBeam Developer Mode, an open source spreadsheet-based trajectory generation tool has been developed, tested and made freely available. The computing power inherent in a spreadsheet environment plus additional functions programmed into the tool insulate users from the underlying schema tedium and allow easy calculation, parameterization, graphical visualization, validation and finally automatic generation of Developer Mode XML scripts which are directly loadable on a TrueBeam linac...
June 2015: Medical Physics
A Tran, V Yu, D Nguyen, K Woods, D Low, K Sheng
PURPOSE: Knowledge learned from previous plans can be used to guide future treatment planning. Existing knowledge-based treatment planning methods study the correlation between organ geometry and dose volume histogram (DVH), which is a lossy representation of the complete dose distribution. A statistical voxel dose learning (SVDL) model was developed that includes the complete dose volume information. Its accuracy of predicting volumetric-modulated arc therapy (VMAT) and non-coplanar 4π radiotherapy was quantified...
June 2015: Medical Physics
B Cai, S Yaddanapudi, B Sun, H Li, C Noel, S Mutic, S Goddu
PURPOSE: In a previous study we have demonstrated the feasibility of using EPID to QA electron beam parameters on a single Varian TrueBeam LINAC. This study aims to provide further investigation on (1) reproducibility of using EPID to detect electron beam energy changes on multiple machines and (2) evaluation of appropriate calibration methods to compare results from different EPIDs. METHODS: Ad-hoc mode electron beam images were acquired in developer mode with XML code...
June 2015: Medical Physics
S Thomas, V Huang, M Milette, C Yuen, T Teke
PURPOSE: In this abstract we implement and validate a 4D VMAT Acuros XB dose calculation using Gafchromic film. Special attention is paid to the physical material assignment in the CT dataset and to reported dose to water and dose to medium. METHODS: A QUASAR phantom with a 3 cm sinusoidal tumor motion and 5 second period was scanned using 4D computed tomography. A CT was also obtained of the static QUASAR phantom with the tumor at the central position. A VMAT plan was created on the average CT dataset and was delivered on a Varian TrueBeam linear accelerator...
June 2015: Medical Physics
N Miri, C Baltes, P Keller, P Greer
PURPOSE: To develop and evaluate models for dose verification of flattened (FF) and flattening filter free (FFF) beams for the new Varian aS1200 backscatter-shielded electronic portal imaging device (EPID). METHODS: The model converts EPID images to incident energy fluence using deconvolution of EPID scatter kernels and fluence to dose in water using convolution with dose-to-water kernels. Model parameters were optimized using non-transmission EPID images of varying jaw defined field sizes for energies of 6 and 10 MV FF and FFF beams...
June 2015: Medical Physics
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