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https://www.readbyqxmd.com/read/28300380/dosimetric-characteristics-of-linatech-dmlc-h-multi-leaf-collimator-monte-carlo-simulation-and-experimental-study
#1
Mikaeil Molazadeh, Ahad Zeinali, Mostafa Robatjazi, Alireza Shirazi, Ghazale Geraily
This study evaluated the basic dosimetric characteristics of a Dynamic Multi Leaf Collimator (DMLC) using a diode detector and film measurements for Intensity Modulated Radiation Therapy Quality Assurance (IMRT QA). The EGSnrc Monte Carlo (MC) simulation system was used for the determination of MLC characteristics. Radiation transmission and abutting leaf leakage relevant to the LinaTech DMLC H were measured using an EDGE detector and EBT3 film. In this study, the BEAMnrc simulation code was used for modeling...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300367/4d-vmat-planning-and-verification-technique-for-dynamic-tracking-using-a-direct-aperture-deformation-dad-method
#2
Yongqian Zhang, Yong Yang, Weihua Fu, Xiang Li, Tianfang Li, Dwight E Heron, M Saiful Huq
We developed a four-dimensional volumetric modulated arc therapy (4D VMAT) planning technique for moving targets using a direct aperture deformation (DAD) method and investigated its feasibility for clinical use. A 3D VMAT plan was generated on a reference phase of a 4D CT dataset. The plan was composed of a set of control points including the beam angle, MLC apertures and weights. To generate the 4D VMAT plan, these control points were assigned to the closest respiratory phases using the temporal information of the gantry angle and respiratory curve...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297461/clinical-experience-with-planning-quality-assurance-and-delivery-of-burst-mode-modulated-arc-therapy
#3
Kristofer Kainz, Douglas Prah, Ergun Ahunbay, X Allen Li
"Burst-mode" modulated arc therapy (hereafter referred to as "mARC") is a form of volumetric-modulated arc therapy characterized by variable gantry rotation speed, static MLCs while the radiation beam is on, and MLC repositioning while the beam is off. We present our clinical experience with the planning techniques and plan quality assurance measurements of mARC delivery. Clinical mARC plans for five representative cases (prostate, low-dose-rate brain, brain with partial-arc vertex fields, pancreas, and liver SBRT) were generated using a Monte Carlo-based treatment planning system...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297456/is-the-dose-distribution-distorted-in-imrt-and-rapidarc-treatment-when-patient-plans-are-swapped-across-beam-matched-machines
#4
Chockkalingam Krishnappan, Chandrasekaran Anu Radha, Vendhan Subramani, Madhan Kumar Gunasekaran
The purpose of this study is to evaluate the degree of dose distribution distortion in advanced treatments like IMRT and RapidArc when patient plans are swapped across dosimetrically equivalent so-called "beam-matched" machines. For this purpose the entire work is divided into two stages. At forefront stage all basic beam properties of 6 MV X-rays like PDD, profiles, output factors, TPR20/10 and MLC transmission of two beam-matched machines - Varian Clinac iX and Varian 600 C/D Unique - are compared and evaluated for differences...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297452/an-epid-based-system-for-gantry-resolved-mlc-quality-assurance-for-vmat
#5
Benjamin J Zwan, Michael P Barnes, Todsaporn Fuangrod, Cameron J Stanton, Daryl J O'Connor, Paul J Keall, Peter B Greer
Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of a comprehensive quality assurance (QA) program for volumetric-modulated arc therapy (VMAT). It is also ideal that such a QA program has the ability to relate MLC positional accuracy to patient-specific dosimetry in order to determine the clinical significance of any detected MLC errors. In this work we propose a method to verify individual MLC trajectories during VMAT deliveries for use as a routine linear accelerator QA tool...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297450/dosimetric-comparison-between-cone-iris-based-and-incise-mlc-based-cyberknife-plans-for-single-and-multiple-brain-metastases
#6
Si Young Jang, Ron Lalonde, Cihat Ozhasoglu, Steven Burton, Dwight Heron, M Saiful Huq
We performed an evaluation of the CyberKnife InCise MLC by comparing plan qualities for single and multiple brain lesions generated using the first version of InCise MLC, fixed cone, and Iris collimators. We also investigated differences in delivery efficiency among the three collimators. Twenty-four patients with single or multiple brain mets treated previously in our clinic on a CyberKnife M6 using cone/Iris collimators were selected for this study. Treatment plans were generated for all lesions using the InCise MLC...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297448/diode-based-transmission-detector-for-imrt-delivery-monitoring-a-validation-study
#7
Taoran Li, Q Jackie Wu, Thomas Matzen, Fang-Fang Yin, Jennifer C O'Daniel
The purpose of this work was to evaluate the potential of a new transmission detector for real-time quality assurance of dynamic-MLC-based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297427/a-comparative-study-of-identical-vmat-plans-with-and-without-jaw-tracking-technique
#8
Hao Wu, Fan Jiang, Haizhen Yue, Qiaoqiao Hu, Jian Zhang, Zhuolun Liu, Jian Gong, Sha Li, Jianhao Geng, Yibao Zhang
The unwanted radiation transmission through the multileaf collimators could be reduced by the jaw tracking technique which is commercially available on Varian TrueBeam accelerators. On the basis of identical plans, this study aims to investigate the dosimetric impact of jaw tracking on the volumetric-modulated arc therapy (VMAT) plans. Using Eclipse treatment planning system (TPS), 40 jaw-tracking VMAT plans with various tumor volumes and shapes were optimized. Fixed jaw plans were created by editing the jaw coordinates of the jaw-tracking plans while other parameters were identical...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297350/impact-of-small-mu-segment-and-dose-rate-on-delivery-accuracy-of-volumetric-modulated-arc-therapy-vmat
#9
Long Huang, Tingliang Zhuang, Anthony Mastroianni, Toufik Djemil, Taoran Cui, Ping Xia
Volumetric-modulated arc therapy (VMAT) plans may require more control points (or segments) than some of fixed-beam IMRT plans that are created with a limited number of segments. Increasing number of control points in a VMAT plan for a given prescription dose could create a large portion of the total number of segments with small number monitor units (MUs) per segment. The purpose of this study is to investigate the impact of the small number MU/segment on the delivery accuracy of VMAT delivered with various dose rates...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297345/a-software-tool-to-automatically-assure-and-report-daily-treatment-deliveries-by-a-cobalt-60-radiation-therapy-device
#10
Deshan Yang, H Omar Wooten, Olga Green, Harold H Li, Shi Liu, Xiaoling Li, Vivian Rodriguez, Sasa Mutic, Rojano Kashani
The aims of this study were to develop a method for automatic and immediate verification of treatment delivery after each treatment fraction in order to detect and correct errors, and to develop a comprehensive daily report which includes delivery verification results, daily image-guided radiation therapy (IGRT) review, and information for weekly physics reviews. After systematically analyzing the requirements for treatment delivery verification and understanding the available information from a commercial MRI-guided radiotherapy treatment machine, we designed a procedure to use 1) treatment plan files, 2) delivery log files, and 3) beam output information to verify the accuracy and completeness of each daily treatment delivery...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297340/dosimetric-properties-of-equivalent-quality-flattening-filter-free-fff-and-flattened-photon-beams-of-versa-hd-linear-accelerator
#11
Mukesh N Meshram, Srimanta Pramanik, C P Ranjith, Saravana K Gopal, Rishabh Dobhal
This study presents the basic dosimetric properties of photon beams of a Versa HD linear accelerator (linac), which is capable of delivering flattening filter-free (FFF) beams with a beam quality equivalent to the corresponding flattened beams based on comprehensive beam data measurement. The analyzed data included the PDDs, profiles, penumbra, out-of-field doses, surface doses, output factors, head and phantom scatter factors, and MLC transmissions for both FFF and flattened beams of 6 MV and 10 MV energy from an Elekta Versa HD linac...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297321/are-simple-imrt-beams-more-robust-against-mlc-error-exploring-the-impact-of-mlc-errors-on-planar-quality-assurance-and-plan-quality-for-different-complexity-beams
#12
Jiazhou Wang, Xiance Jin, Jiayuan Peng, Jiang Xie, Junchao Chen, Weigang Hu
This study investigated the impact of beam complexities on planar quality assurance and plan quality robustness by introducing MLC errors in intensity-modulate radiation therapy. Forty patients' planar quality assurance (QA) plans were enrolled in this study, including 20 dynamic MLC (DMLC) IMRT plans and 20 static MLC (SMLC) IMRT plans. The total beam numbers were 150 and 160 for DMLC and SMLC, respectively. Six different magnitudes of MLC errors were introduced to these beams. Gamma pass rates were calculated by comparing error-free fluence and error-induced fluence...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297319/modeling-the-agility-mlc-in-the-monaco-treatment-planning-system
#13
Michael Snyder, Robert Halford, Cory Knill, Jeffrey N Adams, Todd Bossenberger, Adrian Nalichowski, Ahmad Hammoud, Jay Burmeister
We investigate the relationship between the various parameters in the Monaco MLC model and dose calculation accuracy for an Elekta Agility MLC. The vendor-provided MLC modeling procedure - completed first with external vendor participation and then exclusively in-house - was used in combination with our own procedures to investigate several sets of MLC modeling parameters to determine their effect on dose distributions and point-dose measurements. Simple plans provided in the vendor procedure were used to elucidate specific mechanical characteristics of the MLC, while ten complex treatment plans - five IMRT and five VMAT - created using TG-119-based structure sets were used to test clinical dosimetric effects of particular parameter choices...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297289/a-dosimetric-evaluation-of-knowledge-based-vmat-planning-with-simultaneous-integrated-boosting-for-rectal-cancer-patients
#14
Hao Wu, Fan Jiang, Haizhen Yue, Sha Li, Yibao Zhang
RapidPlan, a commercial knowledge-based optimizer, has been tested on head and neck, lung, esophageal, breast, liver, and prostate cancer patients. To appraise its performance on VMAT planning with simultaneous integrated boosting (SIB) for rectal cancer, this study configured a DVH (dose-volume histogram) estimation model consisting 80 best-effort manual cases of this type. Using the model- generated objectives, the MLC (multileaf collimator) sequences of other 70 clinically approved plans were reoptimized, while the remaining parameters, such as field geometry and photon energy, were maintained...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297283/clinically-relevant-investigation-of-flattening-filter-free-skin-dose
#15
Christopher L Guy, Kishor Karki, Manju Sharma, Siyong Kim
As flattening filter-free (FFF) photon beams become readily available for treatment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2×2,3×3,4×4,6×6,8×8,10×10,20×20, and 30×30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF)...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297276/rounded-leaf-end-modeling-in-pinnacle-vmat-treatment-planning-for-fixed-jaw-linacs
#16
Lori A Young, Fei Yang, Ning Cao, Juergen Meyer
During volume-modulated arc therapies (VMAT), dosimetric errors are introduced by multiple open dynamic leaf gaps that are present in fixed diaphragm linear accelerators. The purpose of this work was to develop a methodology for adjusting the rounded leaf end modeling parameters to improve out-of-field dose agreement in SmartArc VMAT treatment plans delivered by fixed jaw linacs where leaf gap dose is not negligible. Leaf gap doses were measured for an Elekta beam modulator linac with 0.4 cm micro-multileaf collimators (MLC) using an A16 micro-ionization chamber, a MatriXX ion chamber detector array, and Kodak EDR2 film dosimetry in a solid water phantom...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297273/the-dosimetric-impact-of-control-point-spacing-for-sliding-gap-mlc-fields
#17
Benjamin J Zwan, Jonathan Hindmarsh, Erin Seymour, Kankean Kandasamy, Kirbie Sloan, Rajesakar David, Christopher Lee
Dynamic sliding gap multileaf collimator (MLC) fields are used to model MLC properties within the treatment planning system (TPS) for dynamic treatments. One of the key MLC properties in the Eclipse TPS is the dosimetric leaf gap (DLG) and precise determination of this parameter is paramount to ensuring accurate dose delivery. In this investigation, we report on how the spacing between control points (CPs) for sliding gap fields impacts the dose delivery, MLC positioning accuracy, and measurement of the DLG...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296313/determination-of-mlc-model-parameters-for-monaco-using-commercial-diode-arrays
#18
Paul Kinsella, Laura Shields, Patrick McCavana, Brendan McClean, Brian Langan
Multileaf collimators (MLCs) need to be characterized accurately in treatment planning systems to facilitate accurate intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). The aim of this study was to examine the use of MapCHECK 2 and ArcCHECK diode arrays for optimizing MLC parameters in Monaco X-ray voxel Monte Carlo (XVMC) dose calculation algorithm. A series of radiation test beams designed to evaluate MLC model parameters were delivered to MapCHECK 2, ArcCHECK, and EBT3 Gafchromic film for comparison...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296308/clinical-implications-of-the-overshoot-effect-for-treatment-plan-delivery-and-patient-specific-quality-assurance-for-step-and-shoot-imrt
#19
John A Baines, Sylwia J Zawlodzka, Matthew L Parfitt, Brigid E Hickey, Andrew P Pullar
In this work, overshoot and undershoot effects associated with step-and-shoot IMRT (SSIMRT) delivery on a Varian Clinac 21iX are investigated, and their impact on patient-specific QA point dose measurements and treatment plan delivery are evaluated. Pinnacle(3) SSIMRT plans consisting of 5, 10, and 15 identical 5×5 cm2 MLC defined segments and MU/segment values of 5 MU, 10 MU, and 20 MU were utilized and delivered at 600/300 MU/min. Independent of the number of segments the overshoot and undershoot at 600 MU/min were approximately ±10%,±5%, and ±2...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296306/a-novel-phantom-and-procedure-providing-submillimeter-accuracy-in-daily-qa-tests-of-accelerators-used-for-stereotactic-radiosurgery
#20
Ivan A Brezovich, Richard A Popple, Jun Duan, Sui Shen, Xingen Wu, Sidi Benhabib, Mi Huang, Rex A Cardan
Stereotactic radiosurgery (SRS) places great demands on spatial accuracy. Steel BBs used as markers in quality assurance (QA) phantoms are clearly visible in MV and planar kV images, but artifacts compromise cone-beam CT (CBCT) isocenter localization. The purpose of this work was to develop a QA phantom for measuring with sub-mm accuracy isocenter congruence of planar kV, MV, and CBCT imaging systems and to design a practical QA procedure that includes daily Winston-Lutz (WL) tests and does not require computer aid...
July 2016: Journal of Applied Clinical Medical Physics
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