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https://www.readbyqxmd.com/read/28432806/rapid-acceptance-testing-of-modern-linac-using-on-board-mv-and-kv-imaging-systems
#1
Sridhar Yaddanapudi, Bin Cai, Taylor Harry, Steven Dolly, Baozhou Sun, Hua Li, Keith Stinson, Camille Noel, Lakshmi Santanam, Todd Pawlicki, Sasa Mutic, S Murty Goddu
PURPOSE: The purpose of this study was to develop a novel process for using on-board MV and kV Electronic Portal Imaging Devices (EPIDs) to perform linac acceptance testing (AT) for two reasons: 1) to standardize the assessment of new equipment performance, and 2) to reduce the time to clinical use while reducing physicist workload. METHODS AND MATERIALS: In this study, Varian TrueBeam linacs equipped with amorphous silicon based EPID (aS1000) were used. The conventional set of AT tests and tolerances were used as a baseline guide...
April 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/28429391/technical-note-direct-measurement-of-continuous-tmr-data-with-a-1d-tank-and-automated-couch-movements
#2
Nels C Knutson, Matthew C Schmidt, Matthew D Belley, Ngoc Nguyen, H Harold Li, Erno Sajo, Michael Price
PURPOSE: Real-time dynamic control of the linear accelerator, couch, and imaging parameters during radiation delivery was investigated as a novel technique for acquiring tissue maximum ratio (TMR) data. METHODS: TrueBeam Developer Mode (Varian Medical Systems, Palo Alto, CA) was used to control the linear accelerator using the Extensible Markup Language (XML). A single XML file was used to dynamically manipulate the machine, couch, and imaging parameters during radiation delivery...
April 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28422421/results-of-a-10-year-survey-of-workload-for-10-treatment-vaults-at-a-high-throughput-comprehensive-cancer-center
#3
Ziad H Saleh, Jeho Jeong, Brian Quinn, James Mechalakos, Jean St Germain, Lawrence T Dauer
The workload for shielding purposes of modern linear accelerators (linacs) consists of primary and scatter radiation which depends on the dose delivered to isocenter (cGy) and leakage radiation which depends on the monitor units (MUs). In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays)...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28422381/comparison-of-multi-institutional-varian-probeam-pencil-beam-scanning-proton-beam-commissioning-data
#4
Ulrich W Langner, John G Eley, Lei Dong, Katja Langen
PURPOSE: Commissioning beam data for proton spot scanning beams are compared for the first two Varian ProBeam sites in the United States, at the Maryland Proton Treatment Center (MPTC) and Scripps Proton Therapy Center (SPTC). In addition, the extent to which beams can be matched between gantry rooms at MPTC is investigated. METHOD: Beam data for the two sites were acquired with independent dosimetry systems and compared. Integrated depth dose curves (IDDs) were acquired with Bragg peak ion chambers in a 3D water tank for pencil beams at both sites...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28410679/dual-energy-imaging-method-to-improve-the-image-quality-and-the-accuracy-of-dose-calculation-for-cone-beam-computed-tomography
#5
Kuo Men, Jianrong Dai, Xinyuan Chen, Minghui Li, Ke Zhang, Peng Huang
PURPOSE: To improve the image quality and accuracy of dose calculation for cone-beam computed tomography (CT) images through implementation of a dual-energy cone-beam computed tomography method (DE-CBCT), and evaluate the improvement quantitatively. METHODS: Two sets of CBCT projections were acquired using the X-ray volumetric imaging (XVI) system on a Synergy (Elekta, Stockholm, Sweden) system with 120kV (high) and 70kV (low) X-rays, respectively. Then, the electron density relative to water (relative electron density (RED)) of each voxel was calculated using a projection-based dual-energy decomposition method...
April 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28409334/investigation-of-x-ray-focal-spot-alignment-using-a-jig-of-novel-design
#6
Lockie Yuen, Cameron McLucas
The X-ray focal spot and the centre of the flattening filter should be placed as close as possible to the central axis (CAX) on a linear accelerator (linac) to produce a radially symmetric beam. The aim of this study is to devise a method to easily optimise the focal spot position of Varian linac photon beams generated with a flattening filter. A simple and robust jig was designed and built to be inserted into the largest electron applicator. Accessory and jaw position interlocks were overridden to enable photon beam operation...
April 13, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28399817/assessments-of-serum-copper-and-zinc-concentration-and-the-cu-zn-ratio-determination-in-patients-with-multidrug-resistant-pulmonary-tuberculosis-mdr-tb-in-c%C3%A3-te-d-ivoire
#7
Gnogbo Alexis Bahi, Lydie Boyvin, Souleymane Méité, Gervais Melaine M'Boh, Kadjowely Yeo, Kouassi Raymond N'Guessan, Alain Dit Philippe Bidié, Allico Joseph Djaman
BACKGROUND: In Côte d'Ivoire, multidrug-resistant tuberculosis (MDR-TB) is a serious public health problem with a prevalence estimated at 2.5% in 2006. Zinc and copper are essential Trace element needed to strengthen the immune system and also useful in the fight against tuberculosis. The Cu / Zn ratio is a good indicator of oxidative stress. The principal aim of this study was to evaluate the serum concentration of some trace element and determine the Cu / Zn ratio in patients with multidrug resistant pulmonary tuberculosis (MDR-TB) before and after second line treatment of TB...
April 11, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/28393372/design-and-simulation-of-a-short-variable-energy-4-to-10-mv-s-band-linear-accelerator-waveguide
#8
Devin Baillie, B Gino Fallone, Stephen Steciw
PURPOSE: To modify a previously-designed, short, 10 MV linac waveguide so that it can produce any energy from 4 to 10 MV. The modified waveguide is designed to be a drop-in replacement for the 6MV waveguide used in the author's current linear accelerator-magnetic resonance imager (Linac-MR). METHODS: Using our group's previously designed short 10 MV linac as a starting point, the port was moved to the fourth cavity, the shift to the first coupling cavity was removed and a tuning cylinder added to the first coupling cavity...
April 9, 2017: Medical Physics
https://www.readbyqxmd.com/read/28385495/dosimetric-characterization-of-small-fields-using-a-plastic-scintillator-detector-a-large-multicenter-study
#9
Pietro Mancosu, Massimo Pasquino, Giacomo Reggiori, Laura Masi, Serenella Russo, Michele Stasi
PURPOSE: In modern radiation therapy accurate small fields dosimetry is a challenge and its standardization is fundamental to harmonize delivered dose in different institutions. This study presents a multicenter characterization of MLC-defined small field for Elekta and Varian linear accelerators. Measurements were performed using the Exradin W1 plastic scintillator detector. MATERIALS AND METHODS: The project enrolled 24 Italian centers. Each center performed Tissue Phantom Ratio (TPR), in-plane and cross-plane dose profiles of 0...
April 3, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28384620/recovering-traditional-raw-milk-tetilla-cheese-flavour-and-sensory-attributes-by-using-kocuria-varians-and-yarrowia-lipolytica-adjunct-cultures
#10
J A Centeno, J I Garabal, F Docampo, J M Lorenzo, J Carballo
The rationale of the present study was to evaluate the potential of microbial adjunct cultures including Kocuria varians and/or Yarrowia lipolytica strains in the recovery of the typical sensory profile of traditional (raw-milk) Tetilla cheese. Four batches of Tetilla cheese, a short ripened cows' milk cheese produced in Galicia (NW Spain), were made in duplicate from pasteurized milk inoculated with different microbial cultures. A control batch was manufactured by adding a mesophilic commercial D-starter only...
March 22, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/28383157/development-of-a-novel-low-radiation-absorbent-lok-bar-to-reduce-x-ray-scattering-and-absorption-in-rapidarc-%C3%A2-treatment-planning-and-dose-delivery
#11
Hajime Monzen, Kazuki Kubo, Mikoto Tamura, Masaru Hayakawa, Yasumasa Nishimura
We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmer-type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH)...
April 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28346222/sign-determination-methods-for-the-respiratory-signal-in-data-driven-pet-gating
#12
Ottavia Bertolli, Simon Arridge, Scott D Wollenweber, Charles W Stearns, Brian F Hutton, Kris Thielemans
Patient respiratory motion during PET image acquisition leads to blurring in the reconstructed images and may cause significant artifacts, resulting in decreased lesion detectability, inaccurate standard uptake value calculation and incorrect treatment planning in radiation therapy. To reduce these effects data can be regrouped into (nearly) 'motion-free' gates prior to reconstruction by selecting the events with respect to the breathing phase. This gating procedure therefore needs a respiratory signal: on current scanners it is obtained from an external device, whereas with data driven (DD) methods it can be directly obtained from the raw PET data...
April 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28338869/measurement-of-absorption-dose-outside-irradiation-field-in-imrt
#13
Makoto Hirata, Hajime Monzen, Kohei Hanaoka, Yasumasa Nishimura
The absorption dose outside the irradiation field for prostate intensity-modulated radiation therapy was measured and evaluated by comparison with calculated values of radiation treatment planning system (TPS). The values of TPS calculated were using Varian CLINAC21EX/Eclipse and TomoTherapy Planning System for constant irradiation time. The absorption dose was measured by placing a glass-element dosemeter in a human-bone enclosure phantom with a planning target volume inside the irradiation field. The organs at risk were the rectum, spinal cord, thyroid, eyeball and the left lung...
March 3, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28335778/radiation-dose-escalation-based-on-fdg-pet-driven-dose-painting-by-numbers-in-oropharyngeal-squamous-cell-carcinoma-a-dosimetric-comparison-between-tomotherapy-ha-and-rapidarc
#14
Sarah Differding, Edmond Sterpin, Nicolas Hermand, Bianca Vanstraelen, Sandra Nuyts, Nathalie de Patoul, Jean-Marc Denis, John Aldo Lee, Vincent Grégoire
PURPOSE: Validation of dose escalation through FDG-PET dose painting (DP) for oropharyngeal squamous cell carcinoma (SCC) requires randomized clinical trials with large sample size, potentially involving different treatment planning and delivery systems. As a first step of a joint clinical study of DP, a planning comparison was performed between Tomotherapy HiArt® (HT) and Varian RapidArc® (RA). METHODS: The planning study was conducted on five patients with oropharyngeal SCC...
March 23, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28330268/antimicrobial-activity-of-pvp-coated-silver-nanoparticles-synthesized-by-lysinibacillus-varians
#15
Divya Bhatia, Ashwani Mittal, Deepak Kumar Malik
Emergence of resistant microbes to conventional antibiotics and increased emphasis on health-care costs has raised the concern for the development of new effective antimicrobial reagents. Silver nanoparticles being an excellent broad-spectrum antibacterial agent could be considered as a suitable alternative for existing antibiotic. This study demonstrates the extra-cellular synthesis of stable silver nanoparticles using supernatant of Lysinibacillus varians. The synthesized silver nanoparticles were characterized by using UV-visible spectrum analysis, X-ray diffraction, Transmission electron microscopy (TEM) and FT-IR analysis...
December 2016: 3 Biotech
https://www.readbyqxmd.com/read/28325019/frameless-stereotactic-radiosurgery-fsrs-end-to-end-test-with-ebt-xd-gafchromic-film
#16
Yulin Song, Ceferino Obcemea, Boris Mueller, Borys Mychalczak
Frame-based stereotactic radiosurgery (SRS) has been widely used to treat functional disorders, vascular lesions, and primary benign and malignant tumors. Recently, SRS is being increasingly used to treat solitary brain metastases. However, due to its highly invasive nature, frame-based SRS is being gradually replaced by frameless SRS (fSRS). fSRS aims at improving patient comfort and achieving stable patient immobilization with non-invasive means and accurate target localization with image guidance technique...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28303745/grid-therapy-using-high-definition-multileaf-collimators-realizing-benefits-of-the-bystander-effect
#17
Valery Peng, Natalka Suchowerska, Linda Rogers, Elizabeth Claridge Mackonis, Samantha Oakes, David R McKenzie
BACKGROUND: In microbeam radiotherapy (MRT), parallel arrays of high-intensity synchrotron x-ray beams achieve normal tissue sparing without compromising tumor control. Grid-therapy using clinical linacs has spatial modulation on a larger scale and achieves promising results for palliative treatments of bulky tumors. The availability of high definition multileaf collimators (HDMLCs) with 2.5 mm leaves provides an opportunity for grid-therapy to more closely approach MRT. However, challenges to the wider implementation of grid-therapy remain because spatial modulation of the target volume runs counter to current radiotherapy practice and mechanisms for the beneficial effects of MRT are not fully understood...
March 17, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28300376/moving-gpu-opencl-based-monte-carlo-dose-calculation-toward-clinical-use-automatic-beam-commissioning-and-source-sampling-for-treatment-plan-dose-calculation
#18
Zhen Tian, Yongbao Li, Nima Hassan-Rezaeian, Steve B Jiang, Xun Jia
We have previously developed a GPU-based Monte Carlo (MC) dose engine on the OpenCL platform, named goMC, with a built-in analytical linear accelerator (linac) beam model. In this paper, we report our recent improvement on goMC to move it toward clinical use. First, we have adapted a previously developed automatic beam commissioning approach to our beam model. The commissioning was conducted through an optimization process, minimizing the discrepancies between calculated dose and measurement. We successfully commissioned six beam models built for Varian TrueBeam linac photon beams, including four beams of different energies (6 MV, 10 MV, 15 MV, and 18 MV) and two flattening-filter-free (FFF) beams of 6 MV and 10 MV...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28298966/radiation-dose-enhancement-in-skin-therapy-with-nanoparticle-addition-a-monte-carlo-study-on-kilovoltage-photon-and-megavoltage-electron-beams
#19
Xiao J Zheng, James C L Chow
AIM: To investigated the dose enhancement due to the incorporation of nanoparticles in skin therapy using the kilovoltage (kV) photon and megavoltage (MV) electron beams. Monte Carlo simulations were used to predict the dose enhancement when different types and concentrations of nanoparticles were added to skin target layers of varying thickness. METHODS: Clinical kV photon beams (105 and 220 kVp) and MV electron beams (4 and 6 MeV), produced by a Gulmay D3225 orthovoltage unit and a Varian 21 EX linear accelerator, were simulated using the EGSnrc Monte Carlo code...
February 28, 2017: World Journal of Radiology
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
#20
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
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