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https://www.readbyqxmd.com/read/28214683/neutron-measurements-in-radiotherapy-a-method-to-correct-neutron-sensitive-devices-for-parasitic-photon-response
#1
L Irazola, J A Terrón, R Bedogni, A Pola, M Lorenzoli, E Jimenez-Ortega, A R Barbeiro, B Sánchez-Nieto, F Sánchez-Doblado
One of the major causes of secondary malignancies after radiotherapy treatments are peripheral doses, known to increase for some newer techniques (such as IMRT or VMAT). For accelerators operating above 10MV, neutrons can represent important contribution to peripheral doses. This neutron contamination can be measured using different passive or active techniques, available in the literature. As far as active (or direct-reading) procedures are concerned, a major issue is represented by their parasitic photon sensitivity, which can significantly affect the measurement when the point of test is located near to the field-edge...
February 12, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28197653/does-selective-pleural-irradiation-of-malignant-pleural-mesothelioma-allow-radiation-dose-escalation-a-planning-study
#2
A Botticella, G Defraene, K Nackaerts, C Deroose, J Coolen, P Nafteux, B Vanstraelen, S Joosten, L A W Michiels, S Peeters, D De Ruysscher
BACKGROUND: After lung-sparing radiotherapy for malignant pleural mesothelioma (MPM), local failure at sites of previous gross disease represents the dominant form of failure. Our aim is to investigate if selective irradiation of the gross pleural disease only can allow dose escalation. MATERIALS AND METHODS: In all, 12 consecutive stage I-IV MPM patients (6 left-sided and 6 right-sided) were retrospectively identified and included. A magnetic resonance imaging-based pleural gross tumor volume (GTV) was contoured...
February 14, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/28192503/correction-3d-vmat-verification-based-on-monte-carlo-log-file-simulation-with-experimental-feedback-from-film-dosimetry
#3
A R Barbeiro, A Ureba, J A Baeza, R Linares, M Perucha, E Jiménez-Ortega, S Velázquez, J C Mateos, A Leal
[This corrects the article DOI: 10.1371/journal.pone.0166767.].
2017: PloS One
https://www.readbyqxmd.com/read/28168813/the-impacts-of-mid-treatment-cbct-guided-patient-repositioning-on-target-coverage-during-lung-vmat
#4
Dominique Mathieu, Marie-Pierre Campeau, Stéphane Bedwani, David Roberge, Robert Doucet, Karim Zerouali, Houda Bahig, Toni Vu, Louise Lambert, Laura Masucci, Edith Filion
INTRODUCTION: The purpose of this study is quantify intrafraction motion (IFM) during lung volumetric-modulated arc therapy (VMAT) and evaluate the impact of mid-treatment cone beam computed tomography (CBCT)-guided patient repositioning on target coverage. METHOD: This analysis included lung tumours treated with VMAT to 50-60 Gy in 3-5 fractions. Treatment planning was based on four-dimensional CT scans from which internal tumour volumes (ITV) were derived. An isotropic 5 mm margin was added to obtain the final planning target volume (PTV)...
February 7, 2017: Journal of Medical Imaging and Radiation Oncology
https://www.readbyqxmd.com/read/28168322/radical-hypo-fractionated-radiotherapy-with-volumetric-modulated-arc-therapy-in-lung-cancer-a-retrospective-study-of-elderly-patients-with-stage%C3%A2-iii-disease
#5
D Franceschini, F De Rose, L Cozzi, P Navarria, E Clerici, C Franzese, T Comito, A Tozzi, C Iftode, G D'Agostino, M Sorsetti
BACKGROUND: This study aimed to analyse the feasibility and acute toxicity of radical hypo-fractionated radiotherapy (RT) for elderly patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We conducted a retrospective evaluation of treatment with volumetric modulated arc therapy (VMAT) of elderly patients affected by stage III inoperable NSCLC. The dose prescription was 56 Gy in 20 fractions, 55 Gy in 22 fractions, or 50 Gy in 20 fractions...
February 6, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/28159930/compared-planning-dosimetry-of-tomo-vmat-and-imrt-in-rectal-cancer-with-different-simulated-positions
#6
Jang-Chun Lin, Jo-Ting Tsai, Li-Jhen Chen, Ming-Hsien Li, Wei-Hsiu Liu
OBJECTIVES: To compare treatment plans for helical tomotherapy (TOMO), volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for locally advanced rectal cancer (LARC). MATERIALS AND METHODS: This retrospective study from December 2010 to June 2013 included 20 patients with LARC who received neoadjuvant concurrent chemoradiotherapy (CCRT) with radiation doses of greater than 50.4 Gy. Dosimetric quality was evaluated based on doses to organs at risk (OARs), including small bowel, urinary bladder and bilateral femoral head, over the same coverage of the clinical target volume (CTV)...
January 31, 2017: Oncotarget
https://www.readbyqxmd.com/read/28156666/patterns-of-radiation-therapy-technology-use-in-the-treatment-of-bone-metastases
#7
Robert Anton Olson, Shilo Lefresne, Michael R McKenzie
: 211 Background: In recent years, there has been a transition from two-dimensional radiation therapy (2DRT) planning towards more advanced techniques such as three-dimensional conformal radiation therapy (3D-CRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiation therapy (SBRT). Our study aim was to analyze these trends in the treatment of bone metastases. METHODS: All patients aged 18 and older who had received palliative intent RT for bone metastases between 2009-2014 and referred to any 1 of 6 regional cancer centers in British Columbia, Canada were reviewed...
October 9, 2016: Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology
https://www.readbyqxmd.com/read/28143623/fully-automated-treatment-planning-of-spinal-metastases-a-comparison-to-manual-planning-of-volumetric-modulated-arc-therapy-for-conventionally-fractionated-irradiation
#8
Daniel Buergy, Abdul Wahab M Sharfo, Ben J M Heijmen, Peter W J Voet, Sebastiaan Breedveld, Frederik Wenz, Frank Lohr, Florian Stieler
BACKGROUND: Planning for Volumetric Modulated Arc Therapy (VMAT) may be time consuming and its use is limited by available staff resources. Automated multicriterial treatment planning can eliminate this bottleneck. We compared automatically created (auto) VMAT plans generated by Erasmus-iCycle to manually created VMAT plans for treatment of spinal metastases. METHODS: Forty-two targets in 32 patients were analyzed. Lungs and kidneys were defined as organs at risk (OARs)...
January 31, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28134989/a-swiss-cheese-error-detection-method-for-real-time-epid-based-quality-assurance-and-error-prevention
#9
Michelle Passarge, Michael K Fix, Peter Manser, Marco F M Stampanoni, Jeffrey V Siebers
PURPOSE: To develop a robust and efficient process that detects relevant dose errors (dose errors of ≥5%) in external beam radiation therapy and directly indicates the origin of the error. The process is illustrated in the context of electronic portal imaging device (EPID)-based angle-resolved volumetric modulated arc therapy (VMAT) quality assurance (QA), particularly as would be implemented in a real-time monitoring program. METHODS: A Swiss cheese error detection (SCED) method was created as a paradigm for a cine EPID-based during-treatment QA...
January 30, 2017: Medical Physics
https://www.readbyqxmd.com/read/28133751/feasibility-of-external-beam-radiation-therapy-to-deep-seated-targets-with-kilovoltage-x-rays
#10
Magdalena Bazalova-Carter, Michael D Weil, Dylan Yamabe Breitkreutz, Brian P Wilfley, Edward E Graves
PURPOSE: Radiation therapy to deep-seated targets is typically delivered with megavoltage x-ray beams generated by medical linear accelerators or (60) Co sources. Here, we used computer simulations to design and optimize a lower energy kilovoltage x-ray source generating acceptable dose distributions to a deep-seated target. METHODS: The kilovoltage arc therapy (KVAT) x-ray source was designed to treat a 4-cm diameter target located at a 10-cm depth in a 40-cm diameter homogeneous cylindrical phantom...
December 9, 2016: Medical Physics
https://www.readbyqxmd.com/read/28129972/on-the-use-of-volumetric-modulated-arc-therapy-for-single-fraction-thoracic-vertebral-metastases-stereotactic-body-radiosurgery
#11
Damodar Pokhrel, Sumit Sood, Christopher McClinton, Xinglei Shen, Rajeev Badkul, Hongyu Jiang, Matthew Mallory, Mellissa Mitchell, Fen Wang, Christopher Lominska
To retrospectively evaluate quality, efficiency, and delivery accuracy of volumetric-modulated arc therapy (VMAT) plans for single-fraction treatment of thoracic vertebral metastases using image-guided stereotactic body radiosurgery (SBRS) after RTOG 0631 dosimetric compliance criteria. After obtaining credentialing for MD Anderson spine phantom irradiation validation, 10 previously treated patients with thoracic vertebral metastases with noncoplanar hybrid arcs using 1 to 2 3D-conformal partial arcs plus 7 to 9 intensity-modulated radiation therapy beams were retrospectively re-optimized with VMAT using 3 full coplanar arcs...
January 24, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28128301/discovering-novel-phenotypes-with-automatically-inferred-dynamic-models-a-partial-melanocyte-conversion-in-xenopus
#12
Daniel Lobo, Maria Lobikin, Michael Levin
Progress in regenerative medicine requires reverse-engineering cellular control networks to infer perturbations with desired systems-level outcomes. Such dynamic models allow phenotypic predictions for novel perturbations to be rapidly assessed in silico. Here, we analyzed a Xenopus model of conversion of melanocytes to a metastatic-like phenotype only previously observed in an all-or-none manner. Prior in vivo genetic and pharmacological experiments showed that individual animals either fully convert or remain normal, at some characteristic frequency after a given perturbation...
January 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28126474/can-cost-make-a-difference-dosimetrically-volumetric-modulated-arc-therapy-study-for-multileaf-collimators-of-various-widths-for-head-and-neck-and-prostate-cancers
#13
Jong-Han Ho, Shane Hagler, Carrie Lujano, Sopaul Seng, Christine Starks, Kelly Perrin, Lehendrick Turner, Laurence Court
Cancer is a global health issue that disproportionately kills based on stage of disease, cellular pathology, and genetics, to name a few. Another variable to consider in this ongoing fight is treatment machine complexity that leads to elevated development and purchasing cost, leading to a reduced use. Reducing the complexity (in hopes of lowering costs) would benefit underdeveloped, low- and middle-income countries by introducing newer treatment technology, as their currently accepted standards do not meet standards of more advanced, developed countries...
January 23, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28117079/a-national-dosimetry-audit-for-stereotactic-ablative-radiotherapy-in-lung
#14
Gail Distefano, Jonny Lee, Shakardokht Jafari, Clare Gouldstone, Colin Baker, Helen Mayles, Catharine H Clark
BACKGROUND AND PURPOSE: A UK national dosimetry audit was carried out to assess the accuracy of Stereotactic Ablative Body Radiotherapy (SABR) lung treatment delivery. METHODS AND MATERIALS: This mail-based audit used an anthropomorphic thorax phantom containing nine alanine pellets positioned in the lung region for dosimetry, as well as EBT3 film in the axial plane for isodose comparison. Centres used their local planning protocol/technique, creating 27 SABR plans...
January 20, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#15
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102944/a-simple-and-robust-trajectory-based-stereotactic-radiosurgery-treatment
#16
Byron Wilson, Karl Otto, Ermias Gete
INTRODUCTION: We present a Trajectory-based Volumetric Modulated Arc Therapy (TVMAT) technique for Stereotactic Radiosurgery (SRS) that takes advantage of a modern linacs ability to modulate dose rate and move the couch dynamically. In addition, we investigate the quality of the developed TVMAT method and the dosimetric accuracy of the technique. METHODS: The main feature of the TVMAT technique is a standard beam trajectory formed by dynamic motion of the treatment couch and the linac gantry...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28100239/elective-breast-radiotherapy-including-level-i-and-ii-lymph-nodes-a-planning-study-with-the-humeral-head-as-planning-risk-volume
#17
Kathrin Surmann, Jorien van der Leer, Tammy Branje, Maurice van der Sangen, Maarten van Lieshout, Coen W Hurkmans
BACKGROUND: The aim of this study was to assess the dose to the humeral head planning risk volume with the currently used high tangential fields (HTF) and compare different planning techniques for breast radiotherapy including axillary level I and II lymph nodes (PTVn) while sparing the humeral head. METHODS: Ten patients with left-sided breast cancer were enrolled in a planning study with 16 fractions of 2.66 Gy. Four planning techniques were compared: HTF, HTF with sparing of the humeral head, 6-field IMRT with sparing of the humeral head and VMAT with sparing of the humeral head...
January 18, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28089479/estimation-of-radiation-induced-secondary-cancer-risks-for-early-stage-non-small-cell-lung-cancer-patients-after-stereotactic-body-radiation-therapy
#18
Chunhui Han, Timothy E Schultheiss, Jeffrey Y C Wong
PURPOSE: In this study, we evaluated radiation-induced secondary lung cancer risks for the lung and the breast from stereotactic body radiation therapy treatment of early-stage non-small cell lung cancer with different radiation therapy treatment modalities. METHODS AND MATERIALS: Ten patients (5 men and 5 women) with early-stage non-small cell lung cancer who received definitive stereotactic body radiation therapy treatments were retrospectively selected. For each patient, two 3-dimensional conformal radiation therapy (3D-CRT) plans using 6- and 10-MV photons, respectively; a helical tomotherapy (HT) plan; and 2 volumetric modulated arc therapy (VMAT) plans using 1 and 2 arcs, respectively, were generated...
October 19, 2016: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28079525/a-model-based-3d-patient-specific-pre-treatment-qa-method-for-vmat-using-the-epid
#19
P M McCowan, G Asuni, T van Beek, E van Uytven, K Kujanpaa, B M C McCurdy
This study reports the development and validation of a model-based, 3D patient dose reconstruction method for pre-treatment quality assurance using EPID images. The method is also investigated for sensitivity to potential MLC delivery errors. Each cine-mode EPID image acquired during plan delivery was processed using a previously developed back-projection dose reconstruction model providing a 3D dose estimate on the CT simulation data. Validation was carried out using 24 SBRT-VMAT patient plans by comparing: (1) ion chamber point dose measurements in a solid water phantom, (2) the treatment planning system (TPS) predicted 3D dose to the EPID reconstructed 3D dose in a solid water phantom, and (3) the TPS predicted 3D dose to the EPID and our forward predicted reconstructed 3D dose in the patient (CT data)...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079260/an-experimentally-validated-couch-and-mlc-tracking-simulator-used-to-investigate-hybrid-couch-mlc-tracking
#20
Jakob Toftegaard, Rune Hansen, Thomas Ravkilde, Kristijan Macek, Per Rugaard Poulsen
PURPOSE/OBJECTIVE: Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use the simulator to study hybrid couch-MLC tracking for improved tracking performance. MATERIALS AND METHODS: The tracking simulator requires a treatment plan and a motion trajectory as input and simulates the delivered monitor units and motion of all accelerator parts as function of time...
January 12, 2017: Medical Physics
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