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https://www.readbyqxmd.com/read/27910608/x-ray-transport-and-radiation-response-assessment-xtrra-experiments-at-the-national-ignition-facility
#1
K B Fournier, C G Brown, M F Yeoman, J H Fisher, S W Seiler, D Hinshelwood, S Compton, F R Holdener, G E Kemp, C D Newlander, R P Gilliam, N Froula, M Lilly, J F Davis, Maj A Lerch, B E Blue
Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility's diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910392/real-time-radiative-divertor-feedback-control-development-for-the-nstx-u-tokamak-using-a-vacuum-ultraviolet-spectrometer
#2
V A Soukhanovskii, R Kaita, B Stratton
A radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature Te estimated spectroscopically in real time will be used as a control parameter...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910378/development-and-characterization-of-an-interferometer-for-calorimeter-based-absorbed-dose-to-water-measurements-in-a-medical-linear-accelerator
#3
Everardo Flores-Martinez, Martha J Malin, Larry A DeWerd
The quantity of relevance for external beam radiotherapy is absorbed dose to water (ADW). An interferometer was built, characterized, and tested to measure ADW within the dose range of interest for external beam radiotherapy using the temperature dependence of the refractive index of water. The interferometer was used to measure radiation-induced phase shifts of a laser beam passing through a (10 × 10 × 10) cm(3) water-filled glass phantom, irradiated with a 6 MV photon beam from a medical linear accelerator...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910290/radiation-therapy-staffing-model-2014
#4
Leigh J Smith, Rachel Kearvell, Anthony J Arnold, Kevina Choma, Aniko Cooper, Michael R Young, Donna L Matthews, Bronwyn Hilder, Debbie Howson, Katherine Fox, Katheryn Churcher
INTRODUCTION: In 2001, the Radiation Therapy Advisory Panel (RTAP) of the Australian Society of Medical Imaging and Radiation Therapy (ASMIRT) (formerly known as Australian Institute of Radiography) published a model for radiation therapist staffing in Australian radiation oncology departments. Between 2012-2013, the model was reviewed to ensure it reflected current radiation therapy practice, technology, and to facilitate forward planning of the radiation therapy workforce. METHOD: Twenty-four sites from all states participated and provided data on megavoltage simulation, planning and treatment delivery...
December 2016: Journal of Medical Radiation Sciences
https://www.readbyqxmd.com/read/27910001/the-effect-of-influence-quantities-and-detector-orientation-on-small-field-patient-specific-imrt-qa-comparison-of-measurements-with-various-ionization-chambers
#5
Henry Finlay Godson, Ravikumar Manickam, Sathiyan Saminathan, Kadirampatti Mani Ganesh, Retna Ponmalar
Intensity-modulated radiation therapy (IMRT) requires a patient-specific quality assurance (QA) program to validate the treatment plan and a high level of dosimetric accuracy in the treatment delivery. Dosimetric verification generally consists of both absolute- and relative-dose measurements in a phantom using ionization chambers. Measurements were carried out with three different ionization chambers (Scanditronix FC 65G, Exradin A18, and PTW PinPoint 31014) to assess the effects of influence quantities such as the stability, pre- and post-irradiation leakage, stem effect, polarity, and ion recombination on the IMRT point-dose verification with two different orientations...
December 1, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27909957/adaptive-radiation-therapy-in-head-and-neck-cancer-for-clinical-practice-state-of-the-art-and-practical-challenges
#6
REVIEW
Ovidiu Veresezan, Idriss Troussier, Alexis Lacout, Sarah Kreps, Sophie Maillard, Aude Toulemonde, Pierre-Yves Marcy, Florence Huguet, Juliette Thariat
Modern radiation therapy techniques are characterized by high conformality to tumor volumes and steep dose gradients to spare normal organs. These techniques require accurate clinical target volume definitions and rigorous assessment of set up uncertainties using image guidance, a concept called image-guided radiation therapy. Due to alteration of patient anatomy, changes in tissue density/volumes and tumor shrinkage over the course of treatment, treatment accuracy may be challenged. This may result in excessive irradiation of organs at risk/healthy tissues and undercoverage of target volumes with a significant risk of locoregional failure...
December 1, 2016: Japanese Journal of Radiology
https://www.readbyqxmd.com/read/27909738/prostate-bed-target-interfractional-motion-using-rtog-consensus-definitions-and-daily-ct-on-rails-does-target-motion-differ-between-superior-and-inferior-portions-of-the-clinical-target-volume
#7
Vivek Verma, Shifeng Chen, Sumin Zhou, Charles A Enke, Andrew O Wahl
PURPOSE: Using high-quality CT-on-rails imaging, the daily motion of the prostate bed clinical target volume (PB-CTV) based on consensus Radiation Therapy Oncology Group (RTOG) definitions (instead of surgical clips/fiducials) was studied. It was assessed whether PB motion in the superior portion of PB-CTV (SUP-CTV) differed from the inferior PB-CTV (INF-CTV). PATIENTS AND METHODS: Eight pT2-3bN0-1M0 patients underwent postprostatectomy intensity-modulated radiotherapy, totaling 300 fractions...
December 1, 2016: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/27909158/off-site-emergency-planning-at-uk-nuclear-licensed-sites
#8
Paul Leonard, Gareth Thomas
Nuclear emergency planning arrangements in the UK are continually kept under review. This work proposes to outline how experience from nuclear exercises and undertaking emergency response duties can be based on radiological knowledge of specific sites and utilised in the future. In 2014, the UK regulator, the Office for Nuclear Regulation (ONR) revised their principles for the determination of off-site emergency planning areas around nuclear sites where predetermined countermeasures and other protection measures are applied to protect those people who may be affected by a radiation emergency...
December 1, 2016: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/27909157/area-monitoring-of-ambient-dose-rates-in-parts-of-south-western-nigeria-using-a-gps-integrated-radiation-survey-meter
#9
I C Okeyode, J A Rabiu, O O Alatise, V Makinde, F G Akinboro, D Al-Azmi, A O Mustapha
A radiation monitoring system comprising a Geiger-Muller counter connected to a smart phone via Bluetooth was used for a dose rate survey in some parts of south-western Nigeria. The smart phone has the Geographical Positioning System, which provides the navigation information and saves it along with the dose rate data. A large number of data points was obtained that shows the dose rate distribution within the region. The results show that the ambient dose rates in the region range from 60 to 520 nSv (-1) and showed a bias that is attributable to the influence of geology on the ambient radiation dose in the region...
December 1, 2016: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/27908184/irradiation-with-x-rays-of-the-energy-18-mv-induces-radioactivity-in-transfusion-blood-proposal-of-a-safe-method-using-6-mv
#10
Katharina Frentzel, Harun Badakhshi
PURPOSE: To prevent a fatal transfusion-associated graft-versus-host disease, it is recommended to irradiate transfusion blood and blood components with ionizing radiation. Using x-rays from a linear accelerator of the radiotherapy department is an accepted alternative to gamma irradiation devices of the blood bank and to the orthovoltage units that are replacing the gamma irradiators today. However, the use of high energy x-rays may carry a potential risk of induced radioactivity. The objective of this study was to investigate the effect of two different energy levels, 6 and 18 MV, which are executed in routine clinical settings...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908168/examining-credentialing-criteria-and-poor-performance-indicators-for-iroc-houston-s-anthropomorphic-head-and-neck-phantom
#11
Mallory E Carson, Andrea Molineu, Paige A Taylor, David S Followill, Francesco C Stingo, Stephen F Kry
PURPOSE: To analyze the most recent results of the Imaging and Radiation Oncology Core Houston Quality Assurance Center's (IROC-H) anthropomorphic head and neck (H&N) phantom to determine the nature of failing irradiations and the feasibility of altering credentialing criteria. METHODS: IROC-H's H&N phantom, used for intensity-modulated radiation therapy credentialing for National Cancer Institute-sponsored clinical trials, requires that an institution's treatment plan agrees within ±7% of measured thermoluminescent dosimeter (TLD) doses; it also requires that ≥85% of pixels pass ±4 mm distance to agreement (7%/4 mm gamma analysis for film)...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908146/energy-deposition-clustering-as-a-functional-radiation-quality-descriptor-for-modeling-relative-biological-effectiveness
#12
Fernanda Villegas, Gloria Bäckström, Nina Tilly, Anders Ahnesjö
PURPOSE: To explore the use of the frequency of the energy deposition (ED) clusters of different sizes (cluster order, CO) as a surrogate (instead of, e.g., LET) classification of the physical characteristics of ionizing radiation at a nanometer scale, to construct a framework for the calculation of relative biological effectiveness (RBE) with cell survival as endpoint. METHODS: The frequency of cluster order fCO is calculated by sorting the ED sites generated with the Monte Carlo track structure code LIonTrack into clusters based on a single parameter called the cluster distance dC being the maximum allowed distance between two neighboring EDs belonging to a cluster...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27906944/the-safety-of-ct-guided-epidural-steroid-injections-in-an-older-patient-cohort
#13
Andrew J Fenster, Kevin Fernandes, Alan L Brook, Todd Miller
BACKGROUND: Epidural steroid injections (ESIs) are a common method for treating lower back pain, which is one of the most prevalent health-related complaints in the adult US population. Although the safety of CT-guided ESIs has been extensively studied in adults, there is limited data concerning the procedure's safety profile in an older patient population. OBJECTIVE: This retrospective study analyzed safety data among a single-center cohort of patients > 65 years-old who received one or more CT-guided interlaminar ESIs from 2012 to 2015...
November 2016: Pain Physician
https://www.readbyqxmd.com/read/27905164/correlative-study-of-dose-to-thyroid-and-incidence-of-subsequent-dysfunction-after-head-and-neck-radiation
#14
Stella Ling, Aashish D Bhatt, Nicole V Brown, Phuong Nguyen, Jennifer A Sipos, Arnab Chakravarti, Yi Rong
BACKGROUND: Thyroid dysfunction is common after radiotherapy (RT) for patients with head and neck cancers. We attempted to discover RT dose parameters that correspond with RT-induced thyroid dysfunction. METHODS: Records of 102 patients who received RT from 2008 to 2010 were reviewed with respect to thyroid function. Abnormalities were grouped in 2 ways: (1) none, transient, or permanent; and (2) overt or subclinical. RESULTS: At median follow-up of 33...
December 1, 2016: Head & Neck
https://www.readbyqxmd.com/read/27904451/the-ratio-of-weight-loss-to-planning-target-volume-significantly-impacts-setup-errors-in-nasopharyngeal-cancer-patients-undergoing-helical-tomotherapy-with-daily-megavoltage-computed-tomography
#15
Wei-Hsien Hou, Chun-Wei Wang, Chiao-Ling Tsai, Feng-Ming Hsu, Jason Chia-Hsien Cheng
BACKGROUND: Changes in head and neck anatomy during radiation therapy (RT) produce setup uncertainties of nasopharyngeal cancer (NPC) irradiation. We retrospectively analyzed image guidance data to identify clinical predictors of setup errors. PATIENTS AND METHODS: The data of 217 NPC patients undergoing definitive RT on a helical tomotherapy (HT) unit were analyzed. Factors including tumor stage, body mass index, weight loss, and planning target volume (PTV) were assessed as predictors of daily megavoltage computed tomography (MVCT) setup displacements, which were automatically registered using software...
December 1, 2016: Radiology and Oncology
https://www.readbyqxmd.com/read/27904246/noninvasive-imaging-of-the-biliary-system-relevant-to-percutaneous-interventions
#16
REVIEW
Stephen Thomas, Kayleen Jahangir
Clinical data such as history, physical examination, and laboratory tests are useful in identifying patients with biliary obstruction and biliary sources of infection. However, if intervention is planned, noninvasive imaging is needed to confirm the presence, location, and extent of the disease process. Currently, the most commonly available and used noninvasive modalities are ultrasound (US), computed tomography (CT), magnetic resonance (MR), and nuclear medicine hepatobiliary scintigraphy (HIDA). US is quick, portable, readily available, and is commonly the first imaging modality used when biliary pathology is suspected...
December 2016: Seminars in Interventional Radiology
https://www.readbyqxmd.com/read/27903188/the-role-of-diffusion-tensor-imaging-tractography-for-gamma-knife-thalamotomy-planning
#17
João Gabriel Ribeiro Gomes, Alessandra Augusta Gorgulho, Amanda de Oliveira López, Crystian Wilian Chagas Saraiva, Lucas Petri Damiani, Anderson Martins Pássaro, João Victor Salvajoli, Ludmila de Oliveira Siqueira, Bernardo Peres Salvajoli, Antônio Afonso Ferreira De Salles
OBJECTIVE The role of tractography in Gamma Knife thalamotomy (GK-T) planning is still unclear. Pyramidal tractography might reduce the risk of radiation injury to the pyramidal tract and reduce motor complications. METHODS In this study, the ventralis intermedius nucleus (VIM) targets of 20 patients were bilaterally defined using Iplannet Stereotaxy Software, according to the anterior commissure-posterior commissure (AC-PC) line and considering the localization of the pyramidal tract. The 40 targets and tractography were transferred as objects to the GammaPlan Treatment Planning System (GP-TPS)...
December 2016: Journal of Neurosurgery
https://www.readbyqxmd.com/read/27903187/stereotactic-diffusion-tensor-imaging-tractography-for-gamma-knife-radiosurgery
#18
Cormac G Gavin, H Ian Sabin
OBJECTIVE The integration of modern neuroimaging into treatment planning has increased the therapeutic potential and safety of stereotactic radiosurgery. The authors report their method of integrating stereotactic diffusion tensor imaging (DTI) tractography into conventional treatment planning for Gamma Knife radiosurgery (GKRS). The aim of this study was to demonstrate the feasibility of this technique and to address some of the technical limitations of previously reported techniques. METHODS Twenty patients who underwent GKRS composed the study cohort...
December 2016: Journal of Neurosurgery
https://www.readbyqxmd.com/read/27903179/gamma-knife-radiosurgery-for-brain-metastases-from-pulmonary-large-cell-neuroendocrine-carcinoma-a-japanese-multi-institutional-cooperative-study-jlgk1401
#19
Takuya Kawabe, Masaaki Yamamoto, Yasunori Sato, Shoji Yomo, Takeshi Kondoh, Osamu Nagano, Toru Serizawa, Takahiko Tsugawa, Hisayo Okamoto, Atsuya Akabane, Kazuyasu Aita, Manabu Sato, Hidefumi Jokura, Jun Kawagishi, Takashi Shuto, Hideya Kawai, Akihito Moriki, Hiroyuki Kenai, Yoshiyasu Iwai, Masazumi Gondo, Toshinori Hasegawa, Soichiro Yasuda, Yasuhiro Kikuchi, Yasushi Nagatomo, Shinya Watanabe, Naoya Hashimoto
OBJECTIVE In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) of the lung as a variant of large cell carcinoma, and LCNEC now accounts for 3% of all lung cancers. Although LCNEC is categorized among the non-small cell lung cancers, its biological behavior has recently been suggested to be very similar to that of a small cell pulmonary malignancy. The clinical outcome for patients with LCNEC is generally poor, and the optimal treatment for this malignancy has not yet been established...
December 2016: Journal of Neurosurgery
https://www.readbyqxmd.com/read/27903114/a-quantitative-analysis-of-craniopharyngioma-cyst-expansion-during-and-after-radiation-therapy-and-surgical-implications
#20
Kelly Lamiman, Kenneth K Wong, Benita Tamrazi, Jason D Nosrati, Arthur Olch, Eric L Chang, Erin N Kiehna
OBJECTIVE When complete resection of craniopharyngioma is not achievable or the sequelae are prohibitive, limited surgery and radiation therapy have demonstrated excellent local disease control while minimizing treatment-related sequelae. When residual tissue exists, there is a propensity for further cyst development and expansion during and after radiation therapy. This can result in obstructive hydrocephalus, visual changes, and/or clinical decline. The authors present a quantitative analysis of cyst expansion during and after radiotherapy and examine how it affected subsequent management...
December 2016: Neurosurgical Focus
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