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https://www.readbyqxmd.com/read/27911481/photoluminescence-and-thermoluminescence-of-k2-mg-so4-2-eu-and-evaluation-of-its-kinetic-parameters
#1
Archana Deshpande, N S Dhoble, S C Gedam, S J Dhoble
The K2 Mg(SO4 )2 :Eu phosphor, synthesized by a solid-state diffusion method, was studied for its photoluminescence (PL) and thermoluminescence (TL) characteristics. The X-ray diffraction (XRD) pattern of the material was matched with the standard JCPDF No. 36-1499. For PL characteristics, K2 Mg(SO4 )2 :Eu(2)(+) showed an emission peak at 474 nm when excited at 340 nm, while it showed Eu(3)(+) emission at 580 nm, and 594 nm splitting at 613 nm and 618 nm for an excitation of 396 nm wavelength due to radiative transitions from (5) D0 to (7) Fj (j = 0, 1, 2, 3)...
December 2, 2016: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/27911354/a-spectral-interior-ct-by-a-framelet-based-reconstruction-algorithm
#2
Yingmei Wang, Ge Wang, Shuwei Mao, Wenxiang Cong, Zhilong Ji, Jian-Feng Cai, Yangbo Ye
Reducing radiation dose is an important goal in medical computed tomography (CT), for which interior tomography is an effective approach. There have been interior reconstruction algorithms for monochromatic CT, but in reality, X-ray sources are polychromatic. Using a polychromatic acquisition model and motivated by framelet-based image processing algorithms, in this paper, we propose an interior reconstruction algorithm to obtain an image with spectral information assuming only one scan with a current energy-integrating detector...
November 22, 2016: Journal of X-ray Science and Technology
https://www.readbyqxmd.com/read/27911264/percutaneous-radiologically-guided-gastrostomy-tube-placement-comparison-of-antegrade-transoral-and-retrograde-transabdominal-approaches
#3
Zachary M Haber, Hearns W Charles, Jonathan S Gross, Daniel Pflager, Amy R Deipolyi
PURPOSE: We aimed to compare the antegrade transoral and the retrograde transabdominal approaches for fluoroscopy-guided percutaneous gastrostomy tube (G-tube) placement. METHODS: Following institutional review board approval, all G-tubes at two academic hospitals (January 2014 to May 2015) were reviewed retrospectively. Retrograde approach was used at Hospital 1 and both antegrade and retrograde approaches were used at Hospital 2. Chart review determined type of anesthesia used during placement, dose of radiation used, fluoroscopy time, procedure time, medical history, and complications...
December 2, 2016: Diagnostic and Interventional Radiology: Official Journal of the Turkish Society of Radiology
https://www.readbyqxmd.com/read/27911249/international-multicenter-cohort-study-of-pediatric-brain-arteriovenous-malformations-part-2-outcomes-after-stereotactic-radiosurgery
#4
Robert M Starke, Dale Ding, Hideyuki Kano, David Mathieu, Paul P Huang, Caleb Feliciano, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S Grills, Danilo Silva, Mahmoud Abbassy, Symeon Missios, Douglas Kondziolka, Gene H Barnett, L Dade Lunsford, Jason P Sheehan
OBJECTIVE Pediatric patients (age < 18 years) harboring brain arteriovenous malformations (AVMs) are burdened with a considerably higher cumulative lifetime risk of hemorrhage than adults. Additionally, the pediatric population was excluded from recent prospective comparisons of intervention versus conservative management for unruptured AVMs. The aims of this multicenter, retrospective cohort study are to analyze the outcomes after stereotactic radiosurgery for unruptured and ruptured pediatric AVMs. METHODS We analyzed and pooled AVM radiosurgery data from 7 participating in the International Gamma Knife Research Foundation...
December 2, 2016: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/27911139/volumetric-response-of-intracranial-meningioma-after-photon-or-particle-irradiation
#5
Petra Mozes, Jan Oliver Dittmar, Daniel Habermehl, Eric Tonndorf-Martini, Katalin Hideghety, Anne Dittmar, Jürgen Debus, Stephanie E Combs
BACKGROUND: Meningiomas are usually slow growing, well circumscribed intracranial tumors. In symptom-free cases observation with close follow-up imaging could be performed. Symptomatic meningiomas could be surgically removed and/or treated with radiotherapy. The study aimed to evaluate the volumetric response of intracranial meningiomas at different time points after photon, proton, and a mixed photon and carbon ion boost irradiation. PATIENTS AND METHODS: In Group A 38 patients received proton therapy (median dose: 56 GyE in 1...
December 2, 2016: Acta Oncologica
https://www.readbyqxmd.com/read/27910985/uvb-radiation-vitamin-d-and-multiple-sclerosis
#6
H F DeLuca, L Plum
Acheson et al. (1960) observed an inverse relationship between sunlight exposure and the incidence of Multiple Sclerosis (MS). This led to the suggestion that increased levels of vitamin D caused by sunlight in some way suppresses MS. Further, super physiological doses of the metabolically active metabolite of vitamin D, i.e. 1α,25 dihydroxy vitamin D suppresses the animal model of MS i.e. experimental autoimmune encephalomyelitis (EAE). However, this response was accompanied by hypercalcemia. Hypercalcemia itself can suppress EAE...
December 2, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27910829/optimization-of-photon-beam-energies-in-gold-nanoparticle-enhanced-arc-radiation-therapy-using-monte-carlo-methods
#7
B Koger, C Kirkby
As a recent area of development in radiation therapy, gold nanoparticle (GNP) enhanced radiation therapy has shown potential to increase tumour dose while maintaining acceptable levels of healthy tissue toxicity. In this study, the effect of varying photon beam energy in GNP enhanced arc radiation therapy (GEART) is quantified through the introduction of a dose scoring metric, and GEART is compared to a conventional radiotherapy treatment. The PENELOPE Monte Carlo code was used to model several simple phantoms consisting of a spherical tumour containing GNPs (concentration: 15 mg Au g(-1) tumour, 0...
December 2, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910825/monte-carlo-studies-on-water-and-lif-cavity-properties-for-dose-reporting-quantities-when-using-x-ray-and-brachytherapy-sources
#8
Isabela Soares Lopes Branco, Paula Cristina Guimarães Antunes, Gabriel Paiva Fonseca, Hélio Yoriyaz
Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D m,m; and (b) dose to water in medium, D w,m. The discussion about the preferable quantity to be reported is underway. The dose conversion factors, DCF, between dose to water in medium, D w,m, and dose to medium in medium, D m,m, is based on cavity theory and can be obtained using different approaches...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910734/targeting-the-akt-cyclin-d1-pathway-to-overcome-intrinsic-and-acquired-radioresistance-of-tumors-for-effective-radiotherapy
#9
Tsutomu Shimura
PURPOSE: Radiotherapy (RT) is a powerful tool in the treatment of cancer, having the advantage of preserving normal tissues. Clinical outcomes of RT are significantly improved by technological advances, enabling increased radiation doses directed very specifically to a tumor. However, tumor radioresistance remains a major impediment to effective RT. We have shown that human tumor cells surviving after repeated exposure to fractionated radiation (FR) of X-rays for 1 month have acquired radioresistance through constitutive activation of AKT and downstream cyclin D1 nuclear retention...
December 2, 2016: International Journal of Radiation Biology
https://www.readbyqxmd.com/read/27910717/dose-optimisation-for-assessment-of-periodontal-structures-in-cone-beam-ct-examinations
#10
Ayman Al-Okshi, Chrysoula Theodorakou, Christina Lindh
OBJECTIVE: To investigate the relationship between dose and image quality for a dedicated dental Cone Beam CT (CBCT) scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures. METHODS: Radiation dose and image quality measurements were made using the 3D Accuitomo 170 dental CBCT scanner. The SedentexCT IQ phantom was used to investigate the relationship between contrast-to-noise ratio (CNR) and dose-area product (DAP)...
December 2, 2016: Dento Maxillo Facial Radiology
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
#11
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/27910025/cytogenetics-for-biological-dosimetry
#12
Michelle Ricoul, Tamizh Gnana-Sekaran, Laure Piqueret-Stephan, Laure Sabatier
Cytogenetics is the gold-standard in biological dosimetry for assessing a received dose of ionizing radiation. More modern techniques have recently emerged, but none are as specific as cytogenetic approaches, particularly the dicentric assay. Here, we will focus on the principal cytogenetic techniques used for biological dosimetry: the dicentric assay in metaphase cells, the micronuclei assay in binucleated cells, and the premature condensed chromosome (PCC) assay in interphase cells. New fluorescence in situ hybridization (FISH) techniques (such as telomere-centromere hybridization) have facilitated the analysis of the dicentric assay and have permitted to assess the dose a long time after irradiation by translocation analysis (such as by Tri-color FISH or Multiplex-FISH)...
2017: Methods in Molecular Biology
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
#13
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
#14
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/27909635/secondary-neuroendocrine-carcinoma-following-high-dose-radiotherapy-for-head-and-neck-cancer-report-of-two-cases
#15
Amandeep S Taggar, Roderick Simpson, Desiree Hao, Marc Webster, Moosa Khalil, John Lysack, David Skarsgard
Patients treated with radiation have an increased risk of developing second cancers, of which carcinomas, sarcomas, and hematological malignancies have most commonly been reported. Neuroendocrine carcinomas (NEC) are rarely reported in patients previously treated with radiation. Two patients, who had successfully undergone chemoradiotherapy for head and neck cancers at our institution, developed secondary NEC within the radiation field more than five years after the treatment. Both patients underwent curative-intent treatment of secondary malignancies, one with chemotherapy, radiation and surgery (Case 1) and the other with chemotherapy and surgery (Case 2)...
October 25, 2016: Curēus
https://www.readbyqxmd.com/read/27909463/synthetic-nanoparticles-for-delivery-of-radioisotopes-and-radiosensitizers-in-cancer-therapy
#16
REVIEW
Jun Zhao, Min Zhou, Chun Li
Radiotherapy has been, and will continue to be, a critical modality to treat cancer. Since the discovery of radiation-induced cytotoxicity in the late 19th century, both external and internal radiation sources have provided tremendous benefits to extend the life of cancer patients. Despite the dramatic improvement of radiation techniques, however, one challenge persists to limit the anti-tumor efficacy of radiotherapy, which is to maximize the deposited dose in tumor while sparing the rest of the healthy vital organs...
2016: Cancer Nanotechnology
https://www.readbyqxmd.com/read/27909158/off-site-emergency-planning-at-uk-nuclear-licensed-sites
#17
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
#18
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/27909154/towards-a-novel-modular-architecture-for-cern-radiation-monitoring
#19
Hamza Boukabache, Michel Pangallo, Gael Ducos, Nicola Cardines, Antonio Bellotta, Ciarán Toner, Daniel Perrin, Doris Forkel-Wirth
The European Organization for Nuclear Research (CERN) has the legal obligation to protect the public and the people working on its premises from any unjustified exposure to ionising radiation. In this context, radiation monitoring is one of the main concerns of the Radiation Protection Group. After 30 y of reliable service, the ARea CONtroller (ARCON) system is approaching the end of its lifecycle, which raises the need for new, more efficient radiation monitors with a high level of modularity to ensure better maintainability...
November 30, 2016: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/27909130/the-use-of-ultra-low-dose-ct-scans-for-the-evaluation-of-limb-fractures-is-the-reduced-effective-dose-using-ct-in-orthopaedic-injury-reduction-protocol-effective
#20
S R Konda, A M Goch, P Leucht, A Christiano, S Gyftopoulos, G Yoeli, K A Egol
AIMS: To evaluate whether an ultra-low-dose CT protocol can diagnose selected limb fractures as well as conventional CT (C-CT). PATIENTS AND METHODS: We prospectively studied 40 consecutive patients with a limb fracture in whom a CT scan was indicated. These were scanned using an ultra-low-dose CT Reduced Effective Dose Using Computed Tomography In Orthopaedic Injury (REDUCTION) protocol. Studies from 16 selected cases were compared with 16 C-CT scans matched for age, gender and type of fracture...
December 2016: Bone & Joint Journal
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