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Sample records for marika mgi ragnar

  1. Ragnar Granit 100 years--memories and reflections.

    PubMed

    Kernell, D

    2000-12-01

    The Swedish-Finnish Nobel laureate Ragnar Granit, born 100 years ago, is commemorated in a brief article by one of his former PhD students and collaborators. After a short account of Granit's life and scientific career, special attention is given to Granit's role as a teacher in research training and his published thoughts on this matter, partly reflecting Granit's own experience as a "postdoc" in the laboratory of Sherrington (Oxford). The article includes personal recollections of how it was to work together with Granit in his laboratory. PMID:11232369

  2. Ragnar Rommetveit's Approach to Everyday Spoken Dialogue from Within.

    PubMed

    Kowal, Sabine; O'Connell, Daniel C

    2016-04-01

    The following article presents basic concepts and methods of Ragnar Rommetveit's (born 1924) hermeneutic-dialogical approach to everyday spoken dialogue with a focus on both shared consciousness and linguistically mediated meaning. He developed this approach originally in his engagement of mainstream linguistic and psycholinguistic research of the 1960s and 1970s. He criticized this research tradition for its individualistic orientation and its adherence to experimental methodology which did not allow the engagement of interactively established meaning and understanding in everyday spoken dialogue. As a social psychologist influenced by phenomenological philosophy, Rommetveit opted for an alternative conceptualization of such dialogue as a contextualized, partially private world, temporarily co-established by interlocutors on the basis of shared consciousness. He argued that everyday spoken dialogue should be investigated from within, i.e., from the perspectives of the interlocutors and from a psychology of the second person. Hence, he developed his approach with an emphasis on intersubjectivity, perspectivity and perspectival relativity, meaning potential of utterances, and epistemic responsibility of interlocutors. In his methods, he limited himself for the most part to casuistic analyses, i.e., logical analyses of fictitious examples to argue for the plausibility of his approach. After many years of experimental research on language, he pursued his phenomenologically oriented research on dialogue in English-language publications from the late 1980s up to 2003. During that period, he engaged psycholinguistic research on spoken dialogue carried out by Anglo-American colleagues only occasionally. Although his work remained unfinished and open to development, it provides both a challenging alternative and supplement to current Anglo-American research on spoken dialogue and some overlap therewith. PMID:26597220

  3. MouseMine: a new data warehouse for MGI.

    PubMed

    Motenko, H; Neuhauser, S B; O'Keefe, M; Richardson, J E

    2015-08-01

    MouseMine (www.mousemine.org) is a new data warehouse for accessing mouse data from Mouse Genome Informatics (MGI). Based on the InterMine software framework, MouseMine supports powerful query, reporting, and analysis capabilities, the ability to save and combine results from different queries, easy integration into larger workflows, and a comprehensive Web Services layer. Through MouseMine, users can access a significant portion of MGI data in new and useful ways. Importantly, MouseMine is also a member of a growing community of online data resources based on InterMine, including those established by other model organism databases. Adopting common interfaces and collaborating on data representation standards are critical to fostering cross-species data analysis. This paper presents a general introduction to MouseMine, presents examples of its use, and discusses the potential for further integration into the MGI interface. PMID:26092688

  4. Nobel prize: 3 named for medicine, physiology award (George Wald, Ragnar Granit and Haldan Keffer Hartline).

    PubMed

    Dolwing, J E; Ratliff, F

    1967-10-27

    Three scientists, George Wald, Ragnar Granit, and Haldan Keffer Hartline, were named last week to share the 1967 Nobel prize in medicine or physiology. Wald is professor of biology at Harvard University. Granit is retired director of the Neurophysiological Institute of the Royal Medical School in Stockholm; at present he is serving as a visiting professor at St. Catherine's College in Oxford. Hartline is professor of biophysics at Rockefeller University. The following are appreciations and descriptions of Wald's work by John E. Dowling and of Granit's and Hartline's work by Floyd Ratliff. PMID:4860394

  5. Integrating text mining into the MGI biocuration workflow.

    PubMed

    Dowell, K G; McAndrews-Hill, M S; Hill, D P; Drabkin, H J; Blake, J A

    2009-01-01

    A major challenge for functional and comparative genomics resource development is the extraction of data from the biomedical literature. Although text mining for biological data is an active research field, few applications have been integrated into production literature curation systems such as those of the model organism databases (MODs). Not only are most available biological natural language (bioNLP) and information retrieval and extraction solutions difficult to adapt to existing MOD curation workflows, but many also have high error rates or are unable to process documents available in those formats preferred by scientific journals.In September 2008, Mouse Genome Informatics (MGI) at The Jackson Laboratory initiated a search for dictionary-based text mining tools that we could integrate into our biocuration workflow. MGI has rigorous document triage and annotation procedures designed to identify appropriate articles about mouse genetics and genome biology. We currently screen approximately 1000 journal articles a month for Gene Ontology terms, gene mapping, gene expression, phenotype data and other key biological information. Although we do not foresee that curation tasks will ever be fully automated, we are eager to implement named entity recognition (NER) tools for gene tagging that can help streamline our curation workflow and simplify gene indexing tasks within the MGI system. Gene indexing is an MGI-specific curation function that involves identifying which mouse genes are being studied in an article, then associating the appropriate gene symbols with the article reference number in the MGI database.Here, we discuss our search process, performance metrics and success criteria, and how we identified a short list of potential text mining tools for further evaluation. We provide an overview of our pilot projects with NCBO's Open Biomedical Annotator and Fraunhofer SCAI's ProMiner. In doing so, we prove the potential for the further incorporation of semi

  6. Ragnar granit.

    PubMed

    Ratliff, F

    1967-10-27

    If it shall be demanded, then, when a man begins to have any ideas? I think the true answer is, when he first has any sensation. For since there appear not to be any ideas in the mind before the senses have conveyed any in, I conceive that ideas in the understanding are coeval with sensation. . . . PMID:17749064

  7. Feasibility study for a 40-MGY/80-MGY fuel-alcohol production plant. Equipment data, vendor correspondence and catalog cuts

    SciTech Connect

    Not Available

    1982-08-01

    The purpose of this study was to assess the feasibility of construction and operation of a 40 to 80 million gallon per year (MGY) fuel alcohol production plant at a site along the Coosa River in Talladega County, Alabama, about 50 miles from Birmingham. This volume contains a compilation of vendor's quotes and catalog cuts pertaining to equipment selected for the process. The information is presented under the following headings: corn storage and milling; cooking and saccharification; fermentation; fungal amylase production; distillation; evaporator system and solids removal; and grain drying. (DMC)

  8. MARIKA - A model revision system using qualitative analysis of simulations. [of human orientation system

    NASA Technical Reports Server (NTRS)

    Groleau, Nicolas; Frainier, Richard; Colombano, Silvano; Hazelton, Lyman; Szolovits, Peter

    1993-01-01

    This paper describes portions of a novel system called MARIKA (Model Analysis and Revision of Implicit Key Assumptions) to automatically revise a model of the normal human orientation system. The revision is based on analysis of discrepancies between experimental results and computer simulations. The discrepancies are calculated from qualitative analysis of quantitative simulations. The experimental and simulated time series are first discretized in time segments. Each segment is then approximated by linear combinations of simple shapes. The domain theory and knowledge are represented as a constraint network. Incompatibilities detected during constraint propagation within the network yield both parameter and structural model alterations. Interestingly, MARIKA diagnosed a data set from the Massachusetts Eye and Ear Infirmary Vestibular Laboratory as abnormal though the data was tagged as normal. Published results from other laboratories confirmed the finding. These encouraging results could lead to a useful clinical vestibular tool and to a scientific discovery system for space vestibular adaptation.

  9. Preparation and properties of high purity Mg-Y biomaterials.

    PubMed

    Peng, Qiuming; Huang, Yuanding; Zhou, Le; Hort, Norbert; Kainer, Karl Ulrich

    2010-01-01

    An effective zone solidification method has been found to prepare high purity Mg-Y biomaterials. The corrosion and mechanical properties of the purified middle region are improved remarkably compared with common casting method. The average gain size and secondary dendrite space decrease from the top layer to the bottom layer of the ingot. The oxides, defects and precipitates are mainly enriched in the top layer of the ingot under the impulsion of high thermal gradient. These results are in agreement with that simulated by finite elemental method using FLOW-3D software. It is confirmed that the mode of scallop symmetric solidification attributes to the purifying process. This zone solidification method not only contributes to high purity Mg-based biomaterials, but also provides a new approach to prepare high performance Mg alloys. PMID:19800117

  10. Draft genome sequence of Pseudomonas oleovorans strain MGY01 isolated from deep sea water.

    PubMed

    Wang, Runping; Ren, Chong; Huang, Nan; Liu, Yang; Zeng, Runying

    2015-04-01

    Pseudomonas oleovorans MGY01 isolated from the deep-sea water of the South China Sea could effectively degrade malachite green. The draft genome of P. oleovorans MGY01 was sequenced and analyzed to gain insights into its efficient metabolic pathway for degrading malachite green. The data obtained revealed 109 Contigs (N50; 128,269 bp) with whole genome size of 5,201,892 bp. The draft genome sequence of strain MGY01 will be helpful in studying the genetic pathways involved in the degradation of malachite green. PMID:25528517

  11. Disruption and Runaway Electron Mitigation With MGI in DIII-D

    NASA Astrophysics Data System (ADS)

    Wesley, J. C.; Humphreys, D. A.; Parks, P. B.; Strait, E. J.; Hollmann, E. M.; Antar, G.; Jernigan, T. C.; Combs, S. K.; Groth, M.

    2006-10-01

    Past and ongoing disruption mitigation studies in DIII-D employing massive gas injection (MGI) are reviewed and compared with theoretical expectations. Emphasis in the review will be placed on 1) the gas hydrodynamic delivery considerations that determine the rate of impurity and electron delivery to the plasma edge, 2) the role of MHD instability and internal reconnection in effecting edge-to-core mixing of the edge-deposited impurities, and 3) assessment of the mechanism(s) whereby MGI mitigates divertor energy deposition, reduces halo current magnitude and asymmetry and avoids runaway electron production and/or Coulomb-avalanche multiplication. Selected considerations for application of DIII-D MGI results to ITER (wherein time scales for impurity delivery are relaxed relative to DIII-D and other present experiments) will also be addressed.

  12. Isomeric yield ratios of 87m,gY from different nuclear reactions

    NASA Astrophysics Data System (ADS)

    Naik, H.; Kim, G. N.; Kim, K.; Zaman, M.; Sahid, M.; Yang, S.-C.; Lee, M. W.; Kang, Y. R.; Shin, S. G.; Cho, M.-H.; Goswami, A.; Song, T. Y.

    2014-07-01

    The independent isomeric yield ratios of 87m,gY produced from the 93Nb( γ, α2n) and natZr( γ, p xn) reactions with the end-point bremsstrahlung energy of 45-70 MeV have been determined by an off-line γ-ray spectrometric technique using 100 MeV electron linac at the Pohang accelerator laboratory, Korea. The isomeric yield ratios of 87m,gY were also determined from the natZr(p, αxn) and the 89Y(p,p2n) reactions with E P = 15-45 MeV as well as those from the 89Y( α, α2n) reaction with E α = 32-43 MeV using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Science, Korea. The isomeric yield ratios of 87m,gY from the present work in the 93Nb( γ, α2n), natZr( γ, p xn), natZr(p, αxn), 89Y(p,p2n), and 89Y( α, α2n) reactions were compared with those of the literature data in the 85Rb( α, 2n), the 86,87,88Sr(d, xn), 89Y(n,3n), and the 89Y( γ, 2n) reactions to examine the role of target, projectiles, and ejectiles through compound nucleus excitation energy and input angular momentum. The isomeric yield ratios of 87m,gY in the above eleven reactions were also calculated using the computer code TALYS 1.4 and compared with the experimental data. The different behaviors between photon- and neutron-induced reactions and charged-particle-induced reactions are discussed from the viewpoint of compound and non-compound (pre-equilibrium) process.

  13. Effects of spin-orbit coupling on laser cooling of BeI and MgI

    SciTech Connect

    Wan, Mingjie Huang, Duohui; Shao, Juxiang; Li, Yuanyuan; Yu, You; Li, Song

    2015-10-28

    We present the ab initio study of spin-orbit coupling effects on laser cooling of BeI and MgI molecules. Potential energy curves for the X{sup 2}Σ{sup +}{sub 1/2}, A{sup 2}Π{sub 1/2,3/2}, and 2{sup 2}Π{sub 3/2,1/2} states are calculated using multi-reference configuration interaction method plus Davidson corrections. Spectroscopic parameters of BeI and MgI are in excellent agreement with available experimental and theoretical values. The A{sup 2}Π{sub 3/2} state of MgI is a repulsive state. It is an unsuitable scheme for the A{sup 2}Π{sub 3/2}(υ′)← X{sup 2}Σ{sup +}{sub 1/2} (υ″) transition for laser cooling of MgI. Highly diagonally distributed Franck-Condon factors f{sub 00} for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) ← X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transitions and suitable radiative lifetimes τ for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) of BeI and MgI are obtained. Three laser wavelength drives are required for the A{sup 2}Π{sub 1/2,3/2}(υ′)←X{sup 2}Σ{sup +}{sub 1/2} (υ″) transitions of BeI and MgI. The proposed cooling wavelengths of BeI and MgI are both in the violet region. The results imply the feasibility of laser cooling of BeI and MgI, and that laser cooling of BeI is more possible.

  14. Mechanical Properties of Mg-Gd and Mg-Y Solid Solutions

    NASA Astrophysics Data System (ADS)

    Kula, Anna; Jia, Xiaohui; Mishra, Raj K.; Niewczas, Marek

    2015-12-01

    The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4 K and 298 K (-269 °C and 25 °C). The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening and grain-boundary strengthening effects. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is controlled mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behavior under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.

  15. Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels.

    PubMed

    Morana, A; Girard, S; Marin, E; Marcandella, C; Paillet, P; Périsse, J; Macé, J-R; Boukenter, A; Cannas, M; Ouerdane, Y

    2014-09-15

    We report a method for fabricating fiber Bragg gratings (FBG) resistant to very severe environments mixing high radiation doses (up to 3 MGy) and high temperatures (up to 230°C). Such FBGs have been written in two types of radiation resistant optical fibers (pure-silica and fluorine-doped cores) by exposures to a 800 nm femtosecond IR laser at power exceeding 500 mW and then subjected to a thermal annealing treatment of 15 min at 750°C. Under radiation, our study reveals that the radiation induced Bragg wavelength shift (BWS) at a 3 MGy dose is strongly reduced compared to responses of FBGs written with nonoptimized conditions. The BWS remains lower than 10 pm for temperatures of irradiation ranging from 25°C to 230°C without noticeable decrease of the FBG peak amplitude. For an applicative point of view, this radiation induced BWS corresponds to an additional error on the temperature measurements lower than 1.5°C, opening the way to the development of radiation-tolerant multi-point temperature sensors for nuclear industry. PMID:26466259

  16. The Perennial Blooming of MGII and Their Correlation with MGI in the Pearl River Estuary, China

    NASA Astrophysics Data System (ADS)

    Xie, W.

    2015-12-01

    Marine Group (MG) I and MG II Archaea were first reported over two decades ago. While significant progress has been made on MG I, the progress on MG II has been noticeable slower. The common understanding is that while MG I mainly function as chemolithoautotrophs growing on ammonia and live predominantly in deeper water, MG II live heterotrophically and reside mostly in the photic zone. While some MG I lineages that could conduct ammonium oxidation are frequently found in terrestrial environments, MG II are exclusively found in marine environments and thus named Thalassoarchaea. A few studies showed MG IIs were sporadically blooming in coastal waters and may be influenced by the level of eutrophication between seasons, which inhibited the enrichment and cultivation for MGII. In this study, we quantified the abundance of planktonic MGI (represented by archaeal amoA gene) and MGII (16S rRNA gene) using qPCR in the water column of different salinities (A: 0.8‰; B: 18.1‰; C: 23.9‰: D: 31‰) in the Pearl River Estuary over a 12-month period. The results showed that the abundance of MGII in site C (8.5±10.1×107 copies/L) was significantly higher than the other three sites (A: 3.5±8.8×105 copies/L; B: 2.7±4.5×107 copies/L; D: 2.2±4.4×107 copies/L) in all seasons, indicating the perennial blooming of MGII that might be due to the optimal combination of available organic carbon and salinity at this site. We also observed that the correlation between MGI and MGII became better toward the marine water and was significant at site D (R2: A, 0.06; B, 0.1; C, 0.24; D, 0.64), indicating the potential functional relationship between them with increasing salinity. This allowed us to hypothesize that the growth of MGI in the coastal site is more dependent on release of ammonia from organic matter degradation by MGII and other heterotrophic organisms. The Pearl River estuary may be an ideal environment for testing this hypothesis, which may provide insight into the

  17. Thermal Stability of MgyTi1-y Thin Films Investigated by Positron Annihilation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Anastasopol, A.; Eijt, S. W. H.; Schut, H.; Mulder, F. M.; Plazaola, F.; Dam, B.

    Mg-Ti compounds are attractive candidates as hydrogen storage materials for their fast sorption kinetics and high storage capacity. In this context, an investigation of their thermal stability is of great importance. The thermal stability of MgyTi1-y thin films was investigated using positron annihilation spectroscopy. Despite the positive enthalpy of mixing of Mg and Ti, positron Doppler Broadening of Annihilation Radiation (DBAR) depth profiling showed that Mg0.9Ti0.1 films are stable up to 300°C. However, for Mg0.7Ti0.3 films, segregation of Mg and Ti was observed at 300oC by the appearance of a clear Ti signature in the S-W diagrams and in the Doppler broadening depth profiles analyzed using VEPFIT. The thickness of the 250-300 nm thin films remained unchanged during the heating treatments. We further present ab-initio calculations of positron lifetimes of the corresponding metal and metal hydride phases for comparison to our previous positron annihilation lifetime spectroscopy (PALS) study.

  18. Direct band gap nature and optical response of BexMgyZn1-(x+y)Se

    NASA Astrophysics Data System (ADS)

    Naeemullah; Murtaza, G.; Khenata, R.; Bin Omran, S.

    2016-01-01

    For the first time, the electronic and optical properties of the quaternary BexMgyZn1-(x+y)Se alloy have been investigated using first-principles calculations within the framework of density functional theory (DFT). Variations in the direct band gap with the change in x and y compositions show agreement with the experimental measurements. Evaluation of the dielectric function and refractive index reveals the optical activity in the visible and ultraviolet energy regions.

  19. Thermoluminescence (TL) Analysis and Fading Studies of Naturally Occurring Salt Irradiated by 500 mGy Gamma Rays

    SciTech Connect

    Tiwari, Ramesh Chandra; Pau, Kham Suan

    2011-10-20

    The aim of the present study was to investigate the potential of the naturally occurring salt for the dosimetry purposes, using TL. The fine powder samples (20 mg) were irradiated by {gamma}- rays from 500 mGy to 2500 mGy by using Theratron-780C Cobalt-60 source, however, this paper discusses about 500 mGy only. The TL glow curve peak parameters were studied by using Chen's peak shape equation. TL glow curves were compared with fitted curves using glow curve deconvolution (GCD) method by using Kitis expression. The kinetic parameter values (E, b and s) so calculated, are in good agreement with those available in literature. The calculated energy values were also verified by using various heating rate (VHR) method. {chi}{sup 2} test and figure of merit (FOM) calculation was done to accept the goodness of fit between the curves. Fading studies of the sample showed a good fitting between the curves. The analysis suggests that natural salt should be considered for dosimetry purposes.

  20. Prediction of Pressure-Induced Structural Transition and Mechanical Properties of MgY from First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Pu, Chun-Ying; Xun, Xian-Chao; Song, Hai-Zhen; Zhang, Fei-Wu; Lu, Zhi-Wen; Zhou, Da-Wei

    2016-01-01

    Using the particle swarm optimization algorithm on crystal structure prediction, we first predict that MgY alloy undergoes a first-order phase transition from CsCl phase to P4/NMM phase at about 55 GPa with a small volume collapse of 2.63%. The dynamical stability of P4/NMM phase at 55 GPa is evaluated by the phonon spectrum calculation and the electronic structure is discussed. The elastic constants are calculated, after which the bulk moduli, shear moduli, Young's modui, and Debye temperature are derived. The brittleness/ductile behavior, and anisotropy of two phases under pressure are discussed in details. Our results show that external pressure can change the brittle behavior to ductile at 10 GPa for CsCl phase and improve the ductility of MgY alloy. As pressure increases, the elastic anisotropy in shear of CsCl phase decreases, while that of P4/NMM phase remains nearly constant. The elastic anisotropic constructions of the directional dependences of reciprocals of bulk modulus and Young's modulus are also calculated and discussed. Supported by the Henan Joint Funds of the National Natural Science Foundation of China under Grant Nos. U1304612, U1404608, the National Natural Science Foundation of China under Grant Nos. 51501093, 51374132, and the Special Fund of the Theoretical Physics of China under Grant No. 11247222, Postdoctoral Science Foundation of China under Grant No. 2015M581767, and Young Core Instructor Foundation of Henan Province under Grant No. 2015GGJS-122

  1. Analysis of hematopoiesis in mice irradiated with 500 mGy of X rays at different stages of development

    SciTech Connect

    Grande, T.; Bueren, J.A.

    1995-09-01

    We have investigated whether a relatively low dose of 500 mGy of X rays given as a single acute irradiation at different stages of pre-and postnatal development induces significant changes in the content of femoral hematopoietic progenitores during a 1-year period after irradiation. Data obtained show that, in the case of 4-day-old embryos as well as in 2-day, 8-day and 12-week-old mice, this dose is below the threshold capable of inducing a long-term impairment of hematopoiesis in the mouse. Nevertheless, in mice irradiated at the 13th or the 17th day postconception, a hematopoietic dysfunction consisting of a significant reduction in the proportion of femoral granulocyte-macrophage colony-forming units (CFU-GM) was manifested 1 year after irradiation. Our study confirms that, for most stages of development in the mouse, a single acute X irradiation of 500 mGy is below the threshold dose capable of inducing deterministic effects in the mouse hematopoietic system, although it reveals the induction of a significant impairment in the CFU-GM population when irradiation is given at the late stages of embryonic development. 24 refs., 4 figs.

  2. Diagnostics of Local Magnetic Fields in Solar Flares Using FeI 5383 and MgI 5528 Lines

    NASA Astrophysics Data System (ADS)

    Lozitsky, V. G.; Lozitsky, O. V.

    Main purpose of the present work is to estimate upper limit of the local magnetic field strength in solar flares using spectral lines FeI 5383 and MgI 5528. These lines like FeI 5233 have low Lande factors (1.12 and 1.00, respectively) and relatively large spectral width (0.2-0.3 Å). On this account, even in a case of very strong fields (3-4 kG) they must show the simple picture of the Zeeman splitting, with parallel to each other the bisectors of profiles I+V and I - V. In actual fact, another picture was found for nine flares: bisectors of these lines have maximums of splitting on certain distances from line center, what must not be in the homogeneous magnetic field. In particular, both lines have peak of bisector splitting on distance 150-170 mÅ from line center. If we assume the Zeeman nature of named peculiarities then necessary fields are 11.2 kG for FeI 5383 and 10.5-11.2 kG for MgI 5528. Likely, this agreement of field values is a new argument to reality of such very strong magnetic fields in flares.

  3. Photoluminescence properties of MgY4Si3O13:Gd3+, Tb3+ under vacuum ultraviolet excitation

    NASA Astrophysics Data System (ADS)

    Zhao, Wenyu; An, Shengli; Fan, Bin; Li, Songbo

    2013-07-01

    Gd3+ and Tb3+ co-doped MgY4Si3O13 green phosphors were prepared by a solid-state reaction. The photoluminescence properties in vacuum ultraviolet-visible (VUV-vis) range and decay properties were investigated in details. The f-d transition of Gd3+ ions and spin-allowed f-d transition of Tb3+ ions locate at about 134 nm and 239 nm, respectively. Two charge transfer bands of O2- → Gd3+ and O2- → Tb3+ overlap at about 155 nm. Some f-f transition of Tb3+ and Gd3+ ions are confirmed in VUV-vis range. Upon excitation at 172 nm, the optimal composition of MgY3.3Si3O13:0.5Gd3+, 0.2Tb3+ phosphor exhibits the characteristic transitions of Gd3+ and Tb3+ with chromaticity coordinate of (0.2849, 0.5843). The phosphor has a shorter decay time (2.13 ms) than that of Zn2SiO4:Mn2+ (4.56 ms). The results suggest that this green phosphor is a potential candidate for mercury-free luminescence lamps and plasma display panels (PDPs) application.

  4. Microstructures, aging behaviour and mechanical properties in hydrogen and chloride media of backward extruded Mg-Y based biomaterials.

    PubMed

    Peng, Qiuming; Ma, Ning; Fang, Daqing; Li, Hui; Liu, Riping; Tian, Yongjun

    2013-01-01

    Microstructures, aging behaviour from room temperature to 300 °C and mechanical properties in different media of backward extruded (BE) Mg-Y based biomaterial have been investigated. The results reveal that BE-Mg-Y based alloy is mainly composed of polygon-shaped grains and fine precipitates. The results of aging response show that BE-Mg-Y based alloy exhibits remarkable age hardening behaviour when the aging temperature is 200 °C and higher. The high mechanical properties of aged BE-Mg-Y based alloy are mostly associated with fine microstructure, solid solution strengthening and the existence of homogeneous precipitates. The hydrogen embrittlement dependence on the aging time is confirmed in BE-Mg-Y based alloy. Additionally, the strength and elongation of BE-Mg-Y based alloy are significantly influenced by the ion concentration in media. These results offer some implications for understanding the reduced strength of Mg based implants in body environment. It is demonstrated that the temporary high mechanical strength in air of BE-Mg-Y based biomaterials is insufficient to evaluate the in vivo mechanical integrity. PMID:23127631

  5. From nGy to MGy - New dosimetry with LiF:Mg,Cu,P thermoluminescence detectors

    SciTech Connect

    Obryk, Barbara

    2013-05-06

    One of the well known advantages of thermoluminescence (TL) detectors made of lithium fluoride doped with magnesium, copper and phosphorus (LiF:Mg,Cu,P) is their very high sensitivity to ionizing radiation. LiF:Mg,Cu,P detectors enable measurements of radiation doses from tens of nanograys up to a few kilograys, when the total saturation of the signal of the so-called main dosimetric peak occurs. Only recently, unprecedented high-temperature emission of LiF detectors heated to temperatures up to 600 Degree-Sign C, was observed after exposures to radiation doses ranging from 1 kGy to 1 MGy. For quantification of the glow-curve shape changes of LiF:Mg,Cu,P detectors in this range of doses and determination of the absorbed dose, the Ultra-High Temperature Ratio coefficient (UHTR) was defined. This newly established dosimetric method was tested in a range of radiation qualities, such as gamma radiation, electron and proton beams, thermal neutron fields and high-energy mixed fields around the SPS and PS accelerators at CERN. The new method for ultra-high dose range monitoring with a single LiF:Mg,Cu,P detector, which is capable of covering at least twelve orders of magnitude of doses, can be used for dosimetry at high energy accelerators, thermonuclear fusion technology facilities and has great potential for accident dosimetry in particular. A number of dosimetric sets with LiF:Mg,Cu,P detectors are currently installed around the LHC at CERN.

  6. A single-phased tunable emission phosphor MgY2Si3O10: Eu(3+), Bi(3+) with efficient energy transfer for white LEDs.

    PubMed

    Zhou, Hongpeng; Jin, Ye; Jiang, Mingsong; Wang, Qingping; Jiang, Xingxing

    2015-01-21

    A novel single-phased tunable emitting phosphor MgY2Si3O10: Bi(3+), Eu(3+) has been synthesized by a conventional high temperature solid-state method. X-ray diffraction (XRD), photoluminescence emission and excitation spectra were utilized to characterize the as-synthesized samples. Under UV-light pumping, MgY2Si3O10: Bi(3+) showed characteristic blue emission corresponding to the (3)P1→(1)S0 transition of Bi(3+) ions, and MgY2Si3O10: Eu(3+) showed characteristic red emission corresponding to the (5)D0→(7)FJ (J = 1, 2, 3, 4) transition of Eu(3+) ions. Spectra indicate that Bi(3+) ions occupy two nonequivalent sites in the MgY2Si3O10 matrix, namely, Bi(3+)(i) and Bi(3+)(ii). The two sites (Bi(3+)(i) and Bi(3+)(ii)) exhibit broad emission peaks at 411 nm and 490 nm, respectively. Efficient energy transfer between these two Bi(3+) sites has been proven using the spectra. The spectral overlap between the emission spectrum of Bi(3+) and the excitation spectrum of Eu(3+) allows for resonance-type energy transfer to occur from Bi(3+) to Eu(3+). The efficient energy transfer from Bi(3+) to Eu(3+)via a dipole-quadrupole interaction mechanism is significantly demonstrated by comparing experimental data with theoretical calculations. According to the concentration quenching-method, the critical distance of energy transfer from Bi(3+) to Eu(3+) is calculated to be 13.2 Å. As it is a new phosphor, CIE coordinates and CCT temperature, in addition to efficient energy transfer have been also investigated in detail. White light emission for MgY2Si3O10: n Bi(3+), m Eu(3+) can be realized through controlling the concentrations of Bi(3+) and Eu(3+). All of the results indicate that MgY2Si3O10: n Bi(3+), m Eu(3+) is a potential phosphor for white light UV-LEDs. PMID:25409734

  7. Aging and thermal stability of Mg/SiC and Mg/Y2O3 reflection multilayers in the 25-35 nm region

    SciTech Connect

    Ejima, Takeo; Yamazaki, Atsushi; Banse, Takanori; Saito, Katsuhiko; Kondo, Yuji; Ichimaru, Satoshi; Takenaka, Hisataka

    2005-09-10

    Reflection measurements in the 25-35 nm region were made for Mg/SiC and Mg/Y2O3 multilayers kept in a low-humidity atmosphere for 4 or 5 years. Aged Mg/SiC multilayers keep their reflectances, and the reflectance value at 31.2 nm is 0.44 at 10 deg. of the normal angle of incidence. Aged Mg/Y2O3 multilayers change reflectance as top layer materials, and the best value at 30.1 nm is 0.40 at 10 deg. . Reflection measurements are also made for Mg-based multilayers that are annealed from room temperature to 400 deg. C at 50 deg. C intervals. Both multilayers keep their reflectance at annealing temperatures of 200 deg. C. These results suggest that both Mg-based multilayers can be applied to practical optics.

  8. Efficiency enhancement in dye sensitized solar cells using gel polymer electrolytes based on a tetrahexylammonium iodide and MgI2 binary iodide system.

    PubMed

    Bandara, T M W J; Dissanayake, M A K L; Jayasundara, W J M J S R; Albinsson, I; Mellander, B-E

    2012-06-28

    Quasi-solid-state dye-sensitized solar cells have drawn the attention of scientists and technologists as a potential candidate to supplement future energy needs. The conduction of iodide ions in quasi-solid-state polymer electrolytes and the performance of dye sensitized solar cells containing such electrolytes can be enhanced by incorporating iodides having appropriate cations. Gel-type electrolytes, based on PAN host polymers and mixture of salts tetrahexylammonium iodide (Hex4N(+)I(-)) and MgI2, were prepared by incorporating ethylene carbonate and propylene carbonate as plasticizers. The salt composition in the binary mixture was varied in order to optimize the performance of solar cells. The electrolyte containing 120% Hex4N(+)I(-) with respect to weight of PAN and without MgI2 showed the highest conductivity out of the compositions studied, 2.5 × 10(-3) S cm(-1) at 25 °C, and a glass transition at -102.4 °C. However, the electrolyte containing 100% Hex4N(+)I(-) and 20% MgI2 showed the best solar cell performance highlighting the influence of the cation on the performance of the cell. The predominantly ionic behaviour of the electrolytes was established from the dc polarization data and all the electrolytes exhibit iodide ion transport. Seven different solar cells were fabricated employing different electrolyte compositions. The best cell using the electrolyte with 100% Hex4N(+)I(-) and 20% MgI2 with respect to PAN weight showed 3.5% energy conversion efficiency and 8.6 mA cm(-2) short circuit current density. PMID:22618351

  9. Design and assessment of a 6 ps-resolution time-to-digital converter with 5 MGy gamma-dose tolerance for nuclear instrumentation

    SciTech Connect

    Cao, Y.; Leroux, P.; De Cock, W.; Steyaert, M.

    2011-07-01

    Time-to-Digital Converters (TDCs) are key building blocks in time-based mixed-signal systems, used for the digitization of analog signals in time domain. A short survey on state-of-the-art TDCs is given. In order to realize a TDC with picosecond time resolution as well as multi MGy gamma-dose radiation tolerance, a novel multi-stage noise-shaping (MASH) delta-sigma ({Delta}{Sigma}) TDC structure is proposed. The converter, implemented in 0.13 {mu}m, achieves a time resolution of 5.6 ps and an ENOB of 11 bits, when the over sampling ratio (OSR) is 250. The TDC core consumes only 1.7 mW, and occupies an area of 0.11 mm{sup 2}. Owing to the usage of circuit level radiation hardened-by-design techniques, such as passive RC oscillators and constant-g{sub m} biasing, the TDC exhibits enhanced radiation tolerance. At a low dose rate of 1.2 kGy/h, the frequency of the counting clock in the TDC remains constant up to at least 160 kGy. Even after a total dose of 3.4 MGy at a high dose rate of 30 kGy/h, the TDC still achieves a time resolution of 10.5 ps with an OSR of 250. (authors)

  10. Effect of Gamma Irradiation on Cement Composites Observed with XRD and SEM Methods in the Range of Radiation Dose 0-1409 MGy

    NASA Astrophysics Data System (ADS)

    Łowińska-Kluge, A.; Piszora, P.

    2008-08-01

    The effect of gamma radiation in the range of 0-1409 MGy on the structure of a new mineral additive to cement based composites was investigated in the perspective of employing them as radioactive waste protection material. According to the authors knowledge, it is the first paper dealing with observations of the cement matrix, both pure and modified, treated with so giant radiation dose. The absorption of gamma radiation modifies the morphology of the additive grains, causes decomposition of cement hydrates and clinker relicts in cement paste containing the additive at twice higher radiation dose than that inducing the decomposition of the reference pure cement paste and the cement paste containing pozzolane additives.

  11. Effect of a 100-MGy (10/sup 10/ RADS) gamma-ray dose at 5 K on the strength of polyimide insulators

    SciTech Connect

    Coltman, R.R. Jr.; Klabunde, C.E.; Long, C.J.

    1981-01-01

    This study seeks to determine the strength of polyimide materials as a function gamma-ray irradiation dose at 5 K. It compares new results with those from previous studies of epoxies made under the same conditions. The most recent efforts in this program have examined the strength and other properties of pure and glass-fiber-filled polyimide materials irradiated to a dose of 100 MGy (10/sup 10/ rads). At this dose the losses in strength measured at 78 K were less than 40%, and at 300 K slight increases were observed. Overall, the glass-fiber-filled polyimide materials are 5 to 10 times more radiation resistant than glass-fiber-filled epoxy materials.

  12. Effects of different matrixes on the dosimetric response of α-terthiophene films from the kGy to MGy range

    NASA Astrophysics Data System (ADS)

    Russo, M.; D'Angelantonio, M.; Takács, E.; Lavalle, M.; Fuochi, P. G.; Emmi, S. S.

    2002-03-01

    Films of polymethylmethacrylate (PMMA) and polystyrene (PS) containing α-terthiophene (3T) undergo a radiochromic effect when exposed to electrons and gamma rays. The films turn either red-green or red, due to the formation of oligomeric radical cations. In both matrixes, absorbance at 465 nm grows linearly with dose when α-terthiophene concentration reaches 12%. Explored range goes up to ˜2×10 6 Gy, with dose rates spanning over three orders of magnitude. Concerning their application as dosimeters, a higher sensitivity characterises the 3T-PMMA moiety, suggesting its suitability from the kGy range up to 1 MGy. Above this value films become fragile. 3T-PS films are less sensitive, but more radiation resistant. Therefore they better suit the medium-to-high dose dosimetry range. Dose rate influences the response sensitivity in a complex way, however above 80 and up to 3.6×10 4 Gy/min an approximate linearity exists between log(dose rate) and sensitivity, as in the analogous cellulose triacetate system.

  13. Effect of Mg doping on the local structure of LiMgyCo1-yO2 cathode material investigated by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, J. H.; Pan, C. J.; Nithya, C.; Thirunakaran, R.; Gopukumar, S.; Chen, C. H.; Lee, J. F.; Chen, J. M.; Sivashanmugam, A.; Hwang, B. J.

    2014-04-01

    A higher capacity and better cyclability are apparent when magnesium is introduced into the structure of LiCoO2 (y = 0.15). XRD analysis of LiMgyCo1-yO2 (y = 0, 0.1, 0.15), synthesized at 800 °C using a microwave assisted method, shows that the material is in the R-3m space group and to have a slightly expanded unit cell that increases with greater magnesium doping. Structural analysis by X-ray absorption spectroscopy (XAS) at the Co K-edge, L-edge and O K-edge shows that the magnesium is located in the transition metal layer rather than in the lithium layer and the charge balance results from the formation of oxygen vacancies rather than Co4+, while cobalt remains in the 3+ oxidation state. Interestingly, oxygen is found to participate in the charge compensation. Both magnesium, in the transition metal layer, and the Co-defect structure are attributed to the contribution towards structural stabilization of LiCoO2, thereby resulting in its enhanced electrochemical performance.

  14. Global radiation damage at 300 and 260 K with dose rates approaching 1 MGy s[superscript -1

    SciTech Connect

    Warkentin, Matthew; Badeau, Ryan; Hopkins, Jesse B.; Mulichak, Anne M.; Keefe, Lisa J.; Thorne, Robert E.

    2012-02-27

    Global radiation damage to 19 thaumatin crystals has been measured using dose rates from 3 to 680 kGy s{sup -1}. At room temperature damage per unit dose appears to be roughly independent of dose rate, suggesting that the timescales for important damage processes are less than {approx}1 s. However, at T = 260 K approximately half of the global damage manifested at dose rates of {approx}10 kGy s{sup -1} can be outrun by collecting data at 680 kGy s{sup -1}. Appreciable sample-to-sample variability in global radiation sensitivity at fixed dose rate is observed. This variability cannot be accounted for by errors in dose calculation, crystal slippage or the size of the data sets in the assay.

  15. Global radiation damage at 300 and 260 K with dose rates approaching 1 MGy s{sup −1}

    SciTech Connect

    Warkentin, Matthew; Badeau, Ryan; Hopkins, Jesse B.; Mulichak, Anne M.; Keefe, Lisa J.; Thorne, Robert E.

    2012-02-01

    Approximately half of global radiation damage to thaumatin crystals can be outrun at 260 K if data are collected in less than 1 s. Global radiation damage to 19 thaumatin crystals has been measured using dose rates from 3 to 680 kGy s{sup −1}. At room temperature damage per unit dose appears to be roughly independent of dose rate, suggesting that the timescales for important damage processes are less than ∼1 s. However, at T = 260 K approximately half of the global damage manifested at dose rates of ∼10 kGy s{sup −1} can be outrun by collecting data at 680 kGy s{sup −1}. Appreciable sample-to-sample variability in global radiation sensitivity at fixed dose rate is observed. This variability cannot be accounted for by errors in dose calculation, crystal slippage or the size of the data sets in the assay.

  16. MnSOD downregulation induced by extremely low 0.1 mGy single and fractionated X-rays and microgravity treatment in human neuroblastoma cell line, NB-1.

    PubMed

    Indo, Hiroko P; Tomiyoshi, Tsukasa; Suenaga, Shigeaki; Tomita, Kazuo; Suzuki, Hiromi; Masuda, Daisuke; Terada, Masahiro; Ishioka, Noriaki; Gusev, Oleg; Cornette, Richard; Okuda, Takashi; Mukai, Chiaki; Majima, Hideyuki J

    2015-09-01

    A human neuroblastoma cell line, NB-1, was treated with 24 h of microgravity simulation by clinostat, or irradiated with extremely small X-ray doses of 0.1 or 1.0 mGy using single and 10 times fractionation regimes with 1 and 2 h time-intervals. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) examination was performed for apoptosis related factors (BAX, CYTC, APAF1, VDAC1-3, CASP3, CASP8, CASP9 P53, AIF, ANT1 and 2, BCL2, MnSOD, autophagy related BECN and necrosis related CYP-40. The qRT-PCR results revealed that microgravity did not result in significant changes except for a upregulation of proapoptotic VDAC2, and downregulations of proapoptotic CASP9 and antiapoptotic MnSOD. After 0.1 mGy fractionation irradiation, there was increased expression of proapoptotic APAF1 and downregulation of proapoptotic CYTC, VDAC2, VDAC3, CASP8, AIF, ANT1, and ANT2, as well as an increase in expression of antiapoptotic BCL2. There was also a decrease in MnSOD expression with 0.1 mGy fractionation irradiation. These results suggest that microgravity and low-dose radiation may decrease apoptosis but may potentially increase oxidative stress. PMID:26388666

  17. MnSOD downregulation induced by extremely low 0.1 mGy single and fractionated X-rays and microgravity treatment in human neuroblastoma cell line, NB-1

    PubMed Central

    Indo, Hiroko P.; Tomiyoshi, Tsukasa; Suenaga, Shigeaki; Tomita, Kazuo; Suzuki, Hiromi; Masuda, Daisuke; Terada, Masahiro; Ishioka, Noriaki; Gusev, Oleg; Cornette, Richard; Okuda, Takashi; Mukai, Chiaki; Majima, Hideyuki J.

    2015-01-01

    A human neuroblastoma cell line, NB-1, was treated with 24 h of microgravity simulation by clinostat, or irradiated with extremely small X-ray doses of 0.1 or 1.0 mGy using single and 10 times fractionation regimes with 1 and 2 h time-intervals. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) examination was performed for apoptosis related factors (BAX, CYTC, APAF1, VDAC1–3, CASP3, CASP8, CASP9 P53, AIF, ANT1 and 2, BCL2, MnSOD, autophagy related BECN and necrosis related CYP-40. The qRT-PCR results revealed that microgravity did not result in significant changes except for a upregulation of proapoptotic VDAC2, and downregulations of proapoptotic CASP9 and antiapoptotic MnSOD. After 0.1 mGy fractionation irradiation, there was increased expression of proapoptotic APAF1 and downregulation of proapoptotic CYTC, VDAC2, VDAC3, CASP8, AIF, ANT1, and ANT2, as well as an increase in expression of antiapoptotic BCL2. There was also a decrease in MnSOD expression with 0.1 mGy fractionation irradiation. These results suggest that microgravity and low-dose radiation may decrease apoptosis but may potentially increase oxidative stress. PMID:26388666

  18. First results on disruption mitigation by massive gas injection in Korea Superconducting Tokamak Advanced Research

    SciTech Connect

    Yu Yaowei; Kim, Young-Ok; Kim, Hak-Kun; Kim, Hong-Tack; Kim, Woong-Chae; Kim, Kwang-Pyo; Son, Soo-Hyun; Bang, Eun-Nam; Hong, Suk-Ho; Yoon, Si-Woo; Zhuang Huidong; Chen Zhongyong

    2012-12-15

    Massive gas injection (MGI) system was developed on Korea Superconducting Tokamak Advanced Research (KSTAR) in 2011 campaign for disruption studies. The MGI valve has a volume of 80 ml and maximum injection pressure of 50 bar, the diameter of valve orifice to vacuum vessel is 18.4 mm, the distance between MGI valve and plasma edge is {approx}3.4 m. The MGI power supply employs a large capacitor of 1 mF with the maximum voltage of 3 kV, the valve can be opened in less than 0.1 ms, and the amount of MGI can be controlled by the imposed voltage. During KSTAR 2011 campaign, MGI disruptions are carried out by triggering MGI during the flat top of circular and limiter discharges with plasma current 400 kA and magnetic field 2-3.5 T, deuterium injection pressure 39.7 bar, and imposed voltage 1.1-1.4 kV. The results show that MGI could mitigate the heat load and prevent runaway electrons with proper MGI amount, and MGI penetration is deeper under higher amount of MGI or lower magnetic field. However, plasma start-up is difficult after some of D{sub 2} MGI disruptions due to the high deuterium retention and consequently strong outgassing of deuterium in next shot, special effort should be made to get successful plasma start-up after deuterium MGI under the graphite first wall.

  19. Radiation dose in radiography, CT, and arthrography of the temporomandibular joint

    SciTech Connect

    Christiansen, E.L.; Moore, R.J.; Thompson, J.R.; Hasso, A.N.; Hinshaw, D.B. Jr.

    1987-01-01

    Thermoluminescent dosimetry studies were performed on a Rando Humanoid head phantom to compare radiation dosages used in temporomandibular joint examinations. Studies included transaxial and direct sagittal high-resolution CT, reduced milliamperage dynamic CT, tomoarthrography, pluridirectional and linear tomography, pantomography, transcranial plain films, and fluoroscopy. Radiation doses were determined for the brain, lens, pituitary gland, condylar marrow, and thyroid gland. Condylar marrow received doses of 64 and 52 mGy, respectively, for the GE 9800 and 8800 high-resolution scans; 21 and 17 mGy, respectively, for the dynamically sequenced scans; and 26 mGy for the GE 9800 direct sagittal sections. Tomoarthrography yielded 31 mGy and fluoroscopy 12 mGy. Other lower doses showed 5 mGy for polytomography, 3 mGy for ipsilateral joint linear tomography, 1.9 mGy for the GE 9800 slow ScoutView, 1.8 mGy for xeroradiography, 0.9 mGy for contralateral joint linear tomography, 0.3-0.4 mGy for transcranial plain films and pantomography, and 0.2 mGy for the GE 8800 ScoutView. The estimated error in this study was calculated to be +/- 15%. On a relative scale, the radiation doses from high-resolution CT and tomoarthrography are high, dynamic CT yields a medium dose, and all other tomographic and plain-film techniques yield low doses.

  20. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 MgY for the parotid gland, 0.15 MgY for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field.

  1. Entrance surface dose of the common radiological investigations in Abuth, Zaria.

    PubMed

    Nwokorie, Emmanuel; Akpa, T C; Mallam, O P; Akpan, Eyo; Ibinaye, P O; Obiako, O R; Nzotta, C; Ugwu, A C

    2011-09-01

    The entrance surface Dose (ESD) was determined among patients who presented for routine radiological examinations using thermoluminescent dosimeter (TLD) chips placed on averagely built adult [(30 cm) chest width, 60-90kg weight and 20-40years)] by multiplying the incident dose/entrances dose by the back scattered factor [BSF] gotten from an experiment. The values obtained from ESD measurements are as follows 8.03 mGy for Abdomen, 0.13 mGy for chest AP, 0.69 mGy for chest lateral, 0.5 mGy for cervical spine; AP: 0.38 mGy for cervical spine lateral; 4.75 mGy for hip AP: 12.83 mGy for hip lateral: 5.74mGy for lumbar spine, AP lumbar spine lateral is 15.15 mGy. 1.38m Gy is for pelvis AP. 2.93mGy for skull AP/PA 1.2mGy for skull lateral, 5.46mGy for thorax AP, while the lateral is 14.90m Gy. The average dose value is 9.28mGy Range 0.13-14.90mGy (Percentage standard error; +/- 1.45). From this studies Radiation doses delivered for routine investigations are generally lower than IAEA reference doses. Using these values for optimization of radiation protection practices for patient should be ensured since it does not rule out options for stochastic radiation. PMID:23120957

  2. Niche Partitioning of Marine Group I Crenarchaeota in the Euphotic and Upper Mesopelagic Zones of the East China Sea▿†

    PubMed Central

    Hu, Anyi; Jiao, Nianzhi; Zhang, Rui; Yang, Zao

    2011-01-01

    Marine group I Crenarchaeota (MGI) represents a ubiquitous and numerically predominant microbial population in marine environments. An understanding of the spatial dynamics of MGI and its controlling mechanisms is essential for an understanding of the role of MGI in energy and element cycling in the ocean. In the present study, we investigated the diversity and abundance of MGI in the East China Sea (ECS) by analysis of crenarchaeal 16S rRNA gene, the ammonia monooxygenase gene amoA, and the biotin carboxylase gene accA. Quantitative PCR analyses revealed that these genes were higher in abundance in the mesopelagic than in the euphotic zone. In addition, the crenarchaeal amoA gene was positively correlated with the copy number of the MGI 16S rRNA gene, suggesting that most of the MGI in the ECS are nitrifiers. Furthermore, the ratios of crenarchaeal accA to amoA or to MGI 16S rRNA genes increased from the euphotic to the mesopelagic zone, suggesting that the role of MGI in carbon cycling may change from the epipelagic to the mesopelagic zones. Denaturing gradient gel electrophoretic profiling of the 16S rRNA genes revealed depth partitioning in MGI community structures. Clone libraries of the crenarchaeal amoA and accA genes showed both “shallow” and “deep” groups, and their relative abundances varied in the water column. Ecotype simulation analysis revealed that MGI in the upper ocean could diverge into special ecotypes associated with depth to adapt to the light gradient across the water column. Overall, our results showed niche partitioning of the MGI population and suggested a shift in their ecological functions between the euphotic and mesopelagic zones of the ECS. PMID:21873485

  3. Long-Term Musical Group Interaction Has a Positive Influence on Empathy in Children

    ERIC Educational Resources Information Center

    Rabinowitch, Tal-Chen; Cross, Ian; Burnard, Pamela

    2013-01-01

    Musical group interaction (MGI) is a complex social setting requiring certain cognitive skills that may also elicit shared psychological states. We argue that many MGI-specific features may also be important for emotional empathy, the ability to experience another person's emotional state. We thus hypothesized that long-term repeated…

  4. Expecting the Best from Students in Urban Middle Schools. A Report on the Edna McConnell Clark Foundation's Middle Grades Initiative.

    ERIC Educational Resources Information Center

    Clark, Terry A.; Canner, Jane

    The Edna McConnell Clark Foundation developed and sponsored the Middle Grades Initiative (MGI), which began in 1989, in five urban school systems: (1) Baltimore (Maryland); (2) Louisville (Kentucky); (3) Milwaukee (Wisconsin); (4) Oakland (California); and (5) San Diego (California). The purpose of MGI was to change the ways schools educate young,…

  5. Designing of the massive gas injection valve for the joint Texas experimental tokamak.

    PubMed

    Luo, Y H; Chen, Z Y; Tang, Y; Wang, S Y; Ba, W G; Wei, Y N; Ma, T K; Huang, D W; Tong, R H; Yan, W; Geng, P; Shao, J; Zhuang, G

    2014-08-01

    In order to mitigate the negative effects of the plasma disruption a massive gas injection (MGI) valve is designed for the joint Texas experimental tokamak. The MGI valve is based on the eddy-current repulsion mechanism. It has a fueling volume of 30 ml. The piston of the MGI valve is made by non-ferromagnetic material, so it can be installed close to the vacuum vessel which has a strong toroidal magnetic field. A diode is use to prevent current oscillation in the discharge circuit. The drive coil of the valve is installed outside the gas chamber. The opening characteristics and the gas flow of the MGI valve have been tested by a 60 l vacuum chamber. Owing to the large electromagnetic force the reaction time of the valve is shorter than 0.3 ms. Duration for the opening of the MGI valve is in the order of 10 ms. PMID:25173266

  6. Electron spin resonance analysis of tooth enamel does not indicate exposures to large radiation doses in a large proportion of distally-exposed A-bomb survivors.

    PubMed

    Hirai, Yuko; Kodama, Yoshiaki; Cullings, Harry M; Miyazawa, Chuzo; Nakamura, Nori

    2011-01-01

    The atomic bombs in Hiroshima and Nagasaki led to two different types of radiation exposure; one was direct and brief and the other was indirect and persistent. The latter (so-called exposure to residual radiation) resulted from the presence of neutron activation products in the soil, or from fission products present in the fallout. Compared with the doses from direct exposures, estimations of individual doses from residual radiation have been much more complicated, and estimates vary widely among researchers. The present report bases its conclusions on radiation doses recorded in tooth enamel from survivors in Hiroshima. Those survivors were present at distances of about 3 km or greater from the hypocenter at the time of the explosion, and have DS02 estimated doses (direct exposure doses) of less than 5 mGy (and are regarded as control subjects). Individual doses were estimated by measuring CO(2)(-) radicals in tooth enamel with the electron spin resonance (ESR; or electron paramagnetic resonance, EPR) method. The results from 56 molars donated by 49 survivors provided estimated doses which vary from -200 mGy to 500 mGy, and the median dose was 17 mGy (25% and 75% quartiles are -54 mGy and 137 mGy, respectively) for the buccal parts and 13 mGy (25% and 75% quartiles: -49 mGy and 87 mGy, respectively) for the lingual parts of the molars. Three molars had ESR-estimated doses of 300 to 400 mGy for both the buccal and lingual parts, which indicates possible exposures to excess doses of penetrating radiation, although the origin of such radiation remains to be determined. The results did not support claims that a large fraction of distally-exposed survivors received large doses (e.g. 1 Gy) of external penetrating radiation resulting from residual radiation. PMID:21768749

  7. Clinical factors increasing radiation doses to patients undergoing long-lasting procedures: Abdominal stent-graft implantation

    PubMed Central

    Majewska, Natalia; Stanisic, Michal G.; Blaszak, Magdalena Aleksandra; Juszkat, Robert; Frankiewicz, Maciej; Krasinski, Zbigniew; Makalowski, Marcin; Majewski, Waclaw

    2011-01-01

    Summary Background An important negative factor of EVAR is the radiation acquired during long-lasting procedures. The aim of the study was to document the radiation doses of EVAR and to discuss potential reasons for prolongation of radiological procedures. Material/Methods Dose-area product (DAP) (Gy cm2) and air kerma (AK) (Gy) obtained during EVAR from 92 patients were analyzed retrospectively in regards to body mass index (BMI), angulations of aneurysm neck, length of aneurysm neck and occurrence of tortuosity of iliac arteries. Results Total AK for fluoroscopy differed significantly between normal BMI (373 mGy) and BMI 25–29.9 (1125 mGy) or BMI >30 (1085 mGy). Iliac artery tortuosities >45° and short aneurysm necks caused higher doses of total AK (1097 mGy and 1228 mGy, respectively) than iliac artery tortuosities <45° and long aneurysm necks (605 mGy and 720 mGy, respectively). Conclusions The main factors contributing to a high radiation dose being acquired by patients during EVAR are: BMI >25, tortuosity of iliac arteries >45° and short aneurysm necks. PMID:22037751

  8. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

  9. Occupational and patient exposure in coronary angiography procedures

    NASA Astrophysics Data System (ADS)

    Sulieman, A.; Alzimami, K.; Gafar, R.; Babikir, E.; Alsafi, K.; Suliman, I. I.

    2014-11-01

    Cardiac catheterization is the gold standard in the diagnosis and management of coronary artery diseases. The objectives of this study were to evaluate the radiation dose of patients and staff during cardiology procedures. Staff was monitored using thermoluminescence dosimeter (TLD) chips for 86 procedures. The mean patient dose was 2813.6 μGy m2 and the mean fluoroscopic time was 4.8 min. The mean radiation doses for cardiologists were 0.9 mGy for the forehead, 0.92 mGy for the thyroid, 1.38 mGy for the chest, 1.28 mGy for the waist and 1.41 mGy for the hand. The mean radiation doses for assistants were 0.72 mGy for the chest, 0.82 mGy for the hand. High patient and staff exposure is due to lack of experience and protective equipment, exacerbated by a high workload. Interventional procedures remain operator dependent; therefore, continuous training is crucial.

  10. Radiation hardness of plastic scintillators for the Tile Calorimeter of the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Jivan, H.; Sideras-Haddad, E.; Erasmus, R.; Liao, S.; Madhuku, M.; Peters, G.; Sekonya, K.; Solvyanov, O.

    2015-10-01

    The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy and light yield analysis whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs and light loss can be attributed to a breakdown in the light transfer between base and fluor dopants. For doses of 8 MGy to 80 MGy, structural damage leads to possible hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss and light yield loss with increasing dose.

  11. Radiation hardness of plastic scintillators for the Tile Calorimeter of the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Jivan, H.; Mellado, B.; Sideras-Haddad, E.; Erasmus, R.; Liao, S.; Madhuku, M.; Peters, G.; Solvyanov, O.

    2015-06-01

    The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs but a breakdown in the light transfer between base and fluor dopants is observed. For doses of 8 MGy to 80 MGy, structural damage leads to hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss as dose is increased.

  12. An assessment of reference exposure in analogic and digital mammographic units

    NASA Astrophysics Data System (ADS)

    Tilly, J. G.; Miguel, C.; Schelin, H. R.; Porto, L. E.; Paschuk, S.; Denyak, V.; Kmiecik, C.

    2014-11-01

    In this study, the incident air kerma (Ki,a), half-value layer (HVL), output and voltage accuracy for 28 mammography services were evaluated. All mammographs had high frequency rectification, a focus-film distance greater than 60 cm, automatic exposure control, a Mo-Mo anode-filter combination, and compression system. Twenty-three evaluations were made of analogic imaging systems and 21 of digital imaging systems, two of which were full field digital mammography units. The Ki,a was measured in the beam radiation with a 6 cm3 ionization chamber, calibrated for a mammography range of energy. A standard American College of Radiology mammographic phantom simulated a skull caudal incidence. The average, minimum, and maximum Ki,a values were 10.13 mGy, 3.92 mGy, and 30.41 mGy, respectively. However, when the analogic and digital systems are analyzed separately in two subsets, the values were 8.13 mGy, 3.92 mGy, and 11.78 mGy for the analogic systems and 12.33 mGy, 5.21 mGy, and 30.41 mGy for the digital systems, respectively. The results show that the Ki,a values found in digital systems were higher than those in analogic systems, highlighting the differences between these acquisition systems. All HVL values, measured in the primary beam at 28 kV were found between 0.33 mm Al and 0.43 mm Al. Although the manufacture time of the equipment was approximately 146 months (~12 years) prior, the variation in output was between 0.071 mGy/mAs and 0.164 mGy/mAs for the entire sample.

  13. Research Update: The materials genome initiative: Data sharing and the impact of collaborative ab initio databases

    NASA Astrophysics Data System (ADS)

    Jain, Anubhav; Persson, Kristin A.; Ceder, Gerbrand

    2016-05-01

    Materials innovations enable new technological capabilities and drive major societal advancements but have historically required long and costly development cycles. The Materials Genome Initiative (MGI) aims to greatly reduce this time and cost. In this paper, we focus on data reuse in the MGI and, in particular, discuss the impact of three different computational databases based on density functional theory methods to the research community. We also discuss and provide recommendations on technical aspects of data reuse, outline remaining fundamental challenges, and present an outlook on the future of MGI's vision of data sharing.

  14. Practical improvements of multi-grid iteration for adaptive mesh refinement method

    NASA Astrophysics Data System (ADS)

    Miyashita, Hisashi; Yamada, Yoshiyuki

    2005-03-01

    Adaptive mesh refinement(AMR) is a powerful tool to efficiently solve multi-scaled problems. However, the vanilla AMR method has a well-known critical demerit, i.e., it cannot be applied to non-local problems. Although multi-grid iteration (MGI) can be regarded as a good remedy for a non-local problem such as the Poisson equation, we observed fundamental difficulties in applying the MGI technique in AMR to realistic problems under complicated mesh layouts because it does not converge or it requires too many iterations even if it does converge. To cope with the problem, when updating the next approximation in the MGI process, we calculate the precise total corrections that are relatively accurate to the current residual by introducing a new iteration for such a total correction. This procedure greatly accelerates the MGI convergence speed especially under complicated mesh layouts.

  15. Investigation of LiF, Mg and Ti (TLD-100) Reproducibility

    PubMed Central

    Sadeghi, M.; Sina, S.; Faghihi, R.

    2015-01-01

    LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%. PMID:26688801

  16. ITER Disruption Mitigation System Design

    NASA Astrophysics Data System (ADS)

    Rasmussen, David; Lyttle, M. S.; Baylor, L. R.; Carmichael, J. R.; Caughman, J. B. O.; Combs, S. K.; Ericson, N. M.; Bull-Ezell, N. D.; Fehling, D. T.; Fisher, P. W.; Foust, C. R.; Ha, T.; Meitner, S. J.; Nycz, A.; Shoulders, J. M.; Smith, S. F.; Warmack, R. J.; Coburn, J. D.; Gebhart, T. E.; Fisher, J. T.; Reed, J. R.; Younkin, T. R.

    2015-11-01

    The disruption mitigation system for ITER is under design and will require injection of up to 10 kPa-m3 of deuterium, helium, neon, or argon material for thermal mitigation and up to 100 kPa-m3 of material for suppression of runaway electrons. A hybrid unit compatible with the ITER nuclear, thermal and magnetic field environment is being developed. The unit incorporates a fast gas valve for massive gas injection (MGI) and a shattered pellet injector (SPI) to inject a massive spray of small particles, and can be operated as an SPI with a frozen pellet or an MGI without a pellet. Three ITER upper port locations will have three SPI/MGI units with a common delivery tube. One equatorial port location has space for sixteen similar SPI/MGI units. Supported by US DOE under DE-AC05-00OR22725.

  17. Investigation of LiF, Mg and Ti (TLD-100) Reproducibility.

    PubMed

    Sadeghi, M; Sina, S; Faghihi, R

    2015-12-01

    LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%. PMID:26688801

  18. [sup 222]Rn dosimetry in the dog lung

    SciTech Connect

    Harley, N.H.; Meyers, O.A.; Robbins, E.S.

    1991-01-01

    The alpha dose to cells in bronchial airways in the beagle dog during historical exposures to [sup 222]Rn decay products is calculated using updated information on airway morphometry, call nucleus depth, mucus thickness, physical dosimetry and atmospheric characteristics. The alpha dose per unit exposure to basal call nuclei in the upper airways ranges from 2 to 7 mGy WLM[sup [minus]1] (excluding the trachea) depending upon the exposure protocol used. The dose to alveolar tissue is 3 mGy WLM[sup [minus]1]. In the human lung, the dose factor for the bronchial airways is 9 mGy WLM[sub [minus]1] and for the pulmonary parenchyma 0.5 mGy WLM[sup [minus]1] The human tumors appear primarily in the first few branching airway generations while the only tumors observed in the animals were in the bronchioloalveolar region suggesting a difference in cell sensitivity to alpha radiation.

  19. {sup 222}Rn dosimetry in the dog lung

    SciTech Connect

    Harley, N.H.; Meyers, O.A.; Robbins, E.S.

    1991-12-31

    The alpha dose to cells in bronchial airways in the beagle dog during historical exposures to {sup 222}Rn decay products is calculated using updated information on airway morphometry, call nucleus depth, mucus thickness, physical dosimetry and atmospheric characteristics. The alpha dose per unit exposure to basal call nuclei in the upper airways ranges from 2 to 7 mGy WLM{sup {minus}1} (excluding the trachea) depending upon the exposure protocol used. The dose to alveolar tissue is 3 mGy WLM{sup {minus}1}. In the human lung, the dose factor for the bronchial airways is 9 mGy WLM{sub {minus}1} and for the pulmonary parenchyma 0.5 mGy WLM{sup {minus}1} The human tumors appear primarily in the first few branching airway generations while the only tumors observed in the animals were in the bronchioloalveolar region suggesting a difference in cell sensitivity to alpha radiation.

  20. DNA alterations and effects on growth and reproduction in Daphnia magna during chronic exposure to gamma radiation over three successive generations.

    PubMed

    Parisot, Florian; Bourdineaud, Jean-Paul; Plaire, Delphine; Adam-Guillermin, Christelle; Alonzo, Frédéric

    2015-06-01

    This study examined chronic effects of external Cs-137 gamma radiation on Daphnia magna exposed over three successive generations (F0, F1 and F2) to environmentally relevant dose rates (ranging from 0.007 to 35.4 mGy h(-1)). Investigated endpoints included survival, growth, reproduction and DNA alterations quantified using random-amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Results demonstrated that radiation effects on survival, growth and reproduction increased in severity from generation F0 to generation F2. Mortality after 21 days at 35.4 mGy h(-1) increased from 20% in F0 to 30% in F2. Growth was affected by a slight reduction in maximum length at 35.4 mGy h(-1) in F0 and by reductions of 5 and 13% in growth rate, respectively, at 4.70 and 35.4 mGy h(-1) in F2. Reproduction was affected by a reduction of 19% in 21 day-fecundity at 35.4 mGy h(-1) in F0 and by a delay of 1.9 days in brood release as low as 0.070 mGy h(-1) in F2. In parallel, DNA alterations became significant at decreasing dose rates over the course of F0 (from 4.70 mGy h(-1) at hatching to 0.007 mGy h(-1) after ∼21 days) and from F0 to F2 (0.070 mGy h(-1) at hatching to 0.007 mGy h(-1) after ∼21 days), demonstrating their rapid accumulation in F0 daphnids and their transmission to offspring generations. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in F1, with no effect on survival, a slight reduction of 12% in 21 day-fecundity at 35.4 mGy h(-1) and DNA alterations significant at highest dose rates only. The study improved our understanding of long term responses to low doses of radiation at the molecular and organismic levels in a non-human species for a better radioprotection of aquatic ecosystems. PMID:25840277

  1. Is electron beam intraoperative radiotherapy (ELIOT) safe in pregnant women with early breast cancer? In vivo dosimetry to assess fetal dose.

    PubMed

    Galimberti, Viviana; Ciocca, Mario; Leonardi, Maria Cristina; Zanagnolo, Vanna; Paola, Baratella; Manuela, Sargenti; Sahium, Rafaela Cecilio; Lazzari, Roberta; Gentilini, Oreste; Peccatori, Fedro; Veronesi, Umberto; Orecchia, Roberto

    2009-01-01

    Electron beam intraoperative radiotherapy (ELIOT) is a new technique permitting breast radiotherapy to be completed in a single session. Since ELIOT is associated with much reduced irradiation to nontarget tissues, we carried out a study on nonpregnant breast cancer patients to estimate doses to the uterus during ELIOT to better evaluate the possible use of ELIOT in pregnant breast cancer patients. We performed in vivo dosimetry with thermoluminescence radiation detectors (TLDs) in 15 premenopausal patients receiving ELIOT to the breast (prescribed dose 21 Gy) using two mobile linear accelerators. The TLDs were positioned subdiaphragmatically on the irradiated side, at the medial pubic position, and within the uterus. A shielding apron (2 mm lead equivalent) was placed over the viscera from the subcostal to the subpubic region. TLDs showed mean doses of 3.7 mGy (range 1-8.5 mGy) at subdiaphragm, 0.9 mGy (range 0.3-2 mGy) pubic, and 1.7 mGy (range 0.6-3.2 mGy) in utero, for beam energies in the range 5-9 MeV. These findings indicate that ELIOT with a mobile linear accelerator and shielding apron would be safe for the fetus, as doses of a few mGy are not associated with measurable increased risk of fetal damage, and the threshold dose for deterministic effects is estimated at 100-200 mGy. We conclude that studies on the use of ELIOT in pregnant women treated with conservative breast surgery are justified. PMID:18941842

  2. Comparing Ovarian Radiation Doses in Flat-Panel and Conventional Angiography During Uterine Artery Embolization: A Randomized Clinical Trial

    PubMed Central

    Firouznia, Kavous; Ghanaati, Hossein; Sharafi, Aliakbar; Abahashemi, Firouze; Hashemi, Hassan; Jalali, Amir Hossein; Shakiba, Madjid

    2013-01-01

    Background Uterine artery embolization (UAE) is a minimally invasive procedure performed under fluoroscopy for the treatment of uterine fibroids and accompanied by radiation exposure. Objectives To compare ovarian radiation doses during uterine artery embolization (UAE) in patients using conventional digital subtraction angiography (DSA) with those using digital flat-panel technology. Patients and Methods Thirty women who were candidates for UAE were randomly enrolled for one of the two angiographic systems. Ovarian doses were calculated according to in-vitro phantom study results using entrance and exit doses and were compared between the two groups. Results The mean right entrance dose was 1586±1221 mGy in the conventional and 522.3±400.1 mGy in the flat panel group (P=0.005). These figures were 1470±1170 mGy and 456±396 mGy, respectively for the left side (P=0.006). The mean right exit dose was 18.8±12.3 for the conventional and 9.4±6.4 mGy for the flat panel group (P=0.013). These figures were 16.7±11.3 and 10.2±7.2 mGy, respectively for the left side (P=0.06). The mean right ovarian dose was 139.9±92 in the conventional and 23.6±16.2 mGy in the flat panel group (P<0.0001). These figures were 101.7±77.6 and 24.6±16.9 mGy, respectively for the left side (P=0.002). Conclusion Flat panel system can significantly reduce the ovarian radiation dose during UAE compared with conventional DSA. PMID:24348594

  3. Bridging the Gap: Linking Simulation and Testing

    SciTech Connect

    Krajewski, Paul E.; Carsley, John; Stoudt, Mark R.; Hovanski, Yuri

    2012-09-01

    The Materials Genome Initiative (MGI) which is a key enabler for the Advanced Manufacturing Partnership, announced in 2011 by U.S. President Barack Obama, was established to accelerate the development and deployment of advanced materials. The MGI is driven by the need to "bridge the gap" between (I) experimental results and computational analysis to enable the rapid development and validation of new mateirals, and (II) the processes required to convert these materials into useable goods.

  4. Therapeutic effect of lymphokine-activated killer cells treated with low-dose ionizing radiation on osteosarcoma

    PubMed Central

    ZHAO, LEI; LV, MING; SAYIMU, WULIYA; LIU, WEI; ZHANG, HUAWU; JIANG, BO; WANG, DONG

    2015-01-01

    The aim of the present study was to investigate the effect of lymphokine-activated killer (LAK) cells, which received low-dose ionizing radiation, on the treatment of osteosarcoma in rats. The cultured UMR-106 cells were inoculated under the anterior chest skin of 24 rats to establish an osteosarcoma model. In addition, the LAK cells from 24 mice were exposed to doses of 0 (control group), 0.65 or 3.25 mGy X-ray radiation. The tritiated thymidine (3H-TdR) release method and Winn assay were performed to determine the antitumor effects of the LAK cells. The proliferation of the mouse LAK cells treated with 3.25 mGy radiation was significantly higher than that for those treated with 0 or 0.65 mGy radiation, which suggested that low-dose ionizing radiation stimulates the proliferation of LAK cells. The tumor-bearing rats were divided into three groups and injected with LAK cells that had already received 0, 0.65 or 3.25 mGy radiation. The mean survival time of the 3.25-mGy group was longer than that of the 0- and 0.65-mGy groups. After 30 days, tumors with weights of ~6.25 and 2.0 g were identified in the rats of the 0- and 0.65-mGy groups, respectively. However, tumor proliferation was not detectable in the rats of the 3.25-mGy radiation group. Therefore, low-dose ionizing radiation effectively kills osteosarcoma cells in rats by stimulating the proliferation and enhancing the cytotoxicity of LAK cells. PMID:26622587

  5. Regulation of cell surface receptors for different hematopoietic growth factors on myeloid leukemic cells.

    PubMed Central

    Lotem, J; Sachs, L

    1986-01-01

    There are clones of myeloid leukemic cells which are different from normal myeloid cells in that they have become independent of hematopoietic growth factor for cell viability and growth. The ability of these clones to bind three types of hematopoietic growth factors (MGI-1GM = GM-CSF, IL-3 = multi-CSF and MGI-1M = M-CSF = CSF-1) was measured using the method of quantitative absorption at 1 degree C and low pH elution of cell-bound biological activity. Results of binding to normal myeloid and lymphoid cells were similar to those obtained by radioreceptor assays. The results indicate that the number of receptors on different clones of these leukemic cells varied from 0 to 1,300 per cell. The receptors have a high binding affinity. Receptors for different growth factors can be independently expressed in different clones. There was no relationship between expression of receptors for these growth factors and the phenotype of the leukemic cells regarding their ability to be induced to differentiate. The number of receptors on the leukemic cells was lower than on normal mature macrophages. Myeloid leukemic cells induced to differentiate by normal myeloid cell differentiation factor MGI-2 (= DF), or by low doses of actinomycin D or cytosine arabinoside, showed an up-regulation of the number of MGI-1GM and IL-3 receptors. Induction of differentiation of leukemic cells by MGI-2 also induced production and secretion of the growth factor MGI-1GM, and this induced MGI-1GM saturated the up-regulated MGI-1GM receptors. It is suggested that up-regulation of these receptors during differentiation is required for the functioning of differentiated cells. PMID:3023059

  6. Formation of optical color and fluorescence centers in polytetrafluoroethylene under γ-irradiation

    NASA Astrophysics Data System (ADS)

    Seliverstov, D. I.; Nurmukhametov, R. N.; Sergeev, A. M.; Klimenko, V. G.; Khatipov, S. A.

    2011-09-01

    Fluorescent properties and colors of polytetrafluoroethylene (PTFE) samples were studied as functions of absorbed dose of γ-radiation at a temperature above the melting temperature of the crystallites (327°C) in the dose range 0.2-0.8 MGy. The samples were irradiated at low pressure (10-6 Torr) in glass ampuls and at atmospheric pressure in a chamber purged with argon. Samples in ampuls acquired an off-white tint and fluoresced weakly. The fluorescence intensity increased slowly as the radiation dose increased from 0.2 to 0.6 MGy and decreased at 0.8 MGy. Samples irradiated in the chamber fluoresced more strongly and acquired colors that changed from gray (0.2 MGy) to dark-brown (0.8 MGy). Color centers were formed only in the sample surface layer. Their appearance was associated with the adsorption of particles of an unknown nature from the environment. The argon-purged samples turned white upon removing their surface layer (50 μm). The intensity and shape of fluorescence bands emitted by these samples remained essentially unaltered, i.e., depended weakly on the absorbed dose in the range 0.2-0.8 MGy.

  7. [The retrospective cytogenetic dosimetry using the results of conventional chromosomal analysis in Chernobyl clean-up workers].

    PubMed

    Maznik, N A; Vinnikov, V A

    2005-01-01

    The paper presents the results of the cohortal biodosimetry carried out in 435 Chernobyl clean-up workers, who were surveyed with the conventional cytogenetic technique in terms from several days to 10 years after the end of their duties in the Chernobyl accident exclusive zone. An empirical model of the aberrant cell dynamics was utilized for the calculation of mean initial yields of dicentrics and centric rings in groups with different terms and duration of staying in the Chernobyl zone. Corresponding protracted irradiation doses estimated from aberration levels ranged from 79 to 670 mGy. The probabilistic distribution of the radiation doses was constructed by the applying the Bayesian analysis to initial individual chromosome exchange yields extrapolated to the exposure termination moment. This distribution was characterized by the mean dose about 460 mGy and maximum of probability density in the interval of 50-300 mGy. For the late somatic risk assessment in clean-up workers the probabilistic distribution of equivalentally-acute radiation doses was proposed; that had the mean value about 270 mGy, modal classes of 250-350 mGy and 99.8% of the probability density concentrated within the dose range from 0 to 1000 mGy. PMID:16454338

  8. Development of optical components for in-vessel viewing systems used for fusion experimental reactor

    NASA Astrophysics Data System (ADS)

    Obara, Kenjiro; Kakudate, Satoshi; Oka, Kiyoshi; Tada, Eisuke; Morita, Yosuke; Seki, Masahiro

    1994-12-01

    Optical components including imagefiber, periscope, glass, reflecting mirror and adhesive for lens are essential elements of in-vessel viewing system use for fusion experimental reactor and extensive of gamma irradiation tests have been conducted. These components were irradiated in the range of 1 MGy - 100 MGy under the average exposure dose rate of 1 X 106 R/h. As a result, the observation limit of the imagefiber specially fabricated for radiation hard is obtained to be 12 MGy at a illuminance of 8500 lx. Deterioration of transmissivity of three kinds of glass (alkaline barium glass, lead glass and synthetic quartz glass) is small compared with standard glass for commercial periscope. A periscope which was made of these glasses is visible even after 20 MGy at 8500 lx and in case of the standard periscope, the observation limit is 1 kGy at 8500 lx. Decrease in the reflectance on chromium nitride coated reflecting mirror is extremely small than aluminum coated and platinum coated mirrors at accumulated dose of 100 MGy. Two types of adhesive made of polyester resin and epoxy resin became discolored and exfoliated after 50 MGy.

  9. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    NASA Astrophysics Data System (ADS)

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation.

  10. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    PubMed Central

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation. PMID:26795421

  11. SU-E-I-28: Evaluating the Organ Dose From Computed Tomography Using Monte Carlo Calculations

    SciTech Connect

    Ono, T; Araki, F

    2014-06-01

    Purpose: To evaluate organ doses from computed tomography (CT) using Monte Carlo (MC) calculations. Methods: A Philips Brilliance CT scanner (64 slice) was simulated using the GMctdospp (IMPS, Germany) based on the EGSnrc user code. The X-ray spectra and a bowtie filter for MC simulations were determined to coincide with measurements of half-value layer (HVL) and off-center ratio (OCR) profile in air. The MC dose was calibrated from absorbed dose measurements using a Farmer chamber and a cylindrical water phantom. The dose distribution from CT was calculated using patient CT images and organ doses were evaluated from dose volume histograms. Results: The HVLs of Al at 80, 100, and 120 kV were 6.3, 7.7, and 8.7 mm, respectively. The calculated HVLs agreed with measurements within 0.3%. The calculated and measured OCR profiles agreed within 3%. For adult head scans (CTDIvol) =51.4 mGy), mean doses for brain stem, eye, and eye lens were 23.2, 34.2, and 37.6 mGy, respectively. For pediatric head scans (CTDIvol =35.6 mGy), mean doses for brain stem, eye, and eye lens were 19.3, 24.5, and 26.8 mGy, respectively. For adult chest scans (CTDIvol=19.0 mGy), mean doses for lung, heart, and spinal cord were 21.1, 22.0, and 15.5 mGy, respectively. For adult abdominal scans (CTDIvol=14.4 mGy), the mean doses for kidney, liver, pancreas, spleen, and spinal cord were 17.4, 16.5, 16.8, 16.8, and 13.1 mGy, respectively. For pediatric abdominal scans (CTDIvol=6.76 mGy), mean doses for kidney, liver, pancreas, spleen, and spinal cord were 8.24, 8.90, 8.17, 8.31, and 6.73 mGy, respectively. In head scan, organ doses were considerably different from CTDIvol values. Conclusion: MC dose distributions calculated by using patient CT images are useful to evaluate organ doses absorbed to individual patients.

  12. Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients*

    PubMed Central

    Cantalupo, Beatriz de Lucena Villa-Chan; Xavier, Aline Carvalho da Silva; da Silva, Clemanzy Mariano Leandro; Andrade, Marcos Ely Almeida; de Barros, Vinícius Saito Monteiro; Khoury, Helen Jamil

    2016-01-01

    Objective To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and Methods Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses. PMID:27141129

  13. Quantitative assessment of the cataractogenic potential of very low doses of neutrons

    NASA Technical Reports Server (NTRS)

    Worgul, B. V.; Medvedovsky, C.; Huang, Y.; Marino, S. A.; Randers-Pehrson, G.; Brenner, D. J.

    1996-01-01

    We report on the prevalence and relative biological effectiveness (RBE) for various stages of lens opacification in rats induced by very low doses (2 to 250 mGy) of medium-energy (440 keV) neutrons, compared to those for X rays. Neutron doses were delivered either in a single fraction or in four separate fractions and the irradiated animals were followed for over 100 weeks. At the highest observed dose (250 mGy) and at early observation times, there was evidence of an inverse dose-rate effect; i.e., a fractionated exposure was more potent than a single exposure. Neutron RBEs relative to X rays were estimated using a non-parametric technique. The results were only weakly dependent on time postirradiation. At 30 weeks, for example, 80% confidence intervals for the RBE of acutely delivered neutrons relative to X rays were 8-16 at 250 mGy, 10-20 at 50 mGy, 50-100 at 10 mGy and 250-500 at 2 mGy. The results are consistent with the estimated neutron RBEs in Japanese A-bomb survivors, though broad confidence bounds are present in the Japanese results. Our findings are also consistent with data reported earlier for cataractogenesis induced by heavy ions in rats, mice, and rabbits. We conclude from these results that, at very low doses (<10 mGy), the RBE for neutron-induced cataractogenesis is considerably larger than the RBE of 20 commonly used, and use of a significantly larger value for calculating equivalent dose would be prudent.

  14. Kilovoltage cone-beam CT imaging dose during breast radiotherapy: A dose comparison between a left and right breast setup

    SciTech Connect

    Quinn, Alexandra; Holloway, Lois; Begg, Jarrad; Nelson, Vinod; Metcalfe, Peter

    2014-07-01

    The purpose of this study was to investigate the delivered dose from a kilovoltage cone-beam computed tomography (kV-CBCT) acquired in breast treatment position for a left and right breast setup. The dose was measured with thermoluminescent dosimeters positioned within a female anthropomorphic phantom at organ locations. Imaging was performed on an Elekta Synergy XVI system with the phantom setup on a breast board. The image protocol involved 120 kVp, 140 mAs, and a 270° arc rotation clockwise 0° to 270° for the left breast setup and 270° to 180° for the right breast setup (maximum arc rotations possible). The dose delivered to the left breast, right breast, and heart was 5.1 mGy, 3.9 mGy, and 4.0 mGy for the left breast setup kV-CBCT, and 6.4 mGy, 6.0 mGy, and 4.8 mGy for the right breast setup kV-CBCT, respectively. The rotation arc of the kV-CBCT influenced the dose delivered, with the right breast setup kV-CBCT found to deliver a dose of up to 4 mGy or 105% higher to the treated breast′s surface in comparison with the left breast setup. This is attributed to the kV-CBCT source being more proximal to the anterior of the phantom for a right breast setup, whereas the source is more proximal to the posterior of the patient for a left-side scan.

  15. Effect of filter on average glandular dose and image quality in digital mammography

    NASA Astrophysics Data System (ADS)

    Songsaeng, C.; Krisanachinda, A.; Theerakul, K.

    2016-03-01

    To determine the average glandular dose and entrance surface air kerma in both phantoms and patients to assess image quality for different target-filters (W/Rh and W/Ag) in digital mammography system. The compressed breast thickness, compression force, average glandular dose, entrance surface air kerma, peak kilovoltage and tube current time were recorded and compared between W/Rh and W/Ag target filter. The CNR and the figure of merit were used to determine the effect of target filter on image quality. The mean AGD of the W/Rh target filter was 1.75 mGy, the mean ESAK was 6.67 mGy, the mean CBT was 54.1 mm, the mean CF was 14 1bs. The mean AGD of W/Ag target filter was 2.7 mGy, the mean ESAK was 12.6 mGy, the mean CBT was 75.5 mm, the mean CF was 15 1bs. In phantom study, the AGD was 1.2 mGy at 4 cm, 3.3 mGy at 6 cm and 3.83 mGy at 7 cm thickness. The FOM was 24.6, CNR was 9.02 at thickness 6 cm. The FOM was 18.4, CNR was 8.6 at thickness 7 cm. The AGD from Digital Mammogram system with W/Rh of thinner CBT was lower than the AGD from W/Ag target filter.

  16. Kilovoltage cone-beam CT imaging dose during breast radiotherapy: a dose comparison between a left and right breast setup.

    PubMed

    Quinn, Alexandra; Holloway, Lois; Begg, Jarrad; Nelson, Vinod; Metcalfe, Peter

    2014-01-01

    The purpose of this study was to investigate the delivered dose from a kilovoltage cone-beam computed tomography (kV-CBCT) acquired in breast treatment position for a left and right breast setup. The dose was measured with thermoluminescent dosimeters positioned within a female anthropomorphic phantom at organ locations. Imaging was performed on an Elekta Synergy XVI system with the phantom setup on a breast board. The image protocol involved 120kVp, 140mAs, and a 270° arc rotation clockwise 0° to 270° for the left breast setup and 270° to 180° for the right breast setup (maximum arc rotations possible). The dose delivered to the left breast, right breast, and heart was 5.1mGy, 3.9mGy, and 4.0mGy for the left breast setup kV-CBCT, and 6.4mGy, 6.0mGy, and 4.8mGy for the right breast setup kV-CBCT, respectively. The rotation arc of the kV-CBCT influenced the dose delivered, with the right breast setup kV-CBCT found to deliver a dose of up to 4mGy or 105% higher to the treated breast's surface in comparison with the left breast setup. This is attributed to the kV-CBCT source being more proximal to the anterior of the phantom for a right breast setup, whereas the source is more proximal to the posterior of the patient for a left-side scan. PMID:24630912

  17. Determining and Managing Fetal Radiation Dose from Diagnostic Radiology Procedures in Turkey

    PubMed Central

    Cavdar, Iffet; Seven, Mehmet; Uslu, Lebriz; Yeyin, Nami; Tanyildizi, Handan; Abuqbeitah, Mohammad; Acikgoz, A. Serdar; Tuten, Abdullah; Demir, Mustafa

    2015-01-01

    Objective We intended to calculate approximate fetal doses in pregnant women who underwent diagnostic radiology procedures and to evaluate the safety of their pregnancies. Materials and Methods We contacted hospitals in different cities in Turkey where requests for fetal dose calculation are usually sent. Fetal radiation exposure was calculated for 304 cases in 218 pregnant women with gestational ages ranging from 5 days to 19 weeks, 2 days. FetDose software (ver. 4.0) was used in fetal dose calculations for radiographic and computed tomography (CT) procedures. The body was divided into three zones according to distance from the fetus. The first zone consisted of the head area, the lower extremities below the knee, and the upper extremities; the second consisted of the cervicothoracic region and upper thighs; and the third consisted of the abdominopelvic area. Fetal doses from radiologic procedures between zones were compared using the Kruskal-Wallis test and a Bonferroni-corrected Mann-Whitney U-test. Results The average fetal doses from radiography and CT in the first zone were 0.05 ± 0.01 mGy and 0.81 ± 0.04 mGy, respectively; 0.21 ± 0.05 mGy and 1.77 ± 0.22 mGy, respectively, in the second zone; and 6.42 ± 0.82 mGy and 22.94 ± 1.28 mGy, respectively, in the third zone (p < 0.001). Our results showed that fetal radiation exposures in our group of pregnant women did not reach the level (50 mGy) that is known to increase risk for congenital anomalies. Conclusion Fetal radiation exposure in the diagnostic radiology procedures in our study did not reach risk levels that might have indicated abortion. PMID:26576117

  18. Imaging doses from the Elekta Synergy X-ray cone beam CT system.

    PubMed

    Amer, A; Marchant, T; Sykes, J; Czajka, J; Moore, C

    2007-06-01

    The Elekta Synergy is a radiotherapy treatment machine with integrated kilovoltage (kV) X-ray imaging system capable of producing cone beam CT (CBCT) images of the patient in the treatment position. The aim of this study is to assess the additional imaging dose. Cone beam CT dose index (CBDI) is introduced and measured inside standard CTDI phantoms for several sites (head: 100 kV, 38 mAs, lung: 120 kV, 152 mAs and pelvis: 130 kV, 456 mAs). The measured weighted doses were compared with thermoluminescent dosimeter (TLD) measurements at various locations in a Rando phantom and at patients' surfaces. The measured CBDIs in-air at the isocentre were 9.2 mGy 100 mAs(-1), 7.3 mGy 100 mAs(-1) and 5.3 mGy 100 mAs(-1) for 130 kV, 120 kV and 100 kV, respectively. The body phantom weighted CBDI were 5.5 mGy 100 mAs(-1) and 3.8 mGy 100 mAs(-1 )for 130 kV and 120 kV. The head phantom weighted CBDI was 4.3 mGy 100 mAs(-1) for 100 kV. The weighted doses for the Christie Hospital CBCT imaging techniques were 1.6 mGy, 6 mGy and 22 mGy for the head, lung and pelvis. The measured CBDIs were used to estimate the total effective dose for the Synergy system using the ImPACT CT Patient Dosimetry Calculator. Measured CBCT doses using the Christie Hospital protocols are low for head and lung scans whether compared with electronic portal imaging (EPI), commonly used for treatment verification, or single and multiple slice CT. For the pelvis, doses are similar to EPI but higher than CT. Repeated use of CBCT for treatment verification is likely and hence the total patient dose needs to be carefully considered. It is important to consider further development of low dose CBCT techniques to keep additional doses as low as reasonably practicable. PMID:17684077

  19. Medical x-ray exposure doses as contaminants of atomic bomb doses.

    PubMed

    Yamamoto, O; Antoku, S; Russell, W J; Fujita, S; Sawada, S

    1988-03-01

    Since 1967 at the times of their biennial ABCC/RERF radiological examinations, all Adult Health Study (AHS) subjects have been interviewed to determine the exposures to medical x-rays they experienced in institutions other than RERF in order to estimate the numbers of examinations and corresponding doses which they received. These data have been stored on computer tapes together with the doses these subjects received during their radiological examinations in the ABCC/RERF Department of Radiology. Thus, their medical x-ray doses are available along with their atomic bomb doses (tentative 1965 doses revised, T65DR) for assessment of the role of ionizing radiation in the development of diseases. The medical x-ray doses incurred at RERF were assessed by means of phantom dosimetry. Those at other institutions were determined using phantom dosimetry data and results of surveys for trends in radiological examinations in Hiroshima and Nagasaki. By the end of 1982, the average medical x-ray doses to the active bone marrow were 12.04 mGy for A-bomb exposed groups and 8.92 mGy for control groups (not-in-cities); to the male gonads, 2.26 mGy and 1.89 mGy, respectively; and to the female gonads, 17.45 mGy and 12.58 mGy, respectively. Results for Hiroshima and Nagasaki were similar. The main impact of medical x-ray doses was in the lowest T65DR group. Medical x-ray active bone marrow doses ranged from 0.05-500% (mean, 35%) of A-bomb doses in the 10-99 mGy T65DR group. In the 100-999 mGy T65DR group, medical x-ray active bone marrow doses ranged from 0.005-50% (mean, 5%) of their T65DR. In the greater than 1,000-mGy T65DR group, medical x-ray exposures were proportionally less. Female active bone marrow and gonad doses were similar in magnitude to the male active bone marrow doses. Medical x-ray exposures produced smaller doses to the gonads of males than to those of the females. The use of medical x-rays is steadily increasing. Careful consideration of doses from medical sources

  20. Evaluation of entrance surface air kerma from exposure index in computed radiography

    NASA Astrophysics Data System (ADS)

    Costa, A. M.; Pelegrino, M. S.

    2014-11-01

    The aim of this study was to establish an indirect method to calculate the values of entrance surface air kerma in patients undergoing diagnostic examinations in X-ray systems with computed radiography based on the exposure index. The entrance surface air kerma values were compared with values obtained also indirectly based on measurements of X-ray tube output. The mean±standard deviation (1σ) and third quartile for entrance surface air kerma calculated from the exposure index were 2.1±1.0 mGy and 3.0 mGy, respectively. For entrance surface air kerma based on measurements of the X-ray tube output, the mean±standard deviation (1σ) and third quartile were respectively 3.1±1.9 mGy and 5.5 mGy. The observed values of entrance surface air kerma are smaller than the reference level adopted in Brazil (10 mGy). The results obtained with both methods were similar when taking into account the estimated uncertainties in the determination of air kerma values, although the reproducibility of the determinations based on the exposure index is better.

  1. Effect of gamma irradiation at intermediate doses on the performance of reverse osmosis membranes

    NASA Astrophysics Data System (ADS)

    Combernoux, Nicolas; Labed, Véronique; Schrive, Luc; Wyart, Yvan; Carretier, Emilie; Moulin, Philippe

    2016-07-01

    The goal of this study is to explain the degradation of Polyamide (PA) composite reverse osmosis membrane (RO) in function of the irradiation dose. Irradiations were performed with a gamma 60Co source in wet conditions and under oxygen atmosphere. For different doses of 0.2 and 0.5 MGy with a constant dose rate of 0.5 kGy h-1, RO membranes performances (NaCl retention, permeability) were studied before and after irradiation. ATR-FTIR, ion chromatography and gas chromatography were used to characterize structural modification. Results showed that the permeability of RO membranes irradiated at 0.2 MGy exhibited a small decrease, related to scissions of the PVA coating. However, retention did not change at this dose. At 0.5 MGy, permeability showed a large increase of a factor around 2 and retention began to decrease from 99% to 95%. Chromatography measurements revealed a strong link between permselectivity properties variation, ion leakage and oxygen consumption. Add to ATR-FTIR observations, these results emphasized that the cleavages of amide and ester bonds were observed at 0.5 MGy, more precisely the loss of hydrogen bonds between polyamide chains. By different analysis, modifications of the polysulfone layer occur until a dose of 0.2 MGy.

  2. Imaging lobular breast carcinoma: comparison of synchrotron radiation DEI-CT technique with clinical CT, mammography and histology

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Bravin, A.; Keyriläinen, J.; Fernández, M.; Suortti, P.; Thomlinson, W.; Tenhunen, M.; Virkkunen, P.; Karjalainen-Lindsberg, M.-L.

    2004-01-01

    Different modalities for imaging cancer-bearing breast tissue samples are described and compared. The images include clinical mammograms and computed tomography (CT) images, CT images with partly coherent synchrotron radiation (SR), and CT and radiography images taken with SR using the diffraction enhanced imaging (DEI) method. The images are evaluated by a radiologist and compared with histopathological examination of the samples. Two cases of lobular carcinoma are studied in detail. The indications of cancer are very weak or invisible in the conventional images, but the morphological changes due to invasion of cancer become pronounced in the images taken by the DEI method. The strands penetrating adipose tissue are seen clearly in the DEI-CT images, and the histopathology confirms that some strands contain the so-called 'Indian file' formations of cancer cells. The radiation dose is carefully measured for each of the imaging modalities. The mean glandular dose (MGD) for 50% glandular breast tissue is about 1 mGy in conventional mammography and less than 0.25 mGy in projection DEI, while in the clinical CT imaging the MGD is very high, about 45 mGy. The entrance dose of 95 mGy in DEI-CT imaging gives rise to an MGD of 40 mGy, but the dose may be reduced by an order of magnitude, because the contrast is very large in most images.

  3. [Slow Formation and Degradation of γH2AX Foci in Human Skin Fibroblasts Exposed to Low-Dose X-Ray Radiation].

    PubMed

    Grekhova, A K; Eremin, P S; Osipov, A N; Eremin, I I; Pustovalova, M V; Ozerov, I V; Smetanina, N M; Lazareva, N L; Vorobyeva, N Yu; Pulin, A A; Maksimova, O A; Gordeev, A V; Bushmanov, A Yu; Kotenko, K V

    2015-01-01

    It was shown that the kinetics of changes of γH2AX foci number (marker of DNA double-strand breaks) in human skin fibroblasts after exposure to low doses of X-ray radiation (20, 40 and 80 mGy) differs from that observed after exposure to medium-low doses (160 and 240 mGy). After exposure to 160 and 240 mGy the highest number of γH2AX foci was detected at 30 min after exposure (first experimental point) and further their decrease was observed. At the same time we observed a fast phase of repair (upto 4 h), in which there was a decrease of the foci amount to ~50-60% and a slow phase of repair (from 4 h to 24 h). After 24 h only ~3-5% of the foci amount observed at 30 min after irradiation was left. After exposure to low doses, the foci number did not decrease during 2 h and even 24 h after exposure their amount was ~25% from that observed at maximum points (1 h after irradiation at 40 and 80 mGy and 2 h after irradiation at 20 mGy). PMID:26601539

  4. Low-dose neutron dose response of zebrafish embryos obtained from the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Kong, E. Y.; Konishi, T.; Kobayashi, A.; Suya, N.; Cheng, S. H.; Yu, K. N.

    2015-09-01

    The dose response of embryos of the zebrafish, Danio rerio, irradiated at 5 h post fertilization (hpf) by 2-MeV neutrons with ≤100 mGy was determined. The neutron irradiations were made at the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility in the National Institute of Radiological Sciences (NIRS), Chiba, Japan. A total of 10 neutron doses ranging from 0.6 to 100 mGy were employed (with a gamma-ray contribution of 14% to the total dose), and the biological effects were studied through quantification of apoptosis at 25 hpf. The responses for neutron doses of 10, 20, 25, and 50 mGy approximately fitted on a straight line, while those for neutron doses of 0.6, 1 and 2.5 mGy exhibited neutron hormetic effects. As such, hormetic responses were generically developed by different kinds of ionizing radiations with different linear energy transfer (LET) values. The responses for neutron doses of 70 and 100 mGy were significantly below the lower 95% confidence band of the best-fit line, which strongly suggested the presence of gamma-ray hormesis.

  5. Radiation induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1991-01-01

    A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of development is consistent with the findings of small head size induced in those exposed prior to the eight week of conception at Hiroshima. This implies a mechanism for micrencephaly different from those previously suggested and lends credence to a causal relation between radiation and small head size in humans at low doses as reported by Miller and Mulvihill. 16 refs., 13 tabs.

  6. Paternity analysis reveals significant isolation and near neighbor pollen dispersal in small Cariniana legalis Mart. Kuntze populations in the Brazilian Atlantic Forest.

    PubMed

    Tambarussi, Evandro V; Boshier, David; Vencovsky, Roland; Freitas, Miguel L M; Sebbenn, Alexandre M

    2015-12-01

    Throughout the world, large trees are increasingly rare. Cariniana legalis is the tallest tree species of the Brazilian Atlantic Forest, reaching up to 60 m in height. Due to extensive deforestation of the Atlantic Forest, remnant C. legalis populations are small and spatially isolated, requiring the development of strategies for their conservation. For in situ and ex situ genetic conservation to be effective, it is important to understand the levels and patterns of spatial genetic structure (SGS), and gene flow. We investigated SGS and pollen flow in three small, physically isolated C. legalis stands using microsatellite loci. We measured, mapped, and sampled all C. legalis trees in the three stands: 65 trees from Ibicatu population, 22 trees from MGI, and 4 trees from MGII. We also collected and genotyped 600 seeds from Ibicatu, 250 seeds from MGI, and 200 seeds from MGII. Significant SGS was detected in Ibicatu up to 150 m, but substantial levels of external pollen flow were also detected in Ibicatu (8%), although not in MGI (0.4%) or MGII (0%). Selfing was highest in MGII (18%), the smallest group of trees, compared to MGI (6.4%) and Ibicatu (6%). In MGI and MGII, there was a strong pattern of mating among near-neighbors. Seed collection strategies for breeding, in situ and ex situ conservation and ecological restoration, must ensure collection from seed trees located at distances greater than 350 m and from several forest fragments. PMID:27069608

  7. Radiation tolerance of the readout chip for the Phase I upgrade of the CMS pixel detector

    NASA Astrophysics Data System (ADS)

    Hoss, J.; Kästli, H.-C.; Meier, B.; Rohe, T.; Starodumov, A.

    2016-01-01

    For the Phase I upgrade of the CMS pixel detector a new digital readout chip (ROC) has been developed. An important part of the design verification are irradiation studies to ensure sufficient radiation tolerance. The paper summarizes results of the irradiation studies on the final ROC design for the detector layers 2 - 4. Samples have been irradiated with 23 MeV protons to accumulate the expected lifetime dose of 0.5 MGy and up to 1.1 MGy to project the performance of the ROC for layer 1 of the detector. It could be shown that the design is sufficiently radiation tolerant and that all performance parameters stay within their specifications. Additionally, very high doses of up to 4.2 MGy have been tested to explore the limits of the current chip design on 250 nm CMOS technology. The study confirmed that samples irradiated up to the highest dose could be successfully operated with test pulses.

  8. Study of the radiated energy loss during massive gas injection mitigated disruptions on EAST

    NASA Astrophysics Data System (ADS)

    Duan, Y. M.; Hao, Z. K.; Hu, L. Q.; Wang, L.; Xu, P.; Xu, L. Q.; Zhuang, H. D.

    2015-08-01

    The MGI mitigated disruption experiments were carried out on EAST with a new fast gas controlling valve in 2012. Different amounts of noble gas He or mixed gas of 99% He + 1% Ar are injected into plasma in current flat-top phase and current ramp-down phase separately. The initial results of MGI experiments are described. The MGI system and the radiation measurement system are briefly introduced. The characteristics of radiation distribution and radiation energy loss are analyzed. About 50% of the stored thermal energy Wdia is dissipated by radiation during the entire disruption process and the impurities of C and Li from the PFC play important roles to radiative energy loss. The amount of the gas can affect the pre-TQ phase. Strong poloidal asymmetry of radiation begins to appear in the CQ phase, which is possibly caused by the plasma configuration changes as a result of VDE. No toroidal radiation asymmetry is observed presently.

  9. Considerations in the Radiologic Evaluation of the Pregnant Orthopaedic Patient.

    PubMed

    Matzon, Jonas L; Lutsky, Kevin F; Ricci, Emily K; Beredjiklian, Pedro K

    2015-08-01

    Radiographic imaging of the pregnant patient represents a diagnostic and management dilemma for the orthopaedic surgeon. Imaging is often necessary in the setting of trauma; however, in utero radiation exposure can result in deleterious developmental effects in the embryo and fetus. The likelihood of a negative effect is proportional to the radiation dose and the gestational age of the embryo or fetus at the time of exposure. Ionizing radiation doses >100 mGy in the first trimester of pregnancy may lead to spontaneous abortion, malformation, and mental retardation. Whereas plain radiographs of the extremities and cervical spine expose the fetus to minimal doses of radiation of <10 mGy, other commonly performed orthopaedic diagnostic studies, such as CT of the pelvis, emit significantly higher exposure doses of approximately 35 mGy. Non-emitting modalities, such as ultrasonography and MRI, are alternatives for evaluation in the clinical setting. PMID:26116850

  10. Oxygen vacancies controlled multiple magnetic phases in epitaxial single crystal Co0.5(Mg0.55Zn0.45)0.5O1-v thin films.

    PubMed

    Zhu, Dapeng; Cao, Qiang; Qiao, Ruimin; Zhu, Shimeng; Yang, Wanli; Xia, Weixing; Tian, Yufeng; Liu, Guolei; Yan, Shishen

    2016-01-01

    High quality single-crystal fcc-Cox(MgyZn1-y)1-xO1-v epitaxial thin films with high Co concentration up to x = 0.5 have been fabricated by molecular beam epitaxy. Systematic magnetic property characterization and soft X-ray absorption spectroscopy analysis indicate that the coexistence of ferromagnetic regions, superparamagnetic clusters, and non-magnetic boundaries in the as-prepared Cox(MgyZn1-y)1-xO1-v films is a consequence of the intrinsic inhomogeneous distribution of oxygen vacancies. Furthermore, the relative strength of multiple phases could be modulated by controlling the oxygen partial pressure during sample preparation. Armed with both controllable magnetic properties and tunable band-gap, Cox(MgyZn1-y)1-xO1-v films may have promising applications in future spintronics. PMID:27062992

  11. Oxygen vacancies controlled multiple magnetic phases in epitaxial single crystal Co0.5(Mg0.55Zn0.45)0.5O1-v thin films

    NASA Astrophysics Data System (ADS)

    Zhu, Dapeng; Cao, Qiang; Qiao, Ruimin; Zhu, Shimeng; Yang, Wanli; Xia, Weixing; Tian, Yufeng; Liu, Guolei; Yan, Shishen

    2016-04-01

    High quality single-crystal fcc-Cox(MgyZn1-y)1-xO1-v epitaxial thin films with high Co concentration up to x = 0.5 have been fabricated by molecular beam epitaxy. Systematic magnetic property characterization and soft X-ray absorption spectroscopy analysis indicate that the coexistence of ferromagnetic regions, superparamagnetic clusters, and non-magnetic boundaries in the as-prepared Cox(MgyZn1-y)1-xO1-v films is a consequence of the intrinsic inhomogeneous distribution of oxygen vacancies. Furthermore, the relative strength of multiple phases could be modulated by controlling the oxygen partial pressure during sample preparation. Armed with both controllable magnetic properties and tunable band-gap, Cox(MgyZn1-y)1-xO1-v films may have promising applications in future spintronics.

  12. Radiation-induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-11-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  13. Radiation-induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-01-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  14. Cascade Cyclizations of Acyclic and Macrocyclic Alkynones: Studies toward the Synthesis of Phomactin A

    PubMed Central

    Ciesielski, Jennifer; Gandon, Vincent; Frontier, Alison J.

    2013-01-01

    A study of the reactivity and diastereoselectivity of the Lewis acid-promoted cascade cyclizations of both acyclic and macrocyclic alkynones is described. In these reactions, a β-iodoallenolate intermediate is generated via conjugate addition of iodide to an alkynone, followed by an intramolecular aldol reaction with a tethered aldehyde to afford a cyclohexenyl alcohol. The Lewis acid magnesium iodide (MgI2) was found to promote irreversible ring closure, while cyclizations using BF3·OEt2 as promoter occurred reversibly. For both acyclic and macrocyclic ynones, high diastereoselectivity was observed in the intramolecular aldol reaction. The MgI2 protocol for cyclization was applied to the synthesis of advanced intermediates relevant to the synthesis of phomactin natural products, during which a novel transannular cation-olefin cyclization was observed. DFT calculations were conducted to analyze the mechanism of this unusual MgI2-promoted process. PMID:23724905

  15. GASCan 2 payload integration

    NASA Technical Reports Server (NTRS)

    Cody, Dennis J.; Concepcion, Allan G.; Watras, Edward C., III

    1995-01-01

    This project, conducted in cooperation with the NASA Advanced Space Design Program, is part of an ongoing effort to place an experiment package into space. The goal of this project is to build and test flight-ready hardware that can be launched from the Space Shuttle. Get Away Special Canister 2 (GASCan 2) consists of three separate experiments. The Ionospheric Properties and Propagation Experiment (IPPE) determines effects of the ionosphere on radio wave propagation. The Microgravity Ignition experiment (MGI) tests the effects of combustion in a microgravity environment. The Rotational Fluid Flow experiment (RFF) examines fluid behavior under varying levels of gravity. This year the following tasks were completed: design of the IPPE antenna, X- and J-cell battery boxes, J-cell battery box enclosure, and structural bumpers; construction of the MGI canisters, MGI mounting brackets, IPPE antenna, and battery boxes; and the selection of the RFF's operating fluid and the analysis of the fluid behavior under microgravity test conditions.

  16. Characterization of MHD activity and its influence on radiation asymmetries during massive gas injection in DIII-D

    NASA Astrophysics Data System (ADS)

    Shiraki, D.; Commaux, N.; Baylor, L. R.; Eidietis, N. W.; Hollmann, E. M.; Izzo, V. A.; Moyer, R. A.; Paz-Soldan, C.

    2015-07-01

    Measurements from the DIII-D tokamak show that toroidal radiation asymmetries during fast shutdown by massive gas injection (MGI) are largely driven by n=1 magnetohydrodynamic modes during the thermal quench. The phenomenology of these modes, which are driven unstable by profile changes as the thermal energy is quenched, is described based on detailed magnetic measurements. The toroidal evolution of the dominantly n=1 perturbation is understood to be a function of three parameters: the location of the MGI port, pre-MGI plasma rotation, and n=1 error fields. The resulting level of radiation asymmetry in these DIII-D plasmas is modest, with a toroidal peaking factor (TPF) of 1.2+/- 0.1 for the total thermal quench energy and 1.4+/- 0.3 for the peak radiated power, both of which are below the estimated limit for ITER (TPF ≈ 2) (Sugihara et al 2007 Nucl. Fusion 47 337).

  17. Oxygen vacancies controlled multiple magnetic phases in epitaxial single crystal Co0.5(Mg0.55Zn0.45)0.5O1-v thin films

    PubMed Central

    Zhu, Dapeng; Cao, Qiang; Qiao, Ruimin; Zhu, Shimeng; Yang, Wanli; Xia, Weixing; Tian, Yufeng; Liu, Guolei; Yan, Shishen

    2016-01-01

    High quality single-crystal fcc-Cox(MgyZn1-y)1-xO1-v epitaxial thin films with high Co concentration up to x = 0.5 have been fabricated by molecular beam epitaxy. Systematic magnetic property characterization and soft X-ray absorption spectroscopy analysis indicate that the coexistence of ferromagnetic regions, superparamagnetic clusters, and non-magnetic boundaries in the as-prepared Cox(MgyZn1-y)1-xO1-v films is a consequence of the intrinsic inhomogeneous distribution of oxygen vacancies. Furthermore, the relative strength of multiple phases could be modulated by controlling the oxygen partial pressure during sample preparation. Armed with both controllable magnetic properties and tunable band-gap, Cox(MgyZn1-y)1-xO1-v films may have promising applications in future spintronics. PMID:27062992

  18. Absorbed Radiation Dose in Radiosensitive Organs During Coronary CT Angiography Using 320-MDCT: Effect of Maximum Tube Voltage and Heart Rate Variations

    PubMed Central

    Nikolic, Boris; Khosa, Faisal; Lin, Pei-Jan Paul; Khan, Atif N.; Sarwar, Sheryar; Yam, Chun-Shan; Court, Laurence E.; Raptopoulos, Vassilios; Clouse, Melvin E.

    2012-01-01

    OBJECTIVE The purpose of this article is to estimate the absorbed radiation dose in radiosensitive organs during coronary MDCT angiography using 320-MDCT and to determine the effects of tube voltage variation and heart rate (HR) control on absorbed radiation dose. MATERIALS AND METHODS Semiconductor field effect transistor detectors were used to measure absorbed radiation doses for the thyroid, midbreast, breast, and midlung in an anthropomorphic phantom at 100, 120, and 135 kVp at two different HRs of 60 and 75 beats per minute (bpm) with a scan field of view of 320 mm, 400 mA, 320 × 0.5 mm detectors, and 160 mm collimator width (160 mm range). The paired Student’s t test was used for data evaluation. RESULTS At 60 bpm, absorbed radiation doses for 100, 120, and 135 kVp were 13.41 ± 3.59, 21.7 ± 4.12, and 29.28 ± 5.17 mGy, respectively, for midbreast; 11.76 ± 0.58, 18.86 ± 1.06, and 24.82 ± 1.45 mGy, respectively, for breast; 12.19 ± 2.59, 19.09 ± 3.12, and 26.48 ± 5.0 mGy, respectively, for lung; and 0.37 ± 0.14, 0.69 ± 0.14, and 0.92 ± 0.2 mGy, respectively, for thyroid. Corresponding absorbed radiation doses for 75 bpm were 38.34 ± 2.02, 59.72 ± 3.13, and 77.8 ± 3.67 mGy for midbreast; 26.2 ± 1.74, 44 ± 1.11, and 52.84 ± 4.07 mGy for breast; 38.02 ± 1.58, 58.89 ± 1.68, and 78 ± 2.93 mGy for lung; and 0.79 ± 0.233, 1.04 ± 0.18, and 2.24 ± 0.52 mGy for thyroid. Absorbed radiation dose changes were significant for all organs for both tube voltage reductions as well as for HR control from 75 to 60 bpm at all tube voltage settings (p < 0.05). The absorbed radiation doses for the calcium score protocol were 11.2 ± 1.4 mGy for midbreast, 9.12 ± 0.48 mGy for breast, 10.36 ± 1.3 mGy for lung, and 0.4 ± 0.05 mGy for thyroid. CONCLUSION CT angiography with 320-MDCT scanners results in absorbed radiation doses in radiosensitive organs that compare favorably to those previously reported. Significant dose reductions can be achieved by tube

  19. Investigation of the Entrance Surface Dose and Dose to Different Organs in Lumbar Spine Imaging

    PubMed Central

    Sina, S; Zeinali, B; Karimipoorfard, M; Lotfalizadeh, F; Sadeghi, M; Zamani, E; Faghihi, R

    2014-01-01

    Background: Dose assessment using proper dosimeters is especially important in radiation protection optimization and imaging justification in diagnostic radiology. Objective: The aim of this study is to obtain the Entrance Skin Dose (ESD) of patients undergoing lumbar spine imaging using two thermoluminescence dosimeters TLD-100 (LiF: Mg, Ti) and GR-200 (LiF: Mg, Cu, P) and also to obtain the absorbed dose to different organs in lumbar spine imaging with several views. Methods: To measure the ESD values of the patients undergoing lumbar spine imaging, the two TLD types were put on their skin surface. The ESD values for different views of lumbar spine imaging were also measured by putting the TLDs at the surface of the Rando phantom. Several TLD chips were inserted inside different organs of Rando phantom to measure the absorbed dose to different organs in lumbar spine imaging. Results: The results indicate that there is a close agreement between the results of the two dosimeters. Based on the results of this experiment, the ESD dose of the 16 patients included in this study varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for GR-200 measurements. The ESDs obtained by putting the two types of TLDs at the surface of Rando phantom are in close agreement. Conclusion: According to the results, the GR200 has greater sensitivity than the TLD-100. PMID:25599058

  20. SU-E-J-11: Measurement of Eye Lens Dose for Varian On-Board Imaging with Different CBCT Acquisition Techniques

    SciTech Connect

    Deshpande, S; Dhote, D; Kumar, R; Thakur, K

    2015-06-15

    Purpose: To measure actual patient eye lens dose for different cone beam computed tomography (CBCT) acquisition protocol of Varian’s On Board Imagining (OBI) system using Optically Stimulated Luminescence (OSL) dosimeter and study the eye lens dose with patient geometry and distance of isocenter to the eye lens Methods: OSL dosimeter was used to measure eye lens dose of patient. OSL dosimeter was placed on patient forehead center during CBCT image acquisition to measure eye lens dose. For three different cone beam acquisition protocol (standard dose head, low dose head and high quality head) of Varian On-Board Imaging, eye lens doses were measured. Measured doses were correlated with patient geometry and distance between isocenter to eye lens. Results: Measured eye lens dose for standard dose head was in the range of 1.8 mGy to 3.2 mGy, for high quality head protocol dose was in range of 4.5mGy to 9.9 mGy whereas for low dose head was in the range of 0.3mGy to 0.7mGy. Dose to eye lens is depends upon position of isocenter. For posterioraly located tumor eye lens dose is less. Conclusion: From measured doses it can be concluded that by proper selection of imagining protocol and frequency of imaging, it is possible to restrict the eye lens dose below the new limit set by ICRP. However, undoubted advantages of imaging system should be counter balanced by careful consideration of imaging protocol especially for very intense imaging sequences for Adoptive Radiotherapy or IMRT.

  1. The Effects of Electron Radiation on the Glass Transition Temperature of a Polyetherimide.

    NASA Astrophysics Data System (ADS)

    Kern, Kristen Tulloch

    The effects of electron radiation on a polyetherimide (PEI), Ultem^{cdot}, were investigated. In particular, the changes in the glass transition temperature (T_{g} ) with absorbed radiation dose were studied. The polymer was exposed to mono-energetic beams of 100-keV electrons and 1.0-MeV electrons for doses up to 100 megagray (MGy). Dosimetry for the exposures was based on Monte -Carlo simulations of the transfer of energy from an energetic electron to the polymer and on comparison to Nylon standards. Dynamic mechanical analysis was used to determine the T _{g} for non-exposed PEI and the changes in T_{g} resulting from irradiation. The T_{g} did not change significantly for doses up to and including 75 MGy, while a significant increase in T_ {g} occurred for a dose of 100 MGy. The cross-link and chain scission densities in the irradiated PEI were determined using infrared spectroscopy. The cross -link density increased with dose for all doses investigated. The chain scission density increased with dose for doses up to 75 MGy, but was lower for a dose of 100 MGy than for a dose of 75 MGy. Radical population kinetics, based in part on data from an electron paramagnetic resonance study, were correlated with the cross-link density and chain scission density to investigate the mechanism for the observed density variations with dose. The radical population simulations suggest that chain scissioning occurs less readily when the average radical separation during the exposure is less than three molecular radii. Finally, a model for the combined effects of cross-linking and chain scissioning is proposed which combines a statistical-mechanical model for the change in T_{g} with cross-link density and a free-volume model for the change in T _{g} with chain scission density.

  2. Neuroimmune response and sleep studies after whole body irradiation with high-LET particles

    NASA Astrophysics Data System (ADS)

    Marquette, C.; Mathieu, J.; Bertho, J.-M.; Galonnier, M.; Wysoki, J.; Maubert, C.; Balanzat, E.; Gerbin, R.; Aigueperse, J.; Clarençon, D.

    2009-10-01

    In order to investigate the biological effects of galactic rays on astronaut cerebral functions after space flight, mice were exposed to different heavy ions (HZE) in whole-body conditions at doses comparable to the galactic flux: 12C, 16O and 20Ne (95 MeV/u, at 42-76 mGy). Animals were also exposed to 42 mGy of 60Co radiation for comparison with HZE. The neuroimmune response, evaluated by interleukin-1 (IL-1) measurement, showed that this cytokine was produced 3 h after irradiation by 16O or 60Co. In contrast, neither 12C (56.7 mGy) nor 20Ne (76 mGy) induced IL-1 production. However, immunohistochemical staining of 12C-irradiated mouse brain tissue showed 2 months later a marked inflammatory reaction in the hippocampus and a diffuse response in parenchyma. Sleep studies were realized before and after exposure to 42 mGy of 16O and 76 mGy of 20Ne: only the 20Ne radiation displayed a small effect. A slight decrease in paradoxical sleep, corresponding to a reduction in the number of episodes of paradoxical sleep, was manifested between 8 and 22 days after exposure. Exposure to 12C and 16O induced no changes either in cellularity of spleen or thymus, or in caspase 3 activity (as much as four months after irradiation). Taken together, these data indicate that the CNS could be sensitive to heavy ions and that responses to HZE impact depend on the nature of the particle, the dose threshold and the time delay to develop biological processes. Differences in responses to different HZE highlight the complex biological phenomena to which astronauts are submitted during space flight.

  3. The long-term effects of acute exposure to ionising radiation on survival and fertility in Daphnia magna.

    PubMed

    Sarapultseva, Elena I; Dubrova, Yuri E

    2016-10-01

    The results of recent studies have provided strong evidence for the transgenerational effects of parental exposure to ionising radiation and chemical mutagens. However, the transgenerational effects of parental exposure on survival and fertility remain poorly understood. To establish whether parental irradiation can affect the survival and fertility of directly exposed organisms and their offspring, crustacean Daphnia magna were given 10, 100, 1000 and 10,000mGy of acute γ-rays. Exposure to 1000 and 10,000mGy significantly compromised the viability of irradiated Daphnia and their first-generation progeny, but did not affect the second-generation progeny. The fertility of F0 and F1Daphnia gradually declined with the dose of parental exposure and significantly decreased at dose of 100mGy and at higher doses. The effects of parental irradiation on the number of broods were only observed among the F0Daphnia exposed to 1000 and 10,000mGy, whereas the brood size was equally affected in the two consecutive generations. In contrast, the F2 total fertility was compromised only among progeny of parents that received the highest dose of 10,000mGy. We propose that the decreased fertility observed among the F2 progeny of parents exposed to 10,000mGy is attributed to transgenerational effects of parental irradiation. Our results also indicate a substantial recovery of the F2 progeny of irradiated F0Daphnia exposed to the lower doses of acute γ-rays. PMID:27288911

  4. Image texture and radiation dose properties in CT.

    PubMed

    Mozejko, David; Kjernlie Andersen, Hilde; Pedersen, Marius; Waaler, Dag; Trægde Martinsen, Anne Catrine

    2016-01-01

    The aim of this study was to compare image noise properties of GE Discovery HD 750 and Toshiba Aquilion ONE. The uniformity section of a Catphan 600 image quality assurance phantom was scanned with both scanners, at different dose levels and with extension rings simulating patients of different sizes. 36 datasets were obtained and analyzed in terms of noise power spectrum. All the results prove that introduction of extension rings significantly altered the image quality with respect to noise properties. Without extension rings, the Toshiba scanner had lower total visible noise than GE (with GE as reference: FC18 had 82% and FC08 had 80% for 10 mGy, FC18 had 77% and FC08 74% for 15 mGy, FC18 had 80% and FC08 77% for 20 mGy). The total visible noise (TVN) for 20 and 15 mGy were similar for the phantom with the smallest additional extension ring, while Toshiba had higher TVN than GE for the 10 mGy dose level (120% FC18, 110% FC08). For the second and third ring, the GE images had lower TVN than Toshiba images for all dose levels (Toshiba TVN is greater than 155% for all cases). The results indi-cate that GE potentially has less image noise than Toshiba for larger patients. The Toshiba FC18 kernel had higher TVN than the Toshiba FC08 kernel with additional beam hardening correction for all dose levels and phantom sizes (120%, 107%, and 106% for FC18 compared to 110%, 98%, and 97%, for FC08, for 10, 15 and 20 mGy doses, respectively). PMID:27167260

  5. SU-E-I-09: Application of LiF:Mg,Cu (TLD-100H) Dosimeters for in Diagnostic Radiology

    SciTech Connect

    Sina, S; Zeinali, B; Karimipourfard, M; Lotfalizadeh, F; Sadeghi, M; Faghihi, R

    2014-06-01

    Purpose: Accurate dosimetery is very essential in diagnostic radiology. The goal of this study is to verify the application of LiF:Mg,Cu,P (TLD100H) in obtaining the Entrance skin dose (ESD) of patients undergoing diagnostic radiology. The results of dosimetry performed by TLD-100H, were compared with those obtained by TLD100, which is a common dosimeter in diagnostic radiology. Methods: In this study the ESD values were measured using two types of Thermoluminescence dosimeters (TLD-100, and TLD-100H) for 16 patients undergoing diagnostic radiology (lumbar spine imaging). The ESD values were also obtained by putting the two types of TLDs at the surface of Rando phantom for different imaging techniques and different views (AP, and lateral). The TLD chips were annealed with a standard procedure, and the ECC values for each TLD was obtained by exposing the chips to equal amount of radiation. Each time three TLD chips were covered by thin dark plastic covers, and were put at the surface of the phantom or the patient. The average reading of the three chips was used for obtaining the dose. Results: The results show a close agreement between the dose measuered by the two dosimeters.According to the results of this study, the TLD-100H dosimeters have higher sensitivities (i.e.signal(nc)/dose) than TLD-100.The ESD values varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for measurements. Conclusion: The TLD-100H dosimeters are suggested as effective dosimeters for dosimetry in low dose fields because of their higher sensitivities.

  6. Assessment of DNA double-strand breaks induced by intravascular iodinated contrast media following in vitro irradiation and in vivo, during paediatric cardiac catheterization.

    PubMed

    Gould, Richard; McFadden, Sonyia L; Horn, Simon; Prise, Kevin M; Doyle, Philip; Hughes, Ciara M

    2016-01-01

    Paediatric cardiac catheterizations may result in the administration of substantial amounts of iodinated contrast media and ionizing radiation. The aim of this work was to investigate the effect of iodinated contrast media in combination with in vitro and in vivo X-ray radiation on lymphocyte DNA. Six concentrations of iodine (15, 17.5, 30, 35, 45, and 52.5 mg of iodine per mL blood) represented volumes of iodinated contrast media used in the clinical setting. Blood obtained from healthy volunteers was mixed with iodinated contrast media and exposed to radiation doses commonly used in paediatric cardiac catheterizations (0 mGy, 70 mGy, 140 mGy, 250 mGy and 450 mGy). Control samples contained no iodine. For in vivo experimentation, pre and post blood samples were collected from children undergoing cardiac catheterization, receiving iodine concentrations of up to 51 mg of iodine per mL blood and radiation doses of up to 400 mGy. Fluorescence microscopy was performed to assess γH2AX-foci induction, which corresponded to the number of DNA double-strand breaks. The presence of iodine in vitro resulted in significant increases of DNA double-strand breaks beyond that induced by radiation for ≥ 17.5 mg/mL iodine to blood. The in vivo effects of contrast media on children undergoing cardiac catheterization resulted in a 19% increase in DNA double-strand breaks in children receiving an average concentration of 19 mg/mL iodine to blood. A larger investigation is required to provide further information of the potential benefit of lowering the amount of iodinated contrast media received during X-ray radiation investigations. PMID:26549792

  7. Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure

    SciTech Connect

    Maier, Joscha; Sawall, Stefan; Kachelrieß, Marc

    2014-05-15

    Purpose: Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levels from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Methods: Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Results: Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the

  8. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study.

    PubMed

    Sabarudin, Akmal; Mustafa, Zakira; Nassir, Khadijah Mohd; Hamid, Hamzaini Abdul; Sun, Zhonghua

    2015-01-01

    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50 ± 0.29 mSv for thoracic and 6.01 ± 0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07 ± 0.24 mSv and 17.30 ± 0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18 ± 0.48 mGy and 11.96 ± 0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56 ± 0.43 mGy and 33.23 ± 0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58 ± 0.12 mGy in the TCM protocols and 51.52 ± 14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30 ± 1.28mGy and 29.99 ± 2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT. PMID:25679153

  9. Diagnostic Accuracy of CT Enterography for Active Inflammatory Terminal Ileal Crohn Disease: Comparison of Full-Dose and Half-Dose Images Reconstructed with FBP and Half-Dose Images with SAFIRE.

    PubMed

    Gandhi, Namita S; Baker, Mark E; Goenka, Ajit H; Bullen, Jennifer A; Obuchowski, Nancy A; Remer, Erick M; Coppa, Christopher P; Einstein, David; Feldman, Myra K; Kanmaniraja, Devaraju; Purysko, Andrei S; Vahdat, Noushin; Primak, Andrew N; Karim, Wadih; Herts, Brian R

    2016-08-01

    Purpose To compare the diagnostic accuracy and image quality of computed tomographic (CT) enterographic images obtained at half dose and reconstructed with filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with those of full-dose CT enterographic images reconstructed with FBP for active inflammatory terminal or neoterminal ileal Crohn disease. Materials and Methods This retrospective study was compliant with HIPAA and approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety subjects (45 with active terminal ileal Crohn disease and 45 without Crohn disease) underwent CT enterography with a dual-source CT unit. The reference standard for confirmation of active Crohn disease was active terminal ileal Crohn disease based on ileocolonoscopy or established Crohn disease and imaging features of active terminal ileal Crohn disease. Data from both tubes were reconstructed with FBP (100% exposure); data from the primary tube (50% exposure) were reconstructed with FBP and SAFIRE strengths 3 and 4, yielding four datasets per CT enterographic examination. The mean volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) at full dose were 13.1 mGy (median, 7.36 mGy) and 15.9 mGy (median, 13.06 mGy), respectively, and those at half dose were 6.55 mGy (median, 3.68 mGy) and 7.95 mGy (median, 6.5 mGy). Images were subjectively evaluated by eight radiologists for quality and diagnostic confidence for Crohn disease. Areas under the receiver operating characteristic curves (AUCs) were estimated, and the multireader, multicase analysis of variance method was used to compare reconstruction methods on the basis of a noninferiority margin of 0.05. Results The mean AUCs with half-dose scans (FBP, 0.908; SAFIRE 3, 0.935; SAFIRE 4, 0.924) were noninferior to the mean AUC with full-dose FBP scans (0.908; P < .003). The proportion of images with inferior quality was significantly higher with all

  10. SU-E-I-32: Benchmarking Head CT Doses: A Pooled Vs. Protocol Specific Analysis of Radiation Doses in Adult Head CT Examinations

    SciTech Connect

    Fujii, K; Bostani, M; Cagnon, C; McNitt-Gray, M

    2015-06-15

    Purpose: The aim of this study was to collect CT dose index data from adult head exams to establish benchmarks based on either: (a) values pooled from all head exams or (b) values for specific protocols. One part of this was to investigate differences in scan frequency and CT dose index data for inpatients versus outpatients. Methods: We collected CT dose index data (CTDIvol) from adult head CT examinations performed at our medical facilities from Jan 1st to Dec 31th, 2014. Four of these scanners were used for inpatients, the other five were used for outpatients. All scanners used Tube Current Modulation. We used X-ray dose management software to mine dose index data and evaluate CTDIvol for 15807 inpatients and 4263 outpatients undergoing Routine Brain, Sinus, Facial/Mandible, Temporal Bone, CTA Brain and CTA Brain-Neck protocols, and combined across all protocols. Results: For inpatients, Routine Brain series represented 84% of total scans performed. For outpatients, Sinus scans represented the largest fraction (36%). The CTDIvol (mean ± SD) across all head protocols was 39 ± 30 mGy (min-max: 3.3–540 mGy). The CTDIvol for Routine Brain was 51 ± 6.2 mGy (min-max: 36–84 mGy). The values for Sinus were 24 ± 3.2 mGy (min-max: 13–44 mGy) and for Facial/Mandible were 22 ± 4.3 mGy (min-max: 14–46 mGy). The mean CTDIvol for inpatients and outpatients was similar across protocols with one exception (CTA Brain-Neck). Conclusion: There is substantial dose variation when results from all protocols are pooled together; this is primarily a function of the differences in technical factors of the protocols themselves. When protocols are analyzed separately, there is much less variability. While analyzing pooled data affords some utility, reviewing protocols segregated by clinical indication provides greater opportunity for optimization and establishing useful benchmarks.

  11. Perspective: Materials informatics and big data: Realization of the "fourth paradigm" of science in materials science

    NASA Astrophysics Data System (ADS)

    Agrawal, Ankit; Choudhary, Alok

    2016-05-01

    Our ability to collect "big data" has greatly surpassed our capability to analyze it, underscoring the emergence of the fourth paradigm of science, which is data-driven discovery. The need for data informatics is also emphasized by the Materials Genome Initiative (MGI), further boosting the emerging field of materials informatics. In this article, we look at how data-driven techniques are playing a big role in deciphering processing-structure-property-performance relationships in materials, with illustrative examples of both forward models (property prediction) and inverse models (materials discovery). Such analytics can significantly reduce time-to-insight and accelerate cost-effective materials discovery, which is the goal of MGI.

  12. Summary of round robin measurements of radiation induced conductivity in Wesgo AL995 alumina

    SciTech Connect

    Zinkle, S.J.

    1996-10-01

    This existing data on radiation induced conductivity (RIC) measurements performed on the same heat of the IEA reference ceramic insulator are summarized. Six different sets of RIC measurements have been performed on Wesgo AL995 at dose rates between 10 Gy/s and 1 MGy/s. In general, good agreement was obtained between the different groups of researchers. The data indicate that the RIC at a test temperature of 400-500{degrees}C is approximately linear with ionizing dose rate up to {approximately}1000 Gy/s, and exhibits an approximately square root dependence on dose rate between 1 kGy/s and 1 MGy/s.

  13. SU-E-P-08: Establishment of Local Diagnostic Reference Levels of Routine Abdomen Exam in Computed Tomography According to Body Weight

    SciTech Connect

    Wang, H; Wang, Y; Weng, H

    2015-06-15

    Purpose: The national diagnostic reference levels (NDRLs) is an efficient, concise and powerful standard for optimizing radiation protection of a patient. However, for each hospital the dose-reducing potential of focusing on establishment of local DRLs (LDRLs). A lot of study reported that Computed tomography exam contributed majority radiation dose in different medical modalities, therefore, routine abdomen CT exam was choose in initial pilot study in our study. Besides the mAs of routine abdomen CT exam was decided automatic exposure control by linear attenuation is relate to body shape of patient. In this study we would like to establish the local diagnostic reference levels of routine abdomen exam in computed tomography according to body weight of patient. Methods and Materials: There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). The patient sample involved 82 adult patients of both sexes and divided into three groups by their body weight (50–60 kg, 60–70 kg, 70–80 kg).Carried out the routine abdomen examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined. The average values were compared with the European DRLs. Results: The majority of patients (75%) were between 50–70 Kg of body weight, the numbers of patient in each group of weight were 40–50:7; 50–60:29; 60–70:33; 70–80:13. The LDRLs in each group were 10.81mGy, 14.46mGy, 20.27mGy and 21.04mGy, respectively. The DLP were 477mGy, 630mGy, 887mGy and 959mGy, respectively. No matter which group the LDRLs were lower than European DRLs. Conclusions: We would like to state that this was a pioneer work in local hospital in Chiayi. We hope that this may lead the way to further developments in Taiwan.

  14. Nonlinear ionizing radiation-induced changes in eye lens cell proliferation, cyclin D1 expression and lens shape

    PubMed Central

    Markiewicz, Ewa; Barnard, Stephen; Haines, Jackie; Coster, Margaret; van Geel, Orry; Wu, Weiju; Richards, Shane; Ainsbury, Elizabeth; Rothkamm, Kai; Bouffler, Simon; Quinlan, Roy A.

    2015-01-01

    Elevated cataract risk after radiation exposure was established soon after the discovery of X-rays in 1895. Today, increased cataract incidence among medical imaging practitioners and after nuclear incidents has highlighted how little is still understood about the biological responses of the lens to low-dose ionizing radiation (IR). Here, we show for the first time that in mice, lens epithelial cells (LECs) in the peripheral region repair DNA double strand breaks (DSB) after exposure to 20 and 100 mGy more slowly compared with circulating blood lymphocytes, as demonstrated by counts of γH2AX foci in cell nuclei. LECs in the central region repaired DSBs faster than either LECs in the lens periphery or lymphocytes. Although DSB markers (γH2AX, 53BP1 and RAD51) in both lens regions showed linear dose responses at the 1 h timepoint, nonlinear responses were observed in lenses for EdU (5-ethynyl-2′-deoxy-uridine) incorporation, cyclin D1 staining and cell density after 24 h at 100 and 250 mGy. After 10 months, the lens aspect ratio was also altered, an indicator of the consequences of the altered cell proliferation and cell density changes. A best-fit model demonstrated a dose-response peak at 500 mGy. These data identify specific nonlinear biological responses to low (less than 1000 mGy) dose IR-induced DNA damage in the lens epithelium. PMID:25924630

  15. Electron probe X-ray microanalysis of boar and inobuta testes after the Fukushima accident.

    PubMed

    Yamashiro, Hideaki; Abe, Yasuyuki; Hayashi, Gohei; Urushihara, Yusuke; Kuwahara, Yoshikazu; Suzuki, Masatoshi; Kobayashi, Jin; Kino, Yasuyuki; Fukuda, Tomokazu; Tong, Bin; Takino, Sachio; Sugano, Yukou; Sugimura, Satoshi; Yamada, Takahisa; Isogai, Emiko; Fukumoto, Manabu

    2015-12-01

    We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Power Plant (FNPP) accident on the testes of boar and inobuta (a hybrid of Sus scrofa and Sus scrofa domestica). This study examined the contamination levels of radioactive caesium (Cs), especially (134)Cs and (137)Cs, in the testis of both boar and inobuta during 2012, after the Fukushima accident. Morphological analysis and electron-probe X-ray microanalysis (EPMA) were also undertaken on the testes. The (134)Cs and (137)Cs levels were 6430 ± 23 and 6820 ± 32 Bq/kg in the boar testes, and 755 ± 13 and 747 ± 17 Bq/kg in the inobuta testes, respectively. The internal and external exposure of total (134)Cs and (137)Cs in the boar testes were 47.1 mGy and 176.2 mGy, respectively, whereas in the inobuta testes, these levels were 6.09 mGy and 59.8 mGy, respectively. Defective spermatogenesis was not detected by the histochemical analysis of radiation-exposed testes for either animal. In neither animal were Cs molecules detected, using EPMA. In conclusion, we showed that adverse radiation-induced effects were not detected in the examined boar and inobuta testes following the chronic radiation exposure associated with the FNPP accident. PMID:26825300

  16. Nonlinear ionizing radiation-induced changes in eye lens cell proliferation, cyclin D1 expression and lens shape.

    PubMed

    Markiewicz, Ewa; Barnard, Stephen; Haines, Jackie; Coster, Margaret; van Geel, Orry; Wu, Weiju; Richards, Shane; Ainsbury, Elizabeth; Rothkamm, Kai; Bouffler, Simon; Quinlan, Roy A

    2015-04-01

    Elevated cataract risk after radiation exposure was established soon after the discovery of X-rays in 1895. Today, increased cataract incidence among medical imaging practitioners and after nuclear incidents has highlighted how little is still understood about the biological responses of the lens to low-dose ionizing radiation (IR). Here, we show for the first time that in mice, lens epithelial cells (LECs) in the peripheral region repair DNA double strand breaks (DSB) after exposure to 20 and 100 mGy more slowly compared with circulating blood lymphocytes, as demonstrated by counts of γH2AX foci in cell nuclei. LECs in the central region repaired DSBs faster than either LECs in the lens periphery or lymphocytes. Although DSB markers (γH2AX, 53BP1 and RAD51) in both lens regions showed linear dose responses at the 1 h timepoint, nonlinear responses were observed in lenses for EdU (5-ethynyl-2'-deoxy-uridine) incorporation, cyclin D1 staining and cell density after 24 h at 100 and 250 mGy. After 10 months, the lens aspect ratio was also altered, an indicator of the consequences of the altered cell proliferation and cell density changes. A best-fit model demonstrated a dose-response peak at 500 mGy. These data identify specific nonlinear biological responses to low (less than 1000 mGy) dose IR-induced DNA damage in the lens epithelium. PMID:25924630

  17. An investigation on patient dose in screen-film diagnostic radiology in Lhasa City, Xizang Autonomous Region, China.

    PubMed

    Du, Xiang

    2013-12-01

    This study aimed to investigate patient dose in diagnostic screen-film radiographic examinations in the city of Lhasa, China. Seven out of the twenty-six hospitals registered with the Lhasa Health Bureau were included in the investigation. The entrance surface air Kerma (ESAK) of seven conventional screen-film radiology X-ray equipment in these hospitals was measured with a QA dosimeter in September 2012. The X-ray examinations were divided into three categories: PA (posterior-anterior) chest, upper/lower limb, and AP (anterior-posterior) lumbar spine. For each category, ESAKs were calculated and analyzed. The mean ESAK was 0.6 mGy for PA chest, 0.3 mGy for upper/lower limb, and 1.8 mGy for AP lumbar spine. In addition, the mean ESAK value recorded for PA chest X-ray examinations exceeded the corresponding value recommended by the International Atomic Energy Agency (0.4 mGy). PMID:24142378

  18. Radiation exposure in body computed tomography examinations of trauma patients

    NASA Astrophysics Data System (ADS)

    Kortesniemi, M.; Kiljunen, T.; Kangasmäki, A.

    2006-06-01

    Multi-slice CT provides an efficient imaging modality for trauma imaging. The purpose of this study was to provide absorbed and effective dose data from CT taking into account the patient size and compare such doses with the standard CT dose quantities based on standard geometry. The CT examination data from abdominal and thoracic scan series were collected from 36 trauma patients. The CTDIvol, DLPw and effective dose were determined, and the influence of patient size was applied as a correction factor to calculated doses. The patient size was estimated from the patient weight as the effective radius based on the analysis from the axial images of abdominal and thoracic regions. The calculated mean CTDIvol, DLPw and effective dose were 15.2 mGy, 431 mGy cm and 6.5 mSv for the thorax scan, and 18.5 mGy, 893 mGy cm and 14.8 mSv for the abdomen scan, respectively. The doses in the thorax and abdomen scans taking the patient size into account were 34% and 9% larger than the standard dose quantities, respectively. The use of patient size in dose estimation is recommended in order to provide realistic data for evaluation of the radiation exposure in CT, especially for paediatric patients and smaller adults.

  19. Dosimetric measurements and comparison studies in digital imaging system

    NASA Astrophysics Data System (ADS)

    Jung, Ji-Young; Kim, Hee-Joung; Lee, Chang-Lae; Cho, Hyo-Min; Nam, Sora

    2008-03-01

    Number of radiologic exams using digital imaging systems has rapidly increased with advanced imaging technologies. However, it has not been paid attention to the radiation dose in clinical situations. It was the motivation to study radiation dosimetry in the DR system. The objective of this study was to measure beam quality and patient's dose using DR system and to compare them to both IEC standard and IAEA guidelines. The measured average dose for chest and abdomen was 1.376 mGy and 9.501 mGy, respectively, compared to 0.4 mGy and 10.0 mGy in IAEA guidelines. The results also indicated that the DR system has a lower radiation beam quality than that of the IEC standard. The results showed that the patients may be exposed higher radiation for chest exams and lower radiation for abdomen exams using DR system. IAEA Guidelines were prepared based on western people which may be different weight and height for patients compared them to Korean. In conclusion, a new guideline for acceptable DR dosimetry for Korean patients may need to be developed with further studies for large populations. We believe that this research greatly help to introduce the importance of the dosimetry in diagnostic radiology in Korea. And, a development of database for dosimetry in diagnostic radiology will become an opportunity of making aware of radiation safety of medical examination to patient.

  20. The rate of X-ray-induced DNA double-strand break repair in the embryonic mouse brain is unaffected by exposure to 50 Hz magnetic fields

    PubMed Central

    Woodbine, Lisa; Haines, Jackie; Coster, Margaret; Barazzuol, Lara; Ainsbury, Elizabeth; Sienkiewicz, Zenon; Jeggo, Penny

    2015-01-01

    Abstract Purpose: Following in utero exposure to low dose radiation (10–200 mGy), we recently observed a linear induction of DNA double-strand breaks (DSB) and activation of apoptosis in the embryonic neuronal stem/progenitor cell compartment. No significant induction of DSB or apoptosis was observed following exposure to magnetic fields (MF). In the present study, we exploited this in vivo system to examine whether exposure to MF before and after exposure to 100 mGy X-rays impacts upon DSB repair rates. Materials and methods: 53BP1 foci were quantified following combined exposure to radiation and MF in the embryonic neuronal stem/progenitor cell compartment. Embryos were exposed in utero to 50 Hz MF at 300 μT for 3 h before and up to 9 h after exposure to 100 mGy X-rays. Controls included embryos exposed to MF or X-rays alone plus sham exposures. Results: Exposure to MF before and after 100 mGy X-rays did not impact upon the rate of DSB repair in the embryonic neuronal stem cell compartment compared to repair rates following radiation exposure alone. Conclusions: We conclude that in this sensitive system MF do not exert any significant level of DNA damage and do not impede the repair of X-ray induced damage. PMID:25786477

  1. Estimates of Average Glandular Dose with Auto-modes of X-ray Exposures in Digital Breast Tomosynthesis

    PubMed Central

    Kamal, Izdihar; Chelliah, Kanaga K.; Mustafa, Nawal

    2015-01-01

    Objectives: The aim of this research was to examine the average glandular dose (AGD) of radiation among different breast compositions of glandular and adipose tissue with auto-modes of exposure factor selection in digital breast tomosynthesis. Methods: This experimental study was carried out in the National Cancer Society, Kuala Lumpur, Malaysia, between February 2012 and February 2013 using a tomosynthesis digital mammography X-ray machine. The entrance surface air kerma and the half-value layer were determined using a 100H thermoluminescent dosimeter on 50% glandular and 50% adipose tissue (50/50) and 20% glandular and 80% adipose tissue (20/80) commercially available breast phantoms (Computerized Imaging Reference Systems, Inc., Norfolk, Virginia, USA) with auto-time, auto-filter and auto-kilovolt modes. Results: The lowest AGD for the 20/80 phantom with auto-time was 2.28 milliGray (mGy) for two dimension (2D) and 2.48 mGy for three dimensional (3D) images. The lowest AGD for the 50/50 phantom with auto-time was 0.97 mGy for 2D and 1.0 mGy for 3D. Conclusion: The AGD values for both phantoms were lower against a high kilovolt peak and the use of auto-filter mode was more practical for quick acquisition while limiting the probability of operator error. PMID:26052465

  2. Electron probe X-ray microanalysis of boar and inobuta testes after the Fukushima accident

    PubMed Central

    Yamashiro, Hideaki; Abe, Yasuyuki; Hayashi, Gohei; Urushihara, Yusuke; Kuwahara, Yoshikazu; Suzuki, Masatoshi; Kobayashi, Jin; Kino, Yasuyuki; Fukuda, Tomokazu; Tong, Bin; Takino, Sachio; Sugano, Yukou; Sugimura, Satoshi; Yamada, Takahisa; Isogai, Emiko; Fukumoto, Manabu

    2015-01-01

    We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Power Plant (FNPP) accident on the testes of boar and inobuta (a hybrid of Sus scrofa and Sus scrofa domestica). This study examined the contamination levels of radioactive caesium (Cs), especially 134Cs and 137Cs, in the testis of both boar and inobuta during 2012, after the Fukushima accident. Morphological analysis and electron-probe X-ray microanalysis (EPMA) were also undertaken on the testes. The 134Cs and 137Cs levels were 6430 ± 23 and 6820 ± 32 Bq/kg in the boar testes, and 755 ± 13 and 747 ± 17 Bq/kg in the inobuta testes, respectively. The internal and external exposure of total 134Cs and 137Cs in the boar testes were 47.1 mGy and 176.2 mGy, respectively, whereas in the inobuta testes, these levels were 6.09 mGy and 59.8 mGy, respectively. Defective spermatogenesis was not detected by the histochemical analysis of radiation-exposed testes for either animal. In neither animal were Cs molecules detected, using EPMA. In conclusion, we showed that adverse radiation-induced effects were not detected in the examined boar and inobuta testes following the chronic radiation exposure associated with the FNPP accident. PMID:26825300

  3. A case report of image-based dosimetry of bone metastases with Alpharadin ((223)Ra-dichloride) therapy: inter-fraction variability of absorbed dose and follow-up.

    PubMed

    Pacilio, Massimiliano; Ventroni, Guido; Cassano, Bartolomeo; Ialongo, Pasquale; Lorenzon, Leda; Di Castro, Elisabetta; Recine, Federica; Sternberg, Cora N; Mango, Lucio

    2016-02-01

    A 70-year-old man affected by bone metastases from castration resistant prostate cancer underwent Alpharadin ((223)Ra-dichloride) therapy (6 administrations of 50 kBq per kg i.v., once every 4 weeks). The inter-fraction variability of the absorbed dose to lesions was evaluated for four injections. Dosimetric assessments were performed following the MIRD approach and a recently published methodology. The mean absorbed dose and standard deviation for 4 lesions [mean (σ %)] were: 434 mGy (15%) and 516 mGy (21%) for the right and left humeral head, 1205 mGy (14%) and 781 mGy (8%) for the right and left glenoid. The estimated total absorbed dose after the whole treatment, considering also the relative-biological effectiveness of alpha particles (RBE = 5), yielded a D RBE range of 13-36 Gy. A good correlation between (99m)Tc and (223)Ra uptake was obtained (R (2) = 0.7613). The tumour-non-tumour (TNT) ratio of 8 lesions (those above, plus 4 additional), monitored by six (99m)Tc-MDP bone scans over a period of about 10 months, evidenced a TNT reduction in two lesions (-42 and -48 %), but in most lesions the TNT remained fairly constant, evidencing that (223)Ra-dichloride therapy tends to prevent further progression of osseous disease, leading to chronicity of the metastatic status. PMID:26613714

  4. Pediatric Computed Tomography. Radiation Dose in Abdominal Studies

    NASA Astrophysics Data System (ADS)

    López, X.; Ruiz-Trejo, C.; Buenfil, A. E.; Gamboa-deBuen, I.; Dies, P.

    2008-08-01

    Computed tomography is one of the most popular medical imaging modalities used in the last years. However, because is one of the techniques that delivered a considerable radiation dose, precautions should be taken into account. Pediatric patients are more radiosensitive than adults, and the probability that no desirable biological effects can occur is greater. To this, also it adds the probability that they will need more radiological studies in the future. The work consisted in determining the received dose by the pediatric patients undergoing abdominal studies in a multislice computed tomograph, according to the dosimetric quantities established by a Code of Practice published by the International Atomic Energy Agency; using a ionization chamber and a phantom that simulates the abdomen of a pediatric patient. The weighted air kerma index (Cw) was 14.3±0.4 mGy, this value is lower than the published by the American College of Radiology, 25 mGy. The multiple scan average dose (MSAD), which is a quantity established by the NOM-229-SSA1-2002 was determined, finding a value of 14.2±0.1 mGy, it is also below the value established, 25 mGy for an adult study.

  5. Chernobyl's Subclinical Legacy: Prenatal Exposure to Radioactive Fallout and School Outcomes in Sweden. NBER Working Paper No. 13347

    ERIC Educational Resources Information Center

    Almond, Douglas; Edlund, Lena; Palme, Marten

    2007-01-01

    Japanese atomic bomb survivors irradiated 8-25 weeks after ovulation subsequently suffered reduced IQ [Otake and Schull, 1998]. Whether these findings generalize to low doses (less than 10 mGy) has not been established. This paper exploits the natural experiment generated by the Chernobyl nuclear accident in April 1986, which caused a spike in…

  6. Establishment of diagnostic reference levels for dental panoramic radiography in Greece.

    PubMed

    Manousaridis, G; Koukorava, C; Hourdakis, C J; Kamenopoulou, V; Yakoumakis, E; Tsiklakis, K

    2015-07-01

    The purpose of the present study was to present the national diagnostic reference levels (DRL) established for panoramic dental examinations in Greece. The establishment of DRL, as a tool for the optimisation of radiological procedures, is a requirement of national regulations. Measurements performed by the Greek Atomic Energy Commission on 90 panoramic systems have been used for the derivation of DRL values. DRL values have been proposed for exposure settings of different patient types (child, small adult and standard adult), both for film and digital imaging. The DRLs for different patient types are grouped in three categories: children, small adults (corresponding to female) and average adults (corresponding to male). Proposed DRLs for these groups are 2.2, 3.3 and 4.1 mGy, respectively. In order to investigate the correlation of DRLs with the available imaging modalities (CR, DR and film), this parameter was taken into account. DR imaging DRL is the lowest at 3.5 mGy, CR imaging the highest at 4.2 mGy and film imaging at 3.7 mGy. In order to facilitate comparison with other studies, kerma-width product values were calculated from Ki, air and field size. PMID:25836684

  7. Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D

    SciTech Connect

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Jernigan, T. J.; Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; Wesley, J. C.; Lasnier, C. J.; Pitts, R. A.; Sugihara, M.; Watkins, J.

    2013-06-15

    Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

  8. SU-E-I-15: Comparison of Radiation Dose for Radiography and EOS in Adolescent Scoliosis Patients

    SciTech Connect

    Schueler, B; Walz-Flannigan, A

    2014-06-01

    Purpose: To estimate patient radiation dose for whole spine imaging using EOS, a new biplanar slot-scanning radiographic system and compare with standard scoliosis radiography. Methods: The EOS imaging system (EOS Imaging, Paris, France) consists of two orthogonal x-ray fan beams which simultaneously acquire frontal and lateral projection images of a standing patient. The patient entrance skin air kerma was measured for each projection image using manufacturer-recommended exposure parameters for spine imaging. Organ and effective doses were estimated using a commercially-available Monte Carlo simulation program (PCXMC, STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland) for a 15 year old mathematical phantom model. These results were compared to organ and effective dose estimated for scoliosis radiography using computed radiography (CR) with standard exposure parameters obtained from a survey of pediatric radiographic projections. Results: The entrance skin air kerma for EOS was found to be 0.18 mGy and 0.33 mGy for posterior-anterior (PA) and lateral projections, respectively. This compares to 0.76 mGy and 1.4 mGy for CR, PA and lateral projections. Effective dose for EOS (PA and lateral projections combined) is 0.19 mSv compared to 0.51 mSv for CR. Conclusion: The EOS slot-scanning radiographic system allows for reduced patient radiation dose in scoliosis patients as compared to standard CR radiography.

  9. Characterization of amorphous thermoluminescence dosimeters for patient dose measurement in X-ray diagnostic procedures

    NASA Astrophysics Data System (ADS)

    Ramli, N. N. H.; Salleh, H.; Mahdiraji, G. A.; Zulkifli, M. I.; Hashim, S.; Bradley, D. A.; M. Noor, N.

    2015-11-01

    We investigate the use of novel Ge-doped amorphous silica flat fibers as thermoluminescence dosimeters (TLDs) in verifying patient entrance surface-dose (ESD) in diagnostic examinations. Selected fibers with established dosimetric characteristics (including energy dependence, linearity, reproducibility, and fading) were loaded into plastic capsules in groups of six. The fibers have been calibrated against a parallel plate ionization chamber, use being made of x-rays generated at 70 kVp, accessing a Secondary Standards Dosimetry Laboratory (SSDL) facility. The fiber characterization measurements were made using a Toshiba X-ray machine operating within the nominal energies range 40 kVp to 150 kVp, for doses in the range 0.02 mGy up to 3 mGy. For doses from 2 mGy up to 150 mGy, the flat fibers exhibit linearity between TL yield and dose, reproducible to better than 3% standard deviation following repeat measurements (n=3). A marked energy-dependent response is observed for photons generated at potentials from 40 kVp to 150 kVp. From present results, it is concluded that Ge-doped fibers represent a viable system for use in diagnostic dosimetry, corrections being made for the various factors influencing TL yield.

  10. Evaluation of organ doses in CT examinations with an infant anthropomorphic phantom.

    PubMed

    Fujii, K; Akahane, K; Miyazaki, O; Horiuchi, T; Shimada, A; Nagmatsu, H; Yamauchi, M; Yamauchi-Kawaura, C; Kawasaki, T

    2011-09-01

    The aim of this study is to evaluate organ doses in infant CT examinations with multi-detector row CT scanners. Radiation doses were measured with radiophotoluminescence glass dosemeters set in various organ positions within a 1-y-old child anthropomorphic phantom and organ doses were evaluated from the measurement values. Doses for tissues or organs within the scan range were 28-36 mGy in an infant head CT, 3-11 mGy in a chest CT, 5-11 mGy in an abdominal-pelvic CT and 2-14 mGy in a cardiac CT. The doses varied by the differences in the types of CT scanners and scan parameters used at each medical facility. Compared with those for children of various ages, the doses in an infant CT protocol were found to be similar to or slightly smaller than those in a paediatric CT for 5- or 6-y-old children. PMID:21743079

  11. Biodistribution and Radiation Dosimetry for a Probe Targeting Prostate-Specific Membrane Antigen for Imaging and Therapy

    PubMed Central

    Herrmann, Ken; Bluemel, Christina; Weineisen, Martina; Schottelius, Margret; Wester, Hans-Jürgen; Czernin, Johannes; Eberlein, Uta; Beykan, Seval; Lapa, Constantin; Riedmiller, Hubertus; Krebs, Markus; Kropf, Saskia; Schirbel, Andreas; Buck, Andreas K.; Lassmann, Michael

    2016-01-01

    Prostate-specific membrane antigen (PSMA) is a promising target for diagnosis and treatment of prostate cancer. EuK-Subkff-68Ga-DOTAGA (68Ga-PSMA Imaging & Therapy [PSMA I&T]) is a recently introduced PET tracer for imaging PSMA expression in vivo. Whole-body distribution and radiation dosimetry of this new probe were evaluated. Methods Five patients with a history of prostate cancer were injected intravenously with 91–148 MBq of 68Ga-PSMA I&T (mean ± SD, 128 ± 23 MBq). After an initial series of rapid whole-body scans, 3 static whole-body scans were acquired at 1, 2, and 4 h after tracer injection. Time-dependent changes of the injected activity per organ were determined. Mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM. Results Injection of 150 MBq of 68Ga-PSMA I&T resulted in an effective dose of 3.0 mSv. The kidneys were the critical organ (33 mGy), followed by the urinary bladder wall and spleen (10 mGy each), salivary glands (9 mGy each), and liver (7 mGy). Conclusion 68Ga-PSMA I&T exhibits a favorable dosimetry, delivering organ doses that are comparable to (kidneys) or lower than those delivered by 18F-FDG. PMID:25883128

  12. ESR dosimetry study of population in the vicinity of the Semipalatinsk Nuclear Test Site

    PubMed Central

    Zhumadilov, Kassym; Ivannikov, Alexander; Stepanenko, Valeriy; Zharlyganova, Dinara; Toyoda, Shin; Zhumadilov, Zhaxybay; Hoshi, Masaharu

    2013-01-01

    A tooth enamel electron spin resonance (ESR) dosimetry study was carried out with the purpose of obtaining the individual absorbed radiation doses of population from settlements in the Semipalatinsk region of Kazakhstan, which was exposed to radioactive fallout traces from nuclear explosions in the Semipalatinsk Nuclear Test Site and Lop Nor test base, China. Most of the settlements are located near the central axis of radioactive fallout trace from the most contaminating surface nuclear test, which was conducted on 29 August 1949, with the maximum detected excess dose being 430 ± 93 mGy. A maximum dose of 268 ± 79 mGy was determined from the settlements located close to radioactive fallout trace resulting from surface nuclear tests on 24 August 1956 (Ust-Kamenogorsk, Znamenka, Shemonaikha, Glubokoe, Tavriya and Gagarino). An accidental dose of 56 ± 42 mGy was found in Kurchatov city residents located close to fallout trace after the nuclear test on 7 August 1962. This method was applied to human tooth enamel to obtain individual absorbed doses of residents of the Makanchi, Urdzhar and Taskesken settlements located near the Kazakhstan–Chinese border due to the influence of nuclear tests (1964–1981) at Lop Nor. The highest dose was 123 ± 32 mGy. PMID:23404205

  13. Pediatric Computed Tomography. Radiation Dose in Abdominal Studies

    SciTech Connect

    Lopez, X.; Ruiz-Trejo, C.; Buenfil, A. E.; Gamboa-deBuen, I.; Dies, P

    2008-08-11

    Computed tomography is one of the most popular medical imaging modalities used in the last years. However, because is one of the techniques that delivered a considerable radiation dose, precautions should be taken into account. Pediatric patients are more radiosensitive than adults, and the probability that no desirable biological effects can occur is greater. To this, also it adds the probability that they will need more radiological studies in the future. The work consisted in determining the received dose by the pediatric patients undergoing abdominal studies in a multislice computed tomograph, according to the dosimetric quantities established by a Code of Practice published by the International Atomic Energy Agency; using a ionization chamber and a phantom that simulates the abdomen of a pediatric patient. The weighted air kerma index (C{sub w}) was 14.3{+-}0.4 mGy, this value is lower than the published by the American College of Radiology, 25 mGy. The multiple scan average dose (MSAD), which is a quantity established by the NOM-229-SSA1-2002 was determined, finding a value of 14.2{+-}0.1 mGy, it is also below the value established, 25 mGy for an adult study.

  14. Temporal Dynamics of Active Prokaryotic Nitrifiers and Archaeal Communities from River to Sea.

    PubMed

    Hugoni, Mylène; Agogué, Hélène; Taib, Najwa; Domaizon, Isabelle; Moné, Anne; Galand, Pierre E; Bronner, Gisèle; Debroas, Didier; Mary, Isabelle

    2015-08-01

    To test if different niches for potential nitrifiers exist in estuarine systems, we assessed by pyrosequencing the diversity of archaeal gene transcript markers for taxonomy (16S ribosomal RNA (rRNA)) during an entire year along a salinity gradient in surface waters of the Charente estuary (Atlantic coast, France). We further investigated the potential for estuarine prokaryotes to oxidize ammonia and hydrolyze urea by quantifying thaumarchaeal amoA and ureC and bacterial amoA transcripts. Our results showed a succession of different nitrifiers from river to sea with bacterial amoA transcripts dominating in the freshwater station while archaeal transcripts were predominant in the marine station. The 16S rRNA sequence analysis revealed that Thaumarchaeota marine group I (MGI) were the most abundant overall but other archaeal groups like Methanosaeta were also potentially active in winter (December-March) and Euryarchaeota marine group II (MGII) were dominant in seawater in summer (April-August). Each station also contained different Thaumarchaeota MGI phylogenetic clusters, and the clusters' microdiversity was associated to specific environmental conditions suggesting the presence of ecotypes adapted to distinct ecological niches. The amoA and ureC transcript dynamics further indicated that some of the Thaumarchaeota MGI subclusters were involved in ammonia oxidation through the hydrolysis of urea. Our findings show that ammonia-oxidizing Archaea and Bacteria were adapted to contrasted conditions and that the Thaumarchaeota MGI diversity probably corresponds to distinct metabolisms or life strategies. PMID:25851445

  15. Radiation resistance of the insulating materials used in the magnetic systems of accelerators

    NASA Astrophysics Data System (ADS)

    Petrov, V. V.; Pupkov, Yu. A.

    2016-07-01

    The radiation resistance of glass-cloth laminate, impregnating epoxy and silicone compounds, lavsan, and other materials used in particle accelerators is measured. Irradiation is performed on an ILU-6 electron accelerator to a dose of 30-100 MGy. Recommendations on the application of the insulating materials are made.

  16. Genomic and Metabolic Diversity of Marine Group I Thaumarchaeota in the Mesopelagic of Two Subtropical Gyres

    PubMed Central

    Swan, Brandon K.; Chaffin, Mark D.; Martinez-Garcia, Manuel; Morrison, Hilary G.; Field, Erin K.; Poulton, Nicole J.; Masland, E. Dashiell P.; Harris, Christopher C.; Sczyrba, Alexander; Chain, Patrick S. G.; Koren, Sergey; Woyke, Tanja; Stepanauskas, Ramunas

    2014-01-01

    Marine Group I (MGI) Thaumarchaeota are one of the most abundant and cosmopolitan chemoautotrophs within the global dark ocean. To date, no representatives of this archaeal group retrieved from the dark ocean have been successfully cultured. We used single cell genomics to investigate the genomic and metabolic diversity of thaumarchaea within the mesopelagic of the subtropical North Pacific and South Atlantic Ocean. Phylogenetic and metagenomic recruitment analysis revealed that MGI single amplified genomes (SAGs) are genetically and biogeographically distinct from existing thaumarchaea cultures obtained from surface waters. Confirming prior studies, we found genes encoding proteins for aerobic ammonia oxidation and the hydrolysis of urea, which may be used for energy production, as well as genes involved in 3-hydroxypropionate/4-hydroxybutyrate and oxidative tricarboxylic acid pathways. A large proportion of protein sequences identified in MGI SAGs were absent in the marine cultures Cenarchaeum symbiosum and Nitrosopumilus maritimus, thus expanding the predicted protein space for this archaeal group. Identifiable genes located on genomic islands with low metagenome recruitment capacity were enriched in cellular defense functions, likely in response to viral infections or grazing. We show that MGI Thaumarchaeota in the dark ocean may have more flexibility in potential energy sources and adaptations to biotic interactions than the existing, surface-ocean cultures. PMID:24743558

  17. Peripheral dose measurements in cervical cancer radiotherapy: a comparison of volumetric modulated arc therapy and step-and-shoot IMRT techniques

    PubMed Central

    2014-01-01

    Purpose The aim of this study was to investigate the peripheral doses resulting from volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) techniques in cervical cancer radiotherapy. Methods Nine patients with cervical cancer had treatment planned with both VMAT and IMRT. A specially designed phantom was used for this study, with ion chambers placed at interest points approximating the position of the breast, thyroid, and lens. The peripheral doses at the phantom interest points were measured and compared between the VMAT and IMRT techniques. Results VMAT provides a potential dosimetric advantage compared with IMRT. The mean (± standard deviation) peripheral dose to the breast point for 1 fraction (2 Gy) during VMAT measured 5.13 ± 0.96 mGy, compared with 9.04 ± 1.50 mGy for IMRT. At the thyroid and lens interest points, the mean (± standard deviation) peripheral dose during VMAT was 2.19 ± 0.33 and 2.16 ± 0.28 mGy, compared with 7.07 ± 0.76 and 6.97 ± 0.91 mGy for IMRT, respectively. VMAT reduced the monitor units used by 28% and shortened the treatment delivery time by 54% compared with IMRT. Conclusion While the dosimetric results are similar for both techniques, VMAT results in a lower peripheral dose to the patient and reduces the monitor-unit usage and treatment delivery time compared with IMRT. PMID:24555547

  18. MOSFET dosimetry mission inside the ISS as part of the Matroshka-R experiment.

    PubMed

    Hallil, A; Brown, M; Akatov, Yu; Arkhangelsky, V; Chernykh, I; Mitrikas, V; Petrov, V; Shurshakov, V; Tomi, L; Kartsev, I; Lyagushin, V

    2010-03-01

    Radiation measurements of surface and deep organ doses were performed aboard the International Space Station, for the period of January 2006 to April 2007, using a MOSFET dosimetry system combined with the Matroshka-R spherical phantom. The averaged internal and surface dose rates are found to be 0.19 and 0.29 mGy d(-1), respectively. The levels of radiation dose to blood-forming organs (BFO) and to surface organs are compared with recommended safe limits. The maximum measured BFO dose has an average dose rate of 0.23 mGy d(-1) (84 mGy y(-1)), corresponding to 44 % of the recommended annual limit of 0.5 Sv, for a space radiation quality factor of 2.6. The annual surface dose is found to be higher at 126 mGy, corresponding to 16 % of the eye dose limit and to 11 % of the skin dose limit. Doses calculated using the Spenvis software showed deviations of up to 37 % from measurements. PMID:19933696

  19. Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice

    SciTech Connect

    Taylor, Kristina; Lemon, Jennifer A.; Phan, Nghi; Boreham, Douglas R.

    2014-05-28

    There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[18F] fluoro-2-deoxy-d-glucose (18F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy 18F-FDG, 4 Gy γ-rays, 10 mGy 18F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from 18F-FDG, with respect to malignancy, is approximately 1. Furthermore, when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average

  20. Investigation of lung nodule detectability in low-dose 320-slice computed tomography

    PubMed Central

    Silverman, J. D.; Paul, N. S.; Siewerdsen, J. H.

    2009-01-01

    Low-dose imaging protocols in chest CT are important in the screening and surveillance of suspicious and indeterminate lung nodules. Techniques that maintain nodule detectability yet permit dose reduction, particularly for large body habitus, were investigated. The objective of this study was to determine the extent to which radiation dose can be minimized while maintaining diagnostic performance through knowledgeable selection of reconstruction techniques. A 320-slice volumetric CT scanner (Aquilion ONE™, Toshiba Medical Systems) was used to scan an anthropomorphic phantom at doses ranging from ∼0.1 mGy up to that typical of low-dose CT (LDCT, ∼5 mGy) and diagnostic CT (∼10 mGy). Radiation dose was measured via Farmer chamber and MOSFET dosimetry. The phantom presented simulated nodules of varying size and contrast within a heterogeneous background, and chest thickness was varied through addition of tissue-equivalent bolus about the chest. Detectability of a small solid lung nodule (3.2 mm diameter, −37 HU, typically the smallest nodule of clinical significance in screening and surveillance) was evaluated as a function of dose, patient size, reconstruction filter, and slice thickness by means of nine-alternative forced-choice (9AFC) observer tests to quantify nodule detectability. For a given reconstruction filter, nodule detectability decreased sharply below a threshold dose level due to increased image noise, especially for large body size. However, nodule detectability could be maintained at lower doses through knowledgeable selection of (smoother) reconstruction filters. For large body habitus, optimal filter selection reduced the dose required for nodule detection by up to a factor of ∼3 (from ∼3.3 mGy for sharp filters to ∼1.0 mGy for the optimal filter). The results indicate that radiation dose can be reduced below the current low-dose (5 mGy) and ultralow-dose (1 mGy) levels with knowledgeable selection of reconstruction parameters. Image

  1. Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system.

    PubMed

    Palm, Asa; Nilsson, Elisabeth; Herrnsdorf, Lars

    2010-01-01

    According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured. TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a 'stack' of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X-ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom. For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3-35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD +/- 10%). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3. In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications. PMID:20160695

  2. Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice

    DOE PAGESBeta

    Taylor, Kristina; Lemon, Jennifer A.; Phan, Nghi; Boreham, Douglas R.

    2014-05-28

    There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[18F] fluoro-2-deoxy-d-glucose (18F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancermore » risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy 18F-FDG, 4 Gy γ-rays, 10 mGy 18F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from 18F-FDG, with respect to malignancy, is approximately 1. Furthermore, when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental.« less

  3. Quantitative assessment of MS plaques and brain atrophy in multiple sclerosis using semiautomatic segmentation method

    NASA Astrophysics Data System (ADS)

    Heinonen, Tomi; Dastidar, Prasun; Ryymin, Pertti; Lahtinen, Antti J.; Eskola, Hannu; Malmivuo, Jaakko

    1997-05-01

    Quantitative magnetic resonance (MR) imaging of the brain is useful in multiple sclerosis (MS) in order to obtain reliable indices of disease progression. The goal of this project was to estimate the total volume of gliotic and non gliotic plaques in chronic progressive multiple sclerosis with the help of a semiautomatic segmentation method developed at the Ragnar Granit Institute. Youth developed program running on a PC based computer provides de displays of the segmented data, in addition to the volumetric analyses. The volumetric accuracy of the program was demonstrated by segmenting MR images of fluid filed syringes. An anatomical atlas is to be incorporated in the segmentation system to estimate the distribution of MS plaques in various neural pathways of the brain. A total package including MS plaque volume estimation, estimation of brain atrophy and ventricular enlargement, distribution of MS plaques in different neural segments of the brain has ben planned for the near future. Our study confirmed that total lesion volumes in chronic MS disease show a poor correlation to EDSS scores but show a positive correlation to neuropsychological scores. Therefore accurate total volume measurements of MS plaques using the developed semiautomatic segmentation technique helped us to evaluate the degree of neuropsychological impairment.

  4. [The "top ten" of Finnish medicine].

    PubMed

    Leikola, A

    1998-01-01

    In the early 1980s the Wellcome Institute was planning a biographical dictionary on the world's most eminent physicians. The quota reserved for Finland was ten names, and having been asked by Dr. Karin Johannisson, Uppsala, to participate in the project, I undertook the task of choosing them and providing a short biography of each. For this, I asked the advice of ten experts on the history of Finnish medicine, and a "top ten" list was then compiled. The list extended from Johan Haartman, "the father of Finnish medicine", till the Nobel Prize winner Ragnar Granit and the famous pediatrist Arvo Ylppo, who were still alive in the 1980s. The biographies were sent to the editor of the dictionary, but it seems that the work was never published. As I had saved all my correspondence about the matter, it seemed now, fifteen years afterwards, interesting to publish a short report of the project, including an account of how the "top ten" list had been achieved. PMID:11625413

  5. Chapter 41: the history of neurology in Scandinavia.

    PubMed

    Aarli, Johan A; Stien, Ragnar

    2010-01-01

    Neurology is well developed in Scandinavia (Denmark, Finland, Iceland, Norway, and Sweden) with a large number of clinical departments and specialists. The care for neurological patients is fairly equally organized even if neurology has evolved from different sources, from psychiatry in Denmark and Finland, internal medicine in Sweden and electrotherapy in Norway. Evidence of diagnostic activity and treatment of neurological diseases can be found in Scandinavia for more than 5000 years. The oldest are trepanned skulls. Written documentation exists from the Viking era, describing treatment of seizures and possibly also the effect of ergotamine. The methods were in concordance with medical practice in the rest of Europe. Scandinavian neurobiologists have produced important contributions to neuroscience during the last 300 or 400 years. Their names can be recognized as eponyms and Nobel prize laureates. Examples are Niels Stensen (Nicolaus Stenoni), the Bartholin family and Knud Krabbe of Denmark, Ragnar Granit of Finland, Bjørn Sigurdsson (the concept of slow virus infections) of Iceland, Asbjørn Følling and Sigvald Refsum of Norway and Gunnar Wohlfart, Eric Kugelberg, Lisa Welander and Arvid Carlsson of Sweden. In addition, well known neurological diseases were described in Scandinavia long before those neuroscientists that today have their names attached to them: Otto Christian Stengel, Norway (1826: Batten-Spielmayer-Vogt's disease), Johan Christian Lund, Norway (1860: Huntington's chorea) and Ernst Alexander Homén, Finland (1889: Wilson's disease). PMID:19892144

  6. Radium-226 dose to a boy from playing on mill tailings

    SciTech Connect

    Mays, C.W.; Lucas, H.F.; Lloyd, R.D. )

    1991-08-01

    Two boys born in September 1949 played on uranium mill tailings from about ages 8 to 12. One of these boys was diagnosed as having leukemia at age 15.5. The 226Ra body burden of the survivor was measured at age 38. The whole-body 226Ra content measured by counting in vivo was 0 {plus minus} 17 Bq and independently by Rn breath analysis as 4.3 {plus minus} 2.1 Bq. At the same time, a control subject with no known exposure to 226Ra, matched in age, height, and weight, was also measured. The whole-body content was estimated as 4 {plus minus} 15 Bq and independently by Rn breath analysis as 5.5 {plus minus} 3.7 Bq. The body burden of the control subject was not significantly different from that of the exposed person. The radiation dose to the marrow-free skeleton assuming a constant 226Ra:Ca ratio since birth was 0.49 and 1.33 mGy at ages 14 and 38, respectively. The radiation dose to the marrow-free skeleton assuming 226Ra intake only between ages 8 to 12 was 1.4 and 2.8 mGy at ages 14 and 38, respectively. The best estimate is the mean of these two estimates: 0.9 and 2.1 mGy at ages 14 and 38, respectively. The alpha-particle dose to the red marrow from 226Ra and its decay products was 0.05 mGy at age 14 and 0.10 mGy at age 38. Since no excess was found for the radium dial painters whose doses were much higher, the induction of leukemia by doses of this magnitude would seem quite unlikely.

  7. Non-induction of radioadaptive response in zebrafish embryos by neutrons.

    PubMed

    Ng, Candy Y P; Kong, Eva Y; Kobayashi, Alisa; Suya, Noriyoshi; Uchihori, Yukio; Cheng, Shuk Han; Konishi, Teruaki; Yu, Kwan Ngok

    2016-06-01

    In vivo neutron-induced radioadaptive response (RAR) was studied using zebrafish (Danio rerio) embryos. The Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Japan, was employed to provide 2-MeV neutrons. Neutron doses of 0.6, 1, 25, 50 and 100 mGy were chosen as priming doses. An X-ray dose of 2 Gy was chosen as the challenging dose. Zebrafish embryos were dechorionated at 4 h post fertilization (hpf), irradiated with a chosen neutron dose at 5 hpf and the X-ray dose at 10 hpf. The responses of embryos were assessed at 25 hpf through the number of apoptotic signals. None of the neutron doses studied could induce RAR. Non-induction of RAR in embryos having received 0.6- and 1-mGy neutron doses was attributed to neutron-induced hormesis, which maintained the number of damaged cells at below the threshold for RAR induction. On the other hand, non-induction of RAR in embryos having received 25-, 50- and 100-mGy neutron doses was explained by gamma-ray hormesis, which mitigated neutron-induced damages through triggering high-fidelity DNA repair and removal of aberrant cells through apoptosis. Separate experimental results were obtained to verify that high-energy photons could disable RAR. Specifically, 5- or 10-mGy X-rays disabled the RAR induced by a priming dose of 0.88 mGy of alpha particles delivered to 5-hpf zebrafish embryos against a challenging dose of 2 Gy of X-rays delivered to the embryos at 10 hpf. PMID:26850927

  8. TLD assessment of mouse dosimetry during microCT imaging

    SciTech Connect

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-09-15

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm{sup 3} CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0{+-}5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0{+-}6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0{+-}4.0 mGy and 97.0{+-}5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0{+-}5.0 mGy. The author's results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality.

  9. Electron paramagnetic resonance dosimetry: Methodology and material characterization

    NASA Astrophysics Data System (ADS)

    Hayes, Robert Bruce

    Electron Paramagnetic Resonance (EPR) methodologies for radiation dose reconstruction are investigated using various dosimeter materials. Specifically, methodologies were developed and used that were intended to improve the accuracy and precision of EPR dosimetric techniques, including combining specimen rotation during measurement, use of an internal manganese standard, instrument stabilization techniques and strict measurement protocols. Characterization and quantification of these improvements were preformed on three specific EPR dosimeter materials. The dosimeter materials investigated using these optimized EPR techniques were Walrus teeth, human tooth enamel and alanine dosimeters. Walrus teeth showed the least desirable properties for EPR dosimetry yielding large native signals and low sensitivity (EPR signal per unit dose). The methods for tooth enamel and alanine resulted in large improvements in precision and accuracy. The minimum detectable dose (MDD) found for alanine was approximately 30 mGy (three standard deviations from the measured zero dose value). This is a sensitivity improvement of 5 to 10 over other specialized techniques published in the literature that offer MDD's in the range of 150 mGy to 300 mGy. The accuracy of the method on tooth enamel was comparable to that typically reported in the literature although the measurement precision was increased by about 7. This improvement in measurement precision enables various applications including dose vs. depth profile analysis and a more nondestructive testing evaluation (where the whole sample need not be additively irradiated in order to calibrate its radiation response). A nondestructive evaluation of numerous samples showed that the method could reconstruct the same doses to within 10 mGy of those evaluated destructively. Doses used for this assessment were in the range of 100 to 250 mGy. The method had sufficient stability to measure tooth enamel samples exhibiting extreme anisotropy with a

  10. RECONSTRUCTION OF INDIVIDUAL RADIATION DOSES FOR A CASE-CONTROL STUDY OF THYROID CANCER IN FRENCH POLYNESIA

    PubMed Central

    Drozdovitch, Vladimir; Bouville, André; Doyon, Françoise; Brindel, Pauline; Cardis, Elisabeth; de Vathaire, Florent

    2014-01-01

    Forty-one atmospheric nuclear weapons tests (plus five safety tests) were conducted in French Polynesia between 1966 and 1974. To evaluate the potential role of atmospheric nuclear weapons testing on a high incidence of thyroid cancer observed since 1985 in French Polynesia, a population-based case-control study was performed. The study included 602 subjects, either cases or controls, all aged less than 40 y at the end of nuclear weapons testing in 1974. Radiation doses to the thyroids of the study subjects were assessed based on the available historical results of radiation measurements. These were mainly found in the annual reports on the radiological situation in French Polynesia that had been sent to the UNSCEAR Secretariat. For each atmospheric nuclear weapons test that contributed substantially to the local deposition of radionuclides, the radiation dose to the thyroid from 131I intake was estimated. In addition, thyroid doses from the intake of short-lived radioiodines (132I, 133I, 135I) and 132Te, external exposure from gamma-emitted radionuclides deposited on the ground, and ingestion of long-lived 137Cs were reconstructed. The mean thyroid dose among the study subjects was found to be around 3 mGy while the highest dose was estimated to be around 40 mGy. Doses from short-lived iodine and tellurium isotopes ranged up to 10 mGy. Thyroid doses from external exposure ranged up to 3 mGy, while those from internal exposure due to cesium ingestion did not exceed 1 mGy. The dose estimates that have been obtained are based on a rather limited number of radiation measurements performed on a limited number of islands and are highly uncertain. A thorough compilation of the results of all radiation monitoring that was performed in French Polynesia in 1966–1974 would be likely to greatly improve the reliability and the precision of the dose estimates. PMID:18403963

  11. Dosimetric Quantities for Computed Tomography Examinations of Paediatric Patients on the Thoracic and Abdominal Regions

    NASA Astrophysics Data System (ADS)

    Flores-M, E.; Buenfil, A. E.; Dies, P.; Gamboa-deBuen, I.; Ruiz-Trejo, C.

    2010-12-01

    Computed Tomography (CT) is a high dose X ray imaging procedure and its use has rapidly increased in the last two decades fueled by the development of helical CT. The aim of this study is to present values of the dosimetric quantities for CT paediatric examinations of thoracic and abdominal regions. The protocols studied were those of chest, lung-mediastine, chest-abdomen, pulmonary high resolution and mediastine-abdomen, which are the more common examinations performed at "Hospital Infantil de México Federico Gómez" in the thoracic-abdominal region. The measurements were performed on a Siemens SOMATOM Sensation 16 CT Scanner and the equipment used was a CT pencil ionization chamber, connected to an electrometer. This system was calibrated for RQT9 CT beam quality. A PMMA head phantom with diameter of 16 cm and length of 15 cm was also used. The dosimetric quantities measured were the weighted air kerma index (Cw), the volumetric dose index (Cvol) and the CT air kerma-length product. It was found that the pulmonary high resolution examination presented the highest values for the Cw (31.1 mGy) and Cvol (11.1 mGy). The examination with the lowest values of these two quantities was the chest-abdomen protocol with 10.5 mGy for Cw and 5.5 mGy for Cvol. However, this protocol presented the highest value for PKL,CT (282.2 mGy cm) when considering the average clinical length of the examinations.

  12. Radiation decay of thaumatin crystals at three X-ray energies.

    PubMed

    Liebschner, Dorothee; Rosenbaum, Gerold; Dauter, Miroslawa; Dauter, Zbigniew

    2015-04-01

    Radiation damage is an unavoidable obstacle in X-ray crystallographic data collection for macromolecular structure determination, so it is important to know how much radiation a sample can endure before being degraded beyond an acceptable limit. In the literature, the threshold at which the average intensity of all recorded reflections decreases to a certain fraction of the initial value is called the `dose limit'. The first estimated D50 dose-limit value, at which the average diffracted intensity was reduced to 50%, was 20 MGy and was derived from observing sample decay in electron-diffraction experiments. A later X-ray study carried out at 100 K on ferritin protein crystals arrived at a D50 of 43 MGy, and recommended an intensity reduction of protein reflections to 70%, D70, corresponding to an absorbed dose of 30 MGy, as a more appropriate limit for macromolecular crystallography. In the macromolecular crystallography community, the rate of intensity decay with dose was then assumed to be similar for all protein crystals. A series of diffraction images of cryocooled (100 K) thaumatin crystals at identical small, 2° rotation intervals were recorded at X-ray energies of 6.33 , 12.66 and 19.00 keV. Five crystals were used for each wavelength. The decay in the average diffraction intensity to 70% of the initial value, for data extending to 2.45 Å resolution, was determined to be about 7.5 MGy at 6.33 keV and about 11 MGy at the two higher energies. PMID:25849388

  13. Assessment of Ge-doped optical fibres subjected to x-ray irradiation

    NASA Astrophysics Data System (ADS)

    Ibrahim, S. A.; Che Omar, S. S.; Hashim, S.; Mahdiraji, G. A.; Bradley, D. A.; Kadir, A. B.; Isa, N. M.

    2014-11-01

    We have reported the thermoluminescence (TL) response of five different diameters ~120, 241, 362, 483, and 604 μm of 6 mol percent Ge-doped optical fibres. The perfomance of the Ge-doped optical fibre are compared with commercially available TLD-100 chips (LiF:Mg,Ti) in terms of their sensitivity and minimum detectable dose (MDD). The irradiation was performed using X-ray machine (Model ISO 'Narrow Spectrum Series') provided by the Malaysian Nuclear Agency (MNA) at 60 kV X-ray irradiation in low doses ranging from 1-10 mGy. The results show the linear TL dose response from the fibres up to 10 mGy. The smallest diameter of 120 pm optical fibre shows the highest TL dose response compared to above mentioned fibres. The minimum detectable dose (MDD) is 0.82, 0.20, 0.14, 0.08, and 0.13 mGy for Ge-doped with diameters of 120, 241, 362, 483 and 604 μm. All TL materials show the MDD value within the delivered dose 0.01-1.00 mGy subjected to x-ray irradiation. The Ge-doped fibre with diameter of 483 pm was matched the MDD value of TLD-100 chips that equivalent to 0.08 mGy at the same irradiation. We have observed that among the five different diameters of optical fibre, 120 μm shows the best results and its better response than TLD-100 chips (by a factor of 5). The linear response at low dose levels makes this optical fibre most suitable for medical application.

  14. ESR dosimetry study on population of settlements nearby Ust-Kamenogorsk city, Kazakhstan.

    PubMed

    Zhumadilov, Kassym; Ivannikov, Alexander; Zharlyganova, Dinara; Zhumadilov, Zhaxybay; Stepanenko, Valeriy; Apsalikov, Kazbek; Ali, Mohd Rodzi; Zhumadilova, Anara; Toyoda, Shin; Endo, Satoru; Tanaka, Kenichi; Okamoto, Tetsuji; Hoshi, Masaharu

    2009-11-01

    The method of electron spin resonance (ESR) dosimetry has been applied to human tooth enamel, to obtain individual absorbed doses of residents of settlements in vicinity of Ust-Kamenogorsk city, Kazakhstan (located about 400 km to the east from the epicenter of explosion at the Semipalatinsk Nuclear Test Site, SNTS). This region developed as a major mining and metallurgical center during the Soviet period (uranium production). Most of the investigated settlements (Ust-Kamenogorsk city, Glubokoe, Tavriya, Gagarino) are located near the central axis of the radioactive fallout trace that originated from the surface nuclear test on 24 August 1956, while the Kokpekty settlement (located 400 km to the Southeast from SNTS) was chosen as a control because it was not subjected to any radioactive contamination. In total, 44 samples were measured. It was found that the excess doses obtained after subtraction of natural background radiation ranged up to about 114 mGy for residents of Ust-Kamenogorsk city, whose tooth enamel was formed before 1956. For residents of Gagarino, excess doses did not exceed 47 mGy for all ages. For residents of Tavriya, the maximum excess dose was 54 mGy, while for residents of Glubokoe it was about 58 mGy. For the population of the Shemonaikha settlements located at a distance of about 70 km from the central axis of the radioactive fallout trace, highest excess doses were 110 mGy. These high doses may be due to the influence of uranium enterprises located in that region, but probably not due to dental X-ray irradiation. For a final conclusion on the radiological situation in this region, the number of samples was too small and, therefore, more work is required to obtain representative results. PMID:19557425

  15. Combined effects of alpha particles and depleted uranium on Zebrafish (Danio rerio) embryos

    PubMed Central

    Ng, Candy Y.P.; Pereira, Sandrine; Cheng, Shuk Han; Adam-Guillermin, Christelle; Garnier-Laplace, Jacqueline; Yu, Kwan Ngok

    2016-01-01

    The combined effects of low-dose or high-dose alpha particles and depleted uranium (DU) in Zebrafish (Danio rerio) embryos were studied. Three schemes were examined—(i) [ILUL]: 0.44 mGy alpha-particle dose + 10 µg/l DU exposure, (ii) [IHUH]: 4.4 mGy alpha-particle dose + 100 µg/l DU exposure and (iii) [IHUL]: 4.4 mGy alpha-particle dose + 10 µg/l DU exposure—in which Zebrafish embryos were irradiated with alpha particles at 5 h post fertilization (hpf) and/or exposed to uranium at 5–6 hpf. The results were also compared with our previous work, which studied the effects of [ILUH]: 0.44 mGy alpha-particle dose + 100 µg/l DU exposure. When the Zebrafish embryos developed to 24 hpf, the apoptotic signals in the entire embryos, used as the biological endpoint for this study, were quantified. Our results showed that [ILUL] and [IHUL] led to antagonistic effects, whereas [IHUH] led to an additive effect. The effect found for the previously studied case of [ILUH] was difficult to define because it was synergistic with reference to the 100 µg/l DU exposure, but it was antagonistic with reference to the 0.44 mGy alpha-particle dose. All the findings regarding the four different schemes showed that the combined effects critically depended on the dose response to each individual stressor. We also qualitatively explained these findings in terms of promotion of early death of cells predisposed to spontaneous transformation by alpha particles, interacting with the delay in cell death resulting from various concentrations of DU exposure. PMID:26937024

  16. A gradient of radioactive contamination in Dolon village near the SNTS and comparison of computed dose values with instrumental estimates for the 29 August, 1949 nuclear test.

    PubMed

    Stepanenko, Valeriy F; Hoshi, Masaharu; Dubasov, Yuriy V; Sakaguchi, Aya; Yamamoto, Masayoshi; Orlov, Mark Y; Bailiff, Ian K; Ivannikov, Alexander I; Skvortsov, Valeriy G; Iaskova, Elena K; Kryukova, Irina G; Zhumadilov, Kassym S; Endo, Satoru; Tanaka, Kenichi; Apsalikov, Kazbek N; Gusev, Boris I

    2006-02-01

    Spatial distributions of soil contamination by 137Cs (89 sampling points) and 239+240Pu (76 points) near and within Dolon village were analyzed. An essential exponential decrease of contamination was found in Dolon village: the distance of a half reduction in contamination is about 0.87-1.25 km (in a northwest-southeast direction from the supposed centerline of the radioactive trace). This fact is in agreement with the available exposure rate measurements near Dolon (September 1949 archive data): on the basis of a few measurements the pattern of the trace was estimated to comprise a narrow 2 km corridor of maximum exposure rate. To compare computed external doses in air with local dose estimates by retrospective luminescence dosimetry (RLD) the gradient of radioactive soil contamination within the village was accounted for. The computed dose associated with the central axis of the trace was found to be equal to 2260 mGy (calculations based on archive exposure rate data). Local doses near the RLD sampling points (southeast of the village) were calculated to be in the range 466-780 mGy (averaged value: 645+/-70 mGy), which is comparable with RLD data (averaged value 460+/-92 mGy with range 380-618 mGy). A comparison of the computed mean dose in the settlement with dose estimates by ESR tooth enamel dosimetry makes it possible to estimate the "upper level" of the "shielding and behavior" factor in dose reduction for inhabitants of Dolon village which was found to be 0.28+/-0.068. PMID:16571930

  17. Radiation effects in generic populations inhabiting a limiting environment.

    PubMed

    Sazykina, T G; Kryshev, A I

    2012-05-01

    A generic population model is formulated for radiation risk assessment of natural biota. The model demonstrates that effects of radiation on the population survival do not follow directly the effects on individual organisms. Dose rates resulting in population extinction can be analytically calculated. Besides individual radiosensitivity, two key parameters were found to determine the survival potential of a population under chronic radiation stress: the ratio “biomass losses/biomass synthesis,” and the lump amount of limiting resource in the environment. A benchmark scenario “Population response to chronic irradiation” developed within the IAEA Programme EMRAS II was calculated for generic populations of mice, hare/rabbit, wolf/wild dog, and deer/goat chronically exposed to different levels of ionizing radiation. In the conditions of the benchmark scenario, model populations survived normally (>90% of the control value) at dose rates below the following levels: 3 mGy day(-1) for wolf/wild dog; 10 mGy day(-1) for deer/goat; 14 mGy day(-1) for hare/rabbit; and 20 mGy day(-1) for mice. The model predictions showed a relatively high survival potential of short-lived and productive species such as mice. At the same time, populations of long-lived animals with slow and radiosensitive reproduction such as wolf/wild dog were candidates to extinction at chronic exposures above 5 mGy day(-1). Recovery of short-lived and productive species took a much shorter time compared with long-lived and slow reproductive species. PMID:22302184

  18. Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

    SciTech Connect

    Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa

    2010-07-15

    Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.

  19. Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments1

    PubMed Central

    Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa

    2010-01-01

    Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife® system (before and after a supplemental shielding was applied), a TomoTherapy® system, and a Gamma Knife® unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose. PMID:20831066

  20. Non-induction of radioadaptive response in zebrafish embryos by neutrons

    PubMed Central

    Ng, Candy Y.P.; Kong, Eva Y.; Kobayashi, Alisa; Suya, Noriyoshi; Uchihori, Yukio; Cheng, Shuk Han; Konishi, Teruaki; Yu, Kwan Ngok

    2016-01-01

    In vivo neutron-induced radioadaptive response (RAR) was studied using zebrafish (Danio rerio) embryos. The Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Japan, was employed to provide 2-MeV neutrons. Neutron doses of 0.6, 1, 25, 50 and 100 mGy were chosen as priming doses. An X-ray dose of 2 Gy was chosen as the challenging dose. Zebrafish embryos were dechorionated at 4 h post fertilization (hpf), irradiated with a chosen neutron dose at 5 hpf and the X-ray dose at 10 hpf. The responses of embryos were assessed at 25 hpf through the number of apoptotic signals. None of the neutron doses studied could induce RAR. Non-induction of RAR in embryos having received 0.6- and 1-mGy neutron doses was attributed to neutron-induced hormesis, which maintained the number of damaged cells at below the threshold for RAR induction. On the other hand, non-induction of RAR in embryos having received 25-, 50- and 100-mGy neutron doses was explained by gamma-ray hormesis, which mitigated neutron-induced damages through triggering high-fidelity DNA repair and removal of aberrant cells through apoptosis. Separate experimental results were obtained to verify that high-energy photons could disable RAR. Specifically, 5- or 10-mGy X-rays disabled the RAR induced by a priming dose of 0.88 mGy of alpha particles delivered to 5-hpf zebrafish embryos against a challenging dose of 2 Gy of X-rays delivered to the embryos at 10 hpf. PMID:26850927

  1. TLD assessment of mouse dosimetry during microCT imaging

    PubMed Central

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-01-01

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

  2. Computer-based thermal imaging of human gingiva: preliminary investigation.

    PubMed

    Barnett, M L; Gilman, R M; Charles, C H; Bartels, L L

    1989-11-01

    Computer-based thermal imaging techniques were used to compare the rewarming rates of normal and inflamed human gingiva following cooling. A Modified Gingival Index (MGI) score, gingival crevicular fluid (GCF) measurement, and clinical photograph were obtained from a maxillary or mandibular anterior facial region in 20 subjects, aged 25 to 44. Baseline thermograms of the marginal/papillary (M/P) and adjacent attached gingiva (AG) were recorded following an acclimatization period with the patient seated and chin resting on a positioning apparatus. The tissue was then cooled with a gentle stream of air and thermograms were recorded at 10 second intervals for 3 minutes as the tissue rewarmed. Rewarming slopes were calculated based on these thermograms. Correlation coefficients were calculated for MGI with GCF, as well as for both MGI and GCF with AG and M/P rewarming slopes. Mean baseline (SE) temperatures (degrees F) for AG were 75.9 (0.9), 78.0 (0.6), and 80.3 (1.3) for normal, mildly inflamed, and moderately-severely inflamed gingivae, respectively; corresponding mean (SE) temperature differences (degrees F) between AG and M/P were 0.5 (0.2), 0.9 (0.2), and 1.4 (0.3). Intragroup mean M/P temperatures were less than mean AG temperatures, with the mean regional differences increasing with greater severity of inflammation. Rewarming rates also increased as inflammation became more severe, with the rewarming slopes of both the AG and M/P having statistically significant correlations with the MGI and the GCF. The correlation between MGI and GCF was also statistically significant. This study suggests that computer-based thermal imaging techniques can detect both static and dynamic temperature differences between normal gingiva and gingivae with increasing severities of inflammation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2600750

  3. Diagnostic accuracy at several reduced radiation dose levels for CT imaging in the diagnosis of appendicitis

    NASA Astrophysics Data System (ADS)

    Zhang, Di; Khatonabadi, Maryam; Kim, Hyun; Jude, Matilda; Zaragoza, Edward; Lee, Margaret; Patel, Maitraya; Poon, Cheryce; Douek, Michael; Andrews-Tang, Denise; Doepke, Laura; McNitt-Gray, Shawn; Cagnon, Chris; DeMarco, John; McNitt-Gray, Michael

    2012-03-01

    Purpose: While several studies have investigated the tradeoffs between radiation dose and image quality (noise) in CT imaging, the purpose of this study was to take this analysis a step further by investigating the tradeoffs between patient radiation dose (including organ dose) and diagnostic accuracy in diagnosis of appendicitis using CT. Methods: This study was IRB approved and utilized data from 20 patients who underwent clinical CT exams for indications of appendicitis. Medical record review established true diagnosis of appendicitis, with 10 positives and 10 negatives. A validated software tool used raw projection data from each scan to create simulated images at lower dose levels (70%, 50%, 30%, 20% of original). An observer study was performed with 6 radiologists reviewing each case at each dose level in random order over several sessions. Readers assessed image quality and provided confidence in their diagnosis of appendicitis, each on a 5 point scale. Liver doses at each case and each dose level were estimated using Monte Carlo simulation based methods. Results: Overall diagnostic accuracy varies across dose levels: 92%, 93%, 91%, 90% and 90% across the 100%, 70%, 50%, 30% and 20% dose levels respectively. And it is 93%, 95%, 88%, 90% and 90% across the 13.5-22mGy, 9.6-13.5mGy, 6.4-9.6mGy, 4-6.4mGy, and 2-4mGy liver dose ranges respectively. Only 4 out of 600 observations were rated "unacceptable" for image quality. Conclusion: The results from this pilot study indicate that the diagnostic accuracy does not change dramatically even at significantly reduced radiation dose.

  4. Dosimetric Quantities for Computed Tomography Examinations of Paediatric Patients on the Thoracic and Abdominal Regions

    SciTech Connect

    Flores-M, E.; Gamboa de Buen, I.; Buenfil, A. E.; Ruiz-Trejo, C.; Dies, P.

    2010-12-07

    Computed Tomography (CT) is a high dose X ray imaging procedure and its use has rapidly increased in the last two decades fueled by the development of helical CT. The aim of this study is to present values of the dosimetric quantities for CT paediatric examinations of thoracic and abdominal regions. The protocols studied were those of chest, lung-mediastine, chest-abdomen, pulmonary high resolution and mediastine-abdomen, which are the more common examinations performed at ''Hospital Infantil de Mexico Federico Gomez'' in the thoracic-abdominal region. The measurements were performed on a Siemens SOMATOM Sensation 16 CT Scanner and the equipment used was a CT pencil ionization chamber, connected to an electrometer. This system was calibrated for RQT9 CT beam quality. A PMMA head phantom with diameter of 16 cm and length of 15 cm was also used. The dosimetric quantities measured were the weighted air kerma index (C{sub w}), the volumetric dose index (C{sub vol}) and the CT air kerma-length product. It was found that the pulmonary high resolution examination presented the highest values for the C{sub w}(31.1 mGy) and C{sub vol}(11.1 mGy). The examination with the lowest values of these two quantities was the chest-abdomen protocol with 10.5 mGy for C{sub w} and 5.5 mGy for C{sub vol}. However, this protocol presented the highest value for P{sub KL,CT}(282.2 mGy cm) when considering the average clinical length of the examinations.

  5. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study

    PubMed Central

    Pearce, Mark S; Salotti, Jane A; Little, Mark P; McHugh, Kieran; Lee, Choonsik; Kim, Kwang Pyo; Howe, Nicola L; Ronckers, Cecile M; Rajaraman, Preetha; Craft, Alan W; Parker, Louise; de González, Amy Berrington

    2012-01-01

    Summary Background Although CT scans are very useful clinically, potential cancer risks exist from associated ionising radiation, in particular for children who are more radiosensitive than adults. We aimed to assess the excess risk of leukaemia and brain tumours after CT scans in a cohort of children and young adults. Methods In our retrospective cohort study, we included patients without previous cancer diagnoses who were first examined with CT in National Health Service (NHS) centres in England, Wales, or Scotland (Great Britain) between 1985 and 2002, when they were younger than 22 years of age. We obtained data for cancer incidence, mortality, and loss to follow-up from the NHS Central Registry from Jan 1, 1985, to Dec 31, 2008. We estimated absorbed brain and red bone marrow doses per CT scan in mGy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson relative risk models. To avoid inclusion of CT scans related to cancer diagnosis, follow-up for leukaemia began 2 years after the first CT and for brain tumours 5 years after the first CT. Findings During follow-up, 74 of 178 604 patients were diagnosed with leukaemia and 135 of 176 587 patients were diagnosed with brain tumours. We noted a positive association between radiation dose from CT scans and leukaemia (excess relative risk [ERR] per mGy 0·036, 95% CI 0·005–0·120; p=0·0097) and brain tumours (0·023, 0·010–0·049; p<0·0001). Compared with patients who received a dose of less than 5 mGy, the relative risk of leukaemia for patients who received a cumulative dose of at least 30 mGy (mean dose 51·13 mGy) was 3·18 (95% CI 1·46–6·94) and the relative risk of brain cancer for patients who received a cumulative dose of 50–74 mGy (mean dose 60·42 mGy) was 2·82 (1·33–6·03). Interpretation Use of CT scans in children to deliver cumulative doses of about 50 mGy might almost triple the risk of leukaemia and doses of about 60 mGy might triple the risk of brain

  6. DIII-D Studies of Massive Gas Injection Fast Shutdowns for Disruption Mitigation

    SciTech Connect

    Hollmann, E; Jernigan, T; Antar, G; Bakhtiari, M; Boedo, J; Combs, S; Evans, T; Gray, D; Groth, M; Humphreys, D; Lasnier, C; Moyer, R; Parks, P; Rudakov, D; Strait, E; Wesley, J; West, W; Whyte, D; Yu, J

    2006-09-29

    Injection of massive quantities of gas is a promising technique for fast shutdown of ITER for the purpose of avoiding divertor and first wall damage from disruptions. Previous experiments using massive gas injection (MGI) to terminate discharges in the DIII-D tokamak have demonstrated rapid shutdown with reduced wall heating and halo currents (relative to natural disruptions) and with very small runaway electron (RE) generation [1]. Figure 1 shows time traces which give an overview of shutdown time scales. Typically, of order 5 x 10{sup 22} Ar neutrals are fired over a pulse of 25 ms duration into stationary (non-disrupting) discharges. The observed results are consistent with the following scenario: within several ms of the jet trigger, sufficient Ar neutrals are delivered to the plasma to cause the edge temperature to collapse, initiating the inward propagation of a cold front. The exit flow of the jet [Fig. 1(a)] has a {approx} 9 ms rise time; so the quantity of neutrals which initiates the edge collapse is small (<10{sup 20}). When the cold front reaches q {approx} 2 surface, global magnetohydrodynamic (MHD) modes are destabilized [2], mixing hot core plasma with edge impurities. Here, q is the safety factor. Most (>90%) of the plasma thermal energy is lost via impurity radiation during this thermal quench (TQ) phase. Conducted heat loads to the wall are low because of the cold edge temperature. After the TQ, the plasma is very cold (of order several eV), so conducted wall (halo) currents are low, even if the current channel contacts the wall. The plasma current profile broadens and begins decaying resistively. The decaying current generates a toroidal electric field which can accelerate REs; however, RE beam formation appears to be limited in MGI shutdowns. Presently, it is thought that the conducted heat flux and halo current mitigation qualities of the MGI shutdown technique will scale well to a reactor-sized tokamak. However, because of the larger RE gain

  7. WE-D-18A-04: How Iterative Reconstruction Algorithms Affect the MTFs of Variable-Contrast Targets in CT Images

    SciTech Connect

    Dodge, C.T.; Rong, J.; Dodge, C.W.

    2014-06-15

    Purpose: To determine how filtered back-projection (FBP), adaptive statistical (ASiR), and model based (MBIR) iterative reconstruction algorithms affect the measured modulation transfer functions (MTFs) of variable-contrast targets over a wide range of clinically applicable dose levels. Methods: The Catphan 600 CTP401 module, surrounded by an oval, fat-equivalent ring to mimic patient size/shape, was scanned on a GE HD750 CT scanner at 1, 2, 3, 6, 12 and 24 mGy CTDIvol levels with typical patient scan parameters: 120kVp, 0.8s, 40mm beam width, large SFOV, 2.5mm thickness, 0.984 pitch. The images were reconstructed using GE's Standard kernel with FBP; 20%, 40% and 70% ASiR; and MBIR. A task-based MTF (MTFtask) was computed for six cylindrical targets: 2 low-contrast (Polystyrene, LDPE), 2 medium-contrast (Delrin, PMP), and 2 high-contrast (Teflon, air). MTFtask was used to compare the performance of reconstruction algorithms with decreasing CTDIvol from 24mGy, which is currently used in the clinic. Results: For the air target and 75% dose savings (6 mGy), MBIR MTFtask at 5 lp/cm measured 0.24, compared to 0.20 for 70% ASiR and 0.11 for FBP. Overall, for both high-contrast targets, MBIR MTFtask improved with increasing CTDIvol and consistently outperformed ASiR and FBP near the system's Nyquist frequency. Conversely, for Polystyrene at 6 mGy, MBIR (0.10) and 70% ASiR (0.07) MTFtask was lower than for FBP (0.18). For medium and low-contrast targets, FBP remains the best overall algorithm for improved resolution at low CTDIvol (1–6 mGy) levels, whereas MBIR is comparable at higher dose levels (12–24 mGy). Conclusion: MBIR improved the MTF of small, high-contrast targets compared to FBP and ASiR at doses of 50%–12.5% of those currently used in the clinic. However, for imaging low- and mediumcontrast targets, FBP performed the best across all dose levels. For assessing MTF from different reconstruction algorithms, task-based MTF measurements are necessary.

  8. Radiation protection issues in dynamic contrast-enhanced (perfusion) computed tomography.

    PubMed

    Brix, Gunnar; Lechel, Ursula; Nekolla, Elke; Griebel, Jürgen; Becker, Christoph

    2015-12-01

    Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions. To characterize stochastic radiation risks of patients from these studies, life-time attributable cancer risks (LAR) were estimated using sex-, age-, and organ-specific risk models based on the hypothesis of a linear non-threshold dose-response relationship. For the brain, heart and pelvic cancer studies considered, local absorbed doses in the imaging field were about 100-190 mGy (total CTDI(vol), 200 mGy), 15-30 mGy (16 mGy) and 80-270 mGy (140 mGy), respectively. According to a recent publication of the International Commission on Radiological Protection (ICRP Publication 118, 2012), harmful tissue reactions of the cerebro- and cardiovascular systems as well as of the lenses of the eye become increasingly important at radiation doses of more than 0.5 Gy. The LARs estimated for the investigated cerebral and myocardial DCE-CT scenarios are less than 0.07% for males and 0.1% for females at an age of exposure of 40 years. For the considered tumor location and protocol, the corresponding LARs are more than 6 times as high

  9. Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms.

    PubMed

    Koivisto, Juha H; Wolff, Jan E; Kiljunen, Timo; Schulze, Dirk; Kortesniemi, Mika

    2015-01-01

    The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in

  10. Development of CT scanner models for patient organ dose calculations using Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Gu, Jianwei

    There is a serious and growing concern about the CT dose delivered by diagnostic CT examinations or image-guided radiation therapy imaging procedures. To better understand and to accurately quantify radiation dose due to CT imaging, Monte Carlo based CT scanner models are needed. This dissertation describes the development, validation, and application of detailed CT scanner models including a GE LightSpeed 16 MDCT scanner and two image guided radiation therapy (IGRT) cone beam CT (CBCT) scanners, kV CBCT and MV CBCT. The modeling process considered the energy spectrum, beam geometry and movement, and bowtie filter (BTF). The methodology of validating the scanner models using reported CTDI values was also developed and implemented. Finally, the organ doses to different patients undergoing CT scan were obtained by integrating the CT scanner models with anatomically-realistic patient phantoms. The tube current modulation (TCM) technique was also investigated for dose reduction. It was found that for RPI-AM, thyroid, kidneys and thymus received largest dose of 13.05, 11.41 and 11.56 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. For RPI-AF, thymus, small intestine and kidneys received largest dose of 10.28, 12.08 and 11.35 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. The dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. For MDCT with TCM schemas, the fetal dose can be reduced with 14%-25%. To demonstrate the applicability of the method proposed in this dissertation for modeling the CT scanner, additional MDCT scanner was modeled and validated by using the measured CTDI values. These results demonstrated that the

  11. Comparative proteomic analysis of rice after seed ground simulated radiation and spaceflight explains the radiation effects of space environment

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Shi, Jinming; Liang, Shujian; Lei, Huang; Shenyi, Zhang; Sun, Yeqing

    In previous work, we compared the proteomic profiles of rice plants growing after seed space-flights with ground controls by two-dimensional difference gel electrophoresis (2-D DIGE) and found that the protein expression profiles were changed after seed space environment exposures. Spaceflight represents a complex environmental condition in which several interacting factors such as cosmic radiation, microgravity and space magnetic fields are involved. Rice seed is in the process of dormant of plant development, showing high resistance against stresses, so the highly ionizing radiation (HZE) in space is considered as main factor causing biological effects to seeds. To further investigate the radiation effects of space environment, we performed on-ground simulated HZE particle radiation and compared between the proteomes of seed irra-diated plants and seed spaceflight (20th recoverable satellite) plants from the same rice variety. Space ionization shows low-dose but high energy particle effects, for searching the particle effects, ground radiations with the same low-dose (2mGy) but different liner energy transfer (LET) values (13.3KeV/µm-C, 30KeV/µm-C, 31KeV/µm-Ne, 62.2KeV/µm-C, 500Kev/µm-Fe) were performed; using 2-D DIGE coupled with clustering and principle component analysis (PCA) for data process and comparison, we found that the holistic protein expression patterns of plants irradiated by LET-62.2KeV/µm carbon particles were most similar to spaceflight. In addition, although space environment presents a low-dose radiation (0.177 mGy/day on the satellite), the equivalent simulated radiation dose effects should still be evaluated: radiations of LET-62.2KeV/µm carbon particles with different cumulative doses (2mGy, 20mGy, 200mGy, 2000mGy) were further carried out and resulted that the 2mGy radiation still shared most similar proteomic profiles with spaceflight, confirming the low-dose effects of space radiation. Therefore, in the protein expression level

  12. SU-C-12A-05: Radiation Dose in High-Pitch Pediatric Cardiac CTA: Correlation Between Lung Dose and CTDIvol, DLP, and Size Specific Dose Estimates (SSDE)

    SciTech Connect

    Wang, J; Kino, A; Newman, B; Chan, F

    2014-06-01

    Purpose: To investigate the radiation dose for pediatric high pitch cardiac CTA Methods: A total of 14 cases were included in this study, with mean age of 6.2 years (ranges from 2 months to 15 years). Cardiac CTA was performed using a dual-source CT system (Definition Flash, Siemens). Tube voltage (70, 80 and 100kV) was chosen based on patient weight. All patients were scanned using a high-pitch spiral mode (pitch ranges from 2.5 to 3) with tube current modulation technique (CareDose4D, Siemens). For each case, the three dimensional dose distributions were calculated using a Monte Carlo software package (IMPACT-MC, CT Image GmbH). Scanning parameters of each exam, including tube voltage, tube current, beamshaping filters, beam collimation, were defined in the Monte Carlo calculation. Tube current profile along projection angles was obtained from projection data of each tube, which included data within the over-scanning range along z direction. The volume of lungs was segmented out with CT images (3DSlicer). Lung doses of all patients were calculated and compared with CTDIvol, DLP, and SSDE. Results: The average (range) of CTDIvol, DLP and SSDE of all patients was 1.19 mGy (0.58 to 3.12mGy), 31.54 mGy*cm (12.56 to 99 mGy*cm), 2.26 mGy (1.19 to 6.24 mGy), respectively. Radiation dose to the lungs ranged from 0.83 to 4.18 mGy. Lung doses correlated with CTDIvol, DLP and SSDE with correlation coefficients(k) at 0.98, 0.93, and 0.99. However, for the cases with CTDIvol less than 1mGy, only SSDE preserved a strong correlation with lung doses (k=0.83), while much weaker correlations were found for CTDIvol (k=0.29) and DLP (k=-0.47). Conclusion: Lung doses to pediatric patients during Cardiac CTA were estimated. SSDE showed the most robust correlation with lung doses in contrast to CTDIvol and DLP.

  13. Assessment of paediatric CT dose indicators for the purpose of optimisation

    PubMed Central

    Brady, Z; Ramanauskas, F; Cain, T M; Johnston, P N

    2012-01-01

    Objectives To establish local diagnostic reference levels (LDRLs) at the Royal Children's Hospital (RCH) Melbourne, Parkville, Australia, for typical paediatric CT examinations and compare these with international diagnostic reference levels (DRLs) to benchmark local practice. In addition, the aim was to develop a method of analysing local scan parameters to enable identification of areas for optimisation. Methods A retrospective audit of patient records for paediatric CT brain, chest and abdomen/pelvis examinations was undertaken. Demographic information, examination parameters and dose indicators—volumetric CT dose index (CTDIvol) and dose–length product (DLP)—were collected for 220 patients. LDRLs were derived from mean survey values and the effective dose was estimated from DLP values. The normalised CTDIvol values, mAs values and scan length were analysed to better identify parameters that could be optimised. Results The LDRLs across all age categories were 18–45 mGy (CTDIvol) and 250–700 mGy cm (DLP) for brain examinations; 3–23 mGy (CTDIvol) and 100–800 mGy cm (DLP) for chest examinations; and 4–15 mGy (CTDIvol) and 150–750 mGy cm (DLP) for abdomen/pelvis examinations. Effective dose estimates were 1.0–1.6 mSv, 1.8–13.0 mSv and 2.5–10.0 mSv for brain, chest and abdomen/pelvis examinations, respectively. Conclusion The RCH mean CTDIvol and DLP values are similar to or lower than international DRLs. Use of low-kilovoltage protocols for body imaging in younger patients reduced the dose considerably. There exists potential for optimisation in reducing body scan lengths and justifying the selection of reference mAs values. The assessment method used here proved useful for identifying specific parameters for optimisation. Advances in knowledge Assessment of individual CT parameters in addition to comparison with DRLs enables identification of specific areas for CT optimisation. PMID:22844033

  14. In Utero Exposure to Iodine-131 from Chernobyl Fallout and Anthropometric Characteristics in Adolescence

    PubMed Central

    Neta, Gila; Hatch, Maureen; Kitahara, Cari M.; Ostroumova, Evgenia; Bolshova, Elena V.; Tereschenko, Valery P.; Tronko, Mykola D.; Brenner, Alina V.

    2014-01-01

    Prenatal exposure to external radiation has been linked to growth retardation among atomic bomb survivors in adolescence. It is unclear from previous studies whether in utero exposure to internal radiation such as iodine-131 (I-131), which concentrates in the thyroid gland, has an effect on physical growth. We examined the associations between estimated thyroid gland dose from prenatal exposure to I-131 and self-reported height and weight in a cohort of 2,460 individuals exposed to radioactive fallout from the 1986 Chernobyl nuclear accident [mean I-131 dose = 72 (mGy)] and screened for thyroid diseases in adolescence. Using multivariable linear regression models, we estimated the mean differences in height, weight and body mass index (BMI) per unit increase in dose (100 mGy) in models adjusted for gender, age at examination, type of residence (rural/urban) and presence of thyroid disease diagnosed at screening. All of the adjustment factors as well as the trimester of exposure were evaluated as potential modifiers of the dose response. Overall, no significant dose response was found for height (P = 0.29), weight (P = 0.14) or BMI (P = 0.16). We found significant modification of the dose response for weight and BMI by presence/absence of thyroid disease (P = 0.02 and P = 0.03, respectively), but not for other factors. In individuals without thyroid disease (n = 1,856), there was a weak, significant association between I-131 thyroid dose and higher weight (210 g per 100 mGy, P = 0.02) or BMI (70 g/m2 per 100 mGy, P = 0.02) that depended on individuals (n = 52) exposed to ≥500 mGy. In individuals with thyroid disease (n = 579, 67.4% with simple diffuse goiter) no significant association with I-131 for weight (P = 0.14) or BMI (P = 0.14) was found. These results do not support the hypothesis that in utero exposure to I-131 at levels experienced by a majority of study subjects may be associated with meaningful differences in adolescent anthropometry. However

  15. Electron beam irradiation pretreatment and enzymatic saccharification of used newsprint and paper mill wastes

    NASA Astrophysics Data System (ADS)

    Waheed Khan, A.; Labrie, Jean-Pierre; McKeown, Joseph

    Electron beam pretreatment of used newsprint, pulp, as well as pulp recovered from clarifier sludge and paper mill sludge, caused the dissociation of cellulose from lignin, and rendered them suitable for enzymatic hydrolysis. A maximum dose of 1 MGy for newsprint and 1.5—2.0 MGy for pulp and paper mill sludge was required to render cellulose present in them in a form which, could be enzymatically saccharified to 90% of completion. Saccharification approaching the theoretical yield was obtained in 2 days with a cellulolytic enzyme system obtained from Trichoderma reesei. As a result of irradiation, water soluble lignin breakdown products, NaOH- soluble lignin, free cellobiose, glucose, mannose, xylose and their polymers, and acetic acid were produced from these materials.

  16. Radiation doses in adult computed tomography practice in Serbia: initial results.

    PubMed

    Arandjic, Danijela; Ciraj-Bjelac, Olivera; Hadnadjev, Darka; Stojanovic, Sanja; Bozovic, Predrag; Ceklic, Sandra; Lazarevic, Djordje

    2014-11-01

    This work presents initial data on radiation doses in adult computed tomography (CT) in Serbia. Data were collected in terms of CT dose index (CTDIvol) and dose length product (DLP) values for head, chest and abdomen examination. The range of CTDIvol values was found to be 53-98, 11-34 and 8.5-227 mGy whereas for DLP was 803-1066, 350-845 and 1066-3078 mGy cm(-1) for head, chest and abdomen examination, respectively. Except for abdomen on one CT unit, all estimated values were in line with the reported data. This work also presents simple method on how to reduce radiation doses when scanning head. Using axial (step-and-shot) instead of helical mode and decreasing tube current-time product leads to significant dose reduction. CTDIvol was decreased by 20 % whereas DLP was reduced for a factor 2. PMID:25063787

  17. Emergency OSL/TL dosimetry with integrated circuits from mobile phones

    NASA Astrophysics Data System (ADS)

    Sholom, S.; McKeever, S. W. S.

    2014-09-01

    Integrated circuits (ICs) from several mobile phones were studied as possible emergency dosimeters using optically stimulated luminescence (OSL) and thermoluminescence (TL) techniques. Measurement protocols were developed for ICs that take into consideration the effect of sensitization of the samples with increasing dose as well as fading of the signals after sample exposure. It was found that the OSL technique has a higher sensitivity with ICs when compared to TL, while the TL signals were characterized by better stability with time after exposure. Values of minimum measurable doses were found to be in the range between a few tens of mGy and several tens of mGy for the tested samples. It was concluded that ICs from mobile phones could be used for emergency dose reconstruction.

  18. Enhancement of runaway production by resonant magnetic perturbation on J-TEXT

    NASA Astrophysics Data System (ADS)

    Chen, Z. Y.; Huang, D. W.; Izzo, V. A.; Tong, R. H.; Jiang, Z. H.; Hu, Q. M.; Wei, Y. N.; Yan, W.; Rao, B.; Wang, S. Y.; Ma, T. K.; Li, S. C.; Yang, Z. J.; Ding, D. H.; Wang, Z. J.; Zhang, M.; Zhuang, G.; Pan, Y.; J-TEXT Team

    2016-07-01

    The suppression of runaways following disruptions is key for the safe operation of ITER. The massive gas injection (MGI) has been developed to mitigate heat loads, electromagnetic forces and runaway electrons (REs) during disruptions. However, MGI may not completely prevent the generation of REs during disruptions on ITER. Resonant magnetic perturbation (RMP) has been applied to suppress runaway generation during disruptions on several machines. It was found that strong RMP results in the enhancement of runaway production instead of runaway suppression on J-TEXT. The runaway current was about 50% pre-disruption plasma current in argon induced reference disruptions. With moderate RMP, the runway current decreased to below 30% pre-disruption plasma current. The runaway current plateaus reach 80% of the pre-disruptive current when strong RMP was applied. Strong RMP may induce large size magnetic islands that could confine more runaway seed during disruptions. This has important implications for runaway suppression on large machines.

  19. Radioluminescence characterization of hot pressed, reaction bonded, and CVD SiC

    NASA Astrophysics Data System (ADS)

    Malo, M.; Manzano, J.; Moroño, A.; Hodgson, E. R.

    2010-11-01

    Radioluminescence (RL) measurements of three types of silicon carbide, material considered for use in future fusion reactors, have been made to examine the potential of this technique as a possible way to evaluate in-situ the radiation damage during reactor irradiations. RL spectra taken during 1.8 MeV electron irradiation have a strong dependence on SiC type and irradiation time (dose), the intensity decreasing with irradiation dose for all samples. Reported reduction in crystallinity for HP SiC revealed by X-ray diffraction analysis following electron irradiation to 420 MGy, and the marked reduction of the main RL band by 200 MGy may be related, and that RL should be fully examined as a tool for in-situ characterization.

  20. Feasibility of Three-Dimensional MR Angiography Image Fusion Guidance for Endovascular Abdominal Aortic Aneurysm Repair.

    PubMed

    Tacher, Vania; Desgranges, Pascal; You, Ketsakin; Ridouani, Fourat; Marzelle, Jean; Kobeiter, Hicham

    2016-02-01

    Magnetic resonance (MR) angiography image fusion (IF) with live fluoroscopy guidance was used while performing endovascular repair of abdominal aortic aneurysm (EVAR) in five patients with a history of chronic renal disease or severe contrast allergy. Intraprocedural technical success was 100%. Median procedure time was 120 minutes (range, 60-180 min), fluoroscopy time was 40 minutes (range, 17-65 min), dose-area product was 245,867 mGy × cm(2) (range, 68,435-690,053 mGy × cm(2)), and iodinated contrast volume injected was 15 mL (range, 0-40 mL). Technical success was achieved in four of five patients (80%); one case was complicated by a type 1 endoleak on follow-up MR angiography, which was successfully treated. EVAR with MR angiography IF guidance was technically feasible and safe in five patients and reduced or eliminated the use of iodinated contrast media. PMID:26830935

  1. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    SciTech Connect

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Shiraki, D.; Eidietis, N. W.; Parks, P. B.; Lasnier, C. J.

    2015-10-15

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  2. Thermoluminescence response of flat optical fiber subjected to 9 MeV electron irradiations

    NASA Astrophysics Data System (ADS)

    Hashim, S.; Omar, S. S. Che; Ibrahim, S. A.; Hassan, W. M. S. Wan; Ung, N. M.; Mahdiraji, G. A.; Bradley, D. A.; Alzimami, K.

    2015-01-01

    We describe the efforts of finding a new thermoluminescent (TL) media using pure silica flat optical fiber (FF). The present study investigates the dose response, sensitivity, minimum detectable dose and glow curve of FF subjected to 9 MeV electron irradiations with various dose ranges from 0 Gy to 2.5 Gy. The above-mentioned TL properties of the FF are compared with commercially available TLD-100 rods. The TL measurements of the TL media exhibit a linear dose response over the delivered dose using a linear accelerator. We found that the sensitivity of TLD-100 is markedly 6 times greater than that of FF optical fiber. The minimum detectable dose was found to be 0.09 mGy for TLD-100 and 8.22 mGy for FF. Our work may contribute towards the development of a new dosimeter for personal monitoring purposes.

  3. The absorbed dose in femur exposed to diagnostic radiography.

    PubMed

    Salehi, Z; Yusoff, A L

    2013-01-01

    A femur phantom made of wax and a real human bone was used to study the dose during radiographical procedures. The depth dose inside the phantom was determined using DOSXYZnrc, a Monte Carlo simulation software. The results were verified with measurements using TLD-100H. It was found that for 2.5 mm aluminium filtered 84-kVp X-rays, the radiation dose in the bone reached 57 % higher than the surface dose, i.e. 3.23 mGy as opposed to 2.06 mGy at the surface. The use of real bone introduces variations in the bone density in the DOSXYZnrc model, resulting in a lower attenuation effect than expected from solid bone tissues. PMID:23012482

  4. Steady state γ-ray radiation effects on Brillouin fiber sensors

    NASA Astrophysics Data System (ADS)

    Cangialosi, C.; Girard, S.; Boukenter, A.; Marin, E.; Cannas, M.; Delepine-Lesoille, S.; Marcandella, C.; Paillet, P.; Ouerdane, Y.

    2015-09-01

    Brillouin optical time-domain analysis (BOTDA) sensors offer remarkable advantages for the surveillance of the planned French deep geological radioactive wastes repository, called Cigéo1,2. In this work we study the performances of Brillouin distributed sensors in harsh environment. We evaluate the radiation tolerance of different sensor classes and their responses evolution during γ-ray exposition with 1kGy/h dose rate (to reach ~0.2MGy) and after 1, 3, 6 and 10 MGy accumulated doses. Measurements on strained Ge-doped SMF are reported to highlight the variation on Brillouin scattering proprieties, both intrinsic frequency position of Brillouin shift and its dependence on temperature and strain.

  5. Disruption Mitigation Experiments Carried Out on DIII-D

    NASA Astrophysics Data System (ADS)

    Commaux, N.; Baylor, L. R.; Jernigan, T. C.; Evans, T. E.; Humphreys, D. A.; Parks, P. B.; van Zeeland, M. A.; Wesley, J. C.; Hollmann, E. M.; James, A. N.; Yu, J. H.

    2009-11-01

    Disruptions are an important issue for ITER. Major and vertical displacement disruptions in ITER are predicted to generate multi-MeV runaway electron beams (RE) as well as high energy flux to the plasma facing components and high halo currents in the structures that could potentially damage the machine. To mitigate these phenomena, several techniques have been studied on DIII-D: massive gas injection (MGI), external magnetic perturbation, and injection of large shattered cryogenic pellets. MGI, which is proven to mitigate heat fluxes and halo currents, has been tested on DIII-D in terms of impurity radiation toroidal symmetry and optimization of the gas pulse length. Other techniques expected to mitigate the RE have also been tested on DIII-D: deconfinement of the RE using external magnetic fields and collisionally damping the avalanche multiplication process by rapidly increasing the electron density in the core by several orders of magnitude using a new shotgun pellet injector built by ORNL.

  6. Thermoluminescence dosimetric properties and effective atomic numbers of window glass

    NASA Astrophysics Data System (ADS)

    Bootjomchai, Cherdsak; Laopaiboon, Raewat

    2014-03-01

    This work presents the main thermoluminescence (TL) dosimetric characteristics of commercial Thai transparent window glass. The amorphous structure of window glass was investigated by XRD. The glow curve revealed a peak (Tm) at 235 °C. The thermoluminescence response of window glass was studied after irradiation with photons in the absorb dose range of 0-14.05 mGy, which is of interest for the personal protection level of dosimetry. A linear response was obtained after both the first irradiation and the second irradiation. The minimum detectable dose of window glass was 0.15 mGy. The effective atomic number of window glass as a function of photon energy was calculated. The obtained results for the effective atomic number showed that it is very close to that of human biological tissues (Zeff = 6.7-8.4 at studied energy).

  7. The effect of electron irradiation on the structure and iron speciation in sodium aluminum (iron) phosphate glasses

    NASA Astrophysics Data System (ADS)

    Stefanovsky, S. V.; Presniakov, I. A.; Sobolev, A. V.; Glazkova, I. S.; Kadyko, M. I.; Stefanovsky, O. I.

    2016-08-01

    The effect of 8 MeV electron irradiation on the structure of glasses in the series 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 (mol.%) and on the iron speciation in these samples was studied by FTIR and Mössbauer spectroscopic techniques. Irradiation up to a dose of 1.0 MGy has no appreciable effects on the character of the bonds within anionic motif of the glass network. Electron irradiation increases the fraction of aluminum in octahedral coordination. Iron in both unirradiated and irradiated glasses is present mainly as Fe(III) (60-75% of the total amount) in the glasses and partly as Fe(II) and the ratio of two forms remains constant up to a dose of 1.0 MGy.

  8. Crystal Structures of Mutant Forms of the Yeast F[subscript 1] ATPase Reveal Two Modes of Uncoupling

    SciTech Connect

    Arsenieva, Diana; Symersky, Jindrich; Wang, Yamin; Pagadala, Vijayakanth; Mueller, David M.

    2010-11-15

    The mitochondrial ATP synthase couples the flow of protons with the phosphorylation of ADP. A class of mutations, the mitochondrial genome integrity (mgi) mutations, has been shown to uncouple this process in the yeast mitochondrial ATP synthase. Four mutant forms of the yeast F{sub 1} ATPase with mgi mutations were crystallized; the structures were solved and analyzed. The analysis identifies two mechanisms of structural uncoupling: one in which the empty catalytic site is altered and in doing so, apparently disrupts substrate (phosphate) binding, and a second where the steric hindrance predicted between {gamma}Leu83 and {beta}{sub DP} residues, Leu-391 and Glu-395, located in Catch 2 region, is reduced allowing rotation of the {gamma}-subunit with less impedance. Overall, the structures provide key insights into the critical interactions in the yeast ATP synthase involved in the coupling process.

  9. Combined electron-beam and adsorption purification of water from mercury and chromium using materials of vegetable origin as sorbents

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Bludenko, A. V.; Makarov, I. E.; Pikaev, A. K.; Kyung Kim, Duk; Kim, Yuri; Han, Bumsoo

    1997-04-01

    Combined electron-beam and adsorption method of purification of water from Hg(II) and Cr(VI) using materials of vegetable origin as sorbents was developed. It consists in the addition of materials of vegetable origin (e.g. cellulose, carboxymethyl cellulose, starch, and wheat flour) into water, subsequent electron-beam irradiation, sedimentation and filtration of additives with captured Hg(II) or Cr(VI). The method is based on the synergistic effect of the combined action of irradiation and sorbent. The best results were obtained with the wheat flour. For example, the addition of 25 mg/I of the flour to the water containing 1 mg/I Hg(II) and irradiation with dose 1.1 kGy upon bubbling inert gas through the system led to the 98% removal of the pollutant. The possible mechanism of the processes causing the purification of water is discussed.

  10. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    SciTech Connect

    Hollmann, E. M.; Commaux, Nicolas J. C.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, Daisuke

    2015-10-12

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. Furthermore, this IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  11. Discusión de las aproximaciones utilizadas en el estudio de la recombinación dielectrónica de los metales en envolturas estelares

    NASA Astrophysics Data System (ADS)

    Cruzado, A.; di Rocco, H. O.; Ringuelet, A.

    Se calcularon nuevos parámetros atómicos del MgI reemplazando los niveles de energía teóricos por los observados. Con ellos se calculó nuevamente el flujo originado en la Recombinación Dielectrónica (RD) del MgII y se comparó con resultados anteriores. Se evaluó también la posible influencia de diferentes fuentes de opacidad, en el flujo originado en la RD de los metales en atmósferas extendidas de estrellas tempranas. En particular, se calculó la profundidad óptica de las líneas de MgI para diferentes condiciones físicas del medio.

  12. First demonstration of rapid shutdown using neon shattered pellet injection for thermal quench mitigation on DIII-D

    NASA Astrophysics Data System (ADS)

    Commaux, N.; Shiraki, D.; Baylor, L. R.; Hollmann, E. M.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Jernigan, T. C.; Meitner, S. J.; Combs, S. K.; Foust, C. R.

    2016-04-01

    Shattered pellet injection (SPI) is one of the prime candidates for the ITER disruption mitigation system because of its deeper penetration and larger particle flux than massive gas injection (MGI) (Taylor et al 1999 Phys. Plasmas 6 1872) using deuterium (Commaux et al 2010 Nucl. Fusion 50 112001, Combs et al 2010 IEEE Trans. Plasma Sci. 38 400, Baylor et al 2009 Nucl. Fusion 49 085013). The ITER disruption mitigation system will likely use mostly high Z species such as neon because of more effective thermal mitigation and pumping constraints on the maximum amount of deuterium or helium that could be injected. An upgrade of the SPI on DIII-D enables ITER relevant injection characteristics in terms of quantities and gas species. This upgraded SPI system was used on DIII-D for the first time in 2014 for a direct comparison with MGI using identical quantities of neon. This comparison enabled the measurements of density perturbations during the thermal quench (TQ) and radiated power and heat loads to the divertor. It showed that SPI using similar quantities of neon provided a faster and stronger density perturbation and neon assimilation, which resulted in a lower conducted energy to the divertor and a faster TQ onset. Radiated power data analysis shows that this was probably due to the much deeper penetration of the neon in the plasma inducing a higher core radiation than in the MGI case. This experiment shows also that the MHD activity during an SPI shutdown (especially during the TQ) is quite different compared to MGI. This favorable TQ energy dissipation was obtained while keeping the current quench (CQ) duration within acceptable limits when scaled to ITER.

  13. Fast accretion of the earth with a late moon-forming giant impact.

    PubMed

    Yu, Gang; Jacobsen, Stein B

    2011-10-25

    Constraints on the formation history of the Earth are critical for understanding of planet formation processes. (182)Hf-(182)W chronometry of terrestrial rocks points to accretion of Earth in approximately 30 Myr after the formation of the solar system, immediately followed by the Moon-forming giant impact (MGI). Nevertheless, some N-body simulations and (182)Hf-(182)W and (87)Rb-(87)Sr chronology of some lunar rocks have been used to argue for a later formation of the Moon at 52 to > 100 Myr. This discrepancy is often explained by metal-silicate disequilibrium during giant impacts. Here we describe a model of the (182)W isotopic evolution of the accreting Earth, including constraints from partitioning of refractory siderophile elements (Ni, Co, W, V, and Nb) during core formation, which can explain the discrepancy. Our modeling shows that the concentrations of the siderophile elements of the mantle are consistent with high-pressure metal-silicate equilibration in a terrestrial magma ocean. Our analysis shows that the timing of the MGI is inversely correlated with the time scale of the main accretion stage of the Earth. Specifically, the earliest time the MGI could have taken place right at approximately 30 Myr, corresponds to the end of main-stage accretion at approximately 30 Myr. A late MGI (> 52 Myr) requires the main stage of the Earth's accretion to be completed rapidly in < 10.7 ± 2.5 Myr. These are the two end member solutions and a continuum of solutions exists in between these extremes. PMID:22006299

  14. Formal Asymmetric (4+1) Annulation Reaction between Sulfur Ylides and 1,3-Dienes.

    PubMed

    Rousseau, Olivier; Delaunay, Thierry; Dequirez, Geoffroy; Trieu-Van, Tran; Robeyns, Koen; Robiette, Raphaël

    2015-09-01

    A highly enantioselective synthesis of functionalized cyclopentanoids by a formal asymmetric (4+1) annulation strategy was developed. The methodology consists of a stereoselective cyclopropanation reaction between chiral sulfur ylides and 1,3-dienes followed by a, in situ, stereospecific MgI2 -catalyzed rearrangement of vinylcyclopropanes. This method is distinguished by a remarkable compatibility with functional groups and a high stereocontrol. PMID:26235566

  15. Comparison of slot scanning digital mammography system with full-field digital mammography system

    SciTech Connect

    Lai, C.-J.; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T.

    2008-06-15

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125-160 and 200-250 {mu}m calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose/50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (A{sub z}) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher A{sub z}'s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant.

  16. Effect of Body Habitus on Radiation Dose During CT Fluoroscopy-Guided Spine Injections.

    PubMed

    Viola, Ronald J; Nguyen, Giao B; Yoshizumi, Terry T; Stinnett, Sandra S; Hoang, Jenny K; Kranz, Peter G

    2014-10-31

    This study investigated the degree to which body habitus influences radiation dose during CT fluoroscopy (CTF)-guided lumbar epidural steroid injections (ESI). An anthropomorphic phantom containing metal oxide semiconductor field effect transistor (MOSFET) detectors was scanned at two transverse levels to simulate upper and lower lumbar CTF-guided ESI. Circumferential layers of adipose-equivalent material were sequentially added to model patients of three sizes: small (cross-sectional dimensions 25×30 cm), average (34×39 cm), and oversize (43×48 cm). Point dose rates to skin and internal organs within the CTF beam were measured. Scattered point dose rates 5 cm from the radiation beam were also measured. Direct point dose rates to the internal organs ranged from 0.05-0.11 mGy/10mAs in the oversized phantom, and from 0.18-0.43 mGy/10mAs in the small phantom. Skin direct point dose rates ranged from 0.69-0.71 mGy/10mAs in the oversized phantom and 0.88-0.94 mGy/10mAs in the small phantom. This represents a 180-310% increase in organ point dose rates and 24-36% increase in skin point dose rates in the small habitus compared with the oversize habitus. Scatter point dose rates increased by 83-117% for the small compared to the oversize phantom. Decreasing body habitus results in substantial increases in direct organ and skin point doses as well as scattered dose during simulated CTF-guided procedures. Failure to account for individual variations in body habitus will result in inaccurate dose estimation and inappropriate choice of tube current in CTF-guided procedures. PMID:25363254

  17. Cosmic Radiation Exposure of Biological Test Systems During the EXPOSE-E Mission

    PubMed Central

    Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

    2012-01-01

    Abstract In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5–12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples. Key Words: Space radiation—Dosimetry—Passive radiation detectors—Thermoluminescence—EXPOSE-E. Astrobiology 12, 387–392. PMID:22680685

  18. Radiation dose to patients from the Philips CT scanner

    SciTech Connect

    Badcock, P.C.

    1985-07-01

    While the anthropomorphic phantom is useful in radiotherapy dosimetry, corrections for diagnostic qualities of radiation are necessary for departures from tissue-equivalence. TLD measurements were performed for this reason in the rectum of patients undergoing CT scanning of the pelvis. At high slice densities the energy imparted becomes comparable with that associated with fluoroscopic examinations of the abdomen. At low slice densities the average dose is ca 12 mGy.

  19. Towards proposition of a diagnostic reference level for mammographic examination in the greater Khorasan Province, Iran.

    PubMed

    Bahreyni Toossi, M T; Zare, H; Bayani Roodi, Sh; Hashemi, M; Akbari, F; Malekzadeh, M

    2013-06-01

    Although, over the past few years, the application of mammography has risen up sharply in Iran, very little, if any, has been reported of the extent of patient's dose from this type of imaging. The purpose of this study was to establish local diagnostic reference level (DRL) arising from mammography in the great Khorasan province of Iran. It is generally assumed that the glandular tissue is the most vulnerable type of breast tissue. Therefore, the mean glandular dose (MGD) has been widely accepted as the most appropriate dosimetric quantity to predict the risk of radiation-induced cancer. Literary, DRL for mammography is defined as the 75th percentile of MGD distribution. In Khorasan province, 7 out of 40 centres were randomly selected. In this work, 100 patients were studied. Thermoluminescence dosimeters have been used to measure entrance surface doses (ESDs). Since, it is difficult to directly measure MGD, Monte Carlo model-based conversion factors were utilised to conclude MGD from ESD. The results have revealed that patients dose is varied widely. The measured ESDs ranged from 0.74 to 19.81 mGy for the craniocaudal (CC) view and 1.20 to 25.79 mGy for the mediolateral oblique (MLO) view. The average MGDs per image were 0.88 and 1.11 mGy for CC and MLO views, respectively. Based on the internationally adopted definition, DRL arising from mammography tests for Khorasan is 1.33 mGy. Implementation of a dose reduction programme is suggested because of the large variations observed in patient MGD values. In this study, the DRL value is significantly lower than the corresponding values suggested by other researchers elsewhere. PMID:23209184

  20. Computation of thyroid doses and carcinogenic radiation risks to patients undergoing neck CT examinations.

    PubMed

    Huda, Walter; Spampinato, Maria V; Tipnis, Sameer V; Magill, Dennise

    2013-10-01

    The aim of the study was to investigate how differences in patient anatomy and CT technical factors in neck CT impact on thyroid doses and the corresponding carcinogenic risks. The CTDIvol and dose-length product used in 11 consecutive neck CT studies, as well as data on automatic exposure control (AEC) tube current variation(s) from the image DICOM header, were recorded. For each CT image that included the thyroid, the mass equivalent water cylinder was estimated based on the patient cross-sectional area and average relative attenuation coefficient (Hounsfield unit, HU). Patient thyroid doses were estimated by accounting for radiation intensity at the location of the patient's thyroid, patient size and the scan length. Thyroid doses were used to estimate thyroid cancer risks as a function of patient demographics using risk factors in BEIR VII. The length of the thyroid glands ranged from 21 to 54 mm with an average length of 42 ± 12 mm. Water cylinder diameters corresponding to the central slice through the patient thyroid ranged from 18 to 32 cm with a mean of 25 ± 5 cm. The average CTDIvol (32-cm phantom) used to perform these scans was 26 ± 6 mGy, but the use of an AEC increased the tube current by an average of 44 % at the thyroid mid-point. Thyroid doses ranged from 29 to 80 mGy, with an average of 55 ± 19 mGy. A 20-y-old female receiving the highest thyroid dose of 80 mGy would have a thyroid cancer risk of nearly 0.1 %, but radiation risks decreased very rapidly with increasing patient age. The key factors that affect thyroid doses in neck CT examinations are the radiation intensity at the thyroid location and the size of the patient. The corresponding patient thyroid cancer risk is markedly influenced by patient sex and age. PMID:23579263

  1. Radiation dose evaluation in 64-slice CT examinations with adult and paediatric anthropomorphic phantoms.

    PubMed

    Fujii, K; Aoyama, T; Yamauchi-Kawaura, C; Koyama, S; Yamauchi, M; Ko, S; Akahane, K; Nishizawa, K

    2009-12-01

    The objective of this study was to evaluate the organ dose and effective dose to patients undergoing routine adult and paediatric CT examinations with 64-slice CT scanners and to compare the doses with those from 4-, 8- and 16-multislice CT scanners. Patient doses were measured with small (<7 mm wide) silicon photodiode dosemeters (34 in total), which were implanted at various tissue and organ positions within adult and 6-year-old child anthropomorphic phantoms. Output signals from photodiode dosemeters were read on a personal computer, from which organ and effective doses were computed. For the adult phantom, organ doses (for organs within the scan range) and effective doses were 8-35 mGy and 7-18 mSv, respectively, for chest CT, and 12-33 mGy and 10-21 mSv, respectively, for abdominopelvic CT. For the paediatric phantom, organ and effective doses were 4-17 mGy and 3-7 mSv, respectively, for chest CT, and 5-14 mGy and 3-9 mSv, respectively, for abdominopelvic CT. Doses to organs at the boundaries of the scan length were higher for 64-slice CT scanners using large beam widths and/or a large pitch because of the larger extent of over-ranging. The CT dose index (CTDI(vol)), dose-length product (DLP) and the effective dose values using 64-slice CT for the adult and paediatric phantoms were the same as those obtained using 4-, 8- and 16-slice CT. Conversion factors of DLP to the effective dose by International Commission on Radiological Protection 103 were 0.024 mSvmGy(-1)cm(-1) and 0.019 mSvmGy(-1)cm(-1) for adult chest and abdominopelvic CT scans, respectively. PMID:19934069

  2. The feasibility of refuse-fired energy generation in Philadelphia, Pennsylvania

    NASA Astrophysics Data System (ADS)

    Christman, W. M., III

    1982-02-01

    The City of Philadelphia presently disposes of 816, 480 megagrams per year (MGY) of residential refuse, with 1 megagram = 10 to the 3rd power hilograms. Alternatives to a base case of continued incineration and landfilling are evaluated. It is assured that the feasibility studies will yield compatible products and will run a uniform economic analysis against the base case, using as inputs the outputs of the feasibility analyses.

  3. First demonstration of rapid shutdown using neon shattered pellet injection for thermal quench mitigation on DIII-D

    DOE PAGESBeta

    Commaux, Nicolas J. C.; Shiraki, Daisuke; Baylor, Larry R.; Hollmann, E. M.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Jernigan, T. C.; Meitner, S. J.; Combs, Stephen Kirk; et al

    2016-03-02

    Shattered pellet injection (SPI) is one of the prime candidates for the ITER disruption mitigation system because of its deeper penetration and larger particle flux than massive gas injection (MGI) (Taylor et al 1999 Phys. Plasmas 6 1872) using deuterium (Commaux et al 2010 Nucl. Fusion 50 112001, Combs et al 2010 IEEE Trans. Plasma Sci. 38 400, Baylor et al 2009 Nucl. Fusion 49 085013). The ITER disruption mitigation system will likely use mostly high Z species such as neon because of more effective thermal mitigation and pumping constraints on the maximum amount of deuterium or helium that couldmore » be injected. An upgrade of the SPI on DIII-D enables ITER relevant injection characteristics in terms of quantities and gas species. This upgraded SPI system was used on DIII-D for the first time in 2014 for a direct comparison with MGI using identical quantities of neon. This comparison enabled the measurements of density perturbations during the thermal quench (TQ) and radiated power and heat loads to the divertor. It showed that SPI using similar quantities of neon provided a faster and stronger density perturbation and neon assimilation, which resulted in a lower conducted energy to the divertor and a faster TQ onset. Radiated power data analysis shows that this was probably due to the much deeper penetration of the neon in the plasma inducing a higher core radiation than in the MGI case. This experiment shows also that the MHD activity during an SPI shutdown (especially during the TQ) is quite different compared to MGI. Furthermore, this favorable TQ energy dissipation was obtained while keeping the current quench (CQ) duration within acceptable limits when scaled to ITER.« less

  4. Identification of Emission Lines in a Meteor Spectrum Obtained on August 2, 2011

    NASA Astrophysics Data System (ADS)

    Mozgova, A. M.; Borovicka, J.; Spurny, P.; Churyumov, K. I.

    125 emission lines were found in a meteor spectrum obtained on August 2, 2011. The identification of most of the lines is given. The following species were found in the spectrum: CrI, FeI, MgI, SiI, AlI, MnI, CaI, TiI, NaI, FeII, CaII, MgII, SiII, SrII.

  5. Exposure factors and screen-film combinations in temporomandibular joint radiography.

    PubMed

    Thorburn, D N; Stockdill, D A; Kenyon, R P; Cowan, I; Ferguson, M M

    1991-05-01

    Exposure factors and screen-film combinations providing optimal quality are identified for transcranial and transpharyngeal temporomandibular joint views, using conventional intra-oral radiographic equipment without grids. Standardized transcranial and transpharyngeal views, using a fixed whole cadaver head, were performed. Ten readily available screen-film combinations, ranging in nominal speed 20-600, were exposed over 40-100 kV. Films were blindly and independently order ranked by three observers on the basis of sharpness and contrast of cortical outline, trabecular detail, and visualization of adjacent bony structures. Preferred screen-film combinations as a function of kV, preferred kV levels for each screen-film combination, and overall ranking irrespective of kV or screen-film combination, were established. Accepting the use of the lowest radiation dose possible for diagnostically useful radiographs but imposing arbitrarily an upper limit of 20 mGy, it was found that exposures between 50 kV and 70 kV gave the optimal result for both techniques. The amount of scattered radiation in the emergent beam differs greatly between the two techniques. The most favoured combinations for the transpharyngeal technique used screens of fine resolution. Min-r/ortho M screen and film with nominal speed 40 at 60 kV gave 8.0 mGy skin dosage at 0.8 seconds exposure; the same combination at 50 kV was the most favoured, but with skin dosage calculated at 16.7 mGy for 3.0 seconds exposure. For the transcranial technique, medium speed screens providing better differentiation of scattered radiation beams and increased speeds were preferred. Most favoured for image quality was the Lanex Fine/T-Mat G combination at 60 kV giving 17.5 mGy skin radiation dose at 1.75 seconds exposure.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1936423

  6. Dose-rate effects of protons on in vivo activation of nuclear factor-kappa B and cytokines in mouse bone marrow cells

    SciTech Connect

    Rithidech, K.N.; Rusek, A.; Reungpatthanaphong, P.; Honikel, L.; Simon, S.R.

    2010-05-28

    The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-{kappa}B) activation and cytokine expression in bone marrow (BM) cells of exposed mice as a function of the dose rate of protons. The cytokines included in this study are pro-inflammatory [i.e., tumor necrosis factor-alpha (TNF-{alpha}), interleukin-1beta (IL-1{beta}), and IL-6] and anti-inflammatory cytokines (i.e., IL-4 and IL-10). We gave male BALB/cJ mice a whole-body exposure to 0 (sham-controls) or 1.0 Gy of 100 MeV protons, delivered at 5 or 10 mGy min{sup -1}, the dose and dose rates found during solar particle events in space. As a reference radiation, groups of mice were exposed to 0 (sham-controls) or 1 Gy of {sup 137}Cs {gamma} rays (10 mGy min{sup -1}). After irradiation, BM cells were collected at 1.5, 3, 24 h, and 1 month for analyses (five mice per treatment group per harvest time). The results indicated that the in vivo time course of effects induced by a single dose of 1 Gy of 100 MeV protons or {sup 137}Cs {gamma} rays, delivered at 10 mGy min{sup -1}, was similar. Although statistically significant levels of NF-{kappa}B activation and pro-inflammatory cytokines in BM cells of exposed mice when compared to those in the corresponding sham controls (Student's t-test, p < 0.05 or < 0.01) were induced by either dose rate, these levels varied over time for each protein. Further, only a dose rate of 5 mGy min{sup -1} induced significant levels of anti-inflammatory cytokines. The results indicate dose-rate effects of protons.

  7. Studies of adaptive response and mutation induction in MCF-10A cells following exposure to chronic or acute ionizing radiation.

    PubMed

    Manesh, Sara Shakeri; Sangsuwan, Traimate; Wojcik, Andrzej; Haghdoost, Siamak

    2015-10-01

    A phenomenon in which exposure to a low adapting dose of radiation makes cells more resistant to the effects of a subsequent high dose exposure is termed radio-adaptive response. Adaptive response could hypothetically reduce the risk of late adverse effects of chronic or acute radiation exposures in humans. Understanding the underlying mechanisms of such responses is of relevance for radiation protection as well as for the clinical applications of radiation in medicine. However, due to the variability of responses depending on the model system and radiation condition, there is a need to further study under what conditions adaptive response can be induced. In this study, we analyzed if there is a dose rate dependence for the adapting dose, assuming that the adapting dose induces DNA response/repair pathways that are dose rate dependent. MCF-10A cells were exposed to a 50mGy adapting dose administered acutely (0.40Gy/min) or chronically (1.4mGy/h or 4.1mGy/h) and then irradiated by high acute challenging doses. The endpoints of study include clonogenic cell survival and mutation frequency at X-linked hprt locus. In another series of experiment, cells were exposed to 100mGy and 1Gy at different dose rates (acutely and chronically) and then the mutation frequencies were studied. Adaptive response was absent at the level of clonogenic survival. The mutation frequencies were significantly decreased in the cells pre-exposed to 50mGy at 1.4mGy/h followed by 1Gy acute exposure as challenging dose. Importantly, at single dose exposures (1 Gy or 100mGy), no differences at the level of mutation were found comparing different dose rates. PMID:26295444

  8. Effect of gamma-ray irradiation on structural properties of GaAsN films grown by metal organic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Klangtakai, Pawinee; Sanorpim, Sakuntam; Wattanawareekul, Atiwat; Suwanyangyaun, Pattana; Srepusharawoot, Pornjuk; Onabe, Kentaro

    2015-05-01

    The effects of gamma-ray irradiation on the structural properties of GaAs1-xNx films (N concentration=1.9 and 5.1 at%) grown by metal organic vapor phase epitaxy on GaAs (001) substrates were investigated. The GaAs1-xNx films were irradiated by gamma rays with irradiation strength of 0-2.0 MGy. Scanning electron microscopy and atomic force microscopy results showed that a gamma ray with a strength of 0, 0.5, 1.0, 1.5, and 2.0 MGy formed holes with a density of 0.0, 8.8, 9.4, 11.5, and 11.9 μm-2, respectively, on the surface of a GaAs0.981N0.019 film with low N content. On the other hand, the irradiated high-N-content GaAs0.949N0.051 film exhibited a cross-hatch pattern, which was induced by partial strain relaxation at high N levels, with a line density of 0.0, 0.21, 0.37, 0.67, and 0.26 μm-1 corresponding to an irradiation strength of 0, 0.5, 1.0, 1.5, and 2.0 MGy, respectively. The high-resolution X-ray diffraction and Raman scattering results revealed an increase in N incorporation and strain relaxation after irradiation. In addition, the GaAs0.949N0.051 films exhibited phase separation, which took place via N out-diffusion across the interface when the irradiation strength exceeded 1.0 MGy. Based on these results, the main cause of structural change was determined to be the irradiation effects including displacement damage and gamma-ray heating.

  9. Performance of Bragg and long-period gratings written in N- and Ge-doped silica fibers under {gamma}-radiation

    SciTech Connect

    Vasilev, S.A.; Dianov, E.M.; Golant, K.M.

    1998-06-01

    In-fiber Bragg and long-period gratings as well as Mach-Zehnder interferometers based on germanium- and nitrogen-doped silica fibers have been investigated under {gamma}-rays. The majority of the experimental results suggest that both types of gratings in both types of fibers are stable with respect to {gamma}-ray doses of up to 1.47 MGy.

  10. Comparison of slot scanning digital mammography system with full-field digital mammography system

    PubMed Central

    Lai, Chao-Jen; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T.

    2008-01-01

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125–160 and 200–250 μm calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose∕50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (Az) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher Az’s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant. PMID:18649467

  11. Penalized maximum likelihood reconstruction for improved microcalcification detection in breast tomosynthesis.

    PubMed

    Das, Mini; Gifford, Howard C; O'Connor, J Michael; Glick, Stephen J

    2011-04-01

    We examined the application of an iterative penalized maximum likelihood (PML) reconstruction method for improved detectability of microcalcifications (MCs) in digital breast tomosynthesis (DBT). Localized receiver operating characteristic (LROC) psychophysical studies with human observers and 2-D image slices were conducted to evaluate the performance of this reconstruction method and to compare its performance against the commonly used Feldkamp FBP algorithm. DBT projections were generated using rigorous computer simulations that included accurate modeling of the noise and detector blur. Acquisition dose levels of 0.7, 1.0, and 1.5 mGy in a 5-cm-thick compressed breast were tested. The defined task was to localize and detect MC clusters consisting of seven MCs. The individual MC diameter was 150 μm. Compressed-breast phantoms derived from CT images of actual mastectomy specimens provided realistic background structures for the detection task. Four observers each read 98 test images for each combination of reconstruction method and acquisition dose. All observers performed better with the PML images than with the FBP images. With the acquisition dose of 0.7 mGy, the average areas under the LROC curve (A(L)) for the PML and FBP algorithms were 0.69 and 0.43, respectively. For the 1.0-mGy dose, the values of A(L) were 0.93 (PML) and 0.7 (FBP), while the 1.5-mGy dose resulted in areas of 1.0 and 0.9, respectively, for the PML and FBP algorithms. A 2-D analysis of variance applied to the individual observer areas showed statistically significant differences (at a significance level of 0.05) between the reconstruction strategies at all three dose levels. There were no significant differences in observer performance for any of the dose levels. PMID:21041158

  12. Evaluation of surface radiation dose to the thyroid gland and the gonads during routine full-mouth intraoral periapical and maxillary occlusal radiography

    PubMed Central

    Sheikh, Soheyl; Bhoweer, Anil Kumar; Arya, Smriti; Arora, Gagandeep

    2010-01-01

    Aim: The quantitative aspects of radiation doses to critical organs can help the dental professionals to take the necessary radiation protective measures as deemed necessary and can help the general public to allay radiation exposure fear in dental radiography, if any. Our study determines the surface radiation dose to thyroid and gonads in full-mouth intraoral periapical (IOPA) and maxillary occlusal radiography. Materials and Methods: A total number of 120 subjects participated in the study. The surface radiation dose was estimated to the thyroid gland and the gonads in full-mouth IOPA radiography using 10 IOPA (E speed films) and in maxillary occlusal radiography. The measurements were calculated using a digital pocket dosimeter (PD-4507). Results: The average dose at the thyroid gland level during full-mouth intraoral and maxillary occlusal radiography was estimated to be 10.93 mRads (1.093 × 10-2 mGy) and 0.4 mRads (4.0 × 10-2 mGy), respectively. The average surface radiation dose at the gonadal region during a full mouth intraoral and maxillary occlusal radiography was estimated to be 1.5 mRads (1.5 × 10-2 mGy) and 0.15 mRads (1.5 × 10-3 mGy), respectively. Conclusion: Our results suggest that although the radiation exposure doses to critical organs namely thyroid and gonads is within the safe limits still precautionary measures for these organs are advocated. PMID:22114389

  13. Genome-enabled transcriptomics reveals archaeal populations that drive nitrification in a deep-sea hydrothermal plume

    PubMed Central

    Baker, Brett J; Lesniewski, Ryan A; Dick, Gregory J

    2012-01-01

    Ammonia-oxidizing Archaea (AOA) are among the most abundant microorganisms in the oceans and have crucial roles in biogeochemical cycling of nitrogen and carbon. To better understand AOA inhabiting the deep sea, we obtained community genomic and transcriptomic data from ammonium-rich hydrothermal plumes in the Guaymas Basin (GB) and from surrounding deep waters of the Gulf of California. Among the most abundant and active lineages in the sequence data were marine group I (MGI) Archaea related to the cultured autotrophic ammonia-oxidizer, Nitrosopumilus maritimus. Assembly of MGI genomic fragments yielded 2.9 Mb of sequence containing seven 16S rRNA genes (95.4–98.4% similar to N. maritimus), including two near-complete genomes and several lower-abundance variants. Equal copy numbers of MGI 16S rRNA genes and ammonia monooxygenase genes and transcription of ammonia oxidation genes indicates that all of these genotypes actively oxidize ammonia. De novo genomic assembly revealed the functional potential of MGI populations and enhanced interpretation of metatranscriptomic data. Physiological distinction from N. maritimus is evident in the transcription of novel genes, including genes for urea utilization, suggesting an alternative source of ammonia. We were also able to determine which genotypes are most active in the plume. Transcripts involved in nitrification were more prominent in the plume and were among the most abundant transcripts in the community. These unique data sets reveal populations of deep-sea AOA thriving in the ammonium-rich GB that are related to surface types, but with key genomic and physiological differences. PMID:22695863

  14. Cosmic radiation exposure of biological test systems during the EXPOSE-E mission.

    PubMed

    Berger, Thomas; Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

    2012-05-01

    In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5-12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples. PMID:22680685

  15. Effectiveness of fluorography versus cineangiography at reducing radiation exposure during diagnostic coronary angiography.

    PubMed

    Shah, Binita; Mai, Xingchen; Tummala, Lakshmi; Kliger, Chad; Bangalore, Sripal; Miller, Louis H; Sedlis, Steven P; Feit, Frederick; Liou, Michael; Attubato, Michael; Coppola, John; Slater, James

    2014-04-01

    Coronary angiography is the gold standard for defining obstructive coronary disease. However, radiation exposure remains an unwanted hazard. Patients referred for coronary angiography with abdominal circumference<45 inches and glomerular filtration rate>60 ml/min were randomized to the fluorography (n=25) or cineangiography (n=25) group. Patients in the fluorography group underwent coronary angiography using retrospectively stored fluorography with repeat injection under cineangiography only when needed for better resolution per operator's discretion. Patients in the cineangiography group underwent coronary angiography using routine cineangiography. The primary end point was patient radiation exposure measured by radiochromic film. Secondary end points included the radiation output measurement of kerma-area product and air kerma at the interventional reference point (Ka,r) and operator radiation exposure measured by a dosimeter. Patient radiation exposure (158.2 mGy [76.5 to 210.2] vs 272.5 mGy [163.3 to 314.0], p=0.001), kerma-area product (1,323 μGy·m2 [826 to 1,765] vs 3,451 μGy·m2 [2,464 to 4,818], p<0.001), and Ka,r (175 mGy [112 to 252] vs 558 mGy [313 to 621], p<0.001) were significantly lower in the fluorography compared with cineangiography group (42%, 62%, and 69% relative reduction, respectively). Operator radiation exposure trended in the same direction, although statistically nonsignificant (fluorography 2.35 μGy [1.24 to 6.30] vs cineangiography 5.03 μGy [2.48 to 7.80], p=0.059). In conclusion, the use of fluorography in a select group of patients during coronary angiography, with repeat injection under cineangiography only when needed, was efficacious at reducing patient radiation exposure. PMID:24513469

  16. Radiation dose evaluation in 64-slice CT examinations with adult and paediatric anthropomorphic phantoms

    PubMed Central

    Fujii, K; Aoyama, T; Yamauchi-Kawaura, C; Koyama, S; Yamauchi, M; Ko, S; Akahane, K; Nishizawa, K

    2009-01-01

    The objective of this study was to evaluate the organ dose and effective dose to patients undergoing routine adult and paediatric CT examinations with 64-slice CT scanners and to compare the doses with those from 4-, 8- and 16-multislice CT scanners. Patient doses were measured with small (<7 mm wide) silicon photodiode dosemeters (34 in total), which were implanted at various tissue and organ positions within adult and 6-year-old child anthropomorphic phantoms. Output signals from photodiode dosemeters were read on a personal computer, from which organ and effective doses were computed. For the adult phantom, organ doses (for organs within the scan range) and effective doses were 8–35 mGy and 7–18 mSv, respectively, for chest CT, and 12–33 mGy and 10–21 mSv, respectively, for abdominopelvic CT. For the paediatric phantom, organ and effective doses were 4–17 mGy and 3–7 mSv, respectively, for chest CT, and 5–14 mGy and 3–9 mSv, respectively, for abdominopelvic CT. Doses to organs at the boundaries of the scan length were higher for 64-slice CT scanners using large beam widths and/or a large pitch because of the larger extent of over-ranging. The CT dose index (CTDIvol), dose–length product (DLP) and the effective dose values using 64-slice CT for the adult and paediatric phantoms were the same as those obtained using 4-, 8- and 16-slice CT. Conversion factors of DLP to the effective dose by International Commission on Radiological Protection 103 were 0.024 mSv⋅mGy−1⋅cm−1 and 0.019 mSv⋅mGy−1⋅cm−1 for adult chest and abdominopelvic CT scans, respectively. PMID:19934069

  17. Comparison of measured and estimated maximum skin doses during CT fluoroscopy lung biopsies

    SciTech Connect

    Zanca, F.; Jacobs, A.; Crijns, W.; De Wever, W.

    2014-07-15

    Purpose: To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. Methods: Data from 50 patients with lung lesions who underwent a CT fluoroscopy-guided biopsy were collected. The CT protocol consisted of a low-kilovoltage (80 kV) protocol used in combination with an algorithm for dose reduction to the radiology staff during the interventional procedure, HandCare (HC). MSD was assessed during each intervention using EBT2 gafchromic films positioned on patient skin. Lesion size, position, total fluoroscopy time, and patient-effective diameter were registered for each patient. Dose rates were also estimated at the surface of a normal-size anthropomorphic thorax phantom using a 10 cm pencil ionization chamber placed at every 30°, for a full rotation, with and without HC. Measured MSD was compared with MSD values estimated from the phantom measurements and with the cumulative CTDIvol of the procedure. Results: The median measured MSD was 141 mGy (range 38–410 mGy) while the median cumulative CTDIvol was 72 mGy (range 24–262 mGy). The ratio between the MSD estimated from phantom measurements and the measured MSD was 0.87 (range 0.12–4.1) on average. In 72% of cases the estimated MSD underestimated the measured MSD, while in 28% of the cases it overestimated it. The same trend was observed for the ratio of cumulative CTDIvol and measured MSD. No trend was observed as a function of patient size. Conclusions: On average, estimated MSD from dose rate measurements on phantom as well as from CTDIvol of patient examinations underestimates the measured value of MSD. This can be attributed to deviations of the patient's body habitus from the standard phantom size and to patient positioning in the gantry during the procedure.

  18. Runaway beam studies during disruptions at JET-ILW

    NASA Astrophysics Data System (ADS)

    Reux, C.; Plyusnin, V.; Alper, B.; Alves, D.; Bazylev, B.; Belonohy, E.; Brezinsek, S.; Decker, J.; Devaux, S.; de Vries, P.; Fil, A.; Gerasimov, S.; Lupelli, I.; Jachmich, S.; Khilkevitch, E. M.; Kiptily, V.; Koslowski, R.; Kruezi, U.; Lehnen, M.; Manzanares, A.; Mlynář, J.; Nardon, E.; Nilsson, E.; Riccardo, V.; Saint-Laurent, F.; Shevelev, A. E.; Sozzi, C.

    2015-08-01

    Runaway electrons (RE) during disruptions are a concern for future tokamaks including ITER with its metallic wall. Although RE are rare in spontaneous disruptions with the JET ITER-like Wall (JET-ILW), RE beams up to 380 kA were obtained using massive injection (MGI) of argon in JET-ILW divertor discharges. Entry points into the RE domain defined by operational parameters (toroidal field, argon fraction in MGI) are unchanged but higher RE currents have been obtained inside the JET-ILW MGI-generated RE domain when compared to JET-C. This might be due to the influence of the metallic wall on the current quench plasma. Temperatures of 900 °C have been observed following RE impacts on beryllium tiles. Heat deposition depth of ∼2 mm has to be assumed to match the tile cooling time. 3D simulations of the RE energy deposition using the ENDEP/MEMOS codes show that material melting is unlikely with 100 kA RE beams.

  19. High-performance soft-tissue imaging in extremity cone-beam CT

    NASA Astrophysics Data System (ADS)

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Muhit, A.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2014-03-01

    Purpose: Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. Methods: The accelerated MC scatter correction involved fast MC simulation with low number of photons implemented on a GPU (107 photons/sec), followed by Gaussian kernel smoothing in the detector plane and across projection angles. PL reconstructions were investigated for reduction of imaging dose for projections acquired at ~2 mGy. Results: The rapid scatter estimation yielded root-mean-squared-errors of scatter projections of ~15% of peak scatter intensity for 5ṡ106 photons/projection (runtime ~0.5 sec/projection) and 25% improvement in fat-muscle contrast in reconstructions of a cadaveric knee. PL reconstruction largely restored soft-tissue visualization at 2 mGy dose to that of 10 mGy FBP image. Conclusion: The combination of rapid (5-10 minutes/scan) MC-based, patient-specific scatter correction and PL reconstruction offers an important means to overcome the current limitations of extremity CBCT in soft-tissue imaging.

  20. Low radiation doses; are they harmful in infancy?

    PubMed

    Asteriadis, Ioannis

    2004-01-01

    Adults usually ask their physician about the kind of treatment they will be given and especially whether ionizing radiation applied for therapeutic purposes is harmful. When these treatments are applied to children and especially to infants of <18 months of age, parents should be more reluctant to give their consent for such a treatment. A paper under the title "Effect of low doses of ionizing radiation in infancy on cognitive function in adulthood: Swedish population based cohort study" written by Hall P, Adami HO, Trichopoulos D, et al. and published in the British Journal of Medicine 2004, 328:19-21 presents new and important data referring to 3094 males who at an age of <18 months had undergone radiation treatment for haemangiomas of the head and other dermatological lesions. The doses they received in their brain were from 20 mGy to > 250 mGy. Findings were exciting. 17%-32% of these infants did not attend highschool lessons. Many failed to pass tests related to cognitive tests for learning ability or logical reasoning. On the contrary spatial recognition was intact. As the authors state it is important to know that a cranial tomography examination administers to the brain of infants about 120 mGy. These doses are relevant to the doses tested above and found harmful. More radiation protection studies about the possible harmful effects on humans who receive doses of radiation for diagnostic and/or therapeutic purposes, are necessary. PMID:16868634

  1. Direct observation of solid-state reversed transformation from crystals to quasicrystals in a Mg alloy

    PubMed Central

    Liu, Jian-Fang; Yang, Zhi-Qing; Ye, Heng-Qiang

    2015-01-01

    Phase transformation of quasicrystals is of interest in various fields of science and technology. Interestingly, we directly observed unexpected solid-state epitaxial nucleation and growth of Zn 6 Mg 3 Y icosahedral quasicrystals in a Mg alloy at about 573 K which is about 300 K below the melting point of Zn 6 Mg 3 Y, in contrast to formation of quasicrystals through solidification that was usually found in many alloys. Maximizing local packing density of atoms associated with segregation of Y and Zn in Mg adjacent to Mg/Zn 3 MgY interfaces triggered atomic rearrangement in Mg to form icosahedra coupled epitaxially with surface distorted icosahedra of Zn 3 MgY, which plays a critical role in the nucleation of icosahedral clusters. A local Zn:Mg:Y ratio close to 6:3:1, corresponding to a valence electron concentration of about 2.15, should have been reached to trigger the formation of quasicrystals at Mg/Zn 3 MgY interfaces. The solid-state icosahedral ordering in crystals opens a new window for growing quasicrystals and understanding their atomic origin mechanisms. Epitaxial growth of quasicrystals onto crystals can modify the surface/interface structures and properties of crystalline materials. PMID:26066096

  2. High-Performance Soft-Tissue Imaging in Extremity Cone-Beam CT

    PubMed Central

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Muhit, A.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2014-01-01

    Purpose Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. Methods The accelerated MC scatter correction involved fast MC simulation with low number of photons implemented on a GPU (107 photons/sec), followed by Gaussian kernel smoothing in the detector plane and across projection angles. PL reconstructions were investigated for reduction of imaging dose for projections acquired at ~2 mGy. Results The rapid scatter estimation yielded root-mean-squared-errors of scatter projections of ~15% of peak scatter intensity for 5·106 photons/projection (runtime ~0.5 sec/projection) and 25% improvement in fat-muscle contrast in reconstructions of a cadaveric knee. PL reconstruction largely restored soft-tissue visualization at 2 mGy dose to that of 10 mGy FBP image. Conclusion The combination of rapid (5–10 minutes/scan) MC-based, patient-specific scatter correction and PL reconstruction offers an important means to overcome the current limitations of extremity CBCT in soft-tissue imaging. PMID:25076825

  3. Exploiting the IR: Solar and stellar spectroscopy in the IR

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    1987-01-01

    Recent instrumental advances have provided the capability to perform high resolution spectroscopy, in the thermal infrared region of the solar spectrum, with high sensitivity. The 8 to 12 micron region was extensively observed using Fourier transform (FTS) and laser heterodyne techniques. The continuous opacity of the solar atmosphere, due to H(-), increases with wavelength in the infrared region longward of 1.6 microns. Consequently thermal infrared observations probe the upper photosphere, and give an insight into the dynamics and structure of this region. The most notable spectral features in the 10 micron window include pure rotation lines of OH, and emission lines due to high-n states in MgI and AlI. The high-n lines due to MgI and AlI are important to solar and stellar physics because of their very large Zeeman sensitivity. The recent development of a cryogenic grating postdispenser for the FTS has allowed low-noise solar observations of these lines in 90 seconds. Limited mapping of the lines in a sunspot penumbra was performed, and gives information of the structure of the penumbral magnetic field. Although the MgI lines were detected in red giant spectra, instrumental sensitivity is not yet sufficient to see them in stars where significant magnetic fields are expected.

  4. Comparison of full field digital (FFD) and computed radiography (CR) mammography systems in Greece.

    PubMed

    Kalathaki, M; Hourdakis, C J; Economides, S; Tritakis, P; Kalyvas, N; Simantirakis, G; Manousaridis, G; Kaisas, I; Kamenopoulou, V

    2011-09-01

    The purpose of this study is to evaluate and compare the performance of 52 full field digital (FFD) and computed radiography (CR) mammography systems checked by the Greek Atomic Energy Commission with respect to dose and image quality. Entrance surface air kerma (ESAK) was measured and average glandular dose (AGD) was calculated according to the European protocol on dosimetry in mammography. The exposures were performed using the clinical protocol of each laboratory. The image quality was assessed by the total score of resolved phantom structures incorporated in an American College of Radiology accreditation phantom. The mean ESAK values for FFD and CR systems were 4.59 ± 1.93 and 5.0 ± 1.78 mGy, respectively, whereas the AGD yielded a mean value of 1.06 ± 0.36 mGy for the FFD and 1.04 ± 0.35 mGy for the CR systems. Considering image quality, FFD systems indicated a mean total score of 13.04 ± 0.89, whereas CR systems a mean total score of 11.54 ± 1.06. PMID:21821614

  5. The phylogeny of endolithic microbes associated with marine basalts.

    PubMed

    Mason, Olivia U; Stingl, Ulrich; Wilhelm, Larry J; Moeseneder, Markus M; Di Meo-Savoie, Carol A; Fisk, Martin R; Giovannoni, Stephen J

    2007-10-01

    We examined the phylogenetic diversity of microbial communities associated with marine basalts, using over 300 publicly available 16S rDNA sequences and new sequence data from basalt enrichment cultures. Phylogenetic analysis provided support for 11 monophyletic clades originating from ocean crust (sediment, basalt and gabbro). Seven of the ocean crust clades (OCC) are bacterial, while the remaining four OCC are in the Marine Group I (MGI) Crenarchaeota. Most of the OCC were found at diverse geographic sites, suggesting that these microorganisms have cosmopolitan distributions. One OCC in the Crenarchaeota consisted of sequences derived entirely from basalts. The remaining OCC were found in both basalts and sediments. The MGI Crenarchaeota were observed in all studies where archaeal diversity was evaluated. These results demonstrate that basalts are occupied by cosmopolitan clades of microorganisms that are also found in marine sediments but are distinct from microorganisms found in other marine habitats, and that one OCC in the ubiquitous MGI Crenarchaeota clade may be an ecotype specifically adapted to basalt. PMID:17803778

  6. X-ray dose response of calcite-A comprehensive analysis for optimal application in TL dosimetry

    NASA Astrophysics Data System (ADS)

    Kalita, J. M.; Wary, G.

    2016-09-01

    The effect of various annealing treatments on dosimetric characteristics of orange calcite (CaCO3) mineral has been studied in detail. Quantitative analysis on the dose response shows that the 573 K annealed sample showed sublinear dose response from 10 mGy to 1 Gy. The fading and reproducibility of this sample are also good enough for dosimetric application. However, a specific annealing treatment after irradiation shows some significant improvements in the dosimetric characteristics of the sample. The 773 K pre-annealed sample, after X-ray irradiation post-annealing at 340 K for 6 min provides linear dose response from 10 mGy to 3.60 Gy, very less fading and good reproducibility. Moreover, this sample after post-annealing at 380 K for 6 min shows linear dose response from 10 mGy to 5.40 Gy when analyzed from the ∼408 K thermoluminescence (TL) glow peak. Analysis of TL glow curves confirmed that the 1.30 eV trap center in calcite crystal is the most effective trapping site for dosimetric application.

  7. Direct observation of solid-state reversed transformation from crystals to quasicrystals in a Mg alloy

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Fang; Yang, Zhi-Qing; Ye, Heng-Qiang

    2015-06-01

    Phase transformation of quasicrystals is of interest in various fields of science and technology. Interestingly, we directly observed unexpected solid-state epitaxial nucleation and growth of Zn6Mg3Y icosahedral quasicrystals in a Mg alloy at about 573 K which is about 300 K below the melting point of Zn6Mg3Y, in contrast to formation of quasicrystals through solidification that was usually found in many alloys. Maximizing local packing density of atoms associated with segregation of Y and Zn in Mg adjacent to Mg/Zn3MgY interfaces triggered atomic rearrangement in Mg to form icosahedra coupled epitaxially with surface distorted icosahedra of Zn3MgY, which plays a critical role in the nucleation of icosahedral clusters. A local Zn:Mg:Y ratio close to 6:3:1, corresponding to a valence electron concentration of about 2.15, should have been reached to trigger the formation of quasicrystals at Mg/Zn3MgY interfaces. The solid-state icosahedral ordering in crystals opens a new window for growing quasicrystals and understanding their atomic origin mechanisms. Epitaxial growth of quasicrystals onto crystals can modify the surface/interface structures and properties of crystalline materials.

  8. Crystal growth and thermoluminescence response of NaZr2(PO4)3 at high gamma radiation doses

    NASA Astrophysics Data System (ADS)

    Ordóñez-Regil, E.; Contreras-Ramírez, A.; Fernández-Valverde, S. M.; González-Martínez, P. R.; Carrasco-Ábrego, H.

    2013-11-01

    This work describes the synthesis and characterization of NaZr2(PO4)3. The stability of this material under high doses of gamma radiation was investigated in the range of 10-50 MGy. Samples of unaltered and gamma irradiated NaZr2(PO4)3 were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermoluminescence. The results showed that while functional groups were not affected by the gamma irradiation, morphology changes were observed with increasing doses of gamma irradiation. The morphology of the non-irradiated compound is agglomerated flakes; however, irradiation at 10 MGy splits the flakes inducing the formation of well-defined cubes. Gamma irradiation induced the crystal size of the NaZr2(PO4)3 to grow. The heat treatment (973 K) of samples irradiated at 50 MGy resulted in the recovery of the original morphology. Furthermore, the thermoluminescence analysis of the irradiated compound is reported.

  9. Fetal radiation dose in computed tomography.

    PubMed

    Kelaranta, Anna; Kaasalainen, Touko; Seuri, Raija; Toroi, Paula; Kortesniemi, Mika

    2015-07-01

    The connection between recorded volumetric CT dose index (CTDI vol) and determined mean fetal dose (Df) was examined from metal-oxide-semiconductor field-effect transistor dose measurements on an anthropomorphic female phantom in four stages of pregnancy in a 64-slice CT scanner. Automated tube current modulation kept the mean Df fairly constant through all pregnancy stages in trauma (4.4-4.9 mGy) and abdomino-pelvic (2.1-2.4 mGy) protocols. In pulmonary angiography protocol, the mean Df increased exponentially as the distance from the end of the scan range decreased (0.01-0.09 mGy). For trauma protocol, the relative mean Df as a function of gestational age were in the range 0.80-0.97 compared with the mean CTDI vol. For abdomino-pelvic protocol, the relative mean Df was 0.57-0.79 and for pulmonary angiography protocol, 0.01-0.05 compared with the mean CTDI vol, respectively. In conclusion, if the fetus is in the primary beam, the CTDI vol can be used as an upper estimate of the fetal dose. If the fetus is not in the primary beam, the fetal dose can be estimated by considering also the distance of the fetus from the scan range. PMID:25836690

  10. Evaluation of radiation dose to pediatric patients during certain special procedures

    NASA Astrophysics Data System (ADS)

    Sulieman, A.; Alzimami, K.; Elhag, B.; Babikir, E.; Alsafi, K.

    2014-11-01

    This study was intended to measure pediatric entrance surface air kerma (ESAK) and effective dose during micturating cystourethrography (MCU), intravenous urography (IVU) and barium studies (barium meal, enema, and swallow) and to propose a local diagnostic reference level (DRL). ESAK was measured for patients using calibrated thermoluminescent dosimeters (TLDs, GR200A). Effective doses (E) were calculated using the National Radiological Protection Board (NRPB) software. A total of 236 special pediatric procedures were investigated. 21.7% of the sample comprised barium procedures, 18.6% were MCU procedures while 59.5% of the sample were IVU procedures. The mean ESAK measurements (mGy) were 2.1±0.8, 3.0±23 and 1.2±0.2 for barium meal, enema and swallow in the same order. The mean patient dose for IVU procedures was 12.4±8.7 mGy per procedure and the mean patient dose per MCU procedure was 5.8±7 mGy. Local DRLs were proposed for all procedures. The patient doses in this study are within the reported values, suggesting that pediatric patients are adequately protected.

  11. Neonatal exposure to whole body ionizing radiation induces adult neurobehavioural defects: Critical period, dose--response effects and strain and sex comparison.

    PubMed

    Eriksson, Per; Buratovic, Sonja; Fredriksson, Anders; Stenerlöw, Bo; Sundell-Bergman, Synnöve

    2016-05-01

    Development of the brain includes periods which can be critical for its normal maturation. The present study investigates specifically vulnerable peri-/postnatal periods in mice which are essential for understanding the etiology behind radiation induced neurotoxicity and functional defects, including evaluation of neurotoxicity between sexes or commonly used laboratory mouse strains following low/moderate doses of ionizing radiation (IR). Male Naval Medical Research Institute (NMRI) mice, whole body irradiated to a single 500 mGy IR dose, on postnatal day (PND) 3 or PND 10 showed an altered adult spontaneous behaviour and impaired habituation capacity, whereas irradiation on PND 19 did not have any impact on the studied variables. Both NMRI and C57bl/6 male and female mice showed an altered adult spontaneous behaviour and impaired habituation following a single whole body irradiation of 500 or 1000 mGy, but not after 20 or 100 mGy, on PND 10. The present study shows that exposure to low/moderate doses of IR during critical life stages might be involved in the induction of neurological/neurodegenerative disorder/disease. A specifically vulnerable period for radiation induced neurotoxicity seems to be around PND 3-10 in mice. Further studies are needed to investigate mechanisms involved in induction of developmental neurotoxicity following low-dose irradiation. PMID:26876140

  12. Bone marrow dose estimates from work-related medical x-ray examinations given between 1943 and 1966 for personnel from five U.S. nuclear facilities.

    PubMed

    Anderson, Jeri L; Daniels, Robert D

    2006-06-01

    Inclusion of dose from work-related medical x-ray examinations with occupational external dose in an epidemiological study may reduce misclassification of exposures and provide more accurate assessment of leukemia risk from occupational exposure to ionizing radiation. In a multi-site leukemia case-control study, annual bone marrow doses due to work-related x-ray examinations given between 1943 and 1966 were estimated for cases and controls employed at five nuclear facilities. Only active bone marrow dose from photofluorographic chest and routine lumbar spine x rays were included. Bone marrow dose assigned for a single exposure ranged from 1.0 to 1.4 mGy. Mean and median cumulative bone marrow doses for each of the five sites from work-related x-ray examinations ranged from 2.0 to 14 mGy and 2.1 to 8.8 mGy, respectively. Results suggest that bone marrow dose from work-related photofluorographic and lumbar spine x-ray examinations given during the time period of this study may be significant compared to occupational bone marrow dose. PMID:16691102

  13. Effective dose estimation during conventional and CT urography

    NASA Astrophysics Data System (ADS)

    Alzimami, K.; Sulieman, A.; Omer, E.; Suliman, I. I.; Alsafi, K.

    2014-11-01

    Intravenous urography (IVU) and CT urography (CTU) are efficient radiological examinations for the evaluation of the urinary system disorders. However patients are exposed to a significant radiation dose. The objectives of this study are to: (i) measure and compare patient radiation dose by computed tomography urography (CTU) and conventional intravenous urography (IVU) and (ii) evaluate organ equivalent dose and cancer risks from CTU and IVU imaging procedures. A total of 141 patients were investigated. A calibrated CT machine (Siemens-Somatom Emotion duo) was used for CTU, while a Shimadzu X ray machine was used for IVU. Thermoluminescence dosimeters (TLD-GR200A) were used to measure patients' entrance surface doses (ESD). TLDs were calibrated under reproducible reference conditions. Patients radiation dose values (DLP) for CTU were 172±61 mGy cm, CTDIvol 4.75±2 mGy and effective dose 2.58±1 mSv. Patient cancer probabilities were estimated to be 1.4 per million per CTU examination. Patients ESDs values for IVU were 21.62±5 mGy, effective dose 1.79±1 mSv. CT involves a higher effective dose than IVU. In this study the radiation dose is considered low compared to previous studies. The effective dose from CTU procedures was 30% higher compared to IVU procedures. Wide dose variation between patient doses suggests that optimization is not fulfilled yet.

  14. Evaluation of staff, patient and foetal radiation doses due to endoscopic retrograde cholangiopancreatography (ERCP) procedures in a pregnant patient.

    PubMed

    Huda, A; Garzón, W J; Filho, G C L; Vieira, B; Kramer, R; Xu, X G; Gao, Y; Khoury, H J

    2016-03-01

    The use of endoscopic retrograde cholangiopancreatography (ERCP) in pregnant patients is not rare. Most studies on the safety and efficacy of these procedures report short- and long-term pregnancy outcomes and but not foetal absorbed doses. This investigation reports on an ERCP procedure for a 40-y-old woman who was 32-34 weeks pregnant. Thermoluminescent dosemeters (TLD 100) were used to measure doses received by the patient and the staff. Additionally, Monte Carlo calculations were performed using a 3D computational phantom representing a 9-month pregnant patient to estimate the foetal absorbed dose. The results show that the spleen of the mother received the largest absorbed dose of 12.18 mGy since it was closer to the source than other internal organs. For the foetus and uterus, the lowest absorbed dose was found to be 0.01 mGy to the foetal brain, while the largest absorbed dose was estimated to be 0.13 mGy to the placenta. PMID:26084305

  15. Reduction of Radiation Doses to Patients and Staff During Endoscopic Retrograde Cholangiopancreatography

    PubMed Central

    Sulieman, Abdelmoneim; Paroutoglou, Georgios; Kapsoritakis, Andreas; Kapatenakis, Anargeyros; Potamianos, Spiros; Vlychou, Marianna; Theodorou, Kiki

    2011-01-01

    Background/Aim: Endoscopic retrograde cholangiopancreatography (ERCP) is associated with a considerable radiation exposure for patients and staff. While optimization of the radiation dose is recommended, few studies have been published. The purpose of this study has been to measure patient and staff radiation dose, to estimate the effective dose and radiation risk using digital fluoroscopic images. Entrance skin dose (ESD), organ and effective doses were estimated for patients and staff. Materials and Methods: Fifty-seven patients were studied using digital X-ray machine and thermoluminescent dosimeters (TLD) to measure ESD at different body sites. Organ and surface dose to specific radiosensitive organs was carried out. The mean, median, minimum, third quartile and the maximum values are presented due to the asymmetry in data distribution. Results: The mean ESD, exit and thyroid surface dose were estimated to be 75.6 mGy, 3.22 mGy and 0.80 mGy, respectively. The mean effective dose for both gastroenterologist and assistant is 0.01 mSv. The mean patient effective dose was 4.16 mSv, and the cancer risk per procedure was estimated to be 2 × 10-5 Conclusion: ERCP with fluoroscopic technique demonstrate improved dose reduction, compared to the conventional radiographic based technique, reducing the surface dose by a factor of 2, without compromising the diagnostic findings. The radiation absorbed doses to the different organs and effective doses are relatively low. PMID:21196649

  16. [Long-term follow-up cytogenetic survey and biological dosimetry in persons evacuated from 30-km Chernobyl NPP zone].

    PubMed

    Maznik, N A

    2004-01-01

    The paper presents the results of the follow-up cytogenetic survey and biological dosimetry carried out in inhabitants of Pripiat' town and nearby villages, who were departured from the Chernobyl NPP 30-km exclusive zone during first days after the Chernobyl catastrophe. The unstable chromosome aberration level in inhabitants were significantly increased above control in terms up to 1 year after evacuation and declined gardually during next 14 years. In early period the cytogenetic damage frequency in evacuees showed no dependence on gender. The chromosome type aberration level appeared to be lower in young persons comparing with adults. The dicentrics plus centric rings yield had a positive correlation with duration of staying at Chernobyl zone. The average doses of protracted exposure were calculated from the dicentrics and centric rings yields; the dose estimations appeared to be 1.4 times higher in persons evacuated 3-11 days after the accident than that of in persons with shorter departure time. Uing the Bayesian analysis the probabilistic distribution of biological doses was constructed for the studied evacuees group. This distribution was characterized by a mean dose of 360 mGy, the modal doses of 200-450 mGy and 80% of probability density within the dose range 0-1000 mGy, that seems to be sufficient for considering the increased risk of late somatic radiation effects for this cohort. PMID:15571047

  17. Postnatal quality of life, depressive symptoms, and social support among women in southern India.

    PubMed

    Bodhare, Trupti N; Sethi, Pruthwiraj; Bele, Samir D; Gayatri, Dasari; Vivekanand, Achanta

    2015-01-01

    Evaluation of postnatal quality of life (QOL) has remained a poorly researched area in India. The present cross-sectional study assessed postnatal QOL, using the Mother Generated Index (MGI) and its associated risk factors, and was conducted during January-March 2013 among 274 mothers, 6-8 weeks postnatally. A semi-structured questionnaire was used to evaluate sociodemographic and obstetric characteristics and social support. Depressive symptoms were assessed by the Patient Health Questionnaire (PHQ-9) and QOL using the MGI. The vast majority (90.1 percent) of respondents in our study had a primary MGI score <5, those with significantly higher prevalence of physical problems and psychological distress. A total of 39.8 percent of respondents were screened as having other (not major) depressive symptoms and 4.7 percent as having major depressive symptoms. Multiple regression analysis revealed that age (β = 0.033, p = .018) and socioeconomic status (β = 0.156, p < .001) were significantly positively associated with QOL, while increased depressive symptom scores (β = -0.075, p < .001) were significantly negatively associated with QOL. A wide spectrum of QOL aspects were reported, including physical, emotional, social, and economic concerns by the mothers. Prevention, evaluation, and treatment of postnatal depressive symptoms and impaired QOL are warranted, taking into account the role of various biopsychosocial risk factors and specific concerns raised by the mothers. PMID:25719436

  18. Radiation dose levels for conventional chest and abdominal X-ray procedures in elected hospitals in Sudan.

    PubMed

    Babikir, E; Hasan, Hussein A; Abdelrazig, A; Alkhorayef, M A; Manssor, E; Sulieman, A

    2015-07-01

    This study aimed to assess patient entrance surface air kerma (ESAK) during chest and abdominal X-ray procedures in screen film radiography (SFR) and computed radiography (CR) to establish dose reference levels. Patients' doses were measured in five hospitals for a total of 196 patients. ESAK was calculated from exposure parameters using DosCal software. The X-ray tube output (mGy mAs(-1)), accuracy of exposure factors, linearity and reproducibility were measured using an Unfors Xi dosimeter. The overall mean and range of ESAK during chest X-ray were 0.6 ± 0.3 (0.1-1.3) mGy, while for abdominal X-rays they were 4.0 ± 3.2 (1.3-9.2) mGy. Hospital with a CR system was found to use relatively higher doses. Dose values for abdominal X-ray procedures were comparable with previous studies. The dose for chest X-ray procedure was higher by a factor of 2-3 compared with the current international reference levels. PMID:25852182

  19. Do we need keratinized mucosa for a healthy peri-implant soft tissue?

    PubMed

    Esfahanizadeh, Nasrin; Daneshparvar, Niloufar; Motallebi, Sara; Akhondi, Nasrin; Askarpour, Farinaz; Davaie, Sotudeh

    2016-01-01

    The presence of keratinized mucosa plays a fundamental role in peri-implant soft tissue health. This study assessed the impact of the width of keratinized mucosa (WKM) on peri-implant soft tissue parameters. A cross-sectional study was conducted on 110 bone-level implants in 36 patients. A minimum of 6 months had passed since the loading of implants, and the patients had at least 1 implant in 1 quadrant at the molar or premolar site restored with a single crown or fixed partial denture. The health of peri-implant soft tissue was assessed with a modified bleeding index (MBI), modified plaque index (MPI), and modified gingival index (MGI). Probing depth (PD), gingival recession (GR), and WKM were also measured. History of smoking and oral hygiene methods were recorded. A significant inverse correlation existed between WKM and the parameters MBI, MPI, MGI, and GR (P < 0.05). Values of MBI, MPI, MGI, and GR were significantly lower in areas with WKM ≥ 2 mm and higher in areas with WKM < 2 mm (P < 0.05). The WKM was greatest in subjects using the vibratory toothbrushing technique and narrowest in those using the horizontal toothbrushing technique (P < 0.05). The mean WKM was significantly greater in smokers than in nonsmokers (P < 0.05). Results of this study indicate that an association exists between WKM and peri-implant soft tissue health. A minimum of 2 mm of keratinized mucosa around implants is recommended. PMID:27367634

  20. Results of EPR dosimetry for population in the vicinity of the most contaminating radioactive fallout trace after the first nuclear test in the Semipalatinsk test site.

    PubMed

    Ivannikov, Alexander; Zhumadilov, Kassym; Tieliewuhan, Eldana; Jiao, Ling; Zharlyganova, Dinara; Apsalikov, Kazbek N; Berekenova, Gulnara; Zhumadilov, Zhaxybay; Toyoda, Shin; Miyazawa, Chuzou; Skvortsov, Valeriy; Stepanenko, Valeriy; Endo, Satoru; Tanaka, Kenichi; Hoshi, Masaharu

    2006-02-01

    The method of electron paramagnetic resonance (EPR) spectroscopy for tooth enamel is applied to individual radiation dose determination to residents of two villages (Dolon and Mostik) in the vicinity of the Semipalatinsk nuclear test site in Kazakhstan. These villages are located near the central axis of the radioactive fallout trace of the most contaminating surface nuclear test conducted in 1949. It is found that excess doses obtained by subtraction of natural background dose from dose absorbed in enamel range up to 440 mGy to residents of Dolon, whose enamel was formed before 1949, and do not exceed 120 mGy to younger residents. To residents of Mostik, excess doses do not exceed 100 mGy regardless of age except for one resident with an extremely high dose of 1.25 Gy. These results are in agreement with the pattern of radioactive contamination of the territory after the nuclear test of 1949 except one case of extremely high dose, which should be additionally investigated. PMID:16571943

  1. Improved Liver Lesion Conspicuity With Iterative Reconstruction in Computed Tomography Imaging.

    PubMed

    Jensen, Kristin; Andersen, Hilde Kjernlie; Tingberg, Anders; Reisse, Claudius; Fosse, Erik; Martinsen, Anne Catrine T

    2016-01-01

    Studies on iterative reconstruction techniques on computed tomographic (CT) scanners show reduced noise and changed image texture. The purpose of this study was to address the possibility of dose reduction and improved conspicuity of lesions in a liver phantom for different iterative reconstruction algorithms. An anthropomorphic upper abdomen phantom, specially designed for receiver operating characteristic analysis was scanned with 2 different CT models from the same vendor, GE CT750 HD and GE Lightspeed VCT. Images were obtained at 3 dose levels, 5, 10, and 15mGy, and reconstructed with filtered back projection (FBP), and 2 different iterative reconstruction algorithms; adaptive statistical iterative reconstruction and Veo. Overall, 5 interpreters evaluated the images and receiver operating characteristic analysis was performed. Standard deviation and the contrast to noise ratio were measured. Veo image reconstruction resulted in larger area under curves compared with those adaptive statistical iterative reconstruction and FBP image reconstruction for given dose levels. For the CT750 HD, iterative reconstruction at the 10mGy dose level resulted in larger or similar area under curves compared with FBP at the 15mGy dose level (0.88-0.95 vs 0.90). This was not shown for the Lightspeed VCT (0.83-0.85 vs 0.92). The results in this study indicate that the possibility for radiation dose reduction using iterative reconstruction techniques depends on both reconstruction technique and the CT scanner model used. PMID:26790606

  2. Dosimetry of an In-Line Kilovoltage Imaging System and Implementation in Treatment Planning

    SciTech Connect

    Dzierma, Yvonne; Alaei, Parham; Licht, Norbert; Rübe, Christian

    2014-03-15

    Purpose: To present the beam properties of the Siemens 70-kV and 121-kV linear accelerator-mounted imaging modalities and commissioning of the 121-kV beam in the Philips Pinnacle treatment planning system (TPS); measurements in an Alderson phantom were performed for verification of the model and to estimate the cone-beam CT (CBCT) imaging dose in the head and neck, thorax, and pelvis. Methods and Materials: The beam profiles and depth–dose curve were measured in an acrylic phantom using thermoluminescent dosimeters and a soft x-ray ionization chamber. Measurements were imported into the TPS, modeled, and verified by phantom measurements. Results: Modeling of the profiles and the depth–dose curve can be achieved with good quality. Comparison with the measurements in the Alderson phantom is generally good; only very close to bony structures is the dose underestimated by the TPS. For a 200° arc CBCT of the head and neck, a maximum dose of 7 mGy is measured; the thorax and pelvis 360° CBCTs give doses of 4-10 mGy and 7-15 mGy, respectively. Conclusions: Dosimetric characteristics of the Siemens kVision imaging modalities are presented and modeled in the Pinnacle TPS. Thermoluminescent dosimeter measurements in the Alderson phantom agree well with the calculated TPS dose, validating the model and providing an estimate of the imaging dose for different protocols.

  3. Direct observation of solid-state reversed transformation from crystals to quasicrystals in a Mg alloy.

    PubMed

    Liu, Jian-Fang; Yang, Zhi-Qing; Ye, Heng-Qiang

    2015-01-01

    Phase transformation of quasicrystals is of interest in various fields of science and technology. Interestingly, we directly observed unexpected solid-state epitaxial nucleation and growth of Zn6Mg3Y icosahedral quasicrystals in a Mg alloy at about 573 K which is about 300 K below the melting point of Zn6Mg3Y, in contrast to formation of quasicrystals through solidification that was usually found in many alloys. Maximizing local packing density of atoms associated with segregation of Y and Zn in Mg adjacent to Mg/Zn3MgY interfaces triggered atomic rearrangement in Mg to form icosahedra coupled epitaxially with surface distorted icosahedra of Zn3MgY, which plays a critical role in the nucleation of icosahedral clusters. A local Zn:Mg:Y ratio close to 6:3:1, corresponding to a valence electron concentration of about 2.15, should have been reached to trigger the formation of quasicrystals at Mg/Zn3MgY interfaces. The solid-state icosahedral ordering in crystals opens a new window for growing quasicrystals and understanding their atomic origin mechanisms. Epitaxial growth of quasicrystals onto crystals can modify the surface/interface structures and properties of crystalline materials. PMID:26066096

  4. Allele, phenotype and disease data at Mouse Genome Informatics: improving access and analysis.

    PubMed

    Bello, Susan M; Smith, Cynthia L; Eppig, Janan T

    2015-08-01

    A core part of the Mouse Genome Informatics (MGI) resource is the collection of mouse mutations and the annotation phenotypes and diseases displayed by mice carrying these mutations. These data are integrated with the rest of data in MGI and exported to numerous other resources. The use of mouse phenotype data to drive translational research into human disease has expanded rapidly with the improvements in sequencing technology. MGI has implemented many improvements in allele and phenotype data annotation, search, and display to facilitate access to these data through multiple avenues. For example, the description of alleles has been modified to include more detailed categories of allele attributes. This allows improved discrimination between mutation types. Further, connections have been created between mutations involving multiple genes and each of the genes overlapping the mutation. This allows users to readily find all mutations affecting a gene and see all genes affected by a mutation. In a similar manner, the genes expressed by transgenic or knock-in alleles are now connected to these alleles. The advanced search forms and public reports have been updated to take advantage of these improvements. These search forms and reports are used by an expanding number of researchers to identify novel human disease genes and mouse models of human disease. PMID:26162703

  5. Evidence for Radiation Hormesis After In Vitro Exposure of Human Lymphocytes to Low Doses of Ionizing Radiation§

    PubMed Central

    Rithidech, Kanokporn Noy; Scott, Bobby R.

    2008-01-01

    Previous research has demonstrated that adding a very small gamma-ray dose to a small alpha radiation dose can completely suppress lung cancer induction by alpha radiation (a gamma-ray hormetic effect). Here we investigated the possibility of gamma-ray hormesis during low-dose neutron irradiation, since a small contribution to the total radiation dose from neutrons involves gamma rays. Using binucleated cells with micronuclei (micronucleated cells) among in vitro monoenergetic-neutron-irradiated human lymphocytes as a measure of residual damage, we investigated the influence of the small gamma-ray contribution to the dose on suppressing residual damage. We used residual damage data from previous experiments that involved neutrons with five different energies (0.22-, 0.44-, 1.5-, 5.9-, and 13.7-million electron volts [MeV]). Corresponding gamma-ray contributions to the dose were approximately 1%, 1%, 2%, 6%, and 6%, respectively. Total absorbed radiation doses were 0, 10, 50, and 100 mGy for each neutron source. We demonstrate for the first time a protective effect (reduced residual damage) of the small gamma-ray contribution to the neutron dose. Using similar data for exposure to gamma rays only, we also demonstrate a protective effect of 10 mGy (but not 50 or 100 mGy) related to reducing the frequency of micronucleated cells to below the spontaneous level. PMID:18846261

  6. Linear Models Based on Noisy Data and the Frisch Scheme*

    PubMed Central

    Ning, Lipeng; Georgiou, Tryphon T.; Tannenbaum, Allen; Boyd, Stephen P.

    2016-01-01

    We address the problem of identifying linear relations among variables based on noisy measurements. This is a central question in the search for structure in large data sets. Often a key assumption is that measurement errors in each variable are independent. This basic formulation has its roots in the work of Charles Spearman in 1904 and of Ragnar Frisch in the 1930s. Various topics such as errors-in-variables, factor analysis, and instrumental variables all refer to alternative viewpoints on this problem and on ways to account for the anticipated way that noise enters the data. In the present paper we begin by describing certain fundamental contributions by the founders of the field and provide alternative modern proofs to certain key results. We then go on to consider a modern viewpoint and novel numerical techniques to the problem. The central theme is expressed by the Frisch–Kalman dictum, which calls for identifying a noise contribution that allows a maximal number of simultaneous linear relations among the noise-free variables—a rank minimization problem. In the years since Frisch’s original formulation, there have been several insights, including trace minimization as a convenient heuristic to replace rank minimization. We discuss convex relaxations and theoretical bounds on the rank that, when met, provide guarantees for global optimality. A complementary point of view to this minimum-rank dictum is presented in which models are sought leading to a uniformly optimal quadratic estimation error for the error-free variables. Points of contact between these formalisms are discussed, and alternative regularization schemes are presented. PMID:27168672

  7. Low-Dose Gamma Radiation Does Not Induce an Adaptive Response for Micronucleus Induction in Mouse Splenocytes.

    PubMed

    Bannister, L A; Serran, M L; Mantha, R R

    2015-11-01

    Low-dose ionizing radiation is known to induce radioadaptive responses in cells in vitro as well as in mice in vivo. Low-dose radiation decreases the incidence and increases latency for spontaneous and radiation-induced tumors in mice, potentially as a result of enhanced cellular DNA repair efficiency or a reduction in genomic instability. In this study, the cytokinesis-block micronucleus (CBMN) assay was used to examine dose response and potential radioadaptive response for cytogenetic damage and cell survival in C57BL/6 and BALB/c spleen cells exposed in vitro or in vivo to low-dose 60Co gamma radiation. The effects of genetic background, radiation dose and dose rate, sampling time and cell cycle were investigated with respect to dose response and radioadaptive response. In C57BL/6 mice, a linear-quadratic dose-response relationship for the induction of micronuclei (MN) was observed for doses between 100 mGy and 2 Gy. BALB/c mice exhibited increased radiosensitivity for MN induction compared to C57BL/6 mice. A 20 mGy dose had no effect on MN frequencies in splenocytes of either mouse strain, however, increased spleen weight and a reduced number of dead cells were noted in the C57BL/6 strain only. Multiple experimental parameters were investigated in radioadaptive response studies, including dose and dose rate of the priming dose (20 mGy at 0.5 mGy/min and 100 mGy at 10 mGy/min), time interval (4 and 24 h) between priming and challenge doses, cell cycle stage (resting or proliferating) at exposure and kinetics after the challenge dose. Radioadaptive responses were not observed for MN induction for either mouse strain under any of the experimental conditions investigated. In contrast, a synergistic response for radiation-induced micronuclei in C57BL/6 spleen was detected after in vivo 20 mGy irradiation. This increase in the percentage of cells with cytogenetic damage was associated with a reduction in the number of nonviable spleen cells, suggesting that low

  8. Estimating pediatric entrance skin dose from digital radiography examination using DICOM metadata: A quality assurance tool

    SciTech Connect

    Brady, S. L. Kaufman, R. A.

    2015-05-15

    Purpose: To develop an automated methodology to estimate patient examination dose in digital radiography (DR) imaging using DICOM metadata as a quality assurance (QA) tool. Methods: Patient examination and demographical information were gathered from metadata analysis of DICOM header data. The x-ray system radiation output (i.e., air KERMA) was characterized for all filter combinations used for patient examinations. Average patient thicknesses were measured for head, chest, abdomen, knees, and hands using volumetric images from CT. Backscatter factors (BSFs) were calculated from examination kVp. Patient entrance skin air KERMA (ESAK) was calculated by (1) looking up examination technique factors taken from DICOM header metadata (i.e., kVp and mA s) to derive an air KERMA (k{sub air}) value based on an x-ray characteristic radiation output curve; (2) scaling k{sub air} with a BSF value; and (3) correcting k{sub air} for patient thickness. Finally, patient entrance skin dose (ESD) was calculated by multiplying a mass–energy attenuation coefficient ratio by ESAK. Patient ESD calculations were computed for common DR examinations at our institution: dual view chest, anteroposterior (AP) abdomen, lateral (LAT) skull, dual view knee, and bone age (left hand only) examinations. Results: ESD was calculated for a total of 3794 patients; mean age was 11 ± 8 yr (range: 2 months to 55 yr). The mean ESD range was 0.19–0.42 mGy for dual view chest, 0.28–1.2 mGy for AP abdomen, 0.18–0.65 mGy for LAT view skull, 0.15–0.63 mGy for dual view knee, and 0.10–0.12 mGy for bone age (left hand) examinations. Conclusions: A methodology combining DICOM header metadata and basic x-ray tube characterization curves was demonstrated. In a regulatory era where patient dose reporting has become increasingly in demand, this methodology will allow a knowledgeable user the means to establish an automatable dose reporting program for DR and perform patient dose related QA testing for

  9. Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model

    SciTech Connect

    Boivin, Jonathan; Tomic, Nada; Fadlallah, Bassam; DeBlois, Francois; Devic, Slobodan

    2011-09-15

    Purpose: The authors applied 2D reference dosimetry protocol for dose measurements using XR-QA radiochromic film model during diagnostic computed tomography (CT) examinations carried out on patients and humanoid Rando phantom. Methods: Response of XR-QA model GAFCHROMIC film reference dosimetry system was calibrated in terms of Air-Kerma in air. Four most commonly used CT protocols were selected on their CT scanner (GE Lightspeed VCT 64), covering three anatomical sites (head, chest, and abdomen). For each protocol, 25 patients ongoing planned diagnostic CT examination were recruited. Surface dose was measured using four or eight film strips taped on patients' skin and on Rando phantom. Film pieces were scanned prior to and after irradiation using Epson Expression 10000XL document scanner. Optical reflectance of the unexposed film piece was subtracted from exposed one to obtain final net reflectance change, which is subsequently converted to dose using previously established calibration curves. Results: The authors' measurements show that body skin dose variation has a sinusoidal pattern along the scanning axis due to the helical movement of the x-ray tube, and a comb pattern for head dose measurements due to its axial movement. Results show that the mean skin dose at anterior position for patients is (51 {+-} 6) mGy, (29 {+-} 11) mGy, (45 {+-} 13) mGy and (38 {+-} 20) mGy for head, abdomen, angio Abdomen, and chest and abdomen protocol (UP position), respectively. The obtained experimental dose length products (DLP) show higher values than CT based DLP taken from the scanner console for body protocols, but lower values for the head protocol. Internal dose measurements inside the phantom's head indicate nonuniformity of dose distribution within scanned volume. Conclusions: In this work, the authors applied an Air-Kerma in air based radiochromic film reference dosimetry protocol for in vivo skin dose measurements. In this work, they employed green channel extracted

  10. Prospective Evaluation of Prior Image Constrained Compressed Sensing (PICCS) Algorithm in Abdominal CT: A comparison of reduced dose with standard dose imaging

    PubMed Central

    Lubner, Meghan G.; Pickhardt, Perry J.; Kim, David H.; Tang, Jie; Munoz del Rio, Alejandro; Chen, Guang-Hong

    2014-01-01

    Purpose To prospectively study CT dose reduction using the “prior image constrained compressed sensing” (PICCS) reconstruction technique. Methods Immediately following routine standard dose (SD) abdominal MDCT, 50 patients (mean age, 57.7 years; mean BMI, 28.8) underwent a second reduced-dose (RD) scan (targeted dose reduction, 70-90%). DLP, CTDIvol and SSDE were compared. Several reconstruction algorithms (FBP, ASIR, and PICCS) were applied to the RD series. SD images with FBP served as reference standard. Two blinded readers evaluated each series for subjective image quality and focal lesion detection. Results Mean DLP, CTDIvol, and SSDE for RD series was 140.3 mGy*cm (median 79.4), 3.7 mGy (median 1.8), and 4.2 mGy (median 2.3) compared with 493.7 mGy*cm (median 345.8), 12.9 mGy (median 7.9 mGy) and 14.6 mGy (median 10.1) for SD series, respectively. Mean effective patient diameter was 30.1 cm (median 30), which translates to a mean SSDE reduction of 72% (p<0.001). RD-PICCS image quality score was 2.8±0.5, improved over the RD-FBP (1.7±0.7) and RD-ASIR(1.9±0.8)(p<0.001), but lower than SD (3.5±0.5)(p<0.001). Readers detected 81% (184/228) of focal lesions on RD-PICCS series, versus 67% (153/228) and 65% (149/228) for RD-FBP and RD-ASIR, respectively. Mean image noise was significantly reduced on RD-PICCS series (13.9 HU) compared with RD-FBP (57.2) and RD-ASIR (44.1) (p<0.001). Conclusion PICCS allows for marked dose reduction at abdominal CT with improved image quality and diagnostic performance over reduced-dose FBP and ASIR. Further study is needed to determine indication-specific dose reduction levels that preserve acceptable diagnostic accuracy relative to higher-dose protocols. PMID:24943136