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Sample records for high-dose three-dimensional radiation

  1. Radiative transfer for a three-dimensional raining cloud

    NASA Technical Reports Server (NTRS)

    Haferman, J. L.; Krajewski, W. F.; Smith, T. F.; Sanchez, A.

    1993-01-01

    Satellite-sensor-based microwave brightness temperatures for a three-dimensional raining cloud over a reflecting surface are computed by using a radiative transfer model based on the discrete-ordinates solution procedure. The three-dimensional model applied to a plane layer is validated by comparison with results from a one-dimensional model that is available in the literature. Results examining the effects of cloud height, rainfall rate, surface reflectance, rainfall footprint area, and satellite viewing position on one- and three-dimensional brightness temperature calculations are reported. The numerical experiments indicate that, under certain conditions, three-dimensional effects are significant in the analysis of satellite-sensor-based rainfall retrieval algorithms. The results point to the need to consider carefully three-dimensional effects as well as surface reflectance effects when interpreting satellite-measured radiation data.

  2. Cone Beam CT-Based Three-Dimensional Planning in High-Dose-Rate Brachytherapy for Cervical Cancer

    SciTech Connect

    Al-Halabi, Hani; Portelance, Lorraine; Duclos, Marie; Reniers, Brigitte; Bahoric, Boris; Souhami, Luis

    2010-07-15

    Purpose: To evaluate dose-volume histograms (DVHs) of bladder and rectum from the use of cone beam CT (CBCT)-based three-dimensional (3D) treatment planning in intracavitary high-dose-rate brachytherapy (HDRB) for cervical cancer patients and to compare these parameters with International Commission on Radiation Units and Measurements (ICRU) of rectal and bladder reference point dose measurements. Methods and Materials: Thirteen patients with cervical cancer underwent HDRB insertions. CT-compatible tandem and ovoid applicators were used to obtain intraoperative CBCT images. The use of a rectal tube and injection of bladder contrast before scanning facilitated contouring the rectum and bladder. All patients underwent intraoperative orthogonal x-ray filming, and treatments were prescribed using standard two-dimensional planning and dosimetry. DVHs for the bladder and rectum were constructed for each treatment. The minimum dose in the most irradiated 2.0-cm{sup 3} volume of bladder (B{sub D2V}) and rectum (R{sub D2V}) were determined from DVHs and compared to ICRU reference point estimates of bladder (B{sub ICRU}) and rectum (R{sub ICRU}) doses. Results: Twenty-six CBCT-based plans were evaluated. The median B{sub ICRU} dose (347 cGy; range, 164-601 cGy) was significantly lower (p < 0.001) than the median B{sub D2V} (594 cGy; range, 260-969 cGy). The median R{sub ICRU} dose (405 cGy; range, 189-700 cGy) was also significantly lower (p = 0.037) than the median R{sub D2V} (488 cGy; range, 227-786 cGy). Conclusions: CBCT-based 3D planning can be used in HDRB for cervical cancer and is a convenient alternative to CT-based planning, with the advantage of minimizing applicator motion. Correlation with late effects will further define the role of CBCT-based 3D dosimetry in HDRB planning.

  3. Radiation hardness of three-dimensional polycrystalline diamond detectors

    SciTech Connect

    Lagomarsino, Stefano Sciortino, Silvio; Bellini, Marco; Corsi, Chiara; Cindro, Vladimir; Kanxheri, Keida; Servoli, Leonello; Morozzi, Arianna; Passeri, Daniele; Schmidt, Christian J.

    2015-05-11

    The three-dimensional concept in particle detection is based on the fabrication of columnar electrodes perpendicular to the surface of a solid state radiation sensor. It permits to improve the radiation resistance characteristics of a material by lowering the necessary bias voltage and shortening the charge carrier path inside the material. If applied to a long-recognized exceptionally radiation-hard material like diamond, this concept promises to pave the way to the realization of detectors of unprecedented performances. We fabricated conventional and three-dimensional polycrystalline diamond detectors, and tested them before and after neutron damage up to 1.2 ×10{sup 16 }cm{sup −2}, 1 MeV-equivalent neutron fluence. We found that the signal collected by the three-dimensional detectors is up to three times higher than that of the conventional planar ones, at the highest neutron damage ever experimented.

  4. Prospective Clinical Trial of Bladder Filling and Three-Dimensional Dosimetry in High-Dose-Rate Vaginal Cuff Brachytherapy

    SciTech Connect

    Stewart, Alexandra J.; Cormack, Robert A.; Lee, Hang; Xiong Li; Hansen, Jorgen L.; O'Farrell, Desmond A.; Viswanathan, Akila N.

    2008-11-01

    Purpose: To investigate the effect of bladder filling on dosimetry and to determine the best bladder dosimetric parameter for vaginal cuff brachytherapy. Methods and Materials: In this prospective clinical trial, a total of 20 women underwent vaginal cylinder high-dose-rate brachytherapy. The bladder was full for Fraction 2 and empty for Fraction 3. Dose-volume histogram and dose-surface histogram values were generated for the bladder, rectum, and urethra. The midline maximal bladder point (MBP) and the midline maximal rectal point were recorded. Paired t tests, Pearson correlations, and regression analyses were performed. Results: The volume and surface area of the irradiated bladder were significantly smaller when the bladder was empty than when full. Of the several dose-volume histogram and dose-surface histogram parameters evaluated, the bladder maximal dose received by 2 cm{sup 3} of tissue, volume of bladder receiving {>=}50% of the dose, volume of bladder receiving {>=}70% of the dose, and surface area of bladder receiving {>=}50% of the dose significantly predicted for the difference between the empty vs. full filling state. The volume of bladder receiving {>=}70% of the dose and the maximal dose received by 2 cm{sup 3} of tissue correlated significantly with the MBP. Bladder filling did not alter the volume or surface area of the rectum irradiated. However, an empty bladder did result in the nearest point of bowel being significantly closer to the vaginal cylinder than when the bladder was full. Conclusions: Patients undergoing vaginal cuff brachytherapy treated with an empty bladder have a lower bladder dose than those treated with a full bladder. The MBP correlated well with the volumetric assessments of bladder dose and provided a noninvasive method for reporting the MBP dose using three-dimensional imaging. The MBP can therefore be used as a surrogate for complex dosimetry in the clinic.

  5. High dose bystander effects in spatially fractionated radiation therapy

    PubMed Central

    Asur, Rajalakshmi; Butterworth, Karl T.; Penagaricano, Jose A.; Prise, Kevin M.; Griffin, Robert J.

    2014-01-01

    Traditional radiotherapy of bulky tumors has certain limitations. Spatially fractionated radiation therapy (GRID) and intensity modulated radiotherapy (IMRT) are examples of advanced modulated beam therapies that help in significant reductions in normal tissue damage. GRID refers to the delivery of a single high dose of radiation to a large treatment area that is divided into several smaller fields, while IMRT allows improved dose conformity to the tumor target compared to conventional three-dimensional conformal radiotherapy. In this review, we consider spatially fractionated radiotherapy approaches focusing on GRID and IMRT, and present complementary evidence from different studies which support the role of radiation induced signaling effects in the overall radiobiological rationale for these treatments. PMID:24246848

  6. High-dose-rate Three-dimensional Conformal Radiotherapy Combined with Active Breathing Control for Stereotactic Body Radiotherapy of Early-stage Non-small-cell Lung Cancer.

    PubMed

    Wang, Ruozheng; Yin, Yong; Qin, Yonghui; Yu, Jinming

    2015-12-01

    The purpose of this study was to evaluate the feasibility and benefits of using high-dose-rate three-dimensional conformal radiotherapy (3D-CRT) combined with active breathing control (ABC) for stereotactic body radiotherapy (SBRT) of patients with early-stage non-small-cell lung cancer (NSCLC). Eight patients with early-stage NSCLC underwent CT scans under standard free-breathing (FB) and moderately deep inspiration breath-hold (mDIBH) with ABC. Two high-dose-rate 3D-CRT plans (1000 Mu/min) were designed based on the CT scans with FB and mDIBH. The maximal dose (D1%), minimal dose (D99%), conformity index (CI), and homogeneity index (HI) of the planning target volume (PTV), and dose-volume indices of the organs at risk between each plan were compared. The mean PTV volume decreased from 158.04 cm(3) with FB to 76.90 cm(3) with mDIBH (p < 0.05). When mDIBH was used, increases in the affected lung volume (by 47%), contralateral lung volume (by 55%), and total lung volume (by 50%) were observed compared to FB (p < 0.05). The V5-V40 of the affected lung (Vx represented the percentage volume of organs receiving at least the x Gy), V5-V40 and the mean dose for the total lung, V5-V40 and mean dose of the chest wall, and the maximum dose of the spinal cord were less for mDIBH than FB (p < 0.05). There were no significant differences in CI, HI, D1%, or D99% for the PTV between the plans. In conclusion, high-dose-rate 3D-CRT combined with ABC reduced the radiation dose to the lungs and chest wall without affecting the dose distribution in SBRT of early-stage NSCLC patients. PMID:24988055

  7. TWILIGHT: A Cellular Framework for Three-Dimensional Radiative Transfer

    NASA Astrophysics Data System (ADS)

    Khatami, David; Madore, Barry

    2015-01-01

    We describe a new framework for solving three-dimensional radiative transfer of arbitrary geometries, including a full characterisation of the wavelength-dependent anisotropic scattering, absorption, and thermal reemission of light by dust. By adopting a cellular approach to discretising the light and dust, the problem can be efficiently solved through a fully deterministic iterative process. As a proof of concept we present TWILIGHT, our implementation of the cellular approach, in order to demonstrate and benchmark the new method. TWILIGHT simultaneously renders over one hundred unique images of a given environment with no additional slowdown, enabling a close study of inclination effects of three-dimensional dust geometries. In addition to qualitative rendering tests, TWILIGHT is successfully tested against two Monte-Carlo radiative transfer benchmarks, producing similar brightness profiles at varying inclinations. With the proof-of-concept established, we describe the improvements and current developments underway using the cellular framework, including a technique to resolve the subgrid physics of dust radiative transfer from micron-scale grain models to kiloparsec-sized dust environments.

  8. Realistic three-dimensional radiative transfer simulations of observed precipitation

    NASA Astrophysics Data System (ADS)

    Adams, I. S.; Bettenhausen, M. H.

    2013-12-01

    Remote sensing observations of precipitation typically utilize a number of instruments on various platforms. Ground validation campaigns incorporate ground-based and airborne measurements to characterize and study precipitating clouds, while the precipitation measurement constellation envisioned by the Global Precipitation Measurement (GPM) mission includes measurements from differing space-borne instruments. In addition to disparities such as frequency channel selection and bandwidth, measurement geometry and resolution differences between observing platforms result in inherent inconsistencies between data products. In order to harmonize measurements from multiple passive radiometers, a framework is required that addresses these differences. To accomplish this, we have implemented a flexible three-dimensional radiative transfer model. As its core, the radiative transfer model uses the Atmospheric Radiative Transfer Simulator (ARTS) version 2 to solve the radiative transfer equation in three dimensions using Monte Carlo integration. Gaseous absorption is computed with MonoRTM and formatted into look-up tables for rapid processing. Likewise, scattering properties are pre-computed using a number of publicly available codes, such as T-Matrix and DDSCAT. If necessary, a melting layer model can be applied to the input profiles. Gaussian antenna beams estimate the spatial resolutions of the passive measurements, and realistic bandpass characteristics can be included to properly account for the spectral response of the simulated instrument. This work presents three-dimensional simulations of WindSat brightness temperatures for an oceanic rain event sampled by the Tropical Rainfall Measuring Mission (TRMM) satellite. The 2B-31 combined Precipitation Radar / TRMM Microwave Imager (TMI) retrievals provide profiles that are the input to the radiative transfer model. TMI brightness temperatures are also simulated. Comparisons between monochromatic, pencil beam simulations and

  9. Three-Dimensional Radiative Transfer on a Massively Parallel Computer.

    NASA Astrophysics Data System (ADS)

    Vath, Horst Michael

    1994-01-01

    We perform three-dimensional radiative transfer calculations on the MasPar MP-1, which contains 8192 processors and is a single instruction multiple data (SIMD) machine, an example of the new generation of massively parallel computers. To make radiative transfer calculations efficient, we must re-consider the numerical methods and methods of storage of data that have been used with serial machines. We developed a numerical code which efficiently calculates images and spectra of astrophysical systems as seen from different viewing directions and at different wavelengths. We use this code to examine a number of different astrophysical systems. First we image the HI distribution of model galaxies. Then we investigate the galaxy NGC 5055, which displays a radial asymmetry in its optical appearance. This can be explained by the presence of dust in the outer HI disk far beyond the optical disk. As the formation of dust is connected to the presence of stars, the existence of dust in outer regions of this galaxy could have consequences for star formation at a time when this galaxy was just forming. Next we use the code for polarized radiative transfer. We first discuss the numerical computation of the required cyclotron opacities and use them to calculate spectra of AM Her systems, binaries containing accreting magnetic white dwarfs. Then we obtain spectra of an extended polar cap. Previous calculations did not consider the three -dimensional extension of the shock. We find that this results in a significant underestimate of the radiation emitted in the shock. Next we calculate the spectrum of the intermediate polar RE 0751+14. For this system we obtain a magnetic field of ~10 MG, which has consequences for the evolution of intermediate polars. Finally we perform 3D radiative transfer in NLTE in the two-level atom approximation. To solve the transfer equation in this case, we adapt the short characteristic method and examine different acceleration methods to obtain the

  10. Radiation dosimetry using three-dimensional optical random access memories

    NASA Technical Reports Server (NTRS)

    Moscovitch, M.; Phillips, G. W.

    2001-01-01

    Three-dimensional optical random access memories (3D ORAMs) are a new generation of high-density data storage devices. Binary information is stored and retrieved via a light induced reversible transformation of an ensemble of bistable photochromic molecules embedded in a polymer matrix. This paper describes the application of 3D ORAM materials to radiation dosimetry. It is shown both theoretically and experimentally, that ionizing radiation in the form of heavy charged particles is capable of changing the information originally stored on the ORAM material. The magnitude and spatial distribution of these changes are used as a measure of the absorbed dose, particle type and energy. The effects of exposure on 3D ORAM materials have been investigated for a variety of particle types and energies, including protons, alpha particles and 12C ions. The exposed materials are observed to fluoresce when exposed to laser light. The intensity and the depth of the fluorescence is dependent on the type and energy of the particle to which the materials were exposed. It is shown that these effects can be modeled using Monte Carlo calculations. The model provides a better understanding of the properties of these materials. which should prove useful for developing systems for charged particle and neutron dosimetry/detector applications. c2001 Published by Elsevier Science B.V.

  11. THREE-DIMENSIONAL RADIATION TRANSFER IN YOUNG STELLAR OBJECTS

    SciTech Connect

    Whitney, B. A.; Honor, J.; Robitaille, T. P.; Bjorkman, J. E.; Dong, R.; Wolff, M. J.; Wood, K.

    2013-08-15

    We have updated our publicly available dust radiative transfer code (HOCHUNK3D) to include new emission processes and various three-dimensional (3D) geometries appropriate for forming stars. The 3D geometries include warps and spirals in disks, accretion hotspots on the central star, fractal clumping density enhancements, and misaligned inner disks. Additional axisymmetric (2D) features include gaps in disks and envelopes, ''puffed-up inner rims'' in disks, multiple bipolar cavity walls, and iteration of disk vertical structure assuming hydrostatic equilibrium (HSEQ). We include the option for simple power-law envelope geometry, which, combined with fractal clumping and bipolar cavities, can be used to model evolved stars as well as protostars. We include non-thermal emission from polycyclic aromatic hydrocarbons (PAHs) and very small grains, and external illumination from the interstellar radiation field. The grid structure was modified to allow multiple dust species in each cell; based on this, a simple prescription is implemented to model dust stratification. We describe these features in detail, and show example calculations of each. Some of the more interesting results include the following: (1) outflow cavities may be more clumpy than infalling envelopes. (2) PAH emission in high-mass stars may be a better indicator of evolutionary stage than the broadband spectral energy distribution slope; and related to this, (3) externally illuminated clumps and high-mass stars in optically thin clouds can masquerade as young stellar objects. (4) Our HSEQ models suggest that dust settling is likely ubiquitous in T Tauri disks, in agreement with previous observations.

  12. CT based three dimensional dose-volume evaluations for high-dose rate intracavitary brachytherapy for cervical cancer

    PubMed Central

    2014-01-01

    Background In this study, high risk clinical target volumes (HR-CTVs) according to GEC-ESTRO guideline were contoured retrospectively based on CT images taken at the time of high-dose rate intracavitary brachytherapy (HDR-ICBT) and correlation between clinical outcome and dose of HR-CTV were analyzed. Methods Our study population consists of 51 patients with cervical cancer (Stages IB-IVA) treated with 50 Gy external beam radiotherapy (EBRT) using central shield combined with 2–5 times of 6 Gy HDR-ICBT with or without weekly cisplatin. Dose calculation was based on Manchester system and prescribed dose of 6 Gy were delivered for point A. CT images taken at the time of each HDR-ICBT were reviewed and HR-CTVs were contoured. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (α/β = 10 Gy). Results Three-year overall survival, Progression-free survival, and local control rate was 82.4%, 85.3% and 91.7%, respectively. Median cumulative dose of HR-CTV D90 was 65.0 Gy (52.7-101.7 Gy). Median length from tandem to the most lateral edge of HR-CTV at the first ICBT was 29.2 mm (range, 18.0-51.9 mm). On univariate analysis, both LCR and PFS was significantly favorable in those patients D90 for HR-CTV was 60 Gy or greater (p = 0.001 and 0.03, respectively). PFS was significantly favorable in those patients maximum length from tandem to edge of HR-CTV at first ICBT was shorter than 3.5 cm (p = 0.042). Conclusion Volume-dose showed a relationship to the clinical outcome in CT based brachytherapy for cervical carcinoma. PMID:24938757

  13. Three-dimensional, position-sensitive radiation detection

    DOEpatents

    He, Zhong; Zhang, Feng

    2010-04-06

    Disclosed herein is a method of determining a characteristic of radiation detected by a radiation detector via a multiple-pixel event having a plurality of radiation interactions. The method includes determining a cathode-to-anode signal ratio for a selected interaction of the plurality of radiation interactions based on electron drift time data for the selected interaction, and determining the radiation characteristic for the multiple-pixel event based on both the cathode-to-anode signal ratio and the electron drift time data. In some embodiments, the method further includes determining a correction factor for the radiation characteristic based on an interaction depth of the plurality of radiation interactions, a lateral distance between the selected interaction and a further interaction of the plurality of radiation interactions, and the lateral positioning of the plurality of radiation interactions.

  14. Preliminary results of a three-dimensional radiative transfer model

    SciTech Connect

    O`Hirok, W.

    1995-09-01

    Clouds act as the primary modulator of the Earth`s radiation at the top of the atmosphere, within the atmospheric column, and at the Earth`s surface. They interact with both shortwave and longwave radiation, but it is primarily in the case of shortwave where most of the uncertainty lies because of the difficulties in treating scattered solar radiation. To understand cloud-radiative interactions, radiative transfer models portray clouds as plane-parallel homogeneous entities to ease the computational physics. Unfortunately, clouds are far from being homogeneous, and large differences between measurement and theory point to a stronger need to understand and model cloud macrophysical properties. In an attempt to better comprehend the role of cloud morphology on the 3-dimensional radiation field, a Monte Carlo model has been developed. This model can simulate broadband shortwave radiation fluxes while incorporating all of the major atmospheric constituents. The model is used to investigate the cloud absorption anomaly where cloud absorption measurements exceed theoretical estimates and to examine the efficacy of ERBE measurements and cloud field experiments. 3 figs.

  15. Understanding Accretion Disks through Three Dimensional Radiation MHD Simulations

    NASA Astrophysics Data System (ADS)

    Jiang, Yan-Fei

    I study the structures and thermal properties of black hole accretion disks in the radiation pressure dominated regime. Angular momentum transfer in the disk is provided by the turbulence generated by the magneto-rotational instability (MRI), which is calculated self-consistently with a recently developed 3D radiation magneto-hydrodynamics (MHD) code based on Athena. This code, developed by my collaborators and myself, couples both the radiation momentum and energy source terms with the ideal MHD equations by modifying the standard Godunov method to handle the stiff radiation source terms. We solve the two momentum equations of the radiation transfer equations with a variable Eddington tensor (VET), which is calculated with a time independent short characteristic module. This code is well tested and accurate in both optically thin and optically thick regimes. It is also accurate for both radiation pressure and gas pressure dominated flows. With this code, I find that when photon viscosity becomes significant, the ratio between Maxwell stress and Reynolds stress from the MRI turbulence can increase significantly with radiation pressure. The thermal instability of the radiation pressure dominated disk is then studied with vertically stratified shearing box simulations. Unlike the previous results claiming that the radiation pressure dominated disk with MRI turbulence can reach a steady state without showing any unstable behavior, I find that the radiation pressure dominated disks always either collapse or expand until we have to stop the simulations. During the thermal runaway, the heating and cooling rates from the simulations are consistent with the general criterion of thermal instability. However, details of the thermal runaway are different from the predictions of the standard alpha disk model, as many assumptions in that model are not satisfied in the simulations. We also identify the key reasons why previous simulations do not find the instability. The thermal

  16. Three Dimensional Radiative Transfer In Tropical Deep Convective Clouds.

    NASA Astrophysics Data System (ADS)

    di Giuseppe, F.

    In this study the focus is on the interaction between short-wave radiation with a field of tropical deep convective events generated using a 3D cloud resolving model (CRM) to assess the significance of 3D radiative transport (3DRT). It is not currently un- derstood what magnitude of error is involved when a two stream approximation is used to describe the radiative transfer through such a cloud field. It seems likely that deep convective clouds could be the most complex to represent, and that the error in neglecting horizontal transport could be relevant in these cases. The field here con- sidered has an extention of roughly 90x90 km, approximately equivalent to the grid box dimension of many global models. The 3DRT results are compared both with the calculations obtained by an Independent Pixel Approximation (IPA) approch and by the Plane Parallel radiative scheme (PP) implemented in ECMWF's Forecast model. The differences between the three calculations are used to assess both problems in current GCM's representation of radiative heating and inaccuracies in the dynamical response of CRM simulations due to the Independent Column Approximation (ICA). The understanding of the mechanisms involved in the main 3DRT/1D differences is the starting point for the future attempt to develop a parameterization procedure.

  17. Three-dimensional architecture for solid state radiation detectors

    DOEpatents

    Parker, Sherwood

    1999-01-01

    A radiation-damage resistant radiation detector is formed on a substrate formed of a material doped with a first conductivity type dopant. The detector includes at least one first electrode formed of first conductivity type dopant, and at least one second electrode that is spaced-apart from the first electrode and formed of a second conductivity type dopant. Each first and second electrode penetrates into the substrate from a substrate surface, and one or more electrodes may penetrate entirely through the substrate, that is traversing from one surface to the other surface. Particulate and/or electromagnetic radiation penetrating at least a surface of the substrate releases electrons and holes in substrate regions. Because the electrodes may be formed entirely through the substrate thickness, the released charges will be a relatively small distance from at least a portion of such an electrode, e.g., a distance less than the substrate thickness. The electrons and/or holes traverse the small distance and are collected by said electrodes, thus promoting rapid detection of the radiation. By providing one or more electrodes with a dopant profile radially graded in a direction parallel to a substrate surface, an electric field results that promotes rapid collection of released electrons and said holes. Monolithic combinations of such detectors may be fabricated including CMOS electronics to process radiation signals.

  18. Three-dimensional architecture for solid state radiation detectors

    DOEpatents

    Parker, S.

    1999-03-30

    A radiation-damage resistant radiation detector is formed on a substrate formed of a material doped with a first conductivity type dopant. The detector includes at least one first electrode formed of first conductivity type dopant, and at least one second electrode that is spaced-apart from the first electrode and formed of a second conductivity type dopant. Each first and second electrode penetrates into the substrate from a substrate surface, and one or more electrodes may penetrate entirely through the substrate, that is traversing from one surface to the other surface. Particulate and/or electromagnetic radiation penetrating at least a surface of the substrate releases electrons and holes in substrate regions. Because the electrodes may be formed entirely through the substrate thickness, the released charges will be a relatively small distance from at least a portion of such an electrode, e.g., a distance less than the substrate thickness. The electrons and/or holes traverse the small distance and are collected by said electrodes, thus promoting rapid detection of the radiation. By providing one or more electrodes with a dopant profile radially graded in a direction parallel to a substrate surface, an electric field results that promotes rapid collection of released electrons and said holes. Monolithic combinations of such detectors may be fabricated including CMOS electronics to process radiation signals. 45 figs.

  19. Three Dimensional Atmospheric Radiative Transfer-Applications and Methods Comparison

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    We review applications of 3D radiative transfer in the atmosphere, emphasizing the wide spectrum of scales important to remote sensing and modeling of cloud fields, and the characteristic scales introduced into observed radiances and fluxes by the distribution of photon pathlengths at conservative and absorbing wavelengths. We define the "plane-parallel bias", which is a measure of the importance of 3D cloud structure in large-scale models, and the "independent pixel errors" that quantify the significance of 3D effects in remote sensing, and emphasize their relative magnitude and scale dependence. A variety of approaches in current use in 3D radiative transfer, and issues of speed, accuracy, and flexibility are summarized. We also describe a recently initiated "International Intercomparison of 3-Dimensional Radiation Codes", or I3RC. I3RC is a 3-phase effort that has as its goals to: (1) understand the errors and limits of 3D methods; (2) provide "baseline" cases for future 3D code development; (3) promote sharing of 3D tools; (4) derive guidelines for 3D tool selection; and (5) improve atmospheric science education in 3D radiative transfer. Selected results from Phases 1 and 2 of I3RC are discussed. These are taken from five cloud fields: a 1D field of bar clouds, a 2D radar-derived field, a 3D Landsat-derived field, a stratiform cloud from the model of C. Moeng, and a convective cloud from the model of B. Stevens. Computations have been carried out for three monochromatic wavelengths (one conservative, one absorptive, and one thermal) and two solar zenith angles (0, 60 degrees).

  20. Formation of globular clusters induced by external ultraviolet radiation II: Three-dimensional radiation hydrodynamics simulations

    NASA Astrophysics Data System (ADS)

    Abe, Makito; Umemura, Masayuki; Hasegawa, Kenji

    2016-08-01

    We explore the possibility of the formation of globular clusters under ultraviolet (UV) background radiation. One-dimensional spherical symmetric radiation hydrodynamics (RHD) simulations by Hasegawa et al. have demonstrated that the collapse of low-mass (106-7 M⊙) gas clouds exposed to intense UV radiation can lead to the formation of compact star clusters like globular clusters (GCs) if gas clouds contract with supersonic infall velocities. However, three-dimensional effects, such as the anisotropy of background radiation and the inhomogeneity in gas clouds, have not been studied so far. In this paper, we perform three-dimensional RHD simulations in a semi-cosmological context, and reconsider the formation of compact star clusters in strong UV radiation fields. As a result, we find that although anisotropic radiation fields bring an elongated shadow of neutral gas, almost spherical compact star clusters can be procreated from a "supersonic infall" cloud, since photo-dissociating radiation suppresses the formation of hydrogen molecules in the shadowed regions and the regions are compressed by UV heated ambient gas. The properties of resultant star clusters match those of GCs. On the other hand, in weak UV radiation fields, dark matter-dominated star clusters with low stellar density form due to the self-shielding effect as well as the positive feedback by ionizing photons. Thus, we conclude that the "supersonic infall" under a strong UV background is a potential mechanism to form GCs.

  1. Three-dimensional radiative transfer on a massively parallel computer

    NASA Astrophysics Data System (ADS)

    Vath, H. M.

    1994-04-01

    We perform 3D radiative transfer calculations in non-local thermodynamic equilibrium (NLTE) in the simple two-level atom approximation on the Mas-Par MP-1, which contains 8192 processors and is a single instruction multiple data (SIMD) machine, an example of the new generation of massively parallel computers. On such a machine, all processors execute the same command at a given time, but on different data. To make radiative transfer calculations efficient, we must re-consider the numerical methods and storage of data. To solve the transfer equation, we adopt the short characteristic method and examine different acceleration methods to obtain the source function. We use the ALI method and test local and non-local operators. Furthermore, we compare the Ng and the orthomin methods of acceleration. We also investigate the use of multi-grid methods to get fast solutions for the NLTE case. In order to test these numerical methods, we apply them to two problems with and without periodic boundary conditions.

  2. Delay-Line Three-Dimensional Position Sensitive Radiation Detection

    NASA Astrophysics Data System (ADS)

    Jeong, Manhee

    High-resistivity silicon(Si) in large volumes and with good charge carrier transport properties has been produced and achieved success as a radiation detector material over the past few years due to its relatively low cost as well as the availability of well-established processing technologies. One application of that technology is in the fabrication of various position-sensing topologies from which the incident radiation's direction can be determined. We have succeeded in developing the modeling tools for investigating different position-sensing schemes and used those tools to examine both amplitude-based and time-based methods, an assessment that indicates that fine position-sensing can be achieved with simpler readout designs than are conventionally deployed. This realization can make ubiquitous and inexpensive deployment of special nuclear materials (SNM) detecting technology becomes more feasible because if one can deploy position-sensitive semiconductor detectors with only one or two contacts per side. For this purpose, we have described the delay-line radiation detector and its optimized fabrication. The semiconductor physics were simulated, the results from which guided the fabrication of the guard ring structure and the detector electrode, both of which included metal-field-plates. The measured improvement in the leakage current was confirmed with the fabricated devices, and the structures successfully suppressed soft-breakdown. We also demonstrated that fabricating an asymmetric strip-line structure successfully minimizing the pulse shaping and increases the distance through which one can propagate the information of the deposited charge distribution. With fabricated delay-line detectors we can acquire alpha spectra (Am-241) and gamma spectra (Ba-133, Co-57 and Cd-109). The delay-line detectors can therefore be used to extract the charge information from both ion and gamma-ray interactions. Furthermore, standard charge-sensitive circuits yield high SNR

  3. Measurement of three-dimensional radiation dose distributions using MRI.

    PubMed

    Prasad, P V; Nalcioglu, O; Rabbani, B

    1991-10-01

    Recent investigations have shown that nuclear magnetic resonance (NMR) can be used in conjunction with a suitable chemical dosimeter to estimate the dose from ionizing radiation (Gore et al., Phys Med. Biol. 29, 1189-1197, 1984). Based on this fact it was proposed that spatial dose distributions can be measured in gels infused with the chemical dosimeter using NMR imaging. There have been few such attempts and they provided only qualitative results. In this paper, we report results demonstrating the feasibility of obtaining quantitative dose distribution measurements by this technique. It is shown that quantitative dose distribution measurements necessitate the calculation of relaxation rate maps. We have determined that the spin-spin relaxation rate is a more sensitive parameter than the spin-lattice relaxation rate. It is also demonstrated that the addition of chemical sensitizers could improve the dose sensitivity of the measured NMR parameters. The two features characterizing a photon beam, depth-dose relationship, and beam profile as measured by this technique are in good agreement with the measurements using conventional methods, ionization chambers, and film dosimetry. PMID:1924718

  4. Three-dimensional imaging of optically opaque materials using nonionizing terahertz radiation.

    PubMed

    Wallace, Vincent P; Macpherson, Emma; Zeitler, J Axel; Reid, Caroline

    2008-12-01

    Terahertz electromagnetic radiation has already been shown to have a wide number of uses. We consider specific applications of terahertz time-domain imaging that are inherently three-dimensional. This paper highlights the ability of terahertz radiation to reveal subsurface information as we exploit the fact that the radiation can penetrate optically opaque materials such as clothing, cardboard, plastics, and to some extent biological tissue. Using interactive science publishing tools, we concentrate on full three-dimensional terahertz data from three specific areas of application, namely, security, pharmaceutical, and biomedical. PMID:19037404

  5. Three-dimensional radiation dosimetry for gamma knife using a gel dosimeter

    NASA Astrophysics Data System (ADS)

    Hussain, Kazi Muazzam

    The use of three-dimensional radiation dosimetry has been limited. With the use of water phantoms and ionization chambers, it has been possible to determine three dimensional dose distributions on a gross scale for cobalt 60 and linear accelerator sources. This method has been somewhat useful for traditional radiotherapy. There is, however, a need for more precise dosimetry, particularly with stereotactic radiosurgery. Most gamma knife facilities use either thermoluminescant dosimetry or film, neither of which provides three dimensional dose distributions. To overcome this limitation, we have developed a gel dosimetry system that relies on the production of a ferric ion-xylenol orange colored complex. This work demonstrates the use of laser light and a detector to quantify radiation-induced colorimetric changes in absorbance for the gel dosimeter. The absorbance has been reconstructed by the back projection technique to demonstrate the applicability of the gel dosimeter to gamma knife 3D-dose distributions.

  6. Three-dimensional visualization of shear wave propagation generated by dual acoustic radiation pressure

    NASA Astrophysics Data System (ADS)

    Mochizuki, Yuta; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    An elastic property of biological soft tissue is an important indicator of the tissue status. Therefore, quantitative and noninvasive methods for elasticity evaluation have been proposed. Our group previously proposed a method using acoustic radiation pressure irradiated from two directions for elastic property evaluation, in which by measuring the propagation velocity of the shear wave generated by the acoustic radiation pressure inside the object, the elastic properties of the object were successfully evaluated. In the present study, we visualized the propagation of the shear wave in a three-dimensional space by the synchronization of signals received at various probe positions. The proposed method succeeded in visualizing the shear wave propagation clearly in the three-dimensional space of 35 × 41 × 4 mm3. These results show the high potential of the proposed method to estimate the elastic properties of the object in the three-dimensional space.

  7. Equivalent Biochemical Control and Improved Prostate-Specific Antigen Nadir After Permanent Prostate Seed Implant Brachytherapy Versus High-Dose Three-Dimensional Conformal Radiotherapy and High-Dose Conformal Proton Beam Radiotherapy Boost

    SciTech Connect

    Jabbari, Siavash; Weinberg, Vivian K.; Shinohara, Katsuto; Speight, Joycelyn L.; Gottschalk, Alexander R.; Hsu, I.-C.; Pickett, Barby; McLaughlin, Patrick W.; Sandler, Howard M.; Roach, Mack

    2010-01-15

    Purpose: Permanent prostate implant brachytherapy (PPI), three-dimensional conformal radiotherapy (3D-CRT), and conformal proton beam radiotherapy (CPBRT) are used in the treatment of localized prostate cancer, although no head-to-head trials have compared these modalities. We studied the biochemical control (biochemical no evidence of disease [bNED]) and prostate-specific antigen (PSA) nadir achieved with contemporary PPI, and evaluated it against 3D-CRT and CPBRT. Patients and Methods: A total of 249 patients were treated with PPI at the University of California, San Francisco, and the outcomes were compared with those from a 3D-CRT cohort and the published results of a high-dose CPBRT boost (CPBRTB) trial. For each comparison, subsets of the PPI cohort were selected with patient and disease criteria similar to those of the reference group. Results: With a median follow-up of 5.3 years, the bNED rate at 5 and 7 years achieved with PPI was 92% and 86%, respectively, using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition, and 93% using the PSA nadir plus 2 ng/mL definition. Using the ASTRO definition, a 5-year bNED rate of 78% was achieved for the 3D-CRT patients compared with 94% for a comparable PPI subset and 93% vs. 92%, respectively, using the PSA nadir plus 2 ng/mL definition. The median PSA nadir for patients treated with PPI and 3D-CRT was 0.10 and 0.40 ng/mL, respectively (p < .0001). For the CPBRT comparison, the 5-year bNED rate after a CPBRTB was 91% using the ASTRO definition vs. 93% for a similar group of PPI patients. A greater proportion of PPI patients achieved a lower PSA nadir compared with those achieved in the CPBRTB trial (PSA nadir <=0.5 ng/mL, 91% vs. 59%, respectively). Conclusion: We have demonstrated excellent outcomes in low- to intermediate-risk patients treated with PPI, suggesting at least equivalent 5-year bNED rates and a greater proportion of men achieving lower PSA nadirs compared with 3D-CRT or

  8. Multigroup Three-Dimensional Direct Integration Method Radiation Transport Analysis Code System.

    Energy Science and Technology Software Center (ESTSC)

    1987-09-18

    Version 00 TRISTAN solves the three-dimensional, fixed-source, Boltzmann transport equation for neutrons or gamma rays in rectangular geometry. The code can solve an adjoint problem as well as a usual transport problem. TRISTAN is a suitable tool to analyze radiation shielding problems such as streaming and deep penetration problems.

  9. High-resolution three-dimensional imaging by synchrotron-radiation computed laminography

    NASA Astrophysics Data System (ADS)

    Helfen, L.; Baumbach, T.; Pernot, P.; Mikulík, P.; DiMichiel, M.; Baruchel, J.

    2006-08-01

    The methodical development and first instrumental implementation of computed laminography / tomosynthesis using synchrotron radiation are presented. The technique was developed for three-dimensional imaging of flat and laterally extended objects with high spatial resolution. This paper introduces the fundamental principle of the imaging process and discusses the method's particularities in comparison to computed tomography and computed laminography / digital tomosynthesis. Introducing a simple scanning geometry adapted to the particular experimental conditions of synchrotron imaging set-ups (such as the stationary source and a parallel beam) allows us to combine the advantages of laminography and those provided by synchrotron radiation, for instance monochromatic radiation in order to avoid beam hardening artefacts, high beam intensity for achieving high spatial resolution and fast scanning times or spatial coherence for exploiting phase contrast. The potential of the method for three-dimensional imaging of microelectronic devices is demonstrated by examples of flip-chip bonded and wire-bonded devices.

  10. Recent Developments in Three Dimensional Radiation Transport Using the Green's Function Technique

    NASA Technical Reports Server (NTRS)

    Rockell, Candice; Tweed, John; Blattnig, Steve R.; Mertens, Christopher J.

    2010-01-01

    In the future, astronauts will be sent into space for longer durations of time compared to previous missions. The increased risk of exposure to dangerous radiation, such as Galactic Cosmic Rays and Solar Particle Events, is of great concern. Consequently, steps must be taken to ensure astronaut safety by providing adequate shielding. In order to better determine and verify shielding requirements, an accurate and efficient radiation transport code based on a fully three dimensional radiation transport model using the Green's function technique is being developed

  11. Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole

    SciTech Connect

    Sakalli, I.; Ovgun, A.

    2015-09-15

    We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton–Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.

  12. Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Ovgun, A.

    2015-09-01

    We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton-Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.

  13. Three-dimensional surface grid generation for calculation of thermal radiation shape factors

    NASA Technical Reports Server (NTRS)

    Aly, Hany M.

    1992-01-01

    A technique is described to generate three dimensional surface grids suitable for calculating shape factors for thermal radiative heat transfer. The surface under consideration is approximated by finite triangular elements generated in a special manner. The grid is generated by dividing the surface into a two dimensional array of nodes. Each node is defined by its coordinates. Each set of four adjacent nodes is used to construct two triangular elements. Each triangular element is characterized by the vector representation of its vertices. Vector algebra is used to calculate all desired geometric properties of grid elements. The properties are used to determine the shape factor between the element and an area element in space. The grid generation can be graphically displayed using any software with three dimensional features. DISSPLA was used to view the grids.

  14. Three-dimensional radiative transfer calculations on an SIMD machine applied to accretion disks

    NASA Astrophysics Data System (ADS)

    Vath, H.

    We have developed a tool to solve the radiative transfer equation for a three-dimensional astrophysical object on the SIMD computer MasPar MP-1. With this tool we can rapidly calculate the image of such an object as seen from an arbitrary direction and at an arbitrary wavelength. Such images and spectra can then be used to directly compare observations with the model. This tool can be applied to many different areas in astrophysics, e.g., HI disks of galaxies and polarized radiative transfer of accretion columns onto white dwarfs. Here we use this tool to calculate the image and spectrum of a simple model of an accretion disk.

  15. Three-dimensional radiative transfer using a Fourier-transform matrix-operator method

    NASA Technical Reports Server (NTRS)

    Martonchik, J. V.; Diner, D. J.

    1985-01-01

    The three-dimensional equation of transfer for a scattering medium with planar geometry is solved by using a spatial Fourier transform and extending matrix-operator techniques developed previously for the one-dimensional equation. Doubling and adding algorithms were derived by means of an interaction principle for computing the Fourier-transformed radiation field. The resulting expressions fully describe the radiative transfer process in a scattering medium, inhomogeneous in the x-, y- and z-directions, illuminated from above by an arbitrarily general intensity field and bounded from below by a surface with completely general reflection properties.

  16. Modelling canopy scale solar induced chlorophyll fluorescence simulated by the three dimensional radiative transfer model

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Nagai, S.; Inoue, T.; Yang, W.; Ichii, K.

    2014-12-01

    Recent studies show that the vegetation canopy scale sun-induced chlorophyll fluorescence (SIF) can be observed from satellite. To understand how the canopy scale bidirectional fluorescence observations are related to three-dimensional fluorescence distribution within a plant canopy, it is necessary to evaluate canopy scale fluorescence emission using a detailed plant canopy radiative transfer model. In this study, we developed a three-dimensional plant canopy radiative transfer model that can simulate the bidirectional chlorophyll fluorescence radiance and show several preliminary results of fluorescence distribution at the tree level. To simulate the three dimensional variations in chlorophyll fluorescence from trees, we measured tree structures using a terrestrial LiDAR instrument. The measurements were conducted in Yokohama, Japan (35°22'49" N 139°37'29" E). Three Japanese cherry trees (Cerasus Speciosa) were chosen for our study (Figure 1). Leaf-level sun-induced chlorophyll fluorescence (SIF) is also necessary as an input of radiative transfer model. To measure the leaf-level SIF, we used high spectral resolution spectroradiometer (HR 4000, Ocean Optics Inc. USA). The spectral resolution of this instrument is 0.05 nm (full width half maximum). The spectral range measured was 720 to 780 nm. From the spectral radiance measurements, we estimated SIF using the three band Fraunhofer Line Depth (3FLD) method. The effect of solar and view zenith angles, multiple scattering depends on many factors such as back ground reflectance, leaf reflectance transmittance and landscape structures. To understand how the SIF from both sparse and dense forest stands vary with sun and view angles and optical variables, it is necessary to conduct further sensitivity analysis. Radiative transfer simulation will help understand SIF emission at variety of forest canopy cases.

  17. On the Development of a Deterministic Three-Dimensional Radiation Transport Code

    NASA Technical Reports Server (NTRS)

    Rockell, Candice; Tweed, John

    2011-01-01

    Since astronauts on future deep space missions will be exposed to dangerous radiations, there is a need to accurately model the transport of radiation through shielding materials and to estimate the received radiation dose. In response to this need a three dimensional deterministic code for space radiation transport is now under development. The new code GRNTRN is based on a Green's function solution of the Boltzmann transport equation that is constructed in the form of a Neumann series. Analytical approximations will be obtained for the first three terms of the Neumann series and the remainder will be estimated by a non-perturbative technique . This work discusses progress made to date and exhibits some computations based on the first two Neumann series terms.

  18. Extending generalized Kubelka-Munk to three-dimensional radiative transfer.

    PubMed

    Sandoval, Christopher; Kim, Arnold D

    2015-08-10

    The generalized Kubelka-Munk (gKM) approximation is a linear transformation of the double spherical harmonics of order one (DP1) approximation of the radiative transfer equation. Here, we extend the gKM approximation to study problems in three-dimensional radiative transfer. In particular, we derive the gKM approximation for the problem of collimated beam propagation and scattering in a plane-parallel slab composed of a uniform absorbing and scattering medium. The result is an 8×8 system of partial differential equations that is much easier to solve than the radiative transfer equation. We compare the solutions of the gKM approximation with Monte Carlo simulations of the radiative transfer equation to identify the range of validity for this approximation. We find that the gKM approximation is accurate for isotropic scattering media that are sufficiently thick and much less accurate for anisotropic, forward-peaked scattering media. PMID:26368374

  19. Three-dimensional radiative flow with variable thermal conductivity and porous medium

    NASA Astrophysics Data System (ADS)

    Hayat, T.; Shehzad, S. A.; Alsaadi, F. E.; Alsaedi, A.

    2013-06-01

    This investigation deals with the three-dimensional boundary layer flow in a porous medium. The flow is induced by an exponentially stretching surface. Analysis is presented in the presence of heat transfer. Two cases, namely prescribed surface temperature (PST) and prescribed surface heat flux (PHF), are considered. Effects of thermal radiation are also present. The nonlinear partial differential equations are reduced into the ordinary differential equations. Series solutions are developed for the velocities and temperatures. Convergence of series solutions is checked via graphs and numerical values. Results are displayed and discussed for both PST and PHF cases.

  20. MHD three-dimensional flow of nanofluid with velocity slip and nonlinear thermal radiation

    NASA Astrophysics Data System (ADS)

    Hayat, Tasawar; Imtiaz, Maria; Alsaedi, Ahmed; Kutbi, Marwan A.

    2015-12-01

    An analysis has been carried out for the three dimensional flow of viscous nanofluid in the presence of partial slip and thermal radiation effects. The flow is induced by a permeable stretching surface. Water is treated as a base fluid and alumina as a nanoparticle. Fluid is electrically conducting in the presence of applied magnetic field. Entire different concept of nonlinear thermal radiation is utilized in the heat transfer process. Different from the previous literature, the nonlinear system for temperature distribution is solved and analyzed. Appropriate transformations reduce the nonlinear partial differential system to ordinary differential system. Convergent series solutions are computed for the velocity and temperature. Effects of different parameters on the velocity, temperature, skin friction coefficient and Nusselt number are computed and examined. It is concluded that heat transfer rate increases when temperature and radiation parameters are increased.

  1. Fast evaluation of Sommerfeld integrals for EM scattering and radiation by three-dimensional buried objects

    SciTech Connect

    Cui, T.J.; Chew, W.C.

    1999-03-01

    This paper presents a fast method for electromagnetic scattering and radiation problems pertinent to three-dimensional (3-D) buried objects. In this approach, a new symmetrical form of the Green`s function is derived, which can reduce the number of Sommerfeld integrals involved in the buried objects problem. The integration along steepest descent paths and leading-order approximations are introduced to evaluate these Sommerfeld integrals, which can greatly accelerate the computation. Based on the fast evaluation of Sommerfeld integrals, the radiation of an arbitrarily oriented electric dipole buried in a half space is first analyzed and computed. Then, the scattering by buried dielectric objects and conducting objects is considered using the method of moments (MOM). Numerical results show that the fast method can save tremendous CPU time in radiation and scattering problems involving buried objects.

  2. Evaluation of two radiative parameterizations using a three-dimensional large-eddy simulation microphysical model

    SciTech Connect

    Kogan, Y.L.; Kogan, Z.N.; Lilly, D.K.; Khairoutdinov, M.F.

    1995-04-01

    Stratocumulus clouds in the marine boundary layer exert a tremendous impact on the planetary radiation balance because of their persistence and large cover. Even small biases in the representation of their radiative parameters can produce large errors in the simulated planetary radiation balance. General circulation models (GCMs) and climate models most commonly use two parameterizations of cloud optical depth. The first employs as input parameters the climatological or in some other way averaged cloud droplet effective radius and liquid water path. The second concerns droplet concentration, mean droplet radius and cloud geometrical thickness. Both parameterizations are obtained from a general theoretical expression for cloud optical depth. This paper contrasts these two parameterizations with the general theoretical definition, using a set of cloud drop distribution functions generated by the CIMMS three-dimensional large-eddy simulation (LES) stratocumulus cloud microphysical model.

  3. The Coupling of Finite Element and Integral Equation Representations for Efficient Three-Dimensional Modeling of Electromagnetic Scattering and Radiation

    NASA Technical Reports Server (NTRS)

    Cwik, Tom; Zuffada, Cinzia; Jamnejad, Vahraz

    1996-01-01

    Finite element modeling has proven useful for accurtely simulating scattered or radiated fields from complex three-dimensional objects whose geometry varies on the scale of a fraction of a wavelength.

  4. Implementation of Localized Ensemble Assimilation for a Three-Dimensional Radiation Belt Model (Invited)

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Chen, Y.; Kellerman, A. C.; Subbotin, D.; Shprits, Y.

    2013-12-01

    Earth's outer radiation belt is very dynamic and energetic electrons therein undergo constant changes due to acceleration, loss, and trans- port processes. In this work we improve the accuracy of simulated electron phase space density (PSD) of the Versatile Electron Radiation Belt (VERB) code, a three-dimensional radiation belt model, by implementing the localized ensemble transform Kalman filter (LETKF) assimilation method. Assimilation methods based on Kalman filtering have been successfully applied to one-dimensional radial diffusion radiation belt models, where it has been shown to greatly improve the model estimation of electron phase space density (PSD). This work expands upon previous research by implementing the LETKF method to assimilate observed electron density into VERB, a three-dimensional radiation belt model. In particular, the LETKF will perform the assimilation locally, where the size of the local region is defined by the diffusion of electrons in the model. This will enable the optimal assimilation of data throughout the model consistently with the flow of electrons. Two sets of assimilation experiments are presented. The first is an identical-twin experiment, where artificial data is generated from the same model, with the purpose of verifying the assimilation method. In the second set of experiments, real PSD observational data from missions such as CRRES and/or the Van Allen Probes are assimilated into VERB. The results show that data assimilation significantly improves the accuracy of the VERB model by efficiently including the available observations at the appropriate pitch angles, energy levels, and L-shell regions throughout the model.

  5. Simulation of radiation effects on three-dimensional computer optical memories

    SciTech Connect

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle{close_quote}s track axis may be lost. The magnitude of the effect is dependent on the particle{close_quote}s track structure. {copyright} {ital 1997 American Institute of Physics.}

  6. High-resolution three-dimensional imaging of flat objects by synchrotron-radiation computed laminography

    NASA Astrophysics Data System (ADS)

    Helfen, L.; Baumbach, T.; Mikulík, P.; Kiel, D.; Pernot, P.; Cloetens, P.; Baruchel, J.

    2005-02-01

    Computed laminography with synchrotron radiation is developed and carried out for three-dimensional imaging of flat, laterally extended objects with high spatial resolution. Particular experimental conditions of a stationary synchrotron source have been taken into account by a scanning geometry different from that employed with movable conventional laboratory x-ray sources. Depending on the mechanical precision of the sample manipulation system, high spatial resolution down to the scale of 1μm can be attained nondestructively, even for objects of large lateral size. Furthermore, high beam intensity and the parallel-beam geometry enables easy use of monochromatic radiation for optimizing contrast and reducing imaging artifacts. Simulations and experiments on a test object demonstrate the feasibility of the method. Application to the inspection of solder joints in a flip-chip bonded device shows the potential for quality assurance of microsystem devices.

  7. Simulation of radiation effects on three-dimensional computer optical memories

    NASA Technical Reports Server (NTRS)

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.

  8. Three-dimensional Culture Conditions Lead to Decreased Radiation Induced Crytoxicity in Human Mammary Epithelial Cells

    SciTech Connect

    Sowa, Marianne B.; Chrisler, William B.; Zens, Kyra D.; Ashjian, Emily J.; Opresko, Lee K.

    2010-05-01

    For both targeted and non-targeted exposures, the cellular responses to ionizing radiation have predominantly been measured in two dimensional monolayer cultures. Although convenient for biochemical analysis, the true interactions in vivo depend upon complex interactions between cells themselves and the surrounding extra cellular matrix. This study directly compares the influence of culture conditions on radiation induced cytotoxicity following exposure to low-LET ionizing radiation. Using a three dimensional (3D) human mammary epithelial tissue model, we have found a protective effect of 3D cell culture on cell survival after irradiation. The initial state of the cells (i.e., 2D vs. 3D culture) at the time of irradiation does not alter survival, nor does the presence of extracellular matrix during and after exposure to dose, but long term culture in 3D which offers significant reduction in cytotoxicity at a given dose (e.g. ~4 fold increased survival at 5 Gy). The cell cycle delay induced following exposure to 2 and 5 Gy was almost identical between 2D and 3D culture conditions and cannot account for the observed differences in radiation responses. However the amount of apoptosis following radiation exposure is significantly decreased in 3D culture relative to the 2D monolayer after the same dose. A likely mechanism of the cytoprotective effect afforded by 3D culture conditions is the down regulation of radiation induced apoptosis in 3D structures

  9. A global three-dimensional radiation magneto-hydrodynamic simulation of super-eddington accretion disks

    SciTech Connect

    Jiang, Yan-Fei; Stone, James M.; Davis, Shane W.

    2014-12-01

    We study super-Eddington accretion flows onto black holes using a global three-dimensional radiation magneto-hydrodynamical simulation. We solve the time-dependent radiative transfer equation for the specific intensities to accurately calculate the angular distribution of the emitted radiation. Turbulence generated by the magneto-rotational instability provides self-consistent angular momentum transfer. The simulation reaches inflow equilibrium with an accretion rate ∼220 L {sub Edd}/c {sup 2} and forms a radiation-driven outflow along the rotation axis. The mechanical energy flux carried by the outflow is ∼20% of the radiative energy flux. The total mass flux lost in the outflow is about 29% of the net accretion rate. The radiative luminosity of this flow is ∼10 L {sub Edd}. This yields a radiative efficiency ∼4.5%, which is comparable to the value in a standard thin disk model. In our simulation, vertical advection of radiation caused by magnetic buoyancy transports energy faster than photon diffusion, allowing a significant fraction of the photons to escape from the surface of the disk before being advected into the black hole. We contrast our results with the lower radiative efficiencies inferred in most models, such as the slim disk model, which neglect vertical advection. Our inferred radiative efficiencies also exceed published results from previous global numerical simulations, which did not attribute a significant role to vertical advection. We briefly discuss the implications for the growth of supermassive black holes in the early universe and describe how these results provided a basis for explaining the spectrum and population statistics of ultraluminous X-ray sources.

  10. Optimization of MAGIC gel formulation for three-dimensional radiation therapy dosimetry.

    PubMed

    Luci, J J; Whitney, H M; Gore, J C

    2007-05-21

    Polymer gel dosimetry aims to provide three-dimensional images of radiation therapy dose distributions in irradiated aqueous gels. The first gels required manufacture in an oxygen-free environment, but later the MAGIC formulation was introduced, which could be made in normal atmospheric conditions. Here we report our studies of the effects of variations in the composition of the MAGIC gel performed in order to optimize its performance over the useful dose range of 0 to 20 Gy. A new formulation (termed 'MAGIC-2') is comprised of 87% water, 4% methacrylic acid, 9% gelatin, 17.38 x 10(-6) M Cu(2+) and a molar ratio of ascorbic acid to [Cu(2+)] of 1000:1. MAGIC-2 has a dose-response slope-to-intercept ratio that is 78% greater than the original formulation and other more favorable properties. PMID:17473340

  11. Scattering and radiation analysis of three-dimensional cavity arrays via a hybrid finite element method

    NASA Technical Reports Server (NTRS)

    Jin, Jian-Ming; Volakis, John L.

    1992-01-01

    A hybrid numerical technique is presented for a characterization of the scattering and radiation properties of three-dimensional cavity arrays recessed in a ground plane. The technique combines the finite element and boundary integral methods and invokes Floquet's representation to formulate a system of equations for the fields at the apertures and those inside the cavities. The system is solved via the conjugate gradient method in conjunction with the Fast Fourier Transform (FFT) thus achieving an O(N) storage requirement. By virtue of the finite element method, the proposed technique is applicable to periodic arrays comprised of cavities having arbitrary shape and filled with inhomogeneous dielectrics. Several numerical results are presented, along with new measured data, which demonstrate the validity, efficiency, and capability of the technique.

  12. Three-dimensional aspects of radiative transfer in remote sensing of precipitation: Application to the 1986 COHMEX storm

    NASA Technical Reports Server (NTRS)

    Haferman, J. L.; Krajewski, W. F.; Smith, T. F.

    1994-01-01

    Several multifrequency techniques for passive microwave estimation of precipitation based on the absorption and scattering properties of hydrometers have been proposed in the literature. In the present study, plane-parallel limitations are overcome by using a model based on the discrete-ordinates method to solve the radiative transfer equation in three-dimensional rectangular domains. This effectively accounts for the complexity and variety of radiation problems encountered in the atmosphere. This investigation presents result for plane-parallel and three-dimensional radiative transfer for a precipitating system, discusses differences between these results, and suggests possible explanations for these differences. Microphysical properties were obtained from the Colorado State University Regional Atmospehric Modeling System and represent a hailstorm observed during the 1986 Cooperative Huntsville Meteorological Experiment. These properties are used as input to a three-dimensional radiative transfer model in order to simulate satellite observation of the storm. The model output consists of upwelling brightness temperatures at several of the frequencies on the Special Sensor Microwave/Imager. The radiative transfer model accounts for scattering and emission of atmospheric gases and hydrometers in liquid and ice phases. Brightness temperatures obtained from the three-dimensional model of this investigation indicate that horizontal inhomogeneities give rise to brightness temperature fields that can be quite different from fields obtained using plane-parallel radiative transfer theory. These differences are examined for various resolutions of the satellite sensor field of view. In adddition, the issue of boundary conditions for three-dimensional atmospheric radiative transfer is addressed.

  13. Observations of Three-Dimensional Radiative Effects that Influence Satellite Retrievals of Cloud Properties

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander; Lau, William K. M. (Technical Monitor)

    2001-01-01

    This paper examines three-dimensional (3D) radiative effects, which arise from horizontal radiative interactions between areas that have different cloud properties. Earlier studies have argued that these effects can cause significant uncertainties in current satellite retrievals of cloud properties, because the retrievals rely on one-dimensional (1D) theory and do not consider the effects of horizontal changes in cloud properties. This study addresses two questions: which retrieved cloud properties are influenced by 3D radiative effects, and where 3D effects tend to occur? The influence of 3D effects is detected from the wayside illumination and shadowing make clouds appear asymmetric: Areas appear brighter if the cloud top surface is tilted toward, rather than away from, the Sun. The analysis of 30 images by the Moderate Resolution Imaging Spectroradiometer (MODIS) reveals that retrievals of cloud optical thickness and cloud water content are most influenced by 3D effects, whereas retrievals of cloud particle size are much less affected. The results also indicate that while 3D effects are strongest at cloud edges, cloud top variability in cloud interiors, even in overcast regions, also produces considerable 3D effects. Finally, significant 3D effects are found in a wide variety of situations, ranging from thin clouds to thick ones and from low clouds to high ones.

  14. Three-Dimensional Mixed Convection Flow of Viscoelastic Fluid with Thermal Radiation and Convective Conditions

    PubMed Central

    Hayat, Tasawar; Ashraf, Muhammad Bilal; Alsulami, Hamed H.; Alhuthali, Muhammad Shahab

    2014-01-01

    The objective of present research is to examine the thermal radiation effect in three-dimensional mixed convection flow of viscoelastic fluid. The boundary layer analysis has been discussed for flow by an exponentially stretching surface with convective conditions. The resulting partial differential equations are reduced into a system of nonlinear ordinary differential equations using appropriate transformations. The series solutions are developed through a modern technique known as the homotopy analysis method. The convergent expressions of velocity components and temperature are derived. The solutions obtained are dependent on seven sundry parameters including the viscoelastic parameter, mixed convection parameter, ratio parameter, temperature exponent, Prandtl number, Biot number and radiation parameter. A systematic study is performed to analyze the impacts of these influential parameters on the velocity and temperature, the skin friction coefficients and the local Nusselt number. It is observed that mixed convection parameter in momentum and thermal boundary layers has opposite role. Thermal boundary layer is found to decrease when ratio parameter, Prandtl number and temperature exponent are increased. Local Nusselt number is increasing function of viscoelastic parameter and Biot number. Radiation parameter on the Nusselt number has opposite effects when compared with viscoelastic parameter. PMID:24608594

  15. Three-dimensional mixed convection flow of viscoelastic fluid with thermal radiation and convective conditions.

    PubMed

    Hayat, Tasawar; Ashraf, Muhammad Bilal; Alsulami, Hamed H; Alhuthali, Muhammad Shahab

    2014-01-01

    The objective of present research is to examine the thermal radiation effect in three-dimensional mixed convection flow of viscoelastic fluid. The boundary layer analysis has been discussed for flow by an exponentially stretching surface with convective conditions. The resulting partial differential equations are reduced into a system of nonlinear ordinary differential equations using appropriate transformations. The series solutions are developed through a modern technique known as the homotopy analysis method. The convergent expressions of velocity components and temperature are derived. The solutions obtained are dependent on seven sundry parameters including the viscoelastic parameter, mixed convection parameter, ratio parameter, temperature exponent, Prandtl number, Biot number and radiation parameter. A systematic study is performed to analyze the impacts of these influential parameters on the velocity and temperature, the skin friction coefficients and the local Nusselt number. It is observed that mixed convection parameter in momentum and thermal boundary layers has opposite role. Thermal boundary layer is found to decrease when ratio parameter, Prandtl number and temperature exponent are increased. Local Nusselt number is increasing function of viscoelastic parameter and Biot number. Radiation parameter on the Nusselt number has opposite effects when compared with viscoelastic parameter. PMID:24608594

  16. Evaluating a three dimensional model of diffuse photosynthetically active radiation in maize canopies

    NASA Astrophysics Data System (ADS)

    Wang, Xiping; Guo, Yan; Li, Baoguo; Wang, Xiyong; Ma, Yuntao

    2006-07-01

    Diffuse photosynthetically active radiation (DPAR) is important during overcast days and for plant parts shaded from the direct beam radiation. Simulation of DPAR interception by individual plant parts of a canopy, separately from direct beam photosynthetically active radiation (PAR), may give important insights into plant ecology. This paper presents a model to simulate the interception of DPAR in plant canopies. A sub-model of a virtual maize canopy was reconstructed. Plant surfaces were represented as small triangular facets positioned according to three-dimensionally (3D) digitized data collected in the field. Then a second sub-model to simulate the 3D DPAR distribution in the canopy was developed by dividing the sky hemisphere into a grid of fine cells that allowed for the anisotropic distribution of DPAR over the sky hemisphere. This model, DSHP (Dividing Sky Hemisphere with Projecting), simulates which DSH (Divided Sky Hemisphere) cells are directly visible from a facet in the virtual canopy, i.e. not obscured by other facets. The DPAR reaching the center of a facet was calculated by summing the amounts of DPAR present in every DSH cell. The distribution of DPAR in a canopy was obtained from the calculated DPARs intercepted by all facets in the canopy. This DSHP model was validated against DPAR measurements made in an actual maize ( Zea mays L.) canopy over selected days during the early filling stage. The simulated and measured DPAR at different canopy depths showed a good agreement with a R 2 equaling 0.78 ( n=120).

  17. Dispersion engineering of metasurfaces for dual-frequency quasi-three-dimensional cloaking of microwave radiators.

    PubMed

    Jiang, Zhi Hao; Werner, Douglas H

    2016-05-01

    In this work, the design methodology and experimental investigation of compact and lightweight dispersive coatings, comprised by multiple layers of anisotropic metasurfaces, which are capable of cloaking radiators at multiple frequencies are presented. To determine the required surface electromagnetic properties for each layer, an analytical model is developed for predicting the scattering from a cylinder surrounded by multiple layers of anisotropic metasurfaces subject to plane-wave illumination at a general oblique incidence angle. Particularly, two different metasurface coating solutions with different dispersive properties are designed to provide more than 10 dB scattering width suppression at two pre-selected frequencies within a field-of-view (FOV) of ± 20° off normal incidence. Both coating designs implemented using metasurfaces are fabricated and measured, experimentally demonstrating the simultaneous suppression of mutual coupling and quasi-three-dimensional radiation blockage at the two pre-selected frequency ranges. At the same time, the functionality of the coated monopole is still well-maintained. The performance comparison further sheds light on how the optimal performance can be obtained by properly exploiting the dispersion of each metasurface layer of the coating. In addition, the cloaking effect is retained even when the distance between the radiators is significantly reduced. The concept and general design methodology presented here can be extended for applications that would benefit from cloaking multi-spectral terahertz as well as optical antennas. PMID:27137576

  18. Feasibility and efficacy of high-dose three-dimensional-conformal radiotherapy in cirrhotic patients with small-size hepatocellular carcinoma non-eligible for curative therapies-mature results of the French Phase II RTF-1 trial

    SciTech Connect

    Mornex, Francoise . E-mail: francoise.mornex@chu-lyon.fr; Girard, Nicolas; Beziat, Christophe; Kubas, Abdul; Khodri, Mustapha; Trepo, Christian; Merle, Philippe

    2006-11-15

    Purpose: Hepatocellular carcinoma (HCC) is a poor prognosis tumor, and only 20% of patients will benefit from curative therapies (surgery, liver transplantation, percutaneous ablation). Although conventional radiotherapy has been traditionally regarded as inefficient and toxic for cirrhotic patients, three-dimensional conformal radiotherapy (3DCRT) has provided promising preliminary data for the treatment of HCC. Methods and Materials: Prospective phase II trial including Child-Pugh A/B cirrhotic patients with small-size HCC (1 nodule {<=}5 cm, or 2 nodules {<=}3 cm) nonsuitable for curative treatments, to assess tolerance and efficacy of high-dose (66 Gy, 2 Gy/fraction) 3DCRT. Results: Twenty-seven patients were enrolled. Among the 25 assessable patients, tumor response was observed for 23 patients (92%), with complete response for 20 patients (80%), and partial response for 3 patients (12%). Stable disease was observed in 2 patients (8%). Grade 4 toxicities occurred in 2 of 11 (22%) Child-Pugh B patients only. Child-Pugh A patients tolerated treatment well, and 3/16 (19%) developed asymptomatic Grade 3 toxicities. Conclusion: High-dose 3DCRT is a noninvasive, well-tolerated modality that is highly suitable for the treatment of small HCCs in cirrhotic patients, with promising results. However, additional trials are needed to optimize this technique and formally compare it with the usual curative approaches.

  19. Implementation of Ensemble Data Assimilation for a Three-Dimensional Radiation Belt Model

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Chen, Y.; Shprits, Y.; Kellerman, A. C.; Subbotin, D.

    2013-05-01

    Earth's outer radiation belt is very dynamic and undergoes constant changes due to acceleration, loss, and transport processes of the energetic electrons. In this work the ensemble Kalman filter (EnKF) assimilation method is applied to the Versatile Electron Radiation Belt (VERB) code, a three-dimensional radiation belt model developed at the University of California Los Angeles. The VERB model includes radial, pitch angle, and energy diffusion caused by low-latitude and high-latitude chorus, plasma- spheric hiss, and electromagnetic ion cyclotron (EMIC) waves. Assimi- lation methods based on Kalman filtering have been successfully applied to one-dimensional radial diffusion radiation belt models, where it has been shown that assimilating real observational data into the radiation belt models greatly improves the accuracy of electron PSD estimation. In our work we implement the EnKF for assimilation of real electron PSD data into the VERB model. In particular the assimilation is performed locally along the direction of the dominant diffusion of electrons in the model. This will enable the correct assimilation of data to be consistent with the flow of electrons throughout the model. Two set of assimila- tion experiments are presented. The first is an identical-twin experiment, where artificial data is generated from the same model, with the purpose of validating the assimilation method. In the second set of experiments, real PSD observational data from CRRES are assimilated into VERB in order to improve the model estimation of the electron PSD distribution. The results show that data assimilation significantly improves the accu- racy of the VERB model by efficiently including observations to correct the model PSD estimation.

  20. PAKAL: A THREE-DIMENSIONAL MODEL TO SOLVE THE RADIATIVE TRANSFER EQUATION

    SciTech Connect

    De la Luz, Victor; Lara, Alejandro; Mendoza-Torres, J. E.; Selhorst, Caius L.

    2010-06-15

    We present a new numerical model called 'Pakal' intended to solve the radiative transfer equation in a three-dimensional (3D) geometry, using the approximation for a locally plane-parallel atmosphere. Pakal uses pre-calculated radial profiles of density and temperature (based on hydrostatic, hydrodynamic, or MHD models) to compute the emission from 3D source structures with high spatial resolution. Then, Pakal solves the radiative transfer equation in a set of (3D) ray paths, going from the source to the observer. Pakal uses a new algorithm to compute the radiative transfer equation by using an intelligent system consisting of three structures: a cellular automaton; an expert system; and a program coordinator. The code outputs can be either two-dimensional maps or one-dimensional profiles, which reproduce the observations with high accuracy, giving detailed physical information about the environment where the radiation was generated and/or transmitted. We present the model applied to a 3D solar radial geometry, assuming a locally plane-parallel atmosphere, and thermal free-free radio emission from hydrogen-helium gas in thermodynamic equilibrium. We also present the convergence test of the code. We computed the synthetic spectrum of the centimetric-millimetric solar emission and found better agreement with observations (up to 10{sup 4} K at 20 GHz) than previous models reported in the literature. The stability and convergence test show the high accuracy of the code. Finally, Pakal can improve the integration time by up to an order of magnitude compared against linear integration codes.

  1. Apparatus and method for high dose rate brachytherapy radiation treatment

    DOEpatents

    Macey, Daniel J.; Majewski, Stanislaw; Weisenberger, Andrew G.; Smith, Mark Frederick; Kross, Brian James

    2005-01-25

    A method and apparatus for the in vivo location and tracking of a radioactive seed source during and after brachytherapy treatment. The method comprises obtaining multiple views of the seed source in a living organism using: 1) a single PSPMT detector that is exposed through a multiplicity of pinholes thereby obtaining a plurality of images from a single angle; 2) a single PSPMT detector that may obtain an image through a single pinhole or a plurality of pinholes from a plurality of angles through movement of the detector; or 3) a plurality of PSPMT detectors that obtain a plurality of views from different angles simultaneously or virtually simultaneously. The plurality of images obtained from these various techniques, through angular displacement of the various acquired images, provide the information required to generate the three dimensional images needed to define the location of the radioactive seed source within the body of the living organism.

  2. Target volume definition for three-dimensional conformal radiation therapy of lung cancer.

    PubMed

    Armstrong, J G

    1998-06-01

    Three-dimensional conformal radiation therapy (3DCRT) is a mode of high precision radiotherapy which has the potential to improve the therapeutic ratio of radiation therapy for locally advanced non-small cell lung cancer. The preliminary clinical experience with 3DCRT has been promising and justifies further endeavour to refine its clinical application and ultimately test its role in randomized trials. There are several steps to be taken before 3DCRT evolves into an effective single modality for the treatment of lung cancer and before it is effectively integrated with chemotherapy. This article addresses core issues in the process of target volume definition for the application of 3DCRT technology to lung cancer. The International Commission on Radiation Units and Measurements Report no. 50 definitions of target volumes are used to identify the factors influencing target volumes in lung cancer. The rationale for applying 3DCRT to lung cancer is based on the frequency of failure to eradicate gross tumour with conventional approaches. It may therefore be appropriate to ignore subclinical or microscopic extensions when designing a clinical target volume, thereby restricting target volume size and allowing dose escalation. When the clinical target volume is expanded to a planning target volume, an optimized margin would result in homogeneous irradiation to the highest dose feasible within normal tissue constraints. To arrive at such optimized margins, multiple factors, including data acquisition, data transfer, patient movement, treatment reproducibility, and internal organ and target volume motion, must be considered. These factors may vary significantly depending on technology and techniques, and published quantitative analyses are no substitute for meticulous attention to detail and audit of performance. PMID:9849380

  3. Three-dimensional Čerenkov tomography of energy deposition from ionizing radiation beams

    PubMed Central

    Glaser, Adam K.; Voigt, William H.A.; Davis, Scott C.; Zhang, Rongxiao; Gladstone, David J.; Pogue, Brian W.

    2013-01-01

    Since its discovery during the 1930’s, the Čerenkov effect (light emission from charged particles traveling faster than the local speed of light in a dielectric medium) has been paramount in the development of high-energy physics research. The ability of the emitted light to describe a charged particle’s trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, all applications of the process to date have focused on identification of particle’s themselves, rather than their effect upon the surroundings through which they travel. Here, we explore a novel application of the Čerenkov effect for the recovery of the spatial distribution of ionizing radiation energy deposition in a medium, and apply it to the issue of dose determination in medical physics. By capturing multiple projection images of the Čerenkov light induced by a medical linear accelerator (LINAC) x-ray photon beam, we demonstrate the successful three-dimensional (3D) tomographic reconstruction of the imparted dose distribution for the first time. PMID:23455248

  4. Three-dimensional Čerenkov tomography of energy deposition from ionizing radiation beams.

    PubMed

    Glaser, Adam K; Voigt, William H A; Davis, Scott C; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

    2013-03-01

    Since its discovery during the 1930s the Čerenkov effect (light emission from charged particles traveling faster than the local speed of light in a dielectric medium) has been paramount in the development of high-energy physics research. The ability of the emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, to our knowledge, all applications of the process to date have focused on the identification of particles themselves, rather than their effect upon the surroundings through which they travel. Here we explore a novel application of the Čerenkov effect for the recovery of the spatial distribution of ionizing radiation energy deposition in a medium and apply it to the issue of dose determination in medical physics. By capturing multiple projection images of the Čerenkov light induced by a medical linear accelerator x-ray photon beam, we demonstrate the successful three-dimensional tomographic reconstruction of the imparted dose distribution. PMID:23455248

  5. Monte Carlo Three-dimensional Radiative Transfer Modelling of Off Axis Situations

    NASA Astrophysics Data System (ADS)

    Friedeburg, C. V.; Morgner, A.; Wagner, T.; Wenig, M.; Platt, U.

    Off-Axis DOAS measurements with non-artificial scattered light, based upon the renowned DOAS technique, allow to optimize the sensitivity of the technique for the trace gas profile in question by strongly increasing the light's path through the relevant atmosphere layers. Multi-Axis-(MAX) DOAS probe several directions simultaneously or sequentially to increase the spatial resolution. Several devices (ground based, air- borne and ship-built) are operated by our group in the framework of the SCIAMACHY validation. Radiative transfer models are an essential requirement for the interpretation of these measurements and their conversion into detailed profile data. Apart from some existing Monte Carlo Models most codes use analytical algorithms to solve the radia- tive transfer equation for given atmospheric conditions. For specific circumstances, e.g. photon scattering within clouds, these approaches are not efficient enough to pro- vide sufficient accuracy. Also horizontal gradients in atmospheric parameters have to be taken into account. To meet the needs of measurement situations for all kinds of scattered light DOAS platforms, a three dimensional full spherical Monte Carlo model was devised. Here we present Air Mass Factors (AMF) to calculate vertical column densities (VCD) from measured slant column densities (SCD). Sensitivity studies on the influence of the wavelength and telescope direction used, of the altitude of profile layers, albedo, refraction and basic aerosols are shown. Also modelled intensity series are compared with radiometer data.

  6. A High Spatial Resolution Three Dimensional Version of the SASKTRAN Radiative Transfer Model

    NASA Astrophysics Data System (ADS)

    Zawada, D.; Dueck, S.; Lloyd, N. D.; Bourassa, A. E.; Degenstein, D. A.

    2013-12-01

    For the past decade the SASKTRAN radiative transfer model has been used, along with OSIRIS measurements of spectrally dispersed limb scattered sunlight, to retrieve vertical profiles of atmospheric constituents such as ozone, nitrogen dioxide and stratospheric aerosol. SASKTRAN is a spherical geometry, multiple scatter model that uses a successive orders approach. Until recently SASKTRAN has relied on horizontal homogeneity of the atmospheric constituents for its simulations. This paper details recent advances to the SASKTRAN model that now allow it to accurately and quickly calculate the diffuse radiance field in the presence of two and three dimensional structure within the atmospheric state. Included is a description of the modifications along with an analysis of the similarities and differences between the original model and the new version in the presence of structures that are found near realistic ozone hole conditions. These results demonstrate the utility of the SASKTRAN model for use in the retrievals associated with the Canadian Atmospheric Tomography System (CATS), an OSIRIS follow-on instrument, that is currently funded under the auspices of the Canadian Space Agency.

  7. Radiative Effect of Clouds on Tropospheric Chemistry in a Global Three-Dimensional Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Pierce, Robert B.; Norris, Peter; Platnick, Steven E.; Chen, Gao; Logan, Jennifer A.; Yantosca, Robert M.; Evans, Mat J.; Kittaka, Chieko; Feng, Yan; Tie, Xuexi

    2006-01-01

    Clouds exert an important influence on tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies (J-values). We assess the radiative effect of clouds on photolysis frequencies and key oxidants in the troposphere with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations from the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA Global Modeling and Assimilation Office (GMAO). We focus on the year of 2001 with the GEOS-3 meteorological observations. Photolysis frequencies are calculated using the Fast-J radiative transfer algorithm. The GEOS-3 global cloud optical depth and cloud fraction are evaluated and generally consistent with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). Results using the linear assumption, which assumes linear scaling of cloud optical depth with cloud fraction in a grid box, show global mean OH concentrations generally increase by less than 6% because of the radiative effect of clouds. The OH distribution shows much larger changes (with maximum decrease of approx.20% near the surface), reflecting the opposite effects of enhanced (weakened) photochemistry above (below) clouds. The global mean photolysis frequencies for J[O1D] and J[NO2] in the troposphere change by less than 5% because of clouds; global mean O3 concentrations in the troposphere increase by less than 5%. This study shows tropical upper tropospheric O3 to be less sensitive to the radiative effect of clouds than previously reported (approx.5% versus approx.20-30%). These results emphasize that the dominant effect of clouds is to influence the vertical redistribution of the intensity of photochemical activity while global average effects remain modest, again contrasting with previous studies. Differing vertical distributions

  8. Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages.

    PubMed

    Carlton, Holly D; Elmer, John W; Li, Yan; Pacheco, Mario; Goyal, Deepak; Parkinson, Dilworth Y; MacDowell, Alastair A

    2016-01-01

    Synchrotron radiation micro-tomography (SRµT) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm(2), but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample's properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 µm all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials. PMID:27167469

  9. Cell Type-dependent Gene Transcription Profile in Three Dimensional Human Skin Tissue Model Exposed to Low Doses of Ionizing Radiation: Implications for Medical Exposures

    SciTech Connect

    Freiin von Neubeck, Claere H.; Shankaran, Harish; Karin, Norman J.; Kauer, Paula M.; Chrisler, William B.; Wang, Xihai; Robinson, Robert J.; Waters, Katrina M.; Tilton, Susan C.; Sowa, Marianne B.

    2012-04-17

    The concern over possible health risks from exposures to low doses of ionizing radiation has been driven largely by the increase in medical exposures, the routine implementation of X-ray backscatter devices for airport security screening, and, most recently, the nuclear incident in Japan. Due to a paucity of direct epidemiological data at very low doses, cancer risk must be estimated from high dose exposure scenarios. However, there is increasing evidence that low and high dose exposures result in different signaling events and may have different mechanisms of cancer induction. We have examined the radiation induced temporal response of an in vitro three dimensional (3D) human skin tissue model using microarray-based transcriptional profiling. Our data shows that exposure to 100 mGy of X-rays is sufficient to affect gene transcription. Cell type specific analysis showed significant changes in gene expression with the levels of > 1400 genes altered in the dermis and > 400 genes regulated in the epidermis. The two cell types rarely exhibited overlapping responses at the mRNA level. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) measurements validated the microarray data in both regulation direction and value. Key pathways identified relate to cell cycle regulation, immune responses, hypoxia, reactive oxygen signaling, and DNA damage repair. We discuss in particular the role of proliferation and emphasizing how the disregulation of cellular signaling in normal tissue may impact progression towards radiation induced secondary diseases.

  10. INVESTIGATING THE RELIABILITY OF CORONAL EMISSION MEASURE DISTRIBUTION DIAGNOSTICS USING THREE-DIMENSIONAL RADIATIVE MAGNETOHYDRODYNAMIC SIMULATIONS

    SciTech Connect

    Testa, Paola; De Pontieu, Bart; Martinez-Sykora, Juan; Hansteen, Viggo; Carlsson, Mats

    2012-10-10

    Determining the temperature distribution of coronal plasmas can provide stringent constraints on coronal heating. Current observations with the Extreme ultraviolet Imaging Spectrograph (EIS) on board Hinode and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory provide diagnostics of the emission measure distribution (EMD) of the coronal plasma. Here we test the reliability of temperature diagnostics using three-dimensional radiative MHD simulations. We produce synthetic observables from the models and apply the Monte Carlo Markov chain EMD diagnostic. By comparing the derived EMDs with the 'true' distributions from the model, we assess the limitations of the diagnostics as a function of the plasma parameters and the signal-to-noise ratio of the data. We find that EMDs derived from EIS synthetic data reproduce some general characteristics of the true distributions, but usually show differences from the true EMDs that are much larger than the estimated uncertainties suggest, especially when structures with significantly different density overlap along the line of sight. When using AIA synthetic data the derived EMDs reproduce the true EMDs much less accurately, especially for broad EMDs. The differences between the two instruments are due to the: (1) smaller number of constraints provided by AIA data and (2) broad temperature response function of the AIA channels which provide looser constraints to the temperature distribution. Our results suggest that EMDs derived from current observatories may often show significant discrepancies from the true EMDs, rendering their interpretation fraught with uncertainty. These inherent limitations to the method should be carefully considered when using these distributions to constrain coronal heating.

  11. Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanning

    NASA Astrophysics Data System (ADS)

    Babic, Steven; McNiven, Andrea; Battista, Jerry; Jordan, Kevin

    2009-04-01

    The dosimetry of small fields as used in stereotactic radiotherapy, radiosurgery and intensity-modulated radiation therapy can be challenging and inaccurate due to partial volume averaging effects and possible disruption of charged particle equilibrium. Consequently, there exists a need for an integrating, tissue equivalent dosimeter with high spatial resolution to avoid perturbing the radiation beam and artificially broadening the measured beam penumbra. In this work, radiochromic ferrous xylenol-orange (FX) and leuco crystal violet (LCV) micelle gels were used to measure relative dose factors (RDFs), percent depth dose profiles and relative lateral beam profiles of 6 MV x-ray pencil beams of diameter 28.1, 9.8 and 4.9 mm. The pencil beams were produced via stereotactic collimators mounted on a Varian 2100 EX linear accelerator. The gels were read using optical computed tomography (CT). Data sets were compared quantitatively with dosimetric measurements made with radiographic (Kodak EDR2) and radiochromic (GAFChromic® EBT) film, respectively. Using a fast cone-beam optical CT scanner (Vista™), corrections for diffusion in the FX gel data yielded RDFs that were comparable to those obtained by minimally diffusing LCV gels. Considering EBT film-measured RDF data as reference, cone-beam CT-scanned LCV gel data, corrected for scattered stray light, were found to be in agreement within 0.5% and -0.6% for the 9.8 and 4.9 mm diameter fields, respectively. The validity of the scattered stray light correction was confirmed by general agreement with RDF data obtained from the same LCV gel read out with a laser CT scanner that is less prone to the acceptance of scattered stray light. Percent depth dose profiles and lateral beam profiles were found to agree within experimental error for the FX gel (corrected for diffusion), LCV gel (corrected for scattered stray light), and EBT and EDR2 films. The results from this study reveal that a three-dimensional dosimetry method

  12. Laser-processed three dimensional graphitic electrodes for diamond radiation detectors

    NASA Astrophysics Data System (ADS)

    Caylar, Benoît; Pomorski, Michal; Bergonzo, Philippe

    2013-07-01

    We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using α-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.

  13. Laser-processed three dimensional graphitic electrodes for diamond radiation detectors

    SciTech Connect

    Caylar, Benoı-carett; Pomorski, Michal; Bergonzo, Philippe

    2013-07-22

    We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using α-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.

  14. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT)

    SciTech Connect

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    2013-12-15

    Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.

  15. Statistics Analysis of the Uncertainties in Cloud Optical Depth Retrievals Caused by Three-Dimensional Radiative Effects

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2000-01-01

    This paper presents a simple approach to estimate the uncertainties that arise in satellite retrievals of cloud optical depth when the retrievals use one-dimensional radiative transfer theory for heterogeneous clouds that have variations in all three dimensions. For the first time, preliminary error bounds are set to estimate the uncertainty of cloud optical depth retrievals. These estimates can help us better understand the nature of uncertainties that three-dimensional effects can introduce into retrievals of this important product of the MODIS instrument. The probability distribution of resulting retrieval errors is examined through theoretical simulations of shortwave cloud reflection for a wide variety of cloud fields. The results are used to illustrate how retrieval uncertainties change with observable and known parameters, such as solar elevation or cloud brightness. Furthermore, the results indicate that a tendency observed in an earlier study, clouds appearing thicker for oblique sun, is indeed caused by three-dimensional radiative effects.

  16. Nanotube-based three-dimensional albumin composite obtained using continuous laser radiation

    SciTech Connect

    Ageeva, S. A.; Bobrinetskii, I. I.; Nevolin, V. K. Podgaetskii, V. M.; Selishchev, S. V.; Simunin, M. M.; Konov, V. I.; Savranskii, V. V.

    2009-12-15

    The possibility of developing three-dimensional nanostructures for damaged bone and tissue restoration, including treatment of human congenital malformation is considered. Four types of multiwalled and single-walled carbon nanotubes fabricated by chemical vapor deposition via disproportionation on Fe clusters and thermal cathode sputtering in an inert gas were studied. The nanomaterial's topography was studied by atomic-force microscopy. The possibility of using 3D nanocomposites as a biosolder for laser biowelding of cartilaginous tissue was shown. The compatibility of biological tissues with a nanocomposite material in vivo introduced under the perichondrium of ear cartilage of a rabbit was validated.

  17. Long-Term Outcomes After High-Dose Postprostatectomy Salvage Radiation Treatment

    SciTech Connect

    Goenka, Anuj; Magsanoc, Juan Martin; Pei Xin; Schechter, Michael; Kollmeier, Marisa; Cox, Brett; Scardino, Peter T.; Eastham, James A.; Zelefsky, Michael J.

    2012-09-01

    Purpose: To review the impact of high-dose radiotherapy (RT) in the postprostatectomy salvage setting on long-term biochemical control and distant metastases-free survival, and to identify clinical and pathologic predictors of outcomes. Methods and Materials: During 1988-2007, 285 consecutive patients were treated with salvage RT (SRT) after radical prostatectomy. All patients were treated with either three-dimensional conformal RT or intensity-modulated RT. Two hundred seventy patients (95%) were treated to a dose {>=}66 Gy, of whom 205 (72%) received doses {>=}70 Gy. Eighty-seven patients (31%) received androgen-deprivation therapy as a component of their salvage treatment. All clinical and pathologic records were reviewed to identify treatment risk factors and response. Results: The median follow-up time after SRT was 60 months. Seven-year actuarial prostate-specific antigen (PSA) relapse-free survival and distant metastases-free survival were 37% and 77%, respectively. Independent predictors of biochemical recurrence were vascular invasion (p < 0.01), negative surgical margins (p < 0.01), presalvage PSA level >0.4 ng/mL (p < 0.01), androgen-deprivation therapy (p = 0.03), Gleason score {>=}7 (p = 0.02), and seminal vesicle involvement (p = 0.05). Salvage RT dose {>=}70 Gy was not associated with improvement in biochemical control. A doubling time <3 months was the only independent predictor of metastatic disease (p < 0.01). There was a trend suggesting benefit of SRT dose {>=}70 Gy in preventing clinical local failure in patients with radiographically visible local disease at time of SRT (7 years: 90% vs. 79.1%, p = 0.07). Conclusion: Salvage RT provides effective long-term biochemical control and freedom from metastasis in selected patients presenting with detectable PSA after prostatectomy. Androgen-deprivation therapy was associated with improvement in biochemical progression-free survival. Clinical local failures were rare but occurred most commonly in

  18. A finite element-boundary integral method for scattering and radiation by two- and three-dimensional structures

    NASA Technical Reports Server (NTRS)

    Jin, Jian-Ming; Volakis, John L.; Collins, Jeffery D.

    1991-01-01

    A review of a hybrid finite element-boundary integral formulation for scattering and radiation by two- and three-dimensional composite structures is presented. In contrast to other hybrid techniques involving the finite element method, the proposed one is in principle exact and can be implemented using a low O(N) storage. This is of particular importance for large scale applications and is a characteristic of the boundary chosen to terminate the finite element mesh, usually as close to the structure as possible. A certain class of these boundaries lead to convolutional boundary integrals which can be evaluated via the fast Fourier transform (FFT) without a need to generate a matrix; thus, retaining the O(N) storage requirement. The paper begins with a general description of the method. A number of two- and three-dimensional applications are then given, including numerical computations which demonstrate the method's accuracy, efficiency, and capability.

  19. Gene expression profiling in undifferentiated thyroid carcinoma induced by high-dose radiation.

    PubMed

    Bang, Hyun Soon; Choi, Moo Hyun; Kim, Cha Soon; Choi, Seung Jin

    2016-06-01

    Published gene expression studies for radiation-induced thyroid carcinogenesis have used various methodologies. In this study, we identified differential gene expression in a human thyroid epithelial cell line after exposure to high-dose γ-radiation. HTori-3 cells were exposed to 5 or 10 Gy of ionizing radiation using two dose rates (high-dose rate: 4.68 Gy/min, and low-dose rate: 40 mGy/h) and then implanted into the backs of BALB/c nude mice after 4 (10 Gy) or 5 weeks (5 Gy). Decreases in cell viability, increases in giant cell frequency, anchorage-independent growth in vitro, and tumorigenicity in vivo were observed. Particularly, the cells irradiated with 5 Gy at the high-dose rate or 10 Gy at the low-dose rate demonstrated more prominent tumorigenicity. Gene expression profiling was analyzed via microarray. Numerous genes that were significantly altered by a fold-change of >50% following irradiation were identified in each group. Gene expression analysis identified six commonly misregulated genes, including CRYAB, IL-18, ZNF845, CYP24A1, OR4N4 and VN1R4, at all doses. These genes involve apoptosis, the immune response, regulation of transcription, and receptor signaling pathways. Overall, the altered genes in high-dose rate (HDR) 5 Gy and low-dose rate (LDR) 10 Gy were more than those of LDR 5 Gy and HDR 10 Gy. Thus, we investigated genes associated with aggressive tumor development using the two dosage treatments. In this study, the identified gene expression profiles reflect the molecular response following high doses of external radiation exposure and may provide helpful information about radiation-induced thyroid tumors in the high-dose range. PMID:27006382

  20. Gene expression profiling in undifferentiated thyroid carcinoma induced by high-dose radiation

    PubMed Central

    Bang, Hyun Soon; Choi, Moo Hyun; Kim, Cha Soon; Choi, Seung Jin

    2016-01-01

    Published gene expression studies for radiation-induced thyroid carcinogenesis have used various methodologies. In this study, we identified differential gene expression in a human thyroid epithelial cell line after exposure to high-dose γ-radiation. HTori-3 cells were exposed to 5 or 10 Gy of ionizing radiation using two dose rates (high-dose rate: 4.68 Gy/min, and low-dose rate: 40 mGy/h) and then implanted into the backs of BALB/c nude mice after 4 (10 Gy) or 5 weeks (5 Gy). Decreases in cell viability, increases in giant cell frequency, anchorage-independent growth in vitro, and tumorigenicity in vivo were observed. Particularly, the cells irradiated with 5 Gy at the high-dose rate or 10 Gy at the low-dose rate demonstrated more prominent tumorigenicity. Gene expression profiling was analyzed via microarray. Numerous genes that were significantly altered by a fold-change of >50% following irradiation were identified in each group. Gene expression analysis identified six commonly misregulated genes, including CRYAB, IL-18, ZNF845, CYP24A1, OR4N4 and VN1R4, at all doses. These genes involve apoptosis, the immune response, regulation of transcription, and receptor signaling pathways. Overall, the altered genes in high-dose rate (HDR) 5 Gy and low-dose rate (LDR) 10 Gy were more than those of LDR 5 Gy and HDR 10 Gy. Thus, we investigated genes associated with aggressive tumor development using the two dosage treatments. In this study, the identified gene expression profiles reflect the molecular response following high doses of external radiation exposure and may provide helpful information about radiation-induced thyroid tumors in the high-dose range. PMID:27006382

  1. Three-dimensional conformal radiation therapy in the liver: MRI findings along a time continuum.

    PubMed

    Lall, Chandana; Bhargava, Puneet; Sandrasegaran, Kumaresan; Shanbhogue, Alampady K; Ramsinghani, Nilam; Koh, Young Whan; Choi, Jin Young; Choi, Joon-Il

    2015-01-01

    Recent development of 3-dimensional conformal radiation therapies provides a concentrated radiation dose to the tumor. To achieve this goal, a complex design of multiple narrow beamlets is used to shape the radiation exposure to conform to the shape of the tumor. Imaging findings after novel radiation therapy techniques differ from those of conventional radiation therapy. This article discusses changes in the liver parenchyma and tumor after conformal radiation therapy focusing on magnetic resonance imaging. PMID:25700224

  2. Theoretical, experimental and numerical methods for investigating the characteristics of laser radiation scattered in the integrated-optical waveguide with three-dimensional irregularities

    SciTech Connect

    Egorov, Alexander A

    2011-07-31

    We consider theoretical, experimental and numerical methods which make it possible to analyse the key characteristics of laser radiation scattered in the integrated-optical waveguide with three-dimensional irregularities. The main aspects of the three-dimensional vector electrodynamic problem of waveguide scattering are studied. The waveguide light scattering method is presented and its main advantages over the methods of single scattering of laser radiation are discussed. The experimental setup and results of measurements are described. Theoretical and experimental results confirming the validity of the vector theory of three-dimensional waveguide scattering of laser radiation developed by the author are compared for the first time. (fiber and integrated optics)

  3. Magnetic field effect in three-dimensional flow of an Oldroyd-B nanofluid over a radiative surface

    NASA Astrophysics Data System (ADS)

    Shehzad, S. A.; Abdullah, Z.; Abbasi, F. M.; Hayat, T.; Alsaedi, A.

    2016-02-01

    This article investigates the convective heat and mass conditions in three-dimensional flow of an Oldroyd-B nanofluid. The stretched flow is electrically conducting in the presence of an applied magnetic field. Thermal radiation effects are accounted in the energy equation. The governing nonlinear problems are computed for the convergent approximate solutions. Influences of different parameters on the dimensionless temperature and nanoparticle concentration fields are shown and examined. Quantities of physical interest namely local Nusselt and Sherwood numbers are computed and analyzed numerically. Comparison in a limiting case is made with the previous published result and an excellent agreement is noted.

  4. Three-Dimensional Characterization of Cell Clusters Using Synchrotron-Radiation-Based Micro-Computed Tomography

    NASA Astrophysics Data System (ADS)

    Müller, Ert; Riedel, Marco; Thurner, Philipp J.

    2006-04-01

    Micro-computed tomography with the highly intense, monochromatic X rays produced by the synchrotron is a superior method to nondestructively measure the local absorption in three-dimensional space. Because biological tissues and cells consist mainly of water as the surrounding medium, higher absorbing agents have to be incorporated into the structures of interest. Even without X-ray optics such as refractive lens, one can uncover the stain distribution with the spatial resolution of about 1 [mu]m. Incorporating the stain at selected cell compartments, for example, binding to the RNA/DNA, their density distribution becomes quantified. In this communication, we demonstrate that tomograms obtained at the beamlines BW2 and W2 (HASYLAB at DESY, Hamburg, Germany) and 4S (SLS, Villigen, Switzerland) clearly show that the RNA/DNA-stained HEK 293 cell clusters have a core of high density and a peripheral part of lower density, which correlate with results of optical microscopy. The inner part of the clusters is associated with nonvital cells as the result of insufficient oxygen and nutrition supply. This necrotic part is surrounded by (6 ± 1) layers of vital cells.

  5. Dispersion characteristics of three-dimensional dielectric-loaded grating for terahertz Smith-Purcell radiation

    SciTech Connect

    Cao, Miaomiao Li, Ke; University of Chinese Academy of Sciences, Beijing 100049 ; Liu, Wenxin Wang, Yong

    2014-02-15

    In this paper, a dielectric-loaded grating for Smith-Purcell device is proposed. The three-dimensional (3D) analytical theory for hot dispersion relation is obtained by using field matched method, which is solved by numerical simulations. The first and second order growth rates for the proposal model are analyzed, which is obtained by expanding hot dispersion equation at the operating point. The results show that the dispersion can be effectively weakened by introducing dielectric-loaded grating, in which the cutoff frequency is affected by the grating thickness. The dispersion curve becomes flatter and shifts towards lower frequency at the optimum grating parameters. The 3D particle-in-cell (PIC) simulation is also performed and the results are in good agreement with theoretical calculations. Comparing the first order growth rate with the second one, it reveals that the discrepancy is small when electron beam parameters are selected with small values. Otherwise, the discrepancy is large and cannot be ignored. To accurately describe the process of beam-wave interaction, the second order growth rate is necessary to apply.

  6. Tumor-Endothelial Cell Three-dimensional Spheroids: New Aspects to Enhance Radiation and Drug Therapeutics12

    PubMed Central

    Upreti, Meenakshi; Jamshidi-Parsian, Azemat; Koonce, Nathan A; Webber, Jessica S; Sharma, Sunil K; Asea, Alexzander AA; Mader, Mathew J; Griffin, Robert J

    2011-01-01

    Classic cancer research for several decades has focused on understanding the biology of tumor cells in vitro. However, extending these findings to in vivo settings has been impeded owing to limited insights on the impact of microenvironment on tumor cells. We hypothesized that tumor cell biology and treatment response would be more informative when done in the presence of stromal components, like endothelial cells, which exist in the tumor microenvironment. To that end, we have developed a system to grow three-dimensional cultures of GFP-4T1 mouse mammary tumor and 2H11 murine endothelial cells in hanging drops of medium in vitro. The presence of 2H11 endothelial cells in these three-dimensional cocultures was found to sensitize 4T1-GFP tumor cells to chemotherapy (Taxol) and, at the same time, protect cells from ionizing radiation. These spheroidal cultures can also be implanted into the dorsal skinfold window chamber of mice for fluorescence imaging of vascularization and disease progression/treatment response. We observed rapid neovascularization of the tumor-endothelial spheroids in comparison to tumor spheroids grown in nude mice. Molecular analysis revealed pronounced up-regulation of several proangiogenic factors in the tumor tissue derived from the tumor-endothelial spheroids compared with tumor-only spheroids. Furthermore, the rate of tumor growth from tumor-endothelial spheroids in mice was faster than the tumor cell-only spheroids, resulting in greater metastasis to the lung. This three-dimensional coculture model presents an improved way to investigate more pertinent aspects of the therapeutic potential for radiation and/or chemotherapy alone and in combination with antiangiogenic agents. PMID:22191001

  7. Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

    SciTech Connect

    Okada, Go; Morrell, Brian; Koughia, Cyril; Kasap, Safa; Edgar, Andy; Varoy, Chris; Belev, George; Wysokinski, Tomasz; Chapman, Dean

    2011-09-19

    The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm{sup 3+}{yields} Sm{sup 2+} valence conversion in Sm{sup 3+} doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to {approx}5 Gy and saturates at doses exceeding {approx}80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high ''peak-to-valley'' contrast have been observed by means of confocal photoluminescence microscopy.

  8. Three-Dimensional Conformal Radiation Therapy for Esophageal Squamous Cell Carcinoma: Is Elective Nodal Irradiation Necessary?

    SciTech Connect

    Zhao Kuaile; Ma Jinbo; Liu Guang; Wu Kailiang; Shi Xuehui; Jiang Guoliang

    2010-02-01

    Purpose: To evaluate the local control, survival, and toxicity associated with three-dimensional conformal radiotherapy (3D-CRT) for squamous cell carcinoma (SCC) of the esophagus, to determine the appropriate target volumes, and to determine whether elective nodal irradiation is necessary in these patients. Methods and Materials: A prospective study of 3D-CRT was undertaken in patients with esophageal SCC without distant metastases. Patients received 68.4 Gy in 41 fractions over 44 days using late-course accelerated hyperfractionated 3D-CRT. Only the primary tumor and positive lymph nodes were irradiated. Isolated out-of-field regional nodal recurrence was defined as a recurrence in an initially uninvolved regional lymph node. Results: All 53 patients who made up the study population tolerated the irradiation well. No acute or late Grade 4 or 5 toxicity was observed. The median survival time was 30 months (95% confidence interval, 17.7-41.8). The overall survival rate at 1, 2, and 3 years was 77%, 56%, and 41%, respectively. The local control rate at 1, 2, and 3 years was 83%, 74%, and 62%, respectively. Thirty-nine of the 53 patients (74%) showed treatment failure. Seventeen of the 39 (44%) developed an in-field recurrence, 18 (46%) distant metastasis with or without regional failure, and 3 (8%) an isolated out-of-field nodal recurrence only. One patient died of disease in an unknown location. Conclusions: In patients treated with 3D-CRT for esophageal SCC, the omission of elective nodal irradiation was not associated with a significant amount of failure in lymph node regions not included in the planning target volume. Local failure and distant metastases remained the predominant problems.

  9. Natural element method for solving radiative transfer with or without conduction in three-dimensional complex geometries

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Ma, Yu; Yi, Hong-Liang; Tan, He-Ping

    2013-11-01

    A meshless method called as the natural element method (NEM) is developed for solving radiative heat transfer problem in 3D complex enclosures filled with an absorbing, emitting and scattering medium. The boundary surfaces are supposed to be opaque, diffuse as well as gray. The shape functions used in NEM are constructed by the natural neighbor interpolations, which are strictly interpolant and the essential boundary conditions can be imposed directly. The NEM solutions dealing with the radiative heat transfer with or without conduction are validated by comparison with some cases reported by the literature. Furthermore, the radiative heat transfer in cubic enclosures with or without an inner hollow sphere, cylinder and elliptical cylinder is also examined to demonstrate the applicability of the present method towards various three-dimensional geometries. For pure radiative transfer, both the cases of radiative non-equilibrium and radiative equilibrium are investigated. For combined conduction and radiation heat transfer, effects of various parameters such as the conduction-radiation parameter, the scattering albedo, the extinction coefficient, and the boundary emissivity are analyzed on the temperature distributions.

  10. Three-dimensional tomographic imaging for dynamic radiation behavior study using infrared imaging video bolometers in large helical device plasma.

    PubMed

    Sano, Ryuichi; Peterson, Byron J; Teranishi, Masaru; Iwama, Naofumi; Kobayashi, Masahiro; Mukai, Kiyofumi; Pandya, Shwetang N

    2016-05-01

    A three-dimensional (3D) tomography system using four InfraRed imaging Video Bolometers (IRVBs) has been designed with a helical periodicity assumption for the purpose of plasma radiation measurement in the large helical device. For the spatial inversion of large sized arrays, the system has been numerically and experimentally examined using the Tikhonov regularization with the criterion of minimum generalized cross validation, which is the standard solver of inverse problems. The 3D transport code EMC3-EIRENE for impurity behavior and related radiation has been used to produce phantoms for numerical tests, and the relative calibration of the IRVB images has been carried out with a simple function model of the decaying plasma in a radiation collapse. The tomography system can respond to temporal changes in the plasma profile and identify the 3D dynamic behavior of radiation, such as the radiation enhancement that starts from the inboard side of the torus, during the radiation collapse. The reconstruction results are also consistent with the output signals of a resistive bolometer. These results indicate that the designed 3D tomography system is available for the 3D imaging of radiation. The first 3D direct tomographic measurement of a magnetically confined plasma has been achieved. PMID:27250418

  11. Three-dimensional tomographic imaging for dynamic radiation behavior study using infrared imaging video bolometers in large helical device plasma

    NASA Astrophysics Data System (ADS)

    Sano, Ryuichi; Peterson, Byron J.; Teranishi, Masaru; Iwama, Naofumi; Kobayashi, Masahiro; Mukai, Kiyofumi; Pandya, Shwetang N.

    2016-05-01

    A three-dimensional (3D) tomography system using four InfraRed imaging Video Bolometers (IRVBs) has been designed with a helical periodicity assumption for the purpose of plasma radiation measurement in the large helical device. For the spatial inversion of large sized arrays, the system has been numerically and experimentally examined using the Tikhonov regularization with the criterion of minimum generalized cross validation, which is the standard solver of inverse problems. The 3D transport code EMC3-EIRENE for impurity behavior and related radiation has been used to produce phantoms for numerical tests, and the relative calibration of the IRVB images has been carried out with a simple function model of the decaying plasma in a radiation collapse. The tomography system can respond to temporal changes in the plasma profile and identify the 3D dynamic behavior of radiation, such as the radiation enhancement that starts from the inboard side of the torus, during the radiation collapse. The reconstruction results are also consistent with the output signals of a resistive bolometer. These results indicate that the designed 3D tomography system is available for the 3D imaging of radiation. The first 3D direct tomographic measurement of a magnetically confined plasma has been achieved.

  12. Calibration of three-dimensional ultrasound images for image-guided radiation therapy.

    PubMed

    Bouchet, L G; Meeks, S L; Goodchild, G; Bova, F J; Buatti, J M; Friedman, W A

    2001-02-01

    A new technique of patient positioning for radiotherapy/radiosurgery of extracranial tumours using three-dimensional (3D) ultrasound images has been developed. The ultrasound probe position is tracked within the treatment room via infrared light emitting diodes (IRLEDs) attached to the probe. In order to retrieve the corresponding room position of the ultrasound image, we developed an initial ultrasound probe calibration technique for both 2D and 3D ultrasound systems. This technique is based on knowledge of points in both room and image coordinates. We first tested the performance of three algorithms in retrieving geometrical transformations using synthetic data with different noise levels. Closed form solution algorithms (singular value decomposition and Horn's quaternion algorithms) were shown to outperform the Hooke and Jeeves iterative algorithm in both speed and accuracy. Furthermore, these simulations show that for a random noise level of 2.5, 5, 7.5 and 10 mm, the number of points required for a transformation accuracy better than 1 mm is 25, 100, 200 and 500 points respectively. Finally, we verified the tracking accuracy of this system using a specially designed ultrasound phantom. Since ultrasound images have a high noise level, we designed an ultrasound phantom that provides a large number of points for the calibration. This tissue equivalent phantom is made of nylon wires, and its room position is optically tracked using IRLEDs. By obtaining multiple images through the nylon wires, the calibration technique uses an average of 300 points for 3D ultrasound volumes and 200 for 2D ultrasound images, and its stability is very good for both rotation (standard deviation: 0.4 degrees) and translation (standard deviation: 0.3 mm) transformations. After this initial calibration procedure, the position of any voxel in the ultrasound image volume can be determined in world space, thereby allowing real-time image guidance of therapeutic procedures. Finally, the

  13. Effect of high doses of gamma radiation on the functional characteristics of amniotic membrane

    NASA Astrophysics Data System (ADS)

    Singh, Rita; Purohit, Sumita; Chacharkar, M. P.

    2007-06-01

    The effect of different doses of gamma radiation viz. 25, 36 and 50 kGy on the chemical and functional characteristics of the amniotic membrane was studied. The change in the chemical structure of amniotic membranes at high doses of gamma irradiation was evaluated by means of Infrared (IR) Spectroscopy. The degradation of amnion on irradiation with gamma rays could produce a relative variation in IR absorption troughs. This kind of variation was absent in the samples irradiated to doses of 25, 36 and 50 kGy indicating no qualitative change in the material property of amnion. No significant differences in the water absorption capacity and water vapour transmission rate of amniotic membranes irradiated to different doses were observed. Impermeability of the amniotic membranes to different microorganisms was also not affected at high doses of gamma radiation. Gamma irradiation at doses of 25-50 kGy did not evoke undesirable changes in the functional properties of the amniotic membrane.

  14. Radiation Effect On Three Dimensional Vertical Channel Flow Through Porous Medium

    NASA Astrophysics Data System (ADS)

    Guria, M.

    2015-12-01

    The flow of a viscous incompressible fluid through a vertical channel in the presence of radiation immersed in a porous medium has been studied. Approximate solutions have been obtained for the velocity and temperature fields, shear stresses and rate of heat transfer using the perturbation technique. It is found that the primary velocity decreases with an increase in the radiation parameter as well as the Prandtl number for cooling of the plate. It is also found that with an increase in the permeability parameter, the primary velocity increases for cooling of the plate. The magnitude of the secondary velocity decreases near the plate y = 0 and increases near the plate y = d with an increase in the permeability parameter. The temperature distribution decreases with an increase of the radiation parameter as wall as the Prandtl number for cooling of the plate. The shear stresses and the rate of heat transfer, which are of physical interest, are presented in the form of tables.

  15. Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy

    SciTech Connect

    Guardiola, C. Solberg, T.; Carabe, A.; Quirion, D.; Pellegrini, G.; Fleta, C.; Esteban, S.; Lozano, M.; Cortés-Giraldo, M. A.; Gómez, F.

    2015-07-13

    In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an {sup 241}Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program.

  16. A three dimensional radiative transfer method for optical remote sensing of vegetated land surfaces

    NASA Technical Reports Server (NTRS)

    Asrar, Ghassem; Myneni, Ranga B.; Choudhury, Bhaskar J.

    1991-01-01

    In the application of remote sensing at optical wavelengths to vegetated surfaces from satellite borne high resolution instruments, an understanding of the various physical mechanisms that contribute to the measured signal is important. A numerical method of solving the radiative transfer equation in three dimensions is reported. The reliability of coding and accuracy of the algorithm are evaluated by benchmarching. Parametrization of the methods and results of a simulation are presented. The method is tested with experimental data of canopy bidirectional reflectance factors. The effect of spatial heterogeneity on the relationship between the simple ratio and normalized vrs absorbed Photosynthetically Active Radiation (PAR) is discussed.

  17. Extreme events in resonant radiation from three-dimensional light bullets

    NASA Astrophysics Data System (ADS)

    Roger, T.; Majus, D.; Tamosauskas, G.; Panagiotopoulos, P.; Kolesik, M.; Genty, G.; GražulevičiÅ«tÄ--, I.; Dubietis, A.; Faccio, D.

    2014-09-01

    We report measurements that show extreme events in the statistics of resonant radiation emitted from spatiotemporal light bullets. We trace the origin of these extreme events back to instabilities leading to steep gradients in the temporal profile of the intense light bullet that occur during the initial collapse dynamics. Numerical simulations reproduce the extreme valued statistics of the resonant radiation which are found to be intrinsically linked to the simultaneous occurrence of both temporal and spatial self-focusing dynamics. Small fluctuations in both the input energy and in the spatial phase curvature explain the observed extreme behavior.

  18. New lattice Boltzmann method for the simulation of three-dimensional radiation transfer in turbid media.

    PubMed

    McHardy, Christopher; Horneber, Tobias; Rauh, Cornelia

    2016-07-25

    Based on the kinetic theory of photons, a new lattice Boltzmann method for the simulation of 3D radiation transport is presented. The method was successfully validated with Monte Carlo simulations of radiation transport in optical thick absorbing and non-absorbing turbid media containing either isotropic or anisotropic scatterers. Moreover, for the approximation of Mie-scattering, a new iterative algebraic approach for the discretization of the scattering phase function was developed, ensuring full conservation of energy and asymmetry after discretization. It was found that the main error sources of the method are caused by linearization and ray effects and suggestions for further improvement of the method are made. PMID:27464152

  19. Radiation bronchitis and stenosis secondary to high dose rate endobronchial irradiation

    SciTech Connect

    Speiser, B.L. ); Spratling, L.

    1993-03-15

    The purpose of the study was to describe a new clinical entity observed in follow-up bronchoscopies in patients who were treated with high dose rate and medium dose rate remote afterloading brachytherapy of the tracheobronchial tree. Patients were treated by protocol with medium dose rate, 47 patients receiving 1000 cGy at a 5 mm depth times three fractions, high dose rate 144 patients receiving 1000 cGy at a 10 mm depth for three fractions and high dose rate 151 patients receiving cGy at a 10 mm depth for three fractions followed by bronchoscopy. Incidence of this entity was 9% for the first group, 12% for the second, and 13% for the third group. Reactions were grade 1 consisting of mild inflammatory response with a partial whitish circumferential membrane in an asymptomatic patient; grade 2, thicker complete white circumferential membrane with cough and/or obstructive problems requiring intervention; grade 3, severe inflammatory response with marked membranous exudate and mild fibrotic reaction; and grade 4 a predominant fibrotic reaction with progressive stenosis. Variables associated with a slightly increased incidence of radiation bronchitis and stenosis included: large cell carcinoma histology, curative intent, prior laser photoresection, and/or concurrent external radiation. Survival was the strongest predictor of the reaction. Radiation bronchitis and stenosis is a new clinical entity that must be identified in bronchial brachytherapy patients and treated appropriately. 23 refs., 3 figs., 7 tabs.

  20. Radiation dose delivered to the proximal penis as a predictor of the risk of erectile dysfunction after three-dimensional conformal radiotherapy for localized prostate cancer

    SciTech Connect

    Wernicke, A. Gabriella; Valicenti, Richard . E-mail: richard.valicenti@mail.tju.edu; DiEva, Kelly; Houser, Christopher; Pequignot, Ed

    2004-12-01

    Purpose/objective: In this study, we evaluated in a serial manner whether radiation dose to the bulb of the penis is predictive of erectile dysfunction, ejaculatory difficulty (EJ), and overall satisfaction with sex life (quality of life) by using serial validated self-administered questionnaires. Methods and materials: Twenty-nine potent men with AJCC Stage II prostate cancer treated with three-dimensional conformal radiation therapy alone to a median dose 72.0 Gy (range: 66.6-79.2 Gy) were evaluated by determining the doses received by the penile bulb. The penile bulb was delineated volumetrically, and the dose-volume histogram was obtained on each patient. Results: The median follow-up time was 35 months (range, 16-43 months). We found that for D{sub 30}, D{sub 45}, D{sub 60}, and D{sub 75} (doses to a percent volume of PB: 30%, 45%, 60%, and 75%), higher than the corresponding median dose (defined as high-dose group) correlated with an increased risk of impotence (erectile dysfunction firmness score = 0) (odds ratio [OR] = 7.5, p = 0.02; OR = 7.5, p = 0.02; OR = 8.6, p = 0.008; and OR = 6.9, p = 0.015, respectively). Similarly, for EJD D{sub 30}, D{sub 45}, D{sub 60}, and D{sub 75}, doses higher than the corresponding median ones correlated with worsening ejaculatory function score (EJ = 0 or 1) (OR = 8, p = 0.013; OR = 8, p 0.013; OR = 9.2, p = 0.015; and OR = 8, p = 0.026, respectively). For quality of life, low ({<=}median dose) dose groups of patients improve over time, whereas high-dose groups of patients worsen. Conclusions: This study supports the existence of a penile bulb dose-volume relationship underlying the development of radiation-induced erectile dysfunction. Our data may guide the use of inverse treatment planning to maximize the probability of maintaining sexual potency after radiation therapy.

  1. Estimation of radiation-induced cancer from three-dimensional dose distributions: Concept of organ equivalent dose

    SciTech Connect

    Schneider, Uwe . E-mail: uwe.schneider@psi.ch; Zwahlen, Daniel; Ross, Dieter; Kaser-Hotz, Barbara

    2005-04-01

    Purpose: Estimates of secondary cancer risk after radiotherapy are becoming more important for comparative treatment planning. Modern treatment planning systems provide accurate three-dimensional dose distributions for each individual patient. These data open up new possibilities for more precise estimates of secondary cancer incidence rates in the irradiated organs. We report a new method to estimate organ-specific radiation-induced cancer incidence rates. The concept of an organ equivalent dose (OED) for radiation-induced cancer assumes that any two dose distributions in an organ are equivalent if they cause the same radiation-induced cancer incidence. Methods and Materials: The two operational parameters of the OED concept are the organ-specific cancer incidence rate at low doses, which is taken from the data of the atomic bomb survivors, and cell sterilization at higher doses. The effect of cell sterilization in various organs was estimated by analyzing the secondary cancer incidence data of patients with Hodgkin's disease who were treated with radiotherapy in between 1962 and 1993. The radiotherapy plans used at the time the patients had been treated were reconstructed on a fully segmented whole body CT scan. The dose distributions were calculated in individual organs for which cancer incidence data were available. The model parameter that described cell sterilization was obtained by analyzing the dose and cancer incidence rates for the individual organs. Results: We found organ-specific cell radiosensitivities that varied from 0.017 for the mouth and pharynx up to 1.592 for the bladder. Using the two model parameters (organ-specific cancer incidence rate and the parameter characterizing cell sterilization), the OED concept can be applied to any three-dimensional dose distribution to analyze cancer incidence. Conclusion: We believe that the concept of OED presented in this investigation represents a first step in assessing the potential risk of secondary

  2. Radiation Parameterization for Three-Dimensional Inhomogeneous Cirrus Clouds Applied to ARM Data and Climate Models

    SciTech Connect

    Kuo-Nan Liou

    2003-12-29

    OAK-B135 (a) We developed a 3D radiative transfer model to simulate the transfer of solar and thermal infrared radiation in inhomogeneous cirrus clouds. The model utilized a diffusion approximation approach (four-term expansion in the intensity) employing Cartesian coordinates. The required single-scattering parameters, including the extinction coefficient, single-scattering albedo, and asymmetry factor, for input to the model, were parameterized in terms of the ice water content and mean effective ice crystal size. The incorporation of gaseous absorption in multiple scattering atmospheres was accomplished by means of the correlated k-distribution approach. In addition, the strong forward diffraction nature in the phase function was accounted for in each predivided spatial grid based on a delta-function adjustment. The radiation parameterization developed herein is applied to potential cloud configurations generated from GCMs to investigate broken clouds and cloud-overlapping effects on the domain-averaged heating rate. Cloud inhomogeneity plays an important role in the determination of flux and heating rate distributions. Clouds with maximum overlap tend to produce less heating than those with random overlap. Broken clouds show more solar heating as well as more IR cooling as compared to a continuous cloud field (Gu and Liou, 2001). (b) We incorporated a contemporary radiation parameterization scheme in the UCLA atmospheric GCM in collaboration with the UCLA GCM group. In conjunction with the cloud/radiation process studies, we developed a physically-based cloud cover formation scheme in association with radiation calculations. The model clouds were first vertically grouped in terms of low, middle, and high types. Maximum overlap was then used for each cloud type, followed by random overlap among the three cloud types. Fu and Liou's 1D radiation code with modification was subsequently employed for pixel-by-pixel radiation calculations in the UCLA GCM. We showed

  3. A three-dimensional radiative transfer method for optical remote sensing of vegetated land surfaces

    NASA Technical Reports Server (NTRS)

    Myneni, R. B.; Asrar, G.; Hall, F. G.

    1992-01-01

    A numerical method for solving the radiative transfer equation in three spatial dimensions is briefly discussed focusing on an efficient acceleration algorithm. The reliability of coding and accuracy of the algorithm are evaluated by benchmarking. Parameterization of the method and results of a simulation are presented to document the utility of the method for remote sensing applications. Attention is also given to a simple model of the hot spot effect and sample calculations.

  4. Three-dimensional relativistic pair plasma reconnection with radiative feedback in the Crab Nebula

    SciTech Connect

    Cerutti, B.; Werner, G. R.; Uzdensky, D. A.; Begelman, M. C. E-mail: greg.werner@colorado.edu E-mail: mitch@jila.colorado.edu

    2014-02-20

    The discovery of rapid synchrotron gamma-ray flares above 100 MeV from the Crab Nebula has attracted new interest in alternative particle acceleration mechanisms in pulsar wind nebulae. Diffuse shock-acceleration fails to explain the flares because particle acceleration and emission occur during a single or even sub-Larmor timescale. In this regime, the synchrotron energy losses induce a drag force on the particle motion that balances the electric acceleration and prevents the emission of synchrotron radiation above 160 MeV. Previous analytical studies and two-dimensional (2D) particle-in-cell (PIC) simulations indicate that relativistic reconnection is a viable mechanism to circumvent the above difficulties. The reconnection electric field localized at X-points linearly accelerates particles with little radiative energy losses. In this paper, we check whether this mechanism survives in three dimension (3D), using a set of large PIC simulations with radiation reaction force and with a guide field. In agreement with earlier works, we find that the relativistic drift kink instability deforms and then disrupts the layer, resulting in significant plasma heating but few non-thermal particles. A moderate guide field stabilizes the layer and enables particle acceleration. We report that 3D magnetic reconnection can accelerate particles above the standard radiation reaction limit, although the effect is less pronounced than in 2D with no guide field. We confirm that the highest-energy particles form compact bunches within magnetic flux ropes, and a beam tightly confined within the reconnection layer, which could result in the observed Crab flares when, by chance, the beam crosses our line of sight.

  5. Long-term androgen deprivation increases Grade 2 and higher late morbidity in prostate cancer patients treated with three-dimensional conformal radiation therapy

    SciTech Connect

    Feigenberg, Steven J. . E-mail: S_Feigenberg@fccc.edu; Hanlon, Alexandra L.; Horwitz, Eric M.; Uzzo, Robert G.; Eisenberg, Debra; Pollack, Alan

    2005-06-01

    Purpose: To determine whether the use of androgen deprivation (AD) increases late morbidity when combined with high-dose three-dimensional conformal radiation therapy (3D-CRT). Methods and materials: Between May 1989 and November 1998, 1,204 patients were treated for prostate cancer with 3D-CRT to a median dose of 74 Gy. Patients were evaluated every 3-6 months. No AD was given to 945 patients, whereas 140 and 119 patients, respectively, received short-term AD (STAD; {<=}6 months) and long-term AD (LTAD; > 6 months). Radiation morbidity was graded according to the Fox Chase modification of the Late Effects Normal Tissue Task Force late morbidity scale. Covariates in the multivariate analysis (MVA) included age, history of diabetes mellitus, prostate-specific antigen (PSA) level, Gleason score, T category, RT field size, total RT dose, use of rectal shielding, and AD status (no AD vs. STAD vs. LTAD). Results: The only independent predictor for Grade 2 or higher genitourinary (GU) morbidity in the MVA was the use of AD (p = 0.0065). The 5-year risk of Grade 2 or higher GU morbidity was 8% for no AD, 8% for STAD, and 14% for LTAD (p = 0.02). Independent predictors of Grade 2 or higher gastrointestinal (GI) morbidity in the MVA were the use of AD (p = 0.0079), higher total radiation dose (p < 0.0001), the lack of a rectal shield (p = 0.0003), and older age (p = 0.0009). The 5-year actuarial risk of Grade 2 or higher GI morbidity was 17% for no AD vs. 18% for STAD and 26% for LTAD (p = 0.017). Conclusions: The use of LTAD seems to significantly increase the risk of both GU and GI morbidity for patients treated with 3D-CRT.

  6. Comparison of low and high dose ionising radiation using topological analysis of gene coexpression networks

    PubMed Central

    2012-01-01

    Background The growing use of imaging procedures in medicine has raised concerns about exposure to low-dose ionising radiation (LDIR). While the disastrous effects of high dose ionising radiation (HDIR) is well documented, the detrimental effects of LDIR is not well understood and has been a topic of much debate. Since little is known about the effects of LDIR, various kinds of wet-lab and computational analyses are required to advance knowledge in this domain. In this paper we carry out an “upside-down pyramid” form of systems biology analysis of microarray data. We characterised the global genomic response following 10 cGy (low dose) and 100 cGy (high dose) doses of X-ray ionising radiation at four time points by analysing the topology of gene coexpression networks. This study includes a rich experimental design and state-of-the-art computational systems biology methods of analysis to study the differences in the transcriptional response of skin cells exposed to low and high doses of radiation. Results Using this method we found important genes that have been linked to immune response, cell survival and apoptosis. Furthermore, we also were able to identify genes such as BRCA1, ABCA1, TNFRSF1B, MLLT11 that have been associated with various types of cancers. We were also able to detect many genes known to be associated with various medical conditions. Conclusions Our method of applying network topological differences can aid in identifying the differences among similar (eg: radiation effect) yet very different biological conditions (eg: different dose and time) to generate testable hypotheses. This is the first study where a network level analysis was performed across two different radiation doses at various time points, thereby illustrating changes in the cellular response over time. PMID:22594378

  7. Experimental observation of anomalous thermal radiation from a three-dimensional metallic photonic crystal.

    PubMed

    Hsieh, Mei-Li; Lin, Shawn-Yu; Bur, James A; Shenoi, Rajeev

    2015-06-12

    We report some striking results on thermal radiation properties of a resonantly coupled cavity photonic crystal (PhC) at elevated temperatures (T = 400-900 K). We experimentally found that at resonant wavelengths, λ = 1.1, 1.64, 2.85 μm, the PhC emission is spectrally selective, quasi-coherent, directional, and shows significant deviation from Planck's blackbody law at equilibrium. The presence of non-equilibrium effects, driven by strong thermal excitation and cavity resonance, may be the major cause for our experimental observation. PMID:25990113

  8. A Novel Implementation of Massively Parallel Three Dimensional Monte Carlo Radiation Transport

    NASA Astrophysics Data System (ADS)

    Robinson, P. B.; Peterson, J. D. L.

    2005-12-01

    The goal of our summer project was to implement the difference formulation for radiation transport into Cosmos++, a multidimensional, massively parallel, magneto hydrodynamics code for astrophysical applications (Peter Anninos - AX). The difference formulation is a new method for Symbolic Implicit Monte Carlo thermal transport (Brooks and Szöke - PAT). Formerly, simultaneous implementation of fully implicit Monte Carlo radiation transport in multiple dimensions on multiple processors had not been convincingly demonstrated. We found that a combination of the difference formulation and the inherent structure of Cosmos++ makes such an implementation both accurate and straightforward. We developed a "nearly nearest neighbor physics" technique to allow each processor to work independently, even with a fully implicit code. This technique coupled with the increased accuracy of an implicit Monte Carlo solution and the efficiency of parallel computing systems allows us to demonstrate the possibility of massively parallel thermal transport. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48

  9. A three-dimensional phase space dynamical model of the Earth{close_quote}s radiation belt

    SciTech Connect

    Boscher, D.M.; Beutier, T.; Bourdarie, S.

    1996-07-01

    A three dimensional phase space model of the Earth{close_quote}s radiation belt is presented. We have taken into account the magnetic and electric radial diffusions, the pitch angle diffusions due to Coulomb interactions and interactions with the plasmaspheric hiss, and the Coulomb drag. First, a steady state of the belt is presented. Two main maxima are obtained, corresponding to the inner and outer parts of the belt. Then, we have modelled a simple injection at the external boundary. The particle transport seems like what was measured aboard satellites. A high energy particle loss is found, by comparing the model results and the measurements. It remains to be explained. {copyright} {ital 1996 American Institute of Physics.}

  10. The development and investigation of a prototype three-dimensional compensator for whole brain radiation therapy

    NASA Astrophysics Data System (ADS)

    Keall, Paul; Arief, Isti; Shamas, Sofia; Weiss, Elisabeth; Castle, Steven

    2008-05-01

    Whole brain radiation therapy (WBRT) is the standard treatment for patients with brain metastases, and is often used in conjunction with stereotactic radiotherapy for patients with a limited number of brain metastases, as well as prophylactic cranial irradiation. The use of open fields (conventionally used for WBRT) leads to higher doses to the brain periphery if dose is prescribed to the brain center at the largest lateral radius. These dose variations potentially compromise treatment efficacy and translate to increased side effects. The goal of this research was to design and construct a 3D 'brain wedge' to compensate dose heterogeneities in WBRT. Radiation transport theory was invoked to calculate the desired shape of a wedge to achieve a uniform dose distribution at the sagittal plane for an ellipsoid irradiated medium. The calculations yielded a smooth 3D wedge design to account for the missing tissue at the peripheral areas of the brain. A wedge was machined based on the calculation results. Three ellipsoid phantoms, spanning the mean and ± two standard deviations from the mean cranial dimensions were constructed, representing 95% of the adult population. Film was placed at the sagittal plane for each of the three phantoms and irradiated with 6 MV photons, with the wedge in place. Sagittal plane isodose plots for the three phantoms demonstrated the feasibility of this wedge to create a homogeneous distribution with similar results observed for the three phantom sizes, indicating that a single wedge may be sufficient to cover 95% of the adult population. The sagittal dose is a reasonable estimate of the off-axis dose for whole brain radiation therapy. Comparing the dose with and without the wedge the average minimum dose was higher (90% versus 86%), the maximum dose was lower (107% versus 113%) and the dose variation was lower (one standard deviation 2.7% versus 4.6%). In summary, a simple and effective 3D wedge for whole brain radiotherapy has been developed

  11. Spot Radiative Ignition and Subsequent Three Dimensional Flame Spread Over Thin Cellulose Fuels

    NASA Technical Reports Server (NTRS)

    Olson, Sandra L.; Kashiwagi, T.; Kikuchi, M.; Fujita, O.; Ito, K.

    1999-01-01

    Spontaneous radiative ignition and transition to flame spread over thin cellulose fuel samples was studied aboard the USMP-3 STS-75 Space Shuttle mission, and in three test series in the 10 second Japan Microgravity Center (JAMIC). A focused beam from a tungsten/halogen lamp was used to ignite the center of the fuel sample while an external air flow was varied from 0 to 10 cm/s. Non-piloted radiative ignition of the paper was found to occur more easily in microgravity than in normal gravity. Ignition of the sample was achieved under all conditions studied (shuttle cabin air, 21%-50% O2 in JAMIC), with transition to flame spread occurring for all but the lowest oxygen and flow conditions. While radiative ignition in a quiescent atmosphere was achieved, the flame quickly extinguished in air. The ignition delay time was proportional to the gas-phase mixing time, which is estimated using the inverse flow rate. The ignition delay was a much stronger function of flow at lower oxygen concentrations. After ignition, the flame initially spread only upstream, in a fan-shaped pattern. The fan angle increased with increasing external flow and oxygen concentration from zero angle (tunneling flame spread) at the limiting 0.5 cm/s external air flow, to 90 degrees (semicircular flame spread) for external flows at and above 5 cm/s, and higher oxygen concentrations. The fan angle was shown to be directly related to the limiting air flow velocity. Despite the convective heating from the upstream flame, the downstream flame was inhibited due to the 'oxygen shadow' of the upstream flame for the air flow conditions studied. Downstream flame spread rates in air, measured after upstream flame spread was complete and extinguished, were slower than upstream flame spread rates at the same flow. The quench regime for the transition to flame spread was skewed toward the downstream, due to the augmenting role of diffusion for opposed flow flame spread, versus the canceling effect of diffusion

  12. Delayed activation of human microglial cells by high dose ionizing radiation.

    PubMed

    Chen, Hongxin; Chong, Zhao Zhong; De Toledo, Sonia M; Azzam, Edouard I; Elkabes, Stella; Souayah, Nizar

    2016-09-01

    Recent studies have shown that microglia affects the fate of neural stem cells in response to ionizing radiation, which suggests a role for microglia in radiation-induced degenerative outcomes. We therefore investigated the effects of γ-irradiation on cell survival, proliferation, and activation of microglia and explored associated mechanisms. Specifically, we evaluated cellular and molecular changes associated with exposure of human microglial cells (CHME5) to low and high doses of acute cesium-137 γ rays. Twenty-four hours after irradiation, cell cycle analyses revealed dose-dependent decreases in the fraction of cells in S and G2/M phase, which correlated with significant oxidative stress. By one week after irradiation, 20-30% of the cells exposed to high doses of γ rays underwent apoptosis, which correlated with significant concomitant decrease in metabolic activity as assessed by the MTT assay, and microglial activation as judged by both morphological changes and increased expression of Glut-5 and CR43. These changes were associated with increases in the mRNA levels for IL-1α, IL-10 and TNFα. Together, the results show that human CHME5 microglia are relatively resistant to low and moderate doses of γ rays, but are sensitive to acute high doses, and that CHME5 cells are a useful tool for in vitro study of human microglia. PMID:27265419

  13. Polarized radiance fields under a dynamic ocean surface: a three-dimensional radiative transfer solution

    SciTech Connect

    You Yu; Zhai Pengwang; Kattawar, George W.; Yang Ping

    2009-06-01

    The hybrid matrix operator, Monte Carlo (HMOMC) method previously reported [Appl. Opt.47, 1063-1071 (2008)APOPAI0003-693510.1364/AO.47.001063] is improved by neglecting higher-order terms in the coupling of the matrix operators and by introducing a dual grid scheme. The computational efficiency for solving the vector radiative transfer equation in a full 3D coupled atmosphere-surface-ocean system is substantially improved, and, thus, large-scale simulations of the radiance distribution become feasible. The improved method is applied to the computation of the polarized radiance field under realistic surface waves simulated by the power spectral density method. To the authors' best knowledge, this is the first time that the polarized radiance field under a dynamic ocean surface and the underwater image of an object above such an ocean surface have been reported.

  14. Effect of ionizing radiation on acinar morphogenesis of human prostatic epithelial cells under three-dimensional culture conditions.

    PubMed

    Wang, T; X, S Ma; Kong, D; Yi, H; Wang, X; Liang, B; Xu, H; He, M; Jia, L; Qased, A B; Yang, Y; Liu, X

    2012-01-01

    Homeostasis is maintained by the interplay of multiple factors that directly or indirectly regulate cell proliferation and cell death. Complex multiple interactions between cells and the extracellular matrix occur during acinar morphogenesis and changes in these might indicate carcinogenesis of cells from a normal to a malignant, invasive phenotype. In this study, the human prostatic epithelial cell line RWPE-1 was cultured under three-dimensional (3-D) culture conditions, and the effect of ionizing radiation on acinar morphogenesis and its association with autophagy were discussed. The results illustrated that formation of specific spheroid (acinar) structures was detectable under 3-D culture conditions. Radiation induced the disruption of acini in different cell models using either gene overexpression (Akt) or gene knock-down (Beclin 1 and ATG7). Introduction of Akt not only accelerated the growth of cells (i.e., caused the cells to manifest elongating and microspike-like structures that are obviously different from structures seen in wild-type RWPE-1 cells under two-dimensional conditions), but also changed their morphological characteristics under 3-D culture conditions. Knock-down of autophagy-related genes (Beclin 1 and ATG7) increased the radiosensitivity of cells under 3-D culture conditions, and cells died of non-apoptotic death after radiation. The results suggested that ionizing radiation may change the cell phenotype and the formation of acini. Additionally even the autophagy mechanism may play a role in these processes. PMID:22296497

  15. Validating the MYSTIC three-dimensional radiative transfer model with observations from the complex topography of Arizona's Meteor Crater

    NASA Astrophysics Data System (ADS)

    Mayer, B.; Hoch, S. W.; Whiteman, C. D.

    2010-05-01

    The MYSTIC three-dimensional Monte-Carlo radiative transfer model has been extended to simulate solar and thermal irradiances with a rigorous consideration of topography. Forward as well as backward Monte Carlo simulations are possible for arbitrarily oriented surfaces and we demonstrate that the backward Monte Carlo technique is superior to the forward method for applications involving topography, by greatly reducing the computational demands. MYSTIC is used to simulate the short- and longwave radiation fields during a clear day and night in and around Arizona's Meteor Crater, a bowl-shaped, 165-m-deep basin with a diameter of 1200 m. The simulations are made over a 4 by 4 km domain using a 10-m horizontal resolution digital elevation model and meteorological input data collected during the METCRAX (Meteor Crater Experiment) field experiment in 2006. Irradiance (or radiative flux) measurements at multiple locations inside the crater are then used to evaluate the simulations. MYSTIC is shown to realistically model the complex interactions between topography and the radiative field, resolving the effects of terrain shading, terrain exposure, and longwave surface emissions. The effects of surface temperature variations and of temperature stratification within the crater atmosphere on the near-surface longwave irradiance are then evaluated with additional simulations.

  16. Validating the MYSTIC three-dimensional radiative transfer model with observations from the complex topography of Arizona's Meteor Crater

    NASA Astrophysics Data System (ADS)

    Mayer, B.; Hoch, S. W.; Whiteman, C. D.

    2010-09-01

    The MYSTIC three-dimensional Monte-Carlo radiative transfer model has been extended to simulate solar and thermal irradiances with a rigorous consideration of topography. Forward as well as backward Monte Carlo simulations are possible for arbitrarily oriented surfaces and we demonstrate that the backward Monte Carlo technique is superior to the forward method for applications involving topography, by greatly reducing the computational demands. MYSTIC is used to simulate the short- and longwave radiation fields during a clear day and night in and around Arizona's Meteor Crater, a bowl-shaped, 165-m-deep basin with a diameter of 1200 m. The simulations are made over a 4 by 4 km2 domain using a 10-m horizontal resolution digital elevation model and meteorological input data collected during the METCRAX (Meteor Crater Experiment) field experiment in 2006. Irradiance (or radiative flux) measurements at multiple locations inside the crater are then used to evaluate the simulations. MYSTIC is shown to realistically model the complex interactions between topography and the radiative field, resolving the effects of terrain shading, terrain exposure, and longwave surface emissions. The effects of surface temperature variations and of temperature stratification within the crater atmosphere on the near-surface longwave irradiance are then evaluated with additional simulations.

  17. Three-dimensional acoustic radiation force on an arbitrarily located elastic sphere.

    PubMed

    Baresch, Diego; Thomas, Jean-Louis; Marchiano, Régis

    2013-01-01

    This work aims to model the acoustic radiation forces acting on an elastic sphere placed in an inviscid fluid. An expression of the axial and transverse forces exerted on the sphere is derived. The analysis is based on the scattering of an arbitrary acoustic field expanded in the spherical coordinate system centered on the spherical scatterer. The sphere is allowed to be arbitrarily located. The special case of high order Bessel beams, acoustical vortices, are considered. These types of beams have a helicoidal wave front, i.e., a screw-type phase singularity and hence, the beam has a central dark core of zero amplitude surrounded by an intense ring. Depending on the sphere's radius, different radial equilibrium positions may exist and the sphere can be set in rotation around the beam axis by an azimuthal force. This confirms the pseudo-angular moment transfer from the beam to the sphere. Cases where the axial force is directed opposite to the direction of the beam propagation are investigated and the potential use of Bessel beams as tractor beams is demonstrated. Numerical results provide an impetus for further designing acoustical tweezers for potential applications in particle entrapment and remote controlled manipulation. PMID:23297880

  18. Quantifying the Effects of Radiation on Tumour Vasculature with High-Frequency Three-Dimensional Power Doppler Ultrasound

    NASA Astrophysics Data System (ADS)

    Hupple, Clinton

    Recent evidence suggests that radiation may have a significant effect on tumour vasculature in addition to damaging tumour cell DNA. It is well established that endothelial cells are among the first cells to respond after administration of ionizing radiation in both normal and tumour tissues. It has also been suggested that microvascular dysfunction may regulate tumour response to radiotherapy at high doses. However, due to limitations in imaging the microcirculation this response is not well characterized. Advances in high-frequency ultrasound and computation methods now make it possible to acquire and analyze 3-D ultrasound data of tumour blood flow in tumour microcirculation. This thesis outlines the work done to test the hypothesis that single dose 8 Gy radiotherapy produces changes in tumour blood vessels which can be quantified using high-frequency power Doppler ultrasound. In addition, the issue of reproducibility of power Doppler measurements and the relationship between histopathology and power Doppler measurements have been examined.

  19. Chemistry in the First Hydrostatic Core Stage by Adopting Three-dimensional Radiation Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Furuya, Kenji; Aikawa, Yuri; Tomida, Kengo; Matsumoto, Tomoaki; Saigo, Kazuya; Tomisaka, Kohji; Hersant, Franck; Wakelam, Valentine

    2012-10-01

    We investigate molecular evolution from a molecular cloud core to a first hydrostatic core in three spatial dimensions. We perform a radiation hydrodynamic simulation in order to trace fluid parcels, in which molecular evolution is investigated, using a gas-phase and grain-surface chemical reaction network. We derive spatial distributions of molecular abundances and column densities in the molecular cloud core harboring the first core. We find that the total gas and ice abundances of many species in a cold era (10 K) remain unaltered until the temperature reaches ~500 K. The gas abundances in the warm envelope and the outer layer of the first core (T <~ 500 K) are mainly determined via the sublimation of ice-mantle species. Above 500 K, the abundant molecules, such as H2CO, start to be destroyed, and simple molecules, such as CO, H2O, and N2, are reformed. On the other hand, some molecules are effectively formed at high temperature; carbon chains, such as C2H2 and cyanopolyynes, are formed at temperatures >700 K. We also find that large organic molecules, such as CH3OH and HCOOCH3, are associated with the first core (r <~ 10 AU). Although the abundances of these molecules in the first core stage are comparable to or less than in the protostellar stage (hot corino), reflecting the lower luminosity of the central object, their column densities in our model are comparable to the observed values toward the prototypical hot corino, IRAS 16293-2422. We propose that these large organic molecules can be good tracers of the first cores.

  20. MAGIC-type polymer gel for three-dimensional dosimetry: intensity-modulated radiation therapy verification.

    PubMed

    Gustavsson, Helen; Karlsson, Anna; Bäck, Sven A J; Olsson, Lars E; Haraldsson, Pia; Engström, Per; Nyström, Håkan

    2003-06-01

    A new type of polymer gel dosimeter, which responds well to absorbed dose even when manufactured in the presence of normal levels of oxygen, was recently described by Fong et al. [Phys. Med. Biol. 46, 3105-3113 (2001)] and referred to by the acronym MAGIC. The aim of this study was to investigate the feasibility of using this new type of gel for intensity-modulated radiation therapy (IMRT) verification. Gel manufacturing was carried out in room atmosphere under normal levels of oxygen. IMRT inverse treatment planning was performed using the Helios software. The gel was irradiated using a linear accelerator equipped with a dynamic multileaf collimator, and intensity modulation was achieved using sliding window technique. The response to absorbed dose was evaluated using magnetic resonance imaging. Measured and calculated dose distributions were compared with regard to in-plane isodoses and dose volume histograms. In addition, the spatial and dosimetric accuracy was evaluated using the gamma formalism. Good agreement between calculated and measured data was obtained. In the isocenter plane, the 70% and 90% isodoses acquired using the different methods are mostly within 2 mm, with up to 3 mm disagreement at isolated points. For the planning target volume (PTV), the calculated mean relative dose was 96.8 +/- 2.5% (1 SD) and the measured relative mean dose was 98.6 +/- 2.2%. Corresponding data for an organ at risk was 34.4 +/- 0.9% and 32.7 +/- 0.7%, respectively. The gamma criterion (3 mm spatial/3% dose deviation) was fulfilled for 94% of the pixels in the target region. Discrepancies were found in hot spots the upper and lower parts of the PTV, where the measured dose was up to 11% higher than calculated. This was attributed to sub optimal scatter kernels used in the treatment planning system dose calculations. Our results indicate great potential for IMRT verification using MAGIC-type polymer gel. PMID:12852552

  1. CHEMISTRY IN THE FIRST HYDROSTATIC CORE STAGE BY ADOPTING THREE-DIMENSIONAL RADIATION HYDRODYNAMIC SIMULATIONS

    SciTech Connect

    Furuya, Kenji; Aikawa, Yuri; Tomida, Kengo; Tomisaka, Kohji; Matsumoto, Tomoaki; Saigo, Kazuya; Hersant, Franck; Wakelam, Valentine

    2012-10-20

    We investigate molecular evolution from a molecular cloud core to a first hydrostatic core in three spatial dimensions. We perform a radiation hydrodynamic simulation in order to trace fluid parcels, in which molecular evolution is investigated, using a gas-phase and grain-surface chemical reaction network. We derive spatial distributions of molecular abundances and column densities in the molecular cloud core harboring the first core. We find that the total gas and ice abundances of many species in a cold era (10 K) remain unaltered until the temperature reaches {approx}500 K. The gas abundances in the warm envelope and the outer layer of the first core (T {approx}< 500 K) are mainly determined via the sublimation of ice-mantle species. Above 500 K, the abundant molecules, such as H{sub 2}CO, start to be destroyed, and simple molecules, such as CO, H{sub 2}O, and N{sub 2}, are reformed. On the other hand, some molecules are effectively formed at high temperature; carbon chains, such as C{sub 2}H{sub 2} and cyanopolyynes, are formed at temperatures >700 K. We also find that large organic molecules, such as CH{sub 3}OH and HCOOCH{sub 3}, are associated with the first core (r {approx}< 10 AU). Although the abundances of these molecules in the first core stage are comparable to or less than in the protostellar stage (hot corino), reflecting the lower luminosity of the central object, their column densities in our model are comparable to the observed values toward the prototypical hot corino, IRAS 16293-2422. We propose that these large organic molecules can be good tracers of the first cores.

  2. Membrane Signaling Induced by High Doses of Ionizing Radiation in the Endothelial Compartment. Relevance in Radiation Toxicity

    PubMed Central

    Corre, Isabelle; Guillonneau, Maëva; Paris, François

    2013-01-01

    Tumor areas can now be very precisely delimited thanks to technical progress in imaging and ballistics. This has also led to the development of novel radiotherapy protocols, delivering higher doses of ionizing radiation directly to cancer cells. Despite this, radiation toxicity in healthy tissue remains a major issue, particularly with dose-escalation in these new protocols. Acute and late tissue damage following irradiation have both been linked to the endothelium irrigating normal tissues. The molecular mechanisms involved in the endothelial response to high doses of radiation are associated with signaling from the plasma membrane, mainly via the acid sphingomyelinase/ceramide pathway. This review describes this signaling pathway and discusses the relevance of targeting endothelial signaling to protect healthy tissues from the deleterious effects of high doses of radiation. PMID:24252908

  3. Conservative surgery for low rectal carcinoma after high-dose radiation. Functional and oncologic results.

    PubMed Central

    Rouanet, P; Fabre, J M; Dubois, J B; Dravet, F; Saint Aubert, B; Pradel, J; Ychou, M; Solassol, C; Pujol, H

    1995-01-01

    OBJECTIVE: Using a prospective, nonrandomized study, the authors evaluated the morbidity and functional and oncologic results of conservative surgery for cancer of the lower third of the rectum after high-dose radiation. SUMMARY BACKGROUND DATA: Colo-anal anastomosis has made sphincter conservation for low rectal carcinoma technically feasible. The limits to conservative surgery currently are oncologic rather than technical. Adjuvant radiotherapy has proven its benefit in terms of regional control, with a dose relationship. METHODS: Since June 1990, 27 patients with distal rectal adenocarcinoma were treated by preoperative radiotherapy (40 + 20 Gy delivered with three fields) and curative surgery. The mean distance from the anal verge was 47 mm (27-57 mm), and none of the tumors were fixed (15 T2, 12 T3). RESULTS: Mortality and morbidity were not increased by high-dose preoperative radiation. Twenty-one patients underwent conservative surgery (78%-17 total proctectomies and colo-anal anastomoses, 4 trans-anal resections). After colo-anal anastomosis, all patients with colonic pouch had good results; two patients had moderate results and one patient had poor results after straight colo-anal anastomosis. With a mean follow-up of 24 months, the authors noted 1 postoperative death, 2 disease-linked deaths, 1 controlled regional recurrence, 2 evolutive patients with pulmonary metastases, and 21 disease-free patients. CONCLUSIONS: These first results confirm the possibility of conservative surgery for low rectal carcinoma after high-dose radiation. A prospective, randomized trial could be induced to determine the real role of the 20 Gy boost on the sphincter-saving decision. PMID:7826163

  4. The Effect of High Dose Radioiodine Therapy on Formation of Radiation Retinopathy During Thyroid Cancer Treatment

    PubMed Central

    Kaçar Güveli, Tülay; Özkan, Sezer; Öner Tamam, Müge; Uyanık, Ercan; Ediz, Nurcan; Mülazımoğlu, Mehmet; Özpaçacı, Tevfik

    2014-01-01

    Objective: Non-thyroidal complication of high-dose radioiodine therapy for thyroid carcinoma might cause salivary and lacrimal gland dysfunction, which may be transient or permanent in a dose-dependent manner. However, radiation retinopathy complicating 131I therapy, has not been previously well characterized. The aim of this study was to evaluate the extent of retinal damage among patients who had received high doses of radioiodine treatment. Methods: Forty eyes of 20 patients (3 male, 17 female) who received 250-1000 mCi during 131I therapy and on ophthalmological follow up for a year after the last treatment were included in the study. Mean age of the study group was 50 years (range 25-70 years). In ophthalmologic examination, visual acuity was measured in order to determine visual loss. Intraocular pressure was measured in all the patients. Then lens examination was carried out with slit lamp biomicroscopy in order to investigate cataract or partial lens opacities. Fundus observation was carried out through the dilated pupil with slit lamp biomicroscopy using 90 D noncontact lens. Result: The best corrected visual aquity with Snellen chart was found as 1.0 in 36 eyes (90%) and between 0.6 and 0.9 (10%) in 4 eyes (10%). At the biomicroscopic fundus examination, retinal hemorrhage consistent with radiation retinopathy, microaneurysm, microinfarction, edema or exudation, vitreus hemorrhage, partial or total optical disc pallor indicating papillopathy in the optic disc were not observed in any of the eyes. Conclusion: This result indicates that there is not any significant correlation between repeated high-dose radioiodine therapy and radiation retinopathy in differentiated thyroid carcinomas. Even though there is not a significant restriction in use of higher doses of radioiodine therapy in differentiated thyroid carcinoma, more extensive studies are needed in order to obtain more accurate data on possible occurrence of retinopathy. PMID:25541931

  5. Effects of high dose intraperitoneal cytosine arabinoside on the radiation tolerance of the rat spinal cord

    SciTech Connect

    Menten, J.; Landuyt, W.; van der Kogel, A.J.; Ang, K.K.; van der Schueren, E.

    1989-07-01

    The effect of intraperitoneal high dose (9 g/kg) cytosine arabinoside (Ara-C) on the early delayed radiation response of the rat cervical spinal cord has been studied. When given 2 hrs before irradiation, systemically administered Ara-C significantly reduces the isoeffect doses for the induction of paralysis due to white matter necrosis by a factor of approximately 1.2 for both a single irradiation treatment and for a two fraction irradiation with 24 hr interval. No effect on the latency time to develop paralysis was recorded.

  6. Combined methotrexate and high-dose vincristine chemotherapy with radiation therapy for small cell bronchogenic carcinoma

    SciTech Connect

    Holoye, P.Y.; Libnoch, J.A.; Anderson, T.; Cox, J.D.; Byhardt, R.W.; Hoffmann, R.G.

    1985-04-01

    The addition of methotrexate to a previously described regimen of cyclophosphamide, Adriamycin (doxorubicin), and high-dose vincristine (VAC) was tested in 50 evaluable patients with small cell bronchogenic carcinoma. Prophylactic whole brain radiation therapy was given during the first chemotherapy course and consolidation radiation therapy was given to the mediastinum and primary site after achieving partial or complete remission. The addition of methotrexate did not improve the incidence of complete remission as compared to a previous regimen without it. The addition of radiation therapy improved the local control rate. The high-dose vincristine in this and a previous CAV study improved the incidence of complete remission in both limited and extensive disease presentation as compared with the authors previous experience and induced an acceptable and reversible neurotoxicity. Moderate dose consolidation radiotherapy to the lung primary and mediastinum was effective in improving local control. The distinction between limited and extensive disease was found to be vague, as 22% of the patients could be shifted from one group to the other depending on definition. The evaluation of the various staging procedures indicates that bone scan gave a small number of truly abnormal tests. Isotopic brain and liver-spleen scan could be duplicated by computerized axial tomography (CAT). CAT scan of abdomen disclosed unexpected extension to the retroperitoneal nodes and adrenals.

  7. Modelling the effects of plasmaspheric hiss and lightning-generated whistlers in three dimensional radiation belt models

    NASA Astrophysics Data System (ADS)

    Glauert, Sarah; Horne, Richard; Meredith, Nigel

    2014-05-01

    In the Earth's radiation belts the relativistic electron flux is highly variable and can change by orders of magnitude in a few hours. Since these energetic electrons can damage satellites, understanding the causes of this variation is important. Three dimensional diffusion models of this high-energy electron population solve a Fokker-Planck equation for the phase-space density and can include the effects of radial transport, wave-particle interactions and collisions. Various different wave-particle interactions can be included in the models. We present results from the BAS Radiation Belt Model using new diffusion coefficients for plasmaspheric hiss and lightning-generated whistlers. These diffusion coefficients, based on observations of the wave properties, depend on L, energy, pitch-angle and geomagnetic activity. We show that losses due to plasmaspheric hiss depend critically on the wave-normal angle distribution and that a model where the peak of the distribution depends on latitude best reproduces the observed decay rates. Higher frequency waves (˜ 1-2 kHz) only make a significant contribution to losses for L∗ < 3 and the highest frequencies (2-5 kHz), representing lightning-generated whistlers, have a limited effect on relativistic electrons for L∗ > 2.

  8. High-dose MVCT image guidance for stereotactic body radiation therapy

    SciTech Connect

    Westerly, David C.; Schefter, Tracey E.; Kavanagh, Brian D.; Chao, Edward; Lucas, Dan; Flynn, Ryan T.; Miften, Moyed

    2012-08-15

    Purpose: Stereotactic body radiation therapy (SBRT) is a potent treatment for early stage primary and limited metastatic disease. Accurate tumor localization is essential to administer SBRT safely and effectively. Tomotherapy combines helical IMRT with onboard megavoltage CT (MVCT) imaging and is well suited for SBRT; however, MVCT results in reduced soft tissue contrast and increased image noise compared with kilovoltage CT. The goal of this work was to investigate the use of increased imaging doses on a clinical tomotherapy machine to improve image quality for SBRT image guidance. Methods: Two nonstandard, high-dose imaging modes were created on a tomotherapy machine by increasing the linear accelerator (LINAC) pulse rate from the nominal setting of 80 Hz, to 160 Hz and 300 Hz, respectively. Weighted CT dose indexes (wCTDIs) were measured for the standard, medium, and high-dose modes in a 30 cm solid water phantom using a calibrated A1SL ion chamber. Image quality was assessed from scans of a customized image quality phantom. Metrics evaluated include: contrast-to-noise ratios (CNRs), high-contrast spatial resolution, image uniformity, and percent image noise. In addition, two patients receiving SBRT were localized using high-dose MVCT scans. Raw detector data collected after each scan were used to reconstruct standard-dose images for comparison. Results: MVCT scans acquired using a pitch of 1.0 resulted in wCTDI values of 2.2, 4.7, and 8.5 cGy for the standard, medium, and high-dose modes respectively. CNR values for both low and high-contrast materials were found to increase with the square root of dose. Axial high-contrast spatial resolution was comparable for all imaging modes at 0.5 lp/mm. Image uniformity was improved and percent noise decreased as the imaging dose increased. Similar improvements in image quality were observed in patient images, with decreases in image noise being the most notable. Conclusions: High-dose imaging modes are made possible on a

  9. Radiation-induced liver disease in three-dimensional conformal radiation therapy for primary liver carcinoma: The risk factors and hepatic radiation tolerance

    SciTech Connect

    Liang Shixiong; Zhu Xiaodong; Xu Zhiyong

    2006-06-01

    Purpose: To identify risk factors relevant to radiation-induced liver disease (RILD) and to determine the hepatic tolerance to radiation. Methods and Materials: The data of 109 primary liver carcinomas (PLC) treated with hypofractionated three-dimensional conformal radiation therapy (3D-CRT) were analyzed. Seventeen patients were diagnosed with RILD and 13 of 17 died of it. Results: The risk factors for RILD were late T stage, large gross tumor volume, presence of portal vein thrombosis, association with Child-Pugh Grade B cirrhosis, and acute hepatic toxicity. Multivariate analyses demonstrated that the severity of hepatic cirrhosis was a unique independent predictor. For Child-Pugh Grade A patients, the hepatic radiation tolerance was as follows: (1) Mean dose to normal liver (MDTNL) of 23 Gy was tolerable. (2) For cumulative dose-volume histogram, the tolerable volume percentages would be less than: V{sub 5} of 86%, V{sub 1} of 68%, V{sub 15} of 59%, V{sub 2} of 49%, V{sub 25} of 35%, V{sub 3} of 28%, V{sub 35} of 25%, and V{sub 4} of 20%. (3) Tolerable MDTNL could be estimated by MDTNL (Gy) = -1.686 + 0.023 * normal liver volume (cm{sup 3}). Conclusion: The predominant risk factor for RILD was the severity of hepatic cirrhosis. The hepatic tolerance to radiation could be estimated by dosimetric parameters.

  10. Implementation and modification of a three-dimensional radiation stress formulation for surf zone and rip-current applications

    USGS Publications Warehouse

    Kumar, N.; Voulgaris, G.; Warner, J.C.

    2011-01-01

    Regional Ocean Modeling System (ROMS v 3.0), a three-dimensional numerical ocean model, was previously enhanced for shallow water applications by including wave-induced radiation stress forcing provided through coupling to wave propagation models (SWAN, REF/DIF). This enhancement made it suitable for surf zone applications as demonstrated using examples of obliquely incident waves on a planar beach and rip current formation in longshore bar trough morphology (Haas and Warner, 2009). In this contribution, we present an update to the coupled model which implements a wave roller model and also a modified method of the radiation stress term based on Mellor (2008, 2011a,b,in press) that includes a vertical distribution which better simulates non-conservative (i.e., wave breaking) processes and appears to be more appropriate for sigma coordinates in very shallow waters where wave breaking conditions dominate. The improvements of the modified model are shown through simulations of several cases that include: (a) obliquely incident spectral waves on a planar beach; (b) obliquely incident spectral waves on a natural barred beach (DUCK'94 experiment); (c) alongshore variable offshore wave forcing on a planar beach; (d) alongshore varying bathymetry with constant offshore wave forcing; and (e) nearshore barred morphology with rip-channels. Quantitative and qualitative comparisons to previous analytical, numerical, laboratory studies and field measurements show that the modified model replicates surf zone recirculation patterns (onshore drift at the surface and undertow at the bottom) more accurately than previous formulations based on radiation stress (Haas and Warner, 2009). The results of the model and test cases are further explored for identifying the forces operating in rip current development and the potential implication for sediment transport and rip channel development. Also, model analysis showed that rip current strength is higher when waves approach at angles of 5

  11. High-resolution three-dimensional visualization of the rat spinal cord microvasculature by synchrotron radiation micro-CT

    SciTech Connect

    Hu, Jianzhong; Cao, Yong; Wu, Tianding; Li, Dongzhe; Lu, Hongbin

    2014-10-15

    Purpose: Understanding the three-dimensional (3D) morphology of the spinal cord microvasculature has been limited by the lack of an effective high-resolution imaging technique. In this study, synchrotron radiation microcomputed tomography (SRµCT), a novel imaging technique based on absorption imaging, was evaluated with regard to the detection of the 3D morphology of the rat spinal cord microvasculature. Methods: Ten Sprague-Dawley rats were used in this ex vivo study. After contrast agent perfusion, their spinal cords were isolated and scanned using conventional x-rays, conventional micro-CT (CµCT), and SRµCT. Results: Based on contrast agent perfusion, the microvasculature of the rat spinal cord was clearly visualized for the first time ex vivo in 3D by means of SRµCT scanning. Compared to conventional imaging techniques, SRµCT achieved higher resolution 3D vascular imaging, with the smallest vessel that could be distinguished approximately 7.4 μm in diameter. Additionally, a 3D pseudocolored image of the spinal cord microvasculature was generated in a single session of SRµCT imaging, which was conducive to detailed observation of the vessel morphology. Conclusions: The results of this study indicated that SRµCT scanning could provide higher resolution images of the vascular network of the spinal cord. This modality also has the potential to serve as a powerful imaging tool for the investigation of morphology changes in the 3D angioarchitecture of the neurovasculature in preclinical research.

  12. Three-dimensional Effects and Shortwave Cloud Radiative Forcing Associated with Shallow Cumuli Over Central North America

    SciTech Connect

    Berg, Larry K.; Kassianov, Evgueni I.; Long, Charles N.; Mills, Jr., David

    2009-09-30

    Shallow cumuli are ubiquitous over large areas of the globe, including both the interior of continents and the trade wind regions over the oceans. Measurements made at the Atmospheric Radiation Measurement (ARM) Climate Research Facility, located in central North America, provide a unique long-term data set that can be used to investigate the influence that these clouds have on the shortwave surface energy budget at a continental location. Using data collected for the summers of 2000 through 2007, inclusive, over 900 hours with fair-weather cumuli were identified using data from a Total Sky Imager, cloud-radar and lidar. Data from a suite of surface radiometers was used to determine the shortwave forcing. This analysis estimates the three-dimensional effects of shallow cumuli by examining the occurrences of both positive and negative shortwave forcing. We show that the average surface shortwave forcing is approximately -45.5 W m-2. When the data are adjusted to account for periods without shallow clouds, the shortwave forcing over the entire summer (defined as May through August) are reduced in magnitude, with forcings of -2.1 W m-2.

  13. Three-dimensional effects and shortwave cloud radiative forcing associated with shallow cumuli over the central North America

    NASA Astrophysics Data System (ADS)

    Berg, Larry K.; Mills, David, Jr.; Kassianov, Evgueni I.; Long, Charles N.

    2009-09-01

    Shallow cumuli are ubiquitous over large areas of the globe, including both the interior of continents and the trade wind regions over the oceans. Measurements made at the Atmospheric Radiation Measurement (ARM) Climate Research Facility, located in central North America, provide a unique long-term data set that can be used to investigate the influence that these clouds have on the shortwave surface energy budget at a continental location. Using data collected for the summers of 2000 through 2007, inclusive, over 900 hours with fair-weather cumuli were identified using data from a Total Sky Imager, cloud-radar and lidar. Data from a suite of surface radiometers was used to determine the shortwave forcing. This analysis estimates the three-dimensional effects of shallow cumuli by examining the occurrences of both positive and negative shortwave forcing. We show that the average surface shortwave forcing is approximately -45.5 W m-2. When the data are adjusted to account for periods without shallow clouds, the shortwave forcing over the entire summer (defined as May through August) are reduced in magnitude, with forcings of -2.1 W m-2.

  14. RADIATIVE AND MOMENTUM-BASED MECHANICAL ACTIVE GALACTIC NUCLEUS FEEDBACK IN A THREE-DIMENSIONAL GALAXY EVOLUTION CODE

    SciTech Connect

    Choi, Ena; Ostriker, Jeremiah P.; Naab, Thorsten; Johansson, Peter H.

    2012-08-01

    We study the growth of black holes (BHs) in galaxies using three-dimensional smoothed particle hydrodynamic simulations with new implementations of the momentum mechanical feedback, and restriction of accreted elements to those that are gravitationally bound to the BH. We also include the feedback from the X-ray radiation emitted by the BH, which heats the surrounding gas in the host galaxies, and adds radial momentum to the fluid. We perform simulations of isolated galaxies and merging galaxies and test various feedback models with the new treatment of the Bondi radius criterion. We find that overall the BH growth is similar to what has been obtained by earlier works using the Springel, Di Matteo, and Hernquist algorithms. However, the outflowing wind velocities and mechanical energy emitted by winds are considerably higher (v{sub w} {approx} 1000-3000 km s{sup -1}) compared to the standard thermal feedback model (v{sub w} {approx} 50-100 km s{sup -1}). While the thermal feedback model emits only 0.1% of BH released energy in winds, the momentum feedback model emits more than 30% of the total energy released by the BH in winds. In the momentum feedback model, the degree of fluctuation in both radiant and wind output is considerably larger than in standard treatments. We check that the new model of BH mass accretion agrees with analytic results for the standard Bondi problem.

  15. Three-dimensional evaluation of the compression and recovery behavior in a flexible graphite sheet by synchrotron radiation microtomography

    SciTech Connect

    Kobayashi, M.; Toda, H.; Takeuchi, A.; Uesugi, K.; Suzuki, Y.

    2012-07-15

    The compression and unloading behavior of flexible graphite sheets was investigated using synchrotron radiation microtomography with 1 {mu}m voxel size. The recovery ratio of the flexible graphite sheet was measured accurately by in-situ observation. The three-dimensional strain distribution in the interior of the specimen was obtained using the microstructural tracking method. The inner strain distribution with micrometer scale indicated inhomogeneous deformation. The microstructural tracking analysis revealed that deformation units exist in the flexible graphite sheet. The units seem to deform, affecting the neighboring units with each other. The units had a similar size and shape with compacted exfoliated graphite worms that constitute the flexible graphite sheet. Microscopic deformations during compression and unloading are surely affected by the microstructure of the sheet. Highlights: Black-Right-Pointing-Pointer The compression and recovery behavior was investigated using microtomography. Black-Right-Pointing-Pointer The tracking analysis revealed that deformation units exist in the specimen. Black-Right-Pointing-Pointer Each unit deforms in relation to the neighboring unit.

  16. Effect of nonlinear three-dimensional optimized reconstruction algorithm filter on image quality and radiation dose: Validation on phantoms

    SciTech Connect

    Bai Mei; Chen Jiuhong; Raupach, Rainer; Suess, Christoph; Tao Ying; Peng Mingchen

    2009-01-15

    A new technique called the nonlinear three-dimensional optimized reconstruction algorithm filter (3D ORA filter) is currently used to improve CT image quality and reduce radiation dose. This technical note describes the comparison of image noise, slice sensitivity profile (SSP), contrast-to-noise ratio, and modulation transfer function (MTF) on phantom images processed with and without the 3D ORA filter, and the effect of the 3D ORA filter on CT images at a reduced dose. For CT head scans the noise reduction was up to 54% with typical bone reconstruction algorithms (H70) and a 0.6 mm slice thickness; for liver CT scans the noise reduction was up to 30% with typical high-resolution reconstruction algorithms (B70) and a 0.6 mm slice thickness. MTF and SSP did not change significantly with the application of 3D ORA filtering (P>0.05), whereas noise was reduced (P<0.05). The low contrast detectability and MTF of images obtained at a reduced dose and filtered by the 3D ORA were equivalent to those of standard dose CT images; there was no significant difference in image noise of scans taken at a reduced dose, filtered using 3D ORA and standard dose CT (P>0.05). The 3D ORA filter shows good potential for reducing image noise without affecting image quality attributes such as sharpness. By applying this approach, the same image quality can be achieved whilst gaining a marked dose reduction.

  17. Three Dimensional Fusion CT Decreases Radiation Exposure, Procedure Time and Contrast Use during Fenestrated Endovascular Aortic Repair

    PubMed Central

    McNally, Michael M.; Scali, Salvatore T.; Feezor, Robert J.; Neal, Daniel; Huber, Thomas S.; Beck, Adam W.

    2014-01-01

    Objectives Endovascular surgery has revolutionized the treatment of aortic aneurysms; however these improvements have come at the cost of increased radiation and contrast exposure, particularly for more complex procedures. Three dimensional (3D) fusion computed tomographic (CT) imaging is a new technology that may facilitate these repairs. The purpose of this analysis was to determine the impact of utilizing intraoperative 3D fusion CT on performance of fenestrated endovascular aortic repair. Methods A review of our institutional database was performed to identify patients undergoing fenestrated/branched endovascular aortic repair (FEVAR). Subjects treated using 3D fusion CT were compared to patients treated in the immediate 12-month period prior to implementation of this technology when procedures were performed in a standard hybrid operating room without CT fusion capabilities. Primary endpoints included patient radiation exposure (air kerma area product: milliGray; mGy*cm2), fluoroscopy time (minutes; min), contrast usage (mL) and procedure time (min). Patients were grouped by number of aortic graft fenestrations revascularized with a stentgraft and operative outcomes were compared. Results A total of 72 patients (N = 41 before vs. N = 31 after 3D fusion CT implementation) underwent FEVAR from September 2012 through March 2014. For 2-vessel fenestrated endografts, there was a significant decrease in radiation exposure (3400±1900 vs. 1380±520 mGy*cm2; P=.001), fluoroscopy time (63±29 vs. 41±11min; P=.02), and contrast usage (69±16 vs. 26±8 mL; P=.0002) with intraoperative 3D fusion CT. Similarly, for combined 3 and 4-vessel FEVAR, significantly decreased radiation exposure (5400±2225 vs. 2700±1400 mGy*cm2; P<.0001), fluoroscopy time (89±36 vs 6±21min; P=.02), contrast usage (90±25 vs. 39±17mL; P<.0001), as well as procedure time (330±100 vs. 230±50min; P=.002) was noted. Estimated blood loss was significantly less (P<.0001) and length of stay had a

  18. Airborne observations and simulations of three-dimensional radiative interactions between Arctic boundary layer clouds and ice floes

    NASA Astrophysics Data System (ADS)

    Schäfer, M.; Bierwirth, E.; Ehrlich, A.; Jäkel, E.; Wendisch, M.

    2015-07-01

    Based on airborne spectral imaging observations, three-dimensional (3-D) radiative effects between Arctic boundary layer clouds and highly variable Arctic surfaces were identified and quantified. A method is presented to discriminate between sea ice and open water under cloudy conditions based on airborne nadir reflectivity γλ measurements in the visible spectral range. In cloudy cases the transition of γλ from open water to sea ice is not instantaneous but horizontally smoothed. In general, clouds reduce γλ above bright surfaces in the vicinity of open water, while γλ above open sea is enhanced. With the help of observations and 3-D radiative transfer simulations, this effect was quantified to range between 0 and 2200 m distance to the sea ice edge (for a dark-ocean albedo of αwater = 0.042 and a sea-ice albedo of αice = 0.91 at 645 nm wavelength). The affected distance Δ L was found to depend on both cloud and sea ice properties. For a low-level cloud at 0-200 m altitude, as observed during the Arctic field campaign VERtical Distribution of Ice in Arctic clouds (VERDI) in 2012, an increase in the cloud optical thickness τ from 1 to 10 leads to a decrease in Δ L from 600 to 250 m. An increase in the cloud base altitude or cloud geometrical thickness results in an increase in Δ L; for τ = 1/10 Δ L = 2200 m/1250 m in case of a cloud at 500-1000 m altitude. To quantify the effect for different shapes and sizes of ice floes, radiative transfer simulations were performed with various albedo fields (infinitely long straight ice edge, circular ice floes, squares, realistic ice floe field). The simulations show that Δ L increases with increasing radius of the ice floe and reaches maximum values for ice floes with radii larger than 6 km (500-1000 m cloud altitude), which matches the results found for an infinitely long, straight ice edge. Furthermore, the influence of these 3-D radiative effects on the retrieved cloud optical properties was investigated

  19. Pilot Study on Image Quality and Radiation Dose of CT Colonography with Adaptive Iterative Dose Reduction Three-Dimensional

    PubMed Central

    Shen, Hesong; Liang, Dan; Luo, Mingyue; Duan, Chaijie; Cai, Wenli; Zhu, Shanshan; Qiu, Jianping; Li, Wenru

    2015-01-01

    Objective To investigate image quality and radiation dose of CT colonography (CTC) with adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Ten segments of porcine colon phantom were collected, and 30 pedunculate polyps with diameters ranging from 1 to 15 mm were simulated on each segment. Image data were acquired with tube voltage of 120 kVp, and current doses of 10 mAs, 20 mAs, 30 mAs, 40 mAs, 50 mAs, respectively. CTC images were reconstructed using filtered back projection (FBP) and AIDR3D. Two radiologists blindly evaluated image quality. Quantitative evaluation of image quality included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative image quality was evaluated with a five-score scale. Radiation dose was calculated based on dose-length product. Ten volunteers were examined supine 50 mAs with FBP and prone 20 mAs with AIDR3D, and image qualities were assessed. Paired t test was performed for statistical analysis. Results For 20 mAs with AIDR3D and 50 mAs with FBP, image noise, SNRs and CNRs were (16.4 ± 1.6) HU vs. (16.8 ± 2.6) HU, 1.9 ± 0.2 vs. 1.9 ± 0.4, and 62.3 ± 6.8 vs. 62.0 ± 6.2, respectively; qualitative image quality scores were 4.1 and 4.3, respectively; their differences were all not statistically significant. Compared with 50 mAs with FBP, radiation dose (1.62 mSv) of 20 mAs with AIDR3D was decreased by 60.0%. There was no statistically significant difference in image noise, SNRs, CNRs and qualitative image quality scores between prone 20 mAs with AIDR3D and supine 50 mAs with FBP in 10 volunteers, the former reduced radiation dose by 61.1%. Conclusion Image quality of CTC using 20 mAs with AIDR3D could be comparable to standard 50 mAs with FBP, radiation dose of the former reduced by about 60.0% and was only 1.62 mSv. PMID:25635839

  20. Radiation tolerant nanocrystalline ZrN films under high dose heavy-ion irradiations

    SciTech Connect

    Jiao, L.; Wang, H.; Yu, K. Y.; Chen, D.; Jacob, C.; Shao, L.; Zhang, X.

    2015-04-14

    ZrN, a refractory ceramic material, finds many potential applications in advanced nuclear reactors. However, the grain size dependent radiation response in nanocrystalline (nc) ZrN under high dose heavy ion irradiation has not yet been studied to date. Here, we compare the radiation response of nc-ZrN films (with a respective average grain size of ∼9 and 31 nm) to Fe{sup 2+} ion irradiations up to a damage level of 10 displacements-per-atom (dpa). The ZrN film with the average grain size of 9 nm shows prominently enhanced radiation tolerance as evidenced by suppressed grain growth, alleviated radiation softening, as well as reduced variation in electrical resistivity. In contrast, ZrN with the larger average grain size of 31 nm shows prominent radiation softening and resistivity increase, attributed to the high density of defect cluster formed inside the grains. The influence of grain boundaries on enhanced irradiation tolerance in nc-ZrN is discussed.

  1. Three-dimensional radiation-hydrodynamics calculations of the envelopes of young planets embedded in protoplanetary disks

    SciTech Connect

    D'Angelo, Gennaro; Bodenheimer, Peter E-mail: peter@ucolick.org

    2013-11-20

    We perform global three-dimensional (3D) radiation-hydrodynamics calculations of the envelopes surrounding young planetary cores of 5, 10, and 15 Earth masses, located in a protoplanetary disk at 5 and 10 AU from a solar-mass star. We apply a nested-grid technique to resolve the thermodynamics of the disk at the orbital-radius length scale and that of the envelope at the core-radius length scale. The gas is modeled as a solar mixture of molecular and atomic hydrogen, helium, and their ions. The equation of state accounts for both gas and radiation, and gas energy includes contributions from rotational and vibrational states of molecular hydrogen and from ionization of atomic species. Dust opacities are computed from first principles, applying the full Mie theory. One-dimensional (1D) calculations of planet formation are used to supplement the 3D calculations by providing energy deposition rates in the envelope due to solids accretion. We compare 1D and 3D envelopes and find that masses and gas accretion rates agree within factors of 2, and so do envelope temperatures. The trajectories of passive tracers are used to define the size of 3D envelopes, resulting in radii much smaller than the Hill radius and smaller than the Bondi radius. The moments of inertia and angular momentum of the envelopes are determined and the rotation rates are derived from the rigid-body approximation, resulting in slow bulk rotation. We find that the polar flattening is ≲ 0.05. The dynamics of the accretion flow are examined by tracking the motion of tracers that move into the envelope. The anisotropy of this flow is characterized in terms of both its origin and impact site at the envelope surface. Gas merges with the envelope preferentially at mid- to high latitudes.

  2. Formation of Overheated Regions and Truncated Disks around Black Holes: Three-dimensional General Relativistic Radiation-magnetohydrodynamics Simulations

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroyuki R.; Ohsuga, Ken; Kawashima, Tomohisa; Sekiguchi, Yuichiro

    2016-07-01

    Using three-dimensional general relativistic radiation-magnetohydrodynamics simulations of accretion flows around stellar mass black holes, we report that the relatively cold disk (≳ {10}7 {{K}}) is truncated near the black hole. Hot and less dense regions, of which the gas temperature is ≳ {10}9 {{K}} and more than 10 times higher than the radiation temperature (overheated regions), appear within the truncation radius. The overheated regions also appear above as well as below the disk, sandwiching the cold disk, leading to the effective Compton upscattering. The truncation radius is ˜ 30{r}{{g}} for \\dot{M}˜ {L}{{Edd}}/{c}2, where {r}{{g}},\\dot{M},{L}{Edd},c are the gravitational radius, mass accretion rate, Eddington luminosity, and light speed, respectively. Our results are consistent with observations of a very high state, whereby the truncated disk is thought to be embedded in the hot rarefied regions. The truncation radius shifts inward to ˜ 10{r}{{g}} with increasing mass accretion rate \\dot{M}˜ 100{L}{{Edd}}/{c}2, which is very close to an innermost stable circular orbit. This model corresponds to the slim disk state observed in ultraluminous X-ray sources. Although the overheated regions shrink if the Compton cooling effectively reduces the gas temperature, the sandwich structure does not disappear at the range of \\dot{M}≲ 100{L}{{Edd}}/{c}2. Our simulations also reveal that the gas temperature in the overheated regions depends on black hole spin, which would be due to efficient energy transport from black hole to disks through the Poynting flux, resulting in gas heating.

  3. Formation of Overheated Regions and Truncated Disks around Black Holes: Three-dimensional General Relativistic Radiation-magnetohydrodynamics Simulations

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroyuki R.; Ohsuga, Ken; Kawashima, Tomohisa; Sekiguchi, Yuichiro

    2016-07-01

    Using three-dimensional general relativistic radiation-magnetohydrodynamics simulations of accretion flows around stellar mass black holes, we report that the relatively cold disk (≳ {10}7 {{K}}) is truncated near the black hole. Hot and less dense regions, of which the gas temperature is ≳ {10}9 {{K}} and more than 10 times higher than the radiation temperature (overheated regions), appear within the truncation radius. The overheated regions also appear above as well as below the disk, sandwiching the cold disk, leading to the effective Compton upscattering. The truncation radius is ∼ 30{r}{{g}} for \\dot{M}∼ {L}{{Edd}}/{c}2, where {r}{{g}},\\dot{M},{L}{Edd},c are the gravitational radius, mass accretion rate, Eddington luminosity, and light speed, respectively. Our results are consistent with observations of a very high state, whereby the truncated disk is thought to be embedded in the hot rarefied regions. The truncation radius shifts inward to ∼ 10{r}{{g}} with increasing mass accretion rate \\dot{M}∼ 100{L}{{Edd}}/{c}2, which is very close to an innermost stable circular orbit. This model corresponds to the slim disk state observed in ultraluminous X-ray sources. Although the overheated regions shrink if the Compton cooling effectively reduces the gas temperature, the sandwich structure does not disappear at the range of \\dot{M}≲ 100{L}{{Edd}}/{c}2. Our simulations also reveal that the gas temperature in the overheated regions depends on black hole spin, which would be due to efficient energy transport from black hole to disks through the Poynting flux, resulting in gas heating.

  4. Comparison of three dimensional conformal radiation therapy, intensity modulated radiation therapy and volumetric modulated arc therapy for low radiation exposure of normal tissue in patients with prostate cancer.

    PubMed

    Cakir, Aydin; Akgun, Zuleyha; Fayda, Merdan; Agaoglu, Fulya

    2015-01-01

    Radiotherapy has an important role in the treatment of prostate cancer. Three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques are all applied for this purpose. However, the risk of secondary radiation-induced bladder cancer is significantly elevated in irradiated patients compared surgery-only or watchful waiting groups. There are also reports of risk of secondary cancer with low doses to normal tissues. This study was designed to compare received volumes of low doses among 3D-CRT, IMRT and VMAT techniques for prostate patients. Ten prostate cancer patients were selected retrospectively for this planning study. Treatment plans were generated using 3D-CRT, IMRT and VMAT techniques. Conformity index (CI), homogenity index (HI), receiving 5 Gy of the volume (V5%), receiving 2 Gy of the volume (V2%), receiving 1 Gy of the volume (V1%) and monitor units (MUs) were compared. This study confirms that VMAT has slightly better CI while thev olume of low doses was higher. VMAT had lower MUs than IMRT. 3D-CRT had the lowest MU, CI and HI. If target coverage and normal tissue sparing are comparable between different treatment techniques, the risk of second malignancy should be a important factor in the selection of treatment. PMID:25921146

  5. Phase I Study of Concurrent High-Dose Three-Dimensional Conformal Radiotherapy With Chemotherapy Using Cisplatin and Vinorelbine for Unresectable Stage III Non-Small-Cell Lung Cancer

    SciTech Connect

    Sekine, Ikuo; Sumi, Minako; Ito, Yoshinori; Horinouchi, Hidehito; Nokihara, Hiroshi; Yamamoto, Noboru; Kunitoh, Hideo; Ohe, Yuichiro; Kubota, Kaoru; Tamura, Tomohide

    2012-02-01

    Purpose: To determine the maximum tolerated dose in concurrent three-dimensional conformal radiotherapy (3D-CRT) with chemotherapy for unresectable Stage III non-small-cell lung cancer (NSCLC). Patients and Methods: Eligible patients with unresectable Stage III NSCLC, age {>=}20 years, performance status 0-1, percent of volume of normal lung receiving 20 GY or more (V{sub 20}) {<=}30% received three to four cycles of cisplatin (80 mg/m{sup 2} Day 1) and vinorelbine (20 mg/m{sup 2} Days 1 and 8) repeated every 4 weeks. The doses of 3D-CRT were 66 Gy, 72 Gy, and 78 Gy at dose levels 1 to 3, respectively. Results: Of the 17, 16, and 24 patients assessed for eligibility, 13 (76%), 12 (75%), and 6 (25%) were enrolled at dose levels 1 to 3, respectively. The main reasons for exclusion were V{sub 20} >30% (n = 10) and overdose to the esophagus (n = 8) and brachial plexus (n = 2). There were 26 men and 5 women, with a median age of 60 years (range, 41-75). The full planned dose of radiotherapy could be administered to all the patients. Grade 3-4 neutropenia and febrile neutropenia were noted in 24 (77%) and 5 (16%) of the 31 patients, respectively. Grade 4 infection, Grade 3 esophagitis, and Grade 3 pulmonary toxicity were noted in 1 patient, 2 patients, and 1 patient, respectively. The dose-limiting toxicity was noted in 17% of the patients at each dose level. The median survival and 3-year and 4-year survival rates were 41.9 months, 72.3%, and 49.2%, respectively. Conclusions: 72 Gy was the maximum dose that could be achieved in most patients, given the predetermined normal tissue constraints.

  6. External beam radiation therapy followed by high-dose-rate brachytherapy for inoperable superficial esophageal carcinoma

    SciTech Connect

    Pasquier, David . E-mail: d-pasquier@o-lambret.fr; Mirabel, Xavier; Adenis, Antoine; Rezvoy, Nicolas; Hecquet, Genevieve; Fournier, Charles; Coche-Dequeant, Bernard; Prevost, Bernard; Castelain, Bernard; Lartigau, Eric

    2006-08-01

    Purpose: The aim of this study was to retrospectively evaluate the feasibility, efficacy, and tolerance of external beam radiotherapy followed by high-dose-rate brachytherapy in inoperable patients with superficial esophageal cancer. Patients and Methods: From November 1992 to May 1999, 66 patients with superficial esophageal cancer were treated with exclusive radiotherapy. The median age was 60 years (range, 41-85). Fifty-three percent of them were ineligible for surgery owing to synchronous or previously treated head-and-neck cancer. Most of the patients (n = 49) were evaluated with endoscopic ultrasonography (EUS) or computed tomography (CT). The mean doses of external beam radiotherapy and high-dose rate brachytherapy were 57.1 Gy ({+-}4.83) and 8.82 Gy ({+-}3.98), respectively. The most frequently used regimen was 60 Gy followed by 7 Gy at 5 mm depth in two applications. Results: Among patients evaluated with EUS or CT, the complete response rate was 98%. The 3-, 5-, and 7-year survival rates were 57.9%, 35.6%, and 26.6%, respectively. Median overall survival was 3.8 years. The 5-year relapse-free survival and cause-specific survival were 54.6% and 76.9%. The 5-year overall, relapse-free, and cause-specific survival of the whole population of 66 patients was 33%, 53%, and 77%, respectively. Local failure occurred in 15 of 66 patients; 6 were treated with brachytherapy. Severe late toxicity (mostly esophageal stenosis) rated according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale occurred in 6 of 66 patients (9%). Conclusion: This well tolerated regimen may be a therapeutic alternative for inoperable patients with superficial esophageal cancer. Only a randomized study could be able to check the potential benefit of brachytherapy after external beam radiation in superficial esophageal cancer.

  7. Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D) Improves Chest CT Image Quality and Reduces Radiation Exposure

    PubMed Central

    Yamashiro, Tsuneo; Miyara, Tetsuhiro; Honda, Osamu; Kamiya, Hisashi; Murata, Kiyoshi; Ohno, Yoshiharu; Tomiyama, Noriyuki; Moriya, Hiroshi; Koyama, Mitsuhiro; Noma, Satoshi; Kamiya, Ayano; Tanaka, Yuko; Murayama, Sadayuki

    2014-01-01

    Objective To assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) for image quality improvement and dose reduction for chest computed tomography (CT). Methods Institutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D). Using a 5-point scale from 1 (non-diagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease), and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts). Differences in these scores were assessed by Scheffe's test. Results At each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001) and all mediastinal measurements (p<0.01). For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001), and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA. Conclusion For chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%. PMID:25153797

  8. Identifying cell and molecular stress after radiation in a three-dimensional (3-D) model of oral mucositis

    SciTech Connect

    Lambros, Maria Polikandritou; Parsa, Cyrus; Mulamalla, HariChandana; Orlando, Robert; Lau, Bernard; Huang, Ying; Pon, Doreen; Chow, Moses

    2011-02-04

    Research highlights: {yields} We irradiated a 3-D human oral cell culture of keratinocytes and fibroblasts with 12 and 2 Gy. {yields} 6 h after irradiation the histopathology and apoptosis of the 3-D culture were evaluated. Microarrays were used to assess the gene expression in the irradiated 3-D tissue. {yields} 12 Gy induced significant histopathologic changes and cellular apoptosis. {yields} 12 Gy significantly affected genes of the NF-kB pathway, inflammatory cytokines and DAMPs. -- Abstract: Mucositis is a debilitating adverse effect of chemotherapy and radiation treatment. It is important to develop a simple and reliable in vitro model, which can routinely be used to screen new drugs for prevention and treatment of mucositis. Furthermore, identifying cell and molecular stresses especially in the initiation phase of mucositis in this model will help towards this end. We evaluated a three-dimensional (3-D) human oral cell culture that consisted of oral keratinocytes and fibroblasts as a model of oral mucositis. The 3-D cell culture model was irradiated with 12 or 2 Gy. Six hours after the irradiation we evaluated microscopic sections of the cell culture for evidence of morphologic changes including apoptosis. We used microarrays to compare the expression of several genes from the irradiated tissue with identical genes from tissue that was not irradiated. We found that irradiation with 12 Gy induced significant histopathologic effects including cellular apoptosis. Irradiation significantly affected the expression of several genes of the NF-kB pathway and several inflammatory cytokines, such as IL-1B, 1L-8, NF-kB1, and FOS compared to tissue that was not irradiated. We identified significant upregulation of several genes that belong to damage-associated molecular patterns (DAMPs) such as HMB1, S100A13, SA10014, and SA10016 in the 3-D tissues that received 12 Gy but not in tissues that received 2 Gy. In conclusion, this model quantifies radiation damage and this

  9. High doses of gamma radiation suppress allergic effect induced by food lectin

    NASA Astrophysics Data System (ADS)

    Vaz, Antônio F. M.; Souza, Marthyna P.; Vieira, Leucio D.; Aguiar, Jaciana S.; Silva, Teresinha G.; Medeiros, Paloma L.; Melo, Ana M. M. A.; Silva-Lucca, Rosemeire A.; Santana, Lucimeire A.; Oliva, Maria L. V.; Perez, Katia R.; Cuccovia, Iolanda M.; Coelho, Luana C. B. B.; Correia, Maria T. S.

    2013-04-01

    One of the most promising areas for the development of functional foods lies in the development of effective methods to reduce or eliminate food allergenicity, but few reports have summarized information concerning the progress made with food irradiation. In this study, we investigated the relationship between allergenicity and molecular structure of a food allergen after gamma irradiation and evaluate the profile of the allergic response to irradiated allergens. Cramoll, a lectin isolated from a bean and used as a food allergen, was irradiated and the possible structural changes were accompanied by spectrofluorimetry, circular dichroism and microcalorimetry. Subsequently, sensitized animals subjected to intragastric administration of non-irradiated and irradiated Cramoll were treated for 7 days. Then, body weight, leukocytes, cytokine profiles and histological parameters were also determined. Cramoll showed complete inhibition of intrinsic activity after high radiation doses. Changes in fluorescence and CD spectra with a simultaneous collapse of the tertiary structure followed by a pronounced decrease of native secondary structure were observed after irradiation. After oral challenge, sensitized mice demonstrate an association between Cramoll intake, body weight loss, eosinophilia, lymphocytic infiltrate in the gut and Eotaxin secretion. Irradiation significantly reduces, according to the dose, the effects observed by non-irradiated food allergens. We confirm that high-dose radiation may render protein food allergens innocuous by irreversibly compromising their molecular structure.

  10. Skin wound trauma, following high-dose radiation exposure, amplifies and prolongs skeletal tissue loss.

    PubMed

    Swift, Joshua M; Swift, Sibyl N; Smith, Joan T; Kiang, Juliann G; Allen, Matthew R

    2015-12-01

    The present study investigated the detrimental effects of non-lethal, high-dose (whole body) γ-irradiation on bone, and the impact that radiation combined with skin trauma (i.e. combined injury) has on long-term skeletal tissue health. Recovery of bone after an acute dose of radiation (RI; 8 Gy), skin wounding (15-20% of total body skin surface), or combined injury (RI+Wound; CI) was determined 3, 7, 30, and 120 days post-irradiation in female B6D2F1 mice and compared to non-irradiated mice (SHAM) at each time-point. CI mice demonstrated long-term (day 120) elevations in serum TRAP 5b (osteoclast number) and sclerostin (bone formation inhibitor), and suppression of osteocalcin levels through 30 days as compared to SHAM (p<0.05). Radiation-induced reductions in distal femur trabecular bone volume fraction and trabecular number through 120 days post-exposure were significantly greater than non-irradiated mice (p<0.05) and were exacerbated in CI mice by day 30 (p<0.05). Negative alterations in trabecular bone microarchitecture were coupled with extended reductions in cancellous bone formation rate in both RI and CI mice as compared to Sham (p<0.05). Increased osteoclast surface in CI animals was observed for 3 days after irradiation and remained elevated through 120 days (p<0.01). These results demonstrate a long-term, exacerbated response of bone to radiation when coupled with non-lethal wound trauma. Changes in cancellous bone after combined trauma were derived from extended reductions in osteoblast-driven bone formation and increases in osteoclast activity. PMID:26335157

  11. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    NASA Astrophysics Data System (ADS)

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C.; Edgar, A.; Varoy, C.; Belev, G.; Wysokinski, T.; Chapman, D.; Sammynaiken, R.; Kasap, S. O.

    2014-02-01

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm2+ to Sm3+ reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  12. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    SciTech Connect

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C. Kasap, S. O.; Edgar, A.; Varoy, C.; Belev, G.; Wysokinski, T.; Chapman, D.; Sammynaiken, R.

    2014-02-14

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm{sup 3+}) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm{sup 3+}-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm{sup 3+}-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm{sup 2+} to Sm{sup 3+} reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm{sup 2+} to Sm{sup 3+} reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  13. High-Dose-Rate Intraoperative Radiation Therapy for Recurrent Head-and-Neck Cancer

    SciTech Connect

    Perry, David J.; Chan, Kelvin; Wolden, Suzanne; Zelefsky, Michael J.; Chiu, Johnny; Cohen, Gilad; Zaider, Marco; Kraus, Dennis; Shah, Jatin; Lee, Nancy

    2010-03-15

    Purpose: To report the use of high-dose-rate intraoperative radiation therapy (HDR-IORT) for recurrent head-and-neck cancer (HNC) at a single institution. Methods and Materials: Between July 1998 and February 2007, 34 patients with recurrent HNC received 38 HDR-IORT treatments using a Harrison-Anderson-Mick applicator with Iridium-192. A single fraction (median, 15 Gy; range, 10-20 Gy) was delivered intraoperatively after surgical resection to the region considered at risk for close or positive margins. In all patients, the target region was previously treated with external beam radiation therapy (median dose, 63 Gy; range, 24-74 Gy). The 1- and 2-year estimates for in-field local progression-free survival (LPFS), locoregional progression-free survival (LRPFS), distant metastases-free survival (DMFS), and overall survival (OS) were calculated. Results: With a median follow-up for surviving patients of 23 months (range, 6-54 months), 8 patients (24%) are alive and without evidence of disease. The 1- and 2-year LPFS rates are 66% and 56%, respectively, with 13 (34%) in-field recurrences. The 1- and 2-year DMFS rates are 81% and 62%, respectively, with 10 patients (29%) developing distant failure. The 1- and 2-year OS rates are 73% and 55%, respectively, with a median time to OS of 24 months. Severe complications included cellulitis (5 patients), fistula or wound complications (3 patients), osteoradionecrosis (1 patient), and radiation-induced trigeminal neuralgia (1 patient). Conclusions: HDR-IORT has shown encouraging local control outcomes in patients with recurrent HNC with acceptable rates of treatment-related morbidity. Longer follow-up with a larger cohort of patients is needed to fully assess the benefit of this procedure.

  14. Genetic compensation of high dose radiation-induced damage in an anhydrobiotic insect

    NASA Astrophysics Data System (ADS)

    Gusev, Oleg; Nakahara, Yuichi; Sakashita, Tetsuya; Kikawada, Takahiro; Okuda, Takashi

    Anhydrobiotic larvae of African chironomid Polypedilum vanderplanki are known to show an extremely high tolerance against a range of stresses. The tolerance against various extreme environments exhibited by that insect might be due to being almost completely desiccated replacing water with trehalose, a state where little or no chemical reactions occur. From 2005 dried larvae of this insect are being used in a number of space experiments, both inside and outside of ISS as a model organism for estimation the limits of higher organisms' resistance to space environment stresses and long-term storage of the alive anhydrobiotic organisms during continues spaceflight. We have shown previously that both hydrated and dried larvae of Polypedilum vanderplanki have very higher tolerance against both highand low-linear energy transfer (LET), surviving after 7000Gy irradiation. It was suggested that the larvae would have effective DNA-reparation system in addition to artificial protection provided by glass-stage without water. In the present study we conducted analysis of stress-related gene expression in the larvae after 70-2000 Gy irradiations. Both DNA damage level and activity of DNA-reparation, anti-apoptotic and protein-damage related genes were analyzed. Direct visualization of DNA damage in the larvae fat body cells using Comet Assay showed that fragmented by radiation DNA is re-arranged within 76-98 hours after exposure. We found that massive overexpression of hsp and anti-oxidant genes occur in larvae entering anhydrobiosis , and provides refolding of proteins after rehydration. In the irradiated larvae overexpression of DNA-reparation enzymes anti-apoptotic genes was confirmed, suggesting that survival after high-dose irradiation is a result of combination of highly effective blocking of entering the apoptosis after severe DNA damage and DNA reparation.

  15. Mixed convection radiative flow of three dimensional Maxwell fluid over an inclined stretching sheet in presence of thermophoresis and convective condition

    SciTech Connect

    Ashraf, M. Bilal; Hayat, T.; Shehzad, S. A.; Alsaedi, A.

    2015-02-15

    Three dimensional radiative flow of Maxwell fluid over an inclined stretching surface with convective boundary condition is investigated. Heat and mass transfer analysis is taken into account with thermophoresis effects. Similarity transformations are utilized to reduce the partial differential equations into ordinary differential equations. Series solutions of velocity, temperature and concentration are developed. Influence of different parameters Biot number, therrmophoretic parameter, Deborah number, ratio parameter, inclined stretching angle, radiation parameter, mixed convection parameter and concentration buoyancy parameter on the non-dimensional velocity components, temperature and concentration are plotted and discussed in detail. Physical quantities of interests are tabulated and examined.

  16. A numerical study of three-dimensional flame propagation over thin solids in purely forced concurrent flow including gas-phase radiation

    NASA Astrophysics Data System (ADS)

    Feier, Ioan I., Jr.

    The effect of flame radiation on concurrent-flow flame spread over a thin solid sample of finite width in a low-speed wind tunnel is modeled using three-dimensional full Navier-Stokes equations and three-dimensional flame radiation transfer equations. The formulation includes the conservation of mass, momentum, energy, and species: fuel vapor, oxygen, carbon dioxide and water vapor. The SN discrete ordinates method is used to solve the radiation transfer equation with a mean absorption coefficient kappa = Ckappa p, where kappap is the Planck mean absorption coefficient of the gas mixture. The varying parameter C has a value between 0 and 1; C represents the strength of flame radiation. In addition, the solid fuel absorptivity alpha is varied to ascertain the effect of flame radiation heat feedback to the solid. The flow tunnel modeled has a dimension of 10x10x30 cm, the solid fuel has a width of 6-cm with two 1-cm inert strips as edges. Incoming forced flow velocity (5 cm/s) of 21% oxygen is assumed. For comparison with the three-dimensional results, corresponding two-dimensional computations are also performed. Detailed spatial flame profiles, solid surface profiles, and heat fluxes are presented. Increasing the flame radiation strength decreases the flame length. Although flame radiation provides an additional heat transfer mechanism to preheat the solid, it is insufficient to offset the decreased convective heating due to the shorter flame; the net effect is a slower spread rate. The percentage of unreacted fuel vapor that escapes from the flame is under 2%. It is theorized that some of the pyrolyzed fuel vapor diffuses sideway and reacts at the flame edges. A radiative energy balance is analyzed also. Flame radiative feedback to the solid plays a more important role in two-dimensional flames. With high solid fuel absorptivity, a peak in the flame spread rate occurs at an intermediate value of flame radiation strength---due to the competition between two

  17. Monte Carlo Study of Radiation Dose Enhancement by Gadolinium in Megavoltage and High Dose Rate Radiotherapy

    PubMed Central

    Zhang, Daniel G.; Feygelman, Vladimir; Moros, Eduardo G.; Latifi, Kujtim; Zhang, Geoffrey G.

    2014-01-01

    MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF) and conventional flattened 6MV photon beams were used. High dose rate (HDR) brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL) would be needed. PMID:25275550

  18. Three-dimensional visualization of morphology and ventilation procedure (air flow and diffusion) of a subdivision of the acinus using synchrotron radiation microtomography of the human lung specimens

    NASA Astrophysics Data System (ADS)

    Shimizu, Kenji; Ikura, Hirohiko; Ikezoe, Junpei; Nagareda, Tomofumi; Yagi, Naoto; Umetani, Keiji; Imai, Yutaka

    2004-04-01

    We have previously reported a synchrotron radiation (SR) microtomography system constructed at the bending magnet beamline at the SPring-8. This system has been applied to the lungs obtained at autopsy and inflated and fixed by Heitzman"s method. Normal lung and lung specimens with two different types of pathologic processes (fibrosis and emphysema) were included. Serial SR microtomographic images were stacked to yield the isotropic volumetric data with high-resolution (12 μm3 in voxel size). Within the air spaces of a subdivision of the acinus, each voxel is segmented three-dimensionally using a region growing algorithm ("rolling ball algorithm"). For each voxel within the segmented air spaces, two types of voxel coding have been performed: single-seeded (SS) coding and boundary-seeded (BS) coding, in which the minimum distance from an initial point as the only seed point and all object boundary voxels as a seed set were calculated and assigned as the code values to each voxel, respectively. With these two codes, combinations of surface rendering and volume rendering techniques were applied to visualize three-dimensional morphology of a subdivision of the acinus. Furthermore, sequentially filling process of air into a subdivision of the acinus was simulated under several conditions to visualize the ventilation procedure (air flow and diffusion). A subdivision of the acinus was reconstructed three-dimensionally, demonstrating the normal architecture of the human lung. Significant differences in appearance of ventilation procedure were observed between normal and two pathologic processes due to the alteration of the lung architecture. Three-dimensional reconstruction of the microstructure of a subdivision of the acinus and visualization of the ventilation procedure (air flow and diffusion) with SR microtomography would offer a new approach to study the morphology, physiology, and pathophysiology of the human respiratory system.

  19. Transient radiation effects following high dose I-131 therapy for differentiated thyroid cancer (DTC)

    SciTech Connect

    Khan, S.; Waxman, A.; Ramanna, L.

    1994-05-01

    There is limited information regarding the incidence of post-I-131 therapeutic side effects in pts. undergoing high-dose I-131 therapy for DTC. The purpose of the current study is to characterize side effects experienced by patients following 150 mCi.

  20. Three-dimensional MHD boundary layer flow due to an axisymmetric shrinking sheet with radiation, viscous dissipation and heat source/sink

    NASA Astrophysics Data System (ADS)

    Madhu, M.; Balaswamy, B.; Kishan, N.

    2016-05-01

    An analysis is made to study a three dimensional MHD boundary layer flow and heat transfer due to a porous axisymmetric shrinking sheet. The governing partial differential equations of momentum and energy are transformed into self similar non-linear ordinary differential equations by using the suitable similarity transformations. These equations are, then solved by using the variational finite element method. The flow phenomena is characterised by the magnetic parameter M, suction parameter S, porosity parameter Kp, heat source/sink parameter Q, Prandtl number Pr, Eckert number Ec and radiation parameter Rd. The numerical results of the velocity and temperature profiles are obtained and displayed graphically.

  1. The Effectiveness of Intensity Modulated Radiation Therapy versus Three-Dimensional Radiation Therapy in Prostate Cancer: A Meta-Analysis of the Literatures

    PubMed Central

    Zheng, Tianying; Shi, Huashan; Liu, Yang; Feng, Shijian; Hao, Meiqin; Ye, Lei; Wu, Xueqian; Yang, Cheng

    2016-01-01

    Background and Purpose Intensity modulated radiation therapy (IMRT) can deliver higher doses with less damage of healthy tissues compared with three-dimensional radiation therapy (3DCRT). However, for the scenarios with better clinical outcomes for IMRT than 3DCRT in prostate cancer, the results remain ambiguous. We performed a meta-analysis to assess whether IMRT can provide better clinical outcomes in comparison with 3DCRT in patients diagnosed with prostate cancer. Materials and Methods We conducted a meta-analysis of 23 studies (n = 9556) comparing the clinical outcomes, including gastrointestinal (GI) toxicity, genitourinary (GU) toxicity, biochemical controland overall survival (OS). Results IMRT was significantly associated with decreased 2–4 grade acute GI toxicity [risk ratio (RR) = 0.59 (95% confidence interval (CI), 0.44, 0.78)], late GI toxicity [RR = 0.54, 95%CI (0.38, 0.78)], late rectal bleeding [RR = 0.48, 95%CI (0.27, 0.85)], and achieved better biochemical control[RR = 1.17, 95%CI (1.08, 1.27)] in comparison with 3DCRT. IMRT and 3DCRT remain the same in regard of grade 2–4 acute rectal toxicity [RR = 1.03, 95%CI (0.45, 2.36)], late GU toxicity [RR = 1.03, 95%CI (0.82, 1.30)] and overall survival [RR = 1.07, 95%CI (0.96, 1.19)], while IMRT slightly increased the morbidity of grade 2–4 acute GU toxicity [RR = 1.08, 95%CI (1.00, 1.17)]. Conclusions Although some bias cannot be ignored, IMRT appears to be a better choice for the treatment of prostate cancer when compared with 3DCRT. PMID:27171271

  2. Mechanism of action for anti-radiation vaccine in reducing the biological impact of high-dose gamma irradiation

    NASA Astrophysics Data System (ADS)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after high-dose gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naïve animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which they mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  3. Hit-size effectiveness theory applied to high doses of low LET radiation for pink mutations in Tradescantia

    SciTech Connect

    Varma, M.N.; Bond, V.P.; Matthews, G.

    1985-01-01

    A hit-size effectiveness function which represents the probability of inducing a pink mutation in Tradescantia as a function of lineal energy density has been obtained (1) using observed pink mutation data for seven different radiation qualities and their respective single event microdosimetric spectra. In obtaining this function only the linear portions of dose-response curves were used. A significant improvement of the concepts embodied in the proposed hit-size effectiveness theory would be the demonstration of its applicability at high doses (where multiple hits are produced) and high dose rates (at which no significant biological repair takes place). In this article details are given on preliminary calculations of the pink mutation frequency in Tradescantia at 1, 5, 10, 20, and 60 rads for 250 kVp x rays, using the multi-hit spectra and the hit-size effectiveness function obtained on the basis of single hit microdosimetric spectra as outline in (1). A comparison of the calculated and observed pink mutation frequencies indicate excellent agreement and suggests the possibility of obtaining the hit-size effectiveness function from high dose biological-effect data obtained using low-LET radiations. 6 refs., 3 figs., 3 tabs.

  4. Quantum-mechanical calculation of three-dimensional atom-diatom collisions in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    Devries, P. L.; George, T. F.

    1979-01-01

    A formalism is presented for describing the collision of fluorine with the hydrogen molecule in the presence of intense radiation. For a laser frequency on the order of the spin-orbit splitting of fluorine, the interaction of the molecular system with the radiation occurs at relatively long range where, for this system, the electric dipole is vanishingly small. Hence the interaction occurs due to the magnetic dipole coupling. Even so, at low collision energies a substantial enhancement of the quenching cross section is found for a radiation intensity of 10 to the 11th W/sq cm.

  5. High-dose radiation improved local tumor control and overall survival in patients with inoperable/unresectable non-small-cell lung cancer: Long-term results of a radiation dose escalation study

    SciTech Connect

    Kong, F.-M. . E-mail: Fengkong@med.umich.edu; Haken, Randall K. ten; Schipper, Matthew J.; Sullivan, Molly A.; Chen, Ming; Lopez, Carlos; Kalemkerian, Gregory P.; Hayman, James A.

    2005-10-01

    Purpose: To determine whether high-dose radiation leads to improved outcomes in patients with non-small-cell lung cancer (NSCLC). Methods and Materials: This analysis included 106 patients with newly diagnosed or recurrent Stages I-III NSCLC, treated with 63-103 Gy in 2.1-Gy fractions, using three-dimensional conformal radiation therapy (3D-CRT) per a dose escalation trial. Targets included the primary tumor and any lymph nodes {>=}1 cm, without intentionally including negative nodal regions. Nineteen percent of patients (20/106) received neoadjuvant chemotherapy. Patient, tumor, and treatment factors were evaluated for association with outcomes. Estimated median follow-up was 8.5 years. Results: Median survival was 19 months, and 5-year overall survival (OS) was 13%. Multivariate analysis revealed weight loss (p = 0.011) and radiation dose (p = 0.0006) were significant predictors for OS. The 5-year OS was 4%, 22%, and 28% for patients receiving 63-69, 74-84, and 92-103 Gy, respectively. Although presence of nodal disease was negatively associated with locoregional control under univariate analysis, radiation dose was the only significant predictor when multiple variables were included (p = 0.015). The 5-year control rate was 12%, 35%, and 49% for 63-69, 74-84, and 92-103 Gy, respectively. Conclusions: Higher dose radiation is associated with improved outcomes in patients with NSCLC treated in the range of 63-103 Gy.

  6. Development and testing of gallium arsenide photoconductive detectors for ultra-fast, high dose rate electron and photon radiation measurements

    NASA Astrophysics Data System (ADS)

    Kharashvili, George

    Real time radiation dose measurements often present a challenge in high dose rate environments, like those needed for testing survivability of electronic devices or biological agents. Dosimetry needs at particle accelerator facilities require development of devices with fast (tens of picoseconds or less) response to pulsed radiation, linear response over a wide range of dose rates (up to 1011 Gy/s), high resistance to radiation damage, and successful operation in mixed gamma and neutron environments. Gallium arsenide photoconductive detectors (GaAs PCDs) have been shown to exhibit many of these desirable characteristics, especially the fast time response, when neutron irradiation is used to introduce displacement damage in the crystalline lattice of GaAs, hence improving the time response characteristics of the devices at the expense of their sensitivity. The objective of this project was to develop and test GaAs PCDs for ultra fast, high dose rate electron and bremsstrahlung radiation measurements. Effects of neutron pre-irradiation and detector size on the PCD properties were also investigated. GaAs PCDs with three different neutron irradiation levels (0, ˜1014, and 5 x 1015 n/cm 2 (1-MeV equivalent in GaAs) were fabricated. The devices were tested with 7, 20 and 38-MeV electron pulses produced by linear accelerators operating at the L-band frequency of 1.3-GHz and the S-band frequency of 2.8-GHz. In addition, detector responses at high dose rates were tested with 33-ns wide, 7-MeV maximum energy bremsstrahlung pulses produced by a pulse-power accelerator. The time response characteristics and the dose-rate ranges of application of the GaAs PCDs were determined. Several operational issues were identified. Recommendations on how to improve the PCD fabrication procedure and diagnostic capabilities for the high intensity radiation research are also discussed.

  7. Using synchrotron radiation inline phase-contrast imaging computed tomography to visualize three-dimensional printed hybrid constructs for cartilage tissue engineering.

    PubMed

    Olubamiji, Adeola D; Izadifar, Zohreh; Zhu, Ning; Chang, Tuanjie; Chen, Xiongbiao; Eames, B Frank

    2016-05-01

    Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline-PCI-CT for visualizing the components of three-dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell-laden hybrid constructs over time. Second, optimization of inline PCI-CT was performed by investigating three sample-to-detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42-day culture period. The results showed that there was progressive secretion of cartilage-specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge-enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR-inline-PCI-CT images. Summarily, SR-inline-PCI-CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42-day culture period. PMID:27140161

  8. Evidence for Three-Dimensional Radiative Effects in MODIS Cloud Optical Depths Retrieved at Back Scattering View Angles

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2003-01-01

    This study addresses the question whether 1D radiative transfer theory describes well the angular distribution of shortwave cloud reflection. The statistical analysis of a large set of MODIS observations indicates that in oblique backward scattering directions, cloud reflection is stronger than 1D theory would predict. After considering a variety of possible causes, the paper concludes that the most likely reason for the increase lies in 3D radiative interactions. The results' main implication is that cloud optical depths retrieved at back scattering view angles larger than about 50 degrees tend to be overestimated and should be used only with great caution.

  9. Three-dimensional inhomogeneous rain fields: implications for the distribution of intensity and polarization of the microwave thermal radiation.

    NASA Astrophysics Data System (ADS)

    Ilyushin, Yaroslaw; Kutuza, Boris

    Observations and mapping of the upwelling thermal radiation of the Earth is the very promising remote sensing technique for the global monitoring of the weather and precipitations. For reliable interpretation of the observation data, numerical model of the microwave radiative transfer in the precipitating atmosphere is necessary. In the present work, numerical simulations of thermal microwave radiation in the rain have been performed at three wavelengths (3, 8 and 22 mm). Radiative properties of the rain have been simulated using public accessible T-matrix codes (Mishchenko, Moroz) for non-spherical particles of fixed orientation and realistic raindrop size distributions (Marshall-Palmer) within the range of rain intensity 1-100 mm/h. Thermal radiation of infinite flat slab medium and isolated rain cell of kilometer size has been simulated with finite difference scheme for the vectorial radiative transfer equation (VRTE) in dichroic scattering medium. Principal role of cell structure of the rain field in the formation of angular and spatial distribution of the intensity and polarization of the upwelling thermal radiation has been established. Possible approaches to interpretation of satellite data are also discussed. It is necessary that spatial resolution of microwave radiometers be less than rain cell size. At the present time the resolution is approximately 15 km. It can be considerably improved, for example by two-dimensional synthetic aperture millimeter-wave radiometric interferometer for measuring full-component Stokes vector of emission from hydrometeors. The estimates show that in millimeter band it is possible to develop such equipment with spatial resolution of the order of 1-2 km, which is significantly less than the size of rain cell, with sensitivity 0.3-0.5 K. Under this condition the second Stokes parameter may by successfully measured and may be used for investigation of precipitation regions. Y-shaped phased array antenna is the most promising to

  10. Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

    SciTech Connect

    Xie, Lianghai Li, Lei; Wang, Jingdong; Zhang, Yiteng

    2014-04-15

    We present a three-dimensional, two-species (Ba{sup +} and H{sup +}) MHD model to study the early time behaviors of a barium release at about 1 R{sub E} like Combined Release and Radiation Effects Satellite G2, with emphasis placed on the three-dimensional evolution of the barium cloud and its effects on the ambient plasma environment. We find that the perturbations caused by the cloud are the combined results of the initial injection, the radial expansion, and the diamagnetic effect and propagate as fast MHD waves in the magnetosphere. In return, the transverse expansion and the cross-B motion of barium ions are constrained by the magnetic force, which lead to a field-aligned striation of ions and the decoupling of these ions from the neutrals. Our simulation shows the formation and collapse of the diamagnetic cavity in the barium cloud. The estimated time scale for the cavity evolution might be much shorter if photoionization time scale and field aligned expansion of barium ions are considered. In addition, our two species MHD simulation also finds the snowplow effect resulting from the momentum coupling between barium ions and background H{sup +}, which creates density hole and bumps in the background H{sup +} when barium ions expanding along the magnetic field lines.

  11. Three-dimensional sonoembryology.

    PubMed

    Benoit, Bernard; Hafner, Tomislav; Kurjak, Asim; Kupesić, Sanja; Bekavac, Ivanka; Bozek, Tomislav

    2002-01-01

    Three-dimensional (3D) ultrasound plays an important role in obstetrics, predominantly for assessing fetal anatomy. Presenting volume data in a standard anatomic orientation valuably assists both ultrasonographers and pregnant patients to recognize the anatomy more readily. Three-dimensional ultrasound is advantageous in studying normal embryonic and/or fetal development, as well as providing information for families at risk for specific congenital anomalies by confirming normality. This method offers advantages in assessing the embryo in the first trimester due to its ability to obtain multiplanar images through endovaginal volume acquisition. Rotation allows the systematic review of anatomic structures and early detection of fetal anomalies. Three-dimensional ultrasound imaging in vivo compliments pathologic and histologic evaluation of the developing embryo, giving rise to a new term: 3D sonoembryology. Rapid technological development will allow real-time 3D ultrasound to provide improved and expanded patient care on the one side, and increased knowledge of developmental anatomy on the other. PMID:11933658

  12. High-Dose Radiation May Be No Better for Low-Risk Prostate Cancer

    MedlinePlus

    ... Radiation May Be No Better for Low-Risk Prostate Cancer Study finds no benefits in disease progression, survival ... doses of radiation may not benefit low-risk prostate cancer patients, a new review suggests. "In the field ...

  13. Development and validation of a black carbon mixing state resolved three-dimensional model: Aging processes and radiative impact

    SciTech Connect

    Matsui, H.; Koike, Makoto; Kondo, Yutaka; Moteki, N.; Fast, Jerome D.; Zaveri, Rahul A.

    2013-03-16

    : A new two-dimensional aerosol bin scheme, which resolves both aerosol size and black carbon (BC) mixing state for BC aging processes (e.g., condensation and coagulation), has been developed and implemented into the WRF-chem model (MS-resolved WRF-chem). The mixing state of BC simulated by this model is compared with direct measurements over the East Asian region in spring 2009. Model simulations generally reproduce the observed features of the BC mixing state, such as the size-dependent number fractions of BC-containing and BC-free particles and the coating thickness of BC-containing particles. Sensitivity simulations show that the condensation process is dominant for the growth of thinly coated BC particles, while the coagulation process is necessary to produce thickly coated BC particles. Off-line optical and radiative calculations assuming an average mixing state for each size bin show that the domain- and period-averaged absorption coefficient and heating rate by aerosols are overestimated by 30 – 40% in the boundary layer compared with a benchmark simulation with the detailed treatment of mixing state. The absolute value of aerosol radiative forcing is also overestimated (10%, 3 W m-2) at the surface. However, these overestimations are reduced considerably when all the parameters (including mass and number concentration) are calculated with the simple treatment of mixing state. This is because the overestimation of radiative parameters due to higher absorption efficiency (compared with the benchmark simulation) is largely canceled by the underestimation of BC concentrations due to efficient wet removal processes. The overall errors in radiative forcing can be much smaller because of this cancellation but for the wrong reasons.

  14. Development and validation of a black carbon mixing state resolved three-dimensional model: Aging processes and radiative impact

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Koike, M.; Kondo, Y.; Moteki, N.; Fast, J. D.; Zaveri, R. A.

    2013-03-01

    A new two-dimensional aerosol bin scheme, which resolves both aerosol size and black carbon (BC) mixing state for BC aging processes (e.g., condensation and coagulation) with 12 size × 10 mixing state bins, has been developed and implemented into the WRF-chem model (MS-resolved WRF-chem). The mixing state of BC simulated by this model is compared with direct measurements over the East Asian region in spring 2009. Model simulations generally reproduce the observed features of the BC mixing state, such as the size-dependent number fractions of BC-containing and BC-free particles and the coating thickness of BC-containing particles. This result shows that the model can simulate realistic BC mixing states in the atmosphere if condensation and coagulation processes are calculated explicitly with the detailed treatment of BC mixing state. Sensitivity simulations show that the condensation process is dominant for the growth of thinly coated BC particles, while the coagulation process is necessary to produce thickly coated BC particles. Off-line optical and radiative calculations assuming an average mixing state for each size bin show that the domain- and period-averaged absorption coefficient and heating rate by aerosols are overestimated by 30-40% in the boundary layer, compared with a benchmark simulation with the detailed treatment of mixing state. The absolute value of aerosol radiative forcing is also overestimated (10%, 3 W m-2) at the surface. However, these overestimations are reduced considerably when all the parameters (including mass and number concentration) are calculated with the simple treatment of mixing state. This is because the overestimation of radiative parameters due to higher absorption efficiency (compared with the benchmark simulation) is largely canceled by the underestimation of BC concentrations due to efficient wet removal processes. The overall errors in radiative forcing can be much smaller because of this cancellation, but for the wrong

  15. Tree crown structural characterization: A study using terrestrial laser scanning and three-dimensional radiative transfer modeling

    NASA Astrophysics Data System (ADS)

    Moorthy, Inian

    Spectroscopic observational data for vegetated environments, have been coupled with 3D physically-based radiative transfer models for retrievals of biochemical and biophysical indicators of vegetation health and condition. With the recent introduction of Terrestrial Laser Scanning (TLS) units, there now exists a means of rapidly measuring intricate structural details of vegetation canopies, which can also serve as input into 3D radiative transfer models. In this investigation, Intelligent Laser Ranging and Imaging System (ILRIS-3D) data was acquired of individual tree crowns in laboratory, and field-based experiments. The ILRIS-3D uses the Time-Of-Flight (TOF) principle to measure the distances of objects based on the time interval between laser pulse exitance and return, upon reflection from an object. At the laboratory-level, this exploratory study demonstrated and validated innovative approaches for retrieving crown-level estimates of Leaf Area Index (LAI) (r2 = 0.98, rmse = 0.26m2/m2), a critical biophysical parameter for vegetation monitoring and modeling. These methods were implemented and expanded in field experiments conducted in olive (Olea europaea L.) orchards in Cordoba, Spain, where ILRIS-3D observations for 24 structurally-variable trees were made. Robust methodologies were developed to characterize diagnostic architectural parameters, such as tree height (r2 = 0.97, rmse = 0.21m), crown width (r 2 = 0.98, rmse = 0.12m), crown height (r2 = 0.81, rmse = 0.11m), crown volume (r2 = 0.99, rmse = 2.6m3), and LAI (r2 = 0.76, rmse = 0.27m2/ m2). These parameters were subsequently used as direct inputs into the Forest LIGHT (FLIGHT) 3D ray tracing model for characterization of the spectral behavior of the olive crowns. Comparisons between FLIGHT-simulated spectra and measured data showed small differences in the visible (< 3%) and near infrared (< 10%) spectral ranges. These differences between model simulations and measurements were significantly correlated

  16. Adjuvant treatment in patients at high risk of recurrence of thymoma: efficacy and safety of a three-dimensional conformal radiation therapy regimen

    PubMed Central

    Perri, Francesco; Pisconti, Salvatore; Conson, Manuel; Pacelli, Roberto; Della Vittoria Scarpati, Giuseppina; Gnoni, Antonio; D’Aniello, Carmine; Cavaliere, Carla; Licchetta, Antonella; Cella, Laura; Giuliano, Mario; Schiavone, Concetta; Falivene, Sara; Di Lorenzo, Giuseppe; Buonerba, Carlo; Ravo, Vincenzo; Muto, Paolo

    2015-01-01

    Background The clinical benefits of postoperative radiation therapy (PORT) for patients with thymoma are still controversial. In the absence of defined guidelines, prognostic factors such as stage, status of surgical margins, and histology are often considered to guide the choice of adjuvant treatment (radiotherapy and/or chemotherapy). In this study, we describe our single-institution experience of three-dimensional conformal PORT administered as adjuvant treatment to patients with thymoma. Methods Twenty-two consecutive thymoma patients (eleven male and eleven female) with a median age of 52 years and treated at our institution by PORT were analyzed. The patients were considered at high risk of recurrence, having at least one of the following features: stage IIB or III, involved resection margins, or thymic carcinoma histology. Three-dimensional conformal PORT with a median total dose on clinical target volume of 50 (range 44–60) Gy was delivered to the tumor bed by 6–20 MV X-ray of the linear accelerator. Follow-up after radiotherapy was done by computed tomography scan every 6 months for 2 years and yearly thereafter. Results Two of the 22 patients developed local recurrence and four developed distant metastases. Median overall survival was 100 months, and the 3-year and 5-year survival rates were 83% and 74%, respectively. Median disease-free survival was 90 months, and the 5-year recurrence rate was 32%. On univariate analysis, pathologic stage III and presence of positive surgical margins had a significant impact on patient prognosis. Radiation toxicity was mild in most patients and no severe toxicity was registered. Conclusion Adjuvant radiotherapy achieved good local control and showed an acceptable toxicity profile in patients with high-risk thymoma. PMID:26089683

  17. Three dimensional Monte Carlo simulation of molecular movement and heat radiation in vacuum devices: Computer code MOVAK3D

    NASA Astrophysics Data System (ADS)

    Class, G.

    1987-07-01

    A program to simulate gas motion and shine through of thermal radiation in fusion reactor vacuum flow channels was developed. The inner surface of the flow channel is described by plane areas (triangles, parallelograms) and by surfaces of revolution. By introducing control planes in the flow path, a variance reduction and shortening of the computation, respectively, are achieved through particle splitting and Russian roulette. The code is written in PL/I and verified using published data. Computer aided input of model data is performed interactively either under IBM-TSO or at a microprocessor (IBM PC-AT). The data files are exchangeable between the IBM-mainframe and IBM-PC computers. Both computers can produce plots of the elaborated channel model. For testing, the simulating computation can likewise be run interactively, whereas the production computation can be issued batchwise. The results of code verification are explained, and examples of channel models and of the interactive mode are given.

  18. Three-dimensional metamaterials

    DOEpatents

    Burckel, David Bruce

    2012-06-12

    A fabrication method is capable of creating canonical metamaterial structures arrayed in a three-dimensional geometry. The method uses a membrane suspended over a cavity with predefined pattern as a directional evaporation mask. Metallic and/or dielectric material can be evaporated at high vacuum through the patterned membrane to deposit resonator structures on the interior walls of the cavity, thereby providing a unit cell of micron-scale dimension. The method can produce volumetric metamaterial structures comprising layers of such unit cells of resonator structures.

  19. Three-dimensional, Time-Resolved, Intrafraction Motion Monitoring Throughout Stereotactic Liver Radiation Therapy on a Conventional Linear Accelerator

    SciTech Connect

    Worm, Esben S.; Høyer, Morten; Fledelius, Walter; Poulsen, Per R.

    2013-05-01

    Purpose: To investigate the time-resolved 3-dimensional (3D) internal motion throughout stereotactic body radiation therapy (SBRT) of tumors in the liver using standard x-ray imagers of a conventional linear accelerator. Methods and Materials: Ten patients with implanted gold markers received 11 treatment courses of 3-fraction SBRT in a stereotactic body-frame on a conventional linear accelerator. Two pretreatment and 1 posttreatment cone-beam computed tomography (CBCT) scans were acquired during each fraction. The CBCT projection images were used to estimate the internal 3D marker motion during CBCT acquisition with 11-Hz resolution by a monoscopic probability-based method. Throughout the treatment delivery by conformal or volumetric modulated arc fields, simultaneous MV portal imaging (8 Hz) and orthogonal kV imaging (5 Hz) were applied to determine the 3D marker motion using either MV/kV triangulation or the monoscopic method when marker segmentation was unachievable in either MV or kV images. The accuracy of monoscopic motion estimation was quantified by also applying monoscopic estimation as a test for all treatments during which MV/kV triangulation was possible. Results: Root-mean-square deviations between monoscopic estimations and triangulations were less than 1.0 mm. The mean 3D intrafraction and intrafield motion ranges during liver SBRT were 17.6 mm (range, 5.6-39.5 mm) and 11.3 mm (2.1-35.5mm), respectively. The risk of large intrafraction baseline shifts correlated with intrafield respiratory motion range. The mean 3D intrafractional marker displacement relative to the first CBCT was 3.4 mm (range, 0.7-14.5 mm). The 3D displacements exceeded 8.8 mm 10% of the time. Conclusions: Highly detailed time-resolved internal 3D motion was determined throughout liver SBRT using standard imaging equipment. Considerable intrafraction motion was observed. The demonstrated methods provide a widely available approach for motion monitoring that, combined with motion

  20. Coupling sky images with three-dimensional radiative transfer models: a new method to estimate cloud optical depth

    NASA Astrophysics Data System (ADS)

    Mejia, F. A.; Kurtz, B.; Murray, K.; Hinkelman, L. M.; Sengupta, M.; Xie, Y.; Kleissl, J.

    2015-10-01

    A method for retrieving cloud optical depth (τc) using a ground-based sky imager (USI) is presented. The Radiance Red-Blue Ratio (RRBR) method is motivated from the analysis of simulated images of various τc produced by a 3-D Radiative Transfer Model (3DRTM). From these images the basic parameters affecting the radiance and RBR of a pixel are identified as the solar zenith angle (θ0), τc, solar pixel angle/scattering angle (ϑs), and pixel zenith angle/view angle (ϑz). The effects of these parameters are described and the functions for radiance, Iλ(τc, θ0, ϑs, ϑz) and the red-blue ratio, RBR(τc, θ0, ϑs, ϑz) are retrieved from the 3DRTM results. RBR, which is commonly used for cloud detection in sky images, provides non-unique solutions for τc, where RBR increases with τc up to about τc = 1 (depending on other parameters) and then decreases. Therefore, the RRBR algorithm uses the measured Iλmeas(ϑs, ϑz), in addition to RBRmeas(ϑs, ϑz) to obtain a unique solution for τc. The RRBR method is applied to images taken by a USI at the Oklahoma Atmospheric Radiation Measurement program (ARM) site over the course of 220 days and validated against measurements from a microwave radiometer (MWR); output from the Min method for overcast skies, and τc retrieved by Beer's law from direct normal irradiance (DNI) measurements. A τc RMSE of 5.6 between the Min method and the USI are observed. The MWR and USI have an RMSE of 2.3 which is well within the uncertainty of the MWR. An RMSE of 0.95 between the USI and DNI retrieved τc is observed. The procedure developed here provides a foundation to test and develop other cloud detection algorithms.

  1. Three-dimensional imaging of human hippocampal tissue using synchrotron radiation- and grating-based micro computed tomography

    NASA Astrophysics Data System (ADS)

    Hieber, Simone E.; Khimchenko, Anna; Kelly, Christopher; Mariani, Luigi; Thalmann, Peter; Schulz, Georg; Schmitz, Rüdiger; Greving, Imke; Dominietto, Marco; Müller, Bert

    2014-09-01

    Hippocampal sclerosis is a common cause of epilepsy, whereby a neuronal cell loss of more than 50% cells is characteristic. If medication fails the best possible treatment is the extraction of the diseased organ. To analyze the microanatomy of the diseased tissue we scanned a human hippocampus extracted from an epilepsy patient. After the identification of degenerated tissue using magnetic resonance imaging the specimen was reduced in size to fit into a cylindrical container with a diameter of 6 mm. Using synchrotron radiation and grating interferometry we acquired micro computed tomography datasets of the specimen. The present study was one of the first successful phase tomography measurements at the imaging beamline P05 (operated by HZG at the PETRA III storage ring, DESY, Hamburg, Germany). Ring and streak artefacts were reduced by enhanced flat-field corrections, combined wavelet-Fourier filters and bilateral filtering. We improved the flat-field correction by the consideration of the correlation between the projections and the flat-field images. In the present study, the correlation that was based on mean squared differences and evaluated on manually determined reference regions leads to the best artefact reduction. A preliminary segmentation of the abnormal tissue reveals that a clinically relevant study requires the development of even more sophisticated artifact reduction tools or a phase contrast measurement of higher quality.

  2. Signatures of asymmetry in neutron spectra and images predicted by three-dimensional radiation hydrodynamics simulations of indirect drive implosions

    NASA Astrophysics Data System (ADS)

    Chittenden, J. P.; Appelbe, B. D.; Manke, F.; McGlinchey, K.; Niasse, N. P. L.

    2016-05-01

    We present the results of 3D simulations of indirect drive inertial confinement fusion capsules driven by the "high-foot" radiation pulse on the National Ignition Facility. The results are post-processed using a semi-deterministic ray tracing model to generate synthetic deuterium-tritium (DT) and deuterium-deuterium (DD) neutron spectra as well as primary and down scattered neutron images. Results with low-mode asymmetries are used to estimate the magnitude of anisotropy in the neutron spectra shift, width, and shape. Comparisons of primary and down scattered images highlight the lack of alignment between the neutron sources, scatter sites, and detector plane, which limits the ability to infer the ρr of the fuel from a down scattered ratio. Further calculations use high bandwidth multi-mode perturbations to induce multiple short scale length flows in the hotspot. The results indicate that the effect of fluid velocity is to produce a DT neutron spectrum with an apparently higher temperature than that inferred from the DD spectrum and which is also higher than the temperature implied by the DT to DD yield ratio.

  3. Comparison of intensity-modulated radiotherapy with three-dimensional conformal radiation therapy planning for glioblastoma multiforme

    SciTech Connect

    Chan, Maria F.; Schupak, Karen; Burman, Chandra; Chui, C.-S.; Ling, C. Clifton

    2003-12-31

    This study was designed to assess the feasibility and potential benefit of using intensity-modulated radiotherapy (IMRT) planning for patients newly diagnosed with glioblastoma multiforme (GBM). Five consecutive patients with confirmed histopathologically GBM were entered into the study. These patients were planned and treated with 3-dimensional conformal radiation therapy (3DCRT) using our standard plan of 3 noncoplanar wedged fields. They were then replanned with the IMRT method that included a simultaneous boost to the gross tumor volume (GTV). The dose distributions and dose-volume histograms (DHVs) for the planning treatment volume (PTV), GTV, and the relevant critical structures, as obtained with 3DCRT and IMRT, respectively, were compared. In both the 3DCRT and IMRT plans, 59.4 Gy was delivered to the GTV plus a margin of 2.5 cm, with doses to critical structures below the tolerance threshold. However, with the simultaneous boost in IMRT, a higher tumor dose of {approx}70 Gy could be delivered to the GTV, while still maintaining the uninvolved brain at dose levels of the 3DCRT technique. In addition, our experience indicated that IMRT planning is less labor intensive and time consuming than 3DCRT planning. Our study shows that IMRT planning is feasible and efficient for radiotherapy of GBM. In particular, IMRT can deliver a simultaneous boost to the GTV while better sparing the normal brain and other critical structures.

  4. Three dimensional location of internal mammary lymph nodes (IMLN) in patients undergoing radiation therapy: Implications for portal planning

    SciTech Connect

    Kaplan, W.D.; Anderson, J.W.; Siddon, R.L.; Connolly, B.T.; McCormick, C.A.; Laffin, S.M.; Rosenbaum, E.M.; Jennings, C.A.; Harris, J.R.

    1985-05-01

    In breast cancer patients (pts.), radiation therapy (RT) techniques must account for individual anatomy to ensure optimal coverage of tumor regions. Knowledge of IMLN localization is often useful when tangential or anterior (AP) portals are used. We have analyzed IMLN localization in 167 pts. who had lymphoscintigraphy (LS) for RT planning. Parallel and slant-hole collimation were used for imaging. Ribs were defined with lead markers, and a chest x-ray was taken to localize marker positions. Rib and interspace (IS) location of each node was recorded. 768 nodes were analyzed for position and RT coverage (Rib 1-IS 5). The X-bar number of nodes was 4/6 pt. with no significant difference in number by age. Cross-over to the opposite IMLN chain occurred in 13.8% of cases (56.5% manubrial, 17.4% midsternal, and 26.1% xiphoid). With nodes in the idealized tangential field (those from IS 2-5, anterior to a 35/sup 0/ plane entering the thorax 3 cm contralateral to midline, at least one node could have been missed in 31 pts. (18.6%), represented by 44 of 768 nodes (5.7%). In conclusion, RT portals based on ''idealized pts.'' can result in both over and undertreated nodes; LS will obviate this and provide data for individualized treatment planning.

  5. Mechanism of Action for Anti-Radiation Vaccine in Reducing the Biological Impact of High-Dose Irradiation

    NASA Technical Reports Server (NTRS)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    2006-01-01

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. We partially analyzed the biochemical characteristics of the SRDs. The SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  6. Mechanism of Action for Anti-radiation Vaccine in Reducing the Biological Impact of High-dose Gamma Irradiation

    NASA Technical Reports Server (NTRS)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    2007-01-01

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  7. Three Dimensional Dirac Semimetals

    NASA Astrophysics Data System (ADS)

    Zaheer, Saad

    2014-03-01

    Dirac points on the Fermi surface of two dimensional graphene are responsible for its unique electronic behavior. One can ask whether any three dimensional materials support similar pseudorelativistic physics in their bulk electronic spectra. This possibility has been investigated theoretically and is now supported by two successful experimental demonstrations reported during the last year. In this talk, I will summarize the various ways in which Dirac semimetals can be realized in three dimensions with primary focus on a specific theory developed on the basis of representations of crystal spacegroups. A three dimensional Dirac (Weyl) semimetal can appear in the presence (absence) of inversion symmetry by tuning parameters to the phase boundary separating a bulk insulating and a topological insulating phase. More generally, we find that specific rules governing crystal symmetry representations of electrons with spin lead to robust Dirac points at high symmetry points in the Brillouin zone. Combining these rules with microscopic considerations identifies six candidate Dirac semimetals. Another method towards engineering Dirac semimetals involves combining crystal symmetry and band inversion. Several candidate materials have been proposed utilizing this mechanism and one of the candidates has been successfully demonstrated as a Dirac semimetal in two independent experiments. Work carried out in collaboration with: Julia A. Steinberg, Steve M. Young, J.C.Y. Teo, C.L. Kane, E.J. Mele and Andrew M. Rappe.

  8. Human pulmonary acinar airspace segmentation from three-dimensional synchrotron radiation micro CT images of secondary pulmonary lobule

    NASA Astrophysics Data System (ADS)

    Kawata, Y.; Hosokawa, T.; Niki, N.; Umetani, K.; Nakano, Y.; Ohmatsu, H.; Moriyama, N.; Itoh, H.

    2011-03-01

    The recognition of abnormalities relative to the lobular anatomy has become increasingly important in the diagnosis and differential diagnosis of lung abnormalities at clinical routines of CT examinations. This paper aims for a 3-D microstructural analysis of the pulmonary acinus with isotropic spatial resolution in the range of several micrometers by using micro CT. Previously, we demonstrated the ability of synchrotron radiation micro CT (SRμCT) using offset scan mode in microstructural analysis of the whole part of the secondary pulmonary lobule. In this paper, we present a semi-automatic method to segment the acinar and subacinar airspaces from the secondary pulmonary lobule imaged by the SRμCT. The method began with a segmentation of the tissues such as pleural surface, interlobular septa, alveola wall, or vessel using threshold technique and 3-D connected component analysis. Follow-on stages then constructed 3-D air space separated by tissues and represented branching patterns of airways and airspaces distal to the terminal bronchiole. Finally, a graph-partitioning approach isolated acini whose stems were interactively defined as the terminal bronchiole in the secondary pulmonary lobule. Additionally, the isolated acinar airspace was segmented into subacini in which the airway was considered as the stem using the graph-partitioning approach. Results demonstrate that the proposed method can extract several acinar airspaces from the 3-D SRμCT image of secondary pulmonary lobule and that the extracted acinar airspace enable an accurate quantitative description of the anatomy of the human acinus for interpretation of the basic unit of pulmonary structure and function.

  9. High-dose ionizing radiation-induced hematotoxicity and metastasis in mice model.

    PubMed

    Shin, Jang Woo; Son, Jin Young; Raghavendran, Hanumantha Rao Balaji; Chung, Weon Kyu; Kim, Hyeong Geug; Park, Hye Jung; Jang, Seong Soon; Son, Chang Gue

    2011-12-01

    Radiotherapy induces untargeted effects on normal tissues such as bone marrow. So alteration of microenvironment by ionizing irradiation is supposed to influence dynamic host-cancer ecosystem affecting cancer behavior including metastasis. Herein, the incidence of lung metastasis after high-dose irradiation has been investigated using mice model having real-time condition of leucopenia. C57BL/6 mice were pre-exposed to a X-irradiation dose of 6 Gy on previous days 2, 5, 7, 10. Complete hematological parameters including lymphocyte subpopulation in blood and lung tissues were analyzed. Additionally, a group of mice including a non-irradiated group were inoculated with B16F10 cells (3 × 10(5)/200 μl) via tail vein at the same day, and lung metastasized colonies were compared among groups at day 14 of post-inoculation. We observed that (i) total leucocytes and platelet were gradually depleted by day 10; (ii) lung tissue showed gradual infiltration of leucocytes including neutrophils and lymphocytes; (iii) pulmonary colonies were maximum and minimum on day 5 and 10 respectively; (iv) lymphocyte subpopulation analysis showed most number of natural killer (NK) cells in lung tissues on day 10; (v) gene expression of platelet/endothelial cell adhesion molecule (PECAM) in lung tissues peaked on day 5. To sum-up the study, severity of leucopenia did not influence the incidence of metastasis but blood platelets and microenvironment alteration of targeting tissue may be responsible factors for lung metastasis in our experimental model. PMID:21769700

  10. Laser-guided direct writing for three-dimensional tissue engineering: Analysis and application of radiation forces

    NASA Astrophysics Data System (ADS)

    Nahmias, Yaakov Koby

    Tissue Engineering aims for the creation of functional tissues or organs using a combination of biomaterials and living cells. Artificial tissues can be implanted in patients to restore tissue function that was lost due to trauma, disease, or genetic disorder. Tissue equivalents may also be used to screen the effects of drugs and toxins, reducing the use of animals in research. One of the principle limitations to the size of engineered tissue is oxygen and nutrient transport. Lacking their own vascular bed, cells embedded in the engineered tissue will consume all available oxygen within hours while out branching blood vessels will take days to vascularize the implanted tissue. Establishing capillaries within the tissue prior to implantation can potentially eliminate this limitation. One approach to establishing capillaries within the tissue is to directly write endothelial cells with micrometer accuracy as it is being built. The patterned endothelial cells will then self-assemble into vascular structures within the engineering tissue. The cell patterning technique known as laser-guided direct writing can confine multiple cells in a laser beam and deposit them as a steady stream on any non-absorbing surface with micrometer scale accuracy. By applying the generalized Lorenz-Mie theory for light scattering on laser-guided direct writing we were able to accurately predict the behavior of with various cells and particles in the focused laser. In addition, two dimensionless parameters were identified for general radiation-force based system design. Using laser-guided direct writing we were able to direct the assembly of endothelial vascular structures with micrometer accuracy in two and three dimensions. The patterned vascular structures provided the backbone for subsequent in vitro liver morphogenesis. Our studies show that hepatocytes migrate toward and adhere to endothelial vascular structures in response to endothelial-secreted hepatocyte growth factor (HGF). Our

  11. Ex vivo cultures of glioblastoma in three-dimensional hydrogel maintain the original tumor growth behavior and are suitable for preclinical drug and radiation sensitivity screening

    SciTech Connect

    Jiguet Jiglaire, Carine; Baeza-Kallee, Nathalie; Denicolaï, Emilie; Barets, Doriane; Metellus, Philippe; and others

    2014-02-15

    Identification of new drugs and predicting drug response are major challenges in oncology, especially for brain tumors, because total surgical resection is difficult and radiation therapy or chemotherapy is often ineffective. With the aim of developing a culture system close to in vivo conditions for testing new drugs, we characterized an ex vivo three-dimensional culture system based on a hyaluronic acid-rich hydrogel and compared it with classical two-dimensional culture conditions. U87-MG glioblastoma cells and seven primary cell cultures of human glioblastomas were subjected to radiation therapy and chemotherapy drugs. It appears that 3D hydrogel preserves the original cancer growth behavior and enables assessment of the sensitivity of malignant gliomas to radiation and drugs with regard to inter-tumoral heterogeneity of therapeutic response. It could be used for preclinical assessment of new therapies. - Highlights: • We have compared primary glioblastoma cell culture in a 2D versus 3D-matrix system. • In 3D morphology, organization and markers better recapitulate the original tumor. • 3D-matrix culture might represent a relevant system for more accurate drug screening.

  12. Upregulated epidermal growth factor receptor expression following near-infrared irradiation simulating solar radiation in a three-dimensional reconstructed human corneal epithelial tissue culture model

    PubMed Central

    Tanaka, Yohei; Nakayama, Jun

    2016-01-01

    Background and objective Humans are increasingly exposed to near-infrared (NIR) radiation from both natural (eg, solar) and artificial (eg, electrical appliances) sources. Although the biological effects of sun and ultraviolet (UV) exposure have been extensively investigated, the biological effect of NIR radiation is still unclear. We previously reported that NIR as well as UV induces photoaging and standard UV-blocking materials, such as sunglasses, do not sufficiently block NIR. The objective of this study was to investigate changes in gene expression in three-dimensional reconstructed corneal epithelial tissue culture exposed to broad-spectrum NIR irradiation to simulate solar NIR radiation that reaches human tissues. Materials and methods DNA microarray and quantitative real-time polymerase chain reaction analysis were used to assess gene expression levels in a three-dimensional reconstructed corneal epithelial model composed of normal human corneal epithelial cells exposed to water-filtered broad-spectrum NIR irradiation with a contact cooling (20°C). The water-filter allowed 1,000–1,800 nm wavelengths and excluded 1,400–1,500 nm wavelengths. Results A DNA microarray with >62,000 different probes showed 25 and 150 genes that were up- or downregulated by at least fourfold and twofold, respectively, after NIR irradiation. In particular, epidermal growth factor receptor (EGFR) was upregulated by 19.4-fold relative to control cells. Quantitative real-time polymerase chain reaction analysis revealed that two variants of EGFR in human corneal epithelial tissue were also significantly upregulated after five rounds of 10 J/cm2 irradiation (P<0.05). Conclusion We found that NIR irradiation induced the upregulated expression of EGFR in human corneal cells. Since over half of the solar energy reaching the Earth is in the NIR region, which cannot be adequately blocked by eyewear and thus can induce eye damage with intensive or long-term exposure, protection from both

  13. The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

    DOE PAGESBeta

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; Mickel, Patrick R.; Hanson, Donald J.; McDonald, Joseph K.; Hughart, David Russell; Marinella, Matthew J.

    2014-11-11

    This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×107 rad(Si)/s to 4.7 ×108 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×108 rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. Inmore » addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.« less

  14. High-dose radiation therapy alone by moderate hypofractionation for patients with thoracic esophageal squamous cell carcinoma.

    PubMed

    Oh, Dongryul; Noh, Jae Myoung; Nam, Heerim; Lee, Hyebin; Kim, Tae Gyu; Ahn, Yong Chan

    2016-08-01

    We conducted retrospective analyses to investigate the clinical outcome of thoracic esophageal cancer patients who were treated with high-dose radiation therapy (RT) alone by moderate hypofractionation due to medical unfitness or refusal to receive either surgery or chemo-radiotherapy.Between May 2003 and April 2013, 70 patients were treated with high-dose RT alone with curative aim. The planned total RT dose was 60 Gy in daily 3.0 Gy per fraction. We evaluated the survival outcome, toxicities, and prognostic factors affecting patients' survival.At the time of analysis, 32 patients experienced disease progression. The 2-year overall survival (OS), cancer-specific survival (CSS) and local control (LC) rates were 52.1%, 57.8%, and 68.2%, respectively. Among them, 25 patients had superficial (cT1a-b) esophageal cancers, and the 2-year OS, CSS, and LC rates were 80.0%, 87.3%, and 81.6%, respectively. Multivariate analysis revealed that cT disease (P < 0.001) and tumor location (P = 0.022) were the significant factors for OS. The incidence of grade 3 or higher toxicities were 9.9%, including grade 3 esophagitis (2 patients, 2.8%) and grade 4 or 5 trachea-esophageal fistula (5 patients, 7.1%).High-dose RT alone by moderate hypofractionation had led to reasonable clinical outcomes at acceptable toxicity risk in thoracic esophageal cancer patients who are medically unfit or refuse surgery or chemotherapy, especially for the patients having superficial lesion. PMID:27537591

  15. Comparative MicroRNA Expression Patterns in Fibroblasts after Low and High Doses of Low-LET Radiation Exposure

    NASA Technical Reports Server (NTRS)

    Maes, Olivier C.; Xu, Suying; Hada, Megumi; Wu, Honglu; Wang, Eugenia

    2007-01-01

    Exposure to ionizing radiation causes DNA damage to cells, and provokes a plethora of cellular responses controlled by unique gene-directed signaling pathways. MicroRNAs (miRNAs) are small (22-nucleotide), non-coding RNAs which functionally silence gene expression by either degrading the messages or inhibiting translation. Here we investigate radiation-dependent changes in these negative regulators by comparing the expression patterns of all 462 known human miRNAs in fibroblasts, after exposure to low (0.1 Gy) or high (2 Gy) doses of X-rays at 30 min, 2, 6 and 24 hrs post-treatment. The expression patterns of microRNAs after low and high doses of radiation show a similar qualitative down-regulation trend at early (0.5 hr) and late (24 hr) time points, with a quantitatively steeper slope following the 2 Gy exposures. Interestingly, an interruption of this downward trend is observed after the 2 Gy exposure, i.e. a significant up-regulation of microRNAs at 2 hrs, then reverting to the downward trend by 6 hrs; this interruption at the intermediate time point was not observed with the 0.1 Gy exposure. At the early time point (0.5 hr), candidate gene targets of selected down-regulated microRNAs, common to both 0.1 and 2 Gy exposures, were those functioning in chromatin remodeling. Candidate target genes of unique up-regulated microRNAs seen at a 2 hr intermediate time point, after the 2 Gy exposure only, are those involved in cell death signaling. Finally, putative target genes of down-regulated microRNAs seen at the late (24 hr) time point after either doses of radiation are those involved in the up-regulation of DNA repair, cell signaling and homeostasis. Thus we hypothesize that after radiation exposure, microRNAs acting as hub negative regulators for unique signaling pathways needed to be down-regulated so as to de-repress their target genes for the proper cellular responses, including DNA repair and cell maintenance. The unique microRNAs up-regulated at 2 hr after 2

  16. Three dimensional interactive display

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2005-01-01

    A three-dimensional (3-D) interactive display and method of forming the same, includes a transparent capaciflector (TC) camera formed on a transparent shield layer on the screen surface. A first dielectric layer is formed on the shield layer. A first wire layer is formed on the first dielectric layer. A second dielectric layer is formed on the first wire layer. A second wire layer is formed on the second dielectric layer. Wires on the first wire layer and second wire layer are grouped into groups of parallel wires with a turnaround at one end of each group and a sensor pad at the opposite end. An operational amplifier is connected to each of the sensor pads and the shield pad biases the pads and receives a signal from connected sensor pads in response to intrusion of a probe. The signal is proportional to probe location with respect to the monitor screen.

  17. Radiation chemistry of anionic disazo dyes in Cellophane films applications for high-dose dosimetry

    NASA Astrophysics Data System (ADS)

    McLaughlin, William L.

    2003-06-01

    Thin transparent Cellophane films containing anionic disazo "Direct" dyes, e.g. blue Cellophanes, have long been used as monitors of large absorbed doses of ionizing radiation (10-300 kGy) and especially for mapping electron-beam dose profiles. Examples of dyes for such purposes are variations on forms of the disazo dyes, Direct Orange, Direct Violet or Direct Blue. The films have a thickness of 25.6 μm (+0.1 μm) and are available in rolls of either 30 m×0.51 m or 60 m×0.76 m. Such dyed Cellophanes are typically lightfast but can readily be bleached irreversibly by ionizing radiation, as a means of dosimetry using spectrophotometry as the analytical tool. The radiation response is markedly dependent on temperature and relative humidity during irradiation. The reaction is initiated mainly by dehydrogenation and nitrosation upon electrophilic reductive attack on the dye molecule by the thermal electrons, at initial reaction rate constants in the range 10 5-10 6 s -1.

  18. Similarity solution to three dimensional boundary layer flow of second grade nanofluid past a stretching surface with thermal radiation and heat source/sink

    SciTech Connect

    Hayat, T.; Muhammad, Taseer; Shehzad, S. A.; Alsaedi, A.

    2015-01-15

    Development of human society greatly depends upon solar energy. Heat, electricity and water from nature can be obtained through solar power. Sustainable energy generation at present is a critical issue in human society development. Solar energy is regarded one of the best sources of renewable energy. Hence the purpose of present study is to construct a model for radiative effects in three-dimensional of nanofluid. Flow of second grade fluid by an exponentially stretching surface is considered. Thermophoresis and Brownian motion effects are taken into account in presence of heat source/sink and chemical reaction. Results are derived for the dimensionless velocities, temperature and concentration. Graphs are plotted to examine the impacts of physical parameters on the temperature and concentration. Numerical computations are presented to examine the values of skin-friction coefficients, Nusselt and Sherwood numbers. It is observed that the values of skin-friction coefficients are more for larger values of second grade parameter. Moreover the radiative effects on the temperature and concentration are quite reverse.

  19. High-dose external beam radiation for localized prostate cancer: current status and future challenges.

    PubMed

    Nguyen, Paul L; Zietman, Anthony L

    2007-01-01

    Since the 1960s, external beam radiation has been one of the major curative treatment options for patients with clinically localized prostate cancer. Efforts to improve the efficacy of this modality have focused on delivering a higher dose, and several recent randomized trials have confirmed that this higher dose results in improved oncological outcomes, particularly for patients with intermediate-risk disease. Technological advancements over the past 2 decades have allowed highly conformal treatments that spare more normal tissue and reduce early and long-term treatment side effects. In a complementary fashion, methods have been developed for better real-time localization of the prostate such that radiation fields can be shifted before each treatment to match the daily shifts in the position of the target, leading to greater accuracy and allowing for smaller treatment margins that in turn will overlap with less normal tissue. With newer and more expensive technologies such as intensity-modulated radiation therapy and protons being used with increasing frequency for the treatment of prostate cancer, it becomes imperative to study the risks and benefits of each new modality so that informed cost-benefit decisions can be made. Similarly, there has been a growing interest in hypofractionation as a means of exploiting the supposed low alpha/beta ratio of prostate cancer to shorten overall treatment time and thereby improve convenience and lower costs. However, as with any new technology, it is necessary to proceed with caution in the arena of hypofractionation while we await the results of trials that will help us to determine the long-term risks and benefits of hypofractionation and whether biological assumptions about the underlying alpha/beta ratio can translate into a true clinical advantage. PMID:17921728

  20. MESA meets MURaM. Surface effects in main-sequence solar-like oscillators computed using three-dimensional radiation hydrodynamics simulations

    NASA Astrophysics Data System (ADS)

    Ball, W. H.; Beeck, B.; Cameron, R. H.; Gizon, L.

    2016-08-01

    Context. Space-based observations of solar-like oscillators have identified large numbers of stars in which many individual mode frequencies can be precisely measured. However, current stellar models predict oscillation frequencies that are systematically affected by simplified modelling of the near-surface layers. Aims: We use three-dimensional radiation hydrodynamics simulations to better model the near-surface equilibrium structure of dwarfs with spectral types F3, G2, K0 and K5, and examine the differences between oscillation mode frequencies computed in stellar models with and without the improved near-surface equilibrium structure. Methods: We precisely match stellar models to the simulations' gravities and effective temperatures at the surface, and to the temporally- and horizontally-averaged densities and pressures at their deepest points. We then replace the near-surface structure with that of the averaged simulation and compute the change in the oscillation mode frequencies. We also fit the differences using several parametric models currently available in the literature. Results: The surface effect in the stars of solar-type and later is qualitatively similar and changes steadily with decreasing effective temperature. In particular, the point of greatest frequency difference decreases slightly as a fraction of the acoustic cut-off frequency and the overall scale of the surface effect decreases. The surface effect in the hot, F3-type star follows the same trend in scale (i.e. it is larger in magnitude) but shows a different overall variation with mode frequency. We find that a two-term fit using the cube and inverse of the frequency divided by the mode inertia is best able to reproduce the surface terms across all four spectral types, although the scaled solar term and a modified Lorentzian function also match the three cooler simulations reasonably well. Conclusions: Three-dimensional radiation hydrodynamics simulations of near-surface convection can be

  1. Three-dimensional Radiative Transfer Simulations of the Scattering Polarization of the Hydrogen Lyα Line in a Magnetohydrodynamic Model of the Chromosphere-Corona Transition Region

    NASA Astrophysics Data System (ADS)

    Štěpán, J.; Trujillo Bueno, J.; Leenaarts, J.; Carlsson, M.

    2015-04-01

    Probing the magnetism of the upper solar chromosphere requires measuring and modeling the scattering polarization produced by anisotropic radiation pumping in UV spectral lines. Here we apply PORTA (a novel radiative transfer code) to investigate the hydrogen Lyα line in a three-dimensional model of the solar atmosphere resulting from a state of the art magnetohydrodynamic (MHD) simulation. At full spatial resolution the linear polarization signals are very significant all over the solar disk, with a large fraction of the field of view (FOV) showing line-center amplitudes well above the 1% level. Via the Hanle effect the line-center polarization signals are sensitive to the magnetic field of the model's transition region, even when its mean field strength is only 15 G. The breaking of the axial symmetry of the radiation field produces significant forward-scattering polarization in Lyα, without the need of an inclined magnetic field. Interestingly, the Hanle effect tends to decrease such forward-scattering polarization signals in most of the points of the FOV. When the spatial resolution is degraded, the line-center polarization of Lyα drops below the 1% level, reaching values similar to those previously found in one-dimensional (1D) semi-empirical models (i.e., up to about 0.5 %). The center to limb variation (CLV) of the spatially averaged polarization signals is qualitatively similar to that found in 1D models, with the largest line-center amplitudes at μ =cos θ ≈ 0.4 (θ being the heliocentric angle). These results are important, both for designing the needed space-based instrumentation and for a reliable interpretation of future observations of the Lyα polarization.

  2. Three-dimensional non-LTE radiative transfer effects in Fe i lines. III. Line formation in magneto-hydrodynamic atmospheres

    NASA Astrophysics Data System (ADS)

    Holzreuter, R.; Solanki, S. K.

    2015-10-01

    Non-local thermodynamic equilibrium (NLTE) effects in diagnostically important solar Fe i lines are important because of the strong sensitivity of Fe i to ionizing UV radiation, which may lead to a considerable underpopulation of the Fe i levels in the solar atmosphere and, therefore, to a sizeable weakening of Fe i lines. These NLTE effects may be intensified or weakened by horizontal radiative transfer (RT) in a three-dimensionally (3D) structured atmosphere. We analyze the influence of horizontal RT on commonly used Fe i lines in a snapshot of a 3D radiation magneto-hydrodynamic (MHD) simulation of a plage region. NLTE and horizontal RT effects occur with considerable strength (up to 50% in line depth or equivalent width) in the analyzed snapshot. Because they may have either sign, and both signs occur with approximately the same frequency and strength, the net effects are small when considering spatially averaged quantities. The situation in the plage atmosphere turns out to be rather complex. Horizontal transfer leads to line weakening relative to 1D NLTE transfer near the boundaries of kG magnetic elements. Around the centers of these elements, however, we find line strengthening, which is often significant. This behavior contrasts with what is expected from previous 3D RT computations in idealized flux-tube models, which only display line weakening. The origin of this unexpected behavior lies in the fact that magnetic elements are surrounded by dense and relatively cool downflowing gas, which forms the walls of the magnetic elements. The continuum in these dense walls is often formed in colder gas than in the central part of the magnetic elements. Consequently, the central parts of the magnetic element experience a subaverage UV-irradiation leading to the observed 3D NLTE line strengthening.

  3. Black carbon simulations using a size- and mixing-state-resolved three-dimensional model: 1. Radiative effects and their uncertainties

    NASA Astrophysics Data System (ADS)

    Matsui, H.

    2016-02-01

    This study quantifies how uncertainties in the size distribution and mixing state parameters of black carbon (BC) emissions translate into the uncertainties in BC radiative effects by using a particle-size- and mixing-state-resolved three-dimensional model, the Weather Research and Forecasting model with chemistry (WRF-chem) with the Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS) and the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC). The WRF-chem/ATRAS-MOSAIC model can explicitly calculate BC processes in the atmosphere, such as BC aging due to condensation and coagulation and the resulting enhancement of absorption and cloud condensation nuclei activity, with 12 size and 10 BC mixing state bins (128 bins in total). Fifteen model simulations perturbing the emission parameters within their uncertainties are conducted over East Asia (spring 2009) to understand which parameters and processes are important and which are associated with the uncertainty in evaluating BC radiative effects. The simulations reveal a large variability (uncertainty) of BC optical and radiative variables over the East Asian region (the variability is 58-99%), which corresponds to ranges of BC radiative effect of 1.6-2.8 W m-2 at the top of the atmosphere and from -5.2 to -2.1 W m-2 at the surface over East Asia. BC optical and radiative variables are 3 to 5 times sensitive to the size and the mixing state in emissions than BC mass concentrations (the variability is 20%). The two main causes of the difference in sensitivity are the reduction of the variability of BC mass concentrations by coagulation and the enhancement of the variability of BC absorption by resolving BC mixing state. These complicated responses of aerosol processes can be calculated for the first time using a detailed aerosol model such as ATRAS. The results suggest that the following two points are important in the estimation of BC radiative effects: (1) reduction of the

  4. Three-dimensional registration of synchrotron radiation-based micro-computed tomography images with advanced laboratory micro-computed tomography data from murine kidney casts

    NASA Astrophysics Data System (ADS)

    Thalmann, Peter; Hieber, Simone E.; Schulz, Georg; Deyhle, Hans; Khimchenko, Anna; Kurtcuoglu, Vartan; Olgac, Ufuk; Marmaras, Anastasios; Kuo, Willy; Meyer, Eric P.; Beckmann, Felix; Herzen, Julia; Ehrbar, Stefanie; Müller, Bert

    2014-09-01

    Malfunction of oxygen regulation in kidney and liver may lead to the pathogenesis of chronic diseases. The underlying mechanisms are poorly understood. In kidney, it is hypothesized that renal gas shunting from arteries to veins eliminates excess oxygen. Such shunting is highly dependent on the structure of the renal vascular network. The vascular tree has so far not been quantified under maintenance of its connectivity as three-dimensional imaging of the vessel tree down to the smallest capillaries, which in mouse model are smaller than 5 μm in diameter, is a challenging task. An established protocol uses corrosion casts and applies synchrotron radiation-based micro-computed tomography (SRμCT), which provides the desired spatial resolution with the necessary contrast. However, SRμCT is expensive and beamtime access is limited. We show here that measurements with a phoenix nanotomrm (General Electric, Wunstorf, Germany) can provide comparable results to those obtained with SRμCT, except for regions with small vessel structures, where the signal-to-noise level was significantly reduced. For this purpose the nanotom®m measurement was compared with its corresponding measurement acquired at the beamline P05 at PETRA III at DESY, Hamburg, Germany.

  5. A direct comparison of a depth-dependent Radiation stress formulation and a Vortex force formulation within a three-dimensional coastal ocean model

    NASA Astrophysics Data System (ADS)

    Moghimi, Saeed; Klingbeil, Knut; Gräwe, Ulf; Burchard, Hans

    2013-10-01

    In this study a model system consisting of the three-dimensional General Estuarine Transport Model (GETM) and the third generation wind wave model SWAN was developed. Both models were coupled in two-way mode. The effects of waves were included into the ocean model by implementing the depth-dependent Radiation stress formulation (RS) of Mellor (2011a) and the Vortex force formulation (VF) presented by Bennis et al. (2011). Thus, the developed model system offers a direct comparison of these two formulations. The enhancement of the vertical eddy viscosity due to the energy transfer by white capping and breaking waves was taken into account by means of injecting turbulent kinetic energy at the surface. Wave-current interaction inside the bottom boundary layer was considered as well. The implementation of both wave-averaged formulations was validated against three flume experiments. One of these experiments with long period surface waves (swell), had not been evaluated before. The validation showed the capability of the model system to reproduce the three-dimensional interaction of waves and currents. For the flume test cases the wave-induced water level changes (wave set-up and set-down) and the corresponding depth-integrated wave-averaged velocities were similar for RS and VF. Both formulations produced comparable velocity profiles for short period waves. However, for large period waves, VF overestimated the wave set-down near the main breaking points and RS showed artificial offshore-directed transport at the surface where wave shoaling was taking place. Finally the validated model system was applied to a realistic barred beach scenario. For RS and VF the resulting velocity profiles were similar after being significantly improved by a roller evolution method. Both wave-averaged formulations generally provided similar results, but some shortcomings were revealed. Although VF partly showed significant deviations from the measurements, its results were still physically

  6. Pulmonary Artery Invasion, High-Dose Radiation, and Overall Survival in Patients With Non-Small Cell Lung Cancer

    SciTech Connect

    Han, Cheng-Bo; Wang, Wei-Li; Quint, Leslie; Xue, Jian-Xin; Matuszak, Martha; Ten Haken, Randall; Kong, Feng-Ming

    2014-06-01

    Purpose: To investigate whether high-dose radiation to the pulmonary artery (PA) affects overall survival (OS) in patients with non-small cell lung cancer (NSCLC). Methods and Materials: Patients with medically inoperable/unresectable NSCLC treated with definitive radiation therapy in prospective studies were eligible for this study. Pulmonary artery involvement was defined on the basis of pretreatment chest CT and positron emission tomography/CT fusion. Pulmonary artery was contoured according to the Radiation Therapy Oncology Group protocol 1106 atlas, and dose-volume histograms were generated. Results: A total of 100 patients with a minimum follow-up of 1 year for surviving patients were enrolled: 82.0% underwent concurrent chemoradiation therapy. Radiation dose ranged from 60 to 85.5 Gy in 30-37 fractions. Patients with PA invasion of grade ≤2, 3, 4, and 5 had 1-year OS and median survival of 67% and 25.4 months (95% confidence interval [CI] 15.7-35.1), 62% and 22.2 months (95% CI 5.8-38.6), 90% and 35.8 months (95% CI 28.4-43.2), and 50% and 7.0 months, respectively (P=.601). Two of the 4 patients with grade 5 PA invasion died suddenly from massive hemorrhage at 3 and 4.5 months after completion of radiation therapy. Maximum and mean doses to PA were not significantly associated with OS. The V45, V50, V55, and V60 of PA were correlated significantly with a worse OS (P<.05). Patients with V45 >70% or V60 >37% had significantly worse OS (13.3 vs 37.9 months, P<.001, and 13.8 vs 37.9 months, P=.04, respectively). Conclusions: Grade 5 PA invasion and PA volume receiving more than 45-60 Gy may be associated with inferior OS in patients with advanced NSCLC treated with concurrent chemoradiation.

  7. Three dimensional Dirac semimetals

    NASA Astrophysics Data System (ADS)

    Zaheer, Saad

    We extend the physics of graphene to three dimensional systems by showing that Dirac points can exist on the Fermi surface of realistic materials in three dimensions. Many of the exotic electronic properties of graphene can be ascribed to the pseudorelativistic behavior of its charge carriers due to two dimensional Dirac points on the Fermi surface. We show that certain nonsymmorphic spacegroups exhibit Dirac points among the irreducible representations of the appropriate little group at high symmetry points on the surface of the Brillouin zone. We provide a list of all Brillouin zone momenta in the 230 spacegroups that can host Dirac points. We describe microscopic considerations necessary to design materials in one of the candidate spacegroups such that the Dirac point appears at the Fermi energy without any additional non-Dirac-like Fermi pockets. We use density functional theory based methods to propose six new Dirac semimetals: BiO 2 and SbO2 in the beta-cristobalite lattice (spacegroup 227), and BiCaSiO4, BiMgSiO4, BiAlInO 4, and BiZnSiO4 in the distorted spinels lattice (spacegroup 74). Additionally we derive effective Dirac Hamiltonians given group representative operators as well as tight binding models incorporating spin-orbit coupling. Finally we study the Fermi surface of zincblende (spacegroup 216) HgTe which is effectively point-like at Gamma in the Brillouin zone and exhibits accidental degeneracies along a threefold rotation axis. Whereas compressive strain gaps the band structure into a topological insulator, tensile strain shifts the accidental degeneracies away from Gamma and enlarges the Fermi surface. States on the Fermi surface exhibit nontrivial spin texture marked by winding of spins around the threefold rotation axis and by spin vortices indicating a change in the winding number. This is confirmed by microscopic calculations performed in tensile strained HgTe and Hg0.5Zn 0.5 Te as well as k.p theory. We conclude with a summary of recent

  8. Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D)

    PubMed Central

    Shen, Hesong; Dai, Guochao; Luo, Mingyue; Duan, Chaijie; Cai, Wenli; Liang, Dan; Wang, Xinhua; Zhu, Dongyun; Li, Wenru; Qiu, Jianping

    2015-01-01

    Purpose To investigate image quality and radiation dose of CT coronary angiography (CTCA) scanned using automatic tube current modulation (ATCM) and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Eighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP) respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product. Results Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05); compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001). Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%), 486 (96.4%), and 394 (93.8%) in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%), 472 (93.7%), 378 (90.0%), respectively; those for FBP were 217 (64.6%), 173 (34.3%), 114 (27.1%), respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5%) were higher than those of standard AIDR3D (1182, 93.8%) and FBP (504, 40.0%); the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001). The mean effective radiation dose was (2.55±1.21) mSv. Conclusion

  9. Synchrotron radiation micro-CT at the micrometer scale for the analysis of the three-dimensional morphology of microcracks in human trabecular bone.

    PubMed

    Larrue, Aymeric; Rattner, Aline; Peter, Zsolt-Andrei; Olivier, Cécile; Laroche, Norbert; Vico, Laurence; Peyrin, Françoise

    2011-01-01

    Bone quality is an important concept to explain bone fragility in addition to bone mass. Among bone quality factors, microdamage which appears in daily life is thought to have a marked impact on bone strength and plays a major role in the repair process. The starting point for all studies designed to further our understanding of how bone microdamage initiate or dissipate energy, or to investigate the impact of age, gender or disease, remains reliable observation and measurement of microdamage. In this study, 3D Synchrotron Radiation (SR) micro-CT at the micrometric scale was coupled to image analysis for the three-dimensional characterization of bone microdamage in human trabecular bone specimens taken from femoral heads. Specimens were imaged by 3D SR micro-CT with a voxel size of 1.4 µm. A new tailored 3D image analysis technique was developed to segment and quantify microcracks. Microcracks from human trabecular bone were observed in different tomographic sections as well as from 3D renderings. New 3D quantitative measurements on the microcrack density and morphology are reported on five specimens. The 3D microcrack density was found between 3.1 and 9.4/mm3 corresponding to a 2D density between 0.55 and 0.76 /mm2. The microcrack length and width measured in 3D on five selected microcrack ranged respectively from 164 µm to 209 µm and 100 µm to 120 µm. This is the first time that various microcracks in unloaded human trabecular bone--from the simplest linear crack to more complex cross-hatch cracks--have been examined and quantified by 3D imaging at this scale. The suspected complex morphology of microcracks is here considerably more evident than in the 2D observations. In conclusion, this technique opens new perspective for the 3D investigation of microcracks and the impact of age, disease or treatment. PMID:21750707

  10. Four-Year Efficacy, Cosmesis, and Toxicity Using Three-Dimensional Conformal External Beam Radiation Therapy to Deliver Accelerated Partial Breast Irradiation

    SciTech Connect

    Chen, Peter Y.; Wallace, Michelle; Mitchell, Christina; Grills, Inga; Kestin, Larry; Fowler, Ashley; Martinez, Alvaro; Vicini, Frank

    2010-03-15

    Purpose: This prospective study examines the use of three-dimensional conformal external beam radiation therapy (3D-CRT) to deliver accelerated partial breast irradiation (APBI). Four-year data on efficacy, cosmesis, and toxicity are presented. Methods: Patients with Stage O, I, or II breast cancer with lesions <=3 cm, negative margins, and negative nodes were eligible. The 3D-CRT delivered was 38.5 Gy in 3.85 Gy/fraction. Ipsilateral breast, ipsilateral nodal, contralateral breast, and distant failure (IBF, INF, CBF, DF) were estimated using the cumulative incidence method. Disease-free, overall, and cancer-specific survival (DFS, OS, CSS) were recorded. The National Cancer Institute Common Terminology Criteria for Adverse Events (version 3) toxicity scale was used to grade acute and late toxicities. Results: Ninety-four patients are evaluable for efficacy. Median patient age was 62 years with the following characteristics: 68% tumor size <1 cm, 72% invasive ductal histology, 77% estrogen receptor (ER) (+), 88% postmenopausal; 88% no chemotherapy and 44% with no hormone therapy. Median follow-up was 4.2 years (range, 1.3-8.3). Four-year estimates of efficacy were IBF: 1.1% (one local recurrence); INF: 0%; CBF: 1.1%; DF: 3.9%; DFS: 95%; OS: 97%; and CSS: 99%. Four (4%) Grade 3 toxicities (one transient breast pain and three fibrosis) were observed. Cosmesis was rated good/excellent in 89% of patients at 4 years. Conclusions: Four-year efficacy, cosmesis, and toxicity using 3D-CRT to deliver APBI appear comparable to other experiences with similar follow-up. However, additional patients, further follow-up, and mature Phase III data are needed to evaluate thoroughly the extent of application, limitations, and complete value of this particular form of APBI.

  11. Prediction of radiation-induced liver disease by Lyman normal-tissue complication probability model in three-dimensional conformal radiation therapy for primary liver carcinoma

    SciTech Connect

    Xu ZhiYong; Liang Shixiong; Zhu Ji; Zhu Xiaodong; Zhao Jiandong; Lu Haijie; Yang Yunli; Chen Long; Wang Anyu; Fu Xiaolong; Jiang Guoliang . E-mail: jianggl@21cn.com

    2006-05-01

    Purpose: To describe the probability of RILD by application of the Lyman-Kutcher-Burman normal-tissue complication (NTCP) model for primary liver carcinoma (PLC) treated with hypofractionated three-dimensional conformal radiotherapy (3D-CRT). Methods and Materials: A total of 109 PLC patients treated by 3D-CRT were followed for RILD. Of these patients, 93 were in liver cirrhosis of Child-Pugh Grade A, and 16 were in Child-Pugh Grade B. The Michigan NTCP model was used to predict the probability of RILD, and then the modified Lyman NTCP model was generated for Child-Pugh A and Child-Pugh B patients by maximum-likelihood analysis. Results: Of all patients, 17 developed RILD in which 8 were of Child-Pugh Grade A, and 9 were of Child-Pugh Grade B. The prediction of RILD by the Michigan model was underestimated for PLC patients. The modified n, m, TD{sub 5} (1) were 1.1, 0.28, and 40.5 Gy and 0.7, 0.43, and 23 Gy for patients with Child-Pugh A and B, respectively, which yielded better estimations of RILD probability. The hepatic tolerable doses (TD{sub 5}) would be MDTNL of 21 Gy and 6 Gy, respectively, for Child-Pugh A and B patients. Conclusions: The Michigan model was probably not fit to predict RILD in PLC patients. A modified Lyman NTCP model for RILD was recommended.

  12. High-dose mode of mortality in Tribolium: A model system for study of radiation injury and repair in non-proliferative tissues

    SciTech Connect

    Cheng, Chihing Christina.

    1989-01-01

    With appropriate doses of ionizing radiation, both the acute, or lethal-midlethal, dose-independent pattern of mortality, and the hyperacute, dose-dependent pattern, were demonstrated within a single insect genus (Tribolium). This demonstration provides resolution of apparently contradictory reports of insect radiation responses in terms of doses required to cause lethality and those based on survival time as a function of dose. A dose-dependent mortality pattern was elicited in adult Tribolium receiving high doses, viz., 300 Gy or greater; its time course was complete in 10 days, before the dose-independent pattern of mortality began. Visual observations of heavily-irradiated Tribolium suggested neural and/or neuromuscular damage, as had been previously proposed by others for lethally-irradiated wasps, flies, and mosquitoes. Results of experiments using fractionated high doses supported the suggestion that the hyperacute or high-dose mode of death is the result of damage to nonproliferative tissues. Relative resistance of a strain to the hyperacute or high-dose mode of death was not correlated with resistance to the midlethal mode, which is believed to be the result of damage to the proliferative cells of the midgut. Using the high-dose mode of death as a model of radiation damage to nonproliferative tissues, the effects of age, and of a moderate priming dose were assessed. Beetles showed age-related increase in sensitivity to the high-dose mode of death, suggesting a decline in capacity to repair radiation damage to postmitotic tissue. This correlated with a decrease (50%) in the amount of repair reflected in the sparing effect of dose-fractionation (SDF) between the age of 1 to 3 months. The age related increase in radiosensitivity was reduced by a moderate priming dose (40 or 65 Gy) given at a young age.

  13. WE-E-BRE-06: High-Dose Microbeam Radiation Induces Different Responses in Tumor Microenvironment Compared to Conventional Seamless Radiation in Window Chamber Tumor Models

    SciTech Connect

    Chang, S; Zhang, J; Hadsell, M; Fontanella, A; Schroeder, T; Palmer, G; Dewhirst, M; Boss, M; Berman, K

    2014-06-15

    Purpose: Microbeam radiation therapy and GRID therapy are different forms of Spatially-Fractioned Radiation Therapy (SFRT) that is fundamentally different from the conventional seamless and temporally fractionated radiation therapy. SFRT is characterized by a ultra-high dose (10s –100s Gy) dose single treatment with drastic inhomogeneity pattern of given spatial frequencies. Preclinical and limited clinical studies have shown that the SFRT treatments may offer significant improvements in reducing treatment toxicity, especially for those patients who have not benefited from the state-of-the-art radiation therapy approaches. This preliminary study aims to elucidate the underlying working mechanisms of SFRT, which currently remains poorly understood. Methods: A genetically engineered 4T1 murine mammary carcinoma cell line and nude mice skin fold window chamber were used. A nanotechnology-based 160kV x-ray irradiator delivered 50Gy (entrance dose) single treatments of microbeam or seamless radiation. Animals were in 3 groups: mock, seamless radiation, and 300μm microbeam radiation. The windows were imaged using a hyperspectral system to capture total hemoglobin/saturation, GFP fluorescence emission, RFP fluorescence emission, and vessel density at 9 time points up to 7 days post radiation. Results: We found unique physiologic changes in different tumor/normal tissue regions and differential effects between seamless and microbeam treatments. They include 1) compared to microbeam and mock radiation seamless radiation damaged more microvasculature in tumor-surrounding normal tissue, 2) a pronounced angiogenic effect was observed with vascular proliferation in the microbeam irradiated portion of the tumor days post treatment (no such effect observed in seamless and mock groups), and 3) a notable change in tumor vascular orientation was observed where vessels initially oriented parallel to the beam length were replaced by vessels running perpendicular to the irradiation

  14. Phase I Three-Dimensional Conformal Radiation Dose Escalation Study in Newly Diagnosed Glioblastoma: Radiation Therapy Oncology Group Trial 98-03

    SciTech Connect

    Tsien, Christina Moughan, Jennifer; Michalski, Jeff M.; Gilbert, Mark R.; Purdy, James; Simpson, Joseph; Kresel, John J.; Curran, Walter J.; Diaz, Aidnag; Mehta, Minesh P.

    2009-03-01

    Purpose: To evaluate in a Phase I trial the feasibility and toxicity of dose-escalated three-dimensional conformal radiotherapy (3D-CRT) concurrent with chemotherapy in patients with primary supratentorial glioblastoma (GBM). Methods and Materials: A total of 209 patients were enrolled. All received 46 Gy in 2-Gy fractions to the first planning target volume (PTV{sub 1}), defined as the gross tumor volume (GTV) plus 1.8 cm. A subsequent boost was given to PTV{sub 2}, defined as GTV plus 0.3 cm. Patients were stratified into two groups (Group 1: PTV{sub 2} <75 cm{sup 3}; Group 2: PTV{sub 2} {>=}75 cm{sup 3}). Four RT dose levels were evaluated: 66, 72, 78, and 84 Gy. Carmustine 80 mg/m{sup 2} was given during RT, then every 8 weeks for 6 cycles. Pretreatment characteristics were well balanced. Results: Acute and late Grade 3/4 RT-related toxicities were no more frequent at higher RT dose or with larger tumors. There were no dose-limiting toxicities (acute Grade {>=}3 irreversible central nervous system toxicities) observed on any dose level in either group. On the basis of the absence of dose-limiting toxicities, dose was escalated to 84 Gy in both groups. Late RT necrosis was noted at 66 Gy (1 patient), 72 Gy (2 patients), 78 Gy (2 patients), and 84 Gy (3 patients) in Group 1. In Group 2, late RT necrosis was noted at 78 Gy (1 patient) and 84 Gy (2 patients). Median time to RT necrosis was 8.8 months (range, 5.1-12.5 months). Median survival in Group 1 was 11.6-19.3 months. Median survival in Group 2 was 8.2-13.9 months. Conclusions: Our study shows the feasibility of delivering higher than standard (60 Gy) RT dose with concurrent chemotherapy for primary GBM, with an acceptable risk of late central nervous system toxicity.

  15. The Value of Botox-A in Acute Radiation Proctitis: Results From a Phase I/II Study Using a Three-Dimensional Scoring System

    SciTech Connect

    Vuong, Te; Waschke, Kevin; Niazi, Tamim; Richard, Carole; Parent, Josee; Liberman, Sender; Mayrand, Serge; Loungnarath, Rasmy; Stein, Barry; Devic, Slobodan

    2011-08-01

    Purpose: Acute radiation proctitis (ARP) is a common side effect of pelvic radiotherapy, and its management is challenging in daily practice. The present phase I/II study evaluates the safety and efficacy of the botulinum toxin A (BTX-A) in ARP treatment for rectal cancer patients undergoing neoadjuvant high-dose-rate endorectal brachytherapy (HDREBT). Methods and Materials: Fifteen patients, treated with neoadjuvant HDREBT, 26-Gy in 4 fractions, received the study treatment that consisted of a single injection of BTX-A into the rectal wall. The injection was performed post-HDREBT and prior to the development of ARP. The control group, 20 such patients, did not receive the BTX-A injection. Both groups had access to standard treatment with hydrocortisone rectal aerosol foam (Cortifoam) and anti-inflammatory and narcotic medication. The ARP was clinically evaluated by self-administered daily questionnaires using visual analog scores to document frequency and urgency of bowel movements, rectal burning/tenesmus, and pain symptoms before and after HDREBT. Results: At the time of this analysis, there was no observed systemic toxicity. Patient compliance with the self-administered questionnaire was 100% from week 1 to 4, 70% during week 5, and 40% during week 6. The maximum tolerated dose was established at the 100-U dose level, and noticeable mean differences were observed in bowel frequency (p = 0.016), urgency (p = 0.007), and pain (p = 0.078). Conclusions: This study confirms the feasibility and efficacy of BTX-A intervention at 100-U dose level for study patients compared to control patients. A phase III study with this dose level is planned to validate these results.

  16. Improvement of Survival Rate for Patients with Hepatocellular Carcinoma Using Transarterial Chemoembolization in Combination with Three-Dimensional Conformal Radiation Therapy: A Meta-Analysis.

    PubMed

    Bai, Houqiao; Gao, Peng; Gao, Hao; Sun, Guangxi; Dong, Chonghai; Han, Jian; Jiang, Guosheng

    2016-01-01

    BACKGROUND Transarterial chemoembolization (TACE) has been used alone or in combination with three-dimensional conformal radiation therapy (3DCRT) for treating hepatocellular carcinoma (HCC). The overall survival rate of HCC patients undergoing both treatments, however, has not been systematically studied. The aim of this meta-analysis-based study was to evaluate the overall efficacy of the combined therapy or monotherapy, thereby providing information for clinical treatment. MATERIAL AND METHODS We searched Google Scholar, PubMed, and Chinese National Knowledge Infrastructure (CNKI) for eligible studies, and a total of 17 case-control studies (including HCC patients treated by TACE plus 3DCRT or TACE alone) were included to perform the meta-analysis. Based on the available data, we assessed the improvements of 1-year, 2-year, and 3-year survival rate for the combination therapy of TACE and 3DCRT or TACE alone. Furthermore, the analysis was also stratified by the tumor response: complete response (CR), partial response (PR), no response (NR) and progressive disease (PD). Statistical analysis was performed using STATA 12 (Stata Statistical Software: Release 12). RESULTS The results show that HCC patients receiving combination therapy have significantly increased overall survival rate when compared to those receiving TACE alone (1-year survival rate: OR=1.95, 95% CI 1.54-2.47, p=7.3×10^-8; 2-year survival rate: OR=1.87, 95% CI 1.49-2.34, p=1.6×10^-7; 3-year survival rate: OR=2.00, 95% CI 1.52-2.64, p=1.8×10^-6). CONCLUSIONS Assessment of tumor response demonstrates that the combination therapy can efficiently increase the tumor response rate (CR+PR: OR=2.29, 95% CI 1.70-3.08, p=1.1×10^-7), with a lower rate of subsequent tumor development (PD: OR=0.25, 95% CI 0.15-0.40, p=5.5×10^-8). PMID:27228411

  17. Dose-Rate Dependence of High-Dose Health Effects in Humans from Photon Radiation with Application to Radiological Terrorism

    SciTech Connect

    Strom, Daniel J.

    2005-01-14

    In 1981, as part of a symposium entitled ''The Control of Exposure of the Public to Ionizing Radiation in the Event of Accident or Attack,'' Lushbaugh, H?bner, and Fry published a paper examining ''radiation tolerance'' of various human health endpoints as a function of dose rate. This paper may not have received the notice it warrants. The health endpoints examined by Lushbaugh et al. were the lethal dose that will kill 50% of people within 60 days of exposure without medical care (LD50/60); severe bone marrow damage in healthy men; severe bone marrow damage in leukemia patients; temporary sterility (azoospermia); reduced male fertility; and late effects such as cancer. Their analysis was grounded in extensive clinical experience and anchored to a few selected data points, and based on the 1968 dose-rate dependence theory of J.L. Bateman. The Lushbaugh et al. paper did not give predictive equations for the relationships, although they were implied in the text, and the relationships were presented in a non-intuitive way. This work derives the parameters needed in Bateman's equation for each health endpoint, tabulates the results, and plots them in a more conventional manner on logarithmic scales. The results give a quantitative indication of how the human organism can tolerate more radiation dose when it is delivered at lower dose rates. For example, the LD50/60 increases from about 3 grays (300 rads) when given at very high dose rates to over 10 grays (1,000 rads) when given at much lower dose rates over periods of several months. The latter figure is borne out by the case of an individual who survived for at least 19 years after receiving doses in the range of 9 to 17 grays (900-1700 rads) over 106 days. The Lushbaugh et al. work shows the importance of sheltering when confronted with long-term exposure to radiological contamination such as would be expected from a radiological dispersion event, reactor accident, or ground-level nuclear explosion.

  18. Lack of benefit of pelvic radiation in prostate cancer patients with a high risk of positive pelvic lymph nodes treated with high-dose radiation

    SciTech Connect

    Vargas, Carlos Enrique; Galalae, Razavan; Demanes, Jeffrey; Harsolia, Asif; Meldolesi, Elisa; Nuernberg, Nils; Schour, Lionel; Martinez, Alvaro . E-mail: amartinez@beaumont.edu

    2005-12-01

    Purpose: The use of pelvic radiation for patients with a high risk of lymph node (LN) metastasis (>15%) remains controversial. We reviewed the data at three institutions treating patients with a combination of external-beam radiation therapy and high-dose-rate brachytherapy to address the prognostic implications of the use of the Roach formula and the benefit of pelvic treatment. Methods and Materials: From 1986 to 2003, 1,491 patients were treated with external-beam radiation therapy and high-dose-rate brachytherapy. The Roach formula [2/3 prostate-specific antigen + (Gleason score -6) x 10] could be calculated for 1,357 patients. Group I consisted of patients having a risk of positive LN {<=}15% (n = 761), Group II had a risk >15% and {<=}30% (n = 422), and Group III had a risk of LN disease >30% (n 174). A >15% risk of having positive LN was found in 596 patients and was used to determine the benefit of pelvic radiation. The pelvis was treated at two of the cancer centers (n = 312), whereas at the third center (n = 284) radiation therapy was delivered to the prostate and seminal vesicles alone. Average biologic effective dose was {>=}100 Gy ({alpha}{beta} = 1.2). Biochemical failure was as per the American Society for Therapeutic Radiology and Oncology definition. Statistics included the log-rank test as well as Cox univariate and multivariate analysis. Results: For all 596 patients with a positive LN risk >15%, median follow-up was 4.3 years, with a mean of 4.8 years. For all cases, median follow-up was 4 years and mean follow-up was 4.4 years. Five-year results for the three groups based on their risk of positive LN were significantly different in terms of biochemical failure (p < 0.001), clinical control (p < 0.001), disease-free survival excluding biochemical failure (p < 0.001), cause-specific survival (p < 0.001), and overall survival (p < 0.001). For all patients with a risk of positive LN >15% (n 596), Group II (>15-30% risk), or Group III (>30% risk

  19. Image guided radiation therapy boost in combination with high-dose-rate intracavitary brachytherapy for the treatment of cervical cancer

    PubMed Central

    Wang, Xianliang; Li, Jie; Yuan, Ke; Yin, Gang; Wan, Bin

    2016-01-01

    Purpose The purpose of this study was to demonstrate the dosimetric and clinical feasibility of image guided radiation therapy (IGRT) combined with high-dose-rate (HDR) intracavitary brachytherapy (ICBT) to improve dose distribution in cervical cancer treatment. Material and methods For 42 cervical cancer patients, magnetic resonance imaging (MRI) scans were acquired after completion of whole pelvic irradiation 45-46 Gy and 5 fractions of B + I (ICBT + IGRT) treatment were subsequently received. The high risk clinical target volume (HRCTV), intermediate risk clinical target volume (IRCTV), bladder, rectum, and sigmoid were contoured on the computed tomography (CT) scans. The total planning aim doses for HRCTV was D90% > 85 Gy, whilst constraints for rectum and sigmoid were D2cc < 75 Gy and D2cc < 90 Gy for bladder in terms of an equivalent dose in 2 Gy (EQD2) for external beam radiotherapy (EBRT) and brachytherapy boost. The IGRT plan was optimized on top of the ICBT dose distribution. A dosimetric comparison was made between B + I and optimized ICBT (O-ICBT) only. Results The mean D90% of HRCTV was comparable for B + I and O-ICBT (p = 0.82). For B + I plan, HRCTV D100%, IRCTV D100%, and IRCTV D90% were significantly increased by a mean of 10.52 Gy, 5.61 Gy, and 2.70 Gy, respectively (p < 0.01). The D2cc for bladder, rectum, and sigmoid were lower by a mean of 21.36, 6.78, and 10.65 Gy, respectively (p < 0.01). The mean rectum V60 Gy value over 42 patients was almost the same for both techniques but for bladder and sigmoid B + I had higher V60 Gy mean values as compared with the O-ICBT. Conclusions B + I can improve dose distribution in cervical cancer treatment; it could be useful for tumors extended beyond the reach of intracavitary/interstitial brachytherapy (IC/ISBT) or for centers that are inexperienced or ill-equipped with IC/ISBT techniques. Additional confirmatory prospective studies with larger numbers of patients and longer follow-up are required to

  20. Patterns of Recurrence Analysis in Newly Diagnosed Glioblastoma Multiforme After Three-Dimensional Conformal Radiation Therapy With Respect to Pre-Radiation Therapy Magnetic Resonance Spectroscopic Findings

    SciTech Connect

    Park, Ilwoo; Chuang, Cynthia F.; Chang, Susan M.; Berger, Mitchel S.; Nelson, Sarah J.

    2007-10-01

    Purpose: To determine whether the combined magnetic resonance imaging (MRI) and magnetic resonance spectroscopy imaging (MRSI) before radiation therapy (RT) is valuable for RT target definition, and to evaluate the feasibility of replacing the current definition of uniform margins by custom-shaped margins based on the information from MRI and MRSI. Methods and Materials: A total of 23 glioblastoma multiforme (GBM) patients underwent MRI and MRSI within 4 weeks after surgery but before the initiation of RT and at 2-month follow-up intervals thereafter. The MRSI data were quantified on the basis of a Choline-to-NAA Index (CNI) as a measure of spectroscopic abnormality. A combined anatomic and metabolic region of interest (MRI/S) consisting of T2-weighted hyperintensity, contrast enhancement (CE), resection cavity, and CNI2 (CNI {>=} 2) based on the pre-RT imaging was compared to the extent of CNI2 and the RT dose distribution. The spatial relationship of the pre-RT MRI/S and the RT dose volume was compared with the extent of CE at each follow-up. Results: Nine patients showed new or increased CE during follow-up, and 14 patients were either stable or had decreased CE. New or increased areas of CE occurred within CNI2 that was covered by 60 Gy in 6 patients and within the CNI2 that was not entirely covered by 60 Gy in 3 patients. New or increased CE resided within the pre-RT MRI/S lesion in 89% (8/9) of the patients with new or increased CE. Conclusion: These data indicate that the definition of RT target volumes according to the combined morphologic and metabolic abnormality may be sufficient for RT targeting.

  1. Three-dimensional marginal separation

    NASA Technical Reports Server (NTRS)

    Duck, Peter W.

    1988-01-01

    The three dimensional marginal separation of a boundary layer along a line of symmetry is considered. The key equation governing the displacement function is derived, and found to be a nonlinear integral equation in two space variables. This is solved iteratively using a pseudo-spectral approach, based partly in double Fourier space, and partly in physical space. Qualitatively, the results are similar to previously reported two dimensional results (which are also computed to test the accuracy of the numerical scheme); however quantitatively the three dimensional results are much different.

  2. Three-dimensional silicon micromachining

    NASA Astrophysics Data System (ADS)

    Azimi, S.; Song, J.; Dang, Z. Y.; Liang, H. D.; Breese, M. B. H.

    2012-11-01

    A process for fabricating arbitrary-shaped, two- and three-dimensional silicon and porous silicon components has been developed, based on high-energy ion irradiation, such as 250 keV to 1 MeV protons and helium. Irradiation alters the hole current flow during subsequent electrochemical anodization, allowing the anodization rate to be slowed or stopped for low/high fluences. For moderate fluences the anodization rate is selectively stopped only at depths corresponding to the high defect density at the end of ion range, allowing true three-dimensional silicon machining. The use of this process in fields including optics, photonics, holography and nanoscale depth machining is reviewed.

  3. Radiation-induced lung fibrosis after treatment of small cell carcinoma of the lung with very high-dose cyclophosphamide

    SciTech Connect

    Trask, C.W.; Joannides, T.; Harper, P.G.; Tobias, J.S.; Spiro, S.G.; Geddes, D.M.; Souhami, R.L.; Beverly, P.C.

    1985-01-01

    Twenty-five previously untreated patients with small cell carcinoma of the lung were treated with cyclophosphamide 160 to 200 mg/kg (with autologous bone marrow support) followed by radiotherapy (4000 cGy) to the primary site and mediastinum. No other treatment was given until relapse occurred. Nineteen patients were assessable at least 4 months after radiotherapy; of these, 15 (79%) developed radiologic evidence of fibrosis, which was symptomatic in 14 (74%). The time of onset of fibrosis was related to the volume of lung irradiated. A retrospective analysis was made of 20 consecutive patients treated with multiple-drug chemotherapy and an identical radiotherapy regimen as part of a randomized trial. Radiologic and symptomatic fibrosis was one half as frequent (35%) as in the high-dose cyclophosphamide group. Very high-dose cyclophosphamide appears to sensitize the lung to radiotherapy and promotes the production of fibrosis.

  4. Three dimensional colorimetric assay assemblies

    SciTech Connect

    Charych, D.; Reichart, A.

    2000-06-27

    A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

  5. Creating Three-Dimensional Scenes

    ERIC Educational Resources Information Center

    Krumpe, Norm

    2005-01-01

    Persistence of Vision Raytracer (POV-Ray), a free computer program for creating photo-realistic, three-dimensional scenes and a link for Mathematica users interested in generating POV-Ray files from within Mathematica, is discussed. POV-Ray has great potential in secondary mathematics classrooms and helps in strengthening students' visualization…

  6. Three-dimensional stellarator codes

    PubMed Central

    Garabedian, P. R.

    2002-01-01

    Three-dimensional computer codes have been used to develop quasisymmetric stellarators with modular coils that are promising candidates for a magnetic fusion reactor. The mathematics of plasma confinement raises serious questions about the numerical calculations. Convergence studies have been performed to assess the best configurations. Comparisons with recent data from large stellarator experiments serve to validate the theory. PMID:12140367

  7. Three dimensional colorimetric assay assemblies

    DOEpatents

    Charych, Deborah; Reichart, Anke

    2000-01-01

    A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

  8. Three-Dimensional Lissajous Figures.

    ERIC Educational Resources Information Center

    D'Mura, John M.

    1989-01-01

    Described is a mechanically driven device for generating three-dimensional harmonic space figures with different frequencies and phase angles on the X, Y, and Z axes. Discussed are apparatus, viewing stereo pairs, equations of motion, and using space figures in classroom. (YP)

  9. A Treatment Planning Method for Sequentially Combining Radiopharmaceutical Therapy and External Radiation Therapy;External beam therapy; Radiopharmaceutical therapy; Three-dimensional dosimetry; Treatment planning

    SciTech Connect

    Hobbs, Robert F.; McNutt, Todd; Baechler, Sebastien; He Bin; Esaias, Caroline E.; Frey, Eric C.; Loeb, David M.; Wahl, Richard L.; Shokek, Ori; Sgouros, George

    2011-07-15

    Purpose: Effective cancer treatment generally requires combination therapy. The combination of external beam therapy (XRT) with radiopharmaceutical therapy (RPT) requires accurate three-dimensional dose calculations to avoid toxicity and evaluate efficacy. We have developed and tested a treatment planning method, using the patient-specific three-dimensional dosimetry package 3D-RD, for sequentially combined RPT/XRT therapy designed to limit toxicity to organs at risk. Methods and Materials: The biologic effective dose (BED) was used to translate voxelized RPT absorbed dose (D{sub RPT}) values into a normalized total dose (or equivalent 2-Gy-fraction XRT absorbed dose), NTD{sub RPT} map. The BED was calculated numerically using an algorithmic approach, which enabled a more accurate calculation of BED and NTD{sub RPT}. A treatment plan from the combined Samarium-153 and external beam was designed that would deliver a tumoricidal dose while delivering no more than 50 Gy of NTD{sub sum} to the spinal cord of a patient with a paraspinal tumor. Results: The average voxel NTD{sub RPT} to tumor from RPT was 22.6 Gy (range, 1-85 Gy); the maximum spinal cord voxel NTD{sub RPT} from RPT was 6.8 Gy. The combined therapy NTD{sub sum} to tumor was 71.5 Gy (range, 40-135 Gy) for a maximum voxel spinal cord NTD{sub sum} equal to the maximum tolerated dose of 50 Gy. Conclusions: A method that enables real-time treatment planning of combined RPT-XRT has been developed. By implementing a more generalized conversion between the dose values from the two modalities and an activity-based treatment of partial volume effects, the reliability of combination therapy treatment planning has been expanded.

  10. Three-dimensional fault drawing

    SciTech Connect

    Dongan, L. )

    1992-01-01

    In this paper, the author presents a structure interpretation based on three-dimensional fault drawing. It is required that fault closure must be based on geological theory, spacial plotting principle and restrictions in seismic exploration. Geological structure can be well ascertained by analysing the shapes and interrelation of the faults which have been drawn through reasonable fault point closure and fault point correlation. According to this method, the interrelation of fault points is determined by first closing corresponding fault points in intersecting sections, then reasonably correlating the relevant fault points. Fault point correlation is not achieved in base map, so its correctness can be improved greatly. Three-dimensional fault closure is achieved by iteratively revising. The closure grid should be densified gradually. The distribution of major fault system is determined prior to secondary faults. Fault interpretation by workstation also follows this procedure.

  11. Three-dimensional obstetric ultrasound.

    PubMed

    Tache, Veronique; Tarsa, Maryam; Romine, Lorene; Pretorius, Dolores H

    2008-04-01

    Three-dimensional ultrasound has gained a significant popularity in obstetrical practice in recent years. The advantage of this modality in some cases is in question, however. This article provides a basic review of volume acquisition, mechanical positioning, and display modalities. Multiple uses of this technique in obstetrical care including first trimester applications and its utility in clarification of fetal anatomy such as brain, face, heart, and skeleton is discussed. PMID:18450140

  12. Three-dimensional coronary angiography

    NASA Astrophysics Data System (ADS)

    Suurmond, Rolf; Wink, Onno; Chen, James; Carroll, John

    2005-04-01

    Three-Dimensional Coronary Angiography (3D-CA) is a novel tool that allows clinicians to view and analyze coronary arteries in three-dimensional format. This will help to find accurate length estimates and to find the optimal viewing angles of a lesion based on the three-dimensional vessel orientation. Various advanced algorithms are incorporated in this 3D processing utility including 3D-RA calibration, ECG phase selection, 2D vessel extraction, and 3D vessel modeling into a utility with optimized workflow and ease-of-use features, which is fully integrated in the environment of the x-ray catheterization lab. After the 3D processing, the 3D vessels can be viewed and manipulated interactively inside the operating room. The TrueView map provides a quick overview of gantry angles with optimal visualization of a single or bifurcation lesion. Vessel length measurements can be performed without risk of underestimating a vessel segment due to foreshortening. Vessel cross sectional diameters can also be measured. Unlike traditional, projection-based quantitative coronary analysis, the additional process of catheter calibration is not needed for diameter measurements. Validation studies show a high reproducibility of the measurements, with little user dependency.

  13. Three-dimensional ultrasound system for guided breast brachytherapy

    SciTech Connect

    De Jean, Paul; Beaulieu, Luc; Fenster, Aaron

    2009-11-15

    Breast-conserving surgery combined with subsequent radiation therapy is a standard procedure in breast cancer treatment. The disadvantage of whole-breast beam irradiation is that it requires 20-25 treatment days, which is inconvenient for patients with limited mobility or who reside far from the treatment center. However, interstitial high-dose-rate (HDR) brachytherapy is an irradiation method requiring only 5 treatment days and that delivers a lower radiation dose to the surrounding healthy tissue. It involves delivering radiation through {sup 192}Ir seeds placed inside the catheters, which are inserted into the breast. The catheters are attached to a HDR afterloader, which controls the seed placement within the catheters and irradiation times to deliver the proper radiation dose. One disadvantage of using HDR brachytherapy is that it requires performing at least one CT scan during treatment planning. The procedure at our institution involves the use of two CT scans. Performing CT scans requires moving the patient from the brachytherapy suite with catheters inserted in their breasts. One alternative is using three-dimensional ultrasound (3DUS) to image the patient. In this study, the authors developed a 3DUS translation scanning system for use in breast brachytherapy. The new system was validated using CT, the current clinical standard, to image catheters in a breast phantom. Once the CT and 3DUS images were registered, the catheter trajectories were then compared. The results showed that the average angular separation between catheter trajectories was 2.4 deg., the average maximum trajectory separation was 1.0 mm, and the average mean trajectory separation was found to be 0.7 mm. In this article, the authors present the 3DUS translation scanning system's capabilities as well as its potential to be used as the primary treatment planning imaging modality in breast brachytherapy.

  14. Three-dimensional ultrasonic colloidal crystals

    NASA Astrophysics Data System (ADS)

    Caleap, Mihai; Drinkwater, Bruce W.

    2016-05-01

    Colloidal assembly represents a powerful method for the fabrication of functional materials. In this article, we describe how acoustic radiation forces can guide the assembly of colloidal particles into structures that serve as microscopic elements in novel acoustic metadevices or act as phononic crystals. Using a simple three-dimensional orthogonal system, we show that a diversity of colloidal structures with orthorhombic symmetry can be assembled with megahertz-frequency (MHz) standing pressure waves. These structures allow rapid tuning of acoustic properties and provide a new platform for dynamic metamaterial applications. xml:lang="fr"

  15. Three-dimensional Camera Phone

    NASA Astrophysics Data System (ADS)

    Iizuka, Keigo

    2004-12-01

    An inexpensive technique for realizing a three-dimensional (3D) camera phone display is presented. Light from the liquid-crystal screen of a camera phone is linearly polarized, and its direction of polarization is easily manipulated by a cellophane sheet used as a half-waveplate. The novel 3D camera phone display is made possible solely by optical components without resorting to computation, so that the 3D image is displayed in real time. Quality of the original image is not sacrificed in the process of converting it into a 3D image.

  16. Phase II Trial of Radiation Dose Escalation With Conformal External Beam Radiotherapy and High-Dose-Rate Brachytherapy Combined With Long-Term Androgen Suppression in Unfavorable Prostate Cancer: Feasibility Report

    SciTech Connect

    Valero, Jeanette; Cambeiro, Mauricio; Galan, Carlos; Teijeira, Mercedes; Romero, Pilar; Zudaire, Javier; Moreno, Marta; Ciervide, Raquel; Aristu, Jose Javier; Martinez-Monge, Rafael

    2010-02-01

    Purpose: To determine the feasibility of combined long-term luteinizing hormone-releasing hormone agonist-based androgen suppressive therapy (AST) and dose escalation with high-dose-rate (HDR) brachytherapy for high-risk (HRPC) or very-high-risk prostate cancer (VHRPC). Methods and Materials: Between January 2001 and October 2006, 134 patients (median age, 70 years) with either National Comprehensive Cancer Network criteria-defined HRPC (n = 47, 35.1%) or VHRPC (n = 87, 64.9%) were prospectively enrolled in this Phase II trial. Tumor characteristics included a median pretreatment prostate-specific antigen level of 14.6 ng/mL, a median clinical stage of T2c, and a median Gleason score of 7. Three-dimensional conformal radiotherapy (54 Gy in 30 fractions) was followed by HDR brachytherapy (19 Gy in 4 b.i.d. treatments). Androgen suppressive therapy started 0-3 months before three-dimensional conformal radiotherapy and continued for 2 years. Results: One implant was repositioned with a new procedure (0.7%). Five patients (3.7%) discontinued AST at a median of 13 months (range, 6-18 months) because of disease progression (n = 1), hot flashes (n = 2), fatigue (n = 1), and impotence (n = 1). After a median follow-up of 37.4 months (range, 24-90 months), the highest Radiation Therapy Oncology Group-defined late urinary toxicities were Grade 0 in 47.8%, Grade 1 in 38.1%, Grade 2 in 7.5%, and Grade 3 in 6.7% of patients. Maximal late gastrointestinal toxicities were Grade 0 in 73.1%, Grade 1 in 16.4%, Grade 2 in 7.5%, and Grade 3 in 2.9% of patients. There were no Grade 4 or 5 events. Conclusions: Intermediate-term results show that dose escalation with HDR brachytherapy combined with long-term AST is feasible and has a toxicity profile similar to that reported by previous HDR brachytherapy studies.

  17. Dynamics of three-dimensional radiative structures during RMP assisted detached plasmas on the large helical device and its comparison with EMC3-EIRENE modeling

    NASA Astrophysics Data System (ADS)

    Pandya, Shwetang N.; Peterson, Byron J.; Kobayashi, Masahiro; Ida, Katsumi; Mukai, Kiyofumi; Sano, Ryuichi; Miyazawa, Junichi; Tanaka, Hirohiko; Masuzaki, Suguru; Akiyama, Tsuyoshi; Motojima, Gen; Ohno, Noriyasu; LHD Experiment Group

    2016-04-01

    The resonant magnetic perturbation (RMP) island introduced in the stochastic edge of the large helical device (LHD) plasma plays an important role in the stabilization of the plasma detachment (Kobayashi et al 2013 Nucl. Fusion 53 093032). The plasma enters in the sustained detachment phase in the presence of an RMP once the line averaged density exceeds a critical value with a given input power. During detachment the enhanced radiation from the stochastic edge of the LHD undergoes several spatiotemporal changes which are studied quantitatively by an infrared imaging video bolometer (IRVB) diagnostic. The experimental results are compared qualitatively and quantitatively with the radiation predicted by the 3D transport simulation with fluid model, EMC3-EIRENE. A fair amount of qualitative agreement, before and after the detachment, is reported. The issue of overestimated radiation from the model is addressed by changing the free parameters in the EMC3-EIRENE code till the total radiation and the radiation profiles match closely, within a factor of two with the experimental observations. A better quantitative match between the model and the experiment is achieved at higher cross-field impurity diffusion coefficient and lower sputtering coefficient after the detachment. In this article a comparison, the first of its kind, is established between the quantified radiation from the experiments and the synthetic image obtained from the simulation code. This exercise is aimed towards validating the model assumptions against the experimentally measured radiation.

  18. Three-dimensional visual stimulator

    NASA Astrophysics Data System (ADS)

    Takeda, Tsunehiro; Fukui, Yukio; Hashimoto, Keizo; Hiruma, Nobuyuki

    1995-02-01

    We describe a newly developed three-dimensional visual stimulator (TVS) that can change independently the directions, distances, sizes, luminance, and varieties of two sets of targets for both eyes. It consists of liquid crystal projectors (LCP's) that generate the flexible images of targets, Badal otometers that change target distances without changing the visual angles, and relay-lens systems that change target directions. A special control program is developed for real-time control of six motors and two LCP's in the TVS together with a three-dimensional optometer III that simultaneously measures eye movement, accommodation, pupil diameter, and head movement. distance, 0 to -20 D; direction, 16 horizontally and 15 vertically; size, 0-2 deg visual angle; and luminance, 10-2-10 2 cd/m2. The target images are refreshed at 60 Hz and speeds with which the target makes a smooth change (ramp stimuli) are size, 10 deg/s. A simple application demonstrates the performance.

  19. Phase 2 Trial of Hypofractionated High-Dose Intensity Modulated Radiation Therapy With Concurrent and Adjuvant Temozolomide for Newly Diagnosed Glioblastoma

    SciTech Connect

    Iuchi, Toshihiko; Hatano, Kazuo; Kodama, Takashi; Sakaida, Tsukasa; Yokoi, Sana; Kawasaki, Koichiro; Hasegawa, Yuzo; Hara, Ryusuke

    2014-03-15

    Purpose/Objectives: To assess the effect and toxicity of hypofractionated high-dose intensity modulated radiation therapy (IMRT) with concurrent and adjuvant temozolomide (TMZ) in 46 patients with newly diagnosed glioblastoma multiforme (GBM). Methods and Materials: All patients underwent postsurgical hypofractionated high-dose IMRT. Three layered planning target volumes (PTVs) were contoured. PTV1 was the surgical cavity and residual tumor on T1-weighted magnetic resonance images with 5-mm margins, PTV2 was the area with 15-mm margins surrounding the PTV1, and PTV3 was the high-intensity area on fluid-attenuated inversion recovery images. Irradiation was performed in 8 fractions at total doses of 68, 40, and 32 Gy for PTV1, PTV2, and PTV3, respectively. Concurrent TMZ was given at 75 mg/m{sup 2}/day for 42 consecutive days. Adjuvant TMZ was given at 150 to 200 mg/m{sup 2}/day for 5 days every 28 days. Overall and progression-free survivals were evaluated. Results: No acute IMRT-related toxicity was observed. The dominant posttreatment failure pattern was dissemination. During a median follow-up time of 16.3 months (range, 4.3-80.8 months) for all patients and 23.7 months (range, 12.4-80.8 months) for living patients, the median overall survival was 20.0 months after treatment. Radiation necrosis was diagnosed in 20 patients and was observed not only in the high-dose field but also in the subventricular zone (SVZ). Necrosis in the SVZ was significantly correlated with prolonged survival (hazard ratio, 4.08; P=.007) but caused deterioration in the performance status of long-term survivors. Conclusions: Hypofractionated high-dose IMRT with concurrent and adjuvant TMZ altered the dominant failure pattern from localized to disseminated and prolonged the survival of patients with GBM. Necrosis in the SVZ was associated with better patient survival, but the benefit of radiation to this area remains controversial.

  20. Brachial Plexus-Associated Neuropathy After High-Dose Radiation Therapy for Head-and-Neck Cancer

    SciTech Connect

    Chen, Allen M.; Hall, William H.; Li, Judy; Beckett, Laurel; Farwell, D. Gregory; Lau, Derick H.; Purdy, James A.

    2012-09-01

    Purpose: To identify clinical and treatment-related predictors of brachial plexus-associated neuropathies after radiation therapy for head-and-neck cancer. Methods and Materials: Three hundred thirty patients who had previously completed radiation therapy for head-and-neck cancer were prospectively screened using a standardized instrument for symptoms of neuropathy thought to be related to brachial plexus injury. All patients were disease-free at the time of screening. The median time from completion of radiation therapy was 56 months (range, 6-135 months). One-hundred fifty-five patients (47%) were treated by definitive radiation therapy, and 175 (53%) were treated postoperatively. Radiation doses ranged from 50 to 74 Gy (median, 66 Gy). Intensity-modulated radiation therapy was used in 62% of cases, and 133 patients (40%) received concurrent chemotherapy. Results: Forty patients (12%) reported neuropathic symptoms, with the most common being ipsilateral pain (50%), numbness/tingling (40%), motor weakness, and/or muscle atrophy (25%). When patients with <5 years of follow-up were excluded, the rate of positive symptoms increased to 22%. On univariate analysis, the following factors were significantly associated with brachial plexus symptoms: prior neck dissection (p = 0.01), concurrent chemotherapy (p = 0.01), and radiation maximum dose (p < 0.001). Cox regression analysis confirmed that both neck dissection (p < 0.001) and radiation maximum dose (p < 0.001) were independently predictive of symptoms. Conclusion: The incidence of brachial plexus-associated neuropathies after radiation therapy for head-and-neck cancer may be underreported. In view of the dose-response relationship identified, limiting radiation dose to the brachial plexus should be considered when possible.

  1. Mortality risk coefficients for radiation-induced cancer at high doses and dose-rates, and extrapolation to the low dose domain.

    PubMed

    Liniecki, J

    1989-01-01

    Risk coefficients for life-long excessive mortality due to radiation-induced cancers are presented, as derived in 1988 by the U.N. Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), principally on the basis of follow-up from A-bomb survivors in Japan, over the period from 1950 through 1985. The data are based on the new, revised dosimetry (DS 86) in the two cities, and reflect the effects of high and intermediate doses of basically low LET radiation delivered instantaneously. The author presents arguments relevant to the extrapolation of the risk to the low dose (dose rate) domain, as outlined by UNSCEAR in its 1986, and the NCRP (USA) in its 1980, (no 64), reports. The arguments are based on models and dose-response relationships for radiation action, derived from data on cellular radiobiology, animal experiments on radiation-induced cancers and life shortening, as well as the available limited human epidemiological evidence. The available information points to the lower effectiveness of sparsely ionizing radiation at low doses and low dose-rates, as compared with that observed for high, acutely delivered doses. The possible range of the reduction values (DREF) is presented. For high LET radiations, the evidence is less extensive and sometimes contradictory; however, it does not point to a reduction of the effectiveness at low doses/dose-rates, relative to the high dose domain. Practical consequences of these facts are considered. PMID:2489419

  2. Randomized Phase II Trial of High-Dose Melatonin and Radiation Therapy for RPA Class 2 Patients With Brain Metastases (RTOG 0119)

    SciTech Connect

    Berk, Lawrence . E-mail: Berklb@moffitt.usf.edu; Berkey, Brian; Rich, Tyvin; Hrushesky, William; Gallagher, Michael; Kudrimoti, Mahesh; McGarry, Ronald C.; Suh, John; Mehta, Minesh

    2007-07-01

    Purpose: To determine if high-dose melatonin for Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) Class 2 patients with brain metastases improved survival over historical controls, and to determine if the time of day melatonin was given affected its toxicity or efficacy. RTOG 0119 was a phase II randomized trial for this group of patients. Methods and Materials: RTOG RPA Class 2 patients with brain metastases were randomized to 20 mg of melatonin, given either in the morning (8-9 AM) or in the evening (8-9 PM). All patients received radiation therapy (30 Gy in 10 fractions) in the afternoon. Melatonin was continued until neurologic deterioration or death. The primary endpoint was overall survival time. Neurologic deterioration, as reflected by the Mini-Mental Status Examination, was also measured. Results: Neither of the randomized groups had survival distributions that differed significantly from the historic controls of patients treated with whole-brain radiotherapy. The median survivals of the morning and evening melatonin treatments were 3.4 and 2.8 months, while the RTOG historical control survival was 4.1 months. Conclusions: High-dose melatonin did not show any beneficial effect in this group of patients.

  3. Use of benchmark dose-volume histograms for selection of the optimal technique between three-dimensional conformal radiation therapy and intensity-modulated radiation therapy in prostate cancer

    SciTech Connect

    Luo Chunhui; Yang, Claus Chunli; Narayan, Samir; Stern, Robin L.; Perks, Julian; Goldberg, Zelanna; Ryu, Janice; Purdy, James A.; Vijayakumar, Srinivasan . E-mail: Srinivasan.Vijayakumar@ucdmc.ucdavis.edu

    2006-11-15

    Purpose: The aim of this study was to develop and validate our own benchmark dose-volume histograms (DVHs) of bladder and rectum for both conventional three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), and to evaluate quantitatively the benefits of using IMRT vs. 3D-CRT in treating localized prostate cancer. Methods and Materials: During the implementation of IMRT for prostate cancer, our policy was to plan each patient with both 3D-CRT and IMRT. This study included 31 patients with T1b to T2c localized prostate cancer, for whom we completed double-planning using both 3D-CRT and IMRT techniques. The target volumes included prostate, either with or without proximal seminal vesicles. Bladder and rectum DVH data were summarized to obtain an average DVH for each technique and then compared using two-tailed paired t test analysis. Results: For 3D-CRT our bladder doses were as follows: mean 28.8 Gy, v60 16.4%, v70 10.9%; rectal doses were: mean 39.3 Gy, v60 21.8%, v70 13.6%. IMRT plans resulted in similar mean dose values: bladder 26.4 Gy, rectum 34.9 Gy, but lower values of v70 for the bladder (7.8%) and rectum (9.3%). These benchmark DVHs have resulted in a critical evaluation of our 3D-CRT techniques over time. Conclusion: Our institution has developed benchmark DVHs for bladder and rectum based on our clinical experience with 3D-CRT and IMRT. We use these standards as well as differences in individual cases to make decisions on whether patients may benefit from IMRT treatment rather than 3D-CRT.

  4. Three-dimensional study of the multi-cavity FEL

    SciTech Connect

    Krishnagopal, S.; Kumar, V.

    1995-12-31

    The Multi-Cavity Free-Electron Laser has been proposed earlier, as a new configuration to obtain short, intense pulses of radiation, the key idea being to pre-bunch the electron beam in a number of very short cavities. Those studies were one-dimensional. Here we use three-dimensional simulations to study the viability of this concept when three-dimensional effects are included, particularly with regard to the transverse modes of the optical beam.

  5. Concomitant 5-fluorouracil infusion and high-dose radiation for stage III non-small cell lung cancer

    SciTech Connect

    Lokich, J.; Chaffey, J.; Neptune, W. )

    1989-09-01

    Thirty patients with Stage III non-small cell lung cancer were entered on a trial to evaluate the feasibility of combined radiation and concomitant 5-fluorouracil infusion. Patients had received prior debulking surgery (nine), induction chemotherapy (16), or no therapy (five). Radiation employed standard fractionation (180-200 rad/day) administered to a median cumulative dose of 5500 rad (range, 4500-6200 rad). 5-Fluorouracil was infused 24 hours per day throughout the period of radiation at a dose of 300 mg/m2/day for a median of 42 days (range, 28-56 days). Radiation complications included pneumonitis three of 30 (10%) and esophagitis (27%). Chemotherapy complications included stomatitis, two of 27 (7%), and hand-foot syndrome, three of 30 (10%). Treatment interruptions were necessary in six of 30 (20%) and four of 30 required parenteral nutrition. At a median follow-up of 12 months 26/30 (87%) maintained local control and eight had distant metastases (three of whom presented with Stage IV disease). 5-Fluorouracil delivered continuously throughout standard fractionation radiation to high cumulative doses is feasible and practical. Comparative clinical trials of the various combined radiation and chemotherapy schedules employed are in order. One additional clinical observation was the identification of six of 30 (20%) with brain metastases at presentation or after 12 months, all of whom had adenocarcinoma histologic subtype.

  6. Three-dimensional coil inductor

    DOEpatents

    Bernhardt, Anthony F.; Malba, Vincent

    2002-01-01

    A three-dimensional coil inductor is disclosed. The inductor includes a substrate; a set of lower electrically conductive traces positioned on the substrate; a core placed over the lower traces; a set of side electrically conductive traces laid on the core and the lower traces; and a set of upper electrically conductive traces attached to the side traces so as to form the inductor. Fabrication of the inductor includes the steps of forming a set of lower traces on a substrate; positioning a core over the lower traces; forming a set of side traces on the core; connecting the side traces to the lower traces; forming a set of upper traces on the core; and connecting the upper traces to the side traces so as to form a coil structure.

  7. Ionizing radiation and autoimmunity: Induction of autoimmune disease in mice by high dose fractionated total lymphoid irradiation and its prevention by inoculating normal T cells

    SciTech Connect

    Sakaguchi, N.; Sakaguchi, S. Scripps Research Institute, La Jolla, CA PRESTO, JRDC, Institute of Phical and Chemical Research, Tsukuba, Ibaraki ); Miyai, K. )

    1992-11-01

    Ionizing radiation can functionally alter the immune system and break self-tolerance. High dose (42.5 Gy), fractionated (2.5 Gy 17 times) total lymphoid irradiation (TLI) on mice caused various organ-specific autoimmune diseases, such as gastritis, thyroiditis, and orchitis, depending on the radiation dosages, the extent of lymphoid irradiation, and the genetic background of the mouse strains. Radiation-induced tissue damage is not the primary cause of the autoimmune disease because irradiation of the target organs alone failed to elicit the autoimmunity and shielding of the organs from irradiation was unable to prevent it. In contrast, irradiation of both the thymus and the peripheral lymphoid organs/tissues was required for efficient induction of autoimmune disease by TLI. TLI eliminated the majority of mature thymocytes and the peripheral T cells for 1 mo, and inoculation of spleen cell, thymocyte, or bone marrow cell suspensions (prepared from syngeneic nonirradiated mice) within 2 wk after TLI effectively prevented the autoimmune development. Depletion of T cells from the inocula abrogated the preventive activity. CD4[sup +] T cells mediated the autoimmune prevention but CD8[sup +] T cells did not. CD4[sup +] T cells also appeared to mediate the TLI-induced autoimmune disease because CD4[sup +] T cells from disease-bearing TLI mice adoptively transferred the autoimmune disease to syngeneic naive mice. Taken together, these results indicate that high dose, fractionated ionizing radiation on the lymphoid organs/tissues can cause autoimmune disease by affecting the T cell immune system, rather than the target self-Ags, presumably by altering T cell-dependent control of self-reactive T cells. 62 refs., 9 figs., 2 tabs.

  8. The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

    SciTech Connect

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; Mickel, Patrick R.; Hanson, Donald J.; McDonald, Joseph K.; Hughart, David Russell; Marinella, Matthew J.

    2014-11-11

    This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×107 rad(Si)/s to 4.7 ×108 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×108 rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. In addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.

  9. Differential Molecular Stress Responses to Low Compared to High Doses of Ionizing Radiation in Normal Human Fibroblasts

    PubMed Central

    Velegzhaninov, Ilya O.; Shadrin, Dmitry M.; Pylina, Yana I.; Ermakova, Anastasia V.; Shostal, Olga A.; Belykh, Elena S.; Kaneva, Anna V.; Ermakova, Olga V.

    2015-01-01

    Understanding the mechanisms producing low dose ionizing radiation specific biological effects represents one of the major challenges of radiation biology. Although experimental evidence does suggest that various molecular stress response pathways may be involved in the production of low dose effects, much of the detail of those mechanisms remains elusive. We hypothesized that the regulation of various stress response pathways upon irradiation may differ from one another in complex dose-response manners, causing the specific and subtle low dose radiation effects. In the present study, the transcription level of 22 genes involved in stress responses were analyzed using RT-qPCR in normal human fibroblasts exposed to a range of gamma-doses from 1 to 200 cGy. Using the alkali comet assay, we also measured the level of DNA damages in dose-response and time-course experiments. We found non-linear dose responses for the repair of DNA damage after exposure to gamma-radiation. Alterations in gene expression were also not linear with dose for several of the genes examined and did not follow a single pattern. Rather, several patterns could be seen. Our results suggest a complex interplay of various stress response pathways triggered by low radiation doses, with various low dose thresholds for different genes. PMID:26675169

  10. Radiation-induced failures and degradation of wireless real-time dosimeter under high-dose-rate irradiation

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Kuroki, K.; Akiba, N.; Kurosawa, K.; Matsumoto, T.; Nishiyama, J.; Harano, H.

    2010-04-01

    Radiation-induced malfunction and degradation of electronic modules in certain operating conditions are described in this report. The cumulative radiation effects on Atmel AVR microcontrollers, and 2.4 GHz and 303 MHz wireless network devices were evaluated under gamma ray irradiation with dose rates of 100, 10 and 3 Gy/h. The radiation-induced malfunctions occurred at doses of 510+/-22 Gy for AVR microcontrollers, and 484+/-111 and 429+/-14 Gy for 2.4 GHz and 303 MHz wireless network devices, respectively, under a 100 Gy/h equivalent dose rate. The degradation of microcontrollers occurred for total ionizing doses between 400 and 600 Gy under X-ray irradiation. In addition, we evaluated the reliability of neutron dosimeters using a standard neutron field. One of the neutron dosimeters gave a reading that was half of the standard field value.