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Sample records for intense alpha radiation

  1. A 3D Radiative Transfer Simulation of Lyma-alpha Backscatter Intensity Reduced From Voyager’s Ultraviolet Spectrometer

    NASA Astrophysics Data System (ADS)

    Fayock, Brian; Zank, Gary; Heerikhuisen, Jacob

    2014-06-01

    Models of the heliosphere have evolved for the past few decades to fit observations made by a large number of spacecraft. Voyager missions have provided unique in-situ measurements that have proven to be essential for model testing. Lyman-alpha backscatter intensity has been reduced from measurements taken by the ultraviolet spectrometers on board both Voyager spacecraft. We have developed a 3D Monte Carlo radiative transfer code to simulate this backscatter intensity by generating millions of photons from the sun to scatter within a neutral hydrogen distribution resulting from a state-of-the-art 3D MHD-kinetic neutral heliospheric model, both of which have been developed within the Center for Space Physics and Aeronomic Research at the University of Alabama in Huntsville. While many have attempted to simulate the Voyager observations, we are the first to achieve agreement with our results. In this presentation, we will discuss the core mechanisms driving the radiative transfer code, the statistical quantities collected, and the interpretation of the results relative to the spacecraft data.

  2. Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    SciTech Connect

    Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi; Bakule, Pavel; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-15

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

  3. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 ke

  4. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  5. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  6. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  7. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  8. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons.

  9. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 ke

  10. L-alpha intensity in coronal streamers

    NASA Technical Reports Server (NTRS)

    Noci, G.; Poletto, G.; Suess, S. T.; Wang, A.-H.; Wu, S. T.

    1993-01-01

    White-light images are presently the primary source of information on physical conditions in the solar corona at distances greater than a few tenths of a solar radius above the limb. As a consequence, we still only have an incomplete description of structures extending beyond the solar limb. In particular, streamers, although observed for decades, represent a poorly known phenomenon. SOHO, to be launched in 1995, will be able to make long-term observations of these features up to heights of a few solar radii, both in white light and UV. In this paper we present simulations of L-alpha intensity in coronal streamers, based on the two-dimensional (2D) model developed by Wang et at. (1992, 1993) via a time-dependent numerical relaxation approach. Because the model is 2D, we make an a priori hypothesis about the extension of streamers in the third dimension. L-alpha data, obtained from a rocket (Kohl et al., 1983), allowed us to identify a shape which fits the observations.

  11. Lyman alpha radiation in external galaxies

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Mckee, Christopher F.

    1990-01-01

    The Ly alpha line of atomic hydrogen is often a luminous component of the radiation emitted by distant galaxies. Except for those galaxies which have a substantial central source of non-stellar ionizing radiation, most of the Ly alpha radiation emitted by galaxies is generated within regions of the interstellar medium which are photoionized by starlight. Conversely, much of the energy radiated by photoionized regions is carried by the Ly alpha line. Only hot, massive stars are capable of ionizing hydrogen in the interstellar medium which surrounds them, and because such stars are necessarily short-lived, Ly alpha emission traces regions of active star formation. Researchers argue that the strength of the Ly alpha emission observed from external galaxies may be used to estimate quantitatively the dust content of the emitting region, while the Ly alpha line profile is sensitive to the presence of shock waves. Interstellar dust particles and shock waves are intimately associated with the process of star formation in two senses. First, both dust particles and shock waves owe their existence to stellar activity; second, they may both serve as agents which facilitate the formation of stars, shocks by triggering gravitational instabilities in the interstellar gas that they compress, and dust by shielding star-forming molecular clouds from the ionizing and dissociative effects of external UV radiation. By using Ly alpha observations as a probe of the dust content in diffuse gas at high redshift, we might hope to learn about the earliest epochs of star formation.

  12. Radiation reaction at ultrahigh intensities

    SciTech Connect

    Hammond, Richard T.

    2010-06-15

    Intensities of 10{sup 22} W cm{sup -2} have been reached and it is expected that this will be increased by two orders of magnitude in the near future. At these intensities the radiation reaction force is important, especially in calculating the terminal velocity of an electron. The following briefly describes some of the problems of the existing most well-known equations and describes an approach based on conservation of energy. The resulting equation is compared to the Landau Lifshitz and Ford O'Connell equations, and laboratory tests are proposed.

  13. Intensity-Modulated Radiation Therapy (IMRT)

    MedlinePlus

    ... modulating—or controlling—the intensity of the radiation beam in multiple small volumes. IMRT also allows higher ... of multiple intensity-modulated fields coming from different beam directions produce a custom tailored radiation dose that ...

  14. Hydrogen Balmer alpha intensity distributions and line profiles from multiple scattering theory using realistic geocoronal models

    NASA Technical Reports Server (NTRS)

    Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.

    1987-01-01

    The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.

  15. Alpha-beta radiation detector

    DOEpatents

    Fleming, D.M.; Simmons, K.L.; Froelich, T.J.; Carter, G.L.

    1998-08-18

    The invention is based in part on the discovery that a plastic housing that is lightweight is surprisingly efficient inasmuch as background signals from any gamma radiation are significantly reduced by using a plastic housing instead of a metal housing. A further aspect of the present invention is the profile of the housing as a bi-linear approximation to a parabola resulting in full optical response from any location on the scintillation material to the photomultiplier tube. A yet further aspect of the present invention is that the survey probe is resistant to magnetic fields. A yet further aspect of the present invention is the use of a snap-fit retaining bracket that overcomes the need for multiple screws. 16 figs.

  16. Alpha-beta radiation detector

    DOEpatents

    Fleming, Dale M.; Simmons, Kevin L.; Froelich, Thomas J.; Carter, Gregory L.

    1998-01-01

    The invention is based in part on the discovery that a plastic housing that is lightweight is surprisingly efficient inasmuch as background signals from any gamma radiation are significantly reduced by using a plastic housing instead of a metal housing. A further aspect of the present invention is the profile of the housing as a bi-linear approximation to a parabola resulting in full optical response from any location on the scintillation material to the photomultiplier tube. A yet further aspect of the present invention is that the survey probe is resistant to magnetic fields. A yet further aspect of the present invention is the use of a snap-fit retaining bracket that overcomes the need for multiple screws.

  17. [Alpha-2 adrenoreceptor agonists in anaesthesia and intensive care medicine].

    PubMed

    Mavropoulos, G; Minguet, G; Brichant, J F

    2014-02-01

    Alpha-2 adrenoreceptor agonists have long been used in the treatment of arterial hypertension. However, in that indication they have progressively been replaced by antihypertensive drugs with a more interesting therapeutic profile. Nonetheless, pharmacological activation of alpha-2 adrenoreceptors leads to a variety of clinical effects that are of major interest for anaesthesia and intensive care practice. Indeed, the sedative and analgesic properties of alpha-2 adrenoreceptor agonists allow a reduction of hypnotic and opioid needs during general anaesthesia. In addition, they induce a down-regulation of the level of consciousness comparable to that of natural slow-wave sleep during post-anaesthesia and intensive care unit stay. These drugs may also prevent some deleterious effects of the sympathetic discharge in response to surgical stress. Furthermore, alpha-2 adrenoreceptor agonists are potent adjuncts for locoregional anaesthesia. In this article, we will summarize the most frequent applications of alpha-2 adrenoreceptor agonists in anaesthesia and intensive care medicine. We will focus on the clinical data available for the two most representative molecules of this pharmacological class: clonidine and dexmedetomidine. PMID:24683831

  18. LOGNORMAL INTENSITY DISTRIBUTION OF THE FAR-ULTRAVIOLET CONTINUUM BACKGROUND SHORTWARD OF Ly{alpha}

    SciTech Connect

    Seon, Kwang-Il

    2013-07-20

    The diffuse far-ultraviolet (FUV) continuum radiation 'longward' of Ly{alpha} (1216 A) is well known to correlate with the dust emission at 100 {mu}m. However, it has been claimed that the FUV continuum background 'shortward' of Ly{alpha} shows very weak or no correlation with the 100 {mu}m emission. In this paper, the observational data of the diffuse FUV radiation by the Far Ultraviolet Spectroscopic Explorer (FUSE) are reexamined in order to investigate the correlation between the diffuse FUV radiation shortward of Ly{alpha} and the 100 {mu}m emission. Large fluctuations were confirmed in the linear-linear correlation plots, but good correlations were found in the log-log plots. The large fluctuations in the linear-linear plots, and thus poor correlations, between the FUV and 100 {mu}m intensities were attributed to the lognormal property of the FUV intensity distribution. The standard deviation of the intensity distribution of the FUV radiation shortward of Ly{alpha} was found to be {sigma}{sub logI} = 0.16-0.25. The result is consistent with that obtained not only for the FUV radiation longward of 1216 A but also with the dust column density measurements of various molecular clouds. This implies that most of the diffuse FUV radiation shortward of Ly{alpha} is dust-scattered light in the turbulent interstellar medium. The diffuse FUV data obtained from the Voyager missions were also investigated. However, much wider random fluctuations were found compared with the FUSE data, which is most likely due to the systematic difficulties in data reduction of the Voyager data.

  19. INTENSITY MAPPING OF Ly{alpha} EMISSION DURING THE EPOCH OF REIONIZATION

    SciTech Connect

    Silva, Marta B.; Santos, Mario G.; Gong, Yan; Cooray, Asantha; Bock, James

    2013-02-15

    We calculate the absolute intensity and anisotropies of the Ly{alpha} radiation field present during the epoch of reionization. We consider emission from both galaxies and the intergalactic medium (IGM) and take into account the main contributions to the production of Ly{alpha} photons: recombinations, collisions, continuum emission from galaxies, and scattering of Lyn photons in the IGM. We find that the emission from individual galaxies dominates over the IGM with a total Ly{alpha} intensity (times frequency) of about (1.43-3.57) Multiplication-Sign 10{sup -8} erg s{sup -1} cm{sup -2} sr{sup -1} at a redshift of 7. This intensity level is low, so it is unlikely that the Ly{alpha} background during reionization can be established by an experiment aiming at an absolute background light measurement. Instead, we consider Ly{alpha} intensity mapping with the aim of measuring the anisotropy power spectrum that has rms fluctuations at the level of 1 Multiplication-Sign 10{sup -16} [erg s{sup -1} cm{sup -2} sr{sup -1}]{sup 2} at a few Mpc scales. These anisotropies could be measured with a spectrometer at near-IR wavelengths from 0.9 to 1.4 {mu}m with fields in the order of 0.5 to 1 deg{sup 2}. We recommend that existing ground-based programs using narrowband filters also pursue intensity fluctuations to study statistics on the spatial distribution of faint Ly{alpha} emitters. We also discuss the cross-correlation signal with 21 cm experiments that probe H I in the IGM during reionization. A dedicated sub-orbital or space-based Ly{alpha} intensity mapping experiment could provide a viable complimentary approach to probe reionization, when compared to 21 cm experiments, and is likely within experimental reach.

  20. Predicting Ly-alpha intensities in coronal streamers

    NASA Technical Reports Server (NTRS)

    Noci, Giancarlo; Poletto, Giannina; Suess, Steven T.; Wang, A.-H.; Wu, S. T.

    1992-01-01

    SOHO (Solar and Heliospheric Observatory) UVCS (Ultraviolet Coronagraph Spectrometer) will make long term observations of coronal streamers in UV lines, providing a new tool for the analysis of structures which have been known for decades but are still far from being adequately described. Work to evaluate the Lyman alpha brightness of coronal streamers is reported, adopting the streamer models obtained, via a time dependent numerical relaxation technique. This will yield understanding on the role of geometric versus physical factors in determining the streamer lyman alpha intensity and provide guidelines for UVCS observational operations. Future prospects along this line of research are summarized.

  1. Analysis of solar Lyman alpha radiation in the heliosphere

    NASA Astrophysics Data System (ADS)

    Fayock, B.; Zank, G. P.; Heerikhuisen, J.

    2013-06-01

    Various NASA spacecraft have measured ultraviolet radiation in the heliosphere at different locations over time. Much of this data corresponds to back-scattered Lyman-alpha radiation from neutral hydrogen, particularly in the context of planetary atmospheric measurements and inferred solar activity. Less attention has been devoted to using this data in the context of large-scale heliospheric simulations with complex global models. A 3D Monte Carlo simulation has been developed for analysis of Lyman-alpha scattering using global heliospheric models developed within CSPAR as a background. The simulation tracks individual photons in a sun-centered spherical coordinate system with a radial limit of 1000 AU while retaining statistics for each cell within the grid space, which is defined by the global input data. Two of the statistics collected are the number of scatters and the total distance traveled by photons within a cell. Those photons directed towards the sun provide a measure of backscatter intensity that can be compared to antisolar observations of Lyman-alpha photons by spacecraft. Preliminary results reveal a similar trend of intensity between simulation in the upwind direction and reduced Voyager data, suggesting an accurate portrayal of neutral hydrogen in the heliosphere.

  2. The L-alpha/H-alpha intensity ratio in PKS 0237-23. [quasar

    NASA Technical Reports Server (NTRS)

    Hyland, A. R.; Becklin, E. E.; Neugebauer, G.

    1978-01-01

    The ratio I(L-alpha)/I(H-alpha) has been measured to be 1.7 plus or minus 0.6 in the quasar PKS 0237-23. The measured ratio is similar to that measured in 3C 273 by Davidsen et al. and to that inferred by Baldwin from a study of a large number of quasars; it is a factor of 5 to 14 smaller than expected from recombination theory. If the L-alpha radiation is resonantly scattered and there are modest amounts of dust within the ionized region, the measured ratio may be interpreted in terms of recombination theory, with L-alpha being depleted by absorption by the dust.

  3. A novel nanometric DNA thin film as a sensor for alpha radiation

    NASA Astrophysics Data System (ADS)

    Kulkarni, Atul; Kim, Byeonghoon; Dugasani, Sreekantha Reddy; Joshirao, Pranav; Kim, Jang Ah; Vyas, Chirag; Manchanda, Vijay; Kim, Taesung; Park, Sung Ha

    2013-06-01

    The unexpected nuclear accidents have provided a challenge for scientists and engineers to develop sensitive detectors, especially for alpha radiation. Due to the high linear energy transfer value, sensors designed to detect such radiation require placement in close proximity to the radiation source. Here we report the morphological changes and optical responses of artificially designed DNA thin films in response to exposure to alpha radiation as observed by an atomic force microscope, a Raman and a reflectance spectroscopes. In addition, we discuss the feasibility of a DNA thin film as a radiation sensing material. The effect of alpha radiation exposure on the DNA thin film was evaluated as a function of distance from an 241Am source and exposure time. Significant reflected intensity changes of the exposed DNA thin film suggest that a thin film made of biomolecules can be one of promising candidates for the development of online radiation sensors.

  4. High Intensity Radiated Fields (HIRF) project plan

    NASA Astrophysics Data System (ADS)

    Glynn, Michael S.; Blair, Jerry T.; Hintze, M. Marx

    1991-09-01

    Addressed here is the Federal Aviation Administration's approach to High Intensity Radiated Fields (HIRF) affecting the aviation community. Near- and far-term tasks are described. Deliverables, program management, scheduling, and cost issues are discussed.

  5. Radiative trapping in intense laser beams

    NASA Astrophysics Data System (ADS)

    Kirk, J. G.

    2016-08-01

    The dynamics of electrons in counter-propagating, circularly polarized laser beams are shown to exhibit attractors whose ability to trap particles depends on the ratio of the beam intensities and a single parameter describing radiation reaction. Analytical expressions are found for the underlying limit cycles and the parameter range in which they are stable. In high-intensity optical pulses, where radiation reaction strongly modifies the trajectories, the production of collimated gamma-rays and the initiation of non-linear cascades of electron–positron pairs can be optimized by a suitable choice of the intensity ratio.

  6. High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers

    SciTech Connect

    Park, H; Izumi, N; Key, M H; King, J A; Koch, J A; Landen, O L; Patel, P K; Price, D F; Remington, B A; Robey, H F; Snavely, R A; Tabak, M; Town, R J; Wickersham, J E; Stoeckl, C; Storm, M; Theobald, W; Chambers, D M; Eagelton, R; Goldsack, T; Clarke, R J; Heathcote, R; Giraldez, E; Nikroo, A; Steinman, D A; Stephens, R B; Zhang, B B

    2005-11-16

    We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K{alpha} radiation. 1-D radiography experiments using small-edge-on foils resolved 10 {micro}m features with high contrast. We tested a variety of small volume 2-D point sources such as cones, wires, and embedded wires, measuring photon yields and comparing our measurements with predictions from hybrid-PIC LSP simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the 20-100 keV energy range. An initial look at some of these detector issues is also presented.

  7. Detecting radiation reaction at moderate laser intensities.

    PubMed

    Heinzl, Thomas; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Bulanov, Stepan S; Rykovanov, Sergey; Schroeder, Carl B; Esarey, Eric; Leemans, Wim P

    2015-02-01

    We propose a new method of detecting radiation reaction effects in the motion of particles subjected to laser pulses of moderate intensity and long duration. The effect becomes sizable for particles that gain almost no energy through the interaction with the laser pulse. Hence, there are regions of parameter space in which radiation reaction is actually the dominant influence on charged particle motion. PMID:25768626

  8. Intense terahertz radiation and their applications

    NASA Astrophysics Data System (ADS)

    Hafez, H. A.; Chai, X.; Ibrahim, A.; Mondal, S.; Férachou, D.; Ropagnol, X.; Ozaki, T.

    2016-09-01

    In this paper, we will review both past and recent progresses in the generation, detection and application of intense terahertz (THz) radiation. We will restrict the review to laser based intense few-cycle THz sources, and thus will not include sources such as synchrotron-based or narrowband sources. We will first review the various methods used for generating intense THz radiation, including photoconductive antennas (PCAs), optical rectification sources (especially the tilted-pulse-front lithium niobate source and the DAST source, but also those using other crystals), air plasma THz sources and relativistic laser–plasma sources. Next, we will give a brief introduction on the common methods for coherent THz detection techniques (namely the PCA technique and the electro-optic sampling), and point out the limitations of these techniques for measuring intense THz radiation. We will then review three techniques that are highly suited for detecting intense THz radiation, namely the air breakdown coherent detection technique, various single-shot THz detection techniques, and the spectral-domain interferometry technique. Finally, we will give an overview of the various applications that have been made possible with such intense THz sources, including nonlinear THz spectroscopy of condensed matter (optical-pump/THz-probe, THz-pump/THz-probe, THz-pump/optical-probe), nonlinear THz optics, resonant and non-resonant control of material (such as switching of superconductivity, magnetic and polarization switching) and controlling the nonlinear response of metamaterials. We will also provide a short perspective on the future of intense THz sources and their applications.

  9. 20-100 keV K(alpha) X-Ray Source Generation by Short Pulse High Intensity Lasers

    SciTech Connect

    Park, H-S; Koch, J A; Landen, O L; Phillips, T W; Goldsack, T

    2003-08-22

    We are studying the feasibility of utilizing K{alpha} x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K{alpha} sources are created by relativistic electron plasma interactions in the target material after a radiation by short pulse high intensity lasers. In order to understand K{alpha} source characteristics such as production efficiency and brightness as a function of laser parameters, we have performed experiments using the 10 J, 100 fs JanUSP laser. We utilized single-photon counting spectroscopy and x-ray imaging diagnostics to characterize the K{alpha} source. We find that the K{alpha} conversion efficiency from the laser energy is {approx} 3 x 10{sup -4}.

  10. The NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Williams, Reuben A.

    1997-01-01

    High Intensity Radiated Fields (HIRF) are the result of a multitude of intentional and nonintentional electromagnetic sources that currently exists in the world. Many of today's digital systems are susceptible to electronic upset if subjected to certain electromagnetic environments (EME). Modern aerospace designers and manufacturers increasingly rely on sophisticated digital electronic systems to provide critical flight control in both military, commercial, and general aviation aircraft. In an effort to understand and emulate the undesired environment that high energy RF provides modern electronics, the Electromagnetics Research Branch (ERB) of the Flight Electronics and Technology Division (FETD) conducts research on RF and microwave measurement methods related to the understanding of HIRF. In the High Intensity Radiated Fields Laboratory, the effects of high energy radiating electromagnetic fields on avionics and electronic systems are tested and studied.

  11. Physics of intense, high energy radiation effects.

    SciTech Connect

    Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

    2011-02-01

    This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the

  12. Quasiclassical description of bremsstrahlung accompanying {alpha} decay including quadrupole radiation

    SciTech Connect

    Jentschura, U. D.; Milstein, A. I.; Terekhov, I. S.; Boie, H.; Scheit, H.; Schwalm, D.

    2008-01-15

    We present a quasiclassical theory of {alpha} decay accompanied by bremsstrahlung with a special emphasis on the case of {sup 210}Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy E{sub {gamma}} of the radiated photon up to E{sub {gamma}}{approx}Q{sub {alpha}}/{radical}({eta}), where Q{sub {alpha}} is the {alpha}-decay Q-value and {eta} is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment is achieved. Furthermore, we find that a dipole-quadrupole interference significantly changes the {alpha}-{gamma} angular correlation. We obtain good agreement between our theoretical predictions and experimental results.

  13. Detection of alpha radiation in a beta radiation field

    DOEpatents

    Mohagheghi, Amir H.; Reese, Robert P.

    2001-01-01

    An apparatus and method for detecting alpha particles in the presence of high activities of beta particles utilizing an alpha spectrometer. The apparatus of the present invention utilizes a magnetic field applied around the sample in an alpha spectrometer to deflect the beta particles from the sample prior to reaching the detector, thus permitting detection of low concentrations of alpha particles. In the method of the invention, the strength of magnetic field required to adequately deflect the beta particles and permit alpha particle detection is given by an algorithm that controls the field strength as a function of sample beta energy and the distance of the sample to the detector.

  14. Film Dosimetry for Intensity Modulated Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Benites-Rengifo, J.; Martínez-Dávalos, A.; Celis, M.; Lárraga, J.

    2004-09-01

    Intensity Modulated Radiation Therapy (IMRT) is an oncology treatment technique that employs non-uniform beam intensities to deliver highly conformal radiation to the targets while minimizing doses to normal tissues and critical organs. A key element for a successful clinical implementation of IMRT is establishing a dosimetric verification process that can ensure that delivered doses are consistent with calculated ones for each patient. To this end we are developing a fast quality control procedure, based on film dosimetry techniques, to be applied to the 6 MV Novalis linear accelerator for IMRT of the Instituto Nacional de Neurología y Neurocirugía (INNN) in Mexico City. The procedure includes measurements of individual fluence maps for a limited number of fields and dose distributions in 3D using extended dose-range radiographic film. However, the film response to radiation might depend on depth, energy and field size, and therefore compromise the accuracy of measurements. In this work we present a study of the dependence of Kodak EDR2 film's response on the depth, field size and energy, compared with those of Kodak XV2 film. The first aim is to devise a fast and accurate method to determine the calibration curve of film (optical density vs. doses) commonly called a sensitometric curve. This was accomplished by using three types of irradiation techniques: Step-and-shoot, dynamic and static fields.

  15. Apparatus for detecting alpha radiation in difficult access areas

    DOEpatents

    Steadman, Peter; MacArthur, Duncan W.

    1997-09-02

    An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure.

  16. Apparatus for detecting alpha radiation in difficult access areas

    DOEpatents

    Steadman, P.; MacArthur, D.W.

    1997-09-02

    An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure is disclosed. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure. 4 figs.

  17. Colloquium: Nanoplasmas generated by intense radiation

    NASA Astrophysics Data System (ADS)

    Ostrikov, Kostya Ken; Beg, Farhat; Ng, Andrew

    2016-01-01

    Solid, liquid, and gaseous states of matter can exist and acquire unique properties when reduced in size into a nanometer domain. This Colloquium explores the approaches to produce plasmas with nanometer dimensions and the arising physical phenomena and properties associated with this extreme, nonequilibrium state of matter. Analysis of the spatial confinement, coupling, ideality, and degeneracy criteria lead to the possibilities to produce transient nanoplasma states near, in, and from solids by using ultrafast photoexcitation. These states arise through the interplay of nonequilibrium, many-body Coulomb interactions, thermal, and nonthermal effects. Examples include photoexcited electron-hole plasmas in semiconductors, transient solid-to-plasma states including warm dense matter, nanoplasmas produced by interaction of nanoclusters and nanoparticles with intense radiation, nanoplasmas in high-energy ion tracks within solids, nanoplasmas in relativistic regime, and others. Physical phenomena arising due to the localization of high-energy densities to microscales and nanoscales and their potential applications are discussed.

  18. Redistribution of radiation for the wings of Lyman-alpha

    NASA Technical Reports Server (NTRS)

    Yelnik, J.-B.; Burnett, K.; Cooper, J.; Ballagh, R. J.; Voslamber, D.

    1981-01-01

    Earlier work on redistribution of radiation by collisions for isolated lines is extended to overlapping lines, and an explicit expression for the frequency redistribution is given for Lyman-alpha. This expression is valid, even when the emitted photon is in the (non-impact) line wings. A simple physical explanation of the result is possible.

  19. Intense alpha-particle emitting crystallites in uranium mill wastes

    USGS Publications Warehouse

    Landa, E.R.; Stieff, L.R.; Germani, M.S.; Tanner, A.B.; Evans, J.R.

    1994-01-01

    Nuclear emulsion microscopy has demonstrated the presence of small, intense ??-particle emitting crystallites in laboratory-produced tailings derived from the sulfuric acid milling of uranium ores. The ??-particle activity is associated with the isotope pair 210Pb 210Po, and the host mineral appears to be PbSO4 occurring as inclusions in gypsum laths. These particles represent potential inhalation hazards at uranium mill tailings disposal areas. ?? 1994.

  20. SOLAR H{alpha} OSCILLATIONS FROM INTENSITY AND DOPPLER OBSERVATIONS

    SciTech Connect

    Jackiewicz, Jason; Balasubramaniam, K. S.

    2013-03-01

    Chromospheric wave activity around flares and filaments has been a research focus for years, and could provide indirect measurements of local conditions that are not otherwise accessible. One interesting observed phenomenon is oscillations in filaments, activated by distant flares and the large-scale waves they produce. Characteristics of these oscillations, such as periods, amplitudes, and lifetimes, can provide unique information about the filament. We measure oscillation properties in flares and filaments from H{alpha} chromospheric data using a new method that provides important spatial and frequency content of the dynamics. We apply the method to two flare events where filaments are observed to oscillate and determine their properties. We find strong oscillatory signal in flaring active regions in the chromosphere over a range of frequencies. Two filaments are found to oscillate without any detectable chromospheric wave acting as an activation mechanism. We find that filaments oscillate with periods of tens of minutes, but variations are significant at small spatial scales along the filamentary region. The results suggest that there is a frequency dependence of the oscillation amplitude, as well as a spatial dependence along single filaments that is more difficult to quantify. It also appears that the strength of the oscillations does not necessarily depend on the strength of the trigger, although there are other possible effects that make this conclusion preliminary. Applications of this technique to other events and different data sets will provide important new insights into the local energy densities and magnetic fields associated with dynamic chromospheric structures.

  1. FLASH requirements for the high intensity radiated field electromagnetic environment

    NASA Astrophysics Data System (ADS)

    Murdock, John K.

    1995-05-01

    The worldwide proliferation of high intensity emitting sources and the more electric aircraft increase the intensity of the Electromagnetic Environment (EME) in which aircraft must operate. A FLASH program HIRF (High Intensity Radiated Field) EME requirement is derived to cover both commercial and military fixed and rotary wing aircraft. This requirement is derived from the radiated susceptibility requirement documents of both the FAA and U.S. military. Specific test data and analysis will show that we can meet this requirement.

  2. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    PubMed

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium. PMID:11158669

  3. Shorter, Intensive Radiation Works for Prostate Cancer

    MedlinePlus

    ... April 4, 2016 (HealthDay News) -- A slightly higher dose of radiation therapy for early stage prostate cancer may reduce treatment time without compromising effectiveness, researchers report. The ...

  4. Intensity clamping in the filament of femtosecond laser radiation

    SciTech Connect

    Kandidov, V P; Fedorov, V Yu; Tverskoi, O V; Kosareva, O G; Chin, S L

    2011-04-30

    We have studied numerically the evolution of the light field intensity and induced refractive index of a medium upon filamentation of femtosecond laser radiation in air. It is shown that the intensity clamping results from the dynamic balance of optical powers of nonlinear lenses, induced by radiation due to the Kerr nonlinearity of air, and laser plasma produced during photoionisation. We have found the relation between the peak values of the light field intensity and the electron density in laser-produced plasma, as well as the transverse sizes of the filament and the plasma channel. (effects of laser radiation on matter)

  5. Supersonic intensity and non-negative intensity for prediction of radiated sound.

    PubMed

    Liu, Daipei; Peters, Herwig; Marburg, Steffen; Kessissoglou, Nicole

    2016-05-01

    Two numerical methods to identify the surface areas of a vibrating structure that radiate sound are presented. The supersonic intensity identifies only the supersonic wave components of the sound field contributing to far-field radiated sound. The supersonic intensity is calculated using a two-dimensional convolution between a spatial radiation filter and the sound field. To compute the spatial radiation filter, the shortest surface distance between two points on the structure is calculated using the geodesic distance method. The non-negative intensity is based on acoustic radiation modes and identifies the radiated sound power from a vibrating structure. Numerical models of a baffled plate, a cylinder and an engine crankcase are presented. The supersonic intensity is shown to be difficult to implement at low frequencies due to the size of the spatial radiation filter and accuracy of the surface distances. A cut-off coefficient associated with the acoustic wavenumber of the spatial radiation filter is used to reduce the aperture error. A comparison of the two intensity-based techniques both in terms of a sound power ratio and the modal assurance criterion is introduced to identify the optimal values of the cut-off coefficients that result in better convergence between the intensity techniques. PMID:27250172

  6. Measurement of the Relative Intensity of the Ly-(alpha) Lines in Fe 25+

    SciTech Connect

    Wong, K L; Beiersdorfer, P; Reed, K J; Osterheld, A L

    2002-06-18

    The intensity of the polarized Ly-{alpha}{sub 1} (2p{sub 3/2} {yields} 1s{sub 1/2}) transition has been measured relative to that of the unpolarized Ly-{alpha}{sub 2} (2p{sub 1/2} {yields} 1s{sub 1/2}) transition in Fe{sup 25+}. The measurements were made with the Livermore electron beam ion trap EBIT-II for beam energies from threshold to 2.5 times threshold. The results are compared to the corresponding intensity ratio predicted using excitation cross sections from distorted-wave calculations, which includes polarization, the M1(2s{sub 1/2} {yields} 1s{sub 1/2}) transition, and cascade contributions. Discrepancies are found that tend to confirm a recent report of a measurement of the Ly-{alpha} lines in Ti{sup 21+} performed on the Tokyo electron beam ion trap.

  7. An Alpha and Theta Intensive and Short Neurofeedback Protocol for Healthy Aging Working-Memory Training

    PubMed Central

    Reis, Joana; Portugal, Ana Maria; Fernandes, Luís; Afonso, Nuno; Pereira, Mariana; Sousa, Nuno; Dias, Nuno S.

    2016-01-01

    The present study tested the effects of an intensive and short alpha and theta neurofeedback (NF) protocol in working memory (WM) performance in a healthy elder population and explored the effects of a multimodal approach, by supplementing NF with cognitive tasks. Participants were allocated to four groups: NF (N = 9); neurofeedback supplemented with cognitive training (NFCT) (N = 8); cognitive training (CT) (N = 7) and sham neurofeedback (Sham-NF) (N = 6). The intervention consisted in 30-min sessions for 8 days. The NF group presented post intervention increases of alpha and theta relative power as well as performance in the matrix rotation task. In addition, a successful up training of frontal theta showed positive correlation with an improvement of post-training alpha and a better performance in the matrix rotation task. The results presented herein suggest that an intensive and short NF protocol enables elders to learn alpha and theta self-modulation and already presents moderate improvements in cognition and basal EEG. Also, CT group showed moderate performance gains on the cognitive tasks used during the training sessions but no clear improvements on neurophysiology and behavioral measurements were observed. This study represents a first attempt to study the effects of an intensive and short NF protocol in WM performance of elders. The evidence presented here suggests that an intensive and short NF intervention could be a valid alternative for introduction of older populations to NF methodologies. PMID:27458369

  8. An Alpha and Theta Intensive and Short Neurofeedback Protocol for Healthy Aging Working-Memory Training.

    PubMed

    Reis, Joana; Portugal, Ana Maria; Fernandes, Luís; Afonso, Nuno; Pereira, Mariana; Sousa, Nuno; Dias, Nuno S

    2016-01-01

    The present study tested the effects of an intensive and short alpha and theta neurofeedback (NF) protocol in working memory (WM) performance in a healthy elder population and explored the effects of a multimodal approach, by supplementing NF with cognitive tasks. Participants were allocated to four groups: NF (N = 9); neurofeedback supplemented with cognitive training (NFCT) (N = 8); cognitive training (CT) (N = 7) and sham neurofeedback (Sham-NF) (N = 6). The intervention consisted in 30-min sessions for 8 days. The NF group presented post intervention increases of alpha and theta relative power as well as performance in the matrix rotation task. In addition, a successful up training of frontal theta showed positive correlation with an improvement of post-training alpha and a better performance in the matrix rotation task. The results presented herein suggest that an intensive and short NF protocol enables elders to learn alpha and theta self-modulation and already presents moderate improvements in cognition and basal EEG. Also, CT group showed moderate performance gains on the cognitive tasks used during the training sessions but no clear improvements on neurophysiology and behavioral measurements were observed. This study represents a first attempt to study the effects of an intensive and short NF protocol in WM performance of elders. The evidence presented here suggests that an intensive and short NF intervention could be a valid alternative for introduction of older populations to NF methodologies. PMID:27458369

  9. Radiation intensity of lignite-fired oxy-fuel flames

    SciTech Connect

    Andersson, Klas; Johansson, Robert; Hjaertstam, Stefan; Johnsson, Filip; Leckner, Bo

    2008-10-15

    The radiative heat transfer in oxy-fuel flames is compared to corresponding conditions in air-fuel flames during combustion of lignite in the Chalmers 100 kW oxy-fuel test facility. In the oxy-fuel cases the flue-gas recycle rate was varied, so that, in principle, the same stoichiometry was kept in all cases, whereas the oxygen fraction in the recycled flue-gas mixture ranged from 25 to 29 vol.%. Radial profiles of gas concentration, temperature and total radiation intensity were measured in the furnace. The temperature, and thereby the total radiation intensity of the oxy-fuel flames, increases with decreasing flue-gas recycle rate. The ratio of gas and total radiation intensities increases under oxy-fuel conditions compared to air-firing. However, when radiation overlap between gas and particles is considered the ratios for air-firing and oxy-fuel conditions become more similar, since the gas-particle overlap is increased in the CO{sub 2}-rich atmosphere. A large fraction of the radiation in these lignite flames is emitted by particles whose radiation was not significantly influenced by oxy-fuel operation. Therefore, an increment of gas radiation due to higher CO{sub 2} concentration is not evident because of the background of particle radiation, and, the total radiation intensities are similar during oxy-fuel and air-fuel operation as long as the temperature distributions are similar. (author)

  10. RADIATIVE TRANSFER MODELING OF Ly{alpha} EMITTERS. I. STATISTICS OF SPECTRA AND LUMINOSITY

    SciTech Connect

    Zheng Zheng; Cen Renyue; Trac, Hy; Miralda-Escude, Jordi

    2010-06-10

    We combine a cosmological reionization simulation with box size of 100 h {sup -1} Mpc on a side and a Monte Carlo Ly{alpha} radiative transfer code to model Ly{alpha} Emitters (LAEs) at z {approx} 5.7. The model introduces Ly{alpha} radiative transfer as the single factor for transforming the intrinsic Ly{alpha} emission properties into the observed ones. Spatial diffusion of Ly{alpha} photons from radiative transfer results in extended Ly{alpha} emission and only the central part with high surface brightness can be observed. Because of radiative transfer, the appearance of LAEs depends on density and velocity structures in circumgalactic and intergalactic media as well as the viewing angle, which leads to a broad distribution of apparent (observed) Ly{alpha} luminosity for a given intrinsic Ly{alpha} luminosity. Radiative transfer also causes frequency diffusion of Ly{alpha} photons. The resultant Ly{alpha} line is asymmetric with a red tail. The peak of the Ly{alpha} line shifts toward longer wavelength and the shift is anti-correlated with the apparent-to-intrinsic Ly{alpha} luminosity ratio. The simple radiative transfer model provides a new framework for studying LAEs. It is able to explain an array of observed properties of z {approx} 5.7 LAEs in Ouchi et al., producing Ly{alpha} spectra, morphology, and apparent Ly{alpha} luminosity function (LF) similar to those seen in observation. The broad distribution of apparent Ly{alpha} luminosity at fixed UV luminosity provides a natural explanation for the observed UV LF, especially the turnover toward the low luminosity end. The model also reproduces the observed distribution of Ly{alpha} equivalent width (EW) and explains the deficit of UV bright, high EW sources. Because of the broad distribution of the apparent-to-intrinsic Ly{alpha} luminosity ratio, the model predicts effective duty cycles and Ly{alpha} escape fractions for LAEs.

  11. Intense and energetic radiation from crystalline undulators

    NASA Astrophysics Data System (ADS)

    Uggerhøj, U. I.; Wistisen, T. N.

    2015-07-01

    With the recent experimental confirmation of the existence of energetic radiation from a Small Amplitude, Small Period (SASP) crystalline undulator (Wistisen et al., 2014), the field of specially manufactured crystals, from which specific radiation characteristics can be obtained, has evolved substantially. In the present paper we show how the radiation spectra can be tuned, using electrons and positrons of energies from 100 MeV up to 20 GeV. The latter energy is relevant for possible experiments at the FACET facility at Stanford Linear Accelerator Center (SLAC), whereas 100 MeV has been chosen to show the potentialities connected to using crystalline undulators as radiation targets for Nuclear Waste Transmutation (NWT). Energies in the few hundred MeV range are relevant for the facilities at the MAinzer MIcrotron (MAMI). For the 20 GeV case we show explicitly that quantum corrections to the emission spectrum become very significant, an effect that may be observed in the near future using the FACET beam at SLAC.

  12. Enhanced homologous recombination is induced by alpha-particle radiation in somatic cells of Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Bian, Po; Liu, Ping; Wu, Yuejin

    Almost 9 percent of cosmic rays which strike the earth's atmosphere are alpha particles. As one of the ionizing radiations (IR), its biological effects have been widely studied. However, the plant genomic instability induced by alpha-particle radiation was not largely known. In this research, the Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by alpha-particle radiation (3.3MeV). The pronounced effects of systemic exposure to alpha-particle radiation on the somatic homologous recombination frequency (HRF) were found at different doses. The 10Gy dose of radiation induced the maximal HRF which was 1.9-fold higher than the control. The local radiation of alpha-particle (10Gy) on root also resulted in a 2.5-fold increase of somatic HRF in non-radiated aerial plant, indicating that the signal(s) of genomic instability was transferred to non-radiated parts and initiated their genomic instability. Concurrent treatment of seedlings of Arabidopsis thaliana with alpha-particle and DMSO(ROS scavenger) both in systemic and local radiation signifi- cantly suppressed the somatic HR, indicating that the free radicals produced by alpha-particle radiation took part in the production of signal of genomic instability rather than the signal transfer. Key words: alpha-particle radiation, somatic homologous recombination, genomic instability

  13. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Scarlata, Claudia; Hayes, Matthew; Miller, Brendan P.; Pushnig, Johannes; Jansson, Gustav

    2016-01-01

    The class of objects that reionized the intergalactic hydrogen remains an observational and theoretical challenge. Recently, the shape of the Lyman-alpha (Lya) emission line profile has been proposed as a way to pre-select Lyman Continuum (LyC) leaking galaxies. We present results of deep spectroscopic observations obtained with the Cosmic Origin Spectrograph on the HST of a sample of 4 Lya-emitting galaxies at z~0.3, chosen to be candidate LyC leaking galaxies, on the grounds of blueshifted peaks of Lya emission/symmetric extended Lya wings. We do not detect ionizing radiation escaping from these objects, with upper 3sigma limits on the absolute escape fraction of LyC photons between 14 and 2%.

  14. Compton interaction of free electrons with intense low frequency radiation

    NASA Technical Reports Server (NTRS)

    Illarionov, A. F.; Kompaneyets, D. A.

    1978-01-01

    Electron behavior in an intense low frequency radiation field, with induced Compton scattering as the primary mechanism of interaction, is investigated. Evolution of the electron energy spectrum is studied, and the equilibrium spectrum of relativistic electrons in a radiation field with high brightness temperature is found. The induced radiation pressure and heating rate of an electron gas are calculated. The direction of the induced pressure depends on the radiation spectrum. The form of spectrum, under the induced force can accelerate electrons to superrelativistic energies is found.

  15. Investigation of the Frohlich hypothesis with high intensity terahertz radiation

    NASA Astrophysics Data System (ADS)

    Weightman, Peter

    2014-03-01

    This article provides an update to recent reviews of the Frohlich hypothesis that biological organisation is facilitated by the creation of coherent excited states driven by a flow of free energy provided by metabolic processes and mediated by molecular motions in the terahertz range. Sources of intense terahertz radiation have the potential to test this hypothesis since if it is true the growth and development of sensitive systems such as stem cells should be influenced by irradiation with intense terahertz radiation. A brief survey of recent work shows that it is not yet possible to make an assessment of the validity of the Frohlich hypothesis. Under some conditions a variety of cell types respond to irradiation with intense THz radiation in ways that involve changes in the activity of their DNA. In other experiments very intense and prolonged THz radiation has no measureable effect on the behavior of very sensitive systems such as stem cells. The wide variation in experimental conditions makes it impossible to draw any conclusions as to characteristics of THz radiation that will induce a response in living cells. It is possible that in environments suitable for their maintenance and growth cells are capable of compensating for any effects caused by exposure to THz radiation up to some currently unknown level of THz peak power.

  16. Radiation cross-linking of ethylene vinyl alcohol copolymer functionalized with m-isopropenyl-[alpha],[alpha]-dimethyl benzyl isocyanate

    SciTech Connect

    Ekman, K.B.; Naesman, J.H. . Lab. of Polymer Technology)

    1993-10-10

    An ethylene vinyl alcohol copolymer was functionalized with m-isopropenyl-[alpha],[alpha]-dimethyl benzyl isocyanate using reactive processing in a mixer. The functionalization introduces pendant unsaturation to the polymer, which allows radiation cross-linked to gel contents >70% at radiation doses below 100 kGy. Unfunctionalized ethylene vinyl alcohol copolymer, on the other hand, forms no gel upon irradiation. The functionalization was completed within a few minutes of reactive mixing, which was confirmed with both FTIR and [sup 13]C-NMR measurements. The oxygen permeability of ethylene vinyl alcohol copolymer increased with increasing degree of functionalization, and irradiation of the samples formed trapped radicals, which act as oxygen scavengers. Consequently no oxygen permeability was detected. However, radical activity was inhibited by annealing the samples at 110 C resulting in a 24% higher oxygen permeability value for the irradiated unfunctionalized copolymer. The oxygen permeability values of the irradiated functionalized samples were approximately 13% lower. Laminates of m-isopropenyl-[alpha],[alpha]-dimethyl benzyl isocyanate functionalized ethylene vinyl alcohol copolymer and m-isopropenyl-[alpha],[alpha]-dimethyl benzyl isocyanate functionalized ethylene hydroxyethyl methacrylate copolymer acquired improved adhesive strength both at dry and wet conditions as well as at elevated temperature upon exposure to radiation.

  17. A capillary discharge plasma source of intense VUV radiation

    SciTech Connect

    Sobel'man, Igor I; Shevelko, A P; Yakushev, O F; Knight, L V; Turley, R S

    2003-01-31

    The results of investigation of a capillary discharge plasma, used as a source of intense VUV radiation and soft X-rays, are presented. The plasma was generated during the discharge of low-inductance condensers in a gas-filled ceramic capillary. Intense line radiation was observed in a broad spectral range (30-400 A) in various gases (CO{sub 2}, Ne, Ar, Kr, Xe). The absolute radiation yield for the xenon discharge was {approx}5 mJ (2{pi} sr){sup -1} pulse{sup -1} within a spectral band of width 9 A at 135 A. Such a radiation source can be used for various practical applications, such as EUV projection lithography, microscopy of biological objects in a 'water window', reflectometry, etc. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  18. Scatter radiation intensities around full-field digital mammography units.

    PubMed

    Judge, M A; Keavey, E; Phelan, N

    2013-01-01

    The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding. PMID:23239693

  19. A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition

    SciTech Connect

    Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

    2005-08-08

    The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

  20. Observations of Geocoronal H-alpha Emission Intensities Over Changing Solar Geophysical Conditions

    NASA Astrophysics Data System (ADS)

    Nossal, S. M.; Roesler, F. L.; Mierkiewicz, E. J.; Reynolds, R. J.; Bishop, J.; Madsen, G.

    2002-05-01

    We will present observations of thermospheric + exospheric hydrogen H-alpha emissions taken by the Wisconsin H-alpha Mapper Fabry-Perot (WHAM) during the time period of 1997 through 2001. WHAM has acquired more than 37,000 spectra to date over about 100 nights. These observations span from near solar minimum through solar maximum conditions. The WHAM Fabry-Perot is located at the Kitt Peak Observatory near Tucson, Arizona and is remotely operable from Wisconsin. WHAM's resolving power is sufficient for the retrieval of the geocoronal H-alpha emission intensity, but not for the resolution of the line profile. The resolution, precision and high signal-to-noise of the WHAM Fabry-Perot facilitate the separation of the terrestrial emission from the galactic emission. Variability in the WHAM geocoronal H-alpha observations over the rise of the solar cycle is limited to within about 35% with higher emissions observed during solar maximum conditions. This result is consistent with observed limits to the variability over the past solar cycle made using similarly designed Fabry-Perot instruments, but with photomultiplier detection, from midlatitude Wisconsin and Haleakala observing sites. These data are also consistent with comparisons made between winter solstice zenith observations taken during the early 1990's from Wisconsin (NSF-CHARM campaign) and WHAM zenith observations.

  1. Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

    NASA Astrophysics Data System (ADS)

    Skelton, E. F.; Elam, W. T.; Qadri, S. B.; Webb, A. W.; Schiferl, D.

    Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.

  2. Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

    NASA Astrophysics Data System (ADS)

    Skelton, E. F.; Elam, W. T.; Qadri, S. B.; Webb, A. W.; Schiferl, D.

    1986-05-01

    Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that, at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather, there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.

  3. Conversion efficiency and spectral broadening of the K-{alpha} line emitted from planar titanium targets irradiated with ultra-short laser pulses of high intensity

    SciTech Connect

    Arora, V.; Singhal, H.; Naik, P. A.; Gupta, P. D.

    2011-10-15

    A study of the conversion efficiency and line shape of the K-{alpha} x-ray line radiation from a planar titanium target irradiated by an ultra-short laser pulse is performed. The conversion efficiency and spectral broadening are studied as a function of laser intensity (5 x 10{sup 16}-10{sup 18} W cm{sup -2}), laser pulse duration (45 fs-800 fs), and laser fluence (2 x 10{sup 3}-4.2 x 10{sup 4} J cm{sup -2}). The K-{alpha}{sub 1} line (4510 eV) is observed to be broadened (up to {approx}9 eV), predominantly towards the higher energy side and strongly depends on the laser fluence rather than on laser intensity. The reason for the spectral broadening is attributed to K-{alpha} emission in warm dense plasma. The role of hot electrons and direct laser heating on spectral broadening is outlined. In addition to this, our observations indicates that the presence of pre-plasma strongly contribute to the observed broadening through the inner-shell transitions in multiply charged titanium ions in the pre-plasma. The appropriate laser irradiation parameters to achieve high conversion efficiency and minimum spectral width of the K-{alpha} radiation are identified. The study is important, since the control of the spectral profile is of general interest for diffraction or scattering experiments in view of its potential in increasing temporal resolution.

  4. Response of two-phase droplets to intense electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-01-01

    The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

  5. Wake Measurements at alpha ventus - Dependency on Stability and Turbulence Intensity

    NASA Astrophysics Data System (ADS)

    Westerhellweg, Annette; Cañadillas, Beatriz; Kinder, Friederike; Neumann, Tom

    2014-12-01

    Wind and power deficit in the wake are assessed for the offshore wind farm Alpha Ventus. Operational data are evaluated for the power deficit in the wake of a single wind turbine and in a row of wind turbines. The wake of a single wind turbine is described by the maximum power deficit and expansion width of the wake. The impact of atmospheric stability in respect to vertical wind shear and turbulence intensity is assessed showing that wake effects are more pronounced under stable conditions.

  6. Interpreting the Unresolved Intensity of Cosmologically Redshifted Line Radiation

    NASA Astrophysics Data System (ADS)

    Switzer, E. R.; Chang, T.-C.; Masui, K. W.; Pen, U.-L.; Voytek, T. C.

    2015-12-01

    Intensity mapping experiments survey the spectrum of diffuse line radiation rather than detect individual objects at high signal-to-noise ratio. Spectral maps of unresolved atomic and molecular line radiation contain three-dimensional information about the density and environments of emitting gas and efficiently probe cosmological volumes out to high redshift. Intensity mapping survey volumes also contain all other sources of radiation at the frequencies of interest. Continuum foregrounds are typically ~102-103 times brighter than the cosmological signal. The instrumental response to bright foregrounds will produce new spectral degrees of freedom that are not known in advance, nor necessarily spectrally smooth. The intrinsic spectra of foregrounds may also not be well known in advance. We describe a general class of quadratic estimators to analyze data from single-dish intensity mapping experiments and determine contaminated spectral modes from the data themselves. The key attribute of foregrounds is not that they are spectrally smooth, but instead that they have fewer bright spectral degrees of freedom than the cosmological signal. Spurious correlations between the signal and foregrounds produce additional bias. Compensation for signal attenuation must estimate and correct this bias. A successful intensity mapping experiment will control instrumental systematics that spread variance into new modes, and it must observe a large enough volume that contaminant modes can be determined independently from the signal on scales of interest.

  7. Interpreting The Unresolved Intensity Of Cosmologically Redshifted Line Radiation

    NASA Technical Reports Server (NTRS)

    Switzer, E. R.; Chang, T.-C.; Masui, K. W.; Pen, U.-L.; Voytek, T. C.

    2016-01-01

    Intensity mapping experiments survey the spectrum of diffuse line radiation rather than detect individual objects at high signal-to-noise ratio. Spectral maps of unresolved atomic and molecular line radiation contain three-dimensional information about the density and environments of emitting gas and efficiently probe cosmological volumes out to high redshift. Intensity mapping survey volumes also contain all other sources of radiation at the frequencies of interest. Continuum foregrounds are typically approximately 10(sup 2)-10(Sup 3) times brighter than the cosmological signal. The instrumental response to bright foregrounds will produce new spectral degrees of freedom that are not known in advance, nor necessarily spectrally smooth. The intrinsic spectra of fore-grounds may also not be well known in advance. We describe a general class of quadratic estimators to analyze data from single-dish intensity mapping experiments and determine contaminated spectral modes from the data themselves. The key attribute of foregrounds is not that they are spectrally smooth, but instead that they have fewer bright spectral degrees of freedom than the cosmological signal. Spurious correlations between the signal and foregrounds produce additional bias. Compensation for signal attenuation must estimate and correct this bias. A successful intensity mapping experiment will control instrumental systematics that spread variance into new modes, and it must observe a large enough volume that contaminant modes can be determined independently from the signal on scales of interest.

  8. Coherent Cherenkov radiation as an intense THz source

    NASA Astrophysics Data System (ADS)

    Bleko, V.; Karataev, P.; Konkov, A.; Kruchinin, K.; Naumenko, G.; Potylitsyn, A.; Vaughan, T.

    2016-07-01

    Diffraction and Cherenkov radiation of relativistic electrons from a dielectric target has been proposed as mechanism for production of intense terahertz (THz) radiation. The use of an extremely short high-energy electron beam of a 4th generation light source (X-ray free electron laser) appears to be very promising. A moderate power from the electron beam can be extracted and converted into THz radiation with nearly zero absorption losses. The initial experiment on THz observation will be performed at CLARA/VELA FEL test facility in the UK to demonstrate the principle to a wider community and to develop the radiator prototype. In this paper, we present our theoretical predictions (based on the approach of polarization currents), which provides the basis for interpreting the future experimental measurements. We will also present our hardware design and discuss a plan of the future experiment.

  9. Modal analysis and intensity of acoustic radiation of the kettledrum.

    PubMed

    Tronchin, Lamberto

    2005-02-01

    The acoustical features of kettledrums have been analyzed by means of modal analysis and acoustic radiation (p/v ratio) measurements. Modal analysis of two different kettledrums was undertaken, exciting the system both by a hammer and a shaker. Up to 15 vibrational modes were clearly identified. Acoustic radiation was studied using two ways. Based on previous experiments of other researchers, a new parameter, called intensity of acoustic radiation (IAR), has been defined and measured. Results show a strict relationship between IAR and the frequency response function (FRF, which is the v/F ratio), and IAR also strongly relates the modal pattern to acoustic radiation. Finally, IAR is proposed for vibro-acoustical characterization of kettledrums and other musical instruments such as strings, pianos, and harpsichords. PMID:15759711

  10. Alpha radiation effects on weapons-grade plutonium encapsulating materials

    NASA Astrophysics Data System (ADS)

    Saglam, Mehmet

    The scientific understanding of material problems in the long-term storage of plutonium pits is investigated using experimental and theoretical models. The durability of the plutonium pit depends on the integrity of the metal cladding that encapsulates the plutonium. Given sufficient time, the energetic alpha particles (helium nuclei) produced by nuclear decay of the plutonium would degrade the mechanical strength of the metal cladding which could lead to cladding failure and dispersion of plutonium. It is shown that the long-term behavior of the encapsulating materials can be simulated by beam implantation and subsequent analysis using experimental techniques of Electron Microscopy and Neutron Depth Profiling (NDP). In addition computer simulations using the TRIM code were made in order to correlate the measurements to cladding damage. The Neutron Depth Profiling measurements done with samples that had 10 16 cm-2 3He beam implant dose showed no helium redistribution, indicating no microcracking between bubbles, for both beryllium and stainless steel, the pit cladding materials of interest. However, helium redistribution and significant helium loss were observed for samples with a beam implant dose of 1018 cm-2 , indicating microstructural damage. The SEM observations were consistent with the NDP measurements. The proper interpretation of the results rests on the realization that (i)the deleterious effects are related to helium concentration, not implant dose, and (ii)a specified maximum concentration of helium is achieved with a much smaller dose when monoenergetic ions are implanted using beam geometry than for the situation where Pu alphas stop in the pit cladding. Helium is distributed over a much smaller depth interval for beam implantation of monoenergetic ions as compared to the pit cladding implanted ions. Taking this effect into account and using the calculated pit implant dose gives a pit storage time for the 1016 cm-2 beam implant dose results equal to

  11. Determination of molecular size of alpha-1 and alpha-2 adrenoceptors in rat mesenteric artery by radiation inactivation

    SciTech Connect

    Agrawal, D.K.; Grover, A.K.; Daniel, E.E.; Jung, C.Y.

    1986-03-01

    Radiation inactivation of alpha-1 and alpha-2 adrenoceptors in the purified plasma membranes of rat mesenteric artery has been performed with high energy electrons at -45 to -55 degrees C. Alpha-1 and alpha-2 adrenoceptor inactivation was monitored with (3H) prazosin and (3H)yohimbine binding, respectively. Internal endogenous and external standards of known molecular weight were used in these studies to determine the molecular size. The average value of D37 for the (3H)prazosin binding site was 6.75 +/- 0.62 Mrad (n = 4) with an estimated molecular size of 122,921 +/- 11,329 Daltons. However, the average value of D37 for the (3H) yohimbine binding site was higher (D37 = 10.05 +/- 0.91 Mrad) and accordingly the molecular size of this binding site was less than the (3H)prazosin binding sites (molecular weight = 82,540 +/- 7478 Daltons; n = 4). Irradiation did not change the dissociation constant of either radioligand, suggesting that the loss of the radioligand binding sites after radiation is due to receptor protein inactivation. These results confirm our earlier finding that (3H)prazosin and (3H)yohimbine bind to two distinct sites in the plasma membranes of rat mesenteric artery. Whether both of these sites are the subunits of a common macromolecule of alpha adrenoceptor on vascular smooth muscle in rat mesenteric artery cannot be concluded from these results. This report is the first one in the literature on the molecular size of alpha-1 and alpha-2 binding sites in vascular smooth muscle.

  12. Fire Intensity Data for Validation of the Radiative Transfer Equation

    SciTech Connect

    Blanchat, Thomas K.; Jernigan, Dann A.

    2016-01-01

    A set of experiments and test data are outlined in this report that provides radiation intensity data for the validation of models for the radiative transfer equation. The experiments were performed with lightly-sooting liquid hydrocarbon fuels that yielded fully turbulent fires 2 m diameter). In addition, supplemental measurements of air flow and temperature, fuel temperature and burn rate, and flame surface emissive power, wall heat, and flame height and width provide a complete set of boundary condition data needed for validation of models used in fire simulations.

  13. Mutagenesis and repair by low doses of alpha radiation in mammalian cells.

    PubMed

    Puck, Theodore T; Johnson, Robert; Webb, Patricia; Cui, Helen; Valdez, Joseph G; Crissman, Harry

    2002-09-17

    Low doses of alpha radiation in basements have been causally implicated in lung cancer. Previous studies have concentrated on high dose effects, for which no significant repair was found. In the present study, the methodology for measuring mutation by quantitating mitotic breaks and gaps was found to be applicable to G2-phase Chinese hamster ovary cells irradiated with 10-50 cGy of alpha radiation. The mutation yield in such cells closely resembles that of gamma irradiation. Caffeine, which inhibits repair, produces the same straight line increase of alpha and gamma mutation yields plotted against the dose. In the absence of caffeine, the repair of alpha radiation lesions is almost twice as great as for gamma radiation. Mitotic index changes substantiate these interpretations. It is proposed that the higher ion density associated with alpha radiation may result in fewer lesions being missed by the repair processes. The quantitation of chromosomal lesions for G2 cells exposed to low doses of alpha radiation, gamma radiation, or chemical mutagens in the presence and absence of caffeine is a rapid and reproducible methodology. Protection from mutational disease in a fashion similar to the use of sanitation for infectious disease appears practical. PMID:12198179

  14. RadICalc. A program for estimating radiation intensity of radionuclide mixtures

    SciTech Connect

    Robinson, John W.; Dion, Michael P.; Eiden, Gregory C.; Farmer, Orville T.; Liezers, Martin

    2014-09-24

    RadICalc is a cross-platform program designed to calculate the intensity of radiation released by the decay of arbitrary isotopic mixtures. It was developed to address the need for a program that could calculate the composition, activity, and measurable radiation of a sample over time without significant effort from end-users. RadICalc uses Bateman's solutions for radioactive decay to determine activity over time. Radiation intensities are subsequently calculated using a database containing information about alpha particles, beta electrons, gamma- rays, conversion and Auger electrons, and X-rays. The user interface accepts input for isotopic mixture, initial number of atoms, and time passed since sample composition was known. Results are plotted graphically, and there is a search interface provided to and isotopes of interest. RadICalc can determine activity and radiation expected at specific masses with user-defined molecules in addition to atomic species; the latter is useful in mass based isotope separations for radiometric counting applications, a novel method under development at PNNL.

  15. Absolute intensity of radiation emitted by uranium plasmas

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.; Lee, J. H.; Mcfarland, D. R.

    1975-01-01

    The absolute intensity of radiation emitted by fissioning and nonfissioning uranium plasmas in the spectral range from 350 nm to 1000 nm was measured. The plasma was produced in a plasma-focus apparatus and the plasma properties are simular to those anticipated for plasma-core nuclear reactors. The results are expected to contribute to the establishment of design criteria for the development of plasma-core reactors.

  16. The Effect of Intense Laser Radiation on Atomic Collisions

    NASA Astrophysics Data System (ADS)

    Young, Stephen Michael Radley

    1991-02-01

    Available from UMI in association with The British Library. Requires signed TDF. We have carried out theoretical and experimental studies into the effect of intense laser radiation on atomic collisions. The first experiment used neon. Excitation by electron impact in a gas discharge demanded a pressure of at least 0.075 Torr. Measurement of the intensity of 3^1S_0to 3^1P_1 fluorescence has been made for the case where high intensity ASE wings in the laser profile and background laser scatter are unimportant, with the laser tuned to resonance. The field intensity required to produce strong field fluorescence (exemplified by the Mollow triplet) was found to give rise to complications capable of screening the effects sought. Our theoretical model has suggested that at finite detunings, line-centre fluorescence will dominate Rayleigh scatter and omega_3 fluorescence. Our measurements provide information on the saturation of neon fluorescence but not of the variation of the intense field collision rate. Absorption of weak field 253.7 nm laser photons by ground state mercury atoms yielded a high 6 ^3P_1 population at a lower pressure of 0.02 Torr. The Mollow triplet has been observed in the self-broadened mercury system. Dressing of the upper transition (6^3P_1rightarrow 7^3S_1) by an intense laser close to 435.8 nm yielded the strong field signal. Polarisation studies were made possible by the 3-level mercury system (radiation trapping in a 2-level system would depolarise fluorescence) perturbed by argon. The studies yielded results that were explainable in terms of the selective population of Stark shifted dressed states by a detuned, weak probe field. Use has been made of the electric-dipole radiation selection rule m_{J}=0 rightarrow m_{J^' } = 0 unless J=J^' to devise a 'Stark shift collision switch'. The competition between collision and radiation induced transitions within the mercury atom has then been studied. The resonant, strong lambda 435.8 nm field was used

  17. Radiation protection for an ultra-high intensity laser.

    PubMed

    Borne, F; Delacroix, D; Gelé, J M; Massé, D; Amiranoff, F

    2002-01-01

    Radiological characterisation of an experimental chamber and other areas of an ultra-high intensity laser facility (-terawatt) revealed significant levels of X ray, gamma and neutron radiation. Different techniques were used to detect and measure this radiation: TLD. photographic film, bubble detectors and germanium spectrometry. A test series of radiological measurements was made for 150 laser shots (300 femtoseconds) with energies in the 1 to 20 J range and a target illuminance of 10(19) W.cm2. Gamma dose equivalents in the vicinity of the chamber varied between 0.7 and 73 mSv. The dose equivalent due to the neutron component was evaluated to be 1% of the gamma dose equivalent. The amount of radiation generated depends on the laser energy and the nature of the target. No activation or contamination of the chamber or target holder were observed. Ultra-high intensity lasers are being extensively developed at the present time and the investigations performed demonstrate that it is necessary to take radiological risks into consideration in the design of ultra-high intensity laser facilities and to define personnel access conditions. PMID:12212903

  18. Evaluation of pGL1-TNF-alpha therapy in combination with radiation

    NASA Technical Reports Server (NTRS)

    Li, J.; Andres, M. L.; Fodor, I.; Nelson, G. A.; Gridley, D. S.

    1998-01-01

    Long-term control of high-grade brain tumors is rarely achieved with current therapeutic regimens. In this study a new plasmid-based human tumor necrosis factor-alpha (TNF-alpha) expression vector was synthesized (pGL1-TNF-alpha) and evaluated together with radiation in the aggressive, rapidly growing C6 rat glioma model. pGL1-TNF-alpha was successfully transfected into C6 cells in vitro using a cationic polyamine method. Expression was detected up to 7 days and averaged 0.4 ng of TNF-alpha in the culture medium from 1x10(5) cells. The expressed protein was biologically functional, as evidenced by growth inhibition of L929, a TNF-alpha-susceptible cell line. Using fluorescence-labeled monoclonal antibodies and laser scanning cytometry, we confirmed that both the P55 and P75 receptors for TNF-alpha were present on the C6 cell membrane. However, the receptors were present at low density and P55 was expressed more than the P75 receptor. These findings were in contrast to results obtained with TNF-alpha-susceptible L929 cells. Tests in athymic mice showed that pGL1-TNF-alpha administered intratumorally 16-18 h before radiation (each modality given three times) significantly inhibited C6 tumor progression (P<0.05). This effect was more than additive, because pGL1-TNF-alpha alone did not slow tumor growth and radiation alone had little effect on tumor growth. These results indicate that pGL1-TNF-alpha has potential to augment the antitumor effects of radiation against a tumor type that is virtually incurable.

  19. Development of an alpha/beta/gamma detector for radiation monitoring

    SciTech Connect

    Yamamoto, Seiichi; Hatazawa, Jun

    2011-11-15

    For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

  20. Monte Carlo treatment of Lyman-alpha radiation in a plane-parallel atmosphere.

    NASA Technical Reports Server (NTRS)

    Modali, S. B.; Brandt, J. C.; Kastner, S. O.

    1972-01-01

    A Monte Carlo technique involving Stokes vectors is used to obtain the state of polarization and intensity of solar Lyman-alpha photons as they diffuse through a plane-parallel homogeneous model of earth's hydrogen envelope. Fine structure of Lyman-alpha and Doppler redistribution of frequencies are taken into account. Comparison of the results with Heath's observed upper limit for polarization of 1.5 per cent implies an optical thickness tau greater than 7 and intensities of 8-10 kilorayleighs for a solar Lyman-alpha flux of 5.8 ergs per sq cm per sec.

  1. Ly{alpha} DOMINANCE OF THE CLASSICAL T TAURI FAR-ULTRAVIOLET RADIATION FIELD

    SciTech Connect

    Schindhelm, Eric; France, Kevin; Brown, Alexander; Herczeg, Gregory J.; Bergin, Edwin; Yang Hao; Brown, Joanna M.; Linsky, Jeffrey L.; Valenti, Jeff

    2012-09-01

    Far-ultraviolet (FUV) radiation plays an important role in determining chemical abundances in protoplanetary disks. H I Lyman {alpha} (Ly{alpha}) is suspected to be the dominant component of the FUV emission from Classical T Tauri Stars (CTTSs), but is difficult to measure directly due to circumstellar and interstellar H I absorption. To better characterize the intrinsic Ly{alpha} radiation, we present FUV spectra of 14 CTTSs taken with the Hubble Space Telescope Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph instruments. H{sub 2} fluorescence, commonly seen in the spectra of CTTSs, is excited by Ly{alpha} photons, providing an indirect measure of the Ly{alpha} flux incident upon the warm disk surface. We use observed H{sub 2} progression fluxes to reconstruct the CTTS Ly{alpha} profiles. The Ly{alpha} flux correlates with total measured FUV flux, in agreement with an accretion-related source of FUV emission. With a geometry-independent analysis, we confirm that in accreting T Tauri systems Ly{alpha} radiation dominates the FUV flux ({approx}1150 A -1700 A). In the systems surveyed this one line comprises 70%-90% of the total FUV flux.

  2. Approaching oxygen-guided intensity-modulated radiation therapy

    PubMed Central

    Epel, Boris; Redler, Gage; Pelizzari, Charles; Tormyshev, Victor M.; Halpern, Howard J.

    2016-01-01

    The outcome of cancer radiation treatment is strongly correlated with tumor oxygenation. The aim of this study is to use oxygen tension distributions in tumors obtained using Electron Paramagnetic Resonance (EPR) imaging to devise better tumor radiation treatment. The proposed radiation plan is delivered in two steps. In the first step, a uniform 50% tumor control dose (TCD50) is delivered to the whole tumor. For the second step an additional dose boost is delivered to radioresistant, hypoxic tumor regions. FSa fibrosarcomas grown in the gastrocnemius of the legs of C3H mice were used. Oxygen tension images were obtained using a 250 MHz pulse imager and injectable partially deuterated trityl OX63 (OX71) spin probe. Radiation was delivered with a novel animal intensity modulated radiation therapy (IMRT) XRAD225Cx microCT/radiation therapy delivery system. In a simplified scheme for boost dose delivery, the boost area is approximated by a sphere, whose radius and position are determined using an EPR O2 image. The sphere that irradiates the largest fraction of hypoxic voxels in the tumor was chosen using an algorithm based on Receiver Operator Characteristic (ROC) analysis. We used the fraction of irradiated hypoxic volume as the true positive determinant and the fraction of irradiated normoxic volume as the false positive determinant in the terms of that analysis. The most efficient treatment is the one that demonstrates the shortest distance from the ROC curve to the upper left corner of the ROC plot. The boost dose corresponds to the difference between TCD90 and TCD50 values. For the control experiment an identical radiation dose to the normoxic tumor area is delivered. PMID:26782211

  3. Correlations between solar wind parameters and auroral kilometric radiation intensity

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Dangelo, N.

    1981-01-01

    The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

  4. Radiation control in the intensive care unit for high intensity iridium-192 brain implants

    SciTech Connect

    Sewchand, W.; Drzymala, R.E.; Amin, P.P.; Salcman, M.; Salazar, O.M.

    1987-04-01

    A bedside lead cubicle was designed to minimize the radiation exposure of intensive care unit staff during routine interstitial brain irradiation by removable, high intensity iridium-192. The cubicle shields the patient without restricting intensive care routines. The design specifications were confirmed by exposure measurements around the shield with an implanted anthropomorphic phantom simulating the patient situation. The cubicle reduces the exposure rate around an implant patient by as much as 90%, with the exposure level not exceeding 0.1 mR/hour/mg of radium-equivalent /sup 192/Ir. Evaluation of data accumulated for the past 3 years has shown that the exposure levels of individual attending nurses are 0.12 to 0.36 mR/mg of radium-equivalent /sup 192/Ir per 12-hour shift. The corresponding range for entire nursing teams varies between 0.18 and 0.26. A radiation control index (exposure per mg of radium-equivalent /sup 192/Ir per nurse-hour) is thus defined for individual nurses and nursing teams; this index is a significant guide to the planning of nurse rotations for brain implant patients with various /sup 192/Ir loads. The bedside shield reduces exposure from /sup 192/Ir implants by a factor of about 20, as expected, and the exposure from the lower energy radioisotope iodine-125 is barely detectable.

  5. A Novel Microsensor for Measuring Angular Distribution of Radiative Intensity.

    PubMed

    Murphy, Thomas E; Pilorz, Stuart; Prufert-Bebout, Leslie; Bebout, Brad

    2015-01-01

    This article presents the design, construction and characterization of a novel type of light probe for measuring the angular radiance distribution of light fields. The differential acceptance angle (DAA) probe can resolve the directionality of a light field in environments with steep light gradients, such as microbial mats, without the need to remove, reorient, and reinsert the probe, a clear advantage over prior techniques. The probe consists of an inner irradiance sensor inside a concentric, moveable light-absorbing sheath. The radiative intensity in a specific zenith direction can be calculated by comparing the irradiance onto the sensor at different acceptance angles. We used this probe to measure the angular radiance distribution of two sample light fields, and observed good agreement with a conventional radiance probe. The DAA probe will aid researchers in understanding light transfer physics in dense microbial communities and expedite validation of numerical radiative transfer models for these environments. PMID:25763775

  6. RADIATIVE TRANSFER MODELING OF Ly{alpha} EMITTERS. II. NEW EFFECTS ON GALAXY CLUSTERING

    SciTech Connect

    Zheng Zheng; Cen Renyue; Trac, Hy; Miralda-Escude, Jordi

    2011-01-01

    We study the clustering properties of z {approx} 5.7 Ly{alpha} emitters (LAEs) in a cosmological reionization simulation with a full Ly{alpha} radiative transfer calculation. Ly{alpha} radiative transfer substantially modifies the intrinsic Ly{alpha} emission properties, compared to observed ones, depending on the density and velocity structure environment around the Ly{alpha}-emitting galaxy. This environment-dependent Ly{alpha} selection introduces new features in LAE clustering, suppressing (enhancing) the line-of-sight (transverse) density fluctuations and giving rise to scale-dependent galaxy bias. In real space, the contours of the three-dimensional two-point correlation function of LAEs appear to be prominently elongated along the line of sight on large scales, an effect that is opposite to and much stronger than the linear redshift-space distortion effect. The projected two-point correlation function is greatly enhanced in amplitude by a factor of up to a few, compared to the case without the environment-dependent selection effect. The new features in LAE clustering can be understood with a simple, physically motivated model, where Ly{alpha} selection depends on matter density, velocity, and their gradients. We discuss the implications and consequences of the effects on galaxy clustering from Ly{alpha} selection in interpreting clustering measurements and in constraining cosmology and reionization from LAEs.

  7. Direct Radiative Effect of Intense Dust Outbreaks in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Obiso, V.; Basart, S.; Jorba, O.; Pérez García-Pando, C.; Hatzianastassiou, N.; Gassó, S.; Baldasano, J. M.

    2015-12-01

    The broader Mediterranean basin is affected by intense desert dust outbreaks in spring. In the present study, we make use of satellite observations and modelling to investigate dust radiative impacts during three consecutive dust outbreaks occurred over the Mediterranean in the period 9/4-15/4/2008. The direct radiative effect (DRE) is estimated by using two simulations run with the NMMB/BSC-Dust model, where the interaction between dust aerosols and radiation is activated and deactivated, respectively. The simulation domain covers the North Africa, the Middle East and Europe at 0.25ºx0.25° and 40σ-layers. The first outbreak took place over the central and eastern Mediterranean on the 9th reaching aerosol optical depths (AODs) close to 1. The second one, with AODs up to 2, lasted from 10th to 14th affecting mainly the central Mediterranean. The third one, with AODs up to 5, affected the Iberian Peninsula on the 15th. DREs are computed for the outgoing radiation at the top of the atmosphere (TOA), the absorbed radiation into the atmosphere (ATMAB), for the downwelling (SURF) and the absorbed (NETSURF) radiation at surface, for the shortwave (SW), longwave (LW) and NET (SW+LW) radiation. According to our results, it is evident that DREs' spatial patterns are driven by those of AOD. Negative (cooling) instantaneous DRETOA, DRESURF and DRENETSURF values up to -500W/m2, -700W/m2 and -600W/m2, respectively, and positive (warming) instantaneous DREATMAB up to 340W/m2 are found for the SW spectrum, during daytime. Opposite but less pronounced effects are encountered for the LW radiation and during nightime. Due to these perturbations on the radiation field, the surface temperature is reduced locally by up to 8°C during daytime and increased by up to 4°C during nightime. It is found that the regional average NET DREs can be as large as -12W/m2, -45W/m2, -30W/m2 and 27W/m2 for TOA, SURF, NETSURF and ATMAB, respectively. Impacts on atmospheric stability and dust

  8. Salivary nitric oxide and alpha-amylase as indexes of training intensity and load.

    PubMed

    Diaz, M M; Bocanegra, O L; Teixeira, R R; Soares, S S; Espindola, F S

    2013-01-01

    This study examined the variation in salivary nitric oxide (NO), alpha-amylase (sAA) and serum markers of muscle injury during 21 weeks of training in elite swimmers. Samples of saliva and blood were collected once a month during 5 months from 11 male professional athletes during their regular training season. The variation in each marker throughout the 21 weeks was compared with the dynamics of training volume, intensity and load. Unstimulated whole saliva was assessed for NO and sAA whereas venous blood was assessed for lactate dehydrogenase, creatine kinase, and γ-glutamyltransferase. Nitric oxide and sAA showed a proportional response to the intensity of training. However, whereas the concentration of NO increased across the 21 weeks, the activity of sAA decreased. Similar variations in the concentration of NO and the markers of muscle injury were also observed. The higher concentration of NO might be attributed to changes in haemodynamics and muscle regenerative processes. On the other hand, autonomic regulation towards parasympathetic predominance might have been responsible for the decrease in sAA activity. These findings provide appealing evidence for the utilization of salivary constituents in sports medicine to monitor training programmes. PMID:22960992

  9. The radiation techniques of tomotherapy & intensity-modulated radiation therapy applied to lung cancer

    PubMed Central

    Zhu, Zhengfei

    2015-01-01

    Radiotherapy (RT) plays an important role in the management of lung cancer. Development of radiation techniques is a possible way to improve the effect of RT by reducing toxicities through better sparing the surrounding normal tissues. This article will review the application of two forms of intensity-modulated radiation therapy (IMRT), fixed-field IMRT and helical tomotherapy (HT) in lung cancer, including dosimetric and clinical studies. The advantages and potential disadvantages of these two techniques are also discussed. PMID:26207214

  10. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  11. IMRT (intensity modulated radiation therapy): progress in technology and reimbursement.

    PubMed

    Young, R; Snyder, B

    2001-01-01

    For a new treatment technology to become widely accepted in today's healthcare environment, the technology must not only be effective but also financially viable. Intensity modulated radiation therapy (IMRT), a technology that enables radiation oncologists to precisely target and attack cancerous tumors with higher doses of radiation using strategically positioned beams while minimizing collateral damage to healthy cells, now meets both criteria. With IMRT, radiation oncologists for the first time have obtained the ability to divide the treatment field covered by each beam angle into hundreds of segments as small as 2.5 mm by 5 mm. Using the adjustable leaves of an MLC to shape the beam and by controlling exposure times, physicians can deliver a different dose to each segment and therefore modulate dose intensity across the entire treatment field. Development of optimal IMRT plans using conventional manual treatment planning methods would take days. To be clinically practical, IMRT required the development of "inverse treatment planning" software. With this software, a radiation oncologist can prescribe the ideal radiation dose for a specific tumor as well as maximum dose limits for surrounding healthy tissue. These numbers are entered into the treatment planning program which then calculates the optimal delivery approach that will best fit the oncologist's requirements. The radiation oncologist then reviews and approves the proposed treatment plan before it is initiated. The most recent advance in IMRT technology offers a "dynamic" mode or "sliding window" technique. In this more rapid delivery method, the beam remains on while the leaves of the collimator continually re-shape and move the beam aperture over the planned treatment area. This creates a moving beam that saturates the tumor volume with the desired radiation dose while leaving the surrounding healthy tissue in a protective shadow created by the leaves of the collimator. In the dynamic mode, an IMRT

  12. Prone Breast Intensity Modulated Radiation Therapy: 5-Year Results

    SciTech Connect

    Osa, Etin-Osa O.; DeWyngaert, Keith; Roses, Daniel; Speyer, James; Guth, Amber; Axelrod, Deborah; Fenton Kerimian, Maria; Goldberg, Judith D.; Formenti, Silvia C.

    2014-07-15

    Purpose: To report the 5-year results of a technique of prone breast radiation therapy delivered by a regimen of accelerated intensity modulated radiation therapy with a concurrent boost to the tumor bed. Methods and Materials: Between 2003 and 2006, 404 patients with stage I-II breast cancer were prospectively enrolled into 2 consecutive protocols, institutional trials 03-30 and 05-181, that used the same regimen of 40.5 Gy/15 fractions delivered to the index breast over 3 weeks, with a concomitant daily boost to the tumor bed of 0.5 Gy (total dose 48 Gy). All patients were treated after segmental mastectomy and had negative margins and nodal assessment. Patients were set up prone: only if lung or heart volumes were in the field was a supine setup attempted and chosen if found to better spare these organs. Results: Ninety-two percent of patients were treated prone, 8% supine. Seventy-two percent had stage I, 28% stage II invasive breast cancer. In-field lung volume ranged from 0 to 228.27 cm{sup 3}, mean 19.65 cm{sup 3}. In-field heart volume for left breast cancer patients ranged from 0 to 21.24 cm{sup 3}, mean 1.59 cm{sup 3}. There was no heart in the field for right breast cancer patients. At a median follow-up of 5 years, the 5-year cumulative incidence of isolated ipsilateral breast tumor recurrence was 0.82% (95% confidence interval [CI] 0.65%-1.04%). The 5-year cumulative incidence of regional recurrence was 0.53% (95% CI 0.41%-0.69%), and the 5-year overall cumulative death rate was 1.28% (95% CI 0.48%-3.38%). Eighty-two percent (95% CI 77%-85%) of patients judged their final cosmetic result as excellent/good. Conclusions: Prone accelerated intensity modulated radiation therapy with a concomitant boost results in excellent local control and optimal sparing of heart and lung, with good cosmesis. Radiation Therapy Oncology Group protocol 1005, a phase 3, multi-institutional, randomized trial is ongoing and is evaluating the equivalence of a similar dose and

  13. Development and characterization of an in vitro alpha radiation exposure system

    NASA Astrophysics Data System (ADS)

    Beaton, Lindsay A.; Burn, Trevor A.; Stocki, Trevor J.; Chauhan, Vinita; Wilkins, Ruth C.

    2011-06-01

    A simple in vitro alpha radiation exposure system (ARES) was designed to study the biological effects of alpha particle radiation. The ARES consists of six 241Am electroplated stainless steel discs with activities averaging 66 kBq and Mylar-based culture dishes to allow the transmission of alpha particles. The dosimetry of the exposure system was calculated using the GEANT4 Monte Carlo simulation toolkit with the source code adapted from the open-source Microbeam example. The average dose rate and linear energy transfer of the system was simulated to be 0.98 ± 0.01 (statistical)+0.18 - 0.00 (systematic) Gy h-1 and 127.4 ± 0.4 (statistical)+23 - 0 (systematic) keV µm-1, respectively. The system was characterized by a comparison of the survival curves of gamma and alpha irradiated cell lines which showed a relative biological effectiveness of 6.3. This is in good agreement with values obtained using other published alpha particle exposure systems. Results show that the ARES provides a simple, cost-effective exposure platform for research into the biological effects of alpha particle radiation using in vitro modelling of cell cultures.

  14. Development and characterization of an in vitro alpha radiation exposure system.

    PubMed

    Beaton, Lindsay A; Burn, Trevor A; Stocki, Trevor J; Chauhan, Vinita; Wilkins, Ruth C

    2011-06-21

    A simple in vitro alpha radiation exposure system (ARES) was designed to study the biological effects of alpha particle radiation. The ARES consists of six (241)Am electroplated stainless steel discs with activities averaging 66 kBq and Mylar-based culture dishes to allow the transmission of alpha particles. The dosimetry of the exposure system was calculated using the GEANT4 Monte Carlo simulation toolkit with the source code adapted from the open-source Microbeam example. The average dose rate and linear energy transfer of the system was simulated to be 0.98 ± 0.01 (statistical)(+0.18)( - 0.00) (systematic) Gy h(-1) and 127.4 ± 0.4 (statistical)(+23)( - 0) (systematic) keV µm(-1), respectively. The system was characterized by a comparison of the survival curves of gamma and alpha irradiated cell lines which showed a relative biological effectiveness of 6.3. This is in good agreement with values obtained using other published alpha particle exposure systems. Results show that the ARES provides a simple, cost-effective exposure platform for research into the biological effects of alpha particle radiation using in vitro modelling of cell cultures. PMID:21610295

  15. CHEMISTRY OF A PROTOPLANETARY DISK WITH GRAIN SETTLING AND Ly{alpha} RADIATION

    SciTech Connect

    Fogel, Jeffrey K. J.; Bethell, Thomas J.; Bergin, Edwin A.; Calvet, Nuria; Semenov, Dmitry E-mail: tbethell@umich.edu E-mail: ncalvet@umich.edu

    2011-01-01

    We present results from a model of the chemical evolution of protoplanetary disks. In our models, we directly calculate the changing propagation and penetration of a high energy radiation field with Ly{alpha} radiation included. We also explore the effect on our models of including dust grain settling. We find that, in agreement with earlier studies, the evolution of dust grains plays a large role in determining how deep the UV radiation penetrates into the disk. Significant grain settling at the midplane leads to much smaller freeze-out regions and a correspondingly larger molecular layer, which leads to an increase in column density for molecular species such as CO, CN, and SO. The inclusion of Ly{alpha} radiation impacts the disk chemistry through specific species that have large photodissociation cross sections at 1216 A. These include HCN, NH{sub 3}, and CH{sub 4}, for which the column densities are decreased by an order of magnitude or more due to the presence of Ly{alpha} radiation in the UV spectrum. A few species, such as CO{sub 2} and SO, are enhanced by the presence of Ly{alpha} radiation, but rarely by more than a factor of a few.

  16. ZrCo as a new H2 storage and getter for Lyman alpha radiation sources

    NASA Astrophysics Data System (ADS)

    Woyke, Thomas; Schiller, Cornelius; Schmidt, Ulrich; Schober, Tilman; Zöger, Martin

    1995-01-01

    In the past, in sealed-off Lyman- alpha radiation sources (121.57 nm), uranium hydride was used as the hydrogen reservoir. We found that the zirconium-cobalt alloy ZrCo, which has similar thermodynamic properties, can also be used for hydrogen storage in such lamps. Like uranium, ZrCo acts as a getter for atmospheric contaminants. The advantage of the use of ZrCo lies in much easier and safer handling during production and disposal of the lamps. Using ZrCo, we succeeded in producing radiation sources with a large Lyman- alpha radiation output and high spectral purity, which were successfully applied in a Lyman- alpha fluorescence hygrometer for stratospheric observations.

  17. Preoperative intensity modulated radiation therapy for retroperitoneal sarcoma.

    PubMed

    El-Bared, Nancy; Taussky, Daniel; Mehiri, Selma; Patocskai, Erika; Roberge, David; Donath, David

    2014-06-01

    The use of intensity modulated radiation therapy (IMRT) has allowed for the administration of high doses to retroperitoneal sarcomas (RSTS) while limiting toxicity to adjacent organs. The purpose of our study is to assess the outcome and toxicities of patients with RSTS treated with neo-adjuvant external beam radiation (EBRT) therapy using IMRT. This is a retrospective study of 21 patients treated with preoperative IMRT for primary or recurrent RSTS between 2005 and 2011. Overall survival (OS) and local recurrence free survival (LRFS) were computed using the Kaplan-Meier method (log-rank test). Acute and chronic toxicities were assessed using the CTCAE v. 3 criteria. The actuarial 2 and 3-year OS was 66% for both and the 5-year OS was 51%. As for LRFS it was 57% at 2 and 3-year and 51% for the 5-year LRFS. Factors predictive for local control were microscopically negative margins (p = 0.022), a median tumor diameter <15 cm (p = 0.007) and pathology of liposarcoma (p = 0.021). Furthermore, patients treated for recurrent disease fared worse (p = 0.04) in local control than patients treated for primary disease. As for OS, patients treated for Grade 1 histology had a better outcome (p 5 0.05). EBRT was generally well tolerated. Acute gastrointestinal (GI) Grade 1 or 2 toxicities occurred in 33% of patients and one patient had unexplained post-radiation Grade 2 fever that resolved after tumor resection. As for chronic toxicities 24% of our patients presented Grade 1 GI toxicity and one patient presented Grade 3 small bowel stenosis not clearly due to radiation toxicity. Despite the location and volume of the tumors treated, preoperative IMRT was very well tolerated in our patients with retroperitoneal sarcoma. Unfortunately local recurrences remain common and dose escalation is to be considered. PMID:23919397

  18. Preoperative Intensity Modulated Radiation Therapy for Retroperitoneal Sarcoma

    PubMed Central

    El-Bared, Nancy; Taussky, Daniel; Mehiri, Selma; Patocskai, Erika; Roberge, David; Donath, David

    2014-01-01

    The use of intensity modulated radiation therapy (IMRT) has allowed for the administration of high doses to retroperitoneal sarcomas (RSTS) while limiting toxicity to adjacent organs. The purpose of our study is to assess the outcome and toxicities of patients with RSTS treated with neo-adjuvant external beam radiation (EBRT) therapy using IMRT. This is a retrospective study of 21 patients treated with preoperative IMRT for primary or recurrent RSTS between 2005 and 2011. Overall survival (OS) and local recurrence free survival (LRFS) were computed using the Kaplan-Meier method (log-rank test). Acute and chronic toxicities were assessed using the CTCAE v. 3 criteria. The actuarial 2 and 3-year OS was 66% for both and the 5-year OS was 51%. As for LRFS it was 57% at 2 and 3-year and 51% for the 5-year LRFS. Factors predictive for local control were microscopically negative margins (p = 0.022), a median tumor diameter <5 cm (p = 0.007) and pathology of liposarcoma (p = 0.021). Furthermore, patients treated for recurrent disease fared worse (p = 0.04) in local control than patients treated for primary disease. As for OS, patients treated for Grade 1 histology had a better outcome (p = 0.05). EBRT was generally well tolerated. Acute gastrointestinal (GI) Grade 1 or 2 toxicities occurred in 33% of patients and one patient had unexplained post-radiation Grade 2 fever that resolved after tumor resection. As for chronic toxicities 24% of our patients presented Grade 1 GI toxicity and one patient presented Grade 3 small bowel stenosis not clearly due to radiation toxicity. Despite the location and volume of the tumors treated, preoperative IMRT was very well tolerated in our patients with retroperitoneal sarcoma. Unfortunately local recurrences remain common and dose escalation is to be considered. PMID:23919397

  19. Monte Carlo treatment of Lyman-alpha. II - Radiation in a spherical atmosphere

    NASA Technical Reports Server (NTRS)

    Modali, S. B.; Brandt, J. C.; Kastner, S. O.

    1975-01-01

    Intensity and state of polarization of solar L-alpha photons as they diffuse through an inhomogeneous, spherically symmetric, isothermal geocorona are theoretically determined. The fine structure of L-alpha and Doppler redistribution of frequencies are taken into account. The calculation use the Monte Carlo technique involving Stokes vectors. Comparison of the results with OGO-4 and OSO-4 observed intensities at an altitude of 650 km shows good agreement. Calculations of the polarization versus solar zenith angle show a residual polarization at large zenith angles which is mainly due to multiply scattered photons.

  20. Study of silver K{alpha} and bremsstrahlung radiation from short-pulse laser-matter interactions with applications for x-ray radiography

    SciTech Connect

    Westover, B.; Beg, F. N.; MacPhee, A.; Chen, C.; Hey, D.; Maddox, B.; Park, H.-S.; Remington, B.; Ma, T.

    2010-08-15

    Measurements of K{alpha} radiation yield and x-ray bremsstrahlung emission from thin-foil silver targets are presented. The targets were irradiated by a short pulse laser with intensities from 5x10{sup 16} to 10{sup 18} W/cm{sup 2} at 40 ps. Single hit charge-coupled device detectors, differential filter-stack detectors, and a crystal spectrometer were used to investigate the angular distribution of the K{alpha} and bremsstrahlung x-rays. This study is the first to use a broadband detector to estimate the absolute numbers of K{alpha} photons and to determine K{alpha} to bremsstrahlung ratios. The relevance of this work in the context of x-ray diffraction and x-ray radiography is discussed.

  1. Solar Cycle Variations of O VI and H I Lyman Alpha Intensities in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Miralles, M. P.; Panasyuk, A. V.; Strachan, L.; Gardner, L. D.; Suleiman, R. M.; Smith, P. L.; Kohl, J. L.

    2000-05-01

    UVCS/SOHO measurements of O VI (103.2 and 103.7 nm) and H I Lyman alpha intensities in the solar corona have been made from 1996 to the present spanning the rising phase of cycle 23. During solar minimum the corona consisted of large coronal holes at the poles and quiescent streamers at the equator. During the ascending phase of the cycle, the corona presented high latitude streamers and finally polar streamers as the Sun approached solar maximum. Recent observations of the solar corona show the presence of coronal holes at the equator and streamers at the poles. Our observations provide descriptions of these structures over the rising phase of the solar cycle. We compare the properties of quiescent equatorial streamers which occurred at solar minimum to high latitude and polar streamers observed toward solar maximum. We also compare solar minimum polar coronal holes to equatorial coronal holes present at solar maximum. We discuss how these results are related to the plasma properties. This work is supported by NASA under Grant NAG5-7822 to the Smithsonian Astrophysical Observatory, by the Italian Space Agency and by PRODEX (Swiss contribution).

  2. Interplanetary Lyman-alpha spectral profiles and intensities for both repulsive and attractive solar force fields Predicted absorption pattern by a hydrogen cell

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Bertaux, J. L.; Dalaudier, F.

    1985-09-01

    The velocity of H atoms in the vicinity of the sun can be modified through ionization by solar-wind charge exchange and solar EUV photoionization, and through solar gravity. A computer-code model was developed to study these effects in detail; the model includes line profile computation in the repulsive case when the solar Lyman-alpha radiation pressure exceeds solar gravity. The model also predicts the distributions of the intensity I(phi) and reduction factor R(phi) of the intensity when the H cell is activated to observation planes perpendicular to the sun-earth line as a function of angle phi. This particular geometry applies to the space experiment flown on the Prognoz 5 and 6 spacecraft. The basic findings of the parametric study are presented.

  3. Rock Burst Intensity Classification Based on the Radiated Energy with Damage Intensity at Jinping II Hydropower Station, China

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Rui; Feng, Xia-Ting; Li, Qing-Peng; Luo, Ru-Zhou; Li, Shaojun

    2015-01-01

    Based on the radiated energy of 133 rock bursts monitored by a microseismic technique at the Jinping II hydropower station, in Sichuan province, China, we analyzed the advantages and disadvantages of qualitative classification methods for the rock burst intensity. Then, we investigated the characteristics, magnitude, and laws of the radiated energy, as well as the relationship between the rock burst radiated energy and intensity. Then, we selected the energy as an evaluation index for the rock burst intensity classification, and proposed a new rock burst intensity quantitative classification method, which utilized the hierarchical clustering analysis technique with the complete-linkage method. Next, we created a new set of criteria for the quantitative classification of the rock burst intensity based on radiated energy and surrounding rock damage severity. The new criteria classified the rock burst intensity into five levels: extremely intense, intense, moderate, weak, and none, and the common logarithms of the radiated energy of each level were >7 lg( E/J), >4 lg( E/J) and <7 lg( E/J), >2 lg( E/J) and <4 lg( E/J), >1 lg( E/J) and <2 lg( E/J), and <1 lg( E/J), respectively. Finally, we investigated the factors influencing the classification, and verified its feasibility and applicability via several practical rock burst examples.

  4. S-76 rotorcraft high intensity radiated fields. Test plan

    NASA Astrophysics Data System (ADS)

    Blair, Jerry T.; Brooks, Steve M.; Barnes, Ken A.

    1991-07-01

    Concern over the effects of High Intensity Radiated Fields (HIRF) on civil and military aircraft has increased over the past 10 years. The increase is due to several factors which affect the safe flight of all fixed-wing and rotorcraft. Previous flight-critical mechanical controls are being replaced by electronic computer-driven controls; manufacturers are increasing the use of composite materials in the fabrication of new aircraft; and frequency ranges and output power levels of commercial and military transmitters have significantly increased. While much HIRF susceptibility information has been collected, the data are proprietary and have not been released. To address the HIRF concerns and begin development of a releasable HIRF data base, the FAA Technical Center, has implemented a HIRF research program. As part of that program, a HIRF test was performed on a Sikorsky S-76 Helicopter. The purpose, approach, and initial findings of the S-76 HIRF test are addressed.

  5. Intense terahertz pulses from SPARC_LAB coherent radiation source

    NASA Astrophysics Data System (ADS)

    Giorgianni, F.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Cianchi, A.; Daniele, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Lupi, S.; Mostacci, A.; Petrarca, M.; Pompili, R.; Shpakov, V.; Villa, F.

    2015-05-01

    The linac-based Terahertz source at the SPARC_LAB test facility is able to generate highly intense Terahertz broadband pulses via coherent transition radiation (CTR) from high brightness electron beams. The THz pulse duration is typically down to 100 fs RMS and can be tuned through the electron bunch duration and shaping. The measured stored energy in a single THz pulse has reached 40 μJ, which corresponds to a peak electric field of 1.6 MV/cm at the THz focus. Here we present the main features, in particular spatial and spectral distributions and energy characterizations of the SPARC_LAB THz source, which is very competitive for investigations in Condensed Matter, as well as a valid tool for electron beam longitudinal diagnostics.

  6. The solar O III spectrum. II - Longer wavelengths, line widths, and the He II Lyman alpha radiation field

    NASA Technical Reports Server (NTRS)

    Kastner, S. O.; Behring, W. E.; Bhatia, A. K.

    1983-01-01

    The solar O III spectrum above 900 A is analyzed, including several visible and infrared lines which are important in nebular studies. The dependence of the line intensities on the rate of photoexcitation by He Ly-alpha is determined, and the observability of these lines in the solar spectrum is studied. The impact approximation is employed to calculate the expected line widths of the stronger solar O III lines. The photoexciting field at 304 A calculated from the observed intensities of the O III lines below 900 A (Bhatia et al., 1982) is compared with the field predicted by a recent model (Avrett et al., 1976). It is shown that additional radiation trapping must be present beyond that given by this model.

  7. Whistler mode wave intensities in the radiation belts

    SciTech Connect

    Helliwell, R.A.; Walworth, K.F.

    1996-07-01

    A critical factor in the equilibrium of the Earth{close_quote}s radiation belts is the intensity of the whistler mode waves that scatter trapped electrons into the loss cone. Whistler-mode waves include whistlers (from lightning), signals from ground based VLF stations, chorus, hiss and impulses. Those signals that are not trapped in magnetospheric ducts are observed with rockets or satellites, both inside and outside the plasmapause. Ducted signals, occurring mostly inside the plasmapause, have been difficult to observe {ital in} {ital situ}, but are commonly observed at ground stations from which equatorial wave intensities can be estimated only crudely. Models of the process of coherent wave growth based on interaction with gyro resonant counter streaming electrons in an interaction region near the equator, fall into two classes depending on whether the wave field is less or greater than that required for trapping of resonant electrons in the wave{close_quote}s potential wall. Data on the estimated {ital B}{sub in} and {ital B}{sub out} of ducted signals at the input and output of the interaction region, respectively, together with associated total growth (20{endash}35 dB) appear to support the small-signal model. Since the ratios between predictions of the small-signal and large-signal models are of the order of 20 dB, it is critically important to test both models with measurements of appropriate wave fields and associated particle fluxes. {copyright} {ital 1996 American Institute of Physics.}

  8. Reshapable physical modulator for intensity modulated radiation therapy.

    PubMed

    Xu, Tong; Shikhaliev, Polad M; Al-Ghazi, Muthana; Molloi, Sabee

    2002-10-01

    A new method of generating beam intensity modulation filters for intensity modulated radiation therapy (IMRT) is presented. The modulator was based on a reshapable material, which is not compressible but can be deformed under pressure. A two-dimensional (2D) piston array was used to repeatedly shape the attenuating material. The material is a mixture of tungsten powder and a silicon-based binder. The linear attenuation coefficient of the material was measured to be 0.409 cm(-1) for a 6 MV x-ray beam. The maximum thickness of the physical modulator is 10.2 cm, allowing a transmission of 1.5%. A 16 x 16 square piston array was used to generate a depth pattern in the deformable attenuating material. Each piston has a cross section of 6.37 x 6.37 mm2. The modulator was placed 65 cm from the radiation source of the linear accelerator in the position of the shielding tray. At this position, each piston projects to a 1.0 x 1.0 cm2 area at the isocenter, giving a treatment field of 16 x 16 cm2. The percent depth dose curve and output factor measurement show a slight beam hardening and a 1%-4% increase in scatter fraction when 2.2-4.4 cm uniform thickness filters are in the beam. The surface dose was decreased with the filter in the beam. Ion chamber and verification films were used to verify the entrance dose. The measured absolute and relative doses were compared with the calculated dose. The agreement of measurements and calculations is within 3%. In order to verify the spatial modulation of dose, 1-D dose profiles were obtained using dose calculations. Calculated and measured profiles were compared. The 20%-80% penumbra of the modulator was measured to be 5.5-10 mm. The results show that a physical modulator formed using a 16 x 16 piston array and a deformable attenuation material can provide intensity modulation for IMRT comparable with those provided by currently available commercial MLC techniques. PMID:12408295

  9. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles

    SciTech Connect

    Zaider, M.

    1992-01-01

    We report on a theory for describing the biological effects of ionizing radiation in particular radon [alpha] particles. Behind this approach is the recognition that biological effects such as chromosome aberrations, cellular transformation, cellular inactivation, etc, are the result of a hierarchic sequence of radiation effects. We indicate how to treat each of the individual processes in this sequence, and also how to relate one effect to the hierarchically superior one.

  10. Survey of resident education in intensity-modulated radiation therapy.

    PubMed

    Malik, Renuka; Oh, Julia L; Roeske, John C; Mundt, Arno J

    2005-06-01

    Intensity-modulated radiation therapy (IMRT) has been gaining increasing popularity among practicing physicians in the U.S., but the extent to which radiation oncology residents are taught the principles of this technology and are trained to use IMRT remains unknown. In this paper, we assessed the current level of resident education in IMRT in the United States. Chief residents at all 77 accredited radiation oncology programs were sent a 13-question survey addressing formal didactics and hands-on experience in IMRT. The survey assessed the frequency, subject, and format of IMRT didactics. Questions also addressed the number of IMRT patients and anatomical sites treated, resident involvement in the IMRT process, and the intent of IMRT use. Finally, residents were asked for their opinions on their IMRT education. Sixty-one surveys (79%) were completed. Overall, forty-three respondents (71%) reported receiving formal IMRT didactics, with nearly one-third reporting extensive didactics (> or = 3 lectures/seminars et cetera per year). The most common didactic formats were lectures (95%) and journal clubs (63%), most commonly supervised by physicists (98%). Involvement by physicians and radiobiologists were reported by 63% and 7% of respondents, respectively. Overall, 87% of respondents had hands-on IMRT training, with nearly one-half having treated > 25 patients. The most common sites treated were head and neck (94%) and prostate (81%). Involvement in all aspects of the IMRT process was common, particularly target and tissue delineation (98%) and plan evaluation (93%). Most respondents (79%) with hands-on experience reported receiving formal didactics. However, nearly one-third received no or only minimal formal didactics. The percentage of respondents desiring increased IMRT didactics and hands-on experience were 70% and 47%, respectively. Our results suggest that the great majority of radiation oncology residents in the United States are currently exposed to didactics

  11. American Society of Radiation Oncology recommendations for documenting intensity-modulated radiation therapy treatments.

    PubMed

    Holmes, Timothy; Das, Rupak; Low, Daniel; Yin, Fang-Fang; Balter, James; Palta, Jatinder; Eifel, Patricia

    2009-08-01

    Despite the widespread use of intensity-modulated radiation therapy (IMRT) for approximately a decade, a lack of adequate guidelines for documenting these treatments persists. Proper IMRT treatment documentation is necessary for accurate reconstruction of prior treatments when a patient presents with a marginal recurrence. This is especially crucial when the follow-up care is managed at a second treatment facility not involved in the initial IMRT treatment. To address this issue, an American Society for Radiation Oncology (ASTRO) workgroup within the American ASTRO Radiation Physics Committee was formed at the request of the ASTRO Research Council to develop a set of recommendations for documenting IMRT treatments. This document provides a set of comprehensive recommendations for documenting IMRT treatments, as well as image-guidance procedures, with example forms provided. PMID:19616738

  12. American Society of Radiation Oncology Recommendations for Documenting Intensity-Modulated Radiation Therapy Treatments

    SciTech Connect

    Holmes, Timothy Das, Rupak; Low, Daniel; Yin Fangfang; Balter, James; Palta, Jatinder; Eifel, Patricia

    2009-08-01

    Despite the widespread use of intensity-modulated radiation therapy (IMRT) for approximately a decade, a lack of adequate guidelines for documenting these treatments persists. Proper IMRT treatment documentation is necessary for accurate reconstruction of prior treatments when a patient presents with a marginal recurrence. This is especially crucial when the follow-up care is managed at a second treatment facility not involved in the initial IMRT treatment. To address this issue, an American Society for Radiation Oncology (ASTRO) workgroup within the American ASTRO Radiation Physics Committee was formed at the request of the ASTRO Research Council to develop a set of recommendations for documenting IMRT treatments. This document provides a set of comprehensive recommendations for documenting IMRT treatments, as well as image-guidance procedures, with example forms provided.

  13. Precise Determination of the Intensity of 226Ra Alpha Decay to the 186 keV Excited State

    SciTech Connect

    S.P. LaMont; R.J. Gehrke; S.E. Glover; R.H. Filby

    2001-04-01

    There is a significant discrepancy in the reported values for the emission probability of the 186 keV gamma-ray resulting from the alpha decay of 226 Ra to 186 keV excited state of 222 Rn. Published values fall in the range of 3.28 to 3.59 gamma-rays per 100 alpha-decays. An interesting observation is that the lower value, 3.28, is based on measuring the 186 keV gamma-ray intensity relative to the 226 Ra alpha-branch to the 186 keV level. The higher values, which are close to 3.59, are based on measuring the gamma-ray intensity from mass standards of 226 Ra that are traceable to the mass standards prepared by HÓNIGSCHMID in the early 1930''s. This discrepancy was resolved in this work by carefully measuring the 226 Ra alpha-branch intensities, then applying the theoretical E2 multipolarity internal conversion coefficient of 0.692±0.007 to calculate the 186 keV gamma-ray emission probability. The measured value for the alpha branch to the 186 keV excited state was (6.16±0.03)%, which gives a 186 keV gamma-ray emission probability of (3.64±0.04)%. This value is in excellent agreement with the most recently reported 186 keV gamma-ray emission probabilities determined using 226 Ra mass standards.

  14. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    SciTech Connect

    Lim, Karen; Stewart, James; Kelly, Valerie; Xie, Jason; Brock, Kristy K.; Moseley, Joanne; Cho, Young-Bin; Fyles, Anthony; Lundin, Anna; Rehbinder, Henrik; Löf, Johan; Jaffray, David A.; Milosevic, Michael

    2014-09-01

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost.

  15. Ultrasound-based guidance of intensity-modulated radiation therapy

    SciTech Connect

    Fung, Albert Y.C. . E-mail: afung@unmc.edu; Ayyangar, Komanduri M.; Djajaputra, David; Nehru, Ramasamy M.; Enke, Charles A.

    2006-04-01

    In ultrasound-guided intensity-modulated radiation therapy (IMRT) of prostate cancer, ultrasound imaging ascertains the anatomical position of patients during x-ray therapy delivery. The ultrasound transducers are made of piezoelectric ceramics. The same crystal is used for both ultrasound production and reception. Three-dimensional (3D) ultrasound devices capture and correlate series of 2-dimensional (2D) B-mode images. The transducers are often arranged in a convex array for focusing. Lower frequency reaches greater depth, but results in low resolution. For clear image, some gel is usually applied between the probe and the skin contact surface. For prostate positioning, axial and sagittal scans are performed, and the volume contours from computed tomography (CT) planning are superimposed on the ultrasound images obtained before radiation delivery at the linear accelerator. The planning volumes are then overlaid on the ultrasound images and adjusted until they match. The computer automatically deduces the offset necessary to move the patient so that the treatment area is in the correct location. The couch is translated as needed. The currently available commercial equipment can attain a positional accuracy of 1-2 mm. Commercial manufacturer designs differ in the detection of probe coordinates relative to the isocenter. Some use a position-sensing robotic arm, while others have infrared light-emitting diodes or pattern-recognition software with charge-couple-device cameras. Commissioning includes testing of image quality and positional accuracy. Ultrasound is mainly used in prostate positioning. Data for 7825 daily fractions of 234 prostate patients indicated average 3D inter-fractional displacement of about 7.8 mm. There was no perceivable trend of shift over time. Scatter plots showed slight prevalence toward superior-posterior directions. Uncertainties of ultrasound guidance included tissue inhomogeneities, speckle noise, probe pressure, and inter

  16. Mapping of laser diode radiation intensity by atomic-force microscopy

    NASA Astrophysics Data System (ADS)

    Alekseev, P. A.; Dunaevskii, M. S.; Slipchenko, S. O.; Podoskin, A. A.; Tarasov, I. S.

    2015-09-01

    The distribution of the intensity of laser diode radiation has been studied using an original method based on atomic-force microscopy (AFM). It is shown that the laser radiation intensity in both the near field and transition zone of a high-power semiconductor laser under room-temperature conditions can be mapped by AFM at a subwavelength resolution. The obtained patterns of radiation intensity distribution agree with the data of modeling and the results of near-field optical microscopy measurements.

  17. Alpha particle response study of polycrstalline diamond radiation detector

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Topkar, Anita

    2016-05-01

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  18. Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review.

    PubMed Central

    Cruickshank, Moira; Henderson, Lorna; MacLennan, Graeme; Fraser, Cynthia; Campbell, Marion; Blackwood, Bronagh; Gordon, Anthony; Brazzelli, Miriam

    2016-01-01

    BACKGROUND Care of critically ill patients in intensive care units (ICUs) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation (MV). Sedation can alleviate pain and discomfort, provide protection from stressful or harmful events, prevent anxiety and promote sleep. Various sedative agents are available for use in ICUs. In the UK, the most commonly used sedatives are propofol (Diprivan(®), AstraZeneca), benzodiazepines [e.g. midazolam (Hypnovel(®), Roche) and lorazepam (Ativan(®), Pfizer)] and alpha-2 adrenergic receptor agonists [e.g. dexmedetomidine (Dexdor(®), Orion Corporation) and clonidine (Catapres(®), Boehringer Ingelheim)]. Sedative agents vary in onset/duration of effects and in their side effects. The pattern of sedation of alpha-2 agonists is quite different from that of other sedatives in that patients can be aroused readily and their cognitive performance on psychometric tests is usually preserved. Moreover, respiratory depression is less frequent after alpha-2 agonists than after other sedative agents. OBJECTIVES To conduct a systematic review to evaluate the comparative effects of alpha-2 agonists (dexmedetomidine and clonidine) and propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated adults admitted to ICUs. DATA SOURCES We searched major electronic databases (e.g. MEDLINE without revisions, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE and Cochrane Central Register of Controlled Trials) from 1999 to 2014. METHODS Evidence was considered from randomised controlled trials (RCTs) comparing dexmedetomidine with clonidine or dexmedetomidine or clonidine with propofol or benzodiazepines such as midazolam, lorazepam and diazepam (Diazemuls(®), Actavis UK Limited). Primary outcomes included mortality, duration of MV, length of ICU stay and adverse events. One reviewer extracted data and assessed the risk of bias of included trials. A second reviewer cross-checked all the

  19. Chemical Environment Effects on K[beta]/K[alpha] Intensity Ratio: An X-Ray Fluorescence Experiment on Periodic Trends

    ERIC Educational Resources Information Center

    Durham, Chaney R.; Chase, Jeffery M.; Nivens, Delana A.; Baird, William H.; Padgett, Clifford W.

    2011-01-01

    X-ray fluorescence (XRF) data from an energy-dispersive XRF instrument were used to investigate the chlorine K[alpha] and K[beta] peaks in several group 1 salts. The ratio of the peak intensity is sensitive to the local chemical environment of the chlorine atoms studied in this experiment and it shows a periodic trend for these salts. (Contains 1…

  20. S-76 high intensity radiated fields, volume 1

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) test on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practicality of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to real world HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should be noted that all the observed disruptions were of a non-critical nature.

  1. S-76 high intensity radiated fields, volume 3

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) tests on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practically of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to 'real world' HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should however be noted that all the observed disruptions were of a non-critical nature.

  2. S-76 high intensity radiated fields, volume 2

    NASA Astrophysics Data System (ADS)

    Blair, Jerry

    1993-10-01

    The Federal Aviation Administration (FAA) Technical Center sponsored a series of High Intensity Radiated Fields (HIRF) test on a Sikorsky S-76 rotorcraft. The project was conducted to evaluate the practically of performing aircraft level HIRF tests, determine the effects of HIRF on a specific rotorcraft with the potential to obtain information on rotorcraft in general, and evaluate the effects of exposure to real world HIRF emitters. HIRF ground and flight tests were conducted to achieve the objective of the project. Site calibration (SCAL) measurements were made in the test area to determine the levels at which the S-76 would be irradiated when placed in the test area. Ground tests consisted of Low Level Swept Coupling (LLSC) and Low Level Swept Fields (LLSF) tests. The flight tests were flown directly into the main beam of a variety of pulsed and continuous wave (CW) transmitters including the Over the Horizon Back Scatter (OTHB), PAVE PAWS, ASR-9, FPS-65, and FPS-16 radars. Results of the S-76 tests added credibility to the existence of HIRF as a flight safety hazard. In the evaluation of the emitters, the flight tests showed repeatable instances where exposure resulted in instrumentation disruptions. It should be noted that all the observed disruptions were of a non-critical nature.

  3. New evaluation of the alpha and gamma emission intensities in the decay of (244)Cm.

    PubMed

    Badikov, Sergey A; Chechev, Valery P

    2016-03-01

    A method for self-consistent evaluation of the absolute emission probabilities for particles and photons accompanying radionuclide decays was applied to the evaluation of the (244)Cm alpha decay data. The absolute emission probabilities evaluated by the method meet the accurate balance relationships. The self-consistency of the results was reached through an iterative scheme of calculations, using the DDEP recommended probabilities for alpha transitions to the five (240)Pu highly excited levels as an initial approximation. PMID:26712410

  4. Low-intensity contraction activates the alpha1-isoform of 5'-AMP-activated protein kinase in rat skeletal muscle.

    PubMed

    Toyoda, Taro; Tanaka, Satsuki; Ebihara, Ken; Masuzaki, Hiroaki; Hosoda, Kiminori; Sato, Kenji; Fushiki, Tohru; Nakao, Kazuwa; Hayashi, Tatsuya

    2006-03-01

    Skeletal muscle expresses two catalytic subunits, alpha1 and alpha2, of the 5'-AMP-activated protein kinase (AMPK), which has been implicated in contraction-stimulated glucose transport and fatty acid oxidation. Muscle contraction activates the alpha2-containing AMPK complex (AMPKalpha2), but this activation may occur with or without activation of the alpha1-containing AMPK complex (AMPKalpha1), suggesting that AMPKalpha2 is the major isoform responsible for contraction-induced metabolic events in skeletal muscle. We report for the first time that AMPKalpha1, but not AMPKalpha2, can be activated in contracting skeletal muscle. Rat epitrochlearis muscles were isolated and incubated in Krebs-Ringer bicarbonate buffer containing pyruvate. In muscles stimulated to contract at a frequency of 1 and 2 Hz during the last 2 min of incubation, AMPKalpha1 activity increased twofold and AMPKalpha2 activity remained unchanged. Muscle stimulation did not change the muscle AMP concentration or the AMP-to-ATP ratio. AMPK activation was associated with increased phosphorylation of Thr(172) of the alpha-subunit, the primary activation site. Muscle stimulation increased the phosphorylation of acetyl-CoA carboxylase (ACC), a downstream target of AMPK, and the rate of 3-O-methyl-d-glucose transport. In contrast, increasing the frequency (>or=5 Hz) or duration (>or=5 min) of contraction activated AMPKalpha1 and AMPKalpha2 and increased AMP concentration and the AMP/ATP ratio. These results suggest that 1) AMPKalpha1 is the predominant isoform activated by AMP-independent phosphorylation in low-intensity contracting muscle, 2) AMPKalpha2 is activated by an AMP-dependent mechanism in high-intensity contracting muscle, and 3) activation of each isoform enhances glucose transport and ACC phosphorylation in skeletal muscle. PMID:16249251

  5. Influence of reactor radiation on {alpha}-Al{sub 2}O{sub 3} in electrically insulating ceramic

    SciTech Connect

    Astapova, E.S.; Kostyukov, N.S.

    1995-11-01

    Under the action of radiation, structural changes occur in ceramic materials; these changes influence its mechanical properties and corrosion resistance. Neutron resistance has the strongest effect, inducing a number of complex processes. Most ceramic materials consist of one or more crystalline phases cemented by glass phases. Neutron radiation produces opposite density changes in the crystalline and glass phase. The conflict between these processes in the ceramic leads to increase in radiation resistance, which is the essence of the compensation effect. Thus, on irradiation, the density of crystalline quartz in the free state decreases by 15%, while the density of quartz glass increase by 3%, with corresponding changes in the volume of the phases. In porcelain, such changes facilitate an increase in strength. The radiational strength of ceramic materials was investigated - in particular, the structural changes in the irradiation of the ceramic by fast neutrons in a flux of no more than 2{center_dot}10{sup 20} cm{sup -2}. The main effects noticed after irradiation of the ceramic by fast distance and decrease in intensity of the diffractional maxima in the crystalline phases of the ceramic, for example, in the {alpha}-Al{sub 2}O{sub 3} phase of the ceramics microlite, GB-7, ultraporcelain, and 22KhS. In the initial state, GB-7 ceramic has a homogeneous, analogous, but the {alpha}-Al{sub 2}O{sub 3} crystals are smaller. According to chemical analysis, the mass fraction of aluminum oxide in GB-7 and 22KhS is 97.09% and 95.14%, respectively.

  6. Remote diagnostic of the hydrogen wall through measurements of the backscattered solar Lyman alpha radiation by Voyager 1/UVS in 1993-2003

    NASA Astrophysics Data System (ADS)

    Katushkina, O. A.; Quémerais, E.; Izmodenov, V. V.; Alexashov, D. B.; Sandel, B. R.

    2016-01-01

    We perform a new analysis of the Lyman alpha data obtained by Voyager 1 during the spatial scans in 1993-2003 while Voyager 1 was at 53-88 AU from the Sun. These data are the important source of information on the hydrogen distribution in the outer heliosphere. A sophisticated global kinetic-MHD model of the heliospheric interface and a radiative transfer model are used for the analysis. It is shown for the first time that the ratio of the Lyman alpha intensities detected in the downwind and upwind lines of sight in the outer heliosphere is sensitive to the configuration (peak value and location) of the hydrogen wall. The hydrogen wall is a source of Doppler-shifted backscattered Lyman alpha photons, so it can be seen from inside the heliosphere. Therefore, Voyager 1/ultraviolet spectrometer (UVS) Lyman alpha data can be used for remote sensing of the hydrogen wall. We show that our current global model of the outer heliosphere, which is consistent with many other measurements including Lyman alpha data from both Voyager 1 and 2 in 1980-1993, provides a systematically larger downwind to upwind intensity ratio compared with the UVS data in 1993-2003. In order to decrease the ratio, a higher and/or closer hydrogen wall is needed.

  7. The role of protein kinase C alpha translocation in radiation-induced bystander effect

    PubMed Central

    Fang, Zihui; Xu, An; Wu, Lijun; Hei, Tom K.; Hong, Mei

    2016-01-01

    Ionizing radiation is a well known human carcinogen. Evidence accumulated over the past decade suggested that extranuclear/extracellular targets and events may also play a critical role in modulating biological responses to ionizing radiation. However, the underlying mechanism(s) of radiation-induced bystander effect is still unclear. In the current study, AL cells were irradiated with alpha particles and responses of bystander cells were investigated. We found out that in bystander AL cells, protein kinase C alpha (PKCα) translocated from cytosol to membrane fraction. Pre-treatment of cells with PKC translocation inhibitor chelerythrine chloride suppressed the induced extracellular signal-regulated kinases (ERK) activity and the increased cyclooxygenase 2 (COX-2) expression as well as the mutagenic effect in bystander cells. Furthermore, tumor necrosis factor alpha (TNFα) was elevated in directly irradiated but not bystander cells; while TNFα receptor 1 (TNFR1) increased in the membrane fraction of bystander cells. Further analysis revealed that PKC activation caused accelerated internalization and recycling of TNFR1. Our data suggested that PKCα translocation may occur as an early event in radiation-induced bystander responses and mediate TNFα-induced signaling pathways that lead to the activation of ERK and up-regulation of COX-2. PMID:27165942

  8. Radiation Transport of Heliospheric Lyman-alpha from Combined Cassini and Voyager Data Sets

    NASA Technical Reports Server (NTRS)

    Pryor, W.; Gangopadhyay, P.; Sandel, B.; Forrester, T.; Quemerais, E.; Moebius, E.; Esposito, L.; Stewart, I.; McClintock, W.; Jouchoux, A.; Colwell, J.; Izmodenov, V.; Malama, Y.; Shemansky, D.; Ajello, J.; Hansen, C.; Bzowski, M.

    2008-01-01

    Heliospheric neutral hydrogen scatters solar Lyman-alpha radiation from the Sun with '27-day' intensity modulations observed near Earth due to the Sun's rotation combined with Earth's orbital motion. These modulations are increasingly damped in amplitude at larger distances from the Sun due to multiple scattering in the heliosphere, providing a diagnostic of the interplanetary neutral hydrogen density independent of instrument calibration. This paper presents Cassini data from 2003-2004 obtained downwind near Saturn at approximately 10 AU that at times show undamped '27-day' waves in good agreement with the single-scattering models of Pryor et al., 1992. Simultaneous Voyager 1 data from 2003- 2004 obtained upwind at a distance of 88.8-92.6 AU from the Sun show waves damped by a factor of -0.21. The observed degree of damping is interpreted in terms of Monte Carlo multiple-scattering calculations (e.g., Keller et al., 1981) applied to two heliospheric hydrogen two-shock density distributions (discussed in Gangopadhyay et al., 2006) calculated in the frame of the Baranov-Malama model of the solar wind interaction with the two-component (neutral hydrogen and plasma) interstellar wind (Baranov and Malama 1993, Izmodenov et al., 2001, Baranov and Izmodenov, 2006). We conclude that multiple scattering is definitely occurring in the outer heliosphere. Both models compare favorably to the data, using heliospheric neutral H densities at the termination shock of 0.085 cm(exp -3) and 0.095 cm(exp -3). This work generally agrees with earlier discussions of Voyager data in Quemerais et al., 1996 showing the importance of multiple scattering but is based on Voyager data obtained at larger distances from the Sun (with larger damping) simultaneously with Cassini data obtained closer to the Sun.

  9. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew

    2013-10-01

    The class of objects that reionized intergalactic hydrogen remains an observational and theoretical problem that is in contention for being the most prominent puzzle piece in contemporary astrophysics. The current consensus - determined almost entirely by ruling out bright active galaxies - is that the process was possibly begun and almost certainly finished by faint, lower-mass galaxies forming their early generations of stars. Recent observations of z 3 galaxies may even have identified the analog populations.However understanding how the emitted ionizing power of galaxies is causally related to their {robustly determined} physical properties is not a study that can be performed at high-z: neither the spatial information nor the standard multi-wavelength diagnostics are available. Moreover, on a case-by-case basis, the intervening IGM absorption is impossible to determine. These considerations have spawned a number of detailed studies with UV space telescopes, the synthesis of which however is that a characteristic population of Lyman continuum {LyC} emitting objects has not yet been identified. We show in this proposal that we have identified a characteristic trait in galaxy spectra that is highly indicative of LyC emission, by combining {a} high-z phenomenological studies, {b} new high-resolution UV spectra of local galaxies, and {c} sophisticated models of radiation transport. Believing that we have determined the signature, we propose to test the new hypothesis with deep spectroscopic observations with HST/COS under the Cycle 21 UV initiative.

  10. Intense attosecond radiation from an X-ray FEL

    SciTech Connect

    Zholents, Alexander A.; Fawley, William M.

    2003-11-21

    We propose the use of a ultra-relativistic electron beam interacting with a few-cycle, intense laser pulse and an intense pulse of the coherent x-rays to produce a multi-MW intensity, x-ray pulses {approx} 100 attoseconds in duration. Due to a naturally-occurring frequency chirp, these pulses can be further temporally compressed.

  11. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Not Available

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  12. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  13. Intensity Modulated Radiation Therapy With Dose Painting to Treat Rhabdomyosarcoma

    SciTech Connect

    Yang, Joanna C.; Dharmarajan, Kavita V.; Wexler, Leonard H.; La Quaglia, Michael P.; Happersett, Laura; Wolden, Suzanne L.

    2012-11-01

    Purpose: To examine local control and patterns of failure in rhabdomyosarcoma patients treated with intensity modulated radiation therapy (RT) with dose painting (DP-IMRT). Patients and Methods: A total of 41 patients underwent DP-IMRT with chemotherapy for definitive treatment. Nineteen also underwent surgery with or without intraoperative RT. Fifty-six percent had alveolar histologic features. The median interval from beginning chemotherapy to RT was 17 weeks (range, 4-25). Very young children who underwent second-look procedures with or without intraoperative RT received reduced doses of 24-36 Gy in 1.4-1.8-Gy fractions. Young adults received 50.4 Gy to the primary tumor and lower doses of 36 Gy in 1.8-Gy fractions to at-risk lymph node chains. Results: With 22 months of median follow-up, the actuarial local control rate was 90%. Patients aged {<=}7 years who received reduced overall and fractional doses had 100% local control, and young adults had 79% (P=.07) local control. Three local failures were identified in young adults whose primary target volumes had received 50.4 Gy in 1.8-Gy fractions. Conclusions: DP-IMRT with lower fractional and cumulative doses is feasible for very young children after second-look procedures with or without intraoperative RT. DP-IMRT is also feasible in adolescents and young adults with aggressive disease who would benefit from prophylactic RT to high-risk lymph node chains, although dose escalation might be warranted for improved local control. With limited follow-up, it appears that DP-IMRT produces local control rates comparable to those of sequential IMRT in patients with rhabdomyosarcoma.

  14. Radiation efficacy and biological risk from whole-breast irradiation via intensity modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Desantis, David M.

    Radiotherapy is an established modality for women with breast cancer. During the delivery of external beam radiation to the breast, leakage, scattered x-rays from the patient and the linear accelerator also expose healthy tissues and organs outside of the breast, thereby increasing the patient's whole-body dose, which then increases the chance of developing a secondary, radiation-induced cancer. Generally, there are three IntensityModulated Radiotherapy (IMRT) delivery techniques from a conventional linear accelerator; forward planned (FMLC), inverse planned 'sliding window' (DMLC), and inverse planned 'step-and-shoot' (SMLC). The goal of this study was to determine which of these three techniques delivers an optimal dose to the breast with the least chance of causing a fatal, secondary, radiation-induced cancer. A conventional, non-IMRT, 'Wedge' plan also was compared. Computerized Tomography (CT) data sets for both a large and small sized patient were used in this study. With Varian's Eclipse AAA algorithm, the organ doses specified in the revised ICRP 60 publication were used to calculate the whole-body dose. Also, an anthropomorphic phantom was irradiated with thermoluminescent dosimeters (TLD) at each organ site for measured doses. The risk coefficient from the Biological Effects of Ionizing Radiation (BEIR) VII report of 4.69 x 10-2 deaths per Gy was used to convert whole-body dose to risk of a fatal, secondary, radiation-induced cancer. The FMLC IMRT delivered superior tumor coverage over the 3D conventional plan and the inverse DMLC or SMLC treatment plans delivered clinically equivalent tumor coverage. However, the FMLC plan had the least likelihood of inadvertently causing a fatal, secondary, radiation-induced cancer compared to the inverse DMLC, SMLC, and Wedge plans.

  15. Fluorescence Quenching of Alpha-Fetoprotein by Gold Nanoparticles: Effect of Dielectric Shell on Non-Radiative Decay

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Li, Jian-Jun; Wang, A.-Qing; Chen, Yu; Zhao, Jun-Wu

    2010-09-01

    Fluorescence quenching spectrometry was applied to study the interactions between gold colloidal nanoparticles and alpha-fetoprotein (AFP). Experimental results show that the gold nanoparticles can quench the fluorescence emission of adsorbed AFP effectively. Furthermore, the intensity of fluorescence emission peak decreases monotonously with the increasing gold nanoparticles content. A mechanism based on surface plasmon resonance-induced non-radiative decay was investigated to illuminate the effect of a dielectric shell on the fluorescence quenching ability of gold nanoparticles. The calculation results show that the increasing dielectric shell thickness may improve the monochromaticity of fluorescence quenching. However, high energy transfer efficiency can be obtained within a wide wavelength band by coating a thinner dielectric shell.

  16. Bile Acid Malabsorption After Pelvic and Prostate Intensity Modulated Radiation Therapy: An Uncommon but Treatable Condition

    SciTech Connect

    Harris, Victoria; Benton, Barbara; Sohaib, Aslam; Dearnaley, David; Andreyev, H. Jervoise N.

    2012-12-01

    Purpose: Intensity modulated radiation therapy (IMRT) is a significant therapeutic advance in prostate cancer, allowing increased tumor dose delivery and increased sparing of normal tissues. IMRT planning uses strict dose constraints to nearby organs to limit toxicity. Bile acid malabsorption (BAM) is a treatable disorder of the terminal ileum (TI) that presents with symptoms similar to radiation therapy toxicity. It has not been described in patients receiving RT for prostate cancer in the contemporary era. We describe new-onset BAM in men after IMRT for prostate cancer. Methods and Materials: Diagnosis of new-onset BAM was established after typical symptoms developed, selenium-75 homocholic acid taurine (SeHCAT) scanning showed 7-day retention of <15%, and patients' symptoms unequivocally responded to a bile acid sequestrant. The TI was identified on the original radiation therapy plan, and the radiation dose delivered was calculated and compared with accepted dose-volume constraints. Results: Five of 423 men treated in a prospective series of high-dose prostate and pelvic IMRT were identified with new onset BAM (median age, 65 years old). All reported having normal bowel habits before RT. The volume of TI ranged from 26-141 cc. The radiation dose received by the TI varied between 11.4 Gy and 62.1 Gy (uncorrected). Three of 5 patients had TI treated in excess of 45 Gy (equivalent dose calculated in 2-Gy fractions, using an {alpha}/{beta} ratio of 3) with volumes ranging from 1.6 cc-49.0 cc. One patient had mild BAM (SeHCAT retention, 10%-15%), 2 had moderate BAM (SeHCAT retention, 5%-10%), and 2 had severe BAM (SeHCAT retention, <5%). The 3 patients whose TI received {>=}45 Gy developed moderate to severe BAM, whereas those whose TI received <45 Gy had only mild to moderate BAM. Conclusions: Radiation delivered to the TI during IMRT may cause BAM. Identification of the TI from unenhanced RT planning computed tomography scans is difficult and may impede accurate

  17. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  18. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  19. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  20. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  1. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  2. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  3. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  4. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  5. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  6. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  7. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  8. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High-intensity Radiated Fields...

  9. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High-intensity Radiated Fields...

  10. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  11. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1317 High-intensity Radiated Fields...

  12. QUANTIFICATION OF ACTINIDE ALPHA-RADIATION DAMAGE IN MINERALS AND CERAMICS

    SciTech Connect

    Farnan, Ian E.; Cho, Herman M.; Weber, William J.

    2007-01-11

    There are large amounts of heavy alpha-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is a consensus that actinides that have been separated from spent nuclear fuel should be immobilised within mineral-based ceramics rather than glass. Over the long-term, the alpha-decay taking place in these ceramics will severely disrupt their crystalline structure and reduce their durability. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per alpha–decay. Currently, this number is estimated as 1000-2000 atoms/alpha decay event. Here, we report nuclear magnetic resonance, spin-counting experiments that measure close to 5000 atoms/alpha decay event in radiation damaged natural zircons. New radiological NMR measurements on highly radioactive, 239Pu zircon show damage similar to that created by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of dose rate. Based on these measurements, the initially crystalline structure of a 10 wt% 239Pu zircon would be amorphous after only 1400 years in a geological repository. These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics based on an atomistic understanding of the fundamental damage event.

  13. Addition Laws for Intensities of Radiation Emerging from Scattering Atmospheres Containing Energy Sources

    NASA Astrophysics Data System (ADS)

    Nikoghossian, A. G.; Kapanadze, N. G.

    2016-03-01

    A group theoretical approach is developed for solving astrophysical radiative transfer problems described in a previous series of papers. Addition laws for observed radiative intensities are derived for the case in which atmospheres not only absorb and scatter radiation incident on them, but radiate themselves because of energy sources contained within them. As an illustration of the application of these laws, several special radiative transfer problems which we believe are of practical interest are discussed.

  14. Enhancement of K{sub {alpha}} emission through efficient hot electron generation in carbon nanotubes on intense laser pulse irradiation

    SciTech Connect

    Chakravarty, U.; Arora, V.; Naik, P. A.; Chakera, J. A.; Srivastava, H.; Srivastava, A.; Kumbhare, S. R.; Gupta, P. D.; Varma, G. D.

    2012-09-01

    Near complete absorption of the energy of intense ultra-short laser pulses (45 fs, intensity {approx}1.6 Multiplication-Sign 10{sup 16} to 2.5 Multiplication-Sign 10{sup 17} W/cm{sup 2}) is observed in carbon nanotubes deposited on a planar molybdenum substrate. The hollow structure of the nanotube plasma facilitates resonant electric field enhancement during its ionization phase. This resonantly enhanced localized field at a density much larger than the critical density n{sub c} leads to efficient hot electron generation, which results in enhanced K{sub {alpha}} emission of Mo at 17.5 keV. It is observed that for nanotubes, depending on the degree of hollowness, there is an optimum laser intensity for maximum x-ray enhancement compared to a planar uncoated target.

  15. Ly{alpha} RADIATIVE TRANSFER IN COSMOLOGICAL SIMULATIONS USING ADAPTIVE MESH REFINEMENT

    SciTech Connect

    Laursen, Peter; Razoumov, Alexei O.; Sommer-Larsen, Jesper E-mail: razoumov@ap.smu.ca

    2009-05-01

    A numerical code for solving various Ly{alpha} radiative transfer (RT) problems is presented. The code is suitable for an arbitrary, three-dimensional distribution of Ly{alpha} emissivity, gas temperature, density, and velocity field. Capable of handling Ly{alpha} RT in an adaptively refined grid-based structure, it enables detailed investigation of the effects of clumpiness of the interstellar (or intergalactic) medium. The code is tested against various geometrically and physically idealized configurations for which analytical solutions exist, and subsequently applied to three different simulated high-resolution 'Lyman-break galaxies', extracted from high-resolution cosmological simulations at redshift z = 3.6. Proper treatment of the Ly{alpha} scattering reveals a diversity of surface brightness (SB) and line profiles. Specifically, for a given galaxy the maximum observed SB can vary by an order of magnitude, and the total flux by a factor of 3-6, depending on the viewing angle. This may provide an explanation for differences in observed properties of high-redshift galaxies, and in particular a possible physical link between Lyman-break galaxies and regular Ly{alpha} emitters.

  16. Art, alpha-1-antitrypsin polymorphisms and intense creative energy: blessing or curse?

    PubMed

    Schmechel, Donald Everett

    2007-09-01

    Persons heterozygous for Z, S and rare alpha-1-antitrypsin (AAT, SERPIN1A) polymorphisms (ca. 9% of population) are often considered 'silent' carriers with increased vulnerability to environmentally modulated liver and lung disease. They may have significantly more anxiety and bipolar spectrum disorders, nutritional compromise, and white matter disease [Schmechel DE, Browndyke J, Ghio A. Strategies for the dissection of genetic-environmental interactions in neurodegenerative disorders. Neurotoxicology 2006;27:637-57]. Given association of art and mood disorders, we examined occupation and artistic vocation from this same series. One thousand five hundred and thirty-seven consecutive persons aged 16-90 years old received comprehensive work-up including testing for AAT 'phenotype' and level, nutritional factors, and inflammatory, iron and copper indices. Occupations were grouped by Bureau of Labor Standards classification and information gathered on artistic activities. Proportion of reactive airway disease, obstructive pulmonary disease, and pre-existing anxiety disorder or bipolar disorder were significantly increased in persons carrying AAT non-M polymorphisms compared to normal MM genotype (respectively, 10, 20, 21, and 33% compared to 8, 12, 11, and 9%; contingency table, pulmonary: chi2 37, p=0.0001; affective disorder: chi2=171, p=0.0001). In persons with artistic avocation (n=189) or occupation (n=57), AAT non-M polymorphisms are significantly increased (respectively, proportions of 44 and 40% compared to background rate of 9%; contingency table, avocation: chi2=172, p=0.0001; occupation: chi2=57, p=0.0007). Artistic ability and 'anxiety/bipolar spectrum' mood disorders may represent phenotypic attributes that had selective advantage during recent human evolution, an 'intensive creative energy' (ICE) behavioral phenotype. Background proportion of ICE of 7% consists of 49 of 1312 persons with AAT MM genotype (4%), and 58 of 225 persons with non-MM genotypes

  17. Comparative analysis of 60Co intensity-modulated radiation therapy.

    PubMed

    Fox, Christopher; Romeijn, H Edwin; Lynch, Bart; Men, Chunhua; Aleman, Dionne M; Dempsey, James F

    2008-06-21

    In this study, we perform a scientific comparative analysis of using (60)Co beams in intensity-modulated radiation therapy (IMRT). In particular, we evaluate the treatment plan quality obtained with (i) 6 MV, 18 MV and (60)Co IMRT; (ii) different numbers of static multileaf collimator (MLC) delivered (60)Co beams and (iii) a helical tomotherapy (60)Co beam geometry. We employ a convex fluence map optimization (FMO) model, which allows for the comparison of plan quality between different beam energies and configurations for a given case. A total of 25 clinical patient cases that each contain volumetric CT studies, primary and secondary delineated targets, and contoured structures were studied: 5 head-and-neck (H&N), 5 prostate, 5 central nervous system (CNS), 5 breast and 5 lung cases. The DICOM plan data were anonymized and exported to the University of Florida optimized radiation therapy (UFORT) treatment planning system. The FMO problem was solved for each case for 5-71 equidistant beams as well as a helical geometry for H&N, prostate, CNS and lung cases, and for 3-7 equidistant beams in the upper hemisphere for breast cases, all with 6 MV, 18 MV and (60)Co dose models. In all cases, 95% of the target volumes received at least the prescribed dose with clinical sparing criteria for critical organs being met for all structures that were not wholly or partially contained within the target volume. Improvements in critical organ sparing were found with an increasing number of equidistant (60)Co beams, yet were marginal above 9 beams for H&N, prostate, CNS and lung. Breast cases produced similar plans for 3-7 beams. A helical (60)Co beam geometry achieved similar plan quality as static plans with 11 equidistant (60)Co beams. Furthermore, 18 MV plans were initially found not to provide the same target coverage as 6 MV and (60)Co plans; however, adjusting the trade-offs in the optimization model allowed equivalent target coverage for 18 MV. For plans with comparable

  18. Comparative analysis of 60Co intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Fox, Christopher; Romeijn, H. Edwin; Lynch, Bart; Men, Chunhua; Aleman, Dionne M.; Dempsey, James F.

    2008-06-01

    In this study, we perform a scientific comparative analysis of using 60Co beams in intensity-modulated radiation therapy (IMRT). In particular, we evaluate the treatment plan quality obtained with (i) 6 MV, 18 MV and 60Co IMRT; (ii) different numbers of static multileaf collimator (MLC) delivered 60Co beams and (iii) a helical tomotherapy 60Co beam geometry. We employ a convex fluence map optimization (FMO) model, which allows for the comparison of plan quality between different beam energies and configurations for a given case. A total of 25 clinical patient cases that each contain volumetric CT studies, primary and secondary delineated targets, and contoured structures were studied: 5 head-and-neck (H&N), 5 prostate, 5 central nervous system (CNS), 5 breast and 5 lung cases. The DICOM plan data were anonymized and exported to the University of Florida optimized radiation therapy (UFORT) treatment planning system. The FMO problem was solved for each case for 5-71 equidistant beams as well as a helical geometry for H&N, prostate, CNS and lung cases, and for 3-7 equidistant beams in the upper hemisphere for breast cases, all with 6 MV, 18 MV and 60Co dose models. In all cases, 95% of the target volumes received at least the prescribed dose with clinical sparing criteria for critical organs being met for all structures that were not wholly or partially contained within the target volume. Improvements in critical organ sparing were found with an increasing number of equidistant 60Co beams, yet were marginal above 9 beams for H&N, prostate, CNS and lung. Breast cases produced similar plans for 3-7 beams. A helical 60Co beam geometry achieved similar plan quality as static plans with 11 equidistant 60Co beams. Furthermore, 18 MV plans were initially found not to provide the same target coverage as 6 MV and 60Co plans; however, adjusting the trade-offs in the optimization model allowed equivalent target coverage for 18 MV. For plans with comparable target coverage

  19. Inverse planning optimization method for intensity modulated radiation therapy.

    PubMed

    Lan, Yihua; Ren, Haozheng; Li, Cunhua; Min, Zhifang; Wan, Jinxin; Ma, Jianxin; Hung, Chih-Cheng

    2013-10-01

    In order to facilitate the leaf sequencing process in intensity modulated radiation therapy (IMRT), and design of a practical leaf sequencing algorithm, it is an important issue to smooth the planned fluence maps. The objective is to achieve both high-efficiency and high-precision dose delivering by considering characteristics of leaf sequencing process. The key factor which affects total number of monitor units for the leaf sequencing optimization process is the max flow value of the digraph which formulated from the fluence maps. Therefore, we believe that one strategy for compromising dose conformity and total number of monitor units in dose delivery is to balance the dose distribution function and the max flow value mentioned above. However, there are too many paths in the digraph, and we don't know the flow value of which path is the maximum. The maximum flow value among the horizontal paths was selected and used in the objective function of the fluence map optimization to formulate the model. The model is a traditional linear constrained quadratic optimization model which can be solved by interior point method easily. We believe that the smoothed maps from this model are more suitable for leaf sequencing optimization process than other smoothing models. A clinical head-neck case and a prostate case were tested and compared using our proposed model and the smoothing model which is based on the minimization of total variance. The optimization results with the same level of total number of monitor units (TNMU) show that the fluence maps obtained from our model have much better dose performance for the target/non-target region than the maps from total variance based on the smoothing model. This indicates that our model achieves better dose distribution when the algorithm suppresses the TNMU at the same level. Although we have just used the max flow value of the horizontal paths in the diagraph in the objective function, a good balance has been achieved between

  20. Quantification of actinide alpha-radiation damage in minerals and ceramics.

    PubMed

    Farnan, Ian; Cho, Herman; Weber, William J

    2007-01-11

    There are large amounts of heavy alpha-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is consensus that actinides that have been separated from spent nuclear fuel should be immobilized within mineral-based ceramics rather than glass because of their superior aqueous durability and lower risk of accidental criticality. However, in the long term, the alpha-decay taking place in these ceramics will severely disrupt their crystalline structure and reduce their durability. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per alpha-decay. At present, this number is estimated to be 1,000-2,000 atoms/alpha in zircon. Here we report nuclear magnetic resonance, spin-counting experiments that measure close to 5,000 atoms/alpha in radiation-damaged natural zircons. New radiological nuclear magnetic resonance measurements on highly radioactive, 239Pu zircon show damage similar to that caused by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of half-life or loading levels (dose rate). On the basis of these measurements, the initially crystalline structure of a 10 weight per cent 239Pu zircon would be amorphous after only 1,400 years in a geological repository (desired immobilization timescales are of the order of 250,000 years). These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics in terms of an atomistic understanding of the fundamental damage event. PMID:17215840

  1. Effects of radiation reaction in the interaction between cluster media and high intensity lasers in the radiation dominant regime

    NASA Astrophysics Data System (ADS)

    Iwata, Natsumi; Nagatomo, Hideo; Fukuda, Yuji; Matsui, Ryutaro; Kishimoto, Yasuaki

    2016-06-01

    Interaction between media composed of clusters and high intensity lasers in the radiation dominant regime, i.e., intensity of 10 22 - 23 W / cm 2 , is studied based on the particle-in-cell simulation that includes the radiation reaction. By introducing target materials that have the same total mass but different internal structures, i.e., uniform plasma and cluster media with different cluster radii, we investigate the effect of the internal structure on the interaction dynamics, high energy radiation emission, and its reaction. Intense radiation emission is found in the cluster media where electrons exhibit non-ballistic motions suffering from strong accelerations by both the penetrated laser field and charge separation field of clusters. As a result, the clustered structure increases the energy conversion into high energy radiations significantly at the expense of the conversion into particles, while the total absorption rate into radiation and particles remains unchanged from the absorption rate into particles in the case without radiation reaction. The maximum ion energy achieved in the interaction with cluster media is found to be decreased through the radiation reaction to electrons into the same level with that achieved in the interaction with the uniform plasma. The clustered structure thus enhances high energy radiation emission rather than the ion acceleration in the considered intensity regime.

  2. Generation of radiation by intense plasma and electromagnetic undulators

    SciTech Connect

    Joshi, C.

    1991-10-01

    We examine the characteristics of the classical radiation emission resulting from the interaction of a relativistic electron beam that propagates perpendicularly through a large amplitude relativistic plasma wave. Such a study is useful for evaluating the feasibility of using relativistic plasma waves as extremely short wavelength undulators for generating short wavelength radiation. The electron trajectories in a plasma wave undulator and in an ac FEL undulator are obtained using perturbation techniques. The spontaneous radiation frequency spectrum and angular distribution emitted by a single electron oscillating in these two undulators are then calculated. The radiation gain of a copropagating electromagnetic wave is calculated. The approximate analytic results for the trajectories, spontaneous radiation and gain are compared with 3-D simulation results. The characteristics of the plasma wave undulator are compared with the ac FEL undulator and linearly polarized magnetic undulator. 50 refs., 26 figs., 3 tabs.

  3. Semi-Automatic Segmentation of Optic Radiations and LGN, and Their Relationship to EEG Alpha Waves

    PubMed Central

    Descoteaux, Maxime; Bernier, Michaël; Garyfallidis, Eleftherios; Whittingstall, Kevin

    2016-01-01

    At rest, healthy human brain activity is characterized by large electroencephalography (EEG) fluctuations in the 8-13 Hz range, commonly referred to as the alpha band. Although it is well known that EEG alpha activity varies across individuals, few studies have investigated how this may be related to underlying morphological variations in brain structure. Specifically, it is generally believed that the lateral geniculate nucleus (LGN) and its efferent fibres (optic radiation, OR) play a key role in alpha activity, yet it is unclear whether their shape or size variations contribute to its inter-subject variability. Given the widespread use of EEG alpha in basic and clinical research, addressing this is important, though difficult given the problems associated with reliably segmenting the LGN and OR. For this, we employed a multi-modal approach and combined diffusion magnetic resonance imaging (dMRI), functional magnetic resonance imaging (fMRI) and EEG in 20 healthy subjects to measure structure and function, respectively. For the former, we developed a new, semi-automated approach for segmenting the OR and LGN, from which we extracted several structural metrics such as volume, position and diffusivity. Although these measures corresponded well with known morphology based on previous post-mortem studies, we nonetheless found that their inter-subject variability was not significantly correlated to alpha power or peak frequency (p >0.05). Our results therefore suggest that alpha variability may be mediated by an alternative structural source and our proposed methodology may in general help in better understanding the influence of anatomy on function such as measured by EEG or fMRI. PMID:27383146

  4. Semi-Automatic Segmentation of Optic Radiations and LGN, and Their Relationship to EEG Alpha Waves.

    PubMed

    Renauld, Emmanuelle; Descoteaux, Maxime; Bernier, Michaël; Garyfallidis, Eleftherios; Whittingstall, Kevin

    2016-01-01

    At rest, healthy human brain activity is characterized by large electroencephalography (EEG) fluctuations in the 8-13 Hz range, commonly referred to as the alpha band. Although it is well known that EEG alpha activity varies across individuals, few studies have investigated how this may be related to underlying morphological variations in brain structure. Specifically, it is generally believed that the lateral geniculate nucleus (LGN) and its efferent fibres (optic radiation, OR) play a key role in alpha activity, yet it is unclear whether their shape or size variations contribute to its inter-subject variability. Given the widespread use of EEG alpha in basic and clinical research, addressing this is important, though difficult given the problems associated with reliably segmenting the LGN and OR. For this, we employed a multi-modal approach and combined diffusion magnetic resonance imaging (dMRI), functional magnetic resonance imaging (fMRI) and EEG in 20 healthy subjects to measure structure and function, respectively. For the former, we developed a new, semi-automated approach for segmenting the OR and LGN, from which we extracted several structural metrics such as volume, position and diffusivity. Although these measures corresponded well with known morphology based on previous post-mortem studies, we nonetheless found that their inter-subject variability was not significantly correlated to alpha power or peak frequency (p >0.05). Our results therefore suggest that alpha variability may be mediated by an alternative structural source and our proposed methodology may in general help in better understanding the influence of anatomy on function such as measured by EEG or fMRI. PMID:27383146

  5. Alpha-radiation tests on the transmission of cryogenically cooled infrared filter materials used in ISOPHOT

    NASA Astrophysics Data System (ADS)

    Schubert, Josef; Lemke, Dietrich; Kraetschmer, Wolfgang; Mampel, K.

    1995-09-01

    We have studied potential effects of the ISO spacecraft orbital radiation environment on the transmission of infrared interference filters and filter materials. To simulate the critical proton radiation within the earth radiation belts and its influence on the materials at cryogenic temperatures the samples were cooled to LHe temperature and subjected to an Am-241 (alpha) -radiation source (approximately 4.1 MeV) mounted inside a cryostat. The dose per hour absorbed in a 20 micron thick layer, the mean penetration depth for the (alpha) particles, was about 25 krad (Si). The substrates Ge, ZnSe, and CaF2 and three tested ISOPHOT interference bandpass filters (3.21-3.37 micrometers and 2-50 micrometers even after a total dose of approximately 0.5 Mrad (Si), which is more than 100 times the expected total dose for ISOPHOT. The multilayer interference blocking coating on sapphire used on all ISOPHOT far infrared filters to block the wavelength range 1.7-6.7 micrometers showed no degeneration either. The organic far infrared antireflex coating materials polyethylene deposited on a quartz substrate, and a 15 micrometers thick parylene foil used as field lens coating, were investigated in the wavelength range of 16-300 micrometers . Our data suggests a slightly reduced transmission < 6% after 350 krad (Si) exposure.

  6. Two-stream cyclotron radiative instabilities due to the marginally mirror-trapped fraction for fustion alphas in tokamaks

    SciTech Connect

    Arunasalam, V.

    1995-07-01

    It is shown here that the marginally mirror-trapped fraction of the newly-born fusion alpha particles in the deuterium-tritium (DT) reaction dominated tokamak plasmas can induce a two-stream cyclotron radiative instability for the fast Alfven waves propagating near the harmonics of the alpha particle cyclotron frequency {omega}{sub c{alpha}}. This can explain both the experimentally observed time behavior and the spatially localized origin of the fusion product ion cyclotron emission (ICE) in TFTR at frequencies {omega} {approx} m{omega}{sub c{alpha}}.

  7. Epigenetic regulation of diacylglycerol kinase alpha promotes radiation-induced fibrosis.

    PubMed

    Weigel, Christoph; Veldwijk, Marlon R; Oakes, Christopher C; Seibold, Petra; Slynko, Alla; Liesenfeld, David B; Rabionet, Mariona; Hanke, Sabrina A; Wenz, Frederik; Sperk, Elena; Benner, Axel; Rösli, Christoph; Sandhoff, Roger; Assenov, Yassen; Plass, Christoph; Herskind, Carsten; Chang-Claude, Jenny; Schmezer, Peter; Popanda, Odilia

    2016-01-01

    Radiotherapy is a fundamental part of cancer treatment but its use is limited by the onset of late adverse effects in the normal tissue, especially radiation-induced fibrosis. Since the molecular causes for fibrosis are largely unknown, we analyse if epigenetic regulation might explain inter-individual differences in fibrosis risk. DNA methylation profiling of dermal fibroblasts obtained from breast cancer patients prior to irradiation identifies differences associated with fibrosis. One region is characterized as a differentially methylated enhancer of diacylglycerol kinase alpha (DGKA). Decreased DNA methylation at this enhancer enables recruitment of the profibrotic transcription factor early growth response 1 (EGR1) and facilitates radiation-induced DGKA transcription in cells from patients later developing fibrosis. Conversely, inhibition of DGKA has pronounced effects on diacylglycerol-mediated lipid homeostasis and reduces profibrotic fibroblast activation. Collectively, DGKA is an epigenetically deregulated kinase involved in radiation response and may serve as a marker and therapeutic target for personalized radiotherapy. PMID:26964756

  8. Epigenetic regulation of diacylglycerol kinase alpha promotes radiation-induced fibrosis

    PubMed Central

    Weigel, Christoph; Veldwijk, Marlon R.; Oakes, Christopher C.; Seibold, Petra; Slynko, Alla; Liesenfeld, David B.; Rabionet, Mariona; Hanke, Sabrina A.; Wenz, Frederik; Sperk, Elena; Benner, Axel; Rösli, Christoph; Sandhoff, Roger; Assenov, Yassen; Plass, Christoph; Herskind, Carsten; Chang-Claude, Jenny; Schmezer, Peter; Popanda, Odilia

    2016-01-01

    Radiotherapy is a fundamental part of cancer treatment but its use is limited by the onset of late adverse effects in the normal tissue, especially radiation-induced fibrosis. Since the molecular causes for fibrosis are largely unknown, we analyse if epigenetic regulation might explain inter-individual differences in fibrosis risk. DNA methylation profiling of dermal fibroblasts obtained from breast cancer patients prior to irradiation identifies differences associated with fibrosis. One region is characterized as a differentially methylated enhancer of diacylglycerol kinase alpha (DGKA). Decreased DNA methylation at this enhancer enables recruitment of the profibrotic transcription factor early growth response 1 (EGR1) and facilitates radiation-induced DGKA transcription in cells from patients later developing fibrosis. Conversely, inhibition of DGKA has pronounced effects on diacylglycerol-mediated lipid homeostasis and reduces profibrotic fibroblast activation. Collectively, DGKA is an epigenetically deregulated kinase involved in radiation response and may serve as a marker and therapeutic target for personalized radiotherapy. PMID:26964756

  9. Radiation risk to low fluences of alpha particles may be greater than we thought.

    PubMed

    Zhou, H; Suzuki, M; Randers-Pehrson, G; Vannais, D; Chen, G; Trosko, J E; Waldren, C A; Hei, T K

    2001-12-01

    Based principally on the cancer incidence found in survivors of the atomic bombs dropped in Hiroshima and Nagasaki, the International Commission on Radiation Protection (ICRP) and the United States National Council on Radiation Protection and Measurements (NCRP) have recommended that estimates of cancer risk for low dose exposure be extrapolated from higher doses by using a linear, no-threshold model. This recommendation is based on the dogma that the DNA of the nucleus is the main target for radiation-induced genotoxicity and, as fewer cells are directly damaged, the deleterious effects of radiation proportionally decline. In this paper, we used a precision microbeam to target an exact fraction (either 100% or < or =20%) of the cells in a confluent population and irradiated their nuclei with exactly one alpha particle each. We found that the frequencies of induced mutations and chromosomal changes in populations where some known fractions of nuclei were hit are consistent with non-hit cells contributing significantly to the response. In fact, irradiation of 10% of a confluent mammalian cell population with a single alpha particle per cell results in a mutant yield similar to that observed when all of the cells in the population are irradiated. This effect was significantly eliminated in cells pretreated with a 1 mM dose of octanol, which inhibits gap junction-mediated intercellular communication, or in cells carrying a dominant negative connexin 43 vector. The data imply that the relevant target for radiation mutagenesis is larger than an individual cell and suggest a need to reconsider the validity of the linear extrapolation in making risk estimates for low dose, high linear-energy-transfer (LET) radiation exposure. PMID:11734643

  10. Application of Histogram Analysis in Radiation Therapy (HART) in Intensity Modulation Radiation Therapy (IMRT) Treatments

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-03-01

    A carcinoma is a malignant cancer that emerges from epithelial cells in structures through out the body.It invades the critical organs, could metastasize or spread to lymph nodes.IMRT is an advanced mode of radiation therapy treatment for cancer. It delivers more conformal doses to malignant tumors sparing the critical organs by modulating the intensity of radiation beam.An automated software, HART (S. Jang et al.,2008,Med Phys 35,p.2812) was used for efficient analysis of dose volume histograms (DVH) for multiple targets and critical organs in four IMRT treatment plans for each patient. IMRT data for ten head and neck cancer patients were exported as AAPM/RTOG format files from a commercial treatment planning system at Northwestern Memorial Hospital (NMH).HART extracted DVH statistics were used to evaluate plan indices and to analyze dose tolerance of critical structures at prescription dose (PD) for each patient. Mean plan indices (n=10) were found to be in good agreement with published results for Linac based plans. The least irradiated volume at tolerance dose (TD50) was observed for brainstem and the highest volume for larynx in SIB treatment techniques. Thus HART, an open source platform, has extensive clinical implications in IMRT treatments.

  11. Monitoring Alpha Oscillations and Pupil Dilation across a Performance-Intensity Function

    PubMed Central

    McMahon, Catherine M.; Boisvert, Isabelle; de Lissa, Peter; Granger, Louise; Ibrahim, Ronny; Lo, Chi Yhun; Miles, Kelly; Graham, Petra L.

    2016-01-01

    Listening to degraded speech can be challenging and requires a continuous investment of cognitive resources, which is more challenging for those with hearing loss. However, while alpha power (8–12 Hz) and pupil dilation have been suggested as objective correlates of listening effort, it is not clear whether they assess the same cognitive processes involved, or other sensory and/or neurophysiological mechanisms that are associated with the task. Therefore, the aim of this study is to compare alpha power and pupil dilation during a sentence recognition task in 15 randomized levels of noise (-7 to +7 dB SNR) using highly intelligible (16 channel vocoded) and moderately intelligible (6 channel vocoded) speech. Twenty young normal-hearing adults participated in the study, however, due to extraneous noise, data from only 16 (10 females, 6 males; aged 19–28 years) was used in the Electroencephalography (EEG) analysis and 10 in the pupil analysis. Behavioral testing of perceived effort and speech performance was assessed at 3 fixed SNRs per participant and was comparable to sentence recognition performance assessed in the physiological test session for both 16- and 6-channel vocoded sentences. Results showed a significant interaction between channel vocoding for both the alpha power and the pupil size changes. While both measures significantly decreased with more positive SNRs for the 16-channel vocoding, this was not observed with the 6-channel vocoding. The results of this study suggest that these measures may encode different processes involved in speech perception, which show similar trends for highly intelligible speech, but diverge for more spectrally degraded speech. The results to date suggest that these objective correlates of listening effort, and the cognitive processes involved in listening effort, are not yet sufficiently well understood to be used within a clinical setting. PMID:27252671

  12. Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements

    NASA Technical Reports Server (NTRS)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The analysis of Mariner 10 observations of Lyman-alpha resonance radiation shows an increase of interplanetary neutral hydrogen densities above the solar poles. This increase is caused by a latitudinal variation of the solar wind velocity and/or flux. Using both the Mariner 10 results and other solar wind observations, the values of the solar wind flux and velocity with latitude are determined for several cases of interest. The latitudinal variation of interplanetary hydrogen gas, arising from the solar wind latitudinal variation, is shown to be most pronounced in the inner solar system. From this result it is shown that spacecraft Lyman-alpha observations are more sensitive to the latitudinal anisotropy for a spacecraft location in the inner solar system near the downwind axis.

  13. Growth and Characterization of alpha-PbO for Room Temperature Radiation Detection

    NASA Astrophysics Data System (ADS)

    Ford, Erin Leigh

    A global trading structure and high throughput of shipping containers into ports around the world increases the chance of nuclear terrorism via cargo containers. Harmless radioactive sources confuse and impede detection of the materials that pose a real threat, making spectroscopy difficult and requiring detectors with high resolution. The current methods that are used to check containers in ports have security flaws, and only 5% of all shipping containers are checked. The development of semiconductor gamma-ray detectors is one of the protocols being advanced to alleviate this risk because they can function at room temperature and they are cost effective, easily produced, and have high resolution. This dissertation has addressed the current lack of "perfect" room temperature detector materials by investigating alpha-PbO, a novel material in this field. This includes the development of a growth process for alpha-PbO thin films, as well as its structural and performance characterization as a detector material. Because we intend alpha-PbO to be a photoconductive detector, it should have certain properties. A photoconductive detector consists of a highly resistive material with a voltage bias across it. It absorbs incident gamma-rays, creating electron-hole pairs that provide a signal. To function well, it must have a high atomic number and a high density in order to absorb high-energy photons via the photoelectric effect. It should also have a large resistivity and a wide band gap to avoid large leakage currents at room temperature. Finally, it must have good charge carrier transport properties and detector resolution in order to be able to determine the characteristic energy peaks of the radiation-emitting source. We chose alpha-PbO because it has a very high Z and a very high density and a band gap in the correct range. It also has a rich history of use as a photoconductor that reaches back to the 1950s. Numerous methods have been used to grow thin films of alpha

  14. Identification of gene-based responses in human blood cells exposed to alpha particle radiation

    PubMed Central

    2014-01-01

    Background The threat of a terrorist-precipitated nuclear event places humans at danger for radiological exposures. Isotopes which emit alpha (α)-particle radiation pose the highest risk. Currently, gene expression signatures are being developed for radiation biodosimetry and triage with respect to ionizing photon radiation. This study was designed to determine if similar gene expression profiles are obtained after exposures involving α-particles. Methods Peripheral blood mononuclear cells (PBMCs) were used to identify sensitive and robust gene-based biomarkers of α-particle radiation exposure. Cells were isolated from healthy individuals and were irradiated at doses ranging from 0-1.5 Gy. Microarray technology was employed to identify transcripts that were differentially expressed relative to unirradiated cells 24 hours post-exposure. Statistical analysis identified modulated genes at each of the individual doses. Results Twenty-nine genes were common to all doses with expression levels ranging from 2-10 fold relative to control treatment group. This subset of genes was further assessed in independent complete white blood cell (WBC) populations exposed to either α-particles or X-rays using quantitative real-time PCR. This 29 gene panel was responsive in the α-particle exposed WBCs and was shown to exhibit differential fold-changes compared to X-irradiated cells, though no α-particle specific transcripts were identified. Conclusion Current gene panels for photon radiation may also be applicable for use in α-particle radiation biodosimetry. PMID:25017500

  15. Sound radiation from an infinite elastic cylinder with dual-wave propagation-intensity distributions

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1988-01-01

    The radiation of sound from an elastic cylindrical shell filled with fluid and supporting multiwave propagation is studied analytically. Combinations of supersonic and subsonic shell waves are considered. The radiated field is mapped by using acoustic intensity vectors evaluated at various locations. Both time averaged and instantaneous intensity are investigated. The acoustic intensity is seen to vary markedly with axial distance down the cylinder. The effect is shown to be associated with cross terms in the intensity relations, and its magnitude and location to depend upon the relative phase and amplitudes of individual waves. Subsonic shell waves are demonstrated to interact strongly with supersonic shell waves to cause a large modification in the radiated intensity distributions near the shell surface.

  16. Energetic response of Chlorella vulgaris to alpha radiation and PCB stress

    SciTech Connect

    Schaffer, S.A.

    1982-01-01

    This research project has evaluated the bioenergetic response of the green alga Chlorella vulgaris following acute exposure to either the physical stress of radiation or the chemical stress of PCBs. After exposure, changes in survival or growth, adenylate pools (ATP, ADP, and AMP), CO/sub 2/ fixation and oxygen evolution and uptake were measured. By employing anaerobic conditions, or the electron transport inhibitor DCMU or dark conditions separately and in specific combinations, this study evaluated the response of three separate algal ATP producing mechanisms (respiration, total and cyclic photophosphorylation) to alpha radiation or PCB. The use of the adenylate energy charge ratio as an indicator of stress was also evaluated. The results of the radiation experiments indicated that alpha particle exposure between 25 to 275 rads caused a one-hour latent demand for ATP due to radioinduced DNA repair. In order to compensate for this ATP demand, nonessential utilization of ATP was decreased by slowing the rate of carbon fixation. The results also suggest that use of radiation as a tool to study algal physiology. The data obtained from the PCB experiments again showed each phosphorylation mechanism to be insensitive to 10, 100 and 200 ppm Aroclor 1254 exposures. Data suggest, however, that PCBs caused an increased photosynthetic rate, and total adenylate pool with decreased growth. The use of the adenylate energy charge ratio as a stress indicator was assessed. Because this ratio did not fluctuate at doses of radiation or PCBs that caused reduced survival and growth rates, this study concluded that for Chlorella the adenylate energy charge ration was a poor indicator of sublethal stress.

  17. Scintillator assembly for alpha radiation detection and an associated method of making

    DOEpatents

    Lauf, Robert J.; McElhaney, Stephanie A.; Bates, John B.

    1994-01-01

    A scintillator assembly for use in conjunction with a photomultiplier or the like in the detection of alpha radiation utilizes a substrate or transparent yttrium aluminum garnet and a relatively thin film of cerium-doped yttrium aluminum garnet coated upon the substrate. The film material is applied to the substrate in a sputtering process, and the applied film and substrate are annealed to effect crystallization of the film upon the substrate. The resultant assembly provides relatively high energy resolution during use in a detection instrument and is sufficiently rugged for use in field environments.

  18. Scintillator assembly for alpha radiation detection and an associated method of making

    DOEpatents

    Lauf, R.J.; McElhaney, S.A.; Bates, J.B.

    1994-07-26

    A scintillator assembly for use in conjunction with a photomultiplier or the like in the detection of alpha radiation utilizes a substrate or transparent yttrium aluminum garnet and a relatively thin film of cerium-doped yttrium aluminum garnet coated upon the substrate. The film material is applied to the substrate in a sputtering process, and the applied film and substrate are annealed to effect crystallization of the film upon the substrate. The resultant assembly provides relatively high energy resolution during use in a detection instrument and is sufficiently rugged for use in field environments. 4 figs.

  19. High spatial resolution photographs of the sun in L alpha radiation.

    NASA Technical Reports Server (NTRS)

    Prinz, D. K.

    1973-01-01

    Photographs of the sun in predominantly L alpha radiation (centered at 1215.67 A) with 3-sec spatial resolution were taken from an Aerobee rocket shortly after fourth contact by the moon on the eclipse day of July 10, 1972. This preliminary reporting of the results describes the instrument and shows two of the photographs taken. The supergranulation is manifest, and active regions and filaments are well resolved over the entire disk. Densitometer traces across the disk are presented, giving the flux incident on the earth from active regions, cell boundaries, and filaments.

  20. Effects of PGF{sub 2{alpha}} on human melanocytes and regulation of the FP receptor by ultraviolet radiation

    SciTech Connect

    Scott, Glynis . E-mail: Glynis_Scott@urmc.rochester.edu; Jacobs, Stacey; Leopardi, Sonya; Anthony, Frank A.; Learn, Doug; Malaviya, Rama; Pentland, Alice

    2005-04-01

    Prostaglandins are potent lipid hormones that activate multiple signaling pathways resulting in regulation of cellular growth, differentiation, and apoptosis. In the skin, prostaglandins are rapidly released by keratinocytes following ultraviolet radiation and are chronically present in inflammatory skin lesions. We have shown previously that melanocytes, which provide photoprotection to keratinocytes through the production of melanin, express several receptors for prostaglandins, including the PGE{sub 2} receptors EP{sub 1} and EP{sub 3} and the PGF{sub 2{alpha}} receptor FP, and that PGF{sub 2{alpha}} stimulates melanocyte dendricity. We now show that PGF{sub 2{alpha}} stimulates the activity and expression of tyrosinase, the rate-limiting enzyme in melanin synthesis. Analysis of FP receptor regulation showed that the FP receptor is regulated by ultraviolet radiation in melanocytes in vitro and in human skin in vivo. We also show that ultraviolet irradiation stimulates production of PGF{sub 2{alpha}} by melanocytes. These results show that PGF{sub 2{alpha}} binding to the FP receptor activates signals that stimulate a differentiated phenotype (dendricity and pigmentation) in melanocytes. The regulation of the FP receptor and the stimulation of production of PGF{sub 2{alpha}} in melanocytes in response to ultraviolet radiation suggest that PGF{sub 2{alpha}} could act as an autocrine factor for melanocyte differentiation.

  1. Silicone rubber curing by high intensity infrared radiation

    SciTech Connect

    Huang, T.; Tsai, J.; Cherng, C.; Chen, J.

    1994-08-10

    A high-intensity (12 kW) and compact (80 cm) infrared heating oven for fast curing (12 seconds) of tube-like silicone rubber curing studies is reported. Quality inspection by DSC and DMA and results from pilot-scale curing oven all suggest that infrared heating provides a better way of vulcanization regarding to curing time, quality, cost, and spacing over conventional hot air heating. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  2. Cosmic Ray Intensity Variation in Lunar Radiation Environments during Luna and LRO missions

    NASA Astrophysics Data System (ADS)

    Sohn, Jongdae; Oh, Suyeon; Yi, Yu

    The RV-2N-series instruments onboard Luna missions and the CRaTER instrument onboard LRO satellite were designed to monitor in lunar radiation environment by measuring cosmic ray (CR) intensity. In order to examine the origins and the characteristics of the CR intensity variation in lunar radiation environment, we use proton intensity measured by RV-2N-series onboard Luna missions out of the Russian space Zond program for exploration of the Moon and CR intensity observed by the CRaTER on the Moon. We compare the CR intensity on the Moon with that observed by neutron monitors (Climax, McMurdo, Thule) on the Earth. To find the correlation between the solar activity and the CR intensity on the Moon, we also use the sunspot number supplied by NOAA National Geophysical Data Center. We present the result in this time.

  3. Differential Effects of Alpha-Particle Radiation and X-Irradiation on Genes Associated with Apoptosis

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Chen, Jeremy; Kutzner, Barbara; Wilkins, Ruth C.

    2011-01-01

    This study examined differential effects of alpha-(α-) particle radiation and X-rays on apoptosis and associated changes in gene expression. Human monocytic cells were exposed to α-particle radiation and X-rays from 0 to 1.5 Gy. Four days postexposure, cell death was measured by flow cytometry and 84 genes related to apoptosis were analyzed using real-time PCR. On average, 33% of the cells were apoptotic at 1.5 Gy of α-particle radiation. Transcript profiling showed statistical expression of 15 genes at all three doses tested. Cells exposed to X-rays were <5% apoptotic at ~1.5 Gy and induced less than a 2-fold expression in 6 apoptotic genes at the higher doses of radiation. Among these 6 genes, Fas and TNF-α were common to the α-irradiated cells. This data suggests that α-particle radiation initiates cell death by TNF-α and Fas activation and through intermediate signalling mediators that are distinct from X-irradiated cells. PMID:22091383

  4. Effect of alpha-lipoic acid on radiation-induced small intestine injury in mice

    PubMed Central

    Jeong, Bae Kwon; Song, Jin Ho; Jeong, Hojin; Choi, Hoon Sik; Jung, Jung Hwa; Hahm, Jong Ryeal; Woo, Seung Hoon; Jung, Myeong Hee; Choi, Bong-Hoi; Kim, Jin Hyun; Kang, Ki Mun

    2016-01-01

    Purpose Radiation therapy is a highly effective treatment for patients with solid tumors. However, it can cause damage and inflammation in normal tissues. Here, we investigated the effects of alpha-lipoic acid (ALA) as radioprotection agent for the small intestine in a mouse model. Materials and Methods Whole abdomen was evenly irradiated with total a dose of 15 Gy. Mice were treated with either ALA (100 mg/kg, intraperitoneal injection [i.p.]) or saline (equal volume, i.p.) the prior to radiation as 100 mg/kg/day for 3 days. Body weight, food intake, histopathology, and biochemical parameters were evaluated. Results Significant differences in body weight and food intake were observed between the radiation (RT) and ALA + RT groups. Moreover, the number of crypt cells was higher in the ALA + RT group. Inflammation was decreased and recovery time was shortened in the ALA + RT group compared with the RT group. The levels of inflammation-related factors (i.e., phosphorylated nuclear factor kappa B and matrix metalloproteinase-9) and mitogen-activated protein kinases were significantly decreased in the ALA + RT group compared with those in the RT group. Conclusions ALA treatment prior to radiation decreases the severity and duration of radiation-induced enteritis by reducing inflammation, oxidative stress, and cell death. PMID:26943777

  5. Effect of annealing treatment on K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition-metal alloys

    SciTech Connect

    Han, I.; Demir, L.

    2010-06-15

    The influence of heat annealing treatment on the K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition metal was carried out by x-ray fluorescence studies of various alloy compositions. K{beta}-to-K{alpha} x-ray intensity ratios of Fe, Ni, Ti, Co, and Cu in Fe{sub x}Ni{sub 1-x}, Ti{sub x}Ni{sub 1-x}, and Co{sub x}Cu{sub 1-x} alloys unannealed and thermally annealed at different temperatures have been measured following excitation by 22.69-keV x rays from a 10-mCi {sup 109}Cd radioactive point source. The experimental data obtained after annealing treatment indicate deviations of K{beta}-to-K{alpha} x-ray intensity ratios for 3d transition metals in different alloy compositions from the corresponding ratios for unannealed samples. The present investigation makes it possible to perform reliable interpretation of experimental K{beta}-to-K{alpha} x-ray intensity ratios for various 3d transition metals in their alloys and can also provide quantitative information about the changes of the K{beta}-to-K{alpha} x-ray intensity ratios of these metals with annealing treatment in considered systems.

  6. Means of Intensity Modulation of Radiation in External Radiotherapy

    NASA Astrophysics Data System (ADS)

    Bajusová, Alica; Králik, Gabriel; Miglierini, Marcel

    2010-01-01

    The paper deals with the main means of the beam intensity modifications that are used in radio therapeutic praxis. Physical principles and the main characteristics of the physical wedges and the enhanced dynamic wedges (EDW) are described. The main advantages and the disadvantages of the EDW over the conventional physical wedges are listed. The paper describes also a process of dosimetry verification of the application of the EDW that was applied on The Saint Elizabeth Cancer Institute in Bratislava and it details the experiment of the verification of an isodose distribution within this implementation of the EDW.

  7. Means of Intensity Modulation of Radiation in External Radiotherapy

    SciTech Connect

    Bajusova, Alica; Kralik, Gabriel; Miglierini, Marcel

    2010-01-05

    The paper deals with the main means of the beam intensity modifications that are used in radio therapeutic praxis. Physical principles and the main characteristics of the physical wedges and the enhanced dynamic wedges (EDW) are described. The main advantages and the disadvantages of the EDW over the conventional physical wedges are listed. The paper describes also a process of dosimetry verification of the application of the EDW that was applied on The Saint Elizabeth Cancer Institute in Bratislava and it details the experiment of the verification of an isodose distribution within this implementation of the EDW.

  8. Effect of long-term exposure to mobile phone radiation on alpha-Int1 gene sequence of Candida albicans

    PubMed Central

    Shahin-jafari, Ariyo; Bayat, Mansour; Shahhosseiny, Mohammad Hassan; Tajik, Parviz; Roudbar-mohammadi, Shahla

    2015-01-01

    Over the last decade, communication industries have witnessed a tremendous expansion, while, the biological effects of electromagnetic waves have not been fully elucidated. Current study aimed at evaluating the mutagenic effect of long-term exposure to 900-MHz radiation on alpha-Int1 gene sequences of Candida albicans. A standard 900 MHz radiation generator was used for radiation. 10 ml volumes from a stock suspension of C. albicans were transferred into 10 polystyrene tubes. Five tubes were exposed at 4 °C to a fixed magnitude of radiation with different time periods of 10, 70, 210, 350 and 490 h. The other 5 tubes were kept far enough from radiation. The samples underwent genomic DNA extraction. PCR amplification of alpha-Int1 gene sequence was done using one set of primers. PCR products were resolved using agarose gel electrophoresis and the nucleotide sequences were determined. All samples showed a clear electrophoretic band around 441 bp and further sequencing revealed the amplified DNA segments are related to alpha-Int1 gene of the yeast. No mutations in the gene were seen in radiation exposed samples. Long-term exposure of the yeast to mobile phone radiation under the above mentioned conditions had no mutagenic effect on alpha-Int1 gene sequence. PMID:27081370

  9. Effect of long-term exposure to mobile phone radiation on alpha-Int1 gene sequence of Candida albicans.

    PubMed

    Shahin-Jafari, Ariyo; Bayat, Mansour; Shahhosseiny, Mohammad Hassan; Tajik, Parviz; Roudbar-Mohammadi, Shahla

    2016-05-01

    Over the last decade, communication industries have witnessed a tremendous expansion, while, the biological effects of electromagnetic waves have not been fully elucidated. Current study aimed at evaluating the mutagenic effect of long-term exposure to 900-MHz radiation on alpha-Int1 gene sequences of Candida albicans. A standard 900 MHz radiation generator was used for radiation. 10 ml volumes from a stock suspension of C. albicans were transferred into 10 polystyrene tubes. Five tubes were exposed at 4 °C to a fixed magnitude of radiation with different time periods of 10, 70, 210, 350 and 490 h. The other 5 tubes were kept far enough from radiation. The samples underwent genomic DNA extraction. PCR amplification of alpha-Int1 gene sequence was done using one set of primers. PCR products were resolved using agarose gel electrophoresis and the nucleotide sequences were determined. All samples showed a clear electrophoretic band around 441 bp and further sequencing revealed the amplified DNA segments are related to alpha-Int1 gene of the yeast. No mutations in the gene were seen in radiation exposed samples. Long-term exposure of the yeast to mobile phone radiation under the above mentioned conditions had no mutagenic effect on alpha-Int1 gene sequence. PMID:27081370

  10. Terahertz radiation from a wire target irradiated by an ultra-intense laser pulse

    SciTech Connect

    Li Zhichao; Zheng Jian

    2007-05-15

    When an ultra-intense laser pulse impacts the tip of a wire whose other end is grounded, a strong return current can be driven along the wire because some energetic electrons generated in ultra-intense laser matter interaction can escape from the target and an electric field builds up. The wire then behaves like a current-carrying antenna that can emit electromagnetic radiations. If the duration of the driving pulse is several tens of femtoseconds, the radiation spectrum reaches a maximum at terahertz region, and the radiation power per solid angle could be as high as 10{sup 9} W/rad.

  11. Intense XUV radiation driven explosions of Xe clusters

    NASA Astrophysics Data System (ADS)

    Murphy, B.; Hoffmann, K.; Belolipetski, A.; Bernstein, A.; Keto, J.; Ditmire, T.; Artyukov, I.

    2008-04-01

    We have investigated the explosions of large xenon clusters subject to irradiation by high intensity extreme ultraviolet (XUV) light with wavelength near 38 nm. To do this we generated high order harmonics by focusing the output of the 20 TW, 40 fs, 800nm wavelength THOR laser into a jet of argon gas. To select a single harmonic we then employed a Sc/Si short focal length multilayer mirror optimized for the 21st harmonic at 38.1 nm at near normal incidence. This harmonic is focused onto a jet of xenon gas. We characterized the XUV focal spot by scanning a knife edge across an XUV photodiode and determined that our peak XUV intensity was 2x10^10 Wcm-2. Fast ion time-of-flight spectra reveal high ion charge states well above single photon ionization thresholds. These ions exhibit low kinetic energies consistent with hydrodynamic cluster expansion rather than Coulomb explosion. We also measured the electron spectra from these Xe cluster explosions and have observed moderate energy electrons ejected from the clusters.

  12. Detailed 8-transistor SRAM cell analysis for improved alpha particle radiation hardening in nanometer technologies

    NASA Astrophysics Data System (ADS)

    Bota, Sebastià A.; Torrens, Gabriel; Verd, Jaume; Segura, Jaume

    2015-09-01

    Eight-transistor (8T) cells were introduced to improve variability tolerance, cell stability and low-voltage operation in high-speed SRAM caches by decoupling the read and write design requirements. Altogether, 8T-SRAM can be designed without significant area penalty over 6T-SRAM. Ionizing radiation effects are nowadays a major concern for reliability and dependability of emerging electronic SRAM devices, even for sea-level applications. In this paper we demonstrate from experimental results that the 8T-SRAM also exhibits an enhanced overall intrinsic tolerance to alpha particle radiation even though its critical charge values are smaller than conventional 6T cells. We have experimentally found that the soft error rate measured in accelerated experiments with alpha particles in SRAM devices implemented in a 65 nm CMOS is 56% better for 8T cells with respect to standard 6T-cells. Even more, we show that this value can be increased up to a 200% through transistor sizing optimization.

  13. Development of a strongly focusing high-intensity He(+) ion source for a confined alpha particle measurement at ITER.

    PubMed

    Kisaki, M; Shinto, K; Kobuchi, T; Okamoto, A; Kitajima, S; Sasao, M; Tsumori, K; Nishiura, M; Kaneko, O; Matsuda, Y; Wada, M; Sakakita, H; Kiyama, S; Hirano, Y

    2008-02-01

    A strongly focusing high-intensity He(+) ion source has been designed and constructed as a beam source for a high-energy He(0) beam probe system for diagnosis of fusion produced alpha particles in the thermonuclear fusion plasmas. The He(+) beam was extracted from the ion source at an acceleration voltage of 18-35 kV. Temperature distributions of the beam target were observed with an IR camera. The 1/e-holding beam profile half-width was about 15 mm at optimum perveance (Perv) of 0.03 (I(beam)=2.4 A). A beam current about 3 A was achieved at an acceleration voltage of 26.7 kV with an arc power of 10 kW (Perv=0.023). PMID:18315239

  14. Temperature dependence of decay time and intensity of alpha pulses in pure and thallium-activated cesium iodide

    USGS Publications Warehouse

    Senftle, F.E.; Martinez, P.; Alekna, V.P.

    1962-01-01

    The intensity and decay time of Po210 ?? particle scintillations produced in pure and thallium-activated cesium iodide have been measured with a fast electronic system as a function of temperature down to 77??K. Three modes of decay due to alpha excitation have been observed for CsI(Tl), and two for CsI. Other than the 7- and 0.55-??sec modes (at room temperature) reported in the literature for CsI(Tl), an additional temperature-independent mode of about 1.3 ??sec has been detected between 77 and 150??K. In CsI a fast temperature-dependent mode of decay (???100 nsec) was observed between 100-200??K in addition to the known principal mode. ?? 1962 The American Institute of Physics.

  15. Synchronous flowering of the rubber tree (Hevea brasiliensis) induced by high solar radiation intensity.

    PubMed

    Yeang, Hoong-Yeet

    2007-01-01

    How tropical trees flower synchronously near the equator in the absence of significant day length variation or other meteorological cues has long been a puzzle. The rubber tree (Hevea brasiliensis) is used as a model to investigate this phenomenon. The annual cycle of solar radiation intensity is shown to correspond closely with the flowering of the rubber tree planted near the equator and in the subtropics. Unlike in temperate regions, where incoming solar radiation (insolation) is dependent on both day length and radiation intensity, insolation at the equator is due entirely to the latter. Insolation at the upper atmosphere peaks twice a year during the spring and autumn equinoxes, but the actual solar radiation that reaches the ground is attenuated to varying extents in different localities. The rubber tree shows one or two flowering seasons a year (with major and minor seasons in the latter) in accordance with the solar radiation intensity received. High solar radiation intensity, and in particular bright sunshine (as distinct from prolonged diffuse radiation), induces synchronous anthesis and blooming in Hevea around the time of the equinoxes. The same mechanism may be operational in other tropical tree species. PMID:17587376

  16. Response of two-phase droplets to intense electromagnetic radiation.

    PubMed

    Spann, J F; Maloney, D J; Lawson, W F; Casleton, K H

    1993-04-20

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii = 37, 55, and 80 microm) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid. PMID:20820360

  17. Response of two-phase droplets to intense electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-01-01

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

  18. X-radiation /E greater than 10 keV/, H-alpha and microwave emission during the impulsive phase of solar flares.

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.

    1972-01-01

    A study has been made of the variation in hard (E greater than 10 keV) X-radiation, H-alpha and microwave emission during the impulsive phase of solar flares. Analysis shows that the rise-time in the 20-30-keV X-ray spike depends on the electron hardness. The impulsive phase is also marked by an abrupt, very intense increase in H-alpha emission in one or more knots of the flare. Properties of these H-alpha kernels include: (1) a luminosity several times greater than the surrounding flare, (2) an intensity rise starting about 20-30 sec before, peaking about 20-25 sec after, and lasting about twice as long as the hard spike, (3) a location lower in the chromosphere than the remaining flare, (4) essentially no expansion prior to the hard spike, and (5) a position within 6000 km of the boundary separating polarities, usually forming on both sides of the neutral line near both feet of the same tube of force. Correspondingly, impulsive microwave events are characterized by: (1) great similarity in burst structure with 20-32 keV X-rays but only above 5000 MHz, (2) typical low frequency burst cutoff between 1400-3800 MHz, and (3) maximum emission above 7500 MHz.

  19. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  20. Interaction of intense vuv radiation with large xenon clusters

    SciTech Connect

    Walters, Zachary B.; Greene, Chris H.; Santra, Robin

    2006-10-15

    The interaction of atomic clusters with short, intense pulses of laser light to form extremely hot, dense plasmas has attracted extensive experimental and theoretical interest. The high density of atoms within the cluster greatly enhances the atom-laser interaction, while the finite size of the cluster prevents energy from escaping the interaction region. Recent technological advances have allowed experiments to probe the laser-cluster interaction at very high photon energies, with interactions much stronger than suggested by theories for lower photon energies. We present a model of the laser-cluster interaction that uses nonperturbative R-matrix techniques to calculate inverse bremsstrahlung and photoionization cross sections for Herman-Skillman atomic potentials. We describe the evolution of the cluster under the influence of the processes of inverse bremsstrahlung heating, photoionization, collisional ionization and recombination, and expansion of the cluster. We compare total energy absorbed with the Hamburg experiment of Wabnitz et al. [Nature 420, 482 (2002)] and ejected electron spectra with Laarmann et al. [Phys. Rev. Lett. 95, 063402 (2005)].

  1. Prevention and Treatment of Functional and Structural Radiation Injury in the Rat Heart by Pentoxifylline and Alpha-Tocopherol

    SciTech Connect

    Boerma, Marjan Roberto, Kerrey A.; Hauer-Jensen, Martin

    2008-09-01

    Purpose: Radiation-induced heart disease (RIHD) is a severe side effect of thoracic radiotherapy. This study examined the effects of pentoxifylline (PTX) and {alpha}-tocopherol on cardiac injury in a rat model of RIHD. Methods and Materials: Male Sprague-Dawley rats received fractionated local heart irradiation with a daily dose of 9 Gy for 5 days and were observed for 6 months after irradiation. Rats were treated with a combination of PTX, 100 mg/kg/day, and {alpha}-tocopherol (20 IU/kg/day) and received these compounds either from 1 week before until 6 months after irradiation or starting 3 months after irradiation, a time point at which histopathologic changes become apparent in our model of RIHD. Results: Radiation-induced increases in left ventricular diastolic pressure (in mm Hg: 35 {+-} 6 after sham-irradiation, 82 {+-} 11 after irradiation) were significantly reduced by PTX and {alpha}-tocopherol (early treatment: 48 {+-} 7; late treatment: 53 {+-} 6). PTX and {alpha}-tocopherol significantly reduced deposition of collagen types I (radiation only: 3.5 {+-} 0.2 {mu}m{sup 2} per 100 {mu}m{sup 2}; early treatment: 2.7 {+-} 0.8; late treatment: 2.2 {+-} 0.2) and III (radiation only: 13.9 {+-} 0.8; early treatment: 11.0 {+-} 1.2; late treatment: 10.6 {+-} 0.8). On the other hand, radiation-induced alterations in heart/body weight ratios, myocardial degeneration, left ventricular mast cell densities, and most echocardiographic parameters were not significantly altered by PTX and {alpha}-tocopherol. Conclusions: Treatment with PTX and {alpha}-tocopherol may have beneficial effects on radiation-induced myocardial fibrosis and left ventricular function, both when started before irradiation and when started later during the process of RIHD.

  2. Reverberation Chamber Uniformity Validation and Radiated Susceptibility Test Procedures for the NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Nguyen, Truong X.; Mielnik, John J.

    2010-01-01

    The NASA Langley Research Center's High Intensity Radiated Fields Laboratory has developed a capability based on the RTCA/DO-160F Section 20 guidelines for radiated electromagnetic susceptibility testing in reverberation chambers. Phase 1 of the test procedure utilizes mode-tuned stirrer techniques and E-field probe measurements to validate chamber uniformity, determines chamber loading effects, and defines a radiated susceptibility test process. The test procedure is segmented into numbered operations that are largely software controlled. This document is intended as a laboratory test reference and includes diagrams of test setups, equipment lists, as well as test results and analysis. Phase 2 of development is discussed.

  3. Cooling of relativistic electron beams in intense laser pulses: Chirps and radiation

    NASA Astrophysics Data System (ADS)

    Yoffe, S. R.; Noble, A.; Macleod, A. J.; Jaroszynski, D. A.

    2016-09-01

    Next-generation high-power laser facilities (such as the Extreme Light Infrastructure) will provide unprecedented field intensities, and will allow us to probe qualitatively new physical regimes for the first time. One of the important fundamental questions which will be addressed is particle dynamics when radiation reaction and quantum effects play a significant role. Classical theories of radiation reaction predict beam cooling in the interaction of a relativistic electron bunch and a high-intensity laser pulse, with final-state properties only dependent on the laser fluence. The observed quantum suppression of this cooling instead exhibits a dependence on the laser intensity directly. This offers the potential for final-state properties to be modified or even controlled by tailoring the intensity profile of the laser pulse. In addition to beam properties, quantum effects will be manifest in the emitted radiation spectra, which could be manipulated for use as radiation sources. We compare predictions made by classical, quasi-classical and stochastic theories of radiation reaction, and investigate the influence of chirped laser pulses on the observed radiation spectra.

  4. Growth and Characterization of alpha-PbO for Room Temperature Radiation Detection

    NASA Astrophysics Data System (ADS)

    Ford, Erin Leigh

    A global trading structure and high throughput of shipping containers into ports around the world increases the chance of nuclear terrorism via cargo containers. Harmless radioactive sources confuse and impede detection of the materials that pose a real threat, making spectroscopy difficult and requiring detectors with high resolution. The current methods that are used to check containers in ports have security flaws, and only 5% of all shipping containers are checked. The development of semiconductor gamma-ray detectors is one of the protocols being advanced to alleviate this risk because they can function at room temperature and they are cost effective, easily produced, and have high resolution. This dissertation has addressed the current lack of "perfect" room temperature detector materials by investigating alpha-PbO, a novel material in this field. This includes the development of a growth process for alpha-PbO thin films, as well as its structural and performance characterization as a detector material. Because we intend alpha-PbO to be a photoconductive detector, it should have certain properties. A photoconductive detector consists of a highly resistive material with a voltage bias across it. It absorbs incident gamma-rays, creating electron-hole pairs that provide a signal. To function well, it must have a high atomic number and a high density in order to absorb high-energy photons via the photoelectric effect. It should also have a large resistivity and a wide band gap to avoid large leakage currents at room temperature. Finally, it must have good charge carrier transport properties and detector resolution in order to be able to determine the characteristic energy peaks of the radiation-emitting source. We chose alpha-PbO because it has a very high Z and a very high density and a band gap in the correct range. It also has a rich history of use as a photoconductor that reaches back to the 1950s. Numerous methods have been used to grow thin films of alpha

  5. Intensive Care Nurses’ Knowledge of Radiation Safety and Their Behaviors Towards Portable Radiological Examinations

    PubMed Central

    Dianati, Mansoor; Zaheri, Azita; Talari, Hamid Reza; Deris, Fateme; Rezaei, Sara

    2014-01-01

    Background: Radiological examinations for patients who are hospitalized at intensive care units are usually performed using portable radiography devices. However they may require knowledge and safety precautions of nurses. Objectives: The aim of the study was to investigate ICU nurses’ knowledge of radiation safety and their behaviors towards portable radiological examinations. Materials and Methods: In total, 44 intensive care nurses were recruited for this cross-sectional descriptive study using census sampling during April and May 2014. The study setting was at intensive care units of Shahid Beheshti Hospital of Kashan, Iran. An eleven-item questionnaire and a five-item checklist were used for evaluating nurses’ radiation protection knowledge and behaviors, respectively. An expert panel consisting of ten nursing and radiology faculty members confirmed the content validity of the questionnaire and the checklist. Moreover, a Geiger-Müller counter was used for measuring ionizing radiation during portable radiological examinations. Study data were analyzed using the SPSS software version 13.0. Mean, standard deviation, frequency and one-sample t test were used for description of the data. The level of significance was set at below 0.05. Results: The mean of participants’ radiation protection knowledge was 4.77 ± 1.38. The most prevalent radiation protection behavior of nurses was leaving the intensive care unit during portable radiological examinations. Only 6.8% of nurses stayed at the nursing station during radiological examinations. The highest dose of radiation was 0.11 micro Sievert per hour (μSv/h), which was much lower than the highest permitted level of radiation exposure i.e. 0.25 μSv/h. Conclusions: Portable radiological examinations did not expose healthcare providers to high doses of ionizing radiation. Nurses’ radiation protection knowledge was limited and hence, they require in-service education programs. PMID:25741515

  6. Alpha-tocopherol succinate- and AMD3100-mobilized progenitors mitigate radiation combined injury in mice

    PubMed Central

    Singh, Vijay K.; Wise, Stephen Y.; Fatanmi, Oluseyi O.; Beattie, Lindsay A.; Ducey, Elizabeth J.; Seed, Thomas M.

    2014-01-01

    The purpose of this study was to elucidate the role of alpha-tocopherol succinate (TS)- and AMD3100-mobilized progenitors in mitigating combined injury associated with acute radiation exposure in combination with secondary physical wounding. CD2F1 mice were exposed to high doses of cobalt-60 gamma-radiation and then transfused intravenously with 5 million peripheral blood mononuclear cells (PBMCs) from TS- and AMD3100-injected mice after irradiation. Within 1 h after irradiation, mice were exposed to secondary wounding. Mice were observed for 30 d after irradiation and cytokine analysis was conducted by multiplex Luminex assay at various time-points after irradiation and wounding. Our results initially demonstrated that transfusion of TS-mobilized progenitors from normal mice enhanced survival of acutely irradiated mice exposed 24 h prior to transfusion to supralethal doses (11.5–12.5 Gy) of 60Co gamma-radiation. Subsequently, comparable transfusions of TS-mobilized progenitors were shown to significantly mitigate severe combined injuries in acutely irradiated mice. TS administered 24 h before irradiation was able to protect mice against combined injury as well. Cytokine results demonstrated that wounding modulates irradiation-induced cytokines. This study further supports the conclusion that the infusion of TS-mobilized progenitor-containing PBMCs acts as a bridging therapy in radiation-combined-injury mice. We suggest that this novel bridging therapeutic approach involving the infusion of TS-mobilized hematopoietic progenitors following acute radiation exposure or combined injury might be applicable to humans. PMID:23814114

  7. Radiation-induced cationic polymerization of limonene oxide,. cap alpha. -pinene oxide, and. beta. -pinene oxide

    SciTech Connect

    Aikins, J.A.; Williams, F.

    1984-01-01

    After suitable drying, the subject monomers in the form of neat liquids undergo radiation-induced polymerization with no apparent side reactions and high conversions to precipitatable polymers of low molecular weight. A cationic mechanism is evidenced by the strongly retarding effect of tri-n-propylamine on the polymerization rate. At 25/sup 0/C, limonene oxide gives the highest polymerization rates, an average conversion of 36% per Mrad being obtained in comparison with values of 5.7 and 7.3% per Mrad for the ..cap alpha..-pinene and ..beta..-pinene oxides, respectively. Similarly, the average anti DP/sub n/ decreases from 11.8 for the limonene oxide polymer to 5.6 and 4.0 for the ..cap alpha..-pinene oxide and ..beta..-pinene oxide polymers, respectively. A high frequency of chain transfer to monomer is indicated in each case by the fact that the kinetic chain lengths are estimated to be on the order of a hundred times larger than the anti DP/sub n/ values. Structural characterization of the limonene oxide polymer by /sup 1/H and /sup 13/C NMR spectroscopy provides conclusive evidence that the polymerization proceeds by the opening of the epoxide ring to yield a 1,2-trans polyether. Similar NMR studies on the polymers formed from the ..cap alpha..-pinene and ..beta..-pinene oxides show that in the polymerization of these monomers, the opening of the epoxide ring is generally accompanied by the concomitant ring opening of the cyclobutane ring structure to yield a gem-dimethyl group in the main chain. The detection of isopropenyl end groups in the pinene oxide polymers is also consistent with this mode of propagation being followed by chain (proton) transfer to monomer.

  8. SU-E-J-267: Change in Mean CT Intensity of Lung Tumors During Radiation Treatment

    SciTech Connect

    Mahon, R; Tennyson, N; Weiss, E; Hugo, G

    2015-06-15

    Purpose: To evaluate CT intensity change of lung tumors during radiation therapy. Methods: Repeated 4D CT images were acquired on a CT simulator during the course of therapy for 27 lung cancer patients on IRB approved protocols. All subjects received definitive radiation treatment ± chemotherapy. CT scans were completed prior to treatment, and 2–7 times during the treatment course. Primary tumor was delineated by an experienced Radiation Oncologist. Contours were thresholded between −100 HU and 200 HU to remove airways and bone. Correlations between the change in the mean tumor intensity and initial tumor intensity, SUVmax, and tumor volume change rate were investigated. Reproducibility was assessed by evaluating the variation in mean intensity over all phases in 4DCT, for a subgroup of 19 subjects. Results: Reproducibility of tumor intensity between phases as characterized by the root mean square of standard deviation across 19 subjects was 1.8 HU. Subjects had a mean initial tumor intensity of 16.5 ± 11.6 HU and an overall reduction in HU by 10.3 ± 8.5 HU. Evaluation of the changes in tumor intensity during treatment showed a decrease of 0.3 ± 0.3 HU/day for all subjects, except three. No significant correlation was found between change in HU/day and initial HU intensity (p=0.53), initial PET SUVmax (p=0.69), or initial tumor volume (p=0.70). The rate of tumor volume change was weakly correlated (R{sup 2}=0.05) with HU change (p=0.01). Conclusion: Most lung cancer subjects showed a marked trend of decreasing mean tumor CT intensity throughout radiotherapy, including early in the treatment course. Change in HU/day is not correlated with other potential early predictors for response, such as SUV and tumor volume change. This Result supports future studies to evaluate change in tumor intensity on CT as an early predictor of response.

  9. Behavior of uranium oxides and oxyfluorides exposed to moisture and Cm-244 alpha radiation

    NASA Astrophysics Data System (ADS)

    Icenhour, A. S.; Toth, L. M.

    2004-05-01

    Alpha radiolysis studies have been performed on uranium oxides and oxyfluorides (UO3, U3O8, and UO2F2) to evaluate the long-term storage characteristics of U-233. These uranium compounds (using U-238 as the surrogate for U-233) were subjected to relatively high alpha radiation doses (235-634 MGy) by doping with Cm-244. The typical irradiation time for these samples was about 1.5 years, which would be equivalent to more than 50 years irradiation by a U-233 sample. Both dry and wet (up to 10 wt% water) samples were examined in an effort to identify the gas pressure and composition changes that occurred as a result of radiolysis. This study shows that several competing reactions occur during radiolysis with the net effect of generating only very low pressures of hydrogen, nitrogen, and carbon dioxide from water, nitrate, and carbon impurities, respectively. In the absence of nitrate impurities, no pressures greater than 1000 Torr are generated. Usually, however, the oxygen in the air atmosphere over the oxides is consumed with the corresponding oxidation of the uranium oxide. In the presence of up to 10 wt% water, the oxides first show a small pressure rise followed by a net decrease due to the oxygen consumption and the attainment of a steady-state pressure at which the rate of generation of gaseous components is balanced by their recombination and/or consumption in the oxide phase.

  10. Scaling of Ion Acceleration in Super Intense Laser Matter Interaction in Radiative Damping Regime

    NASA Astrophysics Data System (ADS)

    Pandit, Rishi; Sentoku, Yasuhiko; Ackad, Edward

    2015-11-01

    We had derived the radiation reaction terms including the higher orders and implemented in PICLS codes [R. Pandit and Y. Sentoku, Phys. Plasmas 19, 073304 (2012)]. It was found that higher order terms of radiation reaction reduce the ponderomotive force as well as the photon pressure. The ponderomotive scaling, in super intense laser matter interactions, changes due to the decrease of the ponderomotive force on the electron and ion's accelerations. A new scaling of ion acceleration has been derived which depends on the laser intensity and oscillatory energy of electron. At 1023 W/cm2 almost half of the ponderomotive force is damped due to higher order terms. We will show how the theoretical result compares with PICLS simulations by varying laser intensities to understand the effect of the reduced ponderomotive force in super intense laser matter interaction.

  11. Scintillator assembly for alpha radiation detection and method of making the assembly

    DOEpatents

    McElhaney, Stephanie A.; Bauer, Martin L.; Chiles, Marion M.

    1992-01-01

    A scintillator assembly for use in the detection of alpha radiation includes a body of optically-transparent epoxy and an amount of phosphor particles embedded within the body adjacent one surface thereof. When making the body, the phosphor particles are mixed with the epoxy when in an uncured condition and permitted to settle to the bottom surface of a mold within which the epoxy/phosphor mixture is contained. When the mixture subsequently cures to form a hardened body, the one surface of the body which cured against the bottom surface of the mold is coated with a thin layer of opaque material for preventing ambient light form entering the body through the one surface. The layer of opaque material is thereafter coated with a layer of protective material to provide the assembly with a damage-resistant entrance window.

  12. Nonadiabatic behavior of the polarization of electric-field-induced Lyman-. alpha. radiation

    SciTech Connect

    Plotzke, O.; Wille, U.; Hippler, R.; Lutz, H.O. Bereich Schwerionenphysik, Hahn-Meitner-Institut Berlin, Berlin )

    1990-12-10

    The linear polarization of Lyman-{alpha} radiation emitted when hydrogen atoms in the metastable 2{ital s}{sub 1/2} state traverse an external electric field is studied as a function of the effective rise time of the field for field strengths extending from very small values up to 6 keV/cm. With decreasing rise time, the measured polarization exhibits a transition from {ital adiabatic} to {ital sudden} behavior. The transition region is centered at a rise time which is approximately equal to the characteristic time associated with the 2{ital s}{sub 1/2-}2{ital p}{sub 1/2} Lamb splitting in the unperturbed hydrogen system. The experimental data are well described by the results of a time-dependent theory.

  13. Scintillator assembly for alpha radiation detection and method of making the assembly

    DOEpatents

    McElhaney, S.A.; Bauer, M.L.; Chiles, M.M.

    1992-09-22

    A scintillator assembly for use in the detection of alpha radiation includes a body of optically-transparent epoxy and an amount of phosphor particles embedded within the body adjacent one surface thereof. When making the body, the phosphor particles are mixed with the epoxy when in an uncured condition and permitted to settle to the bottom surface of a mold within which the epoxy/phosphor mixture is contained. When the mixture subsequently cures to form a hardened body, the one surface of the body which cured against the bottom surface of the mold is coated with a thin layer of opaque material for preventing ambient light form entering the body through the one surface. The layer of opaque material is thereafter coated with a layer of protective material to provide the assembly with a damage-resistant entrance window. 6 figs.

  14. Mitigation of radiation nephropathy after internal {alpha}-particle irradiation of kidneys

    SciTech Connect

    Jaggi, Jaspreet Singh; Seshan, Surya V.; McDevitt, Michael R.; Sgouros, George; Hyjek, Elizabeth; Scheinberg, David A. . E-mail: d-scheinberg@ski.mskcc.org

    2006-04-01

    Purpose: Internal irradiation of kidneys as a consequence of radioimmunotherapy, radiation accidents, or nuclear terrorism can result in radiation nephropathy. We attempted to modify pharmacologically, the functional and morphologic changes in mouse kidneys after injection with the actinium ({sup 225}Ac) nanogenerator, an in vivo generator of {alpha}- and {beta}-particle emitting elements. Methods and Materials: The animals were injected with 0.35 {mu}Ci of the {sup 225}Ac nanogenerator, which delivers a dose of 27.6 Gy to the kidneys. Then, they were randomized to receive captopril (angiotensin-converting enzyme inhibitor), L-158,809 (angiotensin II receptor-1 blocker), spironolactone (aldosterone receptor antagonist), or a placebo. Results: Forty weeks after the {sup 225}Ac injection, the placebo-control mice showed a significant increase in blood urea nitrogen (BUN) (87.6 {+-} 6.9 mg/dL), dilated Bowman spaces, and tubulolysis with basement membrane thickening. Captopril treatment accentuated the functional (BUN 119.0 {+-} 4.0 mg/dL; p <0.01 vs. placebo controls) and histopathologic damage. In contrast, L-158,809 offered moderate protection (BUN 66.6 {+-} 3.9 mg/dL; p = 0.02 vs. placebo controls). Spironolactone treatment, however, significantly prevented the development of histopathologic and functional changes (BUN 31.2 {+-} 2.5 mg/dL; p <0.001 vs. placebo controls). Conclusions: Low-dose spironolactone and, to a lesser extent, angiotensin receptor-1 blockade can offer renal protection in a mouse model of internal {alpha}-particle irradiation.

  15. Characteristics of a high-intensity plasma flash x-ray generator having a double-target radiation tube

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Sagae, Michiaki; Takahashi, Kei; Oizumi, Teiji; Hayasi, Yasuomi; Tamakawa, Yoshiharu; Yanagisawa, Toru

    1995-05-01

    The radiographic characteristics of a high-intensity plasma flash x-ray generator having a solid-target (anode) radiation tube are described. This generator consisted of the following essential components; a high- voltage power supply, a low-impedance coaxial transmission line, a coaxial oil condenser of 0.2 (mu) F, a turbo-molecular pump, a thyratron pulser as a trigger device, and a flash x-ray triode having a rod-shaped long double anode; a 2.0 mm inner tungsten anode was embedded in 3.0 mm copper anode. The high-voltage condenser was charged from 40 to 60 kV by the power supply, and the electric charges in the condenser were discharged to the tube after triggering the cathode electrode. The maximum tube voltage was equivalent to the charged voltage of the main condenser, and the voltage decreased after the triggering. Both the tube voltage and the current displayed damped oscillations, and the maximum tube current was less than 20 kA. The pulse height of the flash x rays substantially increased according to increases in the charged voltage, and the x-ray durations had values of a few microseconds. The plasma x- ray source substantially grew when the charged voltage was increased. The flash x-ray spectra from the plasma x-ray source were measured by a transmission-type spectrometer having a LiF curved crystal of 0.5 mm in thickness. Compared to the intensities of copper K(alpha) 1 and K(alpha) 2 including nondiagram lines increased by using the double target.

  16. SU-C-303-02: Correlating Metabolic Response to Radiation Therapy with HIF-1alpha Expression

    SciTech Connect

    Campos, D; Peeters, W; Nickel, K; Eliceiri, K; Kimple, R; Van Der Kogel, A; Kissick, M

    2015-06-15

    Purpose: To understand radiation induced alterations in cellular metabolism which could be used to assess treatment or normal tissue response to aid in patient-specific adaptive radiotherapy. This work aims to compare the metabolic response of two head and neck cell lines, one malignant (UM-SCC-22B) and one benign (Normal Oral Keratinocyte), to ionizing radiation. Responses are compared to alterations in HIF-1alpha expression. These dynamics can potentially serve as biomarkers in assessing treatment response allowing for patient-specific adaptive radiotherapy. Methods: Measurements of metabolism and HIF-1alpha expression were taken before and X minutes after a 10 Gy dose of radiation delivered via an orthovoltage x-ray source. In vitro changes in metabolic activity were measured via fluorescence lifetime imaging (FLIM) to assess the mean lifetime of NADH autofluorescence following a dose of 10 Gy. HIF-1alpha expression was measured via immunohistochemical staining of in vitro treated cells and expression was quantified using the FIJI software package. Results: FLIM demonstrated a decrease in the mean fluorescence lifetime of NADH by 100 ps following 10 Gy indicating a shift towards glycolytic pathways for malignant cells; whereas this benign cell line showed little change in metabolic signature. Immunohistochemical analysis showed significant changes in HIF-1alpha expression in response to 10 Gy of radiation that correlate to metabolic profiles. Conclusion: Radiation induces significant changes in metabolic activity and HIF-1alpha expression. These alterations occur on time scales approximating the duration of common radiation treatments (approximately tens of minutes). Further understanding these dynamics has important implications with regard to improvement of therapy and biomarkers of treatment response.

  17. Thermal conditions on the International Space Station: Effects of operations of the station Main Radiators on the Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Xie, Min; Burger, Joseph

    2016-04-01

    A thermal model of the Alpha Magnetic Spectrometer on the International Space Station (ISS) has been developed, and Thermal Desktop® (with RadCAD®) and SINDA/FLUINT software have been used to calculate the effects of the operations of the ISS Main Radiators on AMS temperatures. We find that the ISS Starboard Main Radiator has significant influence on temperatures on the port side of AMS. The simulation results are used in AMS thermal control operations.

  18. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Progress report, July 1990--June 1992

    SciTech Connect

    Zaider, M.

    1992-12-31

    We report on a theory for describing the biological effects of ionizing radiation in particular radon {alpha} particles. Behind this approach is the recognition that biological effects such as chromosome aberrations, cellular transformation, cellular inactivation, etc, are the result of a hierarchic sequence of radiation effects. We indicate how to treat each of the individual processes in this sequence, and also how to relate one effect to the hierarchically superior one.

  19. The Lyman alpha coronagraph

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.; Reeves, E. M.; Kirkham, B.

    1977-01-01

    The rocket-borne Lyman alpha coronagraph (RLAC) is to be used in the absence of a natural solar eclipse to determine coronal temperatures from measurements of the line width of Lyman-alpha and to determine neutral hydrogen densities of coronal material from the absolute intensity. The coronagraph consists of a 75-cm Fastie-Ebert scanning spectrometer with an AMR 641 photoelectric detection system, an off-axis parabolic primary mirror, and an occulting system. A special optical arrangement achieves rejection of radiation from the solar disk.

  20. Transverse beam shape measurements of intense proton beams using optical transition radiation

    SciTech Connect

    Scarpine, Victor E.; /Fermilab

    2012-03-01

    A number of particle physics experiments are being proposed as part of the Department of Energy HEP Intensity Frontier. Many of these experiments will utilize megawatt level proton beams onto targets to form secondary beams of muons, kaons and neutrinos. These experiments require transverse size measurements of the incident proton beam onto target for each beam spill. Because of the high power levels, most beam intercepting profiling techniques will not work at full beam intensity. The possibility of utilizing optical transition radiation (OTR) for high intensity proton beam profiling is discussed. In addition, previous measurements of OTR beam profiles from the NuMI beamline are presented.

  1. In vitro study of cell survival following dynamic MLC intensity-modulated radiation therapy dose delivery

    SciTech Connect

    Moiseenko, Vitali; Duzenli, Cheryl; Durand, Ralph E.

    2007-04-15

    The possibility of reduced cell kill following intensity-modulated radiation therapy (IMRT) compared to conventional radiation therapy has been debated in the literature. This potential reduction in cell kill relates to prolonged treatment times typical of IMRT dose delivery and consequently increased repair of sublethal lesions. While there is some theoretical support to this reduction in cell kill published in the literature, direct experimental evidence specific to IMRT dose delivery patterns is lacking. In this study we present cell survival data for three cell lines: Chinese hamster V79 fibroblasts, human cervical carcinoma, SiHa and colon adenocarcinoma, WiDr. Cell survival was obtained for 2.1 Gy delivered as acute dose with parallel-opposed pair (POP), irradiation time 75 s, which served as a reference; regular seven-field IMRT, irradiation time 5 min; and IMRT with a break for multiple leaf collimator (MLC) re-initialization after three fields were delivered, irradiation time 10 min. An actual seven-field dynamic MLC IMRT plan for a head and neck patient was used. The IMRT plan was generated for a Varian EX or iX linear accelerator with 120 leaf Millenium MLC. Survival data were also collected for doses 1x, 2x, 3x, 4x, and 5x 2.1 Gy to establish parameters of the linear-quadratic equation describing survival following acute dose delivery. Cells were irradiated inside an acrylic cylindrical phantom specifically designed for this study. Doses from both IMRT and POP were validated using ion chamber measurements. A reproducible increase in cell survival was observed following IMRT dose delivery. This increase varied from small for V79, with a surviving fraction of 0.8326 following POP vs 0.8420 following uninterrupted IMRT, to very pronounced for SiHa, with a surviving fraction of 0.3903 following POP vs 0.5330 for uninterrupted IMRT. When compared to IMRT or IMRT with a break for MLC initialization, cell survival following acute dose delivery was

  2. Primary radiation damage of protein crystals by an intense synchrotron X-ray beam.

    PubMed

    Teng, T Y; Moffat, K

    2000-09-01

    X-ray radiation damage of a lysozyme single crystal by an intense monochromatic beam from a third-generation radiation source at the Advanced Photon Source has been studied. The results show that primary radiation damage is linearly dependent on the X-ray dose even when the crystal is at cryogenic temperatures. The existence of an upper limit for the primary radiation damage was observed. Above the threshold of approximately 1 x 10(7) Gy, excessive damage of the crystal develops which is interpreted as the onset of secondary and/or tertiary radiation damage. This upper limit of X-ray dose is compared with Henderson's limit [Henderson (1990). Proc. R. Soc. London, B241, 6-8], and its implication for the amount of useful X-ray diffraction data that can be obtained for crystals of a given scattering power is also discussed. PMID:16609214

  3. High-intensity coherent FIR radiation from sub-picosecond electron bunches

    SciTech Connect

    Kung, P.H.; Lihn, Hung-chi; Wiedemann, H.; Bocek, D.

    1994-01-01

    A facility to generate high-intensity, ultra-short pulses of broad-band far-infrared radiation has been assembled and tested at Stanford. The device uses sub-picosecond relativistic electron bunches to generate coherent radiation through transition or synchrotron radiation in the far-infrared (FIR) regime between millimeter waves and wavelengths of about 100 {mu}m and less. Experimental results show a peak radiation power of greater than 0.33 MW within a micro-bunch and an average FIR radiation power of 4 mW. The average bunch length of 2856 micro-bunches within a 1 {mu}sec macro-pulse is estimated to be about 480 sec. Simulations experimental setup and results will be discussed.

  4. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General §...

  5. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General §...

  6. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General §...

  7. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General §...

  8. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General §...

  9. Evaluation of a low-intensity ultraviolet-C radiation device for decontamination of computer keyboards.

    PubMed

    Shaikh, Aaron A; Ely, Dylan; Cadnum, Jennifer L; Koganti, Sreelatha; Alhmidi, Heba; Sankar C, Thriveen; Jencson, Annette L; Kundrapu, Sirisha; Donskey, Curtis J

    2016-06-01

    Computer keyboards are a potential source for dissemination of pathogenic microorganisms. We demonstrated that a low-intensity ultraviolet-C (UV-C) radiation device was effective in reducing methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and Clostridium difficile spores on steel carriers and significantly reduced bacterial counts on in-use keyboards. PMID:26781219

  10. Quantum mechanical theory of collisional ionization in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    Bellum, J. C.; George, T. F.

    1978-01-01

    The paper presents a quantum mechanical formalism for treating ionizing collisions occurring in the presence of an intense laser field. Both the intense laser radiation and the internal electronic continuum states associated with the emitted electrons are rigorously taken into account by combining discretization techniques with expansions in terms of electronic-field representations for the quasi-molecule-plus-photon system. The procedure leads to a coupled-channel description of the heavy-particle dynamics which involves effective electronic-field potential surfaces and continua. It is suggested that laser-influenced ionizing collisions can be studied to verify the effects of intense laser radiation on inelastic collisional processes. Calculation procedures for electronic transition dipole matrix elements between discrete and continuum electronic states are outlined.

  11. Thermal conditions on the International Space Station: Heat flux and temperature investigation of main radiators for the Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Xie, Min; Gao, Jianmin; Wu, Shaohua; Qin, Yukun

    2016-09-01

    The investigation on heat flux can clarify the thermal condition and explain temperature behavior on the main radiators of the Alpha Magnetic Spectrometer (AMS). In this paper, a detailed investigation of heat flux on the AMS main radiators is proposed. The heat transfer process of the AMS main radiators is theoretically analyzed. An updated thermal model of the AMS on the International Space Station (ISS) is developed to calculate the external heat flux density on the AMS main radiators. We conclude the ISS components and operations affect on the solar flux density of the AMS main radiators by reflecting or shading solar illumination. According to the energy conservation on the AMS main radiators, the temperature variation mainly depends on the solar flux change. The investigations are conducive to reference for the long-duration thermal control of the AMS, and knowledge for the thermal conditions on the ISS.

  12. Radiation Dose Measurement for High-Intensity Laser Interactions with Solid Targets at SLAC

    SciTech Connect

    Liang, Taiee

    2015-09-25

    A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. We found that these laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source’s (LCLS) Matter in Extreme Conditions (MEC) facility. Additionally, radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 1018 to 7.1x1019 W/cm2 are presented.

  13. Four-Week Course of Radiation for Breast Cancer Using Hypofractionated Intensity Modulated Radiation Therapy With an Incorporated Boost

    SciTech Connect

    Freedman, Gary M. . E-mail: Gary.Freedman@FCCC.edu; Anderson, Penny R.; Goldstein, Lori J.; Ma Changming; Li Jinsheng; Swaby, Ramona F.; Litwin, Samuel; Watkins-Bruner, Deborah; Sigurdson, Elin R.; Morrow, Monica

    2007-06-01

    Purpose: Standard radiation for early breast cancer requires daily treatment for 6 to 7 weeks. This is an inconvenience to many women, and for some a barrier for breast conservation. We present the acute toxicity of a 4-week course of hypofractionated radiation. Methods and Materials: A total of 75 patients completed radiation on a Phase II trial approved by the hospital institutional review board. Eligibility criteria were broad to include any patient normally eligible for standard radiation: age {>=}18 years, invasive or in situ cancer, American Joint Committee on Cancer Stage 0 to II, breast-conserving surgery, and any systemic therapy not given concurrently. The median age was 52 years (range, 31-81 years). Of the patients, 15% had ductal carcinoma in situ, 67% T1, and 19% T2; 71% were N0, 17% N1, and 12% NX. Chemotherapy was given before radiation in 44%. Using photon intensity-modulated radiation therapy and incorporated electron beam boost, the whole breast received 45 Gy and the lumpectomy bed 56 Gy in 20 treatments over 4 weeks. Results: The maximum acute skin toxicity by the end of treatment was Grade 0 in 9 patients (12%), Grade 1 in 49 (65%) and Grade 2 in 17 (23%). There was no Grade 3 or higher skin toxicity. After radiation, all Grade 2 toxicity had resolved by 6 weeks. Hematologic toxicity was Grade 0 in most patients except for Grade 1 neutropenia in 2 patients, and Grade 1 anemia in 11 patients. There were no significant differences in baseline vs. 6-week posttreatment patient-reported or physician-reported cosmetic scores. Conclusions: This 4-week course of postoperative radiation using intensity-modulated radiation therapy is feasible and is associated with acceptable acute skin toxicity and quality of life. Long-term follow-up data are needed. This radiation schedule may represent an alternative both to longer 6-week to 7-week standard whole-breast radiation and more radically shortened 1-week, partial-breast treatment schedules.

  14. Calculation of the Electronic Parameters of an Al/DNA/p-Si Schottky Barrier Diode Influenced by Alpha Radiation

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2015-01-01

    Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al)/DNA/silicon (Si) rectifying junctions using their current-voltage (I-V) characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0) was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889–1.423 Ω for 2–8 min). These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors. PMID:25730484

  15. Calculation of the electronic parameters of an Al/DNA/p-Si Schottky barrier diode influenced by alpha radiation.

    PubMed

    Al-Ta'ii, Hassan Maktuff Jaber; Mohd Amin, Yusoff; Periasamy, Vengadesh

    2015-01-01

    Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al)/DNA/silicon (Si) rectifying junctions using their current-voltage (I-V) characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0) was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889-1.423 Ω for 2-8 min). These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors. PMID:25730484

  16. Breast Intensity-Modulated Radiation Therapy Reduces Time Spent With Acute Dermatitis for Women of All Breast Sizes During Radiation

    SciTech Connect

    Freedman, Gary M. Li Tianyu; Nicolaou, Nicos; Chen Yan; Ma, Charlie C.-M.; Anderson, Penny R.

    2009-07-01

    Purpose: To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT). Methods and Materials: The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment. Results: The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts. Conclusions: Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

  17. Predictive factors for acute radiation pneumonitis in postoperative intensity modulated radiation therapy and volumetric modulated arc therapy of esophageal cancer

    PubMed Central

    Zhao, Yaqin; Chen, Lu; Zhang, Shu; Wu, Qiang; Jiang, Xiaoqin; Zhu, Hong; Wang, Jin; Li, Zhiping; Xu, Yong; Zhang, Ying Jie; Bai, Sen; Xu, Feng

    2015-01-01

    Background Radiation pneumonitis (RP) is a common side reaction in radiotherapy for esophageal cancer. There are few reports about RP in esophageal cancer patients receiving postoperative intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). This study aims to analyze clinical or dosimetric factors associated with RP, and provides data for radiotherapy planning. Methods We reviewed 68 postoperative esophageal cancer patients who were treated with radiotherapy at the West China Hospital from October 2010 to November 2012 to identify any correlation between the clinical or dosimetric parameters and acute radiation pneumonitis (ARP) or severe acute radiation pneumonitis (SARP) by t-test, chi-square test, and logistic regression analysis. Results Of the 68 patients, 33 patients (48.5%) developed ARP, 13 of which (19.1%) developed SARP. Of these 33 patients, 8 (11.8%), 12 (17.6%), 11 (16.2%), and 2 (2.9%) patients were grade 1, 2, 3, and 4 ARP, respectively. Univariate analysis showed that lung infection during radiotherapy, use of VMAT, mean lung dose (MLD), and dosimetric parameters (e.g. V20, V30) are significantly correlated with RP. Multivariate analysis found that lung infection during radiotherapy, MLD ≥ 12 Gy, and V30 ≥ 13% are significantly correlated with an increased risk of RP. Conclusion Lung infection during radiotherapy and low radiation dose volume distribution were predictive factors associated with RP and should be accounted for during radiation planning. PMID:26273335

  18. On the excitation of Lyman beta and Balmer alpha radiation by electron-impact dissociation of methane

    NASA Technical Reports Server (NTRS)

    Mclaughlin, R. W.; Zipf, E. C.

    1978-01-01

    The cross sections for the excitation of Ly-beta and H-alpha when methane is dissociated by electron impact have values of 17.1 by 10 to the -19th power sq cm and 26.0 by 10 to the -19th power sq cm, respectively, at an electron impact energy of 100 eV. These results are in disagreement with the implications of recent polarization measurements of H-alpha radiation that suggest negligible H(3p) excitation in the dissociation of CH4 by electron impact.

  19. Photochemical decomposition of N2O by Lyman-alpha radiation: scientific basis for a chemical actinometer.

    PubMed

    Rajappan, Mahesh; Büttner, Michael; Cox, Charlie; Yates, John T

    2010-03-18

    A novel IR method for measuring the kinetics of N(2)O photodecomposition has been devised and used to calibrate the flux of Lyman-alpha (10.2 eV) radiation from a H(2)/Ar microwave discharge lamp. The photodecomposition of N(2)O occurs with a weak pressure dependence due to the operation of a wall effect consuming some photogenerated active oxygen species. This effect is removed by working at high N(2)O pressures. The Lyman-alpha flux from the lamp is 1.28 +/- 0.36 x 10(15) photons cm(-2) s(-1). PMID:20155946

  20. Gas-Monitor Detector for Intense and Pulsed VUV/EUV Free-Electron Laser Radiation

    NASA Astrophysics Data System (ADS)

    Sorokin, A. A.; Bobashev, S. V.; Feldhaus, J.; Gerth, Ch.; Gottwald, A.; Hahn, U.; Kroth, U.; Richter, M.; Shmaenok, L. A.; Steeg, B.; Tiedtke, K.; Treusch, R.

    2004-05-01

    In the framework of current developments of new powerful VUV and EUV radiation sources, like VUV free-electron-lasers or EUV plasma sources for 13-nm lithography, we developed a gas-monitor detector in order to measure the photon flux of highly intense and extremely pulsed VUV and EUV radiation in absolute terms. The device is based on atomic photoionization of a rare gas at low particle density. Therefore, it is free of degradation and almost transparent, which allows the detector to be used as a continuously working beam-intensity monitor. The extended dynamic range of the detector allowed its calibration with relative standard uncertainties of 4% in the Radiometry Laboratory of the Physikalisch-Technische Bundesanstalt at the electron-storage ring BESSY II in Berlin using spectrally dispersed synchrotron radiation at low photon intensities and its utilization for absolute photon flux measurements of high power sources. In the present contribution, we describe the design of the detector and its application for the characterization of VUV free-electron-laser radiation at the TESLA test facility in Hamburg. By first pulse resolved measurements, a peak power of more than 100 MW at a wavelength of 87 nm was detected.

  1. Predictors of Radiation Pneumonitis in Patients Receiving Intensity-Modulated Radiation Therapy for Hodgkin and Non-Hodgkin Lymphoma

    PubMed Central

    Pinnix, Chelsea C.; Smith, Grace L.; Milgrom, Sarah; Osborne, Eleanor M.; Reddy, Jay P.; Akhtari, Mani; Reed, Valerie; Arzu, Isidora; Allen, Pamela K.; Wogan, Christine F.; Fanale, Michele A.; Oki, Yasuhiro; Turturro, Francesco; Romaguera, Jorge; Fayad, Luis; Fowler, Nathan; Westin, Jason; Nastoupil, Loretta; Hagemeister, Fredrick B.; Rodriguez, Alma; Ahmed, Sairah; Nieto, Yago; Dabaja, Bouthaina

    2015-01-01

    Purpose Few studies to date have evaluated factors associated with the development of radiation pneumonitis (RP) in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), especially in patients treated with contemporary radiation techniques. These patients represent a unique group owing to the often large radiation target volumes within the mediastinum and to the potential to receive several lines of chemotherapy that add to pulmonary toxicity for relapsed or refractory disease. Our objective was to determine the incidence and clinical and dosimetric risk factors associated with RP in lymphoma patients treated with intensity modulated radiation therapy (IMRT) at a single institution. Methods We retrospectively reviewed clinical charts and radiation records of 150 consecutive patients who received mediastinal IMRT for HL and NHL from 2009 through 2013. Clinical and dosimetric predictors associated with RP per the Radiation Therapy Oncology Group (RTOG) acute toxicity criteria were identified in univariate analysis using the Pearson χ2 test and logistic multivariate regression. Results Mediastinal radiation was administered as consolidation therapy in 110 patients with newly diagnosed HL or NHL and in 40 patients with relapsed or refractory disease. The overall incidence of RP (RTOG grade 1–3) was 14% in the entire cohort. Risk of RP was increased for patients who received radiation for relapsed or refractory disease (25%) versus those who received consolidation (10%, P=0.019). Several dosimetric parameters predicted RP, including mean lung dose (MLD) >13.5 Gy, V20 >30%, V15 >35%, V10 >40% and V5>55%. The likelihood ratio (LR) χ2 value was highest for V5< 55% (LR χ2=19.37). Conclusions In using IMRT to treat mediastinal lymphoma, all dosimetric parameters predicted RP, although small doses to large volumes of lung had the greatest influence. Patients with relapsed or refractory lymphoma who received salvage chemotherapy and hematopoietic stem cell

  2. Oxidative mechanisms of biological activity of low-intensity radiofrequency radiation.

    PubMed

    Yakymenko, Igor; Tsybulin, Olexandr; Sidorik, Evgeniy; Henshel, Diane; Kyrylenko, Olga; Kyrylenko, Sergiy

    2016-01-01

    This review aims to cover experimental data on oxidative effects of low-intensity radiofrequency radiation (RFR) in living cells. Analysis of the currently available peer-reviewed scientific literature reveals molecular effects induced by low-intensity RFR in living cells; this includes significant activation of key pathways generating reactive oxygen species (ROS), activation of peroxidation, oxidative damage of DNA and changes in the activity of antioxidant enzymes. It indicates that among 100 currently available peer-reviewed studies dealing with oxidative effects of low-intensity RFR, in general, 93 confirmed that RFR induces oxidative effects in biological systems. A wide pathogenic potential of the induced ROS and their involvement in cell signaling pathways explains a range of biological/health effects of low-intensity RFR, which include both cancer and non-cancer pathologies. In conclusion, our analysis demonstrates that low-intensity RFR is an expressive oxidative agent for living cells with a high pathogenic potential and that the oxidative stress induced by RFR exposure should be recognized as one of the primary mechanisms of the biological activity of this kind of radiation. PMID:26151230

  3. Transcriptional and Secretomic Profiling of Epidermal Cells Exposed to Alpha Particle Radiation

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Greene, Hillary Boulay; Wilkins, Ruth C

    2012-01-01

    Alpha (α)-particle emitters are probable isotopes to be used in a terrorist attack. The development of biological assessment tools to identify those who have handled these difficult to detect materials would be an asset to our current forensic capacity. In this study, for the purposes of biomarker discovery, human keratinocytes were exposed to α-particle and X-radiation (0.98 Gy/h at 0, 0.5, 1.0, 1.5 Gy) and assessed for differential gene and protein expression using microarray and Bio-Plex technology, respectively. Secretomic analysis of supernatants showed expression of two pro-inflammatory cytokines (IL-13 and PDGF-bb) to be exclusively affected in α-particle exposed cells. The highest dose of α-particle radiation modulated a total of 67 transcripts (fold change>|1.5|, (False discovery rate) FDR<0.05) in exposed cells. Several genes which responded with high expression levels (>2 fold) included KIF20A, NEFM, C7orf10, HIST1H2BD, BMP6, and HIST1H2AC. Among the high expressing genes, five (CCNB2, BUB1, NEK2, CDC20, AURKA) were also differentially expressed at the medium (1.0 Gy) dose however, these genes were unmodulated following exposure to X-irradiation. Networks of these genes clustered around tumor protein-53 and transforming growth factor-beta signaling. This study has identified some potential gene /protein responses and networks that may be validated further to confirm their specificity and potential to be signature biomarkers of α-particle exposure. PMID:23002402

  4. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  5. Ablation and transmission of thin solid targets irradiated by intense extreme ultraviolet laser radiation

    NASA Astrophysics Data System (ADS)

    Aslanyan, V.; Kuznetsov, I.; Bravo, H.; Woolston, M. R.; Rossall, A. K.; Menoni, C. S.; Rocca, J. J.; Tallents, G. J.

    2016-09-01

    The interaction of an extreme ultraviolet (EUV) laser beam with a parylene foil was studied by experiments and simulation. A single EUV laser pulse of nanosecond duration focused to an intensity of 3 × 1010 W cm-2 perforated micrometer thick targets. The same laser pulse was simultaneously used to diagnose the interaction by a transmission measurement. A combination of 2-dimensional radiation-hydrodynamic and diffraction calculations was used to model the ablation, leading to good agreement with experiment. This theoretical approach allows predictive modelling of the interaction with matter of intense EUV beams over a broad range of parameters.

  6. Telomere Length in Aged Mayak PA Nuclear Workers Chronically Exposed to Internal Alpha and External Gamma Radiation.

    PubMed

    Scherthan, Harry; Sotnik, Natalia; Peper, Michel; Schrock, Gerrit; Azizova, Tamara; Abend, Michael

    2016-06-01

    Telomeres consist of GC-rich DNA repeats and the "shelterin" protein complex that together protect chromosome ends from fusion and degradation. Telomeres shorten with age due to incomplete end replication and upon exposure to environmental and intrinsic stressors. Exposure to ionizing radiation is known to modulate telomere length. However, the response of telomere length in humans chronically exposed to radiation is poorly understood. Here, we studied relative telomere length (RTL) by IQ-FISH to leukocyte nuclei in a group of 100 workers from the plutonium production facility at the Mayak Production Association (PA) who were chronically exposed to alpha-emitting ((239)Pu) radiation and/or gamma (photon) radiation, and 51 local residents serving as controls, with a similar mean age of about 80 years. We applied generalized linear statistical models adjusted for age at biosampling and the second exposure type on a linear scale and observed an age-dependent telomere length reduction. In those individuals with the lowest exposure, a significant reduction of about 20% RTL was observed, both for external gamma radiation (≤1 Gy) and internal alpha radiation (≤0.05-0.1 Gy to the red bone marrow). In highly exposed individuals (>0.1 Gy alpha, 1-1.5 Gy gamma), the RTL was similar to control. Stratification by gender revealed a significant (∼30%) telomere reduction in low-dose-exposed males, which was absent in females. While the gender differences in RTL may reflect different working conditions, lifestyle and/or telomere biology, absence of a dose response in the highly exposed individuals may reflect selection against cells with short telomeres or induction of telomere-protective effects. Our observations suggest that chronic systemic exposure to radiation leads to variable dose-dependent effects on telomere length. PMID:27340887

  7. Radiation-induced cationic polymerization of limonene oxide,. cap alpha. -pinene oxide, and. beta. -pinene oxide

    SciTech Connect

    Aikins, J.A.; Williams, F.

    1985-01-01

    After suitable drying, the subject monomers in the form of neat liquids undergo radiation-induced polymerization with no apparent side reactions and high conversions to precipitatable polymers of low molecular weights. A high frequency of chain (proton) transfer to monomer is indicated by the fact that the kinetic chain lengths are estimated to be several hundred times larger than the range of DP/sub n/ values (12-4). Structural characterization of the limonene oxide polymer by /sup 1/H and /sup 13/C NMR spectroscopy provides conclusive evidence that the polymerization proceeds by the opening of the epoxide ring to yield a 1,2-trans polyether. Similar NMR studies on the polymers formed from the ..cap alpha..-pinene and ..beta..-pinene oxides show that the opening of the epoxide ring for these monomers is generally accompanied by the concomitant ring opening of the cyclobutane ring structure to yield a gem-di-methyl group in the main chain.

  8. Radiation damage induced by MeV alpha particles in polycrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Prawer, S.; Nugent, K. W.; Jamieson, D. N.

    1996-11-01

    Radiation damage induced by 2 MeV alpha particles in polycrystalline diamond films has been studied as a function of the irradiation dose D (1012≤D≤1017 cm-2). The films were characterized using Raman/photoluminescence spectroscopy and I(V,T) measurements. The results can be summarized as follows. In undoped samples the H3 luminescent center (N-V-N) is observed for D≥1014 cm-2. The Raman diamond peak is broadened and shifted to lower frequencies for D≳1015 cm-2. No new graphitic component is detected after irradiation. On the contrary graphitic sp2 defects are annealed by irradiation. For D=3×1016 cm-2 new Raman defect peaks are detected at 1496 and 1635 cm-1. I(V,T) characteristics remain unaffected for D≤1016 cm-2. An increase in the conductivity is observed for D=3×1016 cm-2. At this dose we observe an activation energy of 0.4 eV and thermally stimulated currents related to defect levels at about 0.3 eV. A boron-doped sample (100 Ω cm) has been irradiated at 1017 cm-2 for comparison. After irradiation the conductivity of this sample is reduced and the activation energy of the conductivity is also reduced. Less damage is detected by Raman spectroscopy in the B-doped material.

  9. CHO cell repair of single-strand and double-strand DNA breaks induced by gamma- and alpha-radiations.

    PubMed

    Cole, A; Shonka, F; Corry, P; Cooper, W G

    1975-01-01

    Neutral and alkaline sucrose gradient sedimentation analysis was used to measure double- and single-strand breaks in the DNA of Chinese hamster ovary (CHO) cells exposed to either gamma- or alpha-radiation. After irradiation, cells were incubated for 15-180 min to test the ability of the cell to rejoin the DNA breaks. Essentially complete rejoining was observed for single-strand breaks induced by gamma- or alpha-doses below 20 krad and for double-strand breaks induced by gamma doses below 60 krad. Approximately 80% rejoining was observed for double-strand breaks induced by alpha doses below 40 krad. At higher doses, the repair system appeared to saturate in such a way that essentially no additional breaks were rejoined. PMID:1191188

  10. Radiation exposure among medical professionals working in the Intensive Care Unit

    PubMed Central

    Siddiqui, Suhail S.; Jha, Ashish; Konar, Nambiraj; Ranganathan, Priya; Deshpande, Deepak D.; Divatia, Jigeeshu V.

    2014-01-01

    Background and Aims: With the expanding use of diagnostic and therapeutic radiological modalities in critically ill patients, doctors working in Intensive Care Units (ICUs) are increasingly exposed to ionizing radiation. This risk of radiation exposure occurs not only during bedside radiologic procedures, but also when ICU physicians accompany patients to radiology suites. The aim of this study was to quantify levels of radiation exposure among medical professionals working in the ICU. Materials and Methods: The study was carried out prospectively over 6 months in the ICU of a tertiary-referral cancer hospital. Two teams consisting of 4 ICU resident doctors each were instructed to wear thermoluminescent dosimeters (TLDs) during their duty shifts. Standard radiation protection precautions were used throughout the study period. TLDs were also placed in selected areas of the ICU to measure the amount of scattered radiation. TLDs were analyzed at the end of every 3 months. Results: The readings recorded on TLDs placed in the ICU were almost immeasurable. The mean value of residents' radiation exposure was 0.059 mSv, though the highest individual reading approached 0.1 mSv. The projected maximum yearly radiation exposure was 0.4 mSv. Conclusions: If standard radiation safety precautions are followed, the cumulative radiation exposure to ICU resident doctors is well within permissible limits and is not a cause of concern. However, with the increasing use of radiological procedures in the management of critically ill patients, there is a need to repeat such audits periodically to monitor radiation exposure. PMID:25249743

  11. Theory of molecular rate processes in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    George, T. F.; Zimmerman, I. H.; Devries, P. L.; Yuan, J.-M.; Lam, K.-S.; Bellum, J. C.; Lee, H.-W.; Slutsky, M. S.; Lin, J.-T.

    1979-01-01

    The present paper deals with the influence of intense laser radiation on gas-phase molecular rate processes. Representations of the radiation field, the particle system, and the interaction involving these two entities are discussed from a general rather than abstract point of view. The theoretical methods applied are outlined, and the formalism employed is illustrated by application to a variety of specific processes. Quantum mechanical and semiclassical treatments of representative atom-atom and atom-diatom collision processes in the presence of a field are examined, and examples of bound-continuum processes and heterogeneous catalysis are discussed within the framework of both quantum-mechanical and semiclassical theories.

  12. Development of a proposed international standard for certification of aircraft to High Intensity Radiated Fields (HIRF)

    NASA Technical Reports Server (NTRS)

    Sargent, Noel B.

    1993-01-01

    Avionic systems performing critical functions in modern aircraft are potentially susceptible to the hazards of electromagnetic radiation from ground and airborne transmitters. The Federal Aviation Administration (FAA) requested that the Society of Automotive Engineers (SAE) coordinate the development of procedures and guidance material which can be used during the aircraft certification process to ensure adequate protection against high intensity radiated fields (HIRF). This paper addresses both the technical challenge of drafting a certification procedure and guidance standard as well as the management process used by the SAE subcommittee AE4R to converge a diverse range of opinions by its international membership in the shortest possible time.

  13. 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.

  14. Construction of hybrid peptide synthetases for the production of alpha-l-aspartyl-l-phenylalanine, a precursor for the high-intensity sweetener aspartame.

    PubMed

    Duerfahrt, Thomas; Doekel, Sascha; Sonke, Theo; Quaedflieg, Peter J L M; Marahiel, Mohamed A

    2003-11-01

    Microorganisms produce a large number of pharmacologically and biotechnologically important peptides by using nonribosomal peptide synthetases (NRPSs). Due to their modular arrangement and their domain organization NRPSs are particularly suitable for engineering recombinant proteins for the production of novel peptides with interesting properties. In order to compare different strategies of domain assembling and module fusions we focused on the selective construction of a set of peptide synthetases that catalyze the formation of the dipeptide alpha-l-aspartyl-l-phenylalanine (Asp-Phe), the precursor of the high-intensity sweetener alpha-l-aspartyl-l-phenylalanine methyl ester (aspartame). The de novo design of six different Asp-Phe synthetases was achieved by fusion of Asp and Phe activating modules comprising adenylation, peptidyl carrier protein and condensation domains. Product release was ensured by a C-terminally fused thioesterase domains and quantified by HPLC/MS analysis. Significant differences of enzyme activity caused by the fusion strategies were observed. Two forms of the Asp-Phe dipeptide were detected, the expected alpha-Asp-Phe and the by-product beta-Asp-Phe. Dependent on the turnover rates ranging from 0.01-0.7 min-1, the amount of alpha-Asp-Phe was between 75 and 100% of overall product, indicating a direct correlation between the turnover numbers and the ratios of alpha-Asp-Phe to beta-Asp-Phe. Taken together these results provide useful guidelines for the rational construction of hybrid peptide synthetases. PMID:14622284

  15. Higher order terms of radiative damping in extreme intense laser-matter interaction

    SciTech Connect

    Pandit, Rishi R.; Sentoku, Yasuhiko

    2012-07-15

    The higher order terms of the Lorentz-Abraham-Dirac equation have been derived, and their effects are studied via a relativistic collisional particle-in-cell simulation. The dominant group of terms up to the fourth order of the Lorentz-Abraham-Dirac equation is identified for ultra-intense laser-matter interactions. The second order terms are found to be the damping terms of the Lorentz force while the first order terms represent friction in the equation of motion. Because the second order terms restrict electron acceleration during the laser interaction, electrons/ions are prevented from over-accelerating. Radiative damping becomes highly significant when I{>=} 10{sup 22} W/cm{sup 2} while Bremsstrahlung will be saturated, thus radiative damping will be a dominant source of hard x-rays in regimes at extreme intensities.

  16. Calculation of synchrotron radiation from high intensity electron beam at eRHIC

    SciTech Connect

    Jing Y.; Chubar, O.; Litvinenko, V.

    2012-05-20

    The Electron-Relativistic Heavy Ion Collider (eRHIC) at Brookhaven National Lab is an upgrade project for the existing RHIC. A 30 GeV energy recovery linac (ERL) will provide a high charge and high quality electron beam to collide with proton and ion beams. This will improve the luminosity by at least 2 orders of magnitude. The synchrotron radiation (SR) from the bending magnets and strong quadrupoles for such an intense beam could be penetrating the vacuum chamber and producing hazards to electronic devices and undesired background for detectors. In this paper, we calculate the SR spectral intensity, power density distributions and heat load on the chamber wall. We suggest the wall thickness required to stop the SR and estimate spectral characteristics of the residual and scattered background radiation outside the chamber.

  17. Observation of Relativistic Electron Microbursts in Conjunction with Intense Radiation Belt Whistler-Mode Waves

    NASA Technical Reports Server (NTRS)

    Kersten, K.; Cattell, C. A.; Breneman, A.; Goetz, K.; Kellogg, P. J.; Wygant, J. R.; Wilson, L. B., III; Blake, J. B.; Looper, M. D.; Roth, I.

    2011-01-01

    We present multi-satellite observations of large amplitude radiation belt whistler-mode waves and relativistic electron precipitation. On separate occasions during the Wind petal orbits and STEREO phasing orbits, Wind and STEREO recorded intense whistler-mode waves in the outer nightside equatorial radiation belt with peak-to-peak amplitudes exceeding 300 mV/m. During these intervals of intense wave activity, SAMPEX recorded relativistic electron microbursts in near magnetic conjunction with Wind and STEREO. This evidence of microburst precipitation occurring at the same time and at nearly the same magnetic local time and L-shell with a bursty temporal structure similar to that of the observed large amplitude wave packets suggests a causal connection between the two phenomena. Simulation studies corroborate this idea, showing that nonlinear wave.particle interactions may result in rapid energization and scattering on timescales comparable to those of the impulsive relativistic electron precipitation.

  18. Hole-boring radiation pressure proton acceleration at high intensity in near-critical density targets

    NASA Astrophysics Data System (ADS)

    Yu, Jinqing; Dover, N. P.; Jin, Xiaolin; Li, Bin; Dangor, A. E.; Najmudin, Z.

    2014-10-01

    We will present high quality proton beams accelerated from hole-boring radiation pressure proton acceleration (HB-RPA) using three-dimension Particle-in-Cell simulation results. Scaling works on proton cut off energy with laser parameters such as laser intensity and laser pulse duration have been studied in detail by two-dimension Particle-in-Cell simulations. Optimal conditions for generating proton beam of narrow energy spread will be discussed.

  19. Photoelectric properties of GaAs p-n-junction under illumination of intense laser radiation

    NASA Astrophysics Data System (ADS)

    Ašmontas, S.; Gradauskas, J.; Sužiedėlis, A.; Šilėnas, A.; Vaičikauskas, V.; Žalys, O.; Steikūnas, G.; Steikūnienė, A.

    2014-10-01

    Results of experimental investigation of photoelectric properties of GaAs p-n-junction illuminated by short laser pulses of 1.06 μm wavelength are presented. The influence of laser radiation intensity and external bias voltage on the formation of photoresponse voltage has been studied. Free carrier heating was recognized to influence significantly the magnitude of the measured photovoltage. Possibility to improve the conversion efficiency of solar cells is discussed.

  20. The response of heat-shield materials to intense laser radiation

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.

    1978-01-01

    Experimental results for the response of ATJ graphite, Carbitex 100, and carbon phenolic to intense continuous-wave laser radiation are presented. Both penetration and mass-loss test techniques are used and compared. The results are also compared with a simple ablation theory applicable to laser irradiation. Reasons for the disparity between experiment and theory, and applicability of the results to other heating situations, such as planetary entry, are discussed.

  1. Radiation dosimetry using decreasing TL intensity in a few variety of silicate crystals.

    PubMed

    Watanabe, Shigueo; Cano, Nilo F; Gundu Rao, T K; Oliveira, Letícia M; Carmo, Lucas S; Chubaci, Jose F D

    2015-11-01

    This study shows that there are some ionic crystals which after irradiation with high gamma dose Dm and subsequent irradiation with low doses ranging up to 500Gy present a decreasing TL intensity as dose increases. This interesting feature can be used as a calibration curve in radiation dosimetry. Such behavior can be found in green quartz, three varieties of beryl and pink tourmaline. In all these silicate crystals it can be shown that irradiation with increasing γ-dose there is a dose Dm for which the TL intensity is maximum. Of course, Dm varies depending on the crystal and irradiated crystal with the dose Dm is stable. If one of these crystals is taken and irradiated with doses from low values up to 400-500Gy, a curve of decreasing TL intensity is obtained; such a curve can be used as a calibration curve. PMID:26277189

  2. Useful intensity: A technique to identify radiating regions on arbitrarily shaped surfaces

    NASA Astrophysics Data System (ADS)

    Corrêa Junior, C. A.; Tenenbaum, R. A.

    2013-03-01

    This work presents a new technique for the computation of the numerical equivalent to the supersonic acoustic intensity, for arbitrarily shaped sound sources. The technique provides therefore the identification of the regions of a noise source that effectively contribute to the sound power radiated into the far field by filtering non-propagating sound waves. The proposed technique is entirely formulated on the vibrating surface. The radiated acoustic power is obtained through a numerical operator that relates it with the superficial normal velocity distribution. The power operator is obtained by using the boundary element method. Such operator, possesses the property of being Hermitian. The advantage of this characteristic is that it has real eigenvalues and their eigenvectors form an orthonormal set for the velocity distribution. It is applied to the power operator the decomposition in eigenvalues and eigenvectors, becoming possible to compute the numerical equivalent to the supersonic intensity, called here as useful intensity, after applying a cutoff criterion to remove the non-propagating components. Some numerical tests confirming the effectiveness of the convergence criterion are presented. Examples of the application of the useful intensity technique in vibrating surfaces such as a plate, a cylinder with flat caps and an automotive muffler are presented and the numerical results are discussed.

  3. Water-ion transmembrane transfer under the effect of low-intensity laser radiation

    NASA Astrophysics Data System (ADS)

    Anisimov, A. V.; Vorob'ev, V. N.; Silkin, N. I.

    1997-09-01

    Water-ion transmembrane transfer in maize roots under the effect of infrared laser radiation with power 2.4 mwatt was studied by NMR method. It is shown that laser radiation (LR) alters the dynamics of spin-spin relaxation and increases the rate of transmembrane water exchange and ion penetration which do not depend on the type of paramagnetic ions doped into the intercellular space. The radiation results in the increase of the effective self-diffusion coefficient of water, and it correlates with the data on the effect of LR on the velocity of cytoplasm movement. The data on the decrease of the resistance of Nernst layers in the summary membrane permeability due to 'blowing off' its outer parts by the intensive cytoplasm current are used to explain the obtained results.

  4. Generation of Intense Narrow-Band Tunable Terahertz Radiation from Highly Bunched Electron Pulse Train

    NASA Astrophysics Data System (ADS)

    Li, Heting; Lu, Yalin; He, Zhigang; Jia, Qika; Wang, Lin

    2016-07-01

    We present the analysis and start-to-end simulation of an intense narrow-band terahertz (THz) source with a broad tuning range of radiation frequency, using a single-pass free electron laser (FEL) driven by a THz-pulse-train photoinjector. The fundamental radiation frequency, corresponding to the spacing between the electron microbunches, can be easily tuned by varying the spacing time between the laser micropulses. Since the prebunched electron beam is highly bunched at the first several harmonics, with the harmonic generation technique, the radiation frequency range can be further enlarged by several times. The start-to-end simulation results show that this FEL is capable of generating a few tens megawatts power, several tens micro-joules pulse energy, and a few percent bandwidth at the frequencies of 0.5-5 THz. In addition, several practical issues are considered.

  5. Radiative properties of ceramic metal-halide high intensity discharge lamps containing additives in argon plasma

    NASA Astrophysics Data System (ADS)

    Cressault, Yann; Teulet, Philippe; Zissis, Georges

    2016-07-01

    The lighting represents a consumption of about 19% of the world electricity production. We are thus searching new effective and environment-friendlier light sources. The ceramic metal-halide high intensity lamps (C-MHL) are one of the options for illuminating very high area. The new C-MHL lamps contain additives species that reduce mercury inside and lead to a richer spectrum in specific spectral intervals, a better colour temperature or colour rendering index. This work is particularly focused on the power radiated by these lamps, estimated using the net emission coefficient, and depending on several additives (calcium, sodium, tungsten, dysprosium, and thallium or strontium iodides). The results show the strong influence of the additives on the power radiated despite of their small quantity in the mixtures and the increase of visible radiation portion in presence of dysprosium.

  6. Radiation Exposure to Premature Infants in a Neonatal Intensive Care Unit in Turkey

    PubMed Central

    Onal, Esra; Bor, Dogan; Okumus, Nurullah; Atalay, Yildiz; Turkyilmaz, Canan; Ergenekon, Ebru; Koc, Esin

    2008-01-01

    Objective The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results The mean ESDTO for the chest and abdomen were 67 µGy and 65 µGy per procedure, respectively. The mean ESDTLD per radiograph was 70 µGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 µGy) per radiograph. Mean effective doses were 16 and 27 µSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other. PMID:18838850

  7. Radiation brain injury is reduced by the polyamine inhibitor [alpha]-difluoromethylornithine

    SciTech Connect

    Fike, J.R.; Seilhan, T.M.; Gobbel, G.T. ); Marton, L.J. )

    1994-04-01

    [alpha]-difluoromethylornithine (DFMO) was used to reduce [sup 125]I-induced brain injury in normal beagle dogs. Different DFMO doses and administration schedules were used to determine if the reduction in brain injury was dependent on dose and/or dependent upon when the drug was administered relative to the radiation treatment. Doses of DMFO of 75 mg/kg/day and 37.5 mg/kg/day given 2 days before, during and for 14 days after irradiation reduced levels of putrescine (PU) in the cerebrospinal fluid relative to controls. Volume of edema was significantly reduced by 75 mg/kg/day of DFMO before, during and after irradiation and by the same dose when the drug was started immediately after irradiation. A reduction in edema volume after 37.5 mg/kg/day of DFMO before, during and after irradiation was very near significance. Ultrafast CT studies performed on dogs that received a DFMO dose of 75 mg/kg/day before, during and after irradiation suggested that the reduce edema volume was associated with reduced vascular permeability. Volume of necrosis and volume of contrast enhancement (breakdown of the blood-brain barrier) were significantly lower than controls only after a DFMO dose of 75 mg/kg/day before, during and after irradiation. These latter data, coupled with the findings relative to edema, suggest that different mechanisms may be involved with respect to the effects of DFMO on brain injury, or that the extents of edema, necrosis and breakdown of the blood-brain barrier may depend upon different levels of polyamine depletion. The precise mechanisms by which DFMO exerts the effects observed here need to be determined. 41 refs., 5 figs.

  8. The influence of salt aerosol on alpha radiation detection by WIPP continuous air monitors

    SciTech Connect

    Bartlett, W.T.; Walker, B.A.

    1997-08-01

    Waste Isolation Pilot Plant (WIPP) alpha continuous air monitor (CAM) performance was evaluated to determine if CAMs could detect accidental releases of transuranic radioactivity from the underground repository. Anomalous alpha spectra and poor background subtraction were observed and attributed to salt deposits on the CAM sampling filters. Microscopic examination of salt laden sampling filters revealed that aerosol particles were forming dendritic structures on the surface of the sampling filters. Alpha CAM detection efficiency decreased exponentially as salt deposits increased on the sampling filters, suggesting that sampling-filter salt was performing like a fibrous filter rather than a membrane filter. Aerosol particles appeared to penetrate the sampling-filter salt deposits and alpha particle energy was reduced. These findings indicate that alpha CAMs may not be able to detect acute releases of radioactivity, and consequently CAMs are not used as part of the WIPP dynamic confinement system. 12 refs., 12 figs., 1 tab.

  9. Clinical Outcomes of Intensity-Modulated Pelvic Radiation Therapy for Carcinoma of the Cervix

    SciTech Connect

    Hasselle, Michael D.; Rose, Brent S.; Kochanski, Joel D.; Nath, Sameer K.; Bafana, Rounak; Yashar, Catheryn M.; Hasan, Yasmin; Roeske, John C.; Mundt, Arno J.; Mell, Loren K.

    2011-08-01

    Purpose: To evaluate disease outcomes and toxicity in cervical cancer patients treated with pelvic intensity-modulated radiation therapy (IMRT). Methods and Materials: We included all patients with Stage I-IVA cervical carcinoma treated with IMRT at three different institutions from 2000-2007. Patients treated with extended field or conventional techniques were excluded. Intensity-modulated radiation therapy plans were designed to deliver 45 Gy in 1.8-Gy daily fractions to the planning target volume while minimizing dose to the bowel, bladder, and rectum. Toxicity was graded according to the Radiation Therapy Oncology Group system. Overall survival and disease-free survival were estimated by use of the Kaplan-Meier method. Pelvic failure, distant failure, and late toxicity were estimated by use of cumulative incidence functions. Results: The study included 111 patients. Of these, 22 were treated with postoperative IMRT, 8 with IMRT followed by intracavitary brachytherapy and adjuvant hysterectomy, and 81 with IMRT followed by planned intracavitary brachytherapy. Of the patients, 63 had Stage I-IIA disease and 48 had Stage IIB-IVA disease. The median follow-up time was 27 months. The 3-year overall survival rate and the disease-free survival rate were 78% (95% confidence interval [CI], 68-88%) and 69% (95% CI, 59-81%), respectively. The 3-year pelvic failure rate and the distant failure rate were 14% (95% CI, 6-22%) and 17% (95% CI, 8-25%), respectively. Estimates of acute and late Grade 3 toxicity or higher were 2% (95% CI, 0-7%) and 7% (95% CI, 2-13%), respectively. Conclusions: Intensity-modulated radiation therapy is associated with low toxicity and favorable outcomes, supporting its safety and efficacy for cervical cancer. Prospective clinical trials are needed to evaluate the comparative efficacy of IMRT vs. conventional techniques.

  10. Predictors of Radiation Pneumonitis in Patients Receiving Intensity Modulated Radiation Therapy for Hodgkin and Non-Hodgkin Lymphoma

    SciTech Connect

    Pinnix, Chelsea C.; Smith, Grace L.; Milgrom, Sarah; Osborne, Eleanor M.; Reddy, Jay P.; Akhtari, Mani; Reed, Valerie; Arzu, Isidora; Allen, Pamela K.; Wogan, Christine F.; Fanale, Michele A.; Oki, Yasuhiro; Turturro, Francesco; Romaguera, Jorge; Fayad, Luis; Fowler, Nathan; Westin, Jason; Nastoupil, Loretta; Hagemeister, Fredrick B.; Rodriguez, M. Alma [Department of Lymphoma and others

    2015-05-01

    Purpose: Few studies to date have evaluated factors associated with the development of radiation pneumonitis (RP) in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), especially in patients treated with contemporary radiation techniques. These patients represent a unique group owing to the often large radiation target volumes within the mediastinum and to the potential to receive several lines of chemotherapy that add to pulmonary toxicity for relapsed or refractory disease. Our objective was to determine the incidence and clinical and dosimetric risk factors associated with RP in lymphoma patients treated with intensity modulated radiation therapy (IMRT) at a single institution. Methods and Materials: We retrospectively reviewed clinical charts and radiation records of 150 consecutive patients who received mediastinal IMRT for HL and NHL from 2009 through 2013. Clinical and dosimetric predictors associated with RP according to Radiation Therapy Oncology Group (RTOG) acute toxicity criteria were identified in univariate analysis using the Pearson χ{sup 2} test and logistic multivariate regression. Results: Mediastinal radiation was administered as consolidation therapy in 110 patients with newly diagnosed HL or NHL and in 40 patients with relapsed or refractory disease. The overall incidence of RP (RTOG grades 1-3) was 14% in the entire cohort. Risk of RP was increased for patients who received radiation for relapsed or refractory disease (25%) versus those who received consolidation therapy (10%, P=.019). Several dosimetric parameters predicted RP, including mean lung dose of >13.5 Gy, V{sub 20} of >30%, V{sub 15} of >35%, V{sub 10} of >40%, and V{sub 5} of >55%. The likelihood ratio χ{sup 2} value was highest for V{sub 5} >55% (χ{sup 2} = 19.37). Conclusions: In using IMRT to treat mediastinal lymphoma, all dosimetric parameters predicted RP, although small doses to large volumes of lung had the greatest influence. Patients with relapsed

  11. Imaging Changes in Pediatric Intracranial Ependymoma Patients Treated With Proton Beam Radiation Therapy Compared to Intensity Modulated Radiation Therapy

    SciTech Connect

    Gunther, Jillian R.; Sato, Mariko; Chintagumpala, Murali; Ketonen, Leena; Jones, Jeremy Y.; Allen, Pamela K.; Paulino, Arnold C.; Okcu, M. Fatih; Su, Jack M.; Weinberg, Jeffrey; Boehling, Nicholas S.; Khatua, Soumen; Adesina, Adekunle; Dauser, Robert; Whitehead, William E.; Mahajan, Anita

    2015-09-01

    Purpose: The clinical significance of magnetic resonance imaging (MRI) changes after radiation therapy (RT) in children with ependymoma is not well defined. We compared imaging changes following proton beam radiation therapy (PBRT) to those after photon-based intensity modulated RT (IMRT). Methods and Materials: Seventy-two patients with nonmetastatic intracranial ependymoma who received postoperative RT (37 PBRT, 35 IMRT) were analyzed retrospectively. MRI images were reviewed by 2 neuroradiologists. Results: Sixteen PBRT patients (43%) developed postradiation MRI changes at 3.8 months (median) with resolution by 6.1 months. Six IMRT patients (17%) developed changes at 5.3 months (median) with 8.3 months to resolution. Mean age at radiation was 4.4 and 6.9 years for PBRT and IMRT, respectively (P=.06). Age at diagnosis (>3 years) and time of radiation (≥3 years) was associated with fewer imaging changes on univariate analysis (odds ratio [OR]: 0.35, P=.048; OR: 0.36, P=.05). PBRT (compared to IMRT) was associated with more frequent imaging changes, both on univariate (OR: 3.68, P=.019) and multivariate (OR: 3.89, P=.024) analyses. Seven (3 IMRT, 4 PBRT) of 22 patients with changes had symptoms requiring intervention. Most patients were treated with steroids; some PBRT patients also received bevacizumab and hyperbaric oxygen therapy. None of the IMRT patients had lasting deficits, but 2 patients died from recurrent disease. Three PBRT patients had persistent neurological deficits, and 1 child died secondarily to complications from radiation necrosis. Conclusions: Postradiation MRI changes are more common with PBRT and in patients less than 3 years of age at diagnosis and treatment. It is difficult to predict causes for development of imaging changes that progress to clinical significance. These changes are usually self-limiting, but some require medical intervention, especially those involving the brainstem.

  12. Using time-integrated K{sub {alpha}} images to study refluxing and the extent of pre-plasmas in intense laser-plasma experiment

    SciTech Connect

    Ovchinnikov, V. M.; Schumacher, D. W.; Kemp, G. E.; Krygier, A. G.; Van Woerkom, L. D.; Akli, K. U.; Freeman, R. R.; Stephens, R. B.; Link, A.

    2011-11-15

    We report the results of an experimental and numerical modeling study of the formation of time-integrated K{sub {alpha}} images by electrons excited during an intense laser-plasma interaction. We report the use of the spatial structure of time-integrated K{sub {alpha}} images to quantitatively characterize the pre-plasma profile near the critical surface and to verify the near elimination of back-surface refluxing from targets when a thick layer of a low-Z material is attached to the back. The time integrated K{sub {alpha}} images are found to be sensitive to the relative separation between the critical surface and the bulk target, permitting a single parameter exponential pre-plasma scale length to be determined by fitting to experimental results. The refluxed electrons affect different parts of the K{sub {alpha}} images in a manner that varies depending on the location of the refluxing. We use these properties to characterize refluxing also by fitting to experimental results. Experiments were performed using the Titan laser at the Lawrence Livermore National Laboratory and the simulations used a customized version of the hybrid-PIC code, LSP. We find good quantitative match between experiment and simulation.

  13. Propagation and absorption of high-intensity femtosecond laser radiation in diamond

    SciTech Connect

    Kononenko, V V; Konov, V I; Gololobov, V M; Zavedeev, E V

    2014-12-31

    Femtosecond interferometry has been used to experimentally study the photoexcitation of the electron subsystem of diamond exposed to femtosecond laser pulses of intensity 10{sup 11} to 10{sup 14} W cm{sup -2}. The carrier concentration has been determined as a function of incident intensity for three harmonics of a Ti : sapphire laser (800, 400 and 266 nm). The results demonstrate that, in a wide range of laser fluences (up to those resulting in surface and bulk graphitisation), a well-defined multiphoton absorption prevails. We have estimated nonlinear absorption coefficients for pulsed radiation at λ = 800 nm (four-photon transition) and at 400 and 266 nm (indirect and direct two-photon transitions, respectively). It has also been shown that, at any considerable path length of a femtosecond pulse in diamond (tens of microns or longer), the laser beam experiences a severe nonlinear transformation, determining the amount of energy absorbed by the lattice, which is important for the development of technology for diamond photostructuring by ultrashort pulses. The competition between wave packet self-focusing and the plasma defocusing effect is examined as a major mechanism governing the propagation of intense laser pulses in diamond. (interaction of laser radiation with matter. laser plasma)

  14. Experimental study of intense radiation in terahertz region based on cylindrical surface wave resonator

    SciTech Connect

    Gong, Shaoyan; Ogura, Kazuo; Yambe, Kiyoyuki; Nomizu, Shintaro; Shirai, Akihiro; Yamazaki, Kosuke; Kawamura, Jun; Miura, Takuro; Takanashi, Sho; San, Min Thu

    2015-09-28

    Periodical corrugations structured on a cylindrical conductor have cylindrical surface waves (CSWs), which are reflected at the corrugation ends and form a CSW-resonator. In this paper, intense radiations in terahertz region based on the CSW-resonator are reported. The CSW-resonators with upper cut off frequencies in the modern IEEE G-band (110–300 GHz) are excited by a coaxially injected annular beam in a weakly relativistic region less than 100 kV. It is shown that there exists an oscillation starting energy for the CSW-resonator. Above the starting energy, very intense terahertz radiations on the order of kW are obtained. The operation frequencies in the range of 166–173 GHz and 182–200 GHz are obtained using two types of CSW-resonator with the different corrugation amplitude. Electromagnetic properties of the CSW-resonator can be controlled by the artificial structure and may play an important role in high-intensity terahertz generations and applications.

  15. Radiative processes in Alpha-ZnAl_2S4: Ti spinel type single crystals

    NASA Astrophysics Data System (ADS)

    Kulyuk, Leonid; Klokishner, Sophia; Sushkevich, Konstantin; Koshchug, Dmitrii; Boulon, Georges; Brenier, Alain; Fortin, Emery

    2008-06-01

    The radiative properties of the alpha-ZnAl_2S4 wide band -gap semiconductor (E_g=3.4eV) doped with Ti-ions are investigated . It is shown, that the ZnAl_2S_4:Ti spinel type crystals exhibit a IR luminescence in the spectral range 0.8-1.4 micrometers. The observed spectroscopic and temporal characteristics are assigned to the emission bands arising from the ligand - -Ti^4+ charge transfer for octahedral sites of titanium. Bulk stoichiometric alpha-ZnAl2S4:Ti crystals with impurity concentration 0.1-0.5 at % were grown by a closed tube vapor method with halogen as a transport agent. At temperatures T=2-300K the steady state and time-resolved photoluminescence (PL) studies, as well as the optical absorption measurements , were carried out in the spectral range 0.4-1.5 μm using a liquid nitrogen cooled Ge-detector or photomultiplier. The steady-state PL excitation was provided by Ar^+ (λ_ex1=514nm) and He-Ne (Lambda_ex2=633nm) lasers. The PL kinetics has been examined under pulsed excitation (tau_P~10^-8 s) with wavelengths: "green"-λ_ex1P=532nm and "red"-λ_ex2P=630nm (dye laser and OPO) close to Lambda_ex1 and λ_ex2. The EPR studies of the samples have been carried out as well. Under the "green" excitation (λ_ex1), that corresponds to the maximum of the Ti-impurity absorption (λ_abs~510nm), the steady -state PL spectra of ZnAl^2S^4:Ti crystals consist of 2 broad bands centered at λ_1=1.1μm and Lambda_20.8μm. Τhe first component λ_1 dominates in the spectrum at low temperatures (T<200K). At T~300K the shape of the integral spectrum practically is determined by the second broad band Lambda_2. At "red" excitation (λ_ex2, λ_ex2P) the main contribution to the PL spectra in the whole temperature range is provided by the second component, the kinetics of which obeys the exponential law with a single decay time. In contrast to the second band , the emission decay can be described by the superposition of two exponents with different lifetimes. At low

  16. COMPARISON OF THE DIFFUSE H{alpha} AND FUV CONTINUUM BACKGROUNDS: ON THE ORIGINS OF THE DIFFUSE H{alpha} BACKGROUND

    SciTech Connect

    Seon, Kwang-Il; Kim, Il-Joong; Shinn, Jong-Ho; Han, Wonyong; Witt, Adolf; Edelstein, Jerry; Min, Kyoung-Wook

    2011-12-20

    We compare the diffuse H{alpha} map of our Galaxy with the FUV (1370-1710 A) continuum map. The H{alpha} intensity correlates well with the FUV intensity. The H{alpha}/FUV intensity ratio increases in general with the H{alpha} intensity and the FUV hardness ratio (1370-1520 A to 1560-1710 A), implying that late OB stars may be the main source of the H{alpha} recombination line at high latitudes. The variation of the H{alpha} intensity as a function of the Galactic latitude is also very similar to that of the FUV intensity. The results likely suggest that not only the original radiation sources of the H{alpha} and FUV backgrounds but also the radiative transfer mechanisms responsible for the diffuse backgrounds are largely common. Therefore, we propose a scenario wherein the H{alpha} background at high latitudes is mostly composed of two components, H{alpha} photons produced by in situ recombination at the ionized regions around late OB stars and dust-scattered light of the H{alpha} photons originating from late OB stars.

  17. Analysis of radiation risk from alpha particle component of solar particle events

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

    1994-01-01

    The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

  18. Analysis of radiation risk from alpha particle component of soalr particle events

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

    1994-01-01

    The Solar Particle Events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and Linear Energy Transfer (LET) spectra in shielding are discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

  19. Direct radiative effects induced by intense desert dust outbreaks over the broader Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Obiso, Vincenzo; Vendrell, Lluis; Basart, Sara; Jorba, Oriol; Pérez Garcia-Pando, Carlos; Hatzianastassiou, Nikos; Gassó, Santiago; Baldasano, Jose Maria

    2016-04-01

    Throughout the year, under favorable conditions, massive loads of mineral particles originating in the northern African and Middle East deserts are transported over the Mediterranean basin. Due to their composition and size, dust aerosols perturb the Earth-Atmosphere system's energy budget interacting directly with the shortwave (SW) and longwave (LW) radiation. The present study aims to compute the Mediterranean dust outbreaks' direct radiative effects (DREs) as well as to assess the effect of including dust DREs in numerical simulations of a regional model. To this aim, 20 intense dust outbreaks have been selected based on their spatial coverage and intensity. Their identification, over the period 2000-2013, has been achieved through an objective and dynamic algorithm which utilizes as inputs daily satellite retrievals derived by the MODIS-Terra, EP-TOMS and OMI-Aura sensors. For each outbreak, two simulations of the NMMB/BSC-Dust model were made for a forecast period of 84 hours, with the model initialized at 00 UTC of the day when the dust outbreak was ignited, activating (RADON) and deactivating (RADOFF) dust-radiation interactions. The simulation domain covers the northern Africa, the Middle East and Europe at 0.25° x 0.25° horizontal resolution, for 40 hybrid sigma pressure levels up to 50 hPa. The instantaneous and regional DREs have been calculated at the top of the atmosphere (TOA), into the atmosphere (ATMAB), and at surface, for the downwelling (SURF) and the absorbed (NETSURF) radiation, for the SW, LW and NET (SW+LW) radiation. The interaction between dust aerosols and NET radiation, locally leads to an atmospheric warming (DREATMAB) by up to 150 Wm-2, a surface cooling (DRENETSURF) by up to 250 Wm-2 and a reduction of the downwelling radiation at the surface (DRESURF) by up to 300 Wm-2. At TOA, DREs are mainly negative (down to -150 Wm-2) indicating a cooling of the Earth-Atmosphere system, although positive values (up to 50 Wm-2) are encountered

  20. Observation of intense terahertz-wave coherent synchrotron radiation at LEBRA

    NASA Astrophysics Data System (ADS)

    Sei, Norihiro; Ogawa, Hiroshi; Hayakawa, Ken; Tanaka, Toshinari; Hayakawa, Yasushi; Nakao, Keisuke; Sakai, Takeshi; Nogami, Kyoko; Inagaki, Manabu

    2013-01-01

    We observed intense coherent synchrotron radiation (CSR) in the terahertz region using an S-band linac at the Laboratory for Electron Beam Research and Application at Nihon University. The evolution of the CSR power was measured, and the CSR reflected in the vacuum chamber of the bending magnet could be extracted through the quartz window for a few tens of picoseconds. The long wave packet of the delayed CSR in the autocorrelation suggests that the delayed CSR was the non-resonant ring-down of the vacuum chamber of the bending magnet. To design a high-energy accelerator, it is necessary to decrease high-energy photons resulting from Compton backscattering with intense CSR.

  1. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-01-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  2. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-06-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  3. High-intensity power-resolved radiation imaging of an operational nuclear reactor.

    PubMed

    Beaumont, Jonathan S; Mellor, Matthew P; Villa, Mario; Joyce, Malcolm J

    2015-01-01

    Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors. PMID:26450669

  4. High-intensity power-resolved radiation imaging of an operational nuclear reactor

    NASA Astrophysics Data System (ADS)

    Beaumont, Jonathan S.; Mellor, Matthew P.; Villa, Mario; Joyce, Malcolm J.

    2015-10-01

    Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors.

  5. Radiation emission from ultra-relativistic plasma electrons in short-intense laser light interactions

    NASA Astrophysics Data System (ADS)

    Ondarza-Rovira, R.; Boyd, TJM

    2016-05-01

    Intense femtosecond laser light incident on overcritical density plasmas has shown to emit a prolific number of high-order harmonics of the driver frequency, with spectra characterised by power-law decays. When the laser pulse is p-polarised, plasma effects do modify the harmonic spectrum, weakening the so-called universal decay index p = 8/3 to 5/3. In this work appeal is made to a single particle radiation model in support of the predictions from particle-in-cell (PIC) simulations. Using these, we further show that the emission radiated by electrons -those that are relativistically accelerated inside the plasma, after being expelled into vacuum, the so-called Brunel electrons- is characterised not only by the plasma line but also by ultraviolet harmonic orders characterised by the 5/3 decay index.

  6. Simple tool for prediction of parotid gland sparing in intensity-modulated radiation therapy

    SciTech Connect

    Gensheimer, Michael F.; Hummel-Kramer, Sharon M.; Cain, David; Quang, Tony S.

    2015-10-01

    Sparing one or both parotid glands is a key goal when planning head and neck cancer radiation treatment. If the planning target volume (PTV) overlaps one or both parotid glands substantially, it may not be possible to achieve adequate gland sparing. This finding results in physicians revising their PTV contours after an intensity-modulated radiation therapy (IMRT) plan has been run and reduces workflow efficiency. We devised a simple formula for predicting mean parotid gland dose from the overlap of the parotid gland and isotropically expanded PTV contours. We tested the tool using 44 patients from 2 institutions and found agreement between predicted and actual parotid gland doses (mean absolute error = 5.3 Gy). This simple method could increase treatment planning efficiency by improving the chance that the first plan presented to the physician will have optimal parotid gland sparing.

  7. Influence of low-intensity laser radiation on degree of oxygenation and speed microcirculation of blood

    NASA Astrophysics Data System (ADS)

    Korolevich, Alexander N.; Dubina, Natali S.; Vecherinski, Sergei I.

    2000-11-01

    The paper investigated in vivo the influence of low-intensity laser radiation (he-Ne laser with wavelength 0,63 nm) on the mean velocity of their movement. It is known that characteristic of cardiovascular diseases (CVD) are microcirculation disturbances and disorder in rheological properties of blood. Therefore these investigations were carried out on cardiac ischemia patients. The blood perfusion valve and the mean velocity were measured by the method of photon correlation spectroscopy with the use of fiber optic cables. As the radiation source, a semiconductor laser with wavelength 780 nm (0,8 mW) was used. It has been found that, between the erythrocytes and the mean velocity of their movement there is an inverse dependence on the time of irradiation of patients.

  8. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    SciTech Connect

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B.

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  9. High-intensity power-resolved radiation imaging of an operational nuclear reactor

    PubMed Central

    Beaumont, Jonathan S.; Mellor, Matthew P.; Villa, Mario; Joyce, Malcolm J.

    2015-01-01

    Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors. PMID:26450669

  10. Influence of low-intensity laser radiation on human blood microcirculation

    NASA Astrophysics Data System (ADS)

    Korolevich, Alexander N.; Dubina, Natali S.; Vecherinski, Sergei I.

    2000-05-01

    The paper investigated in vivo the influence of low- intensity laser radiation (He-Ne laser with wavelength 0.63 nm) on the relative value of perfusion (the product of the number of particles moving in the volume being investigated into the mean velocity of their movement) of human blood erythrocytes and the mean velocity of their movement. It is known that characteristic of cardiovascular diseases are microcirculation disturbances and disorder in rheological properties of blood. Therefore these investigations were carried out on cardiac ischemia patients.

  11. [The physical mechanism of the effect of low-intensity electromagnetic radiation on biological cells].

    PubMed

    Emets, B G

    1999-01-01

    The presence of dissolved air and air in the free form (bubbles) was taken into account in the study of electromagnetic radiation on biological cells. It is shown that, upon movement in a temperature gradient field, some bubbles increase in size due to the dissolving of others and the coalescence of bubbles during collisions. As a result, the concentration of dissolved air decreases, which leads to cell responses. It is shown that the temperature gradient needed for substantial degassing can be generated by electromagnetic fields of low intensities. PMID:10439876

  12. Primary photophysical processes which define the biological and therapeutic effect of low-intensity laser radiation

    NASA Astrophysics Data System (ADS)

    Mostovnikov, Vasili A.; Mostovnikova, Galina R.; Plavski, Vitali Y.; Plavskaja, Ljudmila G.; Morozova, Raisa P.

    1995-01-01

    It is shown that reversible conformations (changes of spatial structure) of the cell components, responsible for the metabolic processes regulation, are the basis of biological activity and as a consequence therapeutic effect of low-intensity laser radiation. The physical mechanism of these changes is the reorientation of high regulated anisotropic parts-domains with the liquid- crystalline type of ordering due to the interaction between electric field of the laser lightwave and integral electric dipole of the domain (light induced analogue of Frederix's effect).

  13. New 33 GHz Measurements of the Cosmic Background RadiationIntensity

    SciTech Connect

    De Amici, G.; Smoot, G.; Friedman, S.G.; Witebsky, C.

    1985-03-01

    New measurements have been made of the intensity of the cosmic background radiation (CBR) at 33 GHz (0.91 cm). The experiment was part of a larger effort to measure the spectrum of the CBR between 2.5 and 90 GHz (12 and 0.33 cm). Details are given of the experimental equipment and measurement procedures. The results of measurements made in 1982 and 1983 are presented and discussed in relation to preliminary results from the other radiometers. The measured value, T{sub CBR} = (2.81 {+-} 0.12) K, is in very good agreement both with those previously published and those reported by our collaborators.

  14. Results of using low-intensity laser radiation for plumbum intoxication

    NASA Astrophysics Data System (ADS)

    Dejneka, S. Y.

    1999-11-01

    We have studied the noninvasive effect of low-intensive laser impulse radiation in the infrared spectrum region on the liver projection site in experimental lead intoxication achieved by means of intragastric administration of Pb acetate to albino rats over a period of 30 days in a dose of 30 mg/kg. We determined a number of indices in laboratory animals which characterized the state of the nervous system, immune system, muscular performance efficiency. We have also investigated the hematologic indices and the blood and urinary delta-aminolevulinic acid content as well as the plumbum levels in the blood, urine and the animals' inner organs.

  15. Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study.

    PubMed

    Lee, Katrina; Lenards, Nishele; Holson, Janice

    2016-01-01

    The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient׳s neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to the hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient׳s data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain. PMID:26235550

  16. Intensity-modulated radiation therapy to bilateral lower limb extremities concurrently: a planning case study

    SciTech Connect

    Fitzgerald, Emma Miles, Wesley; Fenton, Paul; Frantzis, Jim

    2014-09-15

    Non-melanomatous skin cancers represent 80% of all newly diagnosed cancers in Australia with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being the most common. A previously healthy 71-year-old woman presented with widespread and tender superficial skin cancers on the lower bilateral limbs. External beam radiation therapy through the use of intensity-modulated radiation therapy (IMRT) was employed as the treatment modality of choice as this technique provides conformal dose distribution to a three-dimensional treatment volume while reducing toxicity to surrounding tissues. The patient was prescribed a dose of 60 Gy to the planning target volume (PTV) with 1.0 cm bolus over the ventral surface of each limb. The beam arrangement consisted of six treatment fields that avoided entry and exit through the contralateral limb. The treatment plans met the International Commission on Radiation Units and Measurements (ICRU) guidelines and produced highly conformal dosimetric results. Skin toxicity was measured against the National Cancer Institute: Common Terminology Criteria for Adverse Events (NCI: CTCAE) version 3. A well-tolerated treatment was delivered with excellent results given the initial extent of the disease. This case study has demonstrated the feasibility and effectiveness of IMRT for skin cancers as an alternative to surgery and traditional superficial radiation therapy, utilising a complex PTV of the extremities for patients with similar presentations.

  17. Reirradiation of spinal metastases with intensity-modulated radiation therapy: an analysis of 23 patients

    PubMed Central

    Kawashiro, Shohei; Harada, Hideyuki; Katagiri, Hirohisa; Asakura, Hirofumi; Ogawa, Hirofumi; Onoe, Tsuyoshi; Sumita, Kiyomi; Murayama, Shigeyuki; Murata, Hideki; Nemoto, Kenji; Takahashi, Mitsuru; Nishimura, Tetsuo

    2016-01-01

    This study aimed to evaluate the efficacy and safety of reirradiation with intensity-modulated radiation therapy (IMRT) for spinal metastases. We retrospectively analyzed 23 patients with spinal metastases who underwent IMRT reirradiation between December 2006 and July 2013. We evaluated the spinal radiation doses during the first and second radiation therapy courses, the interval between the courses, and the clinical outcomes after reirradiation, including skeletal-related events, local control rates (LCRs), overall survival (OS), and toxicities. The median time from the first irradiation to reirradiation was 13 months (range, 2–75 months). The median reirradiation dose delivered to 90% of the planning target volume was 24.5 Gy in 5 fractions (range, 14.7–50 Gy in 3–25 fractions). Nineteen patients experienced pain at reirradiation, and 15 of these attained pain relief. Two of the three patients with paresis in the upper or lower extremities upon initiation of reirradiation demonstrated improvement. Local progression was identified in four patients. The median time to local progression was 37 months. The 1- and 2-year LCRs after reirradiation were 88% and 75%, respectively. The 1- and 2-year OS rates after reirradiation were 45% and 20%, respectively, with a median OS of 12 months. No late toxicities occurred. In conclusion, spinal metastasis reirradiation using IMRT appears safe; pain relief and paresis improvement and/or prevention can be expected, along with a reduced risk of radiation-induced toxicity, especially in the spinal cord. PMID:26662113

  18. Alpha slow-moving high-density-lipoprotein subfraction in serum of a patient with radiation enteritis and peritoneal carcinosis

    SciTech Connect

    Peynet, J.; Legrand, A.; Messing, B.; Thuillier, F.; Rousselet, F.

    1989-04-01

    An alpha slow-moving high-density-lipoprotein (HDL) subfraction was seen in a patient presenting with radiation enteritis and peritoneal carcinosis, who was given long-term cyclic parenteral nutrition. This subfraction, observed in addition to normal HDL, was precipitated with low-density lipoproteins (LDL) and very-low-density lipoproteins (VLDL) by sodium phosphotungstate-magnesium chloride. The patient's serum lipoproteins were analyzed after fractionation by density gradient ultracentrifugation. The alpha slow-moving HDL floated in the ultracentrifugation subfractions with densities ranging from 1.028 to 1.084 kg/L, and their main apolipoproteins included apolipoprotein E in addition to apolipoprotein A-I. These HDL were larger than HDL2. The pathogenesis of this unusual HDL subfraction is hypothesized.

  19. Determination of plume temperature distribution based on the ratios of the radiation intensities of multiple CO2 lines

    NASA Astrophysics Data System (ADS)

    Cieszczyk, S.

    2015-05-01

    New inversion scheme for gas temperature distribution retrieval utilized CO2 spectrum between 2350 cm-1 and 2400 cm-1 is proposed. Inversion model is build base on neural networks. Considered spectral remote sensing method is commonly used for industrial and environmental monitoring. It is a passive single-ended sensor technique in which radiation intensity emerging from a studied object is analyzed. Quantitative investigation of heated gas radiation emission to determine temperature and gas mixture by infrared spectroscopy requires two components apart from optical radiation sensor. First appropriate spectral database and second efficient inversion techniques. In this study calculation of one-dimensional radiative transfer equation have been used for simulation of spectral radiation intensity. To increase quality of retrieval a spectrum preprocessing and feature extraction method is applied. Simulated spectra were parameterized and expressed as ratios of intensities of multiple rotational lines. Each neural network estimates temperature (NN response) at one point on studied path basing on given spectrum (NN input).

  20. DEVELOPMENT OF AN ON-LINE, REAL-TIME ALPHA RADIATION MEASURING INSTRUMENT FOR LIQUID STREAMS

    SciTech Connect

    1996-11-22

    The Department of Energy (DOE) has expressed a need for an on-line, real-time instrument for assaying alpha-emitting radionuclides (uranium and the transuranics) in effluent waters leaving DOE sites to ensure compliance with regulatory limits. Due to the short range of alpha particles in water ({approximately}40 Tm), it is necessary now to intermittently collect samples of water and send them to a central laboratory for analysis. A lengthy and costly procedure is used to separate and measure the radionuclides from each sample. Large variations in radionuclide concentrations in the water may go undetected due to the sporadic sampling. Even when detected, the reading may not be representative of the actual stream concentration. To address these issues, Tecogen, a division of Thermo Power Corporation, a Thermo Electron company, is developing a real-time, field-deployable, alpha monitor based on a solid-state silicon wafer semiconductor (patent pending, to be assigned to the Department of Energy). The Thermo Alpha Monitor (TAM) will serve to monitor effluent water streams (Subsurface Contaminants Focus Area) and will be suitable for process control of remediation as well as decontamination and decommissioning operations, such as monitoring scrubber or rinse water radioactivity levels (Mixed Waste Focus Area and D&D Focus Area). It would be applicable for assaying other liquids, such as oil, or solids after proper preconditioning. Rapid isotopic alpha air monitoring is also possible using this technology. This instrument for direct counting of alpha-emitters in aqueous streams is presently being developed by Thermo Power under a development program funded by the DOE Environmental Management program (DOE-EM), administered by the Morgantown Energy Technology Center (METC). Under this contract, Thermo Power has demonstrated a solid-state, silicon-based semiconductor instrument, which uses a proprietary film-based collection system to quantitatively extract the

  1. Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

    PubMed

    Slatkin, D N; Stoner, R D; Rosander, K M; Kalef-Ezra, J A; Laissue, J A

    1988-06-01

    Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal injection of 10B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since 10B concentrations were approximately equal to 3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from alpha and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LD50 dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a major determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo. PMID:3375251

  2. Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

    PubMed Central

    Slatkin, D N; Stoner, R D; Rosander, K M; Kalef-Ezra, J A; Laissue, J A

    1988-01-01

    Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal injection of 10B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since 10B concentrations were approximately equal to 3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from alpha and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LD50 dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a major determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo. Images PMID:3375251

  3. Combination of pGL1-TNF-alpha gene and radiation (proton and gamma-ray) therapy against brain tumor.

    PubMed

    Gridley, D S; Li, J; Kajioka, E H; Andres, M L; Moyers, M F; Slater, J M

    2000-01-01

    The major goal of this study was to determine if treatment with the newly constructed plasmid vector for tumor necrosis factor-alpha (pGL1-TNF-alpha) could enhance the radiation-induced growth reduction of C6 rat glioma. In addition, two different forms of ionizing radiation (gamma-rays and protons) were utilized. Body and spleen mass, leukocyte blastogenesis, and flow cytometry analysis of cell populations in blood and spleen were performed to detect toxicity, if any, and to identify mechanisms that may correlate with the anti-tumor action of combination therapy. C6 tumor cells were implanted subcutaneously into athymic mice and allowed to become established before treatment initiation. pGL1-TNF-alpha was injected into the implanted tumors, which were then irradiated 16-18 hr later; each modality was administered three times over 8-9 days. The addition of pGL1-TNF-alpha significantly enhanced the anti-tumor effect of radiation (p < 0.05). The effect was more than additive, since pGL1-TNF-alpha alone did not slow tumor progression and radiation alone had only a modest effect. Administration of pGL1-TNF-alpha together with proton radiation resulted in tumor volumes that were 23% smaller than those following pGL1-TNF-alpha + gamma-ray treatment; a similar differential in tumor size was observed in the groups receiving only radiation. Body weights and blood and spleen cell analyses did not reveal treatment-related toxicity. High basal proliferation of blood leukocytes and increased B cell levels in the spleen were associated with pGL1-TNF-alpha + 60Co (gamma-radiation) or proton treatment. Overall, the results suggest that the pGL1-TNF-alpha/radiation combination is effective and safe under the conditions employed. This is the first study to combine gene and proton radiation therapy and to show, under controlled experimental conditions, that proton radiation may have a greater effect against malignant tumors compared to the same physical dose of gamma-radiation. PMID

  4. An angular momentum approximation for molecular collisions in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    An approximation to a previously presented rigorous description of molecular (atom-atom) collisions occurring in the presence of intense radiation is investigated. This rigorous description explicitly considers the angular momentum transferred between the molecule and the radiation field in the absorption or emission of a photon, but involves a complicated system of close-coupled equations which must be solved independently for each projection M of the initial, total molecular angular momentum. (This is a direct consequence of the lack of rotational invariance in the molecule-field problem). These equations are solved for a model system which mimics the collision of a halogen with a rare gas atom. Empirical observations made in the course of performing these calculations lead to the development of an approximation which avoids the repeated calculations for each initial M. This orientational average approximation greatly reduces the effort required to describe the system, and for the model calculation, yields accurate results for field intensities as high as 10 GW/sq cm.

  5. The doppler frequency shift caused by the inhomogeneities of a medium induced by pulses of intense laser radiation

    NASA Astrophysics Data System (ADS)

    Rozanov, N. N.; Kiselev, Al. S.; Kiselev, An. S.

    2008-08-01

    Self-reflection of pulses of intense laser radiation from an inhomogeneity induced by them in a medium with fast optical nonlinearity is analyzed. The reflected radiation is characterized by a considerable Doppler shift and by a signal magnitude that is sufficient for experimental detection.

  6. The calculated risk of fatal secondary malignancies from intensity-modulated radiation therapy

    SciTech Connect

    Kry, Stephen F.; Salehpour, Mohammad . E-mail: msalehpour@mdanderson.org; Followill, David S.; Stovall, Marilyn; Kuban, Deborah A.; White, R. Allen; Rosen, Isaac I.

    2005-07-15

    Purpose: Out-of-field radiation doses to normal tissues may be associated with an increased risk of secondary malignancies, particularly in long-term survivors. Step-and-shoot intensity-modulated radiation therapy (IMRT), an increasingly popular treatment modality, yields higher out-of-field doses than do conventional treatments, because of an increase in required monitor units (beam-on time). Methods: We used published risk coefficients (NRCP Report 116) and out-of-field dose equivalents to multiple organ sites to estimate a conservative maximal risk of fatal secondary malignancy associated with 6 IMRT approaches and 1 conventional external-beam approach for prostate cancer. Results: Depending on treatment energy, the IMRT treatments required 3.5-4.9 times as many monitor units to deliver as did the conventional treatment. The conservative maximum risk of fatal second malignancy was 1.7% for conventional radiation, 2.1% for IMRT using 10-MV X-rays, and 5.1% for IMRT using 18-MV X-rays. Intermediate risks were associated with IMRT using 6-MV X-rays: 2.9% for treatment with the Varian accelerator and 3.7% for treatment with the Siemens accelerator, as well as using 15-MV X-rays: 3.4% (Varian) and 4.0% (Siemens). Conclusion: The risk of fatal secondary malignancy differed substantially between IMRT and conventional radiation therapy for prostate cancer, as well as between different IMRT approaches. Perhaps this risk should be considered when choosing the optimal treatment technique and delivery system for patients who will undergo prostate radiation.

  7. Astrophysical Ionizing Radiation and Earth: A Brief Review and Census of Intermittent Intense Sources

    NASA Astrophysics Data System (ADS)

    Melott, Adrian L.; Thomas, Brian C.

    2011-05-01

    Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review, we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities, ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere; on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. Both photons (e.g., X-rays) and high-energy protons and other nuclei (often called "cosmic rays") constitute hazards. For either species, one of the mechanisms that comes into play even at moderate intensities is the ionization of Earth's atmosphere, which leads through chemical changes (specifically, depletion of stratospheric ozone) to increased ultraviolet B flux from the Sun reaching the surface. UVB is extremely hazardous to most life due to its strong absorption by the genetic material DNA and subsequent breaking of chemical bonds. This often leads to mutation or cell death. It is easily lethal to the microorganisms that lie at the base of the food chain in the ocean. We enumerate the known sources of radiation and characterize their intensities at Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval," our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate-level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note

  8. Astrophysical ionizing radiation and Earth: a brief review and census of intermittent intense sources.

    PubMed

    Melott, Adrian L; Thomas, Brian C

    2011-05-01

    Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review, we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities, ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere; on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. Both photons (e.g., X-rays) and high-energy protons and other nuclei (often called "cosmic rays") constitute hazards. For either species, one of the mechanisms that comes into play even at moderate intensities is the ionization of Earth's atmosphere, which leads through chemical changes (specifically, depletion of stratospheric ozone) to increased ultraviolet B flux from the Sun reaching the surface. UVB is extremely hazardous to most life due to its strong absorption by the genetic material DNA and subsequent breaking of chemical bonds. This often leads to mutation or cell death. It is easily lethal to the microorganisms that lie at the base of the food chain in the ocean. We enumerate the known sources of radiation and characterize their intensities at Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval," our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate-level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note

  9. DEVELOPMENT OF AN ON-LINE, REAL-TIME ALPHA RADIATION MEASURING INSTRUMENT FOR LIQUID STREAMS

    SciTech Connect

    Unknown

    1999-03-14

    The US Department of Energy (DOE) has expressed a need for an on-line, real-time instrument for assaying alpha-emitting radionuclides (uranium and the transuranics) in effluent waters leaving DOE sites to ensure compliance with regulatory limits. Due to the short range of alpha particles in water ({approximately}40 Im), it is necessary now to intermittently collect samples of water and send them to a central laboratory for analysis. A lengthy and costly procedure is used to separate and measure the radionuclides from each sample. Large variations in radionuclide concentrations in the water may go undetected due to the sporadic sampling. Even when detected, the reading may not be representative of the actual stream concentration. To address these issues, the Advanced Technologies Group of Thermo Power Corporation (a Thermo Electron company) is developing a real-time, field-deployable alpha monitor based on a solid-state silicon wafer semiconductor (US Patent 5,652,013 and pending, assigned to the US Department of Energy). The Thermo Water Alpha Monitor will serve to monitor effluent water streams (Subsurface Contaminants Focus Area) and will be suitable for process control of remediation as well as decontamination and decommissioning (D and D) operations, such as monitoring scrubber or rinse water radioactivity levels (Mixed Waste, Plutonium, and D and D Focus Area). It would be applicable for assaying other liquids, such as oil, or solids after proper preconditioning. Rapid isotopic alpha air monitoring is also possible using this technology. This report details the program's accomplishments to date. Most significantly, the Alpha Monitoring Instrument was successfully field demonstrated on water 100X below the Environmental Protection Agency's proposed safe drinking water limit--down to under 1 pCi/1. During the Field Test, the Alpha Monitoring Instrument successfully analyzed isotopic uranium levels on a total of five different surface water, process water, and

  10. 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.

  11. Acoustic intensity-based method for sound radiations in a uniform flow.

    PubMed

    Yu, Chao; Zhou, Zhengfang; Zhuang, Mei

    2009-11-01

    An acoustic intensity-based method (AIBM) is extended and verified for predicting sound radiation in a subsonic uniform flow. The method assumes that the acoustic propagation is governed by the modified Helmholtz equation on and outside of a control surface, which encloses all the noise sources and nonlinear effects. With acoustic pressure derivative and its co-located acoustic pressure as input from an open control surface, the unique solution of the modified Helmholtz equation is obtained by solving the least squares problem. The AIBM is coupled with near-field Computational Fluid Dynamics (CFD)/Computational Aeroacoustics (CAA) methods to predict sound radiation of model aeroacoustic problems. The effectiveness of this hybrid approach has been demonstrated by examples of both tonal and broadband noise. Since the AIBM method is stable and accurate based on the input acoustic data from an open surface in a radiated field, it is therefore advantageous for the far-field prediction of aerodynamics noise propagation when an acoustic input from a closed control surface, like the Ffowcs Williams-Hawkings surface, is not available [Philos. Trans. R. Soc. London, Ser. A 264, 321-342 (1969)]. PMID:19894800

  12. Correcting radiation survey data to account for increased leakage during intensity modulated radiotherapy treatments

    SciTech Connect

    Kairn, T.; Crowe, S. B.; Trapp, J. V.

    2013-11-15

    Purpose: Intensity modulated radiotherapy (IMRT) treatments require more beam-on time and produce more linac head leakage to deliver similar doses to conventional, unmodulated, radiotherapy treatments. It is necessary to take this increased leakage into account when evaluating the results of radiation surveys around bunkers that are, or will be, used for IMRT. The recommended procedure of applying a monitor-unit based workload correction factor to secondary barrier survey measurements, to account for this increased leakage when evaluating radiation survey measurements around IMRT bunkers, can lead to potentially costly overestimation of the required barrier thickness. This study aims to provide initial guidance on the validity of reducing the value of the correction factor when applied to different radiation barriers (primary barriers, doors, maze walls, and other walls) by evaluating three different bunker designs.Methods: Radiation survey measurements of primary, scattered, and leakage radiation were obtained at each of five survey points around each of three different radiotherapy bunkers and the contribution of leakage to the total measured radiation dose at each point was evaluated. Measurements at each survey point were made with the linac gantry set to 12 equidistant positions from 0° to 330°, to assess the effects of radiation beam direction on the results.Results: For all three bunker designs, less than 0.5% of dose measured at and alongside the primary barriers, less than 25% of the dose measured outside the bunker doors and up to 100% of the dose measured outside other secondary barriers was found to be caused by linac head leakage.Conclusions: Results of this study suggest that IMRT workload corrections are unnecessary, for survey measurements made at and alongside primary barriers. Use of reduced IMRT workload correction factors is recommended when evaluating survey measurements around a bunker door, provided that a subset of the measurements used in

  13. Quantitative analysis of tomotherapy, linear-accelerator-based 3D conformal radiation therapy, intensity-modulated radiation therapy, and 4D conformal radiation therapy

    NASA Astrophysics Data System (ADS)

    Cho, Jae-Hwan; Lee, Hae-Kag; Dong, Kyung-Rae; Chung, Woon-Kwan; Lee, Jong-Woong; Park, Hoon-Hee

    2012-04-01

    This study quantified, evaluated and analyzed the radiation dose to which tumors and normal tissues were exposed in 3D conformal radiation therapy (CRT), intensity-modulated radiation therapy (IMRT) and tomotherapy by using a dose volume histogram (DVH) that represented the volume dose and the dose distribution of anatomical structures in the evaluation of treatment planning. Furthermore, a comparison was made for the dose to the gross tumor volume (GTV) and the planning target volume (PTV) of organ to be treated based on the change in field size for three- and four-dimensional computed tomography (3D-CT and 4D-CT) (gating based) and in the histogram with a view to proving the usefulness of 4D-CT therapy, which corresponds to respiration-gated radiation therapy. According to the study results, a comparison of 3D CRT, IMRT with a linear accelerator (LINAC), and tomotherapy demonstrated that the GTV of the cranium was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 5.2% and 4.6%, respectively. The GTV of the neck was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 6.5% and 2.0%, respectively. The GTV of the pelvis was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 8.6% and 3.7%, respectively. When the comparison was made for the 3D-CT and the 4D-CT (gating based) treatment equipment, the GTV and the PTV became smaller for 4D-CT treatment planning than for 3D-CT, which could reduce the area in which normal tissues in the surroundings are exposed to an unnecessary radiation dose. In addition, when 4D-CT treatment planning (gating based) was used, the radiation dose could be concentrated on the GTV, CTV or PTV, which meant that the treatment area exceeded that when 3D-CT's treatment planning was used. Moreover, the radiation dose on nearby normal tissues could be reduced. When 4D-CT treatment planning (gating based) was utilized, unnecessary areas that were exposed to a radiation dose could be reduced more than they could

  14. Enhancement of Lyman-. alpha. radiation following foil-induced dissociation of fast ionic hydrogen clusters H sub n sup +

    SciTech Connect

    Farizon, M.; Clouvas, A.; de Castro Faria, N.V.; Farizon-Mazuy, B.; Gaillard, M.J.; Gerlic, E. ); Denis, A.; Desesquelles, J.; Ouerdane, Y. )

    1991-01-01

    We have measured the Lyman-{alpha} radiation following foil breakup of hydrogen ionic clusters H{sub {ital n}}{sup +} ({ital n}=2 and {ital n}=3 to 61, odd) with velocities above and around the Bohr velocity. An enhancement of this radiation was observed and could reach a factor of 3 with respect to the proton case of the same velocity. Cluster mass number, velocity, and thickness dependences of the relative population of the 2{ital p} state in hydrogen fragments following H{sub {ital n}}{sup +} foil dissociation have been extracted. A specific collective effect on the 2{ital p}-state hydrogen has been observed and interpreted in terms of charge-exchange processes.

  15. Combination of intensity-based image registration with 3D simulation in radiation therapy

    NASA Astrophysics Data System (ADS)

    Li, Pan; Malsch, Urban; Bendl, Rolf

    2008-09-01

    Modern techniques of radiotherapy like intensity modulated radiation therapy (IMRT) make it possible to deliver high dose to tumors of different irregular shapes at the same time sparing surrounding healthy tissue. However, internal tumor motion makes precise calculation of the delivered dose distribution challenging. This makes analysis of tumor motion necessary. One way to describe target motion is using image registration. Many registration methods have already been developed previously. However, most of them belong either to geometric approaches or to intensity approaches. Methods which take account of anatomical information and results of intensity matching can greatly improve the results of image registration. Based on this idea, a combined method of image registration followed by 3D modeling and simulation was introduced in this project. Experiments were carried out for five patients 4DCT lung datasets. In the 3D simulation, models obtained from images of end-exhalation were deformed to the state of end-inhalation. Diaphragm motions were around -25 mm in the cranial-caudal (CC) direction. To verify the quality of our new method, displacements of landmarks were calculated and compared with measurements in the CT images. Improvement of accuracy after simulations has been shown compared to the results obtained only by intensity-based image registration. The average improvement was 0.97 mm. The average Euclidean error of the combined method was around 3.77 mm. Unrealistic motions such as curl-shaped deformations in the results of image registration were corrected. The combined method required less than 30 min. Our method provides information about the deformation of the target volume, which we need for dose optimization and target definition in our planning system.

  16. Intensive swimming exercise-induced oxidative stress and reproductive dysfunction in male wistar rats: protective role of alpha-tocopherol succinate.

    PubMed

    Manna, Indranil; Jana, Kuladip; Samanta, Prabhat Kumar

    2004-04-01

    In the present study, 30 male rats (age 3 mos, Wt 128.6 +/- 3.7 g) were randomly divided into Control group (CG), Experimental group (EG), and Supplemented group (SG), 10 per group. An exercise protocol (3 hrs swimming per day, 5 days a week for 4 weeks) was followed in EG and SG, with no exercise in CG. In SG, alpha-tocopherol succinate was injected sub-cutaneously at a dose of 50 mg x kg(- 1) per body weight per day. After 4 weeks of exercise, significant diminutions (p < 0.05) were noted in somatic indices of testes and accessory sex organs; seminiferous tubuler diameter (STD); testicular (delta (5), 3 beta-hydroxysteroid dehydrogenase delta(5), 3 beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activities; plasma levels of testosterone (T), luteinizing hormone (LH); preleptotine spermatocytes (pLSc), mid-pachytene spermatocytes (mPSc), and Stage 7 spermatids (7 Sd); testicular alpha-tocopherol and glutathione (GSH) content; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione-s-transferase (GST) activities in EG when compared to CG. Moreover, a significant elevation (p < 0.05) in malondialdehyde (MDA) was found in testes of EG compared to CG. No significant alteration was noted in body weight among the groups. Co-administration of alpha-tocopherol succinate restored the above parameters. Intensive swimming exercise-induced oxidative stress causes dysfunction in the male reproductive system, which can be protected by alpha-tocopherol succinate. PMID:15064426

  17. Accelerated alpha radiation damage in a ceramic waste form, interim results

    SciTech Connect

    Frank, S. M.; Johnson, S. G.; Moschetti, T. L.; O'Holleran, T. P.; Sinkler, W.; Esh, D.; Goff, K. M.

    1999-11-11

    Interim results are presented on the alpha-decay damage study of a {sup 238}Pu-loaded ceramic waste form (CWF). The waste form was developed to immobilize fission products and transuranic species accumulated from the electrometallurgical treatment of spent nuclear fuel. To evaluate the effects of {alpha}-decay damage on the waste form the {sup 238}Pu-loaded material was analyzed by (1) x-ray diffraction (XRD), (2) microstructure characterization by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with energy and wavelength dispersive spectroscopy (EDS/WDS) and electron diffraction, (3) bulk density measurements and (4) waste form durability, performed by the product consistency test (PCT). While the predominate phase of plutonium in the CWF, PuO{sub 2}, shows the expected unit cell expansion due to {alpha}-decay damage, currently no significant change has occurred to the macro- or microstructure of the material. The major phase of the waste form is sodalite and contains very little Pu, although the exact amount is unknown. Interestingly, measurement of the sodalite phase unit cell is also showing very slight expansion; again, presumably from {alpha}-decay damage.

  18. DEVELOPMENT OF AN ON-LINE, REAL-TIME ALPHA RADIATION MEASURING INSTRUMENT FOR LIQUID STREAMS

    SciTech Connect

    Unknown

    1999-06-16

    Thermo Power Corporation has proven the technical viability of an on-line, real-time alpha radionuclide instrument for aqueous sample analysis through laboratory and initial field tests of the instrument. The instrument has been shown to be isotonically sensitive to extremely low (ten parts per trillion, or femto Curies per liter) levels of a broad range of radioisotopes. Performance enhancement and other scaling data obtained during the course of this investigation have shown that on-line, real-time operation is possible, with a sub 30-minute response time analyzing 20 ppb (30 pCi/1) natural uranium. Now that these initial field tests in Oak Ridge, Tennessee have been successfully completed, Thermo Power plans to conduct comprehensive field tests of the instrument. The purpose of these endurance tests will be to determine the endurance characteristics of the Thermo Alpha Monitor for Water when it is used by non-Thermo Power personnel in a series of one or more extended field tests. Such endurance testing is the vital next step towards the commercialization of the Alpha Monitor. Subsequently, it will be possible to provide the DOE with an instrument that has the capability of obtaining rapid feedback about the concentrations of alpha-emitting isotope contamination in effluent water streams (Subsurface Contaminants Focus Area). It will also be useful for process control of remediation and D and D operations such as monitoring scrubber/rinse water radioactivity levels (Mixed Waste, Plutonium and D and D Focus Areas).

  19. Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy

    SciTech Connect

    Li, Ruijiang; Xing, Lei

    2011-09-15

    Purpose: To propose an alternative radiation therapy (RT) planning and delivery scheme with optimal angular beam sampling and intrabeam modulation for improved dose distribution while maintaining high delivery efficiency. Methods: In the proposed approach, coined as dense angularly sampled and sparse intensity modulated RT (DASSIM-RT), a large number of beam angles are used to increase the angular sampling, leading to potentially more conformal dose distributions as compared to conventional IMRT. At the same time, intensity modulation of the incident beams is simplified to eliminate the dispensable segments, compensating the increase in delivery time caused by the increased number of beams and facilitating the plan delivery. In a sense, the proposed approach shifts and transforms, in an optimal fashion, some of the beam segments in conventional IMRT to the added beams. For newly available digital accelerators, the DASSIM-RT delivery can be made very efficient by concatenating the beams so that they can be delivered sequentially without operator's intervention. Different from VMAT, the level of intensity modulation in DASSIS-RT is field specific and optimized to meet the need of each beam direction. Three clinical cases (a head and neck (HN) case, a pancreas case, and a lung case) are used to evaluate the proposed RT scheme. DASSIM-RT, VMAT, and conventional IMRT plans are compared quantitatively in terms of the conformality index (CI) and delivery efficiency. Results: Plan quality improves generally with the number and intensity modulation of the incident beams. For a fixed number of beams or fixed level of intensity modulation, the improvement saturates after the intensity modulation or number of beams reaches to a certain level. An interplay between the two variables is observed and the saturation point depends on the values of both variables. For all the cases studied here, the CI of DASSIM-RT with 15 beams and 5 intensity levels (0.90, 0.79, and 0.84 for the HN

  20. Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method

    NASA Astrophysics Data System (ADS)

    Rocha, Humberto; Dias, Joana M.; Ferreira, Brígida C.; Lopes, Maria C.

    2013-05-01

    Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better organ sparing and to improve tumor coverage. However, in clinical practice, most of the time, beam directions continue to be manually selected by the treatment planner without objective and rigorous criteria. The goal of this paper is to introduce a novel approach that uses beam’s-eye-view dose ray tracing metrics within a pattern search method framework in the optimization of the highly non-convex BAO problem. Pattern search methods are derivative-free optimization methods that require a few function evaluations to progress and converge and have the ability to better avoid local entrapment. The pattern search method framework is composed of a search step and a poll step at each iteration. The poll step performs a local search in a mesh neighborhood and ensures the convergence to a local minimizer or stationary point. The search step provides the flexibility for a global search since it allows searches away from the neighborhood of the current iterate. Beam’s-eye-view dose metrics assign a score to each radiation beam direction and can be used within the pattern search framework furnishing a priori knowledge of the problem so that directions with larger dosimetric scores are tested first. A set of clinical cases of head-and-neck tumors treated at the Portuguese Institute of Oncology of Coimbra is used to discuss the potential of this approach in the optimization of the BAO problem.

  1. Radiative corrections to e/sup +/e/sup -/ reactions to all orders in. cap alpha. using the renormalization group

    SciTech Connect

    Tsai, Y.S.

    1983-01-01

    Renormalization group technique is used to improve the accuracy of the lowest order radiative corrections in QED. The exponentiation of infrared terms comes automatically. It also leads to exponentiation of the vertex functions. It predicts the existence of conversion of photons into pairs and the result agrees with the Kroll-Wada relation. Kinoshita-Lee-Nauenberg cancellation of mass singularities occurs to all order in ..cap alpha.. in leading log approximation in the final state if we sum over all the final states. Higher order corrections to the order ..cap alpha../sup 3/ asymmetry is shown to be small. The results are used to derive useful formulas for the radiative corrections to processes such as e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/, e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/..gamma.., e/sup +/e/sup -/ ..-->.. hadron continuum, e/sup +/e/sup -/ ..-->.. very narrow resonance such as phi, and e/sup +/e/sup -/ ..-->.. not very narrow resonance such as Z/sup 0/.

  2. Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

    NASA Technical Reports Server (NTRS)

    Weller, C. S.; Meier, R. R.; Tinsley, B. A.

    1971-01-01

    Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

  3. Intense Nanosecond-Pulsed Cavity-Dumped Laser Radiation at 1.04 THz

    NASA Astrophysics Data System (ADS)

    Wilson, Thomas

    2013-03-01

    We report first results of intense far-infrared (FIR) nanosecond-pulsed laser radiation at 1.04 THz from a previously described[2] cavity-dumped, optically-pumped molecular gas laser. The gain medium, methyl fluoride, is pumped by the 9R20 line of a TEA CO2 laser[3] with a pulse energy of 200 mJ. The THz laser pulses contain of 30 kW peak power in 5 nanosecond pulse widths at a pulse repetition rate of 10 Hz. The line width, measured by a scanning metal-mesh FIR Fabry-Perot interferometer, is 100 MHz. The novel THz laser is being used in experiments to resonantly excite coherent ns-pulsed 1.04 THz longitudinal acoustic phonons in silicon doping-superlattices. The research is supported by NASA EPSCoR NNX11AM04A and AFOSR FA9550-12-1-0100 awards.

  4. Matching Intensity-Modulated Radiation Therapy to an Anterior Low Neck Field

    SciTech Connect

    Amdur, Robert J. Liu, Chihray; Li, Jonathan; Mendenhall, William; Hinerman, Russell

    2007-10-01

    When using intensity-modulated radiation therapy (IMRT) to treat head and neck cancer with the primary site above the level of the larynx, there are two basic options for the low neck lymphatics: to treat the entire neck with IMRT, or to match the IMRT plan to a conventional anterior 'low neck' field. In view of the potential advantages of using a conventional low neck field, it is important to look for ways to minimize or manage the problems of matching IMRT to a conventional radiotherapy field. Treating the low neck with a single anterior field and the standard larynx block decreases the dose to the larynx and often results in a superior IMRT plan at the primary site. The purpose of this article is to review the most applicable studies and to discuss our experience with implementing a technique that involves moving the position of the superior border of the low neck field several times during a single treatment fraction.

  5. Measurement of the intensity of the cosmic background radiation at 3. 0 cm

    SciTech Connect

    Friedman, S.D.

    1984-01-01

    The intensity of the cosmic background radiation (CBR) has been measured at a wavelength of 3.0 cm as part of a program to measure th Rayleigh-Jeans spectrum of the CBR at five wavelengths between 0.33 cm and 12 cm. The instrument used is a dual-antenna Dicke-switched radiometer with a double-sideband noise temperature of 490 K and a sensitivity of 46 mK/Hz/sup 1/2/. The entire radiometer is mounted on bearings. The atmospheric emission was measured by rotating the radiometer, and thus directing one antenna to zenith angles of +- 30/sup 0/ and +- 40/sup 0/. 61 references, 24 figures, 18 tables.

  6. Resonance effects in the interaction between a two-level system and intense polychromatic radiation

    NASA Astrophysics Data System (ADS)

    Kocharovskaia, O. A.; Khanin, Ia. I.; Tsaregradskii, V. B.

    1984-02-01

    A theoretical investigation is made of the interaction between a two-level system and an electromagnetic field with an equidistant spectrum having arbitrary independent spectral-component phases (multimode laser radiation). The concept of the generalized Rabi frequencies of a two-level system situated in a polychromatic field is introduced, and the values of these frequencies are calculated. It is shown, that extrema (resonances) whose positions are independent of mode phases exist in the dependence of the population-difference harmonics and the absorption coefficients of individual modes on the intermode interval and the field intensity. The resonances correspond to the coincidence of mode-beat combination frequencies with the generalized Rabi frequencies.

  7. Quality of Intensity Modulated Radiation Therapy Treatment Plans Using a {sup 60}Co Magnetic Resonance Image Guidance Radiation Therapy System

    SciTech Connect

    Wooten, H. Omar Green, Olga; Yang, Min; DeWees, Todd; Kashani, Rojano; Olsen, Jeff; Michalski, Jeff; Yang, Deshan; Tanderup, Kari; Hu, Yanle; Li, H. Harold; Mutic, Sasa

    2015-07-15

    Purpose: This work describes a commercial treatment planning system, its technical features, and its capabilities for creating {sup 60}Co intensity modulated radiation therapy (IMRT) treatment plans for a magnetic resonance image guidance radiation therapy (MR-IGRT) system. Methods and Materials: The ViewRay treatment planning system (Oakwood Village, OH) was used to create {sup 60}Co IMRT treatment plans for 33 cancer patients with disease in the abdominal, pelvic, thorax, and head and neck regions using physician-specified patient-specific target coverage and organ at risk (OAR) objectives. Backup plans using a third-party linear accelerator (linac)-based planning system were also created. Plans were evaluated by attending physicians and approved for treatment. The {sup 60}Co and linac plans were compared by evaluating conformity numbers (CN) with 100% and 95% of prescription reference doses and heterogeneity indices (HI) for planning target volumes (PTVs) and maximum, mean, and dose-volume histogram (DVH) values for OARs. Results: All {sup 60}Co IMRT plans achieved PTV coverage and OAR sparing that were similar to linac plans. PTV conformity for {sup 60}Co was within <1% and 3% of linac plans for 100% and 95% prescription reference isodoses, respectively, and heterogeneity was on average 4% greater. Comparisons of OAR mean dose showed generally better sparing with linac plans in the low-dose range <20 Gy, but comparable sparing for organs with mean doses >20 Gy. The mean doses for all {sup 60}Co plan OARs were within clinical tolerances. Conclusions: A commercial {sup 60}Co MR-IGRT device can produce highly conformal IMRT treatment plans similar in quality to linac IMRT for a variety of disease sites. Additional work is in progress to evaluate the clinical benefit of other novel features of this MR-IGRT system.

  8. Cost-Effectiveness Analysis of Intensity Modulated Radiation Therapy Versus 3-Dimensional Conformal Radiation Therapy for Anal Cancer

    SciTech Connect

    Hodges, Joseph C.; Beg, Muhammad S.; Das, Prajnan; Meyer, Jeffrey

    2014-07-15

    Purpose: To compare the cost-effectiveness of intensity modulated radiation therapy (IMRT) and 3-dimensional conformal radiation therapy (3D-CRT) for anal cancer and determine disease, patient, and treatment parameters that influence the result. Methods and Materials: A Markov decision model was designed with the various disease states for the base case of a 65-year-old patient with anal cancer treated with either IMRT or 3D-CRT and concurrent chemotherapy. Health states accounting for rates of local failure, colostomy failure, treatment breaks, patient prognosis, acute and late toxicities, and the utility of toxicities were informed by existing literature and analyzed with deterministic and probabilistic sensitivity analysis. Results: In the base case, mean costs and quality-adjusted life expectancy in years (QALY) for IMRT and 3D-CRT were $32,291 (4.81) and $28,444 (4.78), respectively, resulting in an incremental cost-effectiveness ratio of $128,233/QALY for IMRT compared with 3D-CRT. Probabilistic sensitivity analysis found that IMRT was cost-effective in 22%, 47%, and 65% of iterations at willingness-to-pay thresholds of $50,000, $100,000, and $150,000 per QALY, respectively. Conclusions: In our base model, IMRT was a cost-ineffective strategy despite the reduced acute treatment toxicities and their associated costs of management. The model outcome was sensitive to variations in local and colostomy failure rates, as well as patient-reported utilities relating to acute toxicities.

  9. Treatment-related complications of radiation therapy after radical prostatectomy: comparative effectiveness of intensity-modulated versus conformal radiation therapy

    PubMed Central

    Crandley, Edwin F; Hegarty, Sarah E; Hyslop, Terry; Wilson, David D; Dicker, Adam P; Showalter, Timothy N

    2014-01-01

    Intensity-modulated radiation therapy (IMRT) is frequently utilized after prostatectomy without strong evidence for an improvement in outcomes compared to conformal radiation therapy (RT). We analyzed a large group of patients treated with RT after radical prostatectomy (RP) to compare complications after IMRT and CRT. The Surveillance, Epidemiology and End Results (SEER)-Medicare database was queried to identify male Medicare beneficiaries aged 66 years or older who underwent prostatectomy with 1+ adverse pathologic features and received postprostatectomy RT between 1995 and 2007. Chi-square test was used to compare baseline characteristics between the treatment groups. First complication events, based upon administrative procedure or diagnosis codes occurring >1 year after start of RT, were compared for IMRT versus CRT groups. Propensity score adjustment was performed to adjust for potential confounders. Multivariable Cox proportional hazards models of time to first complication were performed. A total of 1686 patients were identified who received RT after RP (IMRT = 634, CRT = 1052). Patients treated with IMRT were more likely to be diagnosed after 2004 (P < 0.001), have minimally invasive prostatectomy (P < 0.001) and have positive margins (P = 0.019). IMRT use increased over time. After propensity score adjustment, IMRT was associated with lower rate of gastrointestinal (GI) complications, and higher rate of genitourinary-incontinence complications, compared to CRT. The observed outcomes after IMRT must be considered when determining the optimal approach for postprostatectomy RT and warrant additional study. PMID:24519910

  10. Spherical cluster analysis for beam angle optimization in intensity-modulated radiation therapy treatment planning

    NASA Astrophysics Data System (ADS)

    Bangert, Mark; Oelfke, Uwe

    2010-10-01

    An intuitive heuristic to establish beam configurations for intensity-modulated radiation therapy is introduced as an extension of beam ensemble selection strategies applying scalar scoring functions. It is validated by treatment plan comparisons for three intra-cranial, pancreas, and prostate cases each. Based on a patient specific matrix listing the radiological quality of candidate beam directions individually for every target voxel, a set of locally ideal beam angles is generated. The spherical distribution of locally ideal beam angles is characteristic for every treatment site and patient: ideal beam angles typically cluster around distinct orientations. We interpret the cluster centroids, which are identified with a spherical K-means algorithm, as irradiation angles of an intensity-modulated radiation therapy treatment plan. The fluence profiles are subsequently optimized during a conventional inverse planning process. The average computation time for the pre-optimization of a beam ensemble is six minutes on a state-of-the-art work station. The treatment planning study demonstrates the potential benefit of the proposed beam angle optimization strategy. For the three prostate cases under investigation, the standard treatment plans applying nine coplanar equi-spaced beams and treatment plans applying an optimized non-coplanar nine-beam ensemble yield clinically comparable dose distributions. For symmetric patient geometries, the dose distribution formed by nine equi-spaced coplanar beams cannot be improved significantly. For the three pancreas and intra-cranial cases under investigation, the optimized non-coplanar beam ensembles enable better sparing of organs at risk while guaranteeing equivalent target coverage. Beam angle optimization by spherical cluster analysis shows the biggest impact for target volumes located asymmetrically within the patient and close to organs at risk.

  11. Intensity Modulated Radiation Therapy for Primary Soft Tissue Sarcoma of the Extremity: Preliminary Results

    SciTech Connect

    Alektiar, Kaled M. . E-mail: alektiak@mskcc.org; Hong, Linda; Brennan, Murray F.; Della-Biancia, Cesar; Singer, Samuel

    2007-06-01

    Purpose: To report preliminary results on using intensity modulated radiation therapy (IMRT) as an adjuvant treatment in primary soft tissue sarcoma (STS) of the extremity. Methods and Materials: Between February 2002 and March 2005, 31 adult patients with primary STS of the extremity were treated with surgery and adjuvant IMRT. Tumor size was >10 cm in 74% of patients and grade was high in 77%. Preoperative IMRT was given to 7 patients (50 Gy) and postoperative IMRT (median dose, 63 Gy) was given to 24 patients. Complete gross resection including periosteal stripping or bone resection was required in 10, and neurolysis or nerve resection in 20. The margins were positive or within 1 mm in 17. Complications from surgery and radiation therapy (RT) were assessed using the Common Terminology Criteria for Adverse Events grading system. Results: Median follow-up time was 23 months. Grade 1 RT dermatitis developed in 71% of patients, Grade 2 in 16%, and Grade 3 in 10%. Infectious wound complications developed in 13% and noninfectious complications in 10%. Two patients (6.4%) developed fractures. Grade 1 neuropathy developed in 28% of patients and Grade 2 in 5%. The rates of Grade 1 and 2 joint stiffness were each 19%. Grade 1 edema was observed in 19% of patients and Grade 2 in 13%. The 2-year local control, distant control, and overall survival were 95%, 65%, and 81%, respectively. Conclusion: Intensity modulated RT appears to provide excellent local control in a difficult group of high-risk patients. The morbidity profile is also favorable, but longer follow-up is needed to confirm the results from this study.

  12. Radiation and temperature effects of the intensive injection of dust aerosol into the atmosphere

    NASA Astrophysics Data System (ADS)

    Gorchakova, I. A.; Mokhov, I. I.; Rublev, A. N.

    2015-03-01

    Based on the measurements at the AERONET station (Ilorin, Nigeria), quantitative estimates of radiation and temperature effects of dust aerosol during the intensive sand storm in the Sahara Desert from January 28 to February 6, 2000, are obtained. The model used in calculations implies particles of dust aerosol being no more than 15 μm in radius (according to the data from AERONET station); another model takes into account large particles (LPs) up to 60 μm in radius and involves a spectral variation in the OPAC refraction index. In the short infrared region, the optical thickness of aerosol weakening increases with LPs taken into account in the aerosol model; the albedo of aerosol single scattering reduces in comparison to the respective optical parameters of the first model. Dust aerosol cools the earth's surface. In the presence of LPs in dust aerosol, the surface-atmosphere system can both cool and warm, while if LPs less than 15 μm in size are not taken into account, the surface cools. The rate of cooling of the 10-m near-surface atmospheric layer Δ T/Δ t changes in the interval of -(4-21)°C/day without the influence of LPs over 15 μm in size on solar radiation transfer taken into account; if this influence is taken into account, the rate is -(6-36)°C/day. In the long infrared region, the surface-atmosphere system warms more intensively if LPs are taken into account by the aerosol model. The heating rate of the 10-m near-surface atmospheric layer does not exceed ~0.5°C/day during the entire period of dust emission without LPs taken into account (AERONET algorithm); if LPs are taken into account (modeling results), heating rate reaches a maximal value of ~0.6°C/day.

  13. Dosimetric and QA aspects of Konrad inverse planning system for commissioning intensity-modulated radiation therapy.

    PubMed

    Deshpande, Shrikant; Sathiyanarayanan, V K; Bhangle, Janhavi; Swamy, Kumara; Basu, Sumit

    2007-04-01

    The intensity-modulated radiation therapy (IMRT) planning is performed using the Konrad inverse treatment planning system and the delivery of the treatment by using Siemens Oncor Impression Plus linear accelerator (step and shoot), which has been commissioned recently. The basic beam data required for commissioning the system were generate. The quality assurance of relative and absolute dose distribution was carried out before clinical implementation. The salient features of Konrad planning system, like dependence of grid size on dose volume histogram (DVH), number of intensity levels and step size in sequencer, are studied quantitatively and qualitatively.To verify whether the planned dose [from treatment planning system (TPS)] and delivered dose are the same, the absolute dose at a point is determined using CC01 ion chamber and the axial plane dose distribution is carried out using Kodak EDR2 in conjunction with OmniPro IMRT Phantom and OmniPro IMRT software from Scanditronix Wellhofer. To obtain the optimum combination in leaf sequencer module, parameters like number of intensity levels, step size are analyzed. The difference between pixel values of optimum fluence profile and the fluence profile obtained for various combinations of number of intensity levels and step size is compared and plotted. The calculations of the volume of any RT structure in the dose volume histogram are compared using grid sizes 3 mm and 4 mm. The measured and planned dose at a point showed good agreement (<3%) except for a few cases wherein the chamber was placed in a relatively high dose gradient region. The axial plane dose distribution using film dosimetry shows excellent agreement (correlation coefficient >0.97) in all the cases. In the leaf sequencer module, the combination of number of intensity level 7 with step size of 3 is the optimal solution for obtaining deliverable segments. The RT structure volume calculation is found to be more accurate with grid size of 3 mm for

  14. Gas Electron Multiplier performance under high intensity X-ray radiation

    NASA Astrophysics Data System (ADS)

    di, Danning

    2015-10-01

    Large size Gas Electron Multiplier (GEM) for the Super Bigbite Spectrometer (SBS) in Hall A at Thomas Jefferson National Laboratory (JLab) have been built at Detector Lab of University of Virginia(UVa). The Proton Polarimeter Back Tracker of the SBS consist of 40 GEM modules of size 60 ×50 cm2. We report R&D and quality test of the GEM detectors under high intensity X-ray radiation. Expected background rate in experiment is up to about 500 kHz/cm2. Such high background rate requires GEM detectors to have timing resolution of about a few nano seconds and operate stably with high rate activities going on within. X-ray with high rate up to 50 MHz/cm2 and energy up to 50 keV was used to test the performance of GEM detectors in detector lab at UVa. Issues caused by high intensity background and detailed R&D effort to adapt GEM detectors for use in the SBS are described.

  15. Saturn kilometric radiation intensities during the Saturn auroral campaign of 2013

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Hospodarsky, G. B.; Gurnett, D. A.; Lamy, L.; Dougherty, M. K.; Nichols, J.; Bunce, E. J.; Pryor, W.; Baines, K.; Stallard, T.; Melin, H.; Crary, F. J.

    2016-01-01

    The Saturn auroral campaign carried out in the spring of 2013 used multiple Earth-based observations, remote-sensing observations from Cassini, and in situ-observations from Cassini to further our understanding of auroras at Saturn. Most of the remote sensing and Earth-based measurements are, by nature, not continuous. And, even the in situ measurements, while continuously obtained, are not always obtained in regions relevant to the study of the aurora. Saturn kilometric radiation, however, is remotely monitored nearly continuously by the Radio and Plasma Wave Science instrument on Cassini. This radio emission, produced by the cyclotron maser instability, is tightly tied to auroral processes at Saturn as are auroral radio emissions at other planets, most notably Jupiter and Earth. This paper provides the time history of the intensity of the radio emissions through the auroral campaign as a means of understanding the temporal relationships between the sometimes widely spaced observations of the auroral activity. While beaming characteristics of the radio emissions are known to prevent single spacecraft observations of this emission from being a perfect auroral activity indicator, we demonstrate a good correlation between the radio emission intensity and the level of UV auroral activity, when both measurements are available.

  16. Electronic response of graphene to an ultrashort intense terahertz radiation pulse

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenichi L.

    2013-05-01

    We have recently reported a study (Ishikawa 2010 Phys. Rev. B 82 201402) on a nonlinear optical response of graphene to a normally incident terahertz radiation pulse within the massless Dirac fermion (MDF) picture, where we have derived physically transparent graphene Bloch equations (GBE). Here we extend it to the tight-binding (TB) model and oblique incidence. The derived equations indicate that interband transitions are governed by the temporal variation of the spinor phase along the electron path in the momentum space and predominantly take place when the electron passes near the Dirac point. At normal incidence, the equations for electron dynamics within the TB model can be cast into the same form of GBE as for the MDF model. At oblique incidence, the equations automatically incorporate photon drag and satisfy the continuity equation for electron density. Single-electron dynamics strongly depend on the model and pulse parameters, but the rapid variations are averaged out after momentum-space integration. Direct current remaining after the pulse is generated in graphene irradiated by an intense monocycle terahertz pulse, even if it is linearly polarized and normally incident. The generated current depends on the carrier-envelope phase, pulse intensity and Fermi energy in a complex manner.

  17. Cognitive impairment and neurogenotoxic effects in rats exposed to low-intensity microwave radiation.

    PubMed

    Deshmukh, Pravin Suryakantrao; Nasare, Namita; Megha, Kanu; Banerjee, Basu Dev; Ahmed, Rafat Sultana; Singh, Digvijay; Abegaonkar, Mahesh Pandurang; Tripathi, Ashok Kumar; Mediratta, Pramod Kumari

    2015-01-01

    The health hazard of microwave radiation (MWR) has become a recent subject of interest as a result of the enormous increase in mobile phone usage. The present study aimed to investigate the effects of chronic low-intensity microwave exposure on cognitive function, heat shock protein 70 (HSP70), and DNA damage in rat brain. Experiments were performed on male Fischer rats exposed to MWR for 180 days at 3 different frequencies, namely, 900, 1800 MHz, and 2450 MHz. Animals were divided into 4 groups: group I: sham exposed; group II: exposed to MWR at 900 MHz, specific absorption rate (SAR) 5.953 × 10(-4) W/kg; group III: exposed to 1800 MHz, SAR 5.835 × 10(-4) W/kg; and group IV: exposed to 2450 MHz, SAR 6.672 × 10(-4) W/kg. All the rats were tested for cognitive function at the end of the exposure period and were subsequently sacrificed to collect brain. Level of HSP70 was estimated by enzyme-linked immunotarget assay and DNA damage was assessed using alkaline comet assay in all the groups. The results showed declined cognitive function, elevated HSP70 level, and DNA damage in the brain of microwave-exposed animals. The results indicated that, chronic low-intensity microwave exposure in the frequency range of 900 to 2450 MHz may cause hazardous effects on the brain. PMID:25749756

  18. The influence of salt aerosol on alpha radiation detection by WIPP continuous air monitors

    SciTech Connect

    Bartlett, W.T.; Walker, B.A.

    1996-01-01

    Alpha continuous air monitors (CAMs) will be used at the Waste Isolation Pilot Plant (WIPP) to measure airborne transuranic radioactivity that might be present in air exhaust or in work-place areas. WIPP CAMs are important to health and safety because they are used to alert workers to airborne radioactivity, to actuate air-effluent filtration systems, and to detect airborne radioactivity so that the radioactivity can be confined in a limited area. In 1993, the Environmental Evaluation Group (EEG) reported that CAM operational performance was affected by salt aerosol, and subsequently, the WIPP CAM design and usage were modified. In this report, operational data and current theories on aerosol collection were reviewed to determine CAM quantitative performance limitations. Since 1993, the overall CAM performance appears to have improved, but anomalous alpha spectra are present when sampling-filter salt deposits are at normal to high levels. This report shows that sampling-filter salt deposits directly affect radon-thoron daughter alpha spectra and overall monitor efficiency. Previously it was assumed that aerosol was mechanically collected on the surface of CAM sampling filters, but this review suggests that electrostatic and other particle collection mechanisms are more important than previously thought. The mechanism of sampling-filter particle collection is critical to measurement of acute releases of radioactivity. 41 refs.

  19. Intensity-modulated radiation therapy for the treatment of nonanaplastic thyroid cancer

    SciTech Connect

    Rosenbluth, Benjamin D.; Serrano, Victoria B.S.; Happersett, Laura; Shaha, Ashok R.; Tuttle, R. Michael; Narayana, Ashwatha; Wolden, Suzanne L.; Rosenzweig, Kenneth E.; Chong, Lanceford M.; Lee, Nancy Y. . E-mail: leen2@mskcc.org

    2005-12-01

    Purpose: Intensity-modulated radiation therapy (IMRT) enables highly conformal treatment for thyroid cancer (TC). In this study, we review outcomes/toxicity in a series of TC patients treated with IMRT. Methods and Materials: Between July 2001 and January 2004, 20 nonanaplastic TC patients underwent IMRT. Mean age was 55. There were 3 T2 and 17 T4 patients. Sixteen patients had N1 disease. Seven patients had metastases before RT. Fifteen underwent surgery before RT. Radioactive iodine (RAI) and chemotherapy were used in 70% and 40%, respectively. Median total RT dose was 63 Gy. Results: With two local failures, 2-year local progression-free rate was 85%. There were six deaths, with a 2-year overall survival rate of 60%. For patients with M0 disease, the 2-year distant metastases-free rate was 46%. The worst acute mucositis and pharyngitis was Grade 3 (n = 7 and 3, respectively). Two patients had Grade 3 acute skin toxicity and 2 had Grade 3 acute laryngeal toxicity. No significant radiation-related late effects were reported. Conclusions: IMRT for TC is feasible and effective in appropriately selected cases. Acute toxicity is manageable with proactive clinical care. Ideal planning target volume doses have yet to be determined. Additional patients and long-term follow-up are needed to confirm these preliminary findings and to clarify late toxicities.

  20. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

    SciTech Connect

    J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

    2006-04-01

    The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

  1. Comparison of optimization algorithms in intensity-modulated radiation therapy planning

    NASA Astrophysics Data System (ADS)

    Kendrick, Rachel

    Intensity-modulated radiation therapy is used to better conform the radiation dose to the target, which includes avoiding healthy tissue. Planning programs employ optimization methods to search for the best fluence of each photon beam, and therefore to create the best treatment plan. The Computational Environment for Radiotherapy Research (CERR), a program written in MATLAB, was used to examine some commonly-used algorithms for one 5-beam plan. Algorithms include the genetic algorithm, quadratic programming, pattern search, constrained nonlinear optimization, simulated annealing, the optimization method used in Varian EclipseTM, and some hybrids of these. Quadratic programing, simulated annealing, and a quadratic/simulated annealing hybrid were also separately compared using different prescription doses. The results of each dose-volume histogram as well as the visual dose color wash were used to compare the plans. CERR's built-in quadratic programming provided the best overall plan, but avoidance of the organ-at-risk was rivaled by other programs. Hybrids of quadratic programming with some of these algorithms seems to suggest the possibility of better planning programs, as shown by the improved quadratic/simulated annealing plan when compared to the simulated annealing algorithm alone. Further experimentation will be done to improve cost functions and computational time.

  2. SU-E-P-18: Intensity-Modulated Radiation Therapy for Cervical Esophageal Squamous Cell Carcinoma

    SciTech Connect

    Bai, W; Qiao, X; Zhou, Z; Song, Y; Zhang, R; Zhen, C

    2015-06-15

    Purpose: To retrospectively analyze the outcomes and prognostic factors of cervical esophageal squamous cell carcinoma (SCC) treated with intensity modulated radiation therapy (IMRT). Methods: Thirty-seven patients with cervical esophageal SCC treated with IMRT were analyzed retrospectively. They received 54–66 Gy in 27–32 fractions. Nineteen patients received concurrent (n=12) or sequential (n=7) platinum-based two drugs chemoradiotherapy. Overall survival (OS), local control rates (LCR) and prognostic factors were evaluated. Acute toxicities and patterns of first failures were observed. Results: The median follow-up was 46 months for alive patients. The l-, 3-, 4- and 5-year OS of the all patients were 83.8%, 59.1%, 47.5% and 32.6% respectively. The median survival time was 46 months. The l-, 3-,4- and 5-year LCR were 82.9%, 63.0%, 54.5% and 54.5%, respectively. Univariate and Multivariate analysis all showed that size of GTV was an independent prognostic factor (p=0.033, p=0.039). There were no patients with Grade 3 acute radiation esophagitis and Grade 2–4 acute pneumonitis. The local failure accounted for 70.0% of all treatment-related failures. Conclusion: IMRT is safe and effective in the treatment of cervical esophageal squamous cell carcinoma. Size of GTV is an independent prognostic factor. Local failure still remains the main reason of treatment failures. The authors declare no conflicts of interest in preparing this article.

  3. Fast radiographic film calibration procedure for helical tomotherapy intensity modulated radiation therapy dose verification

    SciTech Connect

    Yan Yulong; Papanikolaou, Nikos; Weng Xuejun; Penagaricano, Jose; Ratanatharathorn, Vaneerat

    2005-06-15

    Film dosimetry offers an advantageous in-phantom planar dose verification tool in terms of spatial resolution and ease of handling for quality assurance (QA) of intensity modulated radiation therapy (IMRT) plans. A critical step in the success of such a technique is that the film calibration be appropriately conducted. This paper presents a fast and efficient film calibration method for a helical tomotherapy unit using a single sheet of film. Considering the unique un-flattened cone shaped profile from a helical tomotherapy beam, a custom leaf control file (sinogram) was created, to produce a valley shaped intensity pattern. There are eleven intensity steps in the valley pattern, representing varying dose values from 38 to 265 cGy. This dose range covers the most commonly prescribed doses in fractionated IMRT treatments. An ion chamber in a solid water phantom was used to measure the dose in each of the eleven steps. For daily film calibration the whole procedure, including film exposure, processing, digitization and analysis, can be completed within 15 min, making it practical to use this technique routinely. This method is applicable to film calibration on a helical tomotherapy unit and is particularly useful in IMRT planar dose verification due to its efficiency and reproducibility. In this work, we characterized the dose response of the KODAK EDR2 ready-pack film which was used to develop the step valley dose maps and the IMRT QA planar doses. A comparison between the step valley technique and multifilm based calibration showed that both calibration methods agreed with less than 0.4% deviation in the clinically useful dose ranges.

  4. Incorporation of gantry angle correction for 3D dose prediction in intensity-modulated radiation therapy

    PubMed Central

    Sumida, Iori; Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Yagi, Masashi; Ogawa, Kazuhiko

    2015-01-01

    Pretreatment dose verification with beam-by-beam analysis for intensity-modulated radiation therapy (IMRT) is commonly performed with a gantry angle of 0° using a 2D diode detector array. Any changes in multileaf collimator (MLC) position between the actual treatment gantry angle and 0° may result in deviations from the planned dose. We evaluated the effects of MLC positioning errors between the actual treatment gantry angles and nominal gantry angles. A gantry angle correction (GAC) factor was generated by performing a non-gap test at various gantry angles using an electronic portal imaging device (EPID). To convert pixel intensity to dose at the MLC abutment positions, a non-gap test was performed using an EPID and a film at 0° gantry angle. We then assessed the correlations between pixel intensities and doses. Beam-by-beam analyses for 15 prostate IMRT cases as patient-specific quality assurance were performed with a 2D diode detector array at 0° gantry angle to determine the relative dose error for each beam. The resulting relative dose error with or without GAC was added back to the original dose grid for each beam. We compared the predicted dose distributions with or without GAC for film measurements to validate GAC effects. A gamma pass rate with a tolerance of 2%/2 mm was used to evaluate these dose distributions. The gamma pass rate with GAC was higher than that without GAC (P = 0.01). The predicted dose distribution improved with GAC, although the dosimetric effect to a patient was minimal. PMID:25742866

  5. Intensity-Modulated Radiation Therapy With Concurrent Chemotherapy as Preoperative Treatment for Localized Gastric Adenocarcinoma

    SciTech Connect

    Chakravarty, Twisha; Crane, Christopher H.; Ajani, Jaffer A.; Mansfield, Paul F.; Briere, Tina M.; Beddar, A. Sam; Mok, Henry; Reed, Valerie K.; Krishnan, Sunil; Delclos, Marc E.; Das, Prajnan

    2012-06-01

    Purpose: The goal of this study was to evaluate dosimetric parameters, acute toxicity, pathologic response, and local control in patients treated with preoperative intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy for localized gastric adenocarcinoma. Methods: Between November 2007 and April 2010, 25 patients with localized gastric adenocarcinoma were treated with induction chemotherapy, followed by preoperative IMRT and concurrent chemotherapy and, finally, surgical resection. The median radiation therapy dose was 45 Gy. Concurrent chemotherapy was 5-fluorouracil and oxaliplatin in 18 patients, capecitabine in 3, and other regimens in 4. Subsequently, resection was performed with total gastrectomy in 13 patients, subtotal gastrectomy in 7, and other surgeries in 5. Results: Target coverage, expressed as the ratio of the minimum dose received by 99% of the planning target volume to the prescribed dose, was a median of 0.97 (range, 0.92-1.01). The median V{sub 30} (percentage of volume receiving at least 30 Gy) for the liver was 26%; the median V{sub 20} (percentage of volume receiving at least 20 Gy) for the right and left kidneys was 14% and 24%, respectively; and the median V{sub 40} (percentage of volume receiving at least 40 Gy) for the heart was 18%. Grade 3 acute toxicity developed in 14 patients (56%), including dehydration in 10, nausea in 8, and anorexia in 5. Grade 4 acute toxicity did not develop in any patient. There were no significant differences in the rates of acute toxicity, hospitalization, or feeding tube use in comparison to those in a group of 50 patients treated with preoperative three-dimensional conformal radiation therapy with concurrent chemotherapy. R0 resection was obtained in 20 patients (80%), and pathologic complete response occurred in 5 (20%). Conclusions: Preoperative IMRT for gastric adenocarcinoma was well tolerated, accomplished excellent target coverage and normal structure sparing, and led to appropriate

  6. Expert Consensus Contouring Guidelines for Intensity Modulated Radiation Therapy in Esophageal and Gastroesophageal Junction Cancer

    SciTech Connect

    Wu, Abraham J.; Bosch, Walter R.; Chang, Daniel T.; Hong, Theodore S.; Jabbour, Salma K.; Kleinberg, Lawrence R.; Mamon, Harvey J.; Thomas, Charles R.; Goodman, Karyn A.

    2015-07-15

    Purpose/Objective(s): Current guidelines for esophageal cancer contouring are derived from traditional 2-dimensional fields based on bony landmarks, and they do not provide sufficient anatomic detail to ensure consistent contouring for more conformal radiation therapy techniques such as intensity modulated radiation therapy (IMRT). Therefore, we convened an expert panel with the specific aim to derive contouring guidelines and generate an atlas for the clinical target volume (CTV) in esophageal or gastroesophageal junction (GEJ) cancer. Methods and Materials: Eight expert academically based gastrointestinal radiation oncologists participated. Three sample cases were chosen: a GEJ cancer, a distal esophageal cancer, and a mid-upper esophageal cancer. Uniform computed tomographic (CT) simulation datasets and accompanying diagnostic positron emission tomographic/CT images were distributed to each expert, and the expert was instructed to generate gross tumor volume (GTV) and CTV contours for each case. All contours were aggregated and subjected to quantitative analysis to assess the degree of concordance between experts and to generate draft consensus contours. The panel then refined these contours to generate the contouring atlas. Results: The κ statistics indicated substantial agreement between panelists for each of the 3 test cases. A consensus CTV atlas was generated for the 3 test cases, each representing common anatomic presentations of esophageal cancer. The panel agreed on guidelines and principles to facilitate the generalizability of the atlas to individual cases. Conclusions: This expert panel successfully reached agreement on contouring guidelines for esophageal and GEJ IMRT and generated a reference CTV atlas. This atlas will serve as a reference for IMRT contours for clinical practice and prospective trial design. Subsequent patterns of failure analyses of clinical datasets using these guidelines may require modification in the future.

  7. Intensity-Modulated Radiation Therapy in the Salvage of Locally Recurrent Nasopharyngeal Carcinoma

    SciTech Connect

    Qiu Sufang; Lin Shaojun; Tham, Ivan W.K.; Pan Jianji; Lu Jun; Lu, Jiade J.

    2012-06-01

    Purpose: Local recurrences of nasopharyngeal carcinoma (NPC) may be salvaged by reirradiation with conventional techniques, but with significant morbidity. Intensity-modulated radiation therapy (IMRT) may improve the therapeutic ratio by reducing doses to normal tissue. The aim of this study was to address the efficacy and toxicity profile of IMRT for a cohort of patients with locally recurrent NPC. Methods and Materials: Between August 2003 and June 2009, 70 patients with radiologic or pathologically proven locally recurrent NPC were treated with IMRT. The median time to recurrence was 30 months after the completion of conventional radiation to definitive dose. Fifty-seven percent of the tumors were classified asrT3-4. The minimum planned doses were 59.4 to 60 Gy in 1.8- to 2-Gy fractions per day to the gross disease with margins, with or without chemotherapy. Results: The median dose to the recurrent tumor was 70 Gy (range, 50-77.4 Gy). Sixty-five patients received the planned radiation therapy; 5 patients received between 50 and 60 Gy because of acute side effects. With a median follow-up time of 25 months, the rates of 2-year locoregional recurrence-free survival, disease-free survival, and overall survival were 65.8%, 65.8%, and 67.4%, respectively. Moderate to severe late toxicities were noted in 25 patients (35.7%). Eleven patients (15.7%) had posterior nasal space ulceration, 17 (24.3%) experienced cranial nerve palsies, 12 (17.1%) had trismus, and 12 (17.1%) experienced deafness. Extended disease-free interval (relative risk 2.049) and advanced T classification (relative risk 3.895) at presentation were adverse prognostic factors. Conclusion: Reirradiation with IMRT provides reasonable long-term control in patients with locally recurrent NPC.

  8. Fatal pneumonitis associated with intensity-modulated radiation therapy for mesothelioma

    SciTech Connect

    Allen, Aaron M. . E-mail: aallen@lroc.harvard.edu; Czerminska, Maria; Jaenne, Pasi A.; Sugarbaker, David J.; Bueno, Raphael; Harris, Jay R.; Court, Laurence; Baldini, Elizabeth H.

    2006-07-01

    Purpose: To describe the initial experience at Dana-Farber Cancer Institute/Brigham and Women's Hospital with intensity-modulated radiation therapy (IMRT) as adjuvant therapy after extrapleural pneumonectomy (EPP) and adjuvant chemotherapy. Methods and Materials: The medical records of patients treated with IMRT after EPP and adjuvant chemotherapy were retrospectively reviewed. IMRT was given to a dose of 54 Gy to the clinical target volume in 1.8 Gy daily fractions. Treatment was delivered with a dynamic multileaf collimator using a sliding window technique. Eleven of 13 patients received heated intraoperative cisplatin chemotherapy (225 mg/m{sup 2}). Two patients received neoadjuvant intravenous cisplatin/pemetrexed, and 10 patients received adjuvant cisplatin/pemetrexed chemotherapy after EPP but before radiation therapy. All patients received at least 2 cycles of intravenous chemotherapy. The contralateral lung was limited to a V20 (volume of lung receiving 20 Gy or more) of 20% and a mean lung dose (MLD) of 15 Gy. All patients underwent fluorodeoxyglucose positron emission tomography (FDG-PET) for staging, and any FDG-avid areas in the hemithorax were given a simultaneous boost of radiotherapy to 60 Gy. Statistical comparisons were done using two-sided t test. Results: Thirteen patients were treated with IMRT from December 2004 to September 2005. Six patients developed fatal pneumonitis after treatment. The median time from completion of IMRT to the onset of radiation pneumonitis was 30 days (range 5-57 days). Thirty percent of patients (4 of 13) developed acute Grade 3 nausea and vomiting. One patient developed acute Grade 3 thrombocytopenia. The median V20, MLD, and V5 (volume of lung receiving 5 Gy or more) for the patients who developed pneumonitis was 17.6% (range, 15.3-22.3%), 15.2 Gy (range, 13.3-17 Gy), and 98.6% (range, 81-100%), respectively, as compared with 10.9% (range, 5.5-24.7%) (p = 0.08), 12.9 Gy (range, 8.7-16.9 Gy) (p = 0.07), and 90% (range

  9. 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

  10. [Comparison of dynamic properties of various globular proteins and polyglutamic acid in alpha-helical and coil states. Rayleigh scattering of Mossbauer radiation data].

    PubMed

    Krupianskiĭ, Iu F; Kurinov, I V; Kuznetsov, S A; Eshchenko, G V; Gol'danskiĭ, V I

    1997-01-01

    Classical model system: Poly-L-glutamic acid (Poly-Glu) was investigated in a disordered coil state (at pH-7.0) and in helix state (at pH 2.0) by Rayleigh scattering of Moessbauer radiation technique. Consider that the coil state of poly-Glu models unfolded (random coil) state and alpha-helix state models the fluctuating secondary structure (during consequent folding of protein) comparative analysis of dynamical properties of poly-Glu in different states with dynamical properties of different proteins in native state (alpha-helical myoglobin and HSA, partially beta-sheet lysozyme) and in intermediate (molten globule) state (alpha-lactalbumin) was performed. This comparison bring some surprising results: native alpha-helical proteins behave itself close to random coil, native partially beta-sheet protein behaves close to fluctuating secondary structure (alpha-helix) and the dynamic behaviour of molten globule state (partially beta-sheet alpha-lactalbumin) is not different from those behaviour of lysozyme and much more rigid than native alpha-helical proteins. As a result one cannot exclude the possibility that folding process and dynamical properties at different steps of the folding are very different for alpha-helical and beta-sheet proteins. PMID:9181800

  11. Protective action of low-intensity laser radiation relative to the toxic effect of metals (experimental study in vitro)

    NASA Astrophysics Data System (ADS)

    Dejneka, S. Y.

    1997-12-01

    The study of a possible cytotoxic effect of different doses of low-insensitive laser radiation and protective action of low-intensive laser radiation relative to the toxic effect of metals was carried out by means of the alternative method of investigation in vitro on cell cultura Hela. It was established that the investigated doses of low-intensive laser radiation had not produced any toxic effect on cell culture Hela, so the mentioned doses were not cytotoxic. It was revealed that laser radiation reduced the level of the cytotoxic effect of the studied metal salts on the cell culture, and possessed the protective action against the toxic effect of metals. This action has a clear-cut dose- related character.

  12. Out-of-Field Cell Survival Following Exposure to Intensity-Modulated Radiation Fields

    SciTech Connect

    Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2011-04-01

    Purpose: To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication. Methods and Materials: Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator. Results: Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the {alpha}-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response. Conclusions: These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.

  13. Multi-photon ionization of atoms in intense short-wavelength radiation fields

    NASA Astrophysics Data System (ADS)

    Meyer, Michael

    2015-05-01

    The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing

  14. Oncogenic action of beta, proton, alpha and electron radiation on the rat skin

    SciTech Connect

    Burns, F.J.

    1980-01-01

    Rat skin is being utilized as an empirical model for testing dose and time related aspects of the oncogenic action of ionizing radiation, ultraviolet light, and polycyclic aromatic hydrocarbons. Molecular lesions in the skin DNA, including, strand breaks and thymine dimers, are being measured and compared to tumor induction. The induction and repair kinetics of molcular lesions are being compared to split dose repair. Modifiers and radiosensitizers are being utilized to test specific aspects of a chromosome breakage theory of radiation oncogenesis.

  15. Measurement of the Gaponov-Miller force produced in vacuum by tightly focused intense femtosecond laser radiation

    SciTech Connect

    Aseyev, S. A. Mironov, B. N.; Minogin, V. G.; Chekalin, S. V.

    2011-05-15

    A method for measuring the Gaponov-Miller force (GMF) is demonstrated based on the deflection of a picosecond photoelectron beam exposed to tightly focused intense femtosecond laser radiation. It is shown experimentally that the action of this force produced by femtosecond laser pulses linearly depends on their intensity. The method can be used to verify the correctness of measuring the duration of an ultrashort electron bunch based on the GMF.

  16. Disease Control After Reduced Volume Conformal and Intensity Modulated Radiation Therapy for Childhood Craniopharyngioma

    SciTech Connect

    Merchant, Thomas E.; Kun, Larry E.; Hua, Chia-Ho; Wu, Shengjie; Xiong, Xiaoping; Sanford, Robert A.; Boop, Frederick A.

    2013-03-15

    Purpose: To estimate the rate of disease control after conformal radiation therapy using reduced clinical target volume (CTV) margins and to determine factors that predict for tumor progression. Methods and Materials: Eighty-eight children (median age, 8.5 years; range, 3.2-17.6 years) received conformal or intensity modulated radiation therapy between 1998 and 2009. The study group included those prospectively treated from 1998 to 2003, using a 10-mm CTV, defined as the margin surrounding the solid and cystic tumor targeted to receive the prescription dose of 54 Gy. The CTV margin was subsequently reduced after 2003, yielding 2 groups of patients: those treated with a CTV margin greater than 5 mm (n=26) and those treated with a CTV margin less than or equal to 5 mm (n=62). Disease progression was estimated on the basis of additional variables including sex, race, extent of resection, tumor interventions, target volume margins, and frequency of weekly surveillance magnetic resonance (MR) imaging during radiation therapy. Median follow-up was 5 years. Results: There was no difference between progression-free survival rates based on CTV margins (>5 mm vs ≤5 mm) at 5 years (88.1% ± 6.3% vs 96.2% ± 4.4% [P=.6386]). There were no differences based on planning target volume (PTV) margins (or combined CTV plus PTV margins). The PTV was systematically reduced from 5 to 3 mm during the time period of the study. Factors predictive of superior progression-free survival included Caucasian race (P=.0175), no requirement for cerebrospinal fluid shunting (P=.0066), and number of surveillance imaging studies during treatment (P=.0216). Patients whose treatment protocol included a higher number of weekly surveillance MR imaging evaluations had a lower rate of tumor progression. Conclusions: These results suggest that targeted volume reductions for radiation therapy using smaller margins are feasible and safe but require careful monitoring. We are currently investigating

  17. Alterations in alpha-adrenergic and muscarinic cholinergic receptor binding in rat brain following nonionizing radiation

    SciTech Connect

    Gandhi, V.C.; Ross, D.H.

    1987-01-01

    Microwave radiation produces hyperthermia. The mammalian thermoregulatory system defends against changes in temperature by mobilizing diverse control mechanisms. Neurotransmitters play a major role in eliciting thermoregulatory responses. The involvement of adrenergic and muscarinic cholinergic receptors was investigated in radiation-induced hyperthermia. Rats were subjected to radiation at 700 MHz frequency and 15 mW/cm/sup 2/ power density and the body temperature was raised by 2.5 degrees C. Of six brain regions investigated only the hypothalamus showed significant changes in receptor states, confirming its pivotal role in thermoregulation. Adrenergic receptors, studied by (/sup 3/H)clonidine binding, showed a 36% decrease in binding following radiation after a 2.5 degrees C increase in body temperature, suggesting a mechanism to facilitate norepinephrine release. Norepinephrine may be speculated to maintain thermal homeostasis by activating heat dissipation. Muscarinic cholinergic receptors, studied by (3H)quinuclidinyl benzilate binding, showed a 65% increase in binding at the onset of radiation. This may be attributed to the release of acetylcholine in the hypothalamus in response to heat cumulation. The continued elevated binding during the period of cooling after radiation was shut off may suggest the existence of an extra-hypothalamic heat-loss pathway.

  18. Isochronal annealing of radiation damage in (alpha)- and (delta)-Pu alloys

    SciTech Connect

    McCall, S K; Fluss, M J; Chung, B W; Haire, R G

    2009-06-22

    Magnetic isochronal annealing curves were measured on specimens of self damaged {alpha}-Pu and several {delta}-Pu alloys stabilized by Ga and Am. These results are compared to one another and to isochronal resistivity annealing curves, where distinct differences are observed between the magnetic and resistive annealing for the case of {delta}-Pu. The first stage of annealing observed in the resistivity measurements is largely missing from the magnetic measurements, indicating that interstitials contribute little if any signal to the magnetization, while the onset of vacancy migration is strongly reflected in the magnetization signal.

  19. Electrical characterization of alpha radiation-induced defects in p-GaAs grown by metal-organic chemical-vapor deposition

    SciTech Connect

    Naz, Nazir A.; Qurashi, Umar S.; Iqbal, M. Zafar

    2007-03-15

    Investigations of the alpha particle irradiation-induced defects in low-pressure metal-organic chemical-vapor deposition grown p-GaAs have been carried out. By employing deep-level transient spectroscopy, at least seven radiation-induced deep-level defects have been observed in the lower half of the band gap in the temperature range of 12-475 K. Double-correlation deep-level transient spectroscopy measurements show three prominent levels: two known radiation-induced levels namely, H{alpha}1 and H{alpha}5, and one inadvertent center HSA, present before irradiation, to exhibit a significant dependence of thermal emission rate on the junction electric field. For H{alpha}1 and HSA the field-enhanced emission data are well fitted with a Poole-Frenkel model, using a three-dimensional square-well potential with radius r=3.2 and 1.43 nm, respectively. The field effect for H{alpha}5 has been explained by a square-well potential in combination with a phonon-assisted tunneling process. Detailed data on the carrier capture cross section for all three levels have been obtained. The hole capture cross section for the levels H{alpha}1 and H{alpha}5 are found to be temperature independent, while for HSA, the hole capture data show a dependence on temperature. The dependence of hole capture cross section of HSA on temperature has been explained in terms of multiphonon capture mechanism, yielding a capture barrier of 0.13 eV and {sigma}({infinity})=1.5x10{sup -14} cm{sup 2}. These analyses lead us to conclude that the levels H{alpha}1 and HSA are associated with a charged center, while the level H{alpha}5 is most likely a substitutional defect in GaAs.

  20. Plasminogen activator inhibitor-I-related regulation of procollagen I ({alpha}{sub 1} and {alpha}{sub 2}) by antitransforming growth factor-{beta}{sub 1} treatment during radiation-impaired wound healing

    SciTech Connect

    Schultze-Mosgau, Stefan; Thorwarth, Michael; Roedel, Franz; Melnychenko, Ivan; Grabenbauer, Gerhard G.; Amann, Kerstin; Wehrhan, Falk

    2006-01-01

    Purpose: Plasminogen activator inhibitor (PAI)-1 mediates transforming growth factor-{beta}{sub 1} (TGF-{beta}{sub 1})-related signaling by stimulating collagen Type I synthesis in radiation-impaired wound healing. The regulation of {alpha}(I)-procollagen is contradictory in fibroblasts of different fibrotic lesions. It is not known whether anti-TGF-{beta}{sub 1} treatment specifically inhibits {alpha}(I)-procollagen synthesis. We used an experimental wound healing study to address anti-TGF-{beta}{sub 1}-associated influence on {alpha}(I)-procollagen synthesis. Methods and Materials: A free flap was transplanted into the preirradiated (40 Gy) or nonirradiated neck region of Wistar rats: Group 1 (n = 8) surgery alone; Group 2 (n = 14) irradiation and surgery; Group 3 (n = 8) irradiation and surgery and anti-TGF-{beta}{sub 1} treatment. On the 14th postoperative day, skin samples were processed for fibroblast culture, in situ hybridization for TGF-{beta}{sub 1}, immunohistochemistry, and immunoblotting for PAI-1, {alpha}{sub 1}/{alpha}{sub 2}(I)-procollagen. Results: Anti-TGF-{beta}{sub 1} significantly reduced TGF-{beta}{sub 1} mRNA (p < 0.05) and PAI-1 expression (p < 0.05). Anti-TGF-{beta}{sub 1} treatment in vivo significantly reduced {alpha}{sub 1}(I)-procollagen protein (p < 0.05) and the number of expressing cells (p < 0.05) in contrast to significantly increased (p < 0.05) {alpha}{sub 2}(I)-procollagen expression. Conclusion: These results emphasize anti-TGF-{beta}{sub 1} treatment to reduce radiation-induced fibrosis by decreasing {alpha}{sub 1}(I)-procollagen synthesis in vivo. {alpha}{sub 1}(I)-procollagen and {alpha}{sub 2}(I)-procollagen might be differentially regulated by anti-TGF-{beta}{sub 1} treatment. Increased TGF-{beta} signaling in irradiated skin fibroblasts seemed to be reversible, as shown by a reduction in PAI-1 expression after anti-TGF-{beta}{sub 1} treatment.

  1. Application of neural networks for determining optical parameters of strongly scattering media from the intensity profile of backscattered radiation

    SciTech Connect

    Kotova, S P; Maiorov, I V; Maiorova, A M

    2007-01-31

    We analyse the possibilities of simultaneous measuring three optical parameters of scattering media, namely, the scattering and absorption coefficients and the scattering anisotropy parameter by the intensity profile of backscattered radiation by using the neural network inversion method and the method of adaptive-network-based fuzzy inference system. The measurement errors of the absorption and scattering coefficients and the scattering anisotropy parameter are 20%, 5%, and 10%, respectively. (special issue devoted to multiple radiation scattering in random media)

  2. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Kondoh, Takafumi; Kashima, Hiroaki; Yang, Jinfeng; Yoshida, Yoichi; Tagawa, Seiichi

    2008-10-01

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods.

  3. Combined effects of tumor necrosis factor alpha and radiation in the treatment of renal cell carcinoma grown as radia spheroids.

    PubMed

    Van Moorselaar, R J; Schwachöfer, J H; Crooijmans, R P; Van Stratum, P; Debruyne, F M; Schalken, J A

    1990-01-01

    We have investigated the antiproliferative effects of Tumor Necrosis Factor Alpha (TNF) and radiation on a recently described rat renal cell tumor line grown as multicellular tumor spheroids (MTS). Treatment commenced when the spheroids had reached a diameter of 250 microns. TNF was diluted in the tissue culture medium in different concentrations, ranging from 250-1000 ng/ml. TNF monotherapy had a dose-dependent inhibiting effect on spheroid growth. Single-dose irradiation with 2, 4 or 6 Gy also retarded spheroids significantly in their growth. In the combination treatment the highest dose of TNF (1000 ng/ml) was added 4 hours prior to radiation. TNF could not induce a potentiation of the radiation injury at 2 Gy. The combination with 4 Gy, however, had additive and the combination with 6 Gy synergistic antiproliferative effects; in these treatment regimens respectively 2 and 5 out of 24 spheroids were controlled, i.e. cured. These experiments suggest that TNF in combination with radiotherapy may be beneficial for the treatment of renal cell carcinoma or cancer in general. PMID:2285257

  4. Enhancing cosmetic outcomes by combining superficial glycolic acid (alpha-hydroxy acid) peels with nonablative lasers, intense pulsed light, and trichloroacetic acid peels.

    PubMed

    Effron, Cheryl; Briden, M Elizabeth; Green, Barbara A

    2007-01-01

    Nonablative lasers, intense pulsed light (IPL), and trichloroacetic acid (TCA) peels are cosmetic rejuvenation techniques used to remodel skin and provide improved skin texture, firmness, and even pigmentation. Glycolic acid is an alpha-hydroxy acid that can be used as a topical skin peel to provide important complementary benefits to nonablative lasers, IPL, and TCA peels. Superficial glycolic acid peels provide both epidermal and dermal antiaging benefits, can be used to smooth the stratum corneum to reduce light scattering, and can enable the use of lower concentrations of TCA during a peel procedure. When used with these procedures, glycolic acid peels can enhance skin benefits and perceived patient outcomes. Methods of combining nonablative lasers, IPL, and TCA peels with glycolic acid peels were discussed at a dermatologist roundtable event and are summarized in this article. PMID:17455887

  5. Optimization and quality assurance of an image-guided radiation therapy system for intensity-modulated radiation therapy radiotherapy

    SciTech Connect

    Tsai, Jen-San; Micaily, Bizhan; Miyamoto, Curtis

    2012-10-01

    To develop a quality assurance (QA) of XVI cone beam system (XVIcbs) for its optimal imaging-guided radiotherapy (IGRT) implementation, and to construe prostate tumor margin required for intensity-modulated radiation therapy (IMRT) if IGRT is unavailable. XVIcbs spatial accuracy was explored with a humanoid phantom; isodose conformity to lesion target with a rice phantom housing a soap as target; image resolution with a diagnostic phantom; and exposure validation with a Radcal ion chamber. To optimize XVIcbs, rotation flexmap on coincidency between gantry rotational axis and that of XVI cone beam scan was investigated. Theoretic correlation to image quality of XVIcbs rotational axis stability was elaborately studied. Comprehensive QA of IGRT using XVIcbs has initially been explored and then implemented on our general IMRT treatments, and on special IMRT radiotherapies such as head and neck (H and N), stereotactic radiation therapy (SRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Fifteen examples of prostate setup accounted for 350 IGRT cone beam system were analyzed. IGRT accuracy results were in agreement {+-} 1 mm. Flexmap 0.25 mm met the manufacturer's specification. Films confirmed isodose coincidence with target (soap) via XVIcbs, otherwise not. Superficial doses were measured from 7.2-2.5 cGy for anatomic diameters 15-33 cm, respectively. Image quality was susceptible to rotational stability or patient movement. IGRT using XVIcbs on general IMRT treatments such as prostate, SRT, SRS, and SBRT for setup accuracy were verified; and subsequently coordinate shifts corrections were recorded. The 350 prostate IGRT coordinate shifts modeled to Gaussian distributions show central peaks deviated off the isocenter by 0.6 {+-} 3.0 mm, 0.5 {+-} 4.5 mm in the X(RL)- and Z(SI)-coordinates, respectively; and 2.0 {+-} 3.0 mm in the Y(AP)-coordinate as a result of belly and bladder capacity variations. Sixty-eight percent of confidence was

  6. Scattered Lyman-alpha radiation of comet 2012/S1 (ISON) observed by SUMER/SOHO

    NASA Astrophysics Data System (ADS)

    Curdt, W.; Boehnhardt, H.; Germerott, D.; Schuehle, U.; Solanki, S.; Teriaca, L.; Vincent, J.

    2014-07-01

    During its recent perihelion passage, comet ISON came so close to the Sun that it appeared in the field of view (FOV) of the SUMER spectrometer on SOHO and allowed unique observations at far-UV wavelengths with high spatial and temporal resolution. We report results of these observations completed during the comet's encounter with the Sun on November 28.75, 2013. Our data show the dust tail trailing behind the predicted position of the nucleus seen in Lyman-alpha emission as light from the solar disk that is scattered by micron-sized dust particles. The arrow-shaped tail is offset from the trajectory and not aligned with it. We model the dust emission and dynamics to reproduce the appearance of the tail. We could not detect any signature of cometary gas or plasma around the expected position of the nucleus and conclude that the out-gassing processes must have stopped before the comet entered our FOV. Also the model we used to reproduce the observed dust tail needs a sharp fall-off of the dust production hours before perihelion. We compare the radiance of the dust tail to the Lyman-alpha emission of the disk for an estimate of the dust column density. After observing 18 years mostly solar targets, this was the first time that SUMER completed spectroscopic observations of a comet.

  7. Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector.

    PubMed

    Kulkarni, A; Ha, S; Joshirao, P; Manchanda, V; Bak, M S; Kim, T

    2015-06-01

    A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO3)4 ⋅ 5H2O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories. PMID:26133876

  8. Hit rates and radiation doses to nuclei of bone lining cells from alpha-particle-emitting radionuclides

    NASA Technical Reports Server (NTRS)

    Polig, E.; Jee, W. S.; Kruglikov, I. L.

    1992-01-01

    Factors relating the local concentration of a bone-seeking alpha-particle emitter to the mean hit rate have been determined for nuclei of bone lining cells using a Monte Carlo procedure. Cell nuclei were approximated by oblate spheroids with dimensions and location taken from a previous histomorphometric study. The Monte Carlo simulation is applicable for planar and diffuse labels at plane or cylindrical bone surfaces. Additionally, the mean nuclear dose per hit, the dose mean per hit, the mean track segment length and its second moment, the percentage of stoppers, and the frequency distribution of the dose have been determined. Some basic features of the hit statistics for bone lining cells have been outlined, and the consequences of existing standards of radiation protection with regard to the hit frequency to cell nuclei are discussed.

  9. Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector

    SciTech Connect

    Kulkarni, A.; Bak, M. S. E-mail: moonsoo@skku.edu; Ha, S.; Joshirao, P.; Manchanda, V.; Kim, T. E-mail: moonsoo@skku.edu

    2015-06-15

    A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO{sub 3}){sub 4} ⋅ 5H{sub 2}O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories.

  10. Computer-assisted selection of coplanar beam orientations in intensity-modulated radiation therapy*

    NASA Astrophysics Data System (ADS)

    Pugachev, A.; Xing, L.

    2001-09-01

    In intensity-modulated radiation therapy (IMRT), the incident beam orientations are often determined by a trial and error search. The conventional beam's-eye view (BEV) tool becomes less helpful in IMRT because it is frequently required that beams go through organs at risk (OARs) in order to achieve a compromise between the dosimetric objectives of the planning target volume (PTV) and the OARs. In this paper, we report a beam's-eye view dosimetrics (BEVD) technique to assist in the selection of beam orientations in IMRT. In our method, each beam portal is divided into a grid of beamlets. A score function is introduced to measure the `goodness' of each beamlet at a given gantry angle. The score is determined by the maximum PTV dose deliverable by the beamlet without exceeding the tolerance doses of the OARs and normal tissue located in the path of the beamlet. The overall score of the gantry angle is given by a sum of the scores of all beamlets. For a given patient, the score function is evaluated for each possible beam orientation. The directions with the highest scores are then selected as the candidates for beam placement. This procedure is similar to the BEV approach used in conventional radiation therapy, except that the evaluation by a human is replaced by a score function to take into account the intensity modulation. This technique allows one to select beam orientations without the excessive computing overhead of computer optimization of beam orientation. It also provides useful insight into the problem of selection of beam orientation and is especially valuable for complicated cases where the PTV is surrounded by several sensitive structures and where it is difficult to select a set of `good' beam orientations. Several two-dimensional (2D) model cases were used to test the proposed technique. The plans obtained using the BEVD-selected beam orientations were compared with the plans obtained using equiangular spaced beams. For all the model cases investigated

  11. 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

  12. Radiation-Induced Cancers From Modern Radiotherapy Techniques: Intensity-Modulated Radiotherapy Versus Proton Therapy

    SciTech Connect

    Yoon, Myonggeun; Ahn, Sung Hwan; Kim, Jinsung; Shin, Dong Ho; Park, Sung Yong; Lee, Se Byeong; Shin, Kyung Hwan; Cho, Kwan Ho

    2010-08-01

    Purpose: To assess and compare secondary cancer risk resulting from intensity-modulated radiotherapy (IMRT) and proton therapy in patients with prostate and head-and-neck cancer. Methods and Materials: Intensity-modulated radiotherapy and proton therapy in the scattering mode were planned for 5 prostate caner patients and 5 head-and-neck cancer patients. The secondary doses during irradiation were measured using ion chamber and CR-39 detectors for IMRT and proton therapy, respectively. Organ-specific radiation-induced cancer risk was estimated by applying organ equivalent dose to dose distributions. Results: The average secondary doses of proton therapy for prostate cancer patients, measured 20-60cm from the isocenter, ranged from 0.4 mSv/Gy to 0.1 mSv/Gy. The average secondary doses of IMRT for prostate patients, however, ranged between 3 mSv/Gy and 1 mSv/Gy, approximately one order of magnitude higher than for proton therapy. Although the average secondary doses of IMRT were higher than those of proton therapy for head-and-neck cancers, these differences were not significant. Organ equivalent dose calculations showed that, for prostate cancer patients, the risk of secondary cancers in out-of-field organs, such as the stomach, lungs, and thyroid, was at least 5 times higher for IMRT than for proton therapy, whereas the difference was lower for head-and-neck cancer patients. Conclusions: Comparisons of organ-specific organ equivalent dose showed that the estimated secondary cancer risk using scattering mode in proton therapy is either significantly lower than the cases in IMRT treatment or, at least, does not exceed the risk induced by conventional IMRT treatment.

  13. Intensity-Modulated Radiation Therapy for Anal Malignancies: A Preliminary Toxicity and Disease Outcomes Analysis

    SciTech Connect

    Pepek, Joseph M.; Willett, Christopher G.; Wu, Q. Jackie; Yoo, Sua; Clough, Robert W.; Czito, Brian G.

    2010-12-01

    Purpose: Intensity-modulated radiation therapy (IMRT) has the potential to reduce toxicities associated with chemoradiotherapy in the treatment of anal cancer. This study reports the results of using IMRT in the treatment of anal cancer. Methods and Materials: Records of patients with anal malignancies treated with IMRT at Duke University were reviewed. Acute toxicity was graded using the NCI CTCAEv3.0 scale. Overall survival (OS), metastasis-free survival (MFS), local-regional control (LRC) and colostomy-free survival (CFS) were calculated using the Kaplan-Meier method. Results: Forty-seven patients with anal malignancy (89% canal, 11% perianal skin) were treated with IMRT between August 2006 and September 2008. Median follow-up was 14 months (19 months for SCC patients). Median radiation dose was 54 Gy. Eight patients (18%) required treatment breaks lasting a median of 5 days (range, 2-7 days). Toxicity rates were as follows: Grade 4: leukopenia (7%), thrombocytopenia (2%); Grade 3: leukopenia (18%), diarrhea (9%), and anemia (4%); Grade 2: skin (93%), diarrhea (24%), and leukopenia (24%). The 2-year actuarial overall OS, MFS, LRC, and CFS rates were 85%, 78%, 90% and 82%, respectively. For SCC patients, the 2-year OS, MFS, LRC, and CFS rates were 100%, 100%, 95%, and 91%, respectively. Conclusions: IMRT-based chemoradiotherapy for anal cancer results in significant reductions in normal tissue dose and acute toxicities versus historic controls treated without IMRT, leading to reduced rates of toxicity-related treatment interruption. Early disease-related outcomes seem encouraging. IMRT is emerging as a standard therapy for anal cancer.

  14. Intensity-modulated radiation therapy (IMRT) in the treatment of anal cancer: Toxicity and clinical outcome

    SciTech Connect

    Milano, Michael T.; Jani, Ashesh B.; Farrey, Karl J.; Rash, Carla C.; Heimann, Ruth; Chmura, Steven J. . E-mail: schmura@radonc.uchicago.edu

    2005-10-01

    Purpose: To assess survival, local control, and toxicity of intensity modulated radiation therapy (IMRT) in squamous cell carcinoma of the anal canal. Methods and Materials: Seventeen patients were treated with nine-field IMRT plans. Thirteen received concurrent 5-fluorouracil and mitomycin C, whereas 1 patient received 5-fluorouracil alone. Seven patients were planned with three-dimensional anteroposterior/posterior-anterior (AP/PA) fields for dosimetric comparison to IMRT. Results: Compared with AP/PA, IMRT reduced the mean and threshold doses to small bowel, bladder, and genitalia. Treatment was well tolerated, with no Grade {>=}3 acute nonhematologic toxicity. There were no treatment breaks attributable to gastrointestinal or skin toxicity. Of patients who received mitomycin C, 38% experienced Grade 4 hematologic toxicity. IMRT did not afford bone marrow sparing, possibly resulting from the clinical decision to prescribe 45 Gy to the whole pelvis in most patients, vs. the Radiation Therapy Oncology Group-recommended 30.6 Gy whole pelvic dose. Three of 17 patients, who did not achieve a complete response, proceeded to an abdominoperineal resection and colostomy. At a median follow-up of 20.3 months, there were no other local failures. Two-year overall survival, disease-free survival, and colostomy-free survival are: 91%, 65%, and 82% respectively. Conclusions: In this hypothesis-generating analysis, the acute toxicity and clinical outcome with IMRT in the treatment of anal cancer is encouraging. Compared with historical controls, local control is not compromised despite efforts to increase conformality and reduce normal structure dose.

  15. Hypofractionated Dose-Painting Intensity Modulated Radiation Therapy With Chemotherapy for Nasopharyngeal Carcinoma: A Prospective Trial

    SciTech Connect

    Bakst, Richard L.; Lee, Nancy; Pfister, David G.; Zelefsky, Michael J.; Hunt, Margie A.; Kraus, Dennis H.; Wolden, Suzanne L.

    2011-05-01

    Purpose: To evaluate the feasibility of dose-painting intensity-modulated radiation therapy (DP-IMRT) with a hypofractionated regimen to treat nasopharyngeal carcinoma (NPC) with concomitant toxicity reduction. Methods and Materials: From October 2002 through April 2007, 25 newly diagnosed NPC patients were enrolled in a prospective trial. DP-IMRT was prescribed to deliver 70.2 Gy using 2.34-Gy fractions to the gross tumor volume for the primary and nodal sites while simultaneously delivering 54 Gy in 1.8-Gy fractions to regions at risk of microscopic disease. Patients received concurrent and adjuvant platin-based chemotherapy similar to the Intergroup 0099 trial. Results: Patient and disease characteristics are as follows: median age, 46; 44% Asian; 68% male; 76% World Health Organization III; 20% T1, 52% T2, 16% T3, 12% T4; 20% N0, 36% N1, 36% N2, 8% N3. With median follow-up of 33 months, 3-year local control was 91%, regional control was 91%, freedom from distant metastases was 91%, and overall survival was 89%. The average mean dose to each cochlea was 43 Gy. With median audiogram follow-up of 14 months, only one patient had clinically significant (Grade 3) hearing loss. Twelve percent of patients developed temporal lobe necrosis; one patient required surgical resection. Conclusions: Preliminary findings using a hypofractionated DP-IMRT regimen demonstrated that local control, freedom from distant metastases, and overall survival compared favorably with other series of IMRT and chemotherapy. The highly conformal boost to the tumor bed resulted low rates of severe ototoxicity (Grade 3-4). However, the incidence of in-field brain radiation necrosis indicates that 2.34 Gy per fraction is not safe in this setting.

  16. Gel-layer dosimetry for dose verification in intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Tomatis, S.; Carrara, M.; Gambarini, G.; Marchesini, R.; Valente, M.

    2007-09-01

    Intensity-modulated radiotherapy (IMRT) is a technique in which the radiation fluence within each of the treatment beams is not uniformly distributed. This allows the patient dose to follow the boundaries even of a target volume of complex shape, and, virtually, to spare critical healthy organs at risk. The agreement between planned and delivered IMRT dose is verified by means of standard dosimetric methods such as film dosimetry or semiconductors array dosimetry. In this paper, we compare the output of a commercial device using an array of diodes for IMRT absolute dose verification with the output of a gel dosimeter, composed by a 10×8 cm 2 rectangular layer of a tissue-equivalent gel matrix in which a proper chemical dosimeter has been incorporated. The dose distribution is derived from the images of visible light transmittance, detected with a CCD camera before and after the gel exposure. The analysis was carried out on a single IMRT field chosen among those archived at the Istituto Nazionale Tumori of Milan. The radiation field was examined in an area common to both dosimeters. The agreement between the two detectors was good, as shown by analysis of dose profiles, especially for doses above 15-20 cGy. Gel dosimeter was in good agreement with the planned dose too, with a percentage of dosimeter points passing a dose to agreement test ranging between 90% and 93%. Although preliminary, our data suggest that gel dosimetry is a reliable method for IMRT dose verification. Due to the good spatial resolution and to the tissue equivalent properties of its composition, it would be suitable also for 3D IMRT dose reconstruction and verification in the form of multiple piled-up gel layers.

  17. Three-Year Outcomes of Breast Intensity-Modulated Radiation Therapy With Simultaneous Integrated Boost

    SciTech Connect

    McDonald, Mark W.; Godette, Karen D.; Whitaker, Daisy J.; Davis, Lawrence W.; Johnstone, Peter A.S.

    2010-06-01

    Purpose: To report our clinical experience using breast intensity-modulated radiation therapy with simultaneous integrated boost (SIB-IMRT). Methods and Materials: Retrospective review identified 354 Stage 0 to III breast cancer patients treated with SIB-IMRT after conservative surgery between 2003 and 2006. The most common fractionation (89%) simultaneously delivered 1.8 Gy to the ipsilateral breast tissue and 2.14 Gy to the resection cavity, yielding a breast dose of 45 Gy (25 fractions) and cavity dose 59.92 Gy (28 fractions), biologically equivalent for tumor control to 45 Gy to the breast with sequential 16-Gy boost (33 fractions). Results: A total of 356 breasts in 354 patients were treated: 282 with invasive breast cancer, and 74 with ductal carcinoma in situ (DCIS). For left breast radiation, median cardiac V{sub 15} was 2.9% and left ventricular V{sub 15} 1.7%. Median follow-up was 33 months (range, 4-73 months). Acute toxicity was Grade 1 in 57% of cases, Grade 2 in 43%, and Grade 3 in <1%. For invasive breast cancer, the 3-year overall survival was 97.6% and risk of any locoregional recurrence was 2.8%. For ductal carcinoma in situ, 3-year overall survival was 98% and risk of locoregional recurrence 1.4%. In 142 cases at a minimum of 3 years follow-up, global breast cosmesis was judged by physicians as good or excellent in 96.5% and fair in 3.5%. Conclusions: Breast SIB-IMRT reduced treatment duration by five fractions with a favorable acute toxicity profile and low cardiac dose for left breast treatment. At 3 years, locoregional control was excellent, and initial assessment suggested good or excellent cosmesis in a high percentage of evaluable patients.

  18. Ototoxicity After Intensity-Modulated Radiation Therapy and Cisplatin-Based Chemotherapy in Children With Medulloblastoma

    SciTech Connect

    Paulino, Arnold C.; Lobo, Mark; Teh, Bin S.; Okcu, M. Fatih; South, Michael; Butler, E. Brian; Su, Jack; Chintagumpala, Murali

    2010-12-01

    Purpose: To report the incidence of Pediatric Oncology Group (POG) Grade 3 or 4 ototoxicity in a cohort of patients treated with craniospinal irradiation (CSI) followed by posterior fossa (PF) and/or tumor bed (TB) boost using intensity-modulated radiation therapy (IMRT). Methods and Materials: From 1998 to 2006, 44 patients with medulloblastoma were treated with CSI followed by IMRT to the PF and/or TB and cisplatin-based chemotherapy. Patients with standard-risk disease were treated with 18 to 23.4 Gy CSI followed by either a (1) PF boost to 36 Gy and TB boost to 54 to 55.8 Gy or (2) TB boost to 55.8 Gy. Patients with high-risk disease received 36 to 39.6 Gy CSI followed by a (1) PF boost to 54 to 55.8 Gy, (2) PF boost to 45 Gy and TB boost to 55.8 Gy, or (3) TB boost to 55.8 Gy. Median audiogram follow-up was 41 months (range, 11-92.4 months). Results: POG Grade Ototoxicity 0, 1, 2, 3. and 4 was found in 29, 32, 11, 13. and 3 ears. respectively, with POG Grade 3 or 4 accounting for 18.2% of cases. There was a statistically significant difference in mean radiation dose (D{sub mean}) cochlea according to degree of ototoxicity, with D{sub mean} cochlea increasing with severity of hearing loss (p = 0.027). Conclusions: Severe ototoxicity was seen in 18.2% of ears in children treated with IMRT boost and cisplatin-based chemotherapy. Increasing dose to the cochlea was associated with increasing severity of hearing loss.

  19. Adoption of Intensity Modulated Radiation Therapy For Early-Stage Breast Cancer From 2004 Through 2011

    SciTech Connect

    Wang, Elyn H.; Mougalian, Sarah S.; Soulos, Pamela R.; Smith, Benjamin D.; Haffty, Bruce G.; Gross, Cary P.; Yu, James B.

    2015-02-01

    Purpose: Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. Methods and Materials: We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). Results: We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. Conclusions: The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status.

  20. Acute Esophagus Toxicity in Lung Cancer Patients After Intensity Modulated Radiation Therapy and Concurrent Chemotherapy

    SciTech Connect

    Kwint, Margriet; Uyterlinde, Wilma; Nijkamp, Jasper; Chen, Chun; Bois, Josien de; Sonke, Jan-Jakob; Heuvel, Michel van den; Knegjens, Joost; Herk, Marcel van; Belderbos, Jose

    2012-10-01

    Purpose: The purpose of this study was to investigate the dose-effect relation between acute esophageal toxicity (AET) and the dose-volume parameters of the esophagus after intensity modulated radiation therapy (IMRT) and concurrent chemotherapy for patients with non-small cell lung cancer (NSCLC). Patients and Methods: One hundred thirty-nine patients with inoperable NSCLC treated with IMRT and concurrent chemotherapy were prospectively analyzed. The fractionation scheme was 66 Gy in 24 fractions. All patients received concurrently a daily dose of cisplatin (6 mg/m Superscript-Two ). Maximum AET was scored according to Common Toxicity Criteria 3.0. Dose-volume parameters V5 to V70, D{sub mean} and D{sub max} of the esophagus were calculated. A logistic regression analysis was performed to analyze the dose-effect relation between these parameters and grade {>=}2 and grade {>=}3 AET. The outcome was compared with the clinically used esophagus V35 prediction model for grade {>=}2 after radical 3-dimensional conformal radiation therapy (3DCRT) treatment. Results: In our patient group, 9% did not experience AET, and 31% experienced grade 1 AET, 38% grade 2 AET, and 22% grade 3 AET. The incidence of grade 2 and grade 3 AET was not different from that in patients treated with CCRT using 3DCRT. The V50 turned out to be the most significant dosimetric predictor for grade {>=}3 AET (P=.012). The derived V50 model was shown to predict grade {>=}2 AET significantly better than the clinical V35 model (P<.001). Conclusions: For NSCLC patients treated with IMRT and concurrent chemotherapy, the V50 was identified as most accurate predictor of grade {>=}3 AET. There was no difference in the incidence of grade {>=}2 AET between 3DCRT and IMRT in patients treated with concurrent chemoradiation therapy.

  1. Intensity modulated radiation-therapy for preoperative posterior abdominal wall irradiation of retroperitoneal liposarcomas

    SciTech Connect

    Bossi, Alberto . E-mail: alberto.bossi@uz.kuleuven.ac.be; De Wever, Ivo; Van Limbergen, Erik; Vanstraelen, Bianca

    2007-01-01

    Purpose: Preoperative external-beam radiation therapy (preop RT) in the management of Retroperitoneal Liposarcomas (RPLS) typically involves the delivery of radiation to the entire tumor mass: yet this may not be necessary. The purpose of this study is to evaluate a new strategy of preop RT for RPLS in which the target volume is limited to the contact area between the tumoral mass and the posterior abdominal wall. Methods and Materials: Between June 2000 and Jan 2005, 18 patients with the diagnosis of RPLS have been treated following a pilot protocol of pre-op RT, 50 Gy in 25 fractions of 2 Gy/day. The Clinical Target Volume (CTV) has been limited to the posterior abdominal wall, region at higher risk for local relapse. A Three-Dimensional conformal (3D-CRT) and an Intensity Modulated (IMRT) plan were generated and compared; toxicity was reported following the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events v3.0. Results: All patients completed the planned treatment and the acute toxicity was tolerable: 2 patients experienced Grade 3 and 1 Grade 2 anorexia while 2 patients developed Grade 2 nausea. IMRT allows a better sparing of the ipsilateral and the contralateral kidney. All tumors were successfully resected without major complications. At a median follow-up of 27 months 2 patients developed a local relapse and 1 lung metastasis. Conclusions: Our strategy of preop RT is feasible and well tolerated: the rate of resectability is not compromised by limiting the preop CTV to the posterior abdominal wall and a better critical-structures sparing is obtained with IMRT.

  2. Vaginal Motion and Bladder and Rectal Volumes During Pelvic Intensity-Modulated Radiation Therapy After Hysterectomy

    SciTech Connect

    Jhingran, Anuja; Salehpour, Mohammad; Sam, Marianne; Levy, Larry; Eifel, Patricia J.

    2012-01-01

    Purpose: To evaluate variations in bladder and rectal volume and the position of the vaginal vault during a 5-week course of pelvic intensity-modulated radiation therapy (IMRT) after hysterectomy. Methods and Materials: Twenty-four patients were instructed how to fill their bladders before simulation and treatment. These patients underwent computed tomography simulations with full and empty bladders and then underwent rescanning twice weekly during IMRT; patients were asked to have full bladder for treatment. Bladder and rectal volumes and the positions of vaginal fiducial markers were determined, and changes in volume and position were calculated. Results: The mean full and empty bladder volumes at simulation were 480 cc (range, 122-1,052) and 155 cc (range, 49-371), respectively. Bladder volumes varied widely during IMRT: the median difference between the maximum and minimum volumes was 247 cc (range, 96-585). Variations in rectal volume during IMRT were less pronounced. For the 16 patients with vaginal fiducial markers in place throughout IMRT, the median maximum movement of the markers during IMRT was 0.59 cm in the right-left direction (range, 0-0.9), 1.46 cm in the anterior-posterior direction (range, 0.8-2.79), and 1.2 cm in the superior-inferior direction (range, 0.6-2.1). Large variations in rectal or bladder volume frequently correlated with significant displacement of the vaginal apex. Conclusion: Although treatment with a full bladder is usually preferred because of greater sparing of small bowel, our data demonstrate that even with detailed instruction, patients are unable to maintain consistent bladder filling. Variations in organ position during IMRT can result in marked changes in the position of the target volume and the volume of small bowel exposed to high doses of radiation.

  3. Electron-positron pair production from vacuum in the field of high-intensity laser radiation

    NASA Astrophysics Data System (ADS)

    Popov, V. S.; Mur, V. D.; Narozhnyi, N. B.; Popruzhenko, S. V.

    2016-03-01

    The works dealing with the theory of e + e - pair production from vacuum under the action of highintensity laser radiation are reviewed. The following problems are discussed: pair production in a constant electric field E and time-variable homogeneous field E( t); the dependence of the number of produced pairs {N_{{e^ + }{e^ - }}} on the shape of a laser pulse (dynamic Schwinger effect); and a realistic three-dimensional model of a focused laser pulse, which is based on exact solution of Maxwell's equations and contains parameters such as focal spot radius R, diffraction length L, focusing parameter Δ, pulse duration τ, and pulse shape. This model is used to calculate {N_{{e^ + }{e^ - }}} for both a single laser pulse ( n = 1) and several ( n ≥ 2) coherent pulses with a fixed total energy that simultaneously "collide" in a laser focus. It is shown that, at n ≫ 1, the number of pairs increases by several orders of magnitude as compared to the case of a single pulse. The screening of a laser field by the vapors that are generated in vacuum, its "depletion," and the limiting fields to be achieved in laser experiments are considered. The relation between pair production, the problem of a quantum frequency-variable oscillator, and the theory of groups SU(1, 1) and SU(2) is discussed. The relativistic version of the imaginary time method is used in calculations. In terms of this version, a relativistic theory of tunneling is developed and the Keldysh theory is generalized to the case of ionization of relativistic bound systems, namely, atoms and ions. The ionization rate of a hydrogen-like ion with a charge 1 ≤ Z ≤ 92 is calculated as a function of laser radiation intensity ( F and ellipticity ρ.

  4. Intensity-Modulated Radiation Therapy Significantly Improves Acute Gastrointestinal Toxicity in Pancreatic and Ampullary Cancers

    SciTech Connect

    Yovino, Susannah; Poppe, Matthew; Jabbour, Salma; David, Vera; Garofalo, Michael; Pandya, Naimesh; Alexander, Richard; Hanna, Nader; Regine, William F.

    2011-01-01

    Purpose: Among patients with upper abdominal malignancies, intensity-modulated radiation therapy (IMRT) can improve dose distributions to critical dose-limiting structures near the target. Whether these improved dose distributions are associated with decreased toxicity when compared with conventional three-dimensional treatment remains a subject of investigation. Methods and Materials: 46 patients with pancreatic/ampullary cancer were treated with concurrent chemoradiation (CRT) using inverse-planned IMRT. All patients received CRT based on 5-fluorouracil in a schema similar to Radiation Therapy Oncology Group (RTOG) 97-04. Rates of acute gastrointestinal (GI) toxicity for this series of IMRT-treated patients were compared with those from RTOG 97-04, where all patients were treated with three-dimensional conformal techniques. Chi-square analysis was used to determine if there was a statistically different incidence in acute GI toxicity between these two groups of patients. Results: The overall incidence of Grade 3-4 acute GI toxicity was low in patients receiving IMRT-based CRT. When compared with patients who had three-dimensional treatment planning (RTOG 97-04), IMRT significantly reduced the incidence of Grade 3-4 nausea and vomiting (0% vs. 11%, p = 0.024) and diarrhea (3% vs. 18%, p = 0.017). There was no significant difference in the incidence of Grade 3-4 weight loss between the two groups of patients. Conclusions: IMRT is associated with a statistically significant decrease in acute upper and lower GI toxicity among patients treated with CRT for pancreatic/ampullary cancers. Future clinical trials plan to incorporate the use of IMRT, given that it remains a subject of active investigation.

  5. A new Monte Carlo-based treatment plan optimization approach for intensity modulated radiation therapy.

    PubMed

    Li, Yongbao; Tian, Zhen; Shi, Feng; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

    2015-04-01

    Intensity-modulated radiation treatment (IMRT) plan optimization needs beamlet dose distributions. Pencil-beam or superposition/convolution type algorithms are typically used because of their high computational speed. However, inaccurate beamlet dose distributions may mislead the optimization process and hinder the resulting plan quality. To solve this problem, the Monte Carlo (MC) simulation method has been used to compute all beamlet doses prior to the optimization step. The conventional approach samples the same number of particles from each beamlet. Yet this is not the optimal use of MC in this problem. In fact, there are beamlets that have very small intensities after solving the plan optimization problem. For those beamlets, it may be possible to use fewer particles in dose calculations to increase efficiency. Based on this idea, we have developed a new MC-based IMRT plan optimization framework that iteratively performs MC dose calculation and plan optimization. At each dose calculation step, the particle numbers for beamlets were adjusted based on the beamlet intensities obtained through solving the plan optimization problem in the last iteration step. We modified a GPU-based MC dose engine to allow simultaneous computations of a large number of beamlet doses. To test the accuracy of our modified dose engine, we compared the dose from a broad beam and the summed beamlet doses in this beam in an inhomogeneous phantom. Agreement within 1% for the maximum difference and 0.55% for the average difference was observed. We then validated the proposed MC-based optimization schemes in one lung IMRT case. It was found that the conventional scheme required 10(6) particles from each beamlet to achieve an optimization result that was 3% difference in fluence map and 1% difference in dose from the ground truth. In contrast, the proposed scheme achieved the same level of accuracy with on average 1.2 × 10(5) particles per beamlet. Correspondingly, the computation

  6. A new Monte Carlo-based treatment plan optimization approach for intensity modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Li, Yongbao; Tian, Zhen; Shi, Feng; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

    2015-04-01

    Intensity-modulated radiation treatment (IMRT) plan optimization needs beamlet dose distributions. Pencil-beam or superposition/convolution type algorithms are typically used because of their high computational speed. However, inaccurate beamlet dose distributions may mislead the optimization process and hinder the resulting plan quality. To solve this problem, the Monte Carlo (MC) simulation method has been used to compute all beamlet doses prior to the optimization step. The conventional approach samples the same number of particles from each beamlet. Yet this is not the optimal use of MC in this problem. In fact, there are beamlets that have very small intensities after solving the plan optimization problem. For those beamlets, it may be possible to use fewer particles in dose calculations to increase efficiency. Based on this idea, we have developed a new MC-based IMRT plan optimization framework that iteratively performs MC dose calculation and plan optimization. At each dose calculation step, the particle numbers for beamlets were adjusted based on the beamlet intensities obtained through solving the plan optimization problem in the last iteration step. We modified a GPU-based MC dose engine to allow simultaneous computations of a large number of beamlet doses. To test the accuracy of our modified dose engine, we compared the dose from a broad beam and the summed beamlet doses in this beam in an inhomogeneous phantom. Agreement within 1% for the maximum difference and 0.55% for the average difference was observed. We then validated the proposed MC-based optimization schemes in one lung IMRT case. It was found that the conventional scheme required 106 particles from each beamlet to achieve an optimization result that was 3% difference in fluence map and 1% difference in dose from the ground truth. In contrast, the proposed scheme achieved the same level of accuracy with on average 1.2 × 105 particles per beamlet. Correspondingly, the computation time

  7. Polarization of Lyman-(alpha) Radiation from Atomic Hydrogen Excited by Electron Impact from Near-Threshold to 1800eV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Dziczek, D.

    1996-01-01

    The polarization of Lyman-(alpha) radiation, produced by electron impact excitation of atomic hydrogen, has been measured for the first time over the extended energy range from near-threshold to 1800eV. Measurements were obtained in a crossed-beams experiment using a silica-reflection linear polarization analyzer in tandem with a vacuum ultraviolet (VUV) monochromator to isolate the emitted line radiation.

  8. Whole Abdominopelvic Intensity-Modulated Radiation Therapy for Desmoplastic Small Round Cell Tumor After Surgery

    SciTech Connect

    Pinnix, Chelsea C.; Fontanilla, Hiral P.; Hayes-Jordan, Andrea; Subbiah, Vivek; Bilton, Stephen D.; Chang, Eric L.; Grosshans, David R.; McAleer, Mary F.; Sulman, Eric P.; Woo, Shiao Y.; Anderson, Peter; Green, Holly L.; Mahajan, Anita

    2012-05-01

    Purpose: Desmoplastic small round cell tumor (DSCRT) is an uncommon pediatric tumor with a poor prognosis. Aggressive multimodality therapy is the current treatment approach; however. treatment toxicity is of concern. We report our results with whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) as a component of multimodality therapy for DSCRT at a single institution. Materials/Methods: Medical records of all patients with DSCRT who received WAP-IMRT as part of definitive treatment at MD Anderson (2006-2010) were identified and reviewed. Results: Eight patients with DSRCT received WAP-IMRT with a median follow-up of 15.2 months. All patients received multiple courses of chemotherapy followed by surgical debulking of intra-abdominal disease; seven also had intraoperative hyperthermic cisplatin. WAP-IMRT was delivered to a total dose of 30 Gy postoperatively; four patients received a simultaneous boost (6-10 Gy) to sites of gross residual disease. Seven patients received concurrent chemotherapy during WAP-IMRT. No Radiation Therapy Oncology Group Grade 4 nausea, vomiting, or diarrhea occurred during RT. Red-cell transfusions were given to two patients to maintain hemoglobin levels >10 g/dL. Grade 4 cytopenia requiring growth factor support occurred in only one patient; no other significant cytopenias were noted. WAP-IMRT resulted in 25% lower radiation doses to the lumbosacral vertebral bodies and pelvic bones than conventional RT plans. The median time to local or distant failure after WAP-IMRT was 8.73 months in seven patients. One patient who had completed RT 20 months before the last follow-up remains alive without evidence of disease. Five patients (63%) experienced treatment failure in the abdomen. Distant failure occurred in three patients (37.5%). Conclusions: WAP-IMRT with concurrent radiosensitizing chemotherapy was well tolerated after aggressive surgery for DSCRT. Enhanced bone sparing with IMRT probably accounts for the low hematologic

  9. Quantification of beam complexity in intensity-modulated radiation therapy treatment plans

    SciTech Connect

    Du, Weiliang Cho, Sang Hyun; Zhang, Xiaodong; Kudchadker, Rajat J.; Hoffman, Karen E.

    2014-02-15

    Purpose: Excessive complexity in intensity-modulated radiation therapy (IMRT) plans increases the dose uncertainty, prolongs the treatment time, and increases the susceptibility to changes in patient or target geometry. To date, the tools for quantitative assessment of IMRT beam complexity are still lacking. In this study, The authors have sought to develop metrics to characterize different aspects of beam complexity and investigate the beam complexity for IMRT plans of different disease sites. Methods: The authors evaluated the beam complexity scores for 65 step-and-shoot IMRT plans from three sites (prostate, head and neck, and spine) and 26 volumetric-modulated arc therapy (VMAT) plans for the prostate. On the basis of the beam apertures and monitor unit weights of all segments, the authors calculated the mean aperture area, extent of aperture shape irregularity, and degree of beam modulation for each beam. Then the beam complexity values were averaged to obtain the complexity metrics of the IMRT plans. The authors studied the correlation between the beam complexity metrics and the quality assurance (QA) results. Finally, the effects of treatment planning parameters on beam complexity were studied. Results: The beam complexity scores were not uniform among the prostate IMRT beams from different gantry angles. The lateral beams had larger monitor units and smaller shape irregularity, while the anterior-posterior beams had larger modulation values. On average, the prostate IMRT plans had the smallest aperture irregularity, beam modulation, and normalized monitor units; the head and neck IMRT plans had large beam irregularity and beam modulation; and the spine stereotactic radiation therapy plans often had small beam apertures, which may have been associated with the relatively large discrepancies between planned and QA measured doses. There were weak correlations between the beam complexity scores and the measured dose errors. The prostate VMAT beams showed

  10. Spectral evolution of non-thermal electron distributions in intense radiation fields

    NASA Astrophysics Data System (ADS)

    Manolakou, K.; Horns, D.; Kirk, J. G.

    2007-11-01

    Context: Models of many astrophysical gamma-ray sources assume they contain a homogeneous distribution of electrons that are injected as a power law in energy and evolve by interacting with radiation fields, magnetic fields, and particles in the source and by escaping. This problem is particularly complicated if the radiation fields have higher energy density than the magnetic field and are sufficiently energetic that inverse Compton scattering is not limited to the Thomson regime. Aims: We present a simple, time-dependent, semi-analytical solution to the electron kinetic equation that treats both continuous and impulsive injection, cooling via synchrotron and inverse Compton radiation (taking Klein-Nishina effects into account), and energy-dependent particle escape. We used this solution to calculate the temporal evolution of the multi-wavelength spectrum of systems where energetic electrons cool in intense photon fields. Methods: The kinetic equation for an arbitrary, time-dependent source function is solved by the method of Laplace transformations. Using an approximate expression for the energy-loss rate that takes synchrotron and inverse Compton losses into account, including Klein-Nishina effects for scattering off an isotropic photon field with either a power-law or black-body distribution, we find explicit expressions for the cooling time and escape probability of individual electrons. This enables the full, time-dependent solution to be reduced to a single quadrature. From the electron distribution, we then construct the time-dependent, multi-wavelength emission spectrum. Results: We compare our solutions with several limiting cases and discuss the general appearance and temporal behaviour of spectral features (i.e., cooling breaks, bumps, etc.). As a specific example, we model the broad-band energy spectrum of the open stellar association Westerlund-2 at different times of its evolution, and compare it with observations. The model calculation matches the

  11. Cumulative radiation exposure from diagnostic imaging in intensive care unit patients

    PubMed Central

    Moloney, Fiachra; Fama, Daniel; Twomey, Maria; O’Leary, Ruth; Houlihane, Conor; Murphy, Kevin P; O’Neill, Siobhan B; O’Connor, Owen J; Breen, Dorothy; Maher, Michael M

    2016-01-01

    AIM: To quantify cumulative effective dose of intensive care unit (ICU) patients attributable to diagnostic imaging. METHODS: This was a prospective, interdisciplinary study conducted in the ICU of a large tertiary referral and level 1 trauma center. Demographic and clinical data including age, gender, date of ICU admission, primary reason for ICU admission, APACHE II score, length of stay, number of days intubated, date of death or discharge, and re-admission data was collected on all patients admitted over a 1-year period. The overall radiation exposure was quantified by the cumulative effective radiation dose (CED) in millisieverts (mSv) and calculated using reference effective doses published by the United Kingdom National Radiation Protection Board. Pediatric patients were selected for subgroup-analysis. RESULTS: A total of 2737 studies were performed in 421 patients. The total CED was 1704 mSv with a median CED of 1.5 mSv (IQR 0.04-6.6 mSv). Total CED in pediatric patients was 74.6 mSv with a median CED of 0.07 mSv (IQR 0.01-4.7 mSv). Chest radiography was the most commonly performed examination accounting for 83% of all studies but only 2.7% of total CED. Computed tomography (CT) accounted for 16% of all studies performed and contributed 97% of total CED. Trauma patients received a statistically significant higher dose [median CED 7.7 mSv (IQR 3.5-13.8 mSv)] than medical [median CED 1.4 mSv (IQR 0.05-5.4 mSv)] and surgical [median CED 1.6 mSv (IQR 0.04-7.5 mSv)] patients. Length of stay in ICU [OR = 1.12 (95%CI: 1.079-1.157)] was identified as an independent predictor of receiving a CED greater than 15 mSv. CONCLUSION: Trauma patients and patients with extended ICU admission times are at increased risk of higher CEDs. CED should be minimized where feasible, especially in young patients. PMID:27158429

  12. EBT GAFCHROMIC{sup TM} film dosimetry in compensator-based intensity modulated radiation therapy

    SciTech Connect

    Vaezzadeh, Seyedali; Allahverdi, Mahmoud; Nedaie, Hasan A.; Ay, Mohammadreza; Shirazi, Alireza; Yarahmadi, Mehran

    2013-07-01

    The electron benefit transfer (EBT) GAFCHROMIC films possess a number of features making them appropriate for high-quality dosimetry in intensity-modulated radiation therapy (IMRT). Compensators to deliver IMRT are known to change the beam-energy spectrum as well as to produce scattered photons and to contaminate electrons; therefore, the accuracy and validity of EBT-film dosimetry in compensator-based IMRT should be investigated. Percentage-depth doses and lateral-beam profiles were measured using EBT films in perpendicular orientation with respect to 6 and 18 MV photon beam energies for: (1) different thicknesses of cerrobend slab (open, 1.0, 2.0, 4.0, and 6.0 cm), field sizes (5×5, 10×10, and 20×20 cm{sup 2}), and measurement depths (D{sub max}, 5.0 and 10.0 cm); and (2) step-wedged compensator in a solid phantom. To verify results, same measurements were implemented using a 0.125 cm{sup 3} ionization chamber in a water phantom and also in Monte Carlo simulations using the Monte Carlo N-particle radiation transport computer code. The mean energy of photons was increased due to beam hardening in comparison with open fields at both 6 and 18 MV energies. For a 20×20 cm{sup 2} field size of a 6 MV photon beam and a 6.0 cm thick block, the surface dose decreased by about 12% and percentage-depth doses increased up to 3% at 30.0 cm depth, due to the beam-hardening effect induced by the block. In contrast, at 18 MV, the surface dose increased by about 8% and depth dose reduced by 3% at 30.0 cm depth. The penumbral widths (80% to 20%) increase with block thickness, field size, and beam energy. The EBT film results were in good agreement with the ionization chamber dose profiles and Monte Carlo N-particle radiation transport computer code simulation behind the step-wedged compensator. Also, there was a good agreement between the EBT-film and the treatment-planning results on the anthropomorphic phantom. The EBT films can be accurately used as a 2D dosimeter for dose

  13. The 27-day versus 13.5-day variations in the solar Lyman-alpha radiation and the radio wave absorption in the lower ionosphere over Europe

    NASA Technical Reports Server (NTRS)

    Delamorena, B. A.; Lastovicka, Jan; Rapoport, Z. TS.; Alberca, L.

    1989-01-01

    In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio wave absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha variation on time scale day-month is the solar rotation variation (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by variations of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.

  14. Radiation promotes malignant progression of glioma cells through HIF-1alpha stabilization.

    PubMed

    Kim, Young-Heon; Yoo, Ki-Chun; Cui, Yan-Hong; Uddin, Nizam; Lim, Eun-Jung; Kim, Min-Jung; Nam, Seon-Young; Kim, In-Gyu; Suh, Yongjoon; Lee, Su-Jae

    2014-11-01

    Given its contribution to malignant phenotypes of cancer, tumor hypoxia has been considered as a potential therapeutic problem. In the stressful microenvironment condition, hypoxia inducible factor 1 (HIF1) is well known to mediate the transcriptional adaptation of cells to hypoxia and acts as a central player for the process of hypoxia-driven malignant cancer progression. Here, we found that irradiation causes the HIF1α protein to stabilize, even in normoxia condition through activation of p38 MAPK, thereby promoting angiogenesis in tumor microenvironment and infiltrative property of glioma cells. Notably, irradiation reduced hydroxylation of HIF1α through destabilization of prolyl hydroxylases (PHD)-2. Moreover, radiation also decreased the half-life of protein von Hippel-Lindau (pVHL), which is a specific E3 ligase for HIF1α. Of note, inhibition of p38 MAPK attenuated radiation-induced stabilization of HIF1α through destabilization of PHD-2 and pVHL. In agreement with these results, targeting of either p38 MAPK, HIF1α, pVHL or PHD-2 effectively mitigated the radiation-induced tube formation of human brain-derived micro-vessel endothelial cells (HB-MEC) and infiltration of glioma cells. Taken together, our findings suggest that targeting HIF1α in combination with ionizing radiation might increase the efficacy of radiotherapy for glioma treatment. PMID:25109450

  15. Induction of immunogenic cell death by radiation-upregulated karyopherin alpha 2 in vitro.

    PubMed

    Song, Kyung-Hee; Jung, Seung-Youn; Kang, Seong-Mook; Kim, Mi-Hyoung; Ahn, Jiyeon; Hwang, Sang-Gu; Lee, Jun-Ho; Lim, Dae-Seog; Nam, Seon Young; Song, Jie-Young

    2016-01-01

    Accumulating evidence suggests the potential for radiation therapy to generate antitumor immune responses against tumor cells by inducing immunogenic cell death and phenotypic changes. We recently found that ionizing radiation upregulated karyopherin α2 (KPNA2) in HT-29 colorectal tumor cells using quantitative proteomic analysis. To determine whether this increased KPNA2 could function as a damage-associated molecular pattern to induce antitumor immune responses, mouse bone-marrow-derived dendritic cells (BMDCs) were treated with KPNA2. KPNA2 enhanced the surface expression of CD40, CD54, CD80, CD86, and MHC class I/II on BMDCs. DCs treated with KPNA2 exhibited increased secretion of pro-inflammatory cytokines such as IL-1β, IL-6, IL-12, IL-23, and TNF-α. Co-culture of CD4(+) T cells and KPNA2-treated DCs resulted in induction of Th1/17 cytokines (IFN-γ and IL-17) and reduction of TGF-β production. Moreover, KPNA2-treated DCs were capable of increasing granzyme B and perforin expression in cytotoxic T lymphocytes. These results demonstrated that radiation-induced dying colorectal cancer cells released considerable amounts of KPNA2 that induce the maturation and activation of DCs for synergistic antitumor effect of radiation. PMID:27107455

  16. Risk of secondary cancers from scattered radiation during intensity-modulated radiotherapies for hepatocellular carcinoma

    PubMed Central

    2014-01-01

    Purpose To evaluate and compare the risks of secondary cancers from therapeutic doses received by patients with hepatocellular carcinoma (HCC) during intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and tomotherapy (TOMO). Methods Treatments for five patients with hepatocellular carcinoma (HCC) were planned using IMRT, VMAT, and TOMO. Based on the Biological Effects of Ionizing Radiation VII method, the excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) were evaluated from therapeutic doses, which were measured using radiophotoluminescence glass dosimeters (RPLGDs) for each organ inside a humanoid phantom. Results The average organ equivalent doses (OEDs) of 5 patients were measured as 0.23, 1.18, 0.91, 0.95, 0.97, 0.24, and 0.20 Gy for the thyroid, lung, stomach, liver, small intestine, prostate (or ovary), and rectum, respectively. From the OED measurements, LAR incidence were calculated as 83, 46, 22, 30, 2 and 6 per 104 person for the lung, stomach, normal liver, small intestine, prostate (or ovary), and rectum. Conclusions We estimated the secondary cancer risks at various organs for patients with HCC who received different treatment modalities. We found that HCC treatment is associated with a high secondary cancer risk in the lung and stomach. PMID:24886163

  17. The accuracy of inhomogeneity corrections in intensity modulated radiation therapy planning in Philips Pinnacle system.

    PubMed

    Alaei, Parham; Higgins, Patrick D

    2011-01-01

    The degree of accuracy of inhomogeneity corrections in a treatment planning system is dependent on the algorithm used by the system. The choice of field size, however, could have an effect on the calculation accuracy as well. There have been several evaluation studies on the accuracy of inhomogeneity corrections used by different algorithms. Most of these studies, however, focus on evaluating the dose in phantom using simplified geometry and open/static fields. This work focuses on evaluating the degree of dose accuracy in calculations involving intensity-modulated radiation therapy (IMRT) fields incident on a phantom containing both lung- and bone-equivalent heterogeneities using 6 and 10 MV beams. IMRT treatment plans were generated using the Philips Pinnacle treatment planning system and delivered to a phantom containing 55 thermoluminescent dosimeter (TLD) locations within the lung and bone and near the lung and bone interfaces with solid water. The TLD readings were compared with the dose predicted by the planning system. We find satisfactory agreement between planned and delivered doses, with an overall absolute average difference between measurement and calculation of 1.2% for the 6 MV and 3.1% for the 10 MV beam with larger variations observed near the interfaces and in areas of high-dose gradient. The results presented here demonstrate that the convolution algorithm used in the Pinnacle treatment planning system produces accurate results in IMRT plans calculated and delivered to inhomogeneous media, even in regions that potentially lack electronic equilibrium. PMID:20627517

  18. The Accuracy of Inhomogeneity Corrections in Intensity Modulated Radiation Therapy Planning in Philips Pinnacle System

    SciTech Connect

    Alaei, Parham; Higgins, Patrick D.

    2011-10-01

    The degree of accuracy of inhomogeneity corrections in a treatment planning system is dependent on the algorithm used by the system. The choice of field size, however, could have an effect on the calculation accuracy as well. There have been several evaluation studies on the accuracy of inhomogeneity corrections used by different algorithms. Most of these studies, however, focus on evaluating the dose in phantom using simplified geometry and open/static fields. This work focuses on evaluating the degree of dose accuracy in calculations involving intensity-modulated radiation therapy (IMRT) fields incident on a phantom containing both lung- and bone-equivalent heterogeneities using 6 and 10 MV beams. IMRT treatment plans were generated using the Philips Pinnacle treatment planning system and delivered to a phantom containing 55 thermoluminescent dosimeter (TLD) locations within the lung and bone and near the lung and bone interfaces with solid water. The TLD readings were compared with the dose predicted by the planning system. We find satisfactory agreement between planned and delivered doses, with an overall absolute average difference between measurement and calculation of 1.2% for the 6 MV and 3.1% for the 10 MV beam with larger variations observed near the interfaces and in areas of high-dose gradient. The results presented here demonstrate that the convolution algorithm used in the Pinnacle treatment planning system produces accurate results in IMRT plans calculated and delivered to inhomogeneous media, even in regions that potentially lack electronic equilibrium.

  19. Meningioma Causing Visual Impairment: Outcomes and Toxicity After Intensity Modulated Radiation Therapy

    SciTech Connect

    Maclean, Jillian; Fersht, Naomi; Bremner, Fion; Stacey, Chris; Sivabalasingham, Suganya; Short, Susan

    2013-03-15

    Purpose: To evaluate ophthalmologic outcomes and toxicity of intensity modulated radiation therapy (IMRT) in patients with meningiomas causing visual deficits. Methods and Materials: A prospective observational study with formal ophthalmologic and clinical assessment of 30 consecutive cases of meningioma affecting vision treated with IMRT from 2007 to 2011. Prescriptions were 50.4 Gy to mean target dose in 28 daily fractions. The median follow-up time was 28 months. Twenty-six meningiomas affected the anterior visual pathway (including 3 optic nerve sheath meningiomas); 4 were posterior to the chiasm. Results: Vision improved objectively in 12 patients (40%). Improvements were in visual field (5/16 patients), color vision (4/9 patients), acuity (1/15 patients), extraocular movements (3/11 patients), ptosis (1/5 patients), and proptosis (2/6 patients). No predictors of clinical response were found. Two patients had minor reductions in tumor dimensions on magnetic resonance imaging, 1 patient had radiological progression, and the other patients were stable. One patient experienced grade 2 keratitis, 1 patient had a minor visual field loss, and 5 patients had grade 1 dry eye. Conclusion: IMRT is an effective method for treating meningiomas causing ophthalmologic deficits, and toxicity is minimal. Thorough ophthalmologic assessment is important because clinical responses often occur in the absence of radiological change.

  20. Dosimetric comparison of tools for intensity modulated radiation therapy with gamma analysis: a phantom study

    NASA Astrophysics Data System (ADS)

    Akbas, Ugur; Okutan, Murat; Demir, Bayram; Koksal, Canan

    2015-07-01

    Dosimetry of the Intensity Modulated Radiation Therapy (IMRT) is very important because of the complex dose distributions. Diode arrays are the most common and practical measurement tools for clinical usage for IMRT. Phantom selection is critical for QA process. IMRT treatment plans are recalculated for the phantom irradiation in QA. Phantoms are made in different geometrical shapes to measure the doses of different types of irradiation techniques. Comparison of measured and calculated dose distributions for IMRT can be made by using gamma analysis. In this study, 10 head-and-neck IMRT QA plans were created with Varian Eclipse 8.9 treatment planning system. Water equivalent RW3-slab phantoms, Octavius-2 phantom and PTW Seven29 2D-array were used for QA measurements. Gantry, collimator and couch positions set to 00 and QA plans were delivered to RW3 and Octavius phantoms. Then the positions set to original angles and QA plans irradiated again. Measured and calculated fluence maps were evaluated with gamma analysis for different DD and DTA criteria. The effect of different set-up conditions for RW3 and Octavius phantoms in QA plan delivery evaluated by gamma analysis. Results of gamma analysis show that using RW3-slab phantoms with setting parameters to 00 is more appropriate for IMRT QA.

  1. Dosimetric evaluations of the interplay effect in respiratory-gated intensity-modulated radiation therapy

    SciTech Connect

    Chen Hungcheng; Wu, Andrew; Brandner, Edward D.; Heron, Dwight E.; Huq, M. Saiful; Yue, Ning J.; Chen Wencheng

    2009-03-15

    The interplay between a mobile target and a dynamic multileaf collimator can compromise the accuracy of intensity-modulated radiation therapy (IMRT). Our goal in this study is to investigate the dosimetric effects caused by the respiratory motion during IMRT. A moving phantom was built to simulate the typical breathing motion. Different sizes of the gating windows were selected for gated deliveries. The residual motions during the beam-on period ranged from 0.5 to 3 cm. An IMRT plan with five treatment fields from different gantry angles were delivered to the moving phantom for three irradiation conditions: Stationary condition, moving with the use of gating system, and moving without the use of gating system. When the residual motion was 3 cm, the results showed significant differences in dose distributions between the stationary condition and the moving phantom without gating beam control. The overdosed or underdosed areas enclosed about 33% of the treatment area. In contrast, the dose distribution on the moving phantom with gating window set to 0.5 cm showed no significant differences from the stationary phantom. With the appropriate setting of the gating window, the deviation of dose from the respiratory motion can be minimized. It appeals that limiting the residual motion to less than 0.5 cm is critical for the treatments of mobile structures.

  2. A nested partitions framework for beam angle optimization in intensity-modulated radiation therapy.

    PubMed

    D'Souza, Warren D; Zhang, Hao H; Nazareth, Daryl P; Shi, Leyuan; Meyer, Robert R

    2008-06-21

    Coupling beam angle optimization with dose optimization in intensity-modulated radiation therapy (IMRT) increases the size and complexity of an already large-scale combinatorial optimization problem. We have developed a novel algorithm, nested partitions (NP), that is capable of finding suitable beam angle sets by guiding the dose optimization process. NP is a metaheuristic that is flexible enough to guide the search of a heuristic or deterministic dose optimization algorithm. The NP method adaptively samples from the entire feasible region, or search space, and coordinates the sampling effort with a systematic partitioning of the feasible region at successive iterations, concentrating the search in promising subsets. We used a 'warm-start' approach by initiating NP with beam angle samples derived from an integer programming (IP) model. In this study, we describe our implementation of the NP framework with a commercial optimization algorithm. We compared the NP framework with equi-spaced beam angle selection, the IP method, greedy heuristic and random sampling heuristic methods. The results of the NP approach were evaluated using two clinical cases (head and neck and whole pelvis) involving the primary tumor and nodal volumes. Our results show that NP produces better quality solutions than the alternative considered methods. PMID:18523351

  3. A nested partitions framework for beam angle optimization in intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    D'Souza, Warren D.; Zhang, Hao H.; Nazareth, Daryl P.; Shi, Leyuan; Meyer, Robert R.

    2008-06-01

    Coupling beam angle optimization with dose optimization in intensity-modulated radiation therapy (IMRT) increases the size and complexity of an already large-scale combinatorial optimization problem. We have developed a novel algorithm, nested partitions (NP), that is capable of finding suitable beam angle sets by guiding the dose optimization process. NP is a metaheuristic that is flexible enough to guide the search of a heuristic or deterministic dose optimization algorithm. The NP method adaptively samples from the entire feasible region, or search space, and coordinates the sampling effort with a systematic partitioning of the feasible region at successive iterations, concentrating the search in promising subsets. We used a 'warm-start' approach by initiating NP with beam angle samples derived from an integer programming (IP) model. In this study, we describe our implementation of the NP framework with a commercial optimization algorithm. We compared the NP framework with equi-spaced beam angle selection, the IP method, greedy heuristic and random sampling heuristic methods. The results of the NP approach were evaluated using two clinical cases (head and neck and whole pelvis) involving the primary tumor and nodal volumes. Our results show that NP produces better quality solutions than the alternative considered methods.

  4. Intensity-modulated radiation therapy for malignancies of the nasal cavity and paranasal sinuses

    SciTech Connect

    Daly, Megan E.; Chen, Allen M. . E-mail: allenmchen@yahoo.com; Bucci, M. Kara; El-Sayed, Ivan; Xia Ping; Kaplan, Michael J.; Eisele, David W.

    2007-01-01

    Purpose: To report the clinical outcome of patients treated with intensity-modulated radiation therapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 1998 and 2004, 36 patients with malignancies of the sinonasal region were treated with IMRT. Thirty-two patients (89%) were treated in the postoperative setting after gross total resection. Treatment plans were designed to provide a dose of 70 Gy to 95% or more of the gross tumor volume (GTV) and 60 Gy to 95% or more of the clinical tumor volume (CTV) while sparing neighboring critical structures including the optic chiasm, optic nerves, eyes, and brainstem. The primary sites were: 13 ethmoid sinus, 10 maxillary sinus, 7 nasal cavity, and 6 other. Histology was: 12 squamous cell, 7 esthesioneuroblastoma, 5 adenoid cystic, 5 undifferentiated, 5 adenocarcinoma, and 2 other. Median follow-up was 51 months among surviving patients (range, 9-82 months). Results: The 2-year and 5-year estimates of local control were 62% and 58%, respectively. One patient developed isolated distant metastasis, and none developed isolated regional failure. The 5-year rates of disease-free and overall survival were 55% and 45%, respectively. The incidence of ocular toxicity was minimal with no patients reporting decreased vision. Late complications included xerophthalmia (1 patient), lacrimal stenosis (1 patient), and cataract (1 patient). Conclusion: Although IMRT for malignancies of the sinonasal region does not appear to lead to significant improvements in disease control, the low incidence of complications is encouraging.

  5. Organisational standards for the delivery of intensity-modulated radiation therapy in Ontario.

    PubMed

    Whitton, A; Warde, P; Sharpe, M; Oliver, T K; Bak, K; Leszczynski, K; Etheridge, S; Fleming, K; Gutierrez, E; Favell, L; Green, E

    2009-04-01

    By minimising the effect of irradiation on surrounding tissue, intensity-modulated radiation therapy (IMRT) can deliver higher, more effective doses to the targeted tumour site, minimising treatment-related morbidity and possibly improving cancer control and cure. A multidisciplinary IMRT Expert Panel was convened to develop the organisational standards for the delivery of IMRT. The systematic literature search used MEDLINE, EMBASE, the Cochrane Database, the National Guidelines Clearing House and the Health Technology Assessment Database. An environmental scan of unpublished literature used the Google search engine to review the websites of key organisations, cancer agencies/centres and vendor sites in Canada, the USA, Australia and Europe. In total, 22 relevant guidance documents were identified; 12 from the published literature and 10 from the environmental scan. Professional and organisational standards for the provision of IMRT were developed through the analysis of this evidence and the consensus opinion of the IMRT Expert Panel. The resulting standards address the following domains: planning of new IMRT programmes, practice setting requirements, tools, devices and equipment requirements; professional training requirements; role of personnel; and requirements for quality assurance and safety. Here the IMRT Expert Panel offers organisational and professional standards for the delivery of IMRT, with the intent of promoting innovation, improving access and enhancing patient care. PMID:19062263

  6. In vivo measurements with MOSFET detectors in oropharynx and nasopharynx intensity-modulated radiation therapy

    SciTech Connect

    Marcie, Serge . E-mail: serge.marcie@cal.nice.fnclcc.fr; Charpiot, Elisabeth; Bensadoun, Rene-Jean; Ciais, Gaston; Herault, Joel; Costa, Andre; Gerard, Jean-Pierre

    2005-04-01

    Purpose: To evaluate the feasibility of in vivo measurements with metal oxide semiconductor field effect transistor (MOSFET) dosimeters for oropharynx and nasopharynx intensity-modulated radiation therapy (IMRT). Methods and Materials: During a 1-year period, in vivo measurements of the dose delivered to one or two points of the oral cavity by IMRT were obtained with MOSFET dosimeters. Measurements were obtained during each session of 48 treatment plans for 21 patients, all of whom were fitted with a custom-made mouth plate. Calculated and measured values were compared. Results: A total of 344 and 452 measurements were performed for the right and left sides, respectively, of the oral cavity. Seventy percent of the discrepancies between calculated and measured values were within {+-}5%. Uncertainties were due to interfraction patient positions, intrafraction patient movements, and interfraction MOSFET positions. Nevertheless, the discrepancies between the measured and calculated means were within {+-}5% for 92% and 95% of the right and left sides, respectively. Comparison of these discrepancies and the discrepancies between calculated values and measurements made on a phantom revealed that all differences were within {+-}5%. Conclusion: Our experience demonstrates the feasibility of in vivo measurements with MOSFET dosimeters for oropharynx and nasopharynx IMRT.

  7. Setup errors in patients treated with intensity-modulated whole pelvic radiation therapy for gynecological malignancies

    SciTech Connect

    Haslam, Joshua J.; Lujan, Anthony E.; Mundt, Arno J.; Bonta, Dacian V.; Roeske, John C. . E-mail: Roeske@rover.uchicago.edu

    2005-03-31

    Intensity-modulated whole pelvic radiation therapy (IM-WPRT) has decreased the incidence of gastrointestinal complications by reducing the volume of normal tissue irradiated in gynecologic patients. However, IM-WPRT plans result in steep dose gradients around the target volume, and thus accurate patient setup is essential. To quantify the accuracy of our patient positioning, we examined the weekly portal films of 46 women treated with IM-WPRT at our institution. All patients were positioned using a customized immobilization device that was indexed to the treatment table. Setup errors were evaluated by comparing portal images to simulation images using an algorithm that registers user-defined open curve segments drawn on both sets of film. The setup errors, which were separated into systematic and random components, ranged from 1.9 to 3.7 mm for the translations and 1.3 deg to 4.4 deg for the 2 in-plane translations. The systematic errors were all less than the respective random errors, with the largest error in the anterior/posterior direction. In addition, there was no correlation between the magnitude of these errors and patient-specific factors (age, weight, height). In the future, we will investigate the effect of these setup errors on the delivered dose distribution.

  8. Combining segment generation with direct step-and-shoot optimization in intensity-modulated radiation therapy

    SciTech Connect

    Carlsson, Fredrik

    2008-09-15

    A method for generating a sequence of intensity-modulated radiation therapy step-and-shoot plans with increasing number of segments is presented. The objectives are to generate high-quality plans with few, large and regular segments, and to make the planning process more intuitive. The proposed method combines segment generation with direct step-and-shoot optimization, where leaf positions and segment weights are optimized simultaneously. The segment generation is based on a column generation approach. The method is evaluated on a test suite consisting of five head-and-neck cases and five prostate cases, planned for delivery with an Elekta SLi accelerator. The adjustment of segment shapes by direct step-and-shoot optimization improves the plan quality compared to using fixed segment shapes. The improvement in plan quality when adding segments is larger for plans with few segments. Eventually, adding more segments contributes very little to the plan quality, but increases the plan complexity. Thus, the method provides a tool for controlling the number of segments and, indirectly, the delivery time. This can support the planner in finding a sound trade-off between plan quality and treatment complexity.

  9. Radiation-Hydrodynamic Simulation of Experiments With Intense Lasers Generating Collisionless Interpenetrating Plasmas

    NASA Astrophysics Data System (ADS)

    Grosskopf, Michael; Drake, R.; Kuranz, C.; Park, H.; Kugland, N.; Pollaine, S.; Ross, J.; Remington, B.; Spitkovsky, A.; Gargate, L.; Gregori, G.; Bell, A.; Murphy, C.; Meinecke, J.; Reville, B.; Sakawa, Y.; Kuramitsu, Y.; Takabe, H.; Froula, D.; Fiksel, G.; Miniati, F.; Koenig, M.; Ravasio, A.; Liang, E.; Woolsey, N.

    2012-05-01

    Collisionless shocks, shocks generated by plasma wave interactions in regions where the collisional mean-free-path for ions is long compared to the length scale for instabilities that generate magnetic fields, are found in many astrophysical systems such as supernova remnants and planetary bow shocks. Generating conditions to investigate collisionless shock physics is difficult to achieve in a laboratory setting; however, high-energy-density physics facilities have made this a possibility. Experiments whose goal is to investigate the production and growth of magnetic fields in collisionless shocks in laboratory-scale systems are being carried out on intense lasers, several of which are measuring the plasma properties and magnetic field strength in counter-streaming, collisionless flows generated by laser ablation. This poster reports radiation-hydrodynamic simulations using the CRASH code to model the ablative flow of plasma generated in order to assess potential designs, as well as infer properties of collected data from previous experiments. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-FG52-09NA29548, and by the National Laser User Facility Program, grant number DE-NA0000850.

  10. Racial Differences in Diffusion of Intensity-Modulated Radiation Therapy for Localized Prostate Cancer.

    PubMed

    Cobran, Ewan K; Chen, Ronald C; Overman, Robert; Meyer, Anne-Marie; Kuo, Tzy-Mey; O'Brien, Jonathon; Sturmer, Til; Sheets, Nathan C; Goldin, Gregg H; Penn, Dolly C; Godley, Paul A; Carpenter, William R

    2016-09-01

    Intensity-modulated radiation therapy (IMRT), an innovative treatment option for prostate cancer, has rapidly diffused over the past decade. To inform our understanding of racial disparities in prostate cancer treatment and outcomes, this study compared diffusion of IMRT in African American (AA) and Caucasian American (CA) prostate cancer patients during the early years of IMRT diffusion using the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database. A retrospective cohort of 947 AA and 10,028 CA patients diagnosed with localized prostate cancer from 2002 through 2006, who were treated with either IMRT or non-IMRT as primary treatment within 1 year of diagnoses was constructed. Logistic regression was used to examine potential differences in diffusion of IMRT in AA and CA patients, while adjusting for socioeconomic and clinical covariates. A significantly smaller proportion of AA compared with CA patients received IMRT for localized prostate cancer (45% vs. 53%, p < .0001). Racial differences were apparent in multivariable analysis though did not achieve statistical significance, as time and factors associated with race (socioeconomic, geographic, and tumor related factors) explained the preponderance of variance in use of IMRT. Further research examining improved access to innovative cancer treatment and technologies is essential to reducing racial disparities in cancer care. PMID:25657192

  11. Plutonium radiation surrogate

    DOEpatents

    Frank, Michael I.

    2010-02-02

    A self-contained source of gamma-ray and neutron radiation suitable for use as a radiation surrogate for weapons-grade plutonium is described. The source generates a radiation spectrum similar to that of weapons-grade plutonium at 5% energy resolution between 59 and 2614 keV, but contains no special nuclear material and emits little .alpha.-particle radiation. The weapons-grade plutonium radiation surrogate also emits neutrons having fluxes commensurate with the gamma-radiation intensities employed.

  12. Genomic Profiling of a Human Leukemic Monocytic Cell-Line (THP-1) Exposed to Alpha Particle Radiation

    PubMed Central

    Chauhan, Vinita; Howland, Matthew

    2012-01-01

    This study examined alpha (α-) particle radiation effects on global changes in gene expression in human leukemic monocytic cells (THP-1) for the purposes of mining for candidate biomarkers that could be used for the development of a biological assessment tool. THP-1 cells were exposed to α-particle radiation at a dose range of 0 to 1.5 Gy. Twenty-four hours and three days after exposure gene expression was monitored using microarray technology. A total of 16 genes were dose responsive and classified as early onset due to their expression 24 h after exposure. Forty-eight transcripts were dose responsive and classified as late-onset as they were expressed 72 h after exposure. Among these genes, 6 genes were time and dose responsive and validated further using alternate technology. These transcripts were upregulated and associated with biological processes related to immune function, organelle stability and cell signalling/communication. This panel of genes merits further validation to determine if they are strong candidate biomarkers indicative of α-particle exposure. PMID:23097634

  13. International comparison of cave radon concentrations identifying the potential alpha radiation risks to British cave users

    SciTech Connect

    Hyland, R.; Gunn, J.

    1994-08-01

    Elevated concentrations of {sup 222}Rn have been recorded in many limestone caves throughout the world. As prolonged exposure to high radon concentrations has been linked to cancer and tumors, particularly of the lung, a national survey of radon in British caves was undertaken. Passive radon detectors were exposed at 250 sites in 47 caves over four 7-d sampling periods. Mean concentrations ranging from 454-8,868 Bq m{sup {minus}3} were recorded. In one system, in the Peak District, radon concentrations of 155,000 Bq m{sup {minus}3} were recorded. The results indicate that the potential radiation dose from a single 4-h trip could exceed the national average annual background radiation dose (for the UK) from radon of 1.25 mSv. 18 refs., 3 tabs.

  14. International comparison of cave radon concentrations identifying the potential alpha radiation risks to British cave users.

    PubMed

    Hyland, R; Gunn, J

    1994-08-01

    Elevated concentrations of 222Rn have been recorded in many limestone caves throughout the world. As prolonged exposure to high radon concentrations has been linked to cancer and tumors, particularly of the lung (National Academy of Science 1988; Eatough and Henshaw 1990), a national survey of radon in British caves was undertaken. Passive radon detectors were exposed at 250 sites in 47 caves over four 7-d sampling periods. Mean concentrations ranging from 454-8,868 Bq m-3 were recorded. In one system, in the Peak District, radon concentrations of 155,000 Bq m-3 were recorded. The results indicate that the potential radiation dose from a single 4-h trip could exceed the national average annual background radiation dose (for the UK) from radon of 1.25 mSv. PMID:8026972

  15. Tumorigenic action of beta, proton, alpha and electron radiation on the rat skin

    SciTech Connect

    Burns, F.J.

    1980-01-01

    Rat skin is utilized as a model system for studying dose and time related aspects of the oncogenic action of ionizing radiation, ultraviolet light and polycyclic aromatic hydrocarbons. Molecular lesions in the DNA of the epidermis, including strand breaks and thymine dimers, are measured and compared to the temporal and dose related aspects of tumor induction. The induction and repair kinetics of molecular lesions are compared to split dose recovery as modified by sensitizers and type of radition of oncogenic damage.

  16. Alpha Lipoic Acid Attenuates Radiation-Induced Thyroid Injury in Rats

    PubMed Central

    Jung, Jung Hwa; Jung, Jaehoon; Kim, Soo Kyoung; Woo, Seung Hoon; Kang, Ki Mun; Jeong, Bae-Kwon; Jung, Myeong Hee; Kim, Jin Hyun; Hahm, Jong Ryeal

    2014-01-01

    Exposure of the thyroid to radiation during radiotherapy of the head and neck is often unavoidable. The present study aimed to investigate the protective effect of α-lipoic acid (ALA) on radiation-induced thyroid injury in rats. Rats were randomly assigned to four groups: healthy controls (CTL), irradiated (RT), received ALA before irradiation (ALA + RT), and received ALA only (ALA, 100 mg/kg, i.p.). ALA was treated at 24 h and 30 minutes prior to irradiation. The neck area including the thyroid gland was evenly irradiated with 2 Gy per minute (total dose of 18 Gy) using a photon 6-MV linear accelerator. Greater numbers of abnormal and unusually small follicles in the irradiated thyroid tissues were observed compared to the controls and the ALA group on days 4 and 7 after irradiation. However, all pathologies were decreased by ALA pretreatment. The quantity of small follicles in the irradiated rats was greater on day 7 than day 4 after irradiation. However, in the ALA-treated irradiated rats, the numbers of small and medium follicles were significantly decreased to a similar degree as in the control and ALA-only groups. The PAS-positive density of the colloid in RT group was decreased significantly compared with all other groups and reversed by ALA pretreatment. The high activity index in the irradiated rats was lowered by ALA treatment. TGF-ß1 immunoreactivity was enhanced in irradiated rats and was more severe on the day 7 after radiation exposure than on day 4. Expression of TGF-ß1 was reduced in the thyroid that had undergone ALA pretreatment. Levels of serum pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) did not differ significantly between the all groups. This study provides that pretreatment with ALA decreased the severity of radiation-induced thyroid injury by reducing inflammation and fibrotic infiltration and lowering the activity index. Thus, ALA could be used to ameliorate radiation-induced thyroid injury. PMID:25401725

  17. The 55-kD tumor necrosis factor receptor on human keratinocytes is regulated by tumor necrosis factor-alpha and by ultraviolet B radiation.

    PubMed Central

    Trefzer, U; Brockhaus, M; Lötscher, H; Parlow, F; Budnik, A; Grewe, M; Christoph, H; Kapp, A; Schöpf, E; Luger, T A

    1993-01-01

    In previous studies we showed that cultured human keratinocytes expressed the 55-kD TNF receptor (TNFR) and that its expression the important for TNF alpha-mediated upregulation of intercellular adhesion molecule-1 (ICAM-1) expression on keratinocytes. Because factors that either reduce or enhance TNFR expression are likely to have a major impact on the biological effects of TNF alpha on keratinocytes, these studies were conducted to determine the factors that regulate its expression on keratinocytes. Using reverse transcriptase polymerase chain reaction, human keratinocytes were shown to lack 75-kD TNFR expression, indicating that TNF responsiveness of human keratinocytes critically depended on regulation of 55-kD TNFR expression. Human keratinocyte 55-kD TNFR surface and mRNA expression was found to be regulated in vitro by recombinant human (rh) TNF alpha. Stimulation of keratinocytes with rhTNF alpha initially decreased, but later increased, 55-kD TNFR surface expression. This biphasic modulation of 55-kD TNFR surface expression was associated with concomitant changes in 55-kD TNFR mRNA expression. Ultraviolet B (UVB) radiation, a well-known inducer of synthesis and secretion of TNF alpha by human keratinocytes, was found to mimic TNF alpha-induced modulation of 55-kD TNFR surface and mRNA expression via a TNF alpha-mediated autocrine regulatory mechanism. Production of soluble 55-kD TNFR by human keratinocytes remained unaffected by TNF alpha stimulation or UVB irradiation. These studies provide clear evidence that membrane expression of the human 55-kD TNFR may be regulated in human keratinocytes by the ligand itself: TNF alpha. Since in previous studies UVB irradiation transiently inhibited TNF alpha-induced human keratinocyte ICAM-1 expression, it is proposed that UVB radiation-induced biphasic modulation of human keratinocyte 55-kD TNFR expression may affect the capacity of these cells to respond to TNF alpha. Images PMID:8392091

  18. Assessing software upgrades, plan properties and patient geometry using intensity modulated radiation therapy (IMRT) complexity metrics

    SciTech Connect

    McGarry, Conor K.; Chinneck, Candice D.; O'Toole, Monica M.; O'Sullivan, Joe M; Prise, Kevin M.; Hounsell, Alan R.

    2011-04-15

    Purpose: The aim of this study is to compare the sensitivity of different metrics to detect differences in complexity of intensity modulated radiation therapy (IMRT) plans following upgrades, changes to planning parameters, and patient geometry. Correlations between complexity metrics are also assessed. Method: A program was developed to calculate a series of metrics used to describe the complexity of IMRT fields using monitor units (MUs) and multileaf collimator files: Modulation index (MI), modulation complexity score (MCS), and plan intensity map variation (PIMV). Each metric, including the MUs, was used to assess changes in beam complexity for six prostate patients, following upgrades in the inverse planning optimization software designed to incorporate direct aperture optimization (DAO). All beams were delivered to a 2D ionization chamber array and compared to those calculated using gamma analysis. Each complexity metric was then calculated for all beams, on a different set of six prostate IMRT patients, to assess differences between plans calculated using different minimum field sizes and different maximum segment numbers. Different geometries, including CShape, prostate, and head and neck phantoms, were also assessed using the metrics. Correlations between complexity metrics were calculated for 20 prostate IMRT patients. Results: MU, MCS, MI, and PIMV could all detect reduced complexity following an upgrade to the optimization leaf sequencer, although only MI and MCS could detect a reduction in complexity when one-step optimization (DAO) was employed rather than two-step optimization. All metrics detected a reduction in complexity when the minimum field size was increased from 1 to 4 cm and all apart from PIMV detected reduced complexity when the number of segments was significantly reduced. All metrics apart from MI showed differences in complexity depending on the treatment site. Significant correlations exist between all metrics apart from MI and PIMV for

  19. Specific outcomes of the research on the radiation stability of the French nuclear glass towards alpha decay accumulation

    NASA Astrophysics Data System (ADS)

    Peuget, S.; Delaye, J.-M.; Jégou, C.

    2014-01-01

    This paper presents an overview of the main results of the French research on the long-term behavior of SON68 nuclear glass towards alpha decay accumulation. The effect of the radiation damage induced by alpha decay and also helium build-up were investigated by examining glass specimens, doped with a short-lived actinide 244Cm, irradiated by light and heavy ions. Additionally, atomistic simulations by molecular dynamics have provided further information on the atomic-scale effects of the macroscopic phenomena observed. These studies have shown that some macroscopic properties vary with the accumulation of alpha decay, but then stabilize after integrated doses of the order of 4 × 1018 α g-1. For example, the glass density diminishes by about 0.6%, its Young's modulus by about 15%, and its hardness by about 30%, while its fracture toughness increases by around 50%. The SEM and TEM characterization showed that the glass is still homogeneous. No phase separation, crystallization or bubbles formation was noticed up to an alpha decay dose corresponding to several thousand years of disposal of nuclear glass canister. Moreover the initial alteration rate of the glass is not significantly affected by the glass damage induced by alpha decays or heavy ions irradiations. The comparison of the macroscopic evolutions of the Cm doped glass with those obtained for glasses irradiated with light or heavy ions (from either experimental and molecular dynamic studies) suggests that the macroscopic evolutions are induced by the nuclear interactions induced by the recoil nuclei of alpha decay. The analysis of the behavior of the glass structure subjected to ballistic effects with various spectroscopic studies, together with the results of atomistic modeling by molecular dynamics, have identified some slight changes in the local order around some cations. Moreover a modification of the medium-range order has also been demonstrated through changes in the bond angles between network

  20. Intensity Modulated Proton Beam Radiation for Brachytherapy in Patients With Cervical Carcinoma

    SciTech Connect

    Clivio, Alessandro; Kluge, Anne; Cozzi, Luca; Köhler, Christhardt; Neumann, Oliver; Vanetti, Eugenio; Wlodarczyk, Waldemar; Marnitz, Simone

    2013-12-01

    Purpose: To evaluate intensity modulated proton therapy (IMPT) in patients with cervical cancer in terms of coverage, conformity, and dose–volume histogram (DVH) parameters correlated with recommendations from magnetic resonance imaging (MRI)-guided brachytherapy. Methods and Materials: Eleven patients with histologically proven cervical cancer underwent primary chemoradiation for the pelvic lymph nodes, the uterus, the cervix, and the parametric region, with a symmetric margin of 1 cm. The prescription was for 50.4 Gy, with 1.8 Gy per fraction. The prescribed dose to the parametria was 2.12 Gy up to 59.36 Gy in 28 fractions as a simultaneous boost. For several reasons, the patients were unable to undergo brachytherapy. As an alternative, IMPT was planned with 5 fractions of 6 Gy to the cervix, including the macroscopic tumor with an MRI-guided target definition, with an isotropic margin of 5 mm for planning target volume (PTV) definition. Groupe-Europeen de Curietherapie and European society for Radiotherapy and Oncology (GEC-ESTRO) criteria were used for DVH evaluation. Reference comparison plans were optimized for volumetric modulated rapid arc (VMAT) therapy with the RapidArc (RA). Results: The dose to the high-risk volume was calculated with α/β = 10 with 89.6 Gy. For IMPT, the clinical target volume showed a mean dose of 38.2 ± 5.0 Gy (35.0 ±1.8 Gy for RA). The D{sub 98%} was 31.9 ± 2.6 Gy (RA: 30.8 ± 1.0 Gy). With regard to the organs at risk, the 2Gy Equivalent Dose (EQD2) (α/β = 3) to 2 cm{sup 3} of the rectal wall, sigmoid wall, and bladder wall was 62.2 ± 6.4 Gy, 57.8 ± 6.1 Gy, and 80.6 ± 8.7 Gy (for RA: 75.3 ± 6.1 Gy, 66.9 ± 6.9 Gy, and 89.0 ± 7.2 Gy, respectively). For the IMPT boost plans in combination with external beam radiation therapy, all DVH parameters correlated with <5% risk for grades 2 to 4 late gastrointestinal and genitourinary toxicity. Conclusion: In patients who are not eligible for brachytherapy, IMPT as a boost

  1. A feedback constraint optimization method for intensity-modulated radiation therapy of nasopharyngeal carcinoma

    PubMed Central

    LI, YONGWU; SUN, XIAONAN; WANG, QI; ZHOU, QINXUAN; GU, BENXING; SHI, GUOZHI; JIANG, DONGLIANG

    2015-01-01

    Intensity-modulated radiation therapy (IMRT) is able to achieve good target conformance with a limited dose to organs at risk (OARs); however, IMRT increases the irradiation volume and monitor units (MUs) required. The present study aimed to evaluate the use of an IMRT plan with fewer segments and MUs, while maintaining quality in the treatment of nasopharyngeal carcinoma. In the present study, two types of IMRT plan were therefore compared: The direct machine parameter optimization (DMPO)-RT method and the feedback constraint DMPO-RT (fc_DMPO-RT) method, which utilizes compensative feedback constraint in DMPO-RT and maintains optimization. Plans for 23 patients were developed with identical dose prescriptions. Each plan involved synchronous delivery to various targets, with identical OAR constraints, by means of 7 coplanar fields. The average dose, maximum dose, dose-volume histograms of targets and the OAR, MUs of the plan, the number of segments, delivery time and accuracy were subsequently compared. The fc_DMPO-RT exhibited superior dose distribution in terms of the average, maximum and minimum doses to the gross tumor volume compared with that of DMPO-RT (t=62.7, 20.5 and 22.0, respectively; P<0.05). The fc_DMPO-RT also resulted in a smaller maximum dose to the spinal cord (t=7.3; P<0.05), as well as fewer MUs, fewer segments and decreased treatment times than that of the DMPO-RT (t=6.2, 393.4 and 244.3, respectively; P<0.05). The fc_DMPO-RT maintained plan quality with fewer segments and MUs, and the treatment time was significantly reduced, thereby resulting in reduced radiation leakage and an enhanced curative effect. Therefore, introducing feedback constraint into DMPO may result in improved IMRT planning. In nasopharyngeal carcinoma specifically, feedback constraint resulted in the improved protection of OARs in proximity of targets (such as the brainstem and parotid) due to sharp dose distribution and reduced MUs. PMID:26622793

  2. Treatment of Oral Cavity Squamous Cell Carcinoma With Adjuvant or Definitive Intensity-Modulated Radiation Therapy

    SciTech Connect

    Sher, David J.; Thotakura, Vijaya; Balboni, Tracy A.; Norris, Charles M.; Haddad, Robert I.; Posner, Marshall R.; Lorch, Jochen; Goguen, Laura A.; Annino, Donald J.; Tishler, Roy B.

    2011-11-15

    Purpose: The optimal management of oral cavity squamous cell carcinoma (OCSCC) typically involves surgical resection followed by adjuvant radiotherapy or chemoradiotherapy (CRT) in the setting of adverse pathologic features. Intensity-modulated radiation therapy (IMRT) is frequently used to treat oral cavity cancers, but published IMRT outcomes specific to this disease site are sparse. We report the Dana-Farber Cancer Institute experience with IMRT-based treatment for OCSCC. Methods and Materials: Retrospective study of all patients treated at Dana-Farber Cancer Institute for OCSCC with adjuvant or definitive IMRT between August 2004 and December 2009. The American Joint Committee on Cancer disease stage criteria distribution of this cohort included 5 patients (12%) with stage I; 10 patients (24%) with stage II (n = 10, 24%),; 14 patients (33%) with stage III (n = 14, 33%),; and 13 patients (31%) with stage IV. The primary endpoint was overall survival (OS); secondary endpoints were locoregional control (LRC) and acute and chronic toxicity. Results: Forty-two patients with OCSCC were included, 30 of whom were initially treated with surgical resection. Twenty-three (77%) of 30 surgical patients treated with adjuvant IMRT also received concurrent chemotherapy, and 9 of 12 (75%) patients treated definitively without surgery were treated with CRT or induction chemotherapy and CRT. With a median follow-up of 2.1 years (interquartile range, 1.1-3.1 years) for all patients, the 2-year actuarial rates of OS and LRC following adjuvant IMRT were 85% and 91%, respectively, and the comparable results for definitive IMRT were 63% and 64% for OS and LRC, respectively. Only 1 patient developed symptomatic osteoradionecrosis, and among patients without evidence of disease, 35% experienced grade 2 to 3 late dysphagia, with only 1 patient who was continuously gastrostomy-dependent. Conclusions: In this single-institution series, postoperative IMRT was associated with promising LRC

  3. Leakage-Penumbra effect in intensity modulated radiation therapy step-and-shoot dose delivery

    PubMed Central

    Grigorov, Grigor N; Chow, James CL

    2016-01-01

    AIM: To study the leakage-penumbra (LP) effect with a proposed correction method for the step-and-shoot intensity modulated radiation therapy (IMRT). METHODS: Leakage-penumbra dose profiles from 10 randomly selected prostate IMRT plans were studied. The IMRT plans were delivered by a Varian 21 EX linear accelerator equipped with a 120-leaf multileaf collimator (MLC). For each treatment plan created by the Pinnacle3 treatment planning system, a 3-dimensional LP dose distribution generated by 5 coplanar photon beams, starting from 0o with equal separation of 72o, was investigated. For each photon beam used in the step-and-shoot IMRT plans, the first beam segment was set to have the largest area in the MLC leaf-sequencing, and was equal to the planning target volume (PTV). The overshoot effect (OSE) and the segment positional errors were measured using a solid water phantom with Kodak (TL and X-OMAT V) radiographic films. Film dosimetric analysis and calibration were carried out using a film scanner (Vidar VXR-16). The LP dose profiles were determined by eliminating the OSE and segment positional errors with specific individual irradiations. RESULTS: A non-uniformly distributed leaf LP dose ranging from 3% to 5% of the beam dose was measured in clinical IMRT beams. An overdose at the gap between neighboring segments, represented as dose peaks of up to 10% of the total BP, was measured. The LP effect increased the dose to the PTV and surrounding critical tissues. In addition, the effect depends on the number of beams and segments for each beam. Segment positional error was less than the maximum tolerance of 1 mm under a dose rate of 600 monitor units per minute in the treatment plans. The OSE varying with the dose rate was observed in all photon beams, and the effect increased from 1 to 1.3 Gy per treatment of the rectal intersection. As the dosimetric impacts from the LP effect and OSE may increase the rectal post-radiation effects, a correction of LP was proposed and

  4. The Analysis of Data from Voyager's Ultraviolet Spectrometers: The Trend of Observed Interplanetary Lyman-alpha Intensity with Increasing Heliocentric Distance for Multiple Viewing Directions

    NASA Astrophysics Data System (ADS)

    Gilbert, C. R.; Fayock, B.; Heerikhuisen, J.; Zank, G. P.

    2014-12-01

    The motivation for this project was simple: to reduce raw data from the Ultraviolet Spectrometers on both Voyager Spacecraft to verify the results of a simulation of Lyman-alpha radiative transfer within a 3D MHD kinetic-neutral model of the heliosphere created at the University of Alabama in Huntsville. The heliospheric model, which self-consistently includes the interaction between ionized and neutral hydrogen, outputs a density map of neutral hydrogen. The Monte Carlo radiative transfer model then simulates the propagation and scattering of millions of photons through this density map and outputs the relative number of photons that should be seen by spacecraft at any point within 1000 AU of the sun. My project was to learn how to analyze the raw Voyager data and compare it to these simulations. There were several stages of analysis necessary to reduce to useful data. Records containing signals from sources other than the interplanetary medium, such as stars and planets, were discarded. The remaining records were averaged along regional lines of sight to achieve better signal to noise. The spectra were then corrected for inherent device flaws, such as channel-to-channel variations in sensitivity (fixed-pattern noise), dark counts due to the radioisotope thermal electric generator, and imperfections in the scattering of the diffraction grating. Records were then sorted and averaged to create a full-sky map consisting of 18 regions for each specified radial bin to match the cell spacing of the radiative transfer model. The results were then normalized to solar minimum to reduce variations in the data due to solar cycle oscillations. Initial results indicate an unexpected deviation from the models, but more analysis must be performed to determine if the discrepancy comes from the normalization of the data, insufficient angular resolution of the radiative transfer model, or the physics of the models themselves. Future work involves increasing the resolution of the

  5. Determination of Jet Noise Radiation Patterns and Source Locations using 2-Dimensional Intensity Measurements

    NASA Technical Reports Server (NTRS)

    Jaeger, S. M.; Allen, C. S.

    1999-01-01

    Contents include the following: (1) Outline Jet Noise extrapolation to far field. (2) Two dimensional sound intensity. (3) Anechoic chamber cold jet test. (4) Results: Intensity levels. Vector maps. Source location centroids. Directivity. and (5) Conclusions.

  6. An integral quality monitoring system for real-time verification of intensity modulated radiation therapy

    SciTech Connect

    Islam, Mohammad K.; Norrlinger, Bernhard D.; Smale, Jason R.; Heaton, Robert K.; Galbraith, Duncan; Fan, Cary; Jaffray, David A.

    2009-12-15

    Purpose: To develop an independent and on-line beam monitoring system, which can validate the accuracy of segment-by-segment energy fluence delivery for each treatment field. The system is also intended to be utilized for pretreatment dosimetric quality assurance of intensity modulated radiation therapy (IMRT), on-line image-guided adaptive radiation therapy, and volumetric modulated arc therapy. Methods: The system, referred to as the integral quality monitor (IQM), utilizes an area integrating energy fluence monitoring sensor (AIMS) positioned between the final beam shaping device [i.e., multileaf collimator (MLC)] and the patient. The prototype AIMS consists of a novel spatially sensitive large area ionization chamber with a gradient along the direction of the MLC motion. The signal from the AIMS provides a simple output for each beam segment, which is compared in real time to the expected value. The prototype ionization chamber, with a physical area of 22x22 cm{sup 2}, has been constructed out of aluminum with the electrode separations varying linearly from 2 to 20 mm. A calculation method has been developed to predict AIMS signals based on an elementwise integration technique, which takes into account various predetermined factors, including the spatial response function of the chamber, MLC characteristics, beam transmission through the secondary jaws, and field size factors. The influence of the ionization chamber on the beam has been evaluated in terms of transmission, surface dose, beam profiles, and depth dose. The sensitivity of the system was tested by introducing small deviations in leaf positions. A small set of IMRT fields for prostate and head and neck plans was used to evaluate the system. The ionization chamber and the data acquisition software systems were interfaced to two different types of linear accelerators: Elekta Synergy and Varian iX. Results: For a 10x10 cm{sup 2} field, the chamber attenuates the beam intensity by 7% and 5% for 6 and 18

  7. Utility of Normal Tissue-to-Tumor {alpha}/{beta} Ratio When Evaluating Isodoses of Isoeffective Radiation Therapy Treatment Plans

    SciTech Connect

    Gay, Hiram A.; Jin Jianyue; Chang, Albert J.; Ten Haken, Randall K.

    2013-01-01

    Purpose: To achieve a better understanding of the effect of the number of fractions on normal tissue sparing for equivalent tumor control in radiation therapy plans by using equivalent biologically effective dose (BED) isoeffect calculations. Methods and Materials: The simple linear quadratic (LQ) model was assumed to be valid up to 10 Gy per fraction. Using the model, we formulated a well-known mathematical equality for the tumor prescription dose and probed and solved a second mathematical problem for normal tissue isoeffect. That is, for a given arbitrary relative isodose distribution (treatment plan in percentages), 2 isoeffective tumor treatment regimens (N fractions of the dose D and n fractions of the dose d) were denoted, which resulted in the same BED (corresponding to 100% prescription isodose). Given these situations, the LQ model was further exploited to mathematically establish a unique relative isodose level, z (%), for the same arbitrary treatment plan, where the BED to normal tissues was also isoeffective for both fractionation regimens. Results: For the previously stated problem, the relative isodose level z (%), where the BEDs to the normal tissue were also equal, was defined by the normal tissue {alpha}/{beta} ratio divided by the tumor {alpha}/{beta} times 100%. Fewer fractions offers a therapeutic advantage for those portions of the normal tissue located outside the isodose surface, z, whereas more fractions offer a therapeutic advantage for those portions of the normal tissue within the isodose surface, z. Conclusions: Relative isodose-based treatment plan evaluations may be useful for comparing isoeffective tumor regimens in terms of normal tissue effects. Regions of tissues that would benefit from hypofractionation or standard fractionation can be identified.

  8. Isotope effect in the photochemical decomposition of CO{sub 2} (ice) by Lyman-{alpha} radiation

    SciTech Connect

    Yuan Chunqing; Yates, John T. Jr.

    2013-04-21

    The photochemical decomposition of CO{sub 2}(ice) at 75 K by Lyman-{alpha} radiation (10.2 eV) has been studied using transmission infrared spectroscopy. An isotope effect in the decomposition of the CO{sub 2} molecule in the ice has been discovered, favoring {sup 12}CO{sub 2} photodecomposition over {sup 13}CO{sub 2} by about 10%. The effect is caused by electronic energy transfer from the excited CO{sub 2} molecule to the ice matrix, which favors quenching of the heavier electronically-excited {sup 13}CO{sub 2} molecule over {sup 12}CO{sub 2}. The effect is similar to the Menzel-Gomer-Redhead isotope effect in desorption from adsorbed molecules on surfaces when electronically excited. An enhancement of the rate of formation of lattice-trapped CO and CO{sub 3} species is observed for the photolysis of the {sup 12}CO{sub 2} molecule compared to the {sup 13}CO{sub 2} molecule in the ice. Only 0.5% of the primary photoexcitation results in O-CO bond dissociation to produce trapped-CO and trapped-CO{sub 3} product molecules and the majority of the electronically-excited CO{sub 2} molecules return to the ground state. Here either vibrational relaxation occurs (majority process) or desorption of CO{sub 2} occurs (minority process) from highly vibrationally-excited CO{sub 2} molecules in the ice. The observation of the {sup 12}C/{sup 13}C isotope effect in the Lyman-{alpha} induced photodecomposition of CO{sub 2} (ice) suggests that over astronomical time scales the isotope enrichment effect may distort historical information derived from isotope ratios in space wherever photochemistry can occur.

  9. Intense attosecond radiation from an X-ray FEL - extended version

    SciTech Connect

    Zholents, Alexander A.; Fawley, William M.

    2003-12-01

    We propose the use of a ultra-relativistic electron beam interacting with a few-cycle, intense laser pulse and an intense pulse of the coherent x-rays to produce a multi-MW intensity, x-ray pulses {approx}100 attoseconds in duration. Due to a naturally-occurring frequency chirp, these pulses can be further temporally compressed.

  10. Replanning During Intensity Modulated Radiation Therapy Improved Quality of Life in Patients With Nasopharyngeal Carcinoma

    SciTech Connect

    Yang Haihua; Hu Wei; Wang Wei; Chen Peifang; Ding Weijun; Luo Wei

    2013-01-01

    Purpose: Anatomic and dosimetric changes have been reported during intensity modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the effects of replanning on quality of life (QoL) and clinical outcomes during the course of IMRT for NPC patients. Methods and Materials: Between June 2007 and August 2011, 129 patients with NPC were enrolled. Forty-three patients received IMRT without replanning, while 86 patients received IMRT replanning after computed tomography (CT) images were retaken part way through therapy. Chinese versions of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 and Head and Neck Quality of Life Questionnaire 35 were completed before treatment began and at the end of treatment and at 1, 3, 6, and 12 months after the completion of treatment. Overall survival (OS) data were compared using the Kaplan-Meier method. Results: IMRT replanning had a profound impact on the QoL of NPC patients, as determined by statistically significant changes in global QoL and other QoL scales. Additionally, the clinical outcome comparison indicates that replanning during IMRT for NPC significantly improved 2-year local regional control (97.2% vs 92.4%, respectively, P=.040) but did not improve 2-year OS (89.8% vs 82.2%, respectively, P=.475). Conclusions: IMRT replanning improves QoL as well as local regional control in patients with NPC. Future research is needed to determine the criteria for replanning for NPC patients undergoing IMRT.

  11. Automatically-generated rectal dose constraints in intensity-modulated radiation therapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Hwang, Taejin; Kim, Yong Nam; Kim, Soo Kon; Kang, Sei-Kwon; Cheong, Kwang-Ho; Park, Soah; Yoon, Jai-Woong; Han, Taejin; Kim, Haeyoung; Lee, Meyeon; Kim, Kyoung-Joo; Bae, Hoonsik; Suh, Tae-Suk

    2015-06-01

    The dose constraint during prostate intensity-modulated radiation therapy (IMRT) optimization should be patient-specific for better rectum sparing. The aims of this study are to suggest a novel method for automatically generating a patient-specific dose constraint by using an experience-based dose volume histogram (DVH) of the rectum and to evaluate the potential of such a dose constraint qualitatively. The normal tissue complication probabilities (NTCPs) of the rectum with respect to V %ratio in our study were divided into three groups, where V %ratio was defined as the percent ratio of the rectal volume overlapping the planning target volume (PTV) to the rectal volume: (1) the rectal NTCPs in the previous study (clinical data), (2) those statistically generated by using the standard normal distribution (calculated data), and (3) those generated by combining the calculated data and the clinical data (mixed data). In the calculated data, a random number whose mean value was on the fitted curve described in the clinical data and whose standard deviation was 1% was generated by using the `randn' function in the MATLAB program and was used. For each group, we validated whether the probability density function (PDF) of the rectal NTCP could be automatically generated with the density estimation method by using a Gaussian kernel. The results revealed that the rectal NTCP probability increased in proportion to V %ratio , that the predictive rectal NTCP was patient-specific, and that the starting point of IMRT optimization for the given patient might be different. The PDF of the rectal NTCP was obtained automatically for each group except that the smoothness of the probability distribution increased with increasing number of data and with increasing window width. We showed that during the prostate IMRT optimization, the patient-specific dose constraints could be automatically generated and that our method could reduce the IMRT optimization time as well as maintain the

  12. Disease Control and Ototoxicity Using Intensity-Modulated Radiation Therapy Tumor-Bed Boost for Medulloblastoma

    SciTech Connect

    Polkinghorn, William R.; Dunkel, Ira J.; Souweidane, Mark M.; Khakoo, Yasmin; Lyden, David C.; Gilheeney, Stephen W.; Becher, Oren J.; Budnick, Amy S.; Wolden, Suzanne L.

    2011-11-01

    Purpose: We previously reported excellent local control for treating medulloblastoma with a limited boost to the tumor bed. In order to decrease ototoxicity, we subsequently implemented a tumor-bed boost using intensity-modulated radiation therapy (IMRT), the clinical results of which we report here. Patients and Methods: A total of 33 patients with newly diagnosed medulloblastoma, 25 with standard risk, and 8 with high risk, were treated on an IMRT tumor-bed boost following craniospinal irradiation (CSI). Six standard-risk patients were treated with an institutional protocol with 18 Gy CSI in conjunction with intrathecal iodine-131-labeled monoclonal antibody. The majority of patients received concurrent vincristine and standard adjuvant chemotherapy. Pure-tone audiograms were graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: Median age was 9 years old (range, 4-46 years old). Median follow-up was 63 months. Kaplan-Meier estimates of progression-free survival (PFS) and overall survival (OS) rates for standard-risk patients who received 23.4 or 36 Gy CSI (not including those who received 18 Gy CSI with radioimmunotherapy) were 81.4% and 88.4%, respectively, at 5 years; 5-year PFS and OS rates for high-risk patients were both 87.5%. There were no isolated posterior fossa failures outside of the boost volume. Posttreatment audiograms were available for 31 patients, of whom 6%, at a median follow-up of 19 months, had developed Grade 3 hearing loss. Conclusion: An IMRT tumor-bed boost results in excellent local control while delivering a low mean dose to the cochlea, resulting in a low rate of ototoxicity.

  13. Automation and Intensity Modulated Radiation Therapy for Individualized High-Quality Tangent Breast Treatment Plans

    SciTech Connect

    Purdie, Thomas G.; Dinniwell, Robert E.; Fyles, Anthony; Sharpe, Michael B.

    2014-11-01

    Purpose: To demonstrate the large-scale clinical implementation and performance of an automated treatment planning methodology for tangential breast intensity modulated radiation therapy (IMRT). Methods and Materials: Automated planning was used to prospectively plan tangential breast IMRT treatment for 1661 patients between June 2009 and November 2012. The automated planning method emulates the manual steps performed by the user during treatment planning, including anatomical segmentation, beam placement, optimization, dose calculation, and plan documentation. The user specifies clinical requirements of the plan to be generated through a user interface embedded in the planning system. The automated method uses heuristic algorithms to define and simplify the technical aspects of the treatment planning process. Results: Automated planning was used in 1661 of 1708 patients receiving tangential breast IMRT during the time interval studied. Therefore, automated planning was applicable in greater than 97% of cases. The time for treatment planning using the automated process is routinely 5 to 6 minutes on standard commercially available planning hardware. We have shown a consistent reduction in plan rejections from plan reviews through the standard quality control process or weekly quality review multidisciplinary breast rounds as we have automated the planning process for tangential breast IMRT. Clinical plan acceptance increased from 97.3% using our previous semiautomated inverse method to 98.9% using the fully automated method. Conclusions: Automation has become the routine standard method for treatment planning of tangential breast IMRT at our institution and is clinically feasible on a large scale. The method has wide clinical applicability and can add tremendous efficiency, standardization, and quality to the current treatment planning process. The use of automated methods can allow centers to more rapidly adopt IMRT and enhance access to the documented

  14. Beam orientation optimization for intensity modulated radiation therapy using adaptive l2,1-minimization

    NASA Astrophysics Data System (ADS)

    Jia, Xun; Men, Chunhua; Lou, Yifei; Jiang, Steve B.

    2011-10-01

    Beam orientation optimization (BOO) is a key component in the process of intensity modulated radiation therapy treatment planning. It determines to what degree one can achieve a good treatment plan in the subsequent plan optimization process. In this paper, we have developed a BOO algorithm via adaptive l2, 1-minimization. Specifically, we introduce a sparsity objective function term into our model which contains weighting factors for each beam angle adaptively adjusted during the optimization process. Such an objective function favors a small number of beam angles. By optimizing a total objective function consisting of a dosimetric term and the sparsity term, we are able to identify unimportant beam angles and gradually remove them without largely sacrificing the dosimetric objective. In one typical prostate case, the convergence property of our algorithm, as well as how beam angles are selected during the optimization process, is demonstrated. Fluence map optimization (FMO) is then performed based on the optimized beam angles. The resulting plan quality is presented and is found to be better than that of equiangular beam orientations. We have further systematically validated our algorithm in the contexts of 5-9 coplanar beams for five prostate cases and one head and neck case. For each case, the final FMO objective function value is used to compare the optimized beam orientations with the equiangular ones. It is found that, in the majority of cases tested, our BOO algorithm leads to beam configurations which attain lower FMO objective function values than those of corresponding equiangular cases, indicating the effectiveness of our BOO algorithm. Superior plan qualities are also demonstrated by comparing DVH curves between BOO plans and equiangular plans.

  15. The influence of angular misalignment on fixed-portal intensity modulated radiation therapy.

    PubMed

    Low, D A; Zhu, X R; Purdy, J A; Söderström, S

    1997-07-01

    A method has been developed to estimate potential dose errors due to linear accelerator angular setting misalignments of Intensity Modulated Radiation Therapy (IMRT) treatments. A first-order approximation to the dose error at a point is modeled as the dot product of the dose gradient and the shift vector of the point due to the rotational error. The analysis method is applied to a previously published set of optimized fluences for a 50 MV IMRT pelvis irradiation. Three of the published cases exhibiting a wide range of modulation are presented; a rectangular open field, a field optimized for a static multileaf collimator defining the portal outline coupled with a single broad bremsstrahlung profile modulation, and a fully modulated field using a physical modulator. To examine the energy dependence of angle setting errors, the study is repeated using the same fluence distributions, but with a dose-spread kernel appropriate for a 6 MV photon beam. The collimator angle error is set to 2 degree, and the dose error determined with both a centrally located isocenter and an isocenter chosen to model a split-field geometry. The dose error due to a 2 degree gantry setting error is assessed at a plane 10 cm distal to the isocenter. The mathematical form of the dose error due to couch motion is similar to the other two errors, so the dose error resulting from a couch angle missetting is not presented. The magnitude of the errors is largest for the 6 MV beam, while the volume encompassed by the errors is greater for the 50 MV beam. The gantry error yields the largest dose error values, with the 6 MV modulated case presenting dose errors of greater than 40%. PMID:9243475

  16. The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

    PubMed Central

    Sung, Wonmo; Park, Jong Min; Choi, Chang Heon; Ha, Sung Whan

    2012-01-01

    Purpose To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose. Results Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V20 Gy of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%. Conclusion In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution. PMID:23120741

  17. Low-intensity laser radiation in complex treatment of inflammatory diseases of parodontium

    NASA Astrophysics Data System (ADS)

    Sokolova, Irina A.; Erina, Stanislava V.

    1995-04-01

    The problem of complex treatment of inflammatory disease of parodontium has become very acute and actual at the moment. The diseases of inflammatory nature are considered to be the most vital issues of the day. The state of the local immune system of oral cavity plays the most important role in the complicated mechanism of inflammatory process development in the tissues of parodontium. Recently physical factors have become predominant in the system of complex therapy of parodontitis. The application of low-intense laser radiation (LLR) is considered to be the most important and up-to-date method in the preventive dentistry. There were 60 patients of average damage rate suffering from chronic generalizing parodontitis at the age of 25 up to 55 under observation. The major goal of examination was to get the objective results of the following methods' application: parodontium index (Russel, 1956), hygiene index (Fyodorov, Volodkina, 1971), Bacterioscopy of dental-gingival pockets content, simple and broadened stomatoscopy (Kunin, 1970), SIgA level determination in mixed saliva (Manchini et all, 1965) and R-protein level in gingival blood (Kulberg, 1990). All the patients were split into 2 groups. The first group (30 patients) has undergone the laser therapy course while the second group of 30 patients couldn't get it (LLR). Despite the kind of therapy they have undergone, all the patients have got the local anti-inflammatory medicamental therapy. The results of clinical observations have proved the fact that laser therapy application makes it possible to shorten the course of treatment in 1.5 times. The shifts of oral cavity local resistance take place in case of chronic generalizing parodontitis. The direct immunostimulating effect could be observed as a result of LLR- therapy application. The close connection of both anti-inflammatory medicamental and LLR-therapy has proved the possibility of purposeful local immune status correction in case of parodontitis.

  18. Upper limit on the inner radiation belt MeV electron intensity

    PubMed Central

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  19. Prognostic value of Diabetes in Patients with Nasopharyngeal Carcinoma Treated with Intensity-Modulated Radiation Therapy

    PubMed Central

    Peng, Hao; Chen, Lei; Zhang, Yuan; Li, Wen-Fei; Mao, Yan-Ping; Zhang, Fan; Guo, Rui; Liu, Li-Zhi; Lin, Ai-Hua; Sun, Ying; Ma, Jun

    2016-01-01

    The prognostic value of diabetes remains unknown in nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). We retrospectively reviewed medical records of 1489 patients with non-metastatic, histologically-proven NPC treated using IMRT. 81/1489 (5.4%) patients were diabetic, 168/1489 (11.3%) were prediabetic, and 1240/1489 (83.3%) were normoglycemic. The 4-year disease-free survival (DFS), overall survival (OS), loco-regional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) rates were 77.1% vs. 82.4% (P = 0.358), 85.8% vs. 91.0% (P = 0.123), 90.9% vs. 91.7% (P = 0.884), and 85.5% vs. 89.2% (P = 0.445) for diabetic vs. normoglycemic patients, and 82.4% vs. 82.4% (P = 0.993), 88.7% vs. 91.0% (P = 0.285), 90.6% vs. 91.7% (P = 0.832) and 91.5% vs. 89.2% (P = 0.594) for preidabetic vs. normoglycemic patients. Multivariate analysis did not established diabetes as poor prognostic factors in NPC patients treated with IMRT (P = 0.332 for DFS, P = 0.944 for OS, P = 0.977 for LRRFS, P = 0.157 for DMFS), however, triglycerides and low density lipoprotein cholesterol were independent prognostic factors. In conclusion, diabetes does not appear to be a prognostic factor in NPC patients treated with IMRT, and attention should be paid to hyperglycemia-associated hyperlipaemia. PMID:26927312

  20. Effect of fluence smoothing on the quality of intensity-modulated radiation treatment plans.

    PubMed

    Niyas, Puzhakkal; Abdullah, Kallikuzhiyil Kochunny; Noufal, Manthala Padannayil; Sankaran Nair, Thekkedath

    2016-07-01

    A fluence-smoothing function applied for reducing the complexity of a treatment plan is an optional requirement in the inverse planning optimization algorithm of intensity-modulated radiation therapy (IMRT). In this study, we investigated the consequences of fluence smoothing on the quality of highly complex and inhomogeneous plans in a treatment-planning system, Eclipse™. The smoothing function was applied both in the direction of leaf travel (X) and perpendicular to leaf travel (Y). Twenty IMRT plans from patients with cancer of the nasopharynx and lung were selected and re-optimized with use of various smoothing combinations from X = 0, Y = 0 to X = 100, Y = 100. Total monitor units (MUs), dose-volume histograms, and radiobiological estimates were computed for all plans. The study yielded a significant reduction in the average total MUs from 2079 ± 265.4 to 1107 ± 137.4 (nasopharynx) and from 1556 ± 490.3 to 791 ± 176.8 (lung) while increasing smoothing from X, Y = 0 to X, Y = 100. Both the tumor control and normal tissue complication probabilities were found to vary, but not significantly so. No appreciable differences in doses to the target and most of the organs at risk (OARs) were noticed. The doses measured with the I'MRT MatriXX 2-D system indicated improvements in deliverability of the plans with higher smoothing values. Hence, it can be concluded that increased smoothing reduced the total MUs exceptionally well without any considerable changes in OAR doses. The observed progress in plan deliverability in terms of the gamma index strongly supports the recommendation of smoothing levels up to X = 70 and Y = 60, at least for the nasopharynx and lung. PMID:26951466

  1. Evaluation of Parotid Gland Function following Intensity Modulated Radiation Therapy for Head and Neck Cancer

    PubMed Central

    Lee, Seok Ho; Kim, Tae Hyun; Kim, Joo Young; Park, Sung Yong; Pyo, Hong Ryull; Shin, Kyung Hwan; Kim, Dae Yong; Kim, Joo Young

    2006-01-01

    Purpose This study was undertaken to determine the parotid gland tolerance dose levels following intensity modulated radiation therapy (IMRT) for treating patients who suffered with head and neck cancer. Materials and Methods From February 2003 through June 2004, 34 head and neck patients with 6 months of follow-up were evaluated for xerostomia after being treated by IMRT. Their median age was 59 years (range: 29~78). Xerostomia was assessed using a 4-question xerostomia questionnaire score (XQS) and a test for the salivary flow rates (unstimulated and stimulated: USFR and SSFR, respectively). The patients were also given a validated LENT SOMA scale (LSS) questionnaire. Evaluations were performed before IMRT and at 1, 3 and 6 months after IMRT. Results All 34 patients showed significant changes in the XQS, LSS and Salivary Flow rates (USFR and SSFR) after IMRT. No significant changes in the XQS or LSS were noted in 12 patients who received a total parotid mean dose of ≤3,100 cGy at 1, 3 and 6 months post-IMRT relative to the baseline values. However, for the 22 patients who received >3,100 cGy, significant increases in the XQS and LSS were observed. The USFR and SSFR from the parotid glands in 7 patients who received ≤2,750 cGy were significantly preserved at up to 6 months after IMRT. However, the USFR and SSFR in 27 patients who were treated with >2,750 cGy were significantly lower than the baseline values at all times after IMRT. Conclusion We suggest that the total parotid mean dose should be limited to ≤2,750 cGy to preserve the USFR and SSFR and so improve the subsequent quality of life. PMID:19771265

  2. An Anatomically Validated Brachial Plexus Contouring Method for Intensity Modulated Radiation Therapy Planning

    SciTech Connect

    Van de Velde, Joris; Audenaert, Emmanuel; Speleers, Bruno; Vercauteren, Tom; Mulliez, Thomas; Vandemaele, Pieter; Achten, Eric; Kerckaert, Ingrid; D'Herde, Katharina; De Neve, Wilfried; Van Hoof, Tom

    2013-11-15

    Purpose: To develop contouring guidelines for the brachial plexus (BP) using anatomically validated cadaver datasets. Magnetic resonance imaging (MRI) and computed tomography (CT) were used to obtain detailed visualizations of the BP region, with the goal of achieving maximal inclusion of the actual BP in a small contoured volume while also accommodating for anatomic variations. Methods and Materials: CT and MRI were obtained for 8 cadavers positioned for intensity modulated radiation therapy. 3-dimensional reconstructions of soft tissue (from MRI) and bone (from CT) were combined to create 8 separate enhanced CT project files. Dissection of the corresponding cadavers anatomically validated the reconstructions created. Seven enhanced CT project files were then automatically fitted, separately in different regions, to obtain a single dataset of superimposed BP regions that incorporated anatomic variations. From this dataset, improved BP contouring guidelines were developed. These guidelines were then applied to the 7 original CT project files and also to 1 additional file, left out from the superimposing procedure. The percentage of BP inclusion was compared with the published guidelines. Results: The anatomic validation procedure showed a high level of conformity for the BP regions examined between the 3-dimensional reconstructions generated and the dissected counterparts. Accurate and detailed BP contouring guidelines were developed, which provided corresponding guidance for each level in a clinical dataset. An average margin of 4.7 mm around the anatomically validated BP contour is sufficient to accommodate for anatomic variations. Using the new guidelines, 100% inclusion of the BP was achieved, compared with a mean inclusion of 37.75% when published guidelines were applied. Conclusion: Improved guidelines for BP delineation were developed using combined MRI and CT imaging with validation by anatomic dissection.

  3. Prognostic value of Diabetes in Patients with Nasopharyngeal Carcinoma Treated with Intensity-Modulated Radiation Therapy.

    PubMed

    Peng, Hao; Chen, Lei; Zhang, Yuan; Li, Wen-Fei; Mao, Yan-Ping; Zhang, Fan; Guo, Rui; Liu, Li-Zhi; Lin, Ai-Hua; Sun, Ying; Ma, Jun

    2016-01-01

    The prognostic value of diabetes remains unknown in nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). We retrospectively reviewed medical records of 1489 patients with non-metastatic, histologically-proven NPC treated using IMRT. 81/1489 (5.4%) patients were diabetic, 168/1489 (11.3%) were prediabetic, and 1240/1489 (83.3%) were normoglycemic. The 4-year disease-free survival (DFS), overall survival (OS), loco-regional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) rates were 77.1% vs. 82.4% (P = 0.358), 85.8% vs. 91.0% (P = 0.123), 90.9% vs. 91.7% (P = 0.884), and 85.5% vs. 89.2% (P = 0.445) for diabetic vs. normoglycemic patients, and 82.4% vs. 82.4% (P = 0.993), 88.7% vs. 91.0% (P = 0.285), 90.6% vs. 91.7% (P = 0.832) and 91.5% vs. 89.2% (P = 0.594) for preidabetic vs. normoglycemic patients. Multivariate analysis did not established diabetes as poor prognostic factors in NPC patients treated with IMRT (P = 0.332 for DFS, P = 0.944 for OS, P = 0.977 for LRRFS, P = 0.157 for DMFS), however, triglycerides and low density lipoprotein cholesterol were independent prognostic factors. In conclusion, diabetes does not appear to be a prognostic factor in NPC patients treated with IMRT, and attention should be paid to hyperglycemia-associated hyperlipaemia. PMID:26927312

  4. The tracking performance of distributed recoverable flight control systems subject to high intensity radiated fields

    NASA Astrophysics Data System (ADS)

    Wang, Rui

    It is known that high intensity radiated fields (HIRF) can produce upsets in digital electronics, and thereby degrade the performance of digital flight control systems. Such upsets, either from natural or man-made sources, can change data values on digital buses and memory and affect CPU instruction execution. HIRF environments are also known to trigger common-mode faults, affecting nearly-simultaneously multiple fault containment regions, and hence reducing the benefits of n-modular redundancy and other fault-tolerant computing techniques. Thus, it is important to develop models which describe the integration of the embedded digital system, where the control law is implemented, as well as the dynamics of the closed-loop system. In this dissertation, theoretical tools are presented to analyze the relationship between the design choices for a class of distributed recoverable computing platforms and the tracking performance degradation of a digital flight control system implemented on such a platform while operating in a HIRF environment. Specifically, a tractable hybrid performance model is developed for a digital flight control system implemented on a computing platform inspired largely by the NASA family of fault-tolerant, reconfigurable computer architectures known as SPIDER (scalable processor-independent design for enhanced reliability). The focus will be on the SPIDER implementation, which uses the computer communication system known as ROBUS-2 (reliable optical bus). A physical HIRF experiment was conducted at the NASA Langley Research Center in order to validate the theoretical tracking performance degradation predictions for a distributed Boeing 747 flight control system subject to a HIRF environment. An extrapolation of these results for scenarios that could not be physically tested is also presented.

  5. Gamma evaluation combined with isocenter optimal matching in intensity modulated radiation therapy quality assurance

    NASA Astrophysics Data System (ADS)

    Bak, Jino; Choi, Jin Hwa; Park, Suk Won; Park, Kwangwoo; Park, Sungho

    2015-12-01

    Two-dimensional (2D) dose comparisons are widely performed by using a gamma evaluation with patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) or dose delivery quality assurance (DQA). In this way, a pass/fail determination is made for a particular treatment plan. When gamma evaluation results are close to the failure criterion, the pass/fail decision may change applying a small shift to the center of the 2D dose distribution. In this study, we quantitatively evaluated the meaning of such a small relative shift in a 2D dose distribution comparison. In addition, we propose the use of a small shift for a pass/fail criterion in gamma analysis, where the concept of isocenter optimal matching (IOM) is applied to IMRT QA of 20 patients. Gamma evaluations were performed to compare two dose distributions, one with and the other without IOM. In-house software was developed in C++ in order to find IOM values including both translational and rotational shifts. Upon gamma evaluation failure, further investigation was initiated using IOM. In this way, three groups were categorized: group 1 for `pass' on gamma evaluation, group 21 for `fail' on the gamma evaluation and `pass' on the gamma the evaluation with IOM, and group 22 for `fail' on the both gamma evaluations and the IOM calculation. IOM results revealed that some failures could be considered as a `pass'. In group 21, 88.98% (fail) of the averaged gamma pass rate changed to 90.45% (pass) when IOM was applied. On average, a ratio of γ ≥ 1 was reduced by 11.06% in 20 patients. We propose that gamma evaluations that do not pass with a rate of 85% to 90% may be augmented with IOM to reveal a potential pass result.

  6. Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

    SciTech Connect

    Garden, Adam S.; Dong, Lei; Morrison, William H.; Stugis, Erich M.; Glisson, Bonnie S.; Schwartz, David L.; Kies, Merill S.; Ang, K. Kian; Rosenthal, David I.

    2013-03-15

    Purpose: To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT). Methods and Materials: The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed. Results: The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Joint Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease. Conclusions: Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage.

  7. The Radiation Reaction Effect on Electrons at Super-High Laser Intensities with Application to Ion Acceleration

    SciTech Connect

    Naumova, N. M.; Sokolov, I. V.; Tikhonchuk, V. T.; Schlegel, T.; Nees, J. A.; Yanovsky, V. P.; Labaune, C.; Mourou, G. A.

    2009-07-25

    At super-high laser intensities the radiation back reaction on electrons becomes so significant that its influence on laser-plasma interaction cannot be neglected while simulating these processes with particle-in-cell (PIC) codes. We discuss a way of taking the radiation effect on electrons into account and extracting spatial and frequency distributions of the generated high-frequency radiation. We also examine ponderomotive acceleration of ions in the double layer created by strong laser pulses and we compare an analytical description with PIC simulations as well. We discuss: (1) non-stationary features found in simulations, (2) electron cooling effect due to radiation losses, and (3) the limits of the analytical model.

  8. Effect of background gas pressure and laser pulse intensity on laser induced plasma radiation of copper samples

    NASA Astrophysics Data System (ADS)

    Mehrabian, S.; Aghaei, M.; Tavassoli, S. H.

    2010-04-01

    Study of laser induced plasma emission of Cu in one dimension is numerically carried out. Effects of different background gas pressure (He), 100, 500, and 760 torr, and laser pulse intensities, 0.5, 0.7, and 1 GW/cm2, on the plasma emission as well as ablation processes are investigated. Under a specified condition, heat conduction equation in the target accompanied with gas dynamic equations in the plume is solved simultaneously. The mentioned equations are coupled to each other through the Knudsen layer conditions and the energy and mass balances at the interface between the target and the vapor. The Bremsstrahlung radiation of plasma and the spectral emission of copper atoms are studied under various background gas pressure and laser pulse intensities. Furthermore, number density of He, Cu, and the electron, pressure, and temperature of the plume under various conditions are obtained. In the early time after laser pulse, plasma radiation is mainly due to the Bremsstrahlung radiation while after some 10 ns, the plasma radiation is dominated by spectral emission of Cu atoms. A similar uncoupling is observed spatially. The Bremsstrahlung emission is dominant near the sample surface while at farther points the spectral emission is the dominant one. By increase in the background pressure and also the pulse intensity, the dominancy of the spectral emission would occur later in time and farther in position.

  9. Real-time, automated characterization of surfaces for alpha and beta radiation

    SciTech Connect

    Egidi, P.V.; Flynn, C.R.; Blair, M.S.; Selfridge, R.J.

    1997-12-31

    A new data collection system, called ABACUS{trademark}, has been developed that automates and expedites the collection, conversion, and reporting of radiological survey data of surfaces. Field testing of the system by Oak Ridge National Laboratory/Environmental Technology Section is currently underway. Preliminary results are presented. The system detects, discriminates, and separately displays the results for alpha and beta contamination scans on floors and walls with a single pass. Fixed-position static counting is also possible for quantitative measuring. The system is currently configured with five 100 cm{sup 2} dual-phosphor plastic scintillation detectors mounted in a lightweight aluminum fixture that holds the detectors in a fixed array. ABACUS{trademark} can be configured with other detectors if desired. Ratemeter/scalars traditionally coupled to individual detectors have been replaced by a single unit that houses the power supply and discriminator circuit boards to support up to five detectors. The system is designed to be used by a single operator. Each detector`s position and data are transmitted once per second and recorded on a nearby laptop computer. The data are converted to appropriate units, color-coded, and mapped to display graphically the findings for each detector in real-time. Reports can be generated immediately following the survey. Survey data can be exported in a variety of formats. Benefits of ABACUS{trademark} are: (1) immediate feedback to decision makers using the observational approach to characterization or remediation, (2) thorough documentation of survey results, (3) increased statistical confidence in scans by recording counts every second, (4) reduced paperwork and elimination of transcription errors, and (5) time and cost savings for collection, conversion, mapping, evaluating, and reporting data over traditional methods.

  10. Role of tumor necrosis factor-alpha and TRAIL in high-dose radiation-induced bystander signaling in lung adenocarcinoma.

    PubMed

    Shareef, Mohammed M; Cui, Nuan; Burikhanov, Ravshan; Gupta, Seema; Satishkumar, Sabapathi; Shajahan, Shahin; Mohiuddin, Mohammed; Rangnekar, Vivek M; Ahmed, Mansoor M

    2007-12-15

    In the present study, ionizing radiation (IR)-induced bystander effects were investigated in two lung cancer cell lines. A549 cells were found to be more resistant to radiation-conditioned medium (RCM) obtained from A549 cells when compared with the H460 exposed to RCM procured from H460 cells. Significant release of tumor necrosis factor-alpha (TNF-alpha) was observed in A549 cells after IR/RCM exposure, and the survival was reversed with neutralizing antibody against TNF-alpha. In H460 cells, significant release of TNF-related apoptosis-inducing ligand (TRAIL), but not TNF-alpha, was observed in response to IR, RCM exposure, or RCM + 2Gy, and neutralizing antibody against TRAIL diminished clonogenic inhibition. Mechanistically, TNF-alpha present in RCM of A549 was found to mediate nuclear factor-kappaB (NF-kappaB) translocation to nucleus, whereas the soluble TRAIL present in RCM of H460 cells mobilized the nuclear translocation of PAR-4 (a proapoptotic protein). Analysis of IR-inducible early growth response-1 (EGR-1) function showed that EGR-1 was functional in A549 cells but not in H460 cells. A significant decrease in RCM-mediated apoptosis was observed in both A549 cells stably expressing small interfering RNA EGR-1 and EGR-1(-/-) mouse embryonic fibroblast cells. Thus, the high-dose IR-induced bystander responses in A549 may be dependent on the EGR-1 function and its target gene TNF-alpha. These findings show that the reduced bystander response in A549 cells is due to activation of NF-kappaB signaling by TNF-alpha, whereas enhanced response to IR-induced bystander signaling in H460 cells was due to release of TRAIL associated with nuclear translocation of PAR-4. PMID:18089811

  11. Low-dose radiation pretreatment improves survival of human ceiling culture-derived proliferative adipocytes (ccdPAs) under hypoxia via HIF-1 alpha and MMP-2 induction

    SciTech Connect

    Adachi, Naoki; Kubota, Yoshitaka; Kosaka, Kentarou; Akita, Shinsuke; Sasahara, Yoshitarou; Kira, Tomoe; Kuroda, Masayuki; Mitsukawa, Nobuyuki; Bujo, Hideaki; Satoh, Kaneshige

    2015-08-07

    Poor survival is a major problem of adipocyte transplantation. We previously reported that VEGF and MMPs secreted from transplanted adipocytes are essential for angiogenesis and adipogenesis. Pretreatment with low-dose (5 Gy) radiation (LDR) increased VEGF, MMP-2, and HIF-1 alpha mRNA expression in human ceiling culture-derived proliferative adipocytes (hccdPAs). Gene expression after LDR differed between adipose-derived stem cells (hASCs) and hccdPAs. Pretreatment with LDR improved the survival of hccdPAs under hypoxia, which is inevitable in the early stages after transplantation. Upregulation of VEGF and MMP-2 after LDR in hccdPAs is mediated by HIF-1 alpha expression. Our results suggest that pretreatment with LDR may improve adipocyte graft survival in a clinical setting through upregulation of VEGF and MMP-2 via HIF-1 alpha. - Highlights: • Ceiling culture-derived proliferative adipocytes (ccdPAs) react to radiation. • Low-dose radiation (LDR) pretreatment improves survival of ccdPAs under hypoxia. • Gene expression after LDR differs between ccdPAs and adipose-derived stem cells. • LDR-induced increase in MMP-2 and VEGF is dependent on HIF-1 alpha induction. • LDR pretreatment may improve the adipocyte graft survival rate in clinical settings.

  12. The damage repair role of He-Ne laser on plants exposed to different intensities of ultraviolet-B radiation.

    PubMed

    Qi, Zhi; Yue, Ming; Han, Rong; Wang, Xun-Ling

    2002-06-01

    Light-grown broad bean (Vicia faba L.) seedlings were subjected to different intensities of UV-B radiation (0, 0.05, 0.15, 0.45, 0.90, 1.45 and 1.98 W m(-2)) for 7 h under photosynthetically active radiation (70 micromol m(-2) s(-1)) and then exposed to He-Ne laser (632.8 nm, 5.43 mW mm(-2)) radiation for 5 min or red light radiation for 4 h without ambient light radiation. When He-Ne laser radiated leaves were treated using lower intensity UV-B, the activities of superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) improved significantly. Moreover, the UV-B-injured plants treated with laser light recovered faster from UV-B treatment because the concentration of malondialdehyde and the rate of electrolyte leakage from leaf disks reached control levels (no UV-B or laser treatment) early compared with those exposed only to ambient light or in dark conditions. Laser treatment, however, had no repair effect on seedling damage induced by higher UV-B radiation (1.45 and 1.98 W m(-2)), even with higher laser flux rates and longer laser treatment. In addition, the red light treatment had no repair effect on UV-B-induced damage. Meanwhile, the long-term physiological effect of He-Ne laser treatment on UV-B damaged plants was presented and evaluated. The results showed that the laser had a long-term positive physiological effect on the growth of UV-B-damaged plants. With the exception of the severe damage caused by higher UV-B radiation, a laser with the proper flux rate and treatment time can repair UV-B-induced damage and shorten the recovery time. PMID:12081332

  13. Intensity of electromagnetic energy radiation by a quiescent ferromagnetic spherical particle placed in a permanent magnetic field

    NASA Astrophysics Data System (ADS)

    Gladkov, S. O.

    2015-07-01

    The classical problem of calculating the energy of electromagnetic energy radiated from a ferromagnetic particle is solved for the case when the vector of spontaneous magnetization M of the ferromagnet differs from that of external permanent magnetic field H 0. The dependence of electromagnetic radiation intensity on the product κ R (where κ = ω0/ c is the wavevector, R is the radius of the particle, and ω0 = γ e H 0 is the precession frequency of transverse component M ⊥ of the magnetization ( M = M ⊥, M z )) is derived.

  14. Generation of widely tunable intense far-infrared radiation pulses by stimulated Raman transitions in methylfluoride gas

    SciTech Connect

    Lang, P.T.; Sessler, F.; Werling, U.; Renk, K.F. )

    1989-12-18

    We report on the generation of widely tunable intense far-infrared radiation pulses by stimulated Raman transitions in methylfluoride gas. Using a tunable high-pressure CO{sub 2} laser we achieved, by {ital P}-branch tuning of stimulated Raman transitions in {sup 12}CH{sub 3}F and {sup 13}CH{sub 3}F gases, tunable generation of radiation in a series of intervals in the spectral range from 37 to 72 cm{sup {minus}1} covering 20% of this range. Possibilities of further extension of the tuning regions are also discussed.

  15. The Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period Examining Aerosol Properties and Radiative Influences: Preface to Special Section

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard; Feingold, Graham; Ghan, Steven; Ogren, John; Schmid, Beat; Schwartz, Stephen E.; Sheridan, Pat

    2006-01-01

    Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in North Central Oklahoma in May, 2003, examining these relations using in situ airborne measurements and surface-, airborne-, and space-based remote sensing.

  16. Uranium enrichment measurements using the intensity ratios of self-fluorescence X-rays to 92* keV gamma ray in UXK alpha spectral region.

    PubMed

    Yücel, H; Dikmen, H

    2009-04-30

    In this paper, the known multigroup gamma-ray analysis method for uranium (MGAU) as one of the non-destructive gamma-ray spectrometry methods has been applied to certified reference nuclear materials (depleted, natural and enriched uranium) containing (235)U isotope in the range of 0.32-4.51% atom (235)U. Its analysis gives incorrect results for the low component (235)U in depleted and natural uranium samples where the build-up of the decay products begins to interfere with the analysis. The results reveal that the build-up of decay products seems to be significant and thus the algorithms for the presence of decay products should be improved to resulting in the correct enrichment value. For instance, for the case of (235)U analysis in depleted uranium or natural ore samples, self-induced X-rays such as 94.6 keV and 98.4 keV lying in UXK(alpha) spectral region used by MGAU can be excluded from the calculation. Because the significant increases have been observed in the intensities of uranium self-induced X-rays due to gamma-ray emissions with above 100 keV energy arising from decay products of (238)U and (235)U and these parents. Instead, the use of calibration curve to be made between the intensity ratios of self-fluorescence X-rays to 92(*)keV gamma-ray and the certified (235)U abundances is suggested for the determination of (235)U when higher amounts of decay products are detected in the gamma-ray spectrum acquired for the MGAU analysis. PMID:19203602

  17. The Influence of the Photoionizing Radiation Spectrum on Metal-Line Ratios in Ly(alpha) Forest Clouds

    NASA Technical Reports Server (NTRS)

    Giroux, Mark L.; Shull, J. Michael

    1997-01-01

    Recent measurements of Si IV/C IV ratios in the high-redshift Ly(alpha) forest (Songaila & Cowie, AJ, 112, 335 (1996a); Savaglio et at., A&A (in press) (1997)) have opened a new window on chemical enrichment and the first generations of stars. However, the derivation of accurate Si/C abundances requires reliable ionization corrections, which are strongly dependent on the spectral shape of the metagalactic ionizing background and on the 'local effects' of hot stars in nearby galaxies. Recent models have assumed power-law quasar ionizing backgrounds plus a decrement at 4 Ryd to account for He II attenuation in intervening clouds. However, we show that realistic ionizing backgrounds based on cosmological radiative transfer models produce more complex ionizing spectra between 1-5 Ryd that are critical to interpreting ions of Si and C. We also make a preliminary investigation of the effects of He II ionization front nonoverlap. Because the attenuation and reemission by intervening clouds enhance Si IV relative to C the observed high Si IV/C IV ratios do not require an unrealistic Si overproduction (Si/C greater than or equal to 3 (Si/C)(solar mass)). If the ionizing spectrum is dominated by 'local effects' from massive stars, even larger Si IV/C IV ratios are possible. However, unless stellar radiation dominates quasars by more than a factor of 10, we confirm the evidence for some Si overproduction by massive stars; values Si/C approx. 2(Si/C)(solar mass) fit the measurements better than solar abundances. Ultimately, an adequate interpretation of the ratios of C IV, Si IV, and C II may require hot, collisionally ionized gas in a multiphase medium.

  18. Multibeam tomotherapy: a new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy.

    PubMed

    Achterberg, Nils; Müller, Reinhold G

    2007-10-01

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of +/- 36 degrees. Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of "step and shoot" MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as "multibeam tomotherapy." Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The "Multifocal MLC-positioning" algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better

  19. Multibeam tomotherapy: A new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy

    SciTech Connect

    Achterberg, Nils; Mueller, Reinhold G.

    2007-10-15

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of {+-}36 deg. . Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of 'step and shoot' MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as 'multibeam tomotherapy.' Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The 'Multifocal MLC-positioning' algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better

  20. The influence of high intensity terahertz radiation on mammalian cell adhesion, proliferation and differentiation

    NASA Astrophysics Data System (ADS)

    Williams, Rachel; Schofield, Amy; Holder, Gareth; Downes, Joan; Edgar, David; Harrison, Paul; Siggel-King, Michele; Surman, Mark; Dunning, David; Hill, Stephen; Holder, David; Jackson, Frank; Jones, James; McKenzie, Julian; Saveliev, Yuri; Thomsen, Neil; Williams, Peter; Weightman, Peter

    2013-01-01

    Understanding the influence of exposure of biological systems to THz radiation is becoming increasingly important. There is some evidence to suggest that THz radiation can influence important activities within mammalian cells. This study evaluated the influence of the high peak power, low average power THz radiation produced by the ALICE (Daresbury Laboratory, UK) synchrotron source on human epithelial and embryonic stem cells. The cells were maintained under standard tissue culture conditions, during which the THz radiation was delivered directly into the incubator for various exposure times. The influence of the THz radiation on cell morphology, attachment, proliferation and differentiation was evaluated. The study demonstrated that there was no difference in any of these parameters between irradiated and control cell cultures. It is suggested that under these conditions the cells are capable of compensating for any effects caused by exposure to THz radiation with the peak powers levels employed in these studies.

  1. Dosimetric comparison of volumetric modulated arc therapy and intensity-modulated radiation therapy for pancreatic malignancies

    SciTech Connect

    Ali, Arif N.; Dhabaan, Anees H.; Jarrio, Christie S.; Siddiqi, Arsalan K.; Landry, Jerome C.

    2012-10-01

    Volumetric-modulated arc therapy (VMAT) has been previously evaluated for several tumor sites and has been shown to provide significant dosimetric and delivery benefits when compared with intensity-modulated radiation therapy (IMRT). To date, there have been no published full reports on the benefits of VMAT use in pancreatic patients compared with IMRT. Ten patients with pancreatic malignancies treated with either IMRT or VMAT were retrospectively identified. Both a double-arc VMAT and a 7-field IMRT plan were generated for each of the 10 patients using the same defined tumor volumes, organs at risk (OAR) volumes, dose, fractionation, and optimization constraints. The planning tumor volume (PTV) maximum dose (55.8 Gy vs. 54.4 Gy), PTV mean dose (53.9 Gy vs. 52.1 Gy), and conformality index (1.11 vs. 0.99) were statistically similar between the IMRT and VMAT plans, respectively. The VMAT plans had a statistically significant reduction in monitor units compared with the IMRT plans (1109 vs. 498, p < 0.001). In addition, the doses to the liver, small bowel, and spinal cord were comparable between the IMRT and VMAT plans. However, the VMAT plans demonstrated a statistically significant reduction in the mean left kidney V{sub 25} (9.4 Gy vs. 2.3 Gy, p = 0.018), mean right kidney V{sub 15} (53.4 Gy vs. 45.9 Gy, p = 0.035), V{sub 20} (32.2 Gy vs. 25.5 Gy, p = 0.016), and V{sub 25} (21.7 Gy vs. 14.9 Gy, p = 0.001). VMAT was investigated in patients with pancreatic malignancies and compared with the current standard of IMRT. VMAT was found to have similar or improved dosimetric parameters for all endpoints considered. Specifically, VMAT provided reduced monitor units and improved bilateral kidney normal tissue dose. The clinical relevance of these benefits in the context of pancreatic cancer patients, however, is currently unclear and requires further investigation.

  2. Potentially Missing Physics of the Early Universe: Nonlinear Vacuum Polarization in Intense Blackbody Radiation

    SciTech Connect

    Wu, S Q; Hartemann, F V

    2010-04-13

    The standard Big Bang universe model is mainly based on linear interactions, except during exotic periods such as inflation. The purpose of the present proposal is to explore the effects, if any, of vacuum polarization in the very high energy density environment of the early universe. These conditions can be found today in astrophysical settings and may also be emulated in the laboratory using high intensity advanced lasers. Shortly after the Big Bang, there once existed a time when the energy density of the universe corresponded to a temperature in the range 10{sup 8} - 10{sup 9} K, sufficient to cause vacuum polarization effects. During this period, the nonlinear vacuum polarization may have had significant modifications on the propagation of radiation. Thus the thermal spectrum of the early universe may have been starkly non-Planckian. Measurements of the cosmic microwave background today show a spectrum relatively close to an ideal blackbody. Could the early universe have shown spectral deviations due to nonlinear vacuum effects? If so, is it possible to detect traces of those relic photons in the universe today? Found in galactic environments, compact objects such as blazars and magnetars can possess astronomically large energy densities that far exceed anything that can be created in the laboratory. Their field strengths are known to reach energy levels comparable to or surpassing the energy corresponding to the Schwinger critical field E {approx} 10{sup 18} V/m. Nonlinear vacuum effects become prominent under these conditions and have garnered much interest from the astronomical and theoretical physics communities. The effects of a nonlinear vacuum may be of crucial importance for our understanding of these objects. At energies of the order of the electron rest mass, the most important interactions are described by quantum electrodynamics (QED). It is predicted that nonlinear photon-photon interactions will occur at energies approaching the Schwinger

  3. Intrafractional 3D localization using kilovoltage digital tomosynthesis for sliding-window intensity modulated radiation therapy.

    PubMed

    Zhang, Pengpeng; Hunt, Margie; Pham, Hai; Tang, Grace; Mageras, Gig

    2015-09-01

    To implement novel imaging sequences integrated into intensity modulated radiation therapy (IMRT) and determine 3D positions for intrafractional patient motion monitoring and management.In one method, we converted a static gantry IMRT beam into a series of arcs in which dose index and multileaf collimator positions for all control points were unchanged, but gantry angles were modified to oscillate ± 3° around the original angle. Kilovoltage (kV) projections were acquired continuously throughout delivery and reconstructed to provide a series of 6° arc digital tomosynthesis (DTS) images which served to evaluate the in-plane positions of embedded-fiducials/vertebral-body. To obtain out-of-plane positions via triangulation, a 20° gantry rotation with beam hold-off was inserted during delivery to produce a pair of 6° DTS images separated by 14°. In a second method, the gantry remained stationary, but both kV source and detector moved over a 15° longitudinal arc using pitch and translational adjustment of the robotic arms. Evaluation of localization accuracy in an anthropomorphic Rando phantom during simulated intrafractional motion used programmed couch translations from customized scripts. Purpose-built software was used to reconstruct DTS images, register them to reference template images and calculate 3D fiducial positions.No significant dose difference (<0.5%) was found between the original and converted IMRT beams. For a typical hypofractionated spine treatment, 200 single DTS (6° arc) and 10 paired DTS (20° arc) images were acquired for each IMRT beam, providing in-plane and out-of-plane monitoring every 1.6 and 34.5 s, respectively. Mean ± standard deviation error in predicted position was -0.3 ± 0.2 mm, -0.1 ± 0.1 mm in-plane, and 0.2 ± 0.4 mm out-of-plane with rotational gantry, 0.8 ± 0.1 mm, -0.7 ± 0.3 mm in-plane and 1.1 ± 0.1 mm out-of-plane with translational source/detector.Acquiring 3D fiducial positions from kV-DTS during fixed gantry

  4. Larynx-sparing techniques using intensity-modulated radiation therapy for oropharyngeal cancer

    SciTech Connect

    Bar Ad, Voichita; Lin, Haibo; Hwang, Wei-Ting; Deville, Curtiland; Dutta, Pinaki R.; Tochner, Zelig; Both, Stefan

    2012-01-01

    The purpose of the current study was to explore whether the laryngeal dose can be reduced by using 2 intensity-modulated radiation therapy (IMRT) techniques: whole-neck field IMRT technique (WF-IMRT) vs. junctioned IMRT (J-IMRT). The effect on planning target volumes (PTVs) coverage and laryngeal sparing was evaluated. WF-IMRT technique consisted of a single IMRT plan, including the primary tumor and the superior and inferior neck to the level of the clavicular heads. The larynx was defined as an organ at risk extending superiorly to cover the arytenoid cartilages and inferiorly to include the cricoid cartilage. The J-IMRT technique consisted of an IMRT plan for the primary tumor and the superior neck, matched to conventional antero-posterior opposing lower neck fields at the level of the thyroid notch. A central block was used for the anterior lower neck field at the level of the larynx to restrict the dose to the larynx. Ten oropharyngeal cancer cases were analyzed. Both the primary site and bilateral regional lymphatics were included in the radiotherapy targets. The averaged V95 for the PTV57.6 was 99.2% for the WF-IMRT technique compared with 97.4% (p = 0.02) for J-IMRT. The averaged V95 for the PTV64 was 99.9% for the WF-IMRT technique compared with 98.9% (p = 0.02) for J-IMRT and the averaged V95 for the PT70 was 100.0% for WF-IMRT technique compared with 99.5% (p = 0.04) for J-IMRT. The averaged mean laryngeal dose was 18 Gy with both techniques. The averaged mean doses within the matchline volumes were 69.3 Gy for WF-MRT and 66.2 Gy for J-IMRT (p = 0.03). The WF-IMRT technique appears to offer an optimal coverage of the target volumes and a mean dose to the larynx similar with J-IMRT and should be further evaluated in clinical trials.

  5. Failure Patterns After Hemithoracic Pleural Intensity Modulated Radiation Therapy for Malignant Pleural Mesothelioma

    SciTech Connect

    Rimner, Andreas; Spratt, Daniel E.; Zauderer, Marjorie G.; Rosenzweig, Kenneth E.; Wu, Abraham J.; Foster, Amanda; Yorke, Ellen D.; Adusumilli, Prasad; Rusch, Valerie W.; Krug, Lee M.

    2014-10-01

    Purpose: We previously reported our technique for delivering intensity modulated radiation therapy (IMRT) to the entire pleura while attempting to spare the lung in patients with malignant pleural mesothelioma (MPM). Herein, we report a detailed pattern-of-failure analysis in patients with MPM who were unresectable or underwent pleurectomy/decortication (P/D), uniformly treated with hemithoracic pleural IMRT. Methods and Materials: Sixty-seven patients with MPM were treated with definitive or adjuvant hemithoracic pleural IMRT between November 2004 and May 2013. Pretreatment imaging, treatment plans, and posttreatment imaging were retrospectively reviewed to determine failure location(s). Failures were categorized as in-field (within the 90% isodose line), marginal (<90% and ≥50% isodose lines), out-of-field (outside the 50% isodose line), or distant. Results: The median follow-up was 24 months from diagnosis and the median time to in-field local failure from the end of RT was 10 months. Forty-three in-field local failures (64%) were found with a 1- and 2-year actuarial failure rate of 56% and 74%, respectively. For patients who underwent P/D versus those who received a partial pleurectomy or were deemed unresectable, the median time to in-field local failure was 14 months versus 6 months, respectively, with 1- and 2-year actuarial in-field local failure rates of 43% and 60% versus 66% and 83%, respectively (P=.03). There were 13 marginal failures (19%). Five of the marginal failures (38%) were located within the costomediastinal recess. Marginal failures decreased with increasing institutional experience (P=.04). Twenty-five patients (37%) had out-of-field failures. Distant failures occurred in 32 patients (48%). Conclusions: After hemithoracic pleural IMRT, local failure remains the dominant form of failure pattern. Patients treated with adjuvant hemithoracic pleural IMRT after P/D experience a significantly longer time to local and distant failure than

  6. Intensity-Modulated Radiation Therapy in Oropharyngeal Carcinoma: Effect of Tumor Volume on Clinical Outcomes

    SciTech Connect

    Lok, Benjamin H.; Setton, Jeremy; Caria, Nicola; Romanyshyn, Jonathan; Wolden, Suzanne L.; Zelefsky, Michael J.; Park, Jeffery; Rowan, Nicholas; Sherman, Eric J.; Fury, Matthew G.; Ho, Alan; Pfister, David G.; Wong, Richard J.; Shah, Jatin P.; Kraus, Dennis H.; Zhang, Zhigang; Schupak, Karen D.; Gelblum, Daphna Y.; Rao, Shyam D.; Lee, Nancy Y.

    2012-04-01

    Purpose: To analyze the effect of primary gross tumor volume (pGTV) and nodal gross tumor volume (nGTV) on treatment outcomes in patients treated with definitive intensity-modulated radiation therapy (IMRT) for oropharyngeal cancer (OPC). Methods and Materials: Between September 1998 and April 2009, a total of 442 patients with squamous cell carcinoma of the oropharynx were treated with IMRT with curative intent at our center. Thirty patients treated postoperatively and 2 additional patients who started treatment more than 6 months after diagnosis were excluded. A total of 340 patients with restorable treatment plans were included in this present study. The majority of the patients underwent concurrent platinum-based chemotherapy. The pGTV and nGTV were calculated using the original clinical treatment plans. Cox proportional hazards models and log-rank tests were used to evaluate the correlation between tumor volumes and overall survival (OS), and competing risks analysis tools were used to evaluate the correlation between local failure (LF), regional failure (RF), distant metastatic failure (DMF) vs. tumor volumes with death as a competing risk. Results: Median follow-up among surviving patients was 34 months (range, 5-67). The 2-year cumulative incidence of LF, RF and DF in this cohort of patients was 6.1%, 5.2%, and 12.2%, respectively. The 2-year OS rate was 88.6%. Univariate analysis determined pGTV and T-stage correlated with LF (p < 0.0001 and p = 0.004, respectively), whereas nGTV was not associated with RF. On multivariate analysis, pGTV and N-stage were independent risk factors for overall survival (p = 0.0003 and p = 0.0073, respectively) and distant control (p = 0.0008 and p = 0.002, respectively). Conclusions: In this cohort of patients with OPC treated with IMRT, pGTV was found to be associated with overall survival, local failure, and distant metastatic failure.

  7. Origin of Tumor Recurrence After Intensity Modulated Radiation Therapy for Oropharyngeal Squamous Cell Carcinoma

    SciTech Connect

    Raktoe, Sawan A.S.; Dehnad, Homan; Raaijmakers, Cornelis P.J.; Braunius, Weibel; Terhaard, Chris H.J.

    2013-01-01

    Purpose: To model locoregional recurrences of oropharyngeal squamous cell carcinomas (OSCC) treated with primary intensity modulated radiation therapy (IMRT) in order to find the origins from which recurrences grow and relate their location to original target volume borders. Methods and Materials: This was a retrospective analysis of OSCC treated with primary IMRT between January 2002 and December 2009. Locoregional recurrence volumes were delineated on diagnostic scans and coregistered rigidly with treatment planning computed tomography scans. Each recurrence was analyzed with two methods. First, overlapping volumes of a recurrence and original target were measured ('volumetric approach') and assessed as 'in-field', 'marginal', or 'out-field'. Then, the center of mass (COM) of a recurrence volume was assumed as the origin from where a recurrence expanded, the COM location was compared with original target volume borders and assessed as 'in-field', 'marginal', or 'out-field'. Results: One hundred thirty-one OSCC were assessed. For all patients alive at the end of follow-up, the mean follow-up time was 40 months (range, 12-83 months); 2 patients were lost to follow-up. The locoregional recurrence rate was 27%. Of all recurrences, 51% were local, 23% were regional, and 26% had both local and regional recurrences. Of all recurrences, 74% had imaging available for assessment. Regarding volumetric analysis of local recurrences, 15% were in-field gross tumor volume (GTV), and 65% were in-field clinical tumor volume (CTV). Using the COM approach, we found that 70% of local recurrences were in-field GTV and 90% were in-field CTV. Of the regional recurrences, 25% were volumetrically in-field GTV, and using the COM approach, we found 54% were in-field GTV. The COM of local out-field CTV recurrences were maximally 16 mm outside CTV borders, whereas for regional recurrences, this was 17 mm. Conclusions: The COM model is practical and specific for recurrence assessment. Most

  8. Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system

    NASA Astrophysics Data System (ADS)

    Petric, Martin Peter

    This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing field-by-field verification of IMRT plans. This work was motivated by an initial study comparing two IMRT treatment planning systems. The clinical functionality of BrainLAB's BrainSCAN and Varian's Helios IMRT treatment planning systems were compared in terms of implementation and commissioning, dose optimization, and plan assessment. Implementation and commissioning revealed differences in the beam data required to characterize the beam prior to use with the BrainSCAN system requiring higher resolution data compared to Helios. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. The dose optimization and plan assessment comparisons revealed that while both systems use considerably different optimization algorithms and user-control interfaces, they are both capable of producing substantially equivalent dose plans. The extensive use of dosimetric verification techniques in the IMRT treatment planning comparison study motivated the development and implementation of a novel IMRT dosimetric verification system. The system consists of a water-filled phantom with a tissue equivalent plastic scintillator sheet built into the top surface. Scintillation light is reflected by a plastic mirror within the phantom towards a viewing window where it is captured using a CCD camera. Optical photon spread is removed using a micro-louvre optical collimator and by deconvolving a glare kernel from the raw images. Characterization of this

  9. Optimal beam design on intensity-modulated radiation therapy with simultaneous integrated boost in nasopharyngeal cancer

    SciTech Connect

    Cheng, Mei-Chun; Hu, Yu-Wen; Liu, Ching-Sheng; Lee, Jeun-Shenn; Huang, Pin-I; Yen, Sang-Hue; Lee, Yuh-Lin; Hsieh, Chun-Mei; Shiau, Cheng-Ying

    2014-10-01

    This study aims to determine the optimal beam design among various combinations of field numbers and beam trajectories for intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) technique for the treatment of nasopharyngeal cancer (NPC). We used 10 fields with gantry angles of 155°, 130°, 75°, 25°, 0° L, 0° R, 335°, 285°, 230°, and 205° denoted as F10. To decrease doses in the spinal cord, the F10 technique was designed by featuring 2 pairs of split-opposed beam fields at 155° to 335° and 205° to 25°, as well as one pair of manually split beam fields at 0°. The F10 technique was compared with 4 other common field arrangements: F7E, 7 fields with 50° equally spaced gantry angles; F7, the basis of F10 with 155°, 130°, 75°, 0°, 285°, 230°, and 205°; F9E, 9 fields with 40° equally spaced gantry angles; and FP, 7 posterior fields with 180°, 150°, 120°, 90°, 270°, 240°, and 210°. For each individual case of 10 patients, the customized constraints derived after optimization with the standard F10 technique were applied to 4 other field arrangements. The 4 new optimized plans of each individual case were normalized to achieve the same coverage of planning target volume (PTV){sub 63} {sub Gy} as that of the standard F10 technique. The F10 field arrangement exhibited the best coverage in PTV{sub 70} {sub Gy} and the least mean dose in the trachea-esophagus region. Furthermore, the F10 field arrangement demonstrated the highest level of conformity in the low-dose region and the least monitor unit. The F10 field arrangement performed more outstandingly than the other field arrangements in PTV{sub 70} {sub Gy} coverage and spared the central organ. This arrangement also exhibited the highest conformity and delivery efficiency. The F10 technique is recommended as the standard beam geometry for the SIB-IMRT of NPC.

  10. Backreflection-induced oscillations of the intensity of radiation emitted by a single-frequency cw dye ring laser

    SciTech Connect

    Kuehlke, D.; Schroeter, S.

    1982-05-01

    When a certain critical intensity is exceeded, backreflected signals produced by counterpropagating waves with a definite mutual phase shift give rise to oscillations of the intensity of the radiation emitted by a ring laser with a homogeneously broadened line. Measurements are reported of the critical reflection coefficient and of the dependence of the oscillation frequency on the intensity of backreflected signals in the case of a single-mode cw dye ring laser. The experimental results are in good agreement with theoretical predictions. It follows also from these results that a cw dye ring laser can be used as a tunable source of modulated light with a small band width, a depth of modulation of about 100%, and a modulation frequency variable from a few hundreds of kilohertz to approximately 20 MHz.

  11. Measurements of forward scattered laser radiation from intense sub-ps laser interactions with underdense plasmas

    SciTech Connect

    Walton, B. R.; Mangles, S. P. D.; Najmudin, Z.; Tatarakis, M.; Wei, M. S.; Gopal, A.; Marle, C.; Dangor, A. E.; Krushelnick, K.; Fritzler, S.; Malka, V.; Clarke, R. J.; Hernandez-Gomez, C.

    2006-11-15

    Two experiments studying the interaction of high intensity laser pulses (1x10{sup 19}-5x10{sup 20} W/cm{sup 2}) with underdense plasma are compared. The experiments used lasers that differed in power and focused intensity but had similar pulse duration ({approx}1 ps). Spectroscopic measurements of the forward scattered light (sidebands) near the fundamental laser frequency produced by the self-modulation instability were performed and the energies of electrons accelerated in the interaction are measured and compared. It is found that at high intensities the sideband intensities and the electron energies were not directly correlated, implying that relativistic plasma wave generation is not the most important mechanism for electron acceleration in the ultrahigh intensity regime. Simulation results for the forward scattered spectrum agree well with experimental results.

  12. Describing electron motion in ultra-high intensity laser plasma interactions: the inclusion of a stochastic radiation reaction force

    NASA Astrophysics Data System (ADS)

    Ridgers, Christopher

    2014-10-01

    At intensities soon to be reached by next-generation laser facilities (exceeding 5 × 1022W/cm-2) electrons are accelerated so violently in the laser fields that they radiate energy (as gamma-ray photons) comparable to that they gain from the laser pulse. In this case the radiation reaction force becomes important in determining their motion. However, at these intensities the electric field in the electron's rest frame approaches the Schwinger field; the critical field of quantum electrodynamics where quantum effects on the radiation reaction force become crucial. In particular, the force transitions from a deterministic classical force to a stochastic force. I will compare electron motion when the radiation reaction is treated classically and stochastically, showing that the two treatments give the same result in the classical limit (correspondence) and that, surprisingly, a modified deterministic force (called the ``semi-classical'' model) can also be used when quantum effects are strong. I will also demonstrate that the semi-classical treatment fails to predict the rate of pair production by the emitted gamma-ray photons. To describe pair production one needs to adopt a new model for electron motion where the motion is described in terms of the evolution of a probability function in phase space as opposed to motion along a classical (deterministic) worldline.

  13. Dosimetric advantages of intensity-modulated proton therapy for oropharyngeal cancer compared with intensity-modulated radiation: A case-matched control analysis.

    PubMed

    Holliday, Emma B; Kocak-Uzel, Esengul; Feng, Lei; Thaker, Nikhil G; Blanchard, Pierre; Rosenthal, David I; Gunn, G Brandon; Garden, Adam S; Frank, Steven J

    2016-01-01

    A potential advantage of intensity-modulated proton therapy (IMPT) over intensity-modulated (photon) radiation therapy (IMRT) in the treatment of oropharyngeal carcinoma (OPC) is lower radiation dose to several critical structures involved in the development of nausea and vomiting, mucositis, and dysphagia. The purpose of this study was to quantify doses to critical structures for patients with OPC treated with IMPT and compare those with doses on IMRT plans generated for the same patients and with a matched cohort of patients actually treated with IMRT. In this study, 25 patients newly diagnosed with OPC were treated with IMPT between 2011 and 2012. Comparison IMRT plans were generated for these patients and for additional IMRT-treated controls extracted from a database of patients with OPC treated between 2000 and 2009. Cases were matched based on the following criteria, in order: unilateral vs bilateral therapy, tonsil vs base of tongue primary, T-category, N-category, concurrent chemotherapy, induction chemotherapy, smoking status, sex, and age. Results showed that the mean doses to the anterior and posterior oral cavity, hard palate, larynx, mandible, and esophagus were significantly lower with IMPT than with IMRT comparison plans generated for the same cohort, as were doses to several central nervous system structures involved in the nausea and vomiting response. Similar differences were found when comparing dose to organs at risks (OARs) between the IMPT cohort and the case-matched IMRT cohort. In conclusion, these findings suggest that patients with OPC treated with IMPT may experience fewer and less severe side effects during therapy. This may be the result of decreased beam path toxicities with IMPT due to lower doses to several dysphagia, odynophagia, and nausea and vomiting-associated OARs. Further study is needed to evaluate differences in long-term disease control and chronic toxicity between patients with OPC treated with IMPT in comparison to those

  14. THz electromagnetic radiation driven by intense relativistic electron beam based on ion focus regime

    NASA Astrophysics Data System (ADS)

    Zhou, Qing; Yang, Shengpeng; Xu, Jin; Zhang, Wenchao; Tang, Changjian; Duan, Zhaoyun; Gong, Yubin

    2016-06-01

    The simulation study finds that the relativistic electron beam propagating through the plasma background can produce electromagnetic (EM) radiation. With the propagation of the electron beam, the oscillations of the beam electrons in transverse and longitudinal directions have been observed simultaneously, which provides the basis for the electromagnetic radiation. The simulation results clearly show that the electromagnetic radiation frequency can reach up to terahertz (THz) wave band which may result from the filter-like property of plasma background, and the electromagnetic radiation frequency closely depends on the plasma density. To understand the above simulation results physically, the dispersion relation of the beam-plasma system has been derived using the field-matching method, and the dispersion curves show that the slow wave modes can couple with the electron beam effectively in THz wave band, which is an important theoretical evidence of the EM radiation.

  15. The protective effects of ambroxol on radiation lung injury and influence on production of transforming growth factor beta1 and tumor necrosis factor alpha.

    PubMed

    Xia, De-Hong; Xi, Lei; Xv, Chen; Mao, Wei-Dong; Shen, Wei-Sheng; Shu, Zhong-Qin; Yang, Hong-Zhi; Dai, Min

    2010-09-01

    The aim of this article was to investigate the effect of ambroxol on radiation lung injury and the expression of transforming growth factor beta(1) (TGF-beta(1)), as well as tumor necrosis factor alpha (TNF-alpha) in plasma. Totally, 120 patients with locally advanced lung cancer in radiotherapy were randomized into treatment and control groups. Patients in the treatment group took ambroxol orally at a dosage of 90 mg, three times per day for 3 months from the beginning of radiotherapy. The expression of TGF-beta(1) and TNF-alpha in plasma was analyzed. The clinical symptoms and lung diffusing capacity were monitored using high resolving power computed tomography. The level of TGF-beta(1) in the control group was increased (11.8 +/- 5.5 ng/ml), whereas in ambroxol-treated patients, the increase was not significant (5.6 +/- 2.6 ng/ml, P < 0.001). Radiotherapy-induced elevation of TNF-alpha levels, seen in control patients, was also abolished after treatment with ambroxol (5.1 +/- 1.0 vs. 2.4 +/- 0.8 ng/ml, P < 0.001). In the treatment group, carbon monoxide diffusion capacity was not significantly decreased at 6, 12, and 18 months post-radiotherapy, compared with the control group (P < 0.05). Ambroxol decreased the expression of TGF-beta(1) and TNF-alpha, and minimized the diminishment of lung diffusion capacity after radiotherapy. PMID:19636975

  16. The Detection of Lyman Alpha Radiation Formed by the Slowing Down of Protons and Tritons Produced by the 3He (n, tp) Reaction—A Model Study

    PubMed Central

    Cooper, John W.; Coplan, Michael A.; Hughes, Patrick P.

    2009-01-01

    The observation of Lyman alpha (Lα) radiation produced by the end products of the 3He (n,tp) reaction has suggested the possibility of a new method of cold thermal neutron detection. In order for this goal to be achieved, a basic understanding of how the Lα radiation is formed and how it may be detected, is needed. The model study described here is an attempt to provide this basic understanding and to provide quantitative results that can be used in designing future experiments.

  17. [The treatment of neurogenic hyperreflexic bladder dysfunctions in girls with low-intensity laser radiation].

    PubMed

    Kosilov, K V; Itskovich, A I; Orekhov, V R

    1995-01-01

    120 girls were investigated for the efficacy of three methods of treatment: conventional, infrared laser radiation on the projection of the bladder plus He-Ne laser radiation on biologically active points (BAP), red He-Ne laser BAP radiation. All the patients suffered from neurogenic hyperreflexic dysfunctions of the bladder, 99.8% had the diagnosis of vegetovascular dystonia, 94.9% had sympathetic-tonic or mixed patterns. The combined laser exposure brought about the greatest response rate-90.0%. PMID:7785111

  18. Scattering of intense femtosecond laser radiation at water aerosol in backward direction

    NASA Astrophysics Data System (ADS)

    Efimenko, E. S.; Malkov, Yu. A.; Murzanev, A. A.; Stepanov, A. N.

    2015-12-01

    We investigated the scattering of femtosecond laser pulses with intensities within the 1012-1013W/cm2 range at a water aerosol jet at 20° to backward direction. The scattered energy and spectra transformation as a function of incident intensity obtained in experiment show good agreement with the results of extensive numerical modeling based on self-consistent solution of Maxwell equations using a nonlinear 3D FDTD code and balance equation for plasma density.

  19. A novel conformity index for intensity modulated radiation therapy plan evaluation

    SciTech Connect

    Cheung, Fion W. K.; Law, Maria Y. Y.

    2012-09-15

    Purpose: Intensity modulated radiation therapy (IMRT) has gained popularity in the treatment of cancers. Manual evaluation of IMRT plans for head-and-neck cancers has been especially challenging necessitating efficient and objective assessment tools. In this work, the authors address this issue by developing a personalized conformity index (CI) for comparison of IMRT plans for head-and-neck cancers and evaluating its plan quality discerning power in comparison with other widely used CIs. Methods: A two-dimensional CI with dose and distance incorporated (CI{sub DD}) was developed using the MATLAB program language, to quantify the planning target volume (PTV) coverage. Valuable information contained in the digital imaging and communication in medicine (DICOM) RT objects were harvested for computation of each of the CI{sub DD} components. Apart from the dose penalty factor, a distance-based exponential function was employed by varying the penalty weight associated with the location of cold spots within the PTV. With the goal of deriving a customized penalty factor, the distances between individual pixel and its nearest PTV boundary was found. Using the exponential function, the impact of distance penalty was substantially larger for cold spots closer to the PTV centroid but petered out quickly wherever they were situated in the vicinity of PTV border. In order to evaluate the CI{sub DD} scoring system, three CT image data sets of nasopharyngeal carcinoma (NPC) patients were collected. Ten IMRT plans with degrading qualities were generated from each dataset and were ranked based on CI{sub DD} and other existing indices. The coefficient of variance was calculated for each dataset to compare the degree of variation. Results: The CI{sub DD} scoring system that considered spatial importance of each voxel within the PTV was successfully developed. The results demonstrated that the CI{sub DD} including four discrete factors could provide accurate rankings of plan quality by

  20. Factors modifying the response of large animals to low-intensity radiation exposure

    NASA Technical Reports Server (NTRS)

    Page, N. P.; Still, E. T.

    1972-01-01

    In assessing the biological response to space radiation, two of the most important modifying factors are dose protraction and dose distribution to the body. Studies are reported in which sheep and swine were used to compare the hematology and lethality response resulting from radiation exposure encountered in a variety of forms, including acute (high dose-rate), chronic (low dose-rate), combinations of acute and chronic, and whether received as a continuous or as fractionated exposure. While sheep and swine are basically similar in response to acute radiation, their sensitivity to chronic irradiation is markedly different. Sheep remain relatively sensitive as the radiation exposure is protracted while swine are more resistant and capable of surviving extremely large doses of chronic irradiation. This response to chronic irradiation correlated well with changes in radiosensitivity and recovery following an acute, sublethal exposure.

  1. Effects of radiation quality, intensity, and duration on photosynthesis and growth

    NASA Technical Reports Server (NTRS)

    Bugbee, Bruce

    1994-01-01

    Differences in radiation quality from the six most common electric lamps have little effect on photosynthetic rate. Radiation quality primarily alters growth because of changes in branching or internode elongation, which change radiation absorption. Growth and yield in wheat appear to be insensitive to radiation quality. Growth and yield in soybeans can be slightly increased under high pressure sodium (HPS) lamps compared to metal halide lamps, in spite of greatly reduced chlorophyll concentrations under HPS lamps. Daily integrated photosynthetic photon flux (mol m(exp -2)d(exp -1)) most directly determines leaf anatomy and growth. Photosynthetic photon flux (PPF) levels of 800 (mu)mol m(exp -2)s(exp -1) are adequate to simulate field daily-integrated PPF levels for both short and long day plants, but plant canopies can benefit from much higher PPF levels.

  2. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    NASA Astrophysics Data System (ADS)

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-01

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  3. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    SciTech Connect

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-26

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  4. Measurement of the L. beta. to L. cap alpha. intensity ratio through a selective excitation of L/sub III/ subshell in elements of Zgreater than or equal to70

    SciTech Connect

    Murty, G.S.K.; Chandrasekhar Rao, M.V.S.; Raghavaiah, C.V.; Reddy, S.B.; Satyanarayana, G.; Sastry, D.L.

    1989-02-01

    The intensity ratio of L..beta../sub 2/+L..beta../sub 5/+L..beta../sub 6/ to L..cap alpha../sub 1/+L..cap alpha../sub 2/ was measured in seven elements (Zgreater than or equal to70) through a selective excitation of the L/sub III/ subshell using an x-ray tube. A high-resolution Si(Li) detector system coupled to a computer controlled multichannel analyzer was used in these measurements. The results show that the relative transition probabilities L..beta.. and L..cap alpha.. agree with the relativistic Hartree-Fock-Slater calculations in the case of Yb and U, while a discrepancy of 3.1--8.7 % between experiment and theory is found for the other elements.

  5. Radiation Exposure to Staff in Intensive Care Unit with Portable CT Scanner

    PubMed Central

    Xie, Zhichao; Liao, Xuelian; Zhang, Jiangqian; Jia, Lingli

    2016-01-01

    Background. Bedside radiological procedures pose a risk of radiation exposure to ICU staff. The perception of risk may increase the degree of caution among the health care staff and raise new barriers preventing patients from obtaining prompt care. Objective. The aim of this study was to estimate the annual cumulative radiation dose to individual ICU staff. Methods. In this prospective study, forty subjects were required to wear thermoluminescent dosimeter badges during their working hours. The badges were analyzed to determine the exposure after 3 months. Results. A total of 802 radiological procedures were completed at bedside during the study period. The estimated annual dosage to doctors and nurses on average was 0.99 mSv and 0.88 mSv (p < 0.001), respectively. Residents were subjected to the highest radiation exposure (1.04 mSv per year, p = 0.002). The radiation dose was correlated with day shift working hours (r = 0.426; p = 0.006) and length of service (r = −0.403; p < 0.01). Conclusions. With standard precautions, bedside radiological procedures—including portable CT scans—do not expose ICU staff to high dose of ionizing radiation. The level of radiation exposure is related to the daytime working hours and length of service. PMID:27556036

  6. Patterns of Care and Outcomes Associated With Intensity-Modulated Radiation Therapy Versus Conventional Radiation Therapy for Older Patients With Head-and-Neck Cancer

    SciTech Connect

    Yu, James B.; Soulos, Pamela R.; Sharma, Richa; Makarov, Danil V.; Decker, Roy H.; Smith, Benjamin D.; Desai, Rani A.; Cramer, Laura D.; Gross, Cary P.

    2012-05-01

    Purpose: Intensity-modulated radiation therapy (IMRT) requires a high degree of expertise compared with standard radiation therapy (RT). We performed a retrospective cohort study of Medicare patients treated with IMRT compared with standard RT to assess outcomes in national practice. Methods and Materials: Using the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database, we identified patients treated with radiation for cancer of the head and neck from 2002 to 2005. We used multivariate Cox models to determine whether the receipt of IMRT was associated with differences in survival. Results: We identified 1613 patients, 33.7% of whom received IMRT. IMRT was not associated with differences in survival: the 3-year overall survival was 50.5% for IMRT vs. 49.6% for standard RT (p = 0.47). The 3-year cancer-specific survival was 60.0% for IMRT vs. 58.8% (p = 0.45). Conclusion: Despite its complexity and resource intensive nature, IMRT use seems to be as safe as standard RT in national community practice, because the use of IMRT did not have an adverse impact on survival.

  7. Evaluating the intensity of the acoustic radiation force impulse (ARFI) in intravascular ultrasound (IVUS) imaging: Preliminary in vitro results.

    PubMed

    Shih, Cho-Chiang; Lai, Ting-Yu; Huang, Chih-Chung

    2016-08-01

    The ability to measure the elastic properties of plaques and vessels is significant in clinical diagnosis, particularly for detecting a vulnerable plaque. A novel concept of combining intravascular ultrasound (IVUS) imaging and acoustic radiation force impulse (ARFI) imaging has recently been proposed. This method has potential in elastography for distinguishing between the stiffness of plaques and arterial vessel walls. However, the intensity of the acoustic radiation force requires calibration as a standard for the further development of an ARFI-IVUS imaging device that could be used in clinical applications. In this study, a dual-frequency transducer with 11MHz and 48MHz was used to measure the association between the biological tissue displacement and the applied acoustic radiation force. The output intensity of the acoustic radiation force generated by the pushing element ranged from 1.8 to 57.9mW/cm(2), as measured using a calibrated hydrophone. The results reveal that all of the acoustic intensities produced by the transducer in the experiments were within the limits specified by FDA regulations and could still displace the biological tissues. Furthermore, blood clots with different hematocrits, which have elastic properties similar to the lipid pool of plaques, with stiffness ranging from 0.5 to 1.9kPa could be displaced from 1 to 4μm, whereas the porcine arteries with stiffness ranging from 120 to 291kPa were displaced from 0.4 to 1.3μm when an acoustic intensity of 57.9mW/cm(2) was used. The in vitro ARFI images of the artery with a blood clot and artificial arteriosclerosis showed a clear distinction of the stiffness distributions of the vessel wall. All the results reveal that ARFI-IVUS imaging has the potential to distinguish the elastic properties of plaques and vessels. Moreover, the acoustic intensity used in ARFI imaging has been experimentally quantified. Although the size of this two-element transducer is unsuitable for IVUS imaging, the

  8. Ultraviolet observations of cool stars. IV - Intensities of Lyman-alpha and Mg II in epsilon Pegasi and epsilon Eridani, and line width-luminosity correlations

    NASA Technical Reports Server (NTRS)

    Mcclintock, W.; Linsky, J. L.; Henry, R. C.; Moos, H. W.

    1975-01-01

    A spectrometer on the Copernicus satellite has been used to confirm the existence of a line width-luminosity relation for the Ly-alpha and Mg II 2800-A chromospheric emission lines in K-type stars by observation of a K2 dwarf (epsilon Eri) and a K2 supergiant (epsilon Peg). Combined with previously reported observations of lines in three K giants (alpha Boo, alpha Tau, and beta Gem), the data are consistent with an identical dependence of line width on absolute visual magnitude for the Ca II K, Ly-alpha, and Mg II 2795-A lines. Surface fluxes of Ly-alpha, Mg II 2800-A, and O V 1218-A (upper limit) for epsilon Eri, and of Mg II 2800-A for epsilon Peg are also compared with values reported previously for the three giant stars.

  9. Effect of radiation protraction in intensity-modulated radiation therapy with direct aperture optimization: a phantom study

    NASA Astrophysics Data System (ADS)

    Kuperman, V. Y.; Ventura, A. M.; Sommerfeldt, M.

    2008-06-01

    The effect of radiation protraction in step-and-shoot IMRT is investigated for treatment plans created with the help of direct aperture optimization. The latter approach can be used during inverse planning for all clinical linear accelerators with conventional MLC. Direct aperture optimization significantly shortens fraction time for IMRT plans as compared to that for plans obtained by using the conventional inverse planning approach. By analyzing several IMRT plans obtained with direct aperture optimization we found that for α/β ratio of 10 Gy (characteristic of fast growing tumors) the protraction effect is probably clinically insignificant for both conventional and large fraction sizes of 1.9 Gy and 5.7 Gy, respectively. For small α/β of 1-1.5 Gy and conventional fraction size the effect of protraction is still small; however, this effect can be significant for hypofractionated treatments. Based on the obtained results it is recommended that, when possible, IMRT for slow growing prostate cancers be performed with small number of beams (e.g., 5) and small number of segments (e.g., 5-7 segments per beam) to reduce delivery time and, as a result, the associated effect of radiation protraction.

  10. Biophotonics of the interaction of low-intensity laser radiation with blood erythrocytes

    NASA Astrophysics Data System (ADS)

    Asimov, M. M.; Asimov, R. M.; Batyan, A. N.; Trusevich, M. O.; Rubinov, A. N.

    2013-06-01

    We have studied experimentally how optical radiation affects the neutralization of the toxic action of heavy metals and harmful chemical compounds (ecotoxicants) on the oxygen-transport function of blood erythrocytes. It has been found that the optical radiation has a stabilizing effect and prevents lowering the erythrocyte concentration in the presence of phenol and heavy metals in blood. We have studied the neutralization efficiency of the toxic action of ecotoxicants in relation to the laser irradiation time. The obtained data on the effect of the laser radiation on the thermal denaturation of hemoglobin and erythrocytes yield the scientific substantiation to the development of the optical method for the use in medicine upon drawing and conserving donor blood. We have shown that the obtained data can be used in medicine for improving the reliability of conditions of conservation and storage of donor blood, as well as for preventing the toxic action of harmful chemical compounds in the environment.

  11. Radiated energy and impurity density changes during intensive hydrogen influx in the PLT tokamak

    SciTech Connect

    Hinnov, E.; Hosea, J.; Hsuan, H.; Jobes, F.; Meservey, E.; Schmidt, G.; Suckewer, S.

    1981-12-01

    During a discharge a puff of hydrogen is admitted, sufficient to more than triple the plasma density, and the resulting changes in various plasma parameters are determined. The absolute densities of various wall and limiter (carbon) materials are found to decrease by a substantial fraction, probably as a result of lowered peripheral temperature. The radiation pattern deduced from spectroscopically determined plasma composition is in good quantitative agreement with direct bolometric measurements. In the interior of the discharge radiation constitutes only a small part of the power input. Neither the radiated power nor the power input changes very markedly as a result of the density rise, since the effects of temperature and plasma composition changes tend to compensate each other.

  12. 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

  13. Possible molecular effect related to the reception of low-intensity IR radiation: Role of Src-kinase

    NASA Astrophysics Data System (ADS)

    Yachnev, I. L.; Shelykh, T. N.; Podzorova, S. A.; Rogachevskii, I. V.; Krylov, B. V.; Plakhova, V. B.

    2016-06-01

    The patch-clamp technique has been used to demonstrate that low-intensity IR irradiation affects the effective charge of the activation gating system of slow sodium channels in the nociceptive neuron membrane. IR photons are absorbed by ATP molecules bound to Na+,K+-ATPase at their hydrolysis site. Na+,K+-ATPase is a transducer of signal that is further delivered to slow sodium channels and cell genome. It is demonstrated that the irradiation does not modulate the response of a sensory neuron in the presence of PP2, an inhibitor of Src-kinase. The results show that Src-kinase is a series unit involved in the intracellular cascade processes triggered by low-intensity radiation of CO2 laser.

  14. Predicting the macroseismic intensity from early radiated P wave energy for on-site earthquake early warning in Italy

    NASA Astrophysics Data System (ADS)

    Brondi, P.; Picozzi, M.; Emolo, A.; Zollo, A.; Mucciarelli, M.

    2015-10-01

    Earthquake Early Warning Systems (EEWS) are potentially effective tools for risk mitigation in active seismic regions. The present study explores the possibility of predicting the macroseismic intensity within EEW timeframes using the squared velocity integral (IV2) measured on the early P wave signals, a proxy for the P wave radiated energy of earthquakes. This study shows that IV2 correlates better than the peak displacement measured on P waves with both the peak ground velocity and the Housner Intensity, with the latter being recognized by engineers as a reliable proxy for damage assessment. Therefore, using the strong motion recordings of the Italian Accelerometric Archive, a novel relationship between the parameter IV2 and the macroseismic intensity (IM) has been derived. The validity of this relationship has been assessed using the strong motion recordings of the Istituto Nazionale di Geofisica e Vulcanologia Strong Motion Data and Osservatorio Sismico delle Strutture databases, as well as, in the case of the MW 6, 29 May 2012 Emilia earthquake (Italy), comparing the predicted intensities with the ones observed after a macroseismic survey. Our results indicate that P wave IV2 can become a key parameter for the design of on-site EEWS, capable of proving real-time predictions of the IM at target sites.

  15. Dependence of injection locking of a TEA CO/sub 2/ laser on intensity of injected radiation

    SciTech Connect

    Not Available

    1982-09-01

    The authors report the results of an experimental study to determine the minimum required injected power to control the output frequency of a TEA CO/sub 2/ laser. A CW CO/sub 2/ waveguide laser was used as the injection oscillator. Both the power and the frequency of the injected radiation were varied, while the TEA reasonator cavity length was adjusted to match the frequency of the injected signal. Single longitudinal mode (SLM) TEA laser radiation was produced for injected power levels which are several orders of magnitude below those previously reported. The ratio of SLM output power to injection power exceeded 10/sup 12/ at the lowest levels of injected intensity.

  16. Inverse problem of nonlinear acoustics: Synthesizing intense signals to intensify the thermal and radiation action of ultrasound

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.; Gurbatov, S. N.

    2016-07-01

    Inverse problems of nonlinear acoustics have important applied significance. On the one hand, they are necessary for nonlinear diagnostics of media, materials, manufactured articles, building units, and biological and geological structures. On the other hand, they are needed for creating devices that ensure optimal action of acoustic radiation on a target. However, despite the many promising applications, this direction remains underdeveloped, especially for strongly distorted high-intensity waves containing shock fronts. An example of such an inverse problem is synthesis of the spatiotemporal structure of a field in a radiating system that ensures the highest possible energy density in the focal region. This problem is also related to the urgent problems of localizing wave energy and the theory of strongly nonlinear waves. Below we analyze some quite general and simple inverse nonlinear problems.

  17. Decoupling Intensity Radiated by the Emitter in Distance Estimation from Camera to IR Emitter

    PubMed Central

    Cano-García, Angel E.; Galilea, José Luis Lázaro; Fernández, Pedro; Infante, Arturo Luis; Pompa-Chacón, Yamilet; Vázquez, Carlos Andrés Luna

    2013-01-01

    Various models using radiometric approach have been proposed to solve the problem of estimating the distance between a camera and an infrared emitter diode (IRED). They depend directly on the radiant intensity of the emitter, set by the IRED bias current. As is known, this current presents a drift with temperature, which will be transferred to the distance estimation method. This paper proposes an alternative approach to remove temperature drift in the distance estimation method by eliminating the dependence on radiant intensity. The main aim was to use the relative accumulated energy together with other defined models, such as the zeroth-frequency component of the FFT of the IRED image and the standard deviation of pixel gray level intensities in the region of interest containing the IRED image. By using the abovementioned models, an expression free of IRED radiant intensity was obtained. Furthermore, the final model permitted simultaneous estimation of the distance between the IRED and the camera and the IRED orientation angle. The alternative presented in this paper gave a 3% maximum relative error over a range of distances up to 3 m. PMID:23727954

  18. Radiation effects on the D to G Raman intensities of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Aitkaliyeva, Assel; Martin, Michael S.; Harriman, Tres A.; Hildebrand, Daniel S.; Lucca, Don A.; Wang, Jing; Chen, Di; Shao, Lin

    2014-06-01

    For carbon nanotubes irradiated with 140 keV He ions, the intensity ratio of the D to G Raman modes initially increases and then decreases with increasing ion fluence. A model is proposed to describe the competing effects between the reduction in crystal size, which increases the D band intensity with increasing fluence as a long-range order effect, and the reduction in the number of sixfold rings available for D mode vibration, which decreases the D band intensity with increasing fluence as a short-range order effect. The latter effect dominates when the length of the short-range order becomes comparable to the unit-cell dimensions as a result of ion bombardment. This suggests that the appearance of the maximum D to G intensity ratio coincides with the onset of structural amorphization. The model is supported experimentally by examination of irradiated nanotubes with transmission electron microscopy, and theoretically by Raman calculation based on density functional perturbation theory. A universal formula is proposed to describe D /G behaviors under arbitrary ion irradiation.

  19. First Experiences in Intensity Modulated Radiation Surgery at the National Institute of Neurology and Neurosurgery: A Dosimetric Point of View

    NASA Astrophysics Data System (ADS)

    Lárraga-Gutiérrez, José M.; Celis-López, Miguel A.

    2003-09-01

    The National Institute of Neurology and Neurosurgery in Mexico City has acquired a Novalis® shaped beam radiosurgery unit. The institute is pioneer in the use of new technologies for neuroscience. The Novalis® unit allows the use of conformal beam radiosurgery/therapy and the more advanced modality of conformal therapy: Intensity Modulated Radiation Therapy (IMRT). In the present work we present the first cases of treatments that use the IMRT technique and show its ability to protect organs at risk, such as brainstem and optical vias.

  20. Waveguide CO{sub 2} laser with a quasi-homogeneous distribution of the output radiation intensity

    SciTech Connect

    Vlasenko, S A; Gurin, O V; Degtyarev, A V; Maslov, Vyacheslav A; Svich, V A; Topkov, A N

    2013-05-31

    An experimental sample of a waveguide CO{sub 2} laser with a quasi-uniform profile of the output radiation intensity is designed on the basis of a waveguide quasi-optical cavity of a new type comprising the generic confocal cavity with a nonuniform mirror and the hollow waveguide with the dimensions satisfying the conditions for self-imaging the quasi-uniform field. The surface of the mirror has the discrete large-scale absorbing nonuniformities. Results of theoretical and experimental investigations of spatial-energy characteristics of the laser in using uniform or amplitude-stepped reflecting mirrors are presented. (lasers)