ULTRAVIOLET RADIATION DOWN-REGULATES ALLERGY IN BALB/C MICE

EPA Science Inventory

ULTRAVIOLET RADIATION SUPPRESSES ALLERGY IN BALB/C MICE
Marsha D.W. Ward+ *, Denise M. Sailstad+, Debora L. Andrews, Elizabeth H. Boykin, and MaryJane K. Selgrade

ABSTRACT
The immunosuppressive effects of exposure to ultraviolet radiation (UVR) are well known and the...

Modelling of a holographic interferometry based calorimeter for radiation dosimetry

NASA Astrophysics Data System (ADS)

Beigzadeh, A. M.; Vaziri, M. R. Rashidian; Ziaie, F.

2017-08-01

In this research work, a model for predicting the behaviour of holographic interferometry based calorimeters for radiation dosimetry is introduced. Using this technique for radiation dosimetry via measuring the variations of refractive index due to energy deposition of radiation has several considerable advantages such as extreme sensitivity and ability of working without normally used temperature sensors that disturb the radiation field. We have shown that the results of our model are in good agreement with the experiments performed by other researchers under the same conditions. This model also reveals that these types of calorimeters have the additional and considerable merits of transforming the dose distribution to a set of discernible interference fringes.

Lighting considerations in controlled environments for nonphotosynthetic plant responses to blue and ultraviolet radiation

NASA Technical Reports Server (NTRS)

Caldwell, M. M.; Flint, S. D.

1994-01-01

This essay will consider both physical and photobiological aspects of controlled environment lighting in the spectral region beginning in the blue and taken to the normal limit of the solar spectrum in the ultraviolet. The primary emphasis is directed to questions of plant response to sunlight. Measurement and computations used in radiation dosimetry in this part of the spectrum are also briefly treated. Because of interest in the ozone depletion problem, there has been some activity in plant UV-B research and there are several recent reviews available. Some aspects of growth chamber lighting as it relates to UV-B research were covered earlier. Apart from work related to the blue/UV-A receptor, less attention has been given to UV-A responses.

[Ultraviolet radiation and long term space flight].

PubMed

Wu, H B; Su, S N; Ba, F S

2000-08-01

With the prolongation of space flight, influences of various aerospace environmental factors on the astronauts become more and more severe, while ultraviolet radiation is lacking. Some studies indicated that low doses of ultraviolet rays are useful and essential for human body. In space flight, ultraviolet rays can improve the hygienic condition in the space cabin, enhance astronaut's working ability and resistance to unfavorable factors, prevent mineral metabolic disorders, cure purulent skin diseases and deallergize the allergens. So in long-term space flight, moderate amount of ultraviolet rays in the space cabin would be beneficial.

Inhibition of seagrass photosynthesis by ultraviolet-B radiation.

PubMed

Trocine, R P; Rice, J D; Wells, G N

1981-07-01

Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme Kütz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated.Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. This mechanism effectively attenuated photosynthetic inhibition induced by ultraviolet-B dose rates and dosages in excess of natural conditions. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species.Observations obtained in this study seem to suggest the possibility of anthocyanin and/or other flavonoid synthesis as an adaptation to long term ultraviolet-B irradiation by these species. In addition, Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation.

Radiation dosimetry and biophysical models of space radiation effects

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Wu, Honglu; Shavers, Mark R.; George, Kerry

2003-01-01

Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

Photoprotection of human skin beyond ultraviolet radiation.

PubMed

Grether-Beck, Susanne; Marini, Alessandra; Jaenicke, Thomas; Krutmann, Jean

2014-01-01

Photoprotection of human skin by means of sunscreens or daily skin-care products is traditionally centered around the prevention of acute (e.g. sunburn) and chronic (e.g. skin cancer and photoaging) skin damage that may result from exposure to ultraviolet rays (UVB and UVA). Within the last decade, however, it has been appreciated that wavelengths beyond the ultraviolet spectrum, in particular visible light and infrared radiation, contribute to skin damage in general and photoaging of human skin in particular. As a consequence, attempts have been made to develop skin care/sunscreen products that not only protect against UVB or UVA radiation but provide photoprotection against visible light and infrared radiation as well. In this article, we will briefly review the current knowledge about the mechanisms responsible for visible light/infrared radiation-induced skin damage and then, based on this information, discuss strategies that have been successfully used or may be employed in the future to achieve photoprotection of human skin beyond ultraviolet radiation. In this regard we will particularly focus on the use of topical antioxidants and the challenges that result from the task of showing their efficacy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

ULTRAVIOLET PROTECTIVE COMPOUNDS AS A RESPONSE TO ULTRAVIOLET RADIATION EXPOSURE

EPA Science Inventory

Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet radiation. In response to UVR organisms have adapted myriad responses; behavioral, morphological and physiological. Behaviorally, some orga...

Lighting considerations in controlled environments for nonphotosynthetic plant responses to blue and ultraviolet radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldwell, M.M.; Flint, S.D.

1994-12-31

This essay will consider both physical and photobiological aspects of controlled environment lighting in the spectral region beginning in the blue and taken to the normal limit of the solar spectrum in the ultraviolet. The primary emphasis is directed to questions of plant response to sunlight. Measurement and computations used in radiation dosimetry in this part of the spectrum are also briefly treated. Because of interest in the ozone depletion problem, there has been some activity in plant UV-B research and there are several recent reviews available. Some aspects of growth chamber lighting as it relates to UV-B research weremore » covered earlier. Apart from work related to the blue/UV-A receptor, less attention has been given to UV-A responses.« less

Fluorescence of molecular hydrogen excited by solar extreme-ultraviolet radiation

NASA Technical Reports Server (NTRS)

Feldman, P. D.; Fastie, W. G.

1973-01-01

During trans-earth coast, the Apollo 17 ultraviolet spectrometer was scheduled to make observations of the far ultraviolet background in selected regions of the sky. In the course of one of these observations, the spacecraft fuel cells were routinely purged of excess hydrogen and water vapor. The ultraviolet fluorescence spectrum of the purged molecular hydrogen excited by solar extreme ultraviolet radiation is interpreted by absorption of solar L-beta and L-gamma radiation in the nearly resonant (6, 0) and (11, 0) Lyman bands. The results are deemed significant for ultraviolet spectroscopic investigations of the atmospheres of the moon and planets since Lyman-band fluorescence provides an unambiguous means of identification of molecular hydrogen in upper atmospheres.

Two ultraviolet radiation datasets that cover China

NASA Astrophysics Data System (ADS)

Liu, Hui; Hu, Bo; Wang, Yuesi; Liu, Guangren; Tang, Liqin; Ji, Dongsheng; Bai, Yongfei; Bao, Weikai; Chen, Xin; Chen, Yunming; Ding, Weixin; Han, Xiaozeng; He, Fei; Huang, Hui; Huang, Zhenying; Li, Xinrong; Li, Yan; Liu, Wenzhao; Lin, Luxiang; Ouyang, Zhu; Qin, Boqiang; Shen, Weijun; Shen, Yanjun; Su, Hongxin; Song, Changchun; Sun, Bo; Sun, Song; Wang, Anzhi; Wang, Genxu; Wang, Huimin; Wang, Silong; Wang, Youshao; Wei, Wenxue; Xie, Ping; Xie, Zongqiang; Yan, Xiaoyuan; Zeng, Fanjiang; Zhang, Fawei; Zhang, Yangjian; Zhang, Yiping; Zhao, Chengyi; Zhao, Wenzhi; Zhao, Xueyong; Zhou, Guoyi; Zhu, Bo

2017-07-01

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

Aqueous humour and ultraviolet radiation.

PubMed

Ringvold, A

1980-01-01

Studies on the ultraviolet ray absorption in the aqueous humour of rabbit, cat, monkey, guinea pig, and rat showed marked species differences. In the rabbit aqueous the ascorbic acid, the proteins, and some amino acids (tyrosine, phenylalanine, cystine, and tryptophane) are together responsible for the total absorption, and a very great part of it refers to the ascorbic acid content. Accordingly, species with significant amounts of ascorbic acid in the aqueous (monkey, rabbit, guinea pig) have a greater absorption capacity towards ultraviolet radiation than species (cat, rat) lacking this substance. This effect of the ascorbic acid may contribute in protecting the lens against the most biotoxic ultraviolet rays. It seems that the ascorbic acid concentration is highest in the aqueous of typical day animals and lowest in species being active in the dark, indicating a correlation between the aqueous' ascorbic acid level and the quantity of incident light on the eye. The possible significance of changed aqueous ultraviolet ray absorption in the pathogenesis of human cataract development is discussed.

Micro-Fabricated Solid-State Radiation Detectors for Active Personal Dosimetry

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Chen, Liang-Yu

2007-01-01

Active radiation dosimetry is important to human health and equipment functionality for space applications outside the protective environment of a space station or vehicle. This is especially true for long duration missions to the moon, where the lack of a magnetic field offers no protection from space radiation to those on extravehicular activities. In order to improve functionality, durability and reliability of radiation dosimeters for future NASA lunar missions, single crystal silicon carbide devices and scintillating fiber detectors are currently being investigated for applications in advanced extravehicular systems. For many years, NASA Glenn Research Center has led significant efforts in silicon carbide semiconductor technology research and instrumentation research for sensor applications under extreme conditions. This report summarizes the technical progress and accomplishments toward characterization of radiation-sensing components for the recommendation of their fitness for advanced dosimetry development.

Inhibition of Seagrass Photosynthesis by Ultraviolet-B Radiation 1

PubMed Central

Trocine, Robert P.; Rice, John D.; Wells, Gary N.

1981-01-01

Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme Kütz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated. Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. This mechanism effectively attenuated photosynthetic inhibition induced by ultraviolet-B dose rates and dosages in excess of natural conditions. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species. Observations obtained in this study seem to suggest the possibility of anthocyanin and/or other flavonoid synthesis as an adaptation to long term ultraviolet-B irradiation by these species. In addition, Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation. Images PMID:16661893

Fourth conference on radiation protection and dosimetry: Proceedings, program, and abstracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casson, W.H.; Thein, C.M.; Bogard, J.S.

This Conference is the fourth in a series of conferences organized by staff members of Oak Ridge National Laboratory in an effort to improve communication in the field of radiation protection and dosimetry. Scientists, regulators, managers, professionals, technologists, and vendors from the United States and countries around the world have taken advantage of this opportunity to meet with their contemporaries and peers in order to exchange information and ideas. The program includes over 100 papers in 9 sessions, plus an additional session for works in progress. Papers are presented in external dosimetry, internal dosimetry, radiation protection programs and assessments, developmentsmore » in instrumentation and materials, environmental and medical applications, and on topics related to standards, accreditation, and calibration. Individual papers are indexed separately on EDB.« less

Radiation protection and dosimetry issues in the medical applications of ionizing radiation

NASA Astrophysics Data System (ADS)

Vaz, Pedro

2014-11-01

The technological advances that occurred during the last few decades paved the way to the dissemination of CT-based procedures in radiology, to an increasing number of procedures in interventional radiology and cardiology as well as to new techniques and hybrid modalities in nuclear medicine and in radiotherapy. These technological advances encompass the exposure of patients and medical staff to unprecedentedly high dose values that are a cause for concern due to the potential detrimental effects of ionizing radiation to the human health. As a consequence, new issues and challenges in radiological protection and dosimetry in the medical applications of ionizing radiation have emerged. The scientific knowledge of the radiosensitivity of individuals as a function of age, gender and other factors has also contributed to raising the awareness of scientists, medical staff, regulators, decision makers and other stakeholders (including the patients and the public) for the need to correctly and accurately assess the radiation induced long-term health effects after medical exposure. Pediatric exposures and their late effects became a cause of great concern. The scientific communities of experts involved in the study of the biological effects of ionizing radiation have made a strong case about the need to undertake low dose radiation research and the International System of Radiological Protection is being challenged to address and incorporate issues such as the individual sensitivities, the shape of dose-response relationship and tissue sensitivity for cancer and non-cancer effects. Some of the answers to the radiation protection and dosimetry issues and challenges in the medical applications of ionizing radiation lie in computational studies using Monte Carlo or hybrid methods to model and simulate particle transport in the organs and tissues of the human body. The development of sophisticated Monte Carlo computer programs and voxel phantoms paves the way to an accurate

Photoluminescence emission spectra of Makrofol® DE 1-1 upon irradiation with ultraviolet radiation

NASA Astrophysics Data System (ADS)

El Ghazaly, M.; Aydarous, Abdulkadir

Photoluminescence (PL) emission spectra of Makrofol® DE 1-1 (bisphenol-A based polycarbonate) upon irradiation with ultraviolet radiation of different wavelengths were investigated. The absorption-and attenuation coefficient measurements revealed that the Makrofol® DE 1-1 is characterized by high absorbance in the energy range 6.53-4.43 eV but for a lower energy than 4.43 eV, it is approximately transparent. Makrofol® DE 1-1 samples were irradiated with ultraviolet radiation of wavelength in the range from 250 (4.28 eV) to 400 (3.10 eV) nm in step of 10 nm and the corresponding photoluminescence (PL) emission spectra were measured with a spectrofluorometer. It is found that the integrated counts and the peak height of the photoluminescence emission (PL) bands are strongly correlated with the ultraviolet radiation wavelength. They are increased at the ultraviolet radiation wavelength 280 nm and have maximum at 290 nm, thereafter they decrease and diminish at 360 nm of ultraviolet wavelength. The position of the PL emission band peak was red shifted starting from 300 nm, which increased with the increase the ultraviolet radiation wavelength. The PL bandwidth increases linearly with the increase of the ultraviolet radiation wavelength. When Makrofol® DE 1-1 is irradiated with ultraviolet radiation of short wavelength (UVC), the photoluminescence emission spectra peaks also occur in the UVC but of a relatively longer wavelength. The current new findings should be considered carefully when using Makrofol® DE 1-1 in medical applications related to ultraviolet radiation.

Elastomeric Seal Performance after Terrestrial Ultraviolet Radiation Exposure

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.; Dunlap, Patrick H.

2015-01-01

Ultraviolet radiation was evaluated to determine its negative effects on the performance of elastomeric gas pressure seals. The leak rates of the silicone elastomer S0383-70 O-ring test articles were used to quantify the degradation of the seals after exposure to vacuum-ultraviolet and/or middle-to-near-ultraviolet wavelength radiation. Three groups of seals were exposed in terrestrial facilities to 115-165 nm wavelength radiation, 230-500 nm wavelength radiation, or both spectrums, for an orbital spaceflight equivalent of 125 hours. The leak rates of the silicone elastomer S0383-70 seals were quantified and compared to samples that received no radiation. Each lot contained six samples and statistical t-tests were used to determine the separate and combined influences of exposure to the two wavelength ranges. A comparison of the mean leak rates of samples exposed to 115-165 nm wavelength radiation to the control specimens showed no difference, suggesting that spectrum was not damaging. The 230-500 nm wavelength appeared to be damaging, as the mean leak rates of the specimens exposed to that range of wavelengths, and those exposed to the combined 115-165 nm and 230-500 nm spectrums, were significantly different from the leak rates of the control specimens. Most importantly, the test articles exposed to both wavelength spectrums exhibited mean leak rates two orders of magnitude larger than any other exposed specimens, which suggested that both wavelength spectrums are important when simulating the orbital environment.

Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

NASA Technical Reports Server (NTRS)

1979-01-01

The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

The contributions of solar ultraviolet radiation exposure and other determinants to serum 25-hydroxyvitamin D concentrations in Australian adults: the AusD Study.

PubMed

Kimlin, Michael G; Lucas, Robyn M; Harrison, Simone L; van der Mei, Ingrid; Armstrong, Bruce K; Whiteman, David C; Kricker, Anne; Nowak, Madeleine; Brodie, Alison M; Sun, Jiandong

2014-04-01

The Quantitative Assessment of Solar UV [ultraviolet] Exposure for Vitamin D Synthesis in Australian Adults (AusD) Study aimed to better define the relationship between sun exposure and serum 25-hydroxyvitamin D (25(OH)D) concentration. Cross-sectional data were collected between May 2009 and December 2010 from 1,002 participants aged 18-75 years in 4 Australian sites spanning 24° of latitude. Participants completed the following: 1) questionnaires on sun exposure, dietary vitamin D intake, and vitamin D supplementation; 2) 10 days of personal ultraviolet radiation dosimetry; 3) a sun exposure and physical activity diary; and 4) clinical measurements and blood collection for 25(OH)D determination. Our multiple regression model described 40% of the variance in 25(OH)D concentration; modifiable behavioral factors contributed 52% of the explained variance, and environmental and demographic or constitutional variables contributed 38% and 10%, respectively. The amount of skin exposed was the single strongest contributor to the explained variance (27%), followed by location (20%), season (17%), personal ultraviolet radiation exposure (8%), vitamin D supplementation (7%), body mass index (weight (kg)/height (m)(2)) (4%), and physical activity (4%). Modifiable behavioral factors strongly influence serum 25(OH)D concentrations in Australian adults. In addition, latitude was a strong determinant of the relative contribution of different behavioral factors.

Ultraviolet radiation, human health, and the urban forest

Treesearch

Gordon M. Heisler; Richard H. Grant

2000-01-01

Excess exposure to ultraviolet (UV) radiation from the sun, particularly the ultraviolet B (UVB) portion, has been linked with adverse effects on human health ranging from skin cancers to eye diseases such as cataracts. Trees may prevent even greater disease rates in humans by reducing UV exposure. Tree shade greatly reduces UV irradiance when both the sun and sky are...

High LET, passive space radiation dosimetry and spectrometry

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A. L.; Benton, E. R.; Keegan, R. P.; Frigo, L. A.; Sanner, D.; Rowe, V.

1995-01-01

The development of high linear energy transfer (LET), passive radiation dosimetry and spectrometry is needed for the purpose of accurate determination of equivalent doses and assessment of health risks to astronauts on long duration missions. Progress in the following research areas is summerized: intercomparisons of cosmic ray equivalent dose and LET spectra measurements between STS missions and between astronauts; increases LET spectra measurement accuracy with ATAS; space radiation measurements for intercomparisons of passive (PNTD, TLD, TRND, Emulsion) and active (TEPC, RME-111) dosimeters; interaction of cosmic ray particles with nuclei in matter; radiation measurements after long duration space exposures; ground based dosimeter calibrations; neutron detector calibrations; radiation measurements on Soviet/Russian spacecraft; space radiation measurements under thin shielding; and space radiation.

Understanding the Early Evolution of M dwarf Extreme Ultraviolet Radiation

NASA Astrophysics Data System (ADS)

Peacock, Sarah; Barman, Travis; Shkolnik, Evgenya

2015-11-01

The chemistry and evolution of planetary atmospheres depends on the evolution of high-energy radiation emitted by its host star. High levels of extreme ultraviolet (EUV) radiation can drastically alter the atmospheres of terrestrial planets through ionizing, heating, expanding, chemically modifying and eroding them during the first few billion years of a planetary lifetime. While there is evidence that stars emit their highest levels of far and near ultraviolet (FUV; NUV) radiation in the earliest stages of their evolution, we are currently unable to directly measure the EUV radiation. Most previous stellar atmosphere models under-predict FUV and EUV emission from M dwarfs; here we present new models for M stars that include prescriptions for the hot, lowest density atmospheric layers (chromosphere, transition region and corona), from which this radiation is emitted. By comparing our model spectra to GALEX near and far ultraviolet fluxes, we are able to predict the evolution of EUV radiation for M dwarfs from 10 Myr to a few Gyr. This research is the next major step in the HAZMAT (HAbitable Zones and M dwarf Activity across Time) project to analyze how the habitable zone evolves with the evolving properties of stellar and planetary atmospheres.

Solar ultraviolet radiation from cancer induction to cancer prevention: solar ultraviolet radiation and cell biology.

PubMed

Tuorkey, Muobarak J

2015-09-01

Although decades have elapsed, researchers still debate the benefits and hazards of solar ultraviolet radiation (UVR) exposure. On the one hand, humans derive most of their serum 25-hydroxycholecalciferol [25(OH)D3], which has potent anticancer activity, from solar UVB radiation. On the other hand, people are more aware of the risk of cancer incidence associated with harmful levels of solar UVR from daily sunlight exposure. Epidemiological data strongly implicate UV radiation exposure as a major cause of melanoma and other cancers, as UVR promotes mutations in oncogenes and tumor-suppressor genes. This review highlights the impact of the different mutagenic effects of solar UVR, along with the cellular and carcinogenic challenges with respect to sun exposure.

Ultraviolet radiation (UVR) dosimetry system and the use of Ge-doped silica optical fibres

NASA Astrophysics Data System (ADS)

Abdul Rahman, Ahmad Taufek; Abu Bakar, Noor Khairunnisa; Chandra Paul, Mukul; Bradley, D. A.

2014-11-01

Previous studies have shown that over exposure to ultraviolet radiation (UVR), either from sunlight or artificial sources, can cause severe biological effects including cataracts, photokeratitis and skin cancer. In this respect, there exists the need to introduce a sensitive UV dosimetric material capable of measuring radiation dose to high accuracy in order to deliver UVR safely and efficiently. Present study has focussed on the investigation of the potential thermoluminescent (TL) sensitivity of commercially available germanium (Ge)-doped silica (SiO2) optical fibres subjected to UVR. The main interest of this study is to find out whether these doped SiO2 optical fibres can be used as a sensible integrator of environmental UV exposures. In the present study, commercially available Ge-doped SiO2 optical fibres have been used with a core diameter of 11 μm (CorActive, Canada), 23 μm (Central Glass and Ceramic Research Institute Kolkata, India) and 50 μm (Central Glass and Ceramic Research Institute Kolkata, India) and a cladding diameter of 125±0.1 μm, irradiated over a wide range of UV dose. Results have shown that these fibres exhibit a linear dose response (with correlation coefficient better than 0.9852). The 50 μm fibre produces greater TL response than that obtained for 11- and 23 μm fibres. The TL results are compared with that of the well-established TL dosimeter material lithium fluoride.

PREFACE: 8th International Conference on 3D Radiation Dosimetry (IC3DDose)

NASA Astrophysics Data System (ADS)

Olsson, Lars E.; Bäck, S.; Ceberg, Sofie

2015-01-01

IC3DDose 2014, the 8th International Conference on 3D Radiation Dosimetry was held in Ystad, Sweden, from 4-7 September 2014. This grew out of the DosGel series, which began as DosGel99, the 1st International Workshop on Radiation Therapy Gel Dosimetry in Lexington, Kentucky. Since 1999 subsequent DoSGel conferences were held in Brisbane, Australia (2001), Ghent, Belgium (2004), Sherbrooke, Canada (2006) and Crete, Greece (2008). In 2010 the conference was held on Hilton Head Island, South Carolina and underwent a name-change to IC3DDose. The 7th and last meeting was held in Sydney, Australia from 4-8 November 2012. It is worth remembering that the conference series started at the very beginning of the intensity modulated radiotherapy era and that the dosimeters being developed then were, to some extent, ahead of the clinical need of radiotherapy. However, since then the technical developments in radiation therapy have been dramatic, with dynamic treatments, including tracking, gating and volumetric modulated arc therapy, widely introduced in the clinic with the need for 3D dosimetry thus endless. This was also reflected by the contributions at the meeting in Ystad. Accordingly the scope of the meeting has also broadened to IC3DDOSE - I See Three-Dimensional Dose. A multitude of dosimetry techniques and radiation detectors are now represented, all with the common denominator: three-dimensional or 3D. Additionally, quality assurance (QA) procedures and other aspects of clinical dosimetry are represented. The implementation of new dosimetric techniques in radiotherapy is a process that needs every kind of caution, carefulness and thorough validation. Therefore, the clinical needs, reformulated as the aims for IC3DDOSE - I See Three-Dimensional Dose, are: • Enhance the quality and accuracy of radiation therapy treatments through improved clinical dosimetry. • Investigate and understand the dosimetric challenges of modern radiation treatment techniques. • Provide

Effects of ultraviolet radiation on lattice imperfections in pyrolytic boron nitride.

NASA Technical Reports Server (NTRS)

Buckley, J. D.; Cooley, J. A.

1971-01-01

Pyrolitic boron nitride was exposed to 310 equivalent sun hours of ultraviolet radiation in a space environment simulator with the objective to evaluate its applicability as a pigment for a thermal control coating and to identify radiation damage using X-ray diffraction techniques. Lattice parameter comparisons show a definite increase in lattice imperfections in the crystal structure resulting from the ultraviolet irradiation. This sensitivity to radiation damage makes pyrolitic boron nitride unsuitable as a pigment for thermal control coating.

The PUR Experiment on the EXPOSE-R facility: biological dosimetry of solar extraterrestrial UV radiation

NASA Astrophysics Data System (ADS)

Bérces, A.; Egyeki, M.; Fekete, A.; Horneck, G.; Kovács, G.; Panitz, C.

2015-01-01

The aim of our experiment Phage and Uracil Response was to extend the use of bacteriophage T7 and uracil biological dosimeters for measuring the biologically effective ultraviolet (UV) dose in the harsh extraterrestrial radiation conditions. The biological detectors were exposed in vacuum-tightly cases in the European Space Agency (ESA) astrobiological exposure facility attached to the external platform of Zvezda (EXPOSE-R). EXPOSE-R took off to the International Space Station (ISS) in November 2008 and was installed on the External platform of the Russian module Zvezda of the ISS in March 2009. Our goal was to determine the dose-effect relation for the formation of photoproducts (i.e. damage to phage DNA and uracil, respectively). The extraterrestrial solar UV radiation ranges over the whole spectrum from vacuum-UV (λ<200 nm) to UVA (315 nm<λ<400 nm), which causes photolesions (photoproducts) in the nucleic acids/their components either by photoionization or excitation. However, these wavelengths cause not only photolesions but in a wavelength-dependent efficiency the reversion of some photolesions, too. Our biological detectors measured in situ conditions the resultant of both reactions induced by the extraterrestrial UV radiation. From this aspect the role of the photoreversion in the extension of the biological UV dosimetry are discussed.

Human biodistribution and radiation dosimetry of 82Rb.

PubMed

Senthamizhchelvan, Srinivasan; Bravo, Paco E; Esaias, Caroline; Lodge, Martin A; Merrill, Jennifer; Hobbs, Robert F; Sgouros, George; Bengel, Frank M

2010-10-01

Prior estimates of radiation-absorbed doses from (82)Rb, a frequently used PET perfusion tracer, yielded discrepant results. We reevaluated (82)Rb dosimetry using human in vivo biokinetic measurements. Ten healthy volunteers underwent dynamic PET/CT (6 contiguous table positions, each with separate (82)Rb infusion). Source organ volumes of interest were delineated on the CT images and transferred to the PET images to obtain time-integrated activity coefficients. Radiation doses were estimated using OLINDA/EXM 1.0. The highest mean absorbed organ doses (μGy/MBq) were observed for the kidneys (5.81), heart wall (3.86), and lungs (2.96). Mean effective doses were 1.11 ± 0.22 and 1.26 ± 0.20 μSv/MBq using the tissue-weighting factors of the International Commission on Radiological Protection (ICRP), publications 60 and 103, respectively. Our current (82)Rb dosimetry suggests reasonably low radiation exposure. On the basis of this study, a clinical (82)Rb injection of 2 × 1,480 MBq (80 mCi) would result in a mean effective dose of 3.7 mSv using the weighting factors of the ICRP 103-only slightly above the average annual natural background exposure in the United States (3.1 mSv).

Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

NASA Astrophysics Data System (ADS)

Glaser, Adam Kenneth

Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

Ultraviolet laser beam monitor using radiation responsive crystals

DOEpatents

McCann, Michael P.; Chen, Chung H.

1988-01-01

An apparatus and method for monitoring an ultraviolet laser beam includes disposing in the path of an ultraviolet laser beam a substantially transparent crystal that will produce a color pattern in response to ultraviolet radiation. The crystal is exposed to the ultraviolet laser beam and a color pattern is produced within the crystal corresponding to the laser beam intensity distribution therein. The crystal is then exposed to visible light, and the color pattern is observed by means of the visible light to determine the characteristics of the laser beam that passed through crystal. In this manner, a perpendicular cross sectional intensity profile and a longitudinal intensity profile of the ultraviolet laser beam may be determined. The observation of the color pattern may be made with forward or back scattered light and may be made with the naked eye or with optical systems such as microscopes and television cameras.

The effect of prescription eyewear on ocular exposure to ultraviolet radiation.

PubMed Central

Rosenthal, F S; Bakalian, A E; Taylor, H R

1986-01-01

Several studies have suggested that ultraviolet radiation in sunlight may cause cataracts and other eye disease. We evaluated the effect of prescription eyewear in attenuating ocular exposure to ultraviolet radiation (UVR) in the sunlight portions of the ultraviolet spectrum (295-350 nm). Using natural sunlight as the source, the attenuation was measured with two ultraviolet detectors, one sensitive to only UVB (295-315 nm) and one sensitive to both UVA and UVB (295-350 nm). A random sample of spectacles, spectacle lenses, and contact lenses was examined. The average transmission, as measured with either detector, was highest for soft contact lenses, followed by glass spectacle lenses, untinted hard contact lenses, and plastic spectacle lenses. Measurements performed with mannikins wearing spectacles showed that an average of 6.6 per cent of incident radiation reached the eye even when the lenses were covered with black opaque tape. The amount of exposure was increased substantially when the spectacles were moved 0.6 cm away from the forehead. The results show that the protection against ultraviolet exposure provided by prescription eyewear is highly variable and depends largely on its composition, size, and wearing position. PMID:3752323

Solar ultraviolet radiation cataract.

PubMed

Löfgren, Stefan

2017-03-01

Despite being a treatable disease, cataract is still the leading cause for blindness in the world. Solar ultraviolet radiation is epidemiologically linked to cataract development, while animal and in vitro studies prove a causal relationship. However, the pathogenetic pathways for the disease are not fully understood and there is still no perfect model for human age related cataract. This non-comprehensive overview focus on recent developments regarding effects of solar UV radiation wavebands on the lens. A smaller number of fundamental papers are also included to provide a backdrop for the overview. Future studies are expected to further clarify the cellular and subcellular mechanisms for UV radiation-induced cataract and especially the isolated or combined temporal and spatial effects of UVA and UVB in the pathogenesis of human cataract. Regardless of the cause for cataract, there is a need for advances in pharmaceutical or other treatment modalities that do not require surgical replacement of the lens. Copyright © 2016. Published by Elsevier Ltd.

DEMONSTRATION BULLETIN - ULTROX INTERNATIONAL, INC. ULTRAVIOLET RADIATION AND OXIDATION

EPA Science Inventory

The ultraviolet (UV) radiation/oxidation treatment technology developed by Ultrox International uses a combination of UV radiation, ozone, and hydrogen peroxide to oxidize organic compounds in water. Various operating parameters can be adjusted in the Ultrox® system to enhan...

International Standardization of the Clinical Dosimetry of Beta Radiation Brachytherapy Sources: Progress of an ISO Standard

NASA Astrophysics Data System (ADS)

Soares, Christopher

2006-03-01

In 2004 a new work item proposal (NWIP) was accepted by the International Organization for Standardization (ISO) Technical Committee 85 (TC85 -- Nuclear Energy), Subcommittee 2 (Radiation Protection) for the development of a standard for the clinical dosimetry of beta radiation sources used for brachytherapy. To develop this standard, a new Working Group (WG 22 - Ionizing Radiation Dosimetry and Protocols in Medical Applications) was formed. The standard is based on the work of an ad-hoc working group initiated by the Dosimetry task group of the Deutsches Insitiut für Normung (DIN). Initially the work was geared mainly towards the needs of intravascular brachytherapy, but with the decline of this application, more focus has been placed on the challenges of accurate dosimetry for the concave eye plaques used to treat ocular melanoma. Guidance is given for dosimetry formalisms, reference data to be used, calibrations, measurement methods, modeling, uncertainty determinations, treatment planning and reporting, and clinical quality control. The document is currently undergoing review by the ISO member bodies for acceptance as a Committee Draft (CD) with publication of the final standard expected by 2007. There are opportunities for other ISO standards for medical dosimetry within the framework of WG22.

Cloud effects on middle ultraviolet global radiation

NASA Technical Reports Server (NTRS)

Borkowski, J.; Chai, A.-T.; Mo, T.; Green, A. E. O.

1977-01-01

An Eppley radiometer and a Robertson-Berger sunburn meter are employed along with an all-sky camera setup to study cloud effects on middle ultraviolet global radiation at the ground level. Semiempirical equations to allow for cloud effects presented in previous work are compared with the experimental data. The study suggests a means of defining eigenvectors of cloud patterns and correlating them with the radiation at the ground level.

Computer Aided Dosimetry and Verification of Exposure to Radiation

NASA Astrophysics Data System (ADS)

Waller, Edward; Stodilka, Robert Z.; Leach, Karen E.; Lalonde, Louise

2002-06-01

In the timeframe following the September 11th attacks on the United States, increased emphasis has been placed on Chemical, Biological, Radiological and Nuclear (CBRN) preparedness. Of prime importance is rapid field assessment of potential radiation exposure to Canadian Forces field personnel. This work set up a framework for generating an 'expert' computer system for aiding and assisting field personnel in determining the extent of radiation insult to military personnel. Data was gathered by review of the available literature, discussions with medical and health physics personnel having hands-on experience dealing with radiation accident victims, and from experience of the principal investigator. Flow charts and generic data fusion algorithms were developed. Relationships between known exposure parameters, patient interview and history, clinical symptoms, clinical work-ups, physical dosimetry, biological dosimetry, and dose reconstruction as critical data indicators were investigated. The data obtained was examined in terms of information theory. A main goal was to determine how best to generate an adaptive model (i.e. when more data becomes available, how is the prediction improved). Consideration was given to determination of predictive algorithms for health outcome. In addition. the concept of coding an expert medical treatment advisor system was developed (U)

Vacuum and ultraviolet radiation effects on binders and pigments for spacecraft thermal control coatings

NASA Technical Reports Server (NTRS)

Progar, D. J.; Wade, W. R.

1971-01-01

An evaluation of several silicone resin binders and powdered inorganic pigments for potential use in spacecraft thermal-control paint formulations is presented. The pigments were selected on the basis of a hypothesis relating the heat of formation of a compound to the compound's resistance to ultra-radiation-induced degradation. Reflectance measurements were made in situ to determine degradation rates due to ultraviolet radiation. The tested polydimethylsiloxane resins were not significantly affected by long exposures to ultraviolet radiation. All the pigments, which were dispersed in a polydimethylsiloxane resin, were degraded by ultraviolet radiation as determined by an increase of solar absorptance. For the materials evaluated in this study, no evidence was found to indicate that pigments with high heats of formation were resistant to ultraviolet degradation.

Thin film tritium dosimetry

DOEpatents

Moran, Paul R.

1976-01-01

The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

Solar ultraviolet radiation in a changing climate

EPA Science Inventory

The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

PREFACE: 7th International Conference on 3D Radiation Dosimetry (IC3DDose)

NASA Astrophysics Data System (ADS)

Thwaites, David; Baldock, Clive

2013-06-01

IC3DDose 2013, the 7th International Conference on 3D Radiation Dosimetry held in Sydney, Australia from 4-8 November 2012, grew out of the DosGel series, which began as DosGel99, the 1st International Workshop on Radiation Therapy Gel Dosimetry in Lexington, Kentucky. Since 1999 subsequent DoSGel conferences were held in Brisbane, Australia (2001), Ghent, Belgium (2004), Sherbrooke, Canada (2006) and Crete, Greece (2008). In 2010 the conference was held on Hilton Head Island, South Carolina and underwent a name-change to IC3DDose. The aim of the first workshop was to bring together individuals, both researchers and users, with an interest in 3D radiation dosimetry techniques, with a mix of presentations from basic science to clinical applications, which has remained an objective for all of the meetings. One rationale of DosGel99 was stated as supporting the increasing clinical implementation of gel dosimetry, as the technique appeared, at that time, to be leaving the laboratories of gel dosimetry enthusiasts and entering clinical practice. Clearly by labelling the first workshop as the 1st, there was a vision of a continuing series, which has been fulfilled. On the other hand, the expectation of widespread clinical use of gel dosimetry has perhaps not been what was hoped for and anticipated. Nevertheless the rapidly increasing demand for advanced high-precision 3D radiotherapy technology and techniques has continued apace. The need for practical and accurate 3D dosimetry methods for development and quality assurance has only increased. By the 6th meeting, held in South Carolina in 2010, the Conference Scientific Committee recognised the wider developments in 3D systems and methods and decided to widen the scope, whilst keeping the same span from basic science to applications. This was signalled by a change of name from 'Dosgel' to 'IC3DDose', a name that has continued to this latest conference. The conference objectives were: to enhance the quality and accuracy of

TH-A-204-01: Part I - Key Data for Ionizing-Radiation Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seltzer, S.

The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding “fundamental” data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee’s work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair inmore » dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams. The changes in reference dosimetry that would result from adoption of the ICRU recommendations are of the order of 0.5% to 1%, an effect that will not impact clinical dose delivery but will be detectable in the clinical setting. This session will also outline how worldwide metrology is coordinated through the Convention of the Meter and therefore how the international dosimetry community will proceed with adopting these recommendations so that uniformity from country to country in reference dosimetry is maintained. Timelines and communications methods will also be discussed to ensure that users, such as clinical medical physicists, are not surprised when their chamber’s calibration coefficient apparently changes. Learning Objectives: Understand the background for the ICRU committee’s work on key dosimetry data. Understand the proposed changes to key data and the impacts on reference dosimetry. Understand the methodology and

Assessment of the impact of increased solar ultraviolet radiation upon marine ecosystems

NASA Technical Reports Server (NTRS)

Worrest, R. C.; Vandyke, H.

1978-01-01

Reduction of the earth's ozone layer, with a resultant increase in transmission of solar ultraviolet radiation in the 290 to 320nm waveband (UV-B), via space shuttle operations through the stratosphere is considered. It is shown that simulated solar ultraviolet radiation can, under experimental conditions, detrimentally affect the marine organisms that form the base of the food web of oceanic and estuarine ecosystems. Whether a small increase in biologically harmful ultraviolet radiation might overwhelm these mechanisms and produce changes that will have damaging consequences to the biosphere is discussed. The potential for irreversible damage to the productivity, structure and/or functioning of a model estuarine ecosystem by increased UV-B radiation and whether these ecosystems are highly stable or amenable to adaptive change is studied. Data are provided to assess the potential impact upon marine ecosystems if space shuttle operations contribute to a reduction of the stratospheric ozone layer and the sensitivity of key community components to increased UV-B radiation is examined.

Establishing a ultraviolet radiation observational network and enhancing the study on ultraviolet radiation

NASA Astrophysics Data System (ADS)

Bai, Jianhui; Wang, Gengchen

2003-09-01

On the basis of analyzing observational data on solar radiation, meteorological parameters, and total ozone amount for the period of January 1990 to December 1991 in the Beijing area, an empirical calculation method for ultraviolet radiation (UV) in clear sky is obtained. The results show that the calculated values agree well with the observed, with maximum relative bias of 6.2% and mean relative bias for 24 months of 1.9%. Good results are also obtained when this method is applied in Guangzhou and Mohe districts. The long-term variation of UV radiation in clear sky over the Beijing area from 1979 to 1998 is calculated, and the UV variation trends and causes are discussed: direct and indirect UV energy absorption by increasing pollutants in the troposphere may have caused the UV decrease in clear sky in the last 20 years. With the enhancement of people’s quality of life and awareness of health, it will be valuable and practical to provid UV forecasts for typical cities and rural areas. So, we should develop and enhance UV study in systematic monitoring, forecasting, and developing a good and feasible method for UV radiation reporting in China, especially for big cities.

Fostering a culture of interprofessional education for radiation therapy and medical dosimetry students

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lavender, Charlotte, E-mail: charlavender@gmail.com; Miller, Seth; Church, Jessica

A less-studied aspect of radiation therapy and medical dosimetry education is experiential learning through attendance at interprofessional conferences. University of North Carolina radiation therapy and medical dosimetry students regularly attended morning conferences and daily pretreatment peer review, including approximately 145 hours of direct interaction with medical attending physicians and residents, medical physicists, and other faculty. We herein assessed the effect of their participation in these interprofessional conferences on knowledge and communication. The students who graduated from our radiation therapy and medical dosimetry programs who were exposed to the interprofessional education initiative were compared with those who graduated in the previousmore » years. The groups were compared with regard to their knowledge (as assessed by grades on end-of-training examinations) and team communication (assessed via survey). The results for the 2 groups were compared via exact tests. There was a trend for the examination scores for the 2012 cohort to be higher than for the 2007 to 2011 groups. Survey results suggested that students who attended the interprofessional education sessions were more comfortable speaking with attending physicians, residents, physicists, and faculty compared with earlier students who did not attend these educational sessions. Interprofessional education, particularly vertical integration, appears to provide an enhanced educational experience both in regard to knowledge (per the examination scores) and in building a sense of communication (via the survey results). Integration of interprofessional education into radiation therapy and medical dosimetry educational programs may represent an opportunity to enrich the learning experience in multiple ways and merits further study.« less

Anthropomorphic Phantom Radiation Dosimetry at the NATO Standard Reference Point at Aberdeen Proving Ground,

DTIC Science & Technology

1987-04-01

and would still be well under 10(C. .% % p., I V a- E p - -12 - IABLE 8 (a) TLD results for phantom dosimetry - all values shown are measured charge...SAI. Conclusions The current DREO dosimetry system-consisting of bubble, CR39 and TLD dosimeters - has proven capable of producing meaningful results at...MC FILE CoPy’ Defence nationale 00 ANTHROPOMORPHIC PHANTOM RADIATION DOSIMETRY AT THE NATO STANDARD OREFERENCE POINT AT ABERDEEN PROVING GROUND by T

A practical three-dimensional dosimetry system for radiation therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo Pengyi; Adamovics, John; Oldham, Mark

2006-10-15

There is a pressing need for a practical three-dimensional (3D) dosimetry system, convenient for clinical use, and with the accuracy and resolution to enable comprehensive verification of the complex dose distributions typical of modern radiation therapy. Here we introduce a dosimetry system that can achieve this challenge, consisting of a radiochromic dosimeter (PRESAGE trade mark sign ) and a commercial optical computed tomography (CT) scanning system (OCTOPUS trade mark sign ). PRESAGE trade mark sign is a transparent material with compelling properties for dosimetry, including insensitivity of the dose response to atmospheric exposure, a solid texture negating the need formore » an external container (reducing edge effects), and amenability to accurate optical CT scanning due to radiochromic optical contrast as opposed to light-scattering contrast. An evaluation of the performance and viability of the PRESAGE trade mark sign /OCTOPUS, combination for routine clinical 3D dosimetry is presented. The performance of the two components (scanner and dosimeter) was investigated separately prior to full system test. The optical CT scanner has a spatial resolution of {<=}1 mm, geometric accuracy within 1 mm, and high reconstruction linearity (with a R{sup 2} value of 0.9979 and a standard error of estimation of {approx}1%) relative to independent measurement. The overall performance of the PRESAGE trade mark sign /OCTOPUS system was evaluated with respect to a simple known 3D dose distribution, by comparison with GAFCHROMIC[reg] EBT film and the calculated dose from a commissioned planning system. The 'measured' dose distribution in a cylindrical PRESAGE trade mark sign dosimeter (16 cm diameter and 11 cm height) was determined by optical-CT, using a filtered backprojection reconstruction algorithm. A three-way Gamma map comparison (4% dose difference and 4 mm distance to agreement), between the PRESAGE trade mark sign , EBT and calculated dose distributions, showed

Self-expanding stent effects on radiation dosimetry in esophageal cancer.

PubMed

Francis, Samual R; Anker, Christopher J; Wang, Brian; Williams, Greg V; Cox, Kristen; Adler, Douglas G; Shrieve, Dennis C; Salter, Bill J

2013-07-08

It is the purpose of this study to evaluate how self-expanding stents (SESs) affect esophageal cancer radiation planning target volumes (PTVs) and dose delivered to surrounding organs at risk (OARs). Ten patients were evaluated, for whom a SES was placed before radiation. A computed tomography (CT) scan obtained before stent placement was fused to the post-stent CT simulation scan. Three methods were used to represent pre-stent PTVs: 1) image fusion (IF), 2) volume approximation (VA), and 3) diameter approximation (DA). PTVs and OARs were contoured per RTOG 1010 protocol using Eclipse Treatment Planning software. Post-stent dosimetry for each patient was compared to approximated pre-stent dosimetry. For each of the three pre-stent approximations (IF, VA, and DA), the mean lung and liver doses and the estimated percentages of lung volumes receiving 5 Gy, 10 Gy, 20 Gy, and 30 Gy, and heart volumes receiving 40 Gy were significantly lower (p-values < 0.02) than those estimated in the post-stent treatment plans. The lung V5, lung V10, and heart V40 constraints were achieved more often using our pre-stent approximations. Esophageal SES placement increases the dose delivered to the lungs, heart, and liver. This may have clinical importance, especially when the dose-volume constraints are near the recommended thresholds, as was the case for lung V5, lung V10, and heart V40. While stents have established benefits for treating patients with significant dysphagia, physicians considering stent placement and radiation therapy must realize the effects stents can have on the dosimetry.

Topical Review: Polymer gel dosimetry

PubMed Central

Baldock, C; De Deene, Y; Doran, S; Ibbott, G; Jirasek, A; Lepage, M; McAuley, K B; Oldham, M; Schreiner, L J

2010-01-01

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. PMID:20150687

Micrometer-resolved film dosimetry using a microscope in microbeam radiation therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartzsch, Stefan, E-mail: stefan.bartzsch@icr.ac.uk; Oelfke, Uwe; Lott, Johanna

2015-07-15

Purpose: Microbeam radiation therapy (MRT) is a still preclinical tumor therapy approach that uses arrays of a few tens of micrometer wide parallel beams separated by a few 100 μm. The production, measurement, and planning of such radiation fields are a challenge up to now. Here, the authors investigate the feasibility of radiochromic film dosimetry in combination with a microscopic readout as a tool to validate peak and valley doses in MRT, which is an important requirement for a future clinical application of the therapy. Methods: Gafchromic{sup ®} HD-810 and HD-V2 films are exposed to MRT fields at the biomedicalmore » beamline ID17 of the European Synchrotron Radiation Facility (ESRF) and are afterward scanned with a microscope. The measured dose is compared with Monte Carlo calculations. Image analysis tools and film handling protocols are developed that allow accurate and reproducible dosimetry. The performance of HD-810 and HD-V2 films is compared and a detailed analysis of the resolution, noise, and energy dependence is carried out. Measurement uncertainties are identified and analyzed. Results: The dose was measured with a resolution of 5 × 1000 μm{sup 2} and an accuracy of 5% in the peak and between 10% and 15% in the valley region. As main causes for dosimetry uncertainties, statistical noise, film inhomogeneities, and calibration errors were identified. Calibration errors strongly increase at low doses and exceeded 3% for doses below 50 and 70 Gy for HD-V2 and HD-810 films, respectively. While the grain size of both film types is approximately 2 μm, the statistical noise in HD-V2 is much higher than in HD-810 films. However, HD-810 films show a higher energy dependence at low photon energies. Conclusions: Both film types are appropriate for dosimetry in MRT and the microscope is superior to the microdensitometer used before at the ESRF with respect to resolution and reproducibility. However, a very careful analysis of the image data is required

Examining Dermatologist Use and Opinions of Ultraviolet Radiation for Cosmetic and Medical Purposes.

PubMed

Sampson, Blake P; Secrest, Aaron M; Hansen, Christopher B; Geller, Alan C

2018-02-01

BACKGROUND: The commercial tanning industry has opposed efforts to educate the public on the risks of tanning as well as attempts to restrict minors' access to tanning services. Despite a paucity of supporting literature, statements from the tanning industry claiming that dermatologists routinely use in-office phototherapy for cosmetic treatments and refer patients to tanning salons have successfully derailed and defeated legislation in many states. OBJECTIVE: This study aims to evaluate dermatologist referrals for ultraviolet radiation for cosmetic and medical purposes via tanning beds or phototherapy, as well as their opinions on tanning, legislation, and ultraviolet radiation counseling practices. DESIGN: The study was conducted using a 10-question anonymous survey. SETTING: The participants were surveyed during meetings of three regional dermatologic societies. PARTICIPANTS: One hundred and fifty-two dermatologists attending society meetings participated in the study. MEASURES: The authors measured physician referrals, opinions, and recommendations regarding ultraviolet exposure. RESULTS: Zero physicians (0/152) recommended tanning salons for cosmetic reasons. These 152 dermatologists referred 458 (417 adult, 41 pediatric) out of an estimated 809,369 patients (0.057%) to tanning salons for medical treatment. Of these physicians, 76 out of 152 and 15 out of 152 reported referring at least one adult or one pediatric patient, respectively, within the last year. All respondents supported ultraviolet tanning legislation and discouraged cosmetic tanning. CONCLUSION: These findings directly contradict the assertion that dermatologists use ultraviolet radiation for cosmetic purposes or routinely refer patients to tanning salons. This study underscores the complex nature of ultraviolet radiation, as dermatologists infrequently utilize ultraviolet radiation for medical purposes and unanimously support restrictive legislation. In addition, these dermatologists counsel

Examining Dermatologist Use and Opinions of Ultraviolet Radiation for Cosmetic and Medical Purposes

PubMed Central

Secrest, Aaron M.; Hansen, Christopher B.; Geller, Alan C.

2018-01-01

BACKGROUND: The commercial tanning industry has opposed efforts to educate the public on the risks of tanning as well as attempts to restrict minors’ access to tanning services. Despite a paucity of supporting literature, statements from the tanning industry claiming that dermatologists routinely use in-office phototherapy for cosmetic treatments and refer patients to tanning salons have successfully derailed and defeated legislation in many states. OBJECTIVE: This study aims to evaluate dermatologist referrals for ultraviolet radiation for cosmetic and medical purposes via tanning beds or phototherapy, as well as their opinions on tanning, legislation, and ultraviolet radiation counseling practices. DESIGN: The study was conducted using a 10-question anonymous survey. SETTING: The participants were surveyed during meetings of three regional dermatologic societies. PARTICIPANTS: One hundred and fifty-two dermatologists attending society meetings participated in the study. MEASURES: The authors measured physician referrals, opinions, and recommendations regarding ultraviolet exposure. RESULTS: Zero physicians (0/152) recommended tanning salons for cosmetic reasons. These 152 dermatologists referred 458 (417 adult, 41 pediatric) out of an estimated 809,369 patients (0.057%) to tanning salons for medical treatment. Of these physicians, 76 out of 152 and 15 out of 152 reported referring at least one adult or one pediatric patient, respectively, within the last year. All respondents supported ultraviolet tanning legislation and discouraged cosmetic tanning. CONCLUSION: These findings directly contradict the assertion that dermatologists use ultraviolet radiation for cosmetic purposes or routinely refer patients to tanning salons. This study underscores the complex nature of ultraviolet radiation, as dermatologists infrequently utilize ultraviolet radiation for medical purposes and unanimously support restrictive legislation. In addition, these dermatologists counsel

Fostering a culture of interprofessional education for radiation therapy and medical dosimetry students.

PubMed

Lavender, Charlotte; Miller, Seth; Church, Jessica; Chen, Ronald C; Muresan, Petronella A; Adams, Robert D

2014-01-01

A less-studied aspect of radiation therapy and medical dosimetry education is experiential learning through attendance at interprofessional conferences. University of North Carolina radiation therapy and medical dosimetry students regularly attended morning conferences and daily pretreatment peer review, including approximately 145 hours of direct interaction with medical attending physicians and residents, medical physicists, and other faculty. We herein assessed the effect of their participation in these interprofessional conferences on knowledge and communication. The students who graduated from our radiation therapy and medical dosimetry programs who were exposed to the interprofessional education initiative were compared with those who graduated in the previous years. The groups were compared with regard to their knowledge (as assessed by grades on end-of-training examinations) and team communication (assessed via survey). The results for the 2 groups were compared via exact tests. There was a trend for the examination scores for the 2012 cohort to be higher than for the 2007 to 2011 groups. Survey results suggested that students who attended the interprofessional education sessions were more comfortable speaking with attending physicians, residents, physicists, and faculty compared with earlier students who did not attend these educational sessions. Interprofessional education, particularly vertical integration, appears to provide an enhanced educational experience both in regard to knowledge (per the examination scores) and in building a sense of communication (via the survey results). Integration of interprofessional education into radiation therapy and medical dosimetry educational programs may represent an opportunity to enrich the learning experience in multiple ways and merits further study. © 2013 Published by American Association of Medical Dosimetrists on behalf of American Association of Medical Dosimetrists.

SU-E-I-107: Suitability of Various Radiation Detectors Used in Radiation Therapy for X-Ray Dosimetry in Computed Tomography.

PubMed

Liebmann, M; Poppe, B; von Boetticher, H

2012-06-01

Assessment of suitability for X-ray dosimetry in computed tomography of various ionization chambers, diodes and two-dimensional detector arrays primarily used in radiation therapy. An Oldelft X-ray simulation unit was used to irradiate PTW 60008, 60012 dosimetry diodes, PTW 23332, 31013, 31010, 31006 axial symmetrical ionization chambers, PTW 23343, 34001 plane parallel ionization chambers and PTW Starcheck and 2D-Array seven29 as well as a prototype Farmer chamber with a copper wall. Peak potential was varied from 50 kV up to 125 kV and beam qualities were quantified through half-value-layer measurements. Energy response was investigated free in air as well as in 2 cm depth in a solid water phantom and refers to a manufacturer calibrated PTW 60004 diode for kV-dosimetry. The thimble ionization chambers PTW 31010, 31013, the uncapsuled diode PTW 60012 and the PTW 2D-Array seven29 exhibit an energy response deviation in the investigated energy region of approximately 10% or lower thus proving good usability in X-ray dosimetry if higher spatial resolution is needed or rotational irradiations occur. It could be shown that in radiation therapy routinely used detectors are usable in a much lower energy region. The rotational symmetry is of advantage in computed tomography dosimetry and enables dose profile as well as point dose measurements in a suitable phantom for estimation of organ doses. Additional the PTW 2D-Array seven29 can give a quick overview of radiation fields in non-rotating tasks. © 2012 American Association of Physicists in Medicine.

Some Thoughts on Teaching about Ultraviolet Radiation

ERIC Educational Resources Information Center

Thumm, Walter

1975-01-01

Describes the major obstacles in the study of ultraviolet radiation (UV). Presents the beneficial aspects of UV such as vitamin O production, sterilization, clinical treatment of diseases and wounds, and the marking of patients for radiotherapy. Warns of the dangers of UV exposure such as skin cancer and early aging. (GS)

Workshop report on atomic bomb dosimetry-residual radiation exposure: recent research and suggestions for future studies.

PubMed

Kerr, George D; Egbert, Stephen D; Al-Nabulsi, Isaf; Beck, Harold L; Cullings, Harry M; Endo, Satoru; Hoshi, Masaharu; Imanaka, Tetsuji; Kaul, Dean C; Maruyama, Satoshi; Reeves, Glen I; Ruehm, Werner; Sakaguchi, Aya; Simon, Steven L; Spriggs, Gregory D; Stram, Daniel O; Tonda, Tetsuji; Weiss, Joseph F; Weitz, Ronald L; Young, Robert W

2013-08-01

There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewed at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report.

Workshop Report on Atomic Bomb Dosimetry--Residual Radiation Exposure: Recent Research and Suggestions for Future Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2013-06-06

There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewedmore » at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report.« less

Ultraviolet Radiation Dose National Standard of México

NASA Astrophysics Data System (ADS)

Cardoso, R.; Rosas, E.

2006-09-01

We present the Ultraviolet (UV) Radiation Dose National Standard for México. The establishment of this measurement reference at Centro Nacional de Metrología (CENAM) eliminates the need of contacting foreign suppliers in the search for traceability towards the SI units when calibrating instruments at 365 nm. Further more, the UV Radiation Dose National Standard constitutes a highly accurate and reliable source for the UV radiation dose measurements performed in medical and cosmetic treatments as in the the food and pharmaceutics disinfection processes, among other.

Quality management system in the CIEMAT Radiation Dosimetry Service.

PubMed

Martín, R; Navarro, T; Romero, A M; López, M A

2011-03-01

This paper describes the activities realised by the CIEMAT Radiation Dosimetry Service (SDR) for the implementation of a quality management system (QMS) in order to achieve compliance with the requirements of ISO/IEC 17025 and to apply for the accreditation for testing measurements of radiation dose. SDR has decided the accreditation of the service as a whole and not for each of its component laboratories. This makes it necessary to design a QMS common to all, thus ensuring alignment and compliance with standard requirements, and simplifying routine works as possible.

Ultraviolet Radiation: Human Exposure and Health Risks.

ERIC Educational Resources Information Center

Tenkate, Thomas D.

1998-01-01

Provides an overview of human exposure to ultraviolet radiation and associated health effects as well as risk estimates for acute and chronic conditions resulting from such exposure. Demonstrates substantial reductions in health risk that can be achieved through preventive actions. Also includes a risk assessment model for skin cancer. Contains 36…

Progress in high-dose radiation dosimetry. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettinger, K.V.; Nam, J.W.; McLaughlin, W.L.

1981-01-01

The last decade has witnessed a deluge of new high-dose dosimetry techniques and expended applications of methods developed earlier. Many of the principal systems are calibrated by means of calorimetry, although production of heat is not always the final radiation effect of interest. Requirements for a stable and reliable transfer dose meters have led to further developments of several important high-dose systems: thermoluminescent materials, radiochromic dyes, ceric-cerous solutions analyzed by high-frequency oscillometry. A number of other prospective dosimeters are also treated in this review. In addition, an IAEA program of high-dose intercomparison and standardization for industrial radiation processing is described.

Progress in high-dose radiation dosimetry. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettinger, K.V.; Nam, J.W.; McLaughlin, W.L.

1981-01-01

The last decade has witnessed a deluge of new high-dose dosimetry techniques and expended applications of methods developed earlier. Many of the principal systems are calibrated by means of calorimetry, although production of heat is not always the final radiation effect of interest. Requirements for a stable and reliable transfer dose meters have led to further developments of several important high-dose systems: thermoluminescent materials, radiochromic dyes, ceric-cerous solutions analyzed by high-frequency oscillometry. A number of other prospective dosimeters also treated in this review. In addition, an IAEA programme of high-dose intercomparison and standardization for industrial radiation processing is described.

ASSESSMENT OF THE RISK OF SOLAR ULTRAVIOLET RADIATION TO AMPHIBIANS. II: IN SITU CHARACTERIZATION OF SOLAR ULTRAVIOLET RADIATION IN AMPHIBIAN HABITATS

EPA Science Inventory

Ultraviolet B (UVB) radiation has been hypothesized as a potential cause of amphibian population declines and increased incidences of malformations. Realistic studies documenting UV irradiance or dose have rarely been conducted in wetlands used by amphibians. We demonstrate that ...

Self‐expanding stent effects on radiation dosimetry in esophageal cancer

PubMed Central

Francis, Samual R.; Wang, Brian; Williams, Greg V.; Cox, Kristen; Adler, Douglas G.; Shrieve, Dennis C.; Salter, Bill J.

2013-01-01

It is the purpose of this study to evaluate how self‐expanding stents (SESs) affect esophageal cancer radiation planning target volumes (PTVs) and dose delivered to surrounding organs at risk (OARs). Ten patients were evaluated, for whom a SES was placed before radiation. A computed tomography (CT) scan obtained before stent placement was fused to the post‐stent CT simulation scan. Three methods were used to represent pre‐stent PTVs: 1) image fusion (IF), 2) volume approximation (VA), and 3) diameter approximation (DA). PTVs and OARs were contoured per RTOG 1010 protocol using Eclipse Treatment Planning software. Post‐stent dosimetry for each patient was compared to approximated pre‐stent dosimetry. For each of the three pre‐stent approximations (IF, VA, and DA), the mean lung and liver doses and the estimated percentages of lung volumes receiving 5 Gy, 10 Gy, 20 Gy, and 30 Gy, and heart volumes receiving 40 Gy were significantly lower (p‐values <0.02) than those estimated in the post‐stent treatment plans. The lung V5, lung V10, and heart V40 constraints were achieved more often using our pre‐stent approximations. Esophageal SES placement increases the dose delivered to the lungs, heart, and liver. This may have clinical importance, especially when the dose‐volume constraints are near the recommended thresholds, as was the case for lung V5, lung V10, and heart V40. While stents have established benefits for treating patients with significant dysphagia, physicians considering stent placement and radiation therapy must realize the effects stents can have on the dosimetry. PACS number: 87.55.dk PMID:23835387

Mathematics in medicine: tumor detection, radiation dosimetry, and simulation in psychotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bellman, R.; Kashef, B.; Smith, C.P.

1975-05-01

Work done in the application of mathematics to medicine over the last 20 years is briefly reviewed. Scan-rescan processes, radiation dosimetry, and medical interviewing are discussed. The first uses dynamic programming, the second invariant imbedding, and the third simulation. (ACR)

Effects of ultraviolet radiation, visible light, and infrared radiation on erythema and pigmentation: a review.

PubMed

Sklar, Lindsay R; Almutawa, Fahad; Lim, Henry W; Hamzavi, Iltefat

2013-01-01

The effects of ultraviolet radiation, visible light, and infrared radiation on cutaneous erythema, immediate pigment darkening, persistent pigment darkening, and delayed tanning are affected by a variety of factors. Some of these factors include the depth of cutaneous penetration of the specific wavelength, the individual skin type, and the absorption spectra of the different chromophores in the skin. UVB is an effective spectrum to induce erythema, which is followed by delayed tanning. UVA induces immediate pigment darkening, persistent pigment darkening, and delayed tanning. At high doses, UVA (primarily UVA2) can also induce erythema in individuals with skin types I-II. Visible light has been shown to induce erythema and a tanning response in dark skin, but not in fair skinned individuals. Infrared radiation produces erythema, which is probably a thermal effect. In this article we reviewed the available literature on the effects of ultraviolet radiation, visible light, and infrared radiation on the skin in regards to erythema and pigmentation. Much remains to be learned on the cutaneous effects of visible light and infrared radiation.

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T-7 bacteriophage

NASA Technical Reports Server (NTRS)

Spizizen, J.; Isherwood, J. E.; Taylor, G. R.

1975-01-01

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59)F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T-7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T-7 bacteriophage was observed after exposure to solar ultraviolet radiation.

ULTRAVIOLET RADIATION AND ARSENIC INTERACTIONS: EFFECTS ON CLADOCERANS

EPA Science Inventory

The effects of arsenic and ultraviolet radiation (UV) on cladocerans have been examined separately, however the interaction of these two stresses has not been explored. Potential synergism between these two stresses is possible as arsenic is known to inhibit repair of UV induced ...

Key issues of ultraviolet radiation of OH at high altitudes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuhuai; Wan, Tian; Jiang, Jianzheng

2014-12-09

Ultraviolet (UV) emissions radiated by hydroxyl (OH) is one of the fundamental elements in the prediction of radiation signature of high-altitude and high-speed vehicle. In this work, the OH A{sup 2}Σ{sup +}→X{sup 2}Π ultraviolet emission band behind the bow shock is computed under the experimental condition of the second bow-shock ultraviolet flight (BSUV-2). Four related key issues are discussed, namely, the source of hydrogen element in the high-altitude atmosphere, the formation mechanism of OH species, efficient computational algorithm of trace species in rarefied flows, and accurate calculation of OH emission spectra. Firstly, by analyzing the typical atmospheric model, the verticalmore » distributions of the number densities of different species containing hydrogen element are given. According to the different dominating species containing hydrogen element, the atmosphere is divided into three zones, and the formation mechanism of OH species is analyzed in the different zones. The direct simulation Monte Carlo (DSMC) method and the Navier-Stokes equations are employed to compute the number densities of the different OH electronically and vibrationally excited states. Different to the previous work, the trace species separation (TSS) algorithm is applied twice in order to accurately calculate the densities of OH species and its excited states. Using a non-equilibrium radiation model, the OH ultraviolet emission spectra and intensity at different altitudes are computed, and good agreement is obtained with the flight measured data.« less

Key issues of ultraviolet radiation of OH at high altitudes

NASA Astrophysics Data System (ADS)

Zhang, Yuhuai; Wan, Tian; Jiang, Jianzheng; Fan, Jing

2014-12-01

Ultraviolet (UV) emissions radiated by hydroxyl (OH) is one of the fundamental elements in the prediction of radiation signature of high-altitude and high-speed vehicle. In this work, the OH A2Σ+→ X2Π ultraviolet emission band behind the bow shock is computed under the experimental condition of the second bow-shock ultraviolet flight (BSUV-2). Four related key issues are discussed, namely, the source of hydrogen element in the high-altitude atmosphere, the formation mechanism of OH species, efficient computational algorithm of trace species in rarefied flows, and accurate calculation of OH emission spectra. Firstly, by analyzing the typical atmospheric model, the vertical distributions of the number densities of different species containing hydrogen element are given. According to the different dominating species containing hydrogen element, the atmosphere is divided into three zones, and the formation mechanism of OH species is analyzed in the different zones. The direct simulation Monte Carlo (DSMC) method and the Navier-Stokes equations are employed to compute the number densities of the different OH electronically and vibrationally excited states. Different to the previous work, the trace species separation (TSS) algorithm is applied twice in order to accurately calculate the densities of OH species and its excited states. Using a non-equilibrium radiation model, the OH ultraviolet emission spectra and intensity at different altitudes are computed, and good agreement is obtained with the flight measured data.

The radiation dosimetry of intrathecally administered radionuclides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stabin, M.G.; Evans, J.F.

The radiation dose to the spine, spinal cord, marrow, and other organs of the body from intrathecal administration of several radiopharmaceuticals was studied. Anatomic models were developed for the spine, spinal cerebrospinal fluid (CSF), spinal cord, spinal skeleton, cranial skeleton, and cranial CSF. A kinetic model for the transport of CSF was used to determine residence times in the CSF; material leaving the CSF was thereafter assumed to enter the bloodstream and follow the kinetics of the radiopharmaceutical as if intravenously administered. The radiation transport codes MCNP and ALGAMP were used to model the electron and photon transport and energymore » deposition. The dosimetry of Tc-99m DTPA and HSA, In-111 DTPA, I-131 HSA, and Yb-169 DTPA was studied. Radiation dose profiles for the spinal cord and marrow in the spine were developed and average doses to all other organs were estimated, including dose distributions within the bone and marrow.« less

Photosynthetically active radiation (PAR) x ultraviolet radiation (UV) interact to initiate solar injury in apple

USDA-ARS?s Scientific Manuscript database

Sunburn or solar injury (SI) in apple is associated with high temperature, high visible light and ultraviolet radiation (UV). Fruit surface temperature (FST) thresholds for SI related disorders have been developed but there are no thresholds established for solar radiation. The objectives of the s...

DELAY OF CLEAVAGE OF THE ARBACIA EGG BY ULTRAVIOLET RADIATION

PubMed Central

Blum, Harold F.; Price, Judith P.

1950-01-01

While our data do not permit us to state the exact locus or mode of action of ultraviolet radiation in the Arbacia egg, certain general conclusions may be reached. The amount of delay of cleavage of these eggs is determined by two principal factors: (1) The extent of an effect, resulting from photochemical action induced by ultraviolet radiation, which is reversible in a biological sense, the reversibility not being directly dependent upon the process of cell division. (2) The sensitivity of the cell division process to the effects of the ultraviolet-induced photochemical reaction. This factor varies with the stage of cell division, the cell being insensitive during a period corresponding to most of mitosis. It seems likely that these findings may apply to cell division in general, but, since the quantitative relationships observed must, in this case, reflect the integration of two semi-independent factors, the over-all picture may appear quite different for different kinds of cells. PMID:15410486

Small Radiation Beam Dosimetry for Radiosurgery of Trigeminal Neuralgia: One Case Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Garduno, O. A.; Larraga-Gutierrez, J. M.; Unidad de Radioneurocirugia, Instituto Nacional de Neurologia y Neurocirugia. Insurgentes Sur 3677, Col. La Fama, C. P. 14269, Tlalpan, Mexico, D. F.

2008-08-11

The use of small radiation beams for trigeminal neuralgia (TN) treatment requires high precision and accuracy in dose distribution calculations and delivery. Special attention must be kept on the type of detector to be used. In this work, the use of GafChromic EBT registered radiochromic and X-OMAT V2 radiographic films for small radiation beam characterization is reported. The dosimetric information provided by the films (total output factors, tissue maximum ratios and off axis ratios) is compared against measurements with a shielded solid state (diode) reference detector. The film dosimetry was used for dose distribution calculations for the treatment of trigeminalmore » neuralgia radiosurgery. Comparison of the isodose curves shows that the dosimetry produced with the X-OMAT radiographic film overestimates the dose distributions in the penumbra region.« less

Comprehensive Review of Ultraviolet Radiation and the Current Status on Sunscreens

PubMed Central

Moon, Summer; Armstrong, Frank

2012-01-01

In the past, manufacturers’ labeling of sunscreen varied greatly, confusing the consumers regarding efficacy and the appropriate photoprotection provided by their products. Therefore, in June 2011, the United States Food and Drug Administration issued new guidelines for sunscreen labeling. Sunscreen products are over-the-counter drugs; therefore, they are regulated by the United States Food and Drug Administration to determine safety, efficacy, and labeling. This article discusses ultraviolet radiation and the positive and negative effects of ultraviolet radiation, provides a review of sunscreens, and discusses the new United States Food and Drug Administration regulations for sunscreens. PMID:23050030

How feasible is remote 3D dosimetry for MR guided Radiation Therapy (MRgRT)?

NASA Astrophysics Data System (ADS)

Mein, S.; Rankine, L.; Miles, D.; Juang, T.; Cai, B.; Curcuru, A.; Mutic, S.; Fenoli, J.; Adamovics, J.; Li, H.; Oldham, M.

2017-05-01

To develop and apply a remote dosimetry protocol with PRESAGE® radiochromic plastic and optical-CT readout in the validation of MRI guided radiation therapy (MRgRT) treatments (MRIdian® by ViewRay®). Through multi-institutional collaboration we performed PRESAGE® dosimetry studies in 4ml cuvettes to investigate dose-response linearity, MR-compatibility, and energy-independence. An open calibration field and symmetrical 3-field plans were delivered to 10cm diameter PRESAGE® to examine percent depth dose and response uniformity under a magnetic field. Evidence of non-linear dose response led to a large volume PRESAGE® study where small corrections were developed for temporally- and spatially-dependent behaviors observed between irradiation and delayed readout. TG-119 plans were created in the MRIdian® TPS and then delivered to 14.5cm 2kg PRESAGE® dosimeters. Through the domestic investigation of an off-site MRgRT system, a refined 3D remote dosimetry protocol is presented capable of validation of advanced MRgRT radiation treatments.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

NASA Astrophysics Data System (ADS)

Bero, M. A.; Abukassem, I.

2009-05-01

Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

Space radiation dosimetry in low-Earth orbit and beyond.

PubMed

Benton, E R; Benton, E V

2001-09-01

Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. c2001 Elsevier Science B.V. All rights reserved.

CHARACTERIZATION OF RELATIVE SENSITIVITY OF AMPHIBIANS TO ULTRAVIOLET RADIATION

EPA Science Inventory

Different studies have demonstrated that solar ultraviolet (UV) radiation can adversely affect survival and development of embryonic and larval amphibians. However, because of among-laboratory variations in exposure profiles (artificial vs. natural sunlight; natural sunlight at d...

Thermoluminescent dosimetry in veterinary diagnostic radiology.

PubMed

Hernández-Ruiz, L; Jimenez-Flores, Y; Rivera-Montalvo, T; Arias-Cisneros, L; Méndez-Aguilar, R E; Uribe-Izquierdo, P

2012-12-01

This paper presents the results of Environmental and Personnel Dosimetry made in a radiology area of a veterinary hospital. Dosimetry was realized using thermoluminescent (TL) materials. Environmental Dosimetry results show that areas closer to the X-ray equipment are safe. Personnel Dosimetry shows important measurements of daily workday in some persons near to the limit established by ICRP. TL results of radiation measurement suggest TLDs are good candidates as a dosimeter to radiation dosimetry in veterinary radiology. Copyright © 2012 Elsevier Ltd. All rights reserved.

The budget of biologically active ultraviolet radiation in the earth-atmosphere system

NASA Technical Reports Server (NTRS)

Frederick, John E.; Lubin, Dan

1988-01-01

This study applies the concept of a budget to describe the interaction of solar ultraviolet (UV) radiation with the earth-atmosphere system. The wavelength ranges of interest are the biologically relevant UV-B between 280 and 320 nm and the UV-A from 32000 to 400 nm. The Nimbus 7 solar backscattered ultraviolet (SBUV) instrument provides measurements of total column ozone and information concerning cloud cover which, in combination with a simple model of radiation transfer, define the fractions of incident solar irradiance absorbed in the atmosphere, reflected to space, and absorbed at the ground. Results for the month of July quantify the contribution of fractional cloud cover and cloud optical thickness to the radiation budget's three components. Scattering within a thick cloud layer makes the downward radiation field at the cloud base more isotropic than is the case for clear skies. For small solar zenith angles, typical of summer midday conditions, the effective pathlength of this diffuse irradiance through tropospheric ozone is greater than that under clear-sky conditions. The result is an enhanced absorption of UV-B radiation in the troposphere during cloud-covered conditions. Major changes in global cloud cover or cloud optical thicknesses could alter the ultraviolet radiation received by the biosphere by an amount comparable to that predicted for long-term trends in ozone.

Ultraviolet radiation properties as applied to photoclimatherapy at the Dead Sea.

PubMed

Kudish, A I; Abels, D; Harari, M

2003-05-01

The Dead Sea basin, the lowest terrestrial point on earth, is recognized as a natural treatment center for patients with various cutaneous and rheumatic diseases. Psoriasis is the major skin disease treated at the Dead Sea with excellent improvement to complete clearance exceeding 85% after 4 weeks of treatment. These results were postulated to be associated with a unique spectrum of ultraviolet radiation present in the Dead Sea area. The UVB and UVA radiation at two sites is measured continuously by identical sets of broad-band Solar Light Co. Inc. meters (Philadelphia, PA). The spectral selectivity within the UVB and UVA spectrum was determined using a narrow-band spectroradiometer, UV-Optronics 742 (Orlando, FL). The optimum exposure time intervals for photoclimatherapy, defined as the minimum ratio of erythema to therapeutic radiation intensities, were also determined using a Solar Light Co. Inc. Microtops II, Ozone Monitor-Sunphotometer. The ultraviolet radiation at the Dead Sea is attenuated relative to Beer Sheva as a result of the increased optical path length and consequent enhanced scattering. The UVB radiation is attenuated to a greater extent than UVA and the shorter erythema UVB spectral range decreased significantly compared with the longer therapeutic UVB wavelengths. It was demonstrated that the relative attenuation within the UVB spectral range is greatest for the shorter erythema rays and less for the longer therapeutic UVB wavelengths, thus producing a greater proportion of the longer therapeutic UVB wavelengths in the ultraviolet spectrum. These measurements can be utilized to minimize the exposure to solar radiation by correlating the cumulative UVB radiation dose to treatment efficacy and by formulating a patient sun exposure treatment protocol for Dead Sea photoclimatherapy.

The visible signal responsible for proton therapy dosimetry using bare optical fibers is not Čerenkov radiation.

PubMed

Darafsheh, Arash; Taleei, Reza; Kassaee, Alireza; Finlay, Jarod C

2016-11-01

Proton beam dosimetry using bare plastic optical fibers has emerged as a simple approach to proton beam dosimetry. The source of the signal in this method has been attributed to Čerenkov radiation. The aim of this work was a phenomenological study of the nature of the visible light responsible for the signal in bare fiber optic dosimetry of proton therapy beams. Plastic fiber optic probes embedded in solid water phantoms were irradiated with proton beams of energies 100, 180, and 225 MeV produced by a proton therapy cyclotron. Luminescence spectroscopy was performed by a CCD-coupled spectrometer. The spectra were acquired at various depths in phantom to measure the percentage depth dose (PDD) for each beam energy. For comparison, the PDD curves were acquired using a standard multilayer ion chamber device. In order to further analyze the contribution of the Čerenkov radiation in the spectra, Monte Carlo simulation was performed using fluka Monte Carlo code to stochastically simulate radiation transport, ionizing radiation dose deposition, and optical emission of Čerenkov radiation. The measured depth doses using the bare fiber are in agreement with measurements performed by the multilayer ion chamber device, indicating the feasibility of using bare fiber probes for proton beam dosimetry. The spectroscopic study of proton-irradiated fibers showed a continuous spectrum with a shape different from that of Čerenkov radiation. The Monte Carlo simulations confirmed that the amount of the generated Čerenkov light does not follow the radiation absorbed dose in a medium. The source of the optical signal responsible for the proton dose measurement using bare optical fibers is not Čerenkov radiation. It is fluorescence of the plastic material of the fiber.

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

NASA Technical Reports Server (NTRS)

Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.; Lemaire, P.; Marsch, E.

1992-01-01

The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of Extreme Ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy, provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature from 10,000 to more than 1,800,000 K.

Ocular ultraviolet radiation exposure of welders.

PubMed

Tenkate, Thomas D

2017-05-01

reference made to the average solar UVR exposure of a Danish outdoor worker being 22 400 J/m 2 per year (min-max 5400 - 66 900 J/m 2 per year) (10). For comparison, taking the mean 8-hour UVR dose within the welding helmets as 15 mJ/cm2 (3), this would equate to an annual ocular/facial UVR dose for welders of 37 500 J/m 2 (at 5 days/week, 50 weeks/year). Even though this value is weighted for the ACGIH action spectrum, and the value for the Danish outdoor workers is weighted for the erythema spectrum, it provides a reasonable comparison and indicates that welders are likely to receive comparable facial/ocular UVR doses to outdoor workers. Slagor et al also state that "it is inferred that welders are not exposed to large amounts of UVR during their work life, in spite of the photokeratoconjunctivitis incidents" (1, p451). I would propose that the UVR dosimetry studies described above (2, 3), taken together with studies on UVR emissions of welding arcs which show that the MPE for many welding arcs can be exceeded in a matter of seconds (11-13), indicate that welders do work in an extreme UVR environment. These studies also suggest that welders are regularly exposed to levels of UVR that exceed the occupational exposure limits at body sites which are thought to be protected (eg, face and eyes) (2, 3). When these exposures are further considered in light of the range of eye conditions reported to occur in welders (14-17), the importance of implementing a comprehensive eye safety strategy for welders and all workers in a welding environment is imperative. References 1. Slagor RM, La Cour M, Bonde JP. The risk of cataract in relation to metal arc welding. Scan J Work Environ Health. 2016;42(5):447-53. https://doi.org/10.5271/sjweh.3572.  2. Shehade SA, Roberts PJ, Diffey BF, Foulds IS. Photodermatitis due to spot welding. Br J Dermatol. 1987;117:117-9. https://doi.org/10.1111/j.1365-2133.1987.tb04100.x.  3. Tenkate TD, Collins MJ. Personal ultraviolet radiation exposure of

Measurements of Solar Ultraviolet Radiation Exposure at Work and at Leisure in Danish Workers.

PubMed

Grandahl, Kasper; Eriksen, Paul; Ibler, Kristina Sophie; Bonde, Jens Peter; Mortensen, Ole Steen

2018-03-30

Exposure to solar ultraviolet radiation is the main cause of skin cancer and may well present an occupational health and safety problem. In Denmark, skin cancer is a common disease in the general population, but detailed data on solar ultraviolet radiation exposure among outdoor workers are lacking. The aim of this study was to provide objective measurements of solar ultraviolet radiation exposure on working days and at leisure and compare levels of exposure between groups of mainly outdoor, equal-parts-outdoor-and-indoor and indoor workers. To this end, UV-B dosimeters with an aluminum gallium nitride (AlGaN) photodiode detector were used to measure the solar ultraviolet radiation exposure of 457 workers in the Danish summer season. Presented as semi-annual standard erythemal dose (SED) on working days, respectively, at leisure, the results are for mainly outdoor workers 214.2 SED and 64.8 SED, equal-parts-outdoor-and-indoor workers 131.4 SED and 64.8 SED, indoor workers 55.8 SED and 57.6 SED. The daily SED by month is significantly different (α = 0.05) between mainly outdoor, equal-parts-outdoor-and-indoor and indoor workers and across professional groups; some of which are exposed at very high levels that is roofers 361.8 SED. These findings substantiate that exposure to solar ultraviolet radiation is indeed an occupational health and safety problem in Denmark. © 2018 The Authors. Photochemistry and Photobiology published by Wiley Periodicals, Inc. on behalf of American Society for Photobiology.

Development of a portable graphite calorimeter for radiation dosimetry.

PubMed

Sakama, Makoto; Kanai, Tatsuaki; Fukumura, Akifumi

2008-01-01

We developed and performance-tested a portable graphite calorimeter designed to measure the absolute dosimetry of various beams including heavy-ion beams, based on a flexible and convenient means of measurement. This measurement system is fully remote-controlled by the GPIB system. This system uses a digital PID (Proportional, Integral, Derivative) control method based on the LabVIEW software. It was possible to attain stable conditions in a shorter time by this system. The standard deviation of the measurements using the calorimeter was 0.79% at a dose rate of 0.8 Gy/min in 17 calorimeter runs for a (60)Co photon beam. The overall uncertainties for the absorbed dose to graphite and water of the (60)Co photon beam using the developed calorimeter were 0.89% and 1.35%, respectively. Estimations of the correction factors due to vacuum gaps, impurities in the core, the dose gradient and the radiation profile were included in the uncertainties. The absorbed doses to graphite and water irradiated by the (60)Co photon beam were compared with dosimetry measurements obtained using three ionization chambers. The absorbed doses to graphite and water estimated by the two dosimetry methods agreed within 0.1% and 0.3%, respectively.

Stage-dependent teratogenic and lethal effects exerted by ultraviolet B radiation on Rhinella (Bufo) arenarum embryos.

PubMed

Castañaga, Luis A; Asorey, Cynthia M; Sandoval, María T; Pérez-Coll, Cristina S; Argibay, Teresa I; Herkovits, Jorge

2009-02-01

The adverse effects of ultraviolet B radiation from 547.2 to 30,096 J/m2 on morphogenesis, cell differentiation, and lethality of amphibian embryos at six developmental stages were evaluated from 24 up to 168 h postexposure. The ultraviolet B radiation lethal dose 10, 50, and 90 values were obtained for all developmental stages evaluated. The lethal dose 50 values, considered as the dose causing lethality in the 50% of the organisms exposed, in J/m2 at 168 h postexposure, ranged from 2,307 to 18,930; gill circulation and blastula were the most susceptible and resistant stages, respectively. Ultraviolet B radiation caused malformations in all developmental stages but was significantly more teratogenic at the gill circulation and complete operculum stages. Moreover, at the gill circulation stage, even the lowest dose (547.2 J/m2) resulted in malformations to 100% of embryos. The most common malformations were persistent yolk plug, bifid spine, reduced body size, delayed development, asymmetry, microcephaly and anencephaly, tail and body flexures toward the irradiated side, agenesia or partial gill development, abnormal pigment distribution, and hypermotility. The stage-dependent susceptibility to ultraviolet B radiation during amphibian embryogenesis could be explained in the framework of evoecotoxicology, considering ontogenic features as biomarkers of environmental signatures of living forms ancestors during the evolutionary process. The stage-dependent susceptibility to ultraviolet B radiation on Rhinella (Bufo) arenarum embryos for both lethal and teratogenic effects could contribute to a better understanding of the role of the increased ultraviolet B radiation on worldwide amphibian populations decline.

Increased exposure of Southern Ocean phytoplankton to ultraviolet radiation

NASA Astrophysics Data System (ADS)

Lubin, Dan; Arrigo, Kevin R.; van Dijken, Gert L.

2004-05-01

Satellite remote sensing of both surface solar ultraviolet radiation (UVR) and chlorophyll over two decades shows that biologically significant ultraviolet radiation increases began to occur over the Southern Ocean three years before the ozone ``hole'' was discovered. Beginning in October 1983, the most frequent occurrences of enhanced UVR over phytoplankton-rich waters occurred in the Weddell Sea and Indian Ocean sectors of the Southern Ocean, impacting 60% of the surface biomass by the late 1990s. These results suggest two reasons why more serious impacts to the base of the marine food web may not have been detected by field experiments: (1) the onset of UVR increases several years before dedicated field work began may have impacted the most sensitive organisms long before such damage could be detected, and (2) most biological field work has so far not taken place in Antarctic waters most extensively subjected to enhanced UVR.

Effects of near ultraviolet and green radiations on plant growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, R.M.; Edsall, P.C.; Gentile, A.C.

Selective removal of near ultraviolet and green wavelengths from white light permitted enhanced growth of marigold, tomato, corn, and Impatiens plants, Chlamydomonas cells and the mycelium of Sordaria. Additions of near ultraviolet and green radiations caused repressions in the growth of marigold and Sordaria. These wavelengths do not alter the oxidative mechanisms of mitochondria, intact algal cells or marigold leaf tissues. The capacity for chlorophyll and carotenoid synthesis by Euglena cells was unaffected by these wavelengths. 23 references, 2 figures, 4 tables.

Observed ozone response to variations in solar ultraviolet radiation

NASA Technical Reports Server (NTRS)

Gille, J. C.; Smythe, C. M.; Heath, D. F.

1984-01-01

During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers.

ULTRAVIOLET RADIATION DOSE AND AMPHIBIAN DISTRIBUTIONS IN NATIONAL PARKS

EPA Science Inventory

Ultraviolet Radiation Dose and Amphibian Distributions in National Parks. Diamond, S. A., Detenbeck, N. E., USEPA, Duluth, MN, USA, Bradford, D. F., USEPA, Las Vegas, NV, USA, Trenham, P. C., University of California, Davis, CA., USA, Adams, M. J., Corn, P. S., Hossack, B., USGS,...

Sources and measurement of ultraviolet radiation.

PubMed

Diffey, Brian L

2002-09-01

Ultraviolet (UV) radiation is part of the electromagnetic spectrum. The biological effects of UV radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions: UVA, UVB, and UVC. Quantities of UV radiation are expressed using radiometric terminology. A particularly important term in clinical photobiology is the standard erythema dose (SED), which is a measure of the erythemal effectiveness of a UV exposure. UV radiation is produced either by heating a body to an incandescent temperature, as is the case with solar UV, or by passing an electric current through a gas, usually vaporized mercury. The latter process is the mechanism whereby UV radiation is produced artificially. Both the quality (spectrum) and quantity (intensity) of terrestrial UV radiation vary with factors including the elevation of the sun above the horizon and absorption and scattering by molecules in the atmosphere, notably ozone, and by clouds. For many experimental studies in photobiology it is simply not practicable to use natural sunlight and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed; these are based on either optically filtered xenon arc lamps or fluorescent lamps. The complete way to characterize an UV source is by spectroradiometry, although for most practical purposes a detector optically filtered to respond to a limited portion of the UV spectrum normally suffices.

Evaluation of a 3D diamond detector for medical radiation dosimetry

NASA Astrophysics Data System (ADS)

Kanxheri, K.; Servoli, L.; Oh, A.; Munoz Sanchez, F.; Forcolin, G. T.; Murphy, S. A.; Aitkenhead, A.; Moore, C. J.; Morozzi, A.; Passeri, D.; Bellini, M.; Corsi, C.; Lagomarsino, S.; Sciortino, S.

2017-01-01

Synthetic diamond has several properties that are particularly suited to applications in medical radiation dosimetry. It is tissue equivalent, not toxic and shows a high resistance to radiation damage, low leakage current and stability of response. It is an electrical insulator, robust and realizable in small size; due to these features there are several examples of diamond devices, mainly planar single-crystalline chemical vapor depositation (sCVD) diamond, used for relative dose measurement in photon beams. Thanks to a new emerging technology, diamond devices with 3-dimensional structures are produced by using laser pulses to create graphitic paths in the diamond bulk. The necessary bias voltage to operate such detector decreases considerably while the signal response and radiation resistance increase. In order to evaluate the suitability of this new technology for measuring the dose delivered by radiotherapy beams in oncology a 3D polycrystalline (pCVD) diamond detector designed for single charged particle detection has been tested and the photon beam profile has been studied. The good linearity and high sensitivity to the dose observed in the 3D diamond, opens the way to the possibility of realizing a finely segmented device with the potential for dose distribution measurement in a single exposure for small field dosimetry that nowadays is still extremely challenging.

Review on the characteristics of radiation detectors for dosimetry and imaging

NASA Astrophysics Data System (ADS)

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-01

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general

On the Retirement of E.P. Goldfinch, Founder of Radiation Protection Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, Joseph C.; Horowitz, Yigal S.

This special issue of Radiation Protection Dosimetry commemorates the many years of service Eddie has dedicated to the international radiation protection community. Beginning with its first issue in 1981, Eddie led RPD to its current prominence with a guiding hand and Solomon-like wisdom, coupled with keen common sense which will be sorely missed. But, there is no doubt that the journal he created will continue to flourish in the foreseeable future.

New Radiation Dosimetry Estimates for [18F]FLT based on Voxelized Phantoms.

PubMed

Mendes, B M; Ferreira, A V; Nascimento, L T C; Ferreira, S M Z M D; Silveira, M B; Silva, J B

2018-04-25

3'-Deoxy-3-[ 18 F]fluorothymidine, or [ 18 F]FLT, is a positron emission tomography (PET) tracer used in clinical studies for noninvasive assessment of proliferation activity in several types of cancer. Although the use of this PET tracer is expanding, to date, few studies concerning its dosimetry have been published. In this work, new [ 18 F]FLT dosimetry estimates are determined for human and mice using Monte Carlo simulations. Modern voxelized male and female phantoms and [ 18 F]FLT biokinetic data, both published by the ICRP, were used for simulations of human cases. For most human organs/tissues the absorbed doses were higher than those reported in ICRP Publication 128. An effective dose of 1.70E-02 mSv/MBq to the whole body was determined, which is 13.5% higher than the ICRP reference value. These new human dosimetry estimates obtained using more realistic human phantoms represent an advance in the knowledge of [ 18 F]FLT dosimetry. In addition, mice biokinetic data were obtained experimentally. These data and a previously developed voxelized mouse phantom were used for simulations of animal cases. Concerning animal dosimetry, absorbed doses for organs/tissues ranged from 4.47 ± 0.75 to 155.74 ± 59.36 mGy/MBq. The obtained set of organ/tissue radiation doses for healthy Swiss mice is a useful tool for application in animal experiment design.

Solar Activity, Ultraviolet Radiation and Consequences in Birds in Mexico City, 2001- 2002

NASA Astrophysics Data System (ADS)

Valdes, M.; Velasco, V.

2008-12-01

Anomalous behavior in commercial and pet birds in Mexico City was reported during 2002 by veterinarians at the Universidad Nacional Autonoma de Mexico. This was attributed to variations in the surrounding luminosity. The solar components, direct, diffuse, global, ultraviolet band A and B, as well as some meteorological parameters, temperature, relative humidity, and precipitation, were then analyzed at the Solar Radiation Laboratory. Although the total annual radiance of the previously mentioned radiation components did not show important changes, ultraviolet Band-B solar radiation did vary significantly. During 2001 the total annual irradiance , 61.05 Hjcm² to 58.32 Hjcm², was 1.6 standard deviations lower than one year later, in 2002 and increased above the mean total annual irradiance, to 65.75 Hjcm², 2.04 standard deviations, giving a total of 3.73 standard deviations for 2001-2002. Since these differences did not show up clearly in the other solar radiation components, daily extra-atmosphere irradiance was analyzed and used to calculate the total annual extra-atmosphere irradiance, which showed a descent for 2001. Our conclusions imply that Ultraviolet Band-B solar radiation is representative of solar activity and has an important impact on commercial activity related with birds.

Optical dosimetry of radiotherapy beams using Cherenkov radiation: the relationship between light emission and dose.

PubMed

Glaser, Adam K; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

2014-07-21

Recent studies have proposed that light emitted by the Cherenkov effect may be used for a number of radiation therapy dosimetry applications. There is a correlation between the captured light and expected dose under certain conditions, yet discrepancies have also been observed and a complete examination of the theoretical differences has not been done. In this study, a fundamental comparison between the Cherenkov emission and absorbed dose was explored for x-ray photons, electrons, and protons using both a theoretical and Monte Carlo-based analysis. Based on the findings of where dose correlates with Cherenkov emission, it was concluded that for x-ray photons the light emission would be optimally suited for narrow beam stereotactic radiation therapy and surgery validation studies, for verification of dynamic intensity-modulated and volumetric modulated arc therapy treatment plans in water tanks, near monoenergetic sources (e.g., Co-60 and brachy therapy sources) and also for entrance and exit surface imaging dosimetry of both narrow and broad beams. For electron use, Cherenkov emission was found to be only suitable for surface dosimetry applications. Finally, for proton dosimetry, there exists a fundamental lack of Cherenkov emission at the Bragg peak, making the technique of little use, although post-irradiation detection of light emission from radioisotopes could prove to be useful.

Radiation dosimetry using three-dimensional optical random access memories

NASA Technical Reports Server (NTRS)

Moscovitch, M.; Phillips, G. W.

2001-01-01

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

WE-AB-BRB-12: Nanoscintillator Fiber-Optic Detector System for Microbeam Radiation Therapy Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivera, J; Dooley, J; Chang, S

2015-06-15

Purpose: Microbeam Radiation Therapy (MRT) is an experimental radiation therapy that has demonstrated a higher therapeutic ratio than conventional radiation therapy in animal studies. There are several roadblocks in translating the promising treatment technology to clinical application, one of which is the lack of a real-time, high-resolution dosimeter. Current clinical radiation detectors have poor spatial resolution and, as such, are unsuitable for measuring microbeams with submillimeter-scale widths. Although GafChromic film has high spatial resolution, it lacks the real-time dosimetry capability necessary for MRT preclinical research and potential clinical use. In this work we have demonstrated the feasibility of using amore » nanoscintillator fiber-optic detector (nanoFOD) system for real-time MRT dosimetry. Methods: A microplanar beam array is generated using a x-ray research irradiator and a custom-made, microbeam-forming collimator. The newest generation nanoFOD has an effective size of 70 µm in the measurement direction and was calibrated against a kV ion chamber (RadCal Accu-Pro) in open field geometry. We have written a computer script that performs automatic data collection with immediate background subtraction. A computer-controlled detector positioning stage is used to precisely measure the microbeam peak dose and beam profile by translating the stage during data collection. We test the new generation nanoFOD system, with increased active scintillation volume, against the previous generation system. Both raw and processed data are time-stamped and recorded to enable future post-processing. Results: The real-time microbeam dosimetry system worked as expected. The new generation dosimeter has approximately double the active volume compared to the previous generation resulting in over 900% increase in signal. The active volume of the dosimeter still provided the spatial resolution that meets the Nyquist criterion for our microbeam widths. Conclusion

SU-E-T-89: Characterization of Dental Restoration Material for Cs-137 Radiation Dosimetry.

PubMed

Ratliff, S; Gustafson, B; Barry, K

2012-06-01

The purpose of this work is to characterize the radiation-induced thermoluminescence properties of a dental restoration material and to see if the material might be feasible for use in retrospective radiation dosimetry. Retrospective, or accidental, dosimetry is the study of using nearby materials to measure radiation received by individuals. In this project we obtained samples of Ivoclar Vivadent e.max CAD material, a glass-ceramic used for making dental restorations such as full or partial crowns. The samples were machined into square chips .32 cm × .32 cm × .089 cm and annealed in the same furnace used by the dentist. The samples were exposed to a Cs-137 source using a PMMA source holder and then read in a Harshaw 3500 TLD reader. The samples were read without nitrogen gas flux using heating rates of 5 degrees C/s or 10 degrees C/s up to a maximum temperature of 400 degrees Celsius. The glow curves were analyzed using Systat PeakFIT peak-fitting software and Microsoft Excel spreadsheets. The authors gratefully thank Dr. Aaron Imdieke and the staff of River City Dental, St. Cloud, MN for the dental restoration materials and the use of their dental furnace. A sample subjected to a radiation exposure of .04 C/kg exhibits a glow curve with a prominent peak at approximately 140 degrees Celsius, which is well-modeled by the first order glow curve deconvolution formula developed by Kitis, Gomez-Ros, and Tuyn. The activation energy corresponding to this peak is approximately 1 eV. The thermoluminescent signal fades with time after exposure. Ivoclar Vivadent e.max CAD dental restoration material has the potential to be used as a material for retrospective Cs-137 radiation dosimetry. Future work could look at its thermoluminescent dosimetry properties in more detail and also at other dental restoration materials. The authors would like to thank Dr. Aaron Imdieke and the staff of River City Dental, St. Cloud, MN, for the donation of scrap dental restoration materials and

WE-AB-BRB-03: Real-Time Volumetric Scintillation Dosimetry for Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beddar, S.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA

Ultraviolet absorption hygrometer

DOEpatents

Gersh, M.E.; Bien, F.; Bernstein, L.S.

1986-12-09

An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

Interventions to prevent skin cancer by reducing exposure to ultraviolet radiation: a systematic review.

PubMed

Saraiya, Mona; Glanz, Karen; Briss, Peter A; Nichols, Phyllis; White, Cornelia; Das, Debjani; Smith, S Jay; Tannor, Bernice; Hutchinson, Angela B; Wilson, Katherine M; Gandhi, Nisha; Lee, Nancy C; Rimer, Barbara; Coates, Ralph C; Kerner, Jon F; Hiatt, Robert A; Buffler, Patricia; Rochester, Phyllis

2004-12-01

The relationship between skin cancer and ultraviolet radiation is well established. Behaviors such as seeking shade, avoiding sun exposure during peak hours of radiation, wearing protective clothing, or some combination of these behaviors can provide protection. Sunscreen use alone is not considered an adequate protection against ultraviolet radiation. This report presents the results of systematic reviews of effectiveness, applicability, other harms or benefits, economic evaluations, and barriers to use of selected interventions to prevent skin cancer by reducing exposure to ultraviolet radiation. The Task Force on Community Preventive Services found that education and policy approaches to increasing sun-protective behaviors were effective when implemented in primary schools and in recreational or tourism settings, but found insufficient evidence to determine effectiveness when implemented in other settings, such as child care centers, secondary schools and colleges, and occupational settings. They also found insufficient evidence to determine the effectiveness of interventions oriented to healthcare settings and providers, media campaigns alone, interventions oriented to parents or caregivers of children, and community-wide multicomponent interventions. The report also provides suggestions for areas for future research.

Disinfection of Airborne Organisms by Ultraviolet-C Radiation and Sunlight

DTIC Science & Technology

2012-07-01

organisms deposited on surfaces, suspended in water , and contaminating food, all of which have been discussed elsewhere (Block, 2001). In contrast, the... water . Therefore, the primary means for organism inactivation in aerosols is ultraviolet (UV) radiation. Radiation from the sunlight is used as a...cortex is essential for reduction of the water content in the spore core and formation of a dormant spore. The cortex is degraded in spore

Research in extreme ultraviolet and far ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Labov, S. E.

1985-01-01

Instruments designed to explore different aspects of far and extreme ultraviolet cosmic radiation were studied. The far ultraviolet imager (FUVI) was flown on the Aries sounding rocket. Its unique large format 75mm detector mapped out the far ultraviolet background radiation with a resolution of only a few arc minutes. Analysis of this data indicates to what extent the FUVI background is extra galactic in origin. A power spectrum of the spatial fluctuations will have direct consequences for galactic evolution.

Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation

PubMed Central

Kadekaro, Ana Luisa; Leachman, Sancy; Kavanagh, Renny J.; Swope, Viki; Cassidy, Pamela; Supp, Dorothy; Sartor, Maureen; Schwemberger, Sandy; Babcock, George; Wakamatsu, Kazumasa; Ito, Shosuke; Koshoffer, Amy; Boissy, Raymond E.; Manga, Prashiela; Sturm, Richard A.; Abdel-Malek, Zalfa A.

2010-01-01

The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to α-melanocortin and ultraviolet radiation. We found that expression of 2 red hair variants abolished the response to α-melanocortin and its photoprotective effects, evidenced by lack of functional coupling of the receptor, and absence of reduction in ultraviolet radiation-induced hydrogen peroxide generation or enhancement of repair of DNA photoproducts, respectively. These variants had different heterozygous effects on receptor function. Microarray data confirmed the observed differences in responses of melanocytes with functional vs. nonfunctional receptor to α-melanocortin and ultraviolet radiation, and identified DNA repair and antioxidant genes that are modulated by α-melanocortin. Our findings highlight the molecular mechanisms by which the melanocortin 1 receptor genotype controls genomic stability of and the mutagenic effect of ultraviolet radiation on human melanocytes.—Kadekaro, A. L., Leachman, S., Kavanagh, R. J., Swope, V., Cassidy, P., Supp, D., Sartor, M., Schwemberger, S., Babcock, G., Wakamatsu, K., Ito, S., Koshoffer, A., Boissy, R. E., Manga, P., Sturm, R. A., Abdel-Malek, Z. A. Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation. PMID:20519635

The work programme of EURADOS on internal and external dosimetry.

PubMed

Rühm, W; Bottollier-Depois, J F; Gilvin, P; Harrison, R; Knežević, Ž; Lopez, M A; Tanner, R; Vargas, A; Woda, C

2018-01-01

Since the early 1980s, the European Radiation Dosimetry Group (EURADOS) has been maintaining a network of institutions interested in the dosimetry of ionising radiation. As of 2017, this network includes more than 70 institutions (research centres, dosimetry services, university institutes, etc.), and the EURADOS database lists more than 500 scientists who contribute to the EURADOS mission, which is to promote research and technical development in dosimetry and its implementation into practice, and to contribute to harmonisation of dosimetry in Europe and its conformance with international practices. The EURADOS working programme is organised into eight working groups dealing with environmental, computational, internal, and retrospective dosimetry; dosimetry in medical imaging; dosimetry in radiotherapy; dosimetry in high-energy radiation fields; and harmonisation of individual monitoring. Results are published as freely available EURADOS reports and in the peer-reviewed scientific literature. Moreover, EURADOS organises winter schools and training courses on various aspects relevant for radiation dosimetry, and formulates the strategic research needs in dosimetry important for Europe. This paper gives an overview on the most important EURADOS activities. More details can be found at www.eurados.org .

Improving Assessment of Lifetime Solar Ultraviolet Radiation Exposure in Epidemiologic Studies: Comparison of Ultraviolet Exposure Assessment Methods in a Nationwide United States Occupational Cohort.

PubMed

Little, Mark P; Tatalovich, Zaria; Linet, Martha S; Fang, Michelle; Kendall, Gerald M; Kimlin, Michael G

2018-06-13

Solar ultraviolet radiation is the primary risk factor for skin cancers and sun-related eye disorders. Estimates of individual ambient ultraviolet irradiance derived from ground-based solar measurements and from satellite measurements have rarely been compared. Using self-reported residential history from 67,189 persons in a nationwide occupational US radiologic technologists cohort, we estimated ambient solar irradiance using data from ground-based meters and noontime satellite measurements. The mean distance-moved from city of longest residence in childhood increased from 137.6 km at ages 13-19 to 870.3 km at ages ≥65, with corresponding increases in absolute latitude-difference moved. At ages 20/40/60/80, the Pearson/Spearman correlation coefficients of ground-based and satellite-derived solar potential ultraviolet exposure, using irradiance and cumulative radiant-exposure metrics, were high (=0.87-0.92). There was also moderate correlation (Pearson/Spearman correlation coefficients=0.51-0.60) between irradiance at birth and at last-known address, for ground-based and satellite data. Satellite-based lifetime estimates of ultraviolet radiation were generally 14-15% lower than ground-based estimates, albeit with substantial uncertainties, possibly because ground-based estimates incorporate fluctuations in cloud and ozone, which are incompletely incorporated in the single noontime satellite-overpass ultraviolet value. If confirmed elsewhere, the findings suggest that ground-based estimates may improve exposure-assessment accuracy and potentially provide new insights into ultraviolet-radiation-disease relationships in epidemiologic studies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Estimated Ultraviolet Radiation Doses in Wetlands in Six National Parks

EPA Science Inventory

Ultraviolet radiation (UVR) has been suggested as a potential cause of population declines and increases in malformations in amphibians. This study indicates that the present distributions of amphibians in four western U.S. National Parks are not related to UVR exposure, and sugg...

Channel catfish response to ultraviolet-B radiation

USGS Publications Warehouse

Ewing, M.S.; Blazer, V.S.; Fabacher, D.L.; Little, E.E.; Kocan, K.M.

1999-01-01

Fingerling channel catfish Ictalurus punctatus exposed to simulated ultraviolet-B radiation at an average daily dose of 2.9 J/cm2 were quite sensitive to the radiation. After a 24-h exposure, thinning of the most dorsal epidermis frequently was accompanied by edema. Compared with epidermis of unexposed fish, mucous cells in exposed fish were less superficial and club cells were less numerous both dorsally and high on the lateral surface of the body. Sunburn cells with pyknotic nuclei were evident in the epidermis of exposed fish. Among fish exposed for 48 h, focal necrosis and sloughing of the outer epidermal layer were widespread. A methanol-extractable skin substance that is associated with resistance to sunburn in other fish species was not detected in channel catfish.

Tolerance of an albino fish to ultraviolet-B radiation

USGS Publications Warehouse

Fabacher, David L.; Little, Edward E.; Ostrander, Gary K.

1999-01-01

We exposed albino and pigmented medakaOryzias latipes to simulated solar ultraviolet-B (UVB) radiation to determine if albino medaka were less tolerant of UVB radiation than medaka pigmented with melanin. There was no difference in the number of albino and pigmented medaka that died during the exposure period. Spectrophotometric analyses of the outer dorsal skin layers from albino and pigmented medaka indicated that, prior to exposure, both groups of fish had similar amounts of an apparent colorless non-melanin photoprotective substance that appears to protect other fish species from UVB radiation. Our results indicate that albino medaka were as tolerant of UVB radiation as pigmented medaka because they had similar amounts of this photoprotective substance in the outer layers of the skin.

Experimental Determination of Ultraviolet Radiation Protection of Common Materials

ERIC Educational Resources Information Center

Tavares, Susana C. A.; da Silva, Joaquim C. G. Esteves; Paiva, Joao

2007-01-01

Aiming at a better understanding of the problems associated with the depletion of the ozone layer, we propose several experiments to be performed by students of different levels: secondary and first-year undergraduate students. The oxidation of iodide induced by ultraviolet (UV) radiation, generated by a mercury lamp, is used as an indicator for…

The ultraviolet radiation environment of pollen and its effect on pollen germination

NASA Technical Reports Server (NTRS)

1981-01-01

The damage to pollen caused by natural ultraviolet radiation was investigated. Experimental and literature research into the UV radiation environment is reported. Viability and germination of wind and insect pollinated species were determined. Physiological, developmental, and protective factors influencing UV sensitivity of binucleate, advanced binucleate, and trinucleate pollen grains are compared.

MECHANISMS OF PLANT RESISTANCE TO INCREASED SOLAR ULTRAVIOLET-B RADIATION

EPA Science Inventory

Since the major conclusions of the project are being disseminated via the scientific literature, the final report consists of a compilation of 11 articles and manuscripts on the effects of ultraviolet-B radiation (UVB) on soybean growth and yield, stress interactions with UVB, an...

Biological dosimetry of ionizing radiation: Evaluation of the dose with cytogenetic methodologies by the construction of calibration curves

NASA Astrophysics Data System (ADS)

Zafiropoulos, Demetre; Facco, E.; Sarchiapone, Lucia

2016-09-01

In case of a radiation accident, it is well known that in the absence of physical dosimetry biological dosimetry based on cytogenetic methods is a unique tool to estimate individual absorbed dose. Moreover, even when physical dosimetry indicates an overexposure, scoring chromosome aberrations (dicentrics and rings) in human peripheral blood lymphocytes (PBLs) at metaphase is presently the most widely used method to confirm dose assessment. The analysis of dicentrics and rings in PBLs after Giemsa staining of metaphase cells is considered the most valid assay for radiation injury. This work shows that applying the fluorescence in situ hybridization (FISH) technique, using telomeric/centromeric peptide nucleic acid (PNA) probes in metaphase chromosomes for radiation dosimetry, could become a fast scoring, reliable and precise method for biological dosimetry after accidental radiation exposures. In both in vitro methods described above, lymphocyte stimulation is needed, and this limits the application in radiation emergency medicine where speed is considered to be a high priority. Using premature chromosome condensation (PCC), irradiated human PBLs (non-stimulated) were fused with mitotic CHO cells, and the yield of excess PCC fragments in Giemsa stained cells was scored. To score dicentrics and rings under PCC conditions, the necessary centromere and telomere detection of the chromosomes was obtained using FISH and specific PNA probes. Of course, a prerequisite for dose assessment in all cases is a dose-effect calibration curve. This work illustrates the various methods used; dose response calibration curves, with 95% confidence limits used to estimate dose uncertainties, have been constructed for conventional metaphase analysis and FISH. We also compare the dose-response curve constructed after scoring of dicentrics and rings using PCC combined with FISH and PNA probes. Also reported are dose response curves showing scored dicentrics and rings per cell, combining

Effect of Lot Variability on Ultraviolet Radiation Inactivation Kinetics of Cryptosporidium parvum Oocysts

EPA Science Inventory

Numerous studies have demonstrated the efficiency of ultraviolet (UV) radiation for the inactivation of oocysts of Cryptosporidium parvum. In these studies inactivation is measured as reduction in oocysts. A primary goal is to estimate the UV radiation required to achiev...

Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health.

PubMed

Holick, Michael F

2016-03-01

Humans evolved in sunlight and had depended on sunlight for its life giving properties that was appreciated by our early ancestors. However, for more than 40 years the lay press and various medical and dermatology associations have denounced sun exposure because of its association with increased risk for skin cancer. The goal of this review is to put into perspective the many health benefits that have been associated with exposure to sunlight, ultraviolet A (UVA) ultraviolet B (UVB), visible and infrared radiation. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

NASA Astrophysics Data System (ADS)

Singh, Vishwanath P.; Badiger, N. M.

2014-11-01

Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

The relationship between ultraviolet radiation exposure and vitamin D status.

PubMed

Engelsen, Ola

2010-05-01

This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due to decreased solar intensity and cold temperatures, which discourage skin exposure. During the mid-winter season, these factors result in decreased solar radiation exposure, hindering extensively the synthesis of vitamin D in these populations.

Ocean acidification alters the photosynthetic responses of a coccolithophorid to fluctuating ultraviolet and visible radiation.

PubMed

Jin, Peng; Gao, Kunshan; Villafañe, Virginia E; Campbell, Douglas A; Helbling, E Walter

2013-08-01

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO₂ levels, under regimes of fluctuating irradiances with or without UVR. Under both CO₂ levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO₂ showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO₂-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.

WE-AB-BRB-01: Memorial Introduction; Storage Phosphor Panels for Radiation Therapy Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability ofmore » water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA

Micro-Mini & Nano-Dosimetry & Innovative Technologies in Radiation Therapy (MMND&ITRO2016)

NASA Astrophysics Data System (ADS)

2017-01-01

The biennial MMND (formerly MMD) - IPCT workshops, founded in collaboration with Memorial Sloan Kettering Cancer Center (MSKCC) in 2001, has become an important international multidisciplinary forum for the discussion of advanced dosimetric technology for radiation therapy quality assurance (QA) and space science, as well as advanced technologies for prostate cancer treatment. In more recent years, the interests of participants and the scope of the workshops have extended far beyond prostate cancer treatment alone to include all aspects of radiation therapy, radiation science and technology. We therefore decided to change the name in 2016 to Innovative Technologies in Radiation Oncology (ITRO). MMND ITRO 2016 was held on 26-31 January, 2016 at the beautiful Wrest Point Hotel in Hobart, Tasmania and attracted an outstanding international faculty and nearly 200 delegates from 18 countries (http://mmnditro2016.com/) The MMND 2016 program continued to cover advanced medical physics aspects of IMRT, IGRT, VMAT, SBRT, MRI LINAC, innovative brachytherapy, and synchrotron MRT. The demand for sophisticated real time and high temporal and spatial resolution (down to the submillimetre scale) dosimetry methods and instrumentation for end-to-end QA for these radiotherapy technologies is increasing. Special attention was paid to the contribution of advanced imaging and the application of nanoscience to the recent improvements in imaging and radiotherapy. The last decade has seen great progress in charged particle therapy technology which has spread throughout the world and attracted strong current interest in Australia. This demands a better understanding of the fundamental aspects of ion interactions with biological tissue and the relative biological effectiveness (RBE) of protons and heavy ions. The further development of computational and experimental micro-and nano-dosimetry for ions has important application in radiobiology based treatment planning and space radiation

Freeware for reporting radiation dosimetry following the administration of radiopharmaceuticals.

PubMed

Gómez Perales, Jesús Luis; García Mendoza, Antonio

2015-09-01

This work describes the development of a software application for reporting patient radiation dosimetry following radiopharmaceutical administration. The resulting report may be included within the patient's medical records. The application was developed in the Visual Basic programming language. The dosimetric calculations are based on the values given by the International Commission on Radiological Protection (ICRP). The software is available in both Spanish and English and can be downloaded at no cost from www.radiopharmacy.net. Copyright © 2015 Elsevier Ltd. All rights reserved.

INTERACTIONS OF SOLAR ULTRAVIOLET RADIATION AND DISSOLVED ORGANIC MATTER IN FRESHWATER AND MARINE ENVIRONMENTS

EPA Science Inventory

Solar radiation provides the primary driving force for the biogeochemical cycles upon which life and climate depend. Recent studies have demonstrated that the absorption of solar radiation, especially 'm the ultraviolet spectral region, results in photochemical reactions that can...

Absolute measurement of undulator radiation in the extreme ultraviolet

NASA Astrophysics Data System (ADS)

Maezawa, H.; Mitani, S.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Mikuni, A.; Kitamura, H.; Sasaki, T.

1983-04-01

The spectral brightness of undulator radiation emitted by the model PMU-1 incorporated in the SOR-RING, the dedicated synchrotron radiation source in Tokyo, has been studied in the extreme ultraviolet region from 21.6 to 72.9 eV as a function of the electron energy γ, the field parameter K, and the angle of observation ϴ in the absolute scale. A series of measurements covering the first and the second harmonic component of undulator radiation was compared with the fundamental formula λ n= {λ 0}/{2nγ 2}( {1+K 2}/{2}+γϴ 2 and the effects of finite emittance were studied. The brightness at the first peak was smaller than the theoretical value, while an enhanced second harmonic component was observed.

SOLAR ULTRAVIOLET RADIATION AND AQUATIC CARBON, NITROGEN, SULFUR AND METALS CYCLES

EPA Science Inventory

Solar ultraviolet radiation (290-400 nm) has a wide-ranging impact on biological and chemical processes that affect the cycling of elements in aquatic environments. This chapter uses recent field and laboratory observations along with models to assess these impacts on carbon, nit...

SIMULATED SOLAR ULTRAVIOLET RADIATION EFFECTS ON 5 SPECIES OF SCLERACTINIAN CORALS

EPA Science Inventory

The impact of global climate change factors such as increased temperature and ultraviolet radiation (UVR) on coral bleaching are of continued interest to the USEPA. Coral bleaching occurs when symbiotic zooxanthellae and/or their pigments are depleted in response to stressors suc...

Coordinated Studies of Ultraviolet Radiation and Amphibians in Lentic Wetland Habitats

EPA Science Inventory

Ultraviolet radiation (UVR) has been suggested as a potential cause of population declines and increases in malformations in amphibians. This study indicates that the present distributions of amphibians in four western U.S. National Parks are not related to UVR exposure, and sugg...

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.

Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry.

PubMed

Begum, Mahfuza; Rahman, A K M Mizanur; Abdul-Rashid, H A; Yusoff, Z; Begum, Mahbuba; Mat-Sharif, K A; Amin, Y M; Bradley, D A

2015-06-01

Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1Gy to 10Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5cm length are annealed at temperature of 400°C for 1h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1h at 400°C and subsequently 2h at 100°C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Zeff) is found in the range (13.25-13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

PubMed Central

Han, Zhaohui; Driewer, Joseph P.; Zheng, Yuanshui; Low, Daniel A.; Li, H. Harold

2009-01-01

This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.15:Eu2+ material that is used for computed radiography (CR) but features a significantly smaller effective atomic number—18 versus 49—making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl:Eu2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. The findings were (1) KCl:Eu2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. (2) KCl:Eu2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. (3) After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1%∕h after 12 h. (4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy∕min. (5) The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. (6) Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters (0.3 mm thick lead foils) during irradiation, the over-response was reduced. The authors have demonstrated that KCl:Eu2+ dosimeters have many desirable

Ultraviolet radiation effects on the infrared damage rate of a thermal control coating

NASA Technical Reports Server (NTRS)

Bass, J. A.

1972-01-01

The effects of ultraviolet radiation on the infrared reflectance of ZnO silicone white thermal coatings were investigated. Narrow band ultraviolet radiation for wavelengths in the 2200A to 3500A range by a monochromator and a high pressure, 150-W Eimac xenon lamp. The sample was irradiated while in a vacuum of at least 0.000001 torr, and infrared reflectance was measured in situ with a spectroreflectometer at 19,500A. Reflectance degradation was studied as a function of wavelength, time, intensity, and dose. Damage was wavelength dependent at constant exposure, but no maximum was evident above the shortest wavelength investigated here. The degradation rate at constant intensity was an exponential function of time and varies with intensity.

Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere.

PubMed

Keppler, Frank; Vigano, Ivan; McLeod, Andy; Ott, Ulrich; Früchtl, Marion; Röckmann, Thomas

2012-05-30

Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.

Ultraviolet Radiations: Skin Defense-Damage Mechanism.

PubMed

Mohania, Dheeraj; Chandel, Shikha; Kumar, Parveen; Verma, Vivek; Digvijay, Kumar; Tripathi, Deepika; Choudhury, Khushboo; Mitten, Sandeep Kumar; Shah, Dilip

2017-01-01

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Protective mechanisms and acclimation to solar ultraviolet-B radiation in Oenothera stricta

NASA Technical Reports Server (NTRS)

Robberecht, R.; Caldwell, M. M.

1981-01-01

Plant adaptations ameliorating or repairing the damaging effects of ultraviolet-B (UV-B) radiation on plant tissue were investigated. The degree of phenotype plasticity in UV protective mechanisms and acclimation in relation to the natural solar UV-B radiation flux and in an enhanced UV-B irradiance environment was also examined. Mechanisms by which plants avoid radiation, adaptations altering the path of radiation incident on the leaf, and repair processes were considered. Attenuation of UV-B by tissues, UV-B irradiation into the leaf, and the effects of UV-B on photosynthesis were investigated.

Characterization of a smartphone camera's response to ultraviolet A radiation.

PubMed

Igoe, Damien; Parisi, Alfio; Carter, Brad

2013-01-01

As part of a wider study into the use of smartphones as solar ultraviolet radiation monitors, this article characterizes the ultraviolet A (UVA; 320-400 nm) response of a consumer complementary metal oxide semiconductor (CMOS)-based smartphone image sensor in a controlled laboratory environment. The CMOS image sensor in the camera possesses inherent sensitivity to UVA, and despite the attenuation due to the lens and neutral density and wavelength-specific bandpass filters, the measured relative UVA irradiances relative to the incident irradiances range from 0.0065% at 380 nm to 0.0051% at 340 nm. In addition, the sensor demonstrates a predictable response to low-intensity discrete UVA stimuli that can be modelled using the ratio of recorded digital values to the incident UVA irradiance for a given automatic exposure time, and resulting in measurement errors that are typically less than 5%. Our results support the idea that smartphones can be used for scientific monitoring of UVA radiation. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

In-Flight Ultraviolet Radiation on Commercial Airplanes.

PubMed

Cadilhac, Pascal; Bouton, Marie-Christine; Cantegril, Monique; Cardines, Catherine; Gisquet, Alain; Kaufman, Noël; Klerlein, Michel

2017-10-01

Epidemiological studies suggest that pilots and cabin crew have higher incidences and mortality rates of cutaneous malignant melanoma than those of the general population. Exposure to UV radiation is one of the main risk factors for this type of cancer. The aim of this study was to evaluate the level of UV radiation in an airliner in flight. Measurements were taken with a three sensor-integrated electronics UV radiometer (A, B, and C) during 14 flights from July to October 2016. They were performed during daylight hours once the airliner had reached cruising altitude. We failed to find UVC radiation. The measurements detected neither UV A nor B in any parts of the cabins of the planes tested, nor in the Airbus cockpits. UVA radiation was however found in the cockpit of Boeing 777s. But UVA levels remained well below the values found at ground level and they were also strongly reduced (more than 10 times) by cockpit sun visors. Few studies have assessed the level of UV radiation in an airplane. They suggested that the cockpit windshields reduced this type of radiation to some degree (according mainly to the wavelength of the radiation and the nature of the windshield). Our study strongly confirms these results and suggests that increased incidence of melanoma and mortality by this type of illness found among pilots and airline cabin crews may not be related to in-flight UV radiation exposure.Cadilhac P, Bouton M-C, Cantegril M, Cardines C, Gisquet A, Kaufman N, Klerlein M. In-flight ultraviolet radiation on commercial airplanes. Aerosp Med Hum Perform 2017; 88(10):947-951.

Corona And Ultraviolet Equipment For Testing Materials

NASA Technical Reports Server (NTRS)

Laue, Eric G.

1993-01-01

Two assemblies of laboratory equipment developed for use in testing abilities of polymers, paints, and other materials to withstand ultraviolet radiation and charged particles. One is vacuum ultraviolet source built around commercial deuterium lamp. Other exposes specimen in partial vacuum to both ultraviolet radiation and brush corona discharge. Either or both assemblies used separately or together to simulate approximately combination of solar radiation and charged particles encountered by materials aboard spacecraft in orbit around Earth. Also used to provide rigorous environmental tests of materials exposed to artificial ultraviolet radiation and charged particles in industrial and scientific settings or to natural ultraviolet radiation and charged particles aboard aircraft at high altitudes.

TU-F-201-00: Radiochromic Film Dosimetry Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

Effects of solar ultraviolet radiation on coral reef organisms.

PubMed

Banaszak, Anastazia T; Lesser, Michael P

2009-09-01

Organisms living in shallow-water tropical coral reef environments are exposed to high UVR irradiances due to the low solar zenith angles (the angle of the sun from the vertical), the natural thinness of the ozone layer over tropical latitudes, and the high transparency of the water column. The hypothesis that solar ultraviolet radiation (UVR, 290-400 nm) is an important factor that affects the biology and ecology of coral reef organisms dates only to about 1980. It has been previously suggested that increased levels of biologically effective ultraviolet B radiation (UVB, 290-320 nm), which is the waveband primarily affected by ozone depletion, would have relatively small effects on corals and coral reefs and that these effects might be observed as changes in the minimum depths of occurrence of important reef taxa such as corals. This conclusion was based on predictions of increases in UVR as well as its attenuation with depth using the available data on UVR irradiances, ozone levels, and optical properties of the water overlying coral reefs. Here, we review the experimental evidence demonstrating the direct and indirect effects of UVR, both UVB and ultraviolet A (UVA, 320-400 nm) on corals and other reef associated biota, with emphasis on those studies conducted since 1996. Additionally, we re-examine the predictions made in 1996 for the increase in UVB on reefs with currently available data, assess whether those predictions were reasonable, and look at what changes might occur on coral reefs in the future as the multiple effects (i.e. increased temperature, hypercapnia, and ocean acidification) of global climate change continue.

QUALITY ASSURANCE AND SITE MANAGEMENT FOR PRIMENET AND URBAN ULTRAVIOLET RADIATION RESEARCH MONITORING PROGRAM.

EPA Science Inventory

Because exposure to ultraviolet (UV) radiation is an ecosystem stressor and poses a human health risk, the National Exposure Research Laboratory (NERL) has undertaken a research program to measure the intensity of UV-B radiation at various locations throughout the U.S. In Septem...

Radiation damage effects in far-ultraviolet filters, thin films, and substrates.

PubMed

Keffer, C E; Torr, M R; Zukic, M; Spann, J F; Torr, D G; Kim, J

1994-09-01

Advances in vacuum ultraviolet thin-film filter technology have been made through the use of filter designs with multilayers of materials such as Al(2)O(3), BaF(2), CaF(2), HfO(2), LaF(3), MgF(2), and SiO(2). Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 × 9 R(E) orbit will expose the instrument to approximately 250 krad of radiation. Because to our knowledge no previous studies have been made on the potential radiation damage of these materials in the thin-film format, we report on such an assessment here. Transmittances and reflectances of BaF(2), CaF(2), HfO(2), MgF(2), and SiO(2) thin films on MgF(2) substrates, Al(2)O(3) thin films on fused-silica substrates, uncoated fused silica and MgF(2), and four multilayer filters made from these materials were measured from 120 to 180 nm beforeand after irradiation by 250 krad from a (60)Co gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 to 300 nm indicates 2-5% radiation-induced absorption near 260 nm in some of the samples with MgF(2) substrates. From these measurements we conclude that far-ultraviolet filters made from the materials tested should experience less than 5% change from exposure to up to 250 krad of high-energy radiation in space applications.

Internal dosimetry technical basis manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-12-20

The internal dosimetry program at the Savannah River Site (SRS) consists of radiation protection programs and activities used to detect and evaluate intakes of radioactive material by radiation workers. Examples of such programs are: air monitoring; surface contamination monitoring; personal contamination surveys; radiobioassay; and dose assessment. The objectives of the internal dosimetry program are to demonstrate that the workplace is under control and that workers are not being exposed to radioactive material, and to detect and assess inadvertent intakes in the workplace. The Savannah River Site Internal Dosimetry Technical Basis Manual (TBM) is intended to provide a technical and philosophicalmore » discussion of the radiobioassay and dose assessment aspects of the internal dosimetry program. Detailed information on air, surface, and personal contamination surveillance programs is not given in this manual except for how these programs interface with routine and special bioassay programs.« less

Quantitative imaging for clinical dosimetry

NASA Astrophysics Data System (ADS)

Bardiès, Manuel; Flux, Glenn; Lassmann, Michael; Monsieurs, Myriam; Savolainen, Sauli; Strand, Sven-Erik

2006-12-01

Patient-specific dosimetry in nuclear medicine is now a legal requirement in many countries throughout the EU for targeted radionuclide therapy (TRT) applications. In order to achieve that goal, an increased level of accuracy in dosimetry procedures is needed. Current research in nuclear medicine dosimetry should not only aim at developing new methods to assess the delivered radiation absorbed dose at the patient level, but also to ensure that the proposed methods can be put into practice in a sufficient number of institutions. A unified dosimetry methodology is required for making clinical outcome comparisons possible.

PROBABILISTIC RISK ASSESSMENT FOR THE EFFECTS OF SOLAR ULTRAVIOLET RADIATION ON AMPHIBIANS

EPA Science Inventory

Several studies have demonstrated that exposure to solar ultraviolet (UV) radiation can cause elevated mortality and an increased prevalence of eye and limb malformations in developing amphibian larvae. From these observations scientists have hypothesized that recent increases in...

The measurement of radiation dose profiles for electron-beam computed tomography using film dosimetry.

PubMed

Zink, F E; McCollough, C H

1994-08-01

The unique geometry of electron-beam CT (EBCT) scanners produces radiation dose profiles with widths which can be considerably different from the corresponding nominal scan width. Additionally, EBCT scanners produce both complex (multiple-slice) and narrow (3 mm) radiation profiles. This work describes the measurement of the axial dose distribution from EBCT within a scattering phantom using film dosimetry methods, which offer increased convenience and spatial resolution compared to thermoluminescent dosimetry (TLD) techniques. Therapy localization film was cut into 8 x 220 mm strips and placed within specially constructed light-tight holders for placement within the cavities of a CT Dose Index (CTDI) phantom. The film was calibrated using a conventional overhead x-ray tube with spectral characteristics matched to the EBCT scanner (130 kVp, 10 mm A1 HVL). The films were digitized at five samples per mm and calibrated dose profiles plotted as a function of z-axis position. Errors due to angle-of-incidence and beam hardening were estimated to be less than 5% and 10%, respectively. The integral exposure under film dose profiles agreed with ion-chamber measurements to within 15%. Exposures measured along the radiation profile differed from TLD measurements by an average of 5%. The film technique provided acceptable accuracy and convenience in comparison to conventional TLD methods, and allowed high spatial-resolution measurement of EBCT radiation dose profiles.

The Latin American Biological Dosimetry Network (LBDNet).

PubMed

García, O; Di Giorgio, M; Radl, A; Taja, M R; Sapienza, C E; Deminge, M M; Fernández Rearte, J; Stuck Oliveira, M; Valdivia, P; Lamadrid, A I; González, J E; Romero, I; Mandina, T; Guerrero-Carbajal, C; ArceoMaldonado, C; Cortina Ramírez, G E; Espinoza, M; Martínez-López, W; Di Tomasso, M

2016-09-01

Biological Dosimetry is a necessary support for national radiation protection programmes and emergency response schemes. The Latin American Biological Dosimetry Network (LBDNet) was formally founded in 2007 to provide early biological dosimetry assistance in case of radiation emergencies in the Latin American Region. Here are presented the main topics considered in the foundational document of the network, which comprise: mission, partners, concept of operation, including the mechanism to request support for biological dosimetry assistance in the region, and the network capabilities. The process for network activation and the role of the coordinating laboratory during biological dosimetry emergency response is also presented. This information is preceded by historical remarks on biological dosimetry cooperation in Latin America. A summary of the main experimental and practical results already obtained by the LBDNet is also included. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit

2015-04-24

Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth’s surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 – 400 nm). The maximum irradiance of UV radiation was 45 W m{sup −2} on horizontal surface. The maximum irradiance ofmore » UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m{sup −2}.« less

Characterization of photoluminescence spectra from poly allyl diglycol carbonate (CR-39) upon excitation with the ultraviolet radiation of various wavelengths

NASA Astrophysics Data System (ADS)

El Ghazaly, M.; Al-Thomali, Talal A.

2013-04-01

The induced photoluminescence (PL) from the π-conjugated polymer poly allyl diglycol carbonate (PADC) (CR-39) upon excitation with the ultraviolet radiation of different wavelengths was investigated. The absorption and attenuation coefficients of PADC (CR-39) were recorded using a UV-visible spectrometer. It was found that the absorption and attenuation coefficients of the PADC (CR-39) exhibit a strong dependence on the wavelength of ultraviolet radiation. The PL spectra were measured with a Flormax-4 spectrofluorometer (Horiba). PADC (CR-39) samples were excited by ultraviolet radiation with wavelengths in the range from 260 to 420 nm and the corresponding PL emission bands were recorded. The obtained results show a strong correlation between the PL and the excitation wavelength of ultraviolet radiation. The position of the fluorescence emission band peak was red shifted starting from 300 nm, which was increased with the increase in the excitation wavelength. The PL yield and its band peak height were increased with the increase in the excitation wavelength till 290 nm, thereafter they decreased exponentially with the increase in the ultraviolet radiation wavelength. These new findings should be considered carefully during the use of the PADC (CR-39) in the scientific applications and in using PADC (CR-39) in eyeglasses.

Tea, coffee, and cocoa as ultraviolet radiation protectants for beet armyworm nucleopolyhedrovirus

USDA-ARS?s Scientific Manuscript database

The addition of 1% (wt/v) aqueous extracts of cocoa (Theobroma cacao L.) (Malvales: Malvaceae), coffee (Coffea arabica L.) (Gentianales: Rubiaceae), green, and black tea (Camellia sinensis L.) (Ericales: Theaceae) provided excellent ultraviolet (UV) radiation protection for the beet armyworm, Spodo...

Fundamental investigation of ultraviolet radiation effects in polymeric film-forming materials

NASA Technical Reports Server (NTRS)

Giori, C.; Yamauchi, T.; Llewellen, P.; Gilligan, J.

1974-01-01

A literature search from 1958 to present was conducted on the effect of ultraviolet radiation on polymeric materials, with particular emphasis on vacuum photolysis, mechanisms of degradation, and energy transfer phenomena. The literature from 1958 to 1968 was searched manually, while the literature from 1968 to present was searched by using a computerized keyword system. The primary objective was to provide the necessary background information for the design of new or modified materials with improved stability to the vacuum-radiation environment of space.

Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M.; Davis, Scott C.

Purpose: A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank dopedmore » with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. Results: The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. Conclusions: The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real

CytoBayesJ: software tools for Bayesian analysis of cytogenetic radiation dosimetry data.

PubMed

Ainsbury, Elizabeth A; Vinnikov, Volodymyr; Puig, Pedro; Maznyk, Nataliya; Rothkamm, Kai; Lloyd, David C

2013-08-30

A number of authors have suggested that a Bayesian approach may be most appropriate for analysis of cytogenetic radiation dosimetry data. In the Bayesian framework, probability of an event is described in terms of previous expectations and uncertainty. Previously existing, or prior, information is used in combination with experimental results to infer probabilities or the likelihood that a hypothesis is true. It has been shown that the Bayesian approach increases both the accuracy and quality assurance of radiation dose estimates. New software entitled CytoBayesJ has been developed with the aim of bringing Bayesian analysis to cytogenetic biodosimetry laboratory practice. CytoBayesJ takes a number of Bayesian or 'Bayesian like' methods that have been proposed in the literature and presents them to the user in the form of simple user-friendly tools, including testing for the most appropriate model for distribution of chromosome aberrations and calculations of posterior probability distributions. The individual tools are described in detail and relevant examples of the use of the methods and the corresponding CytoBayesJ software tools are given. In this way, the suitability of the Bayesian approach to biological radiation dosimetry is highlighted and its wider application encouraged by providing a user-friendly software interface and manual in English and Russian. Copyright © 2013 Elsevier B.V. All rights reserved.

MO-B-BRB-04: 3D Dosimetry in End-To-End Dosimetry QA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibbott, G.

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

How does solar ultraviolet-B radiation improve drought tolerance of silver birch (Betula pendula Roth.) seedlings?

PubMed

Robson, T Matthew; Hartikainen, Saara M; Aphalo, Pedro J

2015-05-01

We hypothesized that solar ultraviolet (UV) radiation would protect silver birch seedlings from the detrimental effects of water stress through a coordinated suite of trait responses, including morphological acclimation, improved control of water loss through gas exchange and hydraulic sufficiency. To better understand how this synergetic interaction works, plants were grown in an experiment under nine treatment combinations attenuating ultraviolet-A and ultraviolet-B (UVB) from solar radiation together with differential watering to create water-deficit conditions. In seedlings under water deficit, UV attenuation reduced height growth, leaf production and leaf length compared with seedlings receiving the full spectrum of solar radiation, whereas the growth and morphology of well-watered seedlings was largely unaffected by UV attenuation. There was an interactive effect of the treatment combination on water relations, which was more apparent as a change in the water potential at which leaves wilted or plants died than through differences in gas exchange. This suggests that changes occur in the cell wall elastic modulus or accumulation of osmolites in cells under UVB. Overall, the strong negative effects of water deficit are partially ameliorated by solar UV radiation, whereas well-watered silver birch seedlings are slightly disadvantaged by the solar UV radiation they receive. © 2014 John Wiley & Sons Ltd.

AFRRI Neutron Dosimetry and Radiobiology Conference

DTIC Science & Technology

1988-11-09

Neutron Dosimetry and Radiobiology 8 - 9 November 1988 Sponsored by Defense Nuclear Agency ARMED FORCES RADIOBIOLOGY RESEARCH INSTITUTE...neutron radiation is less amenable to amelioration by chemical radioprotectants and more difficult to assess by means of physical dosimetry . These...neutron dosimetry and radiobiology we have witnessed in the past several years,could not have been possible without the sustained efforts of many

Overview of the Radiation Dosimetry Experiment (RaD-X) flight mission

NASA Astrophysics Data System (ADS)

Mertens, Christopher J.

2016-11-01

The NASA Radiation Dosimetry Experiment (RaD-X) stratospheric balloon flight mission addresses the need to reduce the uncertainty in predicting human exposure to cosmic radiation in the aircraft environment. Measurements were taken that characterize the dosimetric properties of cosmic ray primaries, the ultimate source of aviation radiation exposure, and the cosmic ray secondary radiations that are produced and transported to aviation altitudes. In addition, radiation detectors were flown to assess their potential application to long-term, continuous monitoring of the aircraft radiation environment. RaD-X was successfully launched from Fort Sumner, New Mexico (34.5°N, 104.2°W), on 25 September 2015. Over 18 h of science data were obtained from a total of four different type dosimeters at altitudes above 20 km. The RaD-X flight mission was supported by laboratory radiation exposure testing of the balloon flight dosimeters and also by coordinated radiation measurements taken on ER-2 and commercial aircraft. This paper provides the science background and motivation for the RaD-X flight mission, a brief description of the balloon flight profile and the supporting aircraft flights, and a summary of the articles included in the RaD-X special collection and their contributions to the science goals of the RaD-X mission.

Overview of the Radiation Dosimetry Experiment (RaD-X) Flight Mission

NASA Technical Reports Server (NTRS)

Mertens, Christopher J.

2016-01-01

The NASA Radiation Dosimetry Experiment (RaD-X) stratospheric balloon flight mission addresses the need to reduce the uncertainty in predicting human exposure to cosmic radiation in the aircraft environment. Measurements were taken that characterize the dosimetric properties of cosmic ray primaries, the ultimate source of aviation radiation exposure, and the cosmic ray secondary radiations that are produced and transported to aviation altitudes. In addition, radiation detectors were flown to assess their potential application to long-term, continuous monitoring of the aircraft radiation environment. RaD-X was successfully launched from Fort Sumner, New Mexico (34.5 N, 104.2 W), on 25 September 2015. Over 18 h of science data were obtained from a total of four different type dosimeters at altitudes above 20 km. The RaD-X flight mission was supported by laboratory radiation exposure testing of the balloon flight dosimeters and also by coordinated radiation measurements taken on ER-2 and commercial aircraft. This paper provides the science background and motivation for the RaD-X flight mission, a brief description of the balloon flight profile and the supporting aircraft flights, and a summary of the articles included in the RaD-X special collection and their contributions to the science goals of the RaD-X mission.

Solar simulated ultraviolet radiation damages murine neonatal skin and alters Langerhans cell development, but does not induce inflammation.

PubMed

McGee, Heather M; Dharmadasa, Thanuja; Woods, Gregory M

2009-06-01

Development of melanoma has been linked to excessive childhood exposure to sunlight. As neonates have a relatively underdeveloped immune system, it is likely that the immune system reacts differently to the exposure, leading to alterations in this development. This study was designed to assess changes in development of the skin immune system following neonatal irradiation. Ultraviolet radiation exposure led to relative depletion of Langerhans cells, however this was not due to migration or cell death, but rather restriction of Langerhans cells populating the epidermis. During this time, there was evidence of cellular damage, however there was no induction of an inflammatory response. It therefore appears that neonatal exposure to ultraviolet radiation leads to a skew towards a tolerogenic immune response, which may lead to a reduced ability to respond to ultraviolet radiation-induced tumours.

Coral Skeletons Defend against Ultraviolet Radiation

PubMed Central

Reef, Ruth; Kaniewska, Paulina; Hoegh-Guldberg, Ove

2009-01-01

Background Many coral reef organisms are photosynthetic or have evolved in tight symbiosis with photosynthetic symbionts. As such, the tissues of reef organisms are often exposed to intense solar radiation in clear tropical waters and have adapted to trap and harness photosynthetically active radiation (PAR). High levels of ultraviolet radiation (UVR) associated with sunlight, however, represent a potential problem in terms of tissue damage. Methodology/Principal Findings By measuring UVR and PAR reflectance from intact and ground bare coral skeletons we show that the property of calcium carbonate skeletons to absorb downwelling UVR to a significant extent, while reflecting PAR back to the overlying tissue, has biological advantages. We placed cnidarians on top of bare skeletons and a UVR reflective substrate and showed that under ambient UVR levels, UVR transmitted through the tissues of cnidarians placed on top of bare skeletons were four times lower compared to their counterparts placed on a UVR reflective white substrate. In accordance with the lower levels of UVR measured in cnidarians on top of coral skeletons, a similar drop in UVR damage to their DNA was detected. The skeletons emitted absorbed UVR as yellow fluorescence, which allows for safe dissipation of the otherwise harmful radiation. Conclusions/Significance Our study presents a novel defensive role for coral skeletons and reveals that the strong UVR absorbance by the skeleton can contribute to the ability of corals, and potentially other calcifiers, to thrive under UVR levels that are detrimental to most marine life. PMID:19946361

Spectral transmission of the pig lens: effect of ultraviolet A+B radiation.

PubMed

Artigas, C; Navea, A; López-Murcia, M-M; Felipe, A; Desco, C; Artigas, J-M

2014-12-01

To determine the spectral transmission curve of the crystalline lens of the pig. To analyse how this curve changes when the crystalline lens is irradiated with ultraviolet A+B radiation similar to that of the sun. To compare these results with literature data from the human crystalline lens. We used crystalline lenses of the common pig from a slaughterhouse, i.e. genetically similar pigs, fed with the same diet, and slaughtered at six months old. Spectral transmission was measured with a Perkin-Elmer Lambda 35 UV/VIS spectrometer. The lenses were irradiated using an Asahi Spectra Lax-C100 ultraviolet source, which made it possible to select the spectral emission band as well as the intensity and exposure time. The pig lens transmits all the visible spectrum (95%) and lets part of the ultraviolet A through (15%). Exposure to acute UV (A+B) irradiation causes a decrease in its transmission as the intensity or exposure time increases: this decrease is considerable in the UV region. We were able to determine the mean spectral transmission curve of the pig lens. It appears to be similar to that of the human lens in the visible spectrum, but different in the ultraviolet. Pig lens transmission is reduced by UV (A+B) irradiation and its transmission in the UV region can even disappear as the intensity or exposure time increases. An adequate exposure intensity and time of UV (A+B) radiation always causes an anterior subcapsular cataract (ASC). Copyright © 2014. Published by Elsevier Masson SAS.

Effectiveness of eye drops protective against ultraviolet radiation.

PubMed

Daxer, A; Blumthaler, M; Schreder, J; Ettl, A

1998-01-01

To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation. The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness. The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively. The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.

INFLUENCE OF FLORAL OPTICAL PROPERTIES ON THE ULTRAVIOLET RADIATION ENVIRONMENT OF POLLEN

EPA Science Inventory

Pollen in unopened flowers of most species is totally screened from solar ultraviolet-B radiation by imbricated petals that are largely opaque to UV-B. Following flower opening but before another dehiscence, the anther walls of the species investigated filter out over 98% of the ...

Unexplained overexposures on physical dosimetry reported by biological dosimetry.

PubMed

Montoro, A; Almonacid, M; Villaescusa, J I; Verdu, G

2009-01-01

The Medical Service of the Radiation Protection Service from the University Hospital La Fe (Valencia, Spain), carries out medical examinations of the workers occupationally exposed to ionising radiation. The Biological Dosimetry Laboratory is developing its activity since 2001. Up to now, the activities have been focused in performing biological dosimetry studies of Interventionists workers from La Fe Hospital. Recently, the Laboratory has been authorized by the Health Authority in the Valencian Community. Unexplained overexposures of workers and patients are also studied. Workers suspected of being overexposed to ionising radiation were referred for investigation by cytogenetic analysis. Two of these were from Hospitals of the Valencian Community and one belonged to an uranium mine from Portugal. Hospital workers had a physical dose by thermoluminiscence dosimeters (TLD) that exceeded the established limit. The worker of the uranium mine received a dose from a lost source of Cesium 137 with an activity of 170 mCi. All three cases showed normal values after the hematological analysis. Finally, the aim of this study consist to determine whether the dose showed by the dosimeter is reliable or not. In the case of workers that wore dosimeter, it is concluded that the doses measured by dosimeter are not corresponding to real doses. Hospital worker with a physical dose of 2.6 Sv and 0.269 Sv had an estimated absorbed dose by biological dosimetry of 0.076 Gy (0-0.165 Gy) and 0 Gy (0-0.089 Gy), respectively. In case of the mine worker an estimated absorbed dose of 0.073 Gy (0-0.159 Gy) was obtained by biological dosimetry. In all cases we used the odds ratio to present the results due to a very low frequency of observed aberrations [1].

Bibliographical database of radiation biological dosimetry and risk assessment: Part 1, through June 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Straume, T.; Ricker, Y.; Thut, M.

1988-08-29

This database was constructed to support research in radiation biological dosimetry and risk assessment. Relevant publications were identified through detailed searches of national and international electronic databases and through our personal knowledge of the subject. Publications were numbered and key worded, and referenced in an electronic data-retrieval system that permits quick access through computerized searches on publication number, authors, key words, title, year, and journal name. Photocopies of all publications contained in the database are maintained in a file that is numerically arranged by citation number. This report of the database is provided as a useful reference and overview. Itmore » should be emphasized that the database will grow as new citations are added to it. With that in mind, we arranged this report in order of ascending citation number so that follow-up reports will simply extend this document. The database cite 1212 publications. Publications are from 119 different scientific journals, 27 of these journals are cited at least 5 times. It also contains reference to 42 books and published symposia, and 129 reports. Information relevant to radiation biological dosimetry and risk assessment is widely distributed among the scientific literature, although a few journals clearly dominate. The four journals publishing the largest number of relevant papers are Health Physics, Mutation Research, Radiation Research, and International Journal of Radiation Biology. Publications in Health Physics make up almost 10% of the current database.« less

Lanthanum (III) regulates the nitrogen assimilation in soybean seedlings under ultraviolet-B radiation.

PubMed

Huang, Guangrong; Wang, Lihong; Zhou, Qing

2013-01-01

Ultraviolet-B (UV-B, 280-320 nm) radiation has seriously affected the growth of plants. Finding the technology/method to alleviate the damage of UV-B radiation has become a frontal topic in the field of environmental science. The pretreatment with rare earth elements (REEs) is an effective method, but the regulation mechanism of REEs is unknown. Here, the regulation effects of lanthanum (La(III)) on nitrogen assimilation in soybean seedlings (Glycine max L.) under ultraviolet-B radiation were investigated to elucidate the regulation mechanism of REEs on plants under UV-B radiation. UV-B radiation led to the inhibition in the activities of the key enzymes (nitrate reductase, glutamine synthetase, glutamate synthase) in the nitrogen assimilation, the decrease in the contents of nitrate and soluble proteins, as well as the increase in the content of amino acid in soybean seedlings. The change degree of UV-B radiation at the high level (0.45 W m(-2)) was higher than that of UV-B radiation at the low level (0.15 W m(-2)). The pretreatment with 20 mg L(-1) La(III) could alleviate the effects of UV-B radiation on the activities of nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase, promoting amino acid conversion and protein synthesis in soybean seedlings. The regulation effect of La(III) under UV-B radiation at the low level was better than that of UV-B radiation at the high level. The results indicated that the pretreatment with 20 mg L(-1) La(III) could alleviate the inhibition of UV-B radiation on nitrogen assimilation in soybean seedlings.

Technical basis for external dosimetry at the Waste Isolation Pilot Plant (WIPP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, E.W.; Wu, C.F.; Goff, T.E.

1993-12-31

The WIPP External Dosimetry Program, administered by Westinghouse Electric Corporation, Waste Isolation Division, for the US Department of Energy (DOE), provides external dosimetry support services for operations at the Waste Isolation Pilot Plant (WIPP) Site. These operations include the receipt, experimentation with, storage, and disposal of transuranic (TRU) wastes. This document describes the technical basis for the WIPP External Radiation Dosimetry Program. The purposes of this document are to: (1) provide assurance that the WIPP External Radiation Dosimetry Program is in compliance with all regulatory requirements, (2) provide assurance that the WIPP External Radiation Dosimetry Program is derived from amore » sound technical base, (3) serve as a technical reference for radiation protection personnel, and (4) aid in identifying and planning for future needs. The external radiation exposure fields are those that are documented in the WIPP Final Safety Analysis Report.« less

Basal cell carcinoma of the eyelids and solar ultraviolet radiation exposure

PubMed Central

Lindgren, G.; Diffey, B.; Larko, O.

1998-01-01

AIMS—To compare the distribution of eyelid basal cell carcinoma (BCC) with the relative ultraviolet radiation (UVR) exposure to different sites on the eyelids.
METHODS—The location of BCC on the eyelids was allocated to one of seven regions. The UVR exposure was recorded with a polymer film attached to the eyelids at seven sites in a manikin and in human subjects.
RESULTS—Localisation of the 329 tumours was mainly on the lower eyelids (225 tumours), and the medial canthal regions (87 tumours). There was no association between UVR doses at the seven sites of the eyelids and the location of BCCs. The UVR exposure was similar on the upper and lower eyelids, while the number of tumours on the lower eyelids outnumbered the upper lids by a factor of 13 (17 upper, 225 lower)
CONCLUSION—UVR exposure only partially explains the aetiology of periorbital BCC.

 Keywords: polysulphone film; basal cell carcinoma; ultraviolet radiation; eyelid PMID:9930273

A study on resistance to ultraviolet radiation of POSS-TiO2/epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Peng, Dequn; Qin, Wei; Wu, Xiaohong

2015-06-01

Ultraviolet (UV) radiation is a severe space environmental factor, which is harmful to the durability of the polymeric materials of the spacecraft. For this reason, a novel POSS-TiO2/EP nanocomposite was synthesized by incorporating the POSS-TiO2 organic-inorganic hybrid into the epoxy (EP) resin. The effects of UV radiation on EP resin and on POSS-TiO2/EP nanocomposites were investigated in a ground-based simulator that simulates space radiation conditions. Compared with EP resin, the value of bend strength for 5.0 wt% POSS-TiO2/EP varied in a small range before and after UV radiation. Meanwhile, a typical tough feature was observed from the SEM photo for POSS-TiO2/EP nanocomposite after UV exposure. This result indicated that the POSS-TiO2/EP exhibited the excellent properties of anti-space ultraviolet radiation. The thermo gravimetric (TG) results showed that the addition of POSS-TiO2 improved the thermal-stability of EP resin matrix. The synthesized nanocomposites in this work could be used in the satellites to enhance their adaptability to the space environment and extend their service life.

Micro-Raman spectroscopy study of the effect of Mid-Ultraviolet radiation on erythrocyte membrane.

PubMed

Li, N; Li, S X; Guo, Z Y; Zhuang, Z F; Li, R; Xiong, K; Chen, S J; Liu, S H

2012-07-02

Mid-Ultraviolet (UVB) has a significant influence on human health. In this study, human erythrocytes were exposed to UVB to investigate the effects of UVB radiation on erythrocytes membrane. And Micro-Raman spectroscopy was employed to detect the damage. Principal component analysis (PCA) was used to classify the control erythrocytes and the irradiated erythrocytes. Results showed that the erythrocytes membrane was damaged by Mid-Ultraviolet (UVB) radiation. The intensity of the Raman peaks at 1126 cm(-1) and 1082 cm(-1) were used to calculate the Longitudinal Order-Parameters in Chains (S(trans)) which can present the liquidity and ionic permeability of erythrocyte membrane. After UVB radiation for 30 min, both the liquidity and ionic permeability decreased. At the same time, the intensity of the peaks at 1302 cm(-1) (α-helix), 1254 cm(-1) (random coil), 1452 cm(-1) and 1430 cm(-1) (CH(2)/CH(3) stretch) have also changed which indicated the membrane protein also been damaged by UVB. In the whole process of radiation, the more UVB radiation dose the more damage on the erythrocyte membrane. Copyright © 2012 Elsevier B.V. All rights reserved.

Outdoor Exposure to Solar Ultraviolet Radiation and Legislation in Brazil.

PubMed

Silva, Abel A

2016-06-01

The total ozone column of 265 ± 11 Dobson Units in the tropical-equatorial zones and 283 ± 16 Dobson Units in the subtropics of Brazil are among the lowest on Earth, and as a result, the prevalence of skin cancer due to solar ultraviolet radiation is among the highest. Daily erythemal doses in Brazil can be over 7,500 J m. Erythemal dose rates on cloudless days of winter and summer are typically about 0.147 W m and 0.332 W m, respectively. However, radiation enhancement events yielded by clouds have been reported with erythemal dose rates of 0.486 W m. Daily doses of the diffuse component of erythemal radiation have been determined with values of 5,053 J m and diffuse erythemal dose rates of 0.312 W m. Unfortunately, Brazilians still behave in ways that lead to overexposure to the sun. The annual personal ultraviolet radiation ambient dose among Brazilian youths can be about 5.3%. Skin cancer in Brazil is prevalent, with annual rates of 31.6% (non-melanoma) and 1.0% (melanoma). Governmental and non-governmental initiatives have been taken to increase public awareness of photoprotection behaviors. Resolution #56 by the Agência Nacional de Vigilância Sanitária has banned tanning devices in Brazil. In addition, Projects of Law (PL), like PL 3730/2004, propose that the Sistema Único de Saúde should distribute sunscreen to members of the public, while PL 4027/2012 proposes that employers should provide outdoor workers with sunscreen during professional outdoor activities. Similar laws have already been passed in some municipalities. These are presented and discussed in this study.

Application of spectroscopic techniques in the radiation dosimetry of glasses: An update

NASA Astrophysics Data System (ADS)

Natarajan, V.

2009-07-01

The colorimetry and thermoluminescence properties of gamma irradiated glass were reported in as early as 1920. The utility of radio-photoluminescence (RPL) of silver activated metaphosphate glass for monitoring high doses of accidental and routine gamma radiation was reported in the 1960s. Since then considerable amount of research work has been carried out to study the thermoluminescence (TL), optical absorption (OA), electron paramagnetic resonance (EPR) and optically stimulated luminescence (OSL) of different commercially available glasses for high as well as low dose applications. A brief review of the progress made in the spectroscopic studies of glasses during the past few decades and the application of glasses for radiation dosimetry has been given in this paper.

A geometric ultraviolet-B radiation transfer model applied to vegetation canopies

Treesearch

Wei Gao; Richard H. Grant; Gordon M. Heisler; James R. Slusser

2002-01-01

The decrease in stratospheric ozone (O3) has prompted continued efforts to assess the potential damage to plant and animal life due to enhanced levels of solar ultraviolet (UV)-B (280-320 nm) radiation. The objective of this study was to develop and evaluate an analytical model to simulate the UV-B irradiance loading on horizontal below- canopy...

RCT: Module 2.04, Dosimetry, Course 8769

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillmer, Kurt T.

This course will introduce the types of instruments used to measure external and internal radiation to people. Dosimetry is the quantitative assessment of radiation received by the human body. Several types of dosimeters are used worldwide. This information is valuable to all radiological control personnel because dosimeters are the only direct method to measure and document personnel radiation exposure and ensure regulatory compliance with applicable limits. This course will cover dosimetry terms, Department of Energy (DOE) limits, Los Alamos National Laboratory (LANL) administrative guidelines, thermoluminescent dosimeters (TLDs), LANL dosimetry, and bioassay assessment methods. This course will prepare the student withmore » the skills necessary for radiological control technician (RCT) qualification by passing quizzes, tests, and the RCT Comprehensive Phase 1, Unit 2 Examination (TEST 27566) and providing in-thefield skills.« less

Biodistribution and Radiation Dosimetry for the Novel SV2A Radiotracer [(18)F]UCB-H: First-in-Human Study.

PubMed

Bretin, F; Bahri, M A; Bernard, C; Warnock, G; Aerts, J; Mestdagh, N; Buchanan, T; Otoul, C; Koestler, F; Mievis, F; Giacomelli, F; Degueldre, C; Hustinx, R; Luxen, A; Seret, A; Plenevaux, A; Salmon, E

2015-08-01

[(18)F]UCB-H is a novel radiotracer with a high affinity for synaptic vesicle glycoprotein 2A (SV2A), a protein expressed in synaptic vesicles. SV2A is the binding site of levetiracetam, a "first-in-class" antiepileptic drug with a distinct but still poorly understood mechanism of action. The objective of this study was to determine the biodistribution and radiation dosimetry of [(18)F]UCB-H in a human clinical trial and to establish injection limits according to biomedical research guidelines. Additionally, the clinical radiation dosimetry results were compared to estimations in previously published preclinical data. Dynamic whole body positron emission tomography/X-ray computed tomography (PET/CT) imaging was performed over approximately 110 min on five healthy male volunteers after injection of 144.5 ± 7.1 MBq (range, 139.1-156.5 MBq) of [(18)F]UCB-H. Major organs were delineated on CT images, and time-activity curves were obtained from co-registered dynamic PET emission scans. The bladder could only be delineated on PET images. Time-integrated activity coefficients were calculated as area under the curve using trapezoidal numerical integration. Urinary excretion data based on PET activities including voiding was also simulated using the dynamic bladder module of OLINDA/EXM. The radiation dosimetry was calculated using OLINDA/EXM. The effective dose to the OLINDA/EXM 70-kg standard male was 1.54 × 10(-2) ± 6.84 × 10(-4) millisieverts (mSv)/MBq, with urinary bladder wall, gallbladder wall, and the liver receiving the highest absorbed dose. The brain, the tracer's main organ of interest, received an absorbed dose of 1.89 × 10(-2) ± 2.32 × 10(-3) mGy/MBq. This first human dosimetry study of [(18)F]UCB-H indicated that the tracer shows similar radiation burdens to widely used common clinical tracers. Single injections of at maximum 672 MBq for US practice and 649 MBq for European practice keep radiation exposure below

Workshop Report on Atomic Bomb Dosimetry--Review of Dose Related Factors for the Evaluation of Exposures to Residual Radiation at Hiroshima and Nagasaki.

PubMed

Kerr, George D; Egbert, Stephen D; Al-Nabulsi, Isaf; Bailiff, Ian K; Beck, Harold L; Belukha, Irina G; Cockayne, John E; Cullings, Harry M; Eckerman, Keith F; Granovskaya, Evgeniya; Grant, Eric J; Hoshi, Masaharu; Kaul, Dean C; Kryuchkov, Victor; Mannis, Daniel; Ohtaki, Megu; Otani, Keiko; Shinkarev, Sergey; Simon, Steven L; Spriggs, Gregory D; Stepanenko, Valeriy F; Stricklin, Daniela; Weiss, Joseph F; Weitz, Ronald L; Woda, Clemens; Worthington, Patricia R; Yamamoto, Keiko; Young, Robert W

2015-12-01

Groups of Japanese and American scientists, supported by international collaborators, have worked for many years to ensure the accuracy of the radiation dosimetry used in studies of health effects in the Japanese atomic bomb survivors. Reliable dosimetric models and systems are especially critical to epidemiologic studies of this population because of their importance in the development of worldwide radiation protection standards. While dosimetry systems, such as Dosimetry System 1986 (DS86) and Dosimetry System 2002 (DS02), have improved, the research groups that developed them were unable to propose or confirm an additional contribution by residual radiation to the survivor's total body dose. In recognition of the need for an up-to-date review of residual radiation exposures in Hiroshima and Nagasaki, a half-day technical session was held for reports on newer studies at the 59 th Annual HPS Meeting in 2014 in Baltimore, MD. A day-and-a-half workshop was also held to provide time for detailed discussion of the newer studies and to evaluate their potential use in clarifying the residual radiation exposure to atomic bomb survivors at Hiroshima and Nagasaki. The process also involved a re-examination of very early surveys of radioisotope emissions from ground surfaces at Hiroshima and Nagasaki and early reports of health effects. New insights were reported on the potential contribution to residual radiation from neutron-activated radionuclides in the airburst's dust stem and pedestal and in unlofted soil, as well as from fission products and weapon debris from the nuclear cloud. However, disparate views remain concerning the actual residual radiation doses received by the atomic bomb survivors at different distances from the hypocenter. The workshop discussion indicated that measurements made using thermal luminescence and optically stimulated luminescence, like earlier measurements, especially in very thin layers of the samples, could be expanded to detect possible

Ocean Acidification Alters the Photosynthetic Responses of a Coccolithophorid to Fluctuating Ultraviolet and Visible Radiation1[OPEN

PubMed Central

Jin, Peng; Gao, Kunshan; Villafañe, Virginia E.; Campbell, Douglas A.; Helbling, E. Walter

2013-01-01

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400–700 nm) and ultraviolet radiation (UVR; 280–400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO2 levels, under regimes of fluctuating irradiances with or without UVR. Under both CO2 levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO2 showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280–315 nm)-induced inhibition. Ultraviolet A (315–400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO2-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition. PMID:23749851

Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

PubMed

Thompson, Jeroen W; Burdette, Kevin E; Inrig, Elizabeth L; Dewitt, Regina; Mistry, Rajesh; Rink, W Jack; Boreham, Douglas R

2010-09-01

Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d.

UNLAMINATED GAFCHROMIC EBT3 FILM FOR ULTRAVIOLET RADIATION MONITORING.

PubMed

Welch, David; Randers-Pehrson, Gerhard; Spotnitz, Henry M; Brenner, David J

2017-11-01

Measurement of ultraviolet (UV) radiation is important for human health, especially with the expanded usage of short wavelength UV for sterilization purposes. This work examines unlaminated Gafchromic EBT3 film for UV radiation monitoring. The authors exposed the film to select wavelengths in the UV spectrum, ranging from 207 to 328 nm, and measured the change in optical density. The response of the film is wavelength dependent, and of the wavelengths tested, the film was most sensitive to 254 nm light, with measurable values as low as 10 µJ/cm2. The film shows a dose-dependent response that extends over more than four orders of magnitude. The response of the film to short wavelength UV is comparable to the daily safe exposure limits for humans, thus making it valuable as a tool for passive UV radiation monitoring. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

TU-F-201-01: General Aspects of Radiochromic Film Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niroomand-Rad, A.

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

Radiation dosimetry measurements during U.S. Space Shuttle missions with the RME-III.

PubMed

Golightly, M J; Hardy, K; Quam, W

1994-01-01

Time-resolved radiation dosimetry measurements inside the crew compartment have been made during recent Shuttle missions with the U.S. Air Force Radiation Monitoring Equipment-III (RME-III), a portable battery-powered four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. Half of the missions had orbital inclinations of 28.5 degrees with the remainder at inclinations of 57 degrees or greater; altitudes ranged from 300 to 600 km. The determined dose equivalent rates ranged from 70 to 5300 microSv/day. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicles. Measurements indicate that medium- and high-LET particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isocontours of fluence, dose and dose equivalent rate have been developed from measurements made during the STS-28 mission. The drift rate of the South Atlantic Anomaly is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and GCR dose for the STS-28 mission was significantly lower than the measured values.

Epidemiologic evidence for different roles of ultraviolet A and B radiation in melanoma mortality rates.

PubMed

Garland, Cedric F; Garland, Frank C; Gorham, Edward D

2003-07-01

The action spectrum of ultraviolet radiation mainly responsible for melanoma induction is unknown, but evidence suggests it could be ultraviolet A (UVA), which has a different geographic distribution than ultraviolet B (UVB). This study assessed whether melanoma mortality rates are more closely related to the global distribution of UVA or UVB. UVA and UVB radiation and age-adjusted melanoma mortality rates were obtained for all 45 countries reporting cancer data to the World Health Organization. Stratospheric ozone data were obtained from NASA satellites. Average population skin pigmentation was obtained from skin reflectometry measurements. Paradoxically, melanoma mortality rates decreased with increasing UVB in men (r = -0.48, p < 0.001), and women (r = -0.57, p < 0.001), and with increasing UVA in both sexes. By contrast, rates were positively associated with increasing UVA/UVB ratio in men (r = + 0.49, p < 0.001) and women (r = + 0.55, p < 0.001). After multiple adjustment that included controlling for skin pigmentation, only UVA was associated with melanoma mortality rates in men (p < 0.02) with a suggestive but non-significant trend present in women (p = 0.12). UVA radiation was associated with melanoma mortality rates after controlling for UVB and average pigmentation. The results require confirmation in observational studies.

Ultraviolet radiation-blocking characteristics of contact lenses: relevance to eye protection for psoralen-sensitised patients.

PubMed

Anstey, A; Taylor, D; Chalmers, I; Ansari, E

1999-10-01

Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.

Influence of tropospheric ozone control on exposure to ultraviolet radiation at the surface.

PubMed

Madronich, Sasha; Wagner, Mark; Groth, Philip

2011-08-15

Improving air quality by reducing ambient ozone (O(3)) will likely lower O(3) concentrations throughout the troposphere and increase the transmission of solar ultraviolet (UV) radiation to the surface. The changes in surface UV radiation between two control scenarios (nominally 84 and 70 ppb O(3) for summer 2020) in the Eastern two-thirds of the contiguous U.S. are estimated, using tropospheric O(3) profiles calculated with a chemistry-transport model (Community Multi-Scale Air Quality, CMAQ) as inputs to a detailed model of the transfer of solar radiation through the atmosphere (tropospheric ultraviolet-visible, TUV) for clear skies, weighed for the wavelengths known to induce sunburn and skin cancer. Because the incremental emission controls differ according to region, strong spatial variability in O(3) reductions and in corresponding UV radiation increments is seen. The geographically averaged UV increase is 0.11 ± 0.03%, whereas the population-weighted increase is larger, 0.19 ± 0.06%, because O(3) reductions are greater in more densely populated regions. These relative increments in exposure are non-negligible given the already high incidence of UV-related health effects, but are lower by an order of magnitude or more than previous estimates.

PREFACE: Third International Conference on Radiotherapy Gel Dosimetry

NASA Astrophysics Data System (ADS)

DeDeene, Yves; Baldock, Clive

2004-01-01

Gel dosimetry is not merely another dosimetry technique. Gel dosimeters are integrating dosimeters that enable dose verification in three dimensions. The application of a 3D dosimetry technique in the clinic would give a real push to the implementation of advanced high-precision radiotherapy technologies in many institutes. It can be expected that with the recent developments in the field towards more user-friendly gel systems and imaging modalities, gel dosimetry will become a vital link in the chain of high-precision radiation cancer therapy in the near future. Many researchers all over the world have contributed to the emerging technology of gel dosimetry. The research field of gel dosimetry is recognized to be very broad from polymer and analytical chemistry and material research to imaging technologies. The DOSGEL conferences in the past have proven to be an important forum at which material scientists, chemists, medical physicists, magnetic resonance imaging and radiation specialists brought together a critical mass of thoughts, findings and considerations. DOSGEL 2004 has been endorsed by many international, supra-national and national medical physics organizations and publishers. These proceedings contain 51 papers that cover various aspects of gel dosimetry.

Changes in Occupational Radiation Exposures after Incorporation of a Real-time Dosimetry System in the Interventional Radiology Suite.

PubMed

Poudel, Sashi; Weir, Lori; Dowling, Dawn; Medich, David C

2016-08-01

A statistical pilot study was retrospectively performed to analyze potential changes in occupational radiation exposures to Interventional Radiology (IR) staff at Lawrence General Hospital after implementation of the i2 Active Radiation Dosimetry System (Unfors RaySafe Inc, 6045 Cochran Road Cleveland, OH 44139-3302). In this study, the monthly OSL dosimetry records obtained during the eight-month period prior to i2 implementation were normalized to the number of procedures performed during each month and statistically compared to the normalized dosimetry records obtained for the 8-mo period after i2 implementation. The resulting statistics included calculation of the mean and standard deviation of the dose equivalences per procedure and included appropriate hypothesis tests to assess for statistically valid differences between the pre and post i2 study periods. Hypothesis testing was performed on three groups of staff present during an IR procedure: The first group included all members of the IR staff, the second group consisted of the IR radiologists, and the third group consisted of the IR technician staff. After implementing the i2 active dosimetry system, participating members of the Lawrence General IR staff had a reduction in the average dose equivalence per procedure of 43.1% ± 16.7% (p = 0.04). Similarly, Lawrence General IR radiologists had a 65.8% ± 33.6% (p=0.01) reduction while the technologists had a 45.0% ± 14.4% (p=0.03) reduction.

Absorbed radiation dosimetry of the D3-specific PET radioligand [18F]FluorTriopride estimated using rodent and nonhuman primate.

PubMed

Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

2016-01-01

[ 18 F]FluorTriopride ([ 18 F]FTP) is a dopamine D 3 -receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [ 18 F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [ 18 F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [ 18 F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [ 18 F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination.

Absorbed radiation dosimetry of the D3-specific PET radioligand [18F]FluorTriopride estimated using rodent and nonhuman primate

PubMed Central

Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

2016-01-01

[18F]FluorTriopride ([18F]FTP) is a dopamine D3-receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [18F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [18F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [18F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [18F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination. PMID:28078183

Quantifying the effects of corn growth and physiological responses to Ultraviolet-B radiation for modeling

USDA-ARS?s Scientific Manuscript database

To understand the consequences of rising levels of Ultraviolet-B (UV-B) radiation on maize (Zea mays L.), two experiments were conducted using sunlit plant growth chambers at a wide range UV-B radiation. Maize cultivars Terral-2100 and DKC 65-44 were grown in 2003 and 2008, respectively, at four le...

The Mayak Worker Dosimetry System (Mwds-2013): An Introduction to The Documentation

DOE PAGES

Napier, B. A.

2017-03-17

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. Here, this introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

The Mayak Worker Dosimetry System (Mwds-2013): An Introduction to The Documentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B. A.

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. Here, this introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

Wavelength of ultraviolet radiation that enhances onset of clinical infectious bovine keratoconjunctivitis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopecky, K.E.; Pugh, G.W. Jr.; Hughes, D.E.

1980-09-01

Cellulose acetate filtered ultraviolet (uv) radiation and unfiltered uv radiation were used on calves that were subsequently challenge exposed with Moraxella bovis. The onset, course, and severity of infectious bovine keratoconjunctivitis (IBK) were studied. Ten calves irradiated with unfiltered uv had the disease 1 to 2 days after M bovis challenge exposure. Ten calves irradiated with filtered uv and 10 calves not irradiated manifested IBK in a similar manner. Evidence is presented to support the contention that the wavelengths (around 270 nm) which are eliminated by cellulose acetate enhance the course of IBK. The effects on IBK of environmentally increasedmore » solar uv radiation is also discussed.« less

Dosimetry procedures for an industrial irradiation plant

NASA Astrophysics Data System (ADS)

Grahn, Ch.

Accurate and reliable dosimetry procedures constitute a very important part of process control and quality assurance at a radiation processing plant. γ-Dose measurements were made on the GBS 84 irradiator for food and other products on pallets or in containers. Chemical dosimeters wre exposed in the facility under conditions of the typical plant operation. The choice of the dosimeter systems employed was based on the experience in chemical dosimetry gained over several years. Dose uniformity information was obtained in air, spices, bulbs, feeds, cosmetics, plastics and surgical goods. Most products currently irradiated require dose uniformity which can be efficiently provided by pallet or box irradiators like GBS 84. The radiation performance characteristics and some dosimetry procedures are discussed.

Specific issues in small animal dosimetry and irradiator calibration

PubMed Central

Yoshizumi, Terry; Brady, Samuel L.; Robbins, Mike E.; Bourland, J. Daniel

2013-01-01

Purpose In response to the increased risk of radiological terrorist attack, a network of Centers for Medical Countermeasures against Radiation (CMCR) has been established in the United States, focusing on evaluating animal model responses to uniform, relatively homogenous whole- or partial-body radiation exposures at relatively high dose rates. The success of such studies is dependent not only on robust animal models but on accurate and reproducible dosimetry within and across CMCR. To address this issue, the Education and Training Core of the Duke University School of Medicine CMCR organised a one-day workshop on small animal dosimetry. Topics included accuracy in animal dosimetry accuracy, characteristics and differences of cesium-137 and X-ray irradiators, methods for dose measurement, and design of experimental irradiation geometries for uniform dose distributions. This paper summarises the information presented and discussed. Conclusions Without ensuring accurate and reproducible dosimetry the development and assessment of the efficacy of putative countermeasures will not prove successful. Radiation physics support is needed, but is often the weakest link in the small animal dosimetry chain. We recommend: (i) A user training program for new irradiator users, (ii) subsequent training updates, and (iii) the establishment of a national small animal dosimetry center for all CMCR members. PMID:21961967

New advances in protection against solar ultraviolet radiation in textiles for summer clothing.

PubMed

Aguilera, José; de Gálvez, María Victoria; Sánchez-Roldán, Cristina; Herrera-Ceballos, Enrique

2014-01-01

Clothing is considered one of the most important tools for photoprotection against harmful solar ultraviolet radiation (UVR). The standard for sun-protective clothing is based on erythema despite other biological effects of UVR on the skin. We analyzed the potential protection against UVR in fabrics destined for summer clothing based on several action spectra. We examined 50 garments classified by type of fabric composition, structure of the fiber yarn and color. The ultraviolet protection factor was calculated based on fabric ultraviolet transmittance corrected for erythema according to the EU standard E-13758 as well as the UVA transmittance of fabrics. UVR protection was also analyzed in base of different action spectra as for previtamin D3, nonmelanoma skin cancer, photoimmunosuppression and photoaging. Most knitted fabrics used for sports T-shirts offered excellent ratings for ultraviolet protection while normal shirts showed very low ratings, particularly against photoaging. The cover is the most influential variable in fabric photoprotection, having an exponential relationship with the UPF. The relation between cover and UVA protection was linearly negative. Information about ultraviolet protection in textiles used for summer clothing should be included in labeling as some types of fabrics, especially those used for shirts, offer very low UVR protection. © 2014 The American Society of Photobiology.

SEURAT: SPH scheme extended with ultraviolet line radiative transfer

NASA Astrophysics Data System (ADS)

Abe, Makito; Suzuki, Hiroyuki; Hasegawa, Kenji; Semelin, Benoit; Yajima, Hidenobu; Umemura, Masayuki

2018-05-01

We present a novel Lyman alpha (Ly α) radiative transfer code, SEURAT (SPH scheme Extended with Ultraviolet line RAdiative Transfer), where line scatterings are solved adaptively with the resolution of the smoothed particle hydrodynamics (SPH). The radiative transfer method implemented in SEURAT is based on a Monte Carlo algorithm in which the scattering and absorption by dust are also incorporated. We perform standard test calculations to verify the validity of the code; (i) emergent spectra from a static uniform sphere, (ii) emergent spectra from an expanding uniform sphere, and (iii) escape fraction from a dusty slab. Thereby, we demonstrate that our code solves the {Ly} α radiative transfer with sufficient accuracy. We emphasize that SEURAT can treat the transfer of {Ly} α photons even in highly complex systems that have significantly inhomogeneous density fields. The high adaptivity of SEURAT is desirable to solve the propagation of {Ly} α photons in the interstellar medium of young star-forming galaxies like {Ly} α emitters (LAEs). Thus, SEURAT provides a powerful tool to model the emergent spectra of {Ly} α emission, which can be compared to the observations of LAEs.

History of International Workshop on Mini-Micro- and Nano- Dosimetry (MMND) and Innovation Technologies in Radiation Oncology (ITRO)

NASA Astrophysics Data System (ADS)

Rosenfeld, Anatoly B.; Zaider, Marco; Yamada, Josh; Zelefsky, Michael J.

2017-01-01

The biannual MMND (former MMD) - IPCT workshops was founded in collaboration between the Centre for Medical Radiation Physics, University of Wollongong and the Memorial Sloan Kettering Cancer Center (MSKCC) in 2001 and has become an important international multidisciplinary forum for the discussion of advanced quality assurance (QA) dosimetry technology for radiation therapy and space science, as well as advanced technologies for clinical cancer treatment.

Occupational skin cancer induced by ultraviolet radiation and its prevention.

PubMed

Diepgen, T L; Fartasch, M; Drexler, H; Schmitt, J

2012-08-01

Skin cancer is by far the most common kind of cancer diagnosed in many western countries and ultraviolet radiation is the most important risk factor for cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Although employees at several workplaces are exposed to increased levels of UV radiation, skin cancer due to long-term intense occupational exposure to UV radiation is often not considered as occupational disease. The actually available evidence in the epidemiological literature clearly indicates that occupational UV radiation exposure is a substantial and robust risk factor for the development of cutaneous SCC and also clearly shows a significant risk for developing BCC. There is enough scientific evidence that outdoor workers have an increased risk of developing work-related occupational skin cancer due to natural UV radiation exposure and adequate prevention strategies must be implemented. The three measures which are successful and of particular importance in the prevention of nonmelanoma skin cancer in outdoor workers are changes in behaviour regarding awareness of health and disease resulting from exposure to natural UV radiation, protection from direct UV radiation by wearing suitable clothing, and regular and correct use of appropriate sunscreens. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.

Radiation Dosimetry Experiment (RaD-X): High-Altitude Balloon Flight Mission for Improving the NAIRAS Model

NASA Technical Reports Server (NTRS)

Mertens, Christopher J.; Alston, Erica J.; Straume, Tore; Gersey, Brad; Lusby, Terry C.; Norman, Ryan B.; Gronoff, Guillaume P.; Tobiska, W. Kent; Wilkins, Rick

2015-01-01

The NASA Radiation Dosimetry Experiment (RaD-X) high-altitude balloon mission was successfully launched from Fort Sumner, New Mexico USA on 25 September, 2015. Over 15 hours of science data were obtained from four dosimeters at altitudes above about 25 km. One of the main goals of the RaD-X mission is to improve aviation radiation model characterization of cosmic ray primaries by taking dosimetric measurements above the Pfotzer maximum before the production of secondary particles occurs. The second goal of the RaD-X mission is to facilitate the pathway toward real-time, data assimilative predictions of atmospheric cosmic radiation exposure by identifying and characterizing low-cost radiation measurement solutions.

The Australian radiation protection and nuclear safety agency megavoltage photon thermoluminescence dosimetry postal audit service 2007-2010.

PubMed

Oliver, C P; Butler, D J; Webb, D V

2012-03-01

The Australian radiation protection and nuclear safety agency (ARPANSA) has continuously provided a level 1 mailed thermoluminescence dosimetry audit service for megavoltage photons since 2007. The purpose of the audit is to provide an independent verification of the reference dose output of a radiotherapy linear accelerator in a clinical environment. Photon beam quality measurements can also be made as part of the audit in addition to the output measurements. The results of all audits performed between 2007 and 2010 are presented. The average of all reference beam output measurements calculated as a clinically stated dose divided by an ARPANSA measured dose is 0.9993. The results of all beam quality measurements calculated as a clinically stated quality divided by an ARPANSA measured quality is 1.0087. Since 2011 the provision of all auditing services has been transferred from the Ionizing Radiation Standards section to the Australian Clinical Dosimetry Service (ACDS) which is currently housed within ARPANSA.

21 CFR 179.39 - Ultraviolet radiation for the processing and treatment of food.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ultraviolet radiation for the processing and treatment of food. 179.39 Section 179.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) IRRADIATION IN THE PRODUCTION...

21 CFR 179.39 - Ultraviolet radiation for the processing and treatment of food.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ultraviolet radiation for the processing and treatment of food. 179.39 Section 179.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) IRRADIATION IN THE PRODUCTION...

21 CFR 179.39 - Ultraviolet radiation for the processing and treatment of food.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ultraviolet radiation for the processing and treatment of food. 179.39 Section 179.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) IRRADIATION IN THE PRODUCTION...

21 CFR 179.39 - Ultraviolet radiation for the processing and treatment of food.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ultraviolet radiation for the processing and treatment of food. 179.39 Section 179.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) IRRADIATION IN THE PRODUCTION, PROCESSING AND HANDLING OF FOOD...

21 CFR 179.39 - Ultraviolet radiation for the processing and treatment of food.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ultraviolet radiation for the processing and treatment of food. 179.39 Section 179.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) IRRADIATION IN THE PRODUCTION...

Modeling radiation dosimetry to predict cognitive outcomes in pediatric patients with CNS embryonal tumors including medulloblastoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Thomas E.; Kiehna, Erin N.; Li Chenghong

2006-05-01

Purpose: Model the effects of radiation dosimetry on IQ among pediatric patients with central nervous system (CNS) tumors. Methods and Materials: Pediatric patients with CNS embryonal tumors (n = 39) were prospectively evaluated with serial cognitive testing, before and after treatment with postoperative, risk-adapted craniospinal irradiation (CSI) and conformal primary-site irradiation, followed by chemotherapy. Differential dose-volume data for 5 brain volumes (total brain, supratentorial brain, infratentorial brain, and left and right temporal lobes) were correlated with IQ after surgery and at follow-up by use of linear regression. Results: When the dose distribution was partitioned into 2 levels, both had amore » significantly negative effect on longitudinal IQ across all 5 brain volumes. When the dose distribution was partitioned into 3 levels (low, medium, and high), exposure to the supratentorial brain appeared to have the most significant impact. For most models, each Gy of exposure had a similar effect on IQ decline, regardless of dose level. Conclusions: Our results suggest that radiation dosimetry data from 5 brain volumes can be used to predict decline in longitudinal IQ. Despite measures to reduce radiation dose and treatment volume, the volume that receives the highest dose continues to have the greatest effect, which supports current volume-reduction efforts.« less

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA-Results from GRaDEx-I and the Design of GRaDEx-II

NASA Technical Reports Server (NTRS)

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.

1999-01-01

Because of the large amounts of cosmic radiation in the space environment relative to that on earth, the effects of radiation on the physiology of astronauts is of major concern. Doses of radiation which can cause acute or chronic biological effects are to be avoided, therefore determination of the amount of radiation exposure encountered during space flight and assessment of its impact on biological systems is critical. Quantifying the radiation dosage and damage to biological systems, especially to humans during repetitive high altitude flight and during long duration space flight is important for several reasons. Radiation can cause altered biosynthesis and long term genotoxicity resulting in cancer and birth defects etc. Radiation damage to biological systems depends in a complex way on incident radiation species and their energy spectra. Typically non-biological, i.e. film or electronic monitoring systems with narrow energy band sensitivity are used to perform dosimetry and then results are extrapolated to biological models. For this reason it may be desirable to perform radiation dosimetry by using biological molecules e.g. DNA or RNA strands as passive sensors. A lightweight genotoxicology experiment was constructed to determine the degree to which in vitro naked DNA extracted from tissues of a variety of vertebrate organisms is damaged by exposure to radiation in a space environment. The DNA is assayed by means of agarose gel electrophoresis to determine damage such as strand breakage caused by high momentum particles and photons, and base oxidation caused by free radicals. The length distribution of DNA fragments is directly correlated with the radiation dose. It is hoped that a low mass, low cost, passive biological system to determine dose response relationship (increase in strand breaks with increase in exposure) can be developed to perform radiation dosimetry in support of long duration space flight, and to predict negative effects on biological

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA: Results from GRaDEx-I and the Design of GRaDEx-II

NASA Technical Reports Server (NTRS)

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.;

Lithium formate EPR dosimetry for verifications of planned dose distributions prior to intensity-modulated radiation therapy.

PubMed

Gustafsson, H; Lund, E; Olsson, S

2008-09-07

The objective of the present investigation was to evaluate lithium formate electron paramagnetic resonance (EPR) dosimetry for measurement of dose distributions in phantoms prior to intensity-modulated radiation therapy (IMRT). Lithium formate monohydrate tablets were carefully prepared, and blind tests were performed in clinically relevant situations in order to determine the precision and accuracy of the method. Further experiments confirmed that within the accuracy of the current method, the dosimeter response was independent of beam energies and dose rates used for IMRT treatments. The method was applied to IMRT treatment plans, and the dose determinations were compared to ionization chamber measurements. The experiments showed that absorbed doses above 3 Gy could be measured with an uncertainty of less than 2.5% of the dose (coverage factor kappa = 1.96). Measurement time was about 15 min using a well-calibrated dosimeter batch. The conclusion drawn from the investigation was that lithium formate EPR dosimetry is a promising new tool for absorbed dose measurements in external beam radiation therapy, especially for doses above 3 Gy.

Lithium formate EPR dosimetry for verifications of planned dose distributions prior to intensity-modulated radiation therapy

NASA Astrophysics Data System (ADS)

Gustafsson, H.; Lund, E.; Olsson, S.

2008-09-01

The objective of the present investigation was to evaluate lithium formate electron paramagnetic resonance (EPR) dosimetry for measurement of dose distributions in phantoms prior to intensity-modulated radiation therapy (IMRT). Lithium formate monohydrate tablets were carefully prepared, and blind tests were performed in clinically relevant situations in order to determine the precision and accuracy of the method. Further experiments confirmed that within the accuracy of the current method, the dosimeter response was independent of beam energies and dose rates used for IMRT treatments. The method was applied to IMRT treatment plans, and the dose determinations were compared to ionization chamber measurements. The experiments showed that absorbed doses above 3 Gy could be measured with an uncertainty of less than 2.5% of the dose (coverage factor k = 1.96). Measurement time was about 15 min using a well-calibrated dosimeter batch. The conclusion drawn from the investigation was that lithium formate EPR dosimetry is a promising new tool for absorbed dose measurements in external beam radiation therapy, especially for doses above 3 Gy.

Erythemal irradiances of filtered ultraviolet radiation

NASA Astrophysics Data System (ADS)

Parisi, A. V.; Wong, J. C. F.

1997-07-01

A spectrum evaluator employing four passive dosimeters has been used to evaluate the time averaged spectrum to allow calculation of the erythemal exposures resulting from the predominantly UVA component of filtered solar ultraviolet radiation. An exposure interval of approximately 20 min to autumn and spring sunshine was required for the spectrum evaluator to allow evaluation of the filtered source spectrum. For a clear spring day an erythemal exposure of 0.85 MED (minimum erythemal dose) to a horizontal plane and 0.38 MED to a vertical plane over a 6 h period was measured within a glass enclosure. For a partially cloudy day six weeks later, these were 0.89 and 0.44 MED for the horizontal and the vertical planes respectively. The ratios of the filtered to the unfiltered erythemal exposures within and outside the enclosure respectively ranged from 0.08 to 0.18 throughout the two days.

The measurement of ultraviolet radiation and sunburn time over southern Ontario

NASA Technical Reports Server (NTRS)

Evans, W. F. J.

1994-01-01

Studies of the depletion of ozone which have been conducted from the TOMS instrument on the NIMBUS 7 satellite indicate that total ozone has declined by 5 percent over the last 12 years at most mid-latitudes in the Northern Hemisphere typical of southern Ontario. The measurement of the actual resultant increases in UVB is now important. A monitoring program of UVB (biologically active solar ultraviolet radiation) has been conducted for the last 24 months at a site near Bolton, Ontario. The sunburn time varies from less than 17 minutes in late July, to over 4 hours in December on clear days. The levels depend on solar insolation and total ozone column. The ultraviolet levels are strongly affected by cloud and sky conditions. The implications of present and future depletion on the sunburn time are discussed.

ESR dosimetry for atomic bomb survivors and radiologic technologists

NASA Astrophysics Data System (ADS)

Tatsumi-Miyajima, Junko

1987-06-01

An individual absorbed dose for atomic bomb (A-bomb) survivors and radiologic technologists has been estimated using a new personal dosimetry. This dosimetry is based on the electron spin resonance (ESR) spectroscopy of the CO 33- radicals, which are produced in their teeth by radiation. Measurements were carried out to study the characteristics of the dosimetry; the ESR signals of the CO 33- radicals were stable and increased linearly with the radiation dose. In the evaluation of the absorbed dose, the ESR signals were considered to be a function of photon energy. The absorbed doses in ten cases of A-bomb victims and eight cases of radiologic technologists were determined. For A-bomb survivors, the adsorbed doses, which were estimated using the ESR dosimetry, were consistent with the ones obtained using the calculations of the tissue dose in air of A-bomb, and also with the ones obtained using the chromosome measurements. For radiologic technologists, the absorbed doses, which were estimated using the ESR dosimetry, agreed with the ones calculated using the information on the occupational history and conditions. The advantages of this method are that the absorbed dose can be directly estimated by measuring the ESR signals obtained from the teeth of persons, who are exposed to radiation. Therefore, the ESR dosimetry is useful to estimate the accidental exposure and the long term cumulative dose.

The Importance of Dosimetry Standardization in Radiobiology

PubMed Central

Desrosiers, Marc; DeWerd, Larry; Deye, James; Lindsay, Patricia; Murphy, Mark K; Mitch, Michael; Macchiarini, Francesca; Stojadinovic, Strahinja; Stone, Helen

2013-01-01

Radiation dose is central to much of radiobiological research. Precision and accuracy of dose measurements and reporting of the measurement details should be sufficient to allow the work to be interpreted and repeated and to allow valid comparisons to be made, both in the same laboratory and by other laboratories. Despite this, a careful reading of published manuscripts suggests that measurement and reporting of radiation dosimetry and setup for radiobiology research is frequently inadequate, thus undermining the reliability and reproducibility of the findings. To address these problems and propose a course of action, the National Cancer Institute (NCI), the National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute of Standards and Technology (NIST) brought together representatives of the radiobiology and radiation physics communities in a workshop in September, 2011. The workshop participants arrived at a number of specific recommendations as enumerated in this paper and they expressed the desirability of creating dosimetry standard operating procedures (SOPs) for cell culture and for small and large animal experiments. It was also felt that these SOPs would be most useful if they are made widely available through mechanism(s) such as the web, where they can provide guidance to both radiobiologists and radiation physicists, be cited in publications, and be updated as the field and needs evolve. Other broad areas covered were the need for continuing education through tutorials at national conferences, and for journals to establish standards for reporting dosimetry. This workshop did not address issues of dosimetry for studies involving radiation focused at the sub-cellular level, internally-administered radionuclides, biodosimetry based on biological markers of radiation exposure, or dose reconstruction for epidemiological studies. PMID:26401441

[Benchmark experiment to verify radiation transport calculations for dosimetry in radiation therapy].

PubMed

Renner, Franziska

2016-09-01

Monte Carlo simulations are regarded as the most accurate method of solving complex problems in the field of dosimetry and radiation transport. In (external) radiation therapy they are increasingly used for the calculation of dose distributions during treatment planning. In comparison to other algorithms for the calculation of dose distributions, Monte Carlo methods have the capability of improving the accuracy of dose calculations - especially under complex circumstances (e.g. consideration of inhomogeneities). However, there is a lack of knowledge of how accurate the results of Monte Carlo calculations are on an absolute basis. A practical verification of the calculations can be performed by direct comparison with the results of a benchmark experiment. This work presents such a benchmark experiment and compares its results (with detailed consideration of measurement uncertainty) with the results of Monte Carlo calculations using the well-established Monte Carlo code EGSnrc. The experiment was designed to have parallels to external beam radiation therapy with respect to the type and energy of the radiation, the materials used and the kind of dose measurement. Because the properties of the beam have to be well known in order to compare the results of the experiment and the simulation on an absolute basis, the benchmark experiment was performed using the research electron accelerator of the Physikalisch-Technische Bundesanstalt (PTB), whose beam was accurately characterized in advance. The benchmark experiment and the corresponding Monte Carlo simulations were carried out for two different types of ionization chambers and the results were compared. Considering the uncertainty, which is about 0.7 % for the experimental values and about 1.0 % for the Monte Carlo simulation, the results of the simulation and the experiment coincide. Copyright © 2015. Published by Elsevier GmbH.

Direct comparison of radiation dosimetry of six PET tracers using human whole-body imaging and murine biodistribution studies.

PubMed

Sakata, Muneyuki; Oda, Keiichi; Toyohara, Jun; Ishii, Kenji; Nariai, Tadashi; Ishiwata, Kiichi

2013-04-01

We investigated the whole-body biodistributions and radiation dosimetry of five (11)C-labeled and one (18)F-labeled radiotracers in human subjects, and compared the results to those obtained from murine biodistribution studies. The radiotracers investigated were (11)C-SA4503, (11)C-MPDX, (11)C-TMSX, (11)C-CHIBA-1001, (11)C-4DST, and (18)F-FBPA. Dynamic whole-body positron emission tomography (PET) was performed in three human subjects after a single bolus injection of each radiotracer. Emission scans were collected in two-dimensional mode in five bed positions. Regions of interest were placed over organs identified in reconstructed PET images. The OLINDA program was used to estimate radiation doses from the number of disintegrations of these source organs. These results were compared with the predicted human radiation doses on the basis of biodistribution data obtained from mice by dissection. The ratios of estimated effective doses from the human-derived data to those from the mouse-derived data ranged from 0.86 to 1.88. The critical organs that received the highest absorbed doses in the human- and mouse-derived studies differed for two of the six radiotracers. The differences between the human- and mouse-derived dosimetry involved not only the species differences, including faster systemic circulation of mice and differences in the metabolism, but also measurement methodologies. Although the mouse-derived effective doses were roughly comparable to the human-derived doses in most cases, considerable differences were found for critical organ dose estimates and pharmacokinetics in certain cases. Whole-body imaging for investigation of radiation dosimetry is desirable for the initial clinical evaluation of new PET probes prior to their application in subsequent clinical investigations.

Effects of ultraviolet-B radiation on fungal disease development in Cucumis sativus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orth, A.B.; Teramura, A.H.; Sisler, H.D.

1990-09-01

Stratospheric ozone depletion due to increased atmospheric pollutants has received considerable attention because of the potential increase in ultraviolet-B (UV-B, 280-320 nm) radiation that will reach the earth's surface. Three cucumber (Cucumis sativus L.) cultivars were exposed to a daily dose of 11.6 kJ m{sup {minus}2} biologically effective ultraviolet-B (UV-B{sub BE}) radiation in an unshaded greenhouse before and/or after injection by Colletotrichum lagenarium (Pass.) Ell. and Halst. or Cladosporium cucumerinum Ell. and Arth. and analyzed for disease development. Two of these cultivars, Poinsette and Calypso Hybrid, were disease resistant, while the third cultivar, Straight-8, was disease susceptible. Preinfectional treatment ofmore » 1 to 7 days with UV-B{sub BE} in Straight-8 led to greater severity of both diseases. Postinfectional UV treatment did not lead to increased disease severity caused by C. lagenarium, while preinfectional UV treatment in both Straight-8 and Poinsette substantially increased disease severity. Although resistant cultivars Poinsette and Calypso Hybrid showed increased anthracnose disease severity when exposed to UV-B, this effect was apparent only on the cotyledons. Both higher spore concentration and exposure to UV-B radiation resulted in greater disease severity. Of the cucumber cultivars tested for UV-B sensitivity, growth in Poinsette was most sensitive and Calypso Hybrid was least sensitive. These preliminary results indicate that the effects of UV-B radiation on disease development in cucumber vary depending on cultivar, timing and duration of UV-B exposure, inoculation level, and plant age.« less

SU-D-213-06: Dosimetry of Modulated Electron Radiation Therapy Using Fricke Gel Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gawad, M Abdel; Elgohary, M; Hassaan, M

Purpose: Modulated electron radiation therapy (MERT) has been proposed as an effective modality for treatment of superficial targets. MERT utilizes multiple beams of different energies which are intensity modulated to deliver optimized dose distribution. Energy independent dosimeters are thus needed for quantitative evaluations of MERT dose distributions and measurements of absolute doses delivered to patients. Thus in the current work we study the feasibility of Fricke gel dosimeters in MERT dosimetry. Methods: Batches of radiation sensitive Fricke gel is fabricated and poured into polymethyl methacrylate cuvettes. The samples were irradiated in solid water phantom and a thick layer of bolusmore » was used as a buildup. A spectrophotometer system was used for measuring the color changes (the absorbance) before and after irradiation and then we calculate net absorbance. We constructed calibration curves to relate the measured absorbance in terms of absorbed dose for all available electron energies. Dosimetric measurements were performed for mixed electron beam delivery and we also performed measurement for segmented field delivery with the dosimeter placed at the junction of two adjacent electron beams of different energies. Dose measured by our gel dosimetry is compared to that calculation from our precise treatment planning system. We also initiated a Monte Carlo study to evaluate the water equivalence of our dosimeters. MCBEAM and MCSIM codes were used for treatment head simulation and phantom dose calculation. PDDs and profiles were calculated for electron beams incident on a phantom designed with 1cm slab of Fricke gel. Results: The calibration curves showed no observed energy dependence with all studied electron beam energies. Good agreement was obtained between dose calculated and that obtained by gel dosimetry. Monte Carlo results illustrated the tissue equivalency of our Gel dosimeters. Conclusion: Fricke Gel dosimeters represent a good option for the

Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

PubMed

Hooke, Rebecca; Pearson, Andy; O'Hagan, John

2014-01-01

Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown. © 2014 Crown copyright. Photochemistry and Photobiology © 2014 The American Society of Photobiology. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland and Public Health England.

The use of the dicentric assay for biological dosimetry for radiation accidents in Bulgaria.

PubMed

Hadjidekova, Valeria; Hristova, Rositsa; Ainsbury, Elizabeth A; Atanasova, Petya; Popova, Ljubomira; Staynova, Albena

2010-02-01

This paper details the construction of a 137Cs gamma calibration curve that has been established for dicentric assay and the testing and validation of the curve through biological dosimetry in three situations of suspected workplace overexposure that arose accidentally or through negligence or lack of appropriate safety measures. The three situations were: (1) suspected 137Cs contamination in a factory air supply; (2) suspected exposure to an industrial 192Ir source; and (3) accidental exposure of construction workers to radiation from a 60Co radiotherapy source in a hospital medical physics department. From a total of 24 potentially-exposed subjects, only one worker was found to have a statistically significant dose (0.16 Gy, 95% confidence intervals 0.02-0.43 Gy). In all other cases, the main function of the biological dosimetry was to reassure the subjects that any dose received was low.

Replicated mesocosm study on the role of natural ultraviolet radiation in high CDOM, shallow lakes.

PubMed

Pérez, A Patricia; Diaz, Mónica M; Ferraro, Marcela A; Cusminsky, Gabriela C; Zagarese, Horacio E

2003-02-01

The role of ultraviolet radiation on shallow, high CDOM (colored dissolved organic matter) lakes was investigated during two consecutive summers (1999 and 2000) in replicated mesocosms (rectangular fiberglass tanks). Each tank (volume: 300 L; depth: 40 cm) was covered with a layer (approximately 3 cm) of sediment from lake El Toro (40 degrees 14' S; 70 degrees 22' W) and filled with filtered water. The experimental design consisted of two treatments: full natural radiation (UV-exposed) and natural radiation without ultraviolet radiation (UV-shielded). UV-exposed and UV-shielded treatments differed in most studied variables as revealed by repeated measures ANOVA. UV-exposed tanks displayed lower CDOM levels (dissolved absorbance) of lower average molecular size (absorbance ratio between 250 and 365 nm), higher bacterial biomass, and lower chlorophyll a concentration. The effect on consumers (rotifers and crustaceans) was less noticeable. The results are consistent with UV stimulation of bacteria production mediated by higher rates of CDOM photobleaching, and the photoinhibition of planktonic algae. Thus, a major effect of UVR in shallow, high CDOM ecosystems appears to be the stimulation of heterotrophic pathways and a simultaneous inhibition of photoautotrophs.

TOPICAL REVIEW: A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction

NASA Astrophysics Data System (ADS)

Xu, X. George; Bednarz, Bryan; Paganetti, Harald

2008-07-01

It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end.

Ultraviolet radiation exposure triggers neurokinin-1 receptor upregulation in ocular tissues in vivo.

PubMed

Gross, Janine; Wegener, Alfred R; Kronschlaeger, Martin; Holz, Frank G; Schönfeld, Carl-Ludwig; Meyer, Linda M

2018-04-26

The purpose of this study was to investigate the neurokinin receptor-1 (NKR-1) protein expression in ocular tissues before and after supra-cataract threshold ultraviolet radiation (UVR-B peak at 312 nm) exposure in vivo in a mouse model. Six-week-old C57Bl/6 mice were unilaterally exposed to a single (2.9 kJ/m 2 ) and an above 3-fold UVR-B cataract threshold dose (9.4 kJ/m 2 ) of UVR. UVR-exposure (λpeak = 312 nm) was performed in mydriasis using a Bio-Spectra exposure system. After latency periods of 3 and 7 days, eyes were fixed in 4% paraformaldehyde, embedded in paraffin, sectioned and stained with fluorescence coupled antibody for NKR-1 and DAPI for cell nuclei staining. Control animals received only anesthesia but no UVR-exposure. Cataract development was documented with a Leica dark-field microscope and quantified as integrated optical density (IOD). NKR-1 is ubiquitously present in ocular tissues. An above 3-fold cataract threshold dose of UV-radiation induced NKR-1 upregulation after days 3 and 7 in the epithelium and endothelium of the cornea, the endothelial cells of the iris vessels, the pigmented epithelium/stroma of the ciliary body, the lens epithelium, pronounced in the nuclear bow region and the inner plexiform layer of the retina. A significant upregulation of NKR-1 could not be provoked with a single cataract threshold dose (2.9 kJ/m 2 UVR-B) ultraviolet irradiation. All exposed eyes developed anterior subcapsular cataracts. Neurokinin-1 receptor is present ubiquitously in ocular tissues including the lens epithelium and the nuclear bow region of the lens. UV-radiation exposure to an above 3-fold UVR-B cataract threshold dose triggers NKR-1 upregulation in the eye in vivo. The involvement of inflammation in ultraviolet radiation induced cataract and the role of neuroinflammatory peptides such as substance P and its receptor, NKR-1, might have been underestimated to date. Copyright © 2018. Published by Elsevier Ltd.

The role of ultraviolet radiation in the pathogenesis of pterygia (Review).

PubMed

Zhou, Wei-Ping; Zhu, Yuan-Fang; Zhang, Bei; Qiu, Wen-Ya; Yao, Yu-Feng

2016-07-01

Pterygium is a common ophthalmic disease affecting humans only. Extensive epidemiological data have demonstrated a causative effect of chronic ultraviolet (UV) radiation on pterygia. Progress has been made in determining the origin of pterygia, their nasal predilection and wing‑shaped appearance, and the roles of UV radiation in the initiation and the development of pterygia. In the present review, the current understanding of the involvement of UV radiation in the pathogenesis of pterygia is summarized. This involvement includes the alteration of limbal stem cells and fibroblasts that contribute to the initiation of pterygia and the induction of various pro‑inflammatory cytokines, growth factors and matrix metalloproteinases that promote the progression of pterygia. Further elucidation of the roles of UV radiation in the pathogenesis of pterygia may help to encourage individuals at risk of developing pterygia to take preventive measures and aid researchers in the development of novel targeted therapeutic agents to treat pterygia.

Solar ultraviolet radiation and its impact on aquatic systems of Patagonia, South America.

PubMed

Villafañe, V E; Helbling, E W; Zagarese, H E

2001-03-01

Solar ultraviolet radiation (UVR, 280-400 nm) is known to cause a number of detrimental effects in aquatic organisms. The area of Patagonia, which is sometimes under the influence of the Antarctic ozone "hole", occasionally receives enhanced levels of ultraviolet B radiation (UV-B, 280-315 nm). Great efforts have been put into creating a database for UVR climatology by installing a variety of instruments in several localities in the region. However, no comparable effort has been made to determine the impact of normal and enhanced levels of solar UVR upon organisms. Most of the photobiological research in aquatic systems of Patagonia has focused on determining the effects of solar UVR in phytoplankton photosynthesis, DNA damage, and mortality, fecundity and repair mechanisms in zooplanktonic species. Some work has also been done with fish larvae and interactions between species at low trophic levels of the aquatic food web. The results of these studies indicate that in order to assess the overall impact of UVR in a certain waterbody, it is also necessary to consider other variables, such as changes in cloudiness, ozone concentrations, differential sensitivity of organisms, and depth of the upper mixed layer/epilimnion. All factors that can preclude or benefit the acclimation of species to solar radiation.

Decontamination Efficacy of Ultraviolet Radiation against Biofilms of Common Nosocomial Bacteria.

PubMed

Tingpej, Pholawat; Tiengtip, Rattana; Kondo, Sumalee

2015-06-01

Ultraviolet radiation (UV) is commonly used to destroy microorganisms in the health-care environment. However, the efficacy of UV radiation against bacteria growing within biofilms has never been studied. To measure the sterilization effectiveness of UV radiation against common healthcare associated pathogens growing within biofilms. Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Streptococcus epidermidis, Escherichia coli, ESBL-producing E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii were cultivated in the Calgary Biofilm Device. Their biofilms were placed 50 cm from the UV lamp within the Biosafety Cabinet. Viability test, crystal violet assay and a scanning electron microscope were used to evaluate the germicidal efficacy. Within 5 minutes, UV radiation could kill S. aureus, MRSA, S. epidermidis, A. baumannii and ESBL-producing E. coli completely while it required 20 minutes and 30 minutes respectively to kill E. coli and P. aeruginosa. However, the amounts of biomass and the ultrastructure between UV-exposed biofilms and controls were not significantly different. UV radiation is effective in inactivating nosocomial pathogens grown within biofilms, but not removing biofilms and EPS. The biofilm of P. aeruginosa was the most durable.

Fixed, object-specific intensity compensation for cone beam optical CT radiation dosimetry

NASA Astrophysics Data System (ADS)

Dekker, Kurtis H.; Hazarika, Rubin; Silveira, Matheus A.; Jordan, Kevin J.

2018-03-01

Optical cone beam computed tomography (CT) scanning of radiochromic gel dosimeters, using a CCD camera and a low stray light convergent source, provides fast, truly 3D radiation dosimetry with high accuracy. However, a key limiting factor in radiochromic gel dosimetry at large (⩾10 cm diameter) volumes is the initial attenuation of the dosimeters. It is not unusual to observe a 5–10×  difference in signal intensity through the dosimeter center versus through the surrounding medium in pre-irradiation images. Thus, all dosimetric information in a typical experiment is measured within the lower 10%–20% of the camera sensor’s range, and re-use of gels is often not possible due to a lack of transmission. To counteract this, in this note we describe a simple method to create source compensators by printing on transparent films. This technique, which is easily implemented and inexpensive, is an optical analogue to the bowtie filter in x-ray CT. We present transmission images and solution phantom reconstructions to demonstrate that (1) placing compensators beyond the focal zone of the imaging lens prevents high spatial frequency features of the printed films from generating reconstruction artifacts, and (2) object-specific compensation considerably reduces the range of intensities measured in projection images. This will improve the measurable dose range in optical CT dosimetry, and will enable imaging of larger gel volumes (∼15 cm diameter). Additionally, it should enable re-use of dosimeters by printing a new compensator for a second experiment.

Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

NASA Astrophysics Data System (ADS)

Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

2015-12-01

Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

Radiation effects on MOS devices - dosimetry, annealing, irradiation sequence, and sources

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Brucker, G. J.; Van Gunten, O.; Knudson, A. R.; Jordan, T. M.

1983-01-01

This paper reports on some investigations of dosimetry, annealing, irradiation sequences, and radioactive sources, involved in the determination of radiation effects on MOS devices. Results show that agreement in the experimental and theoretical surface to average doses support the use of thermo-luminescent dosimeters (manganese activated calcium fluoride) in specifying the surface dose delivered to thin gate insulators of MOS devices. Annealing measurements indicate the existence of at least two energy levels,,s or a activation energies, for recovery of soft oxide MOS devices after irradiation by electrons, protons, and gammas. Damage sensitivities of MOS devices were found to be independent of combinations and sequences of radiation type or energies. Comparison of various gamma sources indicated a small dependence of damage sensitivity on the Cobalt facility, but a more significant dependence in the case of the Cesium source. These results were attributed to differences in the spectral content of the several sources.

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

NASA Technical Reports Server (NTRS)

Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch, E.; Poland, A. I.

1988-01-01

The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

Photoresist composition for extreme ultraviolet lithography

DOEpatents

Felter, T. E.; Kubiak, G. D.

1999-01-01

A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods. A photoresist composition for extreme ultraviolet radiation of boron carbide polymers, hydrochlorocarbons and mixtures thereof.

[Effect of long-wave ultraviolet light (UV-A) and medium-wave ultraviolet rays (UV-B) on human skin. Critical comparison].

PubMed

Raab, W

1980-04-15

When discussing the effects of ultraviolet radiation on human skin, one should carefully distinguish between the long wave ultraviolet light (UV-A) and the short wave radiations (UV-B and UV-C). Ultraviolet A induces immediate pigmentation but, if high energies are applied, a permanent pigmentation is elicited. This type of ultraviolet A-induced pigmentation has been called "spontaneous" pigmentation as no erythematous reaction is necessary to induce or accelerate melanine formation. Ultraviolet B provokes erythema and consecutive pigmentation. Upon chronic exposure, ultraviolet B causes the wellknown actinic damage of the skin and even provokes carcinoma. With exposures to the sunlight (global radiation), one should be most careful. The public must be informed extensively about the dangers of excessive sunbaths. The use of artificial "suns" with spectra between 260 and 400 nm is limited as it may cause the same type of damage as the global radiation. An exact schedule for use of artificial lamps is strongly recommended. After one cycle of exposures, an interruption is necessary until the next cycle of irradiations may start. Upon continual use for tanning of the skin, artificial lamps may provoke irreversible damage of the skin. Radiation sources with emission spectra of wavelengths between 315 and 400 nm exclusively are well suited for the induction of skin pigmentation (cosmetic use). Potent radiation such as UVASUN systems provoke a "pleasant" permanent pigmentation after exposures for less than one hour. The use of ultraviolet A (UV-A) does not carry any risk for the human skin.

SU-E-T-310: Micro-Dosimetry Study of the Radiation Dose Enhancement at the Gold-Tissue Interface for Nanoparticle-Aided Radiation Therapy.

PubMed

Paudel, N; Shvydka, D; Parsai, E

2012-06-01

Gold nanoparticles (AuNP) have been proposed to be utilized for local dose enhancement in radiation therapy. Due to a very sharp spatial fall-off of the effect, the dosimetry associated with such an approach is difficult to implement in a direct measurement. This study is aimed at establishing a micro-dosimetry technique for experimental verification of dose enhancement in the vicinity of gold-tissue interface. The spatial distribution of the dose enhancement near the gold-tissue interface is modeled with Monte Carlo (MC) package MCNP5 in a 1-dimentional approach of a thin gold slab placed in an ICRU-4 component tissue phantom. The model is replicating the experiment, where the dose enhancement due to gold foils having thicknesses of 1, 10, and 100μm and areas of 12.5×25mm 2 are placed at a short distance from clinical HDR brachytherapy (Ir-192) source. The measurements are carried out with a thin-film CdTe-based photodetector, having thickness <10μm, allowing for high spatial resolution at progressively increasing distances from the foil. Our MC simulation results indicate that for Ir-192 energy spectrum the dose enhancement region extends over ∼1 mm distance from the foil, changing from several hundred at the interface to just a few percent. The trend in the measured dose enhancement closely follows the results obtained from MC simulations. AuNP's have been established as promising candidates for dose enhancement in nanoparticle-aided radiation therapy, particularly, in the energy range relevant to brachytherapy applications. Most researchers study the dose enhancement with MC simulations, or experimental approaches involving biological systems, where achievable dose enhancements are difficult to quantify. Successful development of micro-dosimetry approaches will pave a way for direct assessment of the dose in experiments on biological models, shedding some light on apparent discrepancy between physical dose enhancement and biological effect established in

SU-C-BRE-04: Microbeam-Radiation-Therapy (MRT): Characterizing a Novel MRT Device Using High Resolution 3D Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Q; Juang, T; Bache, S

2014-06-15

Purpose: The feasibility of MRT has recently been demonstrated utilizing a new technology of Carbon-Nano-Tube(CNT) field emission x-ray sources.This approach can deliver very high dose(10's of Gy) in narrow stripes(sub-mm) of radiation which enables the study of novel radiation treatment approaches. Here we investigate the application of highresolution (50um isotropic) PRESAGE/Optical-CT 3D dosimetry techniques to characterize the radiation delivered in this extremely dosimetrically challenging scenario. Methods: The CNT field emission x-ray source irradiator comprises of a linear cathode array and a novel collimator alignment system. This allows a precise delivery of high-energy small beams up to 160 kVp. A cylindricalmore » dosimeter (∼2.2cm in height ∼2.5cm in diameter) was irradiated by CNT MRT delivering 3 strips of radiation with a nominal entrance dose of 32 Gy.A second dosimeter was irradiated with similar entrance dose, with a regular x-ray irradiator collimated to microscopical strip-beams. 50um (isotropic) 3D dosimetry was performed using an in-house optical-CT system designed and optimized for high resolution imaging (including a stray light deconvolution correction).The percentage depth dose (PDD), peak-to-valley ratio (PVR) and beam width (FWHM) data were obtained and analyzed in both cases. Results: High resolution 3D images were successfully achieved with the prototype system, enabling extraction of PDD and dose profiles. The PDDs for the CNT irradiation showed pronounced attenuation, but less build-up effect than that from the multibeam irradiation. The beam spacing between the three strips has an average value of 0.9mm while that for the 13 strips is 1.5 mm at a depth of 16.5 mm. The stray light corrected image shows line profiles with reduced noise and consistent PVR values. Conclusion: MRT dosimetry is extremely challenging due to the ultra small fields involved.This preliminary application of a novel, ultra-high resolution, optical-CT 3D

The Growing Public Health Challenges of Exposure to Ultraviolet Radiation From Use of Indoor Tanning Devices in the United States.

PubMed

Bowman, Diana M; Lewis, Ryan C; Lee, Maximilian S; Yao, Catherine J

2015-08-01

Ultraviolet radiation is recognized as a human carcinogen by the International Agency for Research on Cancer, the world's authority on cancer research. In particular, exposure to ultraviolet radiation can lead to melanoma of the skin, which is the deadliest form of skin cancer in the United States. Yet despite the significant public health burden that is associated with skin cancer in the United States, each year over a million Americans engage in indoor tanning where exposure to artificial ultraviolet radiation occurs. In this article, we argue for an immediate ban on the use of commercial indoor tanning by minors and, based on international precedents, the phasing out of all commercial tanning operations in the United States. We consider the use of indoor tanning devices in the United States, epidemiological data on indoor tanning devices and cancer, regulation of tanning devices, and scientific evidence for increased government intervention. © The Author(s) 2015.

Ultraviolet-B radiation in a row-crop canopy: an extended 1-D model

Treesearch

Wei Gao; Richard H. Grant; Gordon M. Heisler; James R. Slusser

2003-01-01

A decrease in stratospheric ozone may result in a serious threat to plants, since biologically active short-wavelength ultraviolet-B (UV-B 280-320 nm) radiation will increase even with a relatively small decrease in ozone. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species...

Early exposure to ultraviolet-B radiation decreases immune function later in life

PubMed Central

Ceccato, Emma; Cramp, Rebecca L.; Seebacher, Frank; Franklin, Craig E.

2016-01-01

Amphibians have declined dramatically worldwide. Many of these declines are occurring in areas where no obvious anthropogenic stressors are present. It is proposed that in these areas, environmental factors such as elevated solar ultraviolet-B (UV-B) radiation could be responsible. Ultraviolet-B levels have increased in many parts of the world as a consequence of the anthropogenic destruction of the ozone layer. Amphibian tadpoles are particularly sensitive to the damaging effects of UV-B radiation, with exposure disrupting growth and fitness in many species. Given that UV-B can disrupt immune function in other animals, we tested the hypothesis that early UV-B exposure suppresses the immune responses of amphibian tadpoles and subsequent juvenile frogs. We exposed Limnodynastes peronii tadpoles to sublethal levels of UV-B radiation for 6 weeks after hatching, then examined indices of immune function in both the tadpoles and the subsequent metamorphs. There was no significant effect of UV-B on tadpole leucocyte counts or on their response to an acute antigen (phytohaemagglutinin) challenge. However, early UV-B exposure resulted in a significant reduction in both metamorph leucocyte abundance and their response to an acute phytohaemagglutinin challenge. These data demonstrate that early UV-B exposure can have carry-over effects on later life-history traits even if the applied stressor has no immediately discernible effect. These findings have important implications for our understanding of the effects of UV-B exposure on amphibian health and susceptibility to diseases such as chytridiomycosis. PMID:27668081

Biological Sensors for Solar Ultraviolet Radiation

PubMed Central

Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Menck, Carlos F.M.; Schuch, André P.

2011-01-01

Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products. PMID:22163847

Effects of Various Wavelength Ranges of Vacuum Ultraviolet Radiation on Teflon FEP Film Investigated

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; McCracken, Cara A.

2004-01-01

Teflon Fluorinated Ethylene Propylene (FTP) films (DuPont) have been widely used for spacecraft thermal control and have been observed to become embrittled and cracked upon exposure to the space environment. This degradation has been attributed to a synergistic combination of radiation and thermal effects. A research study was undertaken at the NASA Glenn Research Center to examine the effects of different wavelength ranges of vacuum ultraviolet (VUV) radiation on the degradation of the mechanical properties of FEP. This will contribute to an overall understanding of space radiation effects on Teflon FEP, and will provide information necessary to determine appropriate techniques for using laboratory tests to estimate space VUV degradation. Research was conducted using inhouse facilities at Glenn and was carried out, in part, through a grant with the Cleveland State University. Samples of Teflon FEP film of 50.8 microns thickness were exposed to radiation from a VUV lamp from beneath different cover windows to provide different exposure wavelength ranges: MgF2 (115 to 400 nm), crystalline quartz (140 to 400 nm), and fused silica (FS, 155 to 400 nm). Following exposure, FEP film specimens were tensile tested to determine the ultimate tensile strength and elongation at failure as a function of the exposure duration for each wavelength range. The graphs show the effect of ultraviolet exposure on the mechanical properties of the FEP samples.

MO-B-BRB-00: Three Dimensional Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

3D dosimetry estimation for selective internal radiation therapy (SIRT) using SPECT/CT images: a phantom study

NASA Astrophysics Data System (ADS)

Debebe, Senait A.; Franquiz, Juan; McGoron, Anthony J.

2015-03-01

Selective Internal Radiation Therapy (SIRT) is a common way to treat liver cancer that cannot be treated surgically. SIRT involves administration of Yttrium - 90 (90Y) microspheres via the hepatic artery after a diagnostic procedure using 99mTechnetium (Tc)-macroaggregated albumin (MAA) to detect extrahepatic shunting to the lung or the gastrointestinal tract. Accurate quantification of radionuclide administered to patients and radiation dose absorbed by different organs is of importance in SIRT. Accurate dosimetry for SIRT allows optimization of dose delivery to the target tumor and may allow for the ability to assess the efficacy of the treatment. In this study, we proposed a method that can efficiently estimate radiation absorbed dose from 90Y bremsstrahlung SPECT/CT images of liver and the surrounding organs. Bremsstrahlung radiation from 90Y was simulated using the Compton window of 99mTc (78keV at 57%). 99mTc images acquired at the photopeak energy window were used as a standard to examine the accuracy of dosimetry prediction by the simulated bremsstrahlung images. A Liqui-Phil abdominal phantom with liver, stomach and two tumor inserts was imaged using a Philips SPECT/CT scanner. The Dose Point Kernel convolution method was used to find the radiation absorbed dose at a voxel level for a three dimensional dose distribution. This method will allow for a complete estimate of the distribution of radiation absorbed dose by tumors, liver, stomach and other surrounding organs at the voxel level. The method provides a quantitative predictive method for SIRT treatment outcome and administered dose response for patients who undergo the treatment.

Photoprotection beyond ultraviolet radiation--effective sun protection has to include protection against infrared A radiation-induced skin damage.

PubMed

Schroeder, P; Calles, C; Benesova, T; Macaluso, F; Krutmann, J

2010-01-01

Solar radiation is well known to damage human skin, for example by causing premature skin ageing (i.e. photoageing). We have recently learned that this damage does not result from ultraviolet (UV) radiation alone, but also from longer wavelengths, in particular near-infrared radiation (IRA radiation, 760-1,440 nm). IRA radiation accounts for more than one third of the solar energy that reaches human skin. While infrared radiation of longer wavelengths (IRB and IRC) does not penetrate deeply into the skin, more than 65% of the shorter wavelength (IRA) reaches the dermis. IRA radiation has been demonstrated to alter the collagen equilibrium of the dermal extracellular matrix in at least two ways: (a) by leading to an increased expression of the collagen-degrading enzyme matrix metalloproteinase 1, and (b) by decreasing the de novo synthesis of the collagen itself. IRA radiation exposure therefore induces similar biological effects to UV radiation, but the underlying mechanisms are substantially different, specifically, the cellular response to IRA irradiation involves the mitochondrial electron transport chain. Effective sun protection requires specific strategies to prevent IRA radiation-induced skin damage. 2010 S. Karger AG, Basel.

Biodistribution and radiation dosimetry of [64Cu]copper dichloride: first-in-human study in healthy volunteers.

PubMed

Avila-Rodriguez, M A; Rios, C; Carrasco-Hernandez, J; Manrique-Arias, J C; Martinez-Hernandez, R; García-Pérez, F O; Jalilian, A R; Martinez-Rodriguez, E; Romero-Piña, M E; Diaz-Ruiz, A

2017-12-12

In recent years, Copper-64 (T 1/2  = 12.7 h) in the chemical form of copper dichloride ([ 64 Cu]CuCl 2 ) has been identified as a potential agent for PET imaging and radionuclide therapy targeting the human copper transporter 1, which is overexpressed in a variety of cancer cells. Limited human biodistribution and radiation dosimetry data is available for this tracer. The aim of this research was to determine the biodistribution and estimate the radiation dosimetry of [ 64 Cu]CuCl 2 , using whole-body (WB) PET scans in healthy volunteers. Six healthy volunteers were included in this study (3 women and 3 men, mean age ± SD, 54.3 ± 8.6 years; mean weight ± SD, 77.2 ± 12.4 kg). After intravenous injection of the tracer (4.0 MBq/kg), three consecutive WB emission scans were acquired at 5, 30, and 60 min after injection. Additional scans were acquired at 5, 9, and 24 h post-injection. Low-dose CT scan without contrast was used for anatomic localization and attenuation correction. OLINDA/EXM software was used to calculate human radiation doses using the reference adult model. The highest uptake was in the liver, followed by lower and upper large intestine walls, and pancreas, in descending order. Urinary excretion was negligible. The critical organ was liver with a mean absorbed dose of 310 ± 67 μGy/MBq for men and 421 ± 56 μGy/MBq for women, while the mean WB effective doses were 51.2 ± 3.0 and 61.8 ± 5.2 μSv/MBq for men and women, respectively. To the best of our knowledge, this is the first report on biodistribution and radiation dosimetry of [ 64 Cu]CuCl 2 in healthy volunteers. Measured absorbed doses and effective doses are higher than previously reported doses estimated with biodistribution data from patients with prostate cancer, a difference that could be explained not just due to altered biodistribution in cancer patients compared to healthy volunteers but most likely due to the differences in the analysis

Repair of Ultraviolet Radiation Damage in Sensitive Mutants of Micrococcus radiodurans

PubMed Central

Moseley, B. E. B.

1969-01-01

Various aspects of the repair of ultraviolet (UV) radiation-induced damage were compared in wild-type Micrococcus radiodurans and two UV-sensitive mutants. Unlike the wild type, the mutants are more sensitive to radiation at 265 nm than at 280 nm. The delay in deoxyribonucleic acid (DNA) synthesis following exposure to UV is about seven times as long in the mutants as in the wild type. All three strains excise UV-induced pyrimidine dimers from their DNA, although the rate at which cytosine-thymine dimers are excised is slower in the mutants. The three strains also mend the single-strand breaks that appear in the irradiated DNA as a result of dimer excision, although the process is less efficient in the mutants. It is suggested that the increased sensitivity of the mutants to UV radiation may be caused by a partial defect in the second step of dimer excision. PMID:5773016

Develop real-time dosimetry concepts and instrumentation for long term missions

NASA Technical Reports Server (NTRS)

Braby, L. A.

1981-01-01

The development of a rugged portable dosimetry system, based on microdosimetry techniques, which will measure dose and evaluate dose equivalent in a mixed radiation field is described. Progress in the desired dosimetry system can be divided into three distinct areas: development of the radiation detector, and electron system are presented. The mathematical techniques required are investigated.

Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jablonowski, H.; Hammer, M. U.; Reuter, S.

Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stablemore » reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.« less

An investigation of solar erythemal ultraviolet radiation at two sites in tourist attraction areas of Thailand

NASA Astrophysics Data System (ADS)

Buntoung, Sumaman; Pattarapanitchai, Somjet; Wattan, Rungrat; Masiri, Itsara; Promsen, Worrapass; Tohsing, Korntip; Janjai, Serm

2013-05-01

Islands on the southern coasts of Thailand are famous attractions for local and foreign tourists. Tourists usually expose their skins to solar radiation for tanning. Thus information on solar ultraviolet radiation (UV) is of importance for tourists to protect themselves from adverse effects of UV. In this work, solar erythemal ultraviolet radiation (EUV) at two touristic sites namely Samui island (9.451°N, 100.033°E) and Phuket island (8.104°N, 98.304°E) was investigated. In investigating EUV, broadband UV radiometers (Kipp & Zonen, model UVS-B-C) were installed at existing meteorological stations in Samui and Phuket islands. A one-year period of EUV data from these two sites was analyzed. The level of UV index at these sites was studied. The values of UV index higher than 12 at noon time of clear days are usually found in the summer at both sites. Seasonal variation of EUV at both sites was investigated. It was found that the tropical monsoons have strong influence on this variation. Finally, global broadband radiation measured at the sites was also used to establish a correlation between EUV and global broadband radiation. Higher correlation was found for the case of clear sky, as compared to the case of cloudy sky. The correlation obtained from this analysis can be used to estimate EUV from global broadband radiation at these two sites.

[Analysis of the cumulative solar ultraviolet radiation in Mexico].

PubMed

Castanedo-Cázares, Juan Pablo; Torres-Álvarez, Bertha; Portales-González, Bárbara; Martínez-Rosales, Karla; Hernández-Blanco, Diana

2016-01-01

The incidence of skin cancer has increased in Mexico in recent years. Ultraviolet radiation is the main risk factor associated. Due to the need to develop strategies to prevent skin cancer, the aim of the study was to estimate the UV intensity in several representative regions of Mexico, the average annual UV dose of these populations, and the potential benefit of applying sunscreen at different ages. The intensity of UV radiation was quantified by remote and terrestrial radiometry. The dose of UV exposure was measured in minimal erythema doses using validated models for face and arms. The benefit of using a sunscreen was calculated with the use of a sunscreen with SPF 15 from birth to age 70. The UV radiation is lower in December and greater in the period from May to July. The region with a lower annual dose is Tijuana; and the higher annual dose is in the Mexico City area. The annual difference between these regions was 58 %. Through life, a low SPF sunscreen can reduce up to 66 % of the received UV dose. The geographical location is a risk factor for accumulation of UV radiation in Mexico. Since childhood, people receive high amounts of it; however, most of this dose can be reduced using any commercially available sunscreen, if applied strategically.

Protective Effect of Chitin Urocanate Nanofibers against Ultraviolet Radiation

PubMed Central

Ito, Ikuko; Yoneda, Toshikazu; Omura, Yoshihiko; Osaki, Tomohiro; Ifuku, Shinsuke; Saimoto, Hiroyuki; Azuma, Kazuo; Imagawa, Tomohiro; Tsuka, Takeshi; Murahata, Yusuke; Ito, Norihiko; Okamoto, Yoshiharu; Minami, Saburo

2015-01-01

Urocanic acid is a major ultraviolet (UV)-absorbing chromophore. Chitins are highly crystalline structures that are found predominantly in crustacean shells. Alpha-chitin consists of microfibers that contain nanofibrils embedded in a protein matrix. Acid hydrolysis is a common method used to prepare chitin nanofibrils (NFs). We typically obtain NFs by hydrolyzing chitin with acetic acid. However, in the present study, we used urocanic acid to prepare urocanic acid chitin NFs (UNFs) and examined its protective effect against UVB radiation. Hos: HR-1 mice coated with UNFs were UVB irradiated (302 nm, 150 mJ/cm2), and these mice showed markedly lower UVB radiation-induced cutaneous erythema than the control. Additionally, sunburn cells were rarely detected in the epidermis of UNFs-coated mice after UVB irradiation. Although the difference was not as significant as UNFs, the number of sunburn cells in mice treated with acetic acid chitin nanofibrils (ANFs) tended to be lower than in control mice. These results demonstrate that ANFs have a protective effect against UVB and suggest that the anti-inflammatory and antioxidant effects of NFs influence the protective effect of ANFs against UVB radiation. The combination of NFs with other substances that possess UV-protective effects, such as urocanic acid, may provide an enhanced protective effect against UVB radiation. PMID:26703629

Ultraviolet Radiation Round-Robin Testing of Various Backsheets for Photovoltaic Modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koehl, Michael; Ballion, Amal; Lee, Yu-Hsien

2015-06-14

Durability testing of materials exposed to natural weathering requires testing of the ultraviolet (UV) stability, especially for polymeric materials. The type approval testing of photovoltaic (PV) modules according to standards IEC 61215 and IEC 61646, which includes a so-called UV preconditioning test with a total UV dose of 15 kWh/m2, does not correspond to the real loads during lifetime. Between 3%-10% of the UV radiation has to be in the spectral range between 280 and 320 nm (UV-B) in the recent editions of the standards. However, the spectral distribution of the radiation source is very important because different samples showmore » very individual spectral sensitivity for the radiation offered. Less than 6% of the intensity of solar radiation exists in the UV range. In the case of an increase of the intensity of the light source for accelerating the UV test, overheating of the samples would have to be prevented more rigorously and the temperature of the samples have to be measured to avoid misinterpretation of the test results.« less

Ion-kill dosimetry

NASA Technical Reports Server (NTRS)

Katz, R.; Cucinotta, F. A.; Fromm, M.; Chambaudet, A.

2001-01-01

Unanticipated late effects in neutron and heavy ion therapy, not attributable to overdose, imply a qualitative difference between low and high LET therapy. We identify that difference as 'ion kill', associated with the spectrum of z/beta in the radiation field, whose measurement we label 'ion-kill dosimetry'.

Hanford Internal Dosimetry Program Manual, PNL-MA-552

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2009-09-24

This manual is a guide to the services provided by the Hanford Internal Dosimetry Program (IDP), which is operated by the Pacific Northwest National Laboratory.( ) for the U.S. Department of Energy Richland Operations Office, Office of River Protection and their Hanford Site contractors. The manual describes the roles of and relationships between the IDP and the radiation protection programs of the Hanford Site contractors. Recommendations and guidance are also provided for consideration in implementing bioassay monitoring and internal dosimetry elements of radiation protection programs.

Ethylene Decomposition Initiated by Ultraviolet Radiation from Low Pressure Mercury Lamps: Kinetics Model Prediction and Experimental Verification.

NASA Astrophysics Data System (ADS)

Jozwiak, Zbigniew Boguslaw

1995-01-01

Ethylene is an important auto-catalytic plant growth hormone. Removal of ethylene from the atmosphere surrounding ethylene-sensitive horticultural products may be very beneficial, allowing an extended period of storage and preventing or delaying the induction of disorders. Various ethylene removal techniques have been studied and put into practice. One technique is based on using low pressure mercury ultraviolet lamps as a source of photochemical energy to initiate chemical reactions that destroy ethylene. Although previous research showed that ethylene disappeared in experiments with mercury ultraviolet lamps, the reactions were not described and the actual cause of ethylene disappearance remained unknown. Proposed causes for this disappearance were the direct action of ultraviolet rays on ethylene, reaction of ethylene with ozone (which is formed when air or gas containing molecular oxygen is exposed to radiation emitted by this type of lamp), or reactions with atomic oxygen leading to formation of ozone. The objective of the present study was to determine the set of physical and chemical actions leading to the disappearance of ethylene from artificial storage atmosphere under conditions of ultraviolet irradiation. The goal was achieved by developing a static chemical model based on the physical properties of a commercially available ultraviolet lamp, the photochemistry of gases, and the kinetics of chemical reactions. The model was used to perform computer simulations predicting time dependent concentrations of chemical species included in the model. Development of the model was accompanied by the design of a reaction chamber used for experimental verification. The model provided a good prediction of the general behavior of the species involved in the chemistry under consideration; however the model predicted lower than measured rate of ethylene disappearance. Some reasons for the model -experiment disagreement are radiation intensity averaging, the experimental

Dosimetry in dentistry.

PubMed

Asha, M L; Chatterjee, Ingita; Patil, Preeti; Naveen, S

2015-01-01

The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters. Several relevant PubMed indexed articles from 1999 to 2013 were electronically searched by typing "dosimeters", "dosimeters in dentistry", "properties of dosimeters", "thermoluminescent and optically stimulated dosimeters", "recent advancements in dosimetry in dentistry." The searches were limited to articles in English to prepare a concise review on dental dosimetry. Titles and abstracts were screened, and articles that fulfilled the criteria of use of dosimeters in dental applications were selected for a full-text reading. Article was divided into four groups: (1) Biological effects of radiation, (2) properties of dosimeters, (3) types of dosimeters and (4) results of various studies using different dosimeters. The present review on dosimetry based on various studies done with dosimeters revealed that, with the advent of radiographic technique the effective dose delivered is low. Therefore, selection of radiological technique plays an important role in dental dose delivery.

Pregnancy outcome and ultraviolet radiation; A systematic review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Megaw, Lauren, E-mail: lauren.megaw@ed.ac.uk

Background: Season and vitamin D are indirect and direct correlates of ultraviolet (UV) radiation and are associated with pregnancy outcomes. Further to producing vitamin D, UV has positive effects on cardiovascular and immune health that may support a role for UV directly benefitting pregnancy. Objectives: To investigate the effects of UV exposure on pregnancy; specifically fetal growth, preterm birth and hypertensive complications. Methods: We conducted a systematic review of Medline, EMBASE, DoPHER, Global Health, ProQuest Public Health, AustHealth Informit, SCOPUS and Google Scholar to identify 537 citations, 8 of which are included in this review. This review was registered onmore » PROSPERO and a. narrative synthesis is presented following PRISMA guidance. Results: All studies were observational and assessed at high risk of bias. Higher first trimester UV was associated with and improved fetal growth and increased hypertension in pregnancy. Interpretation is limited by study design and quality. Meta-analysis was precluded by the variety of outcomes and methods. Discussion: The low number of studies and risk of bias limit the validity of any conclusions. Environmental health methodological issues are discussed with consideration given to design and analytical improvements to further address this reproductive environmental health question. Conclusions: The evidence for UV having benefits for pregnancy hypertension and fetal growth is limited by the methodological approaches utilized. Future epidemiological efforts should focus on improving the methods of modeling and linking widely available environmental data to reproductive health outcomes. - Highlights: • Biologically plausible pathways support an association between ultraviolet radiation (UV) and pregnancy outcomes. • This study is the first systematic review of prevailing literature on the relationship between UV and singleton pregnancy outcomes. • It focuses on both substantive findings and the

Development of Ultraviolet (UV) Radiation Protective Fabric Using Combined Electrospinning and Electrospraying Technique

NASA Astrophysics Data System (ADS)

Sinha, Mukesh Kumar; Das, B. R.; Kumar, Kamal; Kishore, Brij; Prasad, N. Eswara

2017-06-01

The article reports a novel technique for functionization of nanoweb to develop ultraviolet (UV) radiation protective fabric. UV radiation protection effect is produced by combination of electrospinning and electrospraying technique. A nanofibrous web of polyvinylidene difluoride (PVDF) coated on polypropylene nonwoven fabric is produced by latest nanospider technology. Subsequently, web is functionalized by titanium dioxide (TiO2). The developed web is characterized for evaluation of surface morphology and other functional properties; mechanical, chemical, crystalline and thermal. An optimal (judicious) nanofibre spinning condition is achieved and established. The produced web is uniformly coated by defect free functional nanofibres in a continuous form of useable textile structural membrane for ultraviolet (UV) protective clothing. This research initiative succeeds in preparation and optimization of various nanowebs for UV protection. Field Emission Scanning Electron Microscope (FESEM) result reveals that PVDF webs photo-degradative behavior is non-accelerated, as compared to normal polymeric grade fibres. Functionalization with TiO2 has enhanced the photo-stability of webs. The ultraviolet protection factor of functionalized and non-functionalized nanowebs empirically evaluated to be 65 and 24 respectively. The developed coated layer could be exploited for developing various defence, para-military and civilian UV protective light weight clothing (tent, covers and shelter segments, combat suit, snow bound camouflaging nets). This research therefore, is conducted in an attempt to develop a scientific understanding of PVDF fibre coated webs for photo-degradation and applications for defence protective textiles. This technological research in laboratory scale could be translated into bulk productionization.

SU-E-J-17: A Study of Accelerator-Induced Cerenkov Radiation as a Beam Diagnostic and Dosimetry Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, F; Tosh, R

2014-06-01

Purpose: To investigate accelerator-induced Cerenkov radiation imaging as a possible beam diagnostic and medical dosimetry tool. Methods: Cerenkov emission produced by clinical accelerator beams in a water phantom was imaged using a camera system comprised of a high-sensitivity thermoelectrically-cooled CCD camera coupled to a large aperture (f/0.75) objective lens with 16:1 magnification. This large format lens allows a significant amount of the available Cerenkov light to be collected and focused onto the CCD camera to form the image. Preliminary images, obtained with 6 MV photon beams, used an unshielded camera mounted horizontally with the beam normal to the water surface,more » and confirmed the detection of Cerenkov radiation. Several improvements were subsequently made including the addition of radiation shielding around the camera, and altering of the beam and camera angles to give a more favorable geometry for Cerenkov light collection. A detailed study was then undertaken over a range of electron and photon beam energies and dose rates to investigate the possibility of using this technique for beam diagnostics and dosimetry. Results: A series of images were obtained at a fixed dose rate over a range of electron energies from 6 to 20 MeV. The location of maximum intensity was found to vary linearly with the energy of the beam. A linear relationship was also found between the light observed from a fixed point on the central axis and the dose rate for both photon and electron beams. Conclusion: We have found that the analysis of images of beam-induced Cerenkov light in a water phantom has potential for use as a beam diagnostic and medical dosimetry tool. Our future goals include the calibration of the light output in terms of radiation dose and development of a tomographic system for 3D Cerenkov imaging in water phantoms and other media.« less

Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia

2010-08-04

Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MSmore » displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.« less

Radiation Damage Effects in Far Ultraviolet Filters and Substrates

NASA Technical Reports Server (NTRS)

Keffer, Charles E.; Torr, Marsha R.; Zukic, Muamer; Spann, James F.; Torr, Douglas G.; Kim, Jongmin

1993-01-01

New advances in VUV thin film filter technology have been made using filter designs with multilayers of materials such as Al2O3, BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2. Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 X 9 R(sub E) orbit will expose the instrument to approximately 275 krads of radiation. In view of the fact that no previous studies have been made on potential radiation damage of these materials in the thin film format, we report on such an assessment here. Transmittances and reflectances of BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2 thin films on MgF2 substrates, Al2O3 thin films on fused silica substrates, uncoated fused silica and MgF2, and four multilayer filters made from these materials were measured from 120 nm to 180 nm before and after irradiation by 250 krads from a Co-60 gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 nm to 300 nm indicated a 3 - 5% radiation-induced absorption near 260 nm in some of the samples with MgF2 substrates. From these measurements it is concluded that far ultraviolet filters made from the materials tested should experience less that 5% change from exposure to up to 250 krads of high energy radiation in space applications.

Fine Forecasts: Encouraging the Media to Include Ultraviolet Radiation Information in Summertime Weather Forecasts

ERIC Educational Resources Information Center

Richards, R.; Reeder, A. I.; Bulliard, J.-L.

2004-01-01

Melanoma and skin cancer are largely attributable to over-exposure to solar ultraviolet radiation (UVR). Reports of UVR levels within media weather forecasts appear to be well received by the public and have good potential to communicate the need for appropriate sun protection to a broad audience. This study describes provision of UVR messages by…

Thermoluminescence Dosimetry (TLD) and its Application in Medical Physics

NASA Astrophysics Data System (ADS)

Azorín Nieto, Juan

2004-09-01

Radiation dosimetry is fundamental in Medical Physics, involving patients and phantom dosimetry. In both cases thermoluminescence dosimetry (TLD) is the most appropriate technique for measuring the absorbed dose. In this paper thermoluminescence phenomenon as well as the use of TLD in radiodiagnosis and radiotherapy for in vivo or in phantom measurements is discussed. Some results of measurements made in radiotherapy and radiodiagnosis using home made LiF:Mg,Cu,P+PTFE TLD are presented.

Ultraviolet radiation and the snow alga Chlamydomonas nivalis (Bauer) Wille.

PubMed

Gorton, Holly L; Vogelmann, Thomas C

2003-06-01

Aplanospores of Chlamydomonas nivalis are frequently found in high-altitude, persistent snowfields where they are photosynthetically active despite cold temperatures and high levels of visible and ultraviolet (UV) radiation. The goals of this work were to characterize the UV environment of the cells in the snow and to investigate the existence and localization of screening compounds that might prevent UV damage. UV irradiance decreased precipitously in snow, with UV radiation of wavelengths 280-315 nm and UV radiation of wavelengths 315-400 nm dropping to 50% of incident levels in the top 1 and 2 cm, respectively. Isolated cell walls exhibited UV absorbance, possibly by sporopollenin, but this absorbance was weak in images of broken or plasmolyzed cells observed through a UV microscope. The cells also contained UV-absorbing cytoplasmic compounds, with the extrachloroplastic carotenoid astaxanthin providing most of the screening. Additional screening compound(s) soluble in aqueous methanol with an absorption maximum at 335 nm played a minor role. Thus, cells are protected against potentially high levels of UV radiation by the snow itself when they live several centimeters beneath the surface, and they rely on cellular screening compounds, chiefly astaxanthin, when located near the surface where UV fluxes are high.

Lethal effects of artificial ultraviolet radiation on cereal rust uredospores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddison, A.C.; Manners, J.G.

1973-06-01

Monochromatic far and near ultraviolet and polychromatic radiation reduced uredospore (urediniospore) germinability in Puccinia striiformis West., P. recondita Rob. & Desm. f. sp. tritici Eriks. & Henn., and P. graminis Pers. f. sp. tritici Eriks. &. Henn. survival decreasing approximately logarithmically beyond an initial shoulder on the dose-survival curve. Infectivity was three to six times more sensitive than germinability to germicidal lamp radiation. Sensitivity to germicidal lamp radiation in P. striiformis was independent of temperature, but was greater at high relative humidities than at low. Reciprocity of time and dose rate was demonstrated when this species was subjected to suchmore » radiation. Action spectra for loss of germiability suggested nucleic acids and proteins respectively as chromophores in P. striiformis and P. graminis: data from photoreactivation experiments implied nucleic acid involvement in both species. Sunlamp and simulated sunlight exposures showed uredospores to be sensitive to naturally occurring wavelengths at dose levels received at the earth's surface. The ratio of the doses necessary to reduce germinability to 10% of the contro1 value for P. striiformis, P. recondita, and P. graminis uredospores was 1.0: 1.5 to 2.2:3 to 3.5 after irradiation by the various sources. (auth)« less

EFFECT OF ARSENICALS ON ULTRAVIOLET-RADIATION-INDUCED GROWTH ARREST AND RELATED SIGNALING EVENTS IN HUMAN KERATINOCYTES

EPA Science Inventory

The molecular mechanisms mediating arsenic-induced carcinogenesis are not well understood. The role of confounding factors such as ultraviolet radiation (UV), add another level of complexity to the study of arsenic carcinogenesis and the cancer risk assessment to humans. We hypot...

Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

NASA Technical Reports Server (NTRS)

Dever, Joyce A.

1991-01-01

Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO.

Impact of ultraviolet radiation treatments on the physicochemical properties, antioxidants, enzyme activity and microbial load in freshly prepared hand pressed strawberry juice.

PubMed

Bhat, Rajeev; Stamminger, Rainer

2015-07-01

Freshly prepared, hand-pressed strawberry fruit juice was exposed to ultraviolet radiation (254 nm) at room temperature (25 ℃ ± 1 ℃) for 15, 30 and 60 min with 0 min serving as control. Results revealed decrease in pH, total soluble solids and titratable acidity, while colour parameters (L*, a* and b* values) and clarity of juice (% transmittance) increased significantly. All the results corresponded to exposure time to ultraviolet radiation. Bioactive compounds (total phenolics, ascorbic acid and anthocyanins) decreased along with a recorded reduction in polyphenol oxidase enzyme and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activities, which were again dependent on exposure time. Results on the microbial studies showed significant reduction by 2-log cycles in aerobic plate count as well as in total yeast and mould counts. Though negative results were observed for certain parameters, this is the first time it was endeavoured to demonstrate the impact of ultraviolet radiation radiation on freshly prepared, hand-pressed strawberries juice. © The Author(s) 2014.

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications.

PubMed

Pradhan, A S; Lee, J I; Kim, J L

2008-07-01

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al(2)O(3):C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al(2)O(3):C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF(3):Eu(2+) appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al(2)O(3):C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications

PubMed Central

Pradhan, A. S.; Lee, J. I.; Kim, J. L.

2008-01-01

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al2O3:C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al2O3:C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF3:Eu2+ appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al2O3:C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose

The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

NASA Astrophysics Data System (ADS)

Maynard, Matthew R.; Geyer, John W.; Aris, John P.; Shifrin, Roger Y.; Bolch, Wesley

2011-08-01

Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR™ and then imported to the 3D modeling software package Rhinoceros™ for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in

Protective effect of rare earth against oxidative stress under ultraviolet-B radiation.

PubMed

Wang, Lihong; Huang, Xiaohua; Zhou, Qing

2009-04-01

The effects of lanthanum (III) (La(III)) in protecting soybean leaves against oxidative stress induced by ultraviolet-B (UV-B) radiation were investigated. The increase in contents of hydrogen peroxide (H(2)O(2)) and superoxide (O2*-) due to UV-B radiation suggested oxidative stress. The increase in the content of malondialdehyde (MDA) and the decrease in the index of unsaturated fatty acid (IUFA) indicated oxidative damage on cell membrane induced by UV-B radiation. La(III) partially reversed UV-B-radiation-induced damage of plant growth. The reduction in the contents of H(2)O(2), O2*-, and MDA and increase in the content of IUFA, compared with UV-B treatment, also indicated that La(III) alleviated the oxidative damage induced by UV-B radiation. The increase in the activities of superoxide dismutase and peroxidase and the contents of ascorbate, carotenoids, and flavonoids were observed in soybean leaves with La(III) + UV-B treatment, compared with UV-B treatment. Our data suggested that La(III) could protect soybean plants from UV-B-radiation-induced oxidative stress by reacting with reactive oxygen species directly or by improving the defense system of plants.

Gene expression-based dosimetry by dose and time in mice following acute radiation exposure.

PubMed

Tucker, James D; Divine, George W; Grever, William E; Thomas, Robert A; Joiner, Michael C; Smolinski, Joseph M; Auner, Gregory W

2013-01-01

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to (60)Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4-7 different gene transcripts are needed to explain ≥ 0.69 of the variance (R(2)), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ≥ 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations.

Inclusion of an ultraviolet radiation transfer component in an urban forest effects model for predicting tree influences on potential below-canopy exposure to UVB radiation

Treesearch

Gordon M. Heisler; Richard H. Grant; David J. Nowak; Wei Gao; Daniel E. Crane; Jeffery T. Walton

2003-01-01

Evaluating the impact of ultraviolet-B radiation (UVB) on urban populations would be enhanced by improved predictions of the UVB radiation at the level of human activity. This paper reports the status of plans for incorporating a UVB prediction module into an existing Urban Forest Effects (UFORE) model. UFORE currently has modules to quantify urban forest structure,...

Evaluation of an enclosed ultraviolet-C radiation device for decontamination of mobile handheld devices.

PubMed

Mathew, J Itty; Cadnum, Jennifer L; Sankar, Thriveen; Jencson, Annette L; Kundrapu, Sirisha; Donskey, Curtis J

2016-06-01

Mobile handheld devices used in health care settings may become contaminated with health care-associated pathogens. We demonstrated that an enclosed ultraviolet-C radiation device was effective in rapidly reducing methicillin-resistant Staphylococcus aureus, and with longer exposure times, Clostridium difficile spores, on glass slides and reducing contamination on in-use mobile handheld devices. Published by Elsevier Inc.

Method for generating extreme ultraviolet with mather-type plasma accelerators for use in Extreme Ultraviolet Lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassanein, Ahmed; Konkashbaev, Isak

A device and method for generating extremely short-wave ultraviolet electromagnetic wave uses two intersecting plasma beams generated by two plasma accelerators. The intersection of the two plasma beams emits electromagnetic radiation and in particular radiation in the extreme ultraviolet wavelength. In the preferred orientation two axially aligned counter streaming plasmas collide to produce an intense source of electromagnetic radiation at the 13.5 nm wavelength. The Mather type plasma accelerators can utilize tin, or lithium covered electrodes. Tin, lithium or xenon can be used as the photon emitting gas source.

Ultraviolet radiation from the pulsed corona discharge in water

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Sunka, Pavel

2008-05-01

Quantitative analysis of ultraviolet radiation from the pulsed corona discharge in water with needle-plate electrode geometry (~1-3 J pulse-1) was performed using the potassium ferrioxalate actinometry. Photon flux J190-280 and radiant energy Q190-280 of the UV light emitted from the discharge at spectral region 190-280 nm was determined in dependence on the applied voltage (17-29 kV, positive polarity) and the solution conductivity (100-500 µS cm-1). The intensity of the UV radiation strongly increased with increasing water conductivity and applied voltage. Depending on the applied voltage the determined photon flux varied by more than two orders of magnitude within the range of solution conductivities 100-500 µS cm-1. It was found that photon flux from the discharge may be directly related to the discharge pulse mean power Pp as J190-280 = 44.33 P_p^{2.11} (quanta pulse-1). A significant role of UV radiation in the production of hydrogen peroxide and bacterial inactivation by the corona discharge in water has been identified. As the solution conductivity increased the yield of H2O2 produced by the discharge decreased due to increasing photolysis of H2O2 accounting for up to 14% of the total decomposition rate of H2O2. As regards bactericidal effects, it was estimated that the UV radiation contributes about 30% to the overall inactivation of Escherichia coli.

Reactor Dosimetry Applications Using RAPTOR-M3G:. a New Parallel 3-D Radiation Transport Code

NASA Astrophysics Data System (ADS)

Longoni, Gianluca; Anderson, Stanwood L.

2009-08-01

The numerical solution of the Linearized Boltzmann Equation (LBE) via the Discrete Ordinates method (SN) requires extensive computational resources for large 3-D neutron and gamma transport applications due to the concurrent discretization of the angular, spatial, and energy domains. This paper will discuss the development RAPTOR-M3G (RApid Parallel Transport Of Radiation - Multiple 3D Geometries), a new 3-D parallel radiation transport code, and its application to the calculation of ex-vessel neutron dosimetry responses in the cavity of a commercial 2-loop Pressurized Water Reactor (PWR). RAPTOR-M3G is based domain decomposition algorithms, where the spatial and angular domains are allocated and processed on multi-processor computer architectures. As compared to traditional single-processor applications, this approach reduces the computational load as well as the memory requirement per processor, yielding an efficient solution methodology for large 3-D problems. Measured neutron dosimetry responses in the reactor cavity air gap will be compared to the RAPTOR-M3G predictions. This paper is organized as follows: Section 1 discusses the RAPTOR-M3G methodology; Section 2 describes the 2-loop PWR model and the numerical results obtained. Section 3 addresses the parallel performance of the code, and Section 4 concludes this paper with final remarks and future work.

Treating voxel geometries in radiation protection dosimetry with a patched version of the Monte Carlo codes MCNP and MCNPX.

PubMed

Burn, K W; Daffara, C; Gualdrini, G; Pierantoni, M; Ferrari, P

2007-01-01

The question of Monte Carlo simulation of radiation transport in voxel geometries is addressed. Patched versions of the MCNP and MCNPX codes are developed aimed at transporting radiation both in the standard geometry mode and in the voxel geometry treatment. The patched code reads an unformatted FORTRAN file derived from DICOM format data and uses special subroutines to handle voxel-to-voxel radiation transport. The various phases of the development of the methodology are discussed together with the new input options. Examples are given of employment of the code in internal and external dosimetry and comparisons with results from other groups are reported.

Floating Gate sensor for in-vivo dosimetry in radiation therapies. Design and first characterization.

NASA Astrophysics Data System (ADS)

Faigon, A.; Martinez Vazquez, I.; Carbonetto, S.; García Inza, M.; G

2017-01-01

A floating gate dosimeter was designed and fabricated in a standard CMOS technology. The design guides and characterization are presented. The characterization included the controlled charging by tunneling of the floating gate, and its discharging under irradiation while measuring the transistor drain current whose change is the measure of the absorbed dose. The resolution of the obtained device is close to 1 cGy satisfying the requirements for most radiation therapies dosimetry. Pending statistical proofs, the dosimeter is a potential candidate for wide in-vivo control of radiotherapy treatments.

Jaw Dysfunction Related to Pterygoid and Masseter Muscle Dosimetry After Radiation Therapy in Children and Young Adults With Head-and-Neck Sarcomas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasin, Matthew J., E-mail: matthew.krasin@stjude.org; Wiese, Kristin M.; Spunt, Sheri L.

Purpose: To investigate the relationship between jaw function, patient and treatment variables, and radiation dosimetry of the mandibular muscles and joints in children and young adults receiving radiation for soft-tissue and bone sarcomas. Methods and Materials: Twenty-four pediatric and young adult patients with head-and-neck sarcomas were treated on an institutional review board-approved prospective study of focal radiation therapy for local tumor control. Serial jaw depression measurements were related to radiation dosimetry delivered to the medial and lateral pterygoid muscles, masseter muscles, and temporomandibular joints to generate mathematical models of jaw function. Results: Baseline jaw depression was only influenced by themore » degree of surgical resection. In the first 12 weeks from initiation of radiation, surgical procedures greater than a biopsy, administration of cyclophosphamide containing chemotherapy regimes, and large gross tumor volumes adversely affected jaw depression. Increasing dose to the pterygoid and masseter muscles above 40 Gy predicted loss of jaw function over the full course of follow-up. Conclusions: Clinical and treatment factors are related to initial and subsequent jaw dysfunction. Understanding these complex interactions and the affect of specific radiation doses may help reduce the risk for jaw dysfunction in future children and young adults undergoing radiation therapy for the management of soft-tissue and bone sarcomas.« less

QUANTIFYING ULTRAVIOLET RADIATION DOSE RELATIVE TO WETLAND HABITAT VARIABLES FOR THE ASSESSMENT OF RISK TO AMPHIBIANS

EPA Science Inventory

Ultraviolet B radiation (UV-B) has increased globally over the last several decades due to reduction of stratospheric ozone. UV-B may also increase when climate change alters cloud cover, rainfall, and distributions of vegetation. In aquatic systems, these factors can also intera...

Interactions of Changing Solar Ultraviolet Radiation and Climate with Light Induced Chemical Reactions in Aquatic Environments

EPA Science Inventory

Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet radiation that reach the surface of North American aquatic environments. Concurrent changes in atmospheric CO2 are resulting in changes in stratification and precipitation that ar...

An immunohistochemical panel to assess ultraviolet radiation-associated oxidative skin injury.

PubMed

Mamalis, A; Fiadorchanka, N; Adams, L; Serravallo, M; Heilman, E; Siegel, D; Brody, N; Jagdeo, J

2014-05-01

Ultraviolet (UV) radiation results in a significant loss in years of healthy life, approximately 1.5 million disability-adjusted life years (DALYs), and is associated with greater than 60,000 deaths annually worldwide that are attributed to melanoma and other skin cancers. Currently, there are no standardized biomarkers or assay panels to assess oxidative stress skin injury patterns in human skin exposed to ionizing radiation. Using biopsy specimens from chronic solar UV-exposed and UV-protected skin, we demonstrate that UV radiation-induced oxidative skin injury can be evaluated by an immunohistochemical panel that stains 8-hydroxydeoxyguanosine (8-OH-dG) to assess DNA adducts, 4-hydroxy-2-nonenal (HNE) to assess lipid peroxidation, and advanced glycation end products (AGEs) to assess protein damage. We believe this panel contains the necessary cellular biomarkers to evaluate topical agents, such as sunscreens and anti-oxidants that are designed to prevent oxidative skin damage and may reduce UV-associated skin aging, carcinogenesis, and inflammatory skin diseases. We envision that this panel will become an important tool for researchers developing topical agents to protect against UV radiation and other oxidants and ultimately lead to reductions in lost years of healthy life, DALYs, and annual deaths associated with UV radiation.

Fundamentals of materials, techniques and instrumentation for OSL and FNTD dosimetry

NASA Astrophysics Data System (ADS)

Akselrod, M. S.

2013-02-01

The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al2O3:C as a material of choice for many dosimetric applications including fiberoptic OSL/RL sensors with diameters as small as 300 μm. A new RL/OSL fiberoptic system has a high potential for in vivo and in vitro dosimetry in both radiation therapy and diagnostic mammography. Different aspects of instrumentation, data processing algorithms, post-irradiation and real-time measurements are described. The next technological breakthrough was done with Fluorescent Nuclear Track detectors (FNTD) that has some important advantages in measuring fast neutron and high energy heavy charge particles that became the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology were engineered and successfully demonstrated for occupational and accident dosimetry, for medical dosimetry and radiobiological research.

Method for extreme ultraviolet lithography

DOEpatents

Felter, T. E.; Kubiak, Glenn D.

1999-01-01

A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods.

Method for extreme ultraviolet lithography

DOEpatents

Felter, T. E.; Kubiak, G. D.

2000-01-01

A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods.

The creation of radiation dominated plasmas using laboratory extreme ultra-violet lasers

NASA Astrophysics Data System (ADS)

Tallents, G. J.; Wilson, S.; West, A.; Aslanyan, V.; Lolley, J.; Rossall, A. K.

2017-06-01

Ionization in experiments where solid targets are irradiated by high irradiance extreme ultra-violet (EUV) lasers is examined. Free electron degeneracy effects on ionization in the presence of a high EUV flux of radiation is shown to be important. Overlap of the physics of such plasmas with plasma material under compression in indirect inertial fusion is explored. The design of the focusing optics needed to achieve high irradiance (up to 1014 Wcm-2) using an EUV capillary laser is presented.

Ultraviolet radiation emitted by lamps, TVs, tablets and computers: are there risks for the population?

PubMed

Duarte, Ida Alzira Gomes; Hafner, Mariana de Figueiredo Silva; Malvestiti, Andrey Augusto

2015-01-01

The frequent human exposure to various types of indoor lamps, as well as other light sources (television monitors, tablets and computers), raises a question: are there risks for the population? In the present study the emission of UVA and UVB radiation by lamps and screens of electronic devices were measured in order to determine the safe distance between the emitting source and the individual. We concluded that the lamps and electronic devices do not emit ultraviolet radiation; so they pose no health risk for the population.

Dosimetry with diamond detectors

NASA Astrophysics Data System (ADS)

Gervino, G.; Marino, C.; Silvestri, F.; Lavagno, A.; Truc, F.

2010-05-01

In this paper we present the dosimetry analysis in terms of stability and repeatability of the signal and dose rate dependence of a synthetic single crystal diamond grown by Chemical Vapor Deposition (CVD) technique. The measurements carried out by 5 MeV X-ray photons beam show very promising results, even if the dose rate detector response points out that the charge trapping centers distribution is not uniform inside the crystal volume. This handicap that affects the detectors performances, must be ascribed to the growing process. Synthetic single crystal diamonds could be a valuable alternative to air ionization chambers for quality beam control and for intensity modulated radiation therapy beams dosimetry.

Minimum exposure limits and measured relationships between the vitamin D, erythema and international commission on non-ionizing radiation protection solar ultraviolet.

PubMed

Downs, Nathan; Parisi, Alfio; Butler, Harry; Turner, Joanna; Wainwright, Lisa

2015-01-01

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has established guidelines for exposure to ultraviolet radiation in outdoor occupational settings. Spectrally weighted ICNIRP ultraviolet exposures received by the skin or eye in an 8 h period are limited to 30 J m(-2). In this study, the time required to reach the ICNIRP exposure limit was measured daily in 10 min intervals upon a horizontal plane at a subtropical Australian latitude over a full year and compared with the effective Vitamin D dose received to one-quarter of the available skin surface area for all six Fitzpatrick skin types. The comparison of measured solar ultraviolet exposures for the full range of sky conditions in the 2009 measurement period, including a major September continental dust event, show a clear relationship between the weighted ICNIRP and the effective vitamin D dose. Our results show that the horizontal plane ICNIRP ultraviolet exposure may be used under these conditions to provide minimum guidelines for the healthy moderation of vitamin D, scalable to each of the six Fitzpatrick skin types. © 2014 The American Society of Photobiology.

Prediction of skin cancer occurrence by ultraviolet solar index

PubMed Central

Rivas, Miguel; Rojas, Elisa; Calaf, Gloria M.

2012-01-01

An increase in the amount of solar ultraviolet light that reaches the Earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that exposure to excessive levels of solar ultraviolet light has multiple effects, which can be harmful to humans. Experimental ultraviolet light measurements were obtained in several locations in Chile between 2006 and 2009 using wide-band solar light Biometer YES, calibrated according to World Meteorological Organization (WMO) criteria and integrated into the National Meteorological Center of Chile ultraviolet network (DMC). The aim of this study was to determine skin cancer rates in relation to experimental data accumulated during one year of studying the solar ultraviolet index in Chile, in order to explain the possible effect of radiation on skin cancer. The rate of skin cancer per 100,000 persons was considered in Arica, Santiago, Concepción and Valdivia and extrapolated to other cities. Results of the present study showed that the incidence of skin cancer was markedly correlated with accumulative ultraviolet radiation, and rates of skin cancer could be extrapolated to other locations in Chile. There is a steady increase in the rate of skin cancer in cities located nearest to the equator (low latitude) that receive greater accumulated solar ultraviolet radiation, due to the accumulative effects of this type of radiation on the skin. It can be concluded that Arica is a city at sea level that receives higher levels of ultraviolet solar radiation than other locations, which may explain the higher prevalence of skin cancer in the population of this location, compared with other cities in Chile. PMID:22741013

Effects of ultraviolet radiation and contaminant-related stressors on arctic freshwater ecosystems.

PubMed

Wrona, Frederick J; Prowse, Terry D; Reist, James D; Hobbie, John E; Lévesque, Lucie M J; Macdonald, Robie W; Vincent, Warwick F

2006-11-01

Climate change is likely to act as a multiple stressor, leading to cumulative and/or synergistic impacts on aquatic systems. Projected increases in temperature and corresponding alterations in precipitation regimes will enhance contaminant influxes to aquatic systems, and independently increase the susceptibility of aquatic organisms to contaminant exposure and effects. The consequences for the biota will in most cases be additive (cumulative) and multiplicative (synergistic). The overall result will be higher contaminant loads and biomagnification in aquatic ecosystems. Changes in stratospheric ozone and corresponding ultraviolet radiation regimes are also expected to produce cumulative and/or synergistic effects on aquatic ecosystem structure and function. Reduced ice cover is likely to have a much greater effect on underwater UV radiation exposure than the projected levels of stratospheric ozone depletion. A major increase in UV radiation levels will cause enhanced damage to organisms (biomolecular, cellular, and physiological damage, and alterations in species composition). Allocations of energy and resources by aquatic biota to UV radiation protection will increase, probably decreasing trophic-level productivity. Elemental fluxes will increase via photochemical pathways.

Average latitudinal variation in ultraviolet radiation at the earth's surface. [biological sensitivity and dosage

NASA Technical Reports Server (NTRS)

Johnson, F. S.; Mo, T.; Green, A. E. S.

1976-01-01

Tabulated values are presented for ultraviolet radiation at the earth's surface as a function of wavelength, latitude, and season, for clear sky and seasonally and latitudinally averaged ozone amounts. These tabulations can be combined with any biological sensitivity function in order to obtain the seasonal and latitudinal variation of the corresponding effective doses. The integrated dosages, based on the erythemal sensitivity curve and on the Robertson-Berger sunburn-meter sensitivity curve, have also been calculated, and these are found to vary with latitude and season in very nearly the same way as 307 and 314 nm radiation, respectively.

Resistance of a lizard (the green anole, Anolis carolinensis; Polychridae) to ultraviolet radiation-induced immunosuppression

USGS Publications Warehouse

Cope, R.B.; Fabacher, D.L.; Lieske, C.; Miller, C.A.

2001-01-01

The green anole (Anolis carolinensis) is the most northerly distributed of its Neotropical genus. This lizard avoids a winter hibernation phase by the use of sun basking behaviors. Inevitably, this species is exposed to high doses of ambient solar ultraviolet radiation (UVR). Increases in terrestrial ultraviolet-B (UV-B) radiation secondary to stratospheric ozone depletion and habitat perturbation potentially place this species at risk of UVR-induced immunosuppression. Daily exposure to subinflammatory UVR (8 kJ/m2/day UV-B, 85 kJ/m2/day ultraviolet A [UV-A]), 6 days per week for 4 weeks (total cumulative doses of 192 kJ/m2 UV-B, 2.04 × 103 kJ/m2 UV-A) did not suppress the anole's acute or delayed type hypersensitivity (DTH) response to horseshoe crab hemocyanin. In comparison with the available literature UV-B doses as low as 0.1 and 15.9 kJ/m2 induced suppression of DTH responses in mice and humans, respectively. Exposure of anoles to UVR did not result in the inhibition of ex vivo splenocyte phagocytosis of fluorescein labeled Escherichia coli or ex vivo splenocyte nitric oxide production. Doses of UV-B ranging from 0.35 to 45 kJ/m2 have been reported to suppress murine splenic/peritoneal macrophage phagocytosis and nitric oxide production. These preliminary studies demonstrate the resistance of green anoles to UVR-induced immunosuppression. Methanol extracts of anole skin contained two peaks in the ultraviolet wavelength range that could be indicative of photoprotective substances. However, the resistance of green anoles to UVR is probably not completely attributable to absorption by UVR photoprotective substances in the skin but more likely results from a combination of other factors including absorption by the cutis and absorption and reflectance by various components of the dermis.

DISTRIBUTION PATTERNS OF LENTIC-BREEDING AMPHIBIANS IN RELATION OF ULTRAVIOLET RADIATION EXPOSURE IN WESTERN NORTH AMERICA

EPA Science Inventory

An increase in ultraviolet (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population...Much more work is still needed to determine whether UV-B, either alone or in concert with other factors, is causing widespread population losses in ...

Modeling TiO2 nanoparticle phototoxicity: The importance of chemical concentration, ultraviolet radiation intensity, and time

EPA Science Inventory

Toxicity of TiO2 nanoparticles (nano-TiO2) to aquatic organisms can be greatly increased upon the exposure to ultraviolet radiation (UV). This phenomenon has received some attention for pelagic species, however, investigations of nano-TiO2 phototoxicity in benthic organisms are s...

Initial Results from the Radiation Dosimetry Experiment (RaD-X) Balloon Flight Mission

NASA Technical Reports Server (NTRS)

Mertens, Christopher J.

2015-01-01

The NASA Radiation Dosimetry Experiment (RaD-X) high-altitude balloon mission was successfully launched from Fort Sumner, New Mexico USA on 25 September, 2015. Over 15 hours of science data were obtained from four dosimeters at altitudes above about 25 km. The four dosimeters flown on the RaD-X science payload are a Hawk version 3.0 Tissue Equivalent Proportional Counter (TEPC) manufactured by Far West Technologies, a Liulin dosimeter-spectrometer produced by the Solar Research and Technology Institute, Bulgarian Academy of Sciences, a total ionizing dose detector manufactured by Teledyne Microelectronic Technologies, and the RaySure detector provided by the University of Surrey.

Software tool for portal dosimetry research.

PubMed

Vial, P; Hunt, P; Greer, P B; Oliver, L; Baldock, C

2008-09-01

This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.

DRDC Ottawa Participation in the SILENE Accident Dosimetry Intercomparison Exercise. June 10-21, 2002

DTIC Science & Technology

2002-11-01

of CaF2:Mn and A120 3 TLDs for gamma-ray dosimetry ). In addition, DRDC Ottawa has recently substantially expanded its efforts in radiation dosimetry ...use of any real- time electronic dosimeter. Foils have long been proposed and used for criticality dosimetry (as well as for general monitoring of...ray Dosimetry DRDC Ottawa offers a number (over five) of various thermoluminescence dosimetry ( TLD ) systems. The choice of any particular TLD depends

Ultraviolet radiation emitted by lamps, TVs, tablets and computers: are there risks for the population?

PubMed Central

Duarte, Ida Alzira Gomes; Hafner, Mariana de Figueiredo Silva; Malvestiti, Andrey Augusto

2015-01-01

The frequent human exposure to various types of indoor lamps, as well as other light sources (television monitors, tablets and computers), raises a question: are there risks for the population? In the present study the emission of UVA and UVB radiation by lamps and screens of electronic devices were measured in order to determine the safe distance between the emitting source and the individual. We concluded that the lamps and electronic devices do not emit ultraviolet radiation; so they pose no health risk for the population. PMID:26375236

Assessing children's ultraviolet radiation exposure: the potential usefulness of a colorimeter.

PubMed

Eckhardt, L; Mayer, J A; Creech, L; Johnston, M R; Lui, K J; Sallis, J F; Elder, J P

1996-12-01

This study evaluated the colorimeter as an objective measure of children's ultraviolet (UV) radiation exposure. Fifty-eight children, ages 6 to 9 years, attended two summer measurement sessions, with 46 attending a subsequent winter session. Comparisons between summer sessions for the L* scale showed that only the upper arm significantly changed in the tanner direction, while b* scale values indicated significant tanning for all body sites. All exposed body sites changed significantly in the less tan direction between summer and winter measurements. Using colorimeters to objectively measure children's UV exposure has potential applications for skin cancer prevention programs.

Ultraviolet radiation as disinfection for fish surgical tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Ricardo W.; Markillie, Lye Meng; Colotelo, Alison HA

Telemetry is frequently used to examine the behavior of fish, and the transmitters used are normally surgically implanted into the coelomic cavity of fish. Implantation requires the use of surgical tools such as scalpels, forceps, needle holders, and sutures. When fish are implanted consecutively, as in large telemetry studies, it is common for surgical tools to be sterilized or, at minimum, disinfected between each use so that pathogens that may be present are not spread among fish. To determine the efficacy for this application, ultraviolet (UV) radiation was used to disinfect surgical tools exposed to one of four aquatic organismsmore » that typically lead to negative health issues for salmonids. These organisms included Aeromonas salmonicida, Flavobacterium psychrophilum, Renibacterium salmoninarum, and Saprolegnia parasitica, causative agents of furunculosis, coldwater disease, bacterial kidney disease, and saprolegniasis (water mold), respectively. Four experiments were conducted to address the question of UV efficacy. In the first experiment, forceps were exposed to the three bacteria at three varying concentrations. After exposure to the bacterial culture, tools were placed into a mobile Millipore UV sterilization apparatus. The tools were then exposed for three different time periods – 2, 5, or 15 min. UV radiation exposures at all durations were effective at killing all three bacteria on forceps at the highest bacteria concentrations. In the second experiment, stab scalpels, sutures, and needle holders were exposed to A. salmonicida using the same methodology as used in Experiment 1. UV radiation exposure at 5 and 15 min was effective at killing A. salmonicida on stab scalpels and sutures but not needle holders. In the third experiment, S. parasitica, a water mold, was tested using an agar plate method and forceps-pinch method. UV radiation was effective at killing the water mold at all three exposure durations. Collectively, this study shows that UV

Relationship between student selection criteria and learner success for medical dosimetry students

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Jamie, E-mail: jabaker@mdanderson.org; Tucker, Debra; Raynes, Edilberto

Medical dosimetry education occupies a specialized branch of allied health higher education. Noted international shortages of health care workers, reduced university funding, limitations on faculty staffing, trends in learner attrition, and increased enrollment of nontraditional students force medical dosimetry educational leadership to reevaluate current admission practices. Program officials wish to select medical dosimetry students with the best chances of successful graduation. The purpose of the quantitative ex post facto correlation study was to investigate the relationship between applicant characteristics (cumulative undergraduate grade point average (GPA), science grade point average (SGPA), prior experience as a radiation therapist, and previous academic degrees)more » and the successful completion of a medical dosimetry program, as measured by graduation. A key finding from the quantitative study was the statistically significant positive correlation between a student's previous degree and his or her successful graduation from the medical dosimetry program. Future research investigations could include a larger research sample, representative of more medical dosimetry student populations, and additional studies concerning the relationship of previous work as a radiation therapist and the effect on success as a medical dosimetry student. Based on the quantitative correlation analysis, medical dosimetry leadership on admissions committees could revise student selection rubrics to place less emphasis on an applicant's undergraduate cumulative GPA and increase the weight assigned to previous degrees.« less

A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry.

PubMed

Quast, Ulrich; Kaulich, Theodor W; Álvarez-Romero, José T; Carlsson Tedgren, Sa; Enger, Shirin A; Medich, David C; Mourtada, Firas; Perez-Calatayud, Jose; Rivard, Mark J; Zakaria, G Abu

2016-06-01

In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector's response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector's response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources. This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon's penetration probability and scattering potential. Copyright © 2016. Published by Elsevier Ltd.

SU-E-QI-15: Single Point Dosimetry by Means of Cerenkov Radiation Energy Transfer (CRET)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Volotskova, O; Jenkins, C; Xing, L

2014-06-15

Purpose: Cerenkov light is generated when a charged particles with energy greater then 250 keV, moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons during the static megavoltage linear accelerator (LINAC) operational mode. Recently, Cerenkov radiation gained considerable interest as possible candidate as a new imaging modality. Optical signals generated by Cerenkov radiation may act as a surrogate for the absorbed superficial radiation dose. We demonstrated a novel single point dosimetry method for megavoltage photon and electron therapy utilizing down conversion of Cerenkov photons. Methods: The custom build signalmore » characterization system was used: a sample holder (probe) with adjacent light tight compartments was connected via fiber-optic cables to a photon counting photomultiplier tube (PMT). One compartment contains a medium only while the other contains medium and red-shifting nano-particles (Q-dots, nanoclusters). By taking the difference between the two signals (Cerenkov photons and CRET photons) we obtain a measure of the down-converted light, which we expect to be proportional to dose as measured with an adjacent ion chamber. Experimental results are compared to Monte Carlo simulations performed using the GEANT4 code. Results: The signal correlation between CR signal, CRET readings and dose produced by LINAC at a single point were investigated. The experimental results were compared with simulations. The dose linearity, signal to noise ratio and dose rate dependence were tested with custom build CRET based probe. Conclusion: Performance characteristics of the proposed single point CRET based probe were evaluated. The direct use of the induced Cerenkov emission and CRET in an irradiated single point volume as an indirect surrogate for the imparted dose was investigated. We conclude that CRET is a promising optical based dosimetry method that offers advantages over those already

Ultraviolet radiation cataract: dose dependence

NASA Astrophysics Data System (ADS)

Soderberg, Per G.; Loefgren, Stefan

1994-07-01

Current safety limits for cataract development after acute exposure to ultraviolet radiation (UVR) are based on experiments analyzing experimental data with a quantal, effect-no effect, dose-response model. The present study showed that intensity of forward light scattering is better described with a continuous dose-response model. It was found that 3, 30 and 300 kJ/m2UVR300nm induces increased light scattering within 6 h. For all three doses the intensity of forward light scattering was constant after 6 h. The intensity of forward light scattering was proportional to the log dose of UVR300nm. There was a slight increase of the intensity of forward light scattering on the contralateral side in animals that received 300 kJ/m2. Altogether 72 Sprague-Dawley male rats were included. Half of the rats were exposed in vivo on one side to UVR300nm. The other half was kept as a control group, receiving the same treatment as exposed rats but without delivery of UVR300nm to the eye. Subgroups of the rats received either of the three doses. Rats were sacrificed at varying intervals after the exposure. The lenses were extracted and the forward light scattering was estimated. It is concluded that intensity of forward light scattering in the lens after exposure to UVR300nm should be described with a continuous dose-reponse model.

OSL studies of alkali fluoroperovskite single crystals for radiation dosimetry

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Raja, A.; Madhusoodanan, U.; Annalakshmi, O.; Ramasamy, P.

2016-08-01

This paper presents a preliminary investigation of the optically stimulated luminescence (OSL) of alkali fluoroperovskite single crystals for radiation dosimetry. The perovskite-like KMgF3, NaMgF3 and LiBaF3 polycrystalline compounds doped with rare earths (Eu2+ and Ce3+) were synthesized by standard solid state reaction technique. Phase purity of the synthesized compounds was analyzed by powder X-ray diffraction technique. Single crystals of these compounds have been grown from melt by using vertical Bridgman-Stockbarger method. The Linearly Modulated OSL and Continuous Wave OSL measurements were performed in these alkali fluorides using blue light stimulation. Thermal bleaching experiments have shown that OSL signals originate from traps which are unstable near 200 °C, thus proving the suitability of the signals for dosimetric purposes. Optical bleaching measurements were also performed for these fluoride samples. OSL dose response was studied as a function of dose which was found to increase with beta dose.

A measurement of the radiation dose to LDEF by passive dosimetry

NASA Technical Reports Server (NTRS)

Blake, J. B.; Imamoto, S. S.

1993-01-01

The results from a pair of thermoluminescent dosimeter experiments flown aboard the Long Duration Exposure Facility (LDEF) show an integrated dose several times smaller than that predicted by the NASA environmental models for shielding thicknesses much greater than 0.10 gm/sq cm aluminum. For thicknesses between 0.01 and 0.1 gm/sq cm, the measured dose was in agreement with predictions. The Space and Environment Technology Center of The Aerospace Corporation fielded two related experiments on LDEF to measure the energetic radiation dose by means of passive dosimetry. The sensors were LiF thermoluminescent dosimeters mounted behind various thicknesses of shielding. The details of the experiment are described first, followed by the results of the observations. A comparison is made with the predictions based upon the NASA environmental models and the actual mission profile flown by LDEF; conclusions follow.

Systematic identification of DNA variants associated with ultraviolet radiation using a novel Geographic-Wide Association Study (GeoWAS).

PubMed

Hsu, Irving; Chen, Rong; Ramesh, Aditya; Corona, Erik; Kang, Hyunseok Peter; Ruau, David; Butte, Atul J

2013-06-20

Long-term environmental variables are widely understood to play important roles in DNA variation. Previously, clinical studies examining the impacts of these variables on the human genome were localized to a single country, and used preselected DNA variants. Furthermore, clinical studies or surveys are either not available or difficult to carry out for developing countries. A systematic approach utilizing bioinformatics to identify associations among environmental variables, genetic variation, and diseases across various geographical locations is needed but has been lacking. Using a novel Geographic-Wide Association Study (GeoWAS) methodology, we identified Single Nucleotide Polymorphisms (SNPs) in the Human Genome Diversity Project (HGDP) with population allele frequencies associated geographical ultraviolet radiation exposure, and then assessed the diseases known to be assigned with these SNPs. 2,857 radiation SNPs were identified from over 650,000 SNPs in 52 indigenous populations across the world. Using a quantitative disease-SNP database curated from 5,065 human genetic papers, we identified disease associations with those radiation SNPs. The correlation of the rs16891982 SNP in the SLC45A2 gene with melanoma was used as a case study for analysis of disease risk, and the results were consistent with the incidence and mortality rates of melanoma in published scientific literature. Finally, by analyzing the ontology of genes in which the radiation SNPs were significantly enriched, potential associations between SNPs and neurological disorders such as Alzheimer's disease were hypothesized. A systematic approach using GeoWAS has enabled us to identify DNA variation associated with ultraviolet radiation and their connections to diseases such as skin cancers. Our analyses have led to a better understating at the genetic level of why certain diseases are more predominant in specific geographical locations, due to the interactions between environmental variables such

Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa.

PubMed

Rice, Philip S

2011-04-23

Of the eight human herpes viruses, varicella-zoster virus, which causes chickenpox and zoster, has a unique epidemiology. Primary infection is much less common in children in the tropics compared with temperate areas. This results in increased adult susceptibility causing outbreaks, for example in health-care workers migrating from tropical to temperate countries. The recent demonstration that there are different genotypes of varicella-zoster virus and their geographic segregation into tropical and temperate areas suggests a distinct, yet previously unconsidered climatic factor may be responsible for both the clinical and molecular epidemiological features of this virus infection. Unlike other human herpes viruses, varicella-zoster virus does not require intimate contact for infection to occur indicating that transmission may be interrupted by a geographically restricted climatic factor. The factor with the largest difference between tropical and temperate zones is ultra-violet radiation. This could reduce the infectiousness of chickenpox cases by inactivating virus in vesicles, before or after rupture. This would explain decreased transmissibility in the tropics and why the peak chickenpox incidence in temperate zones occurs during winter and spring, when ultra-violet radiation is at its lowest. The evolution of geographically restricted genotypes is also explained by ultra-violet radiation driving natural selection of different virus genotypes with varying degrees of resistance to inactivation, tropical genotypes being the most resistant. Consequently, temperate viruses should be more sensitive to its effects. This is supported by the observation that temperate genotypes are found in the tropics only in specific circumstances, namely where ultra-violet radiation has either been excluded or significantly reduced in intensity. The hypothesis is testable by exposing different virus genotypes to ultra-violet radiation and quantifying virus survival by plaque forming

Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa

PubMed Central

2011-01-01

Background Of the eight human herpes viruses, varicella-zoster virus, which causes chickenpox and zoster, has a unique epidemiology. Primary infection is much less common in children in the tropics compared with temperate areas. This results in increased adult susceptibility causing outbreaks, for example in health-care workers migrating from tropical to temperate countries. The recent demonstration that there are different genotypes of varicella-zoster virus and their geographic segregation into tropical and temperate areas suggests a distinct, yet previously unconsidered climatic factor may be responsible for both the clinical and molecular epidemiological features of this virus infection. Presentation of the hypothesis Unlike other human herpes viruses, varicella-zoster virus does not require intimate contact for infection to occur indicating that transmission may be interrupted by a geographically restricted climatic factor. The factor with the largest difference between tropical and temperate zones is ultra-violet radiation. This could reduce the infectiousness of chickenpox cases by inactivating virus in vesicles, before or after rupture. This would explain decreased transmissibility in the tropics and why the peak chickenpox incidence in temperate zones occurs during winter and spring, when ultra-violet radiation is at its lowest. The evolution of geographically restricted genotypes is also explained by ultra-violet radiation driving natural selection of different virus genotypes with varying degrees of resistance to inactivation, tropical genotypes being the most resistant. Consequently, temperate viruses should be more sensitive to its effects. This is supported by the observation that temperate genotypes are found in the tropics only in specific circumstances, namely where ultra-violet radiation has either been excluded or significantly reduced in intensity. Testing the Hypothesis The hypothesis is testable by exposing different virus genotypes to ultra-violet

Development of space stable thermal control coatings for use on large space vehicles. [effects of ultraviolet radiation

NASA Technical Reports Server (NTRS)

Gilligan, J. E.; Harada, Y.

1974-01-01

The development of a large scale manufacturing method for the production of a stable zinc orthotitanate pigment is discussed. Major emphasis was placed on the evaluation of ultraviolet radiation stability tests of pigments derived from coprecipitated and individually precipitated oxalates. Emphasis was also placed on an investigation of the conditions (time and temperature) leading to high reflectance and high optical stability. Paints were formulated in OI-650 and in OI-650G vehicles from pigments which were prepared at various temperatures. Analyses of ultraviolet irradiation test data were conducted regarding optimum pigment preparation parameters and treatment conditions.

Equilibrium properties of blackbody radiation with an ultraviolet energy cut-off

NASA Astrophysics Data System (ADS)

Mishra, Dheeraj Kumar; Chandra, Nitin; Vaibhav, Vinay

2017-10-01

We study various equilibrium thermodynamic properties of blackbody radiation (i.e. a photon gas) with an ultraviolet energy cut-off. We find that the energy density, specific heat etc. follow usual acoustic phonon dynamics as have been well studied by Debye. Other thermodynamic quantities like pressure, entropy etc. have also been calculated. The usual Stefan-Boltzmann law gets modified. We observe that the values of the thermodynamic quantities with the energy cut-off is lower than the corresponding values in the theory without any such scale. The phase-space measure is also expected to get modified for an exotic spacetime appearing at Planck scale, which in turn leads to the modification of Planck energy density distribution and the Wien's displacement law. We found that the non-perturbative nature of the thermodynamic quantities in the SR limit (for both unmodified and modified cases), due to nonanalyticity of the leading term, is a general feature of the theory accompanied with an ultraviolet energy cut-off. We have also discussed the possible modification in the case of Big Bang and the Stellar objects and have suggested a table top experiment for verification in effective low energy case.

Experimental active and passive dosimetry systems for the NASA Skylab program

NASA Technical Reports Server (NTRS)

Schneider, M. F.; Janni, J. F.; Ainsworth, G. C.

1972-01-01

Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis.

Ultraviolet damage to the eye revisited: eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear

PubMed Central

Behar-Cohen, Francine; Baillet, Gilles; de Ayguavives, Tito; Garcia, Paula Ortega; Krutmann, Jean; Peña-García, Pablo; Reme, Charlotte; Wolffsohn, James S

2014-01-01

Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children’s eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°–150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to

Ultraviolet damage to the eye revisited: eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear.

PubMed

Behar-Cohen, Francine; Baillet, Gilles; de Ayguavives, Tito; Garcia, Paula Ortega; Krutmann, Jean; Peña-García, Pablo; Reme, Charlotte; Wolffsohn, James S

2014-01-01

Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children's eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°-150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to lay

Physical and biological characterization of a seawater ultraviolet radiation sterilizer

NASA Astrophysics Data System (ADS)

Torrentera, Laura; Uribe, Roberto M.; Rodríguez, Romana R.; Carrillo, Ricardo E.

1994-03-01

The physical and biological characterization of a seawater ultraviolet (UV) sterilizer is described. The physical characterization was performed using radiochromic dye films by evaluating the uniformity of the radiant exposure along each lamp, the effect of the radiation from one lamp on the array of adjacent lamps, and by measuring the UV radiation absorption of seawater with respect to distilled water. The biological characterization was performed by measuring the amount of reduction of bacteria in stored seawater after different filtration and UV treatments. Among the filtration methods tested, differential filtration (5, 3 and 0.45 μm filters connected in series) caused the highest bacterial reduction factor of 60%. UV radiant exposures of 212, 424, 636 and 848 J m -2 yielded bacteria reduction factors of 99.86, 99.969, 99.997 and 100%, respectively, for populations of Vibrio and Pseudomonas bacteria present in stored seawater. It is concluded that the system is useful for water disinfection when 1, 2 or 3 lamps are on; when 4 lamps are used the treated water becomes sterile.

Molecular Mechanisms of Ultraviolet Radiation-Induced DNA Damage and Repair

PubMed Central

Rastogi, Rajesh P.; Richa; Kumar, Ashok; Tyagi, Madhu B.; Sinha, Rajeshwar P.

2010-01-01

DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR) (mainly UV-B: 280–315 nm) is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Additionally, double-strand break repair (by homologous recombination and nonhomologous end joining), SOS response, cell-cycle checkpoints, and programmed cell death (apoptosis) are also operative in various organisms with the expense of specific gene products. This review deals with UV-induced alterations in DNA and its maintenance by various repair mechanisms. PMID:21209706

Effect of DNA-injuring agents on B. stearothermophilus. Report 1. High resistance of B. stearothermophilus to N-nitroso-N-methylurea, ultraviolet and gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gainullina, S.M.; Gumanova, A.V.; Vinogradova, N.A.

1978-01-01

The effects of DNA-attacking agents on thermophilic microorganisms were investigated. Bacillus stearothermophilus were treated with N-nitroso-N-methylurea, ultraviolet radiation or gamma radiation. Survival curves were plotted.

Optical effects of exposing intact human lenses to ultraviolet radiation and visible light.

PubMed

Kessel, Line; Eskildsen, Lars; Lundeman, Jesper Holm; Jensen, Ole Bjarlin; Larsen, Michael

2011-12-30

The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short wavelength region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm) lasers. The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures. Irradiation with high intensity lasers caused scattering lesions in the human lenses. These effects were more likely to be seen when using pulsed lasers because of the high pulse intensity. Prolonged irradiation with UVA led to photodarkening whereas no detrimental effects were observed after irradiation with visible light. Irradiation with visible light does not seem to be harmful to the human lens except if the lens is exposed to laser irradiances that are high enough to warrant thermal protein denaturation that is more readily seen using pulsed laser systems.

TU-G-213-03: IEC Subcommittee 62C (Equipment for Radiotherapy, Nuclear Medicine and Radiation Dosimetry): Recent and Active Projects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culberson, W.

The International Electrotechnical Commission (IEC) writes standards that manufacturers of electrical equipment must comply with. Medical electrical equipment, such as medical imaging, radiation therapy, and radiation dosimetry devices, fall under Technical Committee 62. Of particular interest to medical physicists are the standards developed within Subcommittees (SC) 62B, which addresses diagnostic radiological imaging equipment, and 62C, which addresses equipment for radiation therapy, nuclear medicine and dosimetry. For example, a Working Group of SC 62B is responsible for safety and quality assurance standards for CT scanners and a Working Group of SC 62C is responsible for standards that set requirements for dosimetricmore » safety and accuracy of linacs and proton accelerators. IEC standards thus have an impact on every aspect of a medical physicist’s job, including equipment testing, shielding design, room layout, and workflow. Consequently, it is imperative that US medical physicists know about existing standards, as well as have input on those under development or undergoing revision. The structure of the IEC and current standards development work will be described in detail. The presentation will explain how US medical physicists can learn about IEC standards and contribute to their development. Learning Objectives: Learn about the structure of the IEC and the influence that IEC standards have on the design of equipment for radiology and radiation therapy. Learn about the mechanisms by which the US participates in the development and revision of standards. Understand the specific requirements of several standards having direct relevance to diagnostic and radiation therapy physicists.« less

European Code against Cancer 4th Edition: Ultraviolet radiation and cancer.

PubMed

Greinert, Rüdiger; de Vries, Esther; Erdmann, Friederike; Espina, Carolina; Auvinen, Anssi; Kesminiene, Ausrele; Schüz, Joachim

2015-12-01

Ultraviolet radiation (UVR) is part of the electromagnetic spectrum emitted naturally from the sun or from artificial sources such as tanning devices. Acute skin reactions induced by UVR exposure are erythema (skin reddening), or sunburn, and the acquisition of a suntan triggered by UVR-induced DNA damage. UVR exposure is the main cause of skin cancer, including cutaneous malignant melanoma, basal-cell carcinoma, and squamous-cell carcinoma. Skin cancer is the most common cancer in fair-skinned populations, and its incidence has increased steeply over recent decades. According to estimates for 2012, about 100,000 new cases of cutaneous melanoma and about 22,000 deaths from it occurred in Europe. The main mechanisms by which UVR causes cancer are well understood. Exposure during childhood appears to be particularly harmful. Exposure to UVR is a risk factor modifiable by individuals' behaviour. Excessive exposure from natural sources can be avoided by seeking shade when the sun is strongest, by wearing appropriate clothing, and by appropriately applying sunscreens if direct sunlight is unavoidable. Exposure from artificial sources can be completely avoided by not using sunbeds. Beneficial effects of sun or UVR exposure, such as for vitamin D production, can be fully achieved while still avoiding too much sun exposure and the use of sunbeds. Taking all the scientific evidence together, the recommendation of the 4th edition of the European Code Against Cancer for ultraviolet radiation is: "Avoid too much sun, especially for children. Use sun protection. Do not use sunbeds." Copyright © 2015 International Agency for Research on Cancer. Published by Elsevier Ltd. All rights reserved.

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system.

PubMed

Tachi, Fuyuki; Osakabe, Masahiro

2012-12-01

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites (Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite (Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species (T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system

NASA Astrophysics Data System (ADS)

Tachi, Fuyuki; Osakabe, Masahiro

2012-12-01

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites ( Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite ( Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species ( T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Photodegradation of the antimicrobial triclocarban in aqueous systems under ultraviolet radiation.

PubMed

Ding, Shi-Ling; Wang, Xi-Kui; Jiang, Wen-Qiang; Meng, Xia; Zhao, Ru-Song; Wang, Chen; Wang, Xia

2013-05-01

This work aimed to investigate the effectiveness of ultraviolet (UV) radiation on the degradation of the antimicrobial triclocarban (TCC). We investigated the effects of several operational parameters, including solution pH, initial TCC concentration, photocatalyst TiO₂ loading, presence of natural organic matter, and most common anions in surface waters (e.g., bicarbonate, nitrate, and sulfate). The results showed that UV radiation was very effective for TCC photodegradation and that the photolysis followed pseudo-first-order kinetics. The TCC photolysis rate was pH dependent and favored at high pH. A higher TCC photolysis rate was observed by direct photolysis than TiO₂ photocatalysis. The presence of the inorganic ions bicarbonate, nitrate, and sulfate hindered TCC photolysis. Negative effects on TCC photolysis were also observed by the addition of humic acid due to competitive UV absorbance. The main degradation products of TCC were tentatively identified by gas chromatograph with mass spectrometer, and a possible degradation pathway of TCC was also proposed.

Ionization chamber-based reference dosimetry of intensity modulated radiation beams.

PubMed

Bouchard, Hugo; Seuntjens, Jan

2004-09-01

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the absorbed dose to water calibration coefficient N(D, w)Q for fluence perturbation effects in individual segments of an IMRT delivery and developed a calculation method to evaluate the factor. The method consists of precalculating, using accurate Monte Carlo techniques, ionization chamber, type-dependent cavity air dose, and in-phantom dose to water at the reference point for zero-width pencil beams as a function of position of the pencil beams impinging on the phantom surface. These precalculated kernels are convolved with the IMRT fluence distribution to arrive at the dose-to-water-dose-to-cavity air ratio [D(a)w (IMRT)] for IMRT fields and with a 10x10 cm2 open-field fluence to arrive at the same ratio D(a)w (Q) for the 10x10 cm2 reference field. The correction factor C(Q)IMRT is then calculated as the ratio of D(a)w (IMRT) and D(a)w (Q). The calculation method was experimentally validated and the magnitude of chamber correction factors in reference dose measurements in single static and dynamic IMRT fields was studied. The results show that, for thimble-type ionization chambers the correction factor in a single, realistic dynamic IMRT field can be of the order of 10% or more. We therefore propose that for accurate reference dosimetry of complete n-beam IMRT deliveries, ionization chamber fluence perturbation correction factors must explicitly be taken into account.

L Band EPR Tooth Dosimetry for Heavy Ion Irradiation

PubMed Central

Yamaguchi, Ichiro; Sato, Hitoshi; Kawamura, Hiraku; Hamano, Tsuyoshi; Yoshii, Hiroshi; Suda, Mitsuru; Miyake, Minoru; Kunugita, Naoki

2016-01-01

Electron Paramagnetic Resonance (EPR) tooth dosimetry is being developed as a device to rapidly assess large populations that were potentially exposed to radiation during a major radiation accident or terrorist event. While most exposures are likely to be due to fallout and therefore involve low linear energy transfer (LET) radiation, there is also a potential for exposures to high LET radiation, for which the effect on teeth has been less well characterized by EPR. Therefore, the aim of this paper is to acquire fundamental response curves for high LET radiation in tooth dosimetry using L band EPR. For this purpose, we exposed human teeth to high energy carbon ions using the heavy ion medical accelerator in Chiba at the National Institute of Radiological Sciences. The primary findings were that EPR signals for carbon ion irradiation were about one-tenth the amplitude of the response to the same dose of 150 kVp X-rays. PMID:27542817

Assessing children's ultraviolet radiation exposure: the potential usefulness of a colorimeter.

PubMed Central

Eckhardt, L; Mayer, J A; Creech, L; Johnston, M R; Lui, K J; Sallis, J F; Elder, J P

1996-01-01

OBJECTIVES: This study evaluated the colorimeter as an objective measure of children's ultraviolet (UV) radiation exposure. METHODS: Fifty-eight children, ages 6 to 9 years, attended two summer measurement sessions, with 46 attending a subsequent winter session. RESULTS: Comparisons between summer sessions for the L* scale showed that only the upper arm significantly changed in the tanner direction, while b* scale values indicated significant tanning for all body sites. All exposed body sites changed significantly in the less tan direction between summer and winter measurements. CONCLUSIONS: Using colorimeters to objectively measure children's UV exposure has potential applications for skin cancer prevention programs. PMID:9003142

Relationship between student selection criteria and learner success for medical dosimetry students.

PubMed

Baker, Jamie; Tucker, Debra; Raynes, Edilberto; Aitken, Florence; Allen, Pamela

2016-01-01

Medical dosimetry education occupies a specialized branch of allied health higher education. Noted international shortages of health care workers, reduced university funding, limitations on faculty staffing, trends in learner attrition, and increased enrollment of nontraditional students force medical dosimetry educational leadership to reevaluate current admission practices. Program officials wish to select medical dosimetry students with the best chances of successful graduation. The purpose of the quantitative ex post facto correlation study was to investigate the relationship between applicant characteristics (cumulative undergraduate grade point average (GPA), science grade point average (SGPA), prior experience as a radiation therapist, and previous academic degrees) and the successful completion of a medical dosimetry program, as measured by graduation. A key finding from the quantitative study was the statistically significant positive correlation between a student׳s previous degree and his or her successful graduation from the medical dosimetry program. Future research investigations could include a larger research sample, representative of more medical dosimetry student populations, and additional studies concerning the relationship of previous work as a radiation therapist and the effect on success as a medical dosimetry student. Based on the quantitative correlation analysis, medical dosimetry leadership on admissions committees could revise student selection rubrics to place less emphasis on an applicant׳s undergraduate cumulative GPA and increase the weight assigned to previous degrees. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Implementation of Ultraviolet Radiation Safety Measures for Outdoor Workers.

PubMed

Maguire, Erin; Spurr, Alison

Ultraviolet radiation (UVR) poses a major risk for outdoor workers, putting them at greater risk for skin cancer. In the general population, the incidence of both melanoma and nonmelanoma skin cancers is increasing. It is estimated that 90% of skin cancers in Canada are directly attributable to UVR exposure, making this cancer largely preventable with the appropriate precautions. A scoping review was conducted on the barriers and facilitators to UVR safety in outdoor workers to elucidate why these precautions are not in use currently. We discuss these results according to the Hierarchy of Controls as a means to outline effective and feasible prevention strategies for outdoor workers. In doing so, this review may be used to inform the design of future workplace interventions for UVR safety in outdoor workers to decrease the risk of skin cancer in this vulnerable population.

Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.).

PubMed

Dogu-Baykut, Esra; Gunes, Gurbuz; Decker, Eric Andrew

2014-08-15

Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64 min. UV-C treatment led to 1.04 and 1.38 log CFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a(∗) value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3 μmol GAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14 days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterization of a parallel beam CCD optical-CT apparatus for 3D radiation dosimetry

NASA Astrophysics Data System (ADS)

Krstajić, Nikola; Doran, Simon J.

2006-12-01

This paper describes the initial steps we have taken in establishing CCD based optical-CT as a viable alternative for 3-D radiation dosimetry. First, we compare the optical density (OD) measurements from a high quality test target and variable neutral density filter (VNDF). A modulation transfer function (MTF) of individual projections is derived for three positions of the sinusoidal test target within the scanning tank. Our CCD is then characterized in terms of its signal-to-noise ratio (SNR). Finally, a sample reconstruction of a scan of a PRESAGETM (registered trademark of Heuris Pharma, NJ, Skillman, USA.) dosimeter is given, demonstrating the capabilities of the apparatus.

Characterisation of spectrophotometers used for spectral solar ultraviolet radiation measurements.

PubMed

Gröbner, J

2001-01-01

Spectrophotometers used for spectral measurements of the solar ultraviolet radiation need to be well characterised to provide accurate and reliable data. Since the characterisation and calibration are usually performed in the laboratory under conditions very different from those encountered during solar measurements, it is essential to address all issues concerned with the representativity of the laboratory characterisation with respect to the solar measurements. These include among others the instrument stability, the instrument linearity, the instrument responsivity, the wavelength accuracy, the spectral resolution, stray light rejection and the instrument dependence on ambient temperature fluctuations. These instrument parameters need to be determined often enough so that the instrument changes only marginally in the period between successive characterisations and therefore provides reliable data for the intervening period.

Radiotherapy dosimetry using a commercial OSL system.

PubMed

Viamonte, A; da Rosa, L A R; Buckley, L A; Cherpak, A; Cygler, J E

2008-04-01

A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al2O3:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for 60Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al2O3:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.

ASSESSMENT OF THE RISK OF SOLAR ULTRAVIOLET RADIATION TO AMPHIBIANS: III. PREDICTION OF IMPACTS IN SELECTED NORTHERN MIDWESTERN WETLANDS

EPA Science Inventory

The deleterious effects of solar ultraviolet radiation, especially the UV-B portion of sunlight, have been hypothesized to reduce survival, increase the frequency of malformations, and contribute to the apparent worldwide decline of many amphibian species.

Inactivation of Staphylococcus saprophyticus in chicken meat and exudate using high pressure processing, gamma radiation, and ultraviolet light

USDA-ARS?s Scientific Manuscript database

Stapylococcus saprophyticus is a common contaminant in foods and causes urinary tract infections in humans. Three nonthermal food safety intervention technologies used to improve the safety foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). A...

Safety: Radiation Protection Manual

DTIC Science & Technology

1997-05-30

t e c h n i c a l publication requires it, (2) personnel are required to wear dosimetry , EM 385-1-80 30 May 97 2-4 (3) personnel are required to...of SOPs, review of dosimetry results, changes in standards or guidance, equipment changes, and any other pertinent radiation safety information that...Table 3-4. The EDE is used in dosimetry to account for different organs having different sensitivities to radiation. Table 3-4 Weighting Factors

TH-CD-BRA-11: Implementation and Evaluation of a New 3D Dosimetry Protocol for Validating MRI Guided Radiation Therapy Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mein, S; Rankine, L; Department of Radiation Oncology, Washington University School of Medicine

Purpose: To develop, evaluate and apply a novel high-resolution 3D remote dosimetry protocol for validation of MRI guided radiation therapy treatments (MRIdian by ViewRay™). We demonstrate the first application of the protocol (including two small but required new correction terms) utilizing radiochromic 3D plastic PRESAGE™ with optical-CT readout. Methods: A detailed study of PRESAGE™ dosimeters (2kg) was conducted to investigate the temporal and spatial stability of radiation induced optical density change (ΔOD) over 8 days. Temporal stability was investigated on 3 dosimeters irradiated with four equally-spaced square 6MV fields delivering doses between 10cGy and 300cGy. Doses were imaged (read-out) bymore » optical-CT at multiple intervals. Spatial stability of ΔOD response was investigated on 3 other dosimeters irradiated uniformly with 15MV extended-SSD fields with doses of 15cGy, 30cGy and 60cGy. Temporal and spatial (radial) changes were investigated using CERR and MATLAB’s Curve Fitting Tool-box. A protocol was developed to extrapolate measured ΔOD readings at t=48hr (the typical shipment time in remote dosimetry) to time t=1hr. Results: All dosimeters were observed to gradually darken with time (<5% per day). Consistent intra-batch sensitivity (0.0930±0.002 ΔOD/cm/Gy) and linearity (R2=0.9996) was observed at t=1hr. A small radial effect (<3%) was observed, attributed to curing thermodynamics during manufacture. The refined remote dosimetry protocol (including polynomial correction terms for temporal and spatial effects, CT and CR) was then applied to independent dosimeters irradiated with MR-IGRT treatments. Excellent line profile agreement and 3D-gamma results for 3%/3mm, 10% threshold were observed, with an average passing rate 96.5%± 3.43%. Conclusion: A novel 3D remote dosimetry protocol is presented capable of validation of advanced radiation treatments (including MR-IGRT). The protocol uses 2kg radiochromic plastic dosimeters read

The effect of ultraviolet radiation on the cornea - experimental study.

PubMed

Golu, Andreea; Gheorghişor, Irina; Bălăşoiu, A T; Baltă, Fl; Osiac, E; Mogoantă, L; Bold, Adriana

2013-01-01

Ultraviolet (UV) radiation in high doses may have harmful effects on the eye. The sources of UV radiation are the sun, as well as some artificial sources such as UV lamps or voltaic arcs. Chronic exposure to UV can cause damage to the anterior pole of the eye, ranging from minor (pterygium) to serious photokeratitis. In our study, we applied a UV dose of 6.5 J/cm(2) in the wavelength range of 290-400 nm, for five consecutive days per rat anterior pole of the eye. Seven days after the last dose of radiation, the animals were sacrificed, harvesting both the irradiated and the non-irradiated eye. Histological and immunohistochemical examination of the lesions revealed that the greatest damage to the epithelium was recorded prior to and 2/3 of the remaining corneal stroma. The epithelial lesions we found varied from pseudokeratosis and detachment of the Bowman epithelium membrane to deep epithelial necrosis. Within the corneal stroma, we observed the formation of interstitial edema with disruption of the collagen structure. We also noticed the presence of an inflammatory infiltrate composed mainly of lymphocytes and CD68+ and CD163+ macrophages, as well as the occurrence of vascular devices. These consisted of angiogenesis capillaries with structured wall composed mainly of endothelial CD34+ precursor cells and a basal membrane rich in collagen IV fibers.

21 CFR 878.4635 - Ultraviolet lamp for tanning.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet lamp for tanning. 878.4635 Section 878... tanning. (a) Identification. An ultraviolet lamp for tanning is a device that is a lamp (including a fixture) intended to provide ultraviolet radiation to tan the skin. See § 1040.20 of this chapter. (b...

SU-E-T-62: A Preliminary Experience of Using EPID Transit Dosimetry for Monitoring Daily Dose Variations in Radiation Treatment Delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, R; Chisela, W

2015-06-15

Purpose: To investigate the use of EPID transit dosimetry for monitoring daily dose variations in radiation treatment delivery. Methods: A patient with head and neck cancer treated using nine field IMRT beams was used in this study. The prescription was 45 Gy in 25 fractions. A KV CBCT was acquired before each treatment on a Varian NTX linear accelerator. Integrated images using MV EPID were acquired for each treatment beam. Planning CT images, treatment plan, and daily integrated images were imported into a commercial QA software Dosimetry Check (v4r4 Math Resolutions, LLC, Columbia, MD) to calculate 3D dose of themore » day assuming 25 fractions treatment. Planning CT images were deformed and registered to each daily CBCT using Varian SmartAdapt (v11.MR2). ROIs were then propagated from planning CT to daily CBCT. The correlation between maximum, average dose of ROIs and ROI volume, center of mass shift, Dice Similarity Coefficient (DSC) were investigated. Results: Not all parameters investigated showed strong correlations. For PTV and CTV, the average dose has inverse correlation with their volume change (correlation coefficient −0.52, −0.50, respectively) and DSC (−0.59, −0.59, respectively). The average dose of right parotid has correlation with its volume change (0.56). The maximum dose of spinal cord has correlation with the center of mass superior-inferior shift (0.52) and inverse correlation with the center of mass anterior-posterior shift (−0.73). Conclusion: Transit dosimetry using EPID images collected during treatment delivery offers great potential to monitor daily dose variations due to patient anatomy change, motion, and setup errors in radiation treatment delivery. It can provide a patient-specific QA tool valuable for adaptive radiation therapy. Further work is needed to validate the technique.« less

Vacuum Ultraviolet Radiation Desorption of Molecular Contaminants Deposited on Quartz Crystal Microbalances

NASA Technical Reports Server (NTRS)

Albyn, Keith; Burns, Dewitt

2006-01-01

Recent quartz crystal microbalance measurements made in the Marshall Space Flight Center, Photo-Deposition Facility, for several materials, recorded a significant loss of deposited contaminants when the deposition surface of the microbalance was illuminated by a deuterium lamp. These measurements differ from observations made by other investigators in which the rate of deposition increased significantly when the deposition surface was illuminated with vacuum ultraviolet radiation. These observations suggest that the accelerated deposition of molecular contaminants on optically sensitive surfaces is dependant upon the contaminant being deposited and must be addressed during the materials selection process by common material screening techniques.

Nanotherapy of cancer by photoelectrons emitted from the surface of nanoparticles exposed to nonionizing ultraviolet radiation.

PubMed

Letfullin, Renat R; George, Thomas F

2017-05-01

We introduce a new method for selectively destroying cancer cell organelles by electrons emitted from the surface of intracellularly localized nanoparticles exposed to the nonionizing ultraviolet (UV) radiation. We propose to target cancerous intracellular organelles by nanoparticles and expose them to UV radiation with energy density safe for healthy tissue. We simulate the number of photoelectrons produced by the nanoparticles made of various metals and radii, calculate their kinetic energy and compare it to the threshold energy for producing biological damage. Exposure of metal nanoparticles to UV radiation generates photoelectrons with kinetic energies up to 11 eV, which is high enough to produce single- to double-strand breaks in the DNA and damage the cancerous cell organelles.

Thermoluminescence dosimetry and its applications in medicine--Part 2: History and applications.

PubMed

Kron, T

1995-03-01

Thermoluminescence dosimetry (TLD) has been available for dosimetry of ionising radiation for nearly 100 years. The variety of materials and their different physical forms allow the determination of different radiation qualities over a wide range of absorbed dose. This makes TL dosimeters useful in radiation protection where dose levels of microGy are monitored as well as in radiotherapy where doses up to several Gray are to be measured. The major advantages of TL detectors are their small physical size and that no cables or auxiliary equipment is required during the dose assessment. Therefore TLD is a good method for point dose measurements in phantoms as well as for in vivo dosimetry on patients during radiotherapy treatment. As an integrative dosimetric technique, it can be applied to personal dosimetry and it lends itself to the determination of dose distributions due to multiple or moving radiation sources (e.g. conformal and dynamic radiotherapy, computed tomography). In addition, TL dosimeters are easy to transport, and they can be mailed. This makes them well suited for intercomparison of doses delivered in different institutions. The present article aims at describing the various applications TLD has found in medicine by taking into consideration the physics and practice of TLD measurements which have been discussed in the first part of this review (Australas. Phys. Eng. Sci. Med. 17: 175-199, 1994).

On neutron-gamma mixed field dosimetry with LiF:Mg,Ti at radiation protection dose levels.

PubMed

Weinstein, M; German, U; Alfassi, Z B

2006-01-01

The possibility of using the specific responses of the high temperature Peaks 6 and 7 and Peaks 4 and 5 to different LET radiations was mentioned in the past mainly for very high doses. The applicability of the two regions method for thermal neutrons--gamma ray mixed field dosimetry was investigated by analysing the response of LiF:Mg,Ti dosemeters irradiated to different ratios of thermal neutrons and gamma rays at radiation protection dose levels encountered in routine work conditions, up to approximately 50 mSv. The Region of Interest method was used to define the areas of the Peaks 4 + 5 and 6 + 7. We found that a simple algorithm can be used to determine with good accuracy the separate contributions of neutron and gamma doses.

Germanium-doped optical fiber for real-time radiation dosimetry

NASA Astrophysics Data System (ADS)

Mizanur Rahman, A. K. M.; Zubair, H. T.; Begum, Mahfuza; Abdul-Rashid, H. A.; Yusoff, Z.; Ung, N. M.; Mat-Sharif, K. A.; Wan Abdullah, W. S.; Amouzad Mahdiraji, Ghafour; Amin, Y. M.; Maah, M. J.; Bradley, D. A.

2015-11-01

Over the past three decades growing demand for individualized in vivo dosimetry and subsequent dose verification has led to the pursuit of newer, novel and economically feasible materials for dosimeters. These materials are to facilitate features such as real-time sensing and fast readouts. In this paper, purposely composed SiO2:Ge optical fiber is presented as a suitable candidate for dosimetry. The optical fiber is meant to take advantage of the RL/OSL technique, providing both online remote monitoring of dose rate, and fast readouts for absorbed dose. A laboratory-assembled OSL reader has been used to acquire the RL/OSL response to LINAC irradiations (6 MV photons). The notable RL characteristics observed include constant level of luminescence for the same dose rate (providing better consistency compared to TLD-500), and linearity of response in the radiotherapy range (1 Gy/min to 6 Gy/min). The OSL curve was found to conform to an exponential decay characteristic (illumination with low LED source). The Ge doping resulted in an effective atomic number, Zeff, of 13.5 (within the bone equivalent range). The SiO2:Ge optical fiber sensor, with efficient coupling, can be a viable solution for in vivo dosimetry, besides a broad range of applications.

Potential of herbs in skin protection from ultraviolet radiation

PubMed Central

Korać, Radava R.; Khambholja, Kapil M.

2011-01-01

Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV) radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxidants such as vitamins (vitamin C, vitamin E), flavonoids, and phenolic acids play the main role in fighting against free radical species that are the main cause of numerous negative skin changes. Although isolated plant compounds have a high potential in protection of the skin, whole herbs extracts showed better potential due to their complex composition. Many studies showed that green and black tea (polyphenols) ameliorate adverse skin reactions following UV exposure. The gel from aloe is believed to stimulate skin and assist in new cell growth. Spectrophotometer testing indicates that as a concentrated extract of Krameria triandra it absorbs 25 to 30% of the amount of UV radiation typically absorbed by octyl methoxycinnamate. Sesame oil resists 30% of UV rays, while coconut, peanut, olive, and cottonseed oils block out about 20%. A “sclerojuglonic” compound which is forming from naphthoquinone and keratin is the reaction product that provides UV protection. Traditional use of plant in medication or beautification is the basis for researches and making new trends in cosmetics. This review covers all essential aspects of potential of herbs as radioprotective agents and its future prospects. PMID:22279374

Molecular response of nasal mucosa to therapeutic exposure to broad-band ultraviolet radiation

PubMed Central

Mitchell, David; Paniker, Lakshmi; Sanchez, Guillermo; Bella, Zsolt; Garaczi, Edina; Szell, Marta; Hamid, Qutayba; Kemeny, Lajos; Koreck, Andrea

2010-01-01

Abstract Ultraviolet radiation (UVR) phototherapy is a promising new treatment for inflammatory airway diseases. However, the potential carcinogenic risks associated with this treatment are not well understood. UV-specific DNA photoproducts were used as biomarkers to address this issue. Radioimmunoassay was used to quantify cyclobutane pyrimidine dimers (CPDs) and (6–4) photoproducts in DNA purified from two milieus: nasal mucosa samples from subjects exposed to intranasal phototherapy and human airway (EpiAirway™) and human skin (EpiDerm™) tissue models. Immunohistochemistry was used to detect CPD formation and persistence in human nasal biopsies and human tissue models. In subjects exposed to broadband ultraviolet radiation, DNA damage frequencies were determined prior to as well as immediately after treatment and at increasing times post-treatment. We observed significant levels of DNA damage immediately after treatment and efficient removal of the damage within a few days. No residual damage was observed in human subjects exposed to multiple UVB treatments several weeks after the last treatment. To better understand the molecular response of the nasal epithelium to DNA damage, parallel experiments were conducted in EpiAirway and EpiDerm model systems. Repair rates in these two tissues were very similar and comparable to that observed in human skin. The data suggest that the UV-induced DNA damage response of respiratory epithelia is very similar to that of the human epidermis and that nasal mucosa is able to efficiently repair UVB induced DNA damage. PMID:18671762

Are dark-skinned people really protected from ultraviolet radiation?

PubMed

Young, A L; Levy, S; Nighland, M; Grossman, R; Silvers, D N; Celebi, J T

2010-06-01

Premature ageing of the skin (photoageing) results from the action of ultraviolet radiation (UVR) on skin. One of the histopathological findings of photoageing is the presence of solar elastosis in the dermis. Skin pigmentation is protective against UVR. To evaluate the presence of solar elastosis in dark-skinned people. Normal facial skin biopsies of 147 dark-skinned and 140 light-skinned people were examined histopathologically for solar elastosis. The degree of solar elastosis was graded on a five-point scale by a panel of dermatopathologists blinded to patient demographics. There were 112 of 140 (80%) light-skinned and 50 of 147 (34%) dark-skinned patients with high-grade solar elastosis. In the dark-skinned patient group, high-grade solar elastosis was seen in 29 of 61 (47.5%) Hispanic and 5 of 49 (10.2%) African American subjects. Dark-skinned people are not completely protected from the effects of UVR.

Remote radiation dosimetry

DOEpatents

Braunlich, P.F.; Tetzlaff, W.; Hegland, J.E.; Jones, S.C.

1991-03-12

Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via a transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission. 8 figures.

Remote radiation dosimetry

DOEpatents

Braunlich, Peter F.; Tetzlaff, Wolfgang; Hegland, Joel E.; Jones, Scott C.

1991-01-01

Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission.

Incorporation of multiple cloud layers for ultraviolet radiation modeling studies

NASA Technical Reports Server (NTRS)

Charache, Darryl H.; Abreu, Vincent J.; Kuhn, William R.; Skinner, Wilbert R.

1994-01-01

Cloud data sets compiled from surface observations were used to develop an algorithm for incorporating multiple cloud layers into a multiple-scattering radiative transfer model. Aerosol extinction and ozone data sets were also incorporated to estimate the seasonally averaged ultraviolet (UV) flux reaching the surface of the Earth in the Detroit, Michigan, region for the years 1979-1991, corresponding to Total Ozone Mapping Spectrometer (TOMS) version 6 ozone observations. The calculated UV spectrum was convolved with an erythema action spectrum to estimate the effective biological exposure for erythema. Calculations show that decreasing the total column density of ozone by 1% leads to an increase in erythemal exposure by approximately 1.1-1.3%, in good agreement with previous studies. A comparison of the UV radiation budget at the surface between a single cloud layer method and a multiple cloud layer method presented here is discussed, along with limitations of each technique. With improved parameterization of cloud properties, and as knowledge of biological effects of UV exposure increase, inclusion of multiple cloud layers may be important in accurately determining the biologically effective UV budget at the surface of the Earth.

Dosimetry of laser emission

NASA Astrophysics Data System (ADS)

Kirillov, A. I.; Morskov, V. F.; Ustinov, N. D.

The basic criteria for dosimetric standards on photon, microwave, and ultraviolet emissions are reviewed. Attention is given to the biophysical effects of laser radiation, approaches to the evaluation of optical radiation hazard, and the effect of laser beams on the human eye. The fundamentals of the optical design of dosimeters are discussed, and an eye model is developed for a laser radiation meter. The discussion also covers the design of the electronic circuit of dosimeters and an evaluation of measurement errors.

EFFECTS OF ULTRAVIOLET RADIATION (UVR) ON THE RESPIRATORY ALLERGIC RESPONSES OF BALB/C MICE TO A FUNGAL ALLERGEN

EPA Science Inventory

EFFECTS OF ULTRAVIOLET RADIATION (UVR) ON THE RESPIRATORY ALLERGIC RESPONSES OF BALB/C MICE TO A FUNGAL ALLERGEN. M D W Ward, D M Sailstad, D L Andrews, E H Boykin, and MJ K Selgrade. National Health and Environmental Effects Research Laboratory, Office of Research and Developmen...

Medical Devices; General Hospital and Personal Use Devices; Classification of the Ultraviolet Radiation Chamber Disinfection Device. Final order.

PubMed

2015-11-20

The Food and Drug Administration (FDA or the Agency) is classifying the ultraviolet (UV) radiation chamber disinfection device into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the UV radiation chamber disinfection device classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device.

Quantitative analysis of vacuum-ultraviolet radiation from nanosecond laser-zinc interaction

NASA Astrophysics Data System (ADS)

Parchamy, Homaira; Szilagyi, John; Masnavi, Majid; Richardson, Martin

2018-07-01

The paper reports measurements of the vacuum-ultraviolet spectral irradiances of a flat zinc target over a wavelength region of 124-164 nm generated by 10 and 60 ns duration low-intensities, 5 ×109 - 3 ×1010 W cm-2, 1.06 μm wavelength laser pulses. Maximum radiation conversion efficiencies of 2.5%/2πsr and 0.8%/2πsr were measured for 60 and 10 ns laser pulses at the intensities of 5 ×109 and 1.4 ×1010 W cm-2, respectively. Atomic structure calculations using a relativistic configuration-interaction, flexible atomic code and a developed non-local thermodynamic equilibrium population kinetics model in comparison to the experimental spectra detected by the Seya-Namioka type monochromator reveal the strong broadband experimental emission originates mainly from 3d94p-3d94s, 3d94d-3d94p and 3d84p-3d84s, 3d84d-3d84p unresolved-transition arrays of double and triple ionized zinc, respectively. Two-dimensional radiation-hydrodynamics code is used to investigate time-space plasma evolution and spectral radiation of a 10 ns full-width-at-half-maximum Gaussian laser pulse-zinc interaction.

Maximum in the middle: nonlinear response of microbial plankton to ultraviolet radiation and phosphorus.

PubMed

Medina-Sánchez, Juan Manuel; Delgado-Molina, José Antonio; Bratbak, Gunnar; Bullejos, Francisco José; Villar-Argaiz, Manuel; Carrillo, Presentación

2013-01-01

The responses of heterotrophic microbial food webs (HMFW) to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2×5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses) after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the presence vs. absence of ultraviolet radiation. HMFW underwent a mid-term (<20 days) acute development following a noticeable unimodal response to P enrichment, which peaked at intermediate P-enrichment levels and, unexpectedly, was more accentuated under ultraviolet radiation. However, after depletion of dissolved inorganic P, the HMFW collapsed and was outcompeted by a low-diversity autotrophic compartment, which constrained the development of HMFW and caused a significant loss of functional biodiversity. The dynamics and relationships among variables, and the response patterns found, suggest the importance of biotic interactions (predation/parasitism and competition) in restricting HMFW development, in contrast to the role of abiotic factors as main drivers of autotrophic compartment. The response of HMFW may contribute to ecosystem resilience by favoring the maintenance of the peculiar paths of energy and nutrient-mobilization in these pristine ecosystems, which are vulnerable to threats by the joint action of abiotic stressors related to global change.

Maximum in the Middle: Nonlinear Response of Microbial Plankton to Ultraviolet Radiation and Phosphorus

PubMed Central

Medina-Sánchez, Juan Manuel; Delgado-Molina, José Antonio; Bratbak, Gunnar; Bullejos, Francisco José; Villar-Argaiz, Manuel; Carrillo, Presentación

2013-01-01

The responses of heterotrophic microbial food webs (HMFW) to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2×5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses) after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the presence vs. absence of ultraviolet radiation. HMFW underwent a mid-term (<20 days) acute development following a noticeable unimodal response to P enrichment, which peaked at intermediate P-enrichment levels and, unexpectedly, was more accentuated under ultraviolet radiation. However, after depletion of dissolved inorganic P, the HMFW collapsed and was outcompeted by a low-diversity autotrophic compartment, which constrained the development of HMFW and caused a significant loss of functional biodiversity. The dynamics and relationships among variables, and the response patterns found, suggest the importance of biotic interactions (predation/parasitism and competition) in restricting HMFW development, in contrast to the role of abiotic factors as main drivers of autotrophic compartment. The response of HMFW may contribute to ecosystem resilience by favoring the maintenance of the peculiar paths of energy and nutrient-mobilization in these pristine ecosystems, which are vulnerable to threats by the joint action of abiotic stressors related to global change. PMID:23593178

Role of Ultraviolet Radiation in Papillomavirus-Induced Disease

PubMed Central

Uberoi, Aayushi; Yoshida, Satoshi; Frazer, Ian H.; Pitot, Henry C.; Lambert, Paul F.

2016-01-01

Human papillomaviruses are causally associated with 5% of human cancers. The recent discovery of a papillomavirus (MmuPV1) that infects laboratory mice provides unique opportunities to study the life cycle and pathogenesis of papillomaviruses in the context of a genetically manipulatable host organism. To date, MmuPV1-induced disease has been found largely to be restricted to severely immunodeficient strains of mice. In this study, we report that ultraviolet radiation (UVR), specifically UVB spectra, causes wild-type strains of mice to become highly susceptible to MmuPV1-induced disease. MmuPV1-infected mice treated with UVB develop warts that progress to squamous cell carcinoma. Our studies further indicate that UVB induces systemic immunosuppression in mice that correlates with susceptibility to MmuPV1-associated disease. These findings provide new insight into how MmuPV1 can be used to study the life cycle of papillomaviruses and their role in carcinogenesis, the role of host immunity in controlling papillomavirus-associated pathogenesis, and a basis for understanding in part the role of UVR in promoting HPV infection in humans. PMID:27244228

Role of Ultraviolet Radiation in Papillomavirus-Induced Disease.

PubMed

Uberoi, Aayushi; Yoshida, Satoshi; Frazer, Ian H; Pitot, Henry C; Lambert, Paul F

2016-05-01

Human papillomaviruses are causally associated with 5% of human cancers. The recent discovery of a papillomavirus (MmuPV1) that infects laboratory mice provides unique opportunities to study the life cycle and pathogenesis of papillomaviruses in the context of a genetically manipulatable host organism. To date, MmuPV1-induced disease has been found largely to be restricted to severely immunodeficient strains of mice. In this study, we report that ultraviolet radiation (UVR), specifically UVB spectra, causes wild-type strains of mice to become highly susceptible to MmuPV1-induced disease. MmuPV1-infected mice treated with UVB develop warts that progress to squamous cell carcinoma. Our studies further indicate that UVB induces systemic immunosuppression in mice that correlates with susceptibility to MmuPV1-associated disease. These findings provide new insight into how MmuPV1 can be used to study the life cycle of papillomaviruses and their role in carcinogenesis, the role of host immunity in controlling papillomavirus-associated pathogenesis, and a basis for understanding in part the role of UVR in promoting HPV infection in humans.

The interaction between abiotic photodegradation and microbial decomposition under ultraviolet radiation.

PubMed

Wang, Jing; Liu, Lingli; Wang, Xin; Chen, Yiwei

2015-05-01

Elevated ultraviolet (UV) radiation has been demonstrated to stimulate litter decomposition. Despite years of research, it is still not fully understood whether the acceleration in litter degradation is primarily attributed to abiotic photodegradation or the combined effects of abiotic photodegradation and microbial decomposition. In this study, we used meta-analysis to synthesize photodegradation studies and compared the effects of UV radiation on litter decomposition between abiotic and biotic conditions. We also conducted a microcosm experiment to assess the effects of UV radiation on litter biodegradability and microbial activity. Overall, our meta-analysis found that under abiotic photodegradation, UV radiation reduced the remaining litter mass by 1.44% (95% CI: 0.85% to 2.08%), did not affect the remaining lignin and increased the dissolved organic carbon (DOC) concentration by 14.01% (1.49-23.67%). Under combined abiotic photodegradation and microbial decomposition, UV radiation reduced the remaining litter mass and lignin by 1.60% (0.04-3.58%) and 16.07% (9.27-24.23%), respectively, but did not alter DOC concentration. UV radiation had no significant impact on soil microbial biomass carbon (MBC), but it reduced microbial respiration by 44.91% (2.26-78.62%) and altered the composition of the microbial community. In addition, UV radiation reduced nitrogen (N) immobilization by 19.44% (4.77-37.92%). Our microcosm experiment further indicated that DOC concentration and the amount of respired C in UV-treated litter increased with UV exposure time, suggesting that longer UV exposure resulted in greater biodegradability. Overall, our study suggested that UV exposure could increase litter biodegradability by increasing the microbial accessibility of lignin, as well as the labile carbon supply to microbes. However, the remaining litter mass was not different between the abiotic and biotic conditions, most likely because the positive effect of UV radiation on litter

Technical considerations for implementation of x-ray CT polymer gel dosimetry.

PubMed

Hilts, M; Jirasek, A; Duzenli, C

2005-04-21

Gel dosimetry is the most promising 3D dosimetry technique in current radiation therapy practice. X-ray CT has been shown to be a feasible method of reading out polymer gel dosimeters and, with the high accessibility of CT scanners to cancer hospitals, presents an exciting possibility for clinical implementation of gel dosimetry. In this study we report on technical considerations for implementation of x-ray CT polymer gel dosimetry. Specifically phantom design, CT imaging methods, imaging time requirements and gel dose response are investigated. Where possible, recommendations are made for optimizing parameters to enhance system performance. The dose resolution achievable with an optimized system is calculated given voxel size and imaging time constraints. Results are compared with MRI and optical CT polymer gel dosimetry results available in the literature.

Investigation of thermal and temporal responses of ionization chambers in radiation dosimetry.

PubMed

AlMasri, Hussein; Funyu, Akira; Kakinohana, Yasumasa; Murayama, Sadayuki

2012-07-01

The ionization chamber is a primary dosimeter that is used in radiation dosimetry. Generally, the ion chamber response requires temperature/pressure correction according to the ideal gas law. However, this correction does not consider the thermal volume effect of chambers. The temporal and thermal volume effects of various chambers (CC01, CC13, NACP parallel-plate, PTW) with different wall and electrode materials have been studied in a water phantom. Measurements were done after heating the water with a suitable heating system, and chambers were submerged for a sufficient time to allow for temperature equilibrium. Temporal results show that all chambers equilibrate quickly in water. The equilibration time was between 3 and 5 min for all chambers. Thermal results show that all chambers expanded in response to heating except for the PTW, which contracted. This might be explained by the differences in the volumes of all chambers and also by the difference in wall material composition of PTW from the other chambers. It was found that the smallest chamber, CC01, showed the greatest expansion. The magnitude of the expansion was ~1, 0.8, and 0.9% for CC01, CC13, and parallel-plate chambers, respectively, in the temperature range of 295-320 K. The magnitude of the detected contraction was <0.3% for PTW in the same temperature range. For absolute dosimetry, it is necessary to make corrections for the ion chamber response, especially for small ion chambers like the CC01. Otherwise, room and water phantom temperatures should remain within a close range.

Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks by Ultraviolet Radiation: Metallicity Dependence

NASA Astrophysics Data System (ADS)

Nakatani, Riouhei; Hosokawa, Takashi; Yoshida, Naoki; Nomura, Hideko; Kuiper, Rolf

2018-04-01

Protoplanetary disks are thought to have lifetimes of several million yr in the solar neighborhood, but recent observations suggest that the disk lifetimes are shorter in a low-metallicity environment. We perform a suite of radiation hydrodynamics simulations of photoevaporating protoplanetary disks to study their long-term evolution of ∼10,000 yr and the metallicity dependence of mass-loss rates. Our simulations follow hydrodynamics, extreme and far-ultraviolet (FUV) radiative transfer, and nonequilibrium chemistry in a self-consistent manner. Dust-grain temperatures are also calculated consistently by solving the radiative transfer of the stellar irradiation and grain (re-)emission. We vary the disk metallicity over a wide range of {10}-4 {Z}ȯ ≤slant Z≤slant 10 {Z}ȯ . The photoevaporation rate is lower with higher metallicity in the range of {10}-1 {Z}ȯ ≲ Z≲ 10 {Z}ȯ , because dust shielding effectively prevents FUV photons from penetrating and heating the dense regions of the disk. The photoevaporation rate sharply declines at even lower metallicities in {10}-2 {Z}ȯ ≲ Z≲ {10}-1 {Z}ȯ , because FUV photoelectric heating becomes less effective than dust–gas collisional cooling. The temperature in the neutral region decreases, and photoevaporative flows are excited only in an outer region of the disk. At {10}-4 {Z}ȯ ≤slant Z≲ {10}-2 {Z}ȯ , H I photoionization heating acts as a dominant gas heating process and drives photoevaporative flows with a roughly constant rate. The typical disk lifetime is shorter at Z = 0.3 {Z}ȯ than at Z={Z}ȯ , being consistent with recent observations of the extreme outer galaxy.

Hanford Internal Dosimetry Program Manual, PNL-MA-552

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2003-10-10

This manual is a guide to the services provided by the Hanford Internal Dosimetry Program (IDP). It describes the roles of and relationships between the IDP and site contractors, and provides recommendations and guidance for consideration in implementing bioassay monitoring and internal dosimetry elements of radiation protection programs. Guidance includes identifying conditions under which workers should be placed on bioassay programs, types, descritptions, and capabilities of measurements, suggested routine bioassay programs, limitations on services, and practices for recording and reporting results.

Dosimetry around metallic ports in tissue expanders in patients receiving postmastectomy radiation therapy: an ex vivo evaluation.

PubMed

Moni, Janaki; Graves-Ditman, Maria; Cederna, Paul; Griffith, Kent; Krueger, Editha A; Fraass, Benedick A; Pierce, Lori J

2004-01-01

Postmastectomy breast reconstruction can be accomplished utilizing tissue expanders and implants. However, in patients who require postoperative radiotherapy, the complication rate with tissue expander/implant reconstruction can exceed 50%. One potential cause of this high complication rate may be the metallic port in the tissue expander producing altered dosimetry in the region of the metallic device. The purpose of this study was to quantify the radiation dose distribution in the vicinity of the metallic port and determine its potential contribution to this extremely high complication rate. The absolute dosimetric effect of the tissue expander's metallic port was quantified using film and thermoluminescent dosimetry (TLD) studies with a single beam incident on a metallic port extracted from an expander. TLD measurements were performed at 11 reproducible positions on an intact expander irradiated with tangential fields. A computed tomography (CT)-based treatment plan without inhomogeneity corrections was used to derive expected doses for all TLD positions. Multiple irradiation experiments were performed for all TLD data. Confidence intervals for the dose at TLD sites with the metallic port in place were compared to the expected dose at the site without the metallic port. Film studies did not reveal a significant component of scatter around the metallic port. TLD studies of the extracted metallic port revealed highest doses within the casing of the metallic port and no consistent increased dose at the surface of the expander. No excess dose due to the metallic port in the expander was noted with the phantom TLD data. Based upon these results, it does not appear that the metallic port in tissue expanders significantly contributes to the high complication rate experienced in patients undergoing tissue expander breast reconstruction and receiving radiation therapy. Strategies designed to reduce the breast reconstruction complication rate in this clinical setting will

THE EFFECT OF RADIATION ON ACETABULARIA. III. THE EFFECT OF X RADIATION AND ULTRAVIOLET RADIATION ON THE NUCLEATED PART OF ACETABULARIA MEDITERRANEA (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Six, E.

1958-01-01

A study was made of the effect of x rays and ultraviolet radiation of various wave lengths on the nucleated cell part of Acetabularia mediterranea. The x radintion leads to a reduction of the regenerative capacity, to a decrease of cyst formation of the regenerated cells, and to a lowering of the viability of the cysts. After a dose of 400 hr the regenerative capacity is almost completely destroyed. The capacity for the formation of reproductive gametes is lost after 40 hr. The effect of UV irradiation is, on the other hand, much less. It was concluded that the observedmore » functions of the nucleated cell part are essentially determined by the nucleus, which in rhizoids is extensively shielded against UV radiation. A complete regeneration up to cap formation follows so size and shape of the full-grown regenerated cells do not appear to be influenced essertially by x radiation. (tr-auth)« less

Vacuum ultraviolet radiation effects on two-dimensional MoS2 field-effect transistors

NASA Astrophysics Data System (ADS)

McMorrow, Julian J.; Cress, Cory D.; Arnold, Heather N.; Sangwan, Vinod K.; Jariwala, Deep; Schmucker, Scott W.; Marks, Tobin J.; Hersam, Mark C.

2017-02-01

Atomically thin MoS2 has generated intense interest for emerging electronics applications. Its two-dimensional nature and potential for low-power electronics are particularly appealing for space-bound electronics, motivating the need for a fundamental understanding of MoS2 electronic device response to the space radiation environment. In this letter, we quantify the response of MoS2 field-effect transistors (FETs) to vacuum ultraviolet (VUV) total ionizing dose radiation. Single-layer (SL) and multilayer (ML) MoS2 FETs are compared to identify differences that arise from thickness and band structure variations. The measured evolution of the FET transport properties is leveraged to identify the nature of VUV-induced trapped charge, isolating the effects of the interface and bulk oxide dielectric. In both the SL and ML cases, oxide trapped holes compete with interface trapped electrons, exhibiting an overall shift toward negative gate bias. Raman spectroscopy shows no variation in the MoS2 signatures as a result of VUV exposure, eliminating significant crystalline damage or oxidation as possible radiation degradation mechanisms. Overall, this work presents avenues for achieving radiation-hard MoS2 devices through dielectric engineering that reduces oxide and interface trapped charge.

Variation and Grey GM(1, 1) Prediction of Melting Peak Temperature of Polypropylene During Ultraviolet Radiation Aging

NASA Astrophysics Data System (ADS)

Chen, K.; Y Zhang, T.; Zhang, F.; Zhang, Z. R.

2017-12-01

Grey system theory regards uncertain system in which information is known partly and unknown partly as research object, extracts useful information from part known, and thereby revealing the potential variation rule of the system. In order to research the applicability of data-driven modelling method in melting peak temperature (T m) fitting and prediction of polypropylene (PP) during ultraviolet radiation aging, the T m of homo-polypropylene after different ultraviolet radiation exposure time investigated by differential scanning calorimeter was fitted and predicted by grey GM(1, 1) model based on grey system theory. The results show that the T m of PP declines with the prolong of aging time, and fitting and prediction equation obtained by grey GM(1, 1) model is T m = 166.567472exp(-0.00012t). Fitting effect of the above equation is excellent and the maximum relative error between prediction value and actual value of T m is 0.32%. Grey system theory needs less original data, has high prediction accuracy, and can be used to predict aging behaviour of PP.

Ultraviolet radiation and nanoparticle induced intracellular free radicals generation measured in human keratinocytes by electron paramagnetic resonance spectroscopy.

PubMed

Rancan, F; Nazemi, B; Rautenberg, S; Ryll, M; Hadam, S; Gao, Q; Hackbarth, S; Haag, S F; Graf, C; Rühl, E; Blume-Peytavi, U; Lademann, J; Vogt, A; Meinke, M C

2014-05-01

Several nanoparticle-based formulations used in cosmetics and dermatology are exposed to sunlight once applied to the skin. Therefore, it is important to study possible synergistic effects of nanoparticles and ultraviolet radiation. Electron paramagnetic resonance spectroscopy (EPR) was used to detect intracellular free radicals induced by ultraviolet B (UVB) radiation and amorphous silica nanoparticle and to evaluate the influence of nanoparticle surface chemistry on particle cytotoxicity toward HaCaT cells. Uncoated titanium dioxide nanoparticles served as positive control. In addition, particle intracellular uptake, viability, and induction of interleukin-6 were measured. We found that photo-activated titanium dioxide particles induced a significant amount of intracellular free radicals. On the contrary, no intracellular free radicals were generated by the investigated silica nanoparticles in the dark as well as under UVB radiation. However, under UVB exposure, the non-functionalized silica nanoparticles altered the release of IL-6. At the same concentrations, the amino-functionalized silica nanoparticles had no influence on UVB-induced IL-6 release. EPR spectroscopy is a useful technique to measure nanoparticle-induced intracellular free radicals. Non-toxic concentrations of silica particles enhanced the toxicity of UVB radiation. This synergistic effect was not mediated by particle-generated free radicals and correlated with particle surface charge and intracellular distribution. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

DNA damage and repair in plants under ultraviolet and ionizing radiations.

PubMed

Gill, Sarvajeet S; Anjum, Naser A; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315-400 nm; UV-B, 280-315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH(•)) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context.

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

PubMed Central

Gill, Sarvajeet S.; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315–400 nm; UV-B, 280–315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH•) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context. PMID:25729769

Resonantly enhanced method for generation of tunable, coherent vacuum ultraviolet radiation

DOEpatents

Glownia, James H.; Sander, Robert K.

1985-01-01

Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but to higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

Resonantly enhanced method for generation of tunable, coherent vacuum-ultraviolet radiation

DOEpatents

Glownia, J.H.; Sander, R.K.

1982-06-29

Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but no higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak

NASA Astrophysics Data System (ADS)

Rasouli, C.; Pourshahab, B.; Hosseini Pooya, S. M.; Orouji, T.; Rasouli, H.

2014-05-01

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points - three TLDs per point - to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Thermoluminescence characteristics of flat optical fiber in radiation dosimetry under different electron irradiation conditions

NASA Astrophysics Data System (ADS)

Alawiah, A.; Intan, A. M.; Bauk, S.; Abdul-Rashid, H. A.; Yusoff, Z.; Mokhtar, M. R.; Wan Abdullah, W. S.; Mat Sharif, K. A.; Mahdiraji, G. A.; Mahamd Adikan, F. R.; Tamchek, N.; Noor, N. M.; Bradley, D. A.

2013-05-01

Thermoluminescence (TL) flat optical fibers (FF) have been proposed as radiation sensor in medical dosimetry for both diagnostic and radiotherapy applications. A flat optical fiber with nominal dimensions of (3.226 × 3.417 × 0.980) mm3 contains pure silica SiO2 was selected for this research. The FF was annealed at 400°C for 1 h before irradiated. Kinetic parameters and dosimetric glow curve of TL response were studied in FF with respect to electron irradiation of 6 MeV, 15 MeV and 21 MeV using linear accelerator (LINAC) in the dose range of 2.0-10.0 Gy. The TL response was read using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader used includes; initial preheat temperature of 80°C, maximum readout temperature is 400°C and the heating rate of 30°Cs-1. The proposed FF shows excellent linear radiation response behavior within the clinical relevant dose range for all of these energies, good reproducibility, independence of radiation energy, independence of dose rate and exhibits a very low thermal fading. From these results, the proposed FF can be used as radiation dosimeter and favorably compares with the widely used of LiF:MgTi dosimeter in medical radiotherapy application.

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak.

PubMed

Rasouli, C; Pourshahab, B; Hosseini Pooya, S M; Orouji, T; Rasouli, H

2014-05-01

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points--three TLDs per point--to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Radiation effects in interventional radiology using biological and physical dosimetry methods: a case-control study.

PubMed

Ramos, Miguel; Montoro, Alegria; Almonacid, Miguel; Ferrer, Silvia; Barquinero, Joan Francesc; Tortosa, Ricardo; Verdú, Gumersindo; Rodríguez, Pilar; Barrios, Lleonard; Villaescusa, Juan Ignacio

2008-01-01

Interventional radiologists and staff members are frequently exposed to protracted and fractionated low doses of ionizing radiation, which extend during all their professional activities. These exposures can derive, due to the irradiation of skin tissues and peripheral blood, in deterministic effects (radiodermitis, aged skin, hands depilation) or stochastic ones (skin and non-solid cancers incidence). Epidemiological studies of population exposed to ionizing radiation provide information of radio-induced effects. The radiation risk or radiological detriment has been estimated from a group of six exposed interventionist radiologists of the Hospital La Fe (Valencia, Spain). Dosimetry has been periodically registered from TLDs and wrist dosimeters (physical methods) and estimated through translocations in lymphocytes of peripheral blood (biological methods), by extrapolating the yield of translocations to their respective dose-effect curves. The probability of non-melanoma skin cancer and leukaemia (acute myelogenous, acute lymphocytic and chronic myelogenous leukaemia) incidence has been estimated through the software RADRISK. This software is based on a transport model from epidemiological studies of population exposed to external low-LET ionizing radiation [1]. Other non-solid carcinomas have not been considered due to their low statistical power, such as myeloid and non-Hodgkin lymphomas. The discrepancies observed between the physically recorded doses and biological estimated doses could indicate that exposed workers did not always wear their dosimeters or these dosimeters were not always exposed to the radiation field.

Application of the planar-scanning technique to the near-field dosimetry of millimeter-wave radiators.

PubMed

Zhao, Jianxun; Lu, Hongmin; Deng, Jun

2015-02-01

The planar-scanning technique was applied to the experimental measurement of the electric field and power flux density (PFD) in the exposure area close to the millimeter-wave (MMW) radiator. In the near-field region, the field and PFD were calculated from the plane-wave spectrum of the field sampled on a scan plane far from the radiator. The measurement resolution was improved by reducing the spatial interval between the field samples to a fraction of half the wavelength and implementing multiple iterations of the fast Fourier transform. With the reference to the results from the numerical calculation, an experimental evaluation of the planar-scanning measurement was made for a 50 GHz radiator. Placing the probe 1 to 3 wavelengths from the aperture of the radiator, the direct measurement gave the near-field data with significant differences from the numerical results. The planar-scanning measurement placed the probe 9 wavelengths away from the aperture and effectively reduced the maximum and averaged differences in the near-field data by 70.6% and 65.5%, respectively. Applied to the dosimetry of an open-ended waveguide and a choke ring antenna for 60 GHz exposure, the technique proved useful to the measurement of the PFD in the near-field exposure area of MMW radiators. © 2015 Wiley Periodicals, Inc.

Radiation-induced damage analysed by luminescence methods in retrospective dosimetry and emergency response.

PubMed

Woda, Clemens; Bassinet, Céline; Trompier, François; Bortolin, Emanuela; Della Monaca, Sara; Fattibene, Paola

2009-01-01

The increasing risk of a mass casualty scenario following a large scale radiological accident or attack necessitates the development of appropriate dosimetric tools for emergency response. Luminescence dosimetry has been reliably applied for dose reconstruction in contaminated settlements for several decades and recent research into new materials carried close to the human body opens the possibility of estimating individual doses for accident and emergency dosimetry using the same technique. This paper reviews the luminescence research into materials useful for accident dosimetry and applications in retrospective dosimetry. The properties of the materials are critically discussed with regard to the requirements for population triage. It is concluded that electronic components found within portable electronic devices, such as e.g. mobile phones, are at present the most promising material to function as a fortuitous dosimeter in an emergency response.

Androgenic alopecia may have evolved to protect men from prostate cancer by increasing skin exposure to ultraviolet radiation.

PubMed

Kabai, Peter

2008-01-01

Androgenic alopecia affects populations adapted to colder climate, and individuals at an age and hormonal status susceptible to prostate cancer. Male pattern baldness enhances absorption of UV radiation on the top of the head, an area directly exposed to sunlight during everyday activities. Ultraviolet radiation is reported to reduce the risk of advanced prostate cancer. Here I propose that progression of androgenic alopecia rather than being a risk factor is a finely tuned mechanism evolved to protect against prostate cancer.

Characterization of the proton irradiation induced luminescence of materials and application in radiation oncology dosimetry

NASA Astrophysics Data System (ADS)

Darafsheh, Arash; Zhang, Rongxiao; Kassaee, Alireza; Finlay, Jarod C.

2018-03-01

Visible light generated as the result of interaction of ionizing radiation with matter can be used for radiation therapy quality assurance. In this work, we characterized the visible light observed during proton irradiation of poly(methyl methacrylate) (PMMA) and silica glass fiber materials by performing luminescence spectroscopy. The spectra of the luminescence signal from PMMA and silica glass fibers during proton irradiation showed continuous spectra whose shape were different from that expected from Čerenkov radiation, indicating that Čerenkov radiation cannot be the responsible radioluminescence signal. The luminescence signal from each material showed a Bragg peak pattern and their corresponding proton ranges are in agreement with measurements performed by a standard ion chamber. The spectrum of the silica showed two peaks at 460 and 650 nm stem from the point defects of the silica: oxygen deficiency centers (ODC) and non-bridging oxygen hole centers (NBOHC), respectively. The spectrum of the PMMA fiber showed a continuous spectrum with a peak at 410 nm whose origin is connected with the fluorescence of the PMMA material. Our results are of interest for various applications based on imaging radioluminescent signal in proton therapy and will inform on the design of high-resolution fiber probes for proton therapy dosimetry.

Sensitivity of two salamander (Ambystoma) species to ultraviolet radiation

USGS Publications Warehouse

Calfee, R.D.; Bridges, C.M.; Little, E.E.

2006-01-01

Increased ultraviolet-B (UV-B) radiation reaching the Earth's surface has been implicated in amphibian declines. Recent studies have shown that many amphibian species have differences in sensitivity depending on developmental stage. Embryos and larvae of Ambystoma maculatum (Spotted Salamander) and larvae of Ambystoma talpoideum (Mole Salamander) were exposed to five simulated UV-B treatments in controlled laboratory experiments to determine the relative sensitivity of different lifestages. Hatching success of the embryos exceeded 95% in all treatments; however, the larvae of both species exhibited greater sensitivity to UV-B exposure. Older larvae of A. maculatum that were not exposed to UV-B as embryos were more sensitive than larvae that had hatched during exposure to UV-B. Growth of surviving larvae of A. maculatum was significantly reduced as UV-B intensity increased, whereas growth of A. talpoideum was unaffected. These results were compared to ambient UV-B conditions in natural environments. It appears that the embryo stage is relatively unaffected by UV-B levels observed in natural habitats, probably because of protection from vegetation, organic matter in the water column, oviposition depth, and egg jelly. The larval stage of these species may be at greater risk, particularly if there is an increase in UV-B radiation exposure caused by increases in water clarity and/or decreases in dissolved organic carbon.

Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

1999-01-01

Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

THE ANTIGENIC POTENCY OF EPIDEMIC INFLUENZA VIRUS FOLLOWING INACTIVATION BY ULTRAVIOLET RADIATION

PubMed Central

Salk, Jonas E.; Lavin, G. I.; Francis, Thomas

1940-01-01

A study of the antigenic potency of influenza virus inactivated by ultraviolet radiation has been made. Virus so inactivated is still capable of functioning as an immunizing agent when given to mice by the intraperitoneal route. In high concentrations inactivated virus appears to be nearly as effective as active virus but when quantitative comparisons of the immunity induced by different dilutions are made, it is seen that a hundredfold loss in immunizing capacity occurs during inactivation. Virus in suspensions prepared from the lungs of infected mice is inactivated more rapidly than virus in tissue culture medium. A standard for the comparison of vaccines of epidemic influenza virus is proposed. PMID:19871057

Radiation Dosimetry of Whole-Body Dual-Tracer 18F-FDG and 11C-Acetate PET/CT for Hepatocellular Carcinoma.

PubMed

Liu, Dan; Khong, Pek-Lan; Gao, Yiming; Mahmood, Usman; Quinn, Brian; St Germain, Jean; Xu, X George; Dauer, Lawrence T

2016-06-01

Combined whole-body dual-tracer ((18)F-FDG and (11)C-acetate) PET/CT is increasingly used for staging hepatocellular carcinoma, with only limited studies investigating the radiation dosimetry data of these scans. The aim of the study was to characterize the radiation dosimetry of combined whole-body dual-tracer PET/CT protocols. Consecutive adult patients with hepatocellular carcinoma who underwent whole-body dual-tracer PET/CT scans were retrospectively reviewed with institutional review board approval. OLINDA/EXM 1.1 was used to estimate patient-specific internal dose exposure in each organ. Biokinetic models for (18)F-FDG and (11)C-acetate as provided by ICRP (International Commission on Radiological Protection) publication 106 were used. Standard reference phantoms were modified to more closely represent patient-specific organ mass. With patient-specific parameters, organ equivalent doses from each CT series were estimated using VirtualDose. Dosimetry capabilities for tube current modulation protocols were applied by integrating with the latest anatomic realistic models. Effective dose was calculated using ICRP publication 103 tissue-weighting coefficients for adult male and female, respectively. Fourteen scans were evaluated (12 men, 2 women; mean age ± SD, 60 ± 19.48 y). The patient-specific effective dose from (18)F-FDG and (11)C-acetate was 6.08 ± 1.49 and 1.56 ± 0.47 mSv, respectively, for male patients and 6.62 ± 1.38 and 1.79 ± 0.12 mSV, respectively, for female patients. The patient-specific effective dose of the CT component, which comprised 2 noncontrast whole-body scans, to male and female patients was 21.20 ± 8.94 and 14.79 ± 3.35 mSv, respectively. Thus, the total effective doses of the combined whole-body dual-tracer PET/CT studies for male and female patients were 28.84 ± 10.18 and 23.19 ± 4.61 mSv, respectively. Patient-specific parameters allow for more accurate estimation of organ equivalent doses. Considering the substantial

Methods and Models of the Hanford Internal Dosimetry Program, PNNL-MA-860

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2003-01-03

This manual describes the technical basis for the design of the routine radiobioassay monitoring program and assessments of internal dose. Its purpose is to provide a historical record of the methods, models, and assumptions used for internal dosimetry at Hanford, and serve as a technical reference for radiation protection and dosimetry staff.

Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation

PubMed Central

Martinez-Levasseur, Laura M.; Birch-Machin, Mark A.; Bowman, Amy; Gendron, Diane; Weatherhead, Elizabeth; Knell, Robert J.; Acevedo-Whitehouse, Karina

2013-01-01

A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies. PMID:23989080

Reviewing three dimensional dosimetry: basics and utilization as presented over 17 Years of DosGel and IC3Ddose

NASA Astrophysics Data System (ADS)

Schreiner, L. J.

2017-05-01

For seventeen years a community of basic and clinical scientists and researchers has been meeting bi-annually to promote the clinical advance of techniques to measure radiation dose in three dimensions. The interest in this dosimetry was motivated by its promise as an effective methodology for 3D measurement of the complex conformal dose distributions achieved by modern techniques such as Intensity Modulated and Volumetric Arc Radiation Therapy. Each of the International Conferences on 3D Radiation Dosimetry resulted in the publication of informative proceedings [1-8], the majority openly available on the internet. The proceedings included papers that: i) reviewed the basic science of the radiation sensitive materials used to accumulate the dose information, ii) introduced the science and engineering of the imaging systems required to read the information out, iii) described the work flows and systems required for efficient dosimetry, iv) reported the protocols required for reproducible dosimetry, and v) showed examples of clinical use illustrating advantage and limitations of the dosimetry. This paper is intended to use the framework provided by these proceedings to review the current 3D chemical dosimeters available and to discuss the requirements for their use. The paper describes how 3D dosimetry can complement other dose delivery validation approaches available in the clinic. It closes with some personal reflections of how the motivation for, and practice of, 3D dosimetry have changed (or not) over the years.

Ultraviolet Radiation in Wound Care: Sterilization and Stimulation

PubMed Central

Gupta, Asheesh; Avci, Pinar; Dai, Tianhong; Huang, Ying-Ying; Hamblin, Michael R.

2013-01-01

Significance Wound care is an important area of medicine considering the increasing age of the population who may have diverse comorbidities. Light-based technology comprises a varied set of modalities of increasing relevance to wound care. While low-level laser (or light) therapy and photodynamic therapy both have wide applications in wound care, this review will concentrate on the use of ultraviolet (UV) radiation. Recent Advances UVC (200–280 nm) is highly antimicrobial and can be directly applied to acute wound infections to kill pathogens without unacceptable damage to host tissue. UVC is already widely applied for sterilization of inanimate objects. UVB (280–315 nm) has been directly applied to the wounded tissue to stimulate wound healing, and has been widely used as extracorporeal UV radiation of blood to stimulate the immune system. UVA (315–400 nm) has distinct effects on cell signaling, but has not yet been widely applied to wound care. Critical Issues Penetration of UV light into tissue is limited and optical technology may be employed to extend this limit. UVC and UVB can damage DNA in host cells and this risk must be balanced against beneficial effects. Chronic exposure to UV can be carcinogenic and this must be considered in planning treatments. Future Directions New high-technology UV sources, such as light-emitting diodes, lasers, and microwave-generated UV plasma are becoming available for biomedical applications. Further study of cellular signaling that occurs after UV exposure of tissue will allow the benefits in wound healing to be better defined. PMID:24527357

Estimation of background radiation doses for the Peninsular Malaysia's population by ESR dosimetry of tooth enamel.

PubMed

Rodzi, Mohd; Zhumadilov, Kassym; Ohtaki, Megu; Ivannikov, Alexander; Bhattacharjee, Deborshi; Fukumura, Akifumi; Hoshi, Masaharu

2011-08-01

Background radiation dose is used in dosimetry for estimating occupational doses of radiation workers or determining radiation dose of an individual following accidental exposure. In the present study, the absorbed dose and the background radiation level are determined using the electron spin resonance (ESR) method on tooth samples. The effect of using different tooth surfaces and teeth exposed with single medical X-rays on the absorbed dose are also evaluated. A total of 48 molars of position 6-8 were collected from 13 district hospitals in Peninsular Malaysia. Thirty-six teeth had not been exposed to any excessive radiation, and 12 teeth had been directly exposed to a single X-ray dose during medical treatment prior to extraction. There was no significant effect of tooth surfaces and exposure with single X-rays on the measured absorbed dose of an individual. The mean measured absorbed dose of the population is 34 ± 6.2 mGy, with an average tooth enamel age of 39 years. From the slope of a regression line, the estimated annual background dose for Peninsular Malaysia is 0.6 ± 0.3 mGy y(-1). This value is slightly lower than the yearly background dose for Malaysia, and the radiation background dose is established by ESR tooth measurements on samples from India and Russia.

Shared dosimetry error in epidemiological dose-response analyses

DOE PAGES

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail; ...

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. The use of these methods in the context of several studies including, the Mayak Worker Cohort, and the U.S. Atomic Veterans Study, is discussed.« less

Shared Dosimetry Error in Epidemiological Dose-Response Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. Use of these methods for several studies, including the Mayak Worker Cohort and the U.S. Atomic Veterans Study, is discussed.« less

Coordinated ultraviolet and radio observations of selected nearby stars

NASA Technical Reports Server (NTRS)

Lang, Kenneth R.

1987-01-01

All of the US2 shifts assigned were successfully completed with simultaneous International Ultraviolet Explorer (IUE) and the Very Large Array (VLA) observations of the proposed target stars. The target stars included dwarf M flare stars and RS CVn stars. The combined ultraviolet (IUE) and microwave (VLA) observations have provided important new insights to the radiation mechanisms at these two widely-separated regions of the electromagnetic spectrum. The VLA results included the discovery of narrow-band microwave radiation and rapid time variations in the microwave radiation of dwarf M flare stars. The results indicate that conventional radiation mechanisms cannot explain the microwave emission from these stars. In general, ultraviolet variations and bursts occur when no similar variations are detected at microwave wavelengths and vice versa. Although these is some overlap, the variations in these two spectral regions are usually uncorrelated, suggesting that there is little interaction between the activity centers at the two associated atmospheric levels.

[Association between sunburn in children and ultraviolet radiation and ozone layer, during six summers (1996-2001) in Santiago, Chile (33,5 degrees S)].

PubMed

Aranibar, Ligia; Cabrera, Sergio; Honeyman, Juan

2003-09-01

During the recent 10 years the ozone layer has decreased while ultraviolet radiation has increased in Santiago, Chile. To determine whether the number of sunburns in children correlate with ultraviolet radiation in Santiago. During six Austral Summers (1996-2001) children below 15 years old, consulting for sunburn, were evaluated at the "Corporation for the Aid of Burned Children" (COANIQUEM) in Santiago (33.5 degrees S). The number of children with sunburns during each Summer was compared with the corresponding UV-B radiation and the ozone thickness, to establish a probable relation between a geophysical change and its consequences in skin health. The ozone layer values were obtained from the NASA WEB-page and the ultraviolet radiation was measured with a four-channel medium resolution radiometer. In each Summer there was a predominance of sunburns among boys and among ages between 6 and 10 years. During the 96-97 Austral Summer, the highest number of children with sunburns (63) was diagnosed. That Summer also had the highest mean UV-305 nm radiation with an important amount of days with ozone < or = 260 Dobson Units. Only during that Summer an inverse correlation between ozone and UV-305 nm radiation was detected. At the same time the maximal values of Erythemal Dose Rate (33 muWatt cm2), UV Index (13) and Erythemal Daily Dose (7.500 Joule m2) were observed. In Santiago, Summers with a higher number of days with low ozone protection seem to reappear every 3 years. Understanding the interaction of physical processes that control the ozone layer, may help to design better photo-protection programs for human health.

Ultraviolet-B radiation induced crosslinking improves physical properties of cold- and warm-water fish gelatin gels and films

USDA-ARS?s Scientific Manuscript database

Cold- and warm-water fish gelatin granules were exposed to ultraviolet-B radiation for doses up to 29.7 J/cm2. Solutions and films were prepared from the granules. Gel electrophoresis and refractive index were used to examine changes in molecular weight of the samples. Also, the gel strength and rhe...

Vacuum Ultraviolet Radiation and Atomic Oxygen Durability Evaluation of HST Bi-Stem Thermal Shield Materials

NASA Technical Reports Server (NTRS)

Dever, Joyce; deGroh, Kim K.

2002-01-01

Bellows-type thermal shields were used on the bi-stems of replacement solar arrays installed on the Hubble Space Telescope (HST) during the first HST servicing mission (SMI) in December 1993. These thermal shields helped reduce the problem of thermal gradient- induced jitter observed with the original HST solar arrays during orbital thermal cycling and have been in use on HST for eight years. This paper describes ground testing of the candidate solar array bi-stem thermal shield materials including backside aluminized Teflon(R)FEP (fluorinated ethylene propylene) with and without atomic oxygen (AO) and ultraviolet radiation protective surface coatings for durability to AO and combined AO and vacuum ultraviolet (VOV) radiation. NASA Glenn Research Center (GRC) conducted VUV and AO exposures of samples of candidate thermal shield materials at HST operational temperatures and pre- and post-exposure analyses as part of an overall program coordinated by NASA Goddard Space Flight Center (GSFC) to determine the on-orbit durability of these materials. Coating adhesion problems were observed for samples having the AO- and combined AO/UV-protective coatings. Coating lamination occurred with rapid thermal cycling testing which simulated orbital thermal cycling. This lack of adhesion caused production of coating flakes from the material that would have posed a serious risk to HST optics if the coated materials were used for the bi-stem thermal shields. No serious degradation was observed for the uncoated aluminized Teflon(R) as evaluated by optical microscopy, although atomic force microscopy (AFM) microhardness testing revealed that an embrittled surface layer formed on the uncoated Teflon(R) surface due to vacuum ultraviolet radiation exposure. This embrittled layer was not completely removed by AO erosion, No cracks or particle flakes were produced for the embrittled uncoated material upon exposure to VUV and AO at operational temperatures to an equivalent exposure of

Weekend personal ultraviolet radiation exposure in four cities in Australia: influence of temperature, humidity and ambient ultraviolet radiation.

PubMed

Xiang, Fan; Harrison, Simone; Nowak, Madeleine; Kimlin, Michael; Van der Mei, Ingrid; Neale, Rachel E; Sinclair, Craig; Lucas, Robyn M

2015-02-01

To examine the effects of meteorological factors on weekend sun exposure behaviours and personal received dose of ultraviolet radiation (UVR) in Australian adults. Australian adults (n=1002) living in Townsville (19°S, 146°E), Brisbane (27°S, 153°E), Canberra (35°S, 149°E) and Hobart (43°S, 147°E) were recruited between 2009 and 2010. Data on sun exposure behaviours were collected by daily sun exposure dairies; personal UVR exposure was measured with a polysulphone dosimeter. Meteorological data were obtained from the Australian Bureau of Meteorology; ambient UVR levels were estimated using the Ozone Monitoring Instrument data. Higher daily maximum temperatures were associated with reduced likelihood of wearing a long-sleeved shirt or wearing long trousers in Canberra and Hobart, and higher clothing-adjusted UVR dose in Canberra. Higher daily humidity was associated with less time spent outdoors in Canberra. Higher ambient UVR level was related to a greater clothing-adjusted personal UVR dose in Hobart and a greater likelihood of using sunscreen in Townsville. The current findings enhance our understanding of the impact of weather conditions on the population's sun exposure behaviours. This information will allow us to refine current predictive models for UVR-related diseases, and guide future health service and health promotion needs. Copyright © 2015 Elsevier B.V. All rights reserved.

Publicly Released Prompt Radiation Spectra Suitable for Nuclear Detonation Simulations, Revision 1

DTIC Science & Technology

2017-12-01

dominates the photon emission. During the Hiroshima and Nagasaki bombings , the prompt radiation contributed from 40% to 70% of the free-in-air dose...Terms for the Initial Radiation. LA-UR-83-198. US-Japan Joint Workshop on the Reassessment of the A- Bomb Radiation Dosimetry in Hiroshima and Nagasaki...2005). Reassessment of the Atomic Bomb Radiation Dosimetry for Hiroshima and Nagasaki—Dosimetry System 2002. Hiroshima, Japan: Radiation Effects

Radiation dosimetry predicts IQ after conformal radiation therapy in pediatric patients with localized ependymoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Thomas E.; Kiehna, Erin N.; Li Chenghong

2005-12-01

Purpose: To assess the effects of radiation dose-volume distribution on the trajectory of IQ development after conformal radiation therapy (CRT) in pediatric patients with ependymoma. Methods and Materials: The study included 88 patients (median age, 2.8 years {+-} 4.5 years) with localized ependymoma who received CRT (54-59.4 Gy) that used a 1-cm margin on the postoperative tumor bed. Patients were evaluated with tests that included IQ measures at baseline (before CRT) and at 6, 12, 24, 36, 48, and 60 months. Differential dose-volume histograms (DVH) were derived for total-brain, supratentorial-brain, and right and left temporal-lobe volumes. The data were partitionedmore » into three dose intervals and integrated to create variables that represent the fractional volume that received dose over the specified intervals (e.g., V{sub 0-20Gy}, V{sub 20-40Gy}, V{sub 40-65Gy}) and modeled with clinical variables to develop a regression equation to estimate IQ after CRT. Results: A total of 327 IQ tests were performed in 66 patients with infratentorial tumors and 20 with supratentorial tumors. The median follow-up was 29.4 months. For all patients, IQ was best estimated by age (years) at CRT; percent volume of the supratentorial brain that received doses between 0 and 20 Gy, 20 and 40 Gy, and 40 and 65 Gy; and time (months) after CRT. Age contributed significantly to the intercept (p > 0.0001), and the dose-volume coefficients were statistically significant (V{sub 0-20Gy}, p = 0.01; V{sub 20-40Gy}, p < 0.001; V{sub 40-65Gy}, p = 0.04). A similar model was developed exclusively for patients with infratentorial tumors but not supratentorial tumors. Conclusion: Radiation dosimetry can be used to predict IQ after CRT in patients with localized ependymoma. The specificity of models may be enhanced by grouping according to tumor location.« less

Generating circularly polarized radiation in the extreme ultraviolet spectral range at the free-electron laser FLASH

NASA Astrophysics Data System (ADS)

von Korff Schmising, Clemens; Weder, David; Noll, Tino; Pfau, Bastian; Hennecke, Martin; Strüber, Christian; Radu, Ilie; Schneider, Michael; Staeck, Steffen; Günther, Christian M.; Lüning, Jan; Merhe, Alaa el dine; Buck, Jens; Hartmann, Gregor; Viefhaus, Jens; Treusch, Rolf; Eisebitt, Stefan

2017-05-01

A new device for polarization control at the free electron laser facility FLASH1 at DESY has been commissioned for user operation. The polarizer is based on phase retardation upon reflection off metallic mirrors. Its performance is characterized in three independent measurements and confirms the theoretical predictions of efficient and broadband generation of circularly polarized radiation in the extreme ultraviolet spectral range from 35 eV to 90 eV. The degree of circular polarization reaches up to 90% while maintaining high total transmission values exceeding 30%. The simple design of the device allows straightforward alignment for user operation and rapid switching between left and right circularly polarized radiation.

The effect of melatonin on eye lens of rats exposed to ultraviolet radiation.

PubMed

Anwar, M M; Moustafa, M A

2001-05-01

We investigated the influence of exogenously administered melatonin on adult rats eye lenses exposed to ultraviolet radiation (UV) A and B ranging from 356-254 nm irradiation at 8 microW/cm(2). Rats exposed to this range of UV for 15 min for one week showed a significant (P<0.05) reduction in antioxidant enzymes activities; superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and elevated (P<0.001) lipid peroxidation served as an index of cellular damage by free radicals. UV-radiation significantly (P<0.001) elevated calcium ions (Ca(2+)) and lactate dehydrogenase (LDH) activity in lenses. Depleting animals of their stores of important intracellular antioxidant and elevating lenticular Ca(2+) by UV irradiation, may be the main cause of lens opacification. Melatonin injection with radiation significantly reduced (P<0.05) lipid peroxidation, Ca(2+) and (P<0.001) for LDH. When melatonin was injected after radiation, SOD and GSH-Px enzyme activities increased significantly (P<0.01), and lipid peroxidation, Ca(2+) levels and LDH activities were reduced significantly. Melatonin injection after UV radiation was as effective as melatonin treatment concurrent with UV irradiation. We conclude that melatonin may protect the eye lens from the damaging effects of UV exposure, and its actions protect lens from oxidative stress, elevating Ca(2+) levels, which are considered as an important causes of cataractogenesis.

Skeletal dosimetry models for alpha-particles for use in molecular radiotherapy

NASA Astrophysics Data System (ADS)

Watchman, Christopher J.

Molecular radiotherapy is a cancer treatment methodology whereby a radionuclide is combined with a biologically active molecule to preferentially target cancer cells. Alpha-particle emitting radionuclides show significant potential for use in molecular radiotherapy due to the short range of the alpha-particles in tissue and their high rates of energy deposition. Current radiation dosimetry models used to assess alpha emitter dose in the skeleton were developed originally for occupational applications. In medical dosimetry, individual variability in uptake, translocation and other biological factors can result in poor correlation of clinical outcome with marrow dose estimates determined using existing skeletal models. Methods presented in this work were developed in response to the need for dosimetry models which account for these biological and patient-specific factors. Dosimetry models are presented for trabecular bone alpha particle dosimetry as well as a model for cortical bone dosimetry. These radiation transport models are the 3D chord-based infinite spongiosa transport model (3D-CBIST) and the chord-based infinite cortical transport model (CBICT), respectively. Absorbed fraction data for several skeletal tissues for several subjects are presented. Each modeling strategy accounts for biological parameters, such as bone marrow cellularity, not previously incorporated into alpha-particle skeletal dosimetry models used in radiation protection. Using these data a study investigating the variability in alpha-particle absorbed fractions in the human skeleton is also presented. Data is also offered relating skeletal tissue masses in individual bone sites for a range of ages. These data are necessary for dose calculations and have previously only been available as whole body tissue masses. A revised 3D-CBIST model is also presented which allows for changes in endosteum thickness to account for revised target cell location of tissues involved in the radiological

The Extreme Ultraviolet Explorer

NASA Technical Reports Server (NTRS)

Malina, R. F.; Bowyer, S.; Lampton, M.; Finley, D.; Paresce, F.; Penegor, G.; Heetderks, H.

1982-01-01

The Extreme Ultraviolet Explorer Mission is described. The purpose of this mission is to search the celestial sphere for astronomical sources of extreme ultraviolet (EUV) radiation (100 to 1000 A). The search will be accomplished with the use of three EUV telescopes, each sensitive to different bands within the EUV band. A fourth telescope will perform a higher sensitivity search of a limited sample of the sky in a single EUV band. In six months, the entire sky will be scanned at a sensitivity level comparable to existing surveys in other more traditional astronomical bandpasses.

Surface modification of polymers for biocompatibility via exposure to extreme ultraviolet radiation.

PubMed

Inam Ul Ahad; Bartnik, Andrzej; Fiedorowicz, Henryk; Kostecki, Jerzy; Korczyc, Barbara; Ciach, Tomasz; Brabazon, Dermot

2014-09-01

Polymeric biomaterials are being widely used for the treatment of various traumata, diseases and defects in human beings due to ease in their synthesis. As biomaterials have direct interaction with the extracellular environment in the biological world, biocompatibility is a topic of great significance. The introduction or enhancement of biocompatibility in certain polymers is still a challenge to overcome. Polymer biocompatibility can be controlled by surface modification. Various physical and chemical methods (e.g., chemical and plasma treatment, ion implantation, and ultraviolet irradiation etc.) are in use or being developed for the modification of polymer surfaces. However an important limitation in their employment is the alteration of bulk material. Different surface and bulk properties of biomaterials are often desirable for biomedical applications. Because extreme ultraviolet (EUV) radiation penetration is quite limited even in low density mediums, it could be possible to use it for surface modification without influencing the bulk material. This article reviews the degree of biocompatibility of different polymeric biomaterials being currently employed in various biomedical applications, the surface properties required to be modified for biocompatibility control, plasma and laser ablation based surface modification techniques, and research studies indicating possible use of EUV for enhancing biocompatibility. © 2013 Wiley Periodicals, Inc.

Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

NASA Astrophysics Data System (ADS)

Shinn, Jong-Ho; Seon, Kwang-Il

2015-12-01

In order to examine their relation to the host galaxy, the extraplanar dusts of six nearby galaxies are modeled, employing a three-dimensional Monte Carlo radiative transfer code. The targets are from the highly inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are generally well-reproduced by two dust layers and one light source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFRUV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of an extraplanar dust layer. However, it is found that the remaining three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GALEX point spread function. This indicates that the galaxy samples reported to have UV halos may be contaminated by galaxies with negligible extraplanar (halo) dust. The galaxies showing evidence of an extraplanar dust layer fall within a narrow range on the scatter plots between physical parameters such as SFRUV and extraplanar dust mass. Several mechanisms that could possibly produce the extraplanar dust are discussed. We also found a hint that the extraplanar dust scale-height might not be much different from the polycyclic aromatic hydrocarbon emission characteristic height.

The Molecular and Physiological Responses of Physcomitrella patens to Ultraviolet-B Radiation1[W][OA

PubMed Central

Wolf, Luise; Rizzini, Luca; Stracke, Ralf; Ulm, Roman; Rensing, Stefan A.

2010-01-01

Ultraviolet-B (UV-B) radiation present in sunlight is an important trigger of photomorphogenic acclimation and stress responses in sessile land plants. Although numerous moss species grow in unshaded habitats, our understanding of their UV-B responses is very limited. The genome of the model moss Physcomitrella patens, which grows in sun-exposed open areas, encodes signaling and metabolic components that are implicated in the UV-B response in flowering plants. In this study, we describe the response of P. patens to UV-B radiation at the morphological and molecular levels. We find that P. patens is more capable of surviving UV-B stress than Arabidopsis (Arabidopsis thaliana) and describe the differential expression of approximately 400 moss genes in response to UV-B radiation. A comparative analysis of the UV-B response in P. patens and Arabidopsis reveals both distinct and conserved pathways. PMID:20427465

EPR dosimetry in a mixed neutron and gamma radiation field.

PubMed

Trompier, F; Fattibene, P; Tikunov, D; Bartolotta, A; Carosi, A; Doca, M C

2004-01-01

Suitability of Electron Paramagnetic Resonance (EPR) spectroscopy for criticality dosimetry was evaluated for tooth enamel, mannose and alanine pellets during the 'international intercomparison of criticality dosimetry techniques' at the SILENE reactor held in Valduc in June 2002, France. These three materials were irradiated in neutron and gamma-ray fields of various relative intensities and spectral distributions in order to evaluate their neutron sensitivity. The neutron response was found to be around 10% for tooth enamel, 45% for mannose and between 40 and 90% for alanine pellets according their type. According to the IAEA recommendations on the early estimate of criticality accident absorbed dose, analyzed results show the EPR potentiality and complementarity with regular criticality techniques.

Conversion of far ultraviolet to visible radiation: absolute measurements of the conversion efficiency of tetraphenyl butadiene

NASA Astrophysics Data System (ADS)

Vest, Robert E.; Coplan, Michael A.; Clark, Charles W.

Far ultraviolet (FUV) scintillation of noble gases is used in dark matter and neutrino research and in neutron detection. Upon collisional excitation, noble gas atoms recombine into excimer molecules that decay by FUV emission. Direct detection of FUV is difficult. Another approach is to convert it to visible light using a wavelength-shifting medium. One such medium, tetraphenyl butadiene (TPB) can be vapor-deposited on substrates. Thus the quality of thin TPB films can be tightly controlled. We have measured the absolute efficiency of FUV-to-visible conversion by 1 μm-thick TPB films vs. FUV wavelengths between 130 and 300 nm, with 1 nm resolution. The energy efficiency of FUV to visible conversion varies between 1% and 5%. We make comparisons with other recent results. Work performed at the NIST SURF III Synchrotron Ultraviolet Radiation Facility,.

Development of europium doped BaSO4 TL OSL dual phosphor for radiation dosimetry applications

NASA Astrophysics Data System (ADS)

Patle, Anita; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

2015-08-01

This paper presents the results on the preparation and characterization of Europium-doped Barium sulfate (BaSO4: Eu) TL /OSL dual phosphor. The OSL sensitivity was found to be 11% of the commercially available Al2O3: C, using area integration method. The sample also shows good TL sensitivity and the dosimetric peak appears around 190°C with a shoulder at 282°C. After OSL readout, No change in the TL glow curve is observed. Since the observed TL peaks are not responsible for the observed OSL, good OSL as well as TL sensitivity and low fading will make this phosphor suitable for applications in radiation dosimetry using OSL as well as TL.

Effects of water on fingernail electron paramagnetic resonance dosimetry.

PubMed

Zhang, Tengda; Zhao, Zhixin; Zhang, Haiying; Zhai, Hezheng; Ruan, Shuzhou; Jiao, Ling; Zhang, Wenyi

2016-09-01

Electron paramagnetic resonance (EPR) is a promising biodosimetric method, and fingernails are sensitive biomaterials to ionizing radiation. Therefore, kinetic energy released per unit mass (kerma) can be estimated by measuring the level of free radicals within fingernails, using EPR. However, to date this dosimetry has been deficient and insufficiently accurate. In the sampling processes and measurements, water plays a significant role. This paper discusses many effects of water on fingernail EPR dosimetry, including disturbance to EPR measurements and two different effects on the production of free radicals. Water that is unable to contact free radicals can promote the production of free radicals due to indirect ionizing effects. Therefore, varying water content within fingernails can lead to varying growth rates in the free radical concentration after irradiation-these two variables have a linear relationship, with a slope of 1.8143. Thus, EPR dosimetry needs to be adjusted according to the water content of the fingernails of an individual. When the free radicals are exposed to water, the eliminating effect will appear. Therefore, soaking fingernail pieces in water before irradiation, as many researchers have previously done, can cause estimation errors. In addition, nails need to be dehydrated before making accurately quantitative EPR measurements. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

High-resolution ultraviolet radiation fields of classical T Tauri stars

DOE Office of Scientific and Technical Information (OSTI.GOV)

France, Kevin; Schindhelm, Eric; Bergin, Edwin A.

2014-04-01

The far-ultraviolet (FUV; 912-1700 Å) radiation field from accreting central stars in classical T Tauri systems influences the disk chemistry during the period of giant planet formation. The FUV field may also play a critical role in determining the evolution of the inner disk (r < 10 AU), from a gas- and dust-rich primordial disk to a transitional system where the optically thick warm dust distribution has been depleted. Previous efforts to measure the true stellar+accretion-generated FUV luminosity (both hot gas emission lines and continua) have been complicated by a combination of low-sensitivity and/or low-spectral resolution and did not includemore » the contribution from the bright Lyα emission line. In this work, we present a high-resolution spectroscopic study of the FUV radiation fields of 16 T Tauri stars whose dust disks display a range of evolutionary states. We include reconstructed Lyα line profiles and remove atomic and molecular disk emission (from H{sub 2} and CO fluorescence) to provide robust measurements of both the FUV continuum and hot gas lines (e.g., Lyα, N V, C IV, He II) for an appreciable sample of T Tauri stars for the first time. We find that the flux of the typical classical T Tauri star FUV radiation field at 1 AU from the central star is ∼10{sup 7} times the average interstellar radiation field. The Lyα emission line contributes an average of 88% of the total FUV flux, with the FUV continuum accounting for an average of 8%. Both the FUV continuum and Lyα flux are strongly correlated with C IV flux, suggesting that accretion processes dominate the production of both of these components. On average, only ∼0.5% of the total FUV flux is emitted between the Lyman limit (912 Å) and the H{sub 2} (0-0) absorption band at 1110 Å. The total and component-level high-resolution radiation fields are made publicly available in machine-readable format.« less

Effects of elevated ultraviolet radiation on primary metabolites in selected alpine algae and cyanobacteria

PubMed Central

Hartmann, Anja; Albert, Andreas; Ganzera, Markus

2015-01-01

Extremophilic green algae and cyanobacteria are the most abundant species in high mountain habitats, where rough climate conditions such as temperature differences, limited water retention and high ultraviolet (UV) radiation are the cause for a restricted biological diversity in favor of a few specialized autotrophic microorganisms. In this study, we investigated four algal species from alpine habitat in a sun simulator for their defense strategies in response to UV-A radiation (315–400 nm) up to 13.4 W/m2 and UV-B radiation (280–315 nm) up to 2.8 W/m2. Besides changes in pigment composition we discovered that primary polar metabolites like aromatic amino acids, nucleic bases and nucleosides are increasingly produced when the organisms are exposed to elevated UV radiation. Respective compounds were isolated and identified, and in order to quantify them an HPLC-DAD method was developed and validated. Our results show that especially tyrosine and guanosine were found to be generally two to three times upregulated in the UV-B exposed samples compared to the non-treated control. PMID:26065817

Are there mechanistic differences between ultraviolet and visible radiation induced skin pigmentation?

PubMed