WorldWideScience

Sample records for background radiation dose-rates

  1. Atmospheric radiation flight dose rates

    Science.gov (United States)

    Tobiska, W. K.

    2015-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

  2. Radiation Leukemogenesis at Low Dose Rates

    International Nuclear Information System (INIS)

    The major goals of this program were to study the efficacy of low dose rate radiation exposures for the induction of acute myeloid leukemia (AML) and to characterize the leukemias that are caused by radiation exposures at low dose rate. An irradiator facility was designed and constructed that allows large numbers of mice to be irradiated at low dose rates for protracted periods (up to their life span). To the best of our knowledge this facility is unique in the US and it was subsequently used to study radioprotectors being developed for radiological defense (PLoS One. 7(3), e33044, 2012) and is currently being used to study the role of genetic background in susceptibility to radiation-induced lung cancer. One result of the irradiation was expected; low dose rate exposures are ineffective in inducing AML. However, another result was completely unexpected; the irradiated mice had a very high incidence of hepatocellular carcinoma (HCC), approximately 50%. It was unexpected because acute exposures are ineffective in increasing HCC incidence above background. This is a potential important finding for setting exposure limits because it supports the concept of an 'inverse dose rate effect' for some tumor types. That is, for the development of some tumor types low dose rate exposures carry greater risks than acute exposures

  3. Radiation Leukemogenesis at Low Dose Rates

    Energy Technology Data Exchange (ETDEWEB)

    Weil, Michael; Ullrich, Robert

    2013-09-25

    The major goals of this program were to study the efficacy of low dose rate radiation exposures for the induction of acute myeloid leukemia (AML) and to characterize the leukemias that are caused by radiation exposures at low dose rate. An irradiator facility was designed and constructed that allows large numbers of mice to be irradiated at low dose rates for protracted periods (up to their life span). To the best of our knowledge this facility is unique in the US and it was subsequently used to study radioprotectors being developed for radiological defense (PLoS One. 7(3), e33044, 2012) and is currently being used to study the role of genetic background in susceptibility to radiation-induced lung cancer. One result of the irradiation was expected; low dose rate exposures are ineffective in inducing AML. However, another result was completely unexpected; the irradiated mice had a very high incidence of hepatocellular carcinoma (HCC), approximately 50%. It was unexpected because acute exposures are ineffective in increasing HCC incidence above background. This is a potential important finding for setting exposure limits because it supports the concept of an 'inverse dose rate effect' for some tumor types. That is, for the development of some tumor types low dose rate exposures carry greater risks than acute exposures.

  4. Background gamma terrestrial dose rate in Nigerian functional coal mines

    International Nuclear Information System (INIS)

    Measurements of the background terrestrial gamma radiation dose rates at different indoor and outdoor locations on the surfaces of Okpara underground and Okaba open cast mines in Nigeria were made. Two duly calibrated low-level gamma survey metres were held 1 m above the ground surface for these measurements. Measurements were also made at various locations inside the mine tunnel at the Okpara mine. Results indicate that the indoor background gamma radiation is comparable for both mining environments. The mean outdoor gamma dose rate determined for the Okaba mining environment is 10.4 nGy h-1 as against 11.7 nGy h-1 for Okpara. The ranges are 8.5-16.5 nGy h-1 for the Okpara measurements and 7.5-14.0 nGy h-1 for Okaba. Thus, the outdoor gamma dose rates appear to be generally lower at the Okaba open cast mine than at Okpara. The indoor dose rate values range from 11.0 to 17.0 nGy h-1 in both environments. These indoor measurements have nearly the same mean values 14.4 and 14.5 nGy h-1 for Okpara and Okaba environments, respectively. The indoor to outdoor dose rate ratio is 1.2 for Okpara and 1.4 for Okaba. These values are in consonance with the corresponding ratio given in literature. Dose rate measurements inside the mine tunnel at the Okpara mine are higher than the surface indoor measurements ranging from 13.5 to 20.5 nGy h-1 with a mean of 16.5 nGy h-1. The higher dose rate values measured in the mine tunnel are attributable to the concentration of radon in the 'closed' environment of the mine tunnel. (authors)

  5. Terrestrial gamma dose rate, radioactivity and radiological hazards in the rocks of an elevated radiation background in Juban District, Ad Dali' Governorate, Yemen.

    Science.gov (United States)

    Abdurabu, Wedad Ali; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Heryansyah, Arien; Alnhary, Anees; Fadhl, Shadi

    2016-03-01

    This study aims to evaluate natural radiation and radioactivity in the rock and to assess the corresponding health risk in a region of elevated background radiation in Juban District, Ad Dali' Governorate, Yemen. The mean external gamma dose rate was 374 nGy h(-1) which is approximately six times the world average. The measured results were used to compute annual effective dose equivalent, collective effective dose and excess lifetime cancer risk, which are 2.298 mSv, 61.95 man Sv y(-1) and 8.043  ×  10(-3), respectively. Rocks samples from different geological formations were analyzed for quantitative determination of (226)Ra, (232)Th and (40)K. The specific activity of the rocks samples ranges from 7  ±  1 Bq Kg(-1) to 12 513  ±  329 Bq Kg(-1) for (232)Th, from 6  ±  1 Bq kg(-1) to 3089  ±  74 Bq kg(-1) for (226)Ra and 702  ±  69 Bq kg(-1) to 2954  ±  285 Bq kg(-1) for (40)K. (232)Th is the main contributor to gamma dose rate from the rock samples. Indicators of radiological health impact, radium equivalent activity and external hazard index are 3738 Bq kg(-1) and 10.10, respectively. The mean external hazard index was ten times unity in the studied locations in Juban District, which is higher than the recommended value. PMID:26909670

  6. Background internal dose rates of earthworm and arthropod species in the forests of Aomori, Japan

    International Nuclear Information System (INIS)

    In this study, we measured the concentrations of several natural radionuclides in samples of one earthworm species and 11 arthropod species collected from four coniferous forests in Rokkasho, Aomori Prefecture, Japan, and we assessed the background internal radiation dose rate for each species. Dose rates were calculated by using the radionuclide concentrations in the samples and dose conversion coefficients obtained from the literature. The mean internal dose rate in the earthworm species was 0.28 μGy h-1, and the mean internal dose rates in the arthropod species ranged between 0.036 and 0.69 μGy h-1. (author)

  7. Radiation shielding and dose rate distribution for the building of the high dose rate accelerator

    International Nuclear Information System (INIS)

    A high dose rate electron accelerator was established at Osaka Laboratory for Radiation Chemistry, Takasaki Establishment, JAERI in the fiscal year of 1975. This report shows the fundamental concept for the radiation shielding of the accelerator building and the results of their calculations which were evaluated through the model experiments. After the construction of the building, the leak radiation was measured in order to evaluate the calculating method of radiation shielding. Dose rate distribution of X-rays was also measured in the whole area of the irradiation room as a data base. (author)

  8. ISFSI site boundary radiation dose rate analyses

    International Nuclear Information System (INIS)

    Across the globe nuclear utilities are in the process of designing and analysing Independent Spent Fuel Storage Installations (ISFSI) for the purpose of above ground spent-fuel storage primarily to mitigate the filling of spent-fuel pools. Using a conjoining of discrete ordinates transport theory (DORT) and Monte Carlo (MCNP) techniques, an ISFSI was analysed to determine neutron and photon dose rates for a generic overpack, and ISFSI pad configuration and design at distances ranging from 1 to ∼1700 m from the ISFSI array. The calculated dose rates are used to address the requirements of 10CFR72.104, which provides limits to be enforced for the protection of the public by the NRC in regard to ISFSI facilities. For this overpack, dose rates decrease by three orders of magnitude through the first 200 m moving away from the ISFSI. In addition, the contributions from different source terms changes over distance. It can be observed that although side photons provide the majority of dose rate in this calculation, scattered photons and side neutrons take on more importance as the distance from the ISFSI is increased. (authors)

  9. Review of low dose-rate epidemiological studies and biological mechanisms of dose-rate effects on radiation induced carcinogenesis

    International Nuclear Information System (INIS)

    Radiation protection system adopts the linear non-threshold model with using dose and dose-rate effectiveness factor (DDREF). The dose-rate range where DDREF is applied is below 100 mGy per hour, and it is regarded that there are no dose-rate effects at very low dose rate, less than of the order of 10 mGy per year, even from the biological risk evaluation model based on cellular and molecular level mechanisms for maintenance of genetic integrity. Among low dose-rate epidemiological studies, studies of residents in high natural background areas showed no increase of cancer risks at less than about 10 mGy per year. On the other hand, some studies include a study of the Techa River cohort suggested the increase of cancer risks to the similar degree of Atomic bomb survivor data. The difference of those results was supposed due to the difference of dose rate. In 2014, International Commission on Radiological Protection opened a draft report on stem cell biology for public consultations. The report proposed a hypothesis based on the new idea of stem cell competition as a tissue level quality control mechanism, and suggested that it could explain the dose-rate effects around a few milligray per year. To verify this hypothesis, it would be needed to clarify the existence and the lowest dose of radiation-induced stem cell competition, and to elucidate the rate of stem cell turnover and radiation effects on it. As for the turnover, replenishment of damaged stem cells would be the important biological process. It would be meaningful to collect the information to show the difference of dose rates where the competition and the replenishment would be the predominant processes. (author)

  10. Radiation dose rates from UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Friend, P.J. [Urenco, Capenhurst (United Kingdom)

    1991-12-31

    This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiation dose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiation dose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

  11. Characteristics of radiation dose rate distribution in living environment

    International Nuclear Information System (INIS)

    Natural radiation survey has been performed to characterize the gamma and cosmic ray dose rate distribution in living environment. Various places/environments which we encounter in our daily life were measured with high precision dose rate meter equipped with a pulse height spectrum-to-dose rate converter and a 7.6 cm diameter spherical NaI (Tl) scintillation detector. Several aspects of dose rate distribution have been found through these data; typical and interesting examples are as follows. (1) Gamma ray dose rates were measured inside and outside wooden houses in snowy season and in snowless season to see the effect of snow cover to the diminution of terrestrial gamma ray dose rate. The snow cover turned to be less effective inside a house than outside for the diminution of gamma ray dose rate. (2) Gamma ray dose rates were measured in a 2-storied concrete residence during its construction. The dose rate increased with progressing the construction, which implies that the indoor gamma ray dose rate depends not only on the building material but also on the building structure, that is the solid angle to the natural gamma ray sources such as the floor, ceiling and walls. (3) Continuous measurement was performed while a person made a business trip to Tokyo. Both gamma and cosmic ray dose rate showed a marked variation from place to place, which was found to be caused by the change of environmental conditions such as the nature and geometrical arrangement of the surrounding materials. Based on these data it was known that the gamma ray dose rate generally shows upward tendency and the cosmic ray dose rate downward in artificial environment compared with natural environment. (author)

  12. Background internal dose rates of earthworm and arthropod species in the forests of Aomori, Japan

    International Nuclear Information System (INIS)

    We measured naturally occurring radionuclides in samples from an earthworm species and 11 arthropod species collected in coniferous forests in Rokkasho, Aomori, Japan, to assess background internal radiation dose rates. The rates were calculated from the measured concentrations of the radionuclides and dose coefficients from the literature. The mean internal dose rate of composite earthworm samples was 0.35 μGy h-1, whereas the mean dose rates of the arthropod samples ranged from 36 nGy h-1 to 0.79 μGy h-1. Polonium-210 was the radionuclide with the highest contribution to the internal dose rate for all the species, except the longhorn beetle. (author)

  13. Dose Rate of Environmental Gamma Radiation in Java Island

    International Nuclear Information System (INIS)

    The dose rate Monitoring of environmental gamma radiation at some locations in Java Island in the year 2005 / 2006 has been carried out. The dose rate measurement of gamma radiation is carried out by using the peripheral of Portable Gamma of Ray Spectrometer with detector of NaI(Tl), Merck Exploranium, Model GR-130- MINISPEC, while to determine its geographic position is used by the GPS (Global Positioning System), made in German corporation of GPS III Plus type. The division of measurement region was conducted by dividing Java Island become 66 parts with same distance, except in Jepara area that will built PLTN (Nuclear Energy Power), distance between measurement points is more closed. The results of dose rate measurement are in 66 locations in Java Island the range of (19.24 ± 4.05) nSv/hour until (150.78 ± 12.26) nSv/hour with mean (51.93 ± 36.53) nSv/h. The lowest dose rate was in location of Garut, while highest dose rate was in Ujung Lemah Abang, Jepara location. The data can be used for base line data of dose rate of environmental gamma radiation in Indonesia, specially in Java Island. The mean level of gamma radiation in Java monitoring area (0.46 mSv / year) was still lower than worldwide average effective dose rate of terrestrial gamma rays 0.5 mSv / year (report of UNSCEAR, 2000). (author)

  14. Car-borne survey of natural background gamma dose rate in Canakkale region (Turkey)

    International Nuclear Information System (INIS)

    Natural background gamma radiation was measured along roads in the environs of Canakkale region by using a car-borne spectrometer system with a plastic gamma radiation detector. In addition, activity concentrations of 238U, 226Ra, 232Th and 40K in soil samples from the Canakkale region were determined by using a gamma spectrometer with an HPGe detector. A total of 92 856 data of the background gamma dose rate were collected for the Canakkale region. The background gamma dose rate of the Canakkale region was mapped using ArcGIS software, applying the geostatistical inverse distance-weighted method. The average and population-weighted average of the gamma dose are 55.4 and 40.6 nGy h-1, respectively. The corresponding average annual effective dose to the public ranged from 26.6 to 96.8 μSv. (authors)

  15. Health effect of low dose/low dose rate radiation

    International Nuclear Information System (INIS)

    The clarified and non-clarified scientific knowledge is discussed to consider the cause of confusion of explanation of the title subject. The low dose is defined roughly lower than 200 mGy and low dose rate, 0.05 mGy/min. The health effect is evaluated from 2 aspects of clinical symptom/radiation hazard protection. In the clinical aspect, the effect is classified in physical (early and late) and genetic ones, and is classified in stochastic (no threshold value, TV) and deterministic (with TV) ones from the radioprotection aspect. Although the absence of TV in the carcinogenic and genetic effects has not been proved, ICRP employs the stochastic standpoint from the safety aspect for radioprotection. The lowest human TV known now is 100 mGy, meaning that human deterministic effect would not be generated below this dose. Genetic deterministic effect can be observable only in animal experiments. These facts suggest that the practical risk of exposure to <100 mGy in human is the carcinogenesis. The relationship between carcinogenic risk in A-bomb survivors and their exposed dose are found fitted to the linear no TV model, but the epidemiologic data, because of restriction of subject number analyzed, do not always mean that the model is applicable even below the dose <100 mGy. This would be one of confusing causes in explanation: no carcinogenic risk at <100 mGy or risk linear to dose even at <100 mGy, neither of which is scientifically conclusive at present. Also mentioned is the scarce risk of cancer in residents living in the high background radiation regions in the world in comparison with that in the A-bomb survivors exposed to the chronic or acute low dose/dose rate. Molecular events are explained for the low-dose radiation-induced DNA damage and its repair, gene mutation and chromosome aberration, hypothesis of carcinogenesis by mutation, and non-targeting effect of radiation (bystander effect and gene instability). Further researches to elucidate the low dose

  16. Low doses effects and gamma radiations low dose rates

    International Nuclear Information System (INIS)

    This expose wishes for bringing some definitions and base facts relative to the problematics of low doses effects and low dose rates effects. It shows some already used methods and some actual experimental approaches by focusing on the effects of ionizing radiations with a low linear energy transfer. (N.C.)

  17. High dose rate interstitial radiation for tongue cancer

    International Nuclear Information System (INIS)

    From April 1992 through March 1995, 38 patients with T1-2N0 tongue cancer were treated with high dose rate (HDR) or low dose rate (LDR) brachytherapy alone. Three year local control rates of HDR and LDR groups were 94% and 90%, respectively. Treatment results and complication of HDR brachytherapy were almost the same as those of LDR brachytherapy. At the same period, 11 patients with T1-2N0-2 tongue cancer were treated with external radiation and HDR brachytherapy. Three year local control rate was 90%. HDR brachytherapy have some advantages compared with LDR brachytherapy. (author)

  18. Problems of dose rate in radiation protection regulation

    International Nuclear Information System (INIS)

    Some modern problems of Radiation Safety Standards are discussed. It is known that Standards are based on the Linear-Non-Threshold Concept (LNTC) of radiation risk, which is now called by many experts as conservative. It is thought it is necessary to include in the Standards such factor as dose rate or duration of irradiation. Some model of effects of radiation exposure with taking into account the reparation of cell damage is presented. The practical method for assessment of effects of duration of irradiation on detriments is proposed.(author)

  19. Radiation safety program in a high dose rate brachytherapy facility

    International Nuclear Information System (INIS)

    The use of remote afterloading equipment has been developed to improve radiation safety in the delivery of treatment in brachytherapy. Several accidents, however, have been reported involving high dose-rate brachytherapy system. These events, together with the desire to address the concerns of radiation workers, and the anticipated adoption of the International Basic Safety Standards for Protection Against Ionizing Radiation (IAEA, 1996), led to the development of the radiation safety program at the Department of Radiotherapy, Jose R. Reyes Memorial Medical Center and at the Division of Radiation Oncology, St. Luke's Medical Center. The radiation safety program covers five major aspects: quality control/quality assurance, radiation monitoring, preventive maintenance, administrative measures and quality audit. Measures for evaluation of effectiveness of the program include decreased unnecessary exposures of patients and staff, improved accuracy in treatment delivery and increased department efficiency due to the development of staff vigilance and decreased anxiety. The success in the implementation required the participation and cooperation of all the personnel involved in the procedures and strong management support. This paper will discuss the radiation safety program for a high dose rate brachytherapy facility developed at these two institutes which may serve as a guideline for other hospitals intending to install a similar facility. (author)

  20. Radiological mapping of Kelantan, Malaysia, using terrestrial radiation dose rate.

    Science.gov (United States)

    Garba, Nuraddeen Nasiru; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Sanusi, Syazwan Mohd; Gabdo, Hamman Tukur

    2016-06-01

    Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3. PMID:26540360

  1. Car-borne survey of natural background gamma dose rate in Çanakkale region, Turkey.

    Science.gov (United States)

    Turhan, S; Arıkan, I H; Oğuz, F; Özdemir, T; Yücel, B; Varinlioğlu, A; Köse, A

    2012-01-01

    Natural background gamma radiation was measured along roads in the environs of Çanakkale region by using a car-borne spectrometer system with a plastic gamma radiation detector. In addition, activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples from the Çanakkale region were determined by using a gamma spectrometer with an HPGe detector. A total of 92,856 data of the background gamma dose rate were collected for the Çanakkale region. The background gamma dose rate of the Çanakkale region was mapped using ArcGIS software, applying the geostatistical inverse distance-weighted method. The average and population-weighted average of the gamma dose are 55.4 and 40.6 nGy h⁻¹, respectively. The corresponding average annual effective dose to the public ranged from 26.6 to 96.8 µSv. PMID:21362693

  2. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia

    International Nuclear Information System (INIS)

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h−1 to 500 nGy h−1. The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h−1. This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h−1 (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation. - Highlights: • A methodology is presented to reduce terrestrial gamma dose rate field survey. • Geological background of acid intrusive of granitic type has the highest dose rates. • The mean dose rate is 2 times higher than the world average. • Isodose map of terrestrial gamma radiation for Selangor, Kuala Lumpur and Putrajaya was produced

  3. Evaluation of fluctuation of equivalent dose rate due to radionuclide radiation in buildings

    International Nuclear Information System (INIS)

    Radionuclide gamma radiation in building materials twist natural gamma field, therefore, dosimetry investigation of ionizing radiation of natural radionuclides was carried out near various building constructions. It was detected that equivalent dose rate of natural radionuclides increases exponentially (this empirical dependence stays in force to 10-15 meters from a building) while approaching a building under investigation. It was measured that buildings increase ionizing radiation approximately 1,5-2 times. Wooden buildings are an exception. They change natural background to 5 %. The values of equivalent dose rate in buildings are distributed according to Gaussian distribution. The measured equivalent dose rate is 1,5 times smaller in wooden houses then in block, silicate and ceramic bricks houses. (author)

  4. Monitoring of radiation dose rates around a clinical nuclear medicine site

    International Nuclear Information System (INIS)

    The monitoring of radiation dose around the nuclear medicine site is an important study issue. In this study, TLD-100H radiation dosimeters were used to measure the ambient radiation dose rates around a clinical nuclear medicine site in order to investigate the latent hot zones of radiation exposure. Results of this study showed that the radiation doses measured from all piping and storage systems were comparable to the background dose. A relatively high dose was observed at the single bend point of waste water piping of the PET/CT. Another important finding was the unexpected high dose rates observed at the non-restricted waiting area (NRWA) of SPECT. To conclude, this study provides useful information for further determination of an appropriate dose reduction strategy to achieve the ALARA principle in a clinical nuclear medicine site. - Highlights: • Observed unexpected high dose rates in the non restricted waiting area. • Provides useful Radiation Dose Rates information in nuclear medicine radioactive waste water pipeline system. • Provide TLD setup method in environmental radiation dose evaluate

  5. Assessment of Environmental Gamma Radiation Dose Rate in Ardabil and Sarein in 2009

    Directory of Open Access Journals (Sweden)

    M Alighadri

    2011-10-01

    Full Text Available Background and Objectives: Gamma rays, the most energetic photons within the any other wave in the electromagnetic spectrum, pose enough energy to form charged particles and adversely affect human health. Provided that the external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined, environmental gamma dose rate and corresponding annual effective dose were determined in the cities of Ardabil and Sar Ein.Materials and Methods: Outdoor environmental gamma dose rates were measured using an Ion Chamber Survey Meter in 48 selected locations (one in city center and the remaining in cardinal and ordinal directions in Ardabil and Sar Ein. Ten more locations were monitored along the hot springs effluent in Sar Ein. Measurements of gamma radiation dose rate were performed at 20 and 100 cm above the ground for a period of one hour.Results: Average outdoor environmental gamma dose rate were determined as 265, 219, and 208  for Ardabil, Sar Ein, and along the hot spring effluent, respectively. The annual affective dose for Ardabil and Sar Ein residents were estimated to be 1.45 and 1.39 mSv, respectively.Conclusion: Calculated annual effective dose of 1.49 and 1.35 are appreciably higher than the population weighted average exposure to environmental gamma radiation worldwide and that analysis of soil content to different radionuclide is suggested.

  6. Recommended de minimis radiation dose rates for Canada

    International Nuclear Information System (INIS)

    A de minimis dose or dose rate as used in this report represents a level of risk which is generally accepted as being of no significance to an individual, or in the case of a population, of no significance to society. The doses corresponding to these levels of risk are based on current scientific knowledge. Dose rates recommended in this report are as follows: a de minimis individual dose rate of 10 μSv a-1, based on a risk level that would generally be regarded as negligible in comparison with other risks; and a de minimis collective dose rate of 1 person-Sv a-1, based on an imperceptible increase above the normal incidences of cancer and genetic defects in the exposed population. The concept of de minimis is to be distinguished from 'exempt from regulation' (below regulatory concern). The latter involves broader social and economic factors which encompass but are not limited to the purely risk-based factors addressed by the de minimis dose. De minimis is one of the factors that determine the exemption of sources or practices that may result in doses below or above the de minimis level. Although these de minimis dose rates should be considered in developing criteria and guidelines for deriving quantities and concentrations of radioactive substances that may be exempted from regulation, this document is only concerned with establishing de minimis dose rates, not with exempting sources and practices

  7. Distribution of terrestrial gamma radiation dose rate in the eastern coastal area of Odisha, India.

    Science.gov (United States)

    Gusain, G S; Rautela, B S; Sahoo, S K; Ishikawa, T; Prasad, G; Omori, Y; Sorimachi, A; Tokonami, S; Ramola, R C

    2012-11-01

    Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides (226)Ra, (232)Th and (40)K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of (226)Ra, (232)Th and (40)K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of (226)Ra, (232)Th and (40)K ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view. PMID:22874894

  8. Distribution of terrestrial gamma radiation dose rate in the eastern coastal area of Odisha, India

    International Nuclear Information System (INIS)

    Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides 226Ra, 232Th and 40K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h-1, with an average of 230 nGy h-1. During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of 226Ra, 232Th and 40K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of 226Ra, 232Th and 40K ranged from 15.6 to 69 Bq kg-1 with an average of 46.7 Bq kg-1, from 28.9 to 973 Bq kg-1 with an average of 250 Bq kg-1 and from 139 to 952 Bq kg-1 with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view. (authors)

  9. Vertical distribution of radiation dose rates in the water of a brackish lake in Aomori Prefecture, Japan

    International Nuclear Information System (INIS)

    Seasonal radiation dose rates were measured with glass dosemeters housed in watertight cases at various depths in the water of Lake Obuchi, a brackish lake in Aomori Prefecture, Japan, during fiscal years 2011-2013 to assess the background external radiation dose to aquatic biota in the lake. The mean radiation dose in the surface water of the lake was found to be 27 nGy h-1, which is almost the same as the absorption dose rate due to cosmic ray reported in the literature. Radiation dose rates decreased exponentially with water depth down to a depth of 1 m above the bottom sediment. In the water near the sediment, the dose rate increased with depth owing to the emission of γ-rays from natural radionuclides in the sediment. (authors)

  10. Dose-rate effect for DNA damage induced by ionizing radiation in human tumor cells

    International Nuclear Information System (INIS)

    The effect of dose rate on clonogenic cell survival and DNA double-strand breaks (DSBs) has been examined in a human bladder carcinoma cell line, RT112, treated with ionizing radiation. Cell survival changed markedly over the range of dose rates used (0.01-1.28 Gy/min) with the curves becoming shallower and straighter as the dose rate was lowered. Similarly, the number of DSBs measured by pulsed-field gel electrophoresis (PFGE) immediately after irradiation varied with dose rate. Fewer DSBs were detectable after low-dose-rate irradiation. However, when a 4-h repair period was allowed after irradiation, cells treated at all dose rates exhibited approximately the same amount of damage. The final level of unrejoined DSBs, as detected by PFGE, therefore does not correlate with cell survival at different dose rates. 16 refs., 2 figs

  11. MONTEC, an interactive fortran program to simulate radiation dose and dose-rate responses of populations

    International Nuclear Information System (INIS)

    The computer program MONTEC was written to simulate the distribution of responses in a population whose members are exposed to multiple radiation doses at variable dose rates. These doses and dose rates are randomly selected from lognormal distributions. The individual radiation responses are calculated from three equations, which include dose and dose-rate terms. Other response-dose/rate relationships or distributions can be incorporated by the user as the need arises. The purpose of this documentation is to provide a complete operating manual for the program. This version is written in FORTRAN-10 for the DEC system PDP-10

  12. Mitochondrial DNA deletion and aging induced by low dose rate of radiation in mice

    International Nuclear Information System (INIS)

    Mitochondrial DNA (mtDNA) is a closed circular DNA molecule and more than 100 copies are present in a cell. Deletion mutation of mtDNA accumulates with aging and can be a suitable marker for estimating biological effects on radiation-induced mutation in mice. The mice life span study in the Institute for Environmental Sciences suggests that low dose rate of radiation might accelerate aging in mice prolongly irradiated by 137Cs γ-rays (20 mGy/day for 400 days). To know the relationships between low dose rate irradiation, aging and mutation, we observed deletion mutations of mtDNA from mice irradiated by 137Cs γ-rays (20 mGy/day) for different dates. The real-time fluorescence PCR method was sensitive enough to determine the relative amount of deletion in several tissues. Age-dependent accumulations of deletion mutations were observed in aged mice (250-700 days). However, a significant increase of deletion mutation related to accumulated dose was not detected in 137Cs γ-ray irradiated mice for 4-12 Gy. These data suggest that the effect of the low dose rate irradiation on mtDNA is within a background level. (author)

  13. A method for radiobiological investigations in radiation fields with different LET and high dose rates

    International Nuclear Information System (INIS)

    For investigations: 1. Performed in the field of radiobiology with different LET-radiation and a relatively high background dose rate of one component (e.g. investigations with fast and intermediate reactor neutrons) 2. Concerning radiation risk studies within a wide range 3. Of irradiations, covering a long time period (up to 100 days) a test system is necessary which on the one hand makes it possible to analyze the influence of different LET radiation and secondly shows a relative radiation resistant behaviour and allows a simple cell cycle regulation. A survey is given upon the installed device of a simple cell observation method, the biological test system used and the analysis of effects caused by dose, repair and LET. It is possible to analyze the behaviour of the nonsurvival cells and to demonstrate different reactions of the test parameters to the radiation of different LET. (author)

  14. BZNF-1 wide range pocket intelligent radiation dose rate meter

    International Nuclear Information System (INIS)

    The functional performance, operational principles and technical means as well as the experimental results of the packet intelligent radiation dose ratemeter using G-M detector and a single chip microcomputer are described

  15. Survey of environmental radiation dose rates in Kyoto and Shiga prefectures, Japan

    International Nuclear Information System (INIS)

    We have measured environmental radiation dose rates in several Prefectures, such as Ai chi Prefecture, Gifu Prefecture, and Mie Prefecture, in central Japan. Recently, we measured the environmental radiation dose rates in Kyoto and Shiga Prefectures that are also located in central Japan with a car-borne survey system. At the time of measurement, Kyoto Prefecture (area: 4,613 km2) had a total of 36 districts, and Shiga Prefecture (area: 3,387 km2) a total of 26. Terrestrial gamma ray dose rates and secondary cosmic ray dose rates were measured by a 2 inches ψ x 2 inches NaI(Tl) scintillation counter and a handy-type altimeter (GPS eTrex Legend by Gamin), respectively. The following factors were taken into consideration the shielding effect of the car body, the effect of the road pavement, radon progeny borne by precipitation, and increases in tunnels and near the walls. Terrestrial gamma ray dose rates in Kyoto and Shiga Prefectures were estimated to be 51.7 ± 6.0 n Gy/h (district average: 52.4 ± 4.7 n Gy/h), 52.2 ± 10.5 n Gy/h (district average: 51.9 ± 8.1 n Gy/h), respectively. Secondary cosmic ray dose rates in Kyoto and Shiga Prefectures were 30.0 ± 0.6 n Gy/h (district average: 29.9 ±0.3 n Gy/h), 30.1 ± 0.3 n Gy/h (district average: 30.0 ± 0.2 n Gy/h), respectively. The environmental radiation dose rates due to the sum dose rates of terrestrial gamma ray and secondary cosmic ray in Kyoto and Shiga Prefectures were 81.7 ± 6.2 n Gy/h (district average: 82.3 ± 4.8 n Gy/h), 82.3 ± 10.6 n Gy/h (district average: 82.0 ± 8.1 n Gy/h), respectively. We confirmed that the environmental radiation dose rates in Kyoto and Shiga Prefectures mainly depended on the change of the terrestrial gamma ray dose rates, since the secondary cosmic ray dose rates had little change. Therefore, radiation dose-rate maps of the terrestrial gamma rays as well as maps of the environmental radiation dose-rate were drawn. (author)

  16. Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice

    Energy Technology Data Exchange (ETDEWEB)

    Ware, J.H.; Rusek, A.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X.S.; Kennedy, A.R.

    2010-09-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

  17. Solar Modulation of Inner Trapped Belt Radiation Dose Rate

    Science.gov (United States)

    Diaz, Abel

    2002-03-01

    The two steady sources of radiation in low Earth orbit are the inner trapped-belt and galactic cosmic radiation (GCR), which present a very significant hazard to the astronauts and flight equipment electronics. The fluxes of GCR and inner trapped-belt particles at a fixed altitude are modulated by solar activity. They decrease with increasing solar activity in general. The mechanism of these two sources of radiation are, however, very different. In this project we shall be concerned with modeling the inner trapped-belt protons. The existing trapped-belt models, namely AP-8 is based on data acquired prior to 1970 during solar cycle 20 with relatively low solar flux. These models describe the environment at solar minimum and solar maximum only. Cycles 21 and 22 were much larger, but no valid radiation model exists for such large values. Moreover, the existing models like AP-8, CRRESPRO, and GOST describe the flux to an accuracy of a factor of two to five. There is clear need to accurately predict radiation exposure of astronauts and equipment at all times between the solar minimum and solar maximum, not only on the short duration Space Shuttle flights, but also the longer term stay onboard the International Space Station. In our approach we are taking into account some important parameters, which are responsible for energy losses of protons within the belts. These energy losses are primarily to electrons and by collisions to atmospheric nuclei. Accordingly the atmospheric density dependence at a certain altitude during a specific solar activity is an important parameter that needs to be accurately incorporated into a realistic model. We are involved in developing such a model, which would enable us to predict the radiation exposure for all occasions.

  18. Effects of high dose rate gamma radiation on survival and reproduction of Biomphalaria glabrata

    International Nuclear Information System (INIS)

    Ionizing radiations are known as mutagenic agents, causing lethality and infertility. This characteristic has motivated its application on animal biological control. In this context, the freshwater snail Biomphalaria glabrata can be considered an excellent experimental model to study effects of ionizing radiations on lethality and reproduction. This work was designed to evaluate effects of 60Co gamma radiation at high dose rate (10.04 kGy/h) on B. glabrata. For this purpose, adult snails were selected and exposed to doses ranging from 20 to 100 Gy, with 10 Gy intervals; one group was kept as control. There was not effect of dose rate in the lethality of gamma radiation; the value of 64,3 Gy of LD50 obtained in our study was similar to that obtained by other authors with low dose rates. Nevertheless, our data suggest that there was a dose rate effect in the reproduction. On all dose levels, radiation improved the production of embryos for all exposed individuals. However, viability indexes were below 6% and, even 65 days after irradiation, fertility was not recovered. These results are not in agreement with other studies using low dose rates. Lethality was obtained in all groups irradiated, and the highest doses presented percentiles of dead animals above 50%. The results demonstrated that doses of 20 and 30 Gy were ideal for population control of B. glabrata. Further studies are needed; nevertheless, this research evidenced great potential of high dose rate gamma radiation on B. glabrata reproductive control. (author)

  19. Effects of high dose rate gamma radiation on survival and reproduction of Biomphalaria glabrata

    Energy Technology Data Exchange (ETDEWEB)

    Cantinha, Rebeca S.; Nakano, Eliana [Instituto Butantan, Sao Paulo, SP (Brazil). Lab. de Parasitologia], e-mail: rebecanuclear@gmail.com, e-mail: eliananakano@butantan.gov.br; Borrely, Sueli I. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Centro de Tecnologia das Radiacoes], e-mail: sborrely@ipen.br; Amaral, Ademir; Melo, Ana M.M.A. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia (GERAR)], e-mail: amaral@ufpe.br; Silva, Luanna R.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia. Lab. de Radiobiologia], e-mail: amdemelo@hotmail.com, e-mail: luannaribeiro_lua@hotmail.com

    2009-07-01

    Ionizing radiations are known as mutagenic agents, causing lethality and infertility. This characteristic has motivated its application on animal biological control. In this context, the freshwater snail Biomphalaria glabrata can be considered an excellent experimental model to study effects of ionizing radiations on lethality and reproduction. This work was designed to evaluate effects of {sup 60}Co gamma radiation at high dose rate (10.04 kGy/h) on B. glabrata. For this purpose, adult snails were selected and exposed to doses ranging from 20 to 100 Gy, with 10 Gy intervals; one group was kept as control. There was not effect of dose rate in the lethality of gamma radiation; the value of 64,3 Gy of LD{sub 50} obtained in our study was similar to that obtained by other authors with low dose rates. Nevertheless, our data suggest that there was a dose rate effect in the reproduction. On all dose levels, radiation improved the production of embryos for all exposed individuals. However, viability indexes were below 6% and, even 65 days after irradiation, fertility was not recovered. These results are not in agreement with other studies using low dose rates. Lethality was obtained in all groups irradiated, and the highest doses presented percentiles of dead animals above 50%. The results demonstrated that doses of 20 and 30 Gy were ideal for population control of B. glabrata. Further studies are needed; nevertheless, this research evidenced great potential of high dose rate gamma radiation on B. glabrata reproductive control. (author)

  20. Dose rate and fractionation: Relative importance in radiation for bone marrow transplantation

    International Nuclear Information System (INIS)

    The optimal dose rate and fractionation schedules for total body irradiation (TBI) in bone marrow transplantation (BMT) are presently unknown. This study compares several fractionation and dose rate schedules that are currently in clinical use. C/sub 3/H/HeJ were given TBI and the bone marrow survival fraction was calculated using the CFU's assay. Irradiation was given as low dose rate (LDR) at 5 cGy/min or high dose rate (HDR) at 80 cGy/min, in single fraction (SF) and fractionated (FX) regimens. These results indicate no increase in survival for the normal bone marrow stem cells with fractionation either at high or low dose-rates. In fact, fractionation seemed to decrease the bone marrow survival over single fraction radiation

  1. Background and anthropogenic radionuclide derived dose rates to freshwater ecosystem - Nuclear power plant cooling pond - Reference organisms

    International Nuclear Information System (INIS)

    The radiological assessment of non-human biota to demonstrate protection is now accepted by a number of international and national bodies. Therefore, it is necessary to develop a scientific basis to assess and evaluate exposure of biota to ionizing radiation. Radionuclides from the Ignalina Nuclear Power Plant (Lithuania) were discharged into Lake Druksiai cooling pond. Additional radionuclide migration and recharge to this lake from a hypothetical near-surface, low-level radioactive waste disposal, to be situated 1.5 km from the lake, had been simulated using RESRAD-OFFSITE code. This paper uses ERICA Integrated Approach with associated tools and databases to compare the radiological dose to freshwater reference organisms. Based on these data, it can be concluded that background dose rates to non-human biota in Lake Druksiai far exceed those attributable to anthropogenic radionuclides. With respect the fishery and corresponding annual committed effective human dose as a result of this fish consumption Lake Druksiai continues to be a high-productivity water body with intensive angling and possible commercial fishing. - Highlights: → Dose rates to the reference organisms are lower than expected from the background radioactivity. → Pelagic fish part of adult human annual committed effective dose would be as small as a few μSv y-1. → With respect the fishery Lake Druksiai continues to be a high-productivity water body.

  2. Estimation of radiation dose rate in new polypropylene strainer in primary heat transport system

    International Nuclear Information System (INIS)

    Heavy water is used in Primary Heat Transport system at Dhruva research reactor. It contains suspended and ionic impurities, therefore it is required to purify heavy water for removal of impurities and to maintain grade of heavy water. For enhancing performance of purification system testing of new polypropylene filters is planned for removal of suspended impurities at flow rate of 400 lit/min. Physical properties of polypropylene changes after exposure to radiation after radiation dose of 1.0E+05 Gy it becomes brittle. Calculations of beta and gamma radiation dose rate are based on the activity of radionuclides present in heavy water used as main coolant system. Assessment of service life of new filters is carried out by calculating the radiation dose rate to polypropylene filters during in service and radiation dose rate of existing removed stainless steel strainer. (author)

  3. Space Radiation Quality Factors and the Delta Ray Dose and Dose-Rate Reduction Effectiveness Factor.

    Science.gov (United States)

    Cucinotta, Francis A; Cacao, Eliedonna; Alp, Murat

    2016-03-01

    In this paper, the authors recommend that the dose and dose-rate effectiveness factor used for space radiation risk assessments should be based on a comparison of the biological effects of energetic electrons produced along a cosmic ray particles path in low fluence exposures to high dose-rate gamma-ray exposures of doses of about 1 Gy. Methods to implement this approach are described. PMID:26808878

  4. Correlation between indoor radon concentration and dose rate in air from terrestrial gamma radiation in Japan.

    Science.gov (United States)

    Fujimoto, K

    1998-09-01

    A correlation between the indoor radon concentration and dose rate in air from terrestrial gamma radiation is studied using the results of nationwide indoor radon and external exposure surveys, although the surveys were not conducted at the same time nor at the same location. The radon concentration shows a log-normal-like distribution, whereas the terrestrial gamma radiation dose rate in air shows a normal-like distribution. A log-linear scatterplot for each pair of the indoor radon concentration and gamma-ray dose rate in air in each city reveals a clear relationship. The average, maximum, and minimum as well as regression line of radon concentration were found to increase with the gamma-ray dose rate in air. The group in higher quantile of radon concentration shows larger dependence on the gamma-ray dose rate. The rate of increase of radon concentration with the gamma-ray dose rate in air depends on the house structure. The wooden house has a larger rate of increase than the concrete house, and the regression lines cross at high air dose rate. Based on the finding in the present study a certain criterion level of air dose rate could be established and used for an effective survey to find out which houses might require a remedial action in conjunction with other screening tools. The criterion level of air dose rate might be more effective if the level is set for each house structure since the rate of increase of radon concentration depends on house structure. PMID:9721838

  5. Optimum design for the primary cooling system in BWRs to control shutdown radiation dose rate

    International Nuclear Information System (INIS)

    The reduction of radiation dose rate at the time of shutdown is an important task for smoothly performing the regular inspection and maintenance works in nuclear power plants as the number of those plants in operation has increased. Hitachi Ltd. has investigated the industrially applicable measures to reduce dose rate to suppress the exposure dose per year in 1100 MWe class BWR nuclear power plants below 200 Man-Rem. The exposure dose in normal checking works during a regular inspection is regarded to be macroscopically dependent on the dose rate of piping in recirculation system. Thus, it was found that the above target can be achieved by suppressing the dose rate on piping surface to 30 mR/h. For further reduction if iron crud and 60Co ions contributing to the increase of dose rate, in addition to the oxygen injection into the feed water system and the duplicated condensate purification system, the use of corrosion-resistant steel and low cobalt material has been attempted. However, high temperature water to be filtrated can not be passed through the purification system because it employs ion exchange resin. Therefore, the optimum capacity is selected for the purification system in view of the reduction of dose rate and plant thermal efficiency. Hitachi Ltd. recommends the application of this system, considering the evaluation of contribution by the code predicting dose rate increase and estimating economy. The above measures will achieve the exposure dose target of 200 Man-Rem/year. (Wakatsuki, Y.)

  6. INFLUENCE OF DOSE RATE ON THE CELLULAR RESPONSE TO LOW- AND HIGH-LET RADIATIONS

    Directory of Open Access Journals (Sweden)

    Anne-Sophie eWozny

    2016-03-01

    Full Text Available Nowadays, head and neck squamous cell carcinoma (HNSCC treatment failure is mostly explained by loco-regional progression or intrinsic radioresistance. Radiotherapy has recently evolved with the emergence of heavy ion radiations or new fractionation schemes of photon therapy which modify the dose-rate of treatment delivery. The aim of the present study was then to evaluate the in vitro influence of a dose rate variation during conventional radiotherapy or carbon ion hadrontherapy treatment in order to improve the therapeutic care of patient. In this regard, two HNSCC cell lines were irradiated with photons or 72MeV/n carbon ions at a dose rate of 0.5, 2 or 10Gy/min.For both radiosensitive and radioresistant cells, the change in dose rate significantly affected cell survival in response to photon exposure, this variation of radiosensitivity was associated to the number of initial and residual DNA double-strand breaks. By contrast, the dose rate change did not affect neither cell survival nor the residual DNA double-strand breaks after carbon ion irradiation. As a result, the Relative Biological Efficiency at 10% survival increased when the dose rate decreased.In conclusion, in the radiotherapy treatment of HNSCC, it is advised to remain very careful when modifying the classical schemes towards altered-fractionation. At the opposite, as the dose rate does not seem to have any effects after carbon ion exposure, there is less need to adapt hadrontherapy treatment planning during active system irradiation

  7. Effect of different ionizing radiation dose rates on the Staphylococcal enterotoxin in mechanically deboned chicken meat

    International Nuclear Information System (INIS)

    Samples weighing 50g each were prepared from allotments of back with skin MDCM, to the EEB contamination or not (control). Each sample of MDCM contaminated or not with EEB was conditioned in low density polyethylene bag, frozen (-18 ± 1 deg C) for one night in a tunnel and irradiated with gamma rays from 60Co source in this state with doses of 0.0 kGy (control), 1.5 kGy (5.7 kGy.h-1 - higher dose rate, 1.8 kGy.h-1 - intermediary dose rate and 0.6 kGy.h-1 - lower dose rate) and 3.0 kGy (8.4 kGy.h-'1 - higher dose rate, 2.4 kGy.h-1 - intermediary dose rate and 0.6 kGy.h-1 - lower dose rate). Irradiated or non irradiated MDCM samples were processed to the EEB extraction, according to the VIDAS Staph enterotoxin II kit (bioMerieux) manufacturer protocol. The calculation to determinate the MDCM EEB recovery after the sample (control or irradiated) processing were carried out applying the principle of mass balance, along the whole process. Described experiment was performed in triplicate. Results showed that the irradiation process was effective to remove the MDCM EEB, to both 1.5 kGy and 3.0 kGy. According to the expected, doses of 3.0 kGy showed the highest values of MDCM EEB removal. Regarding the effect of dose rate of radiation on the removal of EEB of the MDCM, it could be observed only for samples irradiated with 1.5 kGy radiation dose; in these processing conditions, the highest value of EEB removal was obtained for samples processed with low radiation dose rate. (author)

  8. Induction method of pulse gamma-radiation exposure dose rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Buber, V.B.; Stepanov, V.M.

    1984-01-01

    Induction method of measurement of pulse ..gamma..-radiation exposure dose rate is presented. The measurements are made by charge detectors of induction type. The ..gamma..-radiation dose rate is given versus the Compton current excited by irradiation. The induction method permits to measure the pulse ..gamma..-radiation exposure dose rate up to the values of 10/sup 7/ A/kg with the time resolution of 10/sup -8/ s and with the error not exceeding 20%. The method is slightly subjected to the effect of external conditions, it permits to measure the local and integral radiation characteristics; its application results in quite insignificant distortions of the ..gamma..-flux being measured.

  9. Effects of Proton Radiation Dose, Dose Rate and Dose Fractionation on Hematopoietic Cells in Mice

    OpenAIRE

    Ware, J.H.; Sanzari, J.; Avery, S.; Sayers, C; Krigsfeld, G.; Nuth, M.; Wan, X. S.; Rusek, A.; Kennedy, A R

    2010-01-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05–0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals...

  10. Car-borne survey of terrestrial gamma radiation dose rate in Okinawa Island, Japan

    International Nuclear Information System (INIS)

    The absorbed dose rate in air due to terrestrial gamma radiation in Okinawa-jima, main island of Okinawa prefecture located in the subtropical region of Japan, was estimated at 4967 points on the paved roads by car-borne survey with NaI(Tl) scintillation survey meter. Based on the data that were converted inside into outside the car, the mean, minimum and maximum of the outdoor dose rates on the pavement were calculated to be 19.0, 10.4 and 47.7 nGy h-1, respectively. Also a contour map of the dose rate was made by simple interpolation. In general, it was found that the northern part of the island has higher dose rate compared with the southern one. (author)

  11. Radiation response of industrial materials: Dose-rate and morphology implications

    Science.gov (United States)

    Berejka, Anthony J.

    2007-08-01

    Industrial uses of ionizing radiation mostly rely upon high current, high dose-rate (100 kGy/s) electron beam (EB) accelerators. To a lesser extent, industry uses low dose-rate (2.8 × 10-3 kGy/s) radioactive Cobalt-60 as a gamma source, generally for some rather specific purposes, as medical device sterilization and the treatment of food and foodstuffs. There are nearly nine times as many (∼1400) high current EB units in commercial operation than gamma sources (∼160). However, gamma sources can be easily scaled-down so that much research on materials effects is conducted using gamma radiation. Likewise, laboratories are more likely to have very low beam current and consequently low dose-rate accelerators such as Van de Graaff generators and linear accelerators. With the advent of very high current EB accelerators, X-ray processing has become an industrially viable option. With X-rays from high power sources, dose-rates can be modulated based upon accelerator power and the attenuation of the X-ray by the distance of the material from the X-ray target. Dose and dose-rate dependence has been found to be of consequence in several commercial applications which can employ the use of ionizing radiation. The combination of dose and dose-rate dependence of the polymerization and crosslinking of wood impregnants and of fiber composite matrix materials can yield more economically viable results which have promising commercial potential. Monomer and oligomer structure also play an important role in attaining these desirable results. The influence of morphology is shown on the radiation response of olefin polymers, such as ethylene, propylene and isobutylene polymers and their copolymers. Both controlled morphology and controlled dose-rate have commercial consequences. These are also impacted both by the adroit selection of materials and through the possible use of X-ray processing.

  12. Effect of radiation dose-rate on hematopoietic cell engraftment in adult zebrafish.

    Directory of Open Access Journals (Sweden)

    Tiffany J Glass

    Full Text Available Although exceptionally high radiation dose-rates are currently attaining clinical feasibility, there have been relatively few studies reporting the biological consequences of these dose-rates in hematopoietic cell transplant (HCT. In zebrafish models of HCT, preconditioning before transplant is typically achieved through radiation alone. We report the comparison of outcomes in adult zebrafish irradiated with 20 Gy at either 25 or 800 cGy/min in the context of experimental HCT. In non-transplanted irradiated fish we observed no substantial differences between dose-rate groups as assessed by fish mortality, cell death in the kidney, endogenous hematopoietic reconstitution, or gene expression levels of p53 and ddb2 (damage-specific DNA binding protein 2 in the kidney. However, following HCT, recipients conditioned with the higher dose rate showed significantly improved donor-derived engraftment at 9 days post transplant (p ≤ 0.0001, and improved engraftment persisted at 31 days post transplant. Analysis for sdf-1a expression, as well as transplant of hematopoietic cells from cxcr4b -/- zebrafish, (odysseus, cumulatively suggest that the sdf-1a/cxcr4b axis is not required of donor-derived cells for the observed dose-rate effect on engraftment. Overall, the adult zebrafish model of HCT indicates that exceptionally high radiation dose-rates can impact HCT outcome, and offers a new system for radiobiological and mechanistic interrogation of this phenomenon. Key words: Radiation dose rate, Total Marrow Irradiation (TMI, Total body irradiation (TBI, SDF-1, Zebrafish, hematopoietic cell transplant.

  13. Gamma dose rate due to natural and manmade radiation sources from a nuclear facility in Mexico

    International Nuclear Information System (INIS)

    The environmental external gamma dose rate has been determined at the Mexican Nuclear Research Centre and surrounding communities, located in a forest area. Outdoor direct measurements of external gamma exposure and absorbed dose rates in air were performed using passive integrating thermoluminescent dosimeters. Radiological measurements were also carried out with a portable high pressure ionization chamber. The gamma dose rate was evaluated from data obtained along 10 years measurements. The activity concentrations of 40K, 226Ra, 232Th, 137Cs, and 235U in surface soil samples at sampling sites are also presented. The radionuclide activity concentrations were determined by low background gamma spectrometry with hyper-pure germanium detectors. A site specific lineal model to describe the relationship between the external gamma dose rate and the 226Ra concentration values in the soil is proposed. (author)

  14. The short term effects of Low-dose-rate Radiation on EL4 Lymphoma Cell

    Energy Technology Data Exchange (ETDEWEB)

    Bong, Jin Jong; Kang, Yu Mi; Shin, Suk Chull; Choi, Moo Hyun; Choi, Seung Jin; Kim, Hee Sun [Radiation Health Research Institute, Korea Hydro and Nuclear Power Co., Ltd, Seoul (Korea, Republic of); Lee, Kyung Mi [Global Research Lab, BAERI Institute, Dept. of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of)

    2012-06-15

    To determine the biological effects of low-dose-rate radiation ({sup 137}Cs, 2.95 mGy/h) on EL4 lymphoma cells during 24 h, we investigated the expression of genes related to apoptosis, cell cycle arrest, DNA repair, iron transport, and ribonucleotide reductase. EL4 cells were continuously exposed to low-dose-rate radiation (total dose: 70.8 mGy) for 24 h. We analyzed cell proliferation and apoptosis by trypan blue exclusion and flow cytometry, gene expression by real-time PCR, and protein levels with the apoptosis ELISA kit. Apoptosis increased in the Low-dose-rate irradiated cells, but cell number did not differ between non- (Non-IR) and Low-dose-rate irradiated (LDR-IR) cells. In concordance with apoptotic rate, the transcriptional activity of ATM, p53, p21, and Parp was upregulated in the LDR-IR cells. Similarly, Phospho-p53 (Ser15), cleaved caspase 3 (Asp175), and cleaved Parp (Asp214) expression was upregulated in the LDR-IR cells. No difference was observed in the mRNA expression of DNA repair-related genes (Msh2, Msh3, Wrn, Lig4, Neil3, ERCC8, and ERCC6) between Non-IR and LDR-IR cells. Interestingly, the mRNA of Trfc was upregulated in the LDR-IR cells. Therefore, we suggest that short-term Low-dose-rate radiation activates apoptosis in EL4 lymphoma cells.

  15. The short term effects of Low-dose-rate Radiation on EL4 Lymphoma Cell

    International Nuclear Information System (INIS)

    To determine the biological effects of low-dose-rate radiation (137Cs, 2.95 mGy/h) on EL4 lymphoma cells during 24 h, we investigated the expression of genes related to apoptosis, cell cycle arrest, DNA repair, iron transport, and ribonucleotide reductase. EL4 cells were continuously exposed to low-dose-rate radiation (total dose: 70.8 mGy) for 24 h. We analyzed cell proliferation and apoptosis by trypan blue exclusion and flow cytometry, gene expression by real-time PCR, and protein levels with the apoptosis ELISA kit. Apoptosis increased in the Low-dose-rate irradiated cells, but cell number did not differ between non- (Non-IR) and Low-dose-rate irradiated (LDR-IR) cells. In concordance with apoptotic rate, the transcriptional activity of ATM, p53, p21, and Parp was upregulated in the LDR-IR cells. Similarly, Phospho-p53 (Ser15), cleaved caspase 3 (Asp175), and cleaved Parp (Asp214) expression was upregulated in the LDR-IR cells. No difference was observed in the mRNA expression of DNA repair-related genes (Msh2, Msh3, Wrn, Lig4, Neil3, ERCC8, and ERCC6) between Non-IR and LDR-IR cells. Interestingly, the mRNA of Trfc was upregulated in the LDR-IR cells. Therefore, we suggest that short-term Low-dose-rate radiation activates apoptosis in EL4 lymphoma cells.

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

    International Nuclear Information System (INIS)

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

  17. Multi-level effects of low dose rate ionizing radiation on southern toad, Anaxyrus [Bufo] terrestris

    International Nuclear Information System (INIS)

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development -embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae

  18. Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris.

    Directory of Open Access Journals (Sweden)

    Karolina Stark

    Full Text Available Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris during its pre-terrestrial stages of development -embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later, to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.

  19. Use of virtual reality to estimate radiation dose rates in nuclear plants

    International Nuclear Information System (INIS)

    Operators in nuclear plants receive radiation doses during several different operation procedures. A training program capable of simulating these operation scenarios will be useful in several ways, helping the planning of operational procedures so as to reduce the doses received by workers, and to minimize operations' times. It can provide safe virtual operation training, visualization of radiation dose rates, and estimation of doses received by workers. Thus, a virtual reality application, a free game engine, has been adapted to achieve the goals of this project. Simulation results for Argonauta research reactor of Instituto de Engenharia Nuclear are shown in this paper. A database of dose rate measurements, previously performed by the radiological protection service, has been used to display the dose rate distribution in the region of interest. The application enables the user to walk in the virtual scenario, displaying at all times the dose accumulated by the avatar. (author)

  20. A geoscientific background on the distribution of terrestrial gamma ray dose rates in the Japanese Islands

    International Nuclear Information System (INIS)

    Lithologic and geologic knowledge is essential to understand the characteristics of the distribution of terrestrial gamma ray dose rates in the Japanese Islands. However, the target fields in lithology and geology are too wide. The present paper focuses particularly on very basic theories about crystallization-differentiation of magma and partial melting of source material, which play a vital role in understanding the distribution of terrestrial gamma ray dose rates. Soil is the main source emitting natural gamma rays which we observe outdoors. Then, it is important to know the relationship of radioactivities between rock and soil. This paper describes the transport of radioactivity from rock to soil theoretically, and evaluates reduction of dose rate due to leaching, eluviation and other effects. Finally, this paper deals with the problem of how the terrestrial gamma ray dose rate averaged over the Japanese Islands changed from the Mesozoic up to the present. Concretely, arranging the bedrock types in order of geologic age, a historical change of dose rate levels is outlined. (author)

  1. Changes in External Radiation Dose Rate for PET-CT Test Patients

    International Nuclear Information System (INIS)

    This paper analyzes changes in the external radiation dose rate of PET-CT test patients as a part of providing basic materials for reduction of radiation exposure to PET-CT test patients. In theory the measurement of external radiation dose rate of PET-CT test patients shows that the further the distance from the patient injected with radioactive pharmaceutical and a longer time elapsement from the injection leads to a smaller amount of radiation. Particularly, the amount of radiation marked the highest in the chest was at 4.17 minutes immediately after the intravenous injection and in the head after 77.47 minutes after urination in advance to the PET-CT test. As in the generalized information, it is desired to keep distance between the patient and caretakers or professionals to reduce the amount of radiation exposure from PET-CT test patients and to resume contact the patient after the time when the radiation has reduced. If contact is unavoidable, it is desired to keep at least 200 cm from the patient. In addition, the amount of radiation reached the highest in the chest at first and then in the head from 77 minutes after injection. Accordingly, it would be helpful in achieving the optimization if contact is made based on the patient's physical characteristics. This study is significant as it measures changes in radiation the dose rate by; distance from the PET-CT test patient, time elapsed, and specific parts of body. Further studies based on the findings in this paper are required to analyze changes in radiation dose rate in accordance with individual characteristics unique to PET-CT patients and to utilize the results to reduce the amount of radiation patient, caretakers and professions are exposed.

  2. Calculation of radiation dose rate arisen from radionuclide contained in building materials

    International Nuclear Information System (INIS)

    This paper presents some results that we used MCNP5 program to calculate radiation dose rate arisen from radionuclide in building materials. Since then, the limits of radionuclide content in building materials are discussed. The calculation results by MCNP are compared with those calculated by analytical method. (author)

  3. COMPARISON OF NATURAL BACKGROUND DOSE RATES FOR RESIDENTS OF THE AMARGOSA VALLEY, NV, TO THOSE IN LEADVILLE, CO, AND THE STATES OF COLORADO AND NEVADA

    Energy Technology Data Exchange (ETDEWEB)

    D. Moeller and L. C. Sun

    2006-02-24

    In the latter half of 2005, the U.S. Environmental Protection Agency (USEPA) published a Proposed Rule (40 CFR Part 197) for establishing a dose rate standard for limiting radionuclide releases from the proposed Yucca Mountain high-level radioactive waste repository during the time period from 10{sup 4} to 10{sup 6} years after closure. The proposed standard was based on the difference in the estimated total dose rate from natural background in the Amargosa Valley and the ''average annual background radiation'' for the State of Colorado. As defined by the USEPA, ''natural background radiation consists of external exposures from cosmic and terrestrial sources, and internal exposures from indoor exposures to naturally-occurring radon''. On the basis of its assessments, the USEPA estimated that the difference in the dose rate in the two identified areas was 3.5 mSv y{sup -1}. The purpose of this review was to provide an independent evaluation and review of this estimate. One of the first observations was that, because site-specific dose rate measurements for the Amargosa Valley ''were not available'', the dose rates for various sources of natural background in that area, used by the USEPA in its assessment, were based on modifications of the average values for the State of Nevada. A second observation was that the conversion factor applied in estimating the dose rates due to exposures to indoor radon and its decay products was a factor of 2 higher than the currently accepted value. Further review revealed that site-specific data for many natural background sources in the Amargosa Valley were available. One particularly important observation was that about 91% of the residents of that area live in mobile homes which, due to their construction and design, have indoor radon concentrations comparable to, or less than, those outdoors. For that reason, alone, the USEPA estimate of the average dose rate for

  4. The variance-covariance method: Microdosimetry in time-varying low dose-rate radiation fields

    OpenAIRE

    Breckow, Joachim; Wenning, A.; Roos, H; Kellerer, Albrecht M.

    1988-01-01

    The variance-covariance method is employed at low doses and in radiation fields of low dose rates from an241Am (4 nGy/s) and a90Sr (300 nGy/s) source. The preliminary applications and results illustrate some of the potential of the method, and show that the dose average of lineal energy or energy imparted can be determined over a wide range of doses and dose rates. The dose averages obtained with the variance-covariance method in time-varying fields, for which the conventional variance method...

  5. Low LET radiation dose rate effect and free radical production and survival

    International Nuclear Information System (INIS)

    The authors previously published the finding that LD-50/30 varied with the reciprocal cube root of x- or gamma-radiation dose rate in a number of studies by others in mice and rats. Human skin erythema also appeared to fit the relationship. Broyles subsequently employed a modification of the relationship with particular interest in dose rates of less than 6 rad per day. Having noted a deflection of actual data from reciprocal cube root- predicted values at higher dose rates in the earlier utilized studies, they modified the original relationship with the finding of a better fit of data from a broad variety of endpoints to predicted values. These end-points include E. Coli survival, murine lens opacification, spermatogonia depletion, and abnormal liver anaphases, skin erythema in man and swine, LD 50/4 in mice and rats, LD-50/30 in mice, rats, and swine, and LD-50/60 in sheep. ED-50 specific loss of dose-rate effect appears to occur with several of the quoted parameters at very high dose rates (greater than 1000 rad per minute). The possible role of oxygen depletion and free radical production and survival

  6. Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter

    DEFF Research Database (Denmark)

    Borg, J.; Christensen, P.

    1995-01-01

    The extrapolation chamber measurement method is the basic method for the determination of dose rates in beta radiation fields and the method has been used for the establishment of beta calibration fields. The paper describes important details of the method and presents results from the measurement...... of depth-dose profiles from different beta radiation fields with E(max) values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high...... sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value of the...

  7. Biological effects of low doses of radiation at low dose rate

    International Nuclear Information System (INIS)

    The purpose of this report was to examine available scientific data and models relevant to the hypothesis that induction of genetic changes and cancers by low doses of ionizing radiation at low dose rate is a stochastic process with no threshold or apparent threshold. Assessment of the effects of higher doses of radiation is based on a wealth of data from both humans and other organisms. 234 refs., 26 figs., 14 tabs

  8. Environmental gamma dose rate monitoring along Mumbai-Pune route using environmental radiation monitor with navigational aid

    International Nuclear Information System (INIS)

    A continuous environmental radiation monitor with navigational aid (ERMNA) for mapping natural gamma radiation background on country wide scale by deployment in railway coaches, has been designed. The system makes use of Indian railway network which is one of the widest network of railways in the world covering nearly complete length and breadth of the country. The system uses an energy compensated (within ± 30%) GN detectors for measurement of environmental dose rate due to natural background, a global positioning system (GPS) for on-line acquisition of positional co-ordinates (longitude and latitude) and an 8085 based data acquisition and processing unit. This system is deployed in guard's cabin of a train. The dose rate data tagged with positional co-ordinates and collected by the system during train journey is down loaded into a Lap Top PC for storage, analysis and graphical representation. The system has been used for background monitoring between Mumbai and Pune. The dose rates recorded over a period of three months ranging from November 1996 to February 1997 along the route show no change in the values which vary from 4 μr/h to 6 μR/h along the route. It drops down to <3 μR/h within tunnels en route. (author)

  9. A High Dose-Rate Gamma Irradiation Test of Passive Elements of Radiation- Tolerant Camera System

    International Nuclear Information System (INIS)

    In this paper, a high dose-rate gamma-ray irradiation test of passive elements, which are components of radiation-tolerant camera system, is described. In the overhaul period of the nuclear power plant, integrity of the neutron-irradiated fuel assembly is evaluated. Among the evaluation methods for the integrity of the neutron-irradiated fuel assembly during the normal operation cycle of the nuclear power plant, VT(visual test) of the four face of nuclear fuel assembly is a major concern. As the neutron-irradiated fuel assembly is a high dose-rate gamma-ray source, approximately a few kGy, radiation-hardened camera composed of vidicon tube-type image sensors is used in the VT. The VT of the four face of nuclear fuel assembly, which is a high dose-rate gamma source, is performed in the canal. The width of canal, d.., is about 1,500mm. As the distance, d2, between the fuel assembly (d3 , 224mm) and the camera system, assumed that the width of camera system is about 200mm, is short below one tenth shielding thickness of gamma-ray of water, about 660mm, a COTS CCD device can not be used directly. As the image resolution of the COTS CCD device is higher than vidicon-tube type image sensor, the VT of the four face of the nuclear fuel assembly is clearly performed, if assumed that the radiation-weakened CCD device is properly shielded from the high dose rate gamma-ray source. In this paper, it is assumed that a radiation-tolerant camera system, which are composed of COTS CCD camera, zoom lens, anti-reflection mirror, and visible window, is used in the VT of the nuclear fuel assembly. And the COTS CCD camera and zoom lens module are shielded from a high dose-rate gamma-ray source using the high-density material, lead or tungsten. The passive elements, mirror and visible window, which are placed in the optical path of CCD camera, are exposed to a high dose-rate gamma-ray source directly. So, the gamma ray irradiation characteristics of passive elements, is needed to test

  10. Radiation-induced 1/f noise degradation of PNP bipolar junction transistors at different dose rates

    Science.gov (United States)

    Qi-Feng, Zhao; Yi-Qi, Zhuang; Jun-Lin, Bao; Wei, Hu

    2016-04-01

    It is found that ionizing-radiation can lead to the base current and the 1/f noise degradations in PNP bipolar junction transistors. In this paper, it is suggested that the surface of the space charge region of the emitter-base junction is the main source of the base surface 1/f noise. A model is developed which identifies the parameters and describes their interactive contributions to the recombination current at the surface of the space charge region. Based on the theory of carrier number fluctuation and the model of surface recombination current, a 1/f noise model is developed. This model suggests that 1/f noise degradations are the result of the accumulation of oxide-trapped charges and interface states. Combining models of ELDRS, this model can explain the reason why the 1/f noise degradation is more severe at a low dose rate than at a high dose rate. The radiations were performed in a Co60 source up to a total dose of 700 Gy(Si). The low dose rate was 0.001 Gy(Si)/s and the high dose rate was 0.1 Gy(Si)/s. The model accords well with the experimental results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61076101 and 61204092).

  11. Experimental long-term exposures of fish to low dose rate gamma- or alpha-radiation

    International Nuclear Information System (INIS)

    While it is well known that α-radiation is much more damaging than γ-radiation (on an equal absorbed dose basis) to man and mammals, there are no data available to compare the effects of these radiations on fish. As many authorised disposals of radioactivity are made to sea or rivers and include α- and γ-emitters it is important that such data is obtained so that estimates of the combined biological damaging effects may be made. This paper describes experiments made to examine the comparative effects of chronic exposure to α- or γ-radiation on reproductive endpoints in a representative fish, the zebrafish Danio rerio. Fish were exposed to γ-radiation or α-radiation for approximately 1 year. The fish were allowed to breed once per week and for each breeding opportunity the total numbers of eggs, numbers of eggs viable at 24 hours and eggs hatching successfully were recorded. Dose rate groups were 300, 1000 or 7400μGy h-1 for γ-radiation and 9.6, 19, 84 and 214μGy h-1 for α-radiation. None of the α-radiation groups showed significant effects on any measure of egg production while among γ-radiation groups only the highest, 7400μGy h-1 group showed an effect. This was a rapid decrease in total number of eggs and viable eggs laid per opportunity, leading to a failure to lay any after 20 weekly opportunities. There was, however, no significant decrease in any group in the hatch rate of eggs which were viable at 24 hours. Comparison of the highest α-radiation dose rate which produced no effect (214μGy h-1) and the γ-radiation dose rate which had a significant effect (7400μGy h-1) gives a relative biological effect (RBEα) of <35. (author)

  12. Terrestrial gamma radiation dose rate in Ryukyu Islands, subtropical region of Japan

    International Nuclear Information System (INIS)

    In order to explain the distribution of natural radiation level in the Asia, in situ measurements of dose rate in air due to terrestrial gamma radiation have been conducted in a total of 21 islands that belong to Ryukyu Islands (Ryukyu Archipelago), subtropical rejoin of southwest Japan. Car-borne surveys have also been carried out in Okinawa-jima, the biggest island of the archipelago. Based on the results for these measurements, arithmetic mean, the maximum and the minimum of the dose rates at 1 m in height from the unpaved soil ground in the archipelago were estimated to be 47, 165 and 8 nGy h-1, respectively. A comparative study of car-borne data obtained prior to and subsequent to the 2011 Fukushima nuclear accident, as for Okinawa-jima, indicated that the nuclear accident has no impact on the environmental radiation at the present time. (authors)

  13. Remote Sensing of Radiation Dose Rate by Customizing an Autonomous Robot

    International Nuclear Information System (INIS)

    Distribution of radiation dose was measured by customizing an autonomous cleaning robot 'Roomba' and a scintillation counter. The robot was used as a vehicle carrying the scintillation survey meter, and was additionally equipped with an H8 micro computer to remote-control the vehicle and to send measured data. The data obtained were arranged with position data, and then the distribution map of the radiation dose rate was produced. Manual, programmed and autonomous driving tests were conducted, and all performances were verified. That is, for each operational mode, the measurements both with moving and with discrete moving were tried in and outside of a room. Consequently, it has been confirmed that remote sensing of radiation dose rate is possible by customizing a robot on market.

  14. The influence of the concentration of atmospheric radon decay products on the environmental radiation dose rate

    International Nuclear Information System (INIS)

    It has been occasionally found from an area monitoring data obtained at an atomic power station that the daily periodical change of the environmental radiation dose rate appeared near the ground surface. It is suggested that the variation has resulted from the change of atmospheric radon concentration and that it has also depended on the geographical features of the observation point. The change component has been estimated to be up to nearly 30 percent of the environmental radiation dose rate from monitoring data. To investigate precisely the phenomena, observation was performed near a monitoring station and at other area in Fukui Prefecture during the summer. The dose rate from terrestrial radiation was 42 nGy/h at the Natasho in Ooi Town and was 30 nGy/h at the Kaminaka in Wakasa Town. The concentration of radon decay products in the air was 0.5 - 30 Bq/m3 at the Natasho site and was 1 - 10 Bq/m3 at the Kaminaka site. From the concentration of radon decay products in the atmosphere, the dose rate was respectively estimated to be 0-7.0 nGy/h at the Natasho site, and to be 0-5.5 nGy/h at the Kaminaka site. Furthermore, 0.26(nGy/h)/(Bq/m3) and 0.56(nGy/h)/(Bq/m3) were estimated as the dose rate conversion factor of radon concentration in the air at the Natasho site and at the Kaminaka site, respectively. (author)

  15. Influence of radiation dose rate on somatic mutation induction in Tradescantia stamen hairs

    International Nuclear Information System (INIS)

    Both x and gamma rays have been used to investigate the effect of dose rate on the induction of pink mutant cells in stamen hairs of Tradescantia clone 02. For inflorescences exposed to doses of 60 to 80 rads of x rays at 0.3 to 503 rads/min there was a progressive increase in the number of mutations/rad/104 hairs as the dose rate was increased from 0.3 to 105 rads/min. However, 300 rads/min did not further increase the mutation rate, and at 503 rads/min the effect was slightly less, but approximately equal to that at 30 rads/min. With 58 to 79 rads of 137Cs gamma rays, the mutation rate increased progressively with dose rate over the entire range studied (0.0034 to 30 rads/min). Some inflorescences were held at 8 C before and during irradiation to slow development so that low dose rates (3.4 to 12 mrads/min) could be delivered within a given development period. The mutation rate during cold treatment was higher than when the same dose rates were given during a period of more rapid development under standard growth conditions. Dose-response relationships were established at three radiation intensities, 0.05, 0.5, and 5.0 rads/min, and the resulting mutation rates were related to those from a previously established curve derived at 30 rads/min. Mutation response was independent of dose rate at 10 rads and below, but a progressively lower incidence of mutation was associated with the 5.0 and 0.5 rad/min intensities over at least a 30- to 160-rad range of doses. Response to 0.05 rads/min was not different from that at 0.5 rads/min over the entire 5- to 30-rad range of doses investigated. (U.S.)

  16. Radiation dose-rate resistivity degradation in ceramic insulators and assessment of the consequences in fusion reactor applications

    International Nuclear Information System (INIS)

    Under neutron and/or gamma absorbed dose-rates typical of fusion reactor conditions, common ceramic insulators such as Al2O3, MgO, MgAl2O3, etc., exhibit a significant instantaneous decrease in their dc resistivity. Ceramic insulators in lightly shielded normal-conducting magnets, direct convertors and first wall applications are shown to be the most affected. Depending on conductor design, magnet location, absorbed dose-rate and applied voltages, it is demonstrated that the resulting leakage currents in the ceramic material are potentially capable of producing significant Joule heating rates which may lead to thermal runaway and subsequent insulator destruction. The theoretical background for this effect is presented and the rather sparse experimental data base reviewed. Recommendations are given for computing worst case radiation-induced conductivity increases as a function of absorbed dose rate. The possible ameliorating influences of long term fluence damage are then discussed. The practical consequences of ceramic resistivity degradation are quantitatively assessed by consideration of resulting leakage current Joule heating in the extruded conductor of a typical normal-conducting magnet. Relationships are derived to compute dose-rate-dependent leakage currents and Joule heating rates as a function of several magnet parameters

  17. Collection of radiation resistant characteristics reports for instruments and materials in high dose rate environment

    International Nuclear Information System (INIS)

    This document presents the collected official reports of radiation irradiation study for the candidate materials to be used in high dose rate environment as J-PARC facility. The effect of radiation damage by loss-beam or secondary particle beam of the accelerators influences the performance and the reliability of various instruments. The knowledge on the radiation resistivity of the materials is important to estimate the life of the equipments, the maintenance interval and dose evaluation for the personnel at the maintenance period. The radiation damage consists with mechanical property, electrical property and gas-evolution property. (author)

  18. Chloroquine Improves Survival and Hematopoietic Recovery After Lethal Low-Dose-Rate Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lim Yiting [Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hedayati, Mohammad; Merchant, Akil A.; Zhang Yonggang; Yu, Hsiang-Hsuan M. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Kastan, Michael B. [Department of Oncology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina (United States); Matsui, William, E-mail: matsuwi@jhmi.edu [Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); DeWeese, Theodore L., E-mail: deweete@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)

    2012-11-01

    Purpose: We have previously shown that the antimalarial agent chloroquine can abrogate the lethal cellular effects of low-dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. Methods and Materials: C57BL/6 mice were irradiated with a total of 12.8 Gy delivered at 9.4 cGy/hour. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 {mu}g per 17 g of body weight, 24 hours and 4 hours before irradiation. Bone marrow cells isolated from tibia, fibula, and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retroorbital injection. Chimerism was assessed by flow cytometry. In vitro methylcellulose colony-forming assay of whole bone marrow cells and fluorescence activated cell sorting analysis of lineage depleted cells were used to assess the effect of chloroquine on progenitor cells. Results: Mice pretreated with chloroquine before radiation exhibited a significantly higher survival rate than did mice treated with radiation alone (80% vs. 31%, p = 0.0026). Chloroquine administration before radiation did not affect the survival of ATM null mice (p = 0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after transplantation (4.2% vs. 0.4%, p = 0.015). Conclusion: Chloroquine administration before radiation had a significant effect on the survival of normal but not ATM null mice, strongly suggesting that the in vivo effect, like the in vitro effect, is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR-irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection

  19. Remote Sensing of Radiation Dose Rate by a Robot for Outdoor Usage

    Science.gov (United States)

    Kobayashi, T.; Doi, K.; Kanematsu, H.; Utsumi, Y.; Hashimoto, R.; Takashina, T.

    2013-04-01

    In the present paper, the design and prototyping of a telemetry system, in which GPS, camera, and scintillation counter were mounted on a crawler type traveling vehicle, were conducted for targeting outdoor usage such as school playground. As a result, the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt. The results were as follows: (1) It was confirmed that the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt (running speed: 17[m/min]). (2) It was confirmed that the location information captured by GPS is visible on the Google map, and that the incorporation of video information is also possible to play. (3)A radiation dose rate of 0.09[μSv / h] was obtained in the ground. The value is less than the 1/40 ([3.8μSv / h]) allowable radiation dose rate for children in Fukushima Prefecture.(4)As a further work, modifying to program traveling, the measurement of the distribution of the radiation dose rate in a school of Fukushima Prefecture, and class delivery on radiation measurement will be carried out.

  20. Remote Sensing of Radiation Dose Rate by a Robot for Outdoor Usage

    International Nuclear Information System (INIS)

    In the present paper, the design and prototyping of a telemetry system, in which GPS, camera, and scintillation counter were mounted on a crawler type traveling vehicle, were conducted for targeting outdoor usage such as school playground. As a result, the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt. The results were as follows: (1) It was confirmed that the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt (running speed: 17[m/min]). (2) It was confirmed that the location information captured by GPS is visible on the Google map, and that the incorporation of video information is also possible to play. (3)A radiation dose rate of 0.09[μSv / h] was obtained in the ground. The value is less than the 1/40 ([3.8μSv / h]) allowable radiation dose rate for children in Fukushima Prefecture.(4)As a further work, modifying to program traveling, the measurement of the distribution of the radiation dose rate in a school of Fukushima Prefecture, and class delivery on radiation measurement will be carried out.

  1. Numerical simulation of gamma-ray radiation dose-rate effects of typical semiconductor devices

    International Nuclear Information System (INIS)

    In order to research radiation effects of ultra-small semiconductor device, a coupled algorithm for FVM with MC Method is described. The transient responses of reverse biased diodes with different structures, working at Gamma-ray radiation environment, are simulated by the new algorithm. The results are compared with Enlow's photocurrent model. It shows that the algorithm is reliable in simulating dose-rate effects of semiconductor devices. The relationship among dose-rate, thickness of epitaxial layer, pulse-width and reverse photocurrent is also investigated. It shows that epi-layer constrains the collecting volume, so that the thinner epi-layer is, the lower peak value and the fast falling-down speed of photocurrent will be; and that the narrower pulse-width is, the higher peak value of current with respect to the same dose will be. (authors)

  2. Reaction rate theory of radiation exposure: Effects of the dose rate on mutation frequencies

    CERN Document Server

    Manabe, Yuichiro; Nakamura, Issei

    2014-01-01

    We develop a kinetic reaction model for the cells having the irradiated DNA molecules due to the ionizing radiation exposure. Our theory simultaneously accounts for the time-dependent reactions of the DNA damage, the DNA mutation, the DNA repair, and the proliferation and apoptosis of cells in a tissue with a minimal set of model parameters. In contrast to the existing theories for the radiation exposition, we do not assume the relationships between the total dose and the induced mutation frequency. We show good agreement between theory and experiment. Importantly, our result shows a new perspective that the key ingredient in the study of the irradiated cells is the rate constants depending on the dose rate. Moreover, we discuss the universal scaling function for mutation frequencies due to the irradiation at low dose rates.

  3. Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter

    DEFF Research Database (Denmark)

    Borg, J.; Christensen, P.

    of depth-dose profiles from different beta radiation fields with E(max) values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high...... sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value of the...

  4. Emesis as a Screening Diagnostic for Low Dose Rate (LDR) Total Body Radiation Exposure.

    Science.gov (United States)

    Camarata, Andrew S; Switchenko, Jeffrey M; Demidenko, Eugene; Flood, Ann B; Swartz, Harold M; Ali, Arif N

    2016-04-01

    Current radiation disaster manuals list the time-to-emesis (TE) as the key triage indicator of radiation dose. The data used to support TE recommendations were derived primarily from nearly instantaneous, high dose-rate exposures as part of variable condition accident databases. To date, there has not been a systematic differentiation between triage dose estimates associated with high and low dose rate (LDR) exposures, even though it is likely that after a nuclear detonation or radiologic disaster, many surviving casualties would have received a significant portion of their total exposure from fallout (LDR exposure) rather than from the initial nuclear detonation or criticality event (high dose rate exposure). This commentary discusses the issues surrounding the use of emesis as a screening diagnostic for radiation dose after LDR exposure. As part of this discussion, previously published clinical data on emesis after LDR total body irradiation (TBI) is statistically re-analyzed as an illustration of the complexity of the issue and confounding factors. This previously published data includes 107 patients who underwent TBI up to 10.5 Gy in a single fraction delivered over several hours at 0.02 to 0.04 Gy min. Estimates based on these data for the sensitivity of emesis as a screening diagnostic for the low dose rate radiation exposure range from 57.1% to 76.6%, and the estimates for specificity range from 87.5% to 99.4%. Though the original data contain multiple confounding factors, the evidence regarding sensitivity suggests that emesis appears to be quite poor as a medical screening diagnostic for LDR exposures. PMID:26910032

  5. Radiation dose-rate meter using an energy-sensitive counter

    International Nuclear Information System (INIS)

    A radiation dose-rate meter is described comprising: an energy-sensitive radiation detecting element which generates at an output thereof ionization current pulses having an amplitude proportional to the charge quanta deposited in the radiation detecting element by detected photons of ionizing radiation; a charge-sensitive preamplifier connected to the output of the radiation detecting element; a filter amplifier having a selected filter time constant for generating fixed width pulses at an output thereof in response to each of the step voltage pulses from the preamplifier having an amplitude proportional to the amplitude of each of the step voltage pulses applied to an input thereof; a multi-level discriminator means responsive to the voltage pulses at the output of the filter amplifier for generating a train of count pulses at an output thereof in response to each of the fixed width pulses; and a count rate meter means connected to the output of the multi-level discriminator means of registering the count pulses of each of the train of count pulses as a quantized measure of the radiation dose-rate per unit time of the detected photons of ionizing radiation

  6. Radiation Dose-Rate Effects on Gene Expression in a Mouse Biodosimetry Model.

    Science.gov (United States)

    Paul, Sunirmal; Smilenov, Lubomir B; Elliston, Carl D; Amundson, Sally A

    2015-07-01

    In the event of a nuclear accident or radiological terrorist attack, there will be a pressing need for biodosimetry to triage a large, potentially exposed population and to assign individuals to appropriate treatment. Exposures from fallout are likely, resulting in protracted dose delivery that would, in turn, impact the extent of injury. Biodosimetry approaches that can distinguish such low-dose-rate (LDR) exposures from acute exposures have not yet been developed. In this study, we used the C57BL/6 mouse model in an initial investigation of the impact of low-dose-rate delivery on the transcriptomic response in blood. While a large number of the same genes responded to LDR and acute radiation exposures, for many genes the magnitude of response was lower after LDR exposures. Some genes, however, were differentially expressed (P false discovery rate information in a mass radiological casualty event. PMID:26114327

  7. ESR dating of elephant teeth and radiation dose rate estimation in soil

    International Nuclear Information System (INIS)

    Chemical analysis of 238U, 232Th and 40K in the dentine as well as enamel of elephant tooth fossil has been carried out in order to estimate the internal absorbed dose rate of the specimens, which was estimated to be (39±4) mrad/y on the assumption of early uptake model of radionuclides. The external radiation dose rate in the soil including the contribution from cosmic rays was also estimated to be (175±18) mrad/y with the help of γ-ray spectroscopic techniques of the soil samples in which the specimens were buried. The 60Co γ-ray equivalent accumulated dose of (2±0.2) x 104 rad for the tooth enamel gave ''ESR age'' of (9±2) x 104 y, which falls in the geologically estimated range between 3 x 104 and 30 x 104 y before the present. (author)

  8. Dose Rate Effect on Grafting by Gamma Radiation of DMAEMA onto Flexible PVC

    International Nuclear Information System (INIS)

    Intravenous tubing, blood bags and catheters stays in contact with blood and body fluids. They are normally made by flexible PVC. The contact of PVC with this fluid is not possible for long periods and there is the necessity of addition of non-thrombogenic substances into blood. This work shows the radiation grafting process to produce copolymer PVC-g-DMAEMA, a new material that allows a future grafting of Heparin on it, and will have the perspective of avoiding undesirable substances additions to blood or body fluid contact. In this preliminary work, only radiation dose rate effect on grafting was studied

  9. Influence of dose-rate on inflammatory damage and adhesion molecule expression after abdominal radiation in the rat

    International Nuclear Information System (INIS)

    Purpose: The goal of this study was to assess the effects of two clinically relevant radiation dose-rates on endothelial adhesion molecule expression, inflammatory response, and microvascular dysfunction. Methods and Materials: Rats were irradiated with 10 Gy at low (0.9 Gy/min) or high (3 Gy/min) dose-rates. Control animals received sham irradiation. Leukocyte rolling, adhesion, emigration, and microvascular permeability were assessed in mesenteric venules by intravital microscopy 6 hours after irradiation. P-selectin and intercellular adhesion molecule-1 (ICAM-1) expression were measured using radiolabeled monoclonal antibodies. Results: Low dose-rate (LDR) abdominal irradiation increased leukocyte adhesion compared with sham-irradiated animals, whereas high dose-rate (HDR) irradiation resulted in enhanced leukocyte rolling, adhesion, and emigration, compared with the LDR or with sham-irradiated rats. Both dose-rates increased microvascular permeability, although this effect was significantly greater after radiation with the high (8-fold) than the low (5-fold) dose-rate. HDR radiation induced significantly larger increments in P-selectin expression in splanchnic organs than LDR, whereas in most organs ICAM-1 expression was only upregulated by the HDR. Blockade of ICAM-1, but not P-selectin, abrogated leukocyte adhesion at both dose-rates. Conclusions: The magnitude of upregulation of endothelial adhesion molecules, leukocyte recruitment, and endothelial barrier dysfunction elicited by radiation therapy is dependent on the dose-rate at which the radiation is delivered

  10. Development of evaluation tool for radiation dose rate distribution in PCV of Hamaoka BWR plants based on water chemistry

    International Nuclear Information System (INIS)

    We have developed an evaluation tool for the radiation dose rate distribution of the work areas in the primary containment vessel (PCV) of Units 3, 4 (BWR5) and 5 (ABWR) at Hamaoka NPS. This tool has been constructed based on the transport behavior of radioactive corrosion products in the primary cooling water of BWR. This tool can be used to evaluate quantitatively the effects of the dose reduction methods by water chemistry control or radiation management. It is composed of two calculation codes; water chemistry code (ACTTUBE) and radiation dose rate code (RADTUBE). ACTTUBE calculates the piping dose rates based on the mass balance of corrosion products, 6 kinds of metal and 5 kinds of radionuclide, among the parts of primary cooling water, such as reactor water, feed water, fuel rod surface and out-of-core piping surface. RADTUBE calculates the dose rate distribution based on the radiation shielding calculation from a calculation result of ACTTUBE. Additionally, this tool has a visualization function of calculated radiation dose rate distribution in the PCV by using a wireless controller and 3D glasses/monitor in order to improve user convenience. The accuracy of the tool's calculation results was evaluated using the water chemistry data and radiation dose rate data of the Hamaoka plants. As a result, it was confirmed that this tool had sufficient accuracy to be used in the evaluation of radiation dose rates for the radiation management of actual plants. (author)

  11. Survey of environmental radiation dose rates from Tokushima to Misasa hot spring in Tottori using a scintillation survey meter

    International Nuclear Information System (INIS)

    In this work, a survey of environmental radiation dose rates from Tokushima to Misasa Hot Spring in Tottori has been performed using a portable NaI(Tl) scintillation survey meter equipped in a car. It has been possible to record the environmental radiation dose rates together with time information by a portable personal computer. In the course of the present survey, the maximum value of the environmental radiation dose rates was 0.203 μSv/h into Kokubunji tunnel in Kagawa prefecture, while the minimum value was 0.016 μSv/h on the bridge of Seto-Ohashi. Radiation dose rates into tunnels were higher than those of public places, in contrast, those on bridges were lower. This trend is in agreement with generally recognized one. That is, the radiation dose rates into tunnels will increase by a top and sides of bedrocks, while those on bridges will decrease by the effect of shielding of river and sea waters for the natural occurring radiation due to bedrocks. Comparing the environmental radiation dose rates at public places in the following four prefectures, Tokushima, Kagawa, Okayama, and Tottori, except those tunnels and bridges, we found that the average radiation dose rate in Tottori was 0.079 ± 0.011 μSv/h and it was the highest value in the four prefectures. This suggests that granites, which generally have the highest content of U and Th, will be geologically distributed in the Chugoku District than the Shikoku One. (author)

  12. MicroShield analysis to calculate external radiation dose rates for several spent fuel casks

    International Nuclear Information System (INIS)

    The purpose of this MicroShield analysis is to calculate the external radiation, primarily gamma, dose rate for spent fuel casks. The reason for making this calculation is that currently all analyses of transportation risk assume that this external dose rate is the maximum allowed by regulation, 10 mrem/hr at 2 m from the casks, and the risks of incident-free transportation are thus always overestimated to an unknown extent. In order to do this, the program by Grove Software, MicroShield 7.01, was used to model three Nuclear Regulatory Commission (NRC) approved casks: HI-STAR 100, GA-4, and NAC-STC, loaded with specific source material. Dimensions were obtained from NUREG/CR-6672 and the Certificates of Compliance for each respective cask. Detectors were placed at the axial point at 1 m and 2 m from the outer gamma shielding of the casks. In the April 8, 2004 publication of the Federal Register, a notice of intent to prepare a Supplemental Yucca Mountain Environmental Impact Statement (DOE/EIS-0250F-S1) was published by the Office of Civilian Radioactive Waste Management (OCRWM) in order to consider design, construction, operation, and transportation of spent nuclear fuel to the Yucca Mountain repository [1]. These more accurate estimates of the external dose rates could be used in order to provide a more risk-informed analysis. (authors)

  13. Influence of clouds on the cosmic radiation dose rate on aircraft

    International Nuclear Information System (INIS)

    Flight missions were made in Brazilian territory in 2009 and 2011 with the aim of measuring the cosmic radiation dose rate incident on aircraft in the South Atlantic Magnetic Anomaly and to compare it with Monte Carlo simulations. During one of these flights, small fluctuations were observed in the vicinity of the aircraft with formation of Cumulonimbus clouds. Motivated by these observations, in this work, the authors investigated the relationship between the presence of clouds and the neutron flux and dose rate incident on aircraft using computational simulation. The Monte Carlo simulations were made using the MCNPX and Geant4 codes, considering the incident proton flux at the top of the atmosphere and its propagation and neutron production through several vertically arranged slabs, which were modelled according to the ISO specifications. The paper presents first-order calculation about the influence of Cumulonimbus clouds on the flux and dose rate due to cosmic neutrons in the atmosphere, at aircraft flight altitudes. The simulations show variations of the order of 5.5 % in the neutrons flux and 3.6 % of the dose rate due to the presence of the cloud. Such variations can extend up to ∼1.5 km from the edge of the cloud. The spectrum of neutrons within a cloud formation was observed undergo changes due to the neutron absorption and scattering processes with the water content inside the cloud. To accomplish these simulations, it is important to have a proper knowledge of the data libraries and nuclear models to be applied, since the simulation processes are strongly dependent on these factors. These results emphasise the importance of conducting more detailed studies on this topic, since the influence of clouds can change the dose and flux on aircraft overflying such formations, as well as could explain some of the fluctuations in the experimental dose rate data obtained in aircraft flights. Future studies should extend such simulations to different types of

  14. Genome instability induced by extreme low dose/low dose rate heavy ion radiation

    International Nuclear Information System (INIS)

    We irradiated normal human fibroblasts (HFL III) with carbon ions (290 MeV/u, 70 keV/um) at very low dose (1 mGy total dose) and low dose rate (1 mGy/6 h) and observed the growth kinetics for several months by continuous culturing. The growth of carbon irradiated cells started to slow down much earlier than that of non-irradiated control cells before reaching senescence. On the other hand, HFL III cells irradiated at the same dose and the dose rate of gamma-rays were slightly accelerated their growth. Our measurements on DNA double strand break (DSB) such as gamma-H2AX foci revealed a higher number of foci in carbon irradiated cells than in gamma-irradiated cells at a cell passage near senescence. Taken together, our results suggest that high linear energy transfer (LET) radiation causes different effects than low LET radiation even at very low doses and that the effect of single low dose irradiation can affect the stability of genome many generations after irradiation. (author)

  15. The role of dose rate in radiation cancer risk: evaluating the effect of dose rate at the molecular, cellular and tissue levels using key events in critical pathways following exposure to low LET radiation

    Science.gov (United States)

    Brooks, Antone L.; Hoel, David G.; Preston, R. Julian

    2016-01-01

    Abstract Purpose: This review evaluates the role of dose rate on cell and molecular responses. It focuses on the influence of dose rate on key events in critical pathways in the development of cancer. This approach is similar to that used by the U.S. EPA and others to evaluate risk from chemicals. It provides a mechanistic method to account for the influence of the dose rate from low-LET radiation, especially in the low-dose region on cancer risk assessment. Molecular, cellular, and tissues changes are observed in many key events and change as a function of dose rate. The magnitude and direction of change can be used to help establish an appropriate dose rate effectiveness factor (DREF). Conclusions: Extensive data on key events suggest that exposure to low dose-rates are less effective in producing changes than high dose rates. Most of these data at the molecular and cellular level support a large (2–30) DREF. In addition, some evidence suggests that doses delivered at a low dose rate decrease damage to levels below that observed in the controls. However, there are some data human and mechanistic data that support a dose-rate effectiveness factor of 1. In summary, a review of the available molecular, cellular and tissue data indicates that not only is dose rate an important variable in understanding radiation risk but it also supports the selection of a DREF greater than one as currently recommended by ICRP (2007) and BEIR VII (NRC/NAS 2006). PMID:27266588

  16. Dose rate and temperature effects in radiation disorder creation in SrTiO sub 3

    CERN Document Server

    Sabathier, C; Krupa, J C

    2002-01-01

    An important aspect of assessing the physical and chemical stability of SrTiO sub 3 phase under radiation is to evaluate the disorder caused by alpha-decays in the actinide loaded nuclear waste form during the repository time. Indeed, radiation can affect considerably the chemical durability of the solid waste forms, especially for alpha-emitter immobilisation. It is already known that amorphization in SrTiO sub 3 can be described at room temperature, by the cascade-overlap model with an additional term representing the initial disorder creation. In the present work, it is shown by using Pb-ion beam to simulate the alpha-recoil nuclei for creating the disorder that Pb-dose rate and sample temperature during irradiation are two important factors that affect SrTiO sub 3 susceptibility to proceed toward amorphization.

  17. The influence of geology on terrestrial gamma radiation dose rate in Pahang state, Malaysia

    International Nuclear Information System (INIS)

    Terrestrial gamma radiation dose (TGRD) rate measurements have been made in Pahang state, Malaysia. Significant variations were found between TGRD measurements and the underlying geological formations. In some cases revealing significant elevations of TGRD. The acid-intrusive geological formation has the highest mean TGRD measurement of 367 nGy/h-1. This is more than six times the world average value of 59 nGy/h-1, while the quaternary geological formation has the lowest mean gamma radiation dose rate of 99 nGy h-1. The annual effective dose equivalent outdoor to the population was 0.216 mSv. The lifetime equivalent dose and relative lifetime cancer risks for an individual living in Pahang state were 81 mSv and 4.7 x 10-3 respectively. These values are more than two times the world average of 34 mSv and 1.95 x 10-3 respectively. (author)

  18. Brachytherapy. Pulsed dose rate brachytherapy - Radiation protection: medical sheet ED 4250

    International Nuclear Information System (INIS)

    After having indicated the required authorization to implement brachytherapy techniques, this document presents the various aspects and measures related to radiation protection when performing pulsed-dose-rate brachytherapy treatments. It presents the concerned personnel, describes the operational process, indicates the associated hazards and the risk related to ionizing radiation, and describes how the risk is to be assessed and how exposure levels are to be determined (elements of risk assessment, delimitation of controlled and monitored areas, personnel classification, and choice of the dose monitoring method). It describes the various components of a risk management strategy (risk reduction, technical measures regarding the installation and the personnel, training and information, prevention and medical monitoring). It briefly presents how risk management is to be assessed, and mentions other related risks (biological risk, handling and posture, handling of heavy loads, mental workload, chemical risk)

  19. Effects of dose, dose-rate and fraction on radiation-induced breast and lung cancers

    International Nuclear Information System (INIS)

    Recent results from a large Canadian epidemiologic cohort study of low-LET radiation and cancer will be described. This is a study of 64,172 tuberculosis patients first treated in Canada between 1930 and 1952, of whom many received substantial doses to breast and lung tissue from repeated chest fluoroscopies. The mortality of the cohort between 1950 and 1987 has been determined by computerized record linkage to the National Mortality Data Base. There is a strong positive association between radiation and breast cancer risk among the females in the cohort, but in contrast very little evidence of any increased risk in lung cancer. The results of this and other studies suggest that the effect of dose-rate and/or fractionation on cancer risk may will differ depending upon the particular cancer being considered. (author)

  20. Estimation of radiation dose rates around medical isotopes production facility of Cyclotron

    International Nuclear Information System (INIS)

    The demand of the radio isotopes for medical application is increasing day by day. Cyclotron is a tool for production of these proton rich isotopes which are termed a SPECT and PET isotopes. The irradiated hot targets from a cyclotron bunker are transferred to the hot cells for processing chemically to obtain the required radioisotope. A pre estimation of dose rates at various locations of the hot cells with worst and normal operation conditions is essential. An exercise of estimation of worst cases also gives an idea about the dose to the workers and necessary preparedness without compromising on the regulatory aspects. 18F, 67Ga, 201Tl are the most important isotopes that will be produced in medical cyclotron. They are produced by bombarding proton on suitable target materials. The activated targets transferred to the hot cells from irradiated machine/production bunker. Chemist has to work at hot cells for chemical synthesis for 18F to form FDG. For SPECT isotope production target has to under go two stages of chemical synthesis. The dose rate estimation around the hot cells will give the estimation of dose to the radiation workers. In addition to medical isotope the other materials surrounding the target also get activated because of proton or neutron activation. The dose estimation depends on the total activity that is produced and the period of time for entire the chemical processing. The dose rate are estimated by using suitable expressions considering normal and worst scenario conditions. A procedure and a case was discussed and result shown both for normal and worse scenario case. It is observed that not only shielding many other factors like ventilation etc played important role. A case study was made and results are shown with the suggestive preventive measures. (author)

  1. Expression of cytoskeletal and matrix genes following exposure to ionizing radiation: Dose-rate effects and protein synthesis requirements

    International Nuclear Information System (INIS)

    Experiments were designed to examine the effects of radiation dose-rate and of the protein synthesis inhibitor cycloheximide on expression of cytoskeletal elements (γ- and β-actin and α-tubulin) and matrix elements (fibronectin) in Syrian hamster embryo cells. Past work from our laboratory had already demonstrated optimum time points and doses for examination of radiation effects on accumulation of specific transcripts. Our results here demonstrated little effect of dose-rate for JANUS fission spectrum neutrons when comparing expression of either α-tubulin or fibronectin genes. Past work had already documented similar results for expression of actin transcripts. Effects of cycloheximide, however, revealed several interesting and novel findings: (1) Cycloheximide repressed accumulation of α-tubulin following exposure to high dose-rate neutrons or γ rays; this did not occur following similar low dose-rate exposure (2) Cycloheximide did not affect accumulation of mRNA for actin genes. Cycloheximide abrogated the moderate induction of fibronectin-mRNA which occurred following exposure to γ rays and high dose-rate neutrons. These results suggest a role for labile proteins in the maintenance of α-tubulin and fibronectin mRNA accumulation following exposure to ionizing radiation. In addition, they suggest that the cellular/molecular response to low dose-rate neutrons may be different from the response to high dose-rate neutrons

  2. Expression of cytoskeletal and matrix genes following exposure to ionizing radiation: Dose-rate effects and protein synthesis requirements

    International Nuclear Information System (INIS)

    Experiments were designed to examine the effects Of radiation dose-rate and of the protein synthesis inhibitor cycloheximide on expression of cytoskeletal elements (γ- and β-actin and α-tubulin) and matrix elements (fibronectin) in Syrian hamster embryo cells. Past work from our laboratory had already demonstrated optimum time points and doses for examination of radiation effects on accumulation of specific transcripts. Our results here demonstrated little effect of dose-rate for JANUS fission spectrum neutrons when comparing expression of either α-tubulin or fibronectin genes. Past work had already documented similar results for expression of actin transcripts. Effects of cycloheximide revealed that cycloheximide repressed accumulation of α-tubulin following exposure to high dose-rate neutrons or γ rays; this did not occur following similar low dose-rate exposure. (2) Cycloheximide did not affect accumulation of MRNA for actin genes; and that cycloheximide abrogated the moderate induction of fibronectin-mRNA which occurred following exposure to γ rays and high dose-rate neutrons. These results suggest a role for labile proteins in the maintenance of α-tubulin and fibronectin MRNA accumulation following exposure to ionizing radiation. in addition, they suggest that the cellular/molecular response to low dose-rate neutrons may be different from the response to high dose-rate neutrons

  3. Dose Rate Effects on The Radiation Oxidation of Polyethylene: Electron Beam vs Gamma Irradiation

    International Nuclear Information System (INIS)

    The yields and spatial distribution of the oxidation products stemming from the oxidation of LLPE films induced by 60-Co gamma and by irradiation with 300 kev, 0.3 mA electrons in the dose range 0.04 kGy/h - 0.6 kGy/h (gamma) and at 1.5 kGy/hr ( e-beam) have been determined by applying a methodology involving FTIR microscopy (carbonyl products, resolution 10 μ), iodometric analysis (peroxides). The FTIR and EPR spectroscopies coupled with the multilayer technique (resolution 25 μ) were also employed for carrying on measurements of the film depth profiles of peroxyl radicals and their alky radicals precursors, radical decay kinetics, 'free' and ' bound' hydroperoxides and alcools. With gamma radiations the products yields are enhanced following the decrease of the dose rate from 0.7 to 0.04 kGy/h without substantial effect on the film depth distributions which appear rather uniform. Using e-beam (dose rate 1.5 kGy/h) a low level concentration limit is attained confined within the first 50 μ which is about 1 order of magnitude smaller as compared to gamma. The mechanistic implications inherent to the experimental results as well as the practical consequences related to the use of radiooxidation as a tool for inducing graft copolymerization reactions are discussed

  4. Effects of dose rates on radiation-induced replenishment of intestinal stem cells determined by Lgr5 lineage tracing

    International Nuclear Information System (INIS)

    An understanding of the dynamics of intestinal Lgr5+ stem cells is important for elucidating the mechanism of colonic cancer development. We previously established a method for evaluating Lgr5+ stem cells by tamoxifen-dependent Lgr5-lineage tracing and showed that high-dose-rate radiation stimulated replenishment of colonic stem cells. In this study, we evaluated the effects of low-dose-rate radiation on stem cell maintenance. Tamoxifen (4OHT)-injected Lgr5-EGFP-IRES-CreERT2 × ROSA-LSL-LacZ mice were used, LacZ-labeled colonic crypts were enumerated, and the loss of LacZ+ crypts under low-dose-rate radiation was estimated. After 4OHT treatment, the number of LacZ-labeled Lgr5+ stem cells was higher in the colon of infant mice than in adult mice. The percentage of LacZ-labeled crypts in infant mice rapidly decreased after 4OHT treatment. However, the percentage of labeled crypts plateaued at ∼2% at 4 weeks post-treatment and remained unchanged for up to 7 months. Thus, it will be advantageous to evaluate the long-term effects of low-dose-rate radiation. Next, we determined the percentages of LacZ-labeled crypts irradiated with 1 Gy administered at different dose rates. As reported in our previous study, mice exposed to high-dose-rate radiation (30 Gy/h) showed a marked replenishment (P = 0.04). However, mice exposed to low-dose-rate radiation (0.003 Gy/h) did not exhibit accelerated stem-cell replenishment (P = 0.47). These findings suggest the percentage of labeled crypts can serve as a useful indicator of the effects of dose rate on the stem cell pool. (author)

  5. Radiation dose rate map interpolation in nuclear plants using neural networks and virtual reality techniques

    International Nuclear Information System (INIS)

    This paper reports the most recent development results of a simulation tool for assessment of radiation dose exposition by nuclear plant's personnel, using artificial intelligence and virtual reality technologies. The main purpose of this tool is to support training of nuclear plants' personnel, to optimize working tasks for minimisation of received dose. A finer grid of measurement points was considered within the nuclear plant's room, for different power operating conditions. Further, an intelligent system was developed, based on neural networks, to interpolate dose rate values among measured points. The intelligent dose prediction system is thus able to improve the simulation of dose received by personnel. This work describes the improvements implemented in this simulation tool.

  6. The radiation sensitivity of the haemopoietic microenvironment - effect of dose rate on ectopic ossicle formation

    International Nuclear Information System (INIS)

    The haemopoietic microenvironment (HM) consists of a complex mixture of cellular types and extra-cellular matrix. It is essential for prolonged haemopoiesis in both the normal situation and after bone marrow transplantation. The competence of the HM can be assessed by ectopic grafting of femoral marrow. A complete haemopoietic organ develops at the site of implantation. Stem cells (CFU-S) which inhabit the ossicle formed after ectopic implantation can be measured, to assess the function of the engrafted HM to support haemopoiesis. Using this functional endpoint the radiation sensitivity of the HM has been examined at both high and low dose rates, and it is concluded that high doses of γ-irradiation delivered at 4 Gy/min or 0.016 Gy/min have widely different effects on the HM, the former proving much more damaging than the latter. 16 refs.; 2 figs

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

    International Nuclear Information System (INIS)

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

  8. Pre-irradiation with a low dose-rate depressed radiation-induced apoptosis in BALB/c mice spleens

    International Nuclear Information System (INIS)

    We aim to elucidate the effects of pre-irradiation to the whole-body with a low dose-rate on the acute radiation-induced apoptosis in the spleens of BALB/c mice. We found significant suppression of apoptosis induced by challenging irradiation at 2.0 Gy (1 Gy/min) immediately after chronic irradiation at 1.5 Gy with a low dose-rate (0.001 Gy/min). These findings suggest that chronic pre-irradiation with a low dose-rate induces some kind of radical detoxification systems and/or repair mechanisms against DNA damage which induces apoptosis. (author)

  9. Simulation of absorbed dose rate due to synchrotron radiation and shielding thickness for radiation safety at Indus-2 using FLUKA

    International Nuclear Information System (INIS)

    Indus-2 is a 2.5 GeV electron synchrotron radiation source at Raja Ramanna Centre for Advanced Technology (RRCAT), India. 26 synchrotron radiation (SR) beam lines are planned in Indus-2 for various research applications, of several are in operation and many are in installation stage. For experiments SR beam is brought in air. Due to intense flux of SR and low energy, the dose rate in the direct beam is high and there is a potential for radiation exposure. Appropriate shielding hutches are needed to house the beamlines and protect the workers from the radiation hazard. Simulations were carried out using computer code FLUKA to find out the absorbed dose in water due to SR and required shielding thickness in the forward direction to reduce dose within acceptable limits. SR spectrum from Indus-2 in the range 4-100 keV was used for simulating the absorbed dose and shielding thickness. It was found that the absorbed dose rate is of the order of 105 Gy/h for the design parameters of Indus-2 (2.5 GeV and 300 mA). Forward shielding thickness of 3 mm lead was found to be sufficient to reduce the dose rate to acceptable level for continuously occupied area (<1μSv/h). The details of the simulation and results are presented in the paper. (author)

  10. Threshold dose-rate observed by administration of tritiated water in mice for radiation risk

    International Nuclear Information System (INIS)

    This paper is the final report of the study series for the dose-rate effect of tritiated water on mice. In the present experiments, mice ([C57-BL/6N x C3H/He]F1 female) was exposed to β-rays by daily administration of tritiated drinking water throughout of life at very low dose-rates, 3.6, 0.9 and 0.2 mGy/day. When compared with the groups exposed at higher dose-rate previously reported, it was found that frequency of tumors was 70∼80% in the range from 240 mGy/day to 9.6 mGy/day and decreased to 50% as same as control with decrease in dose-rate. A linear relationship in semi-log scale was found between the life-shortening and the dose-rate, showing a threshold dose-rate. The threshold dose-rate of 3H β-rays, 2 mGy/day (0.2 mGy/day as tailing threshold dose-rate) was much lower than that of γ-rays, 15 mGy/day(2 mGy/day as tailing threshold dose-rate). In addition, it was observed that the body weight increased by exposure at low dose-rates, most markedly at 0.9 mGy/day. (author)

  11. Analysis and radiation dose rate measurement of the Al-1050 capsule on the rabbit system facility

    International Nuclear Information System (INIS)

    Aluminium is a kind of light metal with density of 2.7 gram /cm exp 3,regarding to the aluminium is characteristic such as easy to fabricated,has a good corrosion resistant and radiation heat resistant, therefore aluminum is selected to be used as a material for sample irradiation capsule with high neutron fluency. Analysis using neutron activation method and capsule irradiation by using high neutron fluency and dose radiation rate measurement was done. The analysis result show that impurities in the Al-1050 capsule are Fe, Cu, Mg, Sb, Zn, and Mn. The capsule irradiated at 15 MW during 6 Hours with neutron fluency of 2,8 x 10 exp 17 n/cm exp 2. The radiation doses rate after 24 hours decay is 220 mrad/h at 0-meter distance and 60 mrad/h at 1-meter distance. Respectively. From the analysis results and measurement show that the Al-1050 capsule has no high neutron absorption element and available to get continuing irradiation at 15 MW as far as 6 hours. Due to the personal safety, therefore the capsule handling could be carried out in the hot cell

  12. Effect of the dose rate of ionizing radiation on the dielectric properties of polyethylene and polytetrafluoroethylene

    International Nuclear Information System (INIS)

    The effect of the dose rate of γ-irradiation on the dielectric properties of LDPE and PTFE was studied. Measurements were taken for dose rates D = 10-3-1 Gy/s, and different irradiation conditins (air and vacuum). The dielectric losses (tan δ) of LDPE γ-irradiated in air with a decrease in the dose rate proportional to D-0.5 because of radiaiton-induced oxidation reaction. For irradiated PTFE, the dependence tan δ on the dose rate is determined by competition between the processes of recombination of primary radicals and their oxidation

  13. Dose-rate and humidity effects upon the gamma-radiation response of nylon-based radiachromic film dosimeters

    International Nuclear Information System (INIS)

    At dose-rates typical for 60Co gamma irradiation sources, the radiation response of hexahydroxyethyl pararosaniline cyanide/ 50μm nylon radiachromic films is dependent upon dose-rate as well as upon the moisture content of the films, or the relative humidity of the surrounding atmosphere, respectively. Under equilibrium moisture conditions, the response measured at 606 nm 24 hours after end of irradiation shows its highest dose-rate dependence at about 32 % r.h. A decrease in dose-rate from 2.8 to 0.039 Gy.s-1 results in a decrease in response by 17%. At higher humidities, the sensitivity of the film as well as the rate dependence decreases and at 86% r.h. no discernible dose-rate effect could be found. At lower humidities than 32% a flat maximum in response follows. At nominal 0% r.h. a second absorption band at 412 nm appears which is converted completely to an additional 606 nm absorption by exposure to a humid atmosphere. After that procedure the resultant response is somewhat lower than but shows almost the same dose-rate dependence as at 32% r.h. or else to eliminate the dose-rate effect by an extrapolation procedure based on the fact that the rate dependence vanishes at zero dose. (author)

  14. Influence of radiation dose and dose-rate on modification of barley seed radiosensitivity by post-treatment with caffeine

    International Nuclear Information System (INIS)

    Influence of radiation doses (100, 150 and 200 Gy) and dose-rates (1.27-0.023 Gy/Sec) on the modification of oxic and anoxic radiation damage by caffeine at different concentrations has been investigated using metabolizing barley seeds as test system. As the radiation dose increases from 100 to 200 Gy, the magnitude of oxic and anoxic damages increase at all the dose-rates. Caffeine is able to afford partial radioprotection against the oxic damage, at the same time potentiating the anoxic damage. However, caffeine effect against the oxic and anoxic components of damage depend largely upon the dose of radiation applied and also on the dose-rate used. The possible mechanism of action of caffeine in bringing about the differential modification of oxic and anoxic damages has been discussed. 19 refs., 2 tables. (author)

  15. Distributed optical fibre temperature measurements in a low dose rate radiation environment based on Rayleigh backscattering

    Science.gov (United States)

    Faustov, A.; Gussarov, A.; Wuilpart, M.; Fotiadi, A. A.; Liokumovich, L. B.; Kotov, O. I.; Zolotovskiy, I. O.; Tomashuk, A. L.; Deschoutheete, T.; Mégret, P.

    2012-04-01

    On-line monitoring of environmental conditions in nuclear facilities is becoming a more and more important problem. Standard electronic sensors are not the ideal solution due to radiation sensitivity and difficulties in installation of multiple sensors. In contrast, radiation-hard optical fibres can sustain very high radiation doses and also naturally offer multi-point or distributed monitoring of external perturbations. Multiple local electro-mechanical sensors can be replaced by just one measuring fibre. At present, there are over four hundred operational nuclear power plants (NPPs) in the world 1. Operating experience has shown that ineffective control of the ageing degradation of major NPP components can threaten plant safety and also plant life. Among those elements, cables are vital components of I&C systems in NPPs. To ensure their safe operation and predict remaining life, environmental monitoring is necessary. In particular, temperature and radiation dose are considered to be the two most important parameters. The aim of this paper is to assess experimentally the feasibility of optical fibre temperature measurements in a low doserate radiation environment, using a commercially available reflectometer based on Rayleigh backscattering. Four different fibres were installed in the Sub-Pile Room of the BR2 Material testing nuclear reactor in Mol, Belgium. This place is man-accessible during the reactor shut-down, allowing easy fibre installation. When the reactor operates, the dose-rates in the room are in a range 0.005-5 Gy/h with temperatures of 40-60 °C, depending on the location. Such a surrounding is not much different to some "hot" environments in NPPs, where I&C cables are located.

  16. Chromosomal Aberrations in DNA Repair Defective Cell Lines: Comparisons of Dose Rate and Radiation Quality

    Science.gov (United States)

    George, K. A.; Hada, M.; Patel, Z.; Huff, J.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Chromosome aberration yields were assessed in DNA double-strand break repair (DSB) deficient cells after acute doses of gamma-rays or high-LET iron nuclei, or low dose-rate (0.018 Gy/hr) gamma-rays. We studied several cell lines including fibroblasts deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase, DNA-PK activity. Chromosomes were analyzed using the fluorescence in-situ hybridization (FISH) chromosome painting method in cells at the first division post-irradiation and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma radiation induced higher yields of both simple and complex exchanges in the DSB repair defective cells than in the normal cells. The quadratic dose-response terms for both chromosome exchange types were significantly higher for the ATM and NBS defective lines than for normal fibroblasts. However, the linear dose-response term was significantly higher only for simple exchanges in the NBS cells. Large increases in the quadratic dose response terms indicate the important roles of ATM and NBS in chromatin modifications that facilitate correct DSB repair and minimize aberration formation. Differences in the response of AT and NBS deficient cells at lower doses suggests important questions about the applicability of observations of radiation sensitivity at high dose to low dose exposures. For all iron nuclei irradiated cells, regression models preferred purely linear and quadratic dose responses for simple and complex exchanges, respectively. All the DNA repair defective cell lines had lower Relative biological effectiveness (RBE) values than normal cells, the lowest being for the DNA-PK-deficient cells, which was near unity. To further

  17. Lifetime radiation risks from low-dose rate radionuclides in beagles

    International Nuclear Information System (INIS)

    One of the largest, long-term (25-yr) animal studies on the effects of low-dose internal irradiation is almost completed. Some 335 beagles were given continuous exposure to graded 90Sr [low linear energy transfer (LET)] in their diets (D-dogs) through adulthood. A second group (R-dogs) was given fractionated doses of 225Ra (high LET) as young adults. A third group of 44 was given a single injection of 90Sr as adults (S-dogs) to compare single to continuous dosages. All dogs were followed through their lifetimes. Only one of the 848 dogs is still alive. The animals were whole-body counted over their entire life span and were examined frequently for assessment of medical status. There were no acute radiation lethalities. Analyses of the large data base from these dogs have begun and preliminary indications are that 90Sr, which was tested over a 1500-fold skeletal dose rate range, does not cause significant life shortening at average accumulation skeletal doses of ∼2500 rads (25 Gy) and that a curvilinear dose response curve for life shortening was seen at higher accumulation doses. The data will be discussed in terms of modern epidemiological concepts and quantifications will be related to certain parameters of human risk from acute or chronic radiation exposures

  18. LET and dose rate effect on radiation-induced copolymerization in physical gel

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Seiko, E-mail: Nakagawa.Seiko@iri-tokyo.jp [Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10 Aomi, Koto-ku, Tokyo 135-0064 (Japan); Taguchi, Mitsumasa; Kimura, Atsushi; Nagasawa, Naotsugu; Hiroki, Akihiro [Environmental Radiation Processing Group, Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2014-09-01

    Highlights: •LET and dose rate effect on polymerization in gel was almost the same as in solution. •The ratio of the dose rate effect in the gel was higher than that in solution. •The initiation and termination processes show the difference on the dose rate effect. -- Abstract: N{sub 2}-saturated 2-propanol solutions containing styrene and maleimide were gelled by the addition of hydroxypropylcellulose and irradiated by proton, He and C-ion beams. The trend in the dose rate and LET effects on the yield and molecular weight distribution of the polymer produced in the gel was almost the same in the solution. On the contrary, the dose rate effect in the gel was higher than that in the solution. This effect was accelerated for irradiations by proton as well as heavier ion with a higher LET value.

  19. Oligodendroglial response to ionizing radiation: Dose and dose-rate response

    Energy Technology Data Exchange (ETDEWEB)

    Levy, R.P.

    1991-01-01

    An in vitro system using neuroglia from neonatal rat brain was developed to examining the morphologic, immunocytochemical and biochemical response of oligodendroglia to ionizing radiation. Following acute [gamma]-radiation at day-in-culture (DIC) 8, oligodendrocyte counts at DIC 14 were 55% to 65% of control values after 2 Gy, and 29% to 36% after 5 Gy. Counts increased to near-normal levels at DIC 21 in the 2 Gy group and to 75% of normal in the 5 Gy group. Myelin basic protein levels (MBP) at DIC 14 were 60% of control values after 2 Gy, and 40% after 5 Gy. At DIC 21, MBP after 2 Gy was 45% greater than that observed at DIC 14, but MBP, as a fraction of age-matched control values, dropped from 60% to 50%. Following 5 Gy, absolute MBP changed little between DIC 14 and DIC 21, but decreased from 40% to 25% of control cultures. It was concluded that oligodendrocytes in irradiated cultures had significantly lower functional capacity than did unirradiated controls. The response to split-dose irradiation indicated that nearly all sublethal damage in the oligodendrocyte population (and its precursors) was repaired within 3 h to 4 h. At DIC 14, the group irradiated in a single fraction had significantly lower oligodendrocyte counts than any group given split doses; all irradiated cultures had marked depression of MBP synthesis, but to significant differences referable to time interval between doses. At DIC 21, cultures irradiated at intervals of 0 h to 2 h had similar oligodendrocyte counts to one another, but these counts were significantly lower than in cultures irradiated at intervals of 4 h to 6 h; MBP levels remained depressed at DIC 21 for all irradiated cultures. The oligodendrocyte response to dose rate (0.03 to 1.97 Gy/min) was evaluated at DIC 14 and DIC 21. Exposure at 0.03 Gy/min suppressed oligodendrocyte counts at DIC 21 less than did higher dose rates in 5-Gy irradiated cultures.

  20. The radiobiological effect of intra-fraction dose-rate modulation in intensity modulated radiation therapy (IMRT)

    Science.gov (United States)

    Bewes, J. M.; Suchowerska, N.; Jackson, M.; Zhang, M.; McKenzie, D. R.

    2008-07-01

    Intensity-modulated radiation therapy (IMRT) achieves optimal dose conformity to the tumor through the use of spatially and temporally modulated radiation fields. In particular, average dose rate and instantaneous dose rate (pulse amplitude) are highly variable within a single IMRT fraction. In this study we isolate these variables and determine their impact on cell survival. Survival was assessed using a clonogenic assay. Two cell lines of differing radiosensitivity were examined: melanoma (MM576) and non-small cell lung cancer (NCI-H460). The survival fraction was observed to be independent of instantaneous dose rate. A statistically significant trend to increased survival was observed as the average dose rate was decreased, for a constant total dose. The results are relevant to IMRT practice, where average treatment times can be significantly extended to allow for movement of the multi-leaf collimator (MLC). Our in vitro study adds to the pool of theoretical evidence for the consequences of protracted treatments. We find that extended delivery times can substantially increase the cell survival. This also suggests that regional variation in the dose-rate history across a tumor, which is inherent to IMRT, will affect radiation dose efficacy.

  1. Simulation of the low-Earth-orbit dose rates using secondary radiations from the HZE particles at NIRS-HIMAC.

    Science.gov (United States)

    Yasuda, H; Suzuki, M; Ando, K; Fujitaka, K

    2001-01-01

    In order to study biological effects from cyclic dose rates encountered at the low-Earth orbit (LEO), an experimental facility was designed in the Biology room of the Heavy Ion Medical Accelerator in Chiba (NIRS-HIMAC). An incubator placed in this facility is irradiated repeatedly by secondary radiations from HZE-particle beams supplied for independent users. The daily-average dose rate (1.4 mGy d-1) measured for 223 days and short-term dose rates measured for selected beam conditions were comparable to the dose rates observed in past LEO missions. Severe solar particle events can be simulated with hourly maximum dose rate of 2.8 mGy h-1. Preliminary measurements using CR-39 and TLD indicated that the dominant LET range is less than 5 keV micrometers-1. These results demonstrate the possibility of this facility for radiobiology studies of the effects of low dose rates comparable to the LEO environment. PMID:11771537

  2. Results of radiation therapy for uterine cervical cancer using high dose rate remote after loading system

    International Nuclear Information System (INIS)

    In Japan, radiotherapy with high dose rate remote after loading system (HDR-RALS) for intracavitary brachytherapy is the standard treatment for more than 30 years. This report showed the usefulness of HDR-RALS for uterine cervical cancer. From 1980 through 1999, 442 patients with uterine cervical cancers (stage I: 66, stage II: 161, stage III: 165, stage IV: 50) were treated. Radiotherapy was performed both external teletherapy and HDR-RALS. Overall survival rate at 5 years was 60.2%. The 5-year actuarial incidence of all complications was 16.4%. The 5-year actuarial incidence of all complications in cases treated with the sum doses of whole pelvic irradiation (without central shield) and RALS up to 49 Gy, 50 to 59 Gy or larger doses were 7.5%, 11.0% and 25.2%, respectively. Radiation therapy using HDR-RALS was very effective. While the dose of whole pelvic irradiation was increased, the actuarial incidence of all complications was increased. (author)

  3. Low Dose-Rate Effects on Chromosomal Aberrations in Workers Occupationally Exposed to Ionising Radiation

    International Nuclear Information System (INIS)

    Full text: Occupational exposure to ionising radiation can be assessed by chromosomal aberrations detected in peripheral blood lymphocytes. Blood samples were collected from 47 occupationally exposed individuals (X-ray diagnostic machines and industrial gamma defectoscopy). The chromosomal aberrations were analysed from at least 500 metaphases per person and their frequencies were compared with those obtained from 110 control individuals. It has been noticed the higher frequency of chromosomal aberrations in the exposed group related to the control. The increase was analysed according to the age groups (31-40, 41-50, and 51-60), sex and duration of employment. The higher frequency of dicentrics was not directly correlated with the age or duration of employment in the exposed group. The acentric fragments were encountered with much higher frequency in the exposed group. The chromosomal aberrations induced by low dose-rate in occupationally exposed people revealed the degree of individual sensitivity and the severity of the initial damage depending on the biological-pathological conditions. (author)

  4. Daily variation of radiation dose rate after the Fukushima Nuclear Accident

    Science.gov (United States)

    Yamauchi, Masatoshi

    2015-04-01

    After the radioactive contamination of the lands from the Fukushima Nuclear Power Plant accident, the radiation dose rates observed by the dosimeters often shows daily variations, at different local times at different places or time. These variations are caused by different reasons: the temperature-dependent characteristics of the dosimeter (instrumental effect), the daily convective wind that lifts up the radioactive small particle on the ground (local effect), and the daily sea-land wind that transports the radioactive small particle from highly contaminated area (regional effect). The last type is most important in understanding the internal dose by air taking. However, while very regular patterns can easily be judged as instrumental effect, variations that strongly depend on the weather conditions are not easily judged. Combining the atmospheric electric field measurement near the ground (potential gradient, PG) with the wind and weather data, some of these unclear cases can be classified into above three reasoning, which will be shown in the presentation. Thus, the PG measurement is important right after any nuclear accidents in the future.

  5. Estimates of Radiation Dose Rates Near Large Diameter Sludge Containers in T Plant

    CERN Document Server

    Himes, D A

    2002-01-01

    Dose rates in T Plant canyon during the handling and storage of large diameter storage containers of K Basin sludge were estimated. A number of different geometries were considered from which most operational situations of interest can be constructed.

  6. High-dose rate intra-operative radiation therapy for local advanced and recurrent colorectal cancer

    International Nuclear Information System (INIS)

    In an effort to improve the local control for advanced and recurrent cancers of the rectum, we have integrated high-dose rate intra-operative radiation therapy (HDR-IORT) into the treatment program. Between 11/92 and 10/95, 47 patients (pts) were treated. There were 26 males and 21 females whose ages ranged from 30-80 (median = 62) years. There were 19 pts with primary unresectable rectal cancer, and 28 pts who were treated for recurrent rectal cancer. Histology was adenocarcinoma - 45 pts, squamous cancer - 2 pts. The range of follow-up is 1-34 months (median = 14 months). The majority of primary unresectable pts received pre-operative radiation therapy (4500-5040 cGy) with chemotherapy (5-FU with Leucovorin) 4-6 weeks later, they underwent resection + HDR-IORT (1200 cGy). For the 28 pts with recurrent cancer, the majority received surgery and HDR-IORT alone because they had received prior RT. For the pts with primary unresectable disease, actuarial 2-year local control was 77%, actuarial distant metastasis-free survival was 71%, disease free survival was 66%, and overall survival was 84%. For those pts with recurrent disease, actuarial 2-year local control rate was 65%, distant metastasis-free survival was 65%, disease free survival was 47%, and overall survival was 61%. Complications occurred in 36%. There were no cases where the anatomical distribution of disease, or technical limitations prevented the adequate delivery of HDR-IORT. We conclude that this technique was most versatile, and enabled all appropriate pts to receive IORT. The preliminary data in terms of local control are encouraging, even for the poor prognostic sub-group of pts with recurrent cancer

  7. Injury to the blood-testis barrier after low-dose-rate chronic radiation exposure in mice

    International Nuclear Information System (INIS)

    Exposure to ionising radiation induces male infertility, accompanied by increasing permeability of the blood-testis barrier. However, the effect on male fertility by low-dose-rate chronic radiation has not been investigated. In this study, the effects of low-dose-rate chronic radiation on male mice were investigated by measuring the levels of tight-junction-associated proteins (ZO-1 and occludin-1), Niemann-Pick disease type 2 protein (NPC-2) and anti-sperm antibody (AsAb) in serum. BALB/c mice were exposed to low-dose-rate radiation (3.49 mGy h-1) for total exposures of 0.02 (6 h), 0.17 (2 d) and 1.7 Gy (21 d). Based on histological examination, the diameter and epithelial depth of seminiferous tubules were significantly decreased in 1.7-Gy-irradiated mice. Compared with those of the non-irradiated group, 1.7-Gy-irradiated mice showed significantly decreased ZO-1, occludin-1 and NPC-2 protein levels, accompanied with increased serum AsAb levels. These results suggest potential blood-testis barrier injury and immune infertility in male mice exposed to low-dose-rate chronic radiation. (authors)

  8. Effect of dose rate on the radiation graft copolymerization of styrene to cellulose in the presence of acid

    International Nuclear Information System (INIS)

    At both low and high dose rates (19.5-501 krad/h), in the absence of air, the presence of certain mineral acids enhance the grafting of styrene in methanol to cellulose by the mutual irradiation technique. Sulphuric acid is the most effective of the mineral acids in enhancement. In the presence of air, acid enhances grafting at high dose rates (c. 400 krad/h). Acid can also induce a Trommsdorff peak in the grafting system or, alternatively, enhance the magnitude of the effect if it is already present. These enhanced acid effects in radiation grafting to cellulose are attributed to an increase in hydrogen atom yields. (author)

  9. Responses of rat R-1 cells to low dose rate gamma radiation and multiple daily dose fractions

    International Nuclear Information System (INIS)

    Multifraction irradiation may offer the same therapeutic gain as continuous irradiation. Therefore, a comparison of the efficacy of low dose rate irradiation and multifraction irradiation was the main objective of the experiments to be described. Both regimens were tested on rat rhabdomyosarcoma (R-1) cells in vitro and in vivo. Exponentially growing R-1 cells were treated in vitro by a multifraction irradiation procedure with dose fractions of 2 Gy gamma radiation and time intervals of 1 to 3 h. The dose rate was 1.3 Gy.min-1. The results indicate that multifractionation of the total dose is more effective with respect to cell inactivation than continuous irradiation. (Auth.)

  10. Simulation of radiation dose rate distributions around casks in ships and vehicles by using QBF code for PC-9801 computer

    International Nuclear Information System (INIS)

    The main aim of the present report is to show that the behavior of the spatial distribution of the radiation dose rate in a wide region can be easily visualized in various aspects of cask shipment even by personal computers which are very popular today, and that the QBF code system is a useful tool to perform this simulation. A great merit of using this code system is that one can easily analyze, with high reliability, roles of various important factors such as shielding structures and cask positions in the behavior of dose rate distributions. (J.P.N.)

  11. The different biological effects of single, fractioned and continuous low dose rate radiation on CL187 colorectal cancer cell line

    International Nuclear Information System (INIS)

    Objective: To investigate the effect and underlying mechanism of single, fractioned and continuous low dose rate radiation on CL187 colorectal cancer cell line. Methods: CL187 cells were exposed to 6 MV X-rays at a high dose rate of 4 Gy/min and 125I seed at a low dose rate of 2.77 cGy/h with three groups:single dose radiation group (SDR), fractioned dose radiation group (FDR) by 2 Gy/f, and continuous low dose rate radiation group (CLDR). The radiation doses were 0, 2, 4 and 8 Gy. Total cell number and cell viability were determined by trypan blue. Clone forming assay was used to evaluate the cell proliferation ability. The percentage of apoptosis cells was analyzed by flow cytometry. Western blot was used to detect the protein expression levels of PHLPP2, PTEN and Bax. Results: Compared with SDR and FDR groups, the total cell number and survival fraction of CLDR group decreased. The relative biological effect (RBE) for 125I seeds compared with 6 MV X-rays was 1.41. The percentage of apoptosis cells of CLDR group was significantly increased (t=-15.08, -11.99, P<0.05). The expression level of Bax increased in CLDR group, while no obvious changes were observed on PHLPP2 and PTEN among three groups. Conclusions: The expression level of PHLPP2 increases in SDR, FDR and CLDR group, while it seems that it was not influenced by dose rate. The expression level of Bax increased in three groups, while more colorectal CL187 cells in CLDR group may be killed due to the increase of Bax expression. (authors)

  12. Distribution of absorbed dose rate in air because of terrestrial gamma radiation in Miyako-jima, Okinawa Prefecture, Japan

    International Nuclear Information System (INIS)

    The absorbed dose rate in air because of terrestrial gamma radiation in Miyako-jima, an island that is part of Okinawa Prefecture in the subtropical region of Japan, was estimated at 637 points by in situ measurements with spectrometers equipped with 3''φ x 3''NaI(Tl) and 1''φ x 2''NaI(TL) scintillation detectors. The mean, minimum, and maximum dose rates were calculated to be about 79 nGy/h, 3 nGy/h, and 165 nGy/h, respectively. The correlation of the dose rate and geology showed that the high-rate areas (>100 nGy/h) and the distribution of the Holocene red soils (Onokoshi Clay) overlap each other. On the other hand, the low dose rates (<30 nGy/h) were mainly found in an outcrop of the Pleistocene Ryukyu Limestone, the main geologic element in the foundation of the red soils. Recent studies (e.g., Inoue et al., 1993) concluded that most of the red soils were not residuals from the base rocks, but of eolian dust ''Kosa (Yellow Sand)'' origin. These results strongly indicate that the dose rate in Miyako-jima has been enhanced as a result of eolian deposits transported mainly from the arid region of China since the last glacial epoch. (author)

  13. Gamma Radiation Measurements and Dose Rates in Commonly Used Building Materials in Cyprus

    CERN Document Server

    Michael, F; Parpottas, Y

    2010-01-01

    A first comprehensive study is presented on radioactivity concentrations and dose rates in 87 commonly used materials, manufactured or imported in Cyprus, for building purposes. The natural radioactivity of K-40, Th-232, U-238 and Ra-226 is determined using high-resolution gamma ray spectroscopy. The respective dose rates and the associated radiological effect indices are also calculated. A comparison of the measured specific activity values with the corresponding world average values shows that most of them are below the world average activity values. The annual indoor effective dose rates received by an individual from three measured imported granites and four measured imported ceramics are found to be higher than the world upper limit value of 1 mSv y-1. Hence, these materials should have a restricted use according to their corresponding calculated activity concentration index values and the related EC 1999 guidelines.

  14. Study of radon progeny distribution and radiation dose rate in the atmosphere

    International Nuclear Information System (INIS)

    The absorbed dose rate in air of airborne gamma-ray and the concentration of radon progeny in surface air have been observed continuously in Maizuru, Japan. When data observed on fine days were plotted, with dose rate as ordinate and contraction as abscissa, these points traced with a lapse of time illustrated an anticlockwise looping for each day. This result suggests that the variation of absorbed dose rate lags behind that of concentration of radon progeny; this is due to the delay time incurred as the concentration level gradually varies from ground surface to upper air. Radon progeny concentrations in precipitation and in surface air have been observed there in order to study the relationship between the two concentrations and the influence of precipitation patterns on the concentration in precipitation. Results obtained from analysis of the observed data suggest that radon progeny in precipitation originate mainly from scavenging within the cloud (rainout) and not from that below the cloud (washout). (author)

  15. Relative effect of radiation dose rate on hemopoietic and nonhemopoietic lethality of total-body irradiation

    International Nuclear Information System (INIS)

    Experiments were undertaken to determine the influence of dose rate on the toxicity of total-body irrdiation (TBI) with and without syngeneic bone-marrow rescue in mice. The results showed a much greater dose-rate dependence for death from nonhemopoietic toxicity than from bone-marrow ablation, with the ratio of LD50's increasing from 1.73 at 25 cGy/min to 2.80 at 1 cGy/min. At the higher dose rates, dose-limiting nonhemopoietic toxicity resulted from late organ injury, affecting the lungs, kidneys, and liver. At 1 cGy/min the major dose-limiting nonhemopoietic toxicity was acute gastrointestinal injury. The implications of these results in the context of TBI in preparation for bone-marrow transplantation are discussed. 15 refs., 4 figs

  16. Dose-volume effect of high dose rate interstitial radiation for tongue and mouth floor cancer

    International Nuclear Information System (INIS)

    Dose volume histograms of the high dose rate brachytherapy for 30 patients with tongue cancer and 6 patients with cancer of the mouth floor were calculated by means of PLATO. All patients were treated with HDR brachytherapy of 6 Gy per day. Twenty patients with tongue cancer and 4 patients with mouth floor cancer were treated with 60 Gy/10 fractions of HDR brachytherapy alone. Other 12 patients were treated with 20-41 Gy of external radiation and 42-60 Gy of HDR brachytherapy. V100% was defined as the volume of 6 Gy per fraction. For tongue cancer, V100% of patients treated with single plane, single plane plus one tube, double plane and volume implant were 14 cm3, 29 cm3, 18 cm3 and 64 cm3, respectively. The corresponding figures of V200% were 3 cm3, 8 cm3, 3 cm3 and 10 cm3. V100% and V200% of mouth floor cancer were 10 cm3 and 3 cm3. For patients treated with HDR brachytherapy alone, local recurrence occurred in 2 patients with small treatment volume (V100%: 9.7cm3, 11.0 cm3) and soft tissue ulcer occurred in 2 patients with large treatment volume (V100%: 25.6 cm3, 31.8 cm3). Treatment volumes of mouth floor cancer were small compared with tongue cancer patients. There were no soft tissue ulcer in 6 patients. For 10 tongue cancer patients treated with combination of external radiation and HDR brachytherapy, 6 patients were treated with single plane implant and 4 patients with volume implant. For single plane implant, V100% and V200% were 13-19 cm3 and 2.3-4.3 cm3, respectively. There were no local recurrence and no soft tissue ulcer. For volume implant, V100% and V200% were extremely high compared with other treatment. Ulcer occurred in the patient without local recurrence. It is difficult to treat these bulky tumor without late complication. Treatment volume is an important factor for both local control and late complication. (author)

  17. Bioassay in BALB/c mice exposed to low dose rate radiation

    Energy Technology Data Exchange (ETDEWEB)

    Km, Sung Dae; Gong, Eun Ji; Bae, Min Ji; Yang, Kwang Mo; Kim, Joong Sun [Dongnam Institute of Radiological and Medical Sciences, Suwon (Korea, Republic of)

    2012-09-15

    The present study was performed to investigate the toxicity of low-dose-rate irradiation in BALB/c mice. Twenty mice of each sex were randomly assigned to four groups of five mice each and were exposed to 0 (sham), 0.02, 0.2, or 2 Gy, equivalents to low-dose-rate irradiation to 3.49 mGy{center_dot}h{sup -1}. Urine, blood, and blood biochemistry were analyzed, and organ weight was measured. The low-dose-rate irradiation did not induce any toxicologically significant changes in mortality, clinical signs, body weight, food and water consumption, urinalysis, and serum biochemistry. However, the weights of reproductive organs including the testis, ovary, and uterus decreased in a dose-dependent manner. Irradiation at 2 Gy significantly decreased the testis, ovary, and uterus weights, but did not change the weights of other organs. There were no adverse effects on hematology in any irradiated group and only the number of neutrophils increased dose dependently. The low-dose-rate irradiation exposure did not cause adverse effects in mice at dose levels of 2 Gy or less, but the reproductive systems of male and female mice showed toxic effects.

  18. Bioassay in BALB/c mice exposed to low dose rate radiation

    International Nuclear Information System (INIS)

    The present study was performed to investigate the toxicity of low-dose-rate irradiation in BALB/c mice. Twenty mice of each sex were randomly assigned to four groups of five mice each and were exposed to 0 (sham), 0.02, 0.2, or 2 Gy, equivalents to low-dose-rate irradiation to 3.49 mGy·h-1. Urine, blood, and blood biochemistry were analyzed, and organ weight was measured. The low-dose-rate irradiation did not induce any toxicologically significant changes in mortality, clinical signs, body weight, food and water consumption, urinalysis, and serum biochemistry. However, the weights of reproductive organs including the testis, ovary, and uterus decreased in a dose-dependent manner. Irradiation at 2 Gy significantly decreased the testis, ovary, and uterus weights, but did not change the weights of other organs. There were no adverse effects on hematology in any irradiated group and only the number of neutrophils increased dose dependently. The low-dose-rate irradiation exposure did not cause adverse effects in mice at dose levels of 2 Gy or less, but the reproductive systems of male and female mice showed toxic effects.

  19. Genetic Factors Affecting Susceptibility to Low Dose & Low Dose-Rate Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bedford, Joel

    2014-04-18

    Our laboratory has, among other things, developed and used the gamma H2AX focus assay and other chromosomal and cell killing assays to show that differences in this DNA double strand break (dsb) related response can be clearly and distinctly demonstrated for cells which are mildly hyper-radiosensitive such as those associated with A-T heterozygosity. We have found this level of mild hypersensitivity for cells from some 20 to 30 % of apparently normal individuals and from apparently normal parents of Retinoblastoma patients. We found significant differences in gene expression in somatic cells from unaffected parents of Rb patients as compared with normal controls, suggesting that these parents may harbor some as yet unidentified genetic abnormality. In other experiments we sought to determine the extent of differences in normal human cellular reaponses to radiation depending on their irradiation in 2D monolayer vs 3D organized acinar growth conditions. We exmined cell reproductive death, chromosomal aberration induction, and the levels of γ-H2AX foci in cells after single acute gamma-ray doses and immediately after 20 hours of irradiation at a dose rate of 0.0017 Gy/min. We found no significant differences in the dose-responses of these cells under the 2D or 3D growth conditions. While this does not mean such differences cannot occur in other situations, it does mean that they do not generally or necessarily occur. In another series of studies in collaboration with Dr Chuan Li, with supprt from this current grant. We reported a role for apoptotic cell death in promoting wound healing and tissue regeneration in mice. Apoptotic cells released growth signals that stimulated the proliferation of progenitor or stem cells. In yet another collaboration with Dr, B. Chen with funds from this grant, the relative radiosensitivity to cell killing as well as chromosomal instability of 13 DNA-PKcs site-directed mutant cell lines (defective at phosphorylation sites or kinase

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

    Science.gov (United States)

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

    2010-04-01

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

  1. An international intercomparison of passive dosemeters, electronic dosemeters and dose rate meters used for environmental radiation measurements

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Thompson, I.M.G.

    1995-01-01

    To assist towards the harmonisation within the EC countries, the Eastern European countries and the USA, of the measurement of environmental dose rates from photon radiation an EC sponsored intercomparison of environmental dose rate meters, electronic dosemeters and TL dosemeters was performed...... during 1994. The intercomparison was organised by the Physikalisch Technische Bundesanstalt (PTB), Braunschweig, Germany, and by the Riso National Laboratory, Roskilde, Denmark. This paper describes the intercomparison experiments performed at the newly established Riso Natural Environmental Radiation...... Measurement Stations during the period 12 to 18 June 1994. The chief aims of the experiments were to allow the participants to check their home calibrations of their detectors and to intercompare the dosemeter responses of the individual environmental radiation measurement systems used in the USA, Eastern...

  2. Life span of mice continuously exposed to low dose rate radiation in long term and their pathological findings

    International Nuclear Information System (INIS)

    Findings in experimental animals exposed to low dose rate radiation are essential for elucidation of its biological effect because its epidemiological human studies performed in such population as the radiation handling personnel involve many unavoidable confounding factors. For the elucidation, authors have conducted an experiment with unusually low dose rate radiation in the specific-pathogen-free (SPF) mouse to see its effect on the life span and pathogenesis, of which outline is given here. All through under the SPF condition, 8 weeks old, male and female SPF mice of B6C3F1 strain were exposed to 137Cs gamma ray at 0, 0.05, 1.1 and 21 mGy/day for 400 days (a half of the average life span of the mouse) in total doses of 0, 20, 400, 800 mGy, respectively, and then maintained until death. Five hundred mice of each sex were included in one rate group, general status and body weight were checked every day, and organ weight measurement and histopathological examination were done at death. Significant shortening of life span was seen in males and females exposed at 21 and at 1.1 and 21 mGy/day, respectively, where 1.1 mGy/day is 400 times as high as the natural radiation dose rate. Major cause of death was malignant lymphoma in both sexes among 10 or more tumors observed. Between exposed and non-exposed groups, the significant increase of tumor incidence was detected in angiosarcoma and myelogenic leukemia of males at 21 mGy/day and ovarian tumor of females at the same rate. It was considered that the life span shortening was not due to the increase of specific tumor incidence by radiation but by early death by many lethal tumors. It was therefore concluded that the long-term continuous low dose rate radiation could induce the early tumorigenesis, tumor growth promotion or both. (K.T.)

  3. ALARA-based strengthening of radiation protection in a high dose rate nuclear power plant: A practical overview

    International Nuclear Information System (INIS)

    In the first years of operation the dose rates at Goesgen nuclear power plant increased more strongly than expected. Co-60 has been the main radiation contributor from the beginning. As an immediate step, investigations were initiated to find and remove unknown cobalt sources. System modifications and optimization in water chemistry were carried out to reduce material and activity transport within the primary system. As a result the dose rates were stabilized after a couple of years -unfortunately on a high level. To reduce the dose rate levels and the occupational radiation exposure, further long term measures were implemented. System decontamination and source replacement were considered as well as the implementation of enhanced shielding procedures and a more source oriented chemistry. As a result the dose rates have reduced significantly and the occupational radiation exposure has been decreased by more than a factor of 2 over the last two decades. The reduction of the mean individual dose turned out even better and was cut by a factor of 5. On terms of plant and personal safety, Goesgen nuclear power plant decided to improve radiation protection using a smooth step by step action plan and has been very successful with it. Currently the technical possibilities have been developed to a high standard. Further improvements will be selective only. In future the focus will be set to personal behavior and human performance, using enhanced target settings, briefings, debriefings, experience feedback and (international) experience exchange. Nevertheless it will be essential to avoid unnecessary administrative and counterproductive short term hurdles. Strengthening of radiation protection is and will be a long term and continuous process. Goesgen nuclear power plant will continue to introduce further actions one by one. (author)

  4. ALARA-based strengthening of radiation protection in a high dose rate nuclear power plant. A practical overview

    International Nuclear Information System (INIS)

    In the first years of operation the dose rates at Goesgen Nuclear Power Plant increased more strongly than expected. Co-60 has been the main radiation contributor from the beginning. As an immediate step, investigations were initiated to find and remove unknown cobalt sources. System modifications and optimization in water chemistry were carried out to reduce material and activity transport within the primary system. As a result the dose rates were stabilized after a couple of years - unfortunately on a high level. To reduce the dose rate levels and the occupational radiation exposure, further long term measures were implemented. System decontamination and source replacement were considered as well as the implementation of enhanced shielding procedures and a more source oriented chemistry. As a result the dose rates have reduced significantly and the occupational radiation exposure has been decreased by more than a factor of 2 over the last two decades. The reduction of the mean individual dose turned out even better and was cut by a factor of 5. On terms of plant and personal safety, Goesgen Nuclear Power Plant decided to improve Radiation Protection using a smooth step by step action plan and has been very successful with it. Currently the technical possibilities have been developed to a high standard. Further improvements will be selective only. In future the focus will be set to personal behavior and human performance, using enhanced target settings, briefings, debriefings, experience feedback and (international) experience exchange. Nevertheless it will be essential to avoid unnecessary administrative and counterproductive short term hurdles. Strengthening of Radiation Protection is and will be a long term and continuous process. Goesgen Nuclear Power Plant will continue to introduce further actions one by one. (author)

  5. Radiation chemistry of water at low dose rates with emphasis on the energy balance

    International Nuclear Information System (INIS)

    There has been considerable interest in absorbed dose water calorimetry. In order to accurately relate the temperature change to the absorbed dose, the energy balance of the overall chemistry of the system must be known. The radiolytic products and their yields are affected by dose rate, dose and added solutes. The yields of the radiolytic products have been calculated using a computer program developed at Atomic Energy of Canada. The chemical energy balance was determined as a function of dose for various dose rates and initial concentrations of hydrogen (H2), oxygen (O2), and hydrogen peroxide (H2O2). In solutions containing H2O2 or O2 and H2 the chemical reactions were exothermic; in other cases they were endothermic. Approach to equilibrium and equilbrium conditions are discussed

  6. Verification of absorbed dose rates in reference beta radiation fields: measurements with an extrapolation chamber and radiochromic film

    Energy Technology Data Exchange (ETDEWEB)

    Reynaldo, S. R. [Development Centre of Nuclear Technology, Posgraduate Course in Science and Technology of Radiations, Minerals and Materials / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Benavente C, J. A.; Da Silva, T. A., E-mail: sirr@cdtn.br [Development Centre of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Beta Secondary Standard 2 (Bss 2) provides beta radiation fields with certified values of absorbed dose to tissue and the derived operational radiation protection quantities. As part of the quality assurance, metrology laboratories are required to verify the reliability of the Bss-2 system by performing additional verification measurements. In the CDTN Calibration Laboratory, the absorbed dose rates and their angular variation in the {sup 90}Sr/{sup 90}Y and {sup 85}Kr beta radiation fields were studied. Measurements were done with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. In comparison to the certificate values provided by the Bss-2, absorbed dose rates measured with the extrapolation chamber differed from -1.4 to 2.9% for the {sup 90}Sr/{sup 90}Y and -0.3% for the {sup 85}Kr fields; their angular variation showed differences lower than 2% for incidence angles up to 40-degrees and it reached 11% for higher angles, when compared to ISO values. Measurements with the radiochromic film showed an asymmetry of the radiation field that is caused by a misalignment. Differences between the angular variations of absorbed dose rates determined by both dosimetry systems suggested that some correction factors for the extrapolation chamber that were not considered should be determined. (Author)

  7. Radiation effects of a 12-bit bipolar digital-to-analog converter under different dose rates

    International Nuclear Information System (INIS)

    Total-dose effects and room-temperature annealing behavior of bipolar digital-to-analog converter (DAC) irradiated by 60Co γ-rays were investigated. The results show that the response of the DAC is different between low- and high-dose-rate irradiation. It was found that the integrated circuits exhibit ELDRS and time dependence effect as well. Based on the space charge model, possible mechanism for this response is discussed. (authors)

  8. Measurement of absorbed dose rate of gamma radiation for lead compounds

    Science.gov (United States)

    Rudraswamy, B.; Dhananjaya, N.; Manjunatha, H. C.

    2010-07-01

    An attempt has been made to estimate the absorbed dose rate using both theoretical and measured mass energy attenuation coefficient of gamma for the lead compounds such as PbNO 3, PbCl 2, PbO 2 and PbO using various gamma sources such as 22Na (511, 1274), 137Cs (661.6), 54Mn (835) and 60Co (1173, 1332 keV).

  9. Dose-rate effects for mammary tumor development in female Sprague-Dawley rats exposed to X and γ radiation

    International Nuclear Information System (INIS)

    Mammary tumour development was followed in two experiments involving a total of 2229 female Sprague-Dawley rats exposed to various doses of X or γ rays at different dose rates. The data for another 462 rats exposed to tritiated water in one of these experiments were also analyzed. The incidence of adenocarcinomas and fibroadenomas at a given time after exposure increased linearly in proportion to total radiation dose for most groups. However, no significant increase in adenocarcinomas was observed with chronic γ exposures up to 1.1 Gy, and the increase in fibroadenomas observed with chronic gamma exposures at a dose rate of 0.0076 Gy h-1 up to an accumulated dose of 3.3 Gy was small compared to that observed after acute exposures. The incidence of all mammary tumors increased almost linearly with the log of dose rate in the range 0.0076 to 26.3 Gy h-1 for 3 Gy total dose of gamma rays. The effects of X rays appeared to be less influenced by dose rate than were the effects of γ rays. (author)

  10. Determination of background radiation

    International Nuclear Information System (INIS)

    The invention relates to a method and appartus for determining the level of background radiation in a spectral region where a Raman peak characteristic of a particular substance, in particular diamond, is expected to occur. The method includes the steps of isolating the radiation in a first spectral band, and isolating the radiation in a second spectral band which overlaps the first spectral band at least partially to form an overlapping band in the vicinity of the expected Raman Peak and a least one sideband. At least one sideband value representative of the radiation present in the one or more sidebands is then obtained, and further values, representative of the radiation isolated by any one or more of the other spectral bands, such as the first and second bands, are then used to derive a background value indicative of the level of background radiation present at the position of the expected Raman peak

  11. Effect Of Dose Rate Of Gamma Rays And Electron Beams Radiation On Bacillus Subtilis Spores In Various Conditions

    International Nuclear Information System (INIS)

    The investigation of the dose rate effect of gamma rays 60Co and electron beams radiations onto resistance of the bacteria spores has been observed. The objective of the research is to know the effect of radiation dose rates onto resistance of the bacteria spores. B. subtilis bacteria often contaminate the silk suture, human cardiac valve for the purposes of transplantation therapy and food material, so that it will be disadvantage to human health. Beside that the bacteria is well known as the most resistant to heat and ethylene oxide treatments, whereas sterilization by ethylene oxide will cause chemical residue on the sterilized materials. The bacteria spores in dry state, wet and frozen conditions in the aquadest, talc and peanut powder suspensions were irradiated with gamma rays at doses from 0 upto 10 kGy, with doses rates of 5 and 10 kGy/hrs. The sample of spores in dry and wet conditions were irradiated using electron beams at the same doses and dose rates were 5 mA/pass and 10 mA/pass. The spores of B. subtilis was cultured on Tryptone Soya Agar medium and incubated at of 32 n 2 oC for 3 days. The survival colonies were calculated and the obtained data was used to establish survival diagram in order to determine the D sub.10 value of spores. The results show that there is no difference relatively among D sub.10 values of bacteria spores irradiated in aquadest, talc or peanut powder suspensions. Nevertheless the D sub.10 (see table 1) of bacteria spores irradiated at 10 kGy/hrs gamma rays or 10 mA/pass electron beams is higher than that of at dose rate 5 kGy/hrs gamma rays or 5 mA/pass electron beams. It means that radiation at 5 kGy/hrs or 5 mA/pass is relatively more efficient than that at dose rates 10 kGy/hrs or 10 mA/pass in killing B. subtilis spores

  12. The natural radiation background

    International Nuclear Information System (INIS)

    The components of the natural background radiation and their variations are described. Cosmic radiation is a major contributor to the external dose to the human body whilst naturally-occurring radionuclides of primordial and cosmogenic origin contribute to both the external and internal doses, with the primordial radionuclides being the major contributor in both cases. Man has continually modified the radiation dose to which he has been subjected. The two traditional methods of measuring background radiation, ionisation chamber measurements and scintillation counting, are looked at and the prospect of using thermoluminescent dosimetry is considered

  13. Dose-rate models for human survival after exposure to ionizing radiation

    International Nuclear Information System (INIS)

    This paper reviews new estimates of the L50 in man by Mole and by Rotblat, the biological processes contributing to hematologic death, the collection of animal experiments dealing with hematologic death, and the use of regression analysis to make new estimates of human mortality based on all relevant animal studies. Regression analysis of animal mortality data has shown that mortality is dependent strongly on dose rate, species, body weight, and time interval over which the exposure is delivered. The model has predicted human LD50s of 194, 250, 310, and 360 rad to marrow when the exposure time is a minute, an hour, a day, and a week, respectively

  14. Dose-rate models for human survival after exposure to ionizing radiation

    International Nuclear Information System (INIS)

    This paper reviews new estimates of the LD50 in man by Mole and by Rotblat, the biological processes contributing to hematologic death, the collection of animal experiments dealing with hematologic death, and the use of regression analysis to make new estimates of human mortality based on all relevant animal studies. Regression analysis of animal mortality data has shown that mortality is dependent strongly on dose rate, species, body weight, and time interval over which the exposure is delivered. The model has predicted human LD50s of 194, 250, 310, and 360 rad to marrow when the exposure time is a minute, an hour, a day, and a week, respectively

  15. Effects of low dose-rate radiation on sperm concentration and testicular volume in crab-eating monkeys (Macaca fascicularis)

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, M.; Kitazume, M.

    1986-05-01

    Mature male crab-eating monkeys over the age of 5 years were exposed to whole-body irradiation with 1.0 (3 monkeys), 1.5 (2 monkeys), 2.5 (3 monkeys) and 4.0 Gy (1 monkey) of /sup 137/Cs gamma-rays at the dose rate of 0.18 x 10/sup -4/ Gy/min (0.024 Gy/22h/day). Immediately after semen collection, sperm number was counted and the testicular volume (V) was measured. Sperm concentrations were continuously decreased after irradiation and reached the level of minimum sperm concentration, i.e., 0.4% for 1.0 Gy and 0.1% for 1.5 Gy. Testicular volume was also decreased to 59% of pre-irradiation at 18 weeks after irradiation with 1.5 Gy. However, after irradiation with 2.5 and 4.0 Gy, sperm concentrations were very low and these doses caused azoospermia. Testicular volume decreased to 48% of pre-irradiation at 16 weeks after 2.5 Gy irradiation. The spermatogenic activity had not recovered 18 and 27 months after irradiation with 2.5 and 4.0 Gy, respectively and the previous ones, the effects of low dose-rate radiation on spermatogenic activity seem to be different from those of high dose-rate radiation.

  16. The effect of dose rate on the crystalline lamellar thickness distribution in gamma-radiation of UHMWPE

    International Nuclear Information System (INIS)

    This study develops a connection between radiation integral dose, dose rate and crystallite thickness. Samples are irradiated at an integral dose of 75 and 150 kGy and at a dose rate of 0.25 and 2.9 kGy/h. The degree of crystallinity and lamellar thickness distributions are determined from DSC. DSC shows the existence of two discrete crystalline lamellar distributions that are highly effected by irradiation protocol. It is also shown that the depth of the material from the surface also plays a role in the lamellar distribution. SAXS is then used to confirm the approximate range of lamellar thicknesses and the existence of two discrete crystallites

  17. Estimation of the method errors for deducting the response to cosmic-ray in measuring terrestrial gamma radiation dose rate

    International Nuclear Information System (INIS)

    It is needed to deduct the response to cosmic-ray from meter readings R for measuring terrestrial gamma radiation dose rate Dr by scintillation gamma dose rate meter with energy compensation. For this purpose, there are two methods, Dr,1 and Dr,2, usually adopted. The results showed that as Dr = 6.0 x 10-8 Gy·h-1, the method errors of the two deduction methods were less than 3.5 and 2.5% for single measuring point value respectively; and 2.0 and 1.5% respectively for average value from measuring points distributed uniformly over a region of altitude (from 1000 to 1500 m) respectively. The characteristics on applicability of the two methods were also discussed

  18. Radiation-chemical discussion on inverse dose-rate effect observed in radiation-induced strand breaks of plasmid DNA

    International Nuclear Information System (INIS)

    Experimental results of inverse dose-rate effect, so-called Kada Effects, which was published by Takakura and her coworkers on radiation-induced strand breaks of plasmid DNA in aerated aqueous solution, have been kinetically analyzed and discussed on the basis of radiation chemistry. the kinetic analysis indicates that there are two possible mechanisms; 1) equilibrium mixture of O2- and HO2 is responsible for strand breaks of DNA, and 2) peroxyl radical produced from citrate is effective for the strand breaks. However, the detailed kinetic analysis revealed that the latter is improbable because unimolecular decay of the peroxyl radical must be assumed to be negligible for its participation despite fast decay of analogous organic peroxyl radicals. The analysis has also given 9.93±0.10 dm3 mol-1 s-1 per nucleotide unit, which corresponds to 7.62 x 104 dm3 mol-1 s-1 per DNA molecule, as the rate constant for the reaction of the equilibrium mixture with plasmid pBR 322 DNA. Furthermore the probability that the reaction of the mixture with a nucleotide unit of DNA leads to strand breaks was obtained to be 3.36 x 10-3 for gamma-irradiated system and 1.98 x 10-3 for beta-irradiated system, respectively. (author)

  19. Influence of low-dose and low-dose-rate ionizing radiation on mutation induction in human cells

    Science.gov (United States)

    Yatagai, F.; Umebayashi, Y.; Suzuki, M.; Abe, T.; Suzuki, H.; Shimazu, T.; Ishioka, N.; Iwaki, M.; Honma, M.

    This is a review paper to introduce our recent studies on the genetic effects of low-dose and low-dose-rate ionizing radiation (IR). Human lymphoblastoid TK6 cells were exposed to γ-rays at a dose-rate of 1.2 mGy/h (total 30 mGy). The frequency of early mutations (EMs) in the thymidine kinase ( TK) gene locus was determined to be 1.7 × 10 -6, or 1.9-fold higher than the level seen in unirradated controls [Umebayashi, Y., Honma, M., Suzuki, M., Suzuki, H., Shimazu, T., Ishioka, N., Iwaki, M., Yatagai, F., Mutation induction in cultured human cells after low-dose and low-dose-rate γ-ray irradiation: detection by LOH analysis. J. Radiat. Res., 48, 7-11, 2007]. These mutants were then analyzed for loss of heterozygosity (LOH) events. Small interstitial-deletion events were restricted to the TK gene locus and were not observed in EMs in unirradated controls, but they comprised about half of the EMs (8/15) after IR exposure. Because of the low level of exposure to IR, this specific type of event cannot be considered to be the direct result of an IR-induced DNA double strand break (DSB). To better understand the effects of low-level IR exposure, the repair efficiency of site-specific chromosomal DSBs was also examined. The pre γ-irradiation under the same condition did not largely influence the efficiency of DSB repair via end-joining, but enhanced such efficiency via homologous recombination to an about 40% higher level (unpublished data). All these results suggest that DNA repair and mutagenesis can be indirectly influenced by low-dose/dose-rate IR.

  20. Experimental and Simulation of Gamma Radiation Dose Rate for High Exposure Building Material

    CERN Document Server

    Abbasi, Akbar

    2015-01-01

    Natural radioactivity concentrations in high exposure building materials are commonly used in Iran, which is measured a direct exposure by using {\\gamma}-ray spectrometry. The values for 226Ra, 232Th and 40K were in the ranges 3.8 - 94.2, 6.5 - 172.2 and 556.9 - 1539.2 Bqkg-1, respectively. The absorbed dose rates in the standard dwelling room due to 238U, 232Th series and 40K were calculated with MCNPX code. The simulation and experimental results were between 7.95 - 41.74 and 8.36 - 39.99 nGy h-1, respectively. These results were compared with experimental outing and there was overlap closely. The simulation results are able to develop for any kind of dwelling places.

  1. Natural background radiation in Jordan

    International Nuclear Information System (INIS)

    An Airborne Gamma Ray survey has been accomplished for Jordan since 1979. A complete report has been submitted to the Natural Resources Authority along with field and processed data ''digital and analogue''. Natural radioelements concentration is not provided with this report. From the corrected count rate data for each natural radioelement, Concentrations and exposure rates at the ground level were calculated. Contoured maps, showing the exposure rates and the dose rates were created. Both maps reflect the surface geology of Jordan, where the Phosphate areas are very well delineated by high-level contours. In southeastern Jordan the Ordovician sandstone, which contain high percentage of Th (around 2000 ppm in some places) and a moderate percentage of U (about 300 ppm), also show high gamma radiation exposures compared with the surrounding areas. Comparing the values of the exposure rates given in (μR/h) to those obtained from other countries such as United States, Canada, Germany, etc. Jordan shows higher background radiation which reach two folds and even more than those in these countries. More detailed studies should be performed in order to evaluate the radiological risk limits on people who are living in areas of high radiation such that the area of the phosphatic belt which covers a vast area of Jordan high Plateau. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Strom, Daniel J.

    2005-01-14

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

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

    International Nuclear Information System (INIS)

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

  4. Radiation Dose-Rate Extraction from the Camera Image of Quince 2 Robot System using Optical Character Recognition

    International Nuclear Information System (INIS)

    In the case of the Japanese Quince 2 robot system, 7 CCD/CMOS cameras were used. 2 CCD cameras of Quince robot are used for the forward and backward monitoring of the surroundings during navigation. And 2 CCD (or CMOS) cameras are used for monitoring the status of front-end and back-end motion mechanics such as flippers and crawlers. A CCD camera with wide field of view optics is used for monitoring the status of the communication (VDSL) cable reel. And another 2 CCD cameras are assigned for reading the indication value of the radiation dosimeter and the instrument. The Quince 2 robot measured radiation in the unit 2 reactor building refueling floor of the Fukushima nuclear power plant. The CCD camera with wide field-of-view (fisheye) lens reads indicator of the dosimeter loaded on the Quince 2 robot, which was sent to carry out investigating the unit 2 reactor building refueling floor situation. The camera image with gamma ray dose-rate information is transmitted to the remote control site via VDSL communication line. At the remote control site, the radiation information in the unit 2 reactor building refueling floor can be perceived by monitoring the camera image. To make up the radiation profile in the surveyed refueling floor, the gamma ray dose-rate information in the image should be converted to numerical value. In this paper, we extract the gamma ray dose-rate value in the unit 2 reactor building refueling floor using optical character recognition method

  5. Health Risks From Low Doses and Low Dose-Rates of Ionizing Radiation. Session 5: Future of Radiation Protection Regulations.

    Science.gov (United States)

    Cool, Donald A

    2016-03-01

    The system of radiological protection is a prospective approach to protection of individuals in all exposure situations. It must be applied equitably across all age groups and all populations. This is a very different circumstance from dose assessment for a particular individual where the unique characteristics of the individual and the exposure can be taken into account. Notwithstanding the ongoing discussions on the possible shape of the dose response at low doses and dose rates, the prospective system of protection has therefore historically used a linear assumption as a pragmatic, prudent and protective approach. These radiation protection criteria are not intended to be a demarcation between "safe" and "unsafe" and are the product of a risk-informed judgement that includes inputs from science, ethics, and experience. There are significant implications for different dose response relationships. A linear model allows for equal treatment of an exposure, irrespective of the previously accumulated exposure. In contrast, other models would predict different implications. Great care is therefore needed in separating the thinking around risk assessment from risk management, and prospective protection for all age groups and genders from retrospective assessment for a particular individual. In the United States, the prospective regulatory structure functions effectively because of assumptions that facilitate independent treatment of different types of exposures, and which provide pragmatic and prudent protection. While the a linear assumption may, in fact, not be consistent with the biological reality, the implications of a different regulatory model must be considered carefully. PMID:26808877

  6. Effect of different radiation dose rates on refrigerated mechanically deboned chicken meat

    International Nuclear Information System (INIS)

    Samples of mechanically deboned chicken meat (MDCM) were irradiated while frozen with doses of 0.0 kGy, 3.0 kGy - 4.04 kGy.h-1 and 3.0 kGy - 0.32 kGy.h-1. Individual lots of irradiated and non irradiated samples were evaluated for Substances Reactive to Thiobarbituric Acid (TBARS) and total count of psychotropic bacteria, while in refrigerated storage (2 ±1 deg C), for 11 days. The values for percentage of recovery for 1,1,3,3-tetraetoxipropane (TEP) and for conversion of the K value for samples irradiated with 3.0 kGy - 4.35 kGy.h-1 and 3.0 kGy - 0.3 kGy.h-1 and samples non irradiated were, respectively: 80.3 %, 70.3 % and 80.4 % and 9.1, 11.2 and 9.1. The results showed that there was not a difference for the TBARS values when irradiated and non irradiated samples were compared up to the forth day of refrigerated storage. Between the seventh and eleventh day of storage the TBARS values increased gradually when values obtained for non irradiated and those samples irradiated with doses of 3.0 kGy - 0.3 kGy.h-1 and 3.0 kGy - 4.35 kGy.h-1 were compared. The average values for psychotropic bacteria obtained for samples non irradiated and those irradiated with doses of 3.0 kGy - 0.32 kGy.h-1 and 3.0 kGy - 4.04 kGy.h-1, during the second and eleventh day of frozen storage were respectively 6.68 log (UFC.g-1), 2.87 log (UFC.g-1) and 2.66 log (UFC.g-1). When both variables were evaluated, it was verified that samples irradiated with a dose rate of 0.32 kGy.-1 presented the smallest values of TBARS than those samples irradiated with a dose rate of 4.04 kGy.h-1, from the seventh day of refrigerated storage and bacterial count within the legal limits allowed by the regulation, being considered the best dosage rate for processing MDCM, in the conditions of the present study. (author)

  7. A comparison of the biological effects of 125I seeds continuous low-dose-rate radiation and 60Co high-dose-rate gamma radiation on non-small cell lung cancer cells.

    Directory of Open Access Journals (Sweden)

    Zhongmin Wang

    Full Text Available To compare the biological effects of 125I seeds continuous low-dose-rate (CLDR radiation and 60Co γ-ray high-dose-rate (HDR radiation on non-small cell lung cancer (NSCLC cells.A549, H1299 and BEAS-2B cells were exposed to 125I seeds CLDR radiation or 60Co γ-ray HDR radiation. The survival fraction was determined using a colony-forming assay. The cell cycle progression and apoptosis were detected by flow cytometry (FCM. The expression of the apoptosis-related proteins caspase-3, cleaved-caspase-3, PARP, cleaved-PARP, BAX and Bcl-2 were detected by western blot assay.After irradiation with 125I seeds CLDR radiation, there was a lower survival fraction, more pronounced cell cycle arrest (G1 arrest and G2/M arrest in A549 and H1299 cells, respectively and a higher apoptotic ratio for A549 and H1299 cells than after 60Co γ-ray HDR radiation. Moreover, western blot assays revealed that 125I seeds CLDR radiation remarkably up-regulated the expression of Bax, cleaved-caspase-3 and cleaved-PARP proteins and down-regulated the expression of Bcl-2 proteins in A549 and H1299 cells compared with 60Co γ-ray HDR radiation. However, there was little change in the apoptotic ratio and expression of apoptosis-related proteins in normal BEAS-2B cells receiving the same treatment.125I seeds CLDR radiation led to remarkable growth inhibition of A549 and H1299 cells compared with 60Co HDR γ-ray radiation; A549 cells were the most sensitive to radiation, followed by H1299 cells. In contrast, normal BEAS-2B cells were relatively radio-resistant. The imbalance of the Bcl-2/Bax ratio and the activation of caspase-3 and PARP proteins might play a key role in the anti-proliferative effects induced by 125I seeds CLDR radiation, although other possibilities have not been excluded and will be investigated in future studies.

  8. Biological impact of high-dose and dose-rate radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Maliev, V.; Popov, D. [Russian Academy of Science, Vladicaucas (Russian Federation); Jones, J.; Gonda, S. [NASA -Johnson Space Center, Houston (United States); Prasad, K.; Viliam, C.; Haase, G. [Antioxida nt Research Institute, Premier Micronutrient Corporation, Novato (United States); Kirchin, V. [Moscow State Veterinary and Biotechnology Acade my, Moscow (Russian Federation); Rachael, C. [University Space Research Association, Colorado (United States)

    2006-07-01

    Experimental anti-radiation vaccine is a power tool of immune - prophylaxis of the acute radiation disease. Existing principles of treatment of the acute radiation dis ease are based on a correction of developing patho-physiological and biochemical processes within the first days after irradiation. Protection from radiation is built on the general principles of immunology and has two main forms - active and passive immunization. Active immunization by the essential radiation toxins of specific radiation determinant (S.D.R.) group allows significantly reduce the lethality and increase duration of life among animals that are irradiated by lethal and sub-lethal doses of gamma radiation.The radiation toxins of S.D.R. group have antigenic properties that are specific for different forms of acute radiation disease. Development of the specific and active immune reaction after intramuscular injection of radiation toxins allows optimize a manifestation of a clinical picture and stabilize laboratory parameters of the acute radiation syndromes. Passive immunization by the anti-radiation serum or preparations of immune-globulins gives a manifestation of the radioprotection effects immediately after this kind of preparation are injected into organisms of mammals. Providing passive immunization by preparations of anti-radiations immune-globulins is possible in different periods of time after radiation. Providing active immunization by preparations of S.D.R. group is possible only to achieve a prophylaxis goal and form the protection effects that start to work in 18 - 35 days after an injection of biological active S.D.R. substance has been administrated. However active and passive immunizations by essential anti-radiation toxins and preparations of gamma-globulins extracted from a hyper-immune serum of a horse have significantly different medical prescriptions for application and depend on many factors like a type of radiation, a power of radiation, absorption doses, a time of

  9. Biological impact of high-dose and dose-rate radiation exposure

    International Nuclear Information System (INIS)

    Experimental anti-radiation vaccine is a power tool of immune - prophylaxis of the acute radiation disease. Existing principles of treatment of the acute radiation dis ease are based on a correction of developing patho-physiological and biochemical processes within the first days after irradiation. Protection from radiation is built on the general principles of immunology and has two main forms - active and passive immunization. Active immunization by the essential radiation toxins of specific radiation determinant (S.D.R.) group allows significantly reduce the lethality and increase duration of life among animals that are irradiated by lethal and sub-lethal doses of gamma radiation.The radiation toxins of S.D.R. group have antigenic properties that are specific for different forms of acute radiation disease. Development of the specific and active immune reaction after intramuscular injection of radiation toxins allows optimize a manifestation of a clinical picture and stabilize laboratory parameters of the acute radiation syndromes. Passive immunization by the anti-radiation serum or preparations of immune-globulins gives a manifestation of the radioprotection effects immediately after this kind of preparation are injected into organisms of mammals. Providing passive immunization by preparations of anti-radiations immune-globulins is possible in different periods of time after radiation. Providing active immunization by preparations of S.D.R. group is possible only to achieve a prophylaxis goal and form the protection effects that start to work in 18 - 35 days after an injection of biological active S.D.R. substance has been administrated. However active and passive immunizations by essential anti-radiation toxins and preparations of gamma-globulins extracted from a hyper-immune serum of a horse have significantly different medical prescriptions for application and depend on many factors like a type of radiation, a power of radiation, absorption doses, a time of

  10. Local microwave background radiation

    OpenAIRE

    Soares, Domingos

    2006-01-01

    An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

  11. Effect Analysis on the Radiation Dose Rate of Nagasaki Atomic Bomb Survivors by Atmospheric Condition

    International Nuclear Information System (INIS)

    The Dosimetry System 2002 (DS02) had been established to evaluate the radiation doses for the atomic bomb survivors in Hiroshima and Nagasaki. The radiation effects of neutrons and gamma-rays emitted from the atomic bombs detonated at both cities were analyzed, and two types of radiation transport codes (i.e., MCNP4C and DORT) were employed in their studies. It was specifically investigated for contribution of each type of radiations to total dose. However, it is insufficient to examine the effects by various environmental factors such as weather conditions, because their calculations were only performed under certain condition at the times of the bombings. In addition, the scope of them does not include acute radiation injury of the atomic bomb survivors in spite of important information for investigating hazard of unexpected radiation accident. Therefore, this study analyzed the contribution of primary and secondary effects (i.e., skyshine and groundshine) of neutrons emitted from the Nagasaki atomic bomb. These analyses were performed through a series of radiation transport calculations by using MCNPX 2.6.0 code with variations of atmospheric density. The acute radiation injury by prompt neutrons was also evaluated as a function of distance from the hypocenter, where hypocenter is the point on the ground directly beneath the epicenter which is the burst point of the bomb in air

  12. Rat skin carcinogenesis as a basis for estimating risks at low doses and dose rates of various types of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Burns, F. J.; Vanderlaan, M.; Strickland, P.; Albert, R. E.

    1976-01-01

    The recovery rate, age dependence and latent period for tumor induction in rat skin were measured for single and split doses of radiation, and the data were analyzed in terms of a general model in an attempt to estimate the expected tumor response for various types of radiation given at low dose rates for long periods of time. The dorsal skin of male rats was exposed to electrons, x rays, or protons in either single or split doses for several doses and the tumor responses were compared during 80 weeks of observation. A two stage model incorporating a reversible or recoverable mode was developed and various parameters in the model, including recovery rate, dose-response coefficients, and indices of age sensitivity, were evaluated experimentally. The measured parameters were then utilized to calculate expected tumor responses for exposure periods extending for duration of life. The calculations indicated that low dose rates could be markedly (/sup 1///sub 100/ to /sup 1///sub 1000/) less effective in producing tumors than the same dose given in a short or acute exposure, although the magnitude of the reduction in effectiveness declines as the dose declines.

  13. Intercomparison exercise on external gamma dose rate under field conditions at the laboratory of natural radiation (Saelices el Chico, Spain)

    International Nuclear Information System (INIS)

    The last nuclear accident in Fukushima nuclear power plant has increased the necessity for measuring radiation in the environment. Therefore, radiation monitors providing results traceable throughout the country become essential and it is very important to test them under the same environmental conditions. The first intercomparison of natural radioactivity under field conditions was held in Saelices el Chico (Salamanca, Spain) in May 2011, including an exercise on environmental dose rate. This article presents the results achieved by 19 instruments belonging to 12 institutions from 7 different countries. The tested detectors are proportional counters, ionisation chambers, Geiger-Mueller and scintillators measuring dose rate in three stations with reference values from 110 to 1800 nGy h-1 All the results were given in terms of air kerma (nGy h-1) and the measurements show agreement within 25 % in all the sites. Evaluation criteria based on accuracy and statistical uncertainty were also carried out and 25 % of participants passed the test in all sites. (authors)

  14. High dose rate sup 60 Co-RALS intraluminal radiation therapy for advanced biliary tract cancer with obstructive jaundice

    Energy Technology Data Exchange (ETDEWEB)

    Tamada, Toshiaki; Yoshimura, Hitoshi; Yoshioka, Tetsuya; Iwata, Kazuro; Ohishi, Hajime; Uchida, Hideo (Nara Medical Univ., Kashihara (Japan))

    1991-12-01

    High-dose-rate intraluminal irradiation with a {sup 60}Co remote afterloading system, using our newly developed applicator, was performed in 15 cases of advanced biliary tract cancer (2 gallbladder cancers, 13 cholangiocarcinomas). The applicator which was thin with an outer diameter of 14 Fr had a double lumen which included a small lumen for a guide wire for easy exchange to a drainage tube. Therefore, the irradiation procedure could be easily finished in a short time within little distress to the patient. The tumor marker CA1 19-9 was useful in assessing the therapeutic effect and follow-up observation after treatment. The average tube-free period and survival time were 5.9 months and 8.3 months, respectively. Histopathological examination of the cases autopsied showed that the combination of intraluminal (30 Gy) and external (30 Gy) irradiation offered good local control of the cancer that was within 1 cm from the source. Cholangiocarcinoma with relatively short length of obstruction, stage III or stage IV when the cancer infiltration was localized around the bile duct, achieved a comparatively long survival time. It was suggested that the combined use of high-dose-rate intraluminal radiotherapy, with precisely delivered radical radiation to tumors localized in the bile duct wall, and external radiotherapy delivered as additional radiation to the surrounding bile duct would provide radiotherapeutic advantage and contribute to survival after treatment for advanced biliary tract cancer. (author).

  15. Effect of radiation dose rate and cyclophosphamide on pulmonary toxicity after total body irradiation in a mouse model

    International Nuclear Information System (INIS)

    Purpose: Interstitial pneumonitis (IP) is still a major complication after total body irradiation (TBI) and bone marrow transplantation (BMT). It is difficult to determine the exact role of radiation in this multifactorial complication, especially because most of the experimental work on lung damage was done using localized lung irradiation and not TBI. We have thus tested the effect of radiation dose rate and combining cyclophosphamide (CTX) with single fraction TBI on lung damage in a mouse model for BMT. Methods and Materials: TBI was given as a single fraction at a high dose rate (HDR, 0.71 Gy/min) or a low dose rate (LDR, 0.08 Gy/min). CTX (250 mg/kg) was given 24 h before TBI. Bone marrow transplantation (BMT) was performed 4-6 h after the last treatment. Lung damage was assessed using ventilation rate (VR) and lethality between 28 and 180 days (LD(50(28))-180). Results: The LD50 for lung damage, ± standard error (SE), increased from 12.0 (± 0.2) Gy using single fraction HDR to 15.8 (± 0.6) Gy using LDR. Adding CTX shifted the dose-response curves towards lower doses. The LD50 values for the combined treatment were 5.3 (± 0.2) and 3.5 (± 0.2) Gy for HDR and LDR, respectively. This indicates that the combined effect of CTX and LDR was more toxic than that of combined CTX and HDR. Lung damage evaluated by VR demonstrated two waves of VR increase. The first wave of VR increase occurred after 6 weeks using TBI only and after 3 weeks in the combined CTX-TBI treatment, irrespective of total dose or dose rate. The second wave of VR elevation resembled the IP that follows localized thoracic irradiation in its time of occurrence. Conclusions: Lung damage following TBI could be spared using LDR. However, CTX markedly enhances TBI-induced lung damage. The combination of CTX and LDR is more toxic to the lungs than combining CTX and HDR

  16. Radiation dose-rate reduction pattern in well-differentiated thyroid cancer treated with I/sup -131/

    International Nuclear Information System (INIS)

    To determine the patterns of dose rate reduction in single and multiple radioiodine (I-131) therapies in cases of well differentiated thyroid cancer patients. Study Design: Analytical series. Place and Duration of Study: Department of Nuclear Medicine and Radiation Physics, Multan Institute of Nuclear Medicine and Radiotherapy (MINAR), Multan, Pakistan, from December 2006 to December 2013. Methodology: Ninety three patients (167 therapies) with well differentiated thyroid cancer treated with different doses of I-131as an in-patient were inducted. Fifty four patients were given only single I-131 herapy dose ranging from 70 mCi (2590 MBq) to 150 mCi (5550 MBq). Thirty nine patients were treated with multiple I-131radioisotope therapy doses ranging from 80 mCi (2960 MBq) to 250 mCi (9250 MBq). T-test was applied on the sample data showed statistically significant difference between the two groups with p-value (p < 0.01) less than 0.05 taken as significant. Results: There were 68 females and 25 males with an age range of 15 to 80 years. Mean age of the patients were 36 years. Among the 93 cases of first time Radio Active Iodine (RAI) therapy, 59 cases (63%) were discharged after 48 hours. Among 39 patients who received RAI therapy second time or more, most were discharged earlier after achieving acceptable discharge dose rate i.e 25 micro r; 2 out of 39 (5%) were discharged after 48 hours. In 58% patients, given single I-131 therapy dose, majority of these were discharged after 48 hours without any major complications. Conclusion: For well differentiated thyroid cancer patients, rapid dose rate reduction is seen in patients receiving second or subsequent radioiodine (RAI) therapy, as compared to first time receiving RAI therapy. (author)

  17. Cosmic Tachyon Background Radiation

    CERN Document Server

    Tomaschitz, R

    1999-01-01

    The equilibrium statistical mechanics of a background radiation of superluminal particles is investigated, based on a vectorial wave equation for tachyons of the Proca type. The partition function, the spectral energy density, and the various thermodynamic variables of an ideal Bose gas of tachyons in an open Robertson-Walker cosmology are derived. The negative mass square in the wave equation changes the frequency scaling in the Rayleigh-Jeans law, and there are also significant changes in the low temperature regime as compared to the microwave background, in particular in the caloric and thermal equations of state.

  18. Determination of scattered gamma radiation in the calibration of environmental dose rate meters

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Hedemann Jensen, P.

    1992-01-01

    the detector responses. Insignificant differences of the order of 1 % between the results for the two geometries were found both experimentally and theoretically. It is thus concluded that the scattered radiation from surrounding buildings farther away than around 15 m from a calibration set......-up contributes negligibly to the detector response relative to that from ground and air. Shadow-shield measurements were used to deduce the contribution to the response from the scattered radiation in free-field geometries and the experimentally obtained results were found to agree agree extremely well with...

  19. Radiation therapy for localized prostate cancer. For high-dose rate conformal brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kinugawa, Keigo; Jo, Yoshimasa; Morioka, Masaaki; Tanaka, Hiroyoshi; Hiratsuka, Junichi; Imajo, Yoshinari [Kawasaki Medical School, Kurashiki, Okayama (Japan)

    1999-05-01

    Sixteen patients with localized prostate cancer were referred to our clinic for radiation therapy in combination with HDR brachytherapy using Ir-192 pellets between October 1997 and August 1998. The patients were given external beam radiation of 45 Gy to the whole pelvis in combination with an interstitial HDR brachytherapy implant of 3 fractions each delivering 5.5 Gy during two days. Using an implanting device especially designed for HDR, 10-18 applicator needles (17 gauge) were implanted into the prostate using transrectal ultrasound (TRUS) with perineal template guidance under spinal anesthesia. Pathological evaluation was performed at 6 months after treatment. This technique of external beam radiation combined with HDR brachytherapy was well tolerated. Serum prostatic antigen (PSA) levels became normalized in 87.5% of the patients (14 out of 16) within 1-14 months (median 2 months) after the irradiation. No significant intraoperative or perioperative complications occurred, however one patient (6.25%) experienced Grade 3 hematuria. Most of the early complications were otherwise Grade 1 or 2. From prospectively planned prostatic rebiopsies performed at 6 months, we can observe the radiation effects in the pathological findings such as fibrosis, basal cell hyperplasia, bizarre cells and intraductal calcifications. (K.H.)

  20. The importance of fluence rate in photodynamic therapy: is there a parallel with ionizing radiation dose-rate effects?

    International Nuclear Information System (INIS)

    Several similarities can be found between dose-rate effects in radiotherapy and fluence-rate effects in photodynamic therapy (PDT). At low dose rates repair of sublethal damage can occur, whereas at high dose rates oxygen depletion can decrease the effects of both therapies. The available literature for fluence-rate effects in PDT is discussed here in relation to therapeutic implications

  1. Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures

    International Nuclear Information System (INIS)

    Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of the present study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection in fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff were compared to radiation doses collected when the radiation dose rates were displayed. When the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose (Hp(10)) per procedure decreased from 68 to 28 μSv (p = 0.003) for this cardiologist and from 4.3 to 2.5 μSv (p = 0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection. (paper)

  2. Electronic dose conversion technique using a NaI(Tl) detector for assessment of exposure dose rate from environmental radiation

    International Nuclear Information System (INIS)

    An electronic dose conversion technique to assess the exposure dose rate due to environmental radiation especially from terrestrial sources was developed. For a 2 x 2 inch cylindrical NaI(Tl) scintillation detector, pulse-height spectra were obtained for gamma-rays of energy up to 3 MeV by Monte Carlo simulation. Based on the simulation results and the experimentally fitted energy resolution, dose conversion factors were calculated by a numerical decomposition method. These calculated dose conversion factors were, then, electronically implemented to a developed dose conversion unit (DCU) which is a microprocessor-controlled single channel analyzer (SCA) with variable discrimination levels. The simulated spectra were confirmed by measurement of several monoenergetic gamma spectra with a multichannel analyzer (MCA). The converted exposure dose rates from the implemented dose conversion algorithm in the DCU were also evaluated for a field test in the vicinity of the nuclear power plant at Kori as well as for several standard sources, and the results were in good agreement with separate measurement by a high pressure ionization chamber (HPIC) within a 6.4% deviation

  3. Life span of C57 mice as influenced by radiation dose, dose rate, and age at exposure

    International Nuclear Information System (INIS)

    This study was designed to measure the life shortening of C57BL/6J male mice as a result of exposure to five external doses from 60Co gamma radiation delivered at six different dose rates. Total doses ranged from 20 to 1620 rad at exposure rates ranging from 0.7 to 36,000 R/day. The ages of the mice at exposure were newborn, 2, 6, or 15 months. Two replications were completed. Although death was the primary endpoint, we did perform gross necropsies. The life span findings are variable, but we found no consistent shortening compared to control life spans. Therefore, we cannot logically extrapolate life shortening to lower doses, from the data we have obtained. In general, the younger the animals were at the beginning of exposure, the longer their life spans were compared to those of controls. This relationship weakened at the higher doses and dose rates, as mice in these categories tended not to have significantly different life spans from controls. Using life span as a criterion, we find this study suggests that some threshold dosage may exist beyond which effects of external irradiation may be manifested. Up to this threshold, there is no shortening effect on life span compared to that of control mice. Our results are in general agreement with the results of other researchers investigating human and other animal life span effects on irradiation

  4. Knowledge on radiation dose-rate for risk communication on nuclear power plants

    International Nuclear Information System (INIS)

    The sense of anxiety on radiation after Fukushima Dai-ichi accident has not disappeared because of the nightmare scenario on radiation cultivated through the Cold War era starting at the atomic bomb dropping at Hiroshima and Nagasaki. In the present paper, from the viewpoint of establishing the social acceptance of nuclear power plants as well as new reasonable regulation, biological defense in depth (production of anti-oxidants, DNA repair, cell death/apoptosis, and immune defense mechanisms) found in a few decades are presented in comparison with the linear no-threshold (LNT) model for the induction of cancer in the range up to 100 mSv (as single or annual doses) applied for the present regulation. (author)

  5. Oligodendroglial response to ionizing radiation: Dose and dose-rate response

    International Nuclear Information System (INIS)

    An in vitro system using neuroglia from neonatal rat brain was developed to examine the morphologic, immunocytochemical and biochemical response of oligodendroglia to ionizing radiation. Following acute γ-irradiation at day-in-culture (DIC) 8, oligodendrocyte counts at DIC 14 were 55% to 65% of control values after 2 Gy, and 29% to 36% after 5 Gy. Counts increased to near-normal levels at DIC 21 in the 2 Gy group and to 75% of normal in the 5 Gy group. Myelin basic protein levels (MBP) at DIC 14 were 60% of control values after 2 Gy, and 40% after 5 Gy. At DIC 21, MBP after 2 Gy was 45% greater than that observed at DIC 14, but MBP, as a fraction of age-matched control values, dropped from 60% to 50%. Following 5 Gy, absolute MBP changed little between DIC 14 and DIC 21, but decreased from 40% to 25% of control cultures. The response to split-dose irradiation indicated that nearly all sublethal damage in the oligodendrocyte population (and its precursors) was repaired within 3 h to 4 h. A new compartmental cell model for radiation response in vitro of the oligodendrocyte population is proposed and examined in relation to the potential reaction to radiation injury in the brain

  6. Survival of tumor bearing mice by sequencing of low dose rate (LDR) neutron and photon radiation

    International Nuclear Information System (INIS)

    Cf-252 neutron radiation (NT) has been shown to be effective therapy for bulky, hypoxic human tumor and to produce consistent rapid clearance and 5 year cures. NT has been found to be more or less effective depending upon the schedule in which it is used and upon mixing with photon radiation. In an effort to study this scheduling and photon effect, LSA tumor was irradiated in vivo in a hypoxic, advanced state, in different schedules in combination of NT with Co-60 photons. The LSA lymphoma of C57BL/ym mice represents an accurate system to assess dose-response of tumor cells in vivo. Mean survival time was used as endpoint. A high RBE for LDR Cf-252 NT was observed with a RBE(n) of -- 5.0. The effect was not greatly sensitive to sequence in which photons were used. Comparison studies were also tested relative to LDR Cs-137 photon radiation. The results support the high efficacy of LDR NT for destruction of hypoxic tumor in vivo

  7. Oligodendroglial response to ionizing radiation: Dose and dose-rate response

    Energy Technology Data Exchange (ETDEWEB)

    Levy, R.P.

    1991-12-01

    An in vitro system using neuroglia from neonatal rat brain was developed to examine the morphologic, immunocytochemical and biochemical response of oligodendroglia to ionizing radiation. Following acute {gamma}-irradiation at day-in-culture (DIC) 8, oligodendrocyte counts at DIC 14 were 55% to 65% of control values after 2 Gy, and 29% to 36% after 5 Gy. Counts increased to near-normal levels at DIC 21 in the 2 Gy group and to 75% of normal in the 5 Gy group. Myelin basic protein levels (MBP) at DIC 14 were 60% of control values after 2 Gy, and 40% after 5 Gy. At DIC 21, MBP after 2 Gy was 45% greater than that observed at DIC 14, but MBP, as a fraction of age-matched control values, dropped from 60% to 50%. Following 5 Gy, absolute MBP changed little between DIC 14 and DIC 21, but decreased from 40% to 25% of control cultures. The response to split-dose irradiation indicated that nearly all sublethal damage in the oligodendrocyte population (and its precursors) was repaired within 3 h to 4 h. A new compartmental cell model for radiation response in vitro of the oligodendrocyte population is proposed and examined in relation to the potential reaction to radiation injury in the brain.

  8. Measurement of radiocesium concentration in trees using cumulative gamma radiation dose rate detection systems - A simple presumption for radiocesium concentration in living woods using glass-badge based gamma radiation dose rate detection system

    Energy Technology Data Exchange (ETDEWEB)

    Yoshihara, T.; Hashida, S.N. [Plant Molecular Biology, Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194 (Japan); Kawachi, N.; Suzui, N.; Yin, Y.G.; Fujimaki, S. [Radiotracer Imaging Gr., Quantum Beam Science Center, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Nagao, Y.; Yamaguchi, M. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2014-07-01

    Radiocesium from the severe accident at the Fukushima Dai-ichi Nuclear Power Plant on 11 March 2011 contaminates large areas. After this, a doubt for forest products, especially of mushroom, is indelible at the areas. Pruned woody parts and litters are containing a considerable amount of radiocesium, and generates a problem at incineration and composting. These mean that more attentive survey for each subject is expected; however, the present survey system is highly laborious/expensive and/or non-effective for this purpose. On the other hand, we can see a glass-badge based gamma radiation dose rate detection system. This system always utilized to detect a personal cumulative radiation dose, and thus, it is not suitable to separate a radiation from a specific object. However, if we can separate a radiation from a specific object and relate it with the own radiocesium concentration, it would enable us to presume the specific concentration with just an easy monitoring but without a destruction of the target nature and a complicated process including sampling, pre-treatment, and detection. Here, we present the concept of the measurement and results of the trials. First, we set glass-badges (type FS, Chiyoda Technol Corp., Japan) on a part of bough (approximately 10 cm in diameter) of Japanese flowering cherry trees (Prunus x yedoensis cv. Somei-Yoshino) with four different settings: A, a direct setting without any shield; B, a setting with an aluminum shield between bough and the glass-badge; C, a setting with a lead shield between bough and the glass-badge; D, a setting with a lead shield covering the glass-badge to shut the radiation from the surrounding but from bough. The deduction between the amount of each setting should separate a specific radiation of the bough from unlimited radiation from the surrounding. Even if the hourly dose rate is not enough to count the difference, a moderate cumulative dose would clear the difference. In fact, results demonstrated a

  9. Dose rate effects in the radiation damage of the plastic scintillators of the CMS Hadron Endcap Calorimeter

    CERN Document Server

    ,

    2016-01-01

    We present measurements of the reduction of light output by plastic scintillators irradiated in the CMS detector during the 8 TeV run of the Large Hadron Collider and show that they indicate a strong dose rate effect. The damage for a given dose is larger for lower dose rate exposures. The results agree with previous measurements of dose rate effects, but are stronger due to the very low dose rates probed. We show that the scaling with dose rate is consistent with that expected from diffusion effects.

  10. Epidemiological studies in high background radiation areas

    International Nuclear Information System (INIS)

    Below the doses of 100-200 mSv of radiation exposure, no acute health effect is observed, and the late health effects such as cancer are yet unclear. The problems making the risk evaluation of low dose radiation exposure difficult are the fact that the magnitude of expected health effects are small even if the risk is assumed to increase in proportion to radiation doses. As a result, studies need to be large particular when dealing with rare disease such as cancer. In addition, the expected health effects are so small that they can easily be masked by lifestyles and environmental factors including smoking. This paper will discuss cancer risk possibly associated with low-dose and low-dose rate radiation exposure, describing epidemiological studies on the residents in the high-background radiation areas. (author)

  11. Fourth IRMF comparison of calibrations of portable gamma-ray dose- rate monitors 2001-2002 Ionising radiation

    CERN Document Server

    Lewis, V E

    2002-01-01

    The Ionising Radiations Metrology Forum (IRMF) organised a fourth comparison of calibrations of gamma-ray dose-rate monitors in which fifteen establishments in the UK participated. The exercise involved the circulation of three gamma-ray monitors for calibration in the fields produced using sup 1 sup 3 sup 7 Cs, sup 2 sup 4 sup 1 Am and sup 6 sup 0 Co. The instruments used were an Electra with MC 20 probe, a Mini-Instruments Mini-rad 1000 and a Siemens electronic personal dosemeter Mk 2 (EPD). The responses relative to 'true' dose equivalent rate were calculated by the individual participants and submitted to the for analysis along with details of the facilities and fields employed. Details of the estimated uncertainties were also reported. The results are compared and demonstrate generally satisfactory agreement between the participating establishments. However, the participants' treatment of uncertainties needs improvement and demonstrates a need for guidance in this area.

  12. Remote Background Radiation Monitoring Using Zigbee Technology

    Directory of Open Access Journals (Sweden)

    Hamisu A. Adamu

    2014-03-01

    Full Text Available In this paper, a solution of remote background radiation monitoring, based on the concept of Wireless Sensor Network (WSN, is presented. Radiation dose rate measured by the sensor node is sent to the monitoring station through ZigBee wireless network operated on 2.4 GHz unlicensed Industrial Scientific Medical (ISM band. The system is calibrated for use for ionizing radiation dose rate range of between naturally occurring background radiation and 1.02 mSv/h. Power consumption of the sensor node is kept low by operating the node ZigBee radio with low duty cycle: i.e by keeping the radio awake only during data transmission/reception. Two ATmega8 microcontrollers, one each for sensor node and the monitoring station, are programmed to perform interfacing, data processing, and control functions. The system range of coverage is 124m for outdoor (line of site deployment and 56.8m for indoor application where 5 brick walls separated the sensor node and the monitoring station. Range of coverage of the system is extendable via the use of ZigBee router(s.

  13. Ruthenium-106 brachytherapy for thick uveal melanoma: reappraisal of apex and base dose radiation and dose rate

    Science.gov (United States)

    Jaberi, Ramin; Sedaghat, Ahad; Azma, Zohreh; Nojomi, Marzieh; Falavarjani, Khalil Ghasemi; Nazari, Hossein

    2016-01-01

    Purpose To evaluate the outcomes of ruthenium-106 (106Ru) brachytherapy in terms of radiation parameters in patients with thick uveal melanomas. Material and methods Medical records of 51 patients with thick (thickness ≥ 7 mm and < 11 mm) uveal melanoma treated with 106Ru brachytherapy during a ten-year period were reviewed. Radiation parameters, tumor regression, best corrected visual acuity (BCVA), and treatment-related complications were assessed. Results Fifty one eyes of 51 consecutive patients including 25 men and 26 women with a mean age of 50.5 ± 15.2 years were enrolled. Patients were followed for 36.1 ± 26.5 months (mean ± SD). Mean radiation dose to tumor apex and to sclera were 71 (± 19.2) Gy and 1269 (± 168.2) Gy. Radiation dose rates to tumor apex and to sclera were 0.37 (± 0.14) Gy/h and 6.44 (± 1.50) Gy/h. Globe preservation was achieved in 82.4%. Preoperative mean tumor thickness of 8.1 (± 0.9) mm decreased to 4.5 (± 1.6) mm, 3.4 (± 1.4) mm, and 3.0 (± 1.46) mm at 12, 24, and 48 months after brachytherapy (p = 0.03). Four eyes that did not show regression after 6 months of brachytherapy were enucleated. Secondary enucleation was performed in 5 eyes because of tumor recurrence or neovascular glaucoma. Tumor recurrence was evident in 6 (11.8%) patients. Mean Log MAR (magnification requirement) visual acuity declined from 0.75 (± 0.63) to 0.94 (± 0.5) (p = 0.04). Best corrected visual acuity of 20/200 or worse was recorded in 37% of the patients at the time of diagnosis and 61.7% of the patients at last exam (p = 0.04). Non-proliferative and proliferative radiation-induced retinopathy was observed in 20 and 7 eyes. Conclusions Thick uveal melanomas are amenable to 106Ru brachytherapy with less than recommended apex radiation dose and dose rates. PMID:26985199

  14. Soil radioactivity and radiation absorbed dose rates at roadsides in high-traffic density areas in Ibadan metropolis, southwestern Nigeria

    International Nuclear Information System (INIS)

    The effect of ionising of ionising radiation on biological systems depends among other factors on time and place of exposure and population involved. Socio-economic factors in human daily activities have subjected humans to certain environmental health risks. In most cases the risk appears to be higher outdoors than indoors. In order to quantify the radiation exposure levels to individuals in the outdoors in areas with high human and vehicular densities, roadside soil samples were collected from major bus stops and round-about in the metropolis of Ibadan and were analysed for their activity concentration levels using gamma-ray spectrometry. The 40K activity concentration ranged between 96.1 and 336.5 Bq kg-1 with a mean of 219.8 ± 71.4 Bq kg-1; 238U was in the range of 10.2-40.7 Bq kg-1 with a mean of 20.3 ± 6.9 Bq kg-1 while that of 232Th ranged between 13.3 and 29.7 Bq kg-1 with a mean of 21.2 ± 5.3 Bq kg-1. The total gamma absorbed dose rates in air ranged between 17.2 and 41.8 nGy h-1 with an average of 32.0 ± 5.8 nGy h-1. The gamma absorbed dose rates at the roadsides in traffic density areas were found to be lower when compared with previously reported values in natural and undisturbed locations in non-traffic density areas in the city. (authors)

  15. Radiation shielding and dose rate evaluation at the interim storage facility for spent fuel from Cernavoda NPP

    International Nuclear Information System (INIS)

    At present studies necessary to license the Interim Storage Facility for the Spent Fuel (CANDU type) from Cernavoda NPP are developed in our country.The spent fuel from Cernavoda NPP is discharged into Spent Fuel Bay in Service Building of the plant, where it remains several years for cooling. After this period, the bundles of spent fuel are to be transferred to the Interim Storage Facility.The dry interim storage solution seems to be the most appropriate variant for Cernavoda NPP.The design of the Spent Fuel Interim Storage Facility must meet the applicable safety requirements in order to ensure radiological protection of the personnel, public and environment during all phases of the facility achievement. In this paper we intend to present the calculation of radiation shielding at the spent fuel interim storage facility for two technical solutions: - Concrete Monolithic Module and Concrete Storage Cask. In order to quantify the fuel composition after irradiation, the isotope generation and depletion code ORIGEN 2.1 has been used, taking into account a cooling time of 7 years and 9 years, respectively, for these two variants. The shielding calculations have been performed using the computer codes QAD-5K and MICROSHIELD-4. The evaluations refer only to gamma radiation because the resulting neutron source (from (α,n) reactions and spontaneous fission) is insignificant as compared to the gamma source. The final results consist in the minimum thickness of the shielding and the corresponding external dose rates, ensuring a design average dose rate based on national and international regulations. (authors)

  16. Analysis of dose-rate effects on cellular responses to chronic radiation exposure

    International Nuclear Information System (INIS)

    The effects in the title were studied on their expression of various genes concerned with radiation exposure by the acute (1 Gy/min) and chronic (0.007-0.694 Gy/min) irradiations to various cell lines. Cell of human origin were the primarily cultured fibroblasts (F), their immortalized strain (imF) by transduction of human teromerase transcriptase (hTERT), breast cancer MCF-7, osteosarcoma U-20S, colon cancer HCT-116 and T-cell leukemia Jurkat. Acute irradiation was done in a gamma-cell with Cs-137 gamma-ray and chronic one, in a CO2-incubator with the Cs-137 source. Expression of genes was analyzed by mRNA sequence with Genome Analyzer. Proteins of p53, p53-Ser15-P, murine double minute 2 (MDM2), p21 and a/b-tubulin were analyzed by Western blotting. D0 values of acute irradiation were found in the range of 1.1-1.4 Gy, suggesting the similar sensitivity of used cells. However, responses to chronic exposure were different from cells to cells: particularly, at 0.347 mGy/min, no effect on growth was observed in cancer-derived cells until 10 days whereas a marked growth inhibition of F and imF cells was seen after 4 days. Arrest of proliferation of F cells after 10 days exposure at 0.347 mGy/min was tentative, but at 0.694 mGy/min, it was irreversible dependently on the exposure time. They were arrested at G0 stage. Gene expression analyzed by mRNA sequence was shown to be changed even by the lowest rate 0.007 mGy/min: levels of protein expressed under control of cancer-suppressing p53 were markedly altered. Western blotting showed an increased expression of examined proteins except for p53, at higher dose than 0.069 mGy/min. Results indicated that the cellular response to radiation involved not only DNA damage but also the process of yielding the damage. (T.T.)

  17. Peculiarities of occurrence and progress of border-line conditions under low radiation dose rate impact

    International Nuclear Information System (INIS)

    In past years more and more attention is drawn to condition of psychic health of population groups working under unhealthy labor conditions. In relation to this there were studied peculiarities of occurrence and progress of affective disorder at Institute of Atomic Energy of the National Nuclear Center of the Republic of Kazakhstan employees. The study conducted showed high level of affective disorder occurrence and intensity of asthenia manifestations in a number of cases prevailing, in essence, affective disorders. Where at asthenia disorders do not correlate with the intensity of somatic background. It is necessary to note that environment factors played considerable role in formation of depression in the examined persons. Investigation results indicate the necessity to elaborate large prophylactic, therapeutic and rehabilitation actions for persons, that are deemed mentally healthy and not needing psychiatric help, for the purpose of detection and elimination of erased affective disorders. In the field of mental disease prophylaxis the group of disorders determined as 'pre-disease' or 'border-line variants of psychic health' are of interest. (author)

  18. Radiation and Reason Why radiation at modest dose rates is quite harmless and current radiation safety regulations are flawed

    CERN Document Server

    CERN. Geneva

    2013-01-01

    Data on the impact of ionising radiation on life are examined in the light of evolutionary biology. This comparison confirms that fear of nuclear radiation is not justified by science itself; rather it originates in a failure of public trust in nuclear science, a relic of the international politics of the Cold War era. Current ionisation safety regulations appease this fear but without scientific support and they need fundamental reformulation. This should change the reaction to accidents like Fukushima, the cost of nuclear energy and the application of nuclear technology to the supply of food and fresh water. Such a boost to the world economy would require that more citizens study and appreciate the science involved – and then tell others -- not as much fun as the Higgs, perhaps, but no less important! www.radiationandreason.com

  19. Study of the radiation levels in low dose rate brachytherapy zones of the National Institute of Neoplastic Illnesses

    International Nuclear Information System (INIS)

    The present study has as objective to evaluate the radiation levels of the Brachytherapy work areas of low dose rate (Gammateque, nurses station and of hospitalization rooms of patients RIC of 4th, 5th Floor-East) and to estimate the effective dose of the occupationally exposed personnel and the public in general. The measurements of the dose rate in these areas, were registered with a radiations monitor Inspector trademark, during a period of 60 days, without altering the routinary work conditions. The more high levels of environmental dose equivalent rate registered in the different work areas its are of 1.41 and 47.78 μSv/h rooms 1 and 2 in the Gammateque environments, in the hospitalization rooms of the 4th and 5th floor in the point 1 are of 40.77 and 23.67, μSv/h respectively and in the point 2 are of 129.19 and 39.93, μSv/h respectively, and in the nurses station of the 4th and 5th floor its are respectively of 7.62 u Sv/h and 0.45 u Sv/h. According to the carried out measurements and the permanency in the work place is possible to estimate the effective dose involved to the occupationally exposed personnel. The personnel that works in Gammateque could be receiving respectively as maximum dose 0.61 mSv/month, and the personnel that works in the nurses station of 13.17 and 0.78 mSv/year in the 4th and 5th floor. These registered differences among the two floors are due to that the 5th floor counts with the shielding systems (screen) contrary to the 4th, another of the factors is the distribution form of the patient beds RIC. We should have present that the radiation levels although in some cases it is very high, however, they are below of the permissible limits according to standards, but it is still possible to reduce even more, the radiation levels in the critical points fulfilling with the ALARA principle. (Author)

  20. Integrated Molecular Analysis Indicates Undetectable Change in DNA Damage in Mice after Continuous Irradiation at ~ 400-fold Natural Background Radiation

    OpenAIRE

    Olipitz, Werner; Wiktor-Brown, Dominika; Shuga, Joe; Pang, Bo; McFaline, Jose; Lonkar, Pallavi; Thomas, Aline; Mutamba, James T; Greenberger, Joel S.; Samson, Leona D.; Dedon, Peter C; Yanch, Jacquelyn C.; Engelward, Bevin P.

    2012-01-01

    Background: In the event of a nuclear accident, people are exposed to elevated levels of continuous low dose-rate radiation. Nevertheless, most of the literature describes the biological effects of acute radiation. Objectives: DNA damage and mutations are well established for their carcinogenic effects. We assessed several key markers of DNA damage and DNA damage responses in mice exposed to low dose-rate radiation to reveal potential genotoxic effects associated with low dose-rate radiation....

  1. Dose and dose rate monitor

    International Nuclear Information System (INIS)

    The methods are discussea of measuring dose rate or dose using a scintillation counte. A plastic scintillator based on polystyrene with PBD and POPOP activators and coated with ZnS(Ag) was chosen for the projected monitor. The scintillators were cylindrical and spherical in shape and of different sizes; black polypropylene tubes were chosen as the best case for the probs. For the counter with different plastic scintillators, the statistical error 2σ for natural background was determined. For determining the suitable thickness of the ZnS(Ag) layer the energy dependence of the counter was measured. Radioisotopes 137Cs, 241Am and 109Cd were chosen as radiation sources. The best suited ZnS(Ag) thickness was found to be 0.5 μm. Experiments were carried out to determine the directional dependence of the detector response and the signal to noise ratio. The temperature dependence of the detector response and its compensation were studied, as were the time stability and fatigue manifestations of the photomultiplier. The design of a laboratory prototype of a dose rate and dose monitor is described. Block diagrams are given of the various functional parts of the instrument. The designed instrument is easiiy portable, battery powered, measures dose rates from natural background in the range of five orders, i.e., 10-2 to 103 nGy/s, and allows to determine a dose of up to 10 mGy. Accouracy of measurement in the energy range of 50 keV to 1 MeV is better than +-20%. (E.S.)

  2. Enhancement of viability of radiosensitive (PBMC) and resistant (MDA-MB-231) clones in low-dose-rate cobalt-60 radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, Patricia Lima, E-mail: patricialfalcao@gmail.com [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil); Motta, Barbara Miranda; Lima, Fernanda Castro de; Lima, Celso Vieira; Campos, Tarcisio Passos Ribeiro [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2015-05-15

    Objective: in the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231) cells line and radiosensitive peripheral blood mononuclear cells (PBMC), as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and methods: the cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min{sup -1} and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB-231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48-72 hours post-radiation. Conclusion: low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer. (author)

  3. D.C.-electrical conductivity as a method for monitoring radiation curing of unsaturated polyester resins. Pt. 2: Influence of electrical field and dose rate

    International Nuclear Information System (INIS)

    The course of radiation cross linking of unsaturated polyester resins was followed by measuring electrical conductivity change. Both the electrical field strength and dose rate influenced the crosslinking. The electrical field somewhat increased the reaction rate possibly due to the orientation of a polar polyester chains. To investigate the effect of electrical field, the samples were irradiated to different doses at different field strengths, from 2.5 to 250 kV/m and then extracted in benzene to determine the extent of crosslinking. The extraction analysis of irradiated samples confirmed the influence of electrical field observed in conductivity measurements. The electrical field effect depended on the dose rate. Three dose rates were applied 3.05, 0.354 and 0.096 kGy/h. The medium dose rate gave the highest reaction rate (on dose scale). Faster decrease of free styrene content with radiation dose than increase of gel content at higher dose rate implies partial styrene grafting or homopolymerization. The higher the electrical field, the more pronounced were the effects of dose rate. (Author)

  4. Enhancement of viability of radiosensitive (PBMC and resistant (MDA-MB-231 clones in low-dose-rate cobalt-60 radiation therapy

    Directory of Open Access Journals (Sweden)

    Patrícia Lima Falcão

    2015-06-01

    Full Text Available Abstract Objective: In the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231 cells line and radiosensitive peripheral blood mononuclear cells (PBMC, as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and Methods: The cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min–1 and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: Radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB- 231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48–72 hours post-radiation. Conclusion: Low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer.

  5. Measurement of natural radioactivity and dose rate assessment of terrestrial gamma radiation in the soil of southern Punjab, Pakistan

    International Nuclear Information System (INIS)

    Activity concentrations of 226Ra, 232Th, 40K and 137Cs in soil samples collected from the most populous area of southern Punjab of Pakistan have been measured by gamma-ray spectrometry. The measured activity concentrations for these radionuclides are compared with the reported data from different other countries and it is found that measured activity concentrations are comparable with the worldwide measured average values reported by the UNSCEAR. Subsequently assessed radiological effects show that the mean radium equivalent activity (Raeq) is 96.7 ± 15.2 Bq kg-1 and air absorbed dose rate (D) is 46.1 ± 7.3 nGy h-1. The values of internal and external radiation hazard indices are found to be less than unity. The annual effective radiation dose is calculated to be 0.28 ± 0.05 mSv, which is well below the limit of 1.0 mSv y-1 recommended by the International Commission on Radiological Protection, for the general public. (authors)

  6. Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident

    International Nuclear Information System (INIS)

    The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium (134Cs and 137Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h−1 (1.2 mGy d−1), even 3 years after

  7. Frequency of chromosome aberration and dose/dose rate effects in the mouse exposed to long-term low dose radiation

    International Nuclear Information System (INIS)

    Authors have been conducting long term irradiation experiments in the mouse with the dose rate as low as unreported hitherto and have shown with highly sensitive methods to detect chromosomal aberration, that there is the positive dose rate effect under even such a condition, of which details are described herein. According to the definition of United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCER) (1993), the low dose rate is 137Cs-gamma-ray at the low dose rate of 1 or 20 mGy/22 h/day (total, 125-615 or 100-8000 mGy, respectively). Other groups received radiations of 0 Gy (non-irradiated, age-matched control), 200-8000 mGy at 200 mGy/22 h/day, 400-8000 mGy at 400 mGy/22 h/day, or 250-2000 mGy at 890 mGy/min. At the defined days after exposure, mice were sacrificed, their spleens were dissected out, splenic cells were cultured for 48 hr, and their chromosome specimens were prepared to be stained with Giemsa or FISH (fluorescence in situ hybridization). Dicentric (dic) and translocation chromosomal aberrations were found to increase even with the lowest total (accumulated) dose, where the frequency was significantly higher than that in control. Comparison of the regression slopes at each dose rate of the relation between dose and aberration revealed the difference dependent on the rate, thus demonstrating the presence of dose rate effect. Dose/dose rate effect factor (DDREF) calculated by authors' procedure (at 1000-100 mGy: DDREF=17.8-4.5 for dic by FISH; 24.5-5.2 for dic+ring chromosome by Giemsa) was thought important in the risk assessment of low dose radiation and also revealed a problem in International Commission on Radiological Protection (ICRP) (1991) calculation of the factor. (K.T.)

  8. A review of data on the effects of low and low dose-rate radiation with special reference to the dose limit problem

    International Nuclear Information System (INIS)

    This is a review of data pertaining to detection and quantification of the effects after exposure to low LET radiations delivered at low and low dose-rate, i.e., at a level of maximum permissible dose for the radiation workers, on experimental materials ranging from plant to rodents and on some human populations. Irradiation at a dose of a few rad is reported to induce mutation or malignant transformation in some selected model systems, with a linear dose-effect relationship. Moreover, the incidence of the chromosome aberrations in spermatocytes is reported to be elevated in the scorpiones (Tityus bahiensis) collected in a region of high natural background radiations (several rem/year). An increase in the incidence of childhood malignancies is reported among children exposed in utero to diagnostic X-rays. Appreciable increase in the incidence of genetic diseases due possibly to chromosome aberrations is also reported among population living in a region of high natural background radiations. Points are raised and discussed as to the interpretation and particularly application of these data to the estimation of somatic and genetic risks of human population from man-made radiations. Recent attempts of risk-benefit analysis with populations subjected to mass X-ray examination of the chest and stomac are referred to. Since we are unaware of the actual injuries due to the exposure even at the level of radiation workers (5 rem/year), it is out of the capacity of a biologist to afford the basis for the decision of limiting the exposure of general population due to the light water reactor operation to 5 mrem/year. (auth.)

  9. Changes in the Number of Double-Strand DNA Breaks in Chinese Hamster V79 Cells Exposed to γ-Radiation with Different Dose Rates

    Directory of Open Access Journals (Sweden)

    Andreyan N. Osipov

    2013-07-01

    Full Text Available A comparative investigation of the induction of double-strand DNA breaks (DSBs in the Chinese hamster V79 cells by γ-radiation at dose rates of 1, 10 and 400 mGy/min (doses ranged from 0.36 to 4.32 Gy was performed. The acute radiation exposure at a dose rate of 400 mGy/min resulted in the linear dose-dependent increase of the γ-H2AX foci formation. The dose-response curve for the acute exposure was well described by a linear function y = 1.22 + 19.7x, where “y” is an average number of γ-H2AX foci per a cell and “x” is the absorbed dose (Gy. The dose rate reduction down to 10 mGy/min lead to a decreased number of γ-H2AX foci, as well as to a change of the dose-response relationship. Thus, the foci number up to 1.44 Gy increased and reached the “plateau” area between 1.44 and 4.32 Gy. There was only a slight increase of the γ-H2AX foci number (up to 7 in cells after the protracted exposure (up to 72 h to ionizing radiation at a dose rate of 1 mGy/min. Similar effects of the varying dose rates were obtained when DNA damage was assessed using the comet assay. In general, our results show that the reduction of the radiation dose rate resulted in a significant decrease of DSBs per cell per an absorbed dose.

  10. Evaluation of background ionising radiation levels within Gwagwalada town, Abuja

    International Nuclear Information System (INIS)

    The background ionising radiation levels within Gwagwalada Town, Abuja has been carried out using Atomtex 1117M Radiation Monitor. Readings were taken in twelve different locations. Twenty different readings were taken at each location and the mean equivalent dose rate was used to calculate the annual equivalent dose rate. A total of 240 measurements were taken across the 12 locations in the study Area. It was observed that the average dose equivalent varied from 0.105±0.008 μSv/h to 0.114±0.015μSv/h with a mean of 0.109±0.013 μSv/h. The mean value from Ungwan Bassa shows the highest equivalent dose rate while the equivalent dose rate from Phase 3 was the lowest. Ungwan Dodo, Ungwan Gwari recorded the second and third highest in-situ gamma radiation of 0.113±0.013 μSv/h and 0.112±0.012 μSv/h respectively. The result shows that the entire equivalent dose rates of all the locations were below the value of the Standard Background Radiation of 0.133 μSv/h. The study also revealed that the average annual equivalent dose rate is 0.192±0.005 mSv/y which is lower than the value of 1.0 mSv/yr averaged over five consecutive years according to the dose limit recommended by the International Commission on Radiological Protection (ICRP).

  11. Low doses effects and gamma radiations low dose rates; Les effets des faibles doses et des faibles debits de doses de rayons gamma

    Energy Technology Data Exchange (ETDEWEB)

    Averbeck, D. [Institut Curie, CNRS UMR 2027, 75 - Paris (France)

    1999-07-01

    This expose wishes for bringing some definitions and base facts relative to the problematics of low doses effects and low dose rates effects. It shows some already used methods and some actual experimental approaches by focusing on the effects of ionizing radiations with a low linear energy transfer. (N.C.)

  12. Intensity-modulated radiation therapy for pancreatic and prostate cancer using pulsed low–dose rate delivery techniques

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie; Lang, Jinyi; Wang, Pei; Kang, Shengwei [Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu (China); Lin, Mu-han; Chen, Xiaoming [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Chen, Fu; Guo, Ming [Department of Radiation Oncology, Eye Ear Nose and Throat Hospital of Fudan University, Shanghai (China); Chen, Lili [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Ma, Chang-Ming Charlie, E-mail: charlie.ma@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States)

    2014-01-01

    Reirradiation of patients who were previously treated with radiotherapy is vastly challenging. Pulsed low–dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while providing significant tumor control for recurrent cancers. This work investigates treatment planning techniques for intensity-modulated radiation therapy (IMRT)-based PLDR treatment of various sites, including cases with pancreatic and prostate cancer. A total of 20 patients with clinical recurrence were selected for this study, including 10 cases with pancreatic cancer and 10 with prostate cancer. Large variations in the target volume were included to test the ability of IMRT using the existing treatment planning system and optimization algorithm to deliver uniform doses in individual gantry angles/fields for PLDR treatments. Treatment plans were generated with 10 gantry angles using the step-and-shoot IMRT delivery technique, which can be delivered in 3-minute intervals to achieve an effective low dose rate of 6.7 cGy/min. Instead of dose constraints on critical structures, ring structures were mainly used in PLDR-IMRT optimization. In this study, the PLDR-IMRT plans were compared with the PLDR-3-dimensional conformal radiation therapy (3DCRT) plans and the PLDR-RapidArc plans. For the 10 cases with pancreatic cancer that were investigated, the mean planning target volume (PTV) dose for each gantry angle in the PLDR-IMRT plans ranged from 17.6 to 22.4 cGy. The maximum doses ranged between 22.9 and 34.8 cGy. The minimum doses ranged from 8.2 to 17.5 cGy. For the 10 cases with prostate cancer that were investigated, the mean PTV doses for individual gantry angles ranged from 18.8 to 22.6 cGy. The maximum doses per gantry angle were between 24.0 and 34.7 cGy. The minimum doses per gantry angle ranged from 4.4 to 17.4 cGy. A significant reduction in the organ at risk (OAR) dose was observed with the PLDR-IMRT plan when compared with that using the PLDR-3DCRT

  13. Intensity-modulated radiation therapy for pancreatic and prostate cancer using pulsed low–dose rate delivery techniques

    International Nuclear Information System (INIS)

    Reirradiation of patients who were previously treated with radiotherapy is vastly challenging. Pulsed low–dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while providing significant tumor control for recurrent cancers. This work investigates treatment planning techniques for intensity-modulated radiation therapy (IMRT)-based PLDR treatment of various sites, including cases with pancreatic and prostate cancer. A total of 20 patients with clinical recurrence were selected for this study, including 10 cases with pancreatic cancer and 10 with prostate cancer. Large variations in the target volume were included to test the ability of IMRT using the existing treatment planning system and optimization algorithm to deliver uniform doses in individual gantry angles/fields for PLDR treatments. Treatment plans were generated with 10 gantry angles using the step-and-shoot IMRT delivery technique, which can be delivered in 3-minute intervals to achieve an effective low dose rate of 6.7 cGy/min. Instead of dose constraints on critical structures, ring structures were mainly used in PLDR-IMRT optimization. In this study, the PLDR-IMRT plans were compared with the PLDR-3-dimensional conformal radiation therapy (3DCRT) plans and the PLDR-RapidArc plans. For the 10 cases with pancreatic cancer that were investigated, the mean planning target volume (PTV) dose for each gantry angle in the PLDR-IMRT plans ranged from 17.6 to 22.4 cGy. The maximum doses ranged between 22.9 and 34.8 cGy. The minimum doses ranged from 8.2 to 17.5 cGy. For the 10 cases with prostate cancer that were investigated, the mean PTV doses for individual gantry angles ranged from 18.8 to 22.6 cGy. The maximum doses per gantry angle were between 24.0 and 34.7 cGy. The minimum doses per gantry angle ranged from 4.4 to 17.4 cGy. A significant reduction in the organ at risk (OAR) dose was observed with the PLDR-IMRT plan when compared with that using the PLDR-3DCRT

  14. A dosimetric study of polyethylene glycol hydrogel in 200 prostate cancer patients treated with high-dose rate brachytherapy ± intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy. Materials and methods: Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy ± intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10 mL PEG hydrogel (DuraSeal™ Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5 mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate, rectal, and bladder doses and prostate–rectal distances were calculated based upon treatment planning CT scans. Results: There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate–rectal separation (mean ± SD, 12 ± 4 mm with gel vs. 4 ± 2 mm without gel, p < 0.001) and significantly decreased the mean rectal D2 mL (47 ± 9% with gel vs. 60 ± 8% without gel, p < 0.001). Gel decreased rectal doses regardless of body mass index (BMI). Conclusions: PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12 mm and led to a significant reduction in rectal radiation doses, regardless of BMI

  15. Preliminary results of concurrent chemotherapy and radiation therapy using high-dose-rate brachytherapy for cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Ja; Lee, Ji Hye; Lee, Re Na; Suh, Hyun Suk [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    2006-09-15

    To determine the efficacy and safety of concurrent chemotherapy and radiation therapy with high-dose-rate brachytherapy for cervical cancer. From January 2001 to December 2002, 30 patients with cervical cancer were treated with concurrent chemotherapy (cisplatin and 5-FU) and definitive radiation therapy. The median age was 58 (range 34 {approx} 74) year old. The pathology of the biopsy sections was squamous cell carcinoma in 29 patients and one was adenocarcinoma. The distribution to FIGO staging system was as follow: stage IB, 7 (23%); IIA, 3 (10%); IIB, 12 (40%); IIIA, 3 (10%); IIIB, 5 (17%). All patients received pelvic external beam irradiation (EBRT) to a total dose of 45 {approx} 50.4 Gy (median: 50.4 Gy) over 5 {approx} 5.5 weeks. Ir-192 HDR intracavity brachytherapy (ICBT) was given after a total dose of 41.1 Gy. HDR-ICBT was performed twice a week, with a fraction point. A dose of 4 Gy and median dose to point A was 28 Gy (range: 16 {approx} 32 Gy) in 7 fractions. The median cumulative biologic effective dose (BED) at point A (EBRT + ICBT) was 88 Gy{sub 10} (range:77 {approx} 94 Gy{sub 10}). The median cumulative BED at ICRU 38 reference point (EBRT + ICBT) was 131 Gy{sub 3} (range: 122 {approx} 140 Gy{sub 3}) at point A, 109 Gy{sub 3} (range:88{approx} 125 Gy{sub 3}) at the rectum and 111 Gy{sub 3} (range: 91 {approx} 123 Gy{sub 3}) at the urinary bladder. Cisplatin (60 mg/m{sup 2}) and 5-FU (1,000 mg/m{sup 2}) was administered intravenously at 2 weeks interval from the first day of radiation for median 5 (range:2 {approx} 6) cycles. The assessment was performed at 1 month after completion of radiation therapy by clinical examination and CT scan. The median follow-up time was 36 months (range:8{approx} 50 months). The complete response rate after concurrent chemo radiation therapy was 93.3%. The 3-yr actuarial pelvic control rate was 87% and 3-yr actuarial overall survival and disease-free survival rate was 93% and 87%, respectively. The local failure

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

    Science.gov (United States)

    Liniecki, J

    1989-01-01

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

  17. Effect of absorbed dose rate of ionizing radiation on decomposition of rare earth nitrates disposed in porous corundum foam

    International Nuclear Information System (INIS)

    The influence of irradiation with different dose rates on the process of rare earth nitrate (neodymium) decomposition on corundum foam was studied. By the method of thermal analysis it has been shown that irradiation decreases the temperature of decomposition of neodymium nitrate, while growth of the dose rate increases the depth of Nd(NO3)3·nH2O decomposition process(including denitration). The presence of x-phase of Al2O3 in the samples facilitates irreversible immobilization of fission products, decreasing considerably the temperature of matrix interaction with applied neodymium nitrate with formation of NdAlO3 phase. 5 refs., 3 figs

  18. Late biological effects of ionizing radiation as influenced by dose, dose rate, age at exposure and genetic sensitivity to neoplastic transformation

    International Nuclear Information System (INIS)

    A most comprehensive investigation is in progress at the Los Alamos Scientific Laboratory to study the late biological effects of whole-body exposure to gamma irradiation as they may be influenced by total dose, dose rate, age at exposure and genetic background. Strain C57B1/6J mice of four age groups (newborn, 2, 6 and l5 months) were given five doses (20, 60, 180, 540, and 1620 rads) of gamma rays, with each dose being delivered at six dose rates (0.7, 2.1, 6.3, 18.9, 56.7 rads/day and 25 rads/min). Forty to sixty mice were used in each of the approximately 119 dose/dose-rate and age combinations. The study was done in two replications with an equal number of mice per replicaton. Strain RF/J mice were used in a companion study to investigate the influence of genetic background on the type and magnitude of effect. Results of the first and second replications of the l5-month-old age group and data on the influence of genetic background on biological response have been completed, and the results show no significant life shortening within the dose and dose-rate range used. It was also concluded that radiaton-induced neoplastic transformaton was significantly greater in mice with a known genetic sensitivity to neoplastic disease than in mammals which do not normally have a significant incidence of tumours. (author)

  19. Effect of dose rate, temperature and impurity content on the radiation damage in the electron irradiated NaCl crystals

    NARCIS (Netherlands)

    Dubinko, V.I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    2000-01-01

    The dependencies of void formation and radiolytic sodium accumulation on the irradiation dose, dose rate, temperature and impurity content are analyzed within a framework of a theoretical model, which is based on a new mechanism of dislocation climb. The mechanism involves the production of V-F cent

  20. Low-dose-rate high-let radiation cytogenetic effects on mice in vivo as model of space radiation action on mammalian

    Science.gov (United States)

    Sorokina, Svetlana; Zaichkina, Svetlana; Rozanova, Olga; Aptikaeva, Gella; Romanchenko, Sergei; Smirnova, Helene; Dyukina, Alsu; Peleshko, Vladimir

    At present time little is known concerning the biological effects of low-dose-rate high-LET radiation exposure in space. The currently available experimental data on the biological effect of low doses of chronic radiation with high-LET values, which occur under the conditions of aircraft and space flights, have been primarily obtained in the examinations of pilots and astronauts after flights. Another way of obtaining this kind of evidence is the simulation of irradiation conditions during aircraft and space flights on high-energy accelerators and the conduction of large-scale experiments on animals under these conditions on Earth. In the present work, we investigated the cytogenetic effects of low-dose-rate high-LET radiation in the dose ranges of 0.2-30 cGy (1 cGy/day) and 0.5-16 cGy (0.43 cGy/day) in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons that simulates the spectral and component composition of radiation fields formed in the conditions of high-altitude flights on SHK mice in vivo. The dose dependence, adaptive response (AR) and the growth of solid tumor were examined. For induction of AR, two groups of mice were exposed to adapting doses of 0.2-30 cGy and the doses of 0.5-16 cGy of high-LET radiation. For comparison, third group of mice from unirradiated males was chronically irradiated with X-rays at adapting doses of 10 cGy (1 cGy/day). After a day, the mice of all groups were exposed to a challenging dose of 1.5 Gy of X-rays (1 Gy/min). After 28 h, the animals of all groups were killed by the method of cervical dislocation. Bone marrow specimens for calculating micronuclei (MN) in polychromatic erythrocytes (PCE) were prepared by a conventional method with minor modifications. The influence of adapting dose of 16 cGy on the growth of solid tumor of Ehrlich ascite carcinoma was estimated by measuring the size of the tumor at different times after the inoculation of ascitic cells s.c. into the femur. It was

  1. The Cosmic Background Radiation

    OpenAIRE

    Smoot, George; Scott, Douglas

    1997-01-01

    We review the current status of experimental data for spectral distortions and angular anisotropies of the cosmic microwave background, as well as discussing the relevant physical processes. This is one of a number of new articles in astrophysics and cosmology which will appear in the 1996 Review of Particle Properties (Phys. Rev. D. in press). Other relevant reviews include: "Big-Bang Cosmology" by K.A. Olive; "Big-Bang Nucleosynthesis" by K.A. Olive & D.N. Schramm; "The Hubble Constant" by ...

  2. Influence of dose, dose rate, and radiation quality on radiation carcinogenesis and life shortening in RFM and BALB/C mice

    International Nuclear Information System (INIS)

    The effects produced by 137Cs gamma rays delivered at a high (45 rads/min) or intermediate (8.2 rads/day) dose rate and the effect of fission neutrons at a high (25 rads/min) and low (1 rad/day) rate in a population of nearly 30,000 RFM and 11,000 BALB/c mice have been studied. Gamma ray doses ranged from 10 to 400 rads with the RFM's and from 50-400 rads with the BALB/c's, while neutron doses ranged from 5 to 200 rads with both strains. The present paper will present an overview of these data and the general findings while subsequent publications will present detailed analyses of each aspect. A variety of neoplasms were sensitive to induction after radiation exposure, including tumors of both reticular tissue origin (leukemia, lymphoma, etc.) and solid tumors. For the RFM, thymic lymphomas were the dominant reticular tissue neoplasm while the majority of solid tumors were either lung adenomas or fit into the broad category of endocrine related tumors, including ovarian, pituitary, harderian, and uterine tumors. The BALB/c was much less sensitive to induction of reticular tissue neoplasms. The tumors that were most sensitive to induction included malignant lung carcinomas, mammary adenocarcinomas and ovarian tumors. In general for both life shortening and tumor induction after gamma ray exposures, when the low to intermediate dose range was sufficiently defined, linearity could be rejected and a dose squared or linear-dose squared relationship adequately fit the data. For neutron exposures, on the other hand, linear relationships were the general finding. The RBE for neutrons varied with tumor type and total dose level. For gamma ray irradiation, the intermediate dose rate resulted in a decreased effectiveness in all cases, while for neutron exposures the dose rate relationships were more complex

  3. Correlation between regional oncological mortality and natural radiation background in the CSR

    International Nuclear Information System (INIS)

    On the basis of published geological data (maps) an attempt was made to correlate the regional distribution of oncological mortality with the dose rate of the natural radiation background in the Czech Socialist Republic. No relationship was observed between the two parameters in the whole area of the CSR; for districts with an increased dose rate of the background or with high mortality the statistical relationship proved an inverse relationship: the higher the background dose rate the lower the oncological mortality and vice versa. (author). 3 figs., 1 tab., 22 refs

  4. Endophytic fungi of the Genus Penicillium isolated of Platypodium elegans from environments of high dose rate of ionizing radiation

    International Nuclear Information System (INIS)

    The present work had as objective to isolate and to identify endophytic microorganisms and were exposed to stress situations, using for this ionizing radiations, these highly mutagen and in high doses, lethal to all the alive organisms. The endophytic microorganisms were obtained the starting from the species arboreal Platypodium elegans Vog., one of them developed in radioactive land in the area of Ipora/Go and other, developed in land Background in the city of Abadia de Goias/GO. The rates of dose of environmental radiation were shown sharply different, being in Ipora (Anomaly 2) with a value of approximately 140 μR/h and in Abadia de Goias with approximately 20 μR/H, both measured the area of root of the tree close to. Tests through PCR-RAPD were accomplished with the isolated ones, for verification of the similarity of its genetic characteristics and possible polymorphism among its DNA's . The isolated ones were studied with relationship to the effects of the gamma radiation, being used as source 60 Co, with doses of 25 to 2131 Gy. These lineages had the same behavior practically with relationship to the resistance of the gamma radiation, declining strongly at levels of approximately 700 Gy. The isolated ones tested were identified at microscope for morphology, being of the Genus Penicillium, with the same genetic characteristics in agreement with PCR/RAPD, being just observed a polymorphism area in its DNA's. In spite of a lineage to have been isolated of a tree developed in radioactive land, any difference was observed among its resistance to the gamma radiation in comparison to the isolated lineage of tree developed in land radiometric background. (author)

  5. Dose-rate and the reciprocity law: TL response of Ge-doped SiO2 optical fibers at therapeutic radiation doses

    International Nuclear Information System (INIS)

    An investigation has been made on commercially available Ge-doped SiO2 optical fibers as a novel thermoluminescence system for radiotherapy dosimetry. This dosimeter has previously been shown by the group to provide sensitive dosimetry over a wide range of electron and photon dose, suitable for the needs of radiotherapy. In addition the optical fiber offers small physical size (125 μm diameter) and hence high spatial resolution. The reciprocity between thermoluminescence (TL) yield of Ge-doped SiO2 optical fibers and dose has been investigated for fixed radiation dose for a range of photon and electron dose rates. For electron beams of nominal energies in the range of 9-20 MeV, we have investigated the TL response of these fibers for dose rates between 100 and 1000 cGy min-1. For photon beams of nominal energies in the range of 6-15 MV, we have used dose rates of 100-600 cGy min-1. Reproducibility and fading at fixed absorbed dose (3 Gy) and dose rate for the optical fibers were also investigated. At fixed dose rates, the TL optical fibers were found to produce a flat TL yield within 4% (1σ) and 3% (1σ) for electron and photon beams, respectively. The optical fibers demonstrated good reproducibility (±1.5%), low residual signal for a readout temperature of 300 oC and negligible fading. A weak dependence on dose-rate has been observed in the range of 3.4-3.9% for electrons (with an associated uncertainty of 4%) and 2.4-2.9% for photons (with an associated uncertainty of <4%). For electron and photon energies we note a consistent trend towards lower response in the TL yield of between 3.4-3.9% and 2.4-2.7%, respectively, at the higher dose rates in comparison with the response at lower dose rates. In addition we note an appreciable systematic energy dependence for both electron and photon beams. It is important to take such factors into account for providing precise and accurate radiotherapy dosimetry. It is also apparent that the optical fibers can be re

  6. An insight in to effect of dose, dose rate and confounding factors on radiation induced DNA damage and repair using comet assay

    International Nuclear Information System (INIS)

    Ionizing radiation is known to induce a variety of DNA lesions such as single strand breaks (SSBs), double strand breaks (DSBs), and oxidative damage to bases, interstrand cross-links and locally multiplies damaged sites (LMDs). However, the most dangerous DNA lesions which are responsible for the origin of lethal effects, mutagenesis, genomic instability and carcinogenesis are the DSBs and LMDs. Humans are at high risk of exposure to low doses of ionizing radiation either through environmental or occupational exposures. It is known that following exposure to doses below 10 cGy mammalian cells adapt to subsequent higher doses of ionizing radiation exposures a phenomenon known as adaptive response. Neither the changes induced by low dose ionizing radiation nor the biochemical pathways that signal this low dose radiation effect are well studied. The genetic effect of ionizing radiation depends on the radiation dose as well as on the dose rate at which it is delivered. The radiation induced cellular effects such as chromosome aberrations, sister chromatid exchange, micronucleus formation, transformation, mutations and changes in gene expression can cause cancer, cell death or damage can transmitted to subsequent generations. Contradictory reports exist in literature about variation in genetic response as function of dose and dose rates. There are different methods available to detect the DNA damage such as Neutral and Alkaline elution assay, DNA unwinding assay, Comet assay, Halo assay, FISH-comet assay, gamma-H2AX. Comet assay is a valuable technique which allows detection of DNA damage and repair at single cell level and provides a unique opportunity to investigate intercellular differences in any eukaryotic cell population. Thus, there is need to evaluate the utility and accuracy of different techniques used for estimation of radiation induced DNA damage. Here, we report our observations on the effect of low-dose, low dose rates, low dose limit, type of radiation

  7. Use of three-dimensional radiation therapy planning tools and intraoperative ultrasound to evaluate high dose rate prostate brachytherapy implants

    International Nuclear Information System (INIS)

    Purpose: We performed a pilot study to evaluate the quality of high dose rate (HDR) prostate implants using a new technique combining intraoperative real-time ultrasound images with a commercially available 3-dimensional radiation therapy planning (3D RTP) system. Methods and Materials: Twenty HDR prostate implants performed by four different physicians on a phase I/II protocol were evaluated retrospectively. Radiation therapy (RT) consisted of pelvic external beam RT (EBRT) to a dose of 46 Gy in 2-Gy fractions over 5 weeks and 2 HDR implants (prescribed dose of 950 cGy per implant). Our in-house real-time geometric optimization technique was used in all patients. Each HDR treatment was delivered without moving the patient. Ultrasound image sets were acquired immediately after needle placement and just prior to HDR treatment. The ultrasound image sets, needle and source positions and dwell times were imported into a commercial computerized tomography (CT) based 3D RTP system. Prostate contours were outlined manually caudad to cephalad. Dose-volume histograms (DVHs) of the prostate were evaluated for each implant. Results: Four patients with stage T2a carcinoma, 4 with stage T2b, and 3 with stage T1c were studied. The median number of needles used per implant was 16 (range 14-18). The median treated volume of the implant (volume of tissue covered by the 100% isodose surface) was 82.6 cc (range 52.6-96.3 cc). The median target volume based on the contours entered in the 3D RTP system was 44.83 cc (range 28.5-67.45 cc). The calculated minimum dose to the target volume was 70% of the prescribed dose (range 45-97%). On average 92% of the target volume received the prescribed dose (range 75-99%). The mean homogeneity index (fraction of the target volume receiving between 1.0 to 1.5 times the prescribed dose) was 80% or 0.8 (range 0.55-0.9). These results compare favorably to recent studies of permanent implants which report a minimum target volume dose of 43% (range 29

  8. Dose Rate Effects in Linear Bipolar Transistors

    Science.gov (United States)

    Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis

    2011-01-01

    Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.

  9. The influence of dose rate, irradiation temperature and post-irradiation storage conditions on the radiation response of Harwell Amber 3042 PMMA dosimeters

    International Nuclear Information System (INIS)

    The response of routine dosimeters is not independent of radiation dose rate, and environmental conditions such as humidity and temperature. In Harwell Amber 3042 dosimeters these influences are minimised by careful conditioning, and the use of special packaging material to maintain humidity. This paper describes studies carried out on the influences of irradiation dose rate and temperature, on two batches of dosimeters. Firstly, this paper gives gamma irradiation response data for dose rates of 6.1, 1.3 and 0.5 Gy·s-1 with irradiation temperatures of 20, 30, 40 and 50 deg. C. Dosimeters were irradiated, to doses of 3, 5, 7, 10 and 15 kGy. Secondly, this paper considers irradiation plus post irradiation storage temperatures, at a fixed dose rate of 1.5 Gy·s-1. Dosimeters were irradiated, to doses of 10 and 20 kGy; at temperatures of 30, 40 and 50 deg. C. The dosimeters were stored at these temperatures for 1, 24 and 48 hours before measurement. Results at both of the recommended measurement wavelengths, 603 nm and 651 nm, are presented. The choice of wavelength is discussed, in order to aid the optimum choice for the conditions prevailing. (author)

  10. Evaluation on radiation features of the KUR deuterium neutron irradiation equipment. Neutron energy spectra and neutron- and gamma-ray absorption dose rate

    International Nuclear Information System (INIS)

    The deuterium irradiation equipment at reactor for research in Kyoto University (KUR) was reformed at main aim of upgrading of neutron capture therapy (NCT) from November, 1995 to March, 1996. Neutron energy spectra at reference radiation position evaluated on a partial radiation mode by multiple activated foil method, was introduced. As a result of carrying out a simulation calculation using two dimensional transmission calculation supposing medical radiation using the obtained spectra, experimental results could be followed satisfactorily in total. And, comparison with differential absorption dose rate measured by using twin-type ionization box and semiconductor detector for medical probe was also carried out. (G.K.)

  11. Impact of dose rate on accuracy of intensity modulated radiation therapy plan delivery using the pretreatment portal dosimetry quality assurance and setting up the workflow at hospital levels

    OpenAIRE

    Karunakaran Kaviarasu; N Arunai Nambi Raj; Krishna Murthy, K.; A Ananda Giri Babu; Bhaskar Laxman Durga Prasad

    2015-01-01

    The aim of this study was to examine the impact of dose rate on accuracy of intensity modulated radiation therapy (IMRT) plan delivery by comparing the gamma agreement between the calculated and measured portal doses by pretreatment quality assurance (QA) using electronic portal imaging device dosimetry and creating a workflow for the pretreatment IMRT QA at hospital levels. As the improvement in gamma agreement leads to increase in the quality of IMRT treatment delivery, gamma evaluation was...

  12. Evaluation of quality characteristics and functional properties of mechanically deboned chicken meats treated with different dose rates of ionizing radiation and use of antioxidants

    International Nuclear Information System (INIS)

    The Mechanically Deboned chicken meat (MDCM) is used in traditional meat products, in greater proportion in those emulsified, replacing meat raw materials more expensive. The raw material can have high MDCM the microbial load, as a result of contamination during processing or failure during the evisceration. The irradiation process is accepted as one of the most effective technologies when compared to conventional techniques of preservation, to reduce contamination of pathogens and spoilage. However, little information is available about the use and effects of different dose rates of ionizing radiation processing. Irradiation causes chemical changes in food, a major cause of deterioration of quality of raw or cooked meat products during refrigerated storage, frozen. The objective of this study was to evaluate the effects of different dose rates of ionizing radiation on the production of Thiobarbituric Acid Reactive Substances (TBARS), color, microbiological and sensory characteristics of mechanically deboned chicken added or without added antioxidants, during the cold storage and evaluation of functional properties. The results showed that among the tested dose rates using cobalt-60 source, dose rate of 4.04 kGy.h-1 was the best for processing MDCM. Furthermore, the use of the combination of rosemary antioxidant and α-tocopherol were able to reduce lipid oxidation generated by irradiation of the samples, showed a synergistic effect to the processing with ionizing radiation in reduction of psychrotrophic bacteria count and contributed to a better sensory quality. The use of radiation in the processing FDMI did not adversely affect the functional properties studied. (author)

  13. Genetic effect of low dose rate radiation on human cells immortalized with the hTERT gene

    International Nuclear Information System (INIS)

    We established immortal human cells by introducing the hTERT gene into skin fibroblast cells obtained from normal (SuSa) and ataxia telangiectasia (AT: AT1OS) individuals of Japanese origin. These immortalized cells showed the same characteristics as the original cells except expanded life span. We irradiated SuSa/T-n and AT1OS/T-n cells with low-dose-rate (LDR; 0.3 mGy/min) irradiation at confluent state in low-serum medium. Then, survival rate and micronucleus frequency of each cell line were analyzed. In SuSa/T-n cells, frequency of HPRT mutation induction was also determined by 6TG selection. In SuSa/T-n cells, survival rate and micronucleus frequency showed higher resistance after irradiation with LDR than high-dose-rate (HDR; 2 Gy/min) irradiation. In contrast, no significant difference was observed in survival and micronucleus induction in AT1OS/T-n cells between HDR and LDR irradiation, suggesting that AT1OS/T-n cells may have some defect in DNA repair activity. In SuSa/T-n cells, the frequency of HPRT mutation after LDR irradiation decreased to approximately one eighth that after HDR irradiation. (author)

  14. Significance of epidemiological and cytogenetic studies on high background radiation area residents

    International Nuclear Information System (INIS)

    Some area in the world are known as background levels of radiation are 3-5 times higher than the world average. The studies in high background area (HBRA) residents provide important direct information on the biological and health effects of chronic low dose rate radiation. (author)

  15. Evaluation of absorbed dose rate and annual effective dose equivalent due to terrestrial gamma radiation in rocks in a part of Southwestern Nigeria

    International Nuclear Information System (INIS)

    The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from 40K, 238U and 232Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6x7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33±2.76 nGy.h-1 and 8.7±2.9 μSv.y-1 respectively. (author)

  16. Evaluation of absorbed dose rate and annual effective dose equivalent due to terrestrial gamma radiation in rocks in a part of Southwestern Nigeria

    Energy Technology Data Exchange (ETDEWEB)

    Ajayi, O.S

    2002-07-01

    The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from {sup 40}K, {sup 238}U and {sup 232}Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6x7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33{+-}2.76 nGy.h{sup -1} and 8.7{+-}2.9 {mu}Sv.y{sup -1} respectively. (author)

  17. Radiation-induced oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder by gamma rays and electron beams: A clear dependence of dose rate

    International Nuclear Information System (INIS)

    Oxidation is an important effect of irradiation on polyethylene in air. In this work, oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder (ca. 110 μm in diameter) induced by gamma rays (γ ray) and electron beams (EB) in air resulted in some large differences in properties, such as oxidative scission due to dose rate differences. However, other properties, such as surface wettability and thermal stability were not that greatly affected. The dose-rates used were 0.0019 kGy/s from a cobalt-60 gamma source and 92 kGy/s from an electron beam. The chemical structure, oxidation level, surface wettability and thermal stability of irradiated UHMWPE were analyzed by FT-IR, XPS, TGA and the static contact angle. Hydrophilic carboxyl and carbonyl groups were present on the surface of irradiated UHMWPE after irradiation in air, resulting in a decrease in the contact angle. After irradiation at 300 kGy, the gel content of the γ ray-irradiated UHMWPE samples decreased to almost zero, while that of EB irradiated UHMWPE decreased to 57%. For UHMWPE powder irradiated by gamma rays at lower doses, radiation-induced oxidation was complete and consistent with a simple theoretic estimation. Surface wettability was primarily affected by surface oxidation, and the oxidation level of UHMWPE could be easily predicted. - Highlights: • UHMWPE powder was irradiated by γ ray and EB in air with difference in dose rate. • Radiation oxidation was studied and compared experimentally and theoretically. • The dose rate has great effect on thickness of oxidation layer in UHMWPE powder

  18. A Study on the radiation effects for the function and structure of rabbit blood platelets in various dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, Kohichi (Nippon Dental Univ., Tokyo (Japan))

    1991-12-01

    Mature peripheral platelets in rabbits were irradiated with a total 10 Gy of {sup 60}Co-{gamma} rays at the average dose rates of 0.2, 0.5, 1.0, 1.5 and 1.7 Gy/min. The effects was evaluated from the functional aspect by determining the ability of platelets to aggregate and replease, and the metabolic aspect by examining the kinetics of prostaglandin in platelets. In addition, platelet structure was compared using an electron microscope. The ability of platelets to aggregate and release was accelerated in all irradiated groups, compared with a non-irradiated group, especially in groups with average dose rates of 0.5 Gy/min and 1.0 Gy/min. The amount of MDA, a final product of prostaglandin in platelets, increased in all irradiated groups in comparison with the non-irradiated group, especially in the 0.5 Gy/min, 1.0 Gy/min and 1.5 Gy/min groups. Observation with a scanning electron microscope revealed a clear rock-like appearance of the surface of aggregates of platelets and a larger number of pseudopodia with longer projections in the 1.0 Gy/min group than in the non-irradiated group. Moreover, the surfaces of the aggregates in the 1.7 Gy/min group, but the adhension between psudopodia of the platelet aggregates was weaker than that of 1.0 Gy/min group. In observation with a transmission electron microscope, dense bodies that released their contents were noticed in platelet aggregates, and a stenopeic appearance between psudopodia and between platelets, and density aggregated platelets were observed in the 1.0 Gy/min irradiated group. Vacuolation of granules in platelets was more marked in aggregates of 1.7 Gy/min group than in that of the non-irradiated group, and large numbers of platelets with uneven surfaces were observed. Therefore, the effects of dose rates were found to be closely related to changes in structures, as well as to the inner function of platelets. (author).

  19. A Study on the radiation effects for the function and structure of rabbit blood platelets in various dose rates

    International Nuclear Information System (INIS)

    Mature peripheral platelets in rabbits were irradiated with a total 10 Gy of 60Co-γ rays at the average dose rates of 0.2, 0.5, 1.0, 1.5 and 1.7 Gy/min. The effects was evaluated from the functional aspect by determining the ability of platelets to aggregate and replease, and the metabolic aspect by examining the kinetics of prostaglandin in platelets. In addition, platelet structure was compared using an electron microscope. The ability of platelets to aggregate and release was accelerated in all irradiated groups, compared with a non-irradiated group, especially in groups with average dose rates of 0.5 Gy/min and 1.0 Gy/min. The amount of MDA, a final product of prostaglandin in platelets, increased in all irradiated groups in comparison with the non-irradiated group, especially in the 0.5 Gy/min, 1.0 Gy/min and 1.5 Gy/min groups. Observation with a scanning electron microscope revealed a clear rock-like appearance of the surface of aggregates of platelets and a larger number of pseudopodia with longer projections in the 1.0 Gy/min group than in the non-irradiated group. Moreover, the surfaces of the aggregates in the 1.7 Gy/min group, but the adhension between psudopodia of the platelet aggregates was weaker than that of 1.0 Gy/min group. In observation with a transmission electron microscope, dense bodies that released their contents were noticed in platelet aggregates, and a stenopeic appearance between psudopodia and between platelets, and density aggregated platelets were observed in the 1.0 Gy/min irradiated group. Vacuolation of granules in platelets was more marked in aggregates of 1.7 Gy/min group than in that of the non-irradiated group, and large numbers of platelets with uneven surfaces were observed. Therefore, the effects of dose rates were found to be closely related to changes in structures, as well as to the inner function of platelets. (author)

  20. Radiation protection in an animal research unit with pet: Occupational doses and dose rates produced by animals

    International Nuclear Information System (INIS)

    This study focuses on the occupational doses of technologists working at an Animal Research Unit using PET radiotracers and on the environmental dose rates produced by the animals (mice, rats and monkeys). In particular, whole body and extremity monitoring is reported and related with the workload. The study shows that doses not only depend on the amount of activity injected but also on the type of animals and radiotracers managed. The extremities, with a great variability of the doses received, are the limiting organs as far as regulatory dose limits for workers are concerned. Mean H∗(10) rates in contact and at 20 cm from the animals, when they are handled by the technologist, range from around 1 mSv/h to 20 μSv/h, respectively.

  1. Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident.

    Science.gov (United States)

    Kubota, Yoshihisa; Takahashi, Hiroyuki; Watanabe, Yoshito; Fuma, Shoichi; Kawaguchi, Isao; Aoki, Masanari; Kubota, Masahide; Furuhata, Yoshiaki; Shigemura, Yusaku; Yamada, Fumio; Ishikawa, Takahiro; Obara, Satoshi; Yoshida, Satoshi

    2015-04-01

    The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h(-1) (1.2 mGy d(-1)), even 3 years after the accident. This dose rate exceeds 0.1-1 mGy d(-1) derived consideration

  2. Radiation dose in the high background radiation area in Kerala, India.

    Science.gov (United States)

    Christa, E P; Jojo, P J; Vaidyan, V K; Anilkumar, S; Eappen, K P

    2012-03-01

    A systematic radiological survey has been carried out in the region of high-background radiation area in Kollam district of Kerala to define the natural gamma-radiation levels. One hundred and forty seven soil samples from high-background radiation areas and five samples from normal background region were collected as per standard sampling procedures and were analysed for (238)U, (232)Th and (40)K by gamma-ray spectroscopy. External gamma dose rates at all sampling locations were also measured using a survey meter. The activities of (238)U, (232)Th and (40)K was found to vary from 17 to 3081 Bq kg(-1), 54 to 11976 Bq kg(-1) and BDL (67.4 Bq kg(-1)) to 216 Bq kg(-1), respectively, in the study area. Such heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of beach sand soil in the region. Radium equivalent activities were found high in several locations. External gamma dose rates estimated from the levels of radionuclides in soil had a range from 49 to 9244 nGy h(-1). The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples. PMID:21515614

  3. Experimental and computational determination of radiation dose rates in the SLOWPOKE-2 research reactor at the Royal Military College of Canada

    International Nuclear Information System (INIS)

    The first SLOWPOKE-2 research reactor designed to use Low Enriched Uranium (LEU) dioxide fuel was commissioned at the Royal Military College of Canada/College militaire royal du Canada in September 1985. The enrichment is 19.89% in 235U . The reactor is a pool-type design, moderated and cooled by light water with the core located at the bottom of a 5.87 m pool, ensuring a 4.42 m layer of water above the core to provide the necessary radiation shielding. Cooling is by means of natural convection, the reactor power being limited to 20 kWth. The design allows free access to the reactor pool: in addition to the pneumatic irradiation system permitting the positioning of small samples within the beryllium reflector and close to the core, larger samples can be positioned in the pool against the reactor vessel using an 'elevator'-type positioning device. Several research projects have taken and are taking advantage of this equipment, most notably investigations of intense radiation effects on advanced polymers such as epoxies and poly-ether-ether-ketones (PEEKs). These research activities however require sound knowledge of the dose rates at the various irradiation sites within the reactor vessel, as well as at incremental positions within the pool. Accurate measurements of the particle fluxes were attempted before, but unfortunately yielded limited information due to the complexity of the composite radiation field and the capabilities of the instrumentation at that time. The present work aims at yet another attempt to gather sound dose rate data, using improved radiation detectors on one hand, and better computational resources (both hardware and software) on the other hand. All research on particle dose rates was performed with the reactor at steady-state half power (10 kWth) and at the reactor core mid-height. (author)

  4. Measurement of terrestrial gamma radiation dose-rate (TGRD) level in soil samples from the district of Rembau, Malaysia, using high-purity Germanium detectors

    International Nuclear Information System (INIS)

    This study assesses the gamma radiation levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected from the district of Rembau, Malaysia using High-purity Germanium (HPGe) Detectors. A 105 measurement were performed on surface soil using NaI (Tl) gamma-ray detector with crystal size 1x1, covering about 83% land of the Rembau district. The concentration of the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected were determined by using HPGe detector based on high-resolution gamma spectrometry system at Malaysia Nuclear Agency. The range of natural gamma radiation measured was from 114±14 nGy h−1 to 857±14 nGy h−1. The range of activity concentrations of U, Th and °K in soil from the studied areas varies from 151-401 Bq kg−1, 113-342 Bq kg−1 and 674-1526 Bq kg−1 with mean values of 245 Bq kg−1, 186 Bq kg−1 and 1152 Bq kg1 respectively. The mean values of terrestrial gamma radiation dose rate measured in Rembau district is 383±18 nGy h−1 compared to the Malaysian average is 92 nGy h−1 and world average is 59 nGy h−1 (UNSCEAR, 2000). The average annual dose from such terrestrial gamma radiation dose rates to an individual in Rembau district, assuming a tropical rural setting is estimated to be 0.78 mSv per year, which is considered to be within the normal range for doses from natural sources. An isodose map for the Rembau district has been plotted

  5. Effects of ground surface decontamination on the air radiation dose rate. Results of a decontamination trial at a playground lot in a Fukushima residential area

    International Nuclear Information System (INIS)

    The Japan Atomic Energy Agency decontaminated schools, playgrounds, swimming pools, and houses in nonevacuated, less-contaminated areas in Fukushima for environmental restoration. A small, 150 m2 playground lot in the residential area was chosen for decontamination demonstration, which used routinely available tools and commodities to carry out the work. The surfaces of playground lot equipment, such as swings, slides, and horizontal iron bars, were completely decontaminated by brushing with water and/or detergent. Side gutters around the playground lot were cleaned by removing the mud and then brushed and washed with a high-pressure water jet (7 MPa). The air dose rate at the playground lot was dominated by radiation from the ground surface and adjacent surroundings, such as apartments and rice fields. Two or three centimeters of the surface soil contaminated with cesium was removed manually with shovels, hoes, and other gardening tools. This significantly reduced the average air dose rate of the entire playground lot from 1.5 μSv/h before decontamination to 0.6 μSv/h. These results showed that ground surface decontamination can contribute measurably to the reduction in air dose rate in relatively small areas in residential areas. (author)

  6. Dose rate mapping of VMAT treatments

    Science.gov (United States)

    Podesta, Mark; Antoniu Popescu, I.; Verhaegen, Frank

    2016-06-01

    Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min‑1 and 12 Gy min‑1 but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates  <1 Gy min‑1. Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

  7. Diamond gamma dose rate monitor

    International Nuclear Information System (INIS)

    CVD (chemical vapor deposition) diamond detectors for X and gamma dose rate monitoring have been fabricated and tested in the 1 mGy/h to 1 kGy/h range. They show excellent performances in terms of sensitivity and linearity. Radiation hardness measurement under 60-Co gamma rays have demonstrated long term stability for integrated doses up to 500 kGy. (authors)

  8. Dose rates of the future

    International Nuclear Information System (INIS)

    Low dose rate (LDR) continuous brachytherapy will keep its place within the spectrum of cancer treatment modalities. However, for financial and logistical reasons, including radiation safety, a fractionated brachytherapy course giving an equivalent total dose according to the linear quadratic (LQ) model in a similar overall treatment time with fraction intervals of several hours, applied during working hours, will probably have prospects in the future. (author). 20 refs., 3 tabs

  9. A background radiation survey along the transcontinental railway in Australia

    International Nuclear Information System (INIS)

    This article reports a survey, carried out during a period from October 31 to November 3, 1994 in Australia, as well as some basic techniques of train-borne measurements for estimating outdoor gamma-ray dose rates. Surface rock and bedrock data are presented for convenience for geological analysis. Cosmic-ray dose rates estimated from atmospheric pressure data are also presented for researchers who are interested in total background radiation dose rates. It was found that gamma levels can be high in the western area. The dose rate data were based on the shielding correction factor evaluated at platforms in many stations. To confirm the validity of this method, the data from train-borne surveys in central Japan were compared with the present Australian data. There were, to some extent, correlations between them. The present study suggests that the train-borne measurements are useful for surveying wide area in a short time with an error of about 20%. (N.K.)

  10. Low dose radiation hypersensitivity and clustered DNA damages in human fibroblasts exposed to low dose and dose rate protons or 137CS y-rays

    Energy Technology Data Exchange (ETDEWEB)

    Bennett P. V.; Bennett, P.V.; Keszenman, D.J.; Johnson, A.M.; Sutherland, B.M.; Wilson, P.F.

    2013-05-14

    Effective radioprotection for human space travelers hinges upon understanding the individual properties of charged particles. A significant fraction of particle radiation astronauts will encounter in space exploratory missions will come from high energy protons in galactic cosmic radiation (GCR) and/or possible exposures to lower energy proton flux from solar particle events (SPEs). These potential exposures present major concerns for NASA and others, in planning and executing long term space exploratory missions. We recently reported cell survival and transformation (acquisition of anchorage-independent growth in soft agar) frequencies in apparently normal NFF-28 primary human fibroblasts exposed to 0-30 cGy of 50MeV, 100MeV (SPE-like), or 1000 MeV (GCR-like) monoenergetic protons. These were modeled after 1989 SPE energies at an SPE-like low dose-rate (LDR) of 1.65 cGy/min or high dose rate (HDR) of 33.3 cGy/min delivered at the NASA Space Radiation Laboratory (NSRL) at BNL.

  11. Evaluation of the effect of radiation levels and dose rates in irradiation of murine fibroblasts used as a feeder layer in the culture of human keratinocytes

    International Nuclear Information System (INIS)

    In 1975, Rheinwald and Green published an effective methodology for obtaining and cultivating human keratinocytes. This methodology consisted of seeding keratinocytes onto a feeder layer composed of lineage 3T3 murine fibroblasts, the proliferation rate of which is then controlled through the action of ionizing radiation. The presence of the feeder layer encourages the development of keratinocyte colonies and their propagation in similar cultures, becoming possible several clinical applications as skin substitutes or wound dressings in situations such as post burn extensive skin loss and other skin disorders. However, good development of these keratinocytes depends on a high quality feeder layer among other factors. In the present work, we evaluated the relationship between radiation levels and dose rates applied to fibroblasts used in construction of feeder layers and the radiation effect on keratinocytes colonies forming efficiency. Results indicate 3T3 lineage murine fibroblasts irradiated with doses varying between 60 and 100 Gy can be used as a feeder layer immediately after irradiation or storage of the irradiated cells in suspension at 4 g C for 24 hours with similar results. The exception is when the irradiation dose rate is 2.75 Gyh-1; in this case, results suggested that the fibroblasts should be used immediately after irradiation. (author)

  12. Adaptive response and genetic instability induced by a low-dose rate radiation simulating the high-altitude flight conditions on mice in vivo

    International Nuclear Information System (INIS)

    Complete text of publication follows. In the present work, we investigated the effect of a low-dose rate of high-LET radiation that simulates the spectral and component composition of radiation fields formed in the conditions of high-altitude flights on mice in vivo. The dose dependence, adaptive response, and genetic instability in generation F1 born from males irradiated under these conditions were examined in polychromatic erythrocytes of bone marrow using the micronucleus test. Two-month-old males of SHK white mongrel mice were used. Irradiation was performed for 24 h a day in the radiation field behind the concrete shield of the U-70 accelerator of 70 GeV protons (Serpukhov), which adequately simulates radiation field formed in the atmosphere at a height of about 10 km, to accumulate doses of 11.5, 21.5 and 31.5 cGy (1 cGy/day). The experiments demonstrated that: 1) irradiation of mice in vivo with these doses of low dose rate high-LET radiation leads to an increase in cytogenetic damage in polychromatic erythrocytes; 2) irradiation of mice with these doses induces no adaptive response in polychromatic erythrocytes as opposite to γ-radiation; and 3) in mice of the F1 generation born from males irradiated with doses of 11.5, 21.5 and 31.5 cGy, an increase in sensitivity to additional irradiation with a dose of 1.5 Gy of γ-radiation and the absence of adaptive response compared with the descendants of unirradiated males occur. These data indicate a genetic instability in generation F1 born from irradiated males.

  13. Dose rate levels around industrial gamma sources

    International Nuclear Information System (INIS)

    Dose rate levels around two gamma ray sources utilized in a mining corporation have been determined. Both gamma ray sources are 137Cs and are installed in a mining corporation to measure on-line the density of mine products. Dose rate levels were calculated in several sites around the 137Cs sources using two active and several passive thermoluminescent dosemeters. Using the 137Cs' gamma factor dose rates were calculated in all the points. A comparison between the measured and calculated dose rate levels was carried out. Calculated dose rate levels was obtained for three cases: first, assuming the sources were bare, second, assuming the sources inside their shielding and the third, adding an extra shield to reduce the dose rate levels to those similar to local background. (author)

  14. [{sup 131}I]Iodoazomycin arabinoside for low-dose-rate isotope radiotherapy: radiolabeling, stability, long-term whole-body clearance and radiation dosimetry estimates in mice

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Piyush [Department of Oncologic Imaging, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada); McQuarrie, Steven A. [Department of Oncologic Imaging, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada); Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada); Zhou, Aihya [Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada); McEwan, Alexander J.B. [Department of Oncologic Imaging, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada); Wiebe, Leonard I. [Department of Oncologic Imaging, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada) and Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, T6G 2N8 (Canada)]. E-mail: leonard.wiebe@ualberta.ca

    2005-08-01

    Background: The preliminary characterization of [{sup 131}I]iodoazomycin arabinoside ([{sup 131}I]IAZA) as a potential radiotherapeutic radiopharmaceutical is described. Methods: High-specific-activity [{sup 131}I]IAZA was prepared in therapeutic doses (up to 3 GBq per batch) by isotope exchange in pivalic acid melt and was purified on Sep-Pak cartridges. Stability in 15% ethanol in saline at 4 deg C was determined by high-performance liquid chromatography. IAZA cytotoxicity (IC{sub 50}, {approx}0.1 mM) against both murine (EMT-6) and human (143B, 143B-LTK) tumor cells determined by MTT test was in the range previously reported for EMT-6 cells using a clonogenic assay. Tissue radioactivity levels were measured in a murine tumor model for the 24- to 168-h postinjection period. Radiation dose estimates obtained from the tissue activity levels for this period were calculated from pharmacokinetic (WinNonlin) and dosimetry (MIRD and RAdiation Dose Assessment Resource) parameters. Results: The radioiodination efficiency was >90%, but with systematic losses during Sep-Pak purification, the recovered yields of [{sup 131}I]IAZA were {approx}75%. The product (specific activity, 4.6-6.4 GBq/{mu}mol) was stable for at least 2 weeks, with only {approx}6% degradation over this storage period. Extended biodistribution studies in Balb/c mice bearing implanted EMT-6 tumors showed that the highest tumor/blood radioactivity ratio (T/B; 4.8) occurred 24 h after dosing; the T/B ratio was {approx}1.5 at the end of the 7-day study. The 24- to 168-h tissue radioactivity data fit a one-compartment model except for liver data, which best fit a two-compartment model. Dosimetry estimates showed a tumor self-dose of 7.4 mGy/MBq, which is several-fold higher than for the liver or the kidney. Conclusions: [{sup 131}I]IAZA can be efficiently radiolabeled at high specific activity, purified by a simple Sep-Pak technique and stored with little radiolysis or chemical decomposition at these specific

  15. American Society for Radiation Oncology (ASTRO) and American College of Radiology (ACR) Practice Guideline for the Performance of High-Dose-Rate Brachytherapy

    International Nuclear Information System (INIS)

    High-Dose-Rate (HDR) brachytherapy is a safe and efficacious treatment option for patients with a variety of different malignancies. Careful adherence to established standards has been shown to improve the likelihood of procedural success and reduce the incidence of treatment-related morbidity. A collaborative effort of the American College of Radiology (ACR) and American Society for Therapeutic Radiation Oncology (ASTRO) has produced a practice guideline for HDR brachytherapy. The guideline defines the qualifications and responsibilities of all the involved personnel, including the radiation oncologist, physicist and dosimetrists. Review of the leading indications for HDR brachytherapy in the management of gynecologic, thoracic, gastrointestinal, breast, urologic, head and neck, and soft tissue tumors is presented. Logistics with respect to the brachytherapy implant procedures and attention to radiation safety procedures and documentation are presented. Adherence to these practice guidelines can be part of ensuring quality and safety in a successful HDR brachytherapy program.

  16. New method of gamma dose-rate measurement using energy-sensitive counters

    International Nuclear Information System (INIS)

    A new concept of charge quantization and pulse-rate measurement was developed to monitor low-level gamma dose rates using energy-sensitive, air-equivalent counters. Applying this concept, the charge from each detected photon is quantized by level-sensitive comparators so that the resulting total output pulse rate is proportional to dose rate. The concept was tested with a proportional counter and a solid-state detector for wide-range dose-rate monitoring applications. The prototypic monitors cover a dose-rate range from background radiation levels 10 μR/h) to 10 R/h

  17. Adjuvant radiation therapy for the treatment of endometrial cancer: experience with combination of external radiation therapy and high-dose rate brachytherapy

    International Nuclear Information System (INIS)

    Objective: To review the results of adjuvant external beam radiation therapy (EBRT) combined with high-dose rate brachytherapy (HDR-BT) for the treatment of endometrial carcinoma. Materials and methods: We retrospectively evaluated 141 patients treated with EBRT and HDR-BT after surgery between January 1993 and January 2001. EBRT was performed with a median dose of 45 Gy, and HDR-BT was performed with a median dose of 24 Gy, with four weekly insertions of 6 Gy. The median age of the patients was 63 years and the disease stage distribution was: CS I (FIGO), 52.4%; CS II, 13.5%; CS III, 29.8%; CS IV, 4.3%. Results: With a median follow-up of 53.7 months, the disease free survival (DFS) at five years was: CS I, 88.0%; CS II, 70.8%; CS III, 55.1%; CS IV, 50.0% (p = 0.0003). Global survival after five years was: CS I, 79.6%; CS II, 74.0%; CS III, 53.6%; CS IV, 100.0% (p = 0.0062). Factors affecting the DFS were histological grade and serous-papillary histology. Recurrence of the disease was observed in 33 cases, 13 (9.2%) of these occurred in the pelvis, vagina or vaginal vault. EBRT + HDR-BT of the vaginal vault allowed disease control in 90.8% of the cases. Conclusion: Radiation therapy is essential for loco-regional control of endometrial cancer and can achieve excellent cure rates in the initial stages. In more advanced stages, therapeutic failure frequently appears as distant metastases suggesting the need for complementary systemic therapy using new treatment modalities, particularly chemotherapy. (author)

  18. Radiation dose rate in the air and the contents of radionuclides in environmental samples in the coastal regions of the Okhotsk Sea

    International Nuclear Information System (INIS)

    We investigated the radiation dose rate in the air and the contents of radionuclides in the environmental samples (soil, raw grass, feed, raw cow's milk) in the coastal regions of the Okhotsk Sea from 2000 to 2002. The following results were obtained concerning the local feature of environmental radioactivity levels in the coastal regions of the Okhotsk Sea. 1. The radiation dose rate in the air above the grassland was 30-60 nGy/h which was two times higher than that in eastern Hokkaido. 2. 137Cs accumulated in soils (depth, 0-30 cm) of the grassland were calculated to be more than 82% of the total 137Cs accumulated in soils. 3. 137Cs and 90Sr contents in raw cow's milk were at low levels, because 137Cs and 90Sr contents in raw grass were low. Especially, 137Cs contents in raw cow's milk were about 1 order of magnitude lower than that in eastern Hokkaido. (author)

  19. Automation of the monitoring in real time of the absorbed dose rate in air due to the environmental gamma radiation in Cuba

    International Nuclear Information System (INIS)

    The Center of Protection and Hygiene of the Radiations (CPHR) like center rector of the National Net of Environmental Radiological Surveillance (RNVRA), it has strengthened their detection capacity and of answer before a situation of radiological emergency. The measurements of the absorbed dose rate in air due to the environmental gamma radiation in the main stations of the Net are obtained in real time and the CPHR receives the data coming from these posts at one time relatively short. To improve the operability of the RNVRA it was necessary to complete the facilities of existent monitoring using 4 automatic measurement stations with probes of gamma detection, implementing in this way a measurement system on real time. On the other hand the software were developed: GenironProbeFech, to obtain the data of the probes, DataMail for the shipment of the same ones by electronic mail and GammaRed that receives and processes the data in the rector center. (Author)

  20. Evaluation of the detriment associated with exposure at low doses and low dose rates in the radiation protection system

    International Nuclear Information System (INIS)

    Questions about quantifying the radiological risk associated with exposure to ionising radiation have been debated repeatedly for a variety of exposure situations, including, among others, medical irradiation, discharges from nuclear facilities, transportation of radioactive waste, and potential nuclear accidents. This paper aims to shed light on the link between exposure and risk, focusing on the items that constitute the detriment associated with this exposure. The management of the risk associated with it relies on a cautious hypothesis of a linear no-threshold relation between exposure and risk of death or detriment. The International Commission on Radiological Protection (ICRP) published General Recommendations in 1966 that recognised this relation, but did not publish a quantification of the risk until 1977. The Commission introduced the concept of effective dose as a risk indicator that makes it possible to determine dose limits according to the risk associated with them. In 1990, the Commission proposed a revision of the quantification and construction of detriment. New limits, based on risk quantification and, for the first time, risk tolerability, were proposed. The optimisation of radiation protection - keeping radiation exposure as low as reasonably achievable in light of the economic and social context - became the key principle of the radiation protection system. The use of detriment makes it possible to use economic tools to guide the decision process for this optimisation - by assessing the monetary value of human life. This concept, widely used in health economics during the 1980's, has been criticised by many and must be used cautiously. ICRP published the latest quantifications of detriment in 2007. Detriment is thus an indicator that assesses the risk of death associated with exposure to ionising radiation for an average individual. Its construction relies on simplifying assumptions that are needed to implement a robust and effective radiation

  1. Study of the antioxidant effect of α-tocopherol on low-density lipoprotein peroxidation induced at low and high γ-radiation dose rates

    International Nuclear Information System (INIS)

    It is well known that vitamin E (α-tocopherol, α-toc) is a very efficient lipid soluble antioxidant and several studies showed its beneficial action in the prevention and reduction of atherosclerosis. However, some in vitro studies suggest a prooxidant role of vitamin E, which could occur under given circumstances. This study was thus designed to investigate the antioxidant vs. prooxidant effect of vitamin E with regards to LDL peroxidation induced under different oxidative stress conditions. LDL was enriched with α-tocopherol and different α-toc/LDL ratios were studied (8.0±2.5, 14.3±3.0, 33.3±3.7, 42.7±3.5 and 48.2±4.5 molecules of α-toc/LDL particle). Enriched and control LDL were oxidized by action of ·OH and O2·- free radicals produced by γ-radiolysis at different dose rates. Susceptibility of LDL to oxidation was examined by the measure of conjugated diene and TBARS formation as well as LDL endogenous α-toc disappearance. Increasing LDL α-toc concentration reduced the LDL susceptibility to oxidation and their oxidizability. α-toc disappearance rates were comprised between 43 and 8.3x10-10 M s-1 and decreased with the radiation dose rate. Our results support an antioxidant role for α-tocopherol at high and low oxidative stress conditions

  2. Radiation-induced oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder by gamma rays and electron beams: A clear dependence of dose rate

    Science.gov (United States)

    Wang, Honglong; Xu, Lu; Hu, Jiangtao; Wang, Mouhua; Wu, Guozhong

    2015-10-01

    Oxidation is an important effect of irradiation on polyethylene in air. In this work, oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder (ca. 110 μm in diameter) induced by gamma rays (γ ray) and electron beams (EB) in air resulted in some large differences in properties, such as oxidative scission due to dose rate differences. However, other properties, such as surface wettability and thermal stability were not that greatly affected. The dose-rates used were 0.0019 kGy/s from a cobalt-60 gamma source and 92 kGy/s from an electron beam. The chemical structure, oxidation level, surface wettability and thermal stability of irradiated UHMWPE were analyzed by FT-IR, XPS, TGA and the static contact angle. Hydrophilic carboxyl and carbonyl groups were present on the surface of irradiated UHMWPE after irradiation in air, resulting in a decrease in the contact angle. After irradiation at 300 kGy, the gel content of the γ ray-irradiated UHMWPE samples decreased to almost zero, while that of EB irradiated UHMWPE decreased to 57%. For UHMWPE powder irradiated by gamma rays at lower doses, radiation-induced oxidation was complete and consistent with a simple theoretic estimation. Surface wettability was primarily affected by surface oxidation, and the oxidation level of UHMWPE could be easily predicted.

  3. Study of the antioxidant effect of {alpha}-tocopherol on low-density lipoprotein peroxidation induced at low and high {gamma}-radiation dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Abdelouahed [Research Centre on Aging and Department of Medicine, University of Sherbrooke, Sherbrooke, QC, J1H 4C4 (Canada)]. E-mail: abdelouahed.khalil@usherbrooke.ca; Milochevitch, Christelle [Research Centre on Aging and Department of Medicine, University of Sherbrooke, Sherbrooke, QC, J1H 4C4 (Canada)

    2005-02-01

    It is well known that vitamin E ({alpha}-tocopherol, {alpha}-toc) is a very efficient lipid soluble antioxidant and several studies showed its beneficial action in the prevention and reduction of atherosclerosis. However, some in vitro studies suggest a prooxidant role of vitamin E, which could occur under given circumstances. This study was thus designed to investigate the antioxidant vs. prooxidant effect of vitamin E with regards to LDL peroxidation induced under different oxidative stress conditions. LDL was enriched with {alpha}-tocopherol and different {alpha}-toc/LDL ratios were studied (8.0{+-}2.5, 14.3{+-}3.0, 33.3{+-}3.7, 42.7{+-}3.5 and 48.2{+-}4.5 molecules of {alpha}-toc/LDL particle). Enriched and control LDL were oxidized by action of {sup {center_dot}}OH and O{sub 2}{sup {center_dot}}{sup -} free radicals produced by {gamma}-radiolysis at different dose rates. Susceptibility of LDL to oxidation was examined by the measure of conjugated diene and TBARS formation as well as LDL endogenous {alpha}-toc disappearance. Increasing LDL {alpha}-toc concentration reduced the LDL susceptibility to oxidation and their oxidizability. {alpha}-toc disappearance rates were comprised between 43 and 8.3x10{sup -10} M s{sup -1} and decreased with the radiation dose rate. Our results support an antioxidant role for {alpha}-tocopherol at high and low oxidative stress conditions.

  4. Dose-rate effects on the bulk etch-rate of CR-39 track detector exposed to low-LET radiations

    CERN Document Server

    Yamauchi, T; Oda, K; Ikeda, T; Honda, Y; Tagawa, S

    1999-01-01

    The effect of gamma-rays and pulsed electrons has been investigated on the bulk etch rate of CR-39 detector at doses up to 100 kGy under various dose-rate between 0.0044 and 35.0 Gy/s. The bulk etch rate increased exponentially with the dose at every examined dose-rates. It was reveled to be strongly depend on the dose-rate: the bulk etch rate was decreased with increasing dose-rate at the same total dose. A primitive model was proposed to explain the dose-rate effect in which oxygen dissolved was assumed to dominate the damage formation process.

  5. Influence of dose rate on normal tissue tolerance

    International Nuclear Information System (INIS)

    Dose rate is one of the most important factors that determine the biological effects of a given dose of radiation. In general, the effects of radiation decrease with a decrease in dose rate. Dose rates that have been used in radiation therapy range from a few cGy/day for permanently implanted interstitial sources for a few Gy/min for external beam radiation therapy and high-dose-rate intracavitary brachytherapy. Processes such as repair of sublethal and potential lethal damage, cell cycle progression and redistribution, repopulation, and reoxygenation that are important for biological effects of fractionated external beam radiation therapy are also important for low-dose-rate intracavitary brachytherapy and brachytherapy and temporarily implanted interstitial sources. Repair of sublethal damage during continuous low-dose-rate irradiation (CLDRI) is probably the most important factor underlying the dose-rate effects observed in animal and human cell lines in vitro and tumor and normal tissues in vivo (1,2). The extent to which these processes determine the effect of dose rate varies with the intrinsic radiosensitivity, repair capacity, and proliferative kinetics of the stromal cells comprising the tissue. In this paper the influence of clinically relevant dose rate on normal tissue tolerance is discussed. To quantify the dose-rate effect, the dose-rate factor (DRF), which is a ratio of the isoeffect dose for a given dose rate and the isoeffect dose of the reference dose rate, has been estimated for each normal tissue whenever possible

  6. Sexual Functioning Among Endometrial Cancer Patients Treated With Adjuvant High-Dose-Rate Intra-Vaginal Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: We used the Female Sexual Function Index (FSFI) to investigate the prevalence of sexual dysfunction (SD) and factors associated with diminished sexual functioning in early stage endometrial cancer (EC) patients treated with simple hysterectomy and adjuvant brachytherapy. Methods and Materials: A cohort of 104 patients followed in a radiation oncology clinic completed questionnaires to quantify current levels of sexual functioning. The time interval between hysterectomy and questionnaire completion ranged from 5 years. Multivariate regression was performed using the FSFI as a continuous variable (score range, 1.2-35.4). SD was defined as an FSFI score of <26, based on the published validation study. Results: SD was reported by 81% of respondents. The mean (± standard deviation) domain scores in order of highest-to-lowest functioning were: satisfaction, 2.9 (±2.0); orgasm, 2.5 (±2.4); desire, 2.4 (±1.3); arousal, 2.2 (±2.0); dryness, 2.1 (±2.1); and pain, 1.9 (±2.3). Compared to the index population in which the FSFI cut-score was validated (healthy women ages 18-74), all scores were low. Compared to published scores of a postmenopausal population, scores were not statistically different. Multivariate analysis isolated factors associated with lower FSFI scores, including having laparotomy as opposed to minimally invasive surgery (effect size, −7.1 points; 95% CI, −11.2 to −3.1; P<.001), lack of vaginal lubricant use (effect size, −4.4 points; 95% CI, −8.7 to −0.2, P=.040), and short time interval (<6 months) from hysterectomy to questionnaire completion (effect size, −4.6 points; 95% CI, −9.3-0.2; P=.059). Conclusions: The rate of SD, as defined by an FSFI score <26, was prevalent. The postmenopausal status of EC patients alone is a known risk factor for SD. Additional factors associated with poor sexual functioning following treatment for EC included receipt of laparotomy and lack of vaginal lubricant use.

  7. Sexual Functioning Among Endometrial Cancer Patients Treated With Adjuvant High-Dose-Rate Intra-Vaginal Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Damast, Shari, E-mail: shari.damast@yale.edu [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Alektiar, Kaled M. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Goldfarb, Shari [Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Eaton, Anne; Patil, Sujata [Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Mosenkis, Jeffrey [Department of Comparative Human Development, University of Chicago, Chicago, Illinois (United States); Bennett, Antonia [Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Atkinson, Thomas [Department of Psychiatry, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Jewell, Elizabeth; Leitao, Mario; Barakat, Richard; Carter, Jeanne [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Basch, Ethan [Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2012-10-01

    Purpose: We used the Female Sexual Function Index (FSFI) to investigate the prevalence of sexual dysfunction (SD) and factors associated with diminished sexual functioning in early stage endometrial cancer (EC) patients treated with simple hysterectomy and adjuvant brachytherapy. Methods and Materials: A cohort of 104 patients followed in a radiation oncology clinic completed questionnaires to quantify current levels of sexual functioning. The time interval between hysterectomy and questionnaire completion ranged from <6 months to >5 years. Multivariate regression was performed using the FSFI as a continuous variable (score range, 1.2-35.4). SD was defined as an FSFI score of <26, based on the published validation study. Results: SD was reported by 81% of respondents. The mean ({+-} standard deviation) domain scores in order of highest-to-lowest functioning were: satisfaction, 2.9 ({+-}2.0); orgasm, 2.5 ({+-}2.4); desire, 2.4 ({+-}1.3); arousal, 2.2 ({+-}2.0); dryness, 2.1 ({+-}2.1); and pain, 1.9 ({+-}2.3). Compared to the index population in which the FSFI cut-score was validated (healthy women ages 18-74), all scores were low. Compared to published scores of a postmenopausal population, scores were not statistically different. Multivariate analysis isolated factors associated with lower FSFI scores, including having laparotomy as opposed to minimally invasive surgery (effect size, -7.1 points; 95% CI, -11.2 to -3.1; P<.001), lack of vaginal lubricant use (effect size, -4.4 points; 95% CI, -8.7 to -0.2, P=.040), and short time interval (<6 months) from hysterectomy to questionnaire completion (effect size, -4.6 points; 95% CI, -9.3-0.2; P=.059). Conclusions: The rate of SD, as defined by an FSFI score <26, was prevalent. The postmenopausal status of EC patients alone is a known risk factor for SD. Additional factors associated with poor sexual functioning following treatment for EC included receipt of laparotomy and lack of vaginal lubricant use.

  8. Cosmic background radiation: a hagiography

    Energy Technology Data Exchange (ETDEWEB)

    Abramo, Luis Raul [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica

    2009-07-01

    Full text. Cosmology advanced tremendously since Gamow and his students predicted the cosmic microwave background radiation, and since Penzias and Wilson observed it for the first time. The observations of the CMBR point to a Universe which is beautiful in its simplicity: the amazing richness of structures can be explained by a minimalistic set of well-known physical laws, a reasonable amount of free parameters, and 'natural' initial conditions which realize the idea of maximum entropy. We will revise the latest observations and show how the CMBR is presently allowing the study of the 'fine structure' of cosmological phenomena. We will also discuss the possibility of a detection of rotational modes (B-modes) in the polarization of the CMBR, that may reveal which processes (inflation ?) acted in the very early universe to endow it with these beautiful and simple properties. (author)

  9. Cosmic background radiation: a hagiography

    International Nuclear Information System (INIS)

    Full text. Cosmology advanced tremendously since Gamow and his students predicted the cosmic microwave background radiation, and since Penzias and Wilson observed it for the first time. The observations of the CMBR point to a Universe which is beautiful in its simplicity: the amazing richness of structures can be explained by a minimalistic set of well-known physical laws, a reasonable amount of free parameters, and 'natural' initial conditions which realize the idea of maximum entropy. We will revise the latest observations and show how the CMBR is presently allowing the study of the 'fine structure' of cosmological phenomena. We will also discuss the possibility of a detection of rotational modes (B-modes) in the polarization of the CMBR, that may reveal which processes (inflation ?) acted in the very early universe to endow it with these beautiful and simple properties. (author)

  10. Dose rate effect in food irradiation

    International Nuclear Information System (INIS)

    It has been suggested that the minor losses of nutrients associated with radiation processing may be further reduced by irradiating foods at the high dose rates generally associated with electron beams from accelerators, rather than at the low dose rates typical of gamma irradiation (e.g. 60Co). This review briefly examines available comparative data on gamma and electron irradiation of foods to evaluate these suggestions. (137 refs., 27 tabs., 11 figs.)

  11. Radon-222 dose rates to burrowing mammals

    OpenAIRE

    Beresford, N.A.; Barnett, C.L.; Potter, E. D.; Vives I Batlle, J.; Barlow, T.S.; Copplestone, D.

    2011-01-01

    Estimates of absorbed dose rates as a consequence of exposure of wildlife to natural background radionuclides are required to put results of assessments conducted for releases of radionuclides from licensed sites into context. There have been recent review papers in which estimated dose rates to marine, freshwater and terrestrial wildlife (specifically the ICRP Reference Animals and Plants (ICRP 2008)) from 40K and radionuclides in the 238U and 232Th series have been presented (Beresford et a...

  12. Assessment of shielding analysis methods, codes, and data for spent fuel transport/storage applications. [Radiation dose rates from shielded spent fuels and high-level radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Parks, C.V.; Broadhead, B.L.; Hermann, O.W.; Tang, J.S.; Cramer, S.N.; Gauthey, J.C.; Kirk, B.L.; Roussin, R.W.

    1988-07-01

    This report provides a preliminary assessment of the computational tools and existing methods used to obtain radiation dose rates from shielded spent nuclear fuel and high-level radioactive waste (HLW). Particular emphasis is placed on analysis tools and techniques applicable to facilities/equipment designed for the transport or storage of spent nuclear fuel or HLW. Applications to cask transport, storage, and facility handling are considered. The report reviews the analytic techniques for generating appropriate radiation sources, evaluating the radiation transport through the shield, and calculating the dose at a desired point or surface exterior to the shield. Discrete ordinates, Monte Carlo, and point kernel methods for evaluating radiation transport are reviewed, along with existing codes and data that utilize these methods. A literature survey was employed to select a cadre of codes and data libraries to be reviewed. The selection process was based on specific criteria presented in the report. Separate summaries were written for several codes (or family of codes) that provided information on the method of solution, limitations and advantages, availability, data access, ease of use, and known accuracy. For each data library, the summary covers the source of the data, applicability of these data, and known verification efforts. Finally, the report discusses the overall status of spent fuel shielding analysis techniques and attempts to illustrate areas where inaccuracy and/or uncertainty exist. The report notes the advantages and limitations of several analysis procedures and illustrates the importance of using adequate cross-section data sets. Additional work is recommended to enable final selection/validation of analysis tools that will best meet the US Department of Energy's requirements for use in developing a viable HLW management system. 188 refs., 16 figs., 27 tabs.

  13. Effective treatment of Stage I uterine papillary serous carcinoma with high dose-rate vaginal apex radiation (192Ir) and chemotherapy

    International Nuclear Information System (INIS)

    Purpose: Uterine papillary serous carcinoma (UPSC) is a morphologically distinct variant of endometrial carcinoma that is associated with a poor prognosis, high recurrence rate, frequent clinical understaging, and poor response to salvage treatment. We retrospectively analyzed local control, actuarial overall survival (OS), actuarial disease-free survival (DFS), salvage rate, and complications for patients with Federation International of Gynecology and Obstetrics (FIGO) (1988) Stage I UPSC. Methods and Materials: This retrospective analysis describes 38 patients with FIGO Stage I UPSC who were treated with the combinations of radiation therapy, chemotherapy, total abdominal hysterectomy, and bilateral salpingo-oophorectomy (TAH/BSO), with or without a surgical staging procedure. Twenty of 38 patients were treated with a combination of low dose-rate (LDR) uterine/vaginal brachytherapy using 226Ra or 137Cs and conventional whole-abdomen radiation therapy (WART) or whole-pelvic radiation therapy (WPRT). Of 20 patients (10%) in this treatment group, 2 received cisplatin chemotherapy. Eighteen patients were treated with high dose-rate (HDR) vaginal apex brachytherapy using 192Ir with an afterloading device and cisplatin, doxorubicin, and cyclophosphamide (CAP) chemotherapy (5 of 18 patients). Only 6 of 20 UPSC patients treated with combination LDR uterine/vaginal brachytherapy and conventional external beam radiotherapy underwent complete surgical staging, consisting of TAH/BSO, pelvic/para-aortic lymph node sampling, omentectomy, and peritoneal fluid analysis, compared to 15 of 18 patients treated with HDR vaginal apex brachytherapy. Results: The 5-year actuarial OS for patients with complete surgical staging and adjuvant radiation/chemotherapy treatment was 100% vs. 61% for patients without complete staging (p = 0.002). The 5-year actuarial OS for all Stage I UPSC patients treated with postoperative HDR vaginal apex brachytherapy and systemic chemotherapy was 94% (18

  14. Quality assurance methods in the German dose rate measurement network

    International Nuclear Information System (INIS)

    The result of the gamma dose rate measurements in the context of the surveillance of environmental radioactivity depends strongly on the physical properties of the counting probes, but also on meteorological effects and the characteristics of the site in the vicinity of the dose rate probes. In the German gamma dose rate measurement network (ODL-monitoring net) substantial quality assurance efforts have been undertaken to ensure that the measured data are representative. These are, in particular, measures to determine the specific physical properties of the deployed monitors (background count rate, dependence on the cosmic radiation), an individual on-site test of the detector efficiency in the context of so-called ''method of repetitive tests'', methods for on-line correlation of precipitation and dose rate display and description of the monitor environment in context of the background capability as well as the validity in case of a contamination situation. Respective investigations have been performed in recent years and, based on the substantial amount of data, an optimisation of the practicability of the measurement data for decision support systems derived. (orig.)

  15. External beam radiation therapy and a low-dose-rate brachytherapy boost without or with androgen deprivation therapy for prostate cancer

    International Nuclear Information System (INIS)

    Purpose: To assess outcomes with external beam radiation therapy (EBRT) and a low-dose-rate (LDR) brachytherapy boost without or with androgen deprivation therapy (ADT) for prostate cancer. Materials and Methods: From January 2001 through August 2011, 120 intermediate-risk or high-risk prostate cancer patients were treated with EBRT to a total dose of 4,500 cGy in 25 daily fractions and a palladium-103 LDR brachytherapy boost of 10,000 cGy (n = 90) or an iodine-125 LDR brachytherapy boost of 11,000 cGy (n = 30). ADT, consisting of a gonadotropin-releasing hormone agonist ± an anti-androgen, was administered to 29/92 (32%) intermediate-risk patients for a median duration of 4 months and 26/28 (93%) high-risk patients for a median duration of 28 months. Results: Median follow-up was 5.2 years (range, 1.1-12.8 years). There was no statistically-significant difference in biochemical disease-free survival (bDFS), distant metastasis-free survival (DMFS), or overall survival (OS) without or with ADT. Also, there was no statistically-significant difference in bDFS, DMFS, or OS with a palladium-103 vs. an iodine-125 LDR brachytherapy boost. Conclusions: There was no statistically-significant difference in outcomes with the addition of ADT, though the power of the current study was limited. The Radiation Therapy Oncology Group 0815 and 0924 phase III trials, which have accrual targets of more than 1,500 men, will help to clarify the role ADT in locally-advanced prostate cancer patients treated with EBRT and a brachytherapy boost. Palladium-103 and iodine-125 provide similar bDFS, DMFS, and OS. (author)

  16. Early observed transient prostate-specific antigen elevations on a pilot study of external beam radiation therapy and fractionated MRI guided High Dose Rate brachytherapy boost

    International Nuclear Information System (INIS)

    To report early observation of transient PSA elevations on this pilot study of external beam radiation therapy and magnetic resonance imaging (MRI) guided high dose rate (HDR) brachytherapy boost. Eleven patients with intermediate-risk and high-risk localized prostate cancer received MRI guided HDR brachytherapy (10.5 Gy each fraction) before and after a course of external beam radiotherapy (46 Gy). Two patients continued on hormones during follow-up and were censored for this analysis. Four patients discontinued hormone therapy after RT. Five patients did not receive hormones. PSA bounce is defined as a rise in PSA values with a subsequent fall below the nadir value or to below 20% of the maximum PSA level. Six previously published definitions of biochemical failure to distinguish true failure from were tested: definition 1, rise >0.2 ng/mL; definition 2, rise >0.4 ng/mL; definition 3, rise >35% of previous value; definition 4, ASTRO defined guidelines, definition 5 nadir + 2 ng/ml, and definition 6, nadir + 3 ng/ml. Median follow-up was 24 months (range 18–36 mo). During follow-up, the incidence of transient PSA elevation was: 55% for definition 1, 44% for definition 2, 55% for definition 3, 33% for definition 4, 11% for definition 5, and 11% for definition 6. We observed a substantial incidence of transient elevations in PSA following combined external beam radiation and HDR brachytherapy for prostate cancer. Such elevations seem to be self-limited and should not trigger initiation of salvage therapies. No definition of failure was completely predictive

  17. External beam radiation therapy and a low-dose-rate brachytherapy boost without or with androgen deprivation therapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Strom, Tobin J.; Hutchinson, Sean Z.; Shrinath, Kushagra; Cruz, Alex A.; Figura, Nicholas B.; Nethers, Kevin; Biagioli, Matthew C.; Fernandez, Daniel C.; Heysek, Randy V.; Wilder, Richard B., E-mail: richard.wilder@moffitt.org [Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL (United States)

    2014-07-15

    Purpose: To assess outcomes with external beam radiation therapy (EBRT) and a low-dose-rate (LDR) brachytherapy boost without or with androgen deprivation therapy (ADT) for prostate cancer. Materials and Methods: From January 2001 through August 2011, 120 intermediate-risk or high-risk prostate cancer patients were treated with EBRT to a total dose of 4,500 cGy in 25 daily fractions and a palladium-103 LDR brachytherapy boost of 10,000 cGy (n = 90) or an iodine-125 LDR brachytherapy boost of 11,000 cGy (n = 30). ADT, consisting of a gonadotropin-releasing hormone agonist ± an anti-androgen, was administered to 29/92 (32%) intermediate-risk patients for a median duration of 4 months and 26/28 (93%) high-risk patients for a median duration of 28 months. Results: Median follow-up was 5.2 years (range, 1.1-12.8 years). There was no statistically-significant difference in biochemical disease-free survival (bDFS), distant metastasis-free survival (DMFS), or overall survival (OS) without or with ADT. Also, there was no statistically-significant difference in bDFS, DMFS, or OS with a palladium-103 vs. an iodine-125 LDR brachytherapy boost. Conclusions: There was no statistically-significant difference in outcomes with the addition of ADT, though the power of the current study was limited. The Radiation Therapy Oncology Group 0815 and 0924 phase III trials, which have accrual targets of more than 1,500 men, will help to clarify the role ADT in locally-advanced prostate cancer patients treated with EBRT and a brachytherapy boost. Palladium-103 and iodine-125 provide similar bDFS, DMFS, and OS. (author)

  18. The evolution of the earth's background radiation field over the past four billion years

    International Nuclear Information System (INIS)

    It seems likely that life has evolved under an evolving background radiation field. The radiation dose from the earth itself has changed over geologic time as the crust of the earth has become enriched in radioactive elements and as those elements subsequently decayed away. The radiation dose from biologic potassium has steadily decreased with time according to the law of radioactive decay. Because of these two effects, it seems likely that early life was exposed to nearly ten times current radiation dose rates. In addition to these sources, cosmic and cosmogenic sources may have periodically raised radiation dose rates to very high levels at times in the past. These sources of radiation exposure are not well understood at present, but are the subject of ongoing research. Modern organisms may be more resistant to the adverse effects of radiation because mutation repair mechanisms evolved under higher radiation levels. This may help to shed some light on the current controversy regarding the biological effects of exposure to low levels of ionizing radiation, or it may simply help us to understand why cancer is primarily a disease of the elderly rather than the middle-aged. In addition, changing radiation levels over geologic time may help to reconcile molecular models of evolution with what is currently known from the fossil record. It may also be that this reconciliation can be used to validate the radiation dose rate models described above. Only time and further research will tell

  19. Mapping the exposure of the Brazilian population to natural background radiation - cosmic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rochedo, Elaine R.R., E-mail: elaine@ird.gov.br [Instituto de Radioprotecao e Dosimetria (lRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Salles, Krause C.S.; Prado, Nadya M.C., E-mail: krausesalles@yahoo.com.br, E-mail: nadya@ime.ib.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    The main objective of this work is to statically and graphically describe the exposure of the Brazilian population to natural background radiation. in this stage, doses due to cosmic rays is being assessed based on sea level dose rates, corrected by latitude and altitude, according to the model recommended by UNSCEAR. In this work, the doses were estimated for ali Brazilian municipalities with more than 100.000 inhabitants. The 253 municipalities selected for this study include about 52% of the Brazilian population. Average dose rate was estimated to be about 50 n Sv/h with a variation coefficient of 31%. The estimated doses have shown a strong influence of altitude on dose rates, with a correlation coefficient of 0,998 for ao exponential fit. This result confirms previous studies that show a large effect of the altitude 00 exposure from cosmic radiation. Considering the same occupation and shielding conditions used by UNSCEAR as global averages, average annual dose was estimated to be 0,37 (0,24 - 0,76) mSv/y, very close to UNSCEAR worldwide average of 0,38 (0,3 - 1,0) mSv/y. (author)

  20. Background radiation dose-rates to non-human biota in a high mountain habitat in Norway

    DEFF Research Database (Denmark)

    Brown, J.E.; Gelsvik, R.; Kålås, J.A.;

    2009-01-01

    of the available literature on naturally occurring radionuclides in wild plants and animals quickly illustrates a paucity of data coverage in numerous cases. Most notable is the lack of comprehensive information for the important dose-forming radionuclides such as 210Po and 210Pb. In order to collate...... commensurate with activity concentrations reported for reindeer muscle sampled at proximate locations, falling at a level of some 10s of Bq kg-1 by fresh weight. Statistical analyses of the data showed that bank vole and shrew 210Po data constitute different populations with different mean ranks. Unweighted...

  1. The Cosmic Background Radiation, 1997

    CERN Document Server

    Smoot, G F; Smoot, George; Scott, Douglas

    1997-01-01

    We summarise the current status of cosmic microwave background spectrum and anisotropy measurements, and their theoretical interpretation. This is the update of the mini-review for the 1997 web-version of the Review of Particle Properties.

  2. Dose rate, mitotic cycle duration, and sensitivity of cell transitions from G1 → S and G2 → M to protracted gamma radiation in root meristems

    International Nuclear Information System (INIS)

    Experiments were designed to determine the relative radiosensitivity of the cell transition points of G1 → S and G2 → M in root meristems of several plant species. Label and mitotic indices and microspectrophotometry were used to measure the proportions of cells in each mitotic cycle stage in root meristems after protracted gamma radiation. The criterion of radiosensitivity was the dose rate needed to produce a tissue with less than 1 percent cells in S and none in M after 3 days of continuous exposure. The results show that DNA is the primary radiation target in proliferative root meristems and that the cycle duration stipulates the time interval of vulnerability. In each species, nonrandom reproducible cell proportions were established with 2C:4C:8C amounts of nuclear DNA after 3 days of exposure. Roots of Helianthus annuus, Crepis capillaris, and Tradescantia clone 02 had 80 percent cells with a 2C amount of DNA and 20 percent had a 4C amount of DNA. In these species the transition point of G1 → S was more radiosensitive than G2 → M. Roots of Pisum sativum and Triticum aestivum had cell proportions at 2C:4C:8C amounts of DNA in frequencies of 0.10 to 0.20:0.40 to 0.60:0.30 to 0.40. In these two species 0.30 to 0.40 cells underwent radiation-induced endoreduplication that resulted from a rapid inhibition of cell transit from G2 → M and a slower impairment of G1 → S. Cells increased from 2C to 4C and from 4C to 8C amounts of DNA during irradiation. The proportions of nuclei with 2C:4C:8C amounts of DNA were dependent in part upon the relative radiosensitivity of the G1 → S and G2 → M control points. The data show the relative radiosensitivity of the transition points from G1 → S and from G2 → M was species specific and unrelated to the cycle duration and mean nuclear DNA content of the plant species

  3. Single-Fraction High-Dose-Rate Brachytherapy and Hypofractionated External Beam Radiation Therapy in the Treatment of Intermediate-Risk Prostate Cancer – Long Term Results

    International Nuclear Information System (INIS)

    Purpose: We present the long-term results of a cohort of patients with intermediate-risk prostate cancer (PC) treated with single-fraction high-dose-rate brachytherapy (HDRB) combined with hypofractionated external beam radiation therapy (HypoRT). Methods and Materials: Patients were treated exclusively with HDRB and HypoRT. HDRB delivered a dose of 10 Gy to the prostate surface and HypoRT consisted of 50 Gy delivered in 20 daily fractions. The first 121 consecutive patients with a minimum of 2 years posttreatment follow-up were assessed for toxicity and disease control. Results: The median follow-up was 65.2 months. No acute Grade III or higher toxicity was seen. Late Grade II gastrointestinal toxicity was seen in 9 patients (7.4%) and Grade III in 2 (1.6%). Late Grade III genitourinary toxicity was seen in 2 patients (1.6%). After a 24-month follow-up, a rebiopsy was offered to the first 58 consecutively treated patients, and 44 patients agreed with the procedure. Negative biopsies were found in 40 patients (91%). The 5-year biochemical relapse-free survival rate was 90.7% (95% CI, 84.5–96.9%), with 13 patients presenting biochemical failure. Among them, 9 were diagnosed with distant metastasis. Prostate cancer–specific and overall survival rates at 5 years were 100% and 98.8% (95% CI, 96.4–100%), respectively. Conclusion: The combination of HDRB and HypoRT is well tolerated, with acceptable toxicity rates. Furthermore, results from rebiopsies revealed an encouraging rate of local control. These results confirm that the use of conformal RT techniques, adapted to specific biological tumor characteristics, have the potential to improve the therapeutic ratio in intermediate-risk PC patients.

  4. Dose-rate and the reciprocity law: the TL response of Ge-doped silica optical fibres at therapeutic radiation doses

    International Nuclear Information System (INIS)

    In the radiotherapy regime, the TL response of Ge-doped optical fibre is investigated with respect to photon and electron dose-rate. The flexible optical fibre dosimeter system has previously been shown by this group to provide sensitive dosimetry over a wide range of electron and photon dose, sufficient to provide for the needs of radiotherapy. The optical fibre also offers small physical size and hence high spatial resolution. While TL measurements reveal linear dose response over the useful range of absorbed dose from 1 - 5 Gy, we know of no previous measurements of response to dose rate. Herein, for the dose range 1 - 5 Gy, we explore dose rates of 100 - 1000 cGy min-1 using a 9 MeV electron beam and 100 - 600 cGy min-1 using a 6 MV photon beam. For fixed doses we examine flatness of response over the cited dose-rate ranges. For electron and photon beams respectively, the optical fibre detectors were found to give flat response to within 4% and 5%, being independent of dose rate to within 2% (1 S.D.) for both electron and photon beam therapy. (Authors)

  5. Natural background radiation in Canada

    International Nuclear Information System (INIS)

    Published airborne gamma ray survey data from 33 areas of Canada were used to compile information on the average ground level exposure from natural radiation. The exposures at ground level were calculated from the surface concentrations of potassium, uranium and thorium. The highest levels of radioactivity were found in northern Canada and were generally related to granitic rocks; the lowest levels with the Athabasca sandstone. Summer outdoor exposure rates have a population-weighted average of 3.7 +- 2.3 μR.h-1, of which 48 percent orginated from potassium, 43 percent from the thorium series and 9 percent from the uranium series. This low level of radioactivity, compared to worldwide data, has resulted from erosion of a geologically old continental crust in which radioactivity decreases with depth. When seasonal variations of soil moisture and snow cover are considered, the annual population-weighted average outdoor exposure rate decreases to 2.8 +- 1.7 μR.h-1 corresponding to an annual outdoor dose-equivalent of 150 +- 90 μSV. Factors increasing the annual outdoor dose-equivalent are cosmic radiation (320 +- 30 μSV) and the internal radioactivity of the body (190 μSV). Using the ratio between indoor and outdoor values for worldwide published data, the average annual Canadian whole-body dose-equivalent from all sources of natural radiation is estimated to be 690 +-130 μSV

  6. Calculating the background radiation in the vicinity of the beam catchers of the ELBE radiation source

    International Nuclear Information System (INIS)

    The ELBE radiation sources comprises beam catchers in the experimenting sites which absorb the primary electron beam as well as the generated secondary radiation. The beam catcher consists of an ultrapure graphite absorber enclosed in a water-cooled stainless steel shell. Background radiation is shielded by iron, lead and heavy concrete. The beam parameters and the position of the beam catchers differ between experimenting sites. In order to determine the dose dependence of photon and neutron fluence and the dose equivalent at the cooling shell of the beam catcher, simulations were carried out using the FLUKA code. Radiation energies of 20 MeV and 50 MeV and electron fluxes of 1 mA were considered. The spatial and energetic distributions of the dose rate equivalent provide a basis for dimensioning of the radiation shields. The calculated distributions of the energy dose rate in the beam catcher serve as a basis for assessing thermal loads on materials and for designing the cooling system. (orig.)

  7. Epidemiological studies on disturbances of human fetal development in areas with various doses of natural background radiation. I. Relationship between incidences of Down's syndrome or visible malformation and gonad dose equivalent rate of natural background radiation

    International Nuclear Information System (INIS)

    The relationship between environmental radiation to the gonads and incidences of Down's syndrome and visible malformation was analyzed using Kendall's rank correlation method. The subjects, studied during a 3-yr period (1979-1981), were inhabitants of 46 prefectures in Japan that had various dose rates of natural background ionizing radiation. Results showed that the natural background very low-dose radiation rate was not a predominant factor responsible for inducing Down's syndrome or other visible malformations

  8. Rate of long term bleaching in FK 51 optical glass darkened by Co60 ionizing radiation at dose rates of 10 krad/hr and 7 rad/hr

    Energy Technology Data Exchange (ETDEWEB)

    Wirtenson, G.R.; White, R.H.

    1997-07-01

    A previous paper presented long term bleaching data on various glasses exposed to 10.6 krad of ionizing radiation. All the glasses reported except FK 51 have readily available `G` glass equivalents that are stabilized to the natural space environment. Yet, FK 51, because of its location on the Abbe diagram is extremely useful in certain lens design applications. To more fully explore the bleaching of FK 51, after the initial dose of 10.6 krad at 11.8 krad/hour, we irradiated three more samples at a similar dose rate but to different total doses. Since the dose rate for this study was significantly higher than the dose rate anticipated for glasses in as shielded space-based lens system (tilde 3 rad/day), additional data were obtained at a lower rate of 7 rad/hour. While this dose rate is still higher than the anticipated operational rate, it is more than 1000 times lower than the dose 011 011 011 rate used for our initial studies. The bleaching rate for the samples exposed at the lower dose rate is considerably less than for the samples exposed at the higher rate.

  9. Rate of long term bleaching in FK 51 optical glass darkened by Co60 ionizing radiation at dose rates of 10 krad/hr and 7 rad/hr

    International Nuclear Information System (INIS)

    A previous paper presented long term bleaching data on various glasses exposed to 10.6 krad of ionizing radiation. All the glasses reported except FK 51 have readily available 'G' glass equivalents that are stabilized to the natural space environment. Yet, FK 51, because of its location on the Abbe diagram is extremely useful in certain lens design applications. To more fully explore the bleaching of FK 51, after the initial dose of 10.6 krad at 11.8 krad/hour, we irradiated three more samples at a similar dose rate but to different total doses. Since the dose rate for this study was significantly higher than the dose rate anticipated for glasses in as shielded space-based lens system (tilde 3 rad/day), additional data were obtained at a lower rate of 7 rad/hour. While this dose rate is still higher than the anticipated operational rate, it is more than 1000 times lower than the dose 011 011 011 rate used for our initial studies. The bleaching rate for the samples exposed at the lower dose rate is considerably less than for the samples exposed at the higher rate

  10. Model of the contribution of the compton generated radiation to the dose rate for an experiment in a semi industrial irradiation plant

    International Nuclear Information System (INIS)

    The model of the build up contribution to the absorbed dose rate in a semi industrial irradiation plant is presented. A static irradiation of a lucite phantom with and without water is modeled. The absorbed dose was measured with silver and potassium dichromate dosemeters. Two approximations are used, the first one is a global adjustment of the attenuation coefficient and the second one consists in a detailed description of the Compton scattering. A specific numerical model is developed for each approximation and the absorbed dose rates calculated are compared with the experimental measurements. The achievements and limitations of both models are discussed. (author)

  11. The influence of dose rate, irradiation temperature and post-irradiation storage conditions on the radiation response of Harwell Gammachrome YR PMMA dosimeters

    International Nuclear Information System (INIS)

    Routine dosimeters are often influenced by changing dose rates, and also environmental conditions such as humidity and temperature. In Harwell Gammachrome YR dosimeters these influences are minimised by a carefully controlled conditioning process, and the use of special packaging material to maintain these conditions. This paper describes studies carried out on the influences of irradiation dose rate and temperature on two batches of dosimeters. Firstly, this paper gives gamma irradiation response data for dose rates of 5.5, 1.1 and 0.5 Gy·s-1 with irradiation temperatures of -20, 0, 10, 20 and 35 deg. C. Dosimeters were irradiated to doses of 0.1, 0.5, 1, 2 and 3 kGy. Secondly, this paper considers both, irradiation and post-irradiation storage temperatures, at a fixed dose rate of 1.4 Gy·s-1. Dosimeters were irradiated to doses of 0.1 and 3 kGy; at temperatures of 30, 40 or 50 deg. C. The dosimeters were stored at these temperatures for 2, 24 and 48 hours before measurement. (author)

  12. The effects of exposure dose and dose rate of gamma radiation on in vitro shoot-forming capacity of cotyledon explants in red pepper (Capsicum annuum L. cv. Yatsufusa)

    International Nuclear Information System (INIS)

    The effect of exposure dose and dose rate of gamma radiation on shoot-forming capacity of cotyledon explants of red pepper were investigated. The twelve-day-old seedlings were irradiated by gamma radiation with varying exposure doses of O, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 and 2.5 krad delivered at the dose rates of l, 5 and 10 krad/ hr. After irradiation, cotyledons were excised from the seedlings and cultured on MURASHIGE and SKOOG medium supplemented with benzyladenine at the concentration of 3 mg/l to induce shoot formation. It was found that the percentage of shoot-forming explants and the number of shoots per explant were decreased as the exposure dose increased. Moreover, the increase in exposure dose delayed callus and shoot bud formation and inhibited the development of shoot buds into vigorous shoots. At the same exposure dose, the higher dose rate (10 krad/hr) was more detrimental for shoot formation than the lower ones (1 and 5 krad/hr). The exposure dose which caused 50 percent reduction in the number of shoots per explant (RD50) was around 1.0 krad at the dose rates of 1 and 5 krad/hr whereas RD50 was 0.75 krad at the rate of 10 krad/hr. (author)

  13. Direct 2-Arm Comparison Shows Benefit of High-Dose-Rate Brachytherapy Boost vs External Beam Radiation Therapy Alone for Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Khor, Richard [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, and University of Melbourne, Melbourne (Australia); Duchesne, Gillian [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, and University of Melbourne, Melbourne (Australia); Monash University, Melbourne (Australia); Tai, Keen-Hun; Foroudi, Farshad; Chander, Sarat; Van Dyk, Sylvia; Garth, Margaret [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, and University of Melbourne, Melbourne (Australia); Williams, Scott, E-mail: Scott.Williams@petermac.org [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, and University of Melbourne, Melbourne (Australia)

    2013-03-01

    Purpose: To evaluate the outcomes of patients treated for intermediate- and high-risk prostate cancer with a single schedule of either external beam radiation therapy (EBRT) and high-dose-rate brachytherapy (HDRB) boost or EBRT alone. Methods and Materials: From 2001-2006, 344 patients received EBRT with HDRB boost for definitive treatment of intermediate- or high-risk prostate cancer. The prescribed EBRT dose was 46 Gy in 23 fractions, with a HDR boost of 19.5 Gy in 3 fractions. This cohort was compared to a contemporaneously treated cohort who received EBRT to 74 Gy in 37 fractions, using a matched pair analysis. Three-dimensional conformal EBRT was used. Matching was performed using a propensity score matching technique. High-risk patients constituted 41% of the matched cohorts. Five-year clinical and biochemical outcomes were analyzed. Results: Initial significant differences in prognostic indicators between the unmatched treatment cohorts were rendered negligible after matching, providing a total of 688 patients. Median biochemical follow-up was 60.5 months. The 5-year freedom from biochemical failure was 79.8% (95% confidence interval [CI], 74.3%-85.0%) and 70.9% (95% CI, 65.4%-76.0%) for the HDRB and EBRT groups, respectively, equating to a hazard ratio of 0.59 (95% CI, 0.43-0.81, P=.0011). Interaction analyses showed no alteration in HDR efficacy when planned androgen deprivation therapy was administered (P=.95), but a strong trend toward reduced efficacy was shown compared to EBRT in high-risk cases (P=.06). Rates of grade 3 urethral stricture were 0.3% (95% CI, 0%-0.9%) and 11.8% (95% CI, 8.1%-16.5%) for EBRT and HDRB, respectively (P<.0001). No differences in clinical outcomes were observed. Conclusions: This comparison of 2 individual contemporaneously treated HDRB and EBRT approaches showed improved freedom from biochemical progression with the HDR approach. The benefit was more pronounced in intermediate- risk patients but needs to be weighed against

  14. Direct 2-Arm Comparison Shows Benefit of High-Dose-Rate Brachytherapy Boost vs External Beam Radiation Therapy Alone for Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the outcomes of patients treated for intermediate- and high-risk prostate cancer with a single schedule of either external beam radiation therapy (EBRT) and high-dose-rate brachytherapy (HDRB) boost or EBRT alone. Methods and Materials: From 2001-2006, 344 patients received EBRT with HDRB boost for definitive treatment of intermediate- or high-risk prostate cancer. The prescribed EBRT dose was 46 Gy in 23 fractions, with a HDR boost of 19.5 Gy in 3 fractions. This cohort was compared to a contemporaneously treated cohort who received EBRT to 74 Gy in 37 fractions, using a matched pair analysis. Three-dimensional conformal EBRT was used. Matching was performed using a propensity score matching technique. High-risk patients constituted 41% of the matched cohorts. Five-year clinical and biochemical outcomes were analyzed. Results: Initial significant differences in prognostic indicators between the unmatched treatment cohorts were rendered negligible after matching, providing a total of 688 patients. Median biochemical follow-up was 60.5 months. The 5-year freedom from biochemical failure was 79.8% (95% confidence interval [CI], 74.3%-85.0%) and 70.9% (95% CI, 65.4%-76.0%) for the HDRB and EBRT groups, respectively, equating to a hazard ratio of 0.59 (95% CI, 0.43-0.81, P=.0011). Interaction analyses showed no alteration in HDR efficacy when planned androgen deprivation therapy was administered (P=.95), but a strong trend toward reduced efficacy was shown compared to EBRT in high-risk cases (P=.06). Rates of grade 3 urethral stricture were 0.3% (95% CI, 0%-0.9%) and 11.8% (95% CI, 8.1%-16.5%) for EBRT and HDRB, respectively (P<.0001). No differences in clinical outcomes were observed. Conclusions: This comparison of 2 individual contemporaneously treated HDRB and EBRT approaches showed improved freedom from biochemical progression with the HDR approach. The benefit was more pronounced in intermediate- risk patients but needs to be weighed against

  15. The Cosmic Background Radiation, 1995

    CERN Document Server

    Smoot, G F

    1995-01-01

    Observations of the Cosmic Microwave background have provided many of the most powerful constraints we have on cosmology and events in the early universe. The spectrum and isotropy of CBR have long been a pillar of Big Bang models. The discovery of low levels on anisotropy has provided new information and tools for our understanding of the early universe. Further observations promise to enhance greatly our knowledge of processes in the early universe and cosmological parameters. We can anticipate rapid advance in this field up to and through the year 2000 which will dramatically focus our efforts in cosmology during the next millenium. This paper outlines the primary science likely to be discovered and defined by a vigorous airborne and ground-based program which should be strongly supported. If successfully excuted, we an anticipate a measurement of the CBR anisotropy spectrum to within a factor of two of the confidence level unavoidably set by cosmic variance. Even so, observations of the CBR are the best a...

  16. Radiation background of Black Sea coastal environment

    International Nuclear Information System (INIS)

    The main objective of the project is to establish the level of radiation background and its sources in the Black Sea coastal environment. Marine samples will be collected in the Black Sea Coast area. The content of different radionuclides will be analyzed and the results will be used in a GIS application. The gamma emitting radionuclides will be measured in ultralow radiation background in the Romanian underground laboratory in salt mine in Slanic-Prahova. The main expected results is an up to date quantification of the radiation sources of the background of the Black Sea coastal environment. (authors)

  17. Radiation Risk from Chronic Low Dose-Rate Radiation Exposures: The Role of Life-Time Animal Studies - Workshop October 2005

    Energy Technology Data Exchange (ETDEWEB)

    Gayle Woloschak

    2009-12-16

    As a part of Radiation research conference, a workshop was held on life-long exposure studies conducted in the course of irradiation experiements done at Argonne National Laboratory between 1952-1992. A recent review article documents many of the issues discussed at that workshop.

  18. Measurement of radioactivity in an elevated radiation background area of Western Ghats

    Directory of Open Access Journals (Sweden)

    Manigandan P.K.

    2014-01-01

    Full Text Available As part of monitoring the exposure of the general public to natural radioactivity, the activity concentration of naturally occurring radionuclides in soil samples in an elevated radiation background area of Western Ghats was determined using gamma-ray spectrometry. Average values of the activity concentration of radionuclides, outdoor terrestrial gamma dose rate, annual effective dose equivalent and radiation hazard indices from soil activity were estimated. The activity concentrations of 232Th and average outdoor terrestrial gamma dose rate were found to be higher than the world average, possibly affecting the Western Ghats environment in general. Therefore, radiological risks to the general population from ionizing radiation from the naturally occurring radionuclides in the soil are considered to be significant. How- ever, other radiological hazard indices were found to be within permissible limits.

  19. Preliminary study on the measurement of background radiation dose at Antarctica during 32nd expedition

    International Nuclear Information System (INIS)

    A significant proportion (10%) of the natural background radiation is of cosmic origin. Cosmic ray consists of gamma, protons, electrons, pions, muons, neutrons and low Z nuclei. Due to the geomagnetic effect, cosmic radiation levels at poles are higher. As a consequence, personnel working in Antarctica (or Arctic) are subjected to high level of cosmic radiation. The present study gives the details of the estimation of background radiation (neutrons, gamma and electrons) dose rate around the Indian station at Antarctica named 'Bharati' measured during 32nd Indian scientific expedition to Antarctica (32nd INSEA). The measurement was carried out by passive dosimeters such as TLDs and CR-39 and active dosimeter such as RadEye G portable gamma survey meter. Gamma and electron components were measured using TLDs and survey meter, whereas CR-39 SSNTDs and neutron sensitive TLDs were used for neutron measurements. These detectors were deployed at few selected locations around Bharati station for about 2½ months during summer expedition. The neutron detectors used in the study were pre-calibrated with 241Am-Be fast/thermal neutron source. The fast neutron dose rate measured based on CR-39 detector was found to about 140-420 nSv/h. The gamma dose rate evaluated by TLDs/survey meter are in the range of 290-400 nSv/h. (author)

  20. Results of high dose rate afterloading brachytherapy boost to conventional external beam radiation therapy for initial and locally advanced prostate cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the impact on biochemical control (bNED), acute and late gastro-intestinal (GI) and urological (GU) morbidity of initial and locally advanced prostate cancer treated with fractionated transrectal ultrasound-guided (TRUS) high dose rate after loading brachytherapy (HDR-B) as a boost to conventional external beam radiation therapy (EBRT). Patients and methods: From March 1997 to February 2000 a total of 119 patients with any of the following characteristics were eligible for study entry: biopsy proven adenocarcinoma Gleason scored (GS), initial prostatic specific antigen (PSA) level dosage 1992 AJCC clinical stage T3a or less, and prostatic volume <60 cc. All patients had prior to HDR-B a course of EBRT 6 MV photons to a median dose of 45 Gy, in 1.8 Gy fractions, to the prostate and seminal vesicles only. HDR-B treatment planning and dosimetric calculations were generated with the Nucletron Planning System. Patients were grouped into two groups, according to their risk for biochemical failure: low-risk group without (LR) or with neoadjuvant total androgen deprivation (AD) prior to EBRT (LR+AD) and high-risk group without (HR) or with neoadjuvant AD (HR+AD), for bNED and dose-escalation protocol. LR encompassed patients who presented GS<6, T1 or T2a and or initial PSA<10 ng/ml, who were treated with 16 Gy (4 Gy fractions, b.i.d.) HDR-B. The remaining patients were grouped into HR or HR+AD and received 20 Gy (5 Gy fractions, b.i.d.) HDR-B. The planning was optimized using the standard geometric optimization. Biological effective doses (BED) for tumor control and late responding tissue were calculated using a α/β ratio of 1.5 and 3 Gy, respectively. They were matched with bNED, acute and late gastrointestinal (GI) and urological (GU) morbidity, according to the RTOG/EORTC scoring criteria. Results: Median age of patients was 68 years (range 47-83), with a median follow-up of 41 months (range 18-48). The crude and actuarial biochemical controls (b

  1. The proportion of thyroid cancers in the Japanese atomic bomb survivors associated with natural background radiation

    International Nuclear Information System (INIS)

    Generalised absolute and relative risk models (with adjustment to the excess absolute risk for time since exposure and age at exposure, and with adjustment to the excess relative risk for age at exposure) are fitted to the Japanese atomic bomb survivor thyroid cancer incidence data followed up over the period 1958-87, taking account of natural background radiation. Thyroid cancers associated with natural background radiation and atomic bomb radiation are overwhelmingly accounted for by exposure at young ages. Over 50% of the excess cases associated with either the atomic bomb radiation or natural background radiation are linked to exposures under the age of 20, irrespective of the assumed risk model or natural background dose rate. The excess risk is overwhelmingly concentrated among females, again irrespective of the assumed model or natural background dose rate. Depending on the assumed natural background dose rate (in the range 0.5-2.0 mSv/year) between 17.3 and 32.0% of the thyroid cancer in this cohort may be associated with natural background radiation if an absolute risk model applies; between 4.2 and 17.1% of the thyroid cancers may be associated with natural background radiation if the relative risk model applies. The proportion of the thyroid tumours attributed to the atomic bomb radiation is between 21.1 and 22.0% for the absolute risk model, and is between 18.7 and 19.1% for the relative risk model, in both cases irrespective of the assumed background radiation dose. In particular, these proportions are not very different from the proportions calculated when fitting models that do not take account of natural background radiation, namely 22.0% for the absolute risk model and 18.6% for the relative risk model. The proportion of thyroid cancers accounted for by natural background radiation progressively increases with attained age, from 0.3% of cancers among those under the age of 15 to 30.5% for those over the age of 60, assuming that the absolute risk

  2. On epidemiological studies of high background radiation areas

    International Nuclear Information System (INIS)

    Until recently, the epidemiological studies of high background radiation areas (HBRA) have 'received relatively little attention', and sometimes even ignored, e.g. UNSCEAR omitted the studies in Kerala from a table of epidemiological studies of radiation and cancer. Authoritative reports on the effects from ionizing radiation such as those from the National Research Council, UNSCEAR, and ICRP instead rely on other sources of information - most notably the A-bomb survivor cohort, medically irradiated cohorts, cohorts of miners exposed to high levels of radon, and the residential radon case-control studies. No doubt this is because HBRA studies typically have had relatively large potential for bias and confounding, low statistical power, and limitations relating to dosimetry. However, great efforts have been made recently to improve HBRA studies, particularly in Kerala and the Yuangjiang area of China. It is anticipated that some of these studies may be able to provide important direct information on health effects from chronic low-dose radiation exposures, a primary concern for radiation protection. In fact, the width of 90% confidence intervals for ERR/Gy reported for incidence from the Kerala study (-0.58, 0.46), and mortality in Yangjiang (-0.67, 0.69), is already comparable to that for some prominent studies of low-dose rate health effects such as of incidence in the Techa River Cohort (0.3, 1.9) and of mortality in the 15-Country Nuclear Workers Study (0.27, 1.80). However, it should be stressed that these intervals do not account for non-sampling sources of uncertainty such as errors in dosimetry and residual confounding. This presentation will focus on ways to further improve HBRA studies around the world, with particular emphasis on the ones in India and China. This will include ways to increase statistical power - such as ways to combine information from different HBRA studies, and possible extensions of the studies such as those designed to better

  3. Array-CGH analysis of mouse malignant lymphomas. Effects of chronic exposure to low-dose-rate γ-radiation on tumorigenesis

    International Nuclear Information System (INIS)

    We previously reported that mice that were chronically irradiated with γ-rays at low dose rates had significantly shorter life spans than unirradiated controls. The major cause of this life-shortening is considered to be the earlier onset and/or the faster progression of malignant lymphomas in the irradiated groups. In this study, chromosomal aberrations in a total of 54 malignant lymphomas from mice irradiated with a dose rate of 21 mGy/day and nonirradiated mice were precisely compared by microarray-based comparative genomic hybridization (array-CGH) analysis. Array-CGH profiles showed that about two-thirds of the tumors had aneuploidy genotypes, in which numeric aberrations of chromosomes 12, 14, 15, 16, and X were observed frequently in the unirradiated group while that of chromosome 15 predominated in the irradiated group. In addition, copy-number alterations were frequently identified on partial chromosomal regions harboring the following oncogenes and tumor suppressor genes: c-myc, N-myc, notch-1, notch-2, hes-1, akt-1, akt-2, akt-3, bcl-6, bcl-10, bcl-11a, bcl-11b, pim-2, BCoR, XIAP, rhoE, p16INK4a, p15INK4b, p73, p27Kip1, RB, and pten. If aberrations extending across whole-chromosomal and partial-chromsomal regions are counted together, gains on chromosomes 3, 12, 13, 14, 16 and X can be associated preferentially with the unirradiated group, whereas gains on chromosome 15, along with losses on chromosomes 4 and 14, were detected more frequently in the irradiated group. These observations offer insights into how low-dose-rate irradiation caused the earlier onset and/or the faster progression of tumors, as well as into the molecular pathogenesis of murine lymphomas. (author)

  4. Biological models and computed iso-effect tables for continuous low dose-rate and intermittent fractionated radiation therapy. Chapter 28

    International Nuclear Information System (INIS)

    Iso-effect tables for continuous low dose-rate radiotherapy and intermittent fractionated radiotherapy are computed using a cell population kinetic model and iso-effect programme. In this way equivalent tissue and tumour doses are estimated for varying fractionation schemes and treatment times. Iso-effect predictions are presented for human skin tolerance and human squamous cell carcinoma. Results are also presented for therapeutic ratios of skin tolerance:squamous cancer lethal dose for well-oxygenated tumours and tumours with 10% hypoxic cells. Using such iso-effect tables, optimal radiotherapy exposure times and a best choice of technique can be identified for different tissues and tumours. (U.K.)

  5. The initial investigation of radiation dose rate at X-ray department and patients treating thyroid by I-131 at nuclear medicine department

    International Nuclear Information System (INIS)

    Survey meter NSM 150 Fuji with detector Geiger Muller has been used to assess for average annual exposure dose which affect radiographer ≤ 2 mSv per year, the staff involved with Fluoroscopy ≤ 19 mSv per year. Dose rate in waiting area of patient is a range from 0.2 to 0.8 μSv/h. Patients who have been treated by radioiodine, may be only discharged when the remaining activity is 400.2 ±368.8 MBq. Radioactivity of I-131 and Tc-99m in the sewage system of hospital is 0.4x10-11 Ci/l. (author)

  6. Confounding factors in radiation epidemiology and their comparability between high background radiation areas and control areas in Yangjiang, China

    International Nuclear Information System (INIS)

    Objective: Confounding factors in radiation epidemiology and their comparability among the four different dose-rate groups in high background radiation areas were studied. Methods: The demography data were collected by a specific registration method. For the components of diet and life style, the samples were taken by a stratified random sampling method. Results: The sex-, age-distributions and the life expectancy of the members of a cohort 35 years old and above in the four dose-rate groups were similar to each other. The components of diet were constituted mostly of grains and vegetables with less meat, eggs and milk. The percentages of cigarette smokers were 27.7%-31.3% in both male and female subjects and the percentages of alcohol drinkers were 4.0%-6.9% in them. Conclusion: The results show that there is good comparability between the four dose-rate groups except for background radiation level, and it is suggested that the taken food consisting of grains and vegetables may be a beneficial factor leading to low incidence of malignancies in this area

  7. Yield of radiation-induced DNA single-strand breaks in Escherichia coli and superinfecting phage lambda at different dose rates. Repair of strand breaks in different buffers

    International Nuclear Information System (INIS)

    Cells of E. coli K-12 strain AB 1886 were irradiated in oxygenated phosphate buffered saline at 20C with electrons from a 4-MeV linear accelerator. The yield of DNA single-strand breaks was determined as a function of the dose rate between 2.5 and 21,000 krad/min. For dose rates over 100 krad/min the yield was found to be constant. Below 10 krad/min the yield of breaks decreases drastically. This is explained by rejoining of breaks during irradiation. Twenty percent of the breaks induced by acute exposure are repaired within 3 min at 20C. Superinfecting phage lambda DNA is repaired at the same rate as chromosomal DNA. In contrast to the results obtained with phosphate-buffered saline, an increase in the number of breaks after irradiation is observed when the bacteria are suspended in tris buffer. It is suggested that buffers of low ionic strength facilitate the leakage through the membrane of a small-molecular-weight component(s) necessary for DNA strand rejoining

  8. Background radiation levels and standards for protection from ionizing radiations

    International Nuclear Information System (INIS)

    Apart from the amount of radiation which a worker may receive while he performs his work, he is also exposed to radiation because of the nature of his environment. In other words, all individuals are subject to some irradiation even though they may not work with radioactive substances. This source of radiation exposure is often referred to as background radiation. In most environments, it is low-level and can be grouped into two natural and man-made. Background radiation provides the basis on which allowable exposure limits for workers are drawn

  9. Natural background radiation and oncologic disease incidence

    International Nuclear Information System (INIS)

    Cause and effect relationships between oncologic disease incidence in human population and environmental factors are examined using investigation materials of Soviet and foreign authors. The data concerning US white population are adduced. The role and contribution of natural background radiation oncologic disease prevalence have been determined with the help of system information analysis. The probable damage of oncologic disease is shown to decrease as the background radiation level diminishes. The linear nature of dose-response relationspip has been established. The necessity to include the life history of the studied population along with environmental factors in epidemiological study under conditions of multiplicity of cancerogenesis causes is emphasized

  10. Dose Rate Evaluation for 5 MW JRTR

    International Nuclear Information System (INIS)

    The Jordan Research and Training Reactor (JRTR) is under design. It is a 5 MW, open pool, water cooled and moderated core with an in-core Be reflector and D2O as an external-reflector. A general view of the JRTR geometry is given in Fig. 1. The main shielding materials for protecting the radiation emitting from the core are water in the axial direction and heavy concrete in the radial direction. Both of the general shielding codes, ANISN (one-dimensional) and DORT (two-dimensional), are well-known and reliable, and were chosen to carry out the shielding calculations. The results show reasonable and sound behavior for the dose rate. Both of the codes present results that pretty much verify each other. The design of the shield is qualified with regard to the design dose rate limits

  11. Ponderable soliton stars and cosmic background radiation

    Science.gov (United States)

    Chiu, Hong-Yee

    1990-01-01

    A theory is developed to describe the possible perturbations of the cosmic background radiation (CBR) by radiation from ponderable soliton stars in the early universe. Since the temperature of such stars is in the range of 10 to the 6th K, thermalization of their emitted radiation is possible. Two models are considered: one in which thermalization is ignored and one in which decoupling from thermalization is considered as a sudden process. The expected perturbation of the CBR is probably less than 1 percent and is largely around the short-wavelength end, in the form of point radio sources. This result is consistent with the most recent COBE measurements.

  12. Exposure to background radiation in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, S.B. [Australian Radiation Lab., Melbourne, VIC (Australia)

    1997-12-31

    The average effective dose received by the Australian population is estimated to be {approx}1.8 mSv / year. One half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This paper reviews a number of research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background, particularly in the workplace and illustrate approaches to the quantification and management of exposure to natural radiation. The average radiation doses to the Australian population are relatively low; the average annual radon concentration ranged from 6 Bq m{sup -3} in Queensland to 16 Bq m{sup -3} in the Australian Capital Territory (ACT). Of more importance is the emerging issue of exposure to elevated background radiation in the workplace. Two situation are presented; the radiation exposure to air crues and show cave tour guides. Annual doses up to 3.8 mSv were estimated for international crew members while the highest estimate for show cave tour guides was 9 mSv per year. 9 refs., 2 tabs., 4 figs.

  13. Exposure to background radiation in Australia

    International Nuclear Information System (INIS)

    The average effective dose received by the Australian population is estimated to be ∼1.8 mSv / year. One half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This paper reviews a number of research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background, particularly in the workplace and illustrate approaches to the quantification and management of exposure to natural radiation. The average radiation doses to the Australian population are relatively low; the average annual radon concentration ranged from 6 Bq m-3 in Queensland to 16 Bq m-3 in the Australian Capital Territory (ACT). Of more importance is the emerging issue of exposure to elevated background radiation in the workplace. Two situation are presented; the radiation exposure to air crues and show cave tour guides. Annual doses up to 3.8 mSv were estimated for international crew members while the highest estimate for show cave tour guides was 9 mSv per year

  14. Estimation of Absorbed Dose Rate and Collective Effective Dose Equivalent Due to Gamma Radiation from Selected Radionuclides in Soil in Ondo and Ekiti State, South-Western Nigeria

    International Nuclear Information System (INIS)

    The concentrations of natural radionuclides, namely 40K, 238U and 232Th, in surface soils in Ondo and Ekiti States, south-western Nigeria have been measured using a very sensitive gamma ray spectroscopic system consisting of a 760 mm x 760 mm NaI(Tl) scintillation detector coupled to a Canberra Series 10 Plus multichannel analyser. The mean absorbed dose rate, annual effective dose equivalent and the collective effective dose equivalent in these states have been estimated from the measured concentrations of the radionuclides, which are 0.015 ± 0.008 μGy.h-1, 18.4 μSv.y-1 and 73.6 man.Sv.y-1 respectively. (author)

  15. Estimation of Absorbed Dose Rate and Collective Effective Dose Equivalent Due to Gamma Radiation from Selected Radionuclides in Soil in Ondo and Ekiti State, South-Western Nigeria

    Energy Technology Data Exchange (ETDEWEB)

    Ajayi, I.R.; Ajayi, O.S

    1999-07-01

    The concentrations of natural radionuclides, namely {sup 40}K, {sup 238}U and {sup 232}Th, in surface soils in Ondo and Ekiti States, south-western Nigeria have been measured using a very sensitive gamma ray spectroscopic system consisting of a 760 mm x 760 mm NaI(Tl) scintillation detector coupled to a Canberra Series 10 Plus multichannel analyser. The mean absorbed dose rate, annual effective dose equivalent and the collective effective dose equivalent in these states have been estimated from the measured concentrations of the radionuclides, which are 0.015 {+-} 0.008 {mu}Gy.h{sup -1}, 18.4 {mu}Sv.y{sup -1} and 73.6 man.Sv.y{sup -1} respectively. (author)

  16. Controllable forms of natural background radiation

    International Nuclear Information System (INIS)

    RENA is a research programm into the controllable forms of natural background radiation, which cover the activities originating from the naturally occurring radionuclides enhanced by human intervention. In the RENA-program emphasis lays upon the policy aspects of environmental-hygienic, economical and governmental character. (H.W.). 15 refs.; 2 tabs

  17. Specific-locus experiments show that female mice exposed near the time of birth to low-LET ionizing radiation exhibit both a low mutational response and a dose-rate effect

    International Nuclear Information System (INIS)

    Female mice were exposed to 300 R of 73-93 R/min X-radiation either as fetuses at 18.5d post conception (p.c.) or within 9h after birth. Combining the similar results from these 2 groups yielded a specific-locus mutation frequency of 9.4x10-8 mutation/locus/R, which is statistically significantly higher than the historical-control mutation frequency, but much lower than the rate obtained by irradiating mature and maturing oocytes in adults. Other females, exposed at 18.5 days p.c. to 300 R of 0.79 R/min γ-radiation, yielded a mutation frequency that was statistically significantly lower than the frequency at high dose rates. The low-dose-rate group also had markedly higher fertility. It appears that the doe-rate effect for mutations induced near the time of birth may be more pronounced than that reported for mature and maturing oocytes of adults. A hypothesis sometimes advanced to explain low mutation frequencies recovered from cell populations that experience considerable radiation-induced cell killing is that there is selection against mutant cells. The reason for the relatively low mutational response following acute irradiation in the experiments is unknown; however, the finding of a dose-rate effect in these oocytes in the presence of only minor radiation-induced cell killing (as judged from fertility) makes it seem unlikely that selection was responsible for the low mutational response following acute exposure. Had selection been an important factor, the mutation frequency should have increased when oocyte killing was markedly reduced. (author). 32 refs.; 5 figs.; 5 tabs

  18. Mapping terrestrial γ-dose rate in Europe based on routine monitoring data

    International Nuclear Information System (INIS)

    After the nuclear reactor accident in Chernobyl in 1986, most countries of the European Union (EU) established monitoring networks measuring outdoor γ-dose rates for early warning. The data are composite values γ-dose rate due to terrestrial, cosmic and artificial radiation sources, and in most cases also include some instrument background. While EURDEP is mainly designed for exchanging and stocking data during radiological emergencies, the data it is storing in its database may potentially contain valuable information about spatio-temporal variations of the 222Rn source term which can be used for the validation of atmospheric transport models and other atmospheric tracer applications. The use of γ-dose rates as a proxy for outdoor radon concentrations is indeed possible if one can extract the terrestrial γ-dose rate contribution from the values reported in EURDEP. It is the purpose of this paper to discuss the preparation of the terrestrial γ-dose rates using EURDEP data and to present seasonal maps of terrestrial γ-dose rates in Europe. Such maps could be used for the preparation of 222Rn source term which can be used for the validation of atmospheric transport models as well as for exploring variations in soil moisture content, an important parameter in flood prediction. These applications are the focus of the ongoing studies, but beyond the scope of this paper. In this paper, we show how the terrestrial γ-dose rate can be derived from the emergency monitoring data and two seasonal maps of γ-dose rates at the European scale are produced using geostatistics

  19. An investigation of gamma background radiation in Hamadan province, Iran

    International Nuclear Information System (INIS)

    The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO4:Dy thermoluminescence dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22 and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in Hamadan province. (authors)

  20. Reference Dose Rates for Fluoroscopy Guided Interventions

    International Nuclear Information System (INIS)

    The wide diversity of fluoroscopy guided interventions which have become available in recent years has improved patient care. They are being performed in increasing numbers, particularly at departments of cardiology and radiology. Some procedures are very complex and require extended fluoroscopy times, i.e. longer than 30 min, and radiation exposure of patient and medical staff is in some cases rather high. The occurrence of radiation-induced skin injuries on patients has shown that radiation protection for fluoroscopy guided interventions should not only be focused on stochastic effects, i.e. tumour induction and hereditary risks, but also on potential deterministic effects. Reference dose levels are introduced by the Council of the European Communities as an instrument to achieve optimisation of radiation protection in radiology. Reference levels in conventional diagnostic radiology are usually expressed as entrance skin dose or dose-area product. It is not possible to define a standard procedure for complex interventions due to the large inter-patient variations with regard to the complexity of specific interventional procedures. Consequently, it is not realistic to establish a reference skin dose or dose-area product for complex fluoroscopy guided interventions. As an alternative, reference values for fluoroscopy guided interventions can be expressed as the entrance dose rates on a homogeneous phantom and on the image intensifier. A protocol has been developed and applied during a nationwide survey of fluoroscopic dose rate during catheter ablations. From this survey reference entrance dose rates of respectively 30 mGy.min-1 on a polymethylmethacrylate (PMMA) phantom with a thickness of 21 cm, and of 0.8 μGy.s-1 on the image intensifier have been derived. (author)

  1. Measuring of gamma dose rate in the air by the autonomous probe Gamma Tracer

    International Nuclear Information System (INIS)

    The results of the measured values of gamma dose rate in the air and the background radiation level on 20 chosen places in close and more distant surrounding of the Kosovo Coal Power Plant are shown. The measuring was made by means of autonomy 'ADL - probe Gamma Tracer system' to interpret long-term continuous series of the natural background radiation. The existing higher level of radiation was pointed out, in the places close to the coal power plant, in respect to the radiation levels of the places out of the influence of that coal power plant. (author)

  2. Pre-operational background radiation monitoring of Emergency Planning Zone (EPZ) of Kudankulam Nuclear Power Plant using mobile radiation monitoring methodology

    International Nuclear Information System (INIS)

    A pre-operational background radiation monitoring was carried out in the Emergency Planning Zone (EPZ) of Kudankulam Nuclear Power Plant (KKNPP). The objective of the radiation survey at pre operational stage was to form baseline radiation data against which future changes in the environmental radiation due to the operation of KKNPP can be compared. The radiation mapping was carried out using mobile monitoring technique - as a state of the art technique, where various radiation monitoring instruments installed on a mobile van were simultaneously used for qualitative and quantitative assessment (dose rate as well as radionuclide identification). During the radiation monitoring survey most of the accessible areas in EPZ have been covered. The radiation data such as dose rate, counts rate and radionuclide activity concentration in the soil were retrieved from various radiation monitors, processed and analyzed. The preoperational background radiation monitoring in EPZ of KKNPP showed the elevated radiation field, which is of the order of 30 times the national average background radiation field, in some regions like Kuthankuzhi, Lakshmipuram, Navvaladi etc. The detailed survey and analysis showed the excess presence of 232Th and 40K in elevated radiation field areas. This study would help to form baseline radiation data against which any future changes in the environmental radiation due to the operation of KKNPP can be evaluated

  3. Dose-rate mapping and search of radioactive sources in Estonia

    International Nuclear Information System (INIS)

    The Estonian Ministry of Environment and the Finnish Centre for Radiation and Nuclear Safety (STUK) agreed in 1995 on a radiation mapping project in Estonia. The country was searched to find potential man-made radioactive sources. Another goal of the project was to produce a background dose-rate map over the whole country. The measurements provided an excellent opportunity to test new in-field measuring systems that are useful in a nuclear disaster. The basic idea was to monitor road sides, cities, domestic waste storage places and former military or rocket bases from a moving vehicle by measuring gamma spectrum and dose rate. The measurements were carried out using vehicle installed systems consisting of a pressurised ionisation chamber (PIC) in 1995 and a combination of a scintillation spectrometer (NaI(TI)) and Geiger-Mueller-counter (GM) in 1996. All systems utilised GPS-satellite navigation signals to relate the measured dose rates and gamma-spectra to current geographical location. The data were recorded for further computer analysis. The dose rate varied usually between 0.03-0.17 μSv/h in the whole country, excluding a few nuclear material storage places (in Saku and in Sillamae). Enhanced dose rates of natural origin (0.17-0.5 μSv/h) were measured near granite statues, buildings and bridges. No radioactive sources were found on road sides or in towns or villages. (orig.) (14 refs.)

  4. Dose-rate mapping and search of radioactive sources in Estonia

    Energy Technology Data Exchange (ETDEWEB)

    Ylaetalo, S.; Karvonen, J.; Ilander, T.; Honkamaa, T.; Toivonen, H.

    1996-12-01

    The Estonian Ministry of Environment and the Finnish Centre for Radiation and Nuclear Safety (STUK) agreed in 1995 on a radiation mapping project in Estonia. The country was searched to find potential man-made radioactive sources. Another goal of the project was to produce a background dose-rate map over the whole country. The measurements provided an excellent opportunity to test new in-field measuring systems that are useful in a nuclear disaster. The basic idea was to monitor road sides, cities, domestic waste storage places and former military or rocket bases from a moving vehicle by measuring gamma spectrum and dose rate. The measurements were carried out using vehicle installed systems consisting of a pressurised ionisation chamber (PIC) in 1995 and a combination of a scintillation spectrometer (NaI(TI)) and Geiger-Mueller-counter (GM) in 1996. All systems utilised GPS-satellite navigation signals to relate the measured dose rates and gamma-spectra to current geographical location. The data were recorded for further computer analysis. The dose rate varied usually between 0.03-0.17 {mu}Sv/h in the whole country, excluding a few nuclear material storage places (in Saku and in Sillamae). Enhanced dose rates of natural origin (0.17-0.5 {mu}Sv/h) were measured near granite statues, buildings and bridges. No radioactive sources were found on road sides or in towns or villages. (orig.) (14 refs.).

  5. The latest cancer statistics of the Hiroshima/Nagasaki A-bomb survivors - a higher radiation risk at dose rates below 50cGy (rad) - consequences for radiation protection

    International Nuclear Information System (INIS)

    The latest BEIR report assumes linear dose effect curves. The latest cancer statistics of the a-bomb survivors (1950 to 1982 and 1950 to 1985) reveal a definite positive correlation between cancer mortality and medium dose rate for groups of survivors exposed to mean kerma dose rates below 0.20 Gy. (orig.)

  6. Gamma knife: Distribution of dose rates

    International Nuclear Information System (INIS)

    In order to establish necessary data for dimensioning treatment room shielding for the first gamma knife in Austria we made use of results of measurements taken from existing installations abroad. Since there are no standardised rules for dimensioning gamma knife sites we felt that further research was necessary. Thus we conducted measurements of the leakage radiation with closed shielding doors and of the dose rate in the treatment room using a Rando Alderson phantom. This paper is intended as additional help for further installations of gamma knifes

  7. Ultraviolet Background Radiation from Cosmic Structure Formation

    OpenAIRE

    Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2003-01-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated by cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ry. The bulk of the radiation is produced by objects in...

  8. Natural background approach to setting radiation standards

    International Nuclear Information System (INIS)

    The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was small compared to the natural background. In order to make this concept quantitative and objective, we propose that small compared with the natural background be interpreted as the standard deviation (weighted with the exposed population) of the natural background. This use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent data. When this method is applied to the population of the United States, it suggests that a dose of 20 mrem/year would be an acceptable standard. This is comparable to the 25 mrem/year suggested as the maximum allowable exposure to an individual from the complete uranium fuel cycle

  9. Inverse dose-rate effect for the induction of 6-thioguanine-resistant mutants in Chinese hamster V79-S cells by 60Co gamma rays

    International Nuclear Information System (INIS)

    Chinese hamster V79-S cells capable of growing in suspension culture were exposed to 60Co gamma rays at a high dose rate (84 Gy/h), low dose rates (200, 50, and 39 mGy/h), and a spectrum of very low dose rates (between 29 and 4.5 mGy/h). Following time for appropriate expression the cultures were assayed for the induction of 6-thioguanine-resistant mutants. For a given dose, a decrease in mutation induction occurred as the dose rate was reduced from high dose rates to low dose rates. However, further reduction in dose rate resulted in a reverse dose-rate effect, and an increase in the frequency of mutants was observed. The contribution of background mutation frequency to this reverse dose-rate effect was studied, both by examining fluctuations of mutation frequency in nonirradiated culture and by its impact upon the dose-rate-independent nature of the reversed effect, and it was found to be negligible. The physiological state of the suspension culture under periods of protracted exposure to very low dose rates was also investigated. The effect of doubling time, plating efficiency, cell cycle distribution, and sensitivity on survival and mutation were examined. In no case was a change apparent during the very low-dose-rate exposures. The results are discussed in terms of the possible expression of cryptic radiation damage after prolonged culture times and/or the involvement of an error-free repair system which requires a certain amount of radiation damage to become active

  10. Design of movable fixed area γ dose rate monitor

    International Nuclear Information System (INIS)

    Movable fixed area γ dose rate monitor has not only the characteristics of fixed area γ dose rate monitor, but that of portable meter as well. Its main function is to monitor the areas where dose rate would change without orderliness to prevent unplanned radiation exposure accidents from happening. The design way of the monitor, the main indicators description, the working principle and the comprising of software and hardware are briefly introduced. The monitor has the characteristics of simple installation, easy maintenance, little power consumption, wide range, notability of visual and audible alarm and so on. Its design and technique have novelty and advancement. (authors)

  11. Dose rate measurements and their evaluation in general indoor houses

    International Nuclear Information System (INIS)

    Since the Fukushima Daiichi Nuclear Power Station accident, exposure doses for residents are investigated where to know the radiation dose rates indoor houses is necessary. As this is not easy, in stead, using the air dose rates estimated and multiplied by RF (reduction factor) value from outdoor air dose rates. For wooden houses RF value of 0.20 is adopted. After modification of RF representation equation and considering gamma ray energy distribution, the author finally obtained satisfactory, equation to calculate the RF value. (S. Ohno)

  12. Measurement of γ absorption dose rate through measuring the full energy peak of γ spectrum

    International Nuclear Information System (INIS)

    Background: At present most radiation dose meters have the serious problem of energy response, and they just use the count rate plus relative correction method to measure the dose rate. This method has large error, and cannot distinguish the type of radionuclide, also cannot obtain the contribution of each radionuclide to the dose rate. Purpose: The research of new method is to measure the dose rate and improve the accuracy of measurement. Methods: The method of γ dose rate measurement through measuring full energy peak of γ spectrum was put forward, the angular response function of parallel γ ray injected into detector was defined. The average angular response over full space in the energy range from 0.02 MeV to 3 MeV was calculated by Monte Carlo simulation for Ø50 mm×50 mm NaI(Tl) detector. Measurement tests have been done using standard radioactive sources of 137Cs, 60Co, 152Eu, 133Ba and in reference radioactive field of 137Cs, 60Co, 226Ra, 241Am in a national lab. Results: The test errors are smaller than 2% compared with the theoretical value for standard sources, and smaller than 3% compared with the value of PTW 10 L spherical chamber for reference radiation field. Conclusion: The results show that the method is suitable for the dose rate measurement for a wide range of energy without experimental calibration, can calculate the dose rate of different energy ray, and at the same time identify the radioactive nuclides in the radiation source. (authors)

  13. Radionuclides and radiation indices of high background radiation area in Chavara-Neendakara placer deposits (Kerala, India).

    Science.gov (United States)

    Derin, Mary Thomas; Vijayagopal, Perumal; Venkatraman, Balasubramaniam; Chaubey, Ramesh Chandra; Gopinathan, Anilkumar

    2012-01-01

    The present paper describes a detailed study on the distribution of radionuclides along Chavara - Neendakara placer deposit, a high background radiation area (HBRA) along the Southwest coast of India (Kerala). Judged from our studies using HPGe gamma spectrometric detector, it becomes evident that Uranium ((238)U), Thorium ((232)Th) and Potassium ((40)K) are the major sources for radioactivity prevailing in the area. Our statistical analyses reveal the existence of a high positive correlation between (238)U and (232)Th, implicating that the levels of these elements are interdependent. Our SEM-EDAX analyses reveal that titanium (Ti) and zircon (Zr) are the major trace elements in the sand samples, followed by aluminum, copper, iron, ruthenium, magnesium, calcium, sulphur and lead. This is first of its kind report on the radiation hazard indices on this placer deposit. The average absorbed dose rates (9795 nGy h(-1)) computed from the present study is comparable with the top-ranking HBRAs in the world, thus offering the Chavara-Neendakara placer the second position, after Brazil; pertinently, this value is much higher than the World average. The perceptibly high absorbed gamma dose rates, entrained with the high annual external effective dose rates (AEED) and average annual gonadal dose equivalent (AGDE) values existing in this HBRA, encourage us to suggest for a candid assessment of the impact of the background radiation, if any, on the organisms that inhabit along this placer deposit. Future research could effectively address the issue of the possible impact of natural radiation on the biota inhabiting this HBRA. PMID:23185629

  14. Radionuclides and radiation indices of high background radiation area in Chavara-Neendakara placer deposits (Kerala, India.

    Directory of Open Access Journals (Sweden)

    Mary Thomas Derin

    Full Text Available The present paper describes a detailed study on the distribution of radionuclides along Chavara - Neendakara placer deposit, a high background radiation area (HBRA along the Southwest coast of India (Kerala. Judged from our studies using HPGe gamma spectrometric detector, it becomes evident that Uranium ((238U, Thorium ((232Th and Potassium ((40K are the major sources for radioactivity prevailing in the area. Our statistical analyses reveal the existence of a high positive correlation between (238U and (232Th, implicating that the levels of these elements are interdependent. Our SEM-EDAX analyses reveal that titanium (Ti and zircon (Zr are the major trace elements in the sand samples, followed by aluminum, copper, iron, ruthenium, magnesium, calcium, sulphur and lead. This is first of its kind report on the radiation hazard indices on this placer deposit. The average absorbed dose rates (9795 nGy h(-1 computed from the present study is comparable with the top-ranking HBRAs in the world, thus offering the Chavara-Neendakara placer the second position, after Brazil; pertinently, this value is much higher than the World average. The perceptibly high absorbed gamma dose rates, entrained with the high annual external effective dose rates (AEED and average annual gonadal dose equivalent (AGDE values existing in this HBRA, encourage us to suggest for a candid assessment of the impact of the background radiation, if any, on the organisms that inhabit along this placer deposit. Future research could effectively address the issue of the possible impact of natural radiation on the biota inhabiting this HBRA.

  15. Polarization of the cosmic background radiation

    International Nuclear Information System (INIS)

    The results and technique of a measurement of the linear polarization of the Cosmic Background Radiation are discussed. The ground-based experiment utilizes a single horn (70 beam width) Dicke-type microwave polarimeter operating at 33 GHz (9.1 mm). Data taken between May 1978 and February 1980 from both the northern hemisphere (Berkeley Lat. = 380N) and the southern hemisphere (Lima Lat. = 120S) show the radiation to be essentially unpolarized over all areas surveyed. For the 380 declination data the 95% confidence level limit on a linearly polarized component is 0.3 mK for the average and 12 and 24 hour periods. Fitting all data gives the 95% confidence level limit on a linearly polarized component of 0.3 mK for spherical harmonics through third order. Constraints on various cosmological models are discussed in light of these limits

  16. Use of thermoluminescence dosimetry for evaluation of internal beta dose-rate in archaeological dating

    International Nuclear Information System (INIS)

    An experimental technique is described for the absolute determination of beta dose-rate in pottery. The calibrated system utilizes thermoluminescent dosimeters (natural calcium fluoride) which are located external to the pottery sample. These measurements give an evaluation of the dose-rate at the centre of the pottery that is effectively independent of the relative importance of the thorium, uranium and potassium content (typically 12 ppm Th, 3 ppm U and 1% K2O in pottery). This has been checked using analysed uranium, thorium and potassium materials. A dose-rate evaluation may be made after 10-14 d with an accuracy of +-5%, where the dose-rate to the dosimeter is of the order of 0.3 mrad d-1. Although the background dose-rate due to cosmic radiation and that arising from radioactive impurities in the calcium fluoride is significant (one third), measurements have shown that it may be accurately established. The technique described is to be preferred to other systems used in pottery dating because of its independence of relative radioisotope concentration. (orig.)

  17. Use of thermoluminescence dosimetry for evaluation of internal beta dose-rate in archaeological dating

    Science.gov (United States)

    Bailiff, I. K.; Aitken, M. J.

    1980-07-01

    An experimental technique is described for the absolute determination of beta dose-rate in pottery. The calibrated system utilizes thermoluminescent dosimeters (natural calcium fluoride) which are located external to the pottery sample. These measurements give an evaluation of the dose-rate at the centre of the pottery that is effectively independent of the relative importance of the thorium, uranium and potassium content (typically 12 ppm Th, 3 ppm U and 1% K 2O in pottery). This has been checked using analysed uranium, thorium and potassium materials. A dose-rate evaluation may be made after 10-14 d with an accuracy of ±5%, where the dose-rate to the dosimeter is of the order of 0.3 mrad d -1. Although the background dose-rate due to cosmic radiation and that arising from radioactive impurities in the calcium fluoride is significant (one third), measurements have shown that it may be accurately established. The technique described is to be preferred to other systems used in pottery dating because of its independence of relative radioisotope concentration.

  18. Background radiation and childhood leukemia: A nationwide register-based case-control study.

    Science.gov (United States)

    Nikkilä, Atte; Erme, Sini; Arvela, Hannu; Holmgren, Olli; Raitanen, Jani; Lohi, Olli; Auvinen, Anssi

    2016-11-01

    High doses of ionizing radiation are an established cause of childhood leukemia. However, substantial uncertainty remains about the effect of low doses of radiation, including background radiation and potential differences between genetic subgroups of leukemia have rarely been explored. We investigated the effect of the background gamma radiation on childhood leukemia using a nationwide register-based case-control study. For each of the 1,093 cases, three age- and gender matched controls were selected (N = 3,279). Conditional logistic regression analyses were adjusted for confounding by Down syndrome, birth weight (large for gestational age), and maternal smoking. Complete residential histories and previously collected survey data of the background gamma radiation in Finland were used to assess the exposure of the study subjects to indoor and outdoor gamma radiation. Overall, background gamma radiation showed a non-significant association with the OR of childhood leukemia (OR 1.01, 95% CI 0.97, 1.05 for 10 nSv/h increase in average equivalent dose rate to red bone marrow). In subgroup analyses, age group 2-childhood leukemia, particularly at age 2-<7 years. Our findings suggest a larger effect of radiation on leukemia with high hyperpdiploidy than other subgroups, but this result requires further confirmation. PMID:27405274

  19. Inhalation and external doses in coastal villages of high background radiation area in Kollam, India

    International Nuclear Information System (INIS)

    The observational evidence for radiation-induced health effects in humans comes largely from the exposures to high doses received over short periods of time. The rate of induction of any health risk at low doses and dose rates is estimated by extrapolation from observations at high doses. Effects of low dose/low dose rate could be done by the study of populations that have been exposed to slightly above-average natural radiation doses. Southwest coastal line of the Kerala state in India is one such region known to have elevated levels of background radioactivity mainly due to the mineral-rich sand available with high abundance of thorium. In the present work, a study was conducted to investigate the inhalation and external radiation doses to human beings in the high background radiation area along the southwest coast of Kerala. Five hundred dwellings were selected for the study. All the selected houses were at least 10 y old with similar construction. Long-term integrated indoor measurements of the external gamma dose using thermoluminescent dosemeters (TLDs) and the inhalation dose with the SSNTD-based twin-cup dosemeters were carried out in the dwellings simultaneously. Ambient gamma dose measurements were also made with a GM tube-based survey meter while deploying and retrieving the dosemeters. The data show a high degree of heterogeneity. The inhalation dose was found to vary from 0.1 to 3.53 mSv y-1 and the external dose rates had a range of 383-11419 μGy y-1. The external doses measured by the survey meter and TLDs showed an excellent correlation. (authors)

  20. High dose rate brachytherapy for oral cancer

    International Nuclear Information System (INIS)

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. (author)

  1. Risk from radionuclides: a frog's perspective : Accumulation of 137Cs in a riparian wetland, radiation doses, and effects on frogs and toads after low-dose rate exposure

    OpenAIRE

    Stark, Karolina

    2006-01-01

    Threats from man-made radionuclides include waste issues, increasing number of power plants, underground bomb testing, nuclear weapons, and “dirty bombs”. Until recently the ionizing radiation protection system focused on protecting humans with an implied protection of biota. However, goals of sustainable development and precautionary principles for human activity are leading to an inclusion of plant and animal populations in the protection system. From this perspective, the present thesis ex...

  2. Assessment of background gamma radiation and determination of excess lifetime cancer risk in Sabzevar City, Iran in 2014

    Directory of Open Access Journals (Sweden)

    Akbar Eslami

    2016-01-01

    Full Text Available Background: Background gamma radiation levels vary in different locations and depended on many factors such as radiation properties of soil, building materials as well as construction types which human lives on it. People are always exposed to ionizing radiation, which could badly influence their health. The aim of this study was to evaluate the background gamma-ray dose rate and the estimated annual effective dose equivalent and determination of excess lifetime cancer risk in Sabzevar City, Iran. Methods: The aim of this cross-sectional study was to determine the dose rate of background gamma radiation in outdoor an indoor areas, 26 stations were selected using the map of the Sabzevar City. The amount of gamma radiation was measured at 4 months (September to January in 2014 year. The dosimeter used in this study was a survey meter, that is designed for monitoring radiation of x, gamma and beta rays. Results: The obtained results show that there are significant differences between the indoor and outdoor exposures (P> 0.05. We did not observe significant differences between the time of sampling and sampling locations, (P<0.05. The minimum and maximum values of dose rate were found 66±20 nSvh-1 and 198±28 nSvh-1. The annual effective dose for Sabzevar residents was estimated to be 0.85 mSv and also the amount of excess lifetime cancer risk was estimated 3.39×10-3. Conclusion: According to the results, the excess lifetime cancer risk and the annual effective dose for the Sabzavar City residents due to the background gamma radiation was higher than the global average (0.5 mSv. The epidemiological studies have been proposed to evaluate the risk of chronic diseases associated with natural radiation exposure among residents.

  3. A database for a meta-analysis of cancer risk in animals at low doses and dose rates of ionising radiation

    International Nuclear Information System (INIS)

    Results of animal experiments listed in the International Radiobiology Archives (I.R.A.), complemented with data published in peer-reviewed literature since 1996 have been assembled in one data base and the induction of cancer at low doses has been analyzed. In total, approximately 100 separate, independent sets of experimental data have been studied. The main objective of this work is to provide information on radiation risk in the 0-500 mGy range. The data analyzed were those for which no significant reduction of life span was observed in exposed animals; or doses did not exceed 1 Gy; or no cancer was observed in exposed animals. With these criteria data sets with organ doses well in excess of 1 Gy were taken into account. In animals with a low natural incidence of cancer, the difference between the observed number of cancer cases and the prediction of the Linear No-threshold (LNT) hypothesis was compared in each experiment. Following intake of alpha emitters, the number of cancers observed is about 60% of the number of number predicted by the LNT, and only about 56% following intake of beta emitters. In some experiments, statistically weak protective effects were observed following the intake of alpha emitters, whereas apparently statistically strong protective effects were observed in some groups of animals exposed to beta radiation. In animals exposed to low LET radiation and neutrons, both clear excess cancer risk and clear cancer deficits were observed. In a second series of analysis, the several modeling approaches were used to model dose-response. Linear, logistic and probit regression models were examined. For all the data sets examined in this work, the analysis of the data using the LOGISTIC model seems to indicate surplus of negative slopes in the dose-response fits. Finer analyses are underway to determine what parameters are common to experiments which display similar dose-response relationships. If they exist in a sufficient number of experiments

  4. Risk of Low Dose/Low Dose Rate Ionizing Radiation to Humans Symposium at the EMS 2009 Annual Meeting - September 2006

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, William F.; von Borstel, Robert C.; Brenner,; Redpath, J. Leslie; Erickson, Barbra E.; Brooks,

    2009-11-12

    The low dose symposium thoughtfully addressed controversy of risk from low dose radiation exposure, hormesis and radon therapy. The stem cell symposium cogently considered the role of DNA damage and repair in hematopoietic stem cells underlying aging and malignancy and provocatively presented evidence that stem cells may have distinct morphologies and replicative properties, as well as special roles in cancer initiation. In the epigenetics symposium, studies illustrated the long range interaction of epigenetic mechanisms, the roles of CTCF and BORIS in region/specific regulation of epigenetic processes, the impact of DNA damage on epigenetic processes as well as links between epigenetic mechanisms and early nutrition and bystander effects.

  5. Quantitative evaluation of radiation quality indices of non-optimized and optimized single and double plane high-dose-rate interstitial implants

    International Nuclear Information System (INIS)

    In this study radiation indices of an ideal single plane HDR implant for non-optimized and optimized treatment plans to get optimal treatment plan condition, such as inter-source spacing (ISS) and inter-cathetor spacing (ICS) were determined. Thus obtained optimal ISS and ICS conditions were then applied to the single and double plane HDR implants already used in the treatment and compared the theoretical results with clinical ones. For the clinical implants, the tumour control probability (TCP) and normal tissue complications were evaluated using LQ model based relations

  6. The Measuring of the Gamma Dose Rate in the Air at Location of the Sar-Mountain

    International Nuclear Information System (INIS)

    The results of the measured values of gamma dose rate in the air at the location of Sar-mountain (Balkan Peninsula) using autonomous ADL-probe Gamma Tracer system. The difference between levels of the natural background radiation and natural environment has been pointed out at the different chosen measuring overall research of natural radioactivity at the location of Sar-mountain

  7. Tank Z-361 dose rate calculations

    International Nuclear Information System (INIS)

    Neutron and gamma ray dose rates were calculated above and around the 6-inch riser of tank Z-361 located at the Plutonium Finishing Plant. Dose rates were also determined off of one side of the tank. The largest dose rate 0.029 mrem/h was a gamma ray dose and occurred 76.2 cm (30 in.) directly above the open riser. All other dose rates were negligible. The ANSI/ANS 1991 flux to dose conversion factor for neutrons and photons were used in this analysis. Dose rates are reported in units of mrem/h with the calculated uncertainty shown within the parentheses

  8. Terrestrial gamma dose rate in Pahang state Malaysia

    International Nuclear Information System (INIS)

    Environmental terrestrial gamma radiations (TGR) were measured in Pahang state Malaysia between January and April 2013. The TGR dose rates ranged from 26 to 750 nGy h-1. The measurements were done based on geology and soil types of the area. The mean TGR dose rate was found to be 176 ± 5 nGy h-1. Few areas of relatively enhanced activity were located in Raub, Temerloh, Bentong and Rompin districts. These areas have external gamma dose rates of between 500 and 750 nGy h-1. An Isodose map of the state was produced using ArcGIS9 software version 9.3. To evaluate the radiological hazard due to terrestrial gamma dose, the annual effective dose equivalent and the mean population weighted dose rate were calculated and found to be 0.22 mSv year-1 and 168 nGy h-1 respectively. (author)

  9. Human response to high-background radiation environments on Earth and in space

    Science.gov (United States)

    Durante, M.; Manti, L.

    2008-09-01

    The main long-term objective of the space exploration program is the colonization of the planets of the Solar System. The high cosmic radiation equivalent dose rate represents an inescapable problem for the safe establishment of permanent human settlements on these planets. The unshielded equivalent dose rate on Mars ranges between 100 and 200 mSv/year, depending on the Solar cycle and altitude, and can reach values as high as 360 mSv/year on the Moon. The average annual effective dose on Earth is about 3 mSv, nearly 85% of which comes from natural background radiation, reduced to less than 1 mSv if man-made sources and the internal exposure to Rn daughters are excluded. However, some areas on Earth display anomalously high levels of background radiation, as is the case with thorium-rich monazite bearing sand deposits where values 200 400 times higher than the world average can be found. About 2% of the world’s population live above 3 km and receive a disproportionate 10% of the annual effective collective dose due to cosmic radiation, with a net contribution to effective dose by the neutron component which is 3 4 fold that at sea level. Thus far, epidemiological studies have failed to show any adverse health effects in the populations living in these terrestrial high-background radiation areas (HBRA), which provide an unique opportunity to study the health implications of an environment that, as closely as possibly achievable on Earth, resembles the chronic exposure of future space colonists to higher-than-normal levels of ionizing radiation. Chromosomal aberrations in the peripheral blood lymphocytes from the HBRA residents have been measured in several studies because chromosomal damage represents an early biomarker of cancer risk. Similar cytogenetic studies have been recently performed in a cohort of astronauts involved in single or repeated space flights over many years. The cytogenetic findings in populations exposed to high dose-rate background radiation

  10. Annual dose rate calculations for thermoluminescence dating

    International Nuclear Information System (INIS)

    Tabulations of decay data and dose rate calculations that are necessary for TL dating are presented. An effort has been made to collect the latest evaluated data and to catalog them in a form that is easily accessible, so that they may be updated as new revised values are reported. It is suggested that the largest error in thermoluminescence dating will come from sources other than the tabulated particle energies and branching ratios. These include: (a) the alpha to beta thermoluminescence efficiency determination; (b) concentration measurements of K, Rb, Th, and U; (c) all departures from secular equilibrium in the uranium and thorium decay chains; and (d) the imprecise calibration of laboratory radiation sources

  11. Evidence for the Cellular Basis of Intestinal Death in Mice, from an Analysis of Dose-Effect Relationships Modified by Quality of Radiation, Dose Rate, Fractionation and Anoxia

    International Nuclear Information System (INIS)

    When animals are killed by radiation, as by other toxic agents, the dose-effect relationship may be characterized by the LD50 together with the 'spread' or variance of the observations. It is generally accepted that the type of dose-effect curve (a probability curve) obtained in such experiments is to be ascribed to subtle and uncontrollable biological variations within any group of experimental animals. Conditions of irradiation have been used such that the values of LD50 might be widely different, e.g. for intestinal death (at 4-5 days) the LD50 for animals exposed to fast electrons while breathing oxygen was 1020 rad, while for animals breathing nitrogen it was 2800 rad. In that example, the variances of the two sets of data were in exactly the same ratio as the LD50 values, so that the anoxia operated as a dose-modifying agent. For other methods of modifying the LD50, however, this was not true: for example when the LD50 was increased from 1200 to 1600 rad by fractionation the variance remained constant. A computer programme was set up to perform probit analyses on animal survival curves, and to test whether 'dose modification' or 'parallel slopes' (i.e. variances proportional to LD50 values, or constant variances) provides the better model for the comparison of the results of irradiation in any two sets of conditions. It was found , in general, that conditions which give true dose modification of cell survival curves (e.g. anoxia) are also dose-modifying for the animal survival curves, whereas conditions which act as if to change the shoulder of a cell survival curve, but not its slope (e.g. dose fractionation) act similarly in respect of animal survival curves. Thus the biological variability which expresses itself in the probability curve for animal survival seems to be closely linked with the survival curve for the particular cell population the depletion of which leads to the gastro-intestinal • syndrome. (author)

  12. Preliminary survey of outdoor gamma dose rates in Lesvos Island (Greece)

    International Nuclear Information System (INIS)

    This study reports the first attempt to record the radioactive background due to gamma radiation in Lesvos Island (Greece). The study reports the results from 335 outdoor total gamma effective dose rate measurements conducted using GPS navigation and a Geiger-Mueller detector (Bicron, Micro Sievert) on the whole surface of the island together with a digital map produced by appropriate mapping GIS programme. The study also reports the measurements of outdoor gamma dose rates due to the 238U, 232Th and 40K radionuclides as estimated via in situ gamma-ray spectrometry measurements performed at 26 sites using a 3 x 3 inch NaI (thallium activated) portable detector. The results from the outdoor total gamma effective dose rates range between 0.0023 and 0.28 μSv h-1. The highest outdoor total gamma effective dose rates (0.013-0.28 μSv h-1) were detected in the northeastern part of the island and the intermediate rates (0.066-0.13 μSv h-1) in the central region. The outdoor gamma dose rates due to 238U, 232Th and 40K radionuclides range between 1.7 ± 0.8 and 154 ± 7 nGy h-1 with an average of 86±6 nGy h-1. The average contribution of each of the examined radionuclides (238U, 232Th and 40K) to the total gamma dose rate was found to be equal to 12±4% for 238U, 58±6% for 232Th and 29±7% for 40K, respectively. (authors)

  13. Preliminary survey of outdoor gamma dose rates in Lesvos Island (Greece).

    Science.gov (United States)

    Petalas, Anastasios B; Vogiannis, Efstratios; Nikolopoulos, Dimitrios; Halvadakis, Constantinos P

    2005-01-01

    This study reports the first attempt to record the radioactive background due to gamma radiation in Lesvos Island (Greece). The study reports the results from 335 outdoor total gamma effective dose rate measurements conducted using GPS navigation and a Geiger-Muller detector (Bicron, Micro Sievert) on the whole surface of the island together with a digital map produced by appropriate mapping GIS programme. The study also reports the measurements of outdoor gamma dose rates due to the 238U, 232Th and 40K radionuclides as estimated via in situ gamma-ray spectrometry measurements performed at 26 sites using a 3 x 3 inch NaI (thallium activated) portable detector. The results from the outdoor total gamma effective dose rates range between 0.0023 and 0.28 microSv h(-1). The highest outdoor total gamma effective dose rates (0.013-0.28 microSv h(-1)) were detected in the northeastern part of the island and the intermediate rates (0.066-0.13 microSv h(-1)) in the central region. The outdoor gamma dose rates due to 238U, 232Th and 40K radionuclides range between 1.7 +/- 0.8 and 154 +/- 7 nGy h(-1) with an average of 86 +/- 6 nGy h(-1). The average contribution of each of the examined radionuclides (238U, 232Th and 40K) to the total gamma dose rate was found to be equal to 12 +/- 4% for 238U, 58 +/- 6% for 232Th and 29 +/- 7% for 40K, respectively. PMID:15728423

  14. Beta particle dose rates to micro-organisms in soil

    International Nuclear Information System (INIS)

    Studies were made to estimate the beta-particle dose rates to micro-organisms of various sizes in soil. The small insects and organisms living in soil are constantly exposed to beta-radiation arising from naturally occuring radionuclides in soil as in this case no overlying tissue shields them. The technique of measuring beta-particle dose rate consisted of using of a thin plastic scintillator to measure the pulse height distribution as the beta particle traverses the scintillator. The integrated response was determined by the number and size of the photomultiplier pulses. From the data of soil analyses it was estimated that typically about 29% of the beta particles emitted per gm. of soil were contributed by the U/Ra series, 21% by the Th series and about 50% by potassium. By combining the individual spectra of these three radionuclides in the proportion found in a typical soil, a resultant spectrum was computed representing the energy distribution of the beta particles. The dose rate received by micro-organisms of different shape and size in soil was derived from the equilibrium dose rates combined with a 'Geometrical Factor' of the organisms. For small organisms, the dose rates did not vary between the spherical and cylindrical types, but in the case of larger organisms, the dose rates were found to be greater for the spherical types of the same diameter. (auth.)

  15. Study of the radiation levels in low dose rate brachytherapy zones of the National Institute of Neoplastic Illnesses; Estudio de los Niveles de Radiacion en Zonas de Braquiterapia de Baja Tasa de Dosis del Instituto Nacional de Enfermedades Neoplasicas

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa J, N.; Mora Y, B. [Instituto Nacional de Enfermedades Neoplasicas, Lima (Peru)]. e-mail: navorf01@yahoo.es

    2006-07-01

    The present study has as objective to evaluate the radiation levels of the Brachytherapy work areas of low dose rate (Gammateque, nurses station and of hospitalization rooms of patients RIC of 4th, 5th Floor-East) and to estimate the effective dose of the occupationally exposed personnel and the public in general. The measurements of the dose rate in these areas, were registered with a radiations monitor Inspector trademark, during a period of 60 days, without altering the routinary work conditions. The more high levels of environmental dose equivalent rate registered in the different work areas its are of 1.41 and 47.78 {mu}Sv/h rooms 1 and 2 in the Gammateque environments, in the hospitalization rooms of the 4th and 5th floor in the point 1 are of 40.77 and 23.67, {mu}Sv/h respectively and in the point 2 are of 129.19 and 39.93, {mu}Sv/h respectively, and in the nurses station of the 4th and 5th floor its are respectively of 7.62 u Sv/h and 0.45 u Sv/h. According to the carried out measurements and the permanency in the work place is possible to estimate the effective dose involved to the occupationally exposed personnel. The personnel that works in Gammateque could be receiving respectively as maximum dose 0.61 mSv/month, and the personnel that works in the nurses station of 13.17 and 0.78 mSv/year in the 4th and 5th floor. These registered differences among the two floors are due to that the 5th floor counts with the shielding systems (screen) contrary to the 4th, another of the factors is the distribution form of the patient beds RIC. We should have present that the radiation levels although in some cases it is very high, however, they are below of the permissible limits according to standards, but it is still possible to reduce even more, the radiation levels in the critical points fulfilling with the ALARA principle. (Author)

  16. Variation of OER with dose rate

    International Nuclear Information System (INIS)

    The oxygen enhancement ratio (OER) has been measured as a function of dose rate from 276 Gy/hr to 0.89 Gy/hr for V-79 cells irradiated at 230C or 370C. As dose rate is decreased, the OER initially increases, from a value of 3.0 to a maximum value of 3.7 to 4.0, at a dose rate between 20 and 60 Gy/hr. The OER subsequently decreases with further dose rate reduction to a minimum value of 2.4 at the lowest dose rate. Similar experiments conducted with cells in nutrient deprived conditions exhibited a monotonic decrease in OER from 3.0 to 1.7 with dose rate reduction. These experimental findings can be understood in terms of the sublethal damage repair capability of cells under different pO2 and nutrient conditions

  17. Background radiation in two locations in Deaf Smith and Swisher Counties within the Palo Duro Basin

    International Nuclear Information System (INIS)

    Data on external background radiation doses resulting from cosmic, terrestrial, and fallout sources and on concentrations of radioactivity in environmental media are presented and discussed. Doses to individuals located at the approximate centers of two locations in Texas, one in Deaf Smith County and the other in Swisher County, are given, as are the population doses to people residing within 50 miles of each of the approximate centers. No adjustments have been made for the effects of buildings on radiation doses - that is, the shielding from external radiation afforded by the buildings and radiation from building materials are not accounted for. Concentrations of radioactivity in air, water, and milk in the region are also given. Because of the lack of specific information on background radiation at the locations, the external-dose rates to people and the radioactivity levels in environmental media for the region have been taken from the literature. A background radiation survey will be conducted in the Palo Duro Basin to obtain additional data. 26 references, 3 figures, 15 tables

  18. Ultraviolet Background Radiation from Cosmic Structure Formation

    CERN Document Server

    Miniati, F; White, S D M; Bianchi, S; Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2004-01-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated by cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ry. The bulk of the radiation is produced by objects in the mass range 10^11-13 M_solar, i.e. large galaxies and small groups. We compute a composite UVB spectrum due to QSO, stellar and thermal components. The ratio of the UVB intensities at the H and He Lyman limits increases from 60 at z=2 to more than 300 at z=6. A comparison of the resulting photoionization rates to the observed Gunn-Peterson effect at high redshifts constrains the escape fraction of ionizing photons from galaxies to be less than a few percent. Near 1 Ry, thermal and stellar emission are comparable amoun...

  19. The OER at low-dose rates

    International Nuclear Information System (INIS)

    There is increasing interest in the treatment of human cancers with multifraction beam therapy at low dose-rates, on the assumption that the OER at low dose-rates is smaller than that at high dose-rates. A comparison has therefore been made of various published values of OER as a function of γ dose-rate for Vicia faba, HeLa cells, P388 cells, hamster cells and chromosome aberrations. The mean value of the OER at low dose-rate was about 20% lower than the mean OER obtained at high dose-rate, although two OER values at low dose-rates were significantly lower than the other reported values. There are technical difficulties associated with maintaining the test systems under hypoxic conditions for long periods of time and the observed decrease in cloning efficiency of hypoxic control cells indicates that cells can be damaged by this treatment alone. It is therefore possible that the high dose-rate OER values would have been reduced if the cells irradiated at high dose-rates under oxic and anoxic conditions had had a pre-treatment period of storage under anoxic conditions. (U.K.)

  20. Dose rate correction in medium dose rate brachytherapy for carcinoma cervix

    International Nuclear Information System (INIS)

    Purpose: To establish the magnitude of brachytherapy dose reduction required for stage IIB and III carcinoma cervix patients treated by external radiation and medium dose rate (MDR) brachytherapy at a dose rate of 220±10 cGy/h at point A.Materials and methods: In study-I, at the time of MDR brachytherapy application at a dose rate of 220±10 cGy/h at point A, patients received either 3060 cGy, a 12.5% dose reduction (MDR-12.5), or 2450 cGy, a 30% dose reduction (MDR-30), to point A and they were compared to a group of previously treated LDR patients who received 3500 cGy to point A at a dose rate of 55-65 cGy/h. Study-II was a prospective randomized trial and patients received either 2450 cGy, a 30% dose reduction (MDR-II (30)) or 2800 cGy, a 20% dose reduction (MDR-II (20)), at point A. Patients were evaluated for local control of disease and morbidity. Results: In study-I the 5-year actuarial local control rate in the MDR-30 and MDR-12.5 groups was 71.7±10% and 70.5±10%, respectively, compared to 63.4±10% in the LDR group. However, the actuarial morbidity (all grades) in the MDR-12.5 group was 58.5±14% as against 34.9±9% in the LDR group (P3 developed complication as against 62.5% of those receiving a rectal BED of (1403 (χ2=46.43; P<0.001). Conclusion: We suggest that at a dose rate of 220±10 cGy/h at point A the brachytherapy dose reduction factor should be around 30%, as suggested by radiobiological data, to keep the morbidity as low as possible without compromising the local control rates. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  1. Thermal radiation of various gravitational backgrounds

    OpenAIRE

    Akhmedov, Emil T.; Akhmedova, Valeria; Pilling, Terry; Singleton, Douglas

    2006-01-01

    We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasi--classical tunneling of particles through a gravitational barrier. We show that our procedure can reproduce the results of Hawking and Unruh radiation. We also show that under certain kinds of coordinate transformations the temperature of the thermal radiation will change in the case of the Schwarzschild black holes. ...

  2. Dose-rate effects for apoptosis and micronucleus formation in gamma-irradiated human lymphocytes

    International Nuclear Information System (INIS)

    We have compared dose-rate effects for γ-radiation-induced apoptosis and micronucleus formation in human lymphocytes. Long-term assessment of individual radiation-induced apoptosis showed little intraindividual variation but significant interindividual variation. The effectiveness of radiation exposure to cause apoptosis or micronucleus formation was reduced by low-dose-rate exposures, but the reduction was apparent at different dose rates for these two end points. Micronucleus formation showed a dose-rate effect when the dose rate was lowered to 0.29 cGy/min, but there was no accompanying cell cycle delay. A further increase in the dose-rate effect was seen at 0.15 cGy/min, but was now accompanied by cell cycle delay. There was no dose-rate effect for the induction of apoptosis until the dose rate was reduced to 0.15 cGy/min, indicating that the mechanisms or signals for processing radiation-induced lesions for these two end points must be different at least in part. There appear to be two mechanisms that contribute to the dose-rate effect for micronucleus formation. One of these does not affect binucleate cell frequency and occurs at dose rates higher than that required to produce a dose-rate effect for apoptosis, and one affects binucleate cell frequency, induced only at the very low dose rate which coincidentally produces a dose-rate effect for apoptosis. Since the dose rate at which cells showed reduced apoptosis as well as a further reduction in micronucleus formation was very low, we conclude that the processing of the radiation-induced lesions that induce apoptosis, and some micronuclei, is very slow in quiescent and PHA-stimulated lymphocytes, respectively. (author)

  3. Dose-rate effects for apoptosis and micronucleus formation in gamma-irradiated human lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Boreham, D.R.; Dolling, J.-A.; Maves, S.R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Siwarungsun, N. [Chulalongkorn Univ., Bangkok (Thailand); Mitchel, R.E.J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2000-07-01

    We have compared dose-rate effects for {gamma}-radiation-induced apoptosis and micronucleus formation in human lymphocytes. Long-term assessment of individual radiation-induced apoptosis showed little intraindividual variation but significant interindividual variation. The effectiveness of radiation exposure to cause apoptosis or micronucleus formation was reduced by low-dose-rate exposures, but the reduction was apparent at different dose rates for these two end points. Micronucleus formation showed a dose-rate effect when the dose rate was lowered to 0.29 cGy/min, but there was no accompanying cell cycle delay. A further increase in the dose-rate effect was seen at 0.15 cGy/min, but was now accompanied by cell cycle delay. There was no dose-rate effect for the induction of apoptosis until the dose rate was reduced to 0.15 cGy/min, indicating that the mechanisms or signals for processing radiation-induced lesions for these two end points must be different at least in part. There appear to be two mechanisms that contribute to the dose-rate effect for micronucleus formation. One of these does not affect binucleate cell frequency and occurs at dose rates higher than that required to produce a dose-rate effect for apoptosis, and one affects binucleate cell frequency, induced only at the very low dose rate which coincidentally produces a dose-rate effect for apoptosis. Since the dose rate at which cells showed reduced apoptosis as well as a further reduction in micronucleus formation was very low, we conclude that the processing of the radiation-induced lesions that induce apoptosis, and some micronuclei, is very slow in quiescent and PHA-stimulated lymphocytes, respectively. (author)

  4. Ultraviolet background radiation from cosmic structure formation

    Science.gov (United States)

    Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2004-03-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated during cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ryd. The bulk of the radiation is produced by objects in the mass range 1011-1013 Msolar, i.e. large galaxies and small groups. We compute a composite UVB spectrum due to quasi-stellar object (QSO), stellar and thermal components. The ratio of the UVB intensities at the H and He Lyman limits increases from 60 at z= 2 to more than 300 at z= 6. A comparison of the resulting photoionization rates to the observed Gunn-Peterson effect at high redshifts constrains the escape fraction of ionizing photons from galaxies to be less than a few per cent. Near 1 Ryd, thermal and stellar emission are comparable, amounting to about 10, 20 and 35 per cent of the total flux at redshifts of 3, 4.5 and higher, respectively. However, near the ionization threshold for He II, the thermal contribution is much stronger. It is comparable to the QSO intensity already at redshift ~3 and dominates at redshifts above 4. Thermal photons alone are enough to produce and sustain He II reionization already at z~ 6. We discuss the possible implications of our results for the thermal history of the intergalactic medium, in particular for He II reionization.

  5. Brachytherapy treatment with high dose rate

    International Nuclear Information System (INIS)

    Retrospectively analyze results and prognostic factors of cervical cancer patients treated with radio concomitant cisplatin-based chemotherapy, radiation therapy combined modality. Methods: From January 2003 to December 2007, 198 patients with invasive cervical cancer were treated at the Oncology Department of Hospital Robau Celestino Hernandez (brachytherapy performed at INOR). The most common age group was 31 to 40 years. The histology in squamous cell carcinoma accounted for 84.3% of cases. The treatment consisted of external pelvic irradiation and vaginal brachytherapy, high dose rate. Concomitant chemotherapy consisted of cisplatin 40 mg/m2 weekly with a maximum of 70 mg for 5 weeks. Results: 66.2% of patients completed 5 cycles of chemotherapy. The median overall survival was 39 months, overall survival, disease-free survival and survival free of locoregional recurrence at 5 years of 78%, 76% and 78.6% respectively .. We found that clinical stage, histological type (adenocarcinoma worst outcome) were statistically related to level of response. Conclusions: Treatment with external pelvic radiation, brachytherapy and concurrent weekly cisplatin in patients with stage IIIB cervical cancer is feasible in the Chilean public health system, well tolerated and results comparable to international literature. (Author)

  6. Mapping the terrestrial air-absorbed gamma dose rate based on the data of airborne gamma-ray spectrometry in southern cities of China

    International Nuclear Information System (INIS)

    An environmental radioactivity survey by Airborne Gamma-ray Spectrometry (AGS) on a large scale was undertaken in Zhuhai Zone (ZZ) and Shenzhen Zone (SZ), which include major cities in southern China, covering areas of 3800 km2 and 4660 km2, respectively. The estimated dose rates by AGS have been compared with observed results by ionization chamber and portable dosemeter. Maps of the terrestrial dose rate at 1m above ground level have been calculated based on the data of AGS. The mean dose rates are 84.37 ± 51.69 and 82.10 ± 32.98 nGy/h in ZZ and SZ, and the maximum rates are 343.11 and 368.36 nGy/h, respectively. Dose rates in some places are above 180 nGy/h; the areas covered where 149 km2 in ZZ and 43 km2 in SZ. The dominant geological conditions that evidently contribute to the radioactive anomalies are outcrops of Middle and Late Jurassic and Cretaceous biotitic-granite. The growth of industrialization and urbanization has dramatically altered radiation background. Stone mining results in the increase of radiation levels with maximum dose rates approaching 368.36 nGy/h in an open pit. The investigation results provide valuable background data and give a good example for mapping nationwide natural radiation terrestrial dose rates in China by AGS. (author)

  7. Research on the determination of 235U fission number by delayed γ-rays absorbed dose rates

    International Nuclear Information System (INIS)

    Background: The determination method of 235U fission number by detecting fission products using HPGe detector has been established before. But in some special cases, we need to get the fission number in-time in high intensity radiation environment. HPGe detector has its limitation due to the complex y spectrum accompany with high flux. Purpose: To get rid of the limitation mentioned above, a new method is introduced by detecting the delayed γ-rays absorbed dose rates. Methods: By using independent fission yield together with radioactive decay dates from CENDL 3.0 and ENDF BVII.1, dynamic calculation for total absorbed dose rate in air 1 meter from the source whose compositions were thermal neutron-induced fission products of 235U has been done. Results: A set of absorbed dose rate data of 235U fission products irradiated through fast rabbit irradiation system on Xi'an pulse reactor was recorded. The deviation of the fission neutron number between method by γ-rays absorbed dose rates and method by HPGe detector is 7%. Conclusion: It's feasible to determine the fission neutron number of 235U using delayed γ-rays absorbed dose rates in a high intensity radiated environment. (authors)

  8. Implementation of High Dose Rate Brachytherapy in Limited Resource Settings

    International Nuclear Information System (INIS)

    Brachytherapy is an essential component of the curative treatment of cervical cancer, a disease with high incidence in many developing countries The IAEA supports the use of high dose rate brachytherapy for centres with a large number of patients with this disease. HDR brachytherapy is also used in other common cancers such as breast cancer, lung, oesophagus and prostate. This publication provides guidance to radiation oncologists, medical physicists and planners on establishing and operating a high dose rate brachytherapy unit with modern standards and presents the main issues to be addressed for its effective and safe operation

  9. Indoor terrestrial gamma dose rate mapping in France: a case study using two different geostatistical models.

    Science.gov (United States)

    Warnery, E; Ielsch, G; Lajaunie, C; Cale, E; Wackernagel, H; Debayle, C; Guillevic, J

    2015-01-01

    information, which is exhaustive throughout France, could help in estimating the telluric gamma dose rates. Such an approach is possible using multivariate geostatistics and cokriging. Multi-collocated cokriging has been performed on 1*1 km(2) cells over the domain. This model used gamma dose rate measurement results and GUP classes. Our results provide useful information on the variability of the natural terrestrial gamma radiation in France ('natural background') and exposure data for epidemiological studies and risk assessment from low dose chronic exposures. PMID:25464050

  10. Comparison of computational models for estimation of whole body and organ radiation dose in rainbow trout from uptake of iodine-131 - Comparison of rainbow trout phantoms for estimation of whole body and organ radiation dose rates from uptake of iodine-131 in freshwater systems

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Nicole E. [Department of Environmental and Engineering Sciences, Clemson University, Clemson, South Carolina, 29634 (United States); Johnson, Thomas E.; Ruedig, Elizabeth; Pinder, John E. III [Department of Environmental and Radiological Health Sciences, Colorado State University, 1681 Campus Delivery, Fort Collins, Colorado, 80523 (United States)

    2014-07-01

    Internal radiation dose rates to biota are typically calculated utilizing dose conversion factors (DCF), which are values for absorbed dose rate per activity concentration (i.e. mGy d{sup -1} per Bq g{sup -1}). The current methodology employed by both the ICRP and within the ERICA Integrated Approach for calculating dose conversion coefficients is to use Monte Carlo modeling of a homogeneously distributed radionuclide within an ellipsoidal phantom chosen to represent a particular organism. It has been shown that for whole-body DCF, homogenous distribution is a reasonable assumption for electrons, and is associated with an uncertainty of less than 30% for photons. However, if a radionuclide has a specific tissue tropism (e.g. iodine-131 in thyroid) a much higher dose will be received by the organ or tissue than by the whole body. Internal organs are modeled generically as spheres within the ellipsoid phantom, due to the complex and variable nature of organ structure and arrangement within different types of organisms. Ratios of whole-body to organ mass offer conservative conversions of whole-body to organ specific DCF (Gomez-Ros et al 2008), but may considerably overestimate the organ dose; more accurate estimates can be made based on specific absorbed fractions and activity concentrations. Establishment of appropriate screening levels in the regulatory paradigm requires incorporation of sufficient knowledge of dose effects; the ICRP currently lists no derived consideration reference levels for organs, meaning that specific risks associated with organ dose rates are unavailable (ICRP 108). Model comparison and refinement is important in the process of determining both dose rates and dose effects, and here we develop and compare three models for rainbow trout (Oncorhynchus mykiss): the simple geometry described above, a more specific geometry employing anatomically relevant organ size and location, and voxel reconstruction of internal anatomy obtained from CT imaging

  11. Biological effect of Pulsed Dose Rate brachytherapy with stepping sources

    International Nuclear Information System (INIS)

    Purpose: To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR), for local tissue dose-rates between those 'averaged over the whole pulse' and the instantaneous high dose rates close to the dwell positions. An earlier publication (Fowler and Mount 1992) had shown that, for dose rates (averaged for the duration of the pulse) up to 3 Gy/h, little change of isoeffect doses from continuous low dose rate (CLDR) are expected, unless larger doses per fraction than 1 Gy are used, and especially if components of very rapid repair are present with half-times of less than about 0.5 hours. However, local and transient dose rates close to stepping sources can be up to several Gy per minute. Methods: Calculations were done assuming the linear quadratic formula for radiation damage, in which only the dose-squared term is subject to repair, at a constant exponential rate. The formula developed by Dale for fractionated low-dose-rate radiotherapy was used. A constant overall time of 140 hours and constant total dose of 70 Gy were assumed throughout, the continuous low dose-rate of 0.5 Gy/h (CLDR) providing the unitary standard effects for each PDR condition. Effects of dose-rates ranging from 4 Gy/h to 120 Gy/h (HDR at 2 Gy/min) were studied, and T (1(2)) from 4 minutes to 1.5 hours. Results: Curves are presented relating the ratio of increased biological effect (proportional to log cell kill) calculated for PDR relative to CLDR. Ratios as high as 1.5 can be found for large doses per pulse (> 1 Gy) at high instantaneous dose-rates if T (1(2)) in tissues is as short as a few minutes. The major influences on effect are dose per pulse, half-time of repair in the tissue, and - when T (1(2)) is short - the instantaneous dose-rate. Maximum ratios of PDR/CLDR effect occur when the dose-rate is such that pulse duration is approximately equal to T (1(2)) of repair. Results are presented for late-responding tissues, the differences from CLDR

  12. External dose rates in coastal urban environments in Brazil

    International Nuclear Information System (INIS)

    A long term activity aiming on assessing the exposure of the Brazilian population to natural background radiation is being developed at IRD/CNEN. Several research groups within IRD work in this activity, although mostly as a parallel work associated to main research lines followed by researches of the institution. One main activity is related to the raise of external gamma dose rates throughout the country. The objective of this work is to present results from recent surveys performed as part of the emergency preparedness for radiological emergencies during major public events in Brazil, such as the the World Youth Day, held in Rio de Janeiro in 2013, and the Confederations Cup and the FIFA World Cup soccer games, in 2013 and 2014, respectively. In this work, only the recent (2014) coastal urban environments measurements were included. Average kerma rates for Fortaleza is 80 ± 23 nGy/h, for Vitoria is 96 ± 33 nGy/h and for Angra dos Reis is 147 ± 16 nGy/h. These results are then compared to previous results on other coastal urban towns (Rio de Janeiro, Niterói and Salvador), and with the high background coastal area of Guarapari town. (authors)

  13. Assessing dose rate distributions in VMAT plans

    Science.gov (United States)

    Mackeprang, P.-H.; Volken, W.; Terribilini, D.; Frauchiger, D.; Zaugg, K.; Aebersold, D. M.; Fix, M. K.; Manser, P.

    2016-04-01

    Dose rate is an essential factor in radiobiology. As modern radiotherapy delivery techniques such as volumetric modulated arc therapy (VMAT) introduce dynamic modulation of the dose rate, it is important to assess the changes in dose rate. Both the rate of monitor units per minute (MU rate) and collimation are varied over the course of a fraction, leading to different dose rates in every voxel of the calculation volume at any point in time during dose delivery. Given the radiotherapy plan and machine specific limitations, a VMAT treatment plan can be split into arc sectors between Digital Imaging and Communications in Medicine control points (CPs) of constant and known MU rate. By calculating dose distributions in each of these arc sectors independently and multiplying them with the MU rate, the dose rate in every single voxel at every time point during the fraction can be calculated. Independently calculated and then summed dose distributions per arc sector were compared to the whole arc dose calculation for validation. Dose measurements and video analysis were performed to validate the calculated datasets. A clinical head and neck, cranial and liver case were analyzed using the tool developed. Measurement validation of synthetic test cases showed linac agreement to precalculated arc sector times within  ±0.4 s and doses  ±0.1 MU (one standard deviation). Two methods for the visualization of dose rate datasets were developed: the first method plots a two-dimensional (2D) histogram of the number of voxels receiving a given dose rate over the course of the arc treatment delivery. In similarity to treatment planning system display of dose, the second method displays the dose rate as color wash on top of the corresponding computed tomography image, allowing the user to scroll through the variation over time. Examining clinical cases showed dose rates spread over a continuous spectrum, with mean dose rates hardly exceeding 100 cGy min-1 for conventional

  14. Structures in the microwave background radiation

    CERN Document Server

    Meissner, K A; Ruszczycki, B

    2012-01-01

    We compare the actual WMAP maps with artificial, purely statistical maps of the same harmonic content to argue that there are, with confidence level 99.7 %, ring-type structures in the observed cosmic microwave background.

  15. Natural radioactivity and associated radiation characteristic of the new high background radiation area of lambwe east southern Kenya

    International Nuclear Information System (INIS)

    Rocks and soils from a number of areas underlined by carbonatite rocks in Kenya have been associated with high levels of natural background radioactivity. People in such high background radiation areas (HBRA), are exposed to abnormally high annual absorbed dose (that have health implications) than the global normal 1 mSvyr-1. In this paper, results of field background radiation measurements, activity concentrations of primordial radionuclides in (mainly carbonatite rock and soil) matrices, and estimated annual external effective dose rates are presented for South and North Ruri hills in Lambwe East location of Suba District, which lies roughly between latitudes 0°30'S and 1°00'S, bounded on the east by longitude 34°30'E and on the west by the shores of Lake Victoria 16 and Winnam Gulf. Altitudes in the region range from about 1000 m on the shores of Lake Victoria to above 1800 m on top of the Ruri hills. The main geological features are carbonatite formations. Twenty one samples were analyzed using high-purity germanium (HPGe) gamma-ray spectrometer. The activity concentrations ranged 14.18 - 6559.99 Bqkg-1 (average: 1396.85 Bqkg-1) for Th-232; 2.73 - 499.24 Bqkg-1 (average: 178.69 Bqkg-1) for U-238; and 56.67 - 1454.73 Bqkg-1 (average: 508.67 Bqkg-1) for K-40. The variability in Th distribution could be due to another contributing factor apart from carbonatite: Homa hills geothermal field fluids might be responsible for delivery of Th to surface rocks; some hot spots have travertine deposits. Measured absorbed dose rates in air outdoors range 700 - 6000.00 nGyh-1 (mean: 2325.84 nGy h-1); assuming 0.4 occupancy factor, these values correspond to individual annual effective dose rates of 1.717 - 14.717 mSvyr-1 (mean: 5.705 mSv yr-1). Measured absorbed dose rates are higher than calculated values since they include the contribution of cosmic rays. The natural radioactivity is fractionated with higher levels in the soils than carbonatite rocks

  16. Spectral Analysis in High Radiation Space Backgrounds with Robust Fitting

    Science.gov (United States)

    Lasche, G. P.; Coldwell, R. L.; Nobel, L. A.; Rester, A. C.; Trombka, J. I.

    1997-01-01

    Spectral analysis software is tested for its ability to fit spectra from space. The approach, which emphasizes the background shape function, is uniquely suited to the identification of weak-strength nuclides in high-radiation background environments.

  17. Computed Tomography–Guided Interstitial High-Dose-Rate Brachytherapy in Combination With Regional Positive Lymph Node Intensity-Modulated Radiation Therapy in Locally Advanced Peripheral Non–Small Cell Lung Cancer: A Phase 1 Clinical Trial

    International Nuclear Information System (INIS)

    Purpose: To assess the technical safety, adverse events, and efficacy of computed tomography (CT)-guided interstitial high-dose-rate (HDR) brachytherapy in combination with regional positive lymph node intensity modulated radiation therapy in patients with locally advanced peripheral non–small cell lung cancer (NSCLC). Methods and Materials: Twenty-six patients with histologically confirmed NSCLC were enrolled in a prospective, officially approved phase 1 trial. Primary tumors were treated with HDR brachytherapy. A single 30-Gy dose was delivered to the 90% isodose line of the gross lung tumor volume. A total dose of at least 70 Gy was administered to the 95% isodose line of the planning target volume of malignant lymph nodes using 6-MV X-rays. The patients received concurrent or sequential chemotherapy. We assessed treatment efficacy, adverse events, and radiation toxicity. Results: The median follow-up time was 28 months (range, 7-44 months). There were 3 cases of mild pneumothorax but no cases of hemothorax, dyspnea, or pyothorax after the procedure. Grade 3 or 4 acute hematologic toxicity was observed in 5 patients. During follow-up, mild fibrosis around the puncture point was observed on the CT scans of 2 patients, but both patients were asymptomatic. The overall response rates (complete and partial) for the primary mass and positive lymph nodes were 100% and 92.3%, respectively. The 1-year and 2-year overall survival (OS) rates were 90.9% and 67%, respectively, with a median OS of 22.5 months. Conclusion: Our findings suggest that HDR brachytherapy is safe and feasible for peripheral locally advanced NSCLC, justifying a phase 2 clinical trial

  18. Computed Tomography–Guided Interstitial High-Dose-Rate Brachytherapy in Combination With Regional Positive Lymph Node Intensity-Modulated Radiation Therapy in Locally Advanced Peripheral Non–Small Cell Lung Cancer: A Phase 1 Clinical Trial

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Li; Zhang, Jian-wen; Lin, Sheng; Luo, Hui-Qun; Wen, Qing-Lian; He, Li-Jia; Shang, Chang-Ling; Ren, Pei-Rong; Yang, Hong-Ru; Pang, Hao-Wen; Yang, Bo; He, Huai-Lin [Department of Oncology, Affiliated Hospital of Luzhou Medical College, Luzhou (China); Chen, Yue, E-mail: chenyue5523@126.com [Department of Nuclear Medicine, Affiliated Hospital of Luzhou Medical College, Luzhou (China); Wu, Jing-Bo, E-mail: wjb6147@163.com [Department of Oncology, Affiliated Hospital of Luzhou Medical College, Luzhou (China)

    2015-08-01

    Purpose: To assess the technical safety, adverse events, and efficacy of computed tomography (CT)-guided interstitial high-dose-rate (HDR) brachytherapy in combination with regional positive lymph node intensity modulated radiation therapy in patients with locally advanced peripheral non–small cell lung cancer (NSCLC). Methods and Materials: Twenty-six patients with histologically confirmed NSCLC were enrolled in a prospective, officially approved phase 1 trial. Primary tumors were treated with HDR brachytherapy. A single 30-Gy dose was delivered to the 90% isodose line of the gross lung tumor volume. A total dose of at least 70 Gy was administered to the 95% isodose line of the planning target volume of malignant lymph nodes using 6-MV X-rays. The patients received concurrent or sequential chemotherapy. We assessed treatment efficacy, adverse events, and radiation toxicity. Results: The median follow-up time was 28 months (range, 7-44 months). There were 3 cases of mild pneumothorax but no cases of hemothorax, dyspnea, or pyothorax after the procedure. Grade 3 or 4 acute hematologic toxicity was observed in 5 patients. During follow-up, mild fibrosis around the puncture point was observed on the CT scans of 2 patients, but both patients were asymptomatic. The overall response rates (complete and partial) for the primary mass and positive lymph nodes were 100% and 92.3%, respectively. The 1-year and 2-year overall survival (OS) rates were 90.9% and 67%, respectively, with a median OS of 22.5 months. Conclusion: Our findings suggest that HDR brachytherapy is safe and feasible for peripheral locally advanced NSCLC, justifying a phase 2 clinical trial.

  19. Attenuation measurements show that the presence of a TachoSil surgical patch will not compromise target irradiation in intra-operative electron radiation therapy or high-dose-rate brachytherapy

    International Nuclear Information System (INIS)

    Surgery of locally advanced and/or recurrent rectal cancer can be complemented with intra-operative electron radiation therapy (IOERT) to deliver a single dose of radiation directly to the unresectable margins, while sparing nearby sensitive organs/structures. Haemorrhages may occur and can affect the dose distribution, leading to an incorrect target irradiation. The TachoSil (TS) surgical patch, when activated, creates a fibrin clot at the surgical site to achieve haemostasis. The aim of this work was to determine the effect of TS on the dose distribution, and ascertain whether it could be used in combination with IOERT. This characterization was extended to include high dose rate (HDR) intraoperative brachytherapy, which is sometimes used at other institutions instead of IOERT. CT images of the TS patch were acquired for initial characterization. Dosimetric measurements were performed in a water tank phantom, using a conventional LINAC with a hard-docking system of cylindrical applicators. Percentage Depth Dose (PDD) curves were obtained, and measurements made at the depth of dose maximum for the three clinically used electron energies (6, 9 and 12MeV), first without any attenuator and then with the activated patch of TS completely covering the tip of the IOERT applicator. For HDR brachytherapy, a measurement setup was improvised using a solid water phantom and a Farmer ionization chamber. Our measurements show that the attenuation of a TachoSil patch is negligible, both for high energy electron beams (6 to 12MeV), and for a HDR 192Ir brachytherapy source. Our results cannot be extrapolated to lower beam energies such as 50 kVp X-rays, which are sometimes used for breast IORT. The TachoSil surgical patch can be used in IORT procedures using 6MeV electron energies or higher, or HDR 192Ir brachytherapy

  20. Emergency preparedness for Tarapur site: environmental gamma dose rate assessment - continuous on-line dose rate data collection and analysis

    International Nuclear Information System (INIS)

    Continuous recording of environmental dose rates around the Nuclear Power Plants (NPPs) and its routine analysis is essential to assess the impact of the operation of these facilities on the public residing in the vicinity of the plants. During the normal operation of a NPP, releases into the atmosphere will be in small quantity. But a major nuclear accident may result in an uncontrolled release through the stack or at ground level causing radiation hazard to the public in the vicinity of the plant. The continuously recorded environmental dose rate data in the Emergency Planning Zone (EPZ) of the NPPs will form a baseline data which will be of great use in assessing the radiological impact during an emergency situation. With this aim, environmental dose rate data around Tarapur site are being collected continuously using various automatic stand alone or manual systems. This paper presents the analysis of the gamma dose rate data collected within the EPZ of Tarapur site during the last six years (1994-1999). The study is carried out using the state of the art systems. The extensive monitoring carried out in and around Tarapur site and the analysis of the data collected shows that radiological impact due to the operation of TAPS and other nuclear facilities at Tarapur on the surrounding environment is insignificant. Assessment of the environmental dose rate in the public domain helps in strengthening the emergency preparedness programme of our NPPs. (author)

  1. Influence of dose rate on leukemogenesis in mice irradiated by gamma rays at a high dose rate or low dose rates

    International Nuclear Information System (INIS)

    The purpose of this study was to assess the extent of the effect of dose rate on tumorigenesis, focusing on myeloid leukemia, one of the typical neoplasias induced by radiation. In the experiment, C3H/He male mice were irradiated with gamma-rays at various doses at a dose rate of 0.88Gy/min, or 0.30mGy/min or 0.016mGy/min, and equations of dose response curves for leukemia were derived from data on the incidence in each group by the least square method. Each equation fitted well with the linear quadratic equation by coefficiency of more than 90%. The extent of the dose rate effect was expressed as dose and dose rate effectiveness factor (DDREF) based on the definition by ICRP-Publication 60. We obtained DDREF by dividing the slope factor of the tangential line of group H (0.88Gy/min) by that of group L-1 (0.30mGy/min) or L-2 (0.016mGy/min), the tangential lines being drawn from the value of the incidence of the control group on the dose response curve. The value of group H to group L-1 was 12.00/1.71=7.022, and that of group H to group L-2 was 12.00/2.56=4.69. These values indicated that reduction of the dose rate caused a decrease in the induction of leukemia, ranging between the values 2 and 10 in the NCRP 1990 report. (author)

  2. Dose-rate, rbe, and oer

    International Nuclear Information System (INIS)

    An analysis of the theories and experimental data dealing with dose-rate effect, relative biological effectiveness (rbe), and oxygen enhancement ratio (oer) for mammalian cells, indicate that neither the theories nor the experimental data themselves are helpful in establishing general rules regarding variations of rbe or oer with dose-rate. There are inconsistencies among the theories which are often at variance with experimental data, which too, are inconsistent among themselves. (orig.)

  3. Chromosome instability and global gene expression patterns in proliferating human T-lymphocytes after low dose rate γ-irradiation, and genetic instability in cells from in vivo radiation-exposed persons

    International Nuclear Information System (INIS)

    Chromosomal instability (Cl), and radiation induced Cl in particular, as well as in a wider sense, genomic instability, has been of great interest lately, as it provides an explanation for the occurrence of multiple mutations during transformation of a normal cell to a malignant tumor cell. To explore this phenomenon, we developed an in vitro system to study the long term, cytogenetic effects of ionizing radiation in human T-lymphocytes. Irradiated or non-irradiated T-cells were grown for up to two months as monoclonal or bulk cell cultures in medium enriched with T-cell growth factors. Analysis of G-banded karyotypes at different time intervals demonstrated clonal aberrations in 65% of the clones derived from irradiated cells, and in only 5% of the clones from non-irradiated cells. Delayed occurrence of de novo aberrations, and a progressive development of subclones with karyotypic abnormalities of increasing complexity, was observed many cell generations after the radiation exposure. Moreover, cells exposed to γ-radiation at a low dose rate (LDR, 0.024 Gy h-1) for 5 days in G0-phase, e.g. a dose that gives the cells time to repair between subsequent hits, also demonstrated CI. Following a radiological accident in Estonia 1994, we studied the possible induction of CI in vivo. Both long term bulk cultures and single cell clones were established from one high and three low exposed persons, as well as control individuals from Estonia. Compared to our historical Swedish controls, we found CI to occur in both bulk cultures and clones, and the aberrations were more complex in the exposed individuals than in the controls, indicating that the aberrations were caused by the irradiation. However, due to the high frequency of CI in the Estonian controls, no conclusion with regard to chromosomal instability in vivo could be drawn from the study. In order to trace factors that induce and maintain the chromosomal instability, and clarify which steps are affected in the

  4. A Phase I/II Trial of Intensity Modulated Radiation (IMRT) Dose Escalation With Concurrent Fixed-dose Rate Gemcitabine (FDR-G) in Patients With Unresectable Pancreatic Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Josef, Edgar, E-mail: edgar.ben-josef@uphs.upenn.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Schipper, Mathew [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Francis, Isaac R. [Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Hadley, Scott; Ten-Haken, Randall; Lawrence, Theodore; Normolle, Daniel [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Simeone, Diane M.; Sonnenday, Christopher [Department of Surgery, University of Michigan, Ann Arbor, Michigan (United States); Abrams, Ross [Department of Radiation Oncology, Rush Medical Center, Chicago, Illinois (United States); Leslie, William [Division of Hematology Oncology, Department of Internal Medicine, Rush Medical Center, Chicago, Illinois (United States); Khan, Gazala; Zalupski, Mark M. [Division of Hematology Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (United States)

    2012-12-01

    Purpose: Local failure in unresectable pancreatic cancer may contribute to death. We hypothesized that intensification of local therapy would improve local control and survival. The objectives were to determine the maximum tolerated radiation dose delivered by intensity modulated radiation with fixed-dose rate gemcitabine (FDR-G), freedom from local progression (FFLP), and overall survival (OS). Methods and Materials: Eligibility included pathologic confirmation of adenocarcinoma, radiographically unresectable, performance status of 0-2, absolute neutrophil count of {>=}1500/mm{sup 3}, platelets {>=}100,000/mm{sup 3}, creatinine <2 mg/dL, bilirubin <3 mg/dL, and alanine aminotransferase/aspartate aminotransferase {<=}2.5 Multiplication-Sign upper limit of normal. FDR-G (1000 mg/m{sup 2}/100 min intravenously) was given on days -22 and -15, 1, 8, 22, and 29. Intensity modulated radiation started on day 1. Dose levels were escalated from 50-60 Gy in 25 fractions. Dose-limiting toxicity was defined as gastrointestinal toxicity grade (G) {>=}3, neutropenic fever, or deterioration in performance status to {>=}3 between day 1 and 126. Dose level was assigned using TITE-CRM (Time-to-Event Continual Reassessment Method) with the target dose-limiting toxicity (DLT) rate set to 0.25. Results: Fifty patients were accrued. DLTs were observed in 11 patients: G3/4 anorexia, nausea, vomiting, and/or dehydration (7); duodenal bleed (3); duodenal perforation (1). The recommended dose is 55 Gy, producing a probability of DLT of 0.24. The 2-year FFLP is 59% (95% confidence interval [CI]: 32-79). Median and 2-year overall survival are 14.8 months (95% CI: 12.6-22.2) and 30% (95% CI 17-45). Twelve patients underwent resection (10 R0, 2 R1) and survived a median of 32 months. Conclusions: High-dose radiation therapy with concurrent FDR-G can be delivered safely. The encouraging efficacy data suggest that outcome may be improved in unresectable patients through intensification of local

  5. A survey of senile dementia in the high background radiation areas in Yangjiang, China

    International Nuclear Information System (INIS)

    Objective: To evaluate the effects of long-term low dose and low dose-rate ionizing radiation exposure on the prevalence rate of senile dementia, further assess the effects of low-dose radiation exposure on central nervous system and study the pathogen of senile dementia, and provide direct observational data of human beings. Methods: A cross-sectional study of the prevalence of senile dementia was carried out in high background radiation areas in Yangjiang, Guangdong Province, China. The survey was conducted in two stages. For the initial screening, Hasegawa Dementia Scale (HDS) was used for all subjects. In the second stage, the stage of diagnosis, special questionnaires of healthy state of old people were sued. The final diagnoses were made according to the third revised edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM III-R) of American Psychiatric Association. Results: 1018 inhabitants aged 65 years and over, including 513 persons in HBRA and 505 in CA were observed. According to DSM III-R, 61 cases (31 cases in HBRA and 30 cases in CA) of senile dementia were diagnosed. The prevalence rates of senile dementia are 6.04% in HBRA and 5.94% in CA, the total prevalence rate being 5.99%. Conclusion: No significant statistical difference in the prevalence rate of senile dementia between the two areas was found, suggesting that the prevalence rate of senile dementia in these areas is not associated with the high background radiation exposure

  6. The Cosmic Background Radiation, Snowmass Workshop

    OpenAIRE

    Smoot, George F.

    1995-01-01

    Observations of the Cosmic Microwave background have provided many of the most powerful constraints we have on cosmology and events in the early universe. The spectrum and isotropy of CBR have long been a pillar of Big Bang models. The discovery of low levels on anisotropy has provided new information and tools for our understanding of the early universe. Further observations promise to enhance greatly our knowledge of processes in the early universe and cosmological parameters. We can antici...

  7. Total ionizing dose effects of domestic SiGe HBTs under different dose rate

    CERN Document Server

    Mo-Han, Liu; Wu-Ying, Ma; Xin, Wang; Qi, Guo; Cheng-Fa, He; Ke, Jiang; Xiao-Long, Li; Ming-Zhu, Xiong

    2015-01-01

    The total ionizing radiation (TID) response of commercial NPN silicon germanium hetero-junction bipolar transistors (SiGe HBTs) produced domestic were investigated under the dose rate of 800mGy(Si)/s and 1.3mGy(Si)/s with Co-60 gamma irradiation source, respectively. The changes of the transistor parameter such as Gummel characteristics, excess base current before and after irradiation are investigated. The results of the experiments shows that for the KT1151, the radiation damage have slightly difference under the different dose rate after the prolonged annealing, shows an time dependent effect(TDE). But for the KT9041, the degradations of low dose rate irradiation are more higher than the high dose rate, demonstrate that there have potential enhanced low dose rate sensitive(ELDRS) effect exist on KT9041. The underlying physical mechanisms of the different dose rates response induced by the gamma ray are detailed discussed.

  8. Cosmic far-ultraviolet background radiation

    International Nuclear Information System (INIS)

    It is demonstrated that interstellar dust grains forward-scatter far-ultraviolet radiation extremely strongly: the value of the Henyey-Greenstein scattering parameter g at 1425 A is shown to be at least 0.75; the actual value is very likely greater than 0.9. Also, observations of the Virgo cluster of galaxies sets a limit tau > 2 x 1025 sec on the life-time of 17-20 eV/c2 heavy neutrinos, if such neutrinos are responsible for the gravitational binding of the cluster. (Auth.)

  9. Radon-thoron exposures in high background radiation areas: a review

    International Nuclear Information System (INIS)

    The radon-thoron measurements reported in literature for the high background radiation areas (HBRAs) of the world are summarised here. The most important areas covered are the Radon Spas and the thorium bearing monazite deposits. Special mention is made of the ongoing programmes of radon-thoron survey in the monazite beach areas of India; preliminary measurements indicate significant levels of thoron exposures. The diurnal and seasonal variations are quite wide underscoring the importance of carrying out integrated measurements for meaningful assessments of population exposures. Radon-thoron inhalation dose rates upto 30 mSv/y have been measured in lran as well as India. It has been generally observed that the cumulative population doses due to radon-thoron inhalation are as high as those due to the external exposures in these HBRAs. (author). 7 refs., 2 tabs., 3 figs

  10. Formation of Primordial Galaxies under UV background Radiation

    CERN Document Server

    Susa, H; Susa, Hajime; Umemura, Masayuki

    2000-01-01

    The pancake collapse of pregalactic clouds under UV background radiation is explored with a one-dimensional sheet model. Here, attention is concentrated on elucidating the basic physics on the thermal evolution of pregalactic clouds exposed to diffuse UV radiation. So, we treat accurately the radiation transfer for the ionizing photons, with solving chemical reactions regarding hydrogen molecules as well as atoms. The self-shielding against UV radiation by H$_2$ Lyman-Werner bands, which regulates the photo-dissociation of hydrogen molecules, is also taken into account. As a result, it is found that when the UV background radiation is at a level of $10^{-22} (\

  11. Measurement of dose rates in granite samples of Bangalore city

    International Nuclear Information System (INIS)

    Naturally occurring radioactive elements arising from the 238U, 232Th, and their short-lived progenies and singly occurring radionuclides like 40K are present in the earth's crust since its formation contribute significantly to the natural background radiation level to the public. House construction materials from the above origin materials can be significant sources of indoor radon in addition to soil and water. As a part of the ongoing measurements to assess the population exposure from these building materials, measurements were initiated around Bangalore. The rocks around the study area are called Closepet granites. The available literature data reveals that the activity concentrations of 226Ra, 232Th and 40K in the soil samples and the radon gas in groundwater samples of the study area found to be higher than the admissible levels. In view of this an attempt has been made to find the dose rate in the granite samples used for building construction in Bangalore city, Karnataka, India

  12. A theoretical and experimental dose rate study at a multipurpose gamma irradiation facility in Ghana

    International Nuclear Information System (INIS)

    Radiation dose rate monitoring out at the Radiation Technology Centre (RTC) of the Ghana Atomic Energy Commission (GAEC) to establish the safety or otherwise of staff at the occupied areas is presented. The facility operates a rectangular source of Co-60 gamma with an having activity of 27.4kCi as at March 2015 and has 14 workers. The aim of the research was determine by means of practical and theoretical evaluations shielding effectiveness of the irradiation chamber. This was to ensure that occupationally exposed workers are not over exposed or their exposures do not exceed the regulatory limits of 7.5μSv/h or 50mSv per annum. The study included dose rate measurements at controlled areas, evaluation of personnel dose history, comparison of experimental and theoretical values and determination of whether the shielding can support a. 18.5PBq (500kCi) Co-60 source. Practical dose rate measurements when the source was in the irradiation position was carried out using a Thermo Scientific Rad-Eye Gamma Survey Meter in the controlled areas of the facility which included the control room, electric room, deionizer room, on top of the roof of irradiation chamber (specifically above the roof plugs) and the two entrances to the irradiation chamber; the personnel door and the goods door. Background reading was found to be 0.08±0.01μSv/h whilst the average dose rates at the two entrances to the irradiation chamber (i e.,- the personnel door and the goods door) were measured to be 0.090μSv/h and 0.109μSv/h respectively. Practical measurements at the roof plugs produced average values of 0.135μSv/h. A particular point on the roof marked as plug-3 produced a relatively higher dose rate of 8.151μSv/h due probably to leakage along the cable to the drive motor. Measurements in the control room, electrical room and deionizer room had average readings of 0.116μSv/h, 0.089μSv/h and 0.614μSv/h respectively. All these average values were below the regulatory limits of 7.5

  13. Variations of dose rate observed by MSL/RAD in transit to Mars

    CERN Document Server

    Guo, Jingnan; Wimmer-Schweingruber, Robert F; Hassler, Donald M; Posner, Arik; Heber, Bernd; Köhler, Jan; Rafkin, Scot; Ehresmann, Bent; Appel, Jan K; Böhm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Brinza, David E; Lohf, Henning; Martin, Cesar; Reitz, Günther

    2015-01-01

    Aims: To predict the cruise radiation environment related to future human missions to Mars, the correlation between solar modulation potential and the dose rate measured by the Radiation Assessment Detector (RAD) has been analyzed and empirical models have been employed to quantify this correlation. Methods: The instrument RAD, onboard Mars Science Laboratory's (MSL) rover Curiosity, measures a broad spectrum of energetic particles along with the radiation dose rate during the 253-day cruise phase as well as on the surface of Mars. With these first ever measurements inside a spacecraft from Earth to Mars, RAD observed the impulsive enhancement of dose rate during solar particle events as well as a gradual evolution of the galactic cosmic ray (GCR) induced radiation dose rate due to the modulation of the primary GCR flux by the solar magnetic field, which correlates with long-term solar activities and heliospheric rotation. Results: We analyzed the dependence of the dose rate measured by RAD on solar modulatio...

  14. Application of accelerated evaluation method of alteration temperature and constant dose rate irradiation on bipolar linear regulator LM317

    International Nuclear Information System (INIS)

    With different irradiation methods including high dose rate irradiation, low dose rate irradiation, alteration temperature and constant dose rate irradiation, and US military standard constant high temperature and constant dose rate irradiation, the ionizing radiation responses of bipolar linear regulator LM317 from three different companies were investigated under the operating and zero biases. The results show that compared with constant high temperature and constant dose rate irradiation method, the alteration temperature and constant dose rate irradiation method can not only very rapidly and accurately evaluate the dose rate effect of three bipolar linear regulators, but also well simulate the damage of low dose rate irradiation. Experiment results make the alteration temperature and constant dose rate irradiation method successfully apply to bipolar linear regulator. (authors)

  15. High dose rate workplace characterisation using passive dosimetric systems

    International Nuclear Information System (INIS)

    Assessment of effective dose of workers requires a knowledge of spectral and angular characteristics of workplace radiation fields. However, when dose rate is high, conventional methods of field characterisation do not work. Therefore, some alternative techniques need to be elaborated. The problem of energy spectrum evaluation in high dose rate fields was addressed by simultaneous application of a set of TLD dosimeters placed in different spherical attenuators. For an assessment of angular distribution of radiation field, an original six-collimator unit was designed. In the problem of deconvolution of the energy spectra, a special attention was paid to solution of ill-conditioned systems of simultaneous equations; this problem was solved by application of regularisation procedures. Both response functions of individual detectors and angle-selective units were simulated by Monte Carlo method. Results of calculations were confirmed by selective benchmark experiments. The proposed techniques were applied at workplaces of Chernobyl Object 'Shelter'. (author)

  16. Importance of dose-rate and cell proliferation in the evaluation of biological experimental results

    Science.gov (United States)

    Curtis, S. B.

    1994-01-01

    The nuclei of cells within the bodies of astronauts traveling on extended missions outside the geomagnetosphere will experience single traversals of particles with high Linear Energy Transfer (LET) (e.g., one iron ion per one hundred years, on average) superimposed on a background of tracks with low LET (approximately one proton every two to three days, and one helium ion per month). In addition, some cell populations within the body will be proliferating, thus possibly providing increasing numbers of cells with 'initiated' targets for subsequent radiation hits. These temporal characteristics are not generally reproduced in laboratory experimental protocols. Implications of the differences in the temporal patterns of radiation delivery between conventionally designed radiation biology experiments and the pattern to be experienced in space are examined and the importance of dose-rate and cell proliferation are pointed out in the context of radiation risk assessment on long mission in space.

  17. Measurements of radon and thoron concentrations in high radiation background area using pin-hole dosimeter

    International Nuclear Information System (INIS)

    In present investigation, newly designed twin cup pin-hole dosimeter with LR-115 track detector has been used for the integrated measurements of radon and thoron in the environmental air of a high background radiation area in coastal Orissa. The twin cup dosimeters were calibrated before installation in the field. The calibration experiment was made in an inter calibration exercise at NIRS, Chiba, Japan. The resulting calibration factors were used to obtain the values of radon and thoron in the study area. Radon and thoron concentrations in the houses of study area were found to vary from 24 Bq/m3 to 98 Bq/m3 and 46 Bq/m3 to 689 Bq/m3, respectively. The indoor and outdoor gamma dose rates in the study area vary from 0.124 μGy/h to 0.257 μGy/h and 0.109 μGy/h to 0.361 μGy/h, respectively. The annual effective dose due to the exposure to indoor radon and progeny was found to vary from 0.70 mSv to 2.84 mSv with an average value of 1.73 mSv. However, the annual effective dose due to the exposure to thoron and progeny was found to vary from 1.16 mSv to 17.36 mSv with an average value of 7.36 mSv. Thoron concentration and gamma dose rate were found relatively higher in the area. - Highlights: • Results of a newly designed twin cup pin-hole dosimeter are reported in this paper. • Radon and thoron were measured in high background radiation area of India. • Concentration of thoron and resulting effective dose were found higher in the area. • The indoor and outdoor gamma dose rates were also relatively higher in the area. • The resulting dose to the people living in the area was estimated

  18. Epidemiological investigation of radiological effects in high background radiation areas of Yangjiang, China

    International Nuclear Information System (INIS)

    The purpose of this investigation is to provide some information for providing whether any detrimental effects exist in a large population whose families have been continuously exposed to a low dose rate radiation. Two areas in Yangjiang Country, characterized by high background radiation (HBR) with environmental gamma exposure, large population size and long-term inhabitants, were selected for evaluation of late effects of HBR. The areas with normal radiation background close to the Yangjiang Country were selected as control areas. Up to 1986 approximately one million person-years in each area in both HBR and control areas have been observed. No increase of cancer mortality was found in the HBR areas; on the contrary, cancer mortality tended to be lower in the HBR areas than the control areas. The prevalence of hereditary diseases and congenital defects was similar in both HBR and control areas, but the frequency of Down's syndrome was higher in the HBR areas (through within the normal range) than the control areas. A possible explanation is the difference of age of maternity between the HBR and control areas, and the extremely low frequency in the control areas. Possible factors influencing the incidence of mutationbased diseases were comparable in the HBR and control groups. However, the cultural and educational levels were somewhat different, probably affecting health status and family planning. It is likely that there may be a dose threshold for cancer incidence, but this remains to be determined by further research. (N.K.)

  19. Diamond gamma dose rate monitor; Debitmetre gamma en diamant

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, A.; Chambaud, P.; Tromson, D.; Bergonzo, P.; Foulon, F.; Joffre, F. [CEA Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire, LETI, 91 - Gif-sur-Yvette (France)

    1999-07-01

    CVD (chemical vapor deposition) diamond detectors for X and gamma dose rate monitoring have been fabricated and tested in the 1 mGy/h to 1 kGy/h range. They show excellent performances in terms of sensitivity and linearity. Radiation hardness measurement under 60-Co gamma rays have demonstrated long term stability for integrated doses up to 500 kGy. (authors)

  20. Variation of OER with dose rate

    International Nuclear Information System (INIS)

    The OER has been measured from 276 Gy/hr to 0.89 Gy/hr for V-79 cells irradiated at 230 or 370C. As dose rate is decreased, the OER initially increased from 3.1 to a maximum of 4.0. Then, the OER decreases to a minimum of 2.4 at lower dose rates. Experiments with cells in nutrient poor conditions (HBSS without glucose) show a monotonic decrease in OER from 3.1 to 1.7. These findings are due to the differences in SLD repair capability and kinetics of cells under different pO/sub 2/ and nutrient conditions

  1. Solar modulation of dose rate onboard the Mir station.

    Science.gov (United States)

    Badhwar, G D; Shurshakov, V A; Tsetlin, V V

    1997-12-01

    Models of the radiation belts that are currently used to estimate exposure for astronauts describe the environment at times of either solar minimum or solar maximum. Static models, constructed using data acquired prior to 1970 during a solar cycle with relatively low solar radio flux, have flux uncertainties of a factor of two to live and dose-rate uncertainties of a factor of about two. The inability of these static models to provide a dynamic description of the radiation belt environment limits our ability to predict radiation exposures for long-duration missions in low earth orbits. In an attempt to add some predictive capability of these models, we studied the measured daily absorbed dose rate on the Mir orbital station over roughly the complete 22nd solar cycle that saw some of the highest solar flux values in the last 40 y. We show that the daily trapped particle dose rate is an approximate power law function of daily atmospheric density. Atmospheric density values are in turn obtained from standard correlation with observed solar radio noise flux. This correlation improves, particularly during periods of high solar activity, if the density at roughly 400 days earlier time is used. This study suggests the possibility of a dose- and flux-predictive trapped-belt model based on atmospheric density. PMID:11542263

  2. Mapping the outdoor gamma dose rate in Indonesia

    International Nuclear Information System (INIS)

    Full text: Indonesia is the largest archipelago in the world, comprising five main islands - Java, Sumatra, Sulawesi, Kalimantan and Papua - as well as 30 archipelagoes totaling 17,508 islands with about 6000 of those inhabited. Mapping the outdoor gamma dose rate in Indonesia is a research project conducted by National Nuclear Energy Agency since 2005 aiming to produce a baseline data map as an overview for planning purposes. In these three years 4 main islands has been measured. The grid system has been used in the research. In Sumatra Island the grid is 50 x 50 km2, while in Java 40 x 40 km2, in Kalimantan 60 x 60 km2, and in Sulawesi 40 x 40 km2. The gamma dose rates have been measured by Mini Gamma Ray Spectrometer Model GR-130 made by Exploranium-Canada. Figure 1 shows the map of outdoor gamma dose rate in Indonesia. Range of dose rate are in Sumatra from 22,96 ± 0,46 n Sv/h to 186,08 ± 3,72 n Sv/h, in Java 11,32 ± 0,72 n Sv/h to 127,54 ± 6,14 n Sv/h, in Kalimantan 10.72 ± 8.32 n Sv/h to 349,48 ± 57,21 n Sv/h, and in Sulawesi 17.7 ± 11,5 n Sv/h to 467 ± 102 n Sv/h. The arithmetic and geometric mean of dose rate in Indonesia are 68 n Sv/h and 53 n Sv/h, respectively. In general, outdoor gamma dose rate in Indonesia is in a normal range. There are some regions have anomaly of gamma dose rate, for examples at North Sumatra 186.08 ± 3,72 n Sv/h (N 2.12727, E 99.80909), at West Kalimantan 349,48 ± 57,21 n Sv/h (S 1.39507, E 110.57584), at West Sulawesi 487 ± 103 n Sv/h (S 2.95781, E 118.86995), etc. These data is very useful as a radiation baseline in Indonesia. (author)

  3. Pulsed low dose rate brachytherapy for pelvic malignancies

    International Nuclear Information System (INIS)

    Purpose: The pulsed low dose rate remote afterloading unit was designed to combine the radiation safety and isodose optimization advantages of high dose rate technology with the radiobiologic advantages of continuous low dose rate brachytherapy. This is the first report of a prospective clinical trial evaluating the relative incidence of acute toxicity and local control in patients with pelvic malignancies who underwent interstitial or intracavitary brachytherapy with the pulsed low dose rate remote afterloader. Methods and Materials: From 5/11/92-6/21/95, 65 patients underwent 77 brachytherapy procedures as part of their treatment regimen for pelvic malignancies. Using the pulsed low dose rate Selectron, equipped with a single cable-driven 0.3-1.0 Ci Ir192 source, target volume doses of 0.40-0.85 Gy per pulse were prescribed to deliver the clinically determined dose. Forty-five intracavitary and 32 interstitial procedures were performed. Fifty-four patients had primary and 11 recurrent disease. Patients were followed closely to assess incidence of Grade 3-5 acute and delayed toxicity, local control, and survival. Results: With a median follow-up of 16.1 months (range 1-29), 33 patients are NED, 10 alive with disease, 13 dead with disease, 4 dead of intercurrent disease, and 5 lost to follow-up. Local control was maintained until last follow-up or death in 48 cases, local failure occurred in 11, unknown in 5. Grade 3-5 acute toxicities (requiring medical or surgical intervention) occurred in 5 out of 77 procedures (6.5%), delayed complications in 10 patients (15% actuarial incidence at 2 years). In the 52 procedures performed for 42 patients with cervix cancer, the acute toxicity incidence was 5.8%, with a 14% 2-year actuarial incidence of delayed complications. Of 32 interstitial templates performed on 30 patients for pelvic malignancies, there were three incidences of acute toxicity and five delayed toxicities. Conclusion: Using the parameters described for this

  4. Cervical Gross Tumor Volume Dose Predicts Local Control Using Magnetic Resonance Imaging/Diffusion-Weighted Imaging—Guided High-Dose-Rate and Positron Emission Tomography/Computed Tomography—Guided Intensity Modulated Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and 18F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials: We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodes by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results: One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions: Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control

  5. Cervical Gross Tumor Volume Dose Predicts Local Control Using Magnetic Resonance Imaging/Diffusion-Weighted Imaging—Guided High-Dose-Rate and Positron Emission Tomography/Computed Tomography—Guided Intensity Modulated Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Dyk, Pawel; Jiang, Naomi; Sun, Baozhou; DeWees, Todd A. [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Fowler, Kathryn J.; Narra, Vamsi [Department of Diagnostic Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Garcia-Ramirez, Jose L.; Schwarz, Julie K. [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Grigsby, Perry W., E-mail: pgrigsby@wustl.edu [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Division of Nuclear Medicine, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Division of Gynecologic Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Alvin J. Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri (United States)

    2014-11-15

    Purpose: Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and {sup 18}F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials: We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodes by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results: One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions: Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control.

  6. Influence of the dose rate in the PVDF degradation processes

    International Nuclear Information System (INIS)

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm-1 which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm-1 which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm-1 which were associated with NH stretch of NH2 and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  7. Influence of the dose rate in the PVDF degradation processes

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  8. THE BACKGROUND RADIATION AND EXPOSURE LEVELS AT VARIOUS SOUTH AFRICAN WEST COAST MILITARY UNITS

    Directory of Open Access Journals (Sweden)

    Jacques Bezuidenhout

    2014-11-01

    Full Text Available The West Coast of South Africa between St Helena Bay to the north and Langebaan Lagoon to the south is characterised by numerous granite protrusions. These outcrops are elements of the underlying Cape Granite Suite, which forms the bedrock of a large part of the Western Cape. Granite contains high levels of natural radionuclides, which results in high levels of natural background radiation in the surrounding area. The impacts of these high levels of radiation exposure on military personal are of concern. There are four military units located in this part of the West Coast, namely SAS Saldanha, 4 Special Forces Regiment, Langebaan Road Air Force Base and the Military Academy. Different sites in and around these military units were selected and soil samples were taken. Laboratory gamma ray measurements were done to determine the levels of natural radioactive nuclides in the soil samples. The radioactive nuclide concentrations were interpolated and then mapped with the help of geographic information systems (also known as geospatial information systems or GIS software. An evaluation of the annual dose rate of military personnel at the units on the West Coast was made and found to range between 0,017 mSv/y and 0,163 mSv/y. These values were mapped and compared to the average global annual dose rate of 0,070 mSv/y. This article reports on an investigation of these results and the overall exposure levels of personnel from the various military units on the West Coast of South Africa.

  9. Relationship of HepG2 cell sensitivity to continuous low dose-rate irradiation with ATM phosphorylation

    Institute of Scientific and Technical Information of China (English)

    Quelin Mei; Jianyong Yang; Duanming Du; Zaizhong Cheng; Pengcheng liu

    2008-01-01

    Objective: To investigate the change of ATM phosphorylation in HepG2 cells and its effect on HepG2 cell survival under a continuous low dose-rate irradiation.Methods: HepG2 cells were exposed to equivalent doses of irradiation delivered at either a continuous low dose-rate (7.76 cGy/h) or a high dose-rate (4500 cGy/h).The ATM phosphorylated proteins and surviving fraction of HepG2 cell after low dose-rate irradiation were compared with that after equivalent doses of high dose-rate irradiation.Results: The phosphorylation of ATM protein was maximal at 0.5 Gy irradiation delivered at either a high dose-rate or a continuous low dose-rate.As the radiation dose increased, the phosphorylation of ATM protein decreased under continuous low dose-rate irradiation.However, the phosphorylation of ATM protein was remained stable under high dose-rate irradiation.When the phosphorylation of ATM protein under continuous low dose-rate irradiation was equal to that under high dose-rate irradiation, there was no significant difference in the surviving fraction of HepG2 cells between two ir-radiation methods (P>0.05).When the phosphorylation of ATM protein significantly decreased after continuous low dose-rate irradiation compared with that after high dose-rate irradiation, increased amounts of cell killing was found in low dose-rate irradiation (P<0.01).Conclusion: Continuous low dose-rate irradiation increases HepG2 cells radiosensitivity compared with high dose-rate irradiation.The increased amounts of cell killing following continuous low dose-rate exposures are associated with reduced ATM phosphorylated protein.

  10. Endophytic fungi of the Genus Penicillium isolated of Platypodium elegans from environments of high dose rate of ionizing radiation; Fungos endofiticos do genero Penicillium isolados de Platypodium elegans provenientes de locais de alta taxa de radiacao

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Victor da

    1999-07-01

    The present work had as objective to isolate and to identify endophytic microorganisms and were exposed to stress situations, using for this ionizing radiations, these highly mutagen and in high doses, lethal to all the alive organisms. The endophytic microorganisms were obtained the starting from the species arboreal Platypodium elegans Vog., one of them developed in radioactive land in the area of Ipora/Go and other, developed in land Background in the city of Abadia de Goias/GO. The rates of dose of environmental radiation were shown sharply different, being in Ipora (Anomaly 2) with a value of approximately 140 {mu}R/h and in Abadia de Goias with approximately 20 {mu}R/H, both measured the area of root of the tree close to. Tests through PCR-RAPD were accomplished with the isolated ones, for verification of the similarity of its genetic characteristics and possible polymorphism among its DNA's . The isolated ones were studied with relationship to the effects of the gamma radiation, being used as source {sup 60} Co, with doses of 25 to 2131 Gy. These lineages had the same behavior practically with relationship to the resistance of the gamma radiation, declining strongly at levels of approximately 700 Gy. The isolated ones tested were identified at microscope for morphology, being of the Genus Penicillium, with the same genetic characteristics in agreement with PCR/RAPD, being just observed a polymorphism area in its DNA's. In spite of a lineage to have been isolated of a tree developed in radioactive land, any difference was observed among its resistance to the gamma radiation in comparison to the isolated lineage of tree developed in land radiometric background. (author)

  11. Activity concentrations and dose rates from decorative granite countertops

    Energy Technology Data Exchange (ETDEWEB)

    Llope, W.J., E-mail: llope@rice.edu [Rice University, 6100 S. Main St. - MS-315, Houston, TX 77005 (United States)

    2011-06-15

    The gamma radiation emitted from a variety of commercial decorative granites available for use in U.S. homes has been measured with portable survey meters as well as an NaI(Th) gamma spectrometer. The {sup 40}K, U-nat, and {sup 232}Th activity concentrations were determined using a full-spectrum analysis. The dose rates that would result from two different arrangements of decorative granite slabs as countertops were explored in simulations involving an adult anthropomorphic phantom. - Highlights: > Gamma rates, spectra, and activity concentrations from decorative granites used as countertops in U.S. homes. > Activity concentrations in Bq/kg for {sup 40}K, U-nat, and {sup 232}Th. > Dose rates for each calculated using an anthropomorphic phantom; typical countertop geometries.

  12. Stopping the greenhouse effect - recommendations submitted by the Bundestag Enquete Commission. - Why nuclear energy cannot solve the global-warming problem - on the urgency of a low-risk, efficient future energy economy. - The latest cancer statistics of the Hiroshima/Nagasaki A-bomb survivors - a higher radiation risk at dose rates below 50cGy (rad) - consequences for radiation protection

    International Nuclear Information System (INIS)

    The report compiles three contributions two of which discuss the issues of global warming, trace gases and ozone depletion. The measures proposed by a German enquete commision to stop the greenhouse effect, i.e. utilization of renewable energy sources, nuclear phaseout because nuclear power is not supposed to solve the global-warming problem, are described. The third contribution gives the latest cancer statistics of the Hiroshima/Nagasaki a-bomb survivors while taking into account the higher radiation risk due to low dose rates. (DG)

  13. Development and characterization of a novel variable low-dose rate irradiator for in vivo mouse studies

    OpenAIRE

    Olipitz, Werner; Hembrador, Sheena; Davidson, Matthew; Yanch, Jacquelyn C; Engelward, Bevin P.

    2010-01-01

    Radiation exposure of humans generally results in low doses delivered at low dose-rate. Our limited knowledge of the biological effects of low dose radiation is mainly based on data from the atomic bomb long-term survivor study (LSS) cohort. However, the total doses and dose-rates in the LSS cohort are still higher than most environmental and occupational exposures in humans. Importantly, the dose-rate is a critical determinant of health risks stemming from radiation exposure. Understanding t...

  14. Radiation background with the CMS RPCs at the LHC

    International Nuclear Information System (INIS)

    The Resistive Plate Chambers (RPCs) are employed in the CMS Experiment at the LHC as dedicated trigger system both in the barrel and in the endcap. This article presents results of the radiation background measurements performed with the 2011 and 2012 proton-proton collision data collected by CMS. Emphasis is given to the measurements of the background distribution inside the RPCs. The expected background rates during the future running of the LHC are estimated both from extrapolated measurements and from simulation

  15. Inverse dose rate effect in tumour cells measured by the comet assay

    International Nuclear Information System (INIS)

    Reduction of the dose rate of low LET radiation from high (Gy/min) to low (Gy/h) usually leads to a reduced effect as measured by the survival methods. If the dose rate is reduced, cells are able to repair sublethal damage even during irradiation. During the last few years a comet assay has been widely used to measure DNA damage induction and repair in single cells. In our study we used the alkaline version of the comet assay for comparison of high (0.833 Gy/min) and low dose rate (0.0707 Gy/min) effects on DNA damage and repair in R1 rat rhabdomyosarcoma and Me45 human malignant melanoma cells. Cells gathered from exponential culture by trypsynization were suspended in a growth medium and irradiated at room temperature, with 5 Gy of photons X generated by linear accelerator at both dose rates. Comets were analysed automatically using self-made software for measurement of percentage DNA in the tail, and tail moment and inertia. Our results show that tail inertia is the best parameter expressing DNA damage and repair. Although the level of DNA damage induced by low dose rate was comparable with that induced by a high dose rate, the damage induced by the low dose rate are repair more slowly than after high dose rate irradiation. This inverse dose rate effect suggest that nature of damage can differ in both groups. (author)

  16. Quality Assurance of Dose rate Measurements in Fields of Natural Radioactivity

    International Nuclear Information System (INIS)

    Full text: By order of the German environmental ministry the Bundesanstalt fuer Strahlenschutz (BfS) is responsible for the quality assurance of measuring programmes performed in former uranium mining areas of East Germany. The properties of the very complex fields of terrestrial and cosmic radiation are not sufficiently considered at the calibration of environmental dose rate meters by national standard laboratories. Therefore, BfS organises annually a countrywide intercomparison of field instruments of local authorities, institutions and firms on reference measuring sites in a former uranium mine environment in Thuringia. There three areas of natural and enhanced activity were prepared. Nuclide spectra and spatial dose rate distributions are well known. Reference instruments are ionisation chambers of different filling pressure and proportional counters carefully calibrated with photon sources over a broad energy and angle range. By measurements in the Physikalisch-Technische Bundesanstalt (PTB) underground laboratory in a former salt mine in 925 m depth the internal background of probes was determined. The response for cosmic radiation was measured on a deep clear lake where the terrestrial radiation is shielded by the water. About 30 institutions participated in the last years with about 90 instruments annually. Whereas considerable and partially type specific deviations were observed at the first intercomparisons now a good level of agreement was obtained. (author)

  17. Natural background as an indicator of radiation-induced cancer

    International Nuclear Information System (INIS)

    A review of the estimates for radiation-induced cancer rates is presented including the recent high estimates of 8 x 10-3 cancers/man rem. Also reviewed are the external background radiation and cancer incidence for the USA by state. A regression analysis of these data reveals a negative correlation between radiation dose and cancer rate, but only with a correlation coefficient of 0.39. However, the cancer induction rate of 8 x 10-3/man rem is shown to describe the observed data with a probability of 1 in 14,000. Thus such high estimates of radiation-induced cancer rate are highly improbable. (UK)

  18. Natural background radiation and population dose in China

    Energy Technology Data Exchange (ETDEWEB)

    Guangzhi, C. (Ministry of Public Health, Beijing, BJ (China)); Ziqiang, P.; Zhenyum, H.; Yin, Y.; Mingqiang, G.

    On the basis of analyzing the data for the natural background radiation level in China, the typical values for indoor and outdoor terrestrial gamma radiation and effective dose equivalents from radon and thoron daughters are recommended. The annual effective dose equivalent from natural radiation to the inhabitant is estimated to be 2.3 mSv, in which 0.54 mSv is from terrestrial gamma radiation and about 0,8 mSv is from radon and its short-lived daughters. 55 Refs.

  19. The OER at low dose-rates

    International Nuclear Information System (INIS)

    The author comments on a letter (Kal, H.B., and Barendsen, G.W., 1976, Br. J. Radiol., vol. 49, 1049) reviewing published values of the OER for low dose-rate γ-rays. Artefacts of the system may have been responsible for one very low OER value taken from work carried out in the early 1960s, but later work in which these problems were eliminated still yielded OER values significantly lower than for acute X- or γ-ray exposures. Consideration is given to significance of this reduction in OER for γ-rays at the low dose-rates characteristic of interstitial implants. The performance of these interstitial implants may be comparable with the most sophisticated and expensive pion or heavy ion treatments. (U.K.)

  20. Shutdown dose rate studies for TFCX

    International Nuclear Information System (INIS)

    As part of the GA-funded TFCX proposal effort, a method was developed and implemented to make fast, repetitive calculations of fusion reactor shutdown dose rates for several operating and shutdown times. The ONEDANT discrete ordinates code is used as the transport code in this procedure. Examples of parametric study results using this method are given. The method is currently being used in tokamak ignition studies at GA

  1. Estimates of dose equivalent rates from natural background radiation

    International Nuclear Information System (INIS)

    Environmental monitoring in Khartoum is being conducted using thermoluminescent dosimetry.The purpose of the study is to estimate dose-equivalent rates from natural background radiation.TL phosphorus LiF.Mg, Cu, P and CaSO4:Mn were used to measure the exposure over land for natural background radiation of terrestrial origin plus cosmic radiation and at position over the Blue Nile to account for natural background radiation of extraterrestrial origin (cosmic rays).The associated dose-equivalent rates have been determined.It was found that the dose-equivalent rates from cosmic radiation obtained through this work using the two types of the TLD phosphorus GR-200 A and CaSO4 are 0.295 mSv per year and 0.265 mSv per year, respectively.While the dose-equivalent rates from total natural background radiation obtained through this work are 0.395 mSv per year using GR-200 A and CaSO4 phosphorus, respectively. (Author)

  2. Spectrum and isotropy of the submillimeter background radiation

    International Nuclear Information System (INIS)

    Two great astronomical discoveries have most shaped our present concept of the Big Bang universe. Like the Hubble recession of the galaxies, the discovery of the 30K background radiation by Penzias and Wilson in 1965 has given rise to a line of research which is still very active today. Penzias and Wilson's universal microwave background at 7 cm was immediately interpreted by R.H. Dicke's group at Princeton as coming from the primordial fireball of incandescent plasma which filled the universe for the million years or so after its explosive birth. This interpretation gives rise to two crucial predictions as to the nature of the background radiation. Its spectrum should be thermal even after having been red shifted by a factor of approximately 1000 by the expansion of the universe, and the radiation should be isotropic - assuming that the universe itself is isotropic. If the background radiation is indeed from the primordial fireball it affords us the only direct view at the very young universe. This paper deals with the spectrum and then the isotropy of the background radiation, with emphasis on high frequency or submillimeter measurements. Prospects for the future are discussed briefly. (Auth.)

  3. Evaluation of quality characteristics and functional properties of mechanically deboned chicken meats treated with different dose rates of ionizing radiation and use of antioxidants; Avaliacao de caracteristicas de qualidade e propriedades funcionais da carne mecanicamente separada de frango tratada com diferentes taxas de dose de radiacao ionizante e uso de antioxidantes

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Poliana de Paula

    2012-07-01

    The Mechanically Deboned chicken meat (MDCM) is used in traditional meat products, in greater proportion in those emulsified, replacing meat raw materials more expensive. The raw material can have high MDCM the microbial load, as a result of contamination during processing or failure during the evisceration. The irradiation process is accepted as one of the most effective technologies when compared to conventional techniques of preservation, to reduce contamination of pathogens and spoilage. However, little information is available about the use and effects of different dose rates of ionizing radiation processing. Irradiation causes chemical changes in food, a major cause of deterioration of quality of raw or cooked meat products during refrigerated storage, frozen. The objective of this study was to evaluate the effects of different dose rates of ionizing radiation on the production of Thiobarbituric Acid Reactive Substances (TBARS), color, microbiological and sensory characteristics of mechanically deboned chicken added or without added antioxidants, during the cold storage and evaluation of functional properties. The results showed that among the tested dose rates using cobalt-60 source, dose rate of 4.04 kGy.h-1 was the best for processing MDCM. Furthermore, the use of the combination of rosemary antioxidant and α-tocopherol were able to reduce lipid oxidation generated by irradiation of the samples, showed a synergistic effect to the processing with ionizing radiation in reduction of psychrotrophic bacteria count and contributed to a better sensory quality. The use of radiation in the processing FDMI did not adversely affect the functional properties studied. (author)

  4. Evaluation of late morbidity in patients with carcinoma of the uterine cervix following a dose rate change

    International Nuclear Information System (INIS)

    Background: A retrospective analysis of late complications for patients with cervical cancer treated with two different brachytherapy schedules in one institute, using the French-Italian glossary. Materials and methods: From 1979 until 1986, a total of 77 patients were treated with external radiation followed by two intracavitary applications with the Gynatron Cs-137 afterloading (dose rate 0. 54 Gy/h). After 1986, 66 patients received intracavitary applications with Selectron-LDR (dose rate 1.07 Gy/h). Because of the expected increase in complications with increasing dose rate, the dose per application was reduced from 25 Gy to 20 Gy. Results: 49/77 late gastrointestinal and urinary complications were scored in the Gynatron group and 46/68 in the Selectron group. Actuarial estimates at 5 years showed 42% and 54.1% late gastrointestinal complications and 16.9% and 24.1% for late urinary complications in the patients treated with, respectively, the Gynatron and Selectron. Conclusions: Despite the dose reduction, there remains a clear dose rate influence on the late morbidity. Correction for this influence is essential

  5. EPR dosimetry of radiation background in the Urals region

    Energy Technology Data Exchange (ETDEWEB)

    Shishkina, E.A.; Degteva, M.O.; Shved, V.A. [Urals Research Center for Radiation Medicine, 48-A Vorovsky, Chelyabinsk 454076 (Russian Federation); Fattibene, P.; Onori, S. [Istituto Superiore di Sanita and Istituto Nazionale di Fisica Nucleare (Italy); Wieser, A. [GSF, Forschungszentrum fuer Umwelt und Gesundheit, Ingolstaedter Landstr (Germany); Ivanov, D.V.; Bayankin, S.N. [Institute of Metal Physics, Russian Academy of Sciences (Russian Federation); Knyazev, V.A.; Vasilenko, E.I.; Gorelov, M. [ZAO, Closed Corporation ' Company GEOSPETSECOLOGIA' (Russian Federation)

    2006-07-01

    Method of Electron Paramagnetic Resonance is extensively applied to individual retrospective dosimetry. The background dose is unavoidable component of cumulative absorbed dose in the tooth enamel accumulated during the lifetime of donor. Estimation of incidental radiation dose using tooth enamel needs in extraction of background dose. Moreover, the variation of background doses in the population is a limited factor for reliable detection of additional irradiation especially for low dose level. Therefore the accurate knowledge of the natural background radiation dose is a critical element of EPR studies of exposed populations. In the Urals region the method applies for such two large cohorts as the workers of Mayak (Ozersk citizens) and Techa River riverside inhabitants (rural population). Current study aimed to investigate the Urals radiation background detected by EPR spectrometry. For this aim two group of unexposed Urals residents were separated, viz: citizens of Ozersk and rural inhabitants of Chelyabinsk region. Comparison of two investigated territories has demonstrated that from the point of view of radiation background it is impossible to assume the Urals population as uniform. The reliable difference between the urban and rural residents has been found. The average background doses of Ozersk donors is in average 50 mGy higher than those detected for rural residents. The individual variability of background doses for Osersk has been higher than in the rural results. The difference in background dose levels between two population results in different limits of accidental dose detection and individualization. The doses for 'Mayak' workers (Ozyorsk citizens) can be classed as anthropogenic if the EPR measurements exceed 120 mGy for teeth younger than 40 years, and 240 mGy for teeth older than 70 years. The anthropogenic doses for Techa River residents (rural population) would be higher than 95 mGy for teeth younger than 50 years and 270 mGy for

  6. EPR dosimetry of radiation background in the Urals region

    International Nuclear Information System (INIS)

    Method of Electron Paramagnetic Resonance is extensively applied to individual retrospective dosimetry. The background dose is unavoidable component of cumulative absorbed dose in the tooth enamel accumulated during the lifetime of donor. Estimation of incidental radiation dose using tooth enamel needs in extraction of background dose. Moreover, the variation of background doses in the population is a limited factor for reliable detection of additional irradiation especially for low dose level. Therefore the accurate knowledge of the natural background radiation dose is a critical element of EPR studies of exposed populations. In the Urals region the method applies for such two large cohorts as the workers of Mayak (Ozersk citizens) and Techa River riverside inhabitants (rural population). Current study aimed to investigate the Urals radiation background detected by EPR spectrometry. For this aim two group of unexposed Urals residents were separated, viz: citizens of Ozersk and rural inhabitants of Chelyabinsk region. Comparison of two investigated territories has demonstrated that from the point of view of radiation background it is impossible to assume the Urals population as uniform. The reliable difference between the urban and rural residents has been found. The average background doses of Ozersk donors is in average 50 mGy higher than those detected for rural residents. The individual variability of background doses for Osersk has been higher than in the rural results. The difference in background dose levels between two population results in different limits of accidental dose detection and individualization. The doses for 'Mayak' workers (Ozyorsk citizens) can be classed as anthropogenic if the EPR measurements exceed 120 mGy for teeth younger than 40 years, and 240 mGy for teeth older than 70 years. The anthropogenic doses for Techa River residents (rural population) would be higher than 95 mGy for teeth younger than 50 years and 270 mGy for teeth older

  7. Natural background radiation and population dose distribution in India

    International Nuclear Information System (INIS)

    A country-wide survey of the outdoor natural background gamma radiation levels has been made using mailed thermoluminescent dosimeters (TLDs). The salient features of the results are: (1) The air-kerma levels and the population doses in various states follow log-normal and normal distributions respectively. (2) The national average value for the air dose (air-kerma) is 775 ± 370 (1σ)μGy/y. (3) The lowest air-kerma recorded is 0.23 mGy/y at Minicoy (Laccadive Islands) and the highest is 26.73 mGy/y at Chavra (monazite areas, Kerala). (4) There are significant temporal variation s (even as high as ± 40 per cent) of the background radiation level at many locations and at least in 10 locations where radon/thoron measurements are available, these could be associated with the seasonal variations in radon/thoron levels. (5) The mail control TLDs indicate a country-wide average value of 785 ± 225 μGy/y for the air-kerma which can be considered to provide a truly national average value for the natural background radiation level in India. (6) The mean natural radiation per caput for the country works out to be 690 ± 200 (1σ) Sv/y. (7) The natural radiation per caput seems to be maximum for Andhra Pradesh (1065 ± 325 μSv/y) and minimum for Maharashtra (370 ± 80 μSv/y). (8) The population dose from the external natural background radiation is estimated to be half a million person-Sievert. (9) Assuming 1 CRP risk factor, it can be estimated that just one out of the 43 cancer deaths occurring on an average per 100,000 population in India, can be attributed to the external natural background radiation. (author). 18 refs., 13 tabs., 9 figs

  8. Comparison in vivo Study of Genotoxic Action of High- Versus Very Low Dose-Rate γ-Irradiation

    OpenAIRE

    A. N. Osipov; Klokov, D. Y.; Elakov, A. L.; Rozanova, O M; Zaichkina, S. I.; Aptikaeva, G. F.; Akhmadieva, A. Kh.

    2004-01-01

    The aim of the present study was to compare genotoxicity induced by high- versus very low dose-rate exposure of mice to γ-radiation within a dose range of 5 to 61 cGy using the single-cell gel electrophoresis (comet) assay and the micronucleus test. CBA/lac male mice were irradiated at a dose rate of 28.2 Gy/h (high dose rate) or 0.07 mGy/h (very low dose rate). The comet assay study on spleen lymphocytes showed that very low dose-rate irradiation resulted in a statistically significant incre...

  9. Determination of dose rates from natural radionuclides in dental materials

    Energy Technology Data Exchange (ETDEWEB)

    Veronese, I. [Dipartimento di Fisica, Universita degli Studi di Milano, Milan (Italy) and INFN, Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milan (Italy)]. E-mail: ivan.veronese@unimi.it; Guzzi, G. [AIRMEB - Italian Association for Metal and Biocompatibility Research, Milan (Italy); Giussani, A. [Dipartimento di Fisica, Universita degli Studi di Milano, Milan (Italy); INFN, Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milan (Italy); Cantone, M.C. [Dipartimento di Fisica, Universita degli Studi di Milano, Milan (Italy); INFN, Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milan (Italy); Ripamonti, D. [Dipartimento di Fisica, Universita degli Studi di Milano, Milan (Italy)

    2006-07-01

    Different types of materials used for dental prosthetics restoration, including feldspathic ceramics, glass ceramics, zirconia-based ceramics, alumina-based ceramics, and resin-based materials, were investigated with regard to content of natural radionuclides by means of thermoluminescence beta dosimetry and gamma spectrometry. The gross beta dose rate from feldspathic and glass ceramics was about ten times higher than the background measurement, whereas resin-based materials generated negligible beta dose rate, similarly to natural tooth samples. The specific activity of uranium and thorium was significantly below the levels found in the period when addition of uranium to dental porcelain materials was still permitted. The high-beta dose levels observed in feldspathic porcelains and glass ceramics are thus mainly ascribable to {sup 4}K, naturally present in these specimens. Although the measured values are below the recommended limits, results indicate that patients with prostheses are subject to higher dose levels than other members of the population. Alumina- and zirconia-based ceramics might be a promising alternative, as they have generally lower beta dose rates than the conventional porcelain materials. However, the dosimetry results, which imply the presence of inhomogeneously distributed clusters of radionuclides in the sample matrix, and the still unsuitable structural properties call for further optimization of these materials.

  10. Determination of dose rates from natural radionuclides in dental materials

    International Nuclear Information System (INIS)

    Different types of materials used for dental prosthetics restoration, including feldspathic ceramics, glass ceramics, zirconia-based ceramics, alumina-based ceramics, and resin-based materials, were investigated with regard to content of natural radionuclides by means of thermoluminescence beta dosimetry and gamma spectrometry. The gross beta dose rate from feldspathic and glass ceramics was about ten times higher than the background measurement, whereas resin-based materials generated negligible beta dose rate, similarly to natural tooth samples. The specific activity of uranium and thorium was significantly below the levels found in the period when addition of uranium to dental porcelain materials was still permitted. The high-beta dose levels observed in feldspathic porcelains and glass ceramics are thus mainly ascribable to 4K, naturally present in these specimens. Although the measured values are below the recommended limits, results indicate that patients with prostheses are subject to higher dose levels than other members of the population. Alumina- and zirconia-based ceramics might be a promising alternative, as they have generally lower beta dose rates than the conventional porcelain materials. However, the dosimetry results, which imply the presence of inhomogeneously distributed clusters of radionuclides in the sample matrix, and the still unsuitable structural properties call for further optimization of these materials

  11. An intercomparison of detectors for measurement of background radiation

    International Nuclear Information System (INIS)

    Measurements of the background radiation were made in 1978 at 14 locations with a high-pressure ionization chamber, thermoluminiscence dosimeters (TLD's), two NaI(Tl) detectors, and a Ge(Li) spectrometer system. Simultaneous measurements with the ionization chamber and the spectrometer system provide reliable estimates of the total background exposure rate, of the individual contributors to the terrestrial exposure rate, and of the exposure rate from the secondary cosmic radiation. The TLD results agree with those of the ionization chamber. The NaI(Tl) detector results show that accurate estimates of the terrestrial exposure rate can be obtained if empirical corrections are applied. (author)

  12. Dose-rate conversion factors for external exposure to photons and electrons

    International Nuclear Information System (INIS)

    This paper describes recent modifications of the computer code DOSFACTER, which was developed for the purpose of estimating dose-rate conversion factors for external exposure to photons and electrons emitted by radionuclides dispersed in the environment. The modifications and additions which have been made to the calculations outlined above include the following: (1) calculation of electron dose-rate factors for radiosensitive portions of the skin; (2) incorporation of improved estimates of organ dose-rate factors for photons; and (3) calculation of dose-rate factors for additional radio nuclides and incorporation of updated radioactive decay data for all radionuclides. The revised dose-rate factors described in this paper are available upon request from the Radiation Shielding Information Center at Oak Ridge National Laboratory

  13. Radioactivity measurements and dose rate calculations using ERICA tool in the terrestrial environment of Greece.

    Science.gov (United States)

    Sotiropoulou, Maria; Florou, Heleny; Manolopoulou, Metaxia

    2016-06-01

    In the present study, the radioactivity levels to which terrestrial non-human biota were exposed are examined. Organisms (grass and herbivore mammals) and abiotic components (soil) were collected during the period of 2010 to 2014 from grasslands where sheep and goats were free-range grazing. Natural background radionuclides ((226)Ra, (228)Ra, (228)Th) and artificial radionuclides ((137)Cs, (134)Cs, (131)I) were detected in the collected samples using gamma spectrometry. The actual measured activity concentrations and site-specific data of the studied organisms were imported in ERICA Assessment Tool (version 1.2.0) in order to provide an insight of the radiological dose rates. The highest activity concentrations were detected in samples collected from Lesvos island and the lowest in samples collected from Attiki and Etoloakarnania prefectures. The highest contribution to the total dose rate was clearly derived from the internal exposure and is closely related to the exposure to alpha emitters of natural background ((226)Ra and (228)Th). The Fukushima-derived traces of (137)Cs, (134)Cs, and (131)I, along with the residual (137)Cs, resulted in quite low contribution to the total dose rate. The obtained results may strengthen the adaptation of software tools to a wider range of ecosystems and may be proved useful in further research regarding the possible impact of protracted low level ionizing radiation on non-human biota. This kind of studies may contribute to the effective incorporation of dosimetry tools in the development of integrated environmental and radiological impact assessment policies. PMID:26897581

  14. Assessment of the ambient dose rate around research reactors by thermoluminescence dosimeters

    Directory of Open Access Journals (Sweden)

    Memon Tanveer A.

    2010-01-01

    Full Text Available Monitoring of radiation levels in and around the nuclear research reactors is essential to safe-guarding life and the environment. Background radiation monitoring at the Pakistan Institute of Nuclear Science & Technology (PINSTECH has been carried out since the early sixties, before the criticality of the 5 MW Pakistan Research Reactor, so as to confirm the safe operation of PINSTECH nuclear facilities. In the present study, ambient dose rate levels were measured around PINSTECH by using TLD-200 (G-2 cards installed at 15 different locations over a five year period (1998-2002. The mean dose rates for individual locations in the said period ranged from 0.14 ± 0.01 to 0.19 ± 0.03 µSv/h, with a mean value of 0.16 ± 0.03 µSv/h. The cu- mulative average annual effective dose equivalent spread over 5 years was 204.4 ± 17 µSv. The data were compared with the world and averages in other countries. It was concluded that, from the health hazard point of view, the operation of research reactors and other nuclear facilities at PINSTECH presents no risk to public health.

  15. Survival of tumor cells after proton irradiation with ultra-high dose rates

    Directory of Open Access Journals (Sweden)

    Belka Claus

    2011-10-01

    Full Text Available Abstract Background Laser acceleration of protons and heavy ions may in the future be used in radiation therapy. Laser-driven particle beams are pulsed and ultra high dose rates of >109 Gy s-1may be achieved. Here we compare the radiobiological effects of pulsed and continuous proton beams. Methods The ion microbeam SNAKE at the Munich tandem accelerator was used to directly compare a pulsed and a continuous 20 MeV proton beam, which delivered a dose of 3 Gy to a HeLa cell monolayer within Results At 10 h after pulsed irradiation, the fraction of G2 cells was significantly lower than after irradiation with the continuous beam, while all other endpoints including colony formation were not significantly different. We determined the relative biological effectiveness (RBE for pulsed and continuous proton beams relative to x-irradiation as 0.91 ± 0.26 and 0.86 ± 0.33 (mean and SD, respectively. Conclusions At the dose rates investigated here, which are expected to correspond to those in radiation therapy using laser-driven particles, the RBE of the pulsed and the (conventional continuous irradiation mode do not differ significantly.

  16. Assessment of the ambient dose rate around research reactors by thermoluminescence dosimeters

    International Nuclear Information System (INIS)

    Monitoring of radiation levels in and around the nuclear research reactors is essential to safeguarding life and the environment. Background radiation monitoring at the Pakistan Institute of Nuclear Science and Technology (PINSTECH) has been carried out since the early sixties, before the criticality of the 5 MW Pakistan Research Reactor, so as to confirm the safe operation of PINSTECH nuclear facilities. In the present study, ambient dose rate levels were measured around PINSTECH by using TLD-200 (G-2 cards) installed at 15 different locations over a five year period (1998-2002). The mean dose rates for individual locations in the said period ranged from 0.1 0.01 to 0.19 ± 0.03 μSv/h, with a mean value of 0.16 ±0.03 μSv/h. The cumulative average annual effective dose equivalent spread over 5 years was 204.4 ± 17 μSv. The data were compared with the world and averages in other countries. It was concluded that, from the health hazard point of view, the operation of research reactors and other nuclear facilities at PINSTECH presents no risk to public health. (author)

  17. Automatic dose-rate controlling equipment

    International Nuclear Information System (INIS)

    The patent of a dose-rate controlling equipment that can be attached to X-ray image-amplifiers is presented. In the new equipment the current of the photocatode of the image-amplifier is led into the regulating unit, which controls the X-ray generator automatically. The advantages of the equipment are the following: it can be simply attached to any type of X-ray image-amplifier, it accomplishes fast and sensitive regulation, it makes possible the control of both the mA and the kV values, it is attached to the most reliable point of the image-transmission chain. (L.E.)

  18. Comparison between calculation methods of dose rates in gynecologic brachytherapy

    International Nuclear Information System (INIS)

    In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)

  19. Environmental outdoor gamma dose rate in air by using TLD dosimeters in Centro Experimental Aramar (CTMSP-Brazil) and region

    International Nuclear Information System (INIS)

    Since 1987, an Environmental Monitoring Programme is being applied for investigating the background radioactive concentrations and chemical parameters in samples collected in Centro Experimental Aramar (CEA) and region. This assessment has been carried out by the Radioecological laboratory. For dosimetric purposes, the experimental results are described obtained with CaF2:Dy thermoluminescence dosimeters (TLD-200) for the measurement of natural outdoor gamma radiation background measured in 26 sample points located in CEA (Centro Experimental Aramar) (CTMSP-Brazil) and surroundings to determine natural gamma radioactivity, from 1998 to 2007. The estimated average annual outdoor gamma dose rate in air in this period is (865 ± 143) μGy.y-1. The average value obtained in the pre-operational conditions is (1006 ± 210) μGy.y-1. The conclusions, by taking into account these results are: the average annual outdoor gamma dose rate is comparable with the background data obtained during the pre-operational conditions indicating low interference in the environment in CEA and region; the average annual outdoor gamma dose rate is analogous as compared with average values of other regions. (author)

  20. A graphical review of radiogenic animal cancer data using the 'dose and dose-rate map'

    International Nuclear Information System (INIS)

    We have been investigating the effects of low dose or low dose rate irradiation on mice, using our low dose-rate irradiation facilities. In these studies, we found that the effects were highly dependent on both total dose and dose rate. To show this visually, we proposed the 'dose/dose rate map', and plotted the results of our laboratory and our co-workers. The map demonstrated that dose/dose rate plane could be divided into three areas; 1) An area where harmful effects are observed, 2) An area where no harmful effects are observed, and 3) Another area, between previous two areas, where certain protective functions are enhanced. As this map would be a powerful tool to find some trend among the vast numbers of data relating the biological effects of ionizing radiation, we have developed a computer program which plots the collected data on the dose/dose rate map sorting by experimental conditions. In this study, we graphically reviewed and analyzed the data relating to the lifespan studies of animals with a view to determining the relationships between doses and dose rates of ionizing radiation and cancer incidence. The data contains about 800 sets of experiments, which concerns 187,000 animals exposed to gamma ray or X-ray and their 112,000 controls, and total of about 30,000 cancers in exposed animals and 14,000 cancers in controls. About 800 points of data were plotted on the dose/dose rate map. The plot showed that 1) The divided three areas in the dose/dose rate map were generally confirmed by these 800 points of data, and 2) In some particular conditions, e.g. sarcoma by X-rays, the biologically effective area is extended to relatively high dose/dose rate area. (author)

  1. Search for radiative decays of cosmic background neutrino using cosmic infrared background energy spectrum

    International Nuclear Information System (INIS)

    We propose to search for the neutrino radiative decay by fitting a photon energy spectrum of the cosmic infrared background to a sum of the photon energy spectrum from the neutrino radiative decay and a continuum. By comparing the present cosmic infrared background energy spectrum observed by AKARI and Spitzer to the photon energy spectrum expected from neutrino radiative decay with a maximum likelihood method, we obtained a lifetime lower limit of 3.1x1012 to 3.8x1012 years at 95% confidence level for the third generation neutrino v3 in the v3 mass range between 50 and 150 meV/c2 under the present constraints by the neutrino oscillation measurements. In the left-right symmetric model, the minimum lifetime of v3 is predicted to be 1.5x1017 years for m3 of 50 meV/c2. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of 1.5x1017 years, by measuring a continuous energy spectrum of the cosmic infrared background. (author)

  2. Remote Afterloading High Dose Rate Brachytherapy AMC EXPERIANCES

    Energy Technology Data Exchange (ETDEWEB)

    Park, Su Gyong; Chang, Hye Sook; Choi, Eun Kyong; Yi, Byong Yong [Ulsan University College of Medicine, Seoul (Korea, Republic of)

    1992-12-15

    Remote afterloading high dose rate brachytherapy(HDRB) is a new technology and needs new biological principle for time and dose schedule. Here, authors attempt to evaluate the technique and clinical outcome in 116 patients, 590 procedures performed at Asan Medical Center for 3 years. From Sep. 1985 to Aug 1992, 471 procedures of intracavitary radiation in 55 patients of cervical cancer and 26 of nasopharyngeal cancer, 79 intraluminal radiation in 12 of esophageal cancer, 11 of endobronchial cancer and 1 Klatskin tumor and 40 interstitial brachytherapy in 4 of breast cancer, 1 sarcoma and 1 urethral cancer were performed. Median follow-up was 7 months with range 1-31 months. All procedures except interstitial were performed under the local anesthesia and they were all well tolerated and completed the planned therapy except 6 patients. 53/58 patients with cervical cancer and 22/26 patients with nasopharynx cancer achieved CR. Among 15 patients with palliative therapy, 80% achieves palliation. We will describe the details of the technique and results in the text. To evaluate biologic effects of HDRB and optimal time/dose/fractionation schedule, we need longer follow-up. But authors feel that HDRB with proper fractionation schedule may yield superior results compared to the low dose rate brachytherapy considering the advantages of HDRB in safety factor for operator, better control of radiation dose and volume and patients comfort over the low dose brachytherapy.

  3. The Effects of the Ionizing Radiation Background on Galaxy Evolution

    CERN Document Server

    Hambrick, D Clay; Naab, Thorsten; Johansson, Peter H

    2009-01-01

    We find that the amount and nature of the assumed ionizing background can strongly affect galaxy formation and evolution. Galaxy evolution simulations typically incorporate an ultraviolet background which falls off rapidly above z=3; e.g., that of Haardt & Madau (1996). However, this decline may be too steep to fit the WMAP constraints on electron scattering optical depth or observations of intermediate redshift (z ~ 2-4) Ly-alpha forest transmission. As an alternative, we present simulations of the cosmological formation of individual galaxies with UV backgrounds that decline more slowly at high redshift: both a simple intensity rescaling and the background recently derived by Faucher-Giguere (2009), which softens the spectrum at higher redshifts. We also test an approximation of the X-ray background with a similar z-dependence. We find for the test galaxies that an increase in either the intensity or hardness of ionizing radiation generically pushes star formation towards lower redshifts: although overa...

  4. Background Radiation Measurements at High Power Research Reactors

    CERN Document Server

    Ashenfelter, J; Baldenegro, C X; Band, H R; Barclay, G; Bass, C D; Berish, D; Bowden, N S; Bryan, C D; Cherwinka, J J; Chu, R; Classen, T; Davee, D; Dean, D; Deichert, G; Dolinski, M J; Dolph, J; Dwyer, D A; Fan, S; Gaison, J K; Galindo-Uribarri, A; Gilje, K; Glenn, A; Green, M; Han, K; Hans, S; Heeger, K M; Heffron, B; Jaffe, D E; Kettell, S; Langford, T J; Littlejohn, B R; Martinez, D; McKeown, R D; Morrell, S; Mueller, P E; Mumm, H P; Napolitano, J; Norcini, D; Pushin, D; Romero, E; Rosero, R; Saldana, L; Seilhan, B S; Sharma, R; Stemen, N T; Surukuchi, P T; Thompson, S J; Varner, R L; Wang, W; Watson, S M; White, B; White, C; Wilhelmi, J; Williams, C; Wise, T; Yao, H; Yeh, M; Yen, Y -R; Zhang, C; Zhang, X

    2016-01-01

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including $\\gamma$-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  5. Background radiation measurements at high power research reactors

    Science.gov (United States)

    Ashenfelter, J.; Balantekin, B.; Baldenegro, C. X.; Band, H. R.; Barclay, G.; Bass, C. D.; Berish, D.; Bowden, N. S.; Bryan, C. D.; Cherwinka, J. J.; Chu, R.; Classen, T.; Davee, D.; Dean, D.; Deichert, G.; Dolinski, M. J.; Dolph, J.; Dwyer, D. A.; Fan, S.; Gaison, J. K.; Galindo-Uribarri, A.; Gilje, K.; Glenn, A.; Green, M.; Han, K.; Hans, S.; Heeger, K. M.; Heffron, B.; Jaffe, D. E.; Kettell, S.; Langford, T. J.; Littlejohn, B. R.; Martinez, D.; McKeown, R. D.; Morrell, S.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Norcini, D.; Pushin, D.; Romero, E.; Rosero, R.; Saldana, L.; Seilhan, B. S.; Sharma, R.; Stemen, N. T.; Surukuchi, P. T.; Thompson, S. J.; Varner, R. L.; Wang, W.; Watson, S. M.; White, B.; White, C.; Wilhelmi, J.; Williams, C.; Wise, T.; Yao, H.; Yeh, M.; Yen, Y.-R.; Zhang, C.; Zhang, X.

    2016-01-01

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  6. Position sensitive detection of neutrons in high radiation background field

    International Nuclear Information System (INIS)

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e− radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm2) spectroscopic Timepix detector adapted for neutron detection utilizing very thin 10B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10−4

  7. Suppressing Background Radiation Using Poisson Principal Component Analysis

    CERN Document Server

    Tandon, P; Dubrawski, A; Labov, S; Nelson, K

    2016-01-01

    Performance of nuclear threat detection systems based on gamma-ray spectrometry often strongly depends on the ability to identify the part of measured signal that can be attributed to background radiation. We have successfully applied a method based on Principal Component Analysis (PCA) to obtain a compact null-space model of background spectra using PCA projection residuals to derive a source detection score. We have shown the method's utility in a threat detection system using mobile spectrometers in urban scenes (Tandon et al 2012). While it is commonly assumed that measured photon counts follow a Poisson process, standard PCA makes a Gaussian assumption about the data distribution, which may be a poor approximation when photon counts are low. This paper studies whether and in what conditions PCA with a Poisson-based loss function (Poisson PCA) can outperform standard Gaussian PCA in modeling background radiation to enable more sensitive and specific nuclear threat detection.

  8. Robust ray-tracing algorithms for interactive dose rate evaluation

    International Nuclear Information System (INIS)

    More than ever, it is essential today to develop simulation tools to rapidly evaluate the dose rate received by operators working on nuclear sites. In order to easily study numerous different scenarios of intervention, computation times of available softwares have to be all lowered. This mainly implies to accelerate the geometrical computations needed for the dose rate evaluation. These computations consist in finding and sorting the whole list of intersections between a big 3D scene and multiple groups of 'radiative' rays meeting at the point where the dose has to be measured. In order to perform all these computations in less than a second, we first propose a GPU algorithm that enables the efficient management of one big group of coherent rays. Then we present a modification of this algorithm that guarantees the robustness of the ray-triangle intersection tests through the elimination of the precision issues due to floating-point arithmetic. This modification does not require the definition of scene-dependent coefficients ('epsilon' style) and only implies a small loss of performance (less than 10%). Finally we propose an efficient strategy to handle multiple ray groups (corresponding to multiple radiative objects) which use the previous results.Thanks to these improvements, we are able to perform an interactive and robust dose rate evaluation on big 3D scenes: all of the intersections (more than 13 million) between 700 000 triangles and 12 groups of 100 000 rays each are found, sorted along each ray and transferred to the CPU in 470 milliseconds. (author)

  9. The Cosmic Microwave Background Radiation and its Polarization

    Science.gov (United States)

    Wollack, Edward

    2016-03-01

    The cosmic microwave background (CMB) radiation and its faint polarization have provided a unique means to constrain the physical state of the early Universe. Continued advances in instrumentation, observation, and analysis have revealed polarized radiation signatures associated with gravitational lensing and have heightened the prospects for using precision polarimetry to experimentally confront the inflationary paradigm. Characterization of this relic radiation field has the power to constrain or reveal the detailed properties of astroparticle species and long wave gravitational radiation. On going and planned CMB polarization efforts from the ground, balloon, and space borne platforms will be briefly surveyed. Recent community activities by the Inflation Probe Science Interest Group (IPSIG) will also be summarized. NASA PCOS mini-symposium (invited IPSIG talk).

  10. Pulsed electrons of ultrahigh dose-rate effect in decreasing ferric ions of a Fricke dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rawi, A.M.; Saleh, M.M.; Al-Meshadani, N.A.F.; Al-Fakhri, K.A.K. (Baghdad Univ. (Iraq). Dept. of Chemistry)

    1983-01-01

    The yield of ferric ions produced in a Fricke dosimeter containing 10/sup -3/ M ferrous sulphate by high intensities of radiation was found to decrease with increasing dose-rates. A G(Fe/sup 3 +/) of 8.2 has been determined with dose-rates generated by the Febetron accelerator in the range 10/sup 27/ to 10/sup 29/ eVl/sup -1/ sec/sup -1/. An almost identical G(Fe/sup 3 +/) for this range of dose-rates has been evaluated by Thomas and Hart using an entirely different method.

  11. Pulsed electrons of ultrahigh dose-rate effect in decreasing ferric ions of a Fricke dosimeter

    International Nuclear Information System (INIS)

    The yield of ferric ions produced in a Fricke dosimeter containing 10-3 M ferrous sulphate by high intensities of radiation was found to decrease with increasing dose-rates. A G(Fe3+) of 8.2 has been determined with dose-rates generated by the Febetron accelerator in the range 1027 to 1029 eVl-1 sec-1. An almost identical G(Fe3+) for this range of dose-rates has been evaluated by Thomas and Hart using an entirely different method. (author)

  12. Construction of radioelement and dose rate baseline maps by combining ground and airborne radiometric data

    International Nuclear Information System (INIS)

    For emergency situations like nuclear accidents, lost isotopic sources, debris of reactor-powered satellites etc. well-documented baseline information is indispensable. Maps of cosmic, terrestrial natural and artificial radiation can be constructed by assembling different datasets such as ground and airborne gamma spectrometry, direct dose rate measurements, and soil/rock samples. The in situ measurements were calibrated using the soil samples taken at/around the field measurement sites, the airborne measurements by a combination of in situ, and soil/rock sample data. The radioelement concentrations (Bq/kg) were in turn converted to dose-rate (nSv/h). First, the cosmic radiation map was constructed from a digital terrain model, averaging topographic heights within cells of 2 km X 2 km size. For the terrestrial radiation a total of 1615 ground data points were available, in addition to the airborne data. The artificial radiation map (Chernobyl and earlier fallout) has the smallest data base (184 data points from airborne and ground measurements). The dose rate map was constructed by summing up the above-mentioned contributions. It relies on a data base which corresponds to a density of about 1 point per 25 km2. The cosmic radiation map shows elevated dose rates in the high parts of the Swiss Alps. The cosmic dose rate ranges from 40 to 190 nSv/h, depending on altitude. The terrestrial dose rate maps show general agreement with lithology: elevated dose rates (100 to 200 nSv/h) characterize the Central Massifs of the Alps where crystalline rocks give a maximum of 370 nSv/h, whereas the sedimentary northern Alpine Foreland (Jura, Molasse basin) shows consistently lower dose rates (40-100 nSv/h). The artificial radiation map has its maximum value in the southern part of Switzerland (90 nSv/h). The map of total dose rate exhibits values from 55 to 570 nSv/h. These values are considerably higher than reported in the Radiation Atlas (''Natural Sources of Ionising Radiation

  13. Long-term TLD measurements of environmental background radiation in the New York City Area

    International Nuclear Information System (INIS)

    The results of month-long TLD measurements at seven locations within 150 km of New York City are reported for 12 years at a few locations and for up to 18 years at others. At some locations, multiple dosimeters were deployed to acquire concurrent indoor and outdoor measurements. The sites were varied and include an urban high-rise residence, three suburban backyards, a rural hillside, and the wooded outskirts of a nuclear power plant (nonoperational). Long-term mean dose rates in air ranged from 50.8 to 123.1 nGy h-1 (5.8 to 14.1 μR h-1) across the area. The typical seasonal dose rate in air variations are presented for two of the sites and are briefly discussed in terms of soil conditions. The data indicate that it is possible to achieve monthly variations from the long-term mean as high as 20 to 40%. One of these locations was monitored for indoor (2 floors) and outdoor air dose rates. This allowed for a time series comparison to be performed illustrating the changing contribution of terrestrial radiation to the total dose rate relative to the steady building material-derived radioactivity. This site also permitted the calculation of indoor/outdoor ratios for two floors. Another suburban location yielded an indoor/outdoor ratio using ground floor dose-rate-in-air measurements. Also presented are mean annual dose rates in air showing a long-term decrease at some locations. A statistical Kendall test was performed to quantify the magnitude of the decrease. A definitive explanation of this trend requires further study

  14. Alternative application for the radiation background in the development of the atlas database of atmospheric radiation

    CERN Document Server

    De la Hoz, Ivan Arturo Morales

    2014-01-01

    Nowadays radiation is one of the variables to be considered in the environmental forecasting and it is meaningful in the increase of global warming, together greenhouse effect. The radiation considered by the meteorological organizations depends on the World Radiometric Reference (WRR), the World Standard Group (WSG), addressed by the World Meteorological Organization (WMO). This work is based on the cosmic microwave background, as a variable to be estimated in order to get information about the incident radiation in the Earth's atmosphere, as a valuable and meaningful contribution in the building of the radiation atlas by the (UPME) and (IDEAM). Due to the fact that the variables considered are ultraviolet and infrared radiation, ozone column, direct radiation and diffuse radiation, the last two get the global radiation, and are the only ones to be evaluated by the national meteorological organizations in the country. The study of the cosmic background radiation as a research project will provide data which ...

  15. Cosmic microwave background radiation anisotropies in brane worlds.

    Science.gov (United States)

    Koyama, Kazuya

    2003-11-28

    We propose a new formulation to calculate the cosmic microwave background (CMB) spectrum in the Randall-Sundrum two-brane model based on recent progress in solving the bulk geometry using a low energy approximation. The evolution of the anisotropic stress imprinted on the brane by the 5D Weyl tensor is calculated. An impact of the dark radiation perturbation on the CMB spectrum is investigated in a simple model assuming an initially scale-invariant adiabatic perturbation. The dark radiation perturbation induces isocurvature perturbations, but the resultant spectrum can be quite different from the prediction of simple mixtures of adiabatic and isocurvature perturbations due to Weyl anisotropic stress. PMID:14683226

  16. Analysis of Potassium in Bricks—Determining the Dose Rate from 40K for Thermoluminescence Dating

    Science.gov (United States)

    Musílek, Ladislav; Polách, Tomáš; Trojek, Tomáš

    2008-08-01

    Thermoluminescence (TL) dating is based on accumulating the natural radiation dose in the material of a dated artefact (brick, pottery, etc.), and comparing the dose accumulated during the lifetime of the object with the dose rate within the sample collected for TL measurement. Determining the dose rate from natural radionuclides in materials is one of the most important and most difficult parts of the technique. The most important radionuclides present are usually nuclides of the uranium and thorium decay series and 40K. An analysis of the total potassium concentration enables us to determine the 40K content effectively, and from this it is possible to calculate the dose rate originating from this radiation source. X-ray fluorescence (XRF) analysis can be used to determine the potassium concentration in bricks rapidly and efficiently. The procedure for analysing potassium, examples of results of dose rate calculation and possible sources of error are described here.

  17. Analysis of Potassium in Bricks--Determining the Dose Rate from 40K for Thermoluminescence Dating

    International Nuclear Information System (INIS)

    Thermoluminescence (TL) dating is based on accumulating the natural radiation dose in the material of a dated artefact (brick, pottery, etc.), and comparing the dose accumulated during the lifetime of the object with the dose rate within the sample collected for TL measurement. Determining the dose rate from natural radionuclides in materials is one of the most important and most difficult parts of the technique. The most important radionuclides present are usually nuclides of the uranium and thorium decay series and 40K. An analysis of the total potassium concentration enables us to determine the 40K content effectively, and from this it is possible to calculate the dose rate originating from this radiation source. X-ray fluorescence (XRF) analysis can be used to determine the potassium concentration in bricks rapidly and efficiently. The procedure for analysing potassium, examples of results of dose rate calculation and possible sources of error are described here

  18. A comparative study of biological effects on tumor cells between low-dose-rate β-irradiation and high- dose-rate γ-irradiation

    International Nuclear Information System (INIS)

    Objective: To elucidate the radiobiological mechanism underlying cancer treatment with low-dose-rate β-irradiation of 32P, by comparing the cell-killing pattern with high-dose-rate γ-irradiation of 60Co. Methods: HeLa cells were exposed to low-dose-rate β-irradiation of 32P or high-dose-rate γ-irradiation of 60Co. Comparisons were made between these two types of radiations, focusing on the cell-killing patterns evaluated by radiation-induced reproductive cell death( senescence) and necrotic cell death through X-gal senescence staining and tRypan blue exclusion method respectively. Results: The results showed that there were different cell-killing patterns in HeLa cells between 32P radiation at dose-rate of 0.375 cGy/min and that of 60Co at dose-rate of 206 cGy/min at 72 h post irradiation. In exposure to 32P, more HeLa cells were lost due to reproductive cell death than to 60Co. X-gal staining showed that senescent cell ratio in HeLa cells after exposure of 32P was higher than after that of 60Co which caused more necrotic cell death. Conclusions: More reproductive and less necrotic cell death contribute to total cell loss in HeLa cells by radiation of 32P than by 60Co. Understanding the underlying mechanism of radiobiology in different radiations is helpful in radiotherapy of malignant tumor by choosing a more reasonable and effective procedure of treatment. (author)

  19. Dose rate measurements around consignments of radioactive material

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency's (IAEA) Regulations for the Safe Transport of Radioactive Material require compliance with various radiation protection control measures and also require the competent authority to arrange for periodic assessments of the radiation doses to workers and to members of the public. It is a two-fold approach of controls and assessments. Periodic reviews of the radiological impact arising from the transport of radioactive materials by road, rail, sea and air, have been undertaken by NRPB on behalf of the UK Competent Authority. Dose assessments were made using estimated exposure times together with measured and extrapolated dose rates from 'near-field' regions close to consignments, 'mid-field' regions occupied by transiently exposed persons and 'far-field' regions occupied by members of the public. The results show that annual doses to workers and public are generally small fractions of dose limits. The exception is a small group of driver/handlers involved with packages for medical and industrial use. Compliance with the Regulations has ensured that a sufficient degree of control exists. Originally, most packages were small compared with the distances to exposed persons. Point source geometry was therefore used. More recently, it has been estimated that only a minority of all consignments of radioactive material is of sufficiently small dimensions for point source geometry to continue to apply. Instead, initial despatches of radionuclide packages can consist of consignments of several cubic metres in size, and only at tertiary despatch level would point source geometry prevail. However, for all physically large loads, the measured dose rates do not decline as rapidly as point source geometry would suggest based on the Tl value. Development of the methodology adopted by the IAEA Regulations over some 40 years has introduced parameters to compensate in part for these levels of dose rate, and, together with operational improvements

  20. Dose and Dose-Rate Effectiveness Factor (DDREF); Der Dosis- und Dosisleistungs-Effektivitaetsfaktor (DDREF)

    Energy Technology Data Exchange (ETDEWEB)

    Breckow, Joachim [Fachhochschule Giessen-Friedberg, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz

    2016-08-01

    For practical radiation protection purposes it is supposed that stochastic radiation effects a determined by a proportional dose relation (LNT). Radiobiological and radiation epidemiological studies indicated that in the low dose range a dependence on dose rates might exist. This would trigger an overestimation of radiation risks based on the LNT model. OCRP had recommended a concept to combine all effects in a single factor DDREF (dose and dose-Rate effectiveness factor). There is still too low information on cellular mechanisms of low dose irradiation including possible repair and other processes. The Strahlenschutzkommission cannot identify a sufficient scientific justification for DDREF and recommends an adaption to the actual state of science.

  1. Nature of the Background Ultraviolet Radiation Field at High Redshifts

    Indian Academy of Sciences (India)

    Archana Samantaray; Pushpa Khare

    2000-06-01

    We have tried to determine the flux of the ultraviolet background radiation field from the column density ratios of various ions in several absorption systems observed in the spectra of QSOs. We find that in most cases the flux is considerably higher than what has been estimated to be contributed by the AGNs. The excess flux could originate locally in hot stars. In a few cases we have been able to show that such galactic flux can only contribute a part of the total required flux. The results suggest that the background gets a significant contribution from an unseen QSO population.

  2. Wormhole solution of BD theory in an anisotropic radiation background

    Directory of Open Access Journals (Sweden)

    B. Nasre Esfahani

    2001-06-01

    Full Text Available   Time-dependent wormhole solution of the BD theory in an anisotropic radiation background is presented. It is also found that the BD scalar field depends only on time. This time dependency is in power-law form. It is shown that the wormhole geometry is valid for ω ≥ -3/2, and for any arbitrary positive values of . The GR limit of our solution is obtained for ω=0 , not for ω→∞ . Though the BD field can be non-exotic, the background material is entirely exotic.

  3. Predictions of radiation backgrounds for GRO/OSSE

    International Nuclear Information System (INIS)

    In view of the important influence of background radiation induced by the charged particle environment on the sensitivity of space-borne gamma-ray instrumentation, an extensive series of simulations has been performed on representations of the Oriented Scintillation Spectrometer Experiment and Gamma Ray Observatory Spacecraft. Previously reported results on shielding are summarised and new results are presented on the influence of detector and spacecraft orientation within anisotropic trapped proton distributions. For the cosmic ray calculation, confidence is obtained by comparison with background observations obtained during a balloon flight of a single detector unit over Alice Springs. (author)

  4. Determination of uncertainties in the calculation of dose rates at transport and storage casks

    International Nuclear Information System (INIS)

    The compliance with the dose rate limits for transport and storage casks (TLB) for spent nuclear fuel from pressurised water reactors can be proved by calculation. This includes the determination of the radioactive sources and the shielding-capability of the cask. In this thesis the entire computational chain, which extends from the determination of the source terms to the final Monte-Carlo-transport-calculation is analysed and the arising uncertainties are quantified not only by benchmarks but also by variational calculi. The background of these analyses is that the comparison with measured dose rates at different TLBs shows an overestimation by the values calculated. Regarding the studies performed, the overestimation can be mainly explained by the detector characteristics for the measurement of the neutron dose rate and additionally in case of the gamma dose rates by the energy group structure, which the calculation is based on. It turns out that the consideration of the uncertainties occurring along the computational chain can lead to even greater overestimation. Concerning the dose rate calculation at cask loadings with spent uranium fuel assemblies an uncertainty of ((+21-28) ±2) % (rel.) for the total gamma dose rate and of (+28±23-55±4) % (rel.) for the total neutron dose rate are estimated. For mixed-loadings with spent uranium and MOX fuel assemblies an uncertainty of (+24±3-27±2) % (rel.) for the total gamma dose rate and of (+28±23-55±4) % (rel.) for the total neutron dose rate are quantified. The results show that the computational chain has not to be modified, because the calculations performed lead to conservative dose rate predictions, even if high uncertainties at neutron dose rate measurements arise. Thus at first the uncertainties of the neutron dose rate measurement have to be decreased to enable a reduction of the overestimation of the calculated dose rate afterwards. In the present thesis the deviation of the measured and calculated

  5. Theoretical explanation of enhanced low dose rate sensitivity in erbium-doped optical fibers.

    Science.gov (United States)

    Gilard, Olivier; Thomas, Jérémie; Troussellier, Laurent; Myara, Mikhael; Signoret, Philippe; Burov, Ekaterina; Sotom, Michel

    2012-05-01

    A new theoretical framework is proposed to explain the dose and dose-rate dependence of radiation-induced absorption in optical fibers. A first-order dispersive kinetics model is used to simulate the growth of the density of color centers during an irradiation. This model succeeds in explaining the enhanced low dose rate sensitivity observed in certain kinds of erbium-doped optical fiber and provides some insight into the physical reasons behind this sensitivity. PMID:22614396

  6. Backgrounds of computer-assisted treatment planning in radiation therapy

    International Nuclear Information System (INIS)

    Interaction of ionising radiation and living materials causes biological damage of tempory or permanent nature. In radiation therapy this phenomenon is used in a controlled fashion in order to stop the proliferation of malignant cells, while at the same time limiting the permanent damage to healthy tissues and organs to at least tolerable levels. Because of the often relatively small differences in response of malignant growths and normal tissues, the margins between tolerable and intolerable are so small that the greatest precision in treatment planning and execution is required. The nature of this treatment agent implies that the radiation therapist has to rely very much on instrumentally obtained and processed information, in all phases of this medical activities around the patient. In this paper a description is given of the backgrounds of computer-assisted methods which have enabled modern individualised and optimised planning for therapy with high energy X- and gamma beams. (orig.)

  7. CERN-derived analysis of lunar radiation backgrounds

    Science.gov (United States)

    Wilson, Thomas L.; Svoboda, Robert

    1993-01-01

    The Moon produces radiation which background-limits scientific experiments there. Early analyses of these backgrounds have either failed to take into consideration the effect of charm in particle physics (because they pre-dated its discovery), or have used branching ratios which are no longer strictly valid (due to new accelerator data). We are presently investigating an analytical program for deriving muon and neutrino spectra generated by the Moon, converting an existing CERN computer program known as GEANT which does the same for the Earth. In so doing, this will (1) determine an accurate prompt neutrino spectrum produced by the lunar surface; (2) determine the lunar subsurface particle flux; (3) determine the consequence of charm production physics upon the lunar background radiation environment; and (4) provide an analytical tool for the NASA astrophysics community with which to begin an assessment of the Moon as a scientific laboratory versus its particle radiation environment. This will be done on a recurring basis with the latest experimental results of the particle data groups at Earth-based high-energy accelerators, in particular with the latest branching ratios for charmed meson decay. This will be accomplished for the first time as a full 3-dimensional simulation.

  8. Evaluation of the natural background radiation in City Sopron

    Energy Technology Data Exchange (ETDEWEB)

    Spaits, T. [West Hungary Univ., Institute of Forestry Mechanics (Hungary); Divos, F. [West Hungary Univ., National Radiation Control System - Sopron Unit (Hungary); Kavasi, N. [Veszprem Univ., Dept. of Radiochemistry (Hungary); Boka, Z. [West Hungary Univ., Dept. of Geodetics and Remote Sensing (Hungary)

    2006-07-01

    In the Postgraduate School of the Faculty of Forestry of the University of West Hungary a project with the topic Research of natural radioactive isotopes in our built and natural environs is being run. Preparing this map is an organic part of this PhD research. The measurements are being made in Sopron city and in its next surroundings, trying to estimate, which dose of radiation a citizen of Sopron is exposed, according to his age and lifestyle. The measurements completely cover the built-up area of Sopron, moreover they exceed the confines, so thus they provide information about the natural areas in the vicinity of the city. In figures, the detection carried out in an area of 24 square kilometres, working with a grid mesh of 200 metres. A sodium-iodide detector was used. We have faced several anomalies while mapping. These are the following: On Main Square (Foter), Ursulin Square (Orsolya ter), Paulites Square (Palosok tere, where a higher dose can be measured, due to granite cobbles, used to cover the pavements of the squares and streets. This was confirmed by the gamma spectrometric examination of the granite stones. In these areas, a triple of the mean dose-rate of 70-90 n Sv/h in Sopron was detected. The highest values of 400 n Sv/h were detected in the cinder-covered car-park of the paint store in Koszegi Street. The total gamma activity concentration of the cinder used in the car-park was nearly 2000 Bq/kg. A triple to a quadruple of the natural level was detected in the vicinity of the chimney of the former thermal power plant and the brick factory. The detection was carried out in four directions with raising range starting by the chimneys, which has spectacularly shown, that the sedimentation of the aerosols can be tracked is a function of distance. The measurements have also shown, that there is a significant difference between dose-levels of the natural areas beyond the eastern and western edge of the city, which can be explained with the different

  9. Evaluation of the natural background radiation in City Sopron

    International Nuclear Information System (INIS)

    In the Postgraduate School of the Faculty of Forestry of the University of West Hungary a project with the topic Research of natural radioactive isotopes in our built and natural environs is being run. Preparing this map is an organic part of this PhD research. The measurements are being made in Sopron city and in its next surroundings, trying to estimate, which dose of radiation a citizen of Sopron is exposed, according to his age and lifestyle. The measurements completely cover the built-up area of Sopron, moreover they exceed the confines, so thus they provide information about the natural areas in the vicinity of the city. In figures, the detection carried out in an area of 24 square kilometres, working with a grid mesh of 200 metres. A sodium-iodide detector was used. We have faced several anomalies while mapping. These are the following: On Main Square (Foter), Ursulin Square (Orsolya ter), Paulites Square (Palosok tere, where a higher dose can be measured, due to granite cobbles, used to cover the pavements of the squares and streets. This was confirmed by the gamma spectrometric examination of the granite stones. In these areas, a triple of the mean dose-rate of 70-90 n Sv/h in Sopron was detected. The highest values of 400 n Sv/h were detected in the cinder-covered car-park of the paint store in Koszegi Street. The total gamma activity concentration of the cinder used in the car-park was nearly 2000 Bq/kg. A triple to a quadruple of the natural level was detected in the vicinity of the chimney of the former thermal power plant and the brick factory. The detection was carried out in four directions with raising range starting by the chimneys, which has spectacularly shown, that the sedimentation of the aerosols can be tracked is a function of distance. The measurements have also shown, that there is a significant difference between dose-levels of the natural areas beyond the eastern and western edge of the city, which can be explained with the different

  10. Down syndrome and the high background radiation areas of Kerala

    International Nuclear Information System (INIS)

    Down syndrome (DS) or trisomy-21 is a complex human clinical entity compromising several functional, structural and developmental features with wide variation in expression levels. The diagnosis is confirmed in majority of the cases by an extra dose of chromosome 21 by cytogenetics and occasionally it may be due to either chromosomal translocation or mosaicism (different cell lines in the same individual). The extra chromosome 21 is usually formed by non-disjunction during meiosis and is the most common numerical chromosomal anomaly compatible with life, as chromosome 21 is one of the smallest with relatively fewer genes most of which are reckoned to be non lethal. Though exact causative factors and pathogenesis is not fully understood, a rise in maternal age at conception coupled with deleterious environmental influence on an ageing ovum is a recognized risk factor. The de novo nature of trisomy-21 and its relatively higher frequency makes it a reliable indicator to assess the role of chronic high background radiation in inducing germ line mutation and congenital malformation. Many other relatively common congenital malformations with multifactorial origin may not have this de novo property and associating its incidence with the prevailing natural background radiation become more complex. In vitro studies have shown association between high intensity radiation and genetics effects but such a relationship so far was not established between DS and radiation

  11. High-dose-rate interstitial brachytherapy for the treatment of penile carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Petera, J.; Odrazka, K.; Zouhar, M.; Bedrosova, J.; Dolezel, M. [Dept. of Oncology and Radiotherapy, Charles Univ. Medical School and Teaching Hospital, Hradec Kralove (Czech Republic)

    2004-02-01

    Background: interstitial low-dose-rate (LDR) brachytherapy allows conservative treatment of T1-T2 penile carcinoma. High-dose-rate (HDR) is often considered to be dangerous for interstitial implants because of a higher risk of complications, but numerous reports suggest that results may be comparable to LDR. Nevertheless, there are no data in the literature available regarding HDR interstitial brachytherapy for carcinoma of the penis. Case report: a 64-year-old man with T1 NO MO epidermoid carcinoma of the glans is reported. Interstitial HDR brachytherapy was performed using the stainless hollow needle technique and a breast template for fixation and good geometry. The dose delivered was 18 x 3 Gy twice daily. Results: after 232 days from brachytherapy, the patient was without any evidence of the tumor, experienced no serious radiation-induced complications, and had a fully functional organ. Conclusion: HDR interstitial brachytherapy is feasible in selected case of penis carcinoma, when careful planning and small single fractions are used. (orig.)

  12. Effects of emitter junction and passive base region on low dose rate effect in bipolar devices

    International Nuclear Information System (INIS)

    Low dose rate effect in bipolar devices consists in the increase of peripheral surface recombination current with dose rate decrease. This is due to the more rapid positive oxide charge and interface trap density build-up as the dose rate becomes lower. High dose rate elevated temperature irradiation is proposed for simulation if the low dose rate effect. In the present we tried to separate the effect of radiation-induced charge in the thick passivation oxide over the emitter junction and passive base regions of npn bipolar transistor. Its goal is to improve bipolar device design for use in space environments and nuclear installations. Three experiments were made during this work. 1. Experiment on radiation-induced charge neutralization (RICN) effect under elevated temperature was performed to show transistor degradation dependence on emitter-base bias. 2. High dose rate elevated and room temperature irradiation of bipolar transistors were performed to separate effects of emitter-junction and passive base regions. 3. Pre- and post- irradiation hydrogen ambient storage was used to investigate its effect on radiation-induced charge build-up over the passive base region. All experiments were performed with npn and pnp transistors. (authors)

  13. Dose rate in the reactor room and environment during maintenance in fusion reactors

    International Nuclear Information System (INIS)

    According to the International Thermonuclear Experimental Reactor (ITER) conceptual design activity, after reactor shutdown, damaged segments are pulled up from the reactor and hung from the reactor room ceiling by a remote handling device. The dose rate in the reactor room and the environment is estimated for this situation, and the following results are obtained. First, the dose rate in the room is > 108 μSv/h. Since this dose rate is 107 times greater than the biological radiation shielding design limit of 25 μSv/h, workers cannot enter the room. Second, lenses and optical fiber composed of glass that is radiation resistant up to 106 Gy would be damaged after <100 h near the segment, and devices using semiconductors could not work after several hours or so in the aforementioned dose-rate conditions. Third, during suspension of one blanket segment from the ceiling, the dose rate in the site boundary can be reduced by one order by a 23-cm-thicker reactor building roof. To reduce dose rate in public exposure to a value that is less than one-tenth of the public exposure radiation shielding design limit of 100 μSv/yr, the distance of the site boundary from the reactor must be greater than 200 m for a reactor building with a 160-cm-thick concrete roof. 9 refs., 6 figs., 2 tabs

  14. Assessment of Radiation Background Variation for Moving Detection Systems

    Energy Technology Data Exchange (ETDEWEB)

    Miller, James Christopher [Los Alamos National Laboratory; Rennie, John Alan [Los Alamos National Laboratory; Toevs, James Waldo [Los Alamos National Laboratory; Wallace, Darrin J. [Los Alamos National Laboratory; Abhold, Mark Edward [Los Alamos National Laboratory

    2015-07-13

    The introduction points out that radiation backgrounds fluctuate across very short distances: factors include geology, soil composition, altitude, building structures, topography, and other manmade structures; and asphalt and concrete can vary significantly over short distances. Brief descriptions are given of the detection system, experimental setup, and background variation measurements. It is concluded that positive and negative gradients can greatly reduce the detection sensitivity of an MDS: negative gradients create opportunities for false negatives (nondetection), and positive gradients create a potentially unacceptable FAR (above 1%); the location of use for mobile detection is important to understand; spectroscopic systems provide more information for screening out false alarms and may be preferred for mobile use; and mobile monitor testing at LANL accounts for expected variations in the background.

  15. Inverse dose-rate effect for mutation induction by γ-rays in human lymphoblasts

    International Nuclear Information System (INIS)

    In order to define further the effects of differences in recombinational proficiency on cell survival and mutation by ionizing radiation, we exposed the syngenic cell lines TK6 and WTK1 to continuous low dose-rate γ-irradiation. We previously demonstrated that acute X-ray exposure results in lower survival and lower mutation induction at both the thymidine kinase (tk) and the hypoxanthine-guanine phosphoribosyltransferase (hprt) loci in TK6 cells compared with WTK1 cells. These differences were attributed in part to reduced levels of recombination in the TK6 line relative to WTK1. Using a low dose rate 137Cs irradiator, we exposed asynchronous growing populations of these cells to γ-rays at 14.3, 6.7 and 2.7 cGy/h. Both cell lines exhibited a dose-rate effect on survival. Compared with acute doses, the low dose-rates also protected against mutation induction at the hrpt locus in WTK1, but protection was inversely related to dose-rate. There was also a slight inverse dose-rate effect in TK6, with mutation induction at the lowest dose-rate exceeding that at acute exposures. (Author)

  16. External dose rate in Unirea salt mine, Slanic-Prahova, Romania.

    Science.gov (United States)

    Margineanu, R M; Apostu, A M; Duliu, O G; Bercea, S; Gomoiu, C M; Cristache, C I

    2009-05-01

    The distribution of the external dose rate within the former Unirea salt mine, host of the Low-Level Background Laboratory was determined and compared with calculated values based on the experimentally determined content of natural radioactive elements in the mine walls. The average external dose rate was found to be 1.3+/-0.3 nSv h(-1), close to calculated one of 1.4+/-0.2 nSv h(-1). PMID:19231217

  17. External dose rate in Unirea salt mine, Slanic-Prahova, Romania

    Energy Technology Data Exchange (ETDEWEB)

    Margineanu, R.M.; Apostu, A.M. [National Institute of Research and Development for Physics and Nuclear Engineering ' Horia-Hulubei' , P.O. Box MG-6, 077125 Magurele (Ilfov) (Romania); Duliu, O.G. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077152 Magurele (Ilfov) (Romania)], E-mail: duliu@b.astral.ro; Bercea, S.; Gomoiu, C.M.; Cristache, C.I. [National Institute of Research and Development for Physics and Nuclear Engineering ' Horia-Hulubei' , P.O. Box MG-6, 077125 Magurele (Ilfov) (Romania)

    2009-05-15

    The distribution of the external dose rate within the former Unirea salt mine, host of the Low-Level Background Laboratory was determined and compared with calculated values based on the experimentally determined content of natural radioactive elements in the mine walls. The average external dose rate was found to be 1.3{+-}0.3 nSv h{sup -1}, close to calculated one of 1.4{+-}0.2 nSv h{sup -1}.

  18. Variation of natural background radiation in the Federal Republic of Germany

    International Nuclear Information System (INIS)

    Within the framework of a research project supported by the Federal Minister of the Interior, 30,000 measurements were conducted with scintillation dosimeters of the same type in 10 institutions distributed all over the Federal Republic of Germany, determining the local rate of gamma radiation in building (mean values). In addition, 25,000 measurements of the local dose rate of gamma radiation in the free environment as well as approximately 600 measurements were performed via gamma spectroscopy of the specific content of natural radioactive substances in building materials. The dose rate measurements were centrally evaluated by an electronic data processing system, whereby regional differences, differences depending on age and type of buildings, differences depending on the content of natural radioactive substances in building materials were taken into consideration. The results of this research program are discussed

  19. Vertebrate radiations of the Jehol Biota and their environmental background

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhonghe

    2004-01-01

    @@ Significant progress has been made in recent years in the studies of various groups of the Jehol Biota, particularly concerning the origin of birds and their flight as well as the evolution of Early Cretaceous birds, dinosaurs, mammals, insects and flowering plants[1-5]. As a result, the Jehol Biota has become well known to both the scientific community and the public. The studies on the Jehol Biota also revealed the patterns and processes of the evolutionary radiations of many major groups of Early Cretaceous animals and plants, such as the earliest known radiation of angiosperms and birds, early differentiation of mammals and many Cretaceous dinosaurian groups. Notably, the radiations of the Jehol vertebrates share some similar patterns attributable to the particular environmental background. For instance, the Jehol vertebrate radiations are highlighted by the presence of abundant arboreal adaptations and herbivorous forms, thus closely linked to the forest environments. In addition, the differentiation of habitats and diets is also characteristic of the evolutionary radiations of pterosaurs, dinosaurs, birds and mammals in the Jehol Biota.

  20. 3D-image-guided high-dose-rate intracavitary brachytherapy for salvage treatment of locally persistent nasopharyngeal carcinoma

    OpenAIRE

    Ren, Yu-Feng; Cao, Xin-Ping; Xu, Jia; Ye, Wei-Jun; Gao, Yuan-Hong; Teh, Bin S.; Wen, Bi-Xiu

    2013-01-01

    Background To evaluate the therapeutic benefit of 3D-image-guided high-dose-rate intracavitary brachytherapy (3D-image-guided HDR-BT) used as a salvage treatment of intensity modulated radiation therapy (IMRT) in patients with locally persistent nasopharyngeal carcinoma (NPC). Methods Thirty-two patients with locally persistent NPC after full dose of IMRT were evaluated retrospectively. 3D-image-guided HDR-BT treatment plan was performed on a 3D treatment planning system (PLATO BPS 14.2). The...

  1. Gamma dose rate mapping of APSARA structural components for decommissioning

    International Nuclear Information System (INIS)

    APSARA was a swimming pool type research reactor operated using Highly Enriched Uranium fuel. The reactor pool water was used as coolant, moderator, reflector and radiological shielding. Graphite and beryllium oxide encased in aluminum boxes were used as in-core reflector. The reactor had a maximum power level of 1 MW and was mostly operated up to 400 KW. APSARA was shut down for major refurbishment in 2009. Defuelling and partial decommissioning of reactor was carried out. The core structure and other reactor components were dismantled and shifted to Waste Management site. 'Second stage decommissioning' planned further consists of dismantling and disposal of various components like thermal column, shielding racks, graphite blocks, stainless steel liner of pool and the pool block itself. Detailed gamma dose rate mapping study served in localizing and identifying hotspots of activation product activity in structural components of the APSARA reactor in order to plan the strategy for dismantling of the pool structure. In-situ gamma spectrometry of the structural components was carried out for qualitative and semi quantitative characterization of the bulk structural materials in pool walls, SS and aluminum liners, shield racks, graphite blocks etc., to plan the dismantling and demolition of large structures. This study has also served in comparing the performance of different radiation measuring instruments used for such large area insitu dose rate measurements and mapping

  2. Improved estimates of Ar-41 gamma dose rates around Hinkley Point power station

    International Nuclear Information System (INIS)

    The dominant source of external gamma dose rates at population centres within a few kilometres of Hinkley Point Power Station arising from operation of the station is the routine discharge of Ar-41 from the 'A' station magnox reactors. Earlier estimates of Ar-41 radiation dose rates were based upon measured discharge rates, combined with calculations using standard plume dispersion and cloud-gamma integration models. This paper presents improved dose estimates derived from environmental gamma dose rate measurements made at distances up to about 1 km from the site, minimising the degree of extrapolation introduced in estimating dose rates at locations up to a few kilometres from the site. Results from associated chemical tracer measurements and wind tunnel simulations covering distances up to about 4 km from the station are outlined. (author)

  3. Research on enhanced low dose rate sensitivity effect for PMOSFET used in space dosimeter

    International Nuclear Information System (INIS)

    In this paper, the ionizing damage effects and annealing behavior of foreign manufacturer production PMOSFET in 4007 circuit under different dose rates and bias conditions were investigated. The experiment results show that the PMOSFETs threshold voltage negative shift is more obvious with the dose rate reduction. It is thought that the PMOSFET of this kind of type has enhanced low dose rate sensitivity (ELDRS) effect. The PMOSFETs threshold voltage does not recover at room annealing after high dose rate exposure and continues the negative drifting, which is due to the radiation-induced interface traps buildup. The annealing temperature is higher, the threshold voltage return drift is more obvious. Zero bias is the worst bias condition. (authors)

  4. Estimation of terrestrial air-absorbed dose rate from the data of regional geochemistry database

    International Nuclear Information System (INIS)

    This paper presents an estimation of air-absorbed dose rate from the data of K2O, U and Th content from Chinese regional geochemical database. A total of 421 group original data of combined samples in Zhongshan City (ZSC), Guangdong Province and south China were extracted from the national geochemical database. Estimated average value of air-absorbed dose rate is 139.4 nGy h-1 in the granite area and 73.7 nGy h-1 in the sedimentary area. The level of air-absorbed dose rate is closely related with the surface lithology. Estimated mean air-absorbed dose rate approximates to the measured average value by a portable plastic scintillator dosemeter in Zhuhai City were bordered with ZSC. The results show that the pre-evaluation of ionizing radiation level using regional geochemical data is feasible. (author)

  5. Calculation of dose-rate conversion factors for external exposure to photons and electrons

    International Nuclear Information System (INIS)

    Methods are presented for the calculation of dose-rate conversion factors for external exposure to photon and electron radiation from radioactive decay. A dose-rate conversion factor is defined as the dose-equivalent rate per unit radionuclide concentration. Exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation from a contaminated ground surface. For each radiation type and exposure mode, dose-rate conversion factors are derived for tissue-equivalent material at the body surface of an exposed individual. In addition, photon dose-rate conversion factors are estimated for 22 body organs. The calculations are based on the assumption that the exposure medium is infinite in extent and that the radionuclide concentration is uniform. The dose-rate conversion factors for immersion in contaminated air and water then follow from the requirement that all of the energy emitted in the radioactive decay is absorbed in the infinite medium. Dose-rate conversion factors for ground-surface exposure are calculated at a reference location above a smooth, infinite plane using the point-kernel integration method and known specific absorbed fractions for photons and electrons in air

  6. Health effects in residents of high background radiation regions

    International Nuclear Information System (INIS)

    Studies carried out in various countries and by the World Health Organization on health effects of exposure of populations to high levels of natural background radiation result in observations of different significance. There are indications of changes in chromosome aberration rate; Down's syndrome has been observed to be possibly related to radiation exposure; malignant neoplasms in bone apparently correspond to high concentrations of 226Ra in drinking water. Although various researchers have looked for them, effects have not been demonstrated regarding cancer mortality (other than malignant neoplasms involving bone), gross congenital abnormalities, fertility index, growth and development, hereditary disease (other than the possibility of Down's syndrome), infant mortality, longevity, multiple births, sex ratio, or spontaneous abortion rate. On the basis of reported data clear quantitative conception of the risk of low-level radiation from natural sources could not be developed and feasibility studies of further epidemiological programmes should be organized. The possibility of reducing the collective population dose from natural sources could be further explored and a basis for necessary legal action on establishment of standards for possible sources of natural radiation, such as building materials, fertilizers, natural gas and water, might be developed. (author)

  7. Radiative corrections in QED in a Lorentz violating background1

    International Nuclear Information System (INIS)

    Radiative corrections in Lorentz violating extensions of QED have received considerable attention in the last years. In this talk I will address the case of fermions coupled to a constant background axial-vector and analise both classical and quantum aspects which prove to be relevant for the consistence of the theory. The modification of the mass-shell conditions in the free theory allows to determine bounds on the fermions' momenta which in turns determines the domain of integration for radiative corrections. We consider this to render the theory free of ambiguities, rather than formal arguments which may lack foundation in this context. Also, the appearance of an anomalous loss of gauge invariance and the role of finite temperature are discussed.

  8. Cosmic Rays Induced Background Radiation on Board of Commercial Flights