Science.gov

Sample records for radiation dose avoided

  1. Value of public health and safety actions and radiation dose avoided

    SciTech Connect

    Baum, J.W.

    1994-05-01

    The values judged best to reflect the willingness of society to pay for the avoidance or reduction of risk were deduced from studies of costs of health care, transportation safety, consumer product safety, government agency actions, wage-risk compensation, consumer behavior (market) studies, and willingness-to-pay surveys. The results ranged from $1,400,000 to $2,700,000 per life saved. Applying the mean of these values ($2,100,000) and the latest risk per unit dose coefficients used by the ICRP (1991), which take into account risks to the general public, including genetic effects and nonfatal cancers, yields a value of dose avoided of $750 to $1,500 per person-cSv for public exposures. The lower value applies if adjustments are made for years of life lost per fatality. A nominal value of $1,000 per person-cSv seems appropriate in light of the many uncertainties involved in deducing these values. These values are consistent with values recommended by several European countries for individual doses in the region of 1 mSv/y (100 mrem/y). Below this dose rate, most countries have values a factor of 7 to 10 lower, based on the assumption that society is less concerned with fatality risks below about 10{sup {minus}4}/y.

  2. Prenatal radiation exposure: dose calculation.

    PubMed

    Scharwächter, C; Röser, A; Schwartz, C A; Haage, P

    2015-05-01

    The unborn child requires special protection. In this context, the indication for an X-ray examination is to be checked critically. If thereupon radiation of the lower abdomen including the uterus cannot be avoided, the examination should be postponed until the end of pregnancy or alternative examination techniques should be considered. Under certain circumstances, either accidental or in unavoidable cases after a thorough risk assessment, radiation exposure of the unborn may take place. In some of these cases an expert radiation hygiene consultation may be required. This consultation should comprise the expected risks for the unborn while not perturbing the mother or the involved medical staff. For the risk assessment in case of an in-utero x-ray exposition deterministic damages with a defined threshold dose are distinguished from stochastic damages without a definable threshold dose. The occurrence of deterministic damages depends on the dose and the developmental stage of the unborn at the time of radiation. To calculate the risks of an in-utero radiation exposure a three-stage concept is commonly applied. Depending on the amount of radiation, the radiation dose is either estimated, roughly calculated using standard tables or, in critical cases, accurately calculated based on the individual event. The complexity of the calculation thereby increases from stage to stage. An estimation based on stage one is easily feasible whereas calculations based on stages two and especially three are more complex and often necessitate execution by specialists. This article demonstrates in detail the risks for the unborn child pertaining to its developmental phase and explains the three-stage concept as an evaluation scheme. It should be noted, that all risk estimations are subject to considerable uncertainties. • Radiation exposure of the unborn child can result in both deterministic as well as stochastic damage und hitherto should be avoided or reduced to a minimum

  3. Radiation: Doses, Effects, Risks.

    ERIC Educational Resources Information Center

    Lean, Geoffrey, Ed.

    Few scientific issues arouse as much public controversy as the effects of radiation. This booklet is an attempt to summarize what is known about radiation and provide a basis for further discussion and debate. The first four chapters of the booklet are based on the most recent reports to the United Nations' General Assembly by the United Nations…

  4. Radiation for Hodgkin's Lymphoma in Young Female Patients: A New Technique to Avoid the Breasts and Decrease the Dose to the Heart

    SciTech Connect

    Dabaja, Bouthaina S.; Rebueno, Neal C.S.; Mazloom, Ali; Thorne, Scott; Perrin, Kelly J.; Tolani, Naresh; Das, Pragnan; Delclos, Marc E.; Iyengar, Puneeth; Reed, Valerie K.; Horace, Patrecia; Salehpour, Mohammad R.

    2011-02-01

    Purpose: To demonstrate how, in young female patients with Hodgkin's lymphoma, using an inclined board technique can further decrease the volume of breasts and heart in the treatment field. Methods and Materials: An inclined board was constructed with the ability to mount an Aquaplast face mask, a Vacu-Lock, and a hip stopper. Eight female patients with early-stage Hodgkin's lymphoma were planned and compared using the conventional flat position and the inclined board position. All patients on the inclined board were planned with 90{sup o} degree table position and 15{sup o} gantry angle rotation to compensate for the beam divergence resulting from the patient's position on the inclined board. Dose-volume histograms were generated, as well as the mean V30 and V5 of both breasts and heart using both treatment positions. Results: The mean value of V30 of the right breast, left breast, and heart decreased from 3%, 3%, and 13%, respectively, using the flat position to 0, 0.4%, and 5%, respectively, using the inclined board. The mean value of V5 of the right breast, left breast, and heart decreased from 6%, 13%, and 36%, respectively, using the flat position to 2%, 8%, and 29%, respectively, using the inclined board. Conclusions: Compared with conventional flat positioning, this simple device and technique allows better sparing of the breasts and the heart while maintaining comparable target coverage and total lung dose.

  5. Radiation dose estimates for radiopharmaceuticals

    SciTech Connect

    Stabin, M.G.; Stubbs, J.B.; Toohey, R.E.

    1996-04-01

    Tables of radiation dose estimates based on the Cristy-Eckerman adult male phantom are provided for a number of radiopharmaceuticals commonly used in nuclear medicine. Radiation dose estimates are listed for all major source organs, and several other organs of interest. The dose estimates were calculated using the MIRD Technique as implemented in the MIRDOSE3 computer code, developed by the Oak Ridge Institute for Science and Education, Radiation Internal Dose Information Center. In this code, residence times for source organs are used with decay data from the MIRD Radionuclide Data and Decay Schemes to produce estimates of radiation dose to organs of standardized phantoms representing individuals of different ages. The adult male phantom of the Cristy-Eckerman phantom series is different from the MIRD 5, or Reference Man phantom in several aspects, the most important of which is the difference in the masses and absorbed fractions for the active (red) marrow. The absorbed fractions for flow energy photons striking the marrow are also different. Other minor differences exist, but are not likely to significantly affect dose estimates calculated with the two phantoms. Assumptions which support each of the dose estimates appears at the bottom of the table of estimates for a given radiopharmaceutical. In most cases, the model kinetics or organ residence times are explicitly given. The results presented here can easily be extended to include other radiopharmaceuticals or phantoms.

  6. Atmospheric radiation flight dose rates

    NASA Astrophysics Data System (ADS)

    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.

  7. EXOMARS IRAS (DOSE) radiation measurements.

    NASA Astrophysics Data System (ADS)

    Federico, C.; Di Lellis, A. M.; Fonte, S.; Pauselli, C.; Reitz, G.; Beaujean, R.

    The characterization and the study of the radiations on their interaction with organic matter is of great interest in view of the human exploration on Mars. The Ionizing RAdiation Sensor (IRAS) selected in the frame of the ExoMars/Pasteur ESA mission is a lightweight particle spectrometer combining various techniques of radiation detection in space. It characterizes the first time the radiation environment on the Mars surface, and provide dose and dose equivalent rates as precursor information absolutely necessary to develop ways to mitigate the radiation risks for future human exploration on Mars. The Martian radiation levels are much higher than those found on Earth and they are relatively low for space. Measurements on the surface will show if they are similar or not to those seen in orbit (modified by the presence of ``albedo'' neutrons produced in the regolith and by the thin Martian atmosphere). IRAS consists of a telescope based on segmented silicon detectors of about 40\\userk\\milli\\metre\\user;k diameter and 300\\user;k\\micro\\metre\\user;k thickness, a segmented organic scintillator, and of a thermoluminescence dosimeter. The telescope will continuously monitor temporal variation of the particle count rate, the dose rate, particle and LET (Linear Energy Transfer) spectra. Tissue equivalent BC430 scintillator material will be used to measure the neutron dose. Neutrons are selected by a criteria requiring no signal in the anti-coincidence. Last, the passive thermoluminescence dosimeter, based on LiF:Mg detectors, regardless the on board operation timing, will measure the total dose accumulated during the exposure period and due to beta and gamma radiation, with a responsivity very close to that of a human tissue.

  8. Radiation dose measurements in coronary CT angiography

    PubMed Central

    Sabarudin, Akmal; Sun, Zhonghua

    2013-01-01

    Coronary computed tomography (CT) angiography is associated with high radiation dose and this has raised serious concerns in the literature. Awareness of various parameters for dose estimates and measurements of coronary CT angiography plays an important role in increasing our understanding of the radiation exposure to patients, thus, contributing to the implementation of dose-saving strategies. This article provides an overview of the radiation dose quantity and its measurement during coronary CT angiography procedures. PMID:24392190

  9. Potential radiation doses from 1994 Hanford Operations

    SciTech Connect

    Soldat, J.K.; Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the potential radiation doses to the public from releases originating at the Hanford Site. Members of the public are potentially exposed to low-levels of radiation from these effluents through a variety of pathways. The potential radiation doses to the public were calculated for the hypothetical MEI and for the general public residing within 80 km (50 mi) of the Hanford Site.

  10. Occupational radiation doses during interventional procedures

    NASA Astrophysics Data System (ADS)

    Nuraeni, N.; Hiswara, E.; Kartikasari, D.; Waris, A.; Haryanto, F.

    2016-03-01

    Digital subtraction angiography (DSA) is a type of fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a bony or dense soft tissue environment. The use of DSA procedures has been increased quite significantly in the Radiology departments in various cities in Indonesia. Various reports showed that both patients and medical staff received a noticeable radiation dose during the course of this procedure. A study had been carried out to measure these doses among interventionalist, nurse and radiographer. The results show that the interventionalist and the nurse, who stood quite close to the X-ray beams compared with the radiographer, received radiation higher than the others. The results also showed that the radiation dose received by medical staff were var depending upon the duration and their position against the X-ray beams. Compared tothe dose limits, however, the radiation dose received by all these three medical staff were still lower than the limits.

  11. Avoidance behaviour and anxiety in rats irradiated with a sublethal dose of gamma-rays.

    PubMed

    Tomášová, Lenka; Smajda, B; Bona, M

    2011-12-01

    The aim of this study was to assess, whether a sublethal dose of gamma-rays will influence the avoidance behaviour and anxiety in rats and whether the response to radiation depends on time of day of its application. Adult male Wistar rats were tested in elevated plus-maze, in hot plate test and in the light/dark box in 4 regular intervals during a day. After two weeks the animals were irradiated with a whole-body dose 6 Gy of gamma-rays. One day after irradiation the animals were repeatedly tested in the same way, as before irradiation. In the plus-maze test an increased level of anxiety was established. The irradiation significantly decreased the locomotor activity of rats, but the extent of exploratory and comfortable behaviour were not altered. After irradiation, an elevated aversion to the thermal stimulus was observed in the hot plate test. The effects of radiation were more pronounced in the light period of the day, than in the dark one. No significant differences in aversion to light were detected after irradiation. The obtained results indicate, that sublethal doses of ionizing radiation can markedly influence the reactivity of animals to adverse stimuli, their motoric activity and emotional status, as well.

  12. Radiation dose optimization in thoracic imaging.

    PubMed

    Tack, D

    2010-01-01

    Guidelines for reduction of CT radiation dose were introduced in 1997 and are now more than 12 years old. The process initiated by the European Regulatory authorities to reduce the excess of radiation from CT has however not produced the expected results. Reference diagnostic levels (DRL) from surveys are still twice as high as needed in most European countries and were not significantly reduced as compared to the initial European ones. Many factors may at least explain partially the lack of dose reduction. One of them is the complexity of the dose optimization process while maintaining image quality at a diagnostically acceptable level. Chest is an anatomical region where radiation dose could be substantially reduced because of high natural contrasts between structures, such as air in the lungs and fat in the mediastinum. In this article, the concept of CT radiation dose optimization and the factors that contribute to maintain global excess in radiation dose are reviewed and a brief summary of results from research in the field of chest CT radiation dose is given.

  13. Radiation dose to the global flying population.

    PubMed

    Alvarez, Luis E; Eastham, Sebastian D; Barrett, Steven R H

    2016-03-01

    Civil airliner passengers and crew are exposed to elevated levels of radiation relative to being at sea level. Previous studies have assessed the radiation dose received in particular cases or for cohort studies. Here we present the first estimate of the total radiation dose received by the worldwide civilian flying population. We simulated flights globally from 2000 to 2013 using schedule data, applying a radiation propagation code to estimate the dose associated with each flight. Passengers flying in Europe and North America exceed the International Commission on Radiological Protection annual dose limits at an annual average of 510 or 420 flight hours per year, respectively. However, this falls to 160 or 120 h on specific routes under maximum exposure conditions.

  14. Gamma Radiation Doses In Sweden

    SciTech Connect

    Almgren, Sara; Isaksson, Mats; Barregaard, Lars

    2008-08-07

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  15. Low-dose radiation exposure and carcinogenesis.

    PubMed

    Suzuki, Keiji; Yamashita, Shunichi

    2012-07-01

    Absorption of energy from ionizing radiation by the genetic material in the cell leads to damage to DNA, which in turn leads to cell death, chromosome aberrations and gene mutations. While early or deterministic effects result from organ and tissue damage caused by cell killing, latter two are considered to be involved in the initial events that lead to the development of cancer. Epidemiological studies have demonstrated the dose-response relationships for cancer induction and quantitative evaluations of cancer risk following exposure to moderate to high doses of low-linear energy transfer radiation. A linear, no-threshold model has been applied to assessment of the risks resulting from exposure to moderate and high doses of ionizing radiation; however, a statistically significant increase has hardly been described for radiation doses below 100 mSv. This review summarizes our current knowledge of the physical and biological features of low-dose radiation and discusses the possibilities of induction of cancer by low-dose radiation.

  16. Radiation Dose from Reentrant Electrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G.D.; Cleghorn, T. E.; Watts, J.

    2003-01-01

    In estimating the crew exposures during an EVA, the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more than 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO.

  17. The Dose Response Relationship for Radiation Carcinogenesis

    NASA Astrophysics Data System (ADS)

    Hall, Eric

    2008-03-01

    Recent surveys show that the collective population radiation dose from medical procedures in the U.S. has increased by 750% in the past two decades. It would be impossible to imagine the practice of medicine today without diagnostic and therapeutic radiology, but nevertheless the widespread and rapidly increasing use of a modality which is a known human carcinogen is a cause for concern. To assess the magnitude of the problem it is necessary to establish the shape of the dose response relationship for radiation carcinogenesis. Information on radiation carcinogenesis comes from the A-bomb survivors, from occupationally exposed individuals and from radiotherapy patients. The A-bomb survivor data indicates a linear relationship between dose and the risk of solid cancers up to a dose of about 2.5 Sv. The lowest dose at which there is a significant excess cancer risk is debatable, but it would appear to be between 40 and 100 mSv. Data from the occupation exposure of nuclear workers shows an excess cancer risk at an average dose of 19.4 mSv. At the other end of the dose scale, data on second cancers in radiotherapy patients indicates that cancer risk does not continue to rise as a linear function of dose, but tends towards a plateau of 40 to 60 Gy, delivered in a fractionated regime. These data can be used to estimate the impact of diagnostic radiology at the low dose end of the dose response relationship, and the impact of new radiotherapy modalities at the high end of the dose response relationship. In the case of diagnostic radiology about 90% of the collective population dose comes from procedures (principally CT scans) which involve doses at which there is credible evidence of an excess cancer incidence. While the risk to the individual is small and justified in a symptomatic patient, the same is not true of some screening procedures is asymptomatic individuals, and in any case the huge number of procedures must add up to a potential public health problem. In the

  18. Radiation Dose from Cigarette Tobacco

    NASA Astrophysics Data System (ADS)

    Papastefanou, C.

    2008-08-01

    The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as 226Ra and 210Pb of the uranium series and 228Ra of the thorium series and/or man-made produced radionuclides, such as 137Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for 226Ra varied from 42.5 to 178.6 μSv y-1 (average 79.7 μSv y-1), while for 228Ra from 19.3 to 116.0 μSv y-1 (average 67.1 μSv y-1) and for 210Pb from 47.0 to 134.9 μSv y-1 (average 104.7 μSv y-1), that is the same order of magnitude for each radionuclide. The sum of the effective dose of the three natural radionuclides varied from 151.9 to 401.3 μSv y-1 (average 251.5 μSv y-1). The annual effective dose from 137Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y-1 (average 199.3 nSv y-1).

  19. Radiation dose from cigarette tobacco

    SciTech Connect

    Papastefanou, C.

    2008-08-07

    The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as {sup 226}Ra and {sup 210}Pb of the uranium series and {sup 228}Ra of the thorium series and/or man-made produced radionuclides, such as {sup 137}Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for {sup 226}Ra varied from 42.5 to 178.6 {mu}Sv y{sup -1} (average 79.7 {mu}Sv y{sup -1}), while for {sup 228}Ra from 19.3 to 116.0 {mu}Sv y{sup -1} (average 67.1 {mu}Sv y{sup -1}) and for {sup 210}Pb from 47.0 to 134.9 {mu}Sv y{sup -1} (average 104.7 {mu}Sv y{sup -1}), that is the same order of magnitude for each radionuclide. The sum of the effective dose of the three natural radionuclides varied from 151.9 to 401.3 {mu}Sv y{sup -1} (average 251.5 {mu}Sv y{sup -1}). The annual effective dose from {sup 137}Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y{sup -1} (average 199.3 nSv y{sup -1})

  20. Mapping of cosmic radiation dose in Croatia.

    PubMed

    Poje, M; Vuković, B; Radolić, V; Miklavčić, I; Faj, D; Varga Pajtler, M; Planinić, J

    2012-01-01

    The Earth is continually bombarded by high-energy particles coming from the outer space and the sun. These particles, termed cosmic radiation, interact with nuclei of atmospheric constituents and decrease in intensity with depth in the atmosphere. Measurements of photon and gamma radiation, performed with a Radiameter at 1 m above the ground, indicated dose rates of 50-100 nSv/h. The neutron dose rate was measured with the CR-39 track etch detector calibrated by the CERN-EU high-energy Reference Field (CERF) facility. Correlation between neutron dose rates and altitudes at 36 sites was examined in order to obtain a significant positive correlation coefficient; the resulting linear regression enabled estimation of a neutron dose at particular altitude. The measured neutron dose rate in Osijek (altitude of 89 m, latitude of 45.31° N) was 110 nSv/h.

  1. [Fetus radiation doses from nuclear medicine and radiology diagnostic procedures. Potential risks and radiation protection instructions].

    PubMed

    Markou, Pavlos

    2007-01-01

    Although in pregnancy it is strongly recommended to avoid diagnostic nuclear medicine and radiology procedures, in cases of clinical necessity or when pregnancy is not known to the physician, these diagnostic procedures are to be applied. In such cases, counseling based on accurate information and comprehensive discussion about the risks of radiation exposure to the fetus should follow. In this article, estimations of the absorbed radiation doses due to nuclear medicine and radiology diagnostic procedures during the pregnancy and their possible risk effects to the fetus are examined and then discussed. Stochastic and detrimental effects are evaluated with respect to other risk factors and related to the fetus absorbed radiation dose and to the post-conception age. The possible termination of a pregnancy, due to radiation exposure is discussed. Special radiation protection instructions are given for radiation exposures in cases of possible, confirmed or unknown pregnancies. It is concluded that nuclear medicine and radiology diagnostic procedures, if not repeated during the pregnancy, are rarely an indication for the termination of pregnancy, because the dose received by the fetus is expected to be less than 100 mSv, which indicates the threshold dose for having deterministic effects. Therefore, the risk for the fetus due to these diagnostic procedures is low. However, stochastic effects are still possible but will be minimized if the radiation absorbed dose to the fetus is kept as low as possible.

  2. Wide-range radiation dose monitor

    DOEpatents

    Kopp, Manfred K.

    1986-01-01

    A radiation dose-rate monitor is provided which operates in a conventional linear mode for radiation in the 0 to 0.5 R/h range and utilizes a nonlinear mode of operation for sensing radiation from 0.5 R/h to over 500 R/h. The nonlinear mode is achieved by a feedback circuit which adjusts the high voltage bias of the proportional counter, and hence its gas gain, in accordance with the amount of radiation being monitored. This allows compression of readout onto a single scale over the range of 0 to greater than 500 R/h without scale switching operations.

  3. Wide-range radiation dose monitor

    DOEpatents

    Kopp, M.K.

    1984-09-20

    A radiation dose-rate monitor is provided which operates in a conventional linear mode for radiation in the 0 to 0.5 R/h range and utilizes a nonlinear mode of operation for sensing radiation from 0.5 R/h to over 500 R/h. The nonlinear mode is achieved by a feedback circuit which adjusts the high voltage bias of the proportional counter, and hence its gas gain, in accordance with the amount of radiation being monitored. This allows compression of readout onto a single scale over the range of 0 to greater than 500 R/h without scale switching operations.

  4. Biodosimetry and assessment of radiation dose

    PubMed Central

    Crespo, Rafael Herranz; Domene, Mercedes Moreno; Rodríguez, María Jesús Prieto

    2011-01-01

    Aim When investigating radiation accidents, it is very important to determine the exposition dose to the individuals. In the case of exposures over 1 Gy, clinicians may expect deterministic effects arising the following weeks and months, in these cases dose estimation will help physicians in the planning of therapy. Nevertheless, for doses below 1 Gy, biodosimetry data are important due to the risk of developing late stochastic effects. Finally, some accidental overexposures are lack of physical measurements and the only way of quantifying dose is by biological dosimetry. Background The analysis of chromosomal aberrations by different techniques is the most developed method of quantifying dose to individuals exposed to ionising radiations.1,2 Furthermore, the analysis of dicentric chromosomes observed in metaphases from peripheral lymphocytes is the routine technique used in case of acute exposures to assess radiation doses. Materials and methods Solid stain of chromosomes is used to determine dicentric yields for dose estimation. Fluorescence in situ hybridization (FISH) for translocations analysis is used when delayed sampling or suspected chronically irradiation dose assessment. Recommendations in technical considerations are based mainly in the IAEA Technical Report No. 405.2 Results Experience in biological dosimetry at Gregorio Marañón General Hospital is described, including own calibration curves used for dose estimation, background studies and real cases of overexposition. Conclusion Dose assessment by biological dosimeters requires a large previous standardization work and a continuous update. Individual dose assessment involves high qualification professionals and its long time consuming, therefore requires specific Centres. For large mass casualties cooperation among specialized Institutions is needed. PMID:24376970

  5. Dosimetric comparison of IMRT rectal and anal canal plans generated using an anterior dose avoidance structure

    SciTech Connect

    Leicher, Brian; Day, Ellen; Colonias, Athanasios; Gayou, Olivier

    2014-10-01

    To describe a dosimetric method using an anterior dose avoidance structure (ADAS) during the treatment planning process for intensity-modulated radiation therapy (IMRT) for patients with anal canal and rectal carcinomas. A total of 20 patients were planned on the Elekta/CMS XiO treatment planning system, version 4.5.1 (Maryland Heights MO) with a superposition algorithm. For each patient, 2 plans were created: one employing an ADAS (ADAS plan) and the other replanned without an ADAS (non-ADAS plan). The ADAS was defined to occupy the volume between the inguinal nodes and primary target providing a single organ at risk that is completely outside of the target volume. Each plan used the same beam parameters and was analyzed by comparing target coverage, overall plan dose conformity using a conformity number (CN) equation, bowel dose-volume histograms, and the number of segments, daily treatment duration, and global maximum dose. The ADAS and non-ADAS plans were equivalent in target coverage, mean global maximum dose, and sparing of small bowel in low-dose regions (5, 10, 15, and 20 Gy). The mean difference between the CN value for the non-ADAS plans and ADAS plans was 0.04 ± 0.03 (p < 0.001). The mean difference in the number of segments was 15.7 ± 12.7 (p < 0.001) in favor of ADAS plans. The ADAS plan delivery time was shorter by 2.0 ± 1.5 minutes (p < 0.001) than the non-ADAS one. The ADAS has proven to be a powerful tool when planning rectal and anal canal IMRT cases with critical structures partially contained inside the target volume.

  6. Dosimetric comparison of IMRT rectal and anal canal plans generated using an anterior dose avoidance structure.

    PubMed

    Leicher, Brian; Day, Ellen; Colonias, Athanasios; Gayou, Olivier

    2014-01-01

    To describe a dosimetric method using an anterior dose avoidance structure (ADAS) during the treatment planning process for intensity-modulated radiation therapy (IMRT) for patients with anal canal and rectal carcinomas. A total of 20 patients were planned on the Elekta/CMS XiO treatment planning system, version 4.5.1 (Maryland Heights MO) with a superposition algorithm. For each patient, 2 plans were created: one employing an ADAS (ADAS plan) and the other replanned without an ADAS (non-ADAS plan). The ADAS was defined to occupy the volume between the inguinal nodes and primary target providing a single organ at risk that is completely outside of the target volume. Each plan used the same beam parameters and was analyzed by comparing target coverage, overall plan dose conformity using a conformity number (CN) equation, bowel dose-volume histograms, and the number of segments, daily treatment duration, and global maximum dose. The ADAS and non-ADAS plans were equivalent in target coverage, mean global maximum dose, and sparing of small bowel in low-dose regions (5, 10, 15, and 20 Gy). The mean difference between the CN value for the non-ADAS plans and ADAS plans was 0.04 ± 0.03 (p < 0.001). The mean difference in the number of segments was 15.7 ± 12.7 (p < 0.001) in favor of ADAS plans. The ADAS plan delivery time was shorter by 2.0 ± 1.5 minutes (p < 0.001) than the non-ADAS one. The ADAS has proven to be a powerful tool when planning rectal and anal canal IMRT cases with critical structures partially contained inside the target volume.

  7. Epigenomic Adaptation to Low Dose Radiation

    SciTech Connect

    Gould, Michael N.

    2015-06-30

    The overall hypothesis of this grant application is that the adaptive responses elicited by low dose ionizing radiation (LDIR) result in part from heritable DNA methylation changes in the epigenome. In the final budget period at the University of Wisconsin-Madison, we will specifically address this hypothesis by determining if the epigenetically labile, differentially methylated regions (DMRs) that regulate parental-specific expression of imprinted genes are deregulated in agouti mice by low dose radiation exposure during gestation. This information is particularly important to ascertain given the 1) increased human exposure to medical sources of radiation; 2) increased number of people predicted to live and work in space; and 3) enhanced citizen concern about radiation exposure from nuclear power plant accidents and terrorist ‘dirty bombs.’

  8. Imaging of Radiation Dose for Stereotactic Radiosurgery

    SciTech Connect

    Guan, Timothy Y.; Almond, Peter R.; Park, Hwan C.; Lindberg, Robert D.; Shields, Christopher B.

    2015-01-15

    The distributions of radiation dose for stereotactic radiosurgery, using a modified linear accelerator (Philips SL-25 and SRS-200), have been studied by using three different dosimeters: (1) ferrous-agarose-xylenol orange (FAX) gels, (2) TLD, and (3) thick-emulsion GafChromic dye film. These dosimeters were loaded into a small volume of defect in a phantom head. A regular linac stereotactic radiosurgery treatment was then given to the phantom head for each type of dosimeter. The measured radiation dose and its distributions were found to be in good agreement with those calculated by the treatment planning computer.

  9. Overestimation of carboplatin doses is avoided by radionuclide GFR measurement

    PubMed Central

    Craig, A J; Samol, J; Heenan, S D; Irwin, A G; Britten, A

    2012-01-01

    Background: Glomerular filtration rate (GFR) is used in the calculation of carboplatin dose. Glomerular filtration rate is measured using a radioisotope method (radionuclide GFR (rGFR)), however, estimation equations are available (estimated GFR (eGFR)). Our aim was to assess the accuracy of three eGFR equations and the subsequent carboplatin dose in an oncology population. Patients and methods: Patients referred for an rGFR over a 3-year period were selected; eGFR was calculated using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft-Gault (CG) equations. Carboplatin doses were calculated for those patients who had received carboplatin chemotherapy. Bias, precision and accuracy were examined. Results: Two hundred and eighty-eight studies met the inclusion/exclusion criteria. Paired t-tests showed significant differences for all three equations between rGFR and eGFR with biases of 12.3 (MDRD), 13.6 (CKD-EPI) and 7.7 ml min−1 per 1.73 m2 (CG). An overestimation in carboplatin dose was seen in 81%, 87% and 66% of studies using the MDRD, CKD-EPI and CG equations, respectively. Conclusion: The MDRD and CKD-EPI equations performed poorly compared with the reference standard rGFR; the CG equation showed smaller bias and higher accuracy in our oncology population. On the basis of our results we recommend that the rGFR should be used for accurate carboplatin chemotherapy dosing and where unavailable the use of the CG equation is preferred. PMID:22935580

  10. Radiation Leukemogenesis at Low Dose Rates

    SciTech Connect

    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.

  11. Radiation-induced genomic instability: radiation quality and dose response

    NASA Technical Reports Server (NTRS)

    Smith, Leslie E.; Nagar, Shruti; Kim, Grace J.; Morgan, William F.

    2003-01-01

    Genomic instability is a term used to describe a phenomenon that results in the accumulation of multiple changes required to convert a stable genome of a normal cell to an unstable genome characteristic of a tumor. There has been considerable recent debate concerning the importance of genomic instability in human cancer and its temporal occurrence in the carcinogenic process. Radiation is capable of inducing genomic instability in mammalian cells and instability is thought to be the driving force responsible for radiation carcinogenesis. Genomic instability is characterized by a large collection of diverse endpoints that include large-scale chromosomal rearrangements and aberrations, amplification of genetic material, aneuploidy, micronucleus formation, microsatellite instability, and gene mutation. The capacity of radiation to induce genomic instability depends to a large extent on radiation quality or linear energy transfer (LET) and dose. There appears to be a low dose threshold effect with low LET, beyond which no additional genomic instability is induced. Low doses of both high and low LET radiation are capable of inducing this phenomenon. This report reviews data concerning dose rate effects of high and low LET radiation and their capacity to induce genomic instability assayed by chromosomal aberrations, delayed lethal mutations, micronuclei and apoptosis.

  12. Methods of calculating radiation absorbed dose.

    PubMed

    Wegst, A V

    1987-01-01

    The new tumoricidal radioactive agents being developed will require a careful estimate of radiation absorbed tumor and critical organ dose for each patient. Clinical methods will need to be developed using standard imaging or counting instruments to determine cumulated organ activities with tracer amounts before the therapeutic administration of the material. Standard MIRD dosimetry methods can then be applied.

  13. Low-dose radiation and leukemia

    SciTech Connect

    Linos, A.; Gray, J.E.; Orvis, A.L.; Kyle, R.A.; O'Fallon, W.M.; Kurland, L.T.

    1980-05-15

    We investigated the effect of diagnostic and low-level therapeutic radiation (less than 300 rads to bone marrow) on the development of leukemia. During this study, 138 patients with leukemia (representing all known incidence cases of leukemia in residents of Olmsted County, Minnesota, between 1955 and 1974) were each matched with two controls, and the lifelong experiences of both groups with regard to diagnostic and therapeutic radiation were ascertained. No statistically significant increase was found in the risk of developing leukemia after radiation doses of 0 to 300 rads (3 Gy) to the bone marrow when these amounts were administered in small doses over long periods of time, as in routine medical care.

  14. 10 CFR 20.1004 - Units of radiation dose.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Units of radiation dose. 20.1004 Section 20.1004 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION General Provisions § 20.1004 Units of radiation dose. (a) Definitions. As used in this part, the units of radiation dose are:...

  15. 10 CFR 20.1004 - Units of radiation dose.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Units of radiation dose. 20.1004 Section 20.1004 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION General Provisions § 20.1004 Units of radiation dose. (a) Definitions. As used in this part, the units of radiation dose are:...

  16. 10 CFR 20.1004 - Units of radiation dose.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Units of radiation dose. 20.1004 Section 20.1004 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION General Provisions § 20.1004 Units of radiation dose. (a) Definitions. As used in this part, the units of radiation dose are:...

  17. 10 CFR 20.1004 - Units of radiation dose.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Units of radiation dose. 20.1004 Section 20.1004 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION General Provisions § 20.1004 Units of radiation dose. (a) Definitions. As used in this part, the units of radiation dose are:...

  18. 10 CFR 20.1004 - Units of radiation dose.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Units of radiation dose. 20.1004 Section 20.1004 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION General Provisions § 20.1004 Units of radiation dose. (a) Definitions. As used in this part, the units of radiation dose are:...

  19. Estimated radiation dose from timepieces containing tritium

    SciTech Connect

    McDowell-Boyer, L M

    1980-01-01

    Luminescent timepieces containing radioactive tritium, either in elemental form or incorporated into paint, are available to the general public. The purpose of this study was to estimate potential radiation dose commitments received by the public annually as a result of exposure to tritium which may escape from the timepieces during their distribution, use, repair, and disposal. Much uncertainty is associated with final dose estimates due to limitations of empirical data from which exposure parameters were derived. Maximum individual dose estimates were generally less than 3 ..mu..Sv/yr, but ranged up to 2 mSv under worst-case conditions postulated. Estimated annual collective (population) doses were less than 5 person/Sv per million timepieces distributed.

  20. Agriculture-related radiation dose calculations

    SciTech Connect

    Furr, J.M.; Mayberry, J.J.; Waite, D.A.

    1987-10-01

    Estimates of radiation dose to the public must be made at each stage in the identification and qualification process leading to siting a high-level nuclear waste repository. Specifically considering the ingestion pathway, this paper examines questions of reliability and adequacy of dose calculations in relation to five stages of data availability (geologic province, region, area, location, and mass balance) and three methods of calculation (population, population/food production, and food production driven). Calculations were done using the model PABLM with data for the Permian and Palo Duro Basins and the Deaf Smith County area. Extra effort expended in gathering agricultural data at succeeding environmental characterization levels does not appear justified, since dose estimates do not differ greatly; that effort would be better spent determining usage of food types that contribute most to the total dose; and that consumption rate and the air dispersion factor are critical to assessment of radiation dose via the ingestion pathway. 17 refs., 9 figs., 32 tabs.

  1. Effects of low doses of radiation.

    PubMed

    Fry, R J

    1996-06-01

    This is a brief review of what is known from experimental studies about the effects of low doses of radiation, and approaches that might improve risk estimates are discussed. The dose-response relationships for cancer induction by radiation vary markedly between tissues. The evidence suggests that 1) the induction of the initial events is dependent on the cell type because the size and/or the number of targets and how the cells handle the initial lesions differs between cell types; and 2) there are marked differences among tissues how initial lesions are expressed and proceed to overt cancer. The recent findings about adaptive responses are discussed in the context of what they contribute to our understanding about the response to irradiation. Lastly, the possibility of extending the approach of determining "The probability of causation," which Vic Bond played such an important role in establishing, is raised.

  2. Optical fibres for high radiation dose environments

    NASA Astrophysics Data System (ADS)

    Henschel, H.; Kohn, O.; Schmidt, H. U.; Bawirzanski, E.; Landers, A.

    1994-06-01

    A variety of modern single mode (SM) and graded index (GI) fibres as well as a new pure silica multimode step index (MMSI) fibre with high OH content were irradiated at a Co-60 gamma ray source with a dose rate of approximately = 1.5Gy/s up to a total dose of 10(exp 6)Gy. The radiation-induced loss of all fibres was measured continuously during and after irradiation at discrete wavelengths (approximately = 850, approximately = 1070, approximately = 1300, approximately = 1550nm). With one SM fibre type also the 'breaking stress' before and after irradiation was determined. Radiation-induced losses of approximately less than 5dB/50m (at approximately = 1300nm) were found with some of the SM fibres, whereas the MMSI fibre showed a final induced loss of only 0.5dB/50m at 1070nm wavelength. The breaking stress of the SM fibre increased by about 10%.

  3. Extended range radiation dose-rate monitor

    DOEpatents

    Valentine, Kenneth H.

    1988-01-01

    An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

  4. 42 CFR 81.6 - Use of radiation dose information.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Use of radiation dose information. 81.6 Section 81... Probability of Causation § 81.6 Use of radiation dose information. Determining probability of causation will require the use of radiation dose information provided to DOL by the National Institute for...

  5. 42 CFR 81.6 - Use of radiation dose information.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Use of radiation dose information. 81.6 Section 81... Probability of Causation § 81.6 Use of radiation dose information. Determining probability of causation will require the use of radiation dose information provided to DOL by the National Institute for...

  6. 42 CFR 81.6 - Use of radiation dose information.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Use of radiation dose information. 81.6 Section 81... Probability of Causation § 81.6 Use of radiation dose information. Determining probability of causation will require the use of radiation dose information provided to DOL by the National Institute for...

  7. 42 CFR 81.6 - Use of radiation dose information.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Use of radiation dose information. 81.6 Section 81... Probability of Causation § 81.6 Use of radiation dose information. Determining probability of causation will require the use of radiation dose information provided to DOL by the National Institute for...

  8. 42 CFR 81.6 - Use of radiation dose information.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Use of radiation dose information. 81.6 Section 81... Probability of Causation § 81.6 Use of radiation dose information. Determining probability of causation will require the use of radiation dose information provided to DOL by the National Institute for...

  9. Low Dose Ionizing Radiation Modulates Immune Function

    SciTech Connect

    Nelson, Gregory A.

    2016-01-12

    In order to examine the effects of low dose ionizing radiation on the immune system we chose to examine an amplified adaptive cellular immunity response. This response is Type IV delayed-type hypersensitivity also called contact hypersensitivity. The agent fluorescein isothiocyanate (FITC) is a low molecular weight, lipophilic, reactive, fluorescent molecule that can be applied to the skin where it (hapten) reacts with proteins (carriers) to become a complete antigen. Exposure to FITC leads to sensitization which is easily measured as a hypersensitivity inflammatory reaction following a subsequent exposure to the ear. Ear swelling, eosinophil infiltration, immunoglobulin E production and cytokine secretion patterns characteristic of a “Th2 polarized” immune response are the components of the reaction. The reaction requires successful implementation of antigen processing and presentation by antigen presenting Langerhans cells, communication with naïve T lymphocytes in draining lymph nodes, expansion of activated T cell clones, migration of activated T cells to the circulation, and recruitment of memory T cells, macrophages and eosinophils to the site of the secondary challenge. Using this model our approach was to quantify system function rather than relying only on indirect biomarkers of cell. We measured the FITC-induced hypersensitivity reaction over a range of doses from 2 cGy to 2 Gy. Irradiations were performed during key events or prior to key events to deplete critical cell populations. In addition to quantifying the final inflammatory response, we assessed cell populations in peripheral blood and spleen, cytokine signatures, IgE levels and expression of genes associated with key processes in sensitization and elicitation/recall. We hypothesized that ionizing radiation would produce a biphasic effect on immune system function resulting in an enhancement at low doses and a depression at higher doses and suggested that this transition would occur in the

  10. Ultraviolet radiation therapy and UVR dose models.

    PubMed

    Grimes, David Robert

    2015-01-01

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  11. Ultraviolet radiation therapy and UVR dose models

    SciTech Connect

    Grimes, David Robert

    2015-01-15

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  12. Single dose testosterone administration alleviates gaze avoidance in women with Social Anxiety Disorder.

    PubMed

    Enter, Dorien; Terburg, David; Harrewijn, Anita; Spinhoven, Philip; Roelofs, Karin

    2016-01-01

    Gaze avoidance is one of the most characteristic and persistent social features in people with Social Anxiety Disorder (SAD). It signals social submissiveness and hampers adequate social interactions. Patients with SAD typically show reduced testosterone levels, a hormone that facilitates socially dominant gaze behavior. Therefore we tested as a proof of principle whether single dose testosterone administration can reduce gaze avoidance in SAD. In a double-blind, within-subject design, 18 medication-free female participants with SAD and 19 female healthy control participants received a single dose of 0.5mg testosterone and a matched placebo, at two separate days. On each day, their spontaneous gaze behavior was recorded using eye-tracking, while they looked at angry, happy, and neutral facial expressions. Testosterone enhanced the percentage of first fixations to the eye-region in participants with SAD compared to healthy controls. In addition, SAD patients' initial gaze avoidance in the placebo condition was associated with more severe social anxiety symptoms and this relation was no longer present after testosterone administration. These findings indicate that single dose testosterone administration can alleviate gaze avoidance in SAD. They support theories on the dominance enhancing effects of testosterone and extend those by showing that effects are particularly strong in individuals featured by socially submissive behavior. The finding that this core characteristic of SAD can be directly influenced by single dose testosterone administration calls for future inquiry into the clinical utility of testosterone in the treatment of SAD.

  13. Clinical applications of image guided-intensity modulated radiation therapy (IG-IMRT) for conformal avoidance of normal tissue

    NASA Astrophysics Data System (ADS)

    Gutierrez, Alonso Navar

    2007-12-01

    Recent improvements in imaging technology and radiation delivery have led to the development of advanced treatment techniques in radiotherapy which have opened the door for novel therapeutic approaches to improve the efficacy of radiation cancer treatments. Among these advances is image-guided, intensity modulated radiation therapy (IG-IMRT), in which imaging is incorporated to aid in inter-/intra-fractional target localization and to ensure accurate delivery of precise and highly conformal dose distributions. In principle, clinical implementation of IG-IMRT should improve normal tissue sparing and permit effective biological dose escalation thus widening the radiation therapeutic window and lead to increases in survival through improved local control of primary neoplastic diseases. Details of the development of three clinical applications made possible solely with IG-IMRT radiation delivery techniques are presented: (1) Laparoscopically implanted tissue expander radiotherapy (LITE-RT) has been developed to enhance conformal avoidance of normal tissue during the treatment of intra-abdominopelvic cancers. LITE-RT functions by geometrically displacing surrounding normal tissue and isolating the target volume through the interfractional inflation of a custom-shaped tissue expander throughout the course of treatment. (2) The unique delivery geometry of helical tomotherapy, a novel form of IG-IMRT, enables the delivery of composite treatment plan m which whole brain radiotherapy (WBRT) with hippocampal avoidance, hypothesized to reduce the risk of memory function decline and improve the patient's quality of life, and simultaneously integrated boost to multiple brain metastases to improve intracranial tumor control is achieved. (3) Escalation of biological dose to targets through integrated, selective subvolume boosts have been shown to efficiently increase tumor dose without significantly increasing normal tissue dose. Helical tomotherapy was used to investigate the

  14. Variations of the radiation dose onboard Mir station.

    PubMed

    Panasyuk, M I; Teltsov, M V; Shumshurov, V I; Tsetlin, V V

    1998-01-01

    Dose variations, associated with the 11-year solar activity cycle, seasonal variations of particle fluxes in the Earth's radiation belts at the station orbit, and solar proton events are studied, using prolonged measurements of radiation doses inside orbital station Mir. Daily averages of radiation doses during the declining phase of the 22nd solar cycle and during transition to the 23rd solar activity cycle reached very large values for astronauts and significantly exceed the values calculated according to existing models.

  15. Low-dose radiation epidemiology studies: status and issues.

    PubMed

    Shore, Roy E

    2009-11-01

    Although the Japanese atomic bomb study and radiotherapy studies have clearly documented cancer risks from high-dose radiation exposures, radiation risk assessment groups have long recognized that protracted or low exposures to low-linear energy transfer radiations are key radiation protection concerns because these are far more common than high-exposure scenarios. Epidemiologic studies of human populations with low-dose or low dose-rate exposures are one approach to addressing those concerns. A number of large studies of radiation workers (Chernobyl clean-up workers, U.S. and Chinese radiological technologists, and the 15-country worker study) or of persons exposed to environmental radiation at moderate to low levels (residents near Techa River, Semipalatinsk, Chernobyl, or nuclear facilities) have been conducted. A variety of studies of medical radiation exposures (multiple-fluoroscopy, diagnostic (131)I, scatter radiation doses from radiotherapy, etc.) also are of interest. Key results from these studies are summarized and compared with risk estimates from the Japanese atomic bomb study. Ideally, one would like the low-dose and low dose-rate studies to guide radiation risk estimation regarding the shape of the dose-response curve, DDREF (dose and dose-rate effectiveness factor), and risk at low doses. However, the degree to which low-dose studies can do so is subject to various limitations, especially those pertaining to dosimetric uncertainties and limited statistical power. The identification of individuals who are particularly susceptible to radiation cancer induction also is of high interest in terms of occupational and medical radiation protection. Several examples of studies of radiation-related cancer susceptibility are discussed, but none thus far have clearly identified radiation-susceptible genotypes.

  16. Risk of cancer subsequent to low-dose radiation

    SciTech Connect

    Warren, S.

    1980-01-01

    The author puts low dose irradiation risks in perspective using average background radiation doses for standards. He assailed irresponsible media coverage during the height of public interest in the Three-Mile Island Reactor incident. (PCS)

  17. Measurement and assessment of radiation dose of astronauts in space

    NASA Astrophysics Data System (ADS)

    Zhang, Binquan; Sun, Yue-qiang; Yang, Chuibai; Zhang, Shenyi; Liang, Jinbao

    Astronauts in flight are exposed by the space radiation, which is mainly composed of proton, electron, heavy ion, and neutron. To assess the radiation risk, measurement and assessment of radiation dose of astronauts is indispensable. Especially, measurement for heavy ion radiation is most important as it contributes the major dose. Until now, most of the measurements and assessments of radiation dose of astronauts are based on the LET (Linear Energy Transfer) spectrum of space radiation. However, according to the ICRP Publication 123, energy and charge number of heavy ions should be measured in order to assess space radiation exposure to astronauts. In addition, from the publication, quality factors for each organs or tissues of astronauts are different and they should be calculated or measured independently. Here, a method to measure the energy and charge number of heavy ion and a voxel phantom based on the anatomy of Chinese adult male are presented for radiation dose assessment of astronauts.

  18. Biological-Based Modeling of Low Dose Radiation Risks

    SciTech Connect

    Scott, Bobby R., Ph.D.

    2006-11-08

    The objective of this project was to refine a biological-based model (called NEOTRANS2) for low-dose, radiation-induced stochastic effects taking into consideration newly available data, including data on bystander effects (deleterious and protective). The initial refinement led to our NEOTRANS3 model which has undergone further refinement (e.g., to allow for differential DNA repair/apoptosis over different dose regions). The model has been successfully used to explain nonlinear dose-response curves for low-linear-energy-transfer (LET) radiation-induced mutations (in vivo) and neoplastic transformation (in vitro). Relative risk dose-response functions developed for neoplastic transformation have been adapted for application to cancer relative risk evaluation for irradiated humans. Our low-dose research along with that conducted by others collectively demonstrate the following regarding induced protection associated with exposure to low doses of low-LET radiation: (1) protects against cell killing by high-LET alpha particles; (2) protects against spontaneous chromosomal damage; (3) protects against spontaneous mutations and neoplastic transformations; (4) suppresses mutations induced by a large radiation dose even when the low dose is given after the large dose; (5) suppresses spontaneous and alpha-radiation-induced cancers; (6) suppresses metastasis of existing cancer; (7) extends tumor latent period; (8) protects against diseases other than cancer; and (9) extends life expectancy. These forms of radiation-induced protection are called adapted protection as they relate to induced adaptive response. Thus, low doses and dose rates of low-LET radiation generally protect rather than harm us. These findings invalidate the linear not threshold (LNT) hypothesis which is based on the premise that any amount of radiation is harmful irrespective of its type. The hypothesis also implicates a linear dose-response curve for cancer induction that has a positive slope and no

  19. CARCINOGENIC EFFECTS OF LOW DOSES OF IONIZING RADIATION

    EPA Science Inventory

    Carcinogenic Effects of Low Doses of Ionizing Radiation

    R Julian Preston, Environmental Carcinogenesis Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711

    The form of the dose-response curve for radiation-induced cancers, particu...

  20. Measuring radiation dose to patients undergoing fluoroscopically-guided interventions

    NASA Astrophysics Data System (ADS)

    Lubis, L. E.; Badawy, M. K.

    2016-03-01

    The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiation dose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiation dose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors’ department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiation dose is discussed. Furthermore, advances in real-time patient radiation dose estimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiation dose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

  1. [About Dose-Effect Relationship in the Environment Radiation Protection].

    PubMed

    Udalova, A A

    2015-01-01

    One of the most important stages in the development of a methodology for the environment radiation protection is the assessment and justification of critical radiation exposure levels for ecosystem components. In this study application of the approach for critical dose level estimation is demonstrated on the example of the data about ionizing radiation effect on reproduction and survival of agricultural plants after acute and chronic exposures. Influence of the type of dose-effect relationship on the estimated values of the critical doses and dose rates is studied using three models (linear, logarithmic and logistic). The findings obtained do not provide any robust recommendations in favor of one of the three tested functions. The models of dose-effect relationship (threshold or non-threshold) and types of radiation-induced effects (stochastic and deterministic) are discussed from the viewpoint of developing a system for radiation protection of human and non-human biota.

  2. A Biodosimeter for Multiparametric Determination of Radiation Dose, Radiation Quality, and Radiation Risk

    NASA Technical Reports Server (NTRS)

    Richmond, Robert; Cruz, Angela; Jansen, Heather; Bors, Karen

    2003-01-01

    Predicting risk of human cancer following exposure of an individual or a population to ionizing radiation is challenging. To an approximation, this is because uncertainties of uniform absorption of dose and the uniform processing of dose-related damage at the cellular level within a complex set of biological variables degrade the confidence of predicting the delayed expression of cancer as a relatively rare event. Cellular biodosimeters that simultaneously report: 1) the quantity of absorbed dose after exposure to ionizing radiation, 2) the quality of radiation delivering that dose, and 3) the risk of developing cancer by the cells absorbing that dose would therefore be useful. An approach to such a multiparametric biodosimeter will be reported. This is the demonstration of a dose responsive field effect of enhanced expression of keratin 18 (K18) in cultures of human mammary epithelial cells irradiated with cesium-1 37 gamma-rays. Dose response of enhanced K18 expression was experimentally extended over a range of 30 to 90 cGy for cells evaluated at mid-log phase. K18 has been reported to be a marker for tumor staging and for apoptosis, and thereby serves as an example of a potential marker for cancer risk, where the reality of such predictive value would require additional experimental development. Since observed radiogenic increase in expression of K18 is a field effect, ie., chronically present in all cells of the irradiated population, it may be hypothesized that K18 expression in specific cells absorbing particulate irradiation, such as the high-LET-producing atomic nuclei of space radiation, will report on both the single-cell distributions of those particles amongst cells within the exposed population, and that the relatively high dose per cell delivered by densely ionizing tracks of those intersecting particles will lead to cell-specific high-expression levels of K18, thereby providing analytical end points that may be used to resolve both the quantity and

  3. Helical Electron Avoidance Radiation Therapy (HEART) for Breast Cancer Treatment

    DTIC Science & Technology

    2005-04-01

    3. K. Li, and L. Ma, "Selective Source Blocking for Treatment of Trigeminal Neuralgia Based on Analytical Gamma Knife Dose Modeling", Phys. Med. Biol...radiosurgery of trigeminal neuralgia " Appl. Clin. Med. Phy., Vol 1(4) 116-119, 2000. (2) Major Presentations 1. The 4 th Era of Hope Conference...treatment planning", Med. Phys. 31(2004) No. 6,1824. 4. L. Ma, and K. Li, " Selective source blocking for treatment of trigeminal neuralgia based on

  4. A Bayesian Semiparametric Model for Radiation Dose-Response Estimation.

    PubMed

    Furukawa, Kyoji; Misumi, Munechika; Cologne, John B; Cullings, Harry M

    2016-06-01

    In evaluating the risk of exposure to health hazards, characterizing the dose-response relationship and estimating acceptable exposure levels are the primary goals. In analyses of health risks associated with exposure to ionizing radiation, while there is a clear agreement that moderate to high radiation doses cause harmful effects in humans, little has been known about the possible biological effects at low doses, for example, below 0.1 Gy, which is the dose range relevant to most radiation exposures of concern today. A conventional approach to radiation dose-response estimation based on simple parametric forms, such as the linear nonthreshold model, can be misleading in evaluating the risk and, in particular, its uncertainty at low doses. As an alternative approach, we consider a Bayesian semiparametric model that has a connected piece-wise-linear dose-response function with prior distributions having an autoregressive structure among the random slope coefficients defined over closely spaced dose categories. With a simulation study and application to analysis of cancer incidence data among Japanese atomic bomb survivors, we show that this approach can produce smooth and flexible dose-response estimation while reasonably handling the risk uncertainty at low doses and elsewhere. With relatively few assumptions and modeling options to be made by the analyst, the method can be particularly useful in assessing risks associated with low-dose radiation exposures.

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

    SciTech Connect

    Friend, P.J.

    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.

  6. [Technical parameters to decrease the radiation dose from conventional and digital radiographs].

    PubMed

    Foulquier, J N

    2010-11-01

    Reducing radiation dose while maintaining adequate image quality on conventional and digital radiographs requires optimal use of the unit. Additional filtration avoids unnecessary tissue exposure and improves photon transmission. Automatic exposure control may reduce exposure and dose. The volume of tissue imaged must be limited by the use of diaphragms and shutters or compression. Sensitive detectors with increased photon detection also contribute to reduce dose. Radiographic films combined to rare-earth screens also afford a good photon-conversion efficiency. Large area flat panel amorphous silicon x-ray sensors may also reduce dose up to 50% compared to films. Finally, calculation of the Kerma-area product independent of the source distance constitutes an important indicator of radiation dose.

  7. Radiation dose estimates for copper-64 citrate in man

    SciTech Connect

    Crook, J.E.; Carlton, J.E.; Stabin, M.; Watson, E.

    1985-01-01

    Tumor imaging agents suitable for use with positron emission tomographs are constantly sought. We have performed studies with animal-tumor-bearing models that have demonstrated the rapid uptake of copper-64. The radiation dose estimates for man indicate that the intravenous administration of 7.0 mCi would result in radiation doses to the kidney of 9.8 to 10.5 rads with other organs receiving substantially less radiation. 5 refs., 3 tabs.

  8. Total dose performance of radiation hardened voltage regulators and references

    NASA Technical Reports Server (NTRS)

    McClure, S.; Gorelick, J.; Pease, R.; Rax, B.; Ladbury, R.

    2001-01-01

    Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.

  9. Impact of dose and volume on radiation-induced mucositis.

    PubMed

    Mantini, Giovanna; Manfrida, Stefania; Cellini, Francesco; Giammarino, Daniela; Petrone, Adelina; Vitucci, Pasquale; Cellini, Numa

    2005-01-01

    There is a relationship between a given radiation dose and the resulting biological effect in the management of head and neck cancer. Radiation mucositis represents a frequent complication in cancer chemoradiation. Its prevention and treatment are major goals in radiation therapy schedules. Critical tissues can be spared using high conformal radiation therapy (3DCRT) based on consensus guidelines for target volume. Current approaches to radiation mucositis with respect to the dose and volume impact are illustrated. The monitoring system of late toxicity used by the authors is presented.

  10. Automated extraction of radiation dose information for CT examinations.

    PubMed

    Cook, Tessa S; Zimmerman, Stefan; Maidment, Andrew D A; Kim, Woojin; Boonn, William W

    2010-11-01

    Exposure to radiation as a result of medical imaging is currently in the spotlight, receiving attention from Congress as well as the lay press. Although scanner manufacturers are moving toward including effective dose information in the Digital Imaging and Communications in Medicine headers of imaging studies, there is a vast repository of retrospective CT data at every imaging center that stores dose information in an image-based dose sheet. As such, it is difficult for imaging centers to participate in the ACR's Dose Index Registry. The authors have designed an automated extraction system to query their PACS archive and parse CT examinations to extract the dose information stored in each dose sheet. First, an open-source optical character recognition program processes each dose sheet and converts the information to American Standard Code for Information Interchange (ASCII) text. Each text file is parsed, and radiation dose information is extracted and stored in a database which can be queried using an existing pathology and radiology enterprise search tool. Using this automated extraction pipeline, it is possible to perform dose analysis on the >800,000 CT examinations in the PACS archive and generate dose reports for all of these patients. It is also possible to more effectively educate technologists, radiologists, and referring physicians about exposure to radiation from CT by generating report cards for interpreted and performed studies. The automated extraction pipeline enables compliance with the ACR's reporting guidelines and greater awareness of radiation dose to patients, thus resulting in improved patient care and management.

  11. The Dose Window for Radiation-Induced Protective Adaptive Responses

    PubMed Central

    Mitchel, Ronald E. J.

    2009-01-01

    Adaptive responses to low doses of low LET radiation occur in all organisms thus far examined, from single cell lower eukaryotes to mammals. These responses reduce the deleterious consequences of DNA damaging events, including radiation-induced or spontaneous cancer and non-cancer diseases in mice. The adaptive response in mammalian cells and mammals operates within a certain window that can be defined by upper and lower dose thresholds, typically between about 1 and 100 mGy for a single low dose rate exposure. However, these thresholds for protection are not a fixed function of total dose, but also vary with dose rate, additional radiation or non-radiation stressors, tissue type and p53 functional status. Exposures above the upper threshold are generally detrimental, while exposures below the lower threshold may or may not increase either cancer or non-cancer disease risk. PMID:20585438

  12. Radiation doses to insertion devices at the Advanced Photon Source

    SciTech Connect

    Moog, E.R.; Den Hartog, P.K.; Semones, E.J.; Job, P.K.

    1997-09-01

    Dose measurements made on and around the insertion devices (IDs) at the Advanced Photon Source are reported. Attempts are made to compare these dose rates to dose rates that have been reported to cause radiation-induced demagnetization, but comparisons are complicated by such factors as the particular magnet material and the techniques used in its manufacture, the spectrum and type of radiation, and the demagnetizing field seen by the magnet. The spectrum of radiation at the IDs. It has almost no effect on the dose to the downstream ends of the IDs, however, since much of the radiation travels through the ID vacuum chamber and cannot be readily shielded. Opening the gaps of the IDs during injection and at other times also helps decrease the radiation exposure.

  13. Patient radiation doses for electron beam CT

    SciTech Connect

    Castellano, Isabel A.; Dance, David R.; Skinner, Claire L.; Evans, Phil M.

    2005-08-15

    A Monte Carlo based computer model has been developed for electron beam computed tomography (EBCT) to calculate organ and effective doses in a humanoid hermaphrodite phantom. The program has been validated by comparison with experimental measurements of the CT dose index in standard head and body CT dose phantoms; agreement to better than 8% has been found. The robustness of the model has been established by varying the input parameters. The amount of energy deposited at the 12:00 position of the standard body CT dose phantom is most susceptible to rotation angle, whereas that in the central region is strongly influenced by the beam quality. The program has been used to investigate the changes in organ absorbed doses arising from partial and full rotation about supine and prone subjects. Superficial organs experience the largest changes in absorbed dose with a change in subject orientation and for partial rotation. Effective doses for typical clinical scan protocols have been calculated and compared with values obtained using existing dosimetry techniques based on full rotation. Calculations which make use of Monte Carlo conversion factors for the scanner that best matches the EBCT dosimetric characteristics consistently overestimate the effective dose in supine subjects by typically 20%, and underestimate the effective dose in prone subjects by typically 13%. These factors can therefore be used to correct values obtained in this way. Empirical dosimetric techniques based on the dose-length product yield errors as great as 77%. This is due to the sensitivity of the dose length product to individual scan lengths. The magnitude of these errors is reduced if empirical dosimetric techniques based on the average absorbed dose in the irradiated volume (CTDI{sub vol}) are used. Therefore conversion factors specific to EBCT have been calculated to convert the CTDI{sub vol} to an effective dose.

  14. SCCT guidelines on radiation dose and dose-optimization strategies in cardiovascular CT.

    PubMed

    Halliburton, Sandra S; Abbara, Suhny; Chen, Marcus Y; Gentry, Ralph; Mahesh, Mahadevappa; Raff, Gilbert L; Shaw, Leslee J; Hausleiter, Jörg

    2011-01-01

    Over the last few years, computed tomography (CT) has developed into a standard clinical test for a variety of cardiovascular conditions. The emergence of cardiovascular CT during a period of dramatic increase in radiation exposure to the population from medical procedures and heightened concern about the subsequent potential cancer risk has led to intense scrutiny of the radiation burden of this new technique. This has hastened the development and implementation of dose reduction tools and prompted closer monitoring of patient dose. In an effort to aid the cardiovascular CT community in incorporating patient-centered radiation dose optimization and monitoring strategies into standard practice, the Society of Cardiovascular Computed Tomography has produced a guideline document to review available data and provide recommendations regarding interpretation of radiation dose indices and predictors of risk, appropriate use of scanner acquisition modes and settings, development of algorithms for dose optimization, and establishment of procedures for dose monitoring.

  15. SCCT guidelines on radiation dose and dose-optimization strategies in cardiovascular CT

    PubMed Central

    Halliburton, Sandra S.; Abbara, Suhny; Chen, Marcus Y.; Gentry, Ralph; Mahesh, Mahadevappa; Raff, Gilbert L.; Shaw, Leslee J.; Hausleiter, Jörg

    2012-01-01

    Over the last few years, computed tomography (CT) has developed into a standard clinical test for a variety of cardiovascular conditions. The emergence of cardiovascular CT during a period of dramatic increase in radiation exposure to the population from medical procedures and heightened concern about the subsequent potential cancer risk has led to intense scrutiny of the radiation burden of this new technique. This has hastened the development and implementation of dose reduction tools and prompted closer monitoring of patient dose. In an effort to aid the cardiovascular CT community in incorporating patient-centered radiation dose optimization and monitoring strategies into standard practice, the Society of Cardiovascular Computed Tomography has produced a guideline document to review available data and provide recommendations regarding interpretation of radiation dose indices and predictors of risk, appropriate use of scanner acquisition modes and settings, development of algorithms for dose optimization, and establishment of procedures for dose monitoring. PMID:21723512

  16. Commentary 2 to Cox and Little: radiation-induced oncogenic transformation: the interplay between dose, dose protraction, and radiation quality

    NASA Technical Reports Server (NTRS)

    Brenner, D. J.; Hall, E. J.

    1992-01-01

    There is now a substantial body of evidence for end points such as oncogenic transformation in vitro, and carcinogenesis and life shortening in vivo, suggesting that dose protraction leads to an increase in effectiveness relative to a single, acute exposure--at least for radiations of medium linear energy transfer (LET) such as neutrons. Table I contains a summary of the pertinent data from studies in which the effect is seen. [table: see text] This phenomenon has come to be known as the "inverse dose rate effect," because it is in marked contrast to the situation at low LET, where protraction in delivery of a dose of radiation, either by fractionation or low dose rate, results in a decreased biological effect; additionally, at medium and high LET, for radiobiological end points such as clonogenic survival, the biological effectiveness is independent of protraction. The quantity and quality of the published reports on the "inverse dose rate effect" leaves little doubt that the effect is real, but the available evidence indicates that the magnitude of the effect is due to a complex interplay between dose, dose rate, and radiation quality. Here, we first summarize the available data on the inverse dose rate effect and suggest that it follows a consistent pattern in regard to dose, dose rate, and radiation quality; second, we describe a model that predicts these features; and, finally, we describe the significance of the effect for radiation protection.

  17. The development of remote wireless radiation dose monitoring system

    SciTech Connect

    Lee, Jin-woo; Jeong, Kyu-hwan; Kim, Jong-il; Im, Chae-wan

    2015-07-01

    Internet of things (IoT) technology has recently shown a large flow of IT trends in human life. In particular, our lives are now becoming integrated with a lot of items around the 'smart-phone' with IoT, including Bluetooth, Near Field Communication (NFC), Beacons, WiFi, and Global Positioning System (GPS). Our project focuses on the interconnection of radiation dosimetry and IoT technology. The radiation workers at a nuclear facility should hold personal dosimeters such as a Thermo-Luminescence Dosimeter (TLD), an Optically Stimulated Luminescence Dosimeter (OSL), pocket ionization chamber dosimeters, an Electronic Personal Dosimeter (EPD), or an alarm dosimeter on their body. Some of them have functions that generate audible or visible alarms to radiation workers in a real working area. However, such devices used in radiation fields these days have no functions for communicating with other areas or the responsible personnel in real time. In particular, when conducting a particular task in a high dose area, or a number of repair works within a radiation field, radiation dose monitoring is important for the health of the workers and the work efficiency. Our project aims at the development of a remote wireless radiation dose monitoring system (RWRD) that can be used to monitor the radiation dose in a nuclear facility for radiation workers and a radiation protection program In this project, a radiation dosimeter is the detection device for personal radiation dose, a smart phone is the mobile wireless communication tool, and, Beacon is the wireless starter for the detection, communication, and position of the worker using BLE (Bluetooth Low Energy). In this report, we report the design of the RWRD and a demonstration case in a real radiation field. (authors)

  18. Microelectronic Chips For Radiation-Dose Tests

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Lin, Yu-Sang; Ray, Kevin P.; Sokoloski, Martin M.

    1993-01-01

    Custom-made single-chip complementary metal-oxide semiconductor (CMOS) integrated circuit designed to reveal effects of ionizing radiation on itself and similar integrated circuits. Potential terrestrial use: safety-oriented monitoring of ionizing radiation at nuclear powerplants, nuclear-waste sites, and the like.

  19. Do changes in biomarkers from space radiation reflect dose or risk?

    NASA Astrophysics Data System (ADS)

    Brooks, A.

    . Following low-LET radiation exposure, the biological response often does not increase as a linear function of dose. Thus, the RBE and the subsequent risk predicted is dependent on the dose where the two radiation types are compared. To avoid this problem the standard procedure is to use the dose and dose-rate response and compare the linear components of the two r diation exposures. Important riska comparisons are often done at very low doses, where the reference radiation may either increase or decrease as a function of dose. Since the low-LET exposure often does not produce a significant change above the background level of damage, the derived RBE factors can become very large.Studies using micronuclei as biomarkers following exposure to mono-energetic neutrons, x-rays and gamma rays delivered at very low doses (up to 0.10 Gy) demonstrated the differences in the shape of each dose-response relationship and the problems associated with the RBE. These studies show that RBE may not accurately reflect the hazards or risk associated with space radiation exposure. As additional measures of biological change are developed, it may become possible to base risk on biological change and not on changes in radiation doses. Research funded through grants # DE-FG03-99ER62787 from DOE Office of Biological and Environmental Research and RO1 CA74053-01 from NIH/NASA to Washington State University Tri-Cities.

  20. Radiation dose measurement for various parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Lae; Kim, Hee-Joung; Jeon, Seong Su; Cho, Hyo-Min; Nam, So Ra; Jung, Ji-Young

    2008-03-01

    The MDCT parameters affecting radiation dose include tube voltage, tube current, change of beam collimation, and size of the human body. The purpose of this study was to measure and evaluate radiation dose for MDCT parameters. A comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber was performed. The ionization chamber was used for measuring radiation dose in the MDCT, as well as of CTDI W according to temperature and pressure correction factors in the CT room. As a result, the patient dose of CTDI W values linearly increased as tube voltage and current were increased, and nonlinearly decreased as beam collimation was increased. And the CTDI W value which was reflected calibration factors, as well as correction factors of temperature and pressure, was found to be greater by the range of 0.479 ~ 3.162 mGy in effective radiation dose than the uncorrected value. Also, Under the abdomen routine CT conditions used in hospitals, patient exposure dose showed a difference of a maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the application of temperature and pressure of the CT room are crucial in measuring and calculating patient exposure dose.

  1. Principles of CT: radiation dose and image quality.

    PubMed

    Goldman, Lee W

    2007-12-01

    This article discusses CT radiation dose, the measurement of CT dose, and CT image quality. The most commonly used dose descriptor is CT dose index, which represents the dose to a location (e.g., depth) in a scanned volume from a complete series of slices. A weighted average of the CT dose index measured at the center and periphery of dose phantoms provides a convenient single-number estimate of patient dose for a procedure, and this value (or a related indicator that includes the scanned length) is often displayed on the operator's console. CT image quality, as in most imaging, is described in terms of contrast, spatial resolution, image noise, and artifacts. A strength of CT is its ability to visualize structures of low contrast in a subject, a task that is limited primarily by noise and is therefore closely associated with radiation dose: The higher the dose contributing to the image, the less apparent is image noise and the easier it is to perceive low-contrast structures. Spatial resolution is ultimately limited by sampling, but both image noise and resolution are strongly affected by the reconstruction filter. As a result, diagnostically acceptable image quality at acceptable doses of radiation requires appropriately designed clinical protocols, including appropriate kilovolt peaks, amperages, slice thicknesses, and reconstruction filters.

  2. Assessment of the effective dose equivalent for external photon radiation

    SciTech Connect

    Reece, W.D.; Poston, J.W.; Xu, X.G. )

    1993-02-01

    Beginning in January 1994, US nuclear power plants must change the way that they determine the radiation exposure to their workforce. At that time, revisions to Title 10 Part 20 of the Code of Federal Regulations will be in force requiring licensees to evaluate worker radiation exposure using a risk-based methodology termed the effective dose equivalent.'' A research project was undertaken to improve upon the conservative method presently used for assessing effective dose equivalent. In this project effective dose equivalent was calculated using a mathematical model of the human body, and tracking photon interactions for a wide variety of radiation source geometries using Monte Carlo computer code simulations. Algorithms were then developed to relate measurements of the photon flux on the surface of the body (as measured by dosimeters) to effective dose equivalent. This report (Volume I of a two-part study) describes: the concept of effective dose equivalent, the evolution of the concept and its incorporation into regulations, the variations in human organ susceptibility to radiation, the mathematical modeling and calculational techniques used, the results of effective dose equivalent calculations for a broad range of photon energiesand radiation source geometries. The study determined that for beam radiation sources the highest effective dose equivalent occurs for beams striking the front of the torso. Beams striking the rear of the torsoproduce the next highest effective dose equivalent, with effective dose equivalent falling significantly as one departs from these two orientations. For point sources, the highest effective dose equivalent occurs when the sources are in contact with the body on the front of the torso. For females the highest effective dose equivalent occurs when the source is on the sternum, for males when it is on the gonads.

  3. Painting Dose: The ART of Radiation.

    PubMed

    Roberts, Hannah J; Zietman, Anthony L; Efstathiou, Jason A

    2016-11-15

    The discovery of X rays in 1895 captivated society like no other scientific advance. Radiation instantly became the subject not only of numerous scientific papers but also of circus bazaars, poetry, fiction, costume design, comics, and marketing for household items. Its spread was "viral." What is not well known, however, is its incorporation into visual art, despite the long tradition of medicine and surgery as a subject in art. Using several contemporary search methods, we identified 5 examples of paintings or sculpture that thematically feature radiation therapy. All were by artists with exhibited careers in art: Georges Chicotot, Marcel Duchamp, David Alfaro Siqueiros, Robert Pope, and Cookie Kerxton. Each artist portrays radiation differently, ranging from traditional healer, to mysterious danger, to futuristic propaganda, to the emotional challenges of undergoing cancer therapy. This range captures the complex role of radiation as both a therapy and a hazard. Whereas some of these artists are now world famous, none of these artworks are as well known as their surgical counterparts. The penetration of radiation into popular culture was rapid and pervasive; yet, its role as a thematic subject in art never fully caught on, perhaps because of a lack of understanding of the technology, radiation's intangibility, or even a suppressive effect of society's ambivalent relationship with it. These 5 artists have established a rich foundation upon which pop culture and art can further develop with time to reflect the extraordinary progress of modern radiation therapy.

  4. KERMA-based radiation dose management system for real-time patient dose measurement

    NASA Astrophysics Data System (ADS)

    Kim, Kyo-Tae; Heo, Ye-Ji; Oh, Kyung-Min; Nam, Sang-Hee; Kang, Sang-Sik; Park, Ji-Koon; Song, Yong-Keun; Park, Sung-Kwang

    2016-07-01

    Because systems that reduce radiation exposure during diagnostic procedures must be developed, significant time and financial resources have been invested in constructing radiation dose management systems. In the present study, the characteristics of an existing ionization-based system were compared to those of a system based on the kinetic energy released per unit mass (KERMA). Furthermore, the feasibility of using the KERMA-based system for patient radiation dose management was verified. The ionization-based system corrected the effects resulting from radiation parameter perturbations in general radiography whereas the KERMA-based system did not. Because of this difference, the KERMA-based radiation dose management system might overestimate the patient's radiation dose due to changes in the radiation conditions. Therefore, if a correction factor describing the correlation between the systems is applied to resolve this issue, then a radiation dose management system can be developed that will enable real-time measurement of the patient's radiation exposure and acquisition of diagnostic images.

  5. Galactic cosmic radiation doses to astronauts outside the magnetosphere

    SciTech Connect

    Letaw, J.R.

    1987-12-06

    The dose and dose equivalent from galactic cosmic radiation outside the magnetosphere were computed. The principal radiation components considered include primary cosmic rays, spallation fragments of the heavy ions, and secondary products (protons, neutrons, alphas, and recoil nuclei) from interactions in tissue. Three mission environments were considered: free space, the lunar surface, and the martian surface. The annual dose equivalents to the blood-forming organs in these environments are approximately 500 mSv, 250 mSv, and 120 mSv, respectively (1 mSv = 0.1 rem). The dose on the lunar surface is one-half of free space because there is only a single hemisphere of exposure. The dose on the martian surface is half again the dose on the moon because of the shielding provided by a thin, carbon dioxide atmosphere. Dose versus aluminum shielding thickness functions have been computed for the free space exposure. Galactic cosmic radiation is energetic and highly penetrating. 30 cm of aluminum shielding reduces the dose equivalent 25% to 40% (depending on the phase of the solar cycle). Aiming for conformity with the draft NCRP annual dose limit for space station crew members, which is 500 mSv/yr, we recommend 7.5 cm of aluminum shielding in all habitable areas of spacecraft designed for long-duration missions outside Earth's magnetosphere. This shielding thickness reduces the galactic cosmic ray dose and diminishes the risk to astronauts from energetic particle events.

  6. Strategies for reduction of radiation dose in cardiac multislice CT.

    PubMed

    Paul, Jean-François; Abada, Hicham T

    2007-08-01

    Because cardiac computed tomography (CT) (mainly coronary CT angiography) is a very promising technique, used more and more for coronary artery evaluation, the benefits and risks of this new low-invasive technique must be balanced. Radiation dose is a major concern for coronary CT angiography, especially in case of repeated examinations or in particular subgroups of patients (for example young female patients). Radiation dose to patient tends to increase from 16- to 64-slice CT. Radiation exposure in ECG-gated acquisitions may reach up to 40 mSv; considerable differences are attributable to the performance of CT machines, to technical dose-sparing tools, but also to radiological habits. Setting radiation dose at the lowest level possible should be a constant goal for the radiologist. Current technological tools are detailed in regard to their efficiency. Optimisation is necessary, by a judicious use of technological tools and also by individual adaptation of kV or mAs. This paper reviews the different current strategies for radiation dose reduction, keeping image quality constant. Data from the literature are discussed, and future technological developments are considered in regards to radiation dose reduction. The particular case of paediatric patients with congenital heart disease is also addressed.

  7. Effects Of Dose Rates On Radiation Damage In CMOS Parts

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Coss, James R.; Price, William E.

    1990-01-01

    Report describes measurements of effects of ionizing-radiation dose rate on consequent damage to complementary metal oxide/semiconductor (CMOS) electronic devices. Depending on irradiation time and degree of annealing, survivability of devices in outer space, or after explosion of nuclear weapons, enhanced. Annealing involving recovery beyond pre-irradiation conditions (rebound) detrimental. Damage more severe at lower dose rates.

  8. Fetal radiation dose in computed tomography.

    PubMed

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

    2015-07-01

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

  9. Radiation dose to the lens and cataract formation

    SciTech Connect

    Henk, J.M.; Whitelocke, R.A.F.; Warrington, A.P.; Bessell, E.M. )

    1993-04-02

    The purpose of this work was to determine the radiation tolerance of the lens of the eye and the incidence of radiation-induced lens changes in patients treated by fractionated supervoltage radiation therapy for orbital tumors. Forty patients treated for orbital lymphoma and pseudotumor with tumor doses of 20--40 Gy were studied. The lens was partly shielded using lead cylinders in most cases. The dose to the germinative zone of the lens was estimated by measurements in a tissue equivalent phantom using both film densitometry and thermoluminescent dosimetry. Opthalmological examination was performed at 6 monthly intervals after treatment. The lead shield was found to reduce the dose to the germinative zone of the lens to between 36--50% of the tumor dose for Cobalt beam therapy, and to between 11--18% for 5 MeV x-rays. Consequently, the lens doses were in the range 4.5--30 Gy in 10--20 fractions. Lens opacities first appeared from between 3 and 9 years after irradiation. Impairment of visual acuity ensued in 74% of the patients who developed lens opacities. The incidence of lens changes was strongly dose-related. None was seen after doses of 5 Gy or lower, whereas doses of 16.5 Gy or higher were all followed by lens opacities which impaired visual acuity. The largest number of patients received a maximum lens dose of 15 Gy; in this group the actuarial incidence of lens opacities at 8 years was 57% with visual impairment in 38%. The adult lens can tolerate a total dose of 5 Gy during a fractionated course of supervoltage radiation therapy without showing any changes. Doses of 16.5 Gy or higher will almost invariably lead to visual impairment. The dose which causes a 50% probability of visual impairment is approximately 15 Gy. 10 refs., 4 figs., 1 tab.

  10. Some cosmic radiation dose measurements aboard flights connecting Zagreb Airport.

    PubMed

    Vuković, B; Radolić, V; Lisjak, I; Vekić, B; Poje, M; Planinić, J

    2008-02-01

    When primary particles from space, mainly protons, enter the atmosphere, they produce interactions with air nuclei, and cosmic-ray showers are induced. The radiation field at aircraft altitude is complex, with different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. The non-neutron component of cosmic radiation dose aboard A320 and ATR40 aircraft was measured with TLD-100 (LiF:Mg,Ti) detectors and the Mini 6100 semiconductor dosimeter; the neutron dose was measured with the neutron dosimeter consisted of LR-115 track detector and boron foil BN-1 or 10B converter. The estimated occupational effective dose for the aircraft crew (A320) working 500 h per year was 1.64 mSv. Another experiment was performed at the flights Zagreb-Paris-Buenos Aires and reversely, when one measured non-neutron cosmic radiation dose; for 26.7 h of flight, the MINI 6100 dosimeter gave an average dose rate of 2.3 microSv/h and the TLD dosimeter registered the dose equivalent of 75 microSv or the average dose rate of 2.7 microSv/h; the neutron dosimeter gave the dose rate of 2.4 microSv/h. In the same month, February 2005, a traveling to Japan (24-h-flight: Zagreb-Frankfurt-Tokyo and reversely) and the TLD-100 measurement showed the average dose rate of 2.4microSv/h; the neutron dosimeter gave the dose rate of 2.5 microSv/h. Comparing dose rates of the non-neutron component (low LET) and the neutron one (high LET) of the radiation field at the aircraft flight level, we could conclude that the neutron component carried about 50% of the total dose, that was near other known data.

  11. A CONCEPTUAL FRAMEWORK FOR MANAGING RADIATION DOSE TO PATIENTS IN DIAGNOSTIC RADIOLOGY USING REFERENCE DOSE LEVELS.

    PubMed

    Almén, Anja; Båth, Magnus

    2016-06-01

    The overall aim of the present work was to develop a conceptual framework for managing radiation dose in diagnostic radiology with the intention to support optimisation. An optimisation process was first derived. The framework for managing radiation dose, based on the derived optimisation process, was then outlined. The outset of the optimisation process is four stages: providing equipment, establishing methodology, performing examinations and ensuring quality. The optimisation process comprises a series of activities and actions at these stages. The current system of diagnostic reference levels is an activity in the last stage, ensuring quality. The system becomes a reactive activity only to a certain extent engaging the core activity in the radiology department, performing examinations. Three reference dose levels-possible, expected and established-were assigned to the three stages in the optimisation process, excluding ensuring quality. A reasonably achievable dose range is also derived, indicating an acceptable deviation from the established dose level. A reasonable radiation dose for a single patient is within this range. The suggested framework for managing radiation dose should be regarded as one part of the optimisation process. The optimisation process constitutes a variety of complementary activities, where managing radiation dose is only one part. This emphasises the need to take a holistic approach integrating the optimisation process in different clinical activities.

  12. Radiation Dose-Response Relationships and Risk Assessment

    SciTech Connect

    Strom, Daniel J.

    2005-07-05

    The notion of a dose-response relationship was probably invented shortly after the discovery of poisons, the invention of alcoholic beverages, and the bringing of fire into a confined space in the forgotten depths of ancient prehistory. The amount of poison or medicine ingested can easily be observed to affect the behavior, health, or sickness outcome. Threshold effects, such as death, could be easily understood for intoxicants, medicine, and poisons. As Paracelsus (1493-1541), the 'father' of modern toxicology said, 'It is the dose that makes the poison.' Perhaps less obvious is the fact that implicit in such dose-response relationships is also the notion of dose rate. Usually, the dose is administered fairly acutely, in a single injection, pill, or swallow; a few puffs on a pipe; or a meal of eating or drinking. The same amount of intoxicants, medicine, or poisons administered over a week or month might have little or no observable effect. Thus, before the discovery of ionizing radiation in the late 19th century, toxicology ('the science of poisons') and pharmacology had deeply ingrained notions of dose-response relationships. This chapter demonstrates that the notion of a dose-response relationship for ionizing radiation is hopelessly simplistic from a scientific standpoint. While useful from a policy or regulatory standpoint, dose-response relationships cannot possibly convey enough information to describe the problem from a quantitative view of radiation biology, nor can they address societal values. Three sections of this chapter address the concepts, observations, and theories that contribute to the scientific input to the practice of managing risks from exposure to ionizing radiation. The presentation begins with irradiation regimes, followed by responses to high and low doses of ionizing radiation, and a discussion of how all of this can inform radiation risk management. The knowledge that is really needed for prediction of individual risk is presented

  13. Radiation Dose from Lunar Neutron Albedo

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Bhattacharya, M.; Lin, Zi-Wei; Pendleton, G.

    2006-01-01

    The lunar neutron albedo from thermal energies to 8 MeV was measured on the Lunar Prospector Mission in 1998-1999. Using GEANT4 we have calculated the neutron albedo due to cosmic ray bombardment of the moon and found a good-agreement with the measured fast neutron spectra. We then calculated the total effective dose from neutron albedo of all energies, and made comparisons with the effective dose contributions from both galactic cosmic rays and solar particle events to be expected on the lunar surface.

  14. Individual and collective doses from cosmic radiation in Ireland.

    PubMed

    Colgan, P A; Synnott, H; Fenton, D

    2007-01-01

    This paper assesses the individual and collective doses in Ireland due to cosmic radiation. Information on the exposure to cosmic radiation at ground level is reviewed and published data on the frequency of routes flown by Irish residents is used to calculate the dose due to air travel. Occupational exposure of aircrew is also evaluated. Experimental data on cosmic radiation exposure at ground level is in good agreement with international estimates and the average individual dose is calculated as 300 microSv annually. Published data on international air travel by Irish residents shows a 50% increase in the number of flights taken between 2001 and 2005. This increase is primarily on short-haul flights to Europe, but there have been significant percentage increases in all long-haul flights, with the exception of flights to Africa. The additional per capita dose due to air travel is estimated to be 45 muSv, of which 51% is accumulated on European routes and 34% on routes to the United States. Exposure of aircrew to cosmic radiation is now controlled by legislation and all airlines holding an Air Operator's Certificate issued by the Irish Aviation Authority are required to report annually the doses received by their employees in the previous year. There has been a 75% increase in the number of aircrew receiving doses >1 mSv since 2002. In 2004 and 2005 the average individual doses received by Irish aircrew were 1.8 and 2.0, mSv, respectively. The corresponding per caput dose for the entire population is <3 muSv. While this is low compared with the per caput doses from other sources of cosmic radiation, aircrew exposure represents a higher collective dose than any other identified group of exposed workers in Ireland.

  15. Radiation Dose-Volume Effects in the Heart

    SciTech Connect

    Gagliardi, Giovanna; Constine, Louis S.; Moiseenko, Vitali; Correa, Candace; Pierce, Lori J.; Allen, Aaron M.; Marks, Lawrence B.

    2010-03-01

    The literature is reviewed to identify the main clinical and dose-volume predictors for acute and late radiation-induced heart disease. A clear quantitative dose and/or volume dependence for most cardiac toxicity has not yet been shown, primarily because of the scarcity of the data. Several clinical factors, such as age, comorbidities and doxorubicin use, appear to increase the risk of injury. The existing dose-volume data is presented, as well as suggestions for future investigations to better define radiation-induced cardiac injury.

  16. Avoiding OHSS: Controlled Ovarian Low-Dose Stimulation in Women with PCOS.

    PubMed

    Fischer, D; Reisenbüchler, C; Rösner, S; Haussmann, J; Wimberger, P; Goeckenjan, M

    2016-06-01

    The polycystic ovary syndrome is a common endocrine disorder which influences outcome and potential risks involved with controlled ovarian stimulation for artificial reproductive techniques (ART). Concrete practical recommendations for the dosage of gonadotropins, the preferred protocol and preventive methods to avoid ovarian hyperstimulation syndrome (OHSS) are lacking. We present retrospective data of 235 individually calculated gonadotropin low-dose stimulations for ART in a single center from 2012 to 2014. Clinical data and outcome parameter of patients diagnosed with PCOS according to Rotterdam criteria (n = 39) were compared with patients without PCOS (n = 196). The starting dose of gonadotropins was individually calculated depending on patients' age, BMI, ovarian reserve, ovarian response in previous cycles, and diagnostic criteria of PCOS. Mean age and duration of infertility did not differ between the groups, whereas mean BMI (p = 0.007) and AMH (p < 0.001) were higher in the PCOS-group. A lower mean FSH-starting and maximum dose was administered to women with PCOS (p < 0.001). The biochemical pregnancy rate of 42.4 % and the clinical pregnancy rate of 32.2 % for PCOS-patients did not differ from those of the control group (42.2 % and 34.4 % respectively). Neither mild, nor moderate or severe manifestation of OHSS occurred significantly more often in patients with PCOS. Our study supports the use of a calculated low-dose FSH-stimulation strategy in ART for patients with PCOS. Further randomized clinical trials should confirm this strategy and lead to define individual risk factors for OHSS, which can be used for recommendation of safer ART-techniques like in vitro maturation.

  17. Time-dependent radiation dose simulations during interplanetary space flights

    NASA Astrophysics Data System (ADS)

    Dobynde, Mikhail; Shprits, Yuri; Drozdov, Alexander; Hoffman, Jeffrey; Li, Ju

    2016-07-01

    Space radiation is one of the main concerns in planning long-term interplanetary human space missions. There are two main types of hazardous radiation - Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR). Their intensities and evolution depend on the solar activity. GCR activity is most enhanced during solar minimum, while the most intense SEPs usually occur during the solar maximum. SEPs are better shielded with thick shields, while GCR dose is less behind think shields. Time and thickness dependences of the intensity of these two components encourage looking for a time window of flight, when radiation intensity and dose of SEP and GCR would be minimized. In this study we combine state-of-the-art space environment models with GEANT4 simulations to determine the optimal shielding, geometry of the spacecraft, and launch time with respect to the phase of the solar cycle. The radiation environment was described by the time-dependent GCR model, and the SEP spectra that were measured during the period from 1990 to 2010. We included gamma rays, electrons, neutrons and 27 fully ionized elements from hydrogen to nickel. We calculated the astronaut's radiation doses during interplanetary flights using the Monte-Carlo code that accounts for the primary and the secondary radiation. We also performed sensitivity simulations for the assumed spacecraft size and thickness to find an optimal shielding. In conclusion, we present the dependences of the radiation dose as a function of launch date from 1990 to 2010, for flight durations of up to 3 years.

  18. Linking Doses with Clinical Scores of Hematopoietic Acute Radiation Syndrome.

    PubMed

    Hu, Shaowen

    2016-10-01

    In radiation accidents, determining the radiation dose the victim received is a key step for medical decision making and patient prognosis. To reconstruct and evaluate the absorbed dose, researchers have developed many physical devices and biological techniques during the last decades. However, using the physical parameter "absorbed dose" alone is not sufficient to predict the clinical development of the various organs injured in an individual patient. In operational situations for radiation accidents, medical responders need more urgently to classify the severity of the radiation injury based on the signs and symptoms of the patient. In this work, the author uses a unified hematopoietic model to describe dose-dependent dynamics of granulocytes, lymphocytes, and platelets, and the corresponding clinical grading of hematopoietic acute radiation syndrome. This approach not only visualizes the time course of the patient's probable outcome in the form of graphs but also indirectly gives information of the remaining stem and progenitor cells, which are responsible for the autologous recovery of the hematopoietic system. Because critical information on the patient's clinical evolution can be provided within a short time after exposure and only peripheral cell counts are required for the simulation, these modeling tools will be useful to assess radiation exposure and injury in human-involved radiation accident/incident scenarios.

  19. Low dose radiation-induced endothelial cell retraction.

    PubMed

    Kantak, S S; Diglio, C A; Onoda, J M

    1993-09-01

    We characterized in vitro the effects of gamma-radiation (12.5-100 cGy) on pulmonary microvascular endothelial cell (PMEC) morphology and F-actin organization. Cellular retraction was documented by phase-contrast microscopy and the organization of actin microfilaments was determined by immunofluorescence. Characterization included radiation dose effects, their temporal duration and reversibility of the effects. A dose-dependent relationship between the level of exposure (12.5-100 cGy) and the rate and extent of endothelial retraction was observed. Moreover, analysis of radiation-induced depolymerization of F-actin microfilament stress fibres correlated positively with the changes in PMEC morphology. The depolymerization of the stress fibre bundles was dependent on radiation dose and time. Cells recovered from exposure to reform contact inhibited monolayers > or = 24 h post-irradiation. Concomitantly, the depolymerized microfilaments reorganized to their preirradiated state as microfilament stress fibres arrayed parallel to the boundaries of adjacent contact-inhibited cells. The data presented here are representative of a series of studies designed to characterize low-dose radiation effects on pulmonary microvascular endothelium. Our data suggest that post-irradiation lung injuries (e.g. oedema) may be induced with only a single fraction of therapeutic radiation, and thus microscopic oedema may initiate prior to the lethal effects of radiation on the microvascular endothelium, and much earlier than would be suggested by the time course for clinically-detectable oedema.

  20. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    SciTech Connect

    Kleiman, Norman Jay

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  1. Space radiation absorbed dose distribution in a human phantom

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  2. Space radiation absorbed dose distribution in a human phantom.

    PubMed

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  3. Errors and Uncertainties in Dose Reconstruction for Radiation Effects Research

    SciTech Connect

    Strom, Daniel J.

    2008-04-14

    Dose reconstruction for studies of the health effects of ionizing radiation have been carried out for many decades. Major studies have included Japanese bomb survivors, atomic veterans, downwinders of the Nevada Test Site and Hanford, underground uranium miners, and populations of nuclear workers. For such studies to be credible, significant effort must be put into applying the best science to reconstructing unbiased absorbed doses to tissues and organs as a function of time. In many cases, more and more sophisticated dose reconstruction methods have been developed as studies progressed. For the example of the Japanese bomb survivors, the dose surrogate “distance from the hypocenter” was replaced by slant range, and then by TD65 doses, DS86 doses, and more recently DS02 doses. Over the years, it has become increasingly clear that an equal level of effort must be expended on the quantitative assessment of uncertainty in such doses, and to reducing and managing uncertainty. In this context, this paper reviews difficulties in terminology, explores the nature of Berkson and classical uncertainties in dose reconstruction through examples, and proposes a path forward for Joint Coordinating Committee for Radiation Effects Research (JCCRER) Project 2.4 that requires a reasonably small level of effort for DOSES-2008.

  4. Wound Trauma Alters Ionizing Radiation Dose Assessment

    DTIC Science & Technology

    2012-06-11

    sterile isotonic 0.9% NaCl as fluid therapy immediately after sham handling, irradiation, and/or wounding. After fluid therapy , mice were returned to...wounds or radiation exposure alone. Consequences of combined injury include acute myelosuppression, immune system inhibition, fluid imbalance, macro...These molecular changes suggest potential approaches for the design of countermeasures and therapies as well as possibilities for recovery from

  5. Peripheral Doses from Noncoplanar IMRT for Pediatric Radiation Therapy

    SciTech Connect

    Kan, Monica W.K.; Leung, Lucullus H.T.; Kwong, Dora L.W.; Wong, Wicger; Lam, Nelson

    2010-01-01

    The use of noncoplanar intensity-modulated radiation therapy (IMRT) might result in better sparing of some critical organs because of a higher degree of freedom in beam angle optimization. However, this can lead to a potential increase in peripheral dose compared with coplanar IMRT. The peripheral dose from noncoplanar IMRT has not been previously quantified. This study examines the peripheral dose from noncoplanar IMRT compared with coplanar IMRT for pediatric radiation therapy. Five cases with different pediatric malignancies in head and neck were planned with both coplanar and noncoplanar IMRT techniques. The plans were performed such that the tumor coverage, conformality, and dose uniformity were comparable for both techniques. To measure the peripheral doses of the 2 techniques, thermoluminescent dosimeters (TLD) were placed in 10 different organs of a 5-year-old pediatric anthropomorphic phantom. With the use of noncoplanar beams, the peripheral doses to the spinal cord, bone marrow, lung, and breast were found to be 1.8-2.5 times of those using the coplanar technique. This is mainly because of the additional internal scatter dose from the noncoplanar beams. Although the use of noncoplanar technique can result in better sparing of certain organs such as the optic nerves, lens, or inner ears depending on how the beam angles were optimized on each patient, oncologists should be alert of the possibility of significantly increasing the peripheral doses to certain radiation-sensitive organs such as bone marrow and breast. This might increase the secondary cancer risk to patients at young age.

  6. Radiation dose assessment of exposure to depleted uranium.

    PubMed

    Li, Wei Bo; Gerstmann, Udo C; Höllriegl, Vera; Szymczak, Wilfried; Roth, Paul; Hoeschen, Christoph; Oeh, Uwe

    2009-07-01

    Depleted uranium (DU) is claimed to contribute to human health problems, known as the Gulf War Syndrome and the Balkan Syndrome. Quantitative radiation dose is required to estimate the health risk of DU materials. The influences of the solubility parameters in the human alimentary tract and the respiratory tract systems and the aerosol particles size on the radiation dose of DU materials were evaluated. The dose conversion factor of daily urinary excretion of DU is provided. The retention and excretion of DU in the human body after a contamination at a wound site were predicted. Dose coefficients of DU after ingestion and inhalation were calculated using the solubility parameters of the DU corrosion products in simulated gastric and simulated lung fluid, which were determined in the Helmholtz Zentrum München. (238)U is the main radiation dose contributor per 1 Bq of DU materials. The dose coefficients of DU materials were estimated to be 3.5 x 10(-8) and 2.1 x 10(-6) Sv Bq(-1) after ingestion and inhalation for members of the public. The ingestion dose coefficient of DU materials is about 75% of the natural uranium value. The inhalation dose coefficient of DU material is in between those for Type M and Type S according to the category for inhaled materials defined by the International Commission on Radiological Protection. Radiation dose possibly received from DU materials can directly be estimated by using the dose conversion factor provided in this study, if daily urinary excretion of DU is measured.

  7. Photon: the minimum dose of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Suntola, Tuomo

    2005-08-01

    A radio engineer can hardly think about smaller amount of electromagnetic radiation than given by a single oscillation cycle of a unit charge in a dipole. When solved from Maxwell's equations for a dipole of one wavelength, the energy of the emitted radiation cycle obtains the form Eλ = 2/3 hf, where the Planck constant h can be expressed in terms of the unit charge, e, the vacuum permeability, μ0, the velocity of light, c, and a numerical factor as h = 1.1049*2π3e2μ0c=6.62607*10-34 [kgm2/s]. A point emitter like an atom can be regarded as a dipole in the fourth dimension. The length of such dipole is measured in the direction of the line element cdt, which in one oscillation cycle means the length of one wavelength. For a dipole in the fourth dimension, three space directions are in the normal plane which eliminates the factor 2/3 from the energy expression thus leading to Planck's equation Eλ = hf for the radiation emitted by a single electron transition in an atom. The expression of the Planck constant obtained from Maxwell's equations leads to a purely numerical expression of the fine structure constant α=1/(1.1049*4π3) = 1/137 and shows that the Planck constant is directly proportional to the velocity of light. When applied to Balmer's formula, the linkage of the Planck constant to the velocity of light shows, that the frequency of an atomic oscillator is directly proportional to the velocity of light. This implies that the velocity of light is observed as constant in local measurements. Such an interpretation makes it possible to convert relativistic spacetime with variable time coordinates into space with variable clock frequencies in universal time, and thus include relativistic phenomena in the framework of quantum mechanics.

  8. Equivalent dose and effective dose from stray radiation during passively scattered proton radiotherapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Fontenot, Jonas; Taddei, Phillip; Zheng, Yuanshui; Mirkovic, Dragan; Jordan, Thomas; Newhauser, Wayne

    2008-03-01

    Proton therapy reduces the integral therapeutic dose required for local control in prostate patients compared to intensity-modulated radiotherapy. One proposed benefit of this reduction is an associated decrease in the incidence of radiogenic secondary cancers. However, patients are also exposed to stray radiation during the course of treatment. The purpose of this study was to quantify the stray radiation dose received by patients during proton therapy for prostate cancer. Using a Monte Carlo model of a proton therapy nozzle and a computerized anthropomorphic phantom, we determined that the effective dose from stray radiation per therapeutic dose (E/D) for a typical prostate patient was approximately 5.5 mSv Gy-1. Sensitivity analysis revealed that E/D varied by ±30% over the interval of treatment parameter values used for proton therapy of the prostate. Equivalent doses per therapeutic dose (HT/D) in specific organs at risk were found to decrease with distance from the isocenter, with a maximum of 12 mSv Gy-1 in the organ closest to the treatment volume (bladder) and 1.9 mSv Gy-1 in the furthest (esophagus). Neutrons created in the nozzle predominated effective dose, though neutrons created in the patient contributed substantially to the equivalent dose in organs near the proton field. Photons contributed less than 15% to equivalent doses.

  9. Classification of radiation effects for dose limitation purposes: history, current situation and future prospects.

    PubMed

    Hamada, Nobuyuki; Fujimichi, Yuki

    2014-07-01

    Radiation exposure causes cancer and non-cancer health effects, each of which differs greatly in the shape of the dose-response curve, latency, persistency, recurrence, curability, fatality and impact on quality of life. In recent decades, for dose limitation purposes, the International Commission on Radiological Protection has divided such diverse effects into tissue reactions (formerly termed non-stochastic and deterministic effects) and stochastic effects. On the one hand, effective dose limits aim to reduce the risks of stochastic effects (cancer/heritable effects) and are based on the detriment-adjusted nominal risk coefficients, assuming a linear-non-threshold dose response and a dose and dose rate effectiveness factor of 2. On the other hand, equivalent dose limits aim to avoid tissue reactions (vision-impairing cataracts and cosmetically unacceptable non-cancer skin changes) and are based on a threshold dose. However, the boundary between these two categories is becoming vague. Thus, we review the changes in radiation effect classification, dose limitation concepts, and the definition of detriment and threshold. Then, the current situation is overviewed focusing on (i) stochastic effects with a threshold, (ii) tissue reactions without a threshold, (iii) target organs/tissues for circulatory disease, (iv) dose levels for limitation of cancer risks vs prevention of non-life-threatening tissue reactions vs prevention of life-threatening tissue reactions, (v) mortality or incidence of thyroid cancer, and (vi) the detriment for tissue reactions. For future discussion, one approach is suggested that classifies radiation effects according to whether effects are life threatening, and radiobiological research needs are also briefly discussed.

  10. Impact of Drug Therapy, Radiation Dose, and Dose Rate on Renal Toxicity Following Bone Marrow Transplantation

    SciTech Connect

    Cheng, Jonathan C.; Schultheiss, Timothy E. Wong, Jeffrey Y.C.

    2008-08-01

    Purpose: To demonstrate a radiation dose response and to determine the dosimetric and chemotherapeutic factors that influence the incidence of late renal toxicity following total body irradiation (TBI). Methods and Materials: A comprehensive retrospective review was performed of articles reporting late renal toxicity, along with renal dose, fractionation, dose rate, chemotherapy regimens, and potential nephrotoxic agents. In the final analysis, 12 articles (n = 1,108 patients), consisting of 24 distinct TBI/chemotherapy conditioning regimens were included. Regimens were divided into three subgroups: adults (age {>=}18 years), children (age <18 years), and mixed population (both adults and children). Multivariate logistic regression was performed to identify dosimetric and chemotherapeutic factors significantly associated with late renal complications. Results: Individual analysis was performed on each population subgroup. For the purely adult population, the only significant variable was total dose. For the mixed population, the significant variables included total dose, dose rate, and the use of fludarabine. For the pediatric population, only the use of cyclosporin or teniposide was significant; no dose response was noted. A logistic model was generated with the exclusion of the pediatric population because of its lack of dose response. This model yielded the following significant variables: total dose, dose rate, and number of fractions. Conclusion: A dose response for renal damage after TBI was identified. Fractionation and low dose rates are factors to consider when delivering TBI to patients undergoing bone marrow transplantation. Drug therapy also has a major impact on kidney function and can modify the dose-response function.

  11. Radiation dose to personnel during percutaneous renal calculus removal

    SciTech Connect

    Bush, W.H.; Jones, D.; Brannen, G.E.

    1985-12-01

    Radiation dose to the radiologist and other personnel was measured during 102 procedures for percutaneous removal of renal calculi from the upper collecting system. A mobile C-arm image intensifier was used to guide entrance to the kidney and stone removal. Average fluoroscopy time was 25 min. Exposure to personnel was monitored by quartz-fiber dosimeters at the collar level above the lead apron. Average radiation dose to the radiologist was 10 mrem (0.10 mSv) per case; to the surgical nurse, 4 mrem (0.04 mSv) per case; to the radiologic technologist, 4 mrem (0.04 mSv) per case; and to the anesthesiologist, 3 mrem (0.03 mSv) per case. Radiation dose to the uroradiologic team during percutaneous nephrostolithotomy is similar to that from other interventional fluoroscopic procedures and is within acceptable limits for both physicians and assisting personnel.

  12. [Mechanism of cytogenetic adaptive response induced by low dose radiation].

    PubMed

    Cai, L; Liu, S

    1990-11-01

    Cytogenetic observation on human lymphocytes indicated that pre-exposure of 10, 50 and 75 mGy X-rays could induced the adaptive response. Experimental results with different temperature treatment showed that the adaptive response induced by low dose radiation could be enhanced by 41 degrees C and 43 degrees C, but inhibited by 4 degrees C in addition the treatment by 41 degrees C for one hour could also cause the adaptive response as did low dose radiation. Results showed that adaptive response induced by low dose radiation (10 or 50 mGy X-rays) could be eliminated by the protein synthesis inhibitor, implying that the adaptive response is related with the metabolism of cells, especially with the production of certain protective proteins.

  13. A molecular fraction method for measuring personnel radiation doses

    NASA Astrophysics Data System (ADS)

    Fadel, M. A.; Khalil, W. A.; Krodja, R. P.; Sheta, N.; Abd El-Baset, M. S.

    1987-02-01

    This work represents a development in fast and albedo neutron and gamma ray dosimetry, using cellulose nitrate, as a tissue equivalent material, in which radiation damage was registered. The changes in molecular fractions of the polymer were measured after irradiation with neutron fluences from a 252Cf source in the range 10 5-10 10 n/cm 2 and gamma doses in the range 10 -4-10 -1 Gy through the use of gel filtration chromatography. Effects of irradiation on phantom, phantom to dosimeter distance, phantom thickness and storage at extreme environmental conditions were studied on the detector response and readout. The results showed that main chain scission followed by formation of new molecular configurations is the predominant effect of radiation on the polymer. The method enables measurements of neutron fluences and gamma doses in mixed radiation fields. Empirical formulae for calculating the absorbed dose from the measured changes in molecular fraction intensities are given.

  14. Boron neutron capture therapy using mixed epithermal and thermal neutron beams in patients with malignant glioma-correlation between radiation dose and radiation injury and clinical outcome

    SciTech Connect

    Kageji, Teruyoshi . E-mail: kageji@clin.med.tokushima-u.ac.jp; Nagahiro, Shinji; Matsuzaki, Kazuhito; Mizobuchi, Yoshifumi; Toi, Hiroyuki; Nakagawa, Yoshinobu; Kumada, Hiroaki

    2006-08-01

    Purpose: To clarify the correlation between the radiation dose and clinical outcome of sodium borocaptate-based intraoperative boron neutron capture therapy in patients with malignant glioma. Methods and Materials: The first protocol (P1998, n = 8) prescribed a maximal gross tumor volume (GTV) dose of 15 Gy. In 2001, a dose-escalated protocol was introduced (P2001, n 11), which prescribed a maximal vascular volume dose of 15 Gy or, alternatively, a clinical target volume (CTV) dose of 18 Gy. Results: The GTV and CTV doses in P2001 were 1.1-1.3 times greater than those in P1998. The maximal vascular volume dose of those with acute radiation injury was 15.8 Gy. The mean GTV and CTV dose in long-term survivors with glioblastoma was 26.4 and 16.5 Gy, respectively. A statistically significant correlation between the GTV dose and median survival time was found. In the 11 glioblastoma patients in P2001, the median survival time was 19.5 months and 1- and 2-year survival rate was 60.6% and 37.9%, respectively. Conclusion: Dose escalation contributed to the improvement in clinical outcome. To avoid radiation injury, the maximal vascular volume dose should be <12 Gy. For long-term survival in patients with glioblastoma after boron neutron capture therapy, the optimal mean dose of the GTV and CTV was 26 and 16 Gy, respectively.

  15. Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation.

    PubMed

    Kume, Atsushi; Akitsu, Tomoko; Nasahara, Kenlo Nishida

    2016-07-01

    The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (μmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies.

  16. Analysis of Radiation Impact on White Mice through Radiation Dose Mapping in Medical Physics Laboratory

    NASA Astrophysics Data System (ADS)

    Sutikno, Madnasri; Susilo; Arya Wijayanti, Riza

    2016-08-01

    A study about X-ray radiation impact on the white mice through radiation dose mapping in Medical Physic Laboratory is already done. The purpose of this research is to determine the minimum distance of radiologist to X-ray instrument through treatment on the white mice. The radiation exposure doses are measured on the some points in the distance from radiation source between 30 cm up to 80 with interval of 30 cm. The impact of radiation exposure on the white mice and the effects of radiation measurement in different directions are investigated. It is founded that minimum distance of radiation worker to radiation source is 180 cm and X-ray has decreased leukocyte number and haemoglobin and has increased thrombocyte number in the blood of white mice.

  17. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  18. Radiation dose study in nuclear medicine using GATE

    NASA Astrophysics Data System (ADS)

    Aguwa, Kasarachi

    Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Jan et al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiation dose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.

  19. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation

    SciTech Connect

    Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E. )

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  20. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation.

    PubMed

    Sondhaus, C A; Bond, V P; Feinendegen, L E

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  1. Radiation Dose and Safety in Cardiac Computed Tomography

    PubMed Central

    Gerber, Thomas C; Kantor, Birgit; McCollough, Cynthia H.

    2009-01-01

    Synopsis As a result of the changes in utilization of imaging procedures that rely on ionizing radiation, the collective dose has increased by over 700% and the annual per-capita dose, by almost 600% over recent years. It is certainly possible that this growing use may have significant effects on public health. Although there are uncertainties related to the accuracy of calculated radiation exposure and the estimated biologic risk, there are measures that can be taken to reduce any potential risks while maintaining diagnostic accuracy. This article will review the existing data regarding biological hazards of radiation exposure associated to medical diagnostic testing, the methodology used to estimate radiation exposure and the measures that can be taken to effectively reduce it. PMID:19766923

  2. Study of UV radiation dose received by the Spanish population.

    PubMed

    Gurrea, Gonzalo; Cañada, Javier

    2007-01-01

    Excess exposure to UV radiation can affect our health by causing sunburn, skin cancer, etc. It is therefore useful to determine the UV dosage received by people as a way of protecting them from the possible negative effects that this kind of radiation can cause. In this work, the personal outdoor percentage, which shows the time spent in outdoor activities, as well as personal UV doses, has been calculated by means of global UV radiation on a horizontal plane. A database of average daily UVB radiation on the horizontal plane given by the National Institute of Meteorology has been used. In this work we evaluate the standard erythema dose of the Spanish population throughout the year.

  3. Radiation dose to physicians’ eye lens during interventional radiology

    NASA Astrophysics Data System (ADS)

    Bahruddin, N. A.; Hashim, S.; Karim, M. K. A.; Sabarudin, A.; Ang, W. C.; Salehhon, N.; Bakar, K. A.

    2016-03-01

    The demand of interventional radiology has increased, leading to significant risk of radiation where eye lens dose assessment becomes a major concern. In this study, we investigate physicians' eye lens doses during interventional procedures. Measurement were made using TLD-100 (LiF: Mg, Ti) dosimeters and was recorded in equivalent dose at a depth of 0.07 mm, Hp(0.07). Annual Hp(0.07) and annual effective dose were estimated using workload estimation for a year and Von Boetticher algorithm. Our results showed the mean Hp(0.07) dose of 0.33 mSv and 0.20 mSv for left and right eye lens respectively. The highest estimated annual eye lens dose was 29.33 mSv per year, recorded on left eye lens during fistulogram procedure. Five physicians had exceeded 20 mSv dose limit as recommended by international commission of radiological protection (ICRP). It is suggested that frequent training and education on occupational radiation exposure are necessary to increase knowledge and awareness of the physicians’ thus reducing dose during the interventional procedure.

  4. Space Radiation Absorbed Dose Distribution in a Human Phantom Torso

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Yang, T.; Atwell, W.

    2000-01-01

    The flight of a human phantom torso with head that containing active dosimeters at 5 organ sites and 1400 TLDs distributed in 34 1" thick sections is described. Experimental dose rates and quality factors are compared with calculations for shielding distributions at the sites using the Computerized Anatomical Male (CAM) model. The measurements were complemented with those obtained from other instruments. These results have provided the most comprehensive data set to map the dose distribution inside a human and to assess the accuracy of radiation transport models and astronaut radiation risk.

  5. Management of pediatric radiation dose using Agfa computed radiography.

    PubMed

    Schaetzing, R

    2004-10-01

    Radiation dose to patients and its management have become important considerations in modern radiographic imaging procedures, but they acquire particular significance in the imaging of children. Because of their longer life expectancy, children exposed to radiation are thought to have a significantly increased risk of radiation-related late sequelae compared to adults first exposed to radiation later in life. Therefore, current clinical thinking dictates that dose in pediatric radiography be minimized, while simultaneously ensuring sufficient diagnostic information in the image, and reducing the need for repeat exposures. Dose management obviously starts with characterization and control of the exposure technique. However, it extends farther through the imaging chain to the acquisition system, and even to the image processing techniques used to optimize acquired images for display. Further, other factors, such as quality control procedures and the ability to handle special pediatric procedures, like scoliosis exams, also come into play. The need for dose management in modern radiography systems has spawned a variety of different solutions, some of which are similar across different manufacturers, and some of which are unique. This paper covers the techniques used in Agfa Computed Radiography (CR) systems to manage dose in a pediatric environment.

  6. Radiation Dose from Medical Imaging: A Primer for Emergency Physicians

    PubMed Central

    Jones, Jesse G.A; Mills, Christopher N.; Mogensen, Monique A.; Lee, Christoph I.

    2012-01-01

    Introduction Medical imaging now accounts for most of the US population's exposure to ionizing radiation. A substantial proportion of this medical imaging is ordered in the emergency setting. We aim to provide a general overview of radiation dose from medical imaging with a focus on computed tomography, as well as a literature review of recent efforts to decrease unnecessary radiation exposure to patients in the emergency department setting. Methods We conducted a literature review through calendar year 2010 for all published articles pertaining to the emergency department and radiation exposure. Results The benefits of imaging usually outweigh the risks of eventual radiation-induced cancer in most clinical scenarios encountered by emergency physicians. However, our literature review identified 3 specific clinical situations in the general adult population in which the lifetime risks of cancer may outweigh the benefits to the patient: rule out pulmonary embolism, flank pain, and recurrent abdominal pain in inflammatory bowel disease. For these specific clinical scenarios, a physician-patient discussion about such risks and benefits may be warranted. Conclusion Emergency physicians, now at the front line of patients' exposure to ionizing radiation, should have a general understanding of the magnitude of radiation dose from advanced medical imaging procedures and their associated risks. Future areas of research should include the development of protocols and guidelines that limit unnecessary patient radiation exposure. PMID:22900113

  7. Dosimeter for measuring skin dose and more deeply penetrating radiation

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1981-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with netruon-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  8. Acute Radiation Risk and BRYNTRN Organ Dose Projection Graphical User Interface

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Hu, Shaowen; Nounu, Hateni N.; Kim, Myung-Hee

    2011-01-01

    The integration of human space applications risk projection models of organ dose and acute radiation risk has been a key problem. NASA has developed an organ dose projection model using the BRYNTRN with SUM DOSE computer codes, and a probabilistic model of Acute Radiation Risk (ARR). The codes BRYNTRN and SUM DOSE are a Baryon transport code and an output data processing code, respectively. The risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations. With a graphical user interface (GUI) to handle input and output for BRYNTRN, the response models can be connected easily and correctly to BRYNTRN. A GUI for the ARR and BRYNTRN Organ Dose (ARRBOD) projection code provides seamless integration of input and output manipulations, which are required for operations of the ARRBOD modules. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations directorate (MOD), and space biophysics researchers. BRYNTRN code operation requires extensive input preparation. Only a graphical user interface (GUI) can handle input and output for BRYNTRN to the response models easily and correctly. The purpose of the GUI development for ARRBOD is to provide seamless integration of input and output manipulations for the operations of projection modules (BRYNTRN, SLMDOSE, and the ARR probabilistic response model) in assessing the acute risk and the organ doses of significant Solar Particle Events (SPEs). The assessment of astronauts radiation risk from SPE is in support of mission design and operational planning to manage radiation risks in future space missions. The ARRBOD GUI can identify the proper shielding solutions using the gender-specific organ dose assessments in order to avoid ARR symptoms, and to stay within the current NASA short-term dose limits. The quantified evaluation of ARR severities based on any given shielding configuration and a specified EVA or other mission

  9. Biological equivalent dose studies for dose escalation in the stereotactic synchrotron radiation therapy clinical trials

    SciTech Connect

    Prezado, Y.; Fois, G.; Edouard, M.; Nemoz, C.; Renier, M.; Requardt, H.; Esteve, F.; Adam, JF.; Elleaume, H.; Bravin, A.

    2009-03-15

    Synchrotron radiation is an innovative tool for the treatment of brain tumors. In the stereotactic synchrotron radiation therapy (SSRT) technique a radiation dose enhancement specific to the tumor is obtained. The tumor is loaded with a high atomic number (Z) element and it is irradiated in stereotactic conditions from several entrance angles. The aim of this work was to assess dosimetric properties of the SSRT for preparing clinical trials at the European Synchrotron Radiation Facility (ESRF). To estimate the possible risks, the doses received by the tumor and healthy tissues in the future clinical conditions have been calculated by using Monte Carlo simulations (PENELOPE code). The dose enhancement factors have been determined for different iodine concentrations in the tumor, several tumor positions, tumor sizes, and different beam sizes. A scheme for the dose escalation in the various phases of the clinical trials has been proposed. The biological equivalent doses and the normalized total doses received by the skull have been calculated in order to assure that the tolerance values are not reached.

  10. Ambient dose and dose rate measurements in the vicinity of Elekta Precise accelerators for radiation therapy.

    PubMed

    Zutz, H; Hupe, O

    2014-12-01

    In radiation therapy, commercially available medical linear accelerators (LINACs) are used. At high primary beam energies in the 10-MeV range, the leakage dose of the accelerator head and the backscatter from the room walls, the air and the patient become more important. Therefore, radiation protection measurements of photon dose rates in the treatment room and in the maze are performed to quantify the radiation field. Since the radiation of the LINACs is usually pulsed with short radiation pulse durations in the microsecond range, there are problems with electronic dose (rate) meters commonly used in radiation protection. In this paper measurements with ionisation chambers are presented and electronic dosemeters are used for testing at selected positions. The measured time-averaged dose rate ranges from a few microsieverts per hour in the maze to some millisieverts per hour in the vicinity of the accelerator head and up to some sieverts per hour in the blanked primary beam and several hundred sieverts per hour in the direct primary beam.

  11. Compelling Issues Compounding the Understanding of Low Dose Radiation Effects: But Do They Matter?

    PubMed

    Morgan, William F

    2016-03-01

    Recent advances in low dose radiation research have raised a number of compelling issues that have compounded the understanding of low dose radiation effects. Here some of them are outlined: the linear no-threshold model for predicting effects at low radiation doses, dose rate effectiveness factor, attributability, and public perception of low dose radiation effects. The impact of changes in any of these hotly debated issues on radiation protection is considered.

  12. Prototype Operational Advances for Atmospheric Radiation Dose Rate Specification

    NASA Astrophysics Data System (ADS)

    Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Garrett, H. B.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, D.; Mertens, C. J.; Xu, X.; Crowley, G.; Reynolds, A.; Azeem, I.; Wiltberger, M. J.; Wiley, S.; Bacon, S.; Teets, E.; Sim, A.; Dominik, L.

    2014-12-01

    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. 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 developed innovative, new space weather observations that will become part of the toolset that is transitioned into operational use. One prototype operational system for providing timely information about the effects of space weather is SET's Automated Radiation Measurements for Aerospace Safety (ARMAS) system. ARMAS will provide the "weather" of the radiation environment to improve aircraft crew and passenger safety. Through several dozen flights the ARMAS project has 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 via Iridium satellites, 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. We are extending the dose measurement domain above commercial aviation altitudes into the stratosphere with a collaborative project organized by NASA's Armstrong Flight Research Center (AFRC) called Upper-atmospheric Space and Earth Weather eXperiment (USEWX). In USEWX we will be flying on the ER-2 high altitude aircraft a micro dosimeter for

  13. Detecting ionizing radiation with optical fibers down to biomedical doses

    NASA Astrophysics Data System (ADS)

    Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

    2013-10-01

    We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

  14. NAIRAS aircraft radiation model development, dose climatology, and initial validation

    PubMed Central

    Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

    2013-01-01

    [1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis

  15. NAIRAS aircraft radiation model development, dose climatology, and initial validation.

    PubMed

    Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

    2013-10-01

    [1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis

  16. Radiation-induced biomarkers for the detection and assessment of absorbed radiation doses

    PubMed Central

    Rana, Sudha; Kumar, Raj; Sultana, Sarwat; Sharma, Rakesh Kumar

    2010-01-01

    Radiation incident involving living organisms is an uncommon but a very serious situation. The first step in medical management including triage is high-throughput assessment of the radiation dose received. Radiation exposure levels can be assessed from viability of cells, cellular organelles such as chromosome and different intermediate metabolites. Oxidative damages by ionizing radiation result in carcinogenesis, lowering of the immune response and, ultimately, damage to the hematopoietic system, gastrointestinal system and central nervous system. Biodosimetry is based on the measurement of the radiation-induced changes, which can correlate them with the absorbed dose. Radiation biomarkers such as chromosome aberration are most widely used. Serum enzymes such as serum amylase and diamine oxidase are the most promising biodosimeters. The level of gene expression and protein are also good biomarkers of radiation. PMID:21829314

  17. Radiation effect in mouse skin: Dose fractionation and wound healing

    SciTech Connect

    Gorodetsky, R.; Mou, X.D.; Fisher, D.R.; Taylor, J.M.; Withers, H.R. )

    1990-05-01

    Radiation induced dermal injury was measured by the gain in the physical strength of healing wounds in mouse skin. A sigmoid dose response for the inhibition of wound healing 14 days after surgery was found for single doses of X rays. The sparing of dermal damage from fractionation of the X-ray dose was quantified in terms of the alpha/beta ratio in the linear-quadratic (LQ) model, at a wide range of doses per fraction reaching as low as about 1 Gy. The fit and the appropriateness of the LQ model for the skin wound healing assay was examined with the use of the Fe-plot in which inverse total dose is plotted versus dose per fraction for wound strength isoeffects. The alpha/beta ratio of the skin was about 2.5 Gy (95% confidence of less than +/- 1 Gy) and was appropriate over a dose range of 1 Gy to about 8 Gy. The low alpha/beta value is typical for a late responding tissue. This assay, therefore, has the advantage of measuring and forecasting late radiation responses of the dermis within a short time after irradiation.

  18. Radiation Doses and Associated Risk From the Fukushima Nuclear Accident.

    PubMed

    Ishikawa, Tetsuo

    2017-03-01

    The magnitude of dose due to the Fukushima Daiichi Accident was estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2013 report published in April 2014. Following this, the UNSCEAR white paper, which comprises a digest of new information for the 2013 Fukushima report, was published in October 2015. Another comprehensive report on radiation dose due to the accident is the International Atomic Energy Agency (IAEA) report on the Fukushima Daiichi Accident published in August 2015. Although the UNSCEAR and IAEA publications well summarize doses received by residents, they review only literature published before the end of December 2014 and the end of March 2015, respectively. However, some studies on dose estimation have been published since then. In addition, the UNSCEAR 2013 report states it was likely that some overestimation had been introduced generally by the methodology used by the Committee. For example, effects of decontamination were not considered in the lifetime external dose estimated. Decontamination is in progress for most living areas in Fukushima Prefecture, which could reduce long-term external dose to residents. This article mainly reviews recent English language articles that may add new information to the UNSCEAR and IAEA publications. Generally, recent articles suggest lower doses than those presented by the UNSCEAR 2013 report.

  19. Pathology effects at radiation doses below those causing increased mortality

    NASA Technical Reports Server (NTRS)

    Carnes, Bruce A.; Gavrilova, Natalia; Grahn, Douglas

    2002-01-01

    Mortality data from experiments conducted at the Argonne National Laboratory (ANL) on the long-term effects of external whole-body irradiation on B6CF(1) mice were used to investigate radiation-induced effects at intermediate doses of (60)Co gamma rays or fission-spectrum neutrons either delivered as a single exposure or protracted over 60 once-weekly exposures. Kaplan-Meier analyses were used to identify the lowest dose in the ANL data (within radiation quality, pattern of exposure, and sex) at which radiation-induced mortality caused by primary tumors could be detected (approximately 1-2 Gy for gamma rays and 10-15 cGy for neutrons). Doses at and below these levels were then examined for radiation-induced shifts in the spectrum of pathology detected at death. To do this, specific pathology events were pooled into larger assemblages based on whether they were cancer, cardiovascular disease or non-neoplastic diseases detected within the lungs and pleura, liver and biliary tract, reproductive organs, or urinary tract. Cancer and cardiovascular disease were further subdivided into categories based on whether they caused death, contributed to death, or were simply observed at death. Counts of how often events falling within each of these combined pathology categories occurred within a mouse were then used as predictor variables in logistic regression to determine whether irradiated mice could be distinguished from control mice. Increased pathology burdens were detected in irradiated mice at doses lower than those causing detectable shifts in mortality-22 cGy for gamma rays and 2 cGy for neutrons. These findings suggest that (1) models based on mortality data alone may underestimate radiation effects, (2) radiation may have adverse health consequences (i.e. elevated health risks) even when mortality risks are not detected, and (3) radiation-induced pathologies other than cancer do occur, and they involve multiple organ systems.

  20. Imaging practices and radiation doses from imaging in radiotherapy.

    PubMed

    Siiskonen, Teemu; Kaijaluoto, Sampsa; Florea, Tudor

    2017-03-25

    Modern radiotherapy treatments require frequent imaging for accurate patient positioning relative to the therapeutic radiation beam. Imaging practices in five Finnish radiotherapy clinics were assessed and discussed from the patient dose optimization point of view. The results show that imaging strategies are not jointly established and variations exist. The organ absorbed doses depend on imaging technique and imaging frequency. In particular, organ doses from the cone beam computed tomography can have very large variations (a factor of 10-50 in breast imaging and factor of 5 in prostate imaging). The cumulative imaging organ dose from the treatment can vary by a factor of ten or more for the same treatment, depending on the chosen technique and imaging frequency. Awareness and optimization of the imaging dose in image-guided radiotherapy should be strengthened.

  1. Estimated ultraviolet radiation doses in wetlands in six national parks

    USGS Publications Warehouse

    Diamond, S.A.; Trenham, P.C.; Adams, Michael J.; Hossack, B.R.; Knapp, R.A.; Stark, L.; Bradford, D.; Corn, P.S.; Czarnowski, K.; Brooks, P.D.; Fagre, D.B.; Breen, B.; Dentenbeck, N.E.; Tonnessen, K.

    2005-01-01

    Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m−2 (range of 3.4–32.1 W-h m−2). The mean dose was lowest in Acadia (13.7 W-h m−2) and highest in Rocky (24.4 W-h m−2). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm−2 (range 21.4–194.7 μW cm−2) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L−1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms.

  2. ULTRAVIOLET RADIATION DOSE AND AMPHIBIAN DISTRIBUTIONS IN NATIONAL PARKS

    EPA Science Inventory

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

  3. Integrated Worker Radiation Dose Assessment for the K Basins

    SciTech Connect

    NELSON, J.V.

    1999-10-27

    This report documents an assessment of the radiation dose workers at the K Basins are expected to receive in the process of removing spent nuclear fuel from the storage basins. The K Basins (K East and K West) are located in the Hanford 100K Area.

  4. Space radiation dose estimates on the surface of Mars.

    PubMed

    Simonsen, L C; Nealy, J E; Townsend, L W; Wilson, J W

    1990-01-01

    A future goal of the U.S. space program is a commitment to the manned exploration and habitation of Mars. An important consideration of such missions is the exposure of crew members to the damaging effects of ionizing radiation from high-energy galactic cosmic ray fluxes and solar proton flares. The crew will encounter the most harmful radiation environment in transit to Mars from which they must be adequately protected. However, once on the planet's surface, the Martian environment should provide a significant amount of protection from free-space radiative fluxes. In current Mars scenario descriptions, the crew flight time to Mars is estimated to be anywhere from 7 months to over a year each way, with stay times on the surface ranging from 20 days to 2 years. To maintain dose levels below established astronaut limits, dose estimates need to be determined for the entire mission length. With extended crew durations on the surface anticipated, the characterization of the Mars radiation environment is important in assessing all radiation protection requirements. This synopsis focuses on the probable doses incurred by surface inhabitants from the transport of galactic cosmic rays and solar protons through the Mars atmosphere.

  5. Scattered radiation doses to some critical organs during pediatric radiotherapy.

    PubMed

    Agard, E T; Ehlers, G; Kirchberg, S

    1985-04-01

    The levels of scattered radiation doses imparted to the eyes, thyroid and gonads of pediatric patients treated with orthovoltage radiation (300 kVp, 2.0 mmCu HVL) and with a 4-MV linear accelerator, were determined by making thermoluminescent dosimeter (TLD) measurements in three paraffin phantoms of different sizes. These phantoms were made from molds of mannequins used for store display, of approximate heights 30", 40" and 50", representing children of ages 1-2, 4-5 and 8-10 yr, respectively. The sites chosen for irradiation were (1) the whole brain, (2) the chest, (3) the kidney bed, (4) the whole abdomen and (5) the spinal column. These sites are normally treated in such pediatric malignancies as medulloblastoma, neuroblastoma and Wilms' tumor. Some of the doses measured are less than 10 rad for an entire treatment regimen, and would therefore be categorized as low-level doses. Where radiation was the only mode of treatment for long-term survivors of such malignancies, especially those treated 20-30 yr ago with orthovoltage radiation, useful data may be extracted for contributing to our knowledge about the long-term effects of low levels of radiation.

  6. Methionine Uptake and Required Radiation Dose to Control Glioblastoma

    SciTech Connect

    Iuchi, Toshihiko; Hatano, Kazuo; Uchino, Yoshio; Itami, Makiko; Hasegawa, Yuzo; Kawasaki, Koichiro; Sakaida, Tsukasa; Hara, Ryusuke

    2015-09-01

    Purpose: The purpose of this study was to retrospectively assess the feasibility of radiation therapy planning for glioblastoma multiforme (GBM) based on the use of methionine (MET) positron emission tomography (PET), and the correlation among MET uptake, radiation dose, and tumor control. Methods and Materials: Twenty-two patients with GBM who underwent MET-PET prior to radiation therapy were enrolled. MET uptake in 30 regions of interest (ROIs) from 22 GBMs, biologically effective doses (BEDs) for the ROIs and their ratios (MET uptake:BED) were compared in terms of whether the ROIs were controlled for >12 months. Results: MET uptake was significantly correlated with tumor control (odds ratio [OR], 10.0; P=.005); however, there was a higher level of correlation between MET uptake:BED ratio and tumor control (OR, 40.0; P<.0001). These data indicated that the required BEDs for controlling the ROIs could be predicted in terms of MET uptake; BED could be calculated as [34.0 × MET uptake] Gy from the optimal threshold of the MET uptake:BED ratio for tumor control. Conclusions: Target delineation based on MET-PET was demonstrated to be feasible for radiation therapy treatment planning. MET-PET could not only provide precise visualization of infiltrating tumor cells but also predict the required radiation doses to control target regions.

  7. Radiation Dose Estimation for Pediatric Patients Undergoing Cardiac Catheterization

    NASA Astrophysics Data System (ADS)

    Wang, Chu

    Patients undergoing cardiac catheterization are potentially at risk of radiation-induced health effects from the interventional fluoroscopic X-ray imaging used throughout the clinical procedure. The amount of radiation exposure is highly dependent on the complexity of the procedure and the level of optimization in imaging parameters applied by the clinician. For cardiac catheterization, patient radiation dosimetry, for key organs as well as whole-body effective, is challenging due to the lack of fixed imaging protocols, unlike other common X-ray based imaging modalities. Pediatric patients are at a greater risk compared to adults due to their greater cellular radio-sensitivities as well as longer remaining life-expectancy following the radiation exposure. In terms of radiation dosimetry, they are often more challenging due to greater variation in body size, which often triggers a wider range of imaging parameters in modern imaging systems with automatic dose rate modulation. The overall objective of this dissertation was to develop a comprehensive method of radiation dose estimation for pediatric patients undergoing cardiac catheterization. In this dissertation, the research is divided into two main parts: the Physics Component and the Clinical Component. A proof-of-principle study focused on two patient age groups (Newborn and Five-year-old), one popular biplane imaging system, and the clinical practice of two pediatric cardiologists at one large academic medical center. The Physics Component includes experiments relevant to the physical measurement of patient organ dose using high-sensitivity MOSFET dosimeters placed in anthropomorphic pediatric phantoms. First, the three-dimensional angular dependence of MOSFET detectors in scatter medium under fluoroscopic irradiation was characterized. A custom-made spherical scatter phantom was used to measure response variations in three-dimensional angular orientations. The results were to be used as angular dependence

  8. The Monte Carlo calculation of integral radiation dose in xeromammography.

    PubMed

    Dance, D R

    1980-01-01

    A Monte Carlo computer program has been developed for the computation of integral radiation dose to the breast in xeromammography. The results are given in terms of the integral dose per unit area of the breast per unit incident exposure. The calculations have been made for monoenergetic incident photons and the results integrated over a variety of X-ray spectra from both tungsten and molybdenum targets. This range incorporates qualities used in conventional and xeromammography. The program includes the selenium plate used in xeroradiography; the energy absorbed in this detector has also been investigated. The latter calculations have been used to predict relative values of exposure and of integral dose to the breast for xeromammograms taken at various radiation qualities. The results have been applied to recent work on the reduction of patient exposure in xeromammography by the addition of aluminium filters to the X-ray beam.

  9. Dose and volume impact on radiation-induced xerostomia.

    PubMed

    Marmiroli, Luca; Salvi, Giovanna; Caiazza, Adolfo; Di Rienzo, Luigi; Massaccesi, Mariangela; Murino, Paola; Macchia, Gabriella

    2005-01-01

    Radiation-induced xerostomia consists in the chronic dryness of the mouth caused by parotid gland irradiation. Parotid glands produce approximately 60% of saliva while the rest is secreted by submandibular and accessory salivary glands. Methods of measuring the salivary output are essentially represented by 99mTc-pertechnate scintigraphy or simpler albeit less accurate methods in stimulated or unstimulated saliva. There are subjective and objective criteria of classification and grading of the secretion of saliva. Radiation-induced xerostomia, namely the residual salivary gland function is evidently associated with the mean dose absorbed. The salivary output tends to decrease after the end of radiotherapy. The partial dose-volume is substantially correlated with the mean dose to the whole gland. As for ipsilateral irradiation for head and neck cancer, conformal RT or IMRT allow to spare the contralateral parotid gland without increasing the risk of contralateral nodal recurrences. The monitoring system of late toxicity used by the authors is presented.

  10. Can radiation therapy treatment planning system accurately predict surface doses in postmastectomy radiation therapy patients?

    SciTech Connect

    Wong, Sharon; Back, Michael; Tan, Poh Wee; Lee, Khai Mun; Baggarley, Shaun; Lu, Jaide Jay

    2012-07-01

    Skin doses have been an important factor in the dose prescription for breast radiotherapy. Recent advances in radiotherapy treatment techniques, such as intensity-modulated radiation therapy (IMRT) and new treatment schemes such as hypofractionated breast therapy have made the precise determination of the surface dose necessary. Detailed information of the dose at various depths of the skin is also critical in designing new treatment strategies. The purpose of this work was to assess the accuracy of surface dose calculation by a clinically used treatment planning system and those measured by thermoluminescence dosimeters (TLDs) in a customized chest wall phantom. This study involved the construction of a chest wall phantom for skin dose assessment. Seven TLDs were distributed throughout each right chest wall phantom to give adequate representation of measured radiation doses. Point doses from the CMS Xio Registered-Sign treatment planning system (TPS) were calculated for each relevant TLD positions and results correlated. There were no significant difference between measured absorbed dose by TLD and calculated doses by the TPS (p > 0.05 (1-tailed). Dose accuracy of up to 2.21% was found. The deviations from the calculated absorbed doses were overall larger (3.4%) when wedges and bolus were used. 3D radiotherapy TPS is a useful and accurate tool to assess the accuracy of surface dose. Our studies have shown that radiation treatment accuracy expressed as a comparison between calculated doses (by TPS) and measured doses (by TLD dosimetry) can be accurately predicted for tangential treatment of the chest wall after mastectomy.

  11. Monte Carlo dose enhancement studies in microbeam radiation therapy

    SciTech Connect

    Martinez-Rovira, I.; Prezado, Y.

    2011-07-15

    Purpose: A radical radiation therapy treatment for gliomas requires extremely high absorbed doses resulting in subsequent deleterious side effects in healthy tissue. Microbeam radiation therapy (MRT) is an innovative technique based on the fact that normal tissue can withstand high radiation doses in small volumes without any significant damage. The synchrotron-generated x-ray beam is collimated and delivered to an array of narrow micrometer-sized planar rectangular fields. Several preclinical experiments performed at the Brookhaven National Laboratory (BNL) and at the European Synchrotron Radiation Facility (ESRF) confirmed that MRT yields a higher therapeutic index than nonsegmented beams of the same characteristics. This index can be greatly improved by loading the tumor with high atomic number (Z) contrast agents. The aim of this work is to find the high-Z element that provides optimum dose enhancement. Methods: Monte Carlo simulations (PENELOPE/penEasy) were performed to assess the peak and valley doses as well as their ratio (PVDR) in healthy tissue and in the tumor, loaded with different contrast agents. The optimization criteria used were maximization of the ratio between the PVDR values in healthy tissue respect to the PVDR in the tumor and minimization of bone and brain valley doses. Results: Dose enhancement factors, PVDR, and valley doses were calculated for different high-Z elements. A significant decrease of PVDR values in the tumor, accompanied by a gain in the valley doses, was found in the presence of high-Z elements. This enables the deposited dose in the healthy tissue to be reduced. The optimum high-Z element depends on the irradiation configuration. As a general trend, the best outcome is provided by the highest Z contrast agents considered, i.e., gold and thallium. However, lanthanides (especially Lu) and hafnium also offer a satisfactory performance. Conclusions: The remarkable therapeutic index in microbeam radiation therapy can be further

  12. PET/CT-guided Interventions: Personnel Radiation Dose

    SciTech Connect

    Ryan, E. Ronan Thornton, Raymond; Sofocleous, Constantinos T.; Erinjeri, Joseph P.; Hsu, Meier; Quinn, Brian; Dauer, Lawrence T.; Solomon, Stephen B.

    2013-08-01

    PurposeTo quantify radiation exposure to the primary operator and staff during PET/CT-guided interventional procedures.MethodsIn this prospective study, 12 patients underwent PET/CT-guided interventions over a 6 month period. Radiation exposure was measured for the primary operator, the radiology technologist, and the nurse anesthetist by means of optically stimulated luminescence dosimeters. Radiation exposure was correlated with the procedure time and the use of in-room image guidance (CT fluoroscopy or ultrasound).ResultsThe median effective dose was 0.02 (range 0-0.13) mSv for the primary operator, 0.01 (range 0-0.05) mSv for the nurse anesthetist, and 0.02 (range 0-0.05) mSv for the radiology technologist. The median extremity dose equivalent for the operator was 0.05 (range 0-0.62) mSv. Radiation exposure correlated with procedure duration and with the use of in-room image guidance. The median operator effective dose for the procedure was 0.015 mSv when conventional biopsy mode CT was used, compared to 0.06 mSv for in-room image guidance, although this did not achieve statistical significance as a result of the small sample size (p = 0.06).ConclusionThe operator dose from PET/CT-guided procedures is not significantly different than typical doses from fluoroscopically guided procedures. The major determinant of radiation exposure to the operator from PET/CT-guided interventional procedures is time spent in close proximity to the patient.

  13. Modeling Dose-response at Low Dose: A Systems Biology Approach for Ionization Radiation.

    PubMed

    Zhao, Yuchao; Ricci, Paolo F

    2010-03-18

    For ionization radiation (IR) induced cancer, a linear non-threshold (LNT) model at very low doses is the default used by a number of national and international organizations and in regulatory law. This default denies any positive benefit from any level of exposure. However, experimental observations and theoretical biology have found that both linear and J-shaped IR dose-response curves can exist at those very low doses. We develop low dose J-shaped dose-response, based on systems biology, and thus justify its use regarding exposure to IR. This approach incorporates detailed, molecular and cellular descriptions of biological/toxicological mechanisms to develop a dose-response model through a set of nonlinear, differential equations describing the signaling pathways and biochemical mechanisms of cell cycle checkpoint, apoptosis, and tumor incidence due to IR. This approach yields a J-shaped dose response curve while showing where LNT behaviors are likely to occur. The results confirm the hypothesis of the J-shaped dose response curve: the main reason is that, at low-doses of IR, cells stimulate protective systems through a longer cell arrest time per unit of IR dose. We suggest that the policy implications of this approach are an increasingly correct way to deal with precautionary measures in public health.

  14. Radiation doses from computed tomography practice in Johor Bahru, Malaysia

    NASA Astrophysics Data System (ADS)

    Karim, M. K. A.; Hashim, S.; Bradley, D. A.; Bakar, K. A.; Haron, M. R.; Kayun, Z.

    2016-04-01

    Radiation doses for Computed Tomography (CT) procedures have been reported, encompassing a total of 376 CT examinations conducted in one oncology centre (Hospital Sultan Ismail) and three diagnostic imaging departments (Hospital Sultanah Aminah, Hospital Permai and Hospital Sultan Ismail) at Johor hospital's. In each case, dose evaluations were supported by data from patient questionnaires. Each CT examination and radiation doses were verified using the CT EXPO (Ver. 2.3.1, Germany) simulation software. Results are presented in terms of the weighted computed tomography dose index (CTDIw), dose length product (DLP) and effective dose (E). The mean values of CTDIw, DLP and E were ranged between 7.6±0.1 to 64.8±16.5 mGy, 170.2±79.2 to 943.3±202.3 mGy cm and 1.6±0.7 to 11.2±6.5 mSv, respectively. Optimization techniques in CT are suggested to remain necessary, with well-trained radiology personnel remaining at the forefront of such efforts.

  15. Contribution of maternal radionuclide burdens to prenatal radiation doses

    SciTech Connect

    Sikov, M.R.; Hui, T.E.

    1996-05-01

    This report describes approaches to calculating and expressing radiation doses to the embryo/fetus from internal radionuclides. Information was obtained for selected, occupationally significant radioelements that provide a spectrum of metabolic and dosimetric characteristics. Evaluations are also presented for inhaled inert gases and for selected radiopharmaceuticals. Fractional placental transfer and/or ratios of concentration in the embryo/fetus to that in the woman were calculated for these materials. The ratios were integrated with data from biokinetic transfer models to estimate radioactivity levels in the embryo/fetus as a function of stage of pregnancy and time after entry into the transfer compartment or blood of the pregnant woman. These results are given as tables of deposition and retention in the embryo/fetus as a function of gestational age at exposure and elapsed time following exposure. Methodologies described by MIRD were extended to formalize and describe details for calculating radiation absorbed doses to the embryo/fetus. Calculations were performed using a model situation that assumed a single injection of 1 {mu}Ci into a woman`s blood; independent calculations were performed for administration at successive months of pregnancy. Gestational -stage-dependent dosimetric tabulations are given together with tables of correlations and relationships. Generalized surrogate dose factors and categorizations are provided in the report to provide for use in operational radiological protection situations. These approaches to calculation yield radiation absorbed doses that can be converted to dose equivalent by multiplication by quality factor. Dose equivalent is the most common quantity for stating prenatal dose limits in the United States and is appropriate for the types of effect that are usually associated with prenatal exposure. If it is desired to obtain alternatives for other purposes, this value can be multiplied by appropriate weighting factors.

  16. Overview of Graphical User Interface for ARRBOD (Acute Radiation Risk and BRYNTRN Organ Dose Projection)

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Hee Y.; Hu, Shaowen; Nounu, Hatem; Cucinotta, Francis A.

    Solar particle events (SPEs) pose the risk of acute radiation sickness (ARS) to astronauts be-cause organ doses from large SPEs may reach critical levels during extra vehicular activities (EVAs) or lightly shielded spacecraft. NASA has developed an organ dose projection model of Baryon transport code (BRYNTRN) with an output data processing module of SUMDOSE, and a probabilistic model of acute radiation risk (ARR). BRYNTRN code operation requires extensive input preparation, and the risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations. With a graphical user interface (GUI) to handle input and output for BRYNTRN, these response models can be connected easily and correctly to BRYNTRN in a user-friendly way. The GUI for the Acute Radiation Risk and BRYNTRN Organ Dose (ARRBOD) projection code provides seamless integration of input and output manipulations required for operations of the ARRBOD modules: BRYNTRN, SUMDOSE, and the ARR probabilistic response model. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations direc-torate (MOD), and space biophysics researchers. Assessment of astronauts' organ doses and ARS from the exposure to historically large SPEs is in support of mission design and opera-tion planning to avoid ARS and stay within the current NASA short-term dose limits. The ARRBOD GUI will serve as a proof-of-concept for future integration of other risk projection models for human space applications. We present an overview of the ARRBOD GUI prod-uct, which is a new self-contained product, for the major components of the overall system, subsystem interconnections, and external interfaces.

  17. Overview of Graphical User Interface for ARRBOD (Acute Radiation Risk and BRYNTRN Organ Dose Projection)

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Hu, Shaowen; Nounu, Hatem N.; Cucinotta, Francis A.

    2010-01-01

    Solar particle events (SPEs) pose the risk of acute radiation sickness (ARS) to astronauts, because organ doses from large SPEs may reach critical levels during extra vehicular activities (EVAs) or lightly shielded spacecraft. NASA has developed an organ dose projection model of Baryon transport code (BRYNTRN) with an output data processing module of SUMDOSE, and a probabilistic model of acute radiation risk (ARR). BRYNTRN code operation requires extensive input preparation, and the risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations. With a graphical user interface (GUI) to handle input and output for BRYNTRN, these response models can be connected easily and correctly to BRYNTRN in a user friendly way. The GUI for the Acute Radiation Risk and BRYNTRN Organ Dose (ARRBOD) projection code provides seamless integration of input and output manipulations required for operations of the ARRBOD modules: BRYNTRN, SUMDOSE, and the ARR probabilistic response model. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations directorate (MOD), and space biophysics researchers. Assessment of astronauts organ doses and ARS from the exposure to historically large SPEs is in support of mission design and operation planning to avoid ARS and stay within the current NASA short-term dose limits. The ARRBOD GUI will serve as a proof-of-concept for future integration of other risk projection models for human space applications. We present an overview of the ARRBOD GUI product, which is a new self-contained product, for the major components of the overall system, subsystem interconnections, and external interfaces.

  18. Worldwide forecast of the biologically effective UV radiation: UV index and daily dose

    NASA Astrophysics Data System (ADS)

    Schmalwieser, Alois W.; Schauberger, Guenther; Janouch, Michal; Nunez, Manuel; Koskela, Tapani; Berger, Daniel; Karamanian, Gabriel; Prosek, Pavel; Laska, Kamil

    2002-01-01

    Since October 1995 a global daily forecast of the UV index and the daily dose, as the irradiance of the biologically effective ultraviolet radiation, for clear sky is calculated. The Austrian model as well as the input parameters are described. By connecting the daily dose with the sensitivity of the photobiological skin types, a recommendation is given to select an appropriate sun protection factor of a sunscreen to avoid overexposure of the skin. The validation of the Austrian forecast model is done by long-term measurements of the biologically effective ultraviolet radiation. Measurements were taken from 6 different sites at 4 continents (Antarctica, Australia, America and Europe) covering the latitudinal range from 67 degree(s)N to 60 degree(s)S. By using the underestimation as criteria in the sense of radiation protection, the Austrian model shows less than 12% underestimation over the whole period for the UV index and less than 10% for the daily dose. The evaluation shows further that the forecast of the daily dose is much more influenced by the attenuation due to clouds than the UV index.

  19. Low dose ionizing radiation detection using conjugated polymers

    SciTech Connect

    Silva, E.A.B.; Borin, J.F.; Nicolucci, P.; Graeff, C.F.O.; Netto, T. Ghilardi; Bianchi, R.F.

    2005-03-28

    In this work, the effect of gamma radiation on the optical properties of poly[2-methoxy-5-(2{sup '}-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) is studied. The samples were irradiated at room temperature with different doses from 0 Gy to 152 Gy using a {sup 60}Co gamma ray source. For thin films, significant changes in the UV-visible spectra were only observed at high doses (>1 kGy). In solution, shifts in absorption peaks are observed at low doses (<10 Gy), linearly dependent on dose. The shifts are explained by conjugation reduction, and possible causes are discussed. Our results indicate that MEH-PPV solution can be used as a dosimeter adequate for medical applications.

  20. Effects of ionizing radiation and restraint stress on activity, avoidance conditioning, and stomach ulcers in albino rats. Final report October 1980-December 1981

    SciTech Connect

    Lanum, J.; Blick, D.W.; Campbell, M.E.; Wheeler, T.G.; Koger, S.A.

    1984-03-01

    In an experiment with albino rats, we have tried to model a nuclear attack scenario in which military personnel receiving 600 to 800 rads of ionizing radiation would be making a counterattack under the stress of an emergency situation. We used a dose of radiation that, though higher than the human exposure field, was estimated to be its physiological equivalent. Restraining the rat in an immobile position, a technique previously shown to have stressing qualities for rats, was chosen as an analogy to the stress of being in a war emergency. Activity and conditioned avoidance acquisition were chosen as test responses. Performance in the activity maze was affected only to a minor degree and in the direction of considering irradiation as activating. However, all irradiated groups showed retarded conditioned avoidance acquisition, which can be interpreted as decreased adaptability to a stressful situation. Further, our results support the expectation of performance decrements in the military scenario that could not be predicted by considering ionizing radiation in isolation. On the avoidance task, male rats in the combination stress-irradiation condition showed more failures to respond and longer response latencies than any other group. Female rats, on the other hand, showed shorter escape/avoidance latencies in the combined stress-irradiation condition than in the irradiation condition alone. This sex difference may be useful as a clue for investigating mechanisms of radiation resistance and interactions between stressors.

  1. Kinetics of avoidance of simulated solar uv radiation by two arthropods

    SciTech Connect

    Barcelo, J.A.; Calkins, J.

    1980-12-01

    There is an increasing likelihood that the solar uv-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar uv-B to withstand full summer sunlight and thus mechanisms which facilitate avoidance of solar uv-B exposure may have significance for the survival of sensitive species. There are many alternative pathways which would lead to avoidance of solar uv-B. We have investigated the dynamics of biological reactions to simulated solar uv-B radiation in two small arthropods, the two-spotted spider mite Tetranychus urticae Koch and the aquatic copepod Cyclops serrulatus. Observations of positioning and rate of movement were made; a mathematical formalism was developed which assisted in interpretation of the observations. Our observations suggest that, although avoidance would mitigate increased solar uv-B effects, even organisms which specifically reduce their uv-B exposure would encounter additional stress if ozone depletion does occur.

  2. Radiation environments and absorbed dose estimations on manned space missions.

    PubMed

    Curtis, S B; Atwell, W; Beever, R; Hardy, A

    1986-01-01

    In order to make an assessment of radiation risk during manned missions in space, it is necessary first to have as accurate an estimation as possible of the radiation environment within the spacecraft to which the astronauts will be exposed. Then, with this knowledge and the inclusion of body self-shielding, estimations can be made of absorbed doses for various body organs (skin, eye, blood-forming organs, etc.). A review is presented of our present knowledge of the radiation environments and absorbed doses expected for several space mission scenarios selected for our development of the new radiation protection guidelines. The scenarios selected are a 90-day mission at an altitude (450 km) and orbital inclinations (28.5 degrees, 57 degrees and 90 degrees) appropriate for NASA's Space Station, a 15-day sortie to geosynchronous orbit and a 90-day lunar mission. All scenarios chosen yielded dose equivalents between five and ten rem to the blood forming organs if no large solar particle event were encountered. Such particle events could add considerable exposure particularly to the skin and eye for all scenarios except the one at 28.5 degrees orbital inclination.

  3. Prefecture-wide multi-centre radiation dose survey as a useful tool for CT dose optimisation: report of Gunma radiation dose study.

    PubMed

    Fukushima, Yasuhiro; Taketomi-Takahashi, Ayako; Nakajima, Takahito; Tsushima, Yoshito

    2015-12-01

    The aim of this study was to verify the usefulness for the dose optimisation of setting a diagnostic reference level (DRL) based on the results of a prefecture-wide multi-centre radiation dose survey and providing data feedback. All hospitals/clinics in the authors' prefecture with computed tomography (CT) scanners were requested to report data. The first survey was done in July 2011, and the results of dose-length products (DLPs) for each CT scanner were fed back to all hospitals/clinics, with DRL set from all the data. One year later, a second survey was done in the same manner. The medians of DLP in the upper abdomen, whole body and coronary CT in 2012 were significantly smaller than those of the 2011 survey. The interquartile ranges of DLP in the head, chest, pelvis and coronary CT were also smaller in 2012. Radiation dose survey with data feedback may be helpful for CT dose optimisation.

  4. Galactic cosmic ray-induced radiation dose on terrestrial exoplanets.

    PubMed

    Atri, Dimitra; Hariharan, B; Grießmeier, Jean-Mathias

    2013-10-01

    This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground- and space-based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets that reside in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Planetary systems around M dwarfs are considered to be prime candidates to search for life beyond the Solar System. Such planets are likely to be tidally locked and have close-in habitable zones. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in the case of super-Earths. Such exoplanets are subjected to a high flux of galactic cosmic rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin that strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another factor governing the radiation dose is the depth of the planetary atmosphere. The higher the depth of the planetary atmosphere, the lower the flux of secondary particles will be on the surface. If the secondary particles are energetic enough, and their flux is sufficiently high, the radiation from muons can also impact the subsurface regions, such as in the case of Mars. If the radiation dose is too high, the chances of sustaining a long-term biosphere on the planet are very low. We have examined the dependence of the GCR-induced radiation dose on the strength of the planetary magnetic field and its atmospheric depth, and found that the latter is the decisive factor for the protection of a planetary biosphere.

  5. Optimal Treatment for Intracranial Germinoma: Can We Lower Radiation Dose Without Chemotherapy?

    SciTech Connect

    Yen, Sang-Hue; Chen, Yi-Wei; Huang, Pin-I

    2010-07-15

    Purpose: To review the effectiveness of reduced-dose and restricted-volume radiation-only therapy in the treatment of intracranial germinoma and to assess the feasibility of reducing or eliminating the use of chemotherapy. Methods and Materials: Between January 1996 and March 2007, a retrospective analysis was performed that included 38 patients who received either reduced radiation alone (30 Gy for 26 patients) or reduced radiation with chemotherapy (n = 12 patients). All 38 patients received extended focal (including whole-ventricle) irradiation and were followed up until February 2008. Overall survival (OS) and relapse-free survival (RFS) rates were calculated. Variables associated with survival were evaluated by univariate Cox proportional hazards regression. Results: Median follow-up was 62.4 months (range, 10.1-142.5 months). The total 5-year OS rate was 93.7%. The 5-year OS and RFS rates for patients receiving radiation only were 100% and 96.2%, respectively. The rates for those receiving radiation plus chemotherapy were 83.3 % and 91.7%, respectively (not statistically significant). No predictive factor was significantly associated with the OS or RFS rate. Chemotherapy had no significant effect on survival but was associated with a higher incidence of treatment-related toxicity. Conclusions: A further decrease in the radiation dose to 30 Gy with whole-ventricle irradiation is sufficient to treat selected patients with intracranial germinoma. Wide-field irradiation or chemotherapy should be avoided as these methods are unnecessary. Thus, reduction of the radiation dose to 30 Gy may be feasible, even without chemotherapy.

  6. Radiation dose to the embryo/fetus: Draft Regulatory Guide DG-8011

    SciTech Connect

    Not Available

    1992-02-01

    Section 20.1208 of 10 CFR Part 20, ``Standards for Protection Against Radiation,`` requires that each licensee ensure that the dose to an embryo/fetus during the entire pregnancy, from occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv). Paragraph 20.1208(b) requires the licensee to make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman that would satisfy the 0.5 rem limit. The dose to the embryo/fetus is to be the sum of (1) the deep-dose equivalent to the declared pregnant woman (10 CFR 10.1208(c)(1)) and (2) the dose to the embryo/fetus from radionuclides in the embryo/fetus and radionuclides in the declared pregnant woman (10 CFR 20.1208(c)(2)). This guide is being developed to provide guidance on calculating the radiation dose to the embryo/fetus.

  7. Radiation dose to the embryo/fetus: Draft Regulatory Guide DG-8011

    SciTech Connect

    Not Available

    1992-02-01

    Section 20.1208 of 10 CFR Part 20, Standards for Protection Against Radiation,'' requires that each licensee ensure that the dose to an embryo/fetus during the entire pregnancy, from occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv). Paragraph 20.1208(b) requires the licensee to make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman that would satisfy the 0.5 rem limit. The dose to the embryo/fetus is to be the sum of (1) the deep-dose equivalent to the declared pregnant woman (10 CFR 10.1208(c)(1)) and (2) the dose to the embryo/fetus from radionuclides in the embryo/fetus and radionuclides in the declared pregnant woman (10 CFR 20.1208(c)(2)). This guide is being developed to provide guidance on calculating the radiation dose to the embryo/fetus.

  8. Radiation absorbed dose estimates for 18F-BPA PET.

    PubMed

    Kono, Yuzuru; Kurihara, Hiroaki; Kawamoto, Hiroshi; Yasui, Naoko; Honda, Naoki; Igaki, Hiroshi; Itami, Jun

    2017-01-01

    Background Boron neutron capture therapy (BNCT) is a molecular radiation therapy approach based on the (10)B (n, α) (7)Li nuclear reaction in cancer cells. In BNCT, delivery of (10)B in the form of 4-borono-phenylalanine conjugated with fructose (BPA-fr) to the cancer cells is important. The PET tracer 4-borono-2-18F-fluoro-phenylalanine (FBPA) has been used to predict the accumulation of BPA-fr before BNCT. Purpose To determine the biodistribution and dosimetric parameters in 18F-BPA PET/CT studies. Material and Methods Human biokinetic data were obtained during clinical 18F-BPA PET studies between February and June 2015 at one institution. Nine consecutive patients were studied prospectively. The internal radiation dose was calculated on the basis of radioactivity data from blood, urine, and normal tissue of the heart, liver, spleen, kidney, and other parts of the body at each time point using OLINDA/EXM1.1 program. We compared our calculations with published 18F-FDG data. Results Adult patients (3 men, 3 women; age range, 28-68 years) had significantly smaller absorbed doses than pediatric patients (3 patients; age range, 5-12 years) ( P = 0.003). The mean effective dose was 57% lower in adult patients compared with pediatric patients. Mean effective doses for 18F-BPA were 25% lower than those for 18F-FDG presented in International Commission of Radiation Protection (ICRP) publication 106. Conclusion We found significant differences in organ absorbed doses for 18F-BPA against those for 18F-FDG presented in ICRP publication 106. Mean effective doses for 18F-BPA were smaller than those for 18F-FDG in the publication by 0.5-38% (mean difference, 25%).

  9. Strategies to reduce radiation dose in cardiac PET/CT

    NASA Astrophysics Data System (ADS)

    Wu, Tung Hsin; Wu, Nien-Yun; Wang, Shyh-Jen; Wu, Jay; S. P. Mok, Greta; Yang, Ching-Ching; Huang, Tzung-Chi

    2011-08-01

    Our aim was to investigate CT dose reduction strategies on a hybrid PET/CT scanner for cardiac applications.MaterialsImage quality and dose estimation of different CT scanning protocols for CT coronary angiography (CTCA), and CT-based attenuation correction for PET imaging were investigated. Fifteen patients underwent CTCA, perfusion PET imaging at rest and under stress, and FDG PET for myocardial viability. These patients were divided into three groups based on the CTCA technique performed: retrospectively gated helical (RGH), ECG tube current modulation (ETCM), and prospective gated axial (PGA) acquisitions. All emission images were corrected for photon attenuation using CT images obtained by default setting and an ultra-low dose CT (ULDCT) scan.ResultsRadiation dose in RGH technique was 22.2±4.0 mSv. It was reduced to 10.95±0.82 and 4.13±0.31 mSv using ETCM and PGA techniques, respectively. Radiation dose in CT transmission scan was reduced by 96.5% (from 4.53±0.5 to 0.16±0.01 mSv) when applying ULDCT as compared to the default CT. No significant difference in terms of image quality was found among various protocols.ConclusionThe proposed CT scanning strategies, i.e. ETCM or PGA for CTCA and ULDCT for PET attenuation correction, could reduce radiation dose up to 47% without degrading imaging quality in an integrated cardiac PET/CT coronary artery examination.

  10. Occupational doses in radiation oncology in Manitoba--1980 to 1986

    SciTech Connect

    Huda, W.; Bews, J.; Sourkes, A.M. )

    1989-10-01

    The province of Manitoba (population of 1.0 million) has two radiotherapy centers employing a number of people, of whom about 60 are exposed to radiation during the course of their work. The individual and collective radiation doses to these workers, as recorded by thermoluminescent dosimeter plaques, were reviewed for the period 1980 to 1986. Whole-body doses to radiotherapy technologists responsible for operating the treatment machines and brachytherapy afterloading procedures ranged from 0.5 to 2.5 mSv y-1, whereas the corresponding doses to nursing staff working on a hospital brachytherapy ward were about 1.0 mSv y-1. The collective occupational dose from radiotherapy in Manitoba was approximately 70 person-mSv. Trends show individual operator and collective doses to be increasing at a higher rate than the number of patients undergoing radiotherapy. Occupational exposure in radiotherapy in this province was found to be comparable to that encountered in nuclear medicine in Manitoba and greater than that in diagnostic radiology.

  11. Biological detection of low radiation doses with integrated photothermal assay

    NASA Astrophysics Data System (ADS)

    Zharov, Vladimir P.; Viegas, Mark; Soderberg, Lee S. F.

    2005-04-01

    The goal of this paper was to evaluate the diagnostic value of integrated photothermal (PT) assay with additional fluorescent and photoacoustic (PA) modules to assess both the "safety limit" of exposure to ionizing γ-radiation and optimal therapeutic doses for cancer treatment. With this assay, the influences of γ irradiation on cancer cells (pancreatic-AR42J and hepatocytes-hepG2) and healthy cells (mouse lymphocytes and erythrocytes) was examined as a function of exposure dose (0.6-5 Gy) and time after irradiation, in vitro and in vivo. Independent verification of data obtained with conventional assays revealed that integrated PT assay allowed us to detect the different stages of radiation impact, including changes in cell metabolism at low dose, or stages related to cell death (apoptosis and necrosis) at high doses with a threshold sensitivity of at least three orders of magnitude better than existing assays. Also, PT assay was capable of quantitatively differentiating the biological action of γ irradiation alone and in combination with drug and nicotine impact. Finally, we demonstrated on an animal model that IPT assay has the potential for use in routine rapid evaluation of biological consequences of low-dose exposure a few days after irradiation.

  12. Problems in evaluating radiation dose via terrestrial and aquatic pathways.

    PubMed

    Vaughan, B E; Soldat, J K; Schreckhise, R G; Watson, E C; McKenzie, D H

    1981-12-01

    This review is concerned with exposure risk and the environmental pathways models used for predictive assessment of radiation dose. Exposure factors, the adequacy of available data, and the model subcomponents are critically reviewed from the standpoint of absolute error propagation. Although the models are inherently capable of better absolute accuracy, a calculated dose is usually overestimated by from two to six orders of magnitude, in practice. The principal reason for so large an error lies in using "generic" concentration ratios in situations where site specific data are needed. Major opinion of the model makers suggests a number midway between these extremes, with only a small likelihood of ever underestimating the radiation dose. Detailed evaluations are made of source considerations influencing dose (i.e., physical and chemical status of released material); dispersal mechanisms (atmospheric, hydrologic and biotic vector transport); mobilization and uptake mechanisms (i.e., chemical and other factors affecting the biological availability of radioelements); and critical pathways. Examples are shown of confounding in food-chain pathways, due to uncritical application of concentration ratios. Current thoughts of replacing the critical pathways approach to calculating dose with comprehensive model calculations are also shown to be ill-advised, given present limitations in the comprehensive data base. The pathways models may also require improved parametrization, as they are not at present structured adequately to lend themselves to validation. The extremely wide errors associated with predicting exposure stand in striking contrast to the error range associated with the extrapolation of animal effects data to the human being.

  13. Radiation doses from Hanford site releases to the atmosphere

    SciTech Connect

    Farris, W.T.; Napier, B.A.; Ikenberry, T.A.

    1994-06-01

    Radiation doses to individuals were estimated for the years 1944-1992. The dose estimates were based on the radioactive-releases from the Hanford Site in south central Washington. Conceptual models and computer codes were used to reconstruct doses through the early 1970s. The published Hanford Site annual environmental data were used to complete the does history through 1992. The most significant exposure pathway was found to be the consumption of cow`s milk containing iodine-131. For the atmospheric pathway, median cumulative dose estimates to the thyroid of children ranged from < 0.1 to 235 rad throughout the area studied. The geographic distribution of the dose levels was directly related to the pattern of iodine-131 deposition and was affected by the distribution of commercial milk and leafy vegetables. For the atmospheric pathway, the-highest estimated cumulative-effective-dose-equivalent (EDE) to an adult was estimated to be 1 rem at Ringold, Washington for the period 1944-1992. For the Columbia River pathway, cumulative EDE estimates ranged from <0.5 to l.5 rem cumulative dose to maximally exposed adults downriver from the Hanford Site for the years 1944-1992. The most significant river exposure pathway was consumption of resident fish containing phosphorus-32 and zinc-65.

  14. Non-uniform dose distributions in cranial radiation therapy

    NASA Astrophysics Data System (ADS)

    Bender, Edward T.

    Radiation treatments are often delivered to patients with brain metastases. For those patients who receive radiation to the entire brain, there is a risk of long-term neuro-cognitive side effects, which may be due to damage to the hippocampus. In clinical MRI and CT scans it can be difficult to identify the hippocampus, but once identified it can be partially spared from radiation dose. Using deformable image registration we demonstrate a semi-automatic technique for obtaining an estimated location of this structure in a clinical MRI or CT scan. Deformable image registration is a useful tool in other areas such as adaptive radiotherapy, where the radiation oncology team monitors patients during the course of treatment and adjusts the radiation treatments if necessary when the patient anatomy changes. Deformable image registration is used in this setting, but there is a considerable level of uncertainty. This work represents one of many possible approaches at investigating the nature of these uncertainties utilizing consistency metrics. We will show that metrics such as the inverse consistency error correlate with actual registration uncertainties. Specifically relating to brain metastases, this work investigates where in the brain metastases are likely to form, and how the primary cancer site is related. We will show that the cerebellum is at high risk for metastases and that non-uniform dose distributions may be advantageous when delivering prophylactic cranial irradiation for patients with small cell lung cancer in complete remission.

  15. Spine stereotactic body radiation therapy plans: Achieving dose coverage, conformity, and dose falloff.

    PubMed

    Hong, Linda X; Shankar, Viswanathan; Shen, Jin; Kuo, Hsiang-Chi; Mynampati, Dinesh; Yaparpalvi, Ravindra; Goddard, Lee; Basavatia, Amar; Fox, Jana; Garg, Madhur; Kalnicki, Shalom; Tomé, Wolfgang A

    2015-01-01

    We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage—prescription dose (PD) to cover at least 95% planning target volume (PTV) and 90% PD to cover at least 99% PTV; (2) conformity index (CI)—ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff—ratio of 50% PIV to the PTV (R(50%)); (4) and maximum dose in percentage of PD at 2 cm from PTV in any direction (D(2cm)) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ(2) test was used to examine the difference in parameters between groups. The PTV V(100% PD) ≥ 95% objective was met in 29.0% of group 1 vs 91.4% of group 2 (p < 0.01) plans. The PTV V(90% PD) ≥ 99% objective was met in 38.7% of group 1 vs 88.6% of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D(2cm), 48.3% plans yielded a minor violation of the objectives and 16.1% a major violation for group 1, whereas 17.1% exhibited a minor violation and 2.9% a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.

  16. Radiation leakage dose from Elekta electron collimation system.

    PubMed

    Pitcher, Garrett M; Hogstrom, Kenneth R; Carver, Robert L

    2016-09-08

    This study provided baseline data required for a greater project, whose objective was to design a new Elekta electron collimation system having significantly lighter electron applicators with equally low out-of field leakage dose. Specifically, off-axis dose profiles for the electron collimation system of our uniquely configured Elekta Infinity accelerator with the MLCi2 treatment head were measured and calculated for two primary purposes: 1) to evaluate and document the out-of-field leakage dose in the patient plane and 2) to validate the dose distributions calculated using a BEAMnrc Monte Carlo (MC) model for out-of-field dose profiles. Off-axis dose profiles were measured in a water phantom at 100 cm SSD for 1 and 2 cm depths along the in-plane, cross-plane, and both diagonal axes using a cylindrical ionization chamber with the 10 × 10 and 20 × 20 cm2 applicators and 7, 13, and 20 MeV beams. Dose distributions were calculated using a previously developed BEAMnrc MC model of the Elekta Infinity accelerator for the same beam energies and applicator sizes and compared with measurements. Measured results showed that the in-field beam flatness met our acceptance criteria (± 3% on major and ±4% on diagonal axes) and that out-of-field mean and maximum percent leakage doses in the patient plane met acceptance criteria as specified by the International Electrotechnical Commission (IEC). Cross-plane out-of-field dose profiles showed greater leakage dose than in-plane profiles, attributed to the curved edges of the upper X-ray jaws and multileaf collimator. Mean leakage doses increased with beam energy, being 0.93% and 0.85% of maximum central axis dose for the 10 × 10 and 20 × 20 cm2 applicators, respectively, at 20 MeV. MC calculations predicted the measured dose to within 0.1% in most profiles outside the radiation field; however, excluding model-ing of nontrimmer applicator components led to calculations exceeding measured data by as much as 0.2% for some regions

  17. The consequence of day-to-day stochastic dose deviation from the planned dose in fractionated radiation therapy.

    PubMed

    Paul, Subhadip; Roy, Prasun Kumar

    2016-02-01

    Radiation therapy is one of the important treatment procedures of cancer. The day-to-day delivered dose to the tissue in radiation therapy often deviates from the planned fixed dose per fraction. This day-to-day variation of radiation dose is stochastic. Here, we have developed the mathematical formulation to represent the day-to-day stochastic dose variation effect in radiation therapy. Our analysis shows that that the fixed dose delivery approximation under-estimates the biological effective dose, even if the average delivered dose per fraction is equal to the planned dose per fraction. The magnitude of the under-estimation effect relies upon the day-to-day stochastic dose variation level, the dose fraction size and the values of the radiobiological parameters of the tissue. We have further explored the application of our mathematical formulation for adaptive dose calculation. Our analysis implies that, compared to the premise of the Linear Quadratic Linear (LQL) framework, the Linear Quadratic framework based analytical formulation under-estimates the required dose per fraction necessary to produce the same biological effective dose as originally planned. Our study provides analytical formulation to calculate iso-effect in adaptive radiation therapy considering day-to-day stochastic dose deviation from planned dose and also indicates the potential utility of LQL framework in this context.

  18. TU-F-12A-04: Differential Radiation Avoidance of Functional Liver Regions Defined by 99mTc-Sulfur Colloid SPECT/CT with Proton Therapy

    SciTech Connect

    Bowen, S; Miyaoka, R; Kinahan, P; Sandison, G; Vesselle, H; Nyflot, M; Apisarnthanarax, S; Saini, J; Wong, T

    2014-06-15

    Purpose: Radiotherapy for hepatocellular carcinoma patients is conventionally planned without consideration of spatial heterogeneity in hepatic function, which may increase risk of radiation-induced liver disease. Pencil beam scanning (PBS) proton radiotherapy (pRT) plans were generated to differentially decrease dose to functional liver volumes (FLV) defined on [{sup 99m}Tc]sulfur colloid (SC) SPECT/CT images (functional avoidance plans) and compared against conventional pRT plans. Methods: Three HCC patients underwent SC SPECT/CT scans for pRT planning acquired 15 min post injection over 24 min. Images were reconstructed with OSEM following scatter, collimator, and exhale CT attenuation correction. Functional liver volumes (FLV) were defined by liver:spleen uptake ratio thresholds (43% to 90% maximum). Planning objectives to FLV were based on mean SC SPECT uptake ratio relative to GTV-subtracted liver and inversely scaled to mean liver dose of 20 Gy. PTV target coverage (V{sub 95}) was matched between conventional and functional avoidance plans. PBS pRT plans were optimized in RayStation for single field uniform dose (SFUD) and systematically perturbed to verify robustness to uncertainty in range, setup, and motion. Relative differences in FLV DVH and target dose heterogeneity (D{sub 2}-D{sub 98})/D50 were assessed. Results: For similar liver dose between functional avoidance and conventional PBS pRT plans (D{sub mean}≤5% difference, V{sub 18Gy}≤1% difference), dose to functional liver volumes were lower in avoidance plans but varied in magnitude across patients (FLV{sub 70%max} D{sub mean}≤26% difference, V{sub 18Gy}≤8% difference). Higher PTV dose heterogeneity in avoidance plans was associated with lower functional liver dose, particularly for the largest lesion [(D{sub 2}-D{sub 98})/D{sub 50}=13%, FLV{sub 90%max}=50% difference]. Conclusion: Differential avoidance of functional liver regions defined on sulfur colloid SPECT/CT is feasible with proton

  19. Radiation-Induced Leukemia at Doses Relevant to Radiation Therapy: Modeling Mechanisms and Estimating Risks

    NASA Technical Reports Server (NTRS)

    Shuryak, Igor; Sachs, Rainer K.; Hlatky, Lynn; Mark P. Little; Hahnfeldt, Philip; Brenner, David J.

    2006-01-01

    Because many cancer patients are diagnosed earlier and live longer than in the past, second cancers induced by radiation therapy have become a clinically significant issue. An earlier biologically based model that was designed to estimate risks of high-dose radiation induced solid cancers included initiation of stem cells to a premalignant state, inactivation of stem cells at high radiation doses, and proliferation of stem cells during cellular repopulation after inactivation. This earlier model predicted the risks of solid tumors induced by radiation therapy but overestimated the corresponding leukemia risks. Methods: To extend the model to radiation-induced leukemias, we analyzed in addition to cellular initiation, inactivation, and proliferation a repopulation mechanism specific to the hematopoietic system: long-range migration through the blood stream of hematopoietic stem cells (HSCs) from distant locations. Parameters for the model were derived from HSC biologic data in the literature and from leukemia risks among atomic bomb survivors v^ ho were subjected to much lower radiation doses. Results: Proliferating HSCs that migrate from sites distant from the high-dose region include few preleukemic HSCs, thus decreasing the high-dose leukemia risk. The extended model for leukemia provides risk estimates that are consistent with epidemiologic data for leukemia risk associated with radiation therapy over a wide dose range. For example, when applied to an earlier case-control study of 110000 women undergoing radiotherapy for uterine cancer, the model predicted an excess relative risk (ERR) of 1.9 for leukemia among women who received a large inhomogeneous fractionated external beam dose to the bone marrow (mean = 14.9 Gy), consistent with the measured ERR (2.0, 95% confidence interval [CI] = 0.2 to 6.4; from 3.6 cases expected and 11 cases observed). As a corresponding example for brachytherapy, the predicted ERR of 0.80 among women who received an inhomogeneous low-dose

  20. Main Sources and Doses of Space Radiation during Mars Missions and Total Radiation Risk for Cosmonauts

    NASA Astrophysics Data System (ADS)

    Mitrikas, Victor; Aleksandr, Shafirkin; Shurshakov, Vyacheslav

    This work contains calculation data of generalized doses and dose equivalents in critical organs and tissues of cosmonauts produces by galactic cosmic rays (GCR), solar cosmic rays (SCR) and the Earth’s radiation belts (ERB) that will impact crewmembers during a flight to Mars, while staying in the landing module and on the Martian surface, and during the return to Earth. Also calculated total radiation risk values during whole life of cosmonauts after the flight are presented. Radiation risk (RR) calculations are performed on the basis of a radiobiological model of radiation damage to living organisms, while taking into account reparation processes acting during continuous long-term exposure at various dose rates and under acute recurrent radiation impact. The calculations of RR are performed for crewmembers of various ages implementing a flight to Mars over 2 - 3 years in maximum and minimum of the solar cycle. The total carcinogenic and non-carcinogenic RR and possible life-span shortening are estimated on the basis of a model of the radiation death probability for mammals. This model takes into account the decrease in compensatory reserve of an organism as well as the increase in mortality rate and descent of the subsequent lifetime of the cosmonaut. The analyzed dose distributions in the shielding and body areas are applied to making model calculations of tissue equivalent spherical and anthropomorphic phantoms.

  1. Recent Updates to Radiation Organ Dose Estimation Tool PIMAL

    SciTech Connect

    Akkurt, Hatice; Wiarda, Dorothea; Eckerman, Keith F

    2011-01-01

    A computational phantom with moving arms and legs and an accompanying graphical user interface, PIMAL, was previously developed to enable radiation dose estimation for different postures in a user-friendly manner. This initial version of the software was useful in adjusting the posture, generating the corresponding MCNP input file, and performing the radiation transport simulations for dose calculations using MCNP5 or MCNPX. However, it only included one mathematical phantom model (hermaphrodite) and allowed only isotropic point sources. Recently, the software was enhanced by adding two more mathematical phantom models, a male and female, and the source features were enhanced significantly by adding internal and external source options in a pull-down menu. Although the initial version of the software included only a mathematical hermaphrodite phantom, the features and models in the software are constantly being enhanced by adding more phantoms as well as other options to enable dose assessment for different configurations/cases in a user-friendly manner. In this latest version of the software, ICRP's recently released reference male and female voxel phantoms are included in a pull-down menu. The male and female models are described using 7 and 14 million voxels, respectively. Currently, the software is being modified further to include the International Commission on Radiation Protection's (ICRP) reference male and female voxel phantoms. Additionally, some case studies are being implemented and included in a library of input files. This paper describes recent updates to the software.

  2. Low dose radiation damage effects in silicon strip detectors

    NASA Astrophysics Data System (ADS)

    Wiącek, P.; Dąbrowski, W.

    2016-11-01

    The radiation damage effects in silicon segmented detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL). However, radiation damage in silicon strip is observed not only after extreme doses up to 1 GGy expected at E-XFEL, but also at doses in the range of tens of Gy, to which the detectors in laboratory instruments like X-ray diffractometers or X-ray spectrometers can be exposed. In this paper we report on investigation of radiation damage effects in a custom developed silicon strip detector used in laboratory diffractometers equipped with X-ray tubes. Our results show that significant degradation of detector performance occurs at low doses, well below 200 Gy, which can be reached during normal operation of laboratory instruments. Degradation of the detector energy resolution can be explained by increasing leakage current and increasing interstrip capacitance of the sensor. Another observed effect caused by accumulation of charge trapped in the surface oxide layer is change of charge division between adjacent strips. In addition, we have observed unexpected anomalies in the annealing process.

  3. Ionizing Radiation Dose Due to the Use of Agricultural Fertilizers

    NASA Astrophysics Data System (ADS)

    Umisedo, Nancy K.; Okuno, Emico; Colacioppo, Sérgio; Medina, Nilberto H.; Hiodo, Francisco Y.

    2008-08-01

    The transference of radionuclides from the fertilizers to/and from soils to the foodstuffs can represent an increment in the internal dose when the vegetables are consumed by the human beings. This work evaluates the contribution of fertilizers to the increase of radiation level in the environment and of dose to the people. Samples of fertilizers, soils and vegetables produced in farms located in the neighbourhood of São Paulo city in the State of São Paulo, Brazil were analysed through gamma spectroscopy. The values of specific activity of 40K, 238U and 232Th show that there is no significant transference of natural radionuclides from fertilizers to the final product of the food chain. The annual committed effective dose due to the ingestion of 40K contained in the group of consumed vegetables analysed in this work resulted in the very low value of 0.882 μSv.

  4. Ionizing Radiation Dose Due to the Use of Agricultural Fertilizers

    SciTech Connect

    Umisedo, Nancy K.; Okuno, Emico; Medina, Nilberto H.; Colacioppo, Sergio; Hiodo, Francisco Y.

    2008-08-07

    The transference of radionuclides from the fertilizers to/and from soils to the foodstuffs can represent an increment in the internal dose when the vegetables are consumed by the human beings. This work evaluates the contribution of fertilizers to the increase of radiation level in the environment and of dose to the people. Samples of fertilizers, soils and vegetables produced in farms located in the neighbourhood of Sao Paulo city in the State of Sao Paulo, Brazil were analysed through gamma spectroscopy. The values of specific activity of {sup 40}K, {sup 238}U and {sup 232}Th show that there is no significant transference of natural radionuclides from fertilizers to the final product of the food chain. The annual committed effective dose due to the ingestion of {sup 40}K contained in the group of consumed vegetables analysed in this work resulted in the very low value of 0.882 {mu}Sv.

  5. Cone beam computed tomography radiation dose and image quality assessments.

    PubMed

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

  6. Chernobyl Doses. Volume 1. Analysis of Forest Canopy Radiation Response from Multispectral Imagery and the Relationship to Doses

    DTIC Science & Technology

    1994-09-01

    AD-A284 746 Defense Nuclear Agency Alexandria, VA 22310-3398 DNA-TR-92-37-V1 Chernobyl Doses Volume 1-Analysis of Forest Canopy Radiation Response...REPORT DATE 3. REPORT TYPE AND DATES COVERED 940901 Technical 870929- 930930 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Chernobyl Doses Volume 1-Analysis of...volume of the report Chernobyl Doses presents details of a new, quantitative method for remotely sensing ionizing radiation dose to vegetation

  7. Glandular dose in breast computed tomography with synchrotron radiation.

    PubMed

    Mettivier, G; Fedon, C; Di Lillo, F; Longo, R; Sarno, A; Tromba, G; Russo, P

    2016-01-21

    The purpose of this work is to provide an evaluation of the mean glandular dose (MGD) for breast computed tomography (CT) with synchrotron radiation in an axial scanning configuration with a partial or total organ volume irradiation, for the in vivo program of breast CT ongoing at the ELETTRA facility (Trieste, Italy). A Geant4 Monte Carlo code was implemented, simulating the photon irradiation from a synchrotron radiation source in the energetic range from 8 to 50 keV with 1 keV intervals, to evaluate the MGD. The code was validated with literature data, in terms of mammographic normalized glandular dose coefficients (DgN) and with ad hoc experimental data, in terms of computed tomography dose index (CTDI). Simulated cylindrical phantoms of different sizes (diameter at phantom base 8, 10, 12, 14 or 16 cm, axial length 1.5 times the radius) and glandular fraction by weight (0%, 14.3%, 25%, 50%, 75% and 100%) were implemented into the code. The validation of the code shows an excellent agreement both with previously published work and in terms of DgN and CDTI measurements. The implemented simulations show a dependence of the glandular dose estimate on the vertical dimension of the irradiated zone when a partial organ irradiation was implemented. Specific normalized coefficients for calculating the MGD to the whole breast or to the single irradiated slice were reported.

  8. Radiation Dose-Volume Effects in the Brain

    SciTech Connect

    Lawrence, Yaacov Richard; Li, X. Allen; El Naqa, Issam; Hahn, Carol A.; Marks, Lawrence B.; Merchant, Thomas E.; Dicker, Adam P.

    2010-03-01

    We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1-2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of <2.5 Gy, an incidence of radiation necrosis of 5% and 10% is predicted to occur at a biologically effective dose of 120 Gy (range, 100-140) and 150 Gy (range, 140-170), respectively. For twice-daily fractionation, a steep increase in toxicity appears to occur when the biologically effective dose is >80 Gy. For large fraction sizes (>=2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers' reported outcomes have prevented us from making toxicity-risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of >=18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT.

  9. Radiation dose estimate in small animal SPECT and PET.

    PubMed

    Funk, Tobias; Sun, Mingshan; Hasegawa, Bruce H

    2004-09-01

    Calculations of radiation dose are important in assessing the medical and biological implications of ionizing radiation in medical imaging techniques such as SPECT and PET. In contrast, radiation dose estimates of SPECT and PET imaging of small animals are not very well established. For that reason we have estimated the whole-body radiation dose to mice and rats for isotopes such as 18F, 99mTc, 201Tl, (111)In, 123I, and 125I that are used commonly for small animal imaging. We have approximated mouse and rat bodies with uniform soft tissue equivalent ellipsoids. The mouse and rat sized ellipsoids had a mass of 30 g and 300 g, respectively, and a ratio of the principal axes of 1:1:4 and 0.7:1:4. The absorbed fractions for various photon energies have been calculated using the Monte Carlo software package MCNP. Using these values, we then calculated MIRD S-values for two geometries that model the distribution of activity in the animal body: (a) a central point source and (b) a homogeneously distributed source, and compared these values against S-value calculations for small ellipsoids tabulated in MIRD Pamphlet 8 to validate our results. Finally we calculated the radiation dose taking into account the biological half-life of the radiopharmaceuticals and the amount of activity administered. Our calculations produced S-values between 1.06 x 10(-13) Gy/Bq s and 2.77 x 10(-13) Gy/Bq s for SPECT agents, and 15.0 x 10(-13) Gy/Bq s for the PET agent 18F, assuming mouse sized ellipsoids with uniform source distribution. The S-values for a central point source in an ellipsoid are about 10% higher than the values obtained for the uniform source distribution. Furthermore, the S-values for mouse sized ellipsoids are approximately 10 times higher than for the rat sized ellipsoids reflecting the difference in mass. We reviewed published data to obtain administered radioactivity and residence times for small animal imaging. From these values and our computed S-values we estimated

  10. Shuttle radiation dose measurements in the International Space Station orbits.

    PubMed

    Badhwar, Gautam D

    2002-01-01

    The International Space Station (ISS) is now a reality with the start of a permanent human presence on board. Radiation presents a serious risk to the health and safety of the astronauts, and there is a clear requirement for estimating their exposures prior to and after flights. Predictions of the dose rate at times other than solar minimum or solar maximum have not been possible, because there has been no method to calculate the trapped-particle spectrum at intermediate times. Over the last few years, a tissue-equivalent proportional counter (TEPC) has been flown at a fixed mid-deck location on board the Space Shuttle in 51.65 degrees inclination flights. These flights have provided data that cover the expected changes in the dose rates due to changes in altitude and changes in solar activity from the solar minimum to the solar maximum of the current 23rd solar cycle. Based on these data, a simple function of the solar deceleration potential has been derived that can be used to predict the galactic cosmic radiation (GCR) dose rates to within +/-10%. For altitudes to be covered by the ISS, the dose rate due to the trapped particles is found to be a power-law function, rho(-2/3), of the atmospheric density, rho. This relationship can be used to predict trapped dose rates inside these spacecraft to +/-10% throughout the solar cycle. Thus, given the shielding distribution for a location inside the Space Shuttle or inside an ISS module, this approach can be used to predict the combined GCR + trapped dose rate to better than +/-15% for quiet solar conditions.

  11. The Radiation Dose-Response of the Human Spinal Cord

    SciTech Connect

    Schultheiss, Timothy E.

    2008-08-01

    Purpose: To characterize the radiation dose-response of the human spinal cord. Methods and Materials: Because no single institution has sufficient data to establish a dose-response function for the human spinal cord, published reports were combined. Requisite data were dose and fractionation, number of patients at risk, number of myelopathy cases, and survival experience of the population. Eight data points for cervical myelopathy were obtained from five reports. Using maximum likelihood estimation correcting for the survival experience of the population, estimates were obtained for the median tolerance dose, slope parameter, and {alpha}/{beta} ratio in a logistic dose-response function. An adequate fit to thoracic data was not possible. Hyperbaric oxygen treatments involving the cervical cord were also analyzed. Results: The estimate of the median tolerance dose (cervical cord) was 69.4 Gy (95% confidence interval, 66.4-72.6). The {alpha}/{beta} = 0.87 Gy. At 45 Gy, the (extrapolated) probability of myelopathy is 0.03%; and at 50 Gy, 0.2%. The dose for a 5% myelopathy rate is 59.3 Gy. Graphical analysis indicates that the sensitivity of the thoracic cord is less than that of the cervical cord. There appears to be a sensitizing effect from hyperbaric oxygen treatment. Conclusions: The estimate of {alpha}/{beta} is smaller than usually quoted, but values this small were found in some studies. Using {alpha}/{beta} = 0.87 Gy, one would expect a considerable advantage by decreasing the dose/fraction to less than 2 Gy. These results were obtained from only single fractions/day and should not be applied uncritically to hyperfractionation.

  12. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method.

    PubMed

    Larson, David B

    2014-10-01

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach.

  13. CANCER RISKS ATTRIBUTABLE TO LOW DOSES OF IONIZING RADIATION - ASSESSING WHAT WE REALLY KNOW?

    EPA Science Inventory

    Cancer Risks Attributable to Low Doses of Ionizing Radiation - What Do We Really Know?

    Abstract
    High doses of ionizing radiation clearly produce deleterious consequences in humans including, but not exclusively, cancer induction. At very low radiation doses the situatio...

  14. Radiation effects on livestock: physiological effects, dose response

    SciTech Connect

    Bell, M.C.

    1985-06-01

    Farm livestock show no measurable effects from being exposed to ionizing radiation unless the level is greatly in excess of the natural background radiation. Possible sources of ionizing radiation which might affect livestock or contribute to radioactivity in the food chain to humans are reactor accidents, fuel reprocessing plant accidents and thermonuclear explosions. Most data on ionizing radiation effects on livestock are from whole body gamma doses near the LD 50/60 level. However, grazing livestock would be subjected to added beta exposure from ingested and skin retained radioactive particles. Results of attempts to simulate exposure of the Hereford cattle at Alamogardo, NM show that cattle are more sensitive to ingested fallout radiation than other species. Poultry LD 50/60 for gamma exposure is about twice the level for mammals, and swine appear to have the most efficient repair system being able to withstand the most chronic gamma exposure. Productivity of most livestock surviving an LD 50/60 exposure is temporarily reduced and longterm effects are small. Livestock are good screeners against undesirables in our diet and with the exception of radiosotopes of iodine in milk, very little fission product radioactivity would be expected to be transferred through the food chain in livestock products for humans. Feeding of stored feed or moving livestock to uncontaminated pastures would be the best protective action to follow. 29 references.

  15. The determination of the penetrating radiation dose at Hanford

    SciTech Connect

    Rathbun, L.A.

    1989-09-01

    Most of the thermoluminescent dosimeters (TLDs) and other devices that have been used to measure environmental radiation on the Hanford Site have measured natural background levels of radiation. Measurements of offsite environmental radiation near the boundary of the Hanford Site have often indicated higher doses than onsite measurements have. However, the converse has been found when radiation measurements from the cities and communities of southeastern Washington were compared with onsite measurements. The historical trends described for environmental TLD data have been better defined in this study by compiling the TLD data for selected locations over a 6-year period (1983 to 1988). The ongoing Hanford Environmental Surveillance Program also provides radionuclide concentrations in soil based on samples collected by technicians at Pacific Northwest Laboratory (PNL) and sent to a commercial laboratory for analyses. As part of the study described in this report, a portable gamma spectroscopy system was used in the field to identify concentrations of gamma-emitting radionuclides in the soil at various locations on the Hanford Site and in the surrounding area. This work began in 1986. Supplemental radiation measurements were made with a microprocessor-based survey meter and large NaI detector. 20 refs., 4 figs., 3 tabs.

  16. Radiation Dose to the Lens of the Eye from Computed Tomography Scans of the Head

    NASA Astrophysics Data System (ADS)

    Januzis, Natalie Ann

    dependent upon the shape and size of the head, which influences whether or not the angled scan range coverage can include the entire brain volume and still avoid the orbit. The clinical component of this dissertation involved performing retrospective patient studies in the pediatric and adult populations, and reconstructing the lens doses from head CT examinations with the methods derived in the physics component. The cumulative lens doses in the patients selected for the retrospective study ranged from 40 to 1020 mGy in the pediatric group, and 53 to 2900 mGy in the adult group. This dissertation represents a comprehensive approach to lens of the eye dosimetry in CT imaging of the head. The collected data and derived formulas can be used in future studies on radiation-induced cataracts from repeated CT imaging of the head. Additionally, it can be used in the areas of personalized patient dose management, and protocol optimization and clinician training.

  17. Problems in evaluating radiation dose via terrestrial and aquatic pathways.

    PubMed Central

    Vaughan, B E; Soldat, J K; Schreckhise, R G; Watson, E C; McKenzie, D H

    1981-01-01

    This review is concerned with exposure risk and the environmental pathways models used for predictive assessment of radiation dose. Exposure factors, the adequacy of available data, and the model subcomponents are critically reviewed from the standpoint of absolute error propagation. Although the models are inherently capable of better absolute accuracy, a calculated dose is usually overestimated by from two to six orders of magnitude, in practice. The principal reason for so large an error lies in using "generic" concentration ratios in situations where site specific data are needed. Major opinion of the model makers suggests a number midway between these extremes, with only a small likelihood of ever underestimating the radiation dose. Detailed evaluations are made of source considerations influencing dose (i.e., physical and chemical status of released material); dispersal mechanisms (atmospheric, hydrologic and biotic vector transport); mobilization and uptake mechanisms (i.e., chemical and other factors affecting the biological availability of radioelements); and critical pathways. Examples are shown of confounding in food-chain pathways, due to uncritical application of concentration ratios. Current thoughts of replacing the critical pathways approach to calculating dose with comprehensive model calculations are also shown to be ill-advised, given present limitations in the comprehensive data base. The pathways models may also require improved parametrization, as they are not at present structured adequately to lend themselves to validation. The extremely wide errors associated with predicting exposure stand in striking contrast to the error range associated with the extrapolation of animal effects data to the human being. PMID:7037381

  18. Radiation Dose to Newborns in Neonatal Intensive Care Units

    PubMed Central

    Bahreyni Toossi, Mohammad Taghi; Malekzadeh, Malakeh

    2012-01-01

    Background With the increase of X-ray use for medical diagnostic purposes, knowing the given doses is necessary in patients for comparison with reference levels. The concept of reference doses or diagnostic reference levels (DRLs) has been developed as a practical aid in the optimization of patient protection in diagnostic radiology. Objectives To assess the radiation doses to neonates from diagnostic radiography (chest and abdomen). This study has been carried out in the neonatal intensive care unit of a province in Iran. Patients and Methods Entrance surface dose (ESD) was measured directly with thermoluminescent dosimeters (TLDs). The population included 195 neonates admitted for a diagnostic radiography, in eight NICUs of different hospital types. Results The mean ESD for chest and abdomen examinations were 76.3 µGy and 61.5 µGy, respectively. DRLs for neonate in NICUs of the province were 88 µGy for chest and 98 µGy for abdomen examinations that were slightly higher than other studies. Risk of death due to radiation cancer incidence of abdomens examination was equal to 1.88 × 10 -6 for male and 4.43 × 10 -6 for female. For chest X-ray, it was equal to 2.54 × 10 -6 for male and 1.17 × 10 -5 for female patients. Conclusion DRLs for neonates in our province were slightly higher than values reported by other studies such as European national diagnostic reference levels and the NRPB reference dose. The main reason was related to using a high mAs and a low kVp applied in most departments and also a low focus film distance (FFD). Probably lack of collimation also affected some exams in the NICUs. PMID:23329980

  19. Modeling the radiation doses from terrestrial gamma-ray flashes

    NASA Astrophysics Data System (ADS)

    Dwyer, Joseph; Liu, Ningyu; Rassoul, Hamid

    2013-04-01

    Terrestrial gamma-ray flashes (TGFs) are intense bursts of gamma-rays that originate from thunderclouds, from altitudes that commercial aircraft fly. Based upon the fluence of gamma-rays measured by the RHESSI spacecraft, Dwyer et al. [2010] inferred radiation doses to individuals inside aircraft in the 0.001 - 0.1 Sv range, depending upon the assumed size of the TGF source region. The largest doses occur when an aircraft is directly struck by the energetic electron beam that produces the TGF. The relativistic feedback discharge model is a self-consistent model that includes the generation of runaway electrons via the positron and x-ray feedback mechanisms and the electric field changes due to the resulting ionization and low-energy electron and ion currents. This model has successfully explained many properties of TGFs, including the gamma-ray intensities, durations, multi-pulsed structures as well as discharge currents and radio emissions. In this presentation we discuss new radiation dose calculations based upon the relativistic feedback discharge model and compare these calculations to previous work.

  20. Radiation signature on exposed cells: Relevance in dose estimation.

    PubMed

    Perumal, Venkatachalam; Gnana Sekaran, Tamizh Selvan; Raavi, Venkateswarlu; Basheerudeen, Safa Abdul Syed; Kanagaraj, Karthik; Chowdhury, Amith Roy; Paul, Solomon Fd

    2015-09-28

    The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable dose estimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net.

  1. Radiation signature on exposed cells: Relevance in dose estimation

    PubMed Central

    Perumal, Venkatachalam; Gnana Sekaran, Tamizh Selvan; Raavi, Venkateswarlu; Basheerudeen, Safa Abdul Syed; Kanagaraj, Karthik; Chowdhury, Amith Roy; Paul, Solomon FD

    2015-01-01

    The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable dose estimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net. PMID:26435777

  2. Contribution of maternal radionuclide burdens to prenatal radiation doses

    SciTech Connect

    Sikov, M.R.; Hui, T.E.; Meznarich, H.K.; Thrall, K.D. . Div. of Regulatory Applications); Traub, R.J. )

    1992-03-01

    This report discusses approaches to calculating and expressing radiation doses to the embryo/fetus from internal radionuclides. Information was obtained for selected, occupationally significant radionuclides in chemical forms that provided a spectrum of metabolic and dosimetric characteristics. Fractional placental transfer and/or ratios of concentration in the embryo/fetus to that in the woman were estimated for these materials, and were combined with data from biokinetic transfer models to predict radioactivity levels in the embryo/fetus as a function of stage of pregnancy and time after entry into the transfer compartment or blood of the pregnant woman. Medical Internal Radiation Dosimetry (MIRD) methodologies were extended to formalize and describe details for calculating radiation absorbed doses to the embryo/fetus. Calculations were performed for representative situations; introduction of 1 {mu}Ci into a woman's blood at successive months of pregnancy was assumed to accommodate the stage dependence of geometric relationships and biological behaviors. Summary tables of results, correlations, and dosimetric relations, and of tentative generalized categorizations, are provided in the report.

  3. Has the use of computers in radiation therapy improved the accuracy in radiation dose delivery?

    NASA Astrophysics Data System (ADS)

    Van Dyk, J.; Battista, J.

    2014-03-01

    Purpose: It is well recognized that computer technology has had a major impact on the practice of radiation oncology. This paper addresses the question as to how these computer advances have specifically impacted the accuracy of radiation dose delivery to the patient. Methods: A review was undertaken of all the key steps in the radiation treatment process ranging from machine calibration to patient treatment verification and irradiation. Using a semi-quantitative scale, each stage in the process was analysed from the point of view of gains in treatment accuracy. Results: Our critical review indicated that computerization related to digital medical imaging (ranging from target volume localization, to treatment planning, to image-guided treatment) has had the most significant impact on the accuracy of radiation treatment. Conversely, the premature adoption of intensity-modulated radiation therapy has actually degraded the accuracy of dose delivery compared to 3-D conformal radiation therapy. While computational power has improved dose calibration accuracy through Monte Carlo simulations of dosimeter response parameters, the overall impact in terms of percent improvement is relatively small compared to the improvements accrued from 3-D/4-D imaging. Conclusions: As a result of computer applications, we are better able to see and track the internal anatomy of the patient before, during and after treatment. This has yielded the most significant enhancement to the knowledge of "in vivo" dose distributions in the patient. Furthermore, a much richer set of 3-D/4-D co-registered dose-image data is thus becoming available for retrospective analysis of radiobiological and clinical responses.

  4. Radiation damage in single-particle cryo-electron microscopy: effects of dose and dose rate

    PubMed Central

    Karuppasamy, Manikandan; Karimi Nejadasl, Fatemeh; Vulovic, Milos; Koster, Abraham J.; Ravelli, Raimond B. G.

    2011-01-01

    Radiation damage is an important resolution limiting factor both in macromolecular X-ray crystallography and cryo-electron microscopy. Systematic studies in macromolecular X-ray crystallography greatly benefited from the use of dose, expressed as energy deposited per mass unit, which is derived from parameters including incident flux, beam energy, beam size, sample composition and sample size. In here, the use of dose is reintroduced for electron microscopy, accounting for the electron energy, incident flux and measured sample thickness and composition. Knowledge of the amount of energy deposited allowed us to compare doses with experimental limits in macromolecular X-ray crystallography, to obtain an upper estimate of radical concentrations that build up in the vitreous sample, and to translate heat-transfer simulations carried out for macromolecular X-ray crystallography to cryo-electron microscopy. Stroboscopic exposure series of 50–250 images were collected for different incident flux densities and integration times from Lumbricus terrestris extracellular hemoglobin. The images within each series were computationally aligned and analyzed with similarity metrics such as Fourier ring correlation, Fourier ring phase residual and figure of merit. Prior to gas bubble formation, the images become linearly brighter with dose, at a rate of approximately 0.1% per 10 MGy. The gradual decomposition of a vitrified hemoglobin sample could be visualized at a series of doses up to 5500 MGy, by which dose the sample was sublimed. Comparison of equal-dose series collected with different incident flux densities showed a dose-rate effect favoring lower flux densities. Heat simulations predict that sample heating will only become an issue for very large dose rates (50 e−Å−2 s−1 or higher) combined with poor thermal contact between the grid and cryo-holder. Secondary radiolytic effects are likely to play a role in dose-rate effects. Stroboscopic data collection

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

    PubMed

    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.

  6. Implications of radiation dose and exposed populations on radiation protection in the 21st century.

    PubMed

    Boice, John D

    2014-02-01

    Radiation is in the public eye because of Fukushima, computed tomography examinations, airport screenings, and possible terrorist attacks. What if the Boston Marathon pressure cooker had also contained a radioactive source? Nuclear power may be on the resurgence. Because of the increasing uses of radiation, the increases in population exposures, and the increasing knowledge of radiation effects, constant vigilance is needed to keep up with the changing times. Psychosocial disorders associated with the inappropriate (but real) fear of radiation need to be recognized as radiation detriments. Radiation risk communication, radiation education, and communication must improve at all levels: to members of the public, to the media, to other scientists, and to radiation professionals. Stakeholders must continue to be involved in all radiation protection initiatives. Finally, we are at a crisis as the number of war babies (me) and baby boomers (you?) who are also radiation professionals continues its rapid decline, and there are few in the pipeline to fill the current and looming substantial need: "The old road is rapidly agin'" (Dylan). NCRP has begun the WARP initiative-Where Are the Radiation Professionals?-an attempt to rejuvenate the pipeline of future professionals before the trickle becomes tiny drops. A Workshop was held in July 2013 with government agencies, military, private sector, universities, White House representatives, and societies to develop a coordinated and national action plan. A "Manhattan Project" is needed to get us "Back to the Future" in terms of the funding levels that existed in years past that provided the necessary resources to train, engage, and retain (a.k.a., jobs) the radiation professionals needed for the nation. If we don't keep swimmin' (Disney's Nemo) we'll "sink like a stone" (Dylan).Introduction of Implications of Radiation Dose and Exposed Populations (Video 2:06, http://links.lww.com/HP/A25).

  7. Spine stereotactic body radiation therapy plans: Achieving dose coverage, conformity, and dose falloff

    SciTech Connect

    Hong, Linda X.; Shankar, Viswanathan; Shen, Jin; Kuo, Hsiang-Chi; Mynampati, Dinesh; Yaparpalvi, Ravindra; Goddard, Lee; Basavatia, Amar; Fox, Jana; Garg, Madhur; Kalnicki, Shalom; Tomé, Wolfgang A.

    2015-10-01

    We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage—prescription dose (PD) to cover at least 95% planning target volume (PTV) and 90% PD to cover at least 99% PTV; (2) conformity index (CI)—ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff—ratio of 50% PIV to the PTV (R{sub 50%}); (4) and maximum dose in percentage of PD at 2 cm from PTV in any direction (D{sub 2cm}) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ{sup 2} test was used to examine the difference in parameters between groups. The PTV V{sub 100%} {sub PD} ≥ 95% objective was met in 29.0% of group 1 vs 91.4% of group 2 (p < 0.01) plans. The PTV V{sub 90%} {sub PD} ≥ 99% objective was met in 38.7% of group 1 vs 88.6% of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D{sub 2cm}, 48.3% plans yielded a minor violation of the objectives and 16.1% a major violation for group 1, whereas 17.1% exhibited a minor violation and 2.9% a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.

  8. Radiation dose and image quality for paediatric interventional cardiology.

    PubMed

    Vano, E; Ubeda, C; Leyton, F; Miranda, P

    2008-08-07

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 microGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 microGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  9. Radiation dose and image quality for paediatric interventional cardiology

    NASA Astrophysics Data System (ADS)

    Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

    2008-08-01

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

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

    SciTech Connect

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

    2012-11-01

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

  11. Source term calculations for assessing radiation dose to equipment

    SciTech Connect

    Denning, R.S.; Freeman-Kelly, R.; Cybulskis, P.; Curtis, L.A.

    1989-07-01

    This study examines results of analyses performed with the Source Term Code Package to develop updated source terms using NUREG-0956 methods. The updated source terms are to be used to assess the adequacy of current regulatory source terms used as the basis for equipment qualification. Time-dependent locational distributions of radionuclides within a containment following a severe accident have been developed. The Surry reactor has been selected in this study as representative of PWR containment designs. Similarly, the Peach Bottom reactor has been used to examine radionuclide distributions in boiling water reactors. The time-dependent inventory of each key radionuclide is provided in terms of its activity in curies. The data are to be used by Sandia National Laboratories to perform shielding analyses to estimate radiation dose to equipment in each containment design. See NUREG/CR-5175, Beta and Gamma Dose Calculations for PWR and BWR Containments.'' 6 refs., 11 tabs.

  12. Hardening electronic devices against very high total dose radiation environments

    NASA Technical Reports Server (NTRS)

    Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.

    1972-01-01

    The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

  13. Perspectives on radiation dose estimates for A-bomb survivors

    SciTech Connect

    Loewe, W.E.

    1986-12-01

    Four decades after the actual events, quantitative characterization of the radiation fields at Hiroshima and Nagasaki continues to be sought, with high accuracy a goal justified by the unique contribution to radiation protection standards that is represented by the medical records of exposed survivors. The most recent effort is distinguished by its reliance on computer modeling and concomitant detail, and by its decentralized direction, both internationally and internally to the US and Japan, with resultant ongoing peer review and wide scope of inquiry. A new system for individual dose estimation has been agreed upon, and its scientific basis has been elaborated in the literature as well as in a comprehensive treatise to be published in the Spring of 1987. In perspective, this new system appears to be an unusually successful achievement that offers the expectation of reliable estimates with the desired accuracy. Some aspects leading to this expectation, along with a caveat, are discussed here. 4 refs., 8 figs., 3 tabs.

  14. 3D measurement of absolute radiation dose in grid therapy

    NASA Astrophysics Data System (ADS)

    Trapp, J. V.; Warrington, A. P.; Partridge, M.; Philps, A.; Leach, M. O.; Webb, S.

    2004-01-01

    Spatially fractionated radiotherapy through a grid is a concept which has a long history and was routinely used in orthovoltage radiation therapy in the middle of last century to minimize damage to the skin and subcutaneous tissue. With the advent of megavoltage radiotherapy and its skin sparing effects the use of grids in radiotherapy declined in the 1970s. However there has recently been a revival of the technique for use in palliative treatments with a single fraction of 10 to 20 Gy. In this work the absolute 3D dose distribution in a grid irradiation is measured for photons using a combination of film and gel dosimetry.

  15. Ceramic Matrix Composites Performances Under High Gamma Radiation Doses

    NASA Astrophysics Data System (ADS)

    Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

    2014-06-01

    Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

  16. An efficient Volumetric Arc Therapy treatment planning approach for hippocampal-avoidance whole-brain radiation therapy (HA-WBRT)

    SciTech Connect

    Shen, Jin; Bender, Edward; Yaparpalvi, Ravindra; Kuo, Hsiang-Chi; Basavatia, Amar; Hong, Linda; Bodner, William; Garg, Madhur K.; Kalnicki, Shalom; Tomé, Wolfgang A.

    2015-10-01

    An efficient and simple class solution is proposed for hippocampal-avoidance whole-brain radiation therapy (HA-WBRT) planning using the Volumetric Arc Therapy (VMAT) delivery technique following the NRG Oncology protocol NRG-CC001 treatment planning guidelines. The whole-brain planning target volume (PTV) was subdivided into subplanning volumes that lie in plane and out of plane with the hippocampal-avoidance volume. To further improve VMAT treatment plans, a partial-field dual-arc technique was developed. Both the arcs were allowed to overlap on the in-plane subtarget volume, and in addition, one arc covered the superior out-of-plane sub-PTV, while the other covered the inferior out-of-plane subtarget volume. For all plans (n = 20), the NRG-CC001 protocol dose-volume criteria were met. Mean values of volumes for the hippocampus and the hippocampal-avoidance volume were 4.1 cm{sup 3} ± 1.0 cm{sup 3} and 28.52 cm{sup 3} ± 3.22 cm{sup 3}, respectively. For the PTV, the average values of D{sub 2%} and D{sub 98%} were 36.1 Gy ± 0.8 Gy and 26.2 Gy ± 0.6 Gy, respectively. The hippocampus D{sub 100%} mean value was 8.5 Gy ± 0.2 Gy and the maximum dose was 15.7 Gy ± 0.3 Gy. The corresponding plan quality indices were 0.30 ± 0.01 (homogeneity index), 0.94 ± 0.01 (target conformality), and 0.75 ± 0.02 (confirmation number). The median total monitor unit (MU) per fraction was 806 MU (interquartile range [IQR]: 792 to 818 MU) and the average beam total delivery time was 121.2 seconds (IQR: 120.6 to 121.35 seconds). All plans passed the gamma evaluation using the 5-mm, 4% criteria, with γ > 1 of not more than 9.1% data points for all fields. An efficient and simple planning class solution for HA-WBRT using VMAT has been developed that allows all protocol constraints of NRG-CC001 to be met.

  17. Radiation Doses to Hanford Workers from Natural Potassium-40

    SciTech Connect

    Strom, Daniel J.; Lynch, Timothy P.; Weier, Dennis R.

    2009-02-01

    The chemical element potassium is an essential mineral in people and is subject to homeostatic regulation. Natural potassium comprises three isotopes, 39K, 40K, and 41K. Potassium-40 is radioactive, with a half life of 1.248 billion years. In most transitions, it emits a β particle with a maximum energy of 0.560 MeV, and sometimes a gamma photon of 1.461 MeV. Because it is ubiquitous, 40K produces radiation dose to all human beings. This report contains the results of new measurements of 40K in 248 adult females and 2,037 adult males performed at the Department of Energy Hanford Site in 2006 and 2007. Potassium concentrations diminish with age, are generally lower in women than in men, and decrease with body mass index (BMI). The average annual effective dose from 40K in the body is 0.149 mSv y-1 for men and 0.123 mSv y-1 women respectively. Averaged over both men and women, the average effective dose per year is 0.136 mSv y-1. Calculated effective doses range from 0.069 to 0.243 mSv y-1 for adult males, and 0.067 to 0.203 mSv y-1 for adult females, a roughly three-fold variation for each gender. The need for dosimetric phantoms with a greater variety of BMI values should be investigated. From our data, it cannot be determined whether the potassium concentration in muscle in people with large BMI values differs from that in people with small BMI values. Similarly, it would be important to know the potassium concentration in other soft tissues, since much of the radiation dose is due to beta radiation, in which the source and target tissues are the same. These uncertainties should be evaluated to determine their consequences for dosimetry.

  18. Estimating the Radiation Dose to the Fetus in Prophylactic Internal Iliac Artery Balloon Occlusion: Three Cases

    PubMed Central

    Kai, Kentaro; Hamada, Tomohiro; Yuge, Akitoshi; Kiyosue, Hiro; Nishida, Yoshihiro; Nasu, Kaei; Narahara, Hisashi

    2015-01-01

    Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiation dose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiation dose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiation dose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiation dose as the absorbed dose. We found that the fetal radiation doses ranged from 12.88 to 31.6 mGy. The fetal radiation dose during the prophylactic IIABOs did not exceed 50 mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus. PMID:26180648

  19. The Concentration Of Tritium In Urine And Internal Radiation Dose Estimation Of PTNBR Radiation Workers

    SciTech Connect

    Tjahaja, Poppy Intan; Sukmabuana, Putu; Aisyah, Neneng Nur

    2010-12-23

    The operation of Triga 2000 reactor in Nuclear Technology Center for Materials and Radiometry (PTNBR BATAN) normally produce tritium radionuclide which is the activation product of deuterium atom in reactor primary cooling water. According to previous monitoring, tritium was detected with the concentration of 8.236{+-}0.677 kBq/L and 1.704{+-}0.046 Bq/L in the primary cooling water and in reactor hall air, respectively. The tritium in reactor hall air chronically can be inhaled by the workers. In this research, tritium content in radiation workers' urine was determined to estimate the internal radiation doses received by the workers. About 50-100 mL of urine samples were collected from 48 PTNBR workers that is classified as 24 radiation workers and 24 administration staffs as a control. Urine samples of 25 mL were then prepared by active charcoal and KMnO{sub 4} addition and followed with complete distillation. The 2 mL of distillate was added with 13 mL scintillator, shaked vigorously and remained in cool and dark condition for about 24 hours. The tritium in the samples was then measured using liquid scintillation counter (LSC) for 1 hour. From the measurement results it was obtained that the tritium concentration in the urine of radiation workers were in the range of not detected and 5.191 Bq/mL, whereas in the administration staffs the concentration were between not detected and 4.607 Bq/mL. Internally radiation doses were calculated using the tritium concentration data, and it was found the averages about 0.602 {mu}Sv/year and 0.532 {mu}Sv/year for radiation workers and administration staffs, respectively. The doses received by the workers were lower than that of the permissible doses from tritium, i.e. 40 {mu}Sv/year.

  20. Dose-response relationships for the onset of avoidance of sonar by free-ranging killer whales.

    PubMed

    Miller, Patrick J O; Antunes, Ricardo N; Wensveen, Paul J; Samarra, Filipa I P; Alves, Ana Catarina; Tyack, Peter L; Kvadsheim, Petter H; Kleivane, Lars; Lam, Frans-Peter A; Ainslie, Michael A; Thomas, Len

    2014-02-01

    Eight experimentally controlled exposures to 1-2 kHz or 6-7 kHz sonar signals were conducted with four killer whale groups. The source level and proximity of the source were increased during each exposure in order to reveal response thresholds. Detailed inspection of movements during each exposure session revealed sustained changes in speed and travel direction judged to be avoidance responses during six of eight sessions. Following methods developed for Phase-I clinical trials in human medicine, response thresholds ranging from 94 to 164 dB re 1 μPa received sound pressure level (SPL) were fitted to Bayesian dose-response functions. Thresholds did not consistently differ by sonar frequency or whether a group had previously been exposed, with a mean SPL response threshold of 142 ± 15 dB (mean ± s.d.). High levels of between- and within-individual variability were identified, indicating that thresholds depended upon other undefined contextual variables. The dose-response functions indicate that some killer whales started to avoid sonar at received SPL below thresholds assumed by the U.S. Navy. The predicted extent of habitat over which avoidance reactions occur depends upon whether whales responded to proximity or received SPL of the sonar or both, but was large enough to raise concerns about biological consequences to the whales.

  1. Radiation Therapy Photon Beams Dose Conformation According to Dose Distribution Around Intracavitary-Applied Brachytherapy Sources

    SciTech Connect

    Jurkovic, Slaven Zauhar, Gordana; Faj, Dario; Radojcic, Deni Smilovic; Svabic, Manda

    2010-04-01

    Intracavitary application of brachytherapy sources followed by external beam radiation is essential for the local treatment of carcinoma of the cervix. Due to very high doses to the central portion of the target volume delivered by brachytherapy sources, this part of the target volume must be shielded while being irradiated by photon beams. Several shielding techniques are available, from rectangular block and standard cervix wedge to more precise, customized step wedge filters. Because the calculation of a step wedge filter's shape was usually based on effective attenuation coefficient, an approach that accounts, in a more precise way, for the scattered radiation, is suggested. The method was verified under simulated clinical conditions using film dosimetry. Measured data for various compensators were compared to the numerically determined sum of the dose distribution around brachytherapy sources and one of compensated beam. Improvements in total dose distribution are demonstrated, using our method. Agreement between calculation and measurements were within 3%. Sensitivity of the method on sources displacement during treatment has also been investigated.

  2. Radiation quality and the shape of dose-effect curves at low doses of ionizing radiation for eukaryotic cells.

    PubMed

    Petin, V G; Kapultcevich, Yu G

    2014-06-01

    To explain different yeast and mammalian cell response to low and high linear energy transfer (LET) radiation in low dose region, the dependence of fine target structure on the stage of cell growth was supposed. Theoretical consideration based on this suggestion was carried out. Results of calculations are qualitatively in agreement with experimental data under assuming that hit-event for both mammalian and yeast cells is a group of ionizations produced by the same ionizing particle. In the dependence of cell cycle phase, sensitive sites (presumable the vulnerable sections of chromosomes) can be located either in periphery of cell nucleus forming a thin layer inside the nucleus or distributed evenly over the whole nucleus. Such rearrangement of the target results in the alteration of the dependence of both survival curve shape and the relative biological effectiveness values on radiation quality.

  3. Thyroid neoplasia following low-dose radiation in childhood

    SciTech Connect

    Ron, E.; Modan, B.; Preston, D.; Alfandary, E.; Stovall, M.; Boice, J.D. Jr. )

    1989-12-01

    The thyroid gland is highly sensitive to the carcinogenic effects of ionizing radiation. Previously, we reported a significant increase of thyroid cancer and adenomas among 10,834 persons in Israel who received radiotherapy to the scalp for ringworm. These findings have now been extended with further follow-up and revised dosimetry. Overall, 98 thyroid tumors were identified among the exposed and 57 among 10,834 nonexposed matched population and 5392 sibling comparison subjects. An estimated thyroid dose of 9 cGy was linked to a fourfold (95% Cl = 2.3-7.9) increase of malignant tumors and a twofold (95% Cl = 1.3-3.0) increase of benign tumors. The dose-response relationship was consistent with linearity. Age was an important modifier of risk with those exposed under 5 years being significantly more prone to develop thyroid tumors than older children. The pattern of radiation risk over time could be described on the basis of a constant multiplication of the background rate, and an absolute risk model was not compatible with the observed data. Overall, the excess relative risk per cGy for thyroid cancer development after childhood exposure is estimated as 0.3, and the absolute excess risk as 13 per 10(6) PY-cGy. For benign tumors the estimated excess relative risk was 0.1 per cGy and the absolute risk was 15 per 10(6) PY-cGy.

  4. Contribution of maternal radionuclide burdens to prenatal radiation doses

    SciTech Connect

    Sikov, M.R.; Traub, R.J.; Meznarich, H.K. )

    1990-10-01

    This report describes approaches to calculating and expressing radiation doses to the embryo/fetus from internal radionuclides. Information was obtained for selected, occupationally significant radioelements to provide a spectrum of metabolic and dosimetric characteristics. Fractional placental transfer and ratios of concentration in the embryo/fetus to that in the woman were calculated for these materials, and were integrated with data from biokinetic transfer models to estimate radioactivity levels in the embryo/fetus as a function of stage of pregnancy and time after entry. The MIRD methodologies were extended to formalize and describe details for calculating radiation adsorbed doses to the embryo/fetus. Calculations were performed for representative situations; introduction of 1 {mu}Ci into a woman's blood at successive months of pregnancy was assumed to accommodate the stage dependence of geometric relationships and biological behaviors. Summary tables of results, correlations, and dosimetric relations, and of tentative generalized categorizations are provided in the report. 60 refs., 3 figs., 3 tabs.

  5. AAPM/RSNA Physics Tutorial for Residents: Topics in CT. Radiation dose in CT.

    PubMed

    McNitt-Gray, Michael F

    2002-01-01

    This article describes basic radiation dose concepts as well as those specifically developed to describe the radiation dose from computed tomography (CT). Basic concepts of radiation dose are reviewed, including exposure, absorbed dose, and effective dose. Radiation dose from CT demonstrates variations within the scan plane and along the z axis because of its unique geometry and usage. Several CT-specific dose descriptors have been developed: the Multiple Scan Average Dose descriptor, the Computed Tomography Dose Index (CTDI) and its variations (CTDI(100), CTDI(w), CTDI(vol)), and the dose-length product. Factors that affect radiation dose from CT include the beam energy, tube current-time product, pitch, collimation, patient size, and dose reduction options. Methods of reducing the radiation dose to a patient from CT include reducing the milliampere-seconds value, increasing the pitch, varying the milliampere-seconds value according to patient size, and reducing the beam energy. The effective dose from CT can be estimated by using Monte Carlo methods to simulate CT of a mathematical patient model, by estimating the energy imparted to the body region being scanned, or by using conversion factors for general anatomic regions. Issues related to radiation dose from CT are being addressed by the Society for Pediatric Radiology, the American Association of Physicists in Medicine, the American College of Radiology, and the Center for Devices and Radiological Health of the Food and Drug Administration.

  6. Time-dependent radiation dose estimations during interplanetary space flights

    NASA Astrophysics Data System (ADS)

    Dobynde, M. I.; Shprits, Y.; Drozdov, A.

    2015-12-01

    Time-dependent radiation dose estimations during interplanetary space flights 1,2Dobynde M.I., 2,3Drozdov A.Y., 2,4Shprits Y.Y.1Skolkovo institute of science and technology, Moscow, Russia 2University of California Los Angeles, Los Angeles, USA 3Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, Russia4Massachusetts Institute of Technology, Cambridge, USASpace radiation is the main restriction for long-term interplanetary space missions. It induces degradation of external components and propagates inside providing damage to internal environment. Space radiation particles and induced secondary particle showers can lead to variety of damage to astronauts in short- and long- term perspective. Contribution of two main sources of space radiation- Sun and out-of-heliosphere space varies in time in opposite phase due to the solar activity state. Currently the only habituated mission is the international interplanetary station that flights on the low Earth orbit. Besides station shell astronauts are protected with the Earth magnetosphere- a natural shield that prevents significant damage for all humanity. Current progress in space exploration tends to lead humanity out of magnetosphere bounds. With the current study we make estimations of spacecraft parameters and astronauts damage for long-term interplanetary flights. Applying time dependent model of GCR spectra and data on SEP spectra we show the time dependence of the radiation in a human phantom inside the shielding capsule. We pay attention to the shielding capsule design, looking for an optimal geometry parameters and materials. Different types of particles affect differently on the human providing more or less harm to the tissues. Incident particles provide a large amount of secondary particles while propagating through the shielding capsule. We make an attempt to find an optimal combination of shielding capsule parameters, namely material and thickness, that will effectively decrease

  7. KREAM: Korean Radiation Exposure Assessment Model for Aviation Route Dose

    NASA Astrophysics Data System (ADS)

    Hwang, J.; Dokgo, K.; Choi, E. J.; Kim, K. C.; Kim, H. P.; Cho, K. S. F.

    2014-12-01

    Since Korean Air has begun to use the polar route from Seoul/ICN airport to New York/JFK airport on August 2006, there are explosive needs for the estimation and prediction against cosmic radiation exposure for Korean aircrew and passengers in South Korea from public. To keep pace with those needs of public, Korean government made the law on safety standards and managements of cosmic radiation for the flight attendants and the pilots in 2013. And we have begun to develop our own Korean Radiation Exposure Assessment Model (KREAM) for aviation route dose since last year funded by Korea Meteorological Administration (KMA). GEANT4 model and NRLMSIS 00 model are used for calculation of the energetic particles' transport in the atmosphere and for obtaining the background atmospheric neutral densities depending on altitude. For prediction the radiation exposure in many routes depending on the various space weather effects, we constructed a database from pre-arranged simulations using all possible combinations of R, S, and G, which are the space weather effect scales provided by the National Oceanic and Atmospheric Administration (NOAA). To get the solar energetic particles' spectrum at the 100 km altitude which we set as a top of the atmospheric layers in the KREAM, we use ACE and GOES satellites' proton flux observations. We compare the results between KREAM and the other cosmic radiation estimation programs such as CARI-6M which is provided by the Federal Aviation Agency (FAA). We also validate KREAM's results by comparison with the measurement from Liulin-6K LET spectrometer onboard Korean commercial flights and Korean Air Force reconnaissance flights.

  8. Radiation Hormesis: Historical Perspective and Implications for Low-Dose Cancer Risk Assessment

    PubMed Central

    Vaiserman, Alexander M.

    2010-01-01

    Current guidelines for limiting exposure of humans to ionizing radiation are based on the linear-no-threshold (LNT) hypothesis for radiation carcinogenesis under which cancer risk increases linearly as the radiation dose increases. With the LNT model even a very small dose could cause cancer and the model is used in establishing guidelines for limiting radiation exposure of humans. A slope change at low doses and dose rates is implemented using an empirical dose and dose rate effectiveness factor (DDREF). This imposes usually unacknowledged nonlinearity but not a threshold in the dose-response curve for cancer induction. In contrast, with the hormetic model, low doses of radiation reduce the cancer incidence while it is elevated after high doses. Based on a review of epidemiological and other data for exposure to low radiation doses and dose rates, it was found that the LNT model fails badly. Cancer risk after ordinarily encountered radiation exposure (medical X-rays, natural background radiation, etc.) is much lower than projections based on the LNT model and is often less than the risk for spontaneous cancer (a hormetic response). Understanding the mechanistic basis for hormetic responses will provide new insights about both risks and benefits from low-dose radiation exposure. PMID:20585444

  9. Cardiovascular risks associated with low dose ionizing particle radiation.

    PubMed

    Yan, Xinhua; Sasi, Sharath P; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton ((1)H; 0.5 Gy, 1 GeV) and iron ion ((56)Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in (56)Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, (56)Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.

  10. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    DOE PAGES

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; ...

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initiallymore » improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.« less

  11. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    SciTech Connect

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.

  12. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    PubMed Central

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  13. Pediatric Computed Tomography. Radiation Dose in Abdominal Studies

    SciTech Connect

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

    2008-08-11

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

  14. Rats avoid exposure to HVdc electric fields: a dose response study.

    PubMed

    Creim, J A; Lovely, R H; Weigel, R J; Forsythe, W C; Anderson, L E

    1993-01-01

    Rats, given the choice, avoid exposure to alternating current (ac) 60-Hz electric fields at intensities > or = 75 kV/m. This study investigated the generality of this behavior by studying the response of rats when exposed to high voltage direct current (HVdc) electric fields. Three hundred eighty male Long Evans rats were studied in 9 experiments with 40 rats per experiment and in one experiment with 20 rats to determine 1) if rats avoid exposure to HVdc electric fields of varying field strengths, and 2) if avoidance did occur, what role, if any, the concentration of air ions would have on the avoidance behavior. In all experiments a three-compartment glass shuttlebox was used; either the left or right compartment could be exposed to a combination of HVdc electric fields and air ions while the other compartment remained sham-exposed. The third, center compartment was a transition zone between exposure and sham-exposure. In each experiment, the rats were individually assessed in 1-h sessions where half of the rats (n = 20) had the choice to locomote between the two sides being exposed or sham-exposed, while the other half of the rats (n = 20) were sham-exposed regardless of their location, except in one experiment where there was no sham-exposed group. The exposure levels for the first six experiments were 80, 55, 42.5, 30, -36, and -55 kV/m, respectively. The air ion concentration was constant at 1.4 x 10(6) ions/cc for the four positive exposure levels and -1.4 x 10(6) ions/cc for the two negative exposure levels. Rats having a choice between exposure and non-exposure relative to always sham-exposed control animals significantly reduced the amount of time spent on the exposed side at 80 kV/m (P < .002) as they did at both 55 and -55 kV/m (P < .005). No significant differences between groups were observed at 42.5, 30, or -36 kV/m. To determine what role the air ion concentration might have had on the avoidance behavior at field strengths of 55 kV/m or greater, four

  15. Comparative transcriptome analysis of rice seedlings induced by different doses of heavy ion radiation

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Sun, Yeqing; Wang, Wei

    2016-07-01

    Highly ionizing radiation (HZE) in space is considered as a main factor causing biological effects on plant seeds. To investigate the different effects on genome-wide gene expression of low-dose and high-dose ion radiation, we carried out ground-base carbon particle HZE experiments with different cumulative doses (0Gy, 0.2Gy, 2Gy) to rice seeds and then performed comparative transcriptome analysis of the rice seedlings. We identified a total of 2551 and 1464 differentially expressed genes (DEGs) in low-dose and high-dose radiation groups, respectively. Gene ontology analyses indicated that low-dose and high-dose ion radiation both led to multiple physiological and biochemical activities changes in rice. By Gene Ontology analyses, the results showed that only one process-oxidation reduction process was enriched in the biological process category after high-dose ion radiation, while more processes such as response to biotic stimulus, heme binding, tetrapyrrole binding, oxidoreductase activity, catalytic activity and oxidoreductase activity were significantly enriched after low-dose ion radiation. The results indicated that the rice plants only focused on the process of oxidation reduction to response to high-dose ion radiation, whereas it was a coordination of multiple biological processes to response to low-dose ion radiation. To elucidate the transcriptional regulation of radiation stress-responsive genes, we identified several DEGs-encoding TFs. AP2/EREBP, bHLH, C2H2, MYB and WRKY TF families were altered significantly in response to ion radiation. Mapman analysis speculated that the biological effects on rice seedlings caused by the radiation stress might share similar mechanisms with the biotic stress. Our findings highlight important alterations in the expression of radiation response genes, metabolic pathways, and TF-encoding genes in rice seedlings exposed to low-dose and high-dose ion radiation.

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

    DOEpatents

    Kopp, Manfred K.

    1988-01-01

    A radiation dose-rate meter is provided which uses an energy-sensitive detector and combines charge quantization and pulse-rate measurement to monitor radiation dose rates. The charge from each detected photon is quantized by level-sensitive comparators so that the resulting total output pulse rate is proportional to the dose-rate.

  17. PABLM: a computer program to calculate accumulated radiation doses from radionuclides in the environment

    SciTech Connect

    Napier, B.A.; Kennedy, W.E. Jr.; Soldat, J.K.

    1980-03-01

    A computer program, PABLM, was written to facilitate the calculation of internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. This report contains details of mathematical models used and calculational procedures required to run the computer program. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in the environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. The radiation dose models consider several exposure pathways. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years. The equations for calculating internal radiation doses are derived from those given by the International Commission on Radiological Protection (ICRP) for body burdens and MPC's of each radionuclide. The radiation doses from external exposure to contaminated water and soil are calculated using the basic assumption that the contaminated medium is large enough to be considered an infinite volume or plane relative to the range of the emitted radiations. The equations for calculations of the radiation dose from external exposure to shoreline sediments include a correction for the finite width of the contaminated beach.

  18. Detection and selective avoidance of near ultraviolet radiation by an aquatic annelid: the medicinal leech.

    PubMed

    Jellies, John

    2014-03-15

    Medicinal leeches are aquatic predators that inhabit surface waters during daylight and also leave the water where they might be exposed to less screened light. Whereas the leech visual system has been shown to respond to visible light, leeches in the genus Hirudo do not appear to be as negatively phototactic as one might expect in order to avoid potential ultraviolet radiation (UVR)-induced damage. I used high intensity light emitting diodes to test the hypothesis that leeches could detect and specifically avoid near UVR (395-405 nm). Groups of unfed juvenile leeches exhibited a robust negative phototaxis to UVR, but had no behavioral response to blue or red and only a slight negative phototaxis to green and white light. Individual leeches also exhibited a vigorous negative phototaxis to UVR; responding in 100% of trials compared with modest negative responses to visible light (responding in ~8% of the trials). The responses in fed and unfed leeches were comparable for UVR stimuli. The responses depended upon the stimulus site: leeches shortened away from UV light to the head, and extended away from UV light to the tail. Electrophysiological nerve recordings showed that the cephalic eyes responded vigorously to UVR. Additionally, individual leech photoreceptors also showed strong responses to UVR, and a higher-order neuron associated with shortening and rapid behavioral responses, the S-cell, was activated by UVR, on both the head and tail. These results demonstrate that the leech can detect UVR and is able to discriminate behaviorally between UVR and visible light.

  19. Detection and selective avoidance of near ultraviolet radiation by an aquatic annelid: the medicinal leech

    PubMed Central

    Jellies, John

    2014-01-01

    Medicinal leeches are aquatic predators that inhabit surface waters during daylight and also leave the water where they might be exposed to less screened light. Whereas the leech visual system has been shown to respond to visible light, leeches in the genus Hirudo do not appear to be as negatively phototactic as one might expect in order to avoid potential ultraviolet radiation (UVR)-induced damage. I used high intensity light emitting diodes to test the hypothesis that leeches could detect and specifically avoid near UVR (395–405 nm). Groups of unfed juvenile leeches exhibited a robust negative phototaxis to UVR, but had no behavioral response to blue or red and only a slight negative phototaxis to green and white light. Individual leeches also exhibited a vigorous negative phototaxis to UVR; responding in 100% of trials compared with modest negative responses to visible light (responding in ~8% of the trials). The responses in fed and unfed leeches were comparable for UVR stimuli. The responses depended upon the stimulus site: leeches shortened away from UV light to the head, and extended away from UV light to the tail. Electrophysiological nerve recordings showed that the cephalic eyes responded vigorously to UVR. Additionally, individual leech photoreceptors also showed strong responses to UVR, and a higher-order neuron associated with shortening and rapid behavioral responses, the S-cell, was activated by UVR, on both the head and tail. These results demonstrate that the leech can detect UVR and is able to discriminate behaviorally between UVR and visible light. PMID:24265432

  20. Acute radiation enteritis caused by dose-dependent radiation exposure in dogs: experimental research.

    PubMed

    Xu, Wenda; Chen, Jiang; Xu, Liu; Li, Hongyu; Guo, Xiaozhong

    2014-12-01

    Accidental or intended radiation exposure in mass casualty settings presents a serious and on-going threat. The development of mitigating and treating agents requires appropriate animal models. Unfortunately, the majority of research on radiation enteritis in animals has lacked specific assessments and targeted therapy. Our study showed beagle dogs, treated by intensity-modulated radiation therapy (IMRT) for abdominal irradiation, were administered single X-ray doses of 8-30 Gy. The degree of intestinal tract injury for all of the animals after radiation exposure was evaluated with regard to clinical syndrome, endoscopic findings, histological features, and intestinal function. The range of single doses (8 Gy, 10-14 Gy, and 16-30 Gy) represented the degree of injury (mild, moderate, and severe, respectively). Acute radiation enteritis included clinical syndrome with fever, vomiting, diarrhea, hemafecia, and weight loss; typical endoscopic findings included edema, bleeding, mucosal abrasions, and ulcers; and intestinal biopsy results revealed mucosal necrosis, erosion, and loss, inflammatory cell infiltration, hemorrhage, and congestion. Changes in serum diamine oxides (DAOs) and d-xylose represented intestinal barrier function and absorption function, respectively, and correlated with the extent of damage (P < 0.05 and P < 0.05, respectively). We successfully developed a dog model of acute radiation enteritis, thus obtaining a relatively objective evaluation of intestinal tract injury based on clinical performance and laboratory examination. The method of assessment of the degree of intestinal tract injury after abdominal irradiation could be beneficial in the development of novel and effective therapeutic strategies for acute radiation enteritis.

  1. Effect of low-dose ionizing radiation on luminous marine bacteria: radiation hormesis and toxicity.

    PubMed

    Kudryasheva, N S; Rozhko, T V

    2015-04-01

    The paper summarizes studies of effects of alpha- and beta-emitting radionuclides (americium-241, uranium-235+238, and tritium) on marine microorganisms under conditions of chronic low-dose irradiation in aqueous media. Luminous marine bacteria were chosen as an example of these microorganisms; bioluminescent intensity was used as a tested physiological parameter. Non-linear dose-effect dependence was demonstrated. Three successive stages in the bioluminescent response to americium-241 and tritium were found: 1--absence of effects (stress recognition), 2--activation (adaptive response), and 3--inhibition (suppression of physiological function, i.e. radiation toxicity). The effects were attributed to radiation hormesis phenomenon. Biological role of reactive oxygen species, secondary products of the radioactive decay, is discussed. The study suggests an approach to evaluation of non-toxic and toxic stages under conditions of chronic radioactive exposure.

  2. Coronary computed tomography angiography using ultra-low-dose contrast media: radiation dose and image quality.

    PubMed

    Komatsu, Sei; Kamata, Teruaki; Imai, Atsuko; Ohara, Tomoki; Takewa, Mitsuhiko; Ohe, Ryoko; Miyaji, Kazuaki; Yoshida, Junichi; Kodama, Kazuhisa

    2013-08-01

    To analyze the invasiveness and image quality of coronary CT angiography (CCTA) with 80 kV. We enrolled 181 patients with low body weight and low calcium level. Of these, 154 patients were randomly assigned to 1 of 3 groups: 280 HU/80 kV (n = 51); 350 HU/80 kV (n = 51); or 350 HU/120 kV (n = 52). The amount of contrast media (CM) was decided with a CT number-controlling system. Twenty-seven patients were excluded because of an invalid time density curve by timing bolus. The predicted amount of CM, volume CT dose index, dose-length product, effective dose, image noise, and 5-point image quality were measured. The amounts of CM for the 80 kV/280 HU, 80 kV/350 HU, and 120 kV/350 HU groups were 10 ± 4 mL, 15 ± 7 mL, and 30 ± 6 mL, respectively. Although image noise was greater at 80 than 120 kV, there was no significant difference in image quality between 80 kV/350 HU and 120 kV/350 HU (p = 0.390). There was no significant difference in image quality between 80 kV/280 HU and 80 kV/350 HU (4.4 ± 0.7 vs. 4.7 ± 0.4, p = 0.056). The amount of CM and effective dose was lower for 80 kV CCTA than for 120 kV CCTA. CCTA at 80 kV/280 HU may decrease the amount of CM and radiation dose necessary while maintaining image quality.

  3. Radiation burden from secondary doses to patients undergoing radiation therapy with photons and light ions and radiation doses from imaging modalities.

    PubMed

    Gudowska, I; Ardenfors, O; Toma-Dasu, I; Dasu, A

    2014-10-01

    Ionising radiation is increasingly used for the treatment of cancer, being the source of a considerable fraction of the medical irradiation to patients. With the increasing success rate of cancer treatments and longer life expectancy of the treated patients, the issue of secondary cancer incidence is of growing concern, especially for paediatric patients who may live long after the treatment and be more susceptible to carcinogenesis. Also, additional imaging procedures like computed tomography, kilovoltage and megavoltage imaging and positron emission tomography, alone or in conjunction with radiation therapy, may add to the radiation burden associated with the risk of occurrence of secondary cancers. This work has been based on literature studies and is focussed on the assessment of secondary doses to healthy tissues that are delivered by the use of modern radiation therapy and diagnostic imaging modalities in the clinical environment.

  4. Develop and fabricate a radiation dose measurement system for satellites

    NASA Astrophysics Data System (ADS)

    Morel, Paul R.; Hanser, Frederick; Belue, Jeff; Cohen, Ram

    1994-11-01

    A second generation Dosimeter has been designed to fulfill the need for accurate radiation dose measurements. Two identical Dosimeters, a flight unit and a backup unit, have been fabricated, tested and calibrated. The backup Dosimeter was integrated into the payload of the Advanced Photovoltaic and Electronic Expedients (APEX) satellite, as part of the Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) experiment. APEX was launched shortly after 1430 UT on 8/3/94, with the initial orbit having apogee/perigee in the equatorial plane. The Dosimeter was turned on in Rev. 20, at about 0410 UT on 8/5/94. The initial turn on showed no anomalies with the Dosimeter operating properly. The Dosimeter was then monitored for several days and proper operation has been verified.

  5. Therapy of locally unresectable pancreatic carcinoma: a randomized comparison of high dose (6000 rads) radiation alone, moderate dose radiation (4000 rads + 5-fluorouracil), and high dose radiation + 5-fluorouracil: the Gastrointestinal Tumor Study Group. [X ray

    SciTech Connect

    Moertel, C.G.; Frytak, S.; Hahn, R.G.

    1981-10-15

    One-hundred-ninety-four eligible and evaluable patients with histologically confirmed locally unresectable adenocarcinoma of the pancreas were randomly assigned to therapy with high-dose (6000 rads) radiation therapy alone, to moderate-dose (4000 rads) radiation + 5-fluorouracil (5-FU), and to high-dose radiation plus 5-FU. Median survival with radiation alone was only 5 1/2 months from date of diagnosis. Both 5-FU-containing treatment regimens produced a highly significant survival improvement when compared with radiation alone. Survival differences between 4000 rads plus 5-FU and 6000 rads plus 5-FU were not significant with an overall median survival of ten months. Significant prognostic variables, in addition to treatment, were pretreatment performance status and pretreatment CEA level. The toxic reactions related to the treatment are discussed.

  6. Steepness of the radiation dose-response curve for dose-per-fraction escalation keeping the number of fractions fixed.

    PubMed

    Bentzen, Søren M

    2005-01-01

    Clinically, there is growing interest in strategies for intensifying radiation therapy by escalating the dose per fraction. This paper considers the steepness of the dose-response curve in this case. The steepness of a radiation dose-response curve is most conveniently quantified by the normalized dose-response gradient, gamma. Under the assumption of a linear-quadratic dose-effect model, a simple analytical relationship is derived between the gamma-value for a dose-response curve generated by varying the total dose while keeping the number of fractions constant, i.e. escalating the dose per fraction, and the gamma-value for a dose-response curve generated by varying the total dose while keeping the dose per fraction constant. This formulation is compared with clinical dose-response data from the literature and shown to be in good agreement with the observations. Some implications of this formulation for non-uniform dose distributions delivered using 3D conformal radiotherapy or intensity modulated radiotherapy (IMRT) are briefly discussed.

  7. Oxycodone IV?; Eliminate Teaspoonfuls; Avoid Vitamin D Products Dosed and Measured in Drops

    PubMed Central

    Cohen, Michael R.; Smetzer, Judy L.

    2015-01-01

    These medication errors have occurred in health care facilities at least once. They will happen again—perhaps where you work. Through education and alertness of personnel and procedural safeguards, they can be avoided. You should consider publishing accounts of errors in your newsletters and/or presenting them at your inservice training programs. Your assistance is required to continue this feature. The reports described here were received through the Institute for Safe Medication Practices (ISMP) Medication Errors Reporting Program. Any reports published by ISMP will be anonymous. Comments are also invited; the writers’ names will be published if desired. ISMP may be contacted at the address shown below. Errors, close calls, or hazardous conditions may be reported directly to ISMP through the ISMP Web site (www.ismp.org), by calling 800-FAIL-SAFE, or via e-mail at ismpinfo@ismp.org. ISMP guarantees the confidentiality and security of the information received and respects reporters’ wishes as to the level of detail included in publications. PMID:26912913

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

    PubMed Central

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

    2014-01-01

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

  9. Is There a Dose-Response Relationship for Heart Disease With Low-Dose Radiation Therapy?

    SciTech Connect

    Chung, Eugene; Corbett, James R.; Moran, Jean M.; Griffith, Kent A.; Marsh, Robin B.; Feng, Mary; Jagsi, Reshma; Kessler, Marc L.; Ficaro, Edward C.; Pierce, Lori J.

    2013-03-15

    Purpose: To quantify cardiac radiation therapy (RT) exposure using sensitive measures of cardiac dysfunction; and to correlate dysfunction with heart doses, in the setting of adjuvant RT for left-sided breast cancer. Methods and Materials: On a randomized trial, 32 women with node-positive left-sided breast cancer underwent pre-RT stress single photon emission computed tomography (SPECT-CT) myocardial perfusion scans. Patients received RT to the breast/chest wall and regional lymph nodes to doses of 50 to 52.2 Gy. Repeat SPECT-CT scans were performed 1 year after RT. Perfusion defects (PD), summed stress defects scores (SSS), and ejection fractions (EF) were evaluated. Doses to the heart and coronary arteries were quantified. Results: The mean difference in pre- and post-RT PD was −0.38% ± 3.20% (P=.68), with no clinically significant defects. To assess for subclinical effects, PD were also examined using a 1.5-SD below the normal mean threshold, with a mean difference of 2.53% ± 12.57% (P=.38). The mean differences in SSS and EF before and after RT were 0.78% ± 2.50% (P=.08) and 1.75% ± 7.29% (P=.39), respectively. The average heart Dmean and D95 were 2.82 Gy (range, 1.11-6.06 Gy) and 0.90 Gy (range, 0.13-2.17 Gy), respectively. The average Dmean and D95 to the left anterior descending artery were 7.22 Gy (range, 2.58-18.05 Gy) and 3.22 Gy (range, 1.23-6.86 Gy), respectively. No correlations were found between cardiac doses and changes in PD, SSS, and EF. Conclusions: Using sensitive measures of cardiac function, no clinically significant defects were found after RT, with the average heart Dmean <5 Gy. Although a dose response may exist for measures of cardiac dysfunction at higher doses, no correlation was found in the present study for low doses delivered to cardiac structures and perfusion, SSS, or EF.

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

    SciTech Connect

    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.

  11. Dosimetry for quantitative analysis of low dose ionizing radiation effects on humans in radiation therapy patients

    SciTech Connect

    Lehmann, J; Stern, R L; Daly, T P; Schwieter, C W; Jones, G E; Arnold, M L; Hartmann-Siantar, C L; Goldberg, Z

    2004-04-20

    We have successfully developed a practical approach to predicting the location of skin surface dose at potential biopsy sites that receive 1 cGy and 10 cGy, respectively, in support of in vivo biologic dosimetry in humans. This represents a significant technical challenge as the sites lie on the patient surface out side the radiation fields. The PEREGRINE Monte Carlo simulation system was used to model radiation dose delivery and TLDs were used for validation on a phantom and confirmation during patient treatment. In the developmental studies the Monte Carlo simulations consistently underestimated the dose at the biopsy site by approximately 15% for a realistic treatment configuration, most likely due to lack of detail in the simulation of the linear accelerator outside the main beam line. Using a single, thickness-independent correction factor for the clinical calculations, the average of 36 measurements for the predicted 1 cGy point was 0.985 cGy (standard deviation: 0.110 cGy) despite patient breathing motion and other real world challenges. Since the 10 cGy point is situated in the region of high dose gradient at the edge of the field, patient motion had a greater effect and the six measured points averaged 5.90 cGy (standard deviation: 1.01 cGy), a difference that is equivalent to approximately a 6 mm shift on the patient's surface.

  12. COMPREHENSIVE DATA CONCERNING COSMIC RADIATION DOSES AT GROUND LEVEL AND IN-FLIGHTS FOR TURKEY.

    PubMed

    Parmaksız, A

    2016-12-01

    Cosmic radiation doses of individuals living in 81 cities in Turkey were estimated by using CARI-6 software. Annual cosmic radiation doses of individuals were found to be between 308 and 736 µSv y(-1) at ground level. The population-weighted annual effective dose from cosmic radiation was determined to be 387 µSv y(-1) for Turkey. Cosmic radiation doses on-board for 137 (60 domestic and 77 international) flights varied from 1.2 to 83 µSv. It was estimated that six or over long-route round-trip air travels may cause cosmic radiation dose above the permissible limit for member of the public, i.e. 1 mSv y(-1) According to the assumption of flights throughout 800 h on each route, cosmic radiation doses were found to be between 1.0 and 4.8 mSv for aircrew.

  13. Sensitivity to low-dose radiation in radiosensitive wasted mice

    SciTech Connect

    Paunesku, T.; Protic, M.; Woloschak, G. E.

    1999-11-12

    Mice homozygous for the autosomal recessive wasted mutation (wst/wst) have abnormalities in T-lymphocytes and in the anterior motor neuron cells of the spinal cord, leading to sensitivity to low doses of ionizing radiation, hind limb paralysis, and immunodeficiency. This defect results in a failure to gain weight by 20 days and death at 28 days of age. The wasted mutation (previously mapped to mouse chromosome 2) is shown to be a 3-bp deletion in a T-cell-specific (and perhaps motor-neuron-specific) regulatory region (promoter) of the proliferating cell nuclear antigen (PCNA) gene on mouse chromosome 2. A regulatory element is also shown to be important in PCNA expression in T-lymphocytes and motor neuron cells afflicted by the 3-bp deletion in the PCNA promoter. The model is as follows: Absence of PCNA expression in the thymuses (and motor neurons) of wasted mice causes cellular apoptosis; this absence of expression is mediated by a positive transactor that can bind to the wild-type but not the wasted mutant PCNA promoter; the bound protein induces late expression of PCNA in T-lymphocytes and prevents onset of radiation sensitivity in the cells.

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

    NASA Astrophysics Data System (ADS)

    Shao, Chia-Ho; Lu, Cheng-Chang; Chen, Tou-Rong; Weng, Jui-Hung; Kao, Pan-Fu; Dong, Shang-Lung; Chou, Ming-Jen

    2014-11-01

    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.

  15. CT Radiation Dose Management: A Comprehensive Optimization Process for Improving Patient Safety.

    PubMed

    Parakh, Anushri; Kortesniemi, Mika; Schindera, Sebastian T

    2016-09-01

    Rising concerns of radiation exposure from computed tomography have caused various advances in dose reduction technologies. While proper justification and optimization of scans has been the main focus to address increasing doses, the value of dose management has been largely overlooked. The purpose of this article is to explain the importance of dose management, provide an overview of the available options for dose tracking, and discuss the importance of a dedicated dose team. The authors also describe how a digital radiation tracking software can be used for analyzing the big data on doses for auditing patient safety, scanner utilization, and productivity, all of which have enormous personal and institutional implications. (©) RSNA, 2016.

  16. The NIOSH Radiation Dose Reconstruction Project: managing technical challenges.

    PubMed

    Moeller, Matthew P; Townsend, Ronald D; Dooley, David A

    2008-07-01

    Approximately two years after promulgation of the Energy Employees Occupational Illness Compensation Program Act, the National Institute for Occupational Safety and Health Office of Compensation and Analysis Support selected a contractor team to perform many aspects of the radiation dose reconstruction process. The project scope and schedule necessitated the development of an organization involving a comparatively large number of health physicists. From the initial stages, there were many technical and managerial challenges that required continuous planning, integration, and conflict resolution. This paper identifies those challenges and describes the resolutions and lessons learned. These insights are hopefully useful to managers of similar scientific projects, especially those requiring significant data, technical methods, and calculations. The most complex challenge has been to complete defensible, individualized dose reconstructions that support timely compensation decisions at an acceptable production level. Adherence to applying claimant-favorable and transparent science consistent with the requirements of the Act has been the key to establishing credibility, which is essential to this large and complex project involving tens of thousands of individual stakeholders. The initial challenges included garnering sufficient and capable scientific staff, developing an effective infrastructure, establishing necessary methods and procedures, and integrating activities to ensure consistent, quality products. The continuing challenges include maintaining the project focus on recommending a compensation determination (rather than generating an accurate dose reconstruction), managing the associated very large data and information management challenges, and ensuring quality control and assurance in the presence of an evolving infrastructure. The lessons learned concern project credibility, claimant favorability, project priorities, quality and consistency, and critical

  17. The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses

    PubMed Central

    Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Lee, In Kyung; Kim, Ji Young

    2015-01-01

    Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro. PMID:26317642

  18. Real-Time Patient Radiation Dose Monitoring System Used in a Large University Hospital.

    PubMed

    Kim, Jungsu; Yoon, Yongsu; Seo, Deoknam; Kwon, Soonmu; Shim, Jina; Kim, Jungmin

    2016-10-01

    Radiation dose monitoring in medical imaging examination areas is mandatory for the reduction of patient radiation exposure. Recently, dose monitoring techniques that use digital imaging and communications in medicine (DICOM) dose structured reports (SR) have been introduced. The present paper discusses the setup of a radiation dose monitoring system based on DICOM data from university hospitals in Korea. This system utilizes the radiation dose data-archiving method of standard DICOM dose SR combined with a DICOM modality performed procedure step (MPPS). The analysis of dose data based on a method utilizing DICOM tag information is proposed herein. This method supports the display of dose data from non-dosimeter-attached X-ray equipment. This system tracks data from 62 pieces of equipment to analyze digital radiographic, mammographic, mobile radiographic, CT, PET-CT, angiographic, and fluorographic modalities.

  19. MO-G-18A-01: Radiation Dose Reducing Strategies in CT, Fluoroscopy and Radiography

    SciTech Connect

    Mahesh, M; Gingold, E; Jones, A

    2014-06-15

    Advances in medical x-ray imaging have provided significant benefits to patient care. According to NCRP 160, there are more than 400 million x-ray procedures performed annually in the United States alone that contributes to nearly half of all the radiation exposure to the US population. Similar growth trends in medical x-ray imaging are observed worldwide. Apparent increase in number of medical x-ray imaging procedures, new protocols and the associated radiation dose and risk has drawn considerable attention. This has led to a number of technological innovations such as tube current modulation, iterative reconstruction algorithms, dose alerts, dose displays, flat panel digital detectors, high efficient digital detectors, storage phosphor radiography, variable filters, etc. that are enabling users to acquire medical x-ray images at a much lower radiation dose. Along with these, there are number of radiation dose optimization strategies that users can adapt to effectively lower radiation dose in medical x-ray procedures. The main objectives of this SAM course are to provide information and how to implement the various radiation dose optimization strategies in CT, Fluoroscopy and Radiography. Learning Objectives: To update impact of technological advances on dose optimization in medical imaging. To identify radiation optimization strategies in computed tomography. To describe strategies for configuring fluoroscopic equipment that yields optimal images at reasonable radiation dose. To assess ways to configure digital radiography systems and recommend ways to improve image quality at optimal dose.

  20. Adaptive Liver Stereotactic Body Radiation Therapy: Automated Daily Plan Reoptimization Prevents Dose Delivery Degradation Caused by Anatomy Deformations

    SciTech Connect

    Leinders, Suzanne M.; Breedveld, Sebastiaan; Méndez Romero, Alejandra; Schaart, Dennis; Seppenwoolde, Yvette; Heijmen, Ben J.M.

    2013-12-01

    Purpose: To investigate how dose distributions for liver stereotactic body radiation therapy (SBRT) can be improved by using automated, daily plan reoptimization to account for anatomy deformations, compared with setup corrections only. Methods and Materials: For 12 tumors, 3 strategies for dose delivery were simulated. In the first strategy, computed tomography scans made before each treatment fraction were used only for patient repositioning before dose delivery for correction of detected tumor setup errors. In adaptive second and third strategies, in addition to the isocenter shift, intensity modulated radiation therapy beam profiles were reoptimized or both intensity profiles and beam orientations were reoptimized, respectively. All optimizations were performed with a recently published algorithm for automated, multicriteria optimization of both beam profiles and beam angles. Results: In 6 of 12 cases, violations of organs at risk (ie, heart, stomach, kidney) constraints of 1 to 6 Gy in single fractions occurred in cases of tumor repositioning only. By using the adaptive strategies, these could be avoided (<1 Gy). For 1 case, this needed adaptation by slightly underdosing the planning target volume. For 2 cases with restricted tumor dose in the planning phase to avoid organ-at-risk constraint violations, fraction doses could be increased by 1 and 2 Gy because of more favorable anatomy. Daily reoptimization of both beam profiles and beam angles (third strategy) performed slightly better than reoptimization of profiles only, but the latter required only a few minutes of computation time, whereas full reoptimization took several hours. Conclusions: This simulation study demonstrated that replanning based on daily acquired computed tomography scans can improve liver stereotactic body radiation therapy dose delivery.

  1. Model calculations of the radiation dose and LET spectra on LDEF and comparisons with flight data

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.; Benton, E. V.

    1996-01-01

    Ionizing radiation environment models, a 3-D spacecraft mass model, and radiation transport codes have been used to predict the radiation dose and linear energy transfer (LET) spectra measured at various locations on the LDEF satellite. The predictions are compared with thermoluminescent dosimeter measurements of the trapped proton and electron doses and with LET spectra measured by plastic nuclear track detectors. The predicted vs observed comparisons indicate some of the uncertainties of present ionizing radiation environment models for low Earth-orbit missions.

  2. A technique for multi-dimensional optimization of radiation dose, contrast dose, and image quality in CT imaging

    NASA Astrophysics Data System (ADS)

    Sahbaee, Pooyan; Abadi, Ehsan; Sanders, Jeremiah; Becchetti, Marc; Zhang, Yakun; Agasthya, Greeshma; Segars, Paul; Samei, Ehsan

    2016-03-01

    The purpose of this study was to substantiate the interdependency of image quality, radiation dose, and contrast material dose in CT towards the patient-specific optimization of the imaging protocols. The study deployed two phantom platforms. First, a variable sized phantom containing an iodinated insert was imaged on a representative CT scanner at multiple CTDI values. The contrast and noise were measured from the reconstructed images for each phantom diameter. Linearly related to iodine-concentration, contrast to noise ratio (CNR), was calculated for different iodine-concentration levels. Second, the analysis was extended to a recently developed suit of 58 virtual human models (5D-XCAT) with added contrast dynamics. Emulating a contrast-enhanced abdominal image procedure and targeting a peak-enhancement in aorta, each XCAT phantom was "imaged" using a CT simulation platform. 3D surfaces for each patient/size established the relationship between iodine-concentration, dose, and CNR. The Sensitivity of Ratio (SR), defined as ratio of change in iodine-concentration versus dose to yield a constant change in CNR was calculated and compared at high and low radiation dose for both phantom platforms. The results show that sensitivity of CNR to iodine concentration is larger at high radiation dose (up to 73%). The SR results were highly affected by radiation dose metric; CTDI or organ dose. Furthermore, results showed that the presence of contrast material could have a profound impact on optimization results (up to 45%).

  3. Radiation Dose-Volume Effects in Radiation-Induced Rectal Injury

    SciTech Connect

    Michalski, Jeff M.; Gay, Hiram; Jackson, Andrew; Tucker, Susan L.; Deasy, Joseph O.

    2010-03-01

    The available dose/volume/outcome data for rectal injury were reviewed. The volume of rectum receiving >=60Gy is consistently associated with the risk of Grade >=2 rectal toxicity or rectal bleeding. Parameters for the Lyman-Kutcher-Burman normal tissue complication probability model from four clinical series are remarkably consistent, suggesting that high doses are predominant in determining the risk of toxicity. The best overall estimates (95% confidence interval) of the Lyman-Kutcher-Burman model parameters are n = 0.09 (0.04-0.14); m = 0.13 (0.10-0.17); and TD{sub 50} = 76.9 (73.7-80.1) Gy. Most of the models of late radiation toxicity come from three-dimensional conformal radiotherapy dose-escalation studies of early-stage prostate cancer. It is possible that intensity-modulated radiotherapy or proton beam dose distributions require modification of these models because of the inherent differences in low and intermediate dose distributions.

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

    DOE PAGES

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; ...

    2014-11-11

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

  5. RADIANCE: An automated, enterprise-wide solution for archiving and reporting CT radiation dose estimates.

    PubMed

    Cook, Tessa S; Zimmerman, Stefan L; Steingall, Scott R; Maidment, Andrew D A; Kim, Woojin; Boonn, William W

    2011-01-01

    There is growing interest in the ability to monitor, track, and report exposure to radiation from medical imaging. Historically, however, dose information has been stored on an image-based dose sheet, an arrangement that precludes widespread indexing. Although scanner manufacturers are beginning to include dose-related parameters in the Digital Imaging and Communications in Medicine (DICOM) headers of imaging studies, there remains a vast repository of retrospective computed tomographic (CT) data with image-based dose sheets. Consequently, it is difficult for imaging centers to monitor their dose estimates or participate in the American College of Radiology (ACR) Dose Index Registry. An automated extraction software pipeline known as Radiation Dose Intelligent Analytics for CT Examinations (RADIANCE) has been designed that quickly and accurately parses CT dose sheets to extract and archive dose-related parameters. Optical character recognition of information in the dose sheet leads to creation of a text file, which along with the DICOM study header is parsed to extract dose-related data. The data are then stored in a relational database that can be queried for dose monitoring and report creation. RADIANCE allows efficient dose analysis of CT examinations and more effective education of technologists, radiologists, and referring physicians regarding patient exposure to radiation at CT. RADIANCE also allows compliance with the ACR's dose reporting guidelines and greater awareness of patient radiation dose, ultimately resulting in improved patient care and treatment.

  6. Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy

    NASA Astrophysics Data System (ADS)

    Hälg, R. A.; Besserer, J.; Boschung, M.; Mayer, S.; Lomax, A. J.; Schneider, U.

    2014-05-01

    In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

  7. Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy.

    PubMed

    Hälg, R A; Besserer, J; Boschung, M; Mayer, S; Lomax, A J; Schneider, U

    2014-05-21

    In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

  8. Analysis of occupational doses of workers on the dose registry of the Federal Radiation Protection Service in 2000 and 2001.

    PubMed

    Ogundare, F O; Balogun, F A

    2003-01-01

    In 2000 and 2001 about 279 and 221 radiation workers, respectively, were monitored by the Federal Radiation Protection Service, University of Ibadan, in Nigeria. The distribution of the occupational doses shows that the majority of workers received doses below 4 mSv in each of the two years. The radiation workers in the two years are classified into two occupational categories: medicine and industry. The mean annual effective doses, collective doses and the collective dose distribution ratios for workers in each category and the entire monitored workers were calculated. The mean annual effective doses were compared with their corresponding worldwide values quoted by UNSCEAR. In each of the two years, a few workers in industry received doses higher than 50 mSv. The collective dose distribution ratio was found to be about 0.49, which is very close to the highest value of 0.5 in the range of values considered by UNSCEAR as normal for this parameter. This suggests that extra measures have to be taken, particularly in industry, to ensure that the proportion of workers at risk does not go outside this normal range. The occupational doses were also modelled by both the log-normal and Weibull distributions. Both distributions were found to describe the data in almost the same way.

  9. Characteristics of radiation-induced performance changes in bar-press avoidance with and without a preshock warning cue

    SciTech Connect

    Burghardt, W.F.; Hunt, W.A.

    1989-01-01

    Rats were trained to perform one of three tasks in which responses on a lever delayed the onset of footshock for 20 sec. One task provided a warning tone beginning 15 sec after the last response on the lever and lasting for 5 sec just prior to the presentation of a shock (fixed-interval signalled avoidance), while a second task provided no external cues (unsignalled avoidance). The third task was similar to the fixed-interval signalled avoidance task, except that the warning tone preceding shock began at varying intervals after the last response on the lever (variable-inteval signalled avoidance). Animals trained on the signalled avoidance paradigms received fewer shocks than those on the unsignalled avoidance paradigm. After 10 krads of gamma radiation, animals performing on either task with cues were less able to avoid shock, although they recovered somewhat over a 90-min period. The animals not provided cues also experienced more shocks during the first 10 min after irradiation but were relatively less affected in performing the task. Response rates on the bar and the patterns of responding on these tasks were not significantly different after irradiation, except that animals responded after the onset of shock more often after irradiation than before. These results suggest that rats will continue to effectively use task-related cues after irradiation, but that the relative degree of behavioral decrement may depend on the initial level of performance or possibly the complexity of the task.

  10. Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image

    NASA Astrophysics Data System (ADS)

    Yeo, Inhwan Jason; Jung, Jae Won; Chew, Meng; Kim, Jong Oh; Wang, Brian; Di Biase, Steven; Zhu, Yunping; Lee, Dohyung

    2009-09-01

    A straightforward and accurate method was developed to verify the delivery of intensity-modulated radiation therapy (IMRT) and to reconstruct the dose in a patient. The method is based on a computational algorithm that linearly describes the physical relationship between beamlets and dose-scoring voxels in a patient and the dose image from an electronic portal imaging device (EPID). The relationship is expressed in the form of dose response functions (responses) that are quantified using Monte Carlo (MC) particle transport techniques. From the dose information measured by the EPID the received patient dose is reconstructed by inversely solving the algorithm. The unique and novel non-iterative feature of this algorithm sets it apart from many existing dose reconstruction methods in the literature. This study presents the algorithm in detail and validates it experimentally for open and IMRT fields. Responses were first calculated for each beamlet of the selected fields by MC simulation. In-phantom and exit film dosimetry were performed on a flat phantom. Using the calculated responses and the algorithm, the exit film dose was used to inversely reconstruct the in-phantom dose, which was then compared with the measured in-phantom dose. The dose comparison in the phantom for all irradiated fields showed a pass rate of higher than 90% dose points given the criteria of dose difference of 3% and distance to agreement of 3 mm.

  11. Thorium-232 in human tissues: Metabolic parameters and radiation doses

    SciTech Connect

    Stehney, A.F.

    1994-09-01

    Higher than environmental levels of {sup 232}Th have been found in autopsy samples of lungs and other organs from four former employees of a Th refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Concentrations of {sup 232}Th in these samples and in tissues from two cases of non-occupational exposure were examined for compatibility with dosimetric models in Publication 30 of the International Commission on Radiological Protection (ICPP 1979a). The concentrations of {sup 232}Th in the lungs of the Th workers relative to the concentrations in bone or liver were much higher than calculated from the model for class Y aerosols of Th and the exposure histories of the subjects, and concentrations in the pulmonary lymph nodes were much lower than calculated for three of the Th workers and both non-occupational cases. Least-squares fits to the measured concentrations showed that the biological half-times of Th in liver, spleen, and kidneys are similar to the half-time in bone instead of the factor of 10 less suggested in Publication 30, and the fractions translocated from body fluids were found to be about 0.03, 0.02, and 0.005, respectively, when the fraction to bone was held at the suggested value of 0.7. Fitted values of the respiratory parameters differed significantly between cases and the differences were ascribable to aerosol differences. Average inhalation rates calculated for individual Th workers ranged from 50 to 110 Bq {sup 232}Th y{sup {minus}1}, and dose equivalents as high as 9.3 Sv to the lungs, 2.0 Sv to bone surfaces, and 1.1 Sv effective dose equivalent were calculated from the inhalation rates and fitted values of the metabolic parameters. The radiation doses were about the same when calculated from parameter values fitted with an assumed translocation fraction of 0.2 from body fluids to bone instead of 0.7.

  12. Characterization of radiation-induced performance decrement using a two-lever shock-avoidance task

    SciTech Connect

    Burghardt, W.F. Jr.; Hunt, W.A.

    1985-07-01

    Rats were trained to perform a task involving responses on two levers. Responding on an avoidance lever delayed the onset of electrical footshock for 20 sec and responding on a warning lever turned on a light for 60 sec. When the light was on, the task on the avoidance lever was changed from unsignaled shock avoidance to signaled shock avoidance by preceding the shocks with 5-sec warning tones. The animals preferred the signaled avoidance condition. After 100 Gy of /sup 60/Co irradiation, the animals were less able to avoid shock, an effect from which the animals recovered somewhat over 90 min. The response rate on the avoidance lever remained at or above control rates, while the response rate on the warning lever showed an initial increase, followed by a decrease below baseline. The data suggest that under these experimental conditions a subject will not respond appropriately to avoid shock or acquire cues that can facilitate the avoidance of shock. The effects, however, do not reflect an inability to perform the required movements but instead appear to reflect some characteristic of the task associated with a particular lever.

  13. Monitoring the radiation dose to a multiprogrammable pacemaker during radical radiation therapy: A case report

    SciTech Connect

    Muller-Runkel, R.; Orsolini, G.; Kalokhe, U.P. )

    1990-11-01

    Multiprogrammable pacemakers, using complimentary metaloxide semiconductor (CMOS) circuitry, may fail during radiation therapy. We report about a patient who received 6,400 cGy for unresectable carcinoma of the left lung. In supine treatment position, arms raised above the head, the pacemaker was outside the treated area by a margin of at least 1 cm, shielded by cerrobend blocking mounted on a tray. From thermoluminescent dosimeter (TLD) measurements, we estimate that the pacemaker received 620 cGy in scatter doses. Its function was monitored before, during, and after completion of radiation therapy. The pacemaker was functioning normally until the patient's death 5 months after completion of treatment. The relevant electrocardiograms (ECGs) are presented.

  14. Dose-dependent hepatic transcriptional responses in Atlantic salmon (Salmo salar) exposed to sublethal doses of gamma radiation.

    PubMed

    Song, You; Salbu, Brit; Teien, Hans-Christian; Heier, Lene Sørlie; Rosseland, Bjørn Olav; Tollefsen, Knut Erik

    2014-11-01

    Due to the production of free radicals, gamma radiation may pose a hazard to living organisms. The high-dose radiation effects have been extensively studied, whereas the ecotoxicity data on low-dose gamma radiation is still limited. The present study was therefore performed using Atlantic salmon (Salmo salar) to characterize effects of low-dose (15, 70 and 280 mGy) gamma radiation after short-term (48h) exposure. Global transcriptional changes were studied using a combination of high-density oligonucleotide microarrays and quantitative real-time reverse transcription polymerase chain reaction (qPCR). Differentially expressed genes (DEGs; in this article the phrase gene expression is taken as a synonym of gene transcription, although it is acknowledged that gene expression can also be regulated, e.g., at protein stability and translational level) were determined and linked to their biological meanings predicted using both Gene Ontology (GO) and mammalian ortholog-based functional analyses. The plasma glucose level was also measured as a general stress biomarker at the organism level. Results from the microarray analysis revealed a dose-dependent pattern of global transcriptional responses, with 222, 495 and 909 DEGs regulated by 15, 70 and 280 mGy gamma radiation, respectively. Among these DEGs, only 34 were commonly regulated by all radiation doses, whereas the majority of differences were dose-specific. No GO functions were identified at low or medium doses, but repression of DEGs associated with GO functions such as DNA replication, cell cycle regulation and response to reactive oxygen species (ROS) were observed after 280mGy gamma exposure. Ortholog-based toxicity pathway analysis further showed that 15mGy radiation affected DEGs associated with cellular signaling and immune response; 70mGy radiation affected cell cycle regulation and DNA damage repair, cellular energy production; and 280mGy radiation affected pathways related to cell cycle regulation and DNA

  15. Estimation of Effective Doses for Radiation Cancer Risks on ISS, Lunar, and Mars Missions with Space Radiation Measurement

    NASA Technical Reports Server (NTRS)

    Kim, M.Y.; Cucinotta, F.A.

    2005-01-01

    Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. The Phantom Torso Experiment (PTE) of NASA s Operational Radiation Protection Program has provided the actual flight measurements of active and passive dosimeters which were placed throughout the phantom on STS-91 mission for 10 days and on ISS Increment 2 mission. For the PTE, the variation in organ doses, which is resulted by the absorption and the changes in radiation quality with tissue shielding, was considered by measuring doses at many tissue sites and at several critical body organs including brain, colon, heart, stomach, thyroid, and skins. These measurements have been compared with the organ dose calculations obtained from the transport models. Active TEPC measurements of lineal energy spectra at the surface of the PTE also provided the direct comparison of galactic cosmic ray (GCR) or trapped proton dose and dose equivalent. It is shown that orienting the phantom body as actual in ISS is needed for the direct comparison of the transport models to the ISS data. One of the most important observations for organ dose equivalent of effective dose estimates on ISS is the fractional contribution from trapped protons and GCR. We show that for most organs over 80% is from GCR. The improved estimation of effective doses for radiation cancer risks will be made with the resultant tissue weighting factors and the modified codes.

  16. Second Solid Cancers After Radiation Therapy: A Systematic Review of the Epidemiologic Studies of the Radiation Dose-Response Relationship

    SciTech Connect

    Berrington de Gonzalez, Amy; Gilbert, Ethel; Curtis, Rochelle; Inskip, Peter; Kleinerman, Ruth; Morton, Lindsay; Rajaraman, Preetha; Little, Mark P.

    2013-06-01

    Rapid innovations in radiation therapy techniques have resulted in an urgent need for risk projection models for second cancer risks from high-dose radiation exposure, because direct observation of the late effects of newer treatments will require patient follow-up for a decade or more. However, the patterns of cancer risk after fractionated high-dose radiation are much less well understood than those after lower-dose exposures (0.1-5 Gy). In particular, there is uncertainty about the shape of the dose-response curve at high doses and about the magnitude of the second cancer risk per unit dose. We reviewed the available evidence from epidemiologic studies of second solid cancers in organs that received high-dose exposure (>5 Gy) from radiation therapy where dose-response curves were estimated from individual organ-specific doses. We included 28 eligible studies with 3434 second cancer patients across 11 second solid cancers. Overall, there was little evidence that the dose-response curve was nonlinear in the direction of a downturn in risk, even at organ doses of ≥60 Gy. Thyroid cancer was the only exception, with evidence of a downturn after 20 Gy. Generally the excess relative risk per Gray, taking account of age and sex, was 5 to 10 times lower than the risk from acute exposures of <2 Gy among the Japanese atomic bomb survivors. However, the magnitude of the reduction in risk varied according to the second cancer. The results of our review provide insights into radiation carcinogenesis from fractionated high-dose exposures and are generally consistent with current theoretical models. The results can be used to refine the development of second solid cancer risk projection models for novel radiation therapy techniques.

  17. Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions

    NASA Technical Reports Server (NTRS)

    McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.

    2012-01-01

    Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.

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

    PubMed

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

    2016-01-22

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

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  1. Displaying 3D radiation dose on endoscopic video for therapeutic assessment and surgical guidance.

    PubMed

    Qiu, Jimmy; Hope, Andrew J; Cho, B C John; Sharpe, Michael B; Dickie, Colleen I; DaCosta, Ralph S; Jaffray, David A; Weersink, Robert A

    2012-10-21

    We have developed a method to register and display 3D parametric data, in particular radiation dose, on two-dimensional endoscopic images. This registration of radiation dose to endoscopic or optical imaging may be valuable in assessment of normal tissue response to radiation, and visualization of radiated tissues in patients receiving post-radiation surgery. Electromagnetic sensors embedded in a flexible endoscope were used to track the position and orientation of the endoscope allowing registration of 2D endoscopic images to CT volumetric images and radiation doses planned with respect to these images. A surface was rendered from the CT image based on the air/tissue threshold, creating a virtual endoscopic view analogous to the real endoscopic view. Radiation dose at the surface or at known depth below the surface was assigned to each segment of the virtual surface. Dose could be displayed as either a colorwash on this surface or surface isodose lines. By assigning transparency levels to each surface segment based on dose or isoline location, the virtual dose display was overlaid onto the real endoscope image. Spatial accuracy of the dose display was tested using a cylindrical phantom with a treatment plan created for the phantom that matched dose levels with grid lines on the phantom surface. The accuracy of the dose display in these phantoms was 0.8-0.99 mm. To demonstrate clinical feasibility of this approach, the dose display was also tested on clinical data of a patient with laryngeal cancer treated with radiation therapy, with estimated display accuracy of ∼2-3 mm. The utility of the dose display for registration of radiation dose information to the surgical field was further demonstrated in a mock sarcoma case using a leg phantom. With direct overlay of radiation dose on endoscopic imaging, tissue toxicities and tumor response in endoluminal organs can be directly correlated with the actual tissue dose, offering a more nuanced assessment of normal tissue

  2. Improving pediatric radiation dose management using Agfa digital radiography DICOM header information.

    PubMed

    Juste, B; Villaescusa, N; Granero, D; Verdú, G

    2007-01-01

    Dose reduction in pediatric explorations is especially important because of children radiation sensitivity. According to this, with the aim of saving radiation exposure in future clinical practice, we have developed a technique to control delivered dose in pediatric radiographic exams. To that, a computer science program has been developed to calculate entrance skin dose (ESD) provided by AGFA radiology digital system, using the "lgM" parameter exported from Dicom files. ESD values are compared with dose limits established in regulations to detect if children are being exposed to excessive amounts of radiation during their explorations.

  3. Estimation of Internal Radiation Dose from both Immediate Releases and Continued Exposures to Contaminated Materials

    SciTech Connect

    Napier, Bruce A.

    2012-03-26

    A brief description is provided of the basic concepts related to 'internal dose' and how it differs from doses that result from radioactive materials and direct radiation outside of the body. The principles of radiation dose reconstruction, as applied to both internal and external doses, is discussed based upon a recent publication prepared by the US National Council on Radiation Protection and Measurements. Finally, ideas are introduced related to residual radioactive contamination in the environment that has resulted from the releases from the damaged reactors and also to the management of wastes that may be generated in both regional cleanup and NPP decommissioning.

  4. Comparison of radiation dose to operator between transradial and transfemoral coronary angiography with optimised radiation protection: a phantom study.

    PubMed

    Liu, Huiliang; Jin, Zhigeng; Jing, Limin

    2014-03-01

    A growing concern in applying radial access in cardiac catheterisation is the increased operator radiation exposure. This study used an anthropomorphic phantom to simulate transradial and transfemoral coronary angiography with optimised radiation protection conditions. Operator radiation exposure was measured with thermoluminescent dosemeters at predefined locations. Compared with the femoral route, the radial route was associated with a dose decrease of 15 % at the operator's chest level with optimised radiation shielding. However, radiation exposure to the operator's hand remained significantly higher when applying radial access even with collective protective equipment used (by a factor of 2). Furthermore, the efficiency of operator radiation protection was found to be dependent on the tube incidence. Awareness should be raised about the significant increase of radiation exposure to operators' hands in transradial coronary angiography. Protection to reduce the dose level to the hands is necessary and should be further improved.

  5. Dosimetry experiences and lessons learned for radiation dose assessment in Korean nuclear power plants.

    PubMed

    Choi, Jong Rak; Kim, Hee Geun; Kong, Tae Young; Son, Jung Kwon

    2013-07-01

    Since the first Korean nuclear power plant (NPP), Kori 1, commenced operation in 1978, a total of 21 NPPs had been put into operation in Korea by the end of 2011. Radiation doses of NPP workers have been periodically evaluated and controlled within the prescribed dose limit. Radiation dose assessment is carried out monthly by reading personal dosemeters for external radiation exposure, which have traceability in compliance with strict technical guidelines. In the case of the internal radiation exposure, workers who have access to the possible area of polluted air are also evaluated for their internal dose after maintenance task. In this article, the overall situation and experience for the assessment and distribution of radiation doses in Korean NPPs is described.

  6. The source-skin distance measuring bridge: A method to avoid radiation teleangiectasia in the skin after interstitial therapy for breast cancer

    SciTech Connect

    Van Limbergen, E.; Briot, E.; Drijkoningen, M. )

    1990-05-01

    Inappropriate positioning of interstitial iridium 192 implants, used as booster dose in the breast conserving treatment of mammary cancer, may cause disturbing teleangiectasia of the breast skin, when high radiation doses are delivered on the dermal blood vessels. Based on the localization of the vascular plexuses in human breast skin, and on the dose distribution around different types of interstitial implants, a method is described to avoid overlap between the high dose area of the implant and the blood vessels in the skin. The latter are demonstrated to run within the first 5 mm under the epiderm. For source lengths varying from 5 to 8 cm, simple mathematical relations exist between the maximal security margin (MSM) and intersource distance (E) for single plane implants (MSM = 0.4 (E + 1)), double plane square implants (MSM = 0.4 E) and double plane triangular implants (MSM = 0.4 (E - 1)). We developed a device to measure precisely the distance between the radioactive wires and the overlying skin, along the whole source trajectory. Using this method, the occurrence of teleangiectasia in the breast skin after interstitial implants with Ir 192 may be significantly reduced.

  7. Radiation dose to patient and personnel during extracorporeal shock wave lithotripsy

    SciTech Connect

    Bush, W.H.; Jones, D.; Gibbons, R.P.

    1987-10-01

    Radiation dose to the patient and personnel was determined during extracorporeal shock wave lithotripsy treatment of 60 patients. Surface radiation dose to the patient's back from the fluoroscopy unit on the side with the kidney stone averaged 10 rem (100 mSv.) per case, although the range was wide (1 to 30 rem). The surface dose from the opposing biplane x-ray unit was less, averaging 5.5 rem (55 mSv.) per case but again with a wide range (0.1 to 21 rem). Exit dose at the lower abdomen averaged 13 mrem. (0.13 mSv.) per case and estimated female gonad dose averaged 100 mrem. (1.2 mSv.). Radiation dose to personnel working in the extracorporeal shock wave lithotripsy suite averaged less than 2 mrem. (0.02 mSv.) per case, making it a procedure that is safe in regard to radiation exposure.

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

    PubMed Central

    Corre, Isabelle; Guillonneau, Maëva; Paris, François

    2013-01-01

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

  9. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    SciTech Connect

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  10. Behavioral and physiological changes produced by a supralethal dose of ionizing radiation: evidence for hormone-influenced sex differences in the rat

    SciTech Connect

    Mickley, G.A.

    1980-01-01

    A sufficiently large and rapid dose of ionizing radiation produces an immediate but transient behavioral incapacitation. Acute hypotension often accompanies the disorder. Although the etiology of this syndrome is unclear, it has been suggested that an increase in histamine excretion contributes to it. Since histamine is known to interact with the endocrine system and since estrogens have been shown to prolong the life of animals exposed to potentially lethal doses of radiation, it was also hypothesized that females might be relatively less affected by an acute, large dose of ionizing radiation. Male and female rats were trained on an avoidance task, irradiated, and then retested. Females showed a less severe decrement after radiation exposure than males. Likewise, females did not suffer the severe hypotension normally associated with male radiogenic early transient incapacitation (ETI); rather, an acute hypertension was produced in females. A second series of experiments revealed that differences in male and female radiation response were eliminated by gonadectomy. Systemic estradiol injection produced strikingly feminine (i.e., superior) postirradiation avoidance responses as well as hypertension in neutered rats. Testosterone injections had no effect on either measure. Central nervous system alterations have been correlated with the ETI. Therefore, final experiments sought a possible central locus of the action of estradiol. It was found that exposure of the nucleus peopticus medialis to estrogens produces postirradiation benefits in avoidance performance and blood pressure similar to those seen after systemic estradiol treatments. Nucleus amygdaloideus medialis implants produced no such benefits.

  11. Emesis in Ferrets Following Exposure to Different Types of Radiation: A Dose-Response Study

    DTIC Science & Technology

    1992-08-01

    SR92-34 Emesis in Ferrets Following Exposure to Different Types of Radiation: N A Dose -Response Study L51 BERNARD M. RABIN, Ph.D., WALTER A. HUNT...fission neutrons (1500-2000 following exposure to different types o" radiation: a dose -response cGy), Young (13) reported that increasing the propor...order to establish the dose -response relationships monkey, but did not produce an increase in the total for emesis following exposure to different types

  12. Retrospective Reconstruction of Radiation Doses of Chernobyl Liquidators by Electron Paramagnetic Resonance

    DTIC Science & Technology

    1997-12-01

    Armed Forces Rad I Research Institute Retrospective Reconstruction of Radiation Doses of Chernobyl Liquidators by Electron Paramagnetic Resonance A...of Radiation Doses of Chernobyl Liquidators by Electron Paramagnetic Resonance Authored by Scientific Center of Radiation Medicine Academy of Medical...libraries associated with the U.S. Government’s Depository Library System. Preface On April 26, 1986, Reactor #4 at the Chernobyl Nuclear Power Plant near

  13. Total-dose radiation effects data for semiconductor devices, volume 2

    NASA Technical Reports Server (NTRS)

    Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

    1981-01-01

    Total ionizing dose radiation test data on integrated circuits are analyzed. Tests were performed with the electron accelerator (Dynamitron) that provides a steady state 2.5 MeV electron beam. Some radiation exposures were made with a Cobalt-60 gamma ray source. The results obtained with the Cobalt-60 source are considered an approximate measure of the radiation damage that would be incurred by an equivalent dose of electrons.

  14. Radiation Doses of Various CT Protocols: a Multicenter Longitudinal Observation Study

    PubMed Central

    2016-01-01

    Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiation doses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiation dose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiation dose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiation doses were decreased during the 3 years. This study showed the effects of decreased CT radiation dose by efforts of radiologists and medical society. PMID:26908984

  15. Method for inserting noise in digital mammography to simulate reduction in radiation dose

    NASA Astrophysics Data System (ADS)

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Vieira, Marcelo A. C.

    2015-03-01

    The quality of clinical x-ray images is closely related to the radiation dose used in the imaging study. The general principle for selecting the radiation is ALARA ("as low as reasonably achievable"). The practical optimization, however, remains challenging. It is well known that reducing the radiation dose increases the quantum noise, which could compromise the image quality. In order to conduct studies about dose reduction in mammography, it would be necessary to acquire repeated clinical images, from the same patient, with different dose levels. However, such practice would be unethical due to radiation related risks. One solution is to simulate the effects of dose reduction in clinical images. This work proposes a new method, based on the Anscombe transformation, which simulates dose reduction in digital mammography by inserting quantum noise into clinical mammograms acquired with the standard radiation dose. Thus, it is possible to simulate different levels of radiation doses without exposing the patient to new levels of radiation. Results showed that the achieved quality of simulated images generated with our method is the same as when using other methods found in the literature, with the novelty of using the Anscombe transformation for converting signal-independent Gaussian noise into signal-dependent quantum noise.

  16. High and Low Doses of Ionizing Radiation Induce Different Secretome Profiles in a Human Skin Model

    SciTech Connect

    Zhang, Qibin; Matzke, Melissa M.; Schepmoes, Athena A.; Moore, Ronald J.; Webb-Robertson, Bobbie-Jo M.; Hu, Zeping; Monroe, Matthew E.; Qian, Weijun; Smith, Richard D.; Morgan, William F.

    2014-03-18

    It is postulated that secreted soluble factors are important contributors of bystander effect and adaptive responses observed in low dose ionizing radiation. Using multidimensional liquid chromatography-mass spectrometry based proteomics, we quantified the changes of skin tissue secretome – the proteins secreted from a full thickness, reconstituted 3-dimensional skin tissue model 48 hr after exposure to 3, 10 and 200 cGy of X-rays. Overall, 135 proteins showed statistical significant difference between the sham (0 cGy) and any of the irradiated groups (3, 10 or 200 cGy) on the basis of Dunnett adjusted t-test; among these, 97 proteins showed a trend of downregulation and 9 proteins showed a trend of upregulation with increasing radiation dose. In addition, there were 21 and 8 proteins observed to have irregular trends with the 10 cGy irradiated group either having the highest or the lowest level among all three radiated doses. Moreover, two proteins, carboxypeptidase E and ubiquitin carboxyl-terminal hydrolase isozyme L1 were sensitive to ionizing radiation, but relatively independent of radiation dose. Conversely, proteasome activator complex subunit 2 protein appeared to be sensitive to the dose of radiation, as rapid upregulation of this protein was observed when radiation doses were increased from 3, to 10 or 200 cGy. These results suggest that different mechanisms of action exist at the secretome level for low and high doses of ionizing radiation.

  17. 76 FR 72416 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ... Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health... promulgated by the Department of Health and Human Services (HHS) as a final rule; advice on methods of dose... quality of dose estimation and reconstruction efforts being performed for purposes of the...

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

    SciTech Connect

    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

  19. Correlating planned radiation dose to the cochlea with primary site and tumor stage in patients with head and neck cancer treated with intensity-modulated radiation therapy

    SciTech Connect

    Zhang, Jeanette; Qureshi, Muhammad M.; Kovalchuk, Nataliya; Truong, Minh Tam

    2014-04-01

    The aim of the study was to determine tumor characteristics that predict higher planned radiation (RT) dose to the cochlea in patients with head and neck cancer (HNC) treated with intensity-modulated radiotherapy (IMRT). From 2004 to 2012, 99 patients with HNC underwent definitive IMRT to a median dose of 69.96 Gy in 33 fractions, with the right and left cochlea-vestibular apparatus contoured for IMRT optimization as avoidance structures. If disease involvement was adjacent to the cochlea, preference was given to tumor coverage by prescription dose. Descriptive statistics were calculated for dose-volume histogram planning data, and mean planning dose to the cochlea (from left or right cochlea, receiving the greater amount of RT dose) was correlated to primary site and tumor stage. Mean (standard deviation) cochlear volume was 1.0 (0.60) cm{sup 3} with maximum and mean planned doses of 31.9 (17.5) Gy and 22.1 (13.7) Gy, respectively. Mean planned dose (Gy) to cochlea by tumor site was as follows: oral cavity (18.6, 14.4), oropharynx (21.7, 9.1), nasopharynx (36.3, 10.4), hypopharynx (14.9, 7.1), larynx (2.1, 0.62), others including the parotid gland, temporal bone, and paranasal sinus (33.6, 24.0), and unknown primary (25.6, 6.7). Average mean planned dose (Gy) to the cochlea in T0-T2 and T3-T4 disease was 22.0 and 29.2 Gy, respectively (p = 0.019). By site, a significant difference was noted for nasopharynx and others (31.6 and 50.7, p = 0.012) but not for oropharynx, oral cavity, and hypopharynx. Advanced T category predicted for higher mean cochlear dose, particularly for nasopharyngeal, parotid gland, temporal bone, and paranasal sinus HNC sites.

  20. 78 FR 53147 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ... (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... employees at any Department of Energy facility who were exposed to radiation but for whom it is not feasible to estimate their radiation dose, and on whether there is reasonable likelihood that such...

  1. 78 FR 14303 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... employees at any Department of Energy facility who were exposed to radiation but for whom it is not feasible to estimate their radiation dose, and on whether there is reasonable likelihood that such...

  2. Total-dose radiation effects data for semiconductor devices (1989 supplement)

    NASA Technical Reports Server (NTRS)

    Martin, Keith E.; Coss, James R.; Goben, Charles A.; Shaw, David C.; Farmanesh, Sam; Davarpanah, Michael M.; Craft, Leroy H.; Price, William E.

    1990-01-01

    Steady state, total dose radiation test data are provided for electronic designers and other personnel using semiconductor devices in a radiation environment. The data are presented in graphic and narrative formats. Two primary radiation source types were used: Cobalt-60 gamma rays and a Dynamitron electron accelerator capable of delivering 2.5 MeV electrons at a steady rate.

  3. New model for assessing dose, dose rate, and temperature sensitivity of radiation-induced absorption in glasses

    SciTech Connect

    Gilard, Olivier; Quadri, Gianandrea; Caussanel, Matthieu; Duval, Herve; Reynaud, Francois

    2010-11-15

    A new theoretical approach is proposed to explain the dose, dose rate and temperature sensitivity of the radiation-induced absorption (RIA) in glasses. In this paper, a {beta}{sup th}-order dispersive kinetic model is used to simulate the growth of the density of color centers in irradiated glasses. This model yields an explanation for the power-law dependence on dose and dose rate usually observed for the RIA in optical fibers. It also leads to an Arrhenius-like relationship between the RIA and the glass temperature during irradiation. With a very limited number of adjustable parameters, the model succeeds in explaining, with a good agreement, the RIA growth of two different optical fiber references over wide ranges of dose, dose rate and temperature.

  4. Radiation Dose Deposition in the Active Marrow of Reference Man.

    DTIC Science & Technology

    1977-10-31

    gamma ray-fission neutron exposure , the relative biological effec- tiveness (RBE) per unit marrow dose between neutrons and gamma rays in producing...calculations in terms of marrow dose (rad (marrow)) per unit incident fluence. The third presents in- tegral marrow doses calculated for exposure to...in the marrow than other devices. This is shown by the fact that the neutron dose deposited by a given total exposure from such a de- vice is as much

  5. [New mammography technologies and their impact on radiation dose].

    PubMed

    Chevalier del Rio, M

    2013-12-01

    This article reviews new mammography technologies resulting from advances in digital detectors and processing techniques. Most are just starting to be commercialized or are in the clinical trial phase. The results of clinical trials with the new 2D techniques (contrast-enhanced techniques or stereotactic techniques) show they are useful for diagnosing cancer. However, the greater complexity of the image acquisition process suggests that their use will be limited to particular cases such as inconclusive lesions or women with high risk for developing breast cancer. Among the 3D technologies (breast tomography and breast tomosynthesis), only breast tomosynthesis has been implemented in clinical practice, so it is the only technique for which it is possible to know the sensitivity, specificity, and radiation dose delivered. This article describes the principles underlying the way breast tomosynthesis works and the techniques used for image acquisition and reconstruction. It also summarizes the main results obtained in clinical studies, which generally show that breast tomosynthesis increases the breast cancer detection rate while decreasing the recall rate and number of biopsies taken. The protocol for breast tomosynthesis approved by the Food and Drug Administration (USA) consists of two conventional mammography projections for each breast and two tomosynthesis projections for each breast. This means multiplying the risks of inducing cancer and death associated with 2D mammography by a factor between 2 and 3 (2.6-3.3 and 0.7-0.9 per 100,000 women exposed when 50 years old, respectively). The protocol for breast tomosynthesis examinations is one of the aspects that is essential to determine when including tomosynthesis in screening programs and routine breast imaging.

  6. Gastrointestinal Dose-Histogram Effects in the Context of Dose-Volume–Constrained Prostate Radiation Therapy: Analysis of Data From the RADAR Prostate Radiation Therapy Trial

    SciTech Connect

    Ebert, Martin A.; Foo, Kerwyn; Haworth, Annette; Gulliford, Sarah L.; Kennedy, Angel; Joseph, David J.; Denham, James W.

    2015-03-01

    Purpose: To use a high-quality multicenter trial dataset to determine dose-volume effects for gastrointestinal (GI) toxicity following radiation therapy for prostate carcinoma. Influential dose-volume histogram regions were to be determined as functions of dose, anatomical location, toxicity, and clinical endpoint. Methods and Materials: Planning datasets for 754 participants in the TROG 03.04 RADAR trial were available, with Late Effects of Normal Tissues (LENT) Subjective, Objective, Management, and Analytic (SOMA) toxicity assessment to a median of 72 months. A rank sum method was used to define dose-volume cut-points as near-continuous functions of dose to 3 GI anatomical regions, together with a comprehensive assessment of significance. Univariate and multivariate ordinal regression was used to assess the importance of cut-points at each dose. Results: Dose ranges providing significant cut-points tended to be consistent with those showing significant univariate regression odds-ratios (representing the probability of a unitary increase in toxicity grade per percent relative volume). Ranges of significant cut-points for rectal bleeding validated previously published results. Separation of the lower GI anatomy into complete anorectum, rectum, and anal canal showed the impact of mid-low doses to the anal canal on urgency and tenesmus, completeness of evacuation and stool frequency, and mid-high doses to the anorectum on bleeding and stool frequency. Derived multivariate models emphasized the importance of the high-dose region of the anorectum and rectum for rectal bleeding and mid- to low-dose regions for diarrhea and urgency and tenesmus, and low-to-mid doses to the anal canal for stool frequency, diarrhea, evacuation, and bleeding. Conclusions: Results confirm anatomical dependence of specific GI toxicities. They provide an atlas summarizing dose-histogram effects and derived constraints as functions of anatomical region, dose, toxicity, and endpoint for

  7. High and low dose radiation effects on mammary adenocarcinoma cells - an epigenetic connection.

    PubMed

    Luzhna, Lidia; Filkowski, Jody; Kovalchuk, Olga

    2016-01-01

    The successful treatment of cancer, including breast cancer, depends largely on radiation therapy and proper diagnostics. The effect of ionizing radiation on cells and tissues depends on the radiation dose and energy level, but there is insufficient evidence concerning how tumor cells respond to the low and high doses of radiation that are often used in medical diagnostic and treatment modalities. The purpose of this study was to investigate radiation-induced gene expression changes in the MCF-7 breast adenocarcinoma cell line. Using microarray technology tools, we were able to screen the differential gene expressions profiles between various radiation doses applied to MCF-7 cells. Here, we report the substantial alteration in the expression level of genes after high-dose treatment. In contrast, no dramatic gene expression alterations were noticed after the application of low and medium doses of radiation. In response to a high radiation dose, MCF-7 cells exhibited down-regulation of biological pathways such as cell cycle, DNA replication, and DNA repair and activation of the p53 pathway. Similar dose-dependent responses were seen on the epigenetic level, which was tested by a microRNA expression analysis. MicroRNA analysis showed dose-dependent radiation-induced microRNA expression alterations that were associated with cell cycle arrest and cell death. An increased rate of apoptosis was determined by an Annexin V assay. The results of this study showed that high doses of radiation affect gene expression genetically and epigenetically, leading to alterations in cell cycle, DNA replication, and apoptosis.

  8. High and low dose radiation effects on mammary adenocarcinoma cells – an epigenetic connection

    PubMed Central

    Luzhna, Lidia; Filkowski, Jody; Kovalchuk, Olga

    2016-01-01

    The successful treatment of cancer, including breast cancer, depends largely on radiation therapy and proper diagnostics. The effect of ionizing radiation on cells and tissues depends on the radiation dose and energy level, but there is insufficient evidence concerning how tumor cells respond to the low and high doses of radiation that are often used in medical diagnostic and treatment modalities. The purpose of this study was to investigate radiation-induced gene expression changes in the MCF-7 breast adenocarcinoma cell line. Using microarray technology tools, we were able to screen the differential gene expressions profiles between various radiation doses applied to MCF-7 cells. Here, we report the substantial alteration in the expression level of genes after high-dose treatment. In contrast, no dramatic gene expression alterations were noticed after the application of low and medium doses of radiation. In response to a high radiation dose, MCF-7 cells exhibited down-regulation of biological pathways such as cell cycle, DNA replication, and DNA repair and activation of the p53 pathway. Similar dose-dependent responses were seen on the epigenetic level, which was tested by a microRNA expression analysis. MicroRNA analysis showed dose-dependent radiation-induced microRNA expression alterations that were associated with cell cycle arrest and cell death. An increased rate of apoptosis was determined by an Annexin V assay. The results of this study showed that high doses of radiation affect gene expression genetically and epigenetically, leading to alterations in cell cycle, DNA replication, and apoptosis. PMID:27226982

  9. Radiation fields and dose assessments in Korean nuclear power plants.

    PubMed

    Kim, Hee Geun; Kong, Tae Young; Jeong, Woo Tae; Kim, Seok Tae

    2011-07-01

    In the primary systems of nuclear power plants (NPPs), various radionuclides including fission products and corrosion products are generated due to the complex water chemistry conditions. In particular, (3)H, (14)C, (58)Co, (60)Co, (137)Cs, and (131)I are important or potential radionuclides with respect to dose assessment for workers and the management of radioactive effluents or dose assessment for the public. In this paper, the dominant contributors to the dose for workers and the public were reviewed and the process of dose assessment attributable to those contributors was investigated. Furthermore, an analysis was carried out on some examples of dose to workers during NPP operation.

  10. Animal Studies of Residual Hematopoietic and Immune System Injury from Low Dose/Low Dose Rate Radiation and Heavy Metals.

    DTIC Science & Technology

    1998-09-01

    accidents and industrial accidents (e.g., Chernobyl ) who receive high doses of radiation over a relatively short period of time, there are thousands of...several years after exposure may have been terminated. Examples of such groups include those affected by the fallout near Chernobyl , those living near...cohorts (e.g., Chernobyl victims) particular damage from low dose irradiation, especially membrane damage and mismatched DNA repair. Dosimetric Problems

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

    PubMed Central

    Rithidech, Kanokporn Noy; Scott, Bobby R.

    2008-01-01

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

  12. Reduction in stray radiation dose using a body-shielding device during external radiation therapy.

    PubMed

    Zhang, Shuxu; Jiang, Shaohui; Zhang, Quanbin; Lin, Shengqu; Wang, Ruihao; Zhou, Xiang; Zhang, Guoqian; Lei, Huaiyu; Yu, Hui

    2017-03-01

    With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD. In addition, SRDs in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%-80%; however, there were no significant differences in SRDs when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus (P>0.05). Importantly, the 10 mm bolus absorbed back-scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD. After shielding with BSD, total SRDs in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRDs at distances were not identical in anterior, posterior, left and right direction of phantom without BSD. As higher dose in anterior and lower dose in posterior, SRDs were substantial similarities after shielding. There was no significant difference in SRDs for left and right directions with or without shielding. Interestingly, SRDs in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during

  13. Does vertebroplasty affect radiation dose distribution?: comparison of spatial dose distributions in a cement-injected vertebra as calculated by treatment planning system and actual spatial dose distribution.

    PubMed

    Komemushi, Atsushi; Tanigawa, Noboru; Kariya, Shuji; Yagi, Rie; Nakatani, Miyuki; Suzuki, Satoshi; Sano, Akira; Ikeda, Koshi; Utsunomiya, Keita; Harima, Yoko; Sawada, Satoshi

    2012-01-01

    Purpose. To assess differences in dose distribution of a vertebral body injected with bone cement as calculated by radiation treatment planning system (RTPS) and actual dose distribution. Methods. We prepared two water-equivalent phantoms with cement, and the other two phantoms without cement. The bulk density of the bone cement was imported into RTPS to reduce error from high CT values. A dose distribution map for the phantoms with and without cement was calculated using RTPS with clinical setting and with the bulk density importing. Actual dose distribution was measured by the film density. Dose distribution as calculated by RTPS was compared to the dose distribution measured by the film dosimetry. Results. For the phantom with cement, dose distribution was distorted for the areas corresponding to inside the cement and on the ventral side of the cement. However, dose distribution based on film dosimetry was undistorted behind the cement and dose increases were seen inside cement and around the cement. With the equivalent phantom with bone cement, differences were seen between dose distribution calculated by RTPS and that measured by the film dosimetry. Conclusion. The dose distribution of an area containing bone cement calculated using RTPS differs from actual dose distribution.

  14. [Formation of optimum dose fields in contact radiation therapy of malignant tumors].

    PubMed

    Klepper, L Ia

    2003-01-01

    The definition of the homogeneity of a dose field in the contact radiation therapy for malignant tumors is introduced. The mathematical interpretation of problems in the formation of optimum dose fields, to which the maximum homogeneity of a dose field at the site of lesion corresponds, is presented. It is shown that the problems in the formation of optimum dose fields may be divided into two subsets in relation to whether the sources of radiation are located at the site of lesion or adjacent to the latter (application techniques of radiation). An analytical method for solving a problem in the formation of an optimal dose field in the ring circle by means of one ring source of radiation (the first type of problems). The investigation was conducted with the support of the Russian Fund of Fundamental Investigations (RFFI 01-01-00137).

  15. Dose Response for Chromosome Aberrations in Human Lymphocytes and Fibroblasts After Exposure to Very Low Dose of High Let Radiation

    NASA Technical Reports Server (NTRS)

    Hada, M.; George, K.; Chappell, L.; Cucinotta, F. A.

    2011-01-01

    The relationship between biological effects and low doses of absorbed radiation is still uncertain, especially for high LET radiation exposure. Estimates of risks from low-dose and low-dose-rates are often extrapolated using data from Japanese atomic bomb survivor with either linear or linear quadratic models of fit. In this study, chromosome aberrations were measured in human peripheral blood lymphocytes and normal skin fibroblasts cells after exposure to very low dose (0.01 - 0.20 Gy) of 170 MeV/u Si-28 ions or 600 MeV/u Fe-56 ions, including doses where on average less than one direct ion traversal per cell nucleus occurs. Chromosomes were analyzed using the whole-chromosome fluorescence in situ hybridization (FISH) technique during the first cell division after irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). The responses for doses above 0.1 Gy (more than one ion traverses a cell) showed linear dose responses. However, for doses less than 0.1 Gy, both Si-28 ions and Fe-56 ions showed a dose independent response above background chromosome aberrations frequencies. Possible explanations for our results are non-targeted effects due to aberrant cell signaling [1], or delta-ray dose fluctuations [2] where a fraction of cells receive significant delta-ray doses due to the contributions of multiple ion tracks that do not directly traverse cell nuclei where chromosome aberrations are scored.

  16. Dose painting to treat single-lobe prostate cancer with hypofractionated high-dose radiation using targeted external beam radiation: Is it feasible?

    SciTech Connect

    Amini, Arya; Westerly, David C.; Waxweiler, Timothy V.; Ryan, Nicole; Raben, David

    2015-10-01

    Targeted focal therapy strategies for treating single-lobe prostate cancer are under investigation. In this planning study, we investigate the feasibility of treating a portion of the prostate to full-dose external beam radiation with reduced dose to the opposite lobe, compared with full-dose radiation delivered to the entire gland using hypofractionated radiation. For 10 consecutive patients with low- to intermediate-risk prostate cancer, 2 hypofractionated, single-arc volumetric-modulated arc therapy (VMAT) plans were designed. The first plan (standard hypofractionation regimen [STD]) included the entire prostate gland, treated to 70 Gy delivered in 28 fractions. The second dose painting plan (DP) encompassed the involved lobe treated to 70 Gy delivered in 28 fractions, whereas the opposing, uninvolved lobe received 50.4 Gy in 28 fractions. Mean dose to the opposing neurovascular bundle (NVB) was considerably lower for DP vs STD, with a mean dose of 53.9 vs 72.3 Gy (p < 0.001). Mean penile bulb dose was 18.6 Gy for DP vs 19.2 Gy for STD (p = 0.880). Mean rectal dose was 21.0 Gy for DP vs 22.8 Gy for STD (p = 0.356). Rectum V{sub 70} (the volume receiving ≥70 Gy) was 2.01% for DP vs 2.74% for STD (p = 0.328). Bladder V{sub 70} was 1.69% for DP vs 2.78% for STD (p = 0.232). Planning target volume (PTV) maximum dose points were 76.5 and 76.3 Gy for DP and STD, respectively (p = 0.760). This study demonstrates the feasibility of using VMAT for partial-lobe prostate radiation in patients with prostate cancer involving 1 lobe. Partial-lobe prostate plans appeared to spare adjacent critical structures including the opposite NVB.

  17. Adaption By Low Dose Radiation Exposure: A Look at Scope and Limitations for Radioprotection.

    PubMed

    Mitchel, Ron E J

    2015-01-01

    The procedures and dose limitations used for radiation protection in the nuclear industry are founded on the assumption that risk is directly proportional to dose, without a threshold. Based on this idea that any dose, no matter how small, will increase risk, radiation protection regulations generally attempt to reduce any exposure to "as low as reasonably achievable" (ALARA). We know however, that these regulatory assumptions are inconsistent with the known biological effects of low doses. Low doses induce protective effects, and these adaptive responses are part of a general response to low stress. Adaptive responses have been tightly conserved during evolution, from single celled organisms up to humans, indicating their importance. Here we examine cellular and animal studies that show the influence of radiation induced protective effects on diverse diseases, and examine the radiation dose range that is effective for different tissues in the same animal. The concept of a dose window, with upper and lower effective doses, as well as the effect of multiple stressors and the influence of genetics will also be examined. The effect of the biological variables on low dose responses will be considered from the point of view of the limitations they may impose on any revised radiation protection regulations.

  18. Correlation between scatter radiation dose at height of operator's eye and dose to patient for different angiographic projections.

    PubMed

    Leyton, Fernando; Nogueira, Maria S; Gubolino, Luiz A; Pivetta, Makyson R; Ubeda, Carlos

    2016-11-01

    Studies have reported cases of radiation-induced cataract among cardiology professionals. In view of the evidence of epidemiological studies, the ICRP recommends a new threshold for opacities and a new radiation dose to eye lens limit of 20mSv per year for occupational exposure. The aim of this paper is to report scattered radiation doses at the height of the operator's eye in an interventional cardiology facility without considering radiation protection devices and to correlate these values with different angiographic projections and operational modes. Measurements were taken in a cardiac laboratory with an angiography X-ray system equipped with flat-panel detector. PMMA plates of 30×30×5cm were used with a thickness of 20cm. Measurements were taken in two fluoroscopy modes (low and normal, 15pulses/s) and in cine mode (15frames/s). Four angiographic projections were used: anterior posterior; lateral; left anterior oblique caudal (spider); and left anterior oblique cranial, with a cardiac protocol for patients weighing between 70 and 90kg. Measurements of phantom entrance dose rate and scatter dose rate were performed with two Unfors Xi plus detectors. The detector measuring scatter radiation was positioned at the usual distance of the cardiologist's eyes during working conditions. There is a good linear correlation between the kerma area product and scatter dose at the lens. Experimental correlation factors of 2.3, 12.0, 12.2 and 17.6μSv/Gycm2 were found for different projections. PMMA entrance dose rates for low and medium fluoroscopy and cine modes were 13, 39 and 282mGy/min, respectively, for AP projection.

  19. Radiation dose implications of airborne contaminant deposition to humans.

    PubMed

    Andersson, K G; Fogh, C L; Byrne, M A; Roed, J; Goddard, A J H; Hotchkiss, S A M

    2002-02-01

    In nuclear accident consequence assessment, dose contributions from radionuclide deposition on the human body have in the past generally been either ignored or estimated on the basis of rather simple models. Recent experimental work has improved the state of knowledge of relevant processes and parameter ranges. The results presented in this paper represent a first approach to a detailed assessment of doses from radiopollutant deposition on the human body, based on contaminant-specific data. Both the dose to skin from beta-emitters and the whole-body dose from gamma-emitters on body surfaces were found to give potentially significant contributions to dose. Further, skin penetration of some contaminants could lead to significant internal doses.

  20. Final Technical Report for the grant entitled "Genetic Factors Affecting Susceptibility to Low-Dose Radiation"

    SciTech Connect

    Morgan, William, F., Ph.D., D.Sc.

    2006-11-22

    The goal of this proposal was to test the hypothesis that mice heterozygous for the Nijmegen Breakage Syndrome (NBS1) gene are genetically susceptible to low doses of ionizing radiation. The rationale for this is that patients with NBS are radiation sensitive, because of defects in cellular responses to radiation induced genetic damage and haploinsufficiency at this genetic locus provides the potential for genetic susceptibility to low doses of ionizing radiation. Wild type and heterozygous NBS1 mice were irradiated and followed over their lifetime for radiation induced genomic instability, carcinogenesis and non-specific life shortening. No differences in cytogenetic damage, cancer induction or life span were observed between the hypomorphic mice indicating that genetic imbalance at the NBS1 loci does not modulate low dose radiation sensitivity.

  1. Influence of organs in the ICRP's remainder on effective dose equivalent computed for diagnostic radiation exposures

    SciTech Connect

    Gibbs, S.J.

    1989-04-01

    The ICRP effective dose equivalent has been compared with a weighted dose equivalent, computed by treating the entire remainder instead of the sample of five remainder organs in the ICRP method as uniformly radiosensitive, for dose distributions from three common diagnostic exposures: chest, dental full-mouth and dental panoramic. Complete dose distributions were computed by a Monte Carlo model. In all three cases the effective dose equivalent was greater than the weighted dose equivalent. The difference was only 20% for the chest exam but was more than fivefold for both dental exposures. Dose distributions for the dental exposures were less homogeneous than for the chest examination. Selection of organs to be included in the remainder markedly affects the effective dose equivalent. In the case of highly inhomogeneous dose distributions, the effective dose equivalent probably significantly over-estimates radiation detriment.

  2. Risk equivalent of exposure versus dose of radiation

    SciTech Connect

    Bond, V.P.

    1986-01-01

    This report describes a risk analysis study of low-dose irradiation and the resulting biological effects on a cell. The author describes fundamental differences between the effects of high-level exposure (HLE) and low-level exposure (LLE). He stresses that the concept of absorbed dose to an organ is not a dose but a level of effect produced by a particular number of particles. He discusses the confusion between a linear-proportional representation of dose limits and a threshold-curvilinear representation, suggesting that a LLE is a composite of both systems. (TEM)

  3. Dose Response for Chromosome Aberrations in Human Lymphocytes and Fibroblasts after Exposure to Very Low Doses of High LET Radiation

    NASA Technical Reports Server (NTRS)

    Hada, M.; George, Kerry; Cucinotta, Francis A.

    2011-01-01

    The relationship between biological effects and low doses of absorbed radiation is still uncertain, especially for high LET radiation exposure. Estimates of risks from low-dose and low-dose-rates are often extrapolated using data from Japanese atomic bomb survivors with either linear or linear quadratic models of fit. In this study, chromosome aberrations were measured in human peripheral blood lymphocytes and normal skin fibroblasts cells after exposure to very low dose (1-20 cGy) of 170 MeV/u Si-28- ions or 600 MeV/u Fe-56-ions. Chromosomes were analyzed using the whole chromosome fluorescence in situ hybridization (FISH) technique during the first cell division after irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving greater than 2 breaks in 2 or more chromosomes). The curves for doses above 10 cGy were fitted with linear or linear-quadratic functions. For Si-28- ions no dose response was observed in the 2-10 cGy dose range, suggesting a non-target effect in this range.

  4. Mechanisms of action for an anti-radiation vaccine in reducing the biological impact of high dose and dose-rate, low-linear energy transfer radiation exposure.

    PubMed

    Maliev, V; Popov, D; Casey, R C; Jones, J A

    2007-01-01

    The development of an anti-radiation vaccine could be very useful in reducing acute radiation syndromes. Existing principles for the treatment of acute radiation syndromes are based on the amelioration of progressive pathophysiological changes, using the concept of replacement therapy. Active immunization by small quantities of the essential radiation-induced systemic toxins of what we call the Specific Radiation Determinant (SRD) before irradiation increased duration of life among animals that were irradiated by lethal or sub-lethal doses of gamma-radiation. The SRD toxins possess antigenic properties that are specific to different forms of acute radiation sickness. Intramuscular injection of larger quantities of the SRD toxins induce signs and symptoms in irradiated naive animals similar to those observed in acute radiation syndromes, including death. Providing passive immunization, at variable periods of time following radiation, with preparations of immune-globulins directed at the SRD molecules, can confer some protection in the development of clinical sequelae in irradiated animals. Improved survival rates and times were observed in animals that received lower, sublethal doses of the same SRDs prior to irradiation. Therefore, active immunization can be induced by SRD molecules as a prophylaxis. The protective effects of the immunization begin to manifest 15-35 days after an injection of a biologically active SDR preparation. The SRD molecules are a group of radiation toxins with antigenic properties that correlate specifically with different forms of radiation disease. The SRD molecules are composed of glycoproteins and lipoproteins that accumulate in the lymphatic system of mammals in the first hours after irradiation, and preliminary analysis suggests that they may originate from cellular membrane components. The molecular weight of the SRD group ranges from 200-250 kDa. The SRD molecules were isolated from the lymphatic systems of laboratory animals that

  5. Measurements of individual radiation doses in residents living around the Fukushima Nuclear Power Plant.

    PubMed

    Nagataki, Shigenobu; Takamura, Noboru; Kamiya, Kenji; Akashi, Makoto

    2013-11-01

    At the outset of the accident at Fukushima Daiichi Nuclear Power Plant in March 2011, the radiation doses experienced by residents were calculated from the readings at monitoring posts, with several assumptions being made from the point of view of protection and safety. However, health effects should also be estimated by obtaining measurements of the individual radiation doses. The individual external radiation doses, determined by a behavior survey in the "evacuation and deliberate evacuation area" in the first 4 months, were <5 mSv in 97.4% of residents (maximum: 15 mSv). Doses in Fukushima Prefecture were <3 mSv in 99.3% of 386,572 residents analyzed. External doses in Fukushima City determined by personal dosimeters were <1 mSv/3 months (September-November, 2011) in 99.7% of residents (maximum: 2.7 mSv). Thyroid radiation doses, determined in March using a NaI (TI) scintillation survey meter in children in the evacuation and deliberate evacuation area, were <10 mSv in 95.7% of children (maximum: 35 mSv). Therefore, all doses were less than the intervention level of 50 mSv proposed by international organizations. Internal radiation doses determined by cesium-134 ((134)C) and cesium-137 ((137)C) whole-body counters (WBCs) were <1 mSv in 99% of the residents, and the maximum thyroid equivalent dose by iodine-131 WBCs was 20 mSv. The exploratory committee of the Fukushima Health Management Survey mentions on its website that radiation from the accident is unlikely to be a cause of adverse health effects in the future. In any event, sincere scientific efforts must continue to obtain individual radiation doses that are as accurate as possible. However, observation of the health effects of the radiation doses described above will require reevaluation of the protocol used for determining adverse health effects. The dose-response relationship is crucial, and the aim of the survey should be to collect sufficient data to confirm the presence or absence of radiation health

  6. Evaluation of radiation dose to anthropomorphic paediatric models from positron-emitting labelled tracers

    NASA Astrophysics Data System (ADS)

    Xie, Tianwu; Zaidi, Habib

    2014-03-01

    PET uses specific molecules labelled with positron-emitting radionuclides to provide valuable biochemical and physiological information. However, the administration of radiotracers to patients exposes them to low-dose ionizing radiation, which is a concern in the paediatric population since children are at a higher cancer risk from radiation exposure than adults. Therefore, radiation dosimety calculations for commonly used positron-emitting radiotracers in the paediatric population are highly desired. We evaluate the absorbed dose and effective dose for 19 positron-emitting labelled radiotracers in anthropomorphic paediatric models including the newborn, 1-, 5-, 10- and 15-year-old male and female. This is achieved using pre-calculated S-values of positron-emitting radionuclides of UF-NCI paediatric phantoms and published biokinetic data for various radiotracers. The influence of the type of anthropomorphic model, tissue weight factors and direct human- versus mouse-derived biokinetic data on the effective dose for paediatric phantoms was also evaluated. In the case of 18F-FDG, dosimetry calculations of reference paediatric patients from various dose regimens were also calculated. Among the considered radiotracers, 18F-FBPA and 15O-water resulted in the highest and lowest effective dose in the paediatric phantoms, respectively. The ICRP 103 updated tissue-weighting factors decrease the effective dose in most cases. Substantial differences of radiation dose were observed between direct human- versus mouse-derived biokinetic data. Moreover, the effect of using voxel- versus MIRD-type models on the calculation of the effective dose was also studied. The generated database of absorbed organ dose and effective dose for various positron-emitting labelled radiotracers using new generation computational models and the new ICRP tissue-weighting factors can be used for the assessment of radiation risks to paediatric patients in clinical practice. This work also contributes

  7. Management of pediatric radiation dose using GE fluoroscopic equipment.

    PubMed

    Belanger, Barry; Boudry, John

    2006-09-01

    In this article, we present GE Healthcare's design philosophy and implementation of X-ray imaging systems with dose management for pediatric patients, as embodied in its current radiography and fluoroscopy and interventional cardiovascular X-ray product offerings. First, we present a basic framework of image quality and dose in the context of a cost-benefit trade-off, with the development of the concept of imaging dose efficiency. A set of key metrics of image quality and dose efficiency is presented, including X-ray source efficiency, detector quantum efficiency (DQE), detector dynamic range, and temporal response, with an explanation of the clinical relevance of each. Second, we present design methods for automatically selecting optimal X-ray technique parameters (kVp, mA, pulse width, and spectral filtration) in real time for various clinical applications. These methods are based on an optimization scheme where patient skin dose is minimized for a target desired image contrast-to-noise ratio. Operator display of skin dose and Dose-Area Product (DAP) is covered, as well. Third, system controls and predefined protocols available to the operator are explained in the context of dose management and the need to meet varying clinical procedure imaging demands. For example, fluoroscopic dose rate is adjustable over a range of 20:1 to adapt to different procedure requirements. Fourth, we discuss the impact of image processing techniques upon dose minimization. In particular, two such techniques, dynamic range compression through adaptive multiband spectral filtering and fluoroscopic noise reduction, are explored in some detail. Fifth, we review a list of system dose-reduction features, including automatic spectral filtration, virtual collimation, variable-rate pulsed fluoroscopic, grid and no-grid techniques, and fluoroscopic loop replay with store. In addition, we describe a new feature that automatically minimizes the patient-to-detector distance, along with an

  8. Radiation Leukemogenesis: Applying Basic Science of Epidemiological Estimates of Low Dose Risks and Dose-Rate Effects

    SciTech Connect

    Hoel, D. G.

    1998-11-01

    The next stage of work has been to examine more closely the A-bomb leukemia data which provides the underpinnings of the risk estimation of CML in the above mentioned manuscript. The paper by Hoel and Li (Health Physics 75:241-50) shows how the linear-quadratic model has basic non-linearities at the low dose region for the leukemias including CML. Pierce et. al., (Radiation Research 123:275-84) have developed distributions for the uncertainty in the estimated exposures of the A-bomb cohort. Kellerer, et. al., (Radiation and Environmental Biophysics 36:73-83) has further considered possible errors in the estimated neutron values and with changing RBE values with dose and has hypothesized that the tumor response due to gamma may not be linear. We have incorporated his neutron model and have constricted new A-bomb doses based on his model adjustments. The Hoel and Li dose response analysis has also been applied using the Kellerer neutron dose adjustments for the leukemias. Finally, both Pierce's dose uncertainties and Kellerer neutron adjustments are combined as well as the varying RBE with dose as suggested by Rossi and Zaider and used for leukemia dose-response analysis. First the results of Hoel and Li showing a significantly improved fit of the linear-quadratic dose response by the inclusion of a threshold (i.e. low-dose nonlinearity) persisted. This work has been complete for both solid tumor as well as leukemia for both mortality as well as incidence data. The results are given in the manuscript described below which has been submitted to Health Physics.

  9. ALLDOS: a computer program for calculation of radiation doses from airborne and waterborne releases

    SciTech Connect

    Strenge, D.L.; Napier, B.A.; Peloquin, R.A.; Zimmerman, M.G.

    1980-10-01

    The computer code ALLDOS is described and instructions for its use are presented. ALLDOS generates tables of radiation doses to the maximum individual and the population in the region of the release site. Acute or chronic release of radionuclides may be considered to airborne and waterborne pathways. The code relies heavily on data files of dose conversion factors and environmental transport factors for generating the radiation doses. A source inventory data library may also be used to generate the release terms for each pathway. Codes available for preparation of the dose conversion factors are described and a complete sample problem is provided describing preparation of data files and execution of ALLDOS.

  10. Radiation Dose-Volume Effects in the Lung

    SciTech Connect

    Marks, Lawrence B.; Bentzen, Soren M. D.Sc.; Deasy, Joseph O.; Kong, F.-M.; Bradley, Jeffrey D.; Vogelius, Ivan S.; El Naqa, Issam; Hubbs, Jessica L. M.S.; Lebesque, Joos V.; Timmerman, Robert D.; Martel, Mary K.; Jackson, Andrew

    2010-03-01

    The three-dimensional dose, volume, and outcome data for lung are reviewed in detail. The rate of symptomatic pneumonitis is related to many dosimetric parameters, and there are no evident threshold 'tolerance dose-volume' levels. There are strong volume and fractionation effects.

  11. Radiation dose aspects in the handling of emerging nuclear fuels.

    PubMed

    Nicolaou, G

    2014-12-01

    The occupational annual dose levels, encountered at fabrication of emerging nuclear fuels, have been studied. Emerging fuels for the single and multiple recycling of Pu and MA have resulted in considerably higher gamma and neutron doses in comparison with commercial fuels. The occupational dose limit is exceeded at fabrication by a single fuel rod in all fuel cases with (241)Am and Cm isotopes present in their composition. In the absence of these isotopes, 2-4 adjacent fuel rods are sufficient to exceed the limit. Self-shielding within the fuel reduces significantly only the gamma dose that would have been delivered otherwise. Hence, only the first row of fuel rods in an assembly contributes to the dose, whereas in the case of neutrons, all fuel rods contribute.

  12. Should supplemental antioxidant administration be avoided during chemotherapy and radiation therapy?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite nearly two decades of research investigating the use of dietary antioxidant supplementation during conventional chemotherapy and radiation therapy, controversy remains about the efficacy and safety of this complementary treatment. Several studies of concurrent antioxidant administration with...

  13. Total ionizing dose radiation effects on NMOS parasitic transistors in advanced bulk CMOS technology devices

    NASA Astrophysics Data System (ADS)

    Baoping, He; Zujun, Wang; Jiangkun, Sheng; Shaoyan, Huang

    2016-12-01

    In this paper, total ionizing dose effect of NMOS transistors in advanced CMOS technology are examined. The radiation tests are performed at 60Co sources at the dose rate of 50 rad (Si)/s. The investigation's results show that the radiation-induced charge buildup in the gate oxide can be ignored, and the field oxide isolation structure is the main total dose problem. The total ionizing dose (TID) radiation effects of field oxide parasitic transistors are studied in detail. An analytical model of radiation defect charge induced by TID damage in field oxide is established. The I - V characteristics of the NMOS parasitic transistors at different doses are modeled by using a surface potential method. The modeling method is verified by the experimental I - V characteristics of 180 nm commercial NMOS device induced by TID radiation at different doses. The model results are in good agreement with the radiation experimental results, which shows the analytical model can accurately predict the radiation response characteristics of advanced bulk CMOS technology device. Project supported by the National Natural Science Foundation of China (No. 11305126).

  14. Radiation dose due to radon and thoron progeny inhalation in high-level natural radiation areas of Kerala, India.

    PubMed

    Omori, Yasutaka; Tokonami, Shinji; Sahoo, Sarata Kumar; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Hosoda, Masahiro; Kudo, Hiromi; Pornnumpa, Chanis; Nair, Raghu Ram K; Jayalekshmi, Padmavaty Amma; Sebastian, Paul; Akiba, Suminori

    2017-03-20

    In order to evaluate internal exposure to radon and thoron, concentrations for radon, thoron, and thoron progeny were measured for 259 dwellings located in high background radiation areas (HBRAs, outdoor external dose: 3-5 mGy y(-1)) and low background radiation areas (control areas, outdoor external dose: 1 mGy y(-1)) in Karunagappally Taluk, Kerala, India. The measurements were conducted using passive-type radon-thoron detectors and thoron progeny detectors over two six-month measurement periods from June 2010 to June 2011. The results showed no major differences in radon and thoron progeny concentrations between the HBRAs and the control areas. The geometric mean of the annual effective dose due to radon and thoron was calculated as 0.10 and 0.44 mSv, respectively. The doses were small, but not negligible compared with the external dose in the two areas.

  15. Methodology for Estimating Radiation Dose Rates to Freshwater Biota Exposed to Radionuclides in the Environment

    SciTech Connect

    Blaylock, B.G.

    1993-01-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be

  16. Implications for human and environmental health of low doses of ionising radiation.

    PubMed

    Mothersill, Carmel; Seymour, Colin

    2014-07-01

    The last 20 years have seen a major paradigm shift in radiation biology. Several discoveries challenge the DNA centric view which holds that DNA damage is the critical effect of radiation irrespective of dose. This theory leads to the assumption that dose and effect are simply linked - the more energy deposition, the more DNA damage and the greater the biological effect. This is embodied in radiation protection (RP) regulations as the linear-non-threshold (LNT) model. However the science underlying the LNT model is being challenged particularly in relation to the environment because it is now clear that at low doses of concern in RP, cells, tissues and organisms respond to radiation by inducing responses which are not readily predictable by dose. These include adaptive responses, bystander effects, genomic instability and low dose hypersensitivity, and are commonly described as stress responses, while recognizing that "stress" can be good as well as bad. The phenomena contribute to observed radiation responses and appear to be influenced by genetic, epigenetic and environmental factors, meaning that dose and response are not simply related. The question is whether our discovery of these phenomena means that we need to re-evaluate RP approaches. The so-called "non-targeted" mechanisms mean that low dose radiobiology is very complex and supra linear or sub-linear (even hormetic) responses are possible but their occurrence is unpredictable for any given system level. Issues which may need consideration are synergistic or antagonistic effects of other pollutants. RP, at present, only looks at radiation dose but the new (NTE) radiobiology means that chemical or physical agents, which interfere with tissue responses to low doses of radiation, could critically modulate the predicted risk. Similarly, the "health" of the organism could determine the effect of a given low dose by enabling or disabling a critical response. These issues will be discussed.

  17. Radiation doses to paediatric patients and comforters undergoing chest X rays.

    PubMed

    Sulieman, A; Vlychou, M; Tsougos, I; Theodorou, K

    2011-09-01

    Pneumonia is an important cause of hospital admission among children in the developed world and it is estimated to be responsible for 3-18 % of all paediatric admissions. Chest X ray is an important examination for pneumonia diagnosis and for evaluation of complications. This study aims to determine the entrance surface dose (ESD), organ, effective doses and propose a local diagnostic reference level. The study was carried out at the university hospital of Larissa, Greece. Patients were divided into three groups: organ and effective doses were estimated using National Radiological Protection Board software. The ESD was determined by thermoluminescent dosemeters for 132 children and 76 comforters. The average ESD value was 55 ± 8 µGy. The effective dose for patients was 11.2 ± 5 µSv. The mean radiation dose for comforter is 22 ± 3 µGy. The radiation dose to the patients is well within dose constraint, in the light of the current practice.

  18. Estimation of organ dose equivalents from residents of radiation-contaminated buildings with Rando phantom measurements.

    PubMed

    Lee, J S; Dong, S L; Wu, T H

    1999-05-01

    Since August 1996, a dose reconstruction model has been conducted with thermoluminescent dosimeter (TLD)-embedded chains, belts and badges for external dose measurements on the residents in radiation-contaminated buildings. The TLD dosimeters, worn on the front of the torso, would not be adequate for dose measurement in cases when the radiation is anisotropic or the incident angles of radiation sources are not directed in the front-to-back direction. The shielding and attenuation by the body would result in the dose equivalent estimation being somewhat skewed. An organ dose estimation method with a Rando phantom under various exposure geometries is proposed. The conversion factors, obtained from the phantom study, may be applicable to organ dose estimations for residents in the contaminated buildings if the incident angles correspond to the phantom simulation results. There is a great demand for developing a mathematical model or Monte Carlo calculation to deal with complicated indoor layout geometry problems involving ionizing radiation. Further research should be directed toward conducting laboratory simulation by investigating the relationship between doses delivered from multiple radiation sources. It is also necessary to collaborate with experimental biological dosimetry, such as chromosome aberration analysis, fluorescence in situ hybridization (FISH) and retrospective ESR-dosimetry with teeth, applied to the residents, so that the organ dose equivalent estimations may be more reliable for radio-epidemiological studies.

  19. A Survey of Pediatric CT Protocols and Radiation Doses in South Korean Hospitals to Optimize the Radiation Dose for Pediatric CT Scanning.

    PubMed

    Hwang, Jae-Yeon; Do, Kyung-Hyun; Yang, Dong Hyun; Cho, Young Ah; Yoon, Hye-Kyung; Lee, Jin Seong; Koo, Hyun Jung

    2015-12-01

    Children are at greater risk of radiation exposure than adults because the rapidly dividing cells of children tend to be more radiosensitive and they have a longer expected life time in which to develop potential radiation injury. Some studies have surveyed computed tomography (CT) radiation doses and several studies have established diagnostic reference levels according to patient age or body size; however, no survey of CT radiation doses with a large number of patients has yet been carried out in South Korea. The aim of the present study was to investigate the radiation dose in pediatric CT examinations performed throughout South Korea. From 512 CT (222 brain CT, 105 chest CT, and 185 abdominopelvic CT) scans that were referred to our tertiary hospital, a dose report sheet was available for retrospective analysis of CT scan protocols and dose, including the volumetric CT dose index (CTDIvol), dose-length product (DLP), effective dose, and size-specific dose estimates (SSDE). At 55.2%, multiphase CT was the most frequently performed protocol for abdominopelvic CT. Tube current modulation was applied most often in abdominopelvic CT and chest CT, accounting for 70.1% and 62.7%, respectively. Regarding the CT dose, the interquartile ranges of the CTDIvol were 11.1 to 22.5 (newborns), 16.6 to 39.1 (≤1 year), 14.6 to 41.7 (2-5 years), 23.5 to 44.1 (6-10 years), and 31.4 to 55.3 (≤15 years) for brain CT; 1.3 to 5.7 (≤1 year), 3.9 to 6.8 (2-5 years), 3.9 to 9.3 (6-10 years), and 7.7 to 13.8 (≤15 years) for chest CT; and 4.0 to 7.5 (≤1 year), 4.2 to 8.9 (2-5 years), 5.7 to 12.4 (6-10 years), and 7.6 to 16.6 (≤15 years) for abdominopelvic CT. The SSDE and CTDIvol were well correlated for patients <5 years old, whereas the CTDIvol was lower in patients ≥6 years old. Our study describes the various parameters and dosimetry metrics of pediatric CT in South Korea. The CTDIvol, DLP, and effective dose were generally lower than in German and UK surveys, except in

  20. Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats

    PubMed Central

    Kumar, Raju Suresh; Potu, Bhagath Kumar; Nayak, Satheesha; Bhat, P. Gopalakrishna; Mailankot, Maneesh

    2010-01-01

    Introduction The interaction of mobile phone radio-frequency electromagnetic radiation (RF-EMR) with the brain is a serious concern of our society. Objective We evaluated the effect of RF-EMR from mobile phones on passive avoidance behaviour and hippocampal morphology in rats. Materials and methods Healthy male albino Wistar rats were exposed to RF-EMR by giving 50 missed calls (within 1 hour) per day for 4 weeks, keeping a GSM (0.9 GHz/1.8 GHz) mobile phone in vibratory mode (no ring tone) in the cage. After the experimental period, passive avoidance behaviour and hippocampal morphology were studied. Results Passive avoidance behaviour was significantly affected in mobile phone RF-EMR-exposed rats demonstrated as shorter entrance latency to the dark compartment when compared to the control rats. Marked morphological changes were also observed in the CA3 region of the hippocampus of the mobile phone-exposed rats in comparison to the control rats. Conclusion Mobile phone RF-EMR exposure significantly altered the passive avoidance behaviour and hippocampal morphology in rats. PMID:20095879

  1. COMPARISON OF THE PERIPHERAL DOSES FROM DIFFERENT IMRT TECHNIQUES FOR PEDIATRIC HEAD AND NECK RADIATION THERAPY.

    PubMed

    Toyota, Masahiko; Saigo, Yasumasa; Higuchi, Kenta; Fujimura, Takuya; Koriyama, Chihaya; Yoshiura, Takashi; Akiba, Suminori

    2017-02-25

    Intensity-modulated radiation therapy (IMRT) can deliver high and homogeneous doses to the target area while limiting doses to organs at risk. We used a pediatric phantom to simulate the treatment of a head and neck tumor in a child. The peripheral doses were examined for three different IMRT techniques [dynamic multileaf collimator (DMLC), segmental multileaf collimator (SMLC) and volumetric modulated arc therapy (VMAT)]. Peripheral doses were evaluated taking thyroid, breast, ovary and testis as the points of interest. Doses were determined using a radio-photoluminescence glass dosemeter, and the COMPASS system was used for three-dimensional dose evaluation. VMAT achieved the lowest peripheral doses because it had the highest monitor unit efficiency. However, doses in the vicinity of the irradiated field, i.e. the thyroid, could be relatively high, depending on the VMAT collimator angle. DMLC and SMLC had a large area of relatively high peripheral doses in the breast region.

  2. Dose-effect relation of interstitial low-dose-rate radiation (Ir192) in an animal tumor model.

    PubMed

    Ruifrok, A C; Levendag, P C; Lakeman, R F; Deurloo, I K; Visser, A G

    1990-01-01

    One way to deliver high doses of radiation to deep seated tumors without damaging the surrounding tissue is by interstitial techniques. This is commonly applied clinically; however, biological data of tumor response to interstitial low-dose-rate gamma irradiation are scarce. Therefore, we have studied the response of rhabdomyosarcoma R1 tumors implanted in the flanks of female Wag/Rij rats using an interstitial Ir192 afterloading system. A template was developed by which four catheters can be implanted in a square geometry with a fixed spacing. Subsequently four Ir192 wires of 2 cm length each are inserted. For dose prescription the highest isodose enveloping the tumor volume was chosen. Interstitial irradiation was performed using tumor volumes of 1500-2000 mm3. A range of minimum tumor doses of 20 up to 115 Gy were given at a mean dose-rate of 48 cGy/hr. Dose-effect relations were obtained from tumor growth curves and tumor cure data, and compared to data from external irradiation. The dose required for 50% cures with interstitial irradiation (TCD50) appears to be 95 +/- 9 Gy. The TCD50 for low-dose-rate interstitial gamma irradiation is 1.5 times the TCD50 for single dose external X ray irradiation at high dose rates, but is comparable to the TCD50 found after fractionated X ray irradiation at high dose rate. Sham treatment of the tumors had no effect on the time needed to reach twice the treatment volume. The growth rate of tumors regrowing after interstitial radiotherapy is not markedly different from the growth rate of untreated (control) tumors (volume doubting time 5.6 +/- 1 day), in contrast to the decreased growth rate after external X ray irradiation. It is argued that the absence of a clear tumor bed effect may be explained by some sparing of the stroma by the low-dose-rate of the interstitial irradiation per se as well as by the physical dose distribution of the interstitial Ir192 sources, giving a relative low dose of radiation to the surrounding

  3. Consideration of the radiation dose delivered away from the treatment field to patients in radiotherapy

    PubMed Central

    Taylor, Michael L.; Kron, Tomas

    2011-01-01

    Radiation delivery to cancer patients for radiotherapy is invariably accompanied by unwanted radiation to other parts of the patient’s body. Traditionally, considerable effort has been made to calculate and measure the radiation dose to the target as well as to nearby critical structures. Only recently has attention been focused also on the relatively low doses that exist far from the primary radiation beams. In several clinical scenarios, such doses have been associated with cardiac toxicity as well as an increased risk of secondary cancer induction. Out-of-field dose is a result of leakage and scatter and generally difficult to predict accurately. The present review aims to present existing data, from measurements and calculations, and discuss its implications for radiotherapy. PMID:21731221

  4. Pre-treatment of Stegomyia aegypti mosquitoes with a sublethal dose of imidacloprid impairs behavioural avoidance induced by lemon oil and DEET.

    PubMed

    Thany, S H; Tong, F; Bloomquist, J R

    2015-03-01

    The present study was conducted to determine whether imidacloprid can impair the avoidance behaviour of the mosquito Stegomyia aegypti. Laboratory investigations using a T-maze apparatus showed that St. aegypti mosquitoes present long term avoidance behaviour when they are exposed to repetitive trials with lemon oil and DEET. The present study tested the effect of a sublethal dose of imidacloprid on the avoidance behaviour of St. aegypti mosquitoes over a 48 h period. Data suggest that 0.5 ng of imidacloprid/mosquito reduces the avoidance behaviour of mosquitoes exposed to lemon oil, on the first day of exposure, after the second trial; whereas imidacloprid affected DEET repellency only the first day of exposure, after the second trial. Imidacloprid was toxic against St. aegypti mosquitoes, and at sublethal doses was able to impair the repellency induced by lemon oil and DEET. The present data were consistent with the finding that St. aegypti mosquitoes exhibit long term avoidance behaviour, and treatment of mosquitoes with a sublethal dose of imidacloprid under DEET application can affect the repellency of DEET against St. aegypti.

  5. Implications of Intercellular Signaling for Radiation Therapy: A Theoretical Dose-Planning Study

    SciTech Connect

    McMahon, Stephen J.; McGarry, Conor K.; Butterworth, Karl T.; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2013-12-01

    Purpose: Recent in vitro results have shown significant contributions to cell killing from signaling effects at doses that are typically used in radiation therapy. This study investigates whether these in vitro observations can be reconciled with in vivo knowledge and how signaling may have an impact on future developments in radiation therapy. Methods and Materials: Prostate cancer treatment plans were generated for a series of 10 patients using 3-dimensional conformal therapy, intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy techniques. These plans were evaluated using mathematical models of survival following modulated radiation exposures that were developed from in vitro observations and incorporate the effects of intercellular signaling. The impact on dose–volume histograms and mean doses were evaluated by converting these survival levels into “signaling-adjusted doses” for comparison. Results: Inclusion of intercellular communication leads to significant differences between the signalling-adjusted and physical doses across a large volume. Organs in low-dose regions near target volumes see the largest increases, with mean signaling-adjusted bladder doses increasing from 23 to 33 Gy in IMRT plans. By contrast, in high-dose regions, there is a small decrease in signaling-adjusted dose due to reduced contributions from neighboring cells, with planning target volume mean doses falling from 74 to 71 Gy in IMRT. Overall, however, the dose distributions remain broadly similar, and comparisons between the treatment modalities are largely unchanged whether physical or signaling-adjusted dose is compared. Conclusions: Although incorporating cellular signaling significantly affects cell killing in low-dose regions and suggests a different interpretation for many phenomena, their effect in high-dose regions for typical planning techniques is comparatively small. This indicates that the significant signaling effects observed in vitro

  6. Radiation dose dependent change in physiochemical, mechanical and barrier properties of guar gum based films.

    PubMed

    Saurabh, Chaturbhuj K; Gupta, Sumit; Bahadur, Jitendra; Mazumder, S; Variyar, Prasad S; Sharma, Arun

    2013-11-06

    Mechanical and water vapor barrier properties of biodegradable films prepared from radiation processed guar gum were investigated. Films prepared from GG irradiated up to 500 Gy demonstrated significantly higher tensile strength as compared to non-irradiated control films. This improvement in tensile strength observed was demonstrated to be due to the ordering of polymer structures as confirmed by small angle X-ray scattering analysis. Exposure to doses higher than 500 Gy, however, resulted in a dose dependent decrease in tensile strength. A dose dependent decrease in puncture strength with no significant differences in the percent elongation was also observed at all the doses studied. Water vapor barrier properties of films improved up to 15% due to radiation processing. Radiation processing at lower doses for improving mechanical and barrier properties of guar based packaging films is demonstrated here for the first time.

  7. Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation

    NASA Technical Reports Server (NTRS)

    Sutherland, Betsy M.; Bennett, Paula V.; Cintron-Torres, Nela; Hada, Megumi; Trunk, John; Monteleone, Denise; Sutherland, John C.; Laval, Jacques; Stanislaus, Marisha; Gewirtz, Alan

    2002-01-01

    Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.

  8. SU-C-BRA-07: Virtual Bronchoscopy-Guided IMRT Planning for Mapping and Avoiding Radiation Injury to the Airway Tree in Lung SAbR

    SciTech Connect

    Sawant, A; Modiri, A; Bland, R; Yan, Y; Ahn, C; Timmerman, R

    2015-06-15

    Purpose: Post-treatment radiation injury to central and peripheral airways is a potentially important, yet under-investigated determinant of toxicity in lung stereotactic ablative radiotherapy (SAbR). We integrate virtual bronchoscopy technology into the radiotherapy planning process to spatially map and quantify the radiosensitivity of bronchial segments, and propose novel IMRT planning that limits airway dose through non-isotropic intermediate- and low-dose spillage. Methods: Pre- and ∼8.5 months post-SAbR diagnostic-quality CT scans were retrospectively collected from six NSCLC patients (50–60Gy in 3–5 fractions). From each scan, ∼5 branching levels of the bronchial tree were segmented using LungPoint, a virtual bronchoscopic navigation system. The pre-SAbR CT and the segmented bronchial tree were imported into the Eclipse treatment planning system and deformably registered to the planning CT. The five-fraction equivalent dose from the clinically-delivered plan was calculated for each segment using the Universal Survival Curve model. The pre- and post-SAbR CTs were used to evaluate radiation-induced segmental collapse. Two of six patients exhibited significant segmental collapse with associated atelectasis and fibrosis, and were re-planned using IMRT. Results: Multivariate stepwise logistic regression over six patients (81 segments) showed that D0.01cc (minimum point dose within the 0.01cc receiving highest dose) was a significant independent factor associated with collapse (odds-ratio=1.17, p=0.010). The D0.01cc threshold for collapse was 57Gy, above which, collapse rate was 45%. In the two patients exhibiting segmental collapse, 22 out of 32 segments showed D0.01cc >57Gy. IMRT re-planning reduced D0.01cc below 57Gy in 15 of the 22 segments (68%) while simultaneously achieving the original clinical plan objectives for PTV coverage and OAR-sparing. Conclusion: Our results indicate that the administration of lung SAbR can Result in significant injury to

  9. Radiation Dose-Volume Effects in the Spinal Cord

    SciTech Connect

    Kirkpatrick, John P.; Kogel, Albert J. van der; Schultheiss, Timothy E.

    2010-03-01

    Dose-volume data for myelopathy in humans treated with radiotherapy (RT) to the spine is reviewed, along with pertinent preclinical data. Using conventional fractionation of 1.8-2 Gy/fraction to the full-thickness cord, the estimated risk of myelopathy is <1% and <10% at 54 Gy and 61 Gy, respectively, with a calculated strong dependence on dose/fraction (alpha/beta = 0.87 Gy.) Reirradiation data in animals and humans suggest partial repair of RT-induced subclinical damage becoming evident about 6 months post-RT and increasing over the next 2 years. Reports of myelopathy from stereotactic radiosurgery to spinal lesions appear rare (<1%) when the maximum spinal cord dose is limited to the equivalent of 13 Gy in a single fraction or 20 Gy in three fractions. However, long-term data are insufficient to calculate a dose-volume relationship for myelopathy when the partial cord is treated with a hypofractionated regimen.

  10. Comprehensive assessment of radiation dose estimates for the CORE320 study.

    PubMed

    Rybicki, Frank J; Mather, Richard T; Kumamaru, Kanako K; Brinker, Jeffrey; Chen, Marcus Y; Cox, Christopher; Matheson, Matthew B; Dewey, Marc; DiCarli, Marcelo F; Miller, Julie M; Geleijns, Jacob; George, Richard T; Paul, Narinder; Texter, John; Vavere, Andrea; Yaw, Tan Swee; Lima, Joao A C; Clouse, Melvin E

    2015-01-01

    OBJECTIVE. The purpose of this study was to comprehensively study estimated radiation doses for subjects included in the main analysis of the Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography (CORE320) study ( ClinicalTrials.gov identifier NCT00934037), a clinical trial comparing combined CT angiography (CTA) and perfusion CT with the reference standard catheter angiography plus myocardial perfusion SPECT. SUBJECTS AND METHODS. Prospectively acquired data on 381 CORE320 subjects were analyzed in four groups of testing related to radiation exposure. Radiation dose estimates were compared between modalities for combined CTA and perfusion CT with respect to covariates known to influence radiation exposure and for the main clinical outcomes defined by the trial. The final analysis assessed variations in radiation dose with respect to several factors inherent to the trial. RESULTS. The mean radiation dose estimate for the combined CTA and perfusion CT protocol (8.63 mSv) was significantly (p < 0.0001 for both) less than the average dose delivered from SPECT (10.48 mSv) and the average dose from diagnostic catheter angiography (11.63 mSv). There was no significant difference in estimated CTA-perfusion CT radiation dose for subjects who had false-positive or false-negative results in the CORE320 main analyses in a comparison with subjects for whom the CTA-perfusion CT findings were in accordance with the reference standard SPECT plus catheter angiographic findings. CONCLUSION. Radiation dose estimates from CORE320 support clinical implementation of a combined CT protocol for assessing coronary anatomy and myocardial perfusion.

  11. High-dose fractionated radiation therapy for select patients with brain metastases

    SciTech Connect

    Pezner, R.D.; Lipsett, J.A.; Archambeau, J.O.; Fine, R.M.; Moss, W.T.

    1981-08-01

    Four patients with metastases to the brain were treated by high-dose fractionated radiation therapy. In all four cases, a complete response and prolonged disease-free survival could be documented. Unlike the standard therapy for such patients (i.e., craniotomy and postoperative irradiation), high-dose fractionated radiation therapy carries no operative risk and can encompass multiple brain metastases and metastases in deep or critical intracranial sites. The risk of radiotherapy side effects in the brain is discussed.

  12. Biochemical Changes in Blood Components after Lethal Doses of Radiation.

    DTIC Science & Technology

    1982-10-01

    from the knowledge that ionizing radiation An induce lipid peroxidation (27); this then can affect membrane phospholipase A2 activity (28). Changes in... phospholipase A2 activity could result in changes in arachidonic acid production and the generation of lipoxygenase and cyclooxy- genase products (29...postirradiation. If ionizing radiation does alter phospholipase A2 activity, this would be interesting because the arachidonic acid cascade is a very

  13. Critical target and dose and dose-rate responses for the induction of chromosomal instability by ionizing radiation

    NASA Technical Reports Server (NTRS)

    Limoli, C. L.; Corcoran, J. J.; Milligan, J. R.; Ward, J. F.; Morgan, W. F.

    1999-01-01

    To investigate the critical target, dose response and dose-rate response for the induction of chromosomal instability by ionizing radiation, bromodeoxyuridine (BrdU)-substituted and unsubstituted GM10115 cells were exposed to a range of doses (0.1-10 Gy) and different dose rates (0.092-17.45 Gy min(-1)). The status of chromosomal stability was determined by fluorescence in situ hybridization approximately 20 generations after irradiation in clonal populations derived from single progenitor cells surviving acute exposure. Overall, nearly 700 individual clones representing over 140,000 metaphases were analyzed. In cells unsubstituted with BrdU, a dose response was found, where the probability of observing delayed chromosomal instability in any given clone was 3% per gray of X rays. For cells substituted with 25-66% BrdU, however, a dose response was observed only at low doses (<1.0 Gy); at higher doses (>1.0 Gy), the incidence of chromosomal instability leveled off. There was an increase in the frequency and complexity of chromosomal instability per unit dose compared to cells unsubstituted with BrdU. The frequency of chromosomal instability appeared to saturate around approximately 30%, an effect which occurred at much lower doses in the presence of BrdU. Changing the gamma-ray dose rate by a factor of 190 (0.092 to 17.45 Gy min(-1)) produced no significant differences in the frequency of chromosomal instability. The enhancement of chromosomal instability promoted by the presence of the BrdU argues that DNA comprises at least one of the critical targets important for the induction of this end point of genomic instability.

  14. Dose-effect relation of interstitial low-dose-rate radiation (Ir192) in an animal tumor model

    SciTech Connect

    Ruifrok, A.C.; Levendag, P.C.; Lakeman, R.F.; Deurloo, I.K.; Visser, A.G. )

    1990-01-01

    One way to deliver high doses of radiation to deep seated tumors without damaging the surrounding tissue is by interstitial techniques. This is commonly applied clinically; however, biological data of tumor response to interstitial low-dose-rate gamma irradiation are scarce. Therefore, we have studied the response of rhabdomyosarcoma R1 tumors implanted in the flanks of female Wag/Rij rats using an interstitial Ir192 afterloading system. A template was developed by which four catheters can be implanted in a square geometry with a fixed spacing. Subsequently four Ir192 wires of 2 cm length each are inserted. For dose prescription the highest isodose enveloping the tumor volume was chosen. Interstitial irradiation was performed using tumor volumes of 1500-2000 mm3. A range of minimum tumor doses of 20 up to 115 Gy were given at a mean dose-rate of 48 cGy/hr. Dose-effect relations were obtained from tumor growth curves and tumor cure data, and compared to data from external irradiation. The dose required for 50% cures with interstitial irradiation (TCD50) appears to be 95 +/- 9 Gy. The TCD50 for low-dose-rate interstitial gamma irradiation is 1.5 times the TCD50 for single dose external X ray irradiation at high dose rates, but is comparable to the TCD50 found after fractionated X ray irradiation at high dose rate. Sham treatment of the tumors had no effect on the time needed to reach twice the treatment volume. The growth rate of tumors regrowing after interstitial radiotherapy is not markedly different from the growth rate of untreated (control) tumors (volume doubting time 5.6 +/- 1 day), in contrast to the decreased growth rate after external X ray irradiation.

  15. Micro RNA responses to chronic or acute exposures to low dose ionizing radiation

    PubMed Central

    Chaudhry, M. Ahmad; Omaruddin, Romaica A.; Kreger, Bridget; de Toledo, Sonia M.; Azzam, Edouard I.

    2014-01-01

    Human health risks of exposure to low dose ionizing radiation remain ambiguous and are the subject of intense debate. A wide variety of biological effects are induced after cellular exposure to ionizing radiation, but the underlying molecular mechanism(s) remain to be completely understood. We hypothesized that low dose c-radiation-induced effects are controlled by the modulation of micro RNA (miRNA) that participate in the control of gene expression at the posttranscriptional level and are involved in many cellular processes. We monitored the expression of several miRNA in human cells exposed to acute or chronic low doses of 10 cGy or a moderate dose of 400 cGy of 137Cs γ-rays. Dose, dose rate and time dependent differences in the relative expression of several miRNA were investigated. The expression patterns of many miRNA differed after exposure to either chronic or acute 10 cGy. The expression of miRNA let-7e, a negative regulator of RAS oncogene, and the c-MYC miRNA cluster were upregulated after 10 cGy chronic dose but were downregulated after 3 h of acute 10 cGy. The miR-21 was upregulated in chronic or acute low dose and moderate dose treated cells and its target genes hPDCD4, hPTEN, hSPRY2, and hTPM1 were found to be downregulated. These findings provide evidence that low dose and dose rate c-irradiation dictate the modulation of miRNA, which can result in a differential cellular response than occurs at high doses. This information will contribute to understanding the risks to human health after exposure to low dose radiation. PMID:22367372

  16. Radiation Resistance Study of Semi-Insulating GaAs-Based Radiation Detectors to Extremely High Gamma Doses

    NASA Astrophysics Data System (ADS)

    Ly Anh, T.; Perd'ochová, A.; Nečas, V.; Pavlicová, V.

    2006-01-01

    In our previous paper [V. Nečas et al.: Nucl. Inst. and Meth. A 458 (2001) 348-351] we reported on the study on radiation stability of semi-insulating (SI) LEG GaAs detectors to doses of photons from 60Co up to 19.2 kGy. Later we presented a study, which covered radiation hardness to the same doses on the base of detector material itself, where strong dependence has been proved [T. Ly Anh et al., Proceedings of the XII th International Conference on Semiconducting and Insulating Materials (SIMC-XII-2002). Smolenice Castle, Slovakia (2002) 292-295 (0-7803-7418-5)]. In this paper we present both the key electrical and detection characteristics of SI GaAs radiation detectors prepared using substrates from four various supplies and two different types of contacts, which were exposed to several gamma doses from 60Co up to the integral dose of about 1 MGy. The obtained results show that SI LEG GaAs detectors provide good spectroscopic performances and even their slight improvement after low to middle gamma irradiation doses (3 -10 kGy) was observed. Further dose exposure caused the degradation of detection properties with an extreme and following improvement depending on detector material properties. SI GaAs detector still retains its working capabilities even after very high doses applied, up to 1 MGy.

  17. WE-A-18A-01: TG246 On Patient Dose From Diagnostic Radiation

    SciTech Connect

    Supanich, M; Dong, F; Andersson, J; Pavlicek, W; Bolch, W; Fetterly, K

    2014-06-15

    Radiation dose from diagnostic and interventional radiations continues to be a focus of the regulatory, accreditation and standards organizations in the US and Europe. A Joint AAPM/EFOMP effort has been underway in the past year — having the goal to assist the clinical medical physicist with communicating optional and varied approaches in estimating (and validating) patient dose. In particular, the tools provided by DICOM Radiation Dose Structured Reports, either by themselves or as part of a networked data repository of dose related information are a rich source of actionable information. The tools of the medical physicist have evolved to include using DICOM data in meaningful ways to look at patient dose with respect to imaging practices. In addition to how accurate or reproducible a dose value is (totally necessary and our traditional workspace) it is now being asked how reproducible (patient to patient, device to device) are the delivered doses (new tasking)? Clinical medical physicists are best equipped to assist our radiology and technologist colleagues with this effort. The purpose of this session is to review the efforts of TG246 - bringing forward a summary content of the TG246 Report including specific dose descriptors for CT and Fluoroscopy — particularly in a focus of leveraging the RDSR as a means for monitoring good practices ALARA. Additionally, rapidly evolving technologies for more refined dose estimates are now in use. These will be presented as they look to having highly patient specific dose estimates in automated use.

  18. Clinical usefulness of the management and delivery of radiation dose-distribution images using the Internet.

    PubMed

    Nakagawa, K; Onogi, Y; Aoki, Y; Kozuka, T; Ohtomo, K

    1998-01-01

    Dose distribution images in radiation therapy play important roles in the management of cancer patients. To date, hard copies of these images have been stored for referral by radiation oncologists as needed. In most cases, these images are not available to medical personnel outside the radiation oncology department. We have developed a means to access these dose distribution images from the hospital via the World-Wide Web (WWW). A screen snapshot of a dose distribution image on the CRT of a treatment planning unit is copied to the WWW server and converted to a GIF (graphic interchange format) image. Similarly, we can register dose volume histograms and digitally reconstructed radiographs (DRR) on the WWW. Medical personnel can view these images through the WWW browser from anywhere in the hospital. As a result, radiation oncologists are given detailed information on target definition in treatment planning by expert physicians. The system also helps co-medical personnel in understanding dose distribution and predicting radiation injury. At the same time, it actualizes an electronic archive of dose distribution images, which is a database for quick and reliable review, evaluation, and comparison of treatment plans. This technique also fosters closer relationships among radiation oncologists, physicians, and co-medical personnel.

  19. Time- and dose-dependent effects of total-body ionizing radiation on muscle stem cells

    PubMed Central

    Masuda, Shinya; Hisamatsu, Tsubasa; Seko, Daiki; Urata, Yoshishige; Goto, Shinji; Li, Tao-Sheng; Ono, Yusuke

    2015-01-01

    Exposure to high levels of genotoxic stress, such as high-dose ionizing radiation, increases both cancer and noncancer risks. However, it remains debatable whether low-dose ionizing radiation reduces cellular function, or rather induces hormetic health benefits. Here, we investigated the effects of total-body γ-ray radiation on muscle stem cells, called satellite cells. Adult C57BL/6 mice were exposed to γ-radiation at low- to high-dose rates (low, 2 or 10 mGy/day; moderate, 50 mGy/day; high, 250 mGy/day) for 30 days. No hormetic responses in proliferation, differentiation, or self-renewal of satellite cells were observed in low-dose radiation-exposed mice at the acute phase. However, at the chronic phase, population expansion of satellite cell-derived progeny was slightly decreased in mice exposed to low-dose radiation. Taken together, low-dose ionizing irradiation may suppress satellite cell function, rather than induce hormetic health benefits, in skeletal muscle in adult mice. PMID:25869487

  20. The annual effective dose from natural sources of ionising radiation in Canada.

    PubMed

    Grasty, R L; LaMarre, J R

    2004-01-01

    A review and analysis of published information combined with the results of recent gamma ray surveys were used to determine the annual effective dose to Canadians from natural sources of radiation. The dose due to external radiation was determined from ground gamma ray surveys carried out in the cities of Toronto, Ottawa, Montreal and Winnipeg and was calculated to be 219 microSv. A compilation of airborne gamma ray data from Canada and the United States shows that there are large variations in external radiation with the highest annual outdoor level of 1424 microSv being found in northern Canada. The annual effective inhalation dose of 926 microSv from 222Rn and 220Rn was calculated from approximately 14,000 measurements across Canada. This value includes a contribution of 128 microSv from 222Rn in the outdoor air together with 6 microSv from long-lived uranium and thorium series radionuclides in dust particles. Based on published information, the annual effective dose due to internal radioactivity is 306 microSv. A program developed by the Federal Aviation Administration was used to calculate a population-weighted annual effective dose from cosmic radiation of 318 microSv. The total population-weighted average annual effective dose to Canadians from all sources of natural background radiation was calculated to be 1769 microSv but varies significantly from city to city, largely due to differences in the inhalation dose from 222Rn.

  1. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors.

    PubMed

    Sasaki, Masao S; Tachibana, Akira; Takeda, Shunichi

    2014-05-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking.

  2. Cosmic radiation dose in aircraft--a neutron track etch detector.

    PubMed

    Vuković, B; Radolić, V; Miklavcić, I; Poje, M; Varga, M; Planinić, J

    2007-01-01

    Cosmic radiation bombards us at high altitude by ionizing particles. The radiation environment is a complex mixture of charged particles of solar and galactic origin, as well as of secondary particles produced in interaction of the galactic cosmic particles with the nuclei of atmosphere of the Earth. The radiation field at aircraft altitude consists of different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. The non-neutron component of cosmic radiation dose aboard ATR 42 and A 320 aircrafts (flight level of 8 and 11 km, respectively) was measured with TLD-100 (LiF:Mg,Ti) detectors and the Mini 6100 semiconductor dosimeter. The estimated occupational effective dose for the aircraft crew (A 320) working 500 h per year was 1.64 mSv. Other experiments, or dose rate measurements with the neutron dosimeter, consisting of LR-115 track detector and boron foil BN-1 or 10B converter, were performed on five intercontinental flights. Comparison of the dose rates of the non-neutron component (low LET) and the neutron one (high LET) of the radiation field at the aircraft flight level showed that the neutron component carried about 50% of the total dose. The dose rate measurements on the flights from the Middle Europe to the South and Middle America, then to Korea and Japan, showed that the flights over or near the equator region carried less dose rate; this was in accordance with the known geomagnetic latitude effect.

  3. Cardiovascular diseases related to ionizing radiation: The risk of low-dose exposure (Review)

    PubMed Central

    Baselet, Bjorn; Rombouts, Charlotte; Benotmane, Abderrafi Mohammed; Baatout, Sarah; Aerts, An

    2016-01-01

    Traditionally, non-cancer diseases are not considered as health risks following exposure to low doses of ionizing radiation. Indeed, non-cancer diseases are classified as deterministic tissue reactions, which are characterized by a threshold dose. It is judged that below an absorbed dose of 100 mGy, no clinically relevant tissue damage occurs, forming the basis for the current radiation protection system concerning non-cancer effects. Recent epidemiological findings point, however, to an excess risk of non-cancer diseases following exposure to lower doses of ionizing radiation than was previously thought. The evidence is the most sound for cardiovascular disease (CVD) and cataract. Due to limited statistical power, the dose-risk relationship is undetermined below 0.5 Gy; however, if this relationship proves to be without a threshold, it may have considerable impact on current low-dose health risk estimates. In this review, we describe the CVD risk related to low doses of ionizing radiation, the clinical manifestation and the pathology of radiation-induced CVD, as well as the importance of the endothelium models in CVD research as a way forward to complement the epidemiological data with the underlying biological and molecular mechanisms. PMID:27748824

  4. Commentary: ethical issues of current health-protection policies on low-dose ionizing radiation.

    PubMed

    Socol, Yehoshua; Dobrzyński, Ludwik; Doss, Mohan; Feinendegen, Ludwig E; Janiak, Marek K; Miller, Mark L; Sanders, Charles L; Scott, Bobby R; Ulsh, Brant; Vaiserman, Alexander

    2014-05-01

    The linear no-threshold (LNT) model of ionizing-radiation-induced cancer is based on the assumption that every radiation dose increment constitutes increased cancer risk for humans. The risk is hypothesized to increase linearly as the total dose increases. While this model is the basis for radiation safety regulations, its scientific validity has been questioned and debated for many decades. The recent memorandum of the International Commission on Radiological Protection admits that the LNT-model predictions at low doses are "speculative, unproven, undetectable and 'phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of sparsely-ionizing or sparsely-ionizing plus highly-ionizing radiation may be beneficial to human health (hormesis/adaptive response). The present LNT-model-based regulations impose excessive costs on the society. For example, the median-cost medical program is 5000 times more cost-efficient in saving lives than controlling radiation emissions. There are also lives lost: e.g., following Fukushima accident, more than 1000 disaster-related yet non-radiogenic premature deaths were officially registered among the population evacuated due to radiation concerns. Additional negative impacts of LNT-model-inspired radiophobia include: refusal of some patients to undergo potentially life-saving medical imaging; discouragement of the study of low-dose radiation therapies; motivation for radiological terrorism and promotion of nuclear proliferation.

  5. Involved field radiation for Hodgkin's lymphoma: The actual dose to breasts in close proximity

    SciTech Connect

    Dabaja, Bouthaina; Wang Zhonglo; Stovall, Marilyn; Baker, Jamie S.; Smith, Susan A.; Khan, Meena; Ballas, Leslie; Salehpour, Mohammad R.

    2012-01-01

    To decrease the risk of late toxicities in Hodgkin's lymphoma (HL) patients treated with radiation therapy (RT) (HL), involved field radiation therapy (IFRT) has largely replaced the extended fields. To determine the out-of-field dose delivered from a typical IFRT to surrounding critical structures, we measured the dose at various points in an anthropomorphic phantom. The phantom is divided into 1-inch-thick slices with the ability to insert TLDs at 3-cm intervals grid spacing. Two treatment fields were designed, and a total of 45 TLDs were placed (equally spaced) at the margin of the each of the 2 radiation fields. After performing a computed tomography simulation, 2 treatment plans targeting the mediastinum, a typical treatment field in patients with early stage HL, were generated. A total dose of 3060 cGy was delivered to the gross tumor volume for each field consecutively. The highest measured dose detected at 1 cm from the field edge in the planning target volume was 496 cGy, equivalent to 16% of the isocentric dose. The dose dropped significantly with increasing distance from the field edge. It ranged from 1.1-3.9% of the isocentric dose at a distance of 3.2-4 cm to <1.6% at a distance of >6 cm. Although the computer treatment planning system (CTPS) frequently underestimated the dose delivered, the difference in dose between measured and generated by CTPS was <2.5% in 90 positions measured. The collateral dose of radiation to breasts from IFRT is minimal. The out-of-field dose, although mildly underestimated by CTPS, becomes insignificant at >3 cm from the field edge of the radiation field.

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

    PubMed Central

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

    2016-01-01

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

  7. Proton tissue dose for the blood forming organ in human geometry: Isotropic radiation

    NASA Technical Reports Server (NTRS)

    Khandelwal, G. S.; Wilson, J. W.

    1974-01-01

    A computer program is described which calculates doses averaged within five major segments of the blood forming organ in the human body taking into account selfshielding of the detailed body geometry and nuclear star effects for proton radiation of arbitrary energy spectrum (energy less than 1 GeV) and isotropic angular distribution. The dose calculation includes the first term of an asymptotic series expansion of transport theory which is known to converge rapidly for most points in the human body. The result is always a conservative estimate of dose and is given as physical dose (rad) and dose equivalent (rem).

  8. Methods of space radiation dose analysis with applications to manned space systems

    NASA Technical Reports Server (NTRS)

    Langley, R. W.; Billings, M. P.

    1972-01-01

    The full potential of state-of-the-art space radiation dose analysis for manned missions has not been exploited. Point doses have been overemphasized, and the critical dose to the bone marrow has been only crudely approximated, despite the existence of detailed man models and computer codes for dose integration in complex geometries. The method presented makes it practical to account for the geometrical detail of the astronaut as well as the vehicle. Discussed are the major assumptions involved and the concept of applying the results of detailed proton dose analysis to the real-time interpretation of on-board dosimetric measurements.

  9. Determination of canine dose conversion factors in mixed neutron and gamma radiation fields. Technical report

    SciTech Connect

    Torres, B.A.; Bhatt, R.C.; Myska, J.C.; Holland, B.K.

    1996-07-01

    The primary objective of mixed-field neutron/gamma radiation dosimetry in canine irradiation experiments conducted at the Armed Forces Radiobiology Research Institute (AFRRI) is to determine the absorbed midline tissue dose (MLT) at the region of interest in the canine. A dose conversion factor (DCF) can be applied to free-in-air (FIA) dose measurements to estimate the MLT doses to canines. This report is a summary of the measured DCFs that were used to determine the MLT doses in canines at AFRRI from 1979 to 1992.

  10. Changes in biomarkers from space radiation may reflect dose not risk

    NASA Astrophysics Data System (ADS)

    Brooks, Antone L.; Lei, Xingye C.; Rithidech, Kanokporn

    This presentation evaluates differences between radiation biomarkers of dose and risk and demonstrates the consequential problems associated with using biomarkers to do risk calculations following radiation exposures to the complex radiation environment found in deep space. Dose is a physical quantity, while risk is a biological quantity. Dose does not predict risk. This manuscript discusses species sensitivity factors, tissue weighting factors, and radiation quality factors derived from relative biological effectiveness (RBE). These factors are used to modify dose to make it a better predictor of risk. At low doses, where it is not possible to measure changes in risk, biomarkers have been used incorrectly as an intermediate step in predicting risk. Examples of biomarkers that do not predict risk are reviewed. Species sensitivity factors were evaluated using the Syrian hamster and the Wistar rat. Although the frequency of chromosome damage is very similar in these two species, the Wistar rat is very sensitive to radiation-induced lung cancer while the Syrian hamster is very resistant. To illustrate problems involved in using tissue weighting factors, rat trachea and deep lung tissues were compared. The similar level of chromosome damage observed in these two tissues would predict that the risk for cancer induction would be the same. However, even though large numbers of deep lung tumors result from inhaled radon, under the same exposure conditions there has never been a tracheal tumor observed. Finally, the Relative Biological Effectiveness (RBE) used to generate "quality factors" that convert exposure and dose from different types of radiation to a single measure of risk, is discussed. Important risk comparisons are done at very low doses, where the response to the reference radiation has been shown to either increase or decrease as a function of dose. Thus, the RBE and the subsequent risk predicted is more dependent on the background response of the endpoint and

  11. Using RADFET for the real-time measurement of gamma radiation dose rate

    NASA Astrophysics Data System (ADS)

    Andjelković, Marko S.; Ristić, Goran S.; Jakšić, Aleksandar B.

    2015-02-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0 , 10 , 20  and 30 V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65  to 32.1 Gy h-1 and up to the total absorbed dose of 25 Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose.

  12. Effect of radiation protraction on BED in the case of large fraction dose

    SciTech Connect

    Kuperman, V. Y.

    2013-08-15

    Purpose: To investigate the effect of radiation protraction on biologically effective dose (BED) in the case when dose per fraction is significantly greater than the standard dose of 2 Gy.Methods: By using the modified linear-quadratic model with monoexponential repair, the authors investigate the effect of long treatment times combined with dose escalation.Results: The dependences of the protraction factor and the corresponding BED on fraction time were determined for different doses per fraction typical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). In the calculations, the authors consider changes in the BED to the normal tissue under the condition of fixed BED to the target.Conclusion: The obtained results demonstrate that simultaneous increase in fraction time and dose per fraction can be beneficial for SRS and SBRT because of the related decrease in BED to normal structures while BED to the target is fixed.

  13. 75 FR 10291 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-05

    ...: 2010-4725] DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health (ABRWH... Department of Health and Human Services (HHS) as a final rule; advice on methods of dose reconstruction...

  14. 76 FR 38182 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-29

    ... HUMAN SERVICES Centers for Disease Control and Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... Department of Health and Human Services (HHS) as a final rule; advice on methods of dose...

  15. 78 FR 733 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-04

    ... HUMAN SERVICES Centers for Disease Control and Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... Department of Health and Human Services (HHS) as a final rule; advice on methods of dose...

  16. 77 FR 14377 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... HUMAN SERVICES Centers for Disease Control and Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... Department of Health and Human Services (HHS) as a final rule; advice on methods of dose...

  17. 75 FR 21338 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-23

    ... HUMAN SERVICES Centers for Disease Control and Prevention Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker Health (ABRWH), National Institute for Occupational... Human Services (HHS) as a final rule; advice on methods of dose reconstruction which have also...

  18. DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENTIAL FLUORESCENCE ASSAY

    EPA Science Inventory

    A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposur...

  19. DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENNTIAL FLUORESENCE ASSAY

    EPA Science Inventory

    A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposures...

  20. Space radiation dose analysis for solar flare of August 1989

    SciTech Connect

    Nealy, J.E.; Simonsen, L.C.; Sauer, H.H.; Wilson, J.W.; Townsend, L.W.

    1990-12-01

    Potential dose and dose rate levels to astronauts in deep space are predicted for the solar flare event which occurred during the week of August 13, 1989. The Geostationary Operational Environmental Satellite (GOES-7) monitored the temporal development and energy characteristics of the protons emitted during this event. From these data, differential fluence as a function of energy was obtained in order to analyze the flare using the Langley baryon transport code, BRYNTRN, which describes the interactions of incident protons in matter. Dose equivalent estimates for the skin, ocular lens, and vital organs for 0.5 to 20 g/sq cm of aluminum shielding were predicted. For relatively light shielding (less than 2 g/sq cm), the skin and ocular lens 30-day exposure limits are exceeded within several hours of flare onset. The vital organ (5 cm depth) dose equivalent is exceeded only for the thinnest shield (0.5 g/sq cm). Dose rates (rem/hr) for the skin, ocular lens, and vital organs are also computed.

  1. Real-time fast inverse dose optimization for image guided adaptive radiation therapy-Enhancements to fast inverse dose optimization (FIDO)

    NASA Astrophysics Data System (ADS)

    Goldman, S. P.; Turnbull, D.; Johnson, C.; Chen, J. Z.; Battista, J. J.

    2009-05-01

    A fast, accurate and stable optimization algorithm is very important for inverse planning of intensity-modulated radiation therapy (IMRT), and for implementing dose-adaptive radiotherapy in the future. Conventional numerical search algorithms with positive beam weight constraints generally require numerous iterations and may produce suboptimal dose results due to trapping in local minima regions of the objective function landscape. A direct solution of the inverse problem using conventional quadratic objective functions without positive beam constraints is more efficient but it will result in unrealistic negative beam weights. We review here a direct solution of the inverse problem that is efficient and does not yield unphysical negative beam weights. In fast inverse dose optimization (FIDO) method the objective function for the optimization of a large number of beamlets is reformulated such that the optimization problem is reducible to a linear set of equations. The optimal set of intensities is then found through a matrix inversion, and negative beamlet intensities are avoided without the need for externally imposed ad hoc conditions. In its original version [S. P. Goldman, J. Z. Chen, and J. J. Battista, in Proceedings of the XIVth International Conference on the Use of Computers in Radiation Therapy, 2004, pp. 112-115; S. P. Goldman, J. Z. Chen, and J. J. Battista, Med. Phys. 32, 3007 (2005)], FIDO was tested on single two-dimensional computed tomography (CT) slices with sharp KERMA beams without scatter, in order to establish a proof of concept which demonstrated that FIDO could be a viable method for the optimization of cancer treatment plans. In this paper we introduce the latest advancements in FIDO that now include not only its application to three-dimensional volumes irradiated by beams with full scatter but include as well a complete implementation of clinical dose-volume constraints including maximum and minimum dose as well as equivalent uniform dose

  2. Radiation doses of employees of a Nuclear Medicine Department after implementation of more rigorous radiation protection methods.

    PubMed

    Piwowarska-Bilska, Hanna; Supinska, Aleksandra; Listewnik, Maria H; Zorga, Piotr; Birkenfeld, Bozena

    2013-11-01

    The appropriate radiation protection measures applied in departments of nuclear medicine should lead to a reduction in doses received by the employees. During 1991-2007, at the Department of Nuclear Medicine of Pomeranian Medical University (Szczecin, Poland), nurses received on average two-times higher (4.6 mSv) annual doses to the whole body than those received by radiopharmacy technicians. The purpose of this work was to examine whether implementation of changes in the radiation protection protocol will considerably influence the reduction in whole-body doses received by the staff that are the most exposed. A reduction in nurses' exposure by ~63 % took place in 2008-11, whereas the exposure of radiopharmacy technicians grew by no more than 22 % in comparison with that in the period 1991-2007. Proper reorganisation of the work in departments of nuclear medicine can considerably affect dose reduction and bring about equal distribution of the exposure.

  3. Radioimmunotherapy treatment planning based on radiation absorbed dose or patient size

    SciTech Connect

    Eary, J.F.; Krohn, K.A.; Press, O.W. |

    1996-05-01

    Several approaches have been used to plan treatment doses for patients undergoing radioimmunotherapy. Investigators often use fixed doses, or doses based on patient size (mCi/kg or mCi/m{sup 2}). Our treatment protocols for lymphoma and leukemia involved calculation of tissue radiation absorbed dose based on images from a trace labeled infusion of antibody prior to treatment. In a recent analysis of patients treated in the Phase I and II dose escalation trial for treatment of non-Hodgkin`s lymphoma with I-131 anti-CD20 antibody (B1), we investigated the relationship between our dosimetry based treatment and dose based on patient size. Tissue radiation dose for several normal organs and for tumors were plotted versus the mCi administered per kg or m{sup 2} of the patient to evaluate the relationship between the two treatment approaches. These graphs showed correlation coefficients ranging from 0.021 to 0.684, demonstrating the variability in antibody catabolism between patients. This means that fixed doses or administrations based on patient size do not deliver consistent radiation doses to normal organs or tumors. This finding was extrapolated to show that toxicity from doses based on patient size di not correlate with treatment dose; those based on calculated rad/organ did. Phase I clinical trials using treatment doses based on patient size where there are likely to be variations in patient antibody catabolism will result in confounding toxicities at apparently similar mCi dose levels. Use of pre-treatment scans for treatment dose planning are worth the additional effort by normalizing the normal tissue toxicity.

  4. Low-dose ionising radiation and cardiovascular diseases--Strategies for molecular epidemiological studies in Europe.

    PubMed

    Kreuzer, Michaela; Auvinen, Anssi; Cardis, Elisabeth; Hall, Janet; Jourdain, Jean-Rene; Laurier, Dominique; Little, Mark P; Peters, Annette; Raj, Ken; Russell, Nicola S; Tapio, Soile; Zhang, Wei; Gomolka, Maria

    2015-01-01

    It is well established that high-dose ionising radiation causes cardiovascular diseases. In contrast, the evidence for a causal relationship between long-term risk of cardiovascular diseases after moderate doses (0.5-5 Gy) is suggestive and weak after low doses (<0.5 Gy). However, evidence is emerging that doses under 0.5 Gy may also increase long-term risk of cardiovascular disease. This would have major implications for radiation protection with respect to medical use of radiation for diagnostic purposes and occupational or environmental radiation exposure. Therefore, it is of great importance to gain information about the presence and possible magnitude of radiation-related cardiovascular disease risk at doses of less than 0.5 Gy. The biological mechanisms implicated in any such effects are unclear and results from epidemiological studies are inconsistent. Molecular epidemiological studies can improve the understanding of the pathogenesis and the risk estimation of radiation-induced circulatory disease at low doses. Within the European DoReMi (Low Dose Research towards Multidisciplinary Integration) project, strategies to conduct molecular epidemiological studies in this field have been developed and evaluated. Key potentially useful European cohorts are the Mayak workers, other nuclear workers, uranium miners, Chernobyl liquidators, the Techa river residents and several diagnostic or low-dose radiotherapy patient cohorts. Criteria for informative studies are given and biomarkers to be investigated suggested. A close collaboration between epidemiology, biology and dosimetry is recommended, not only among experts in the radiation field, but also those in cardiovascular diseases.

  5. Increasing Use of Dose-Escalated External Beam Radiation Therapy for Men With Nonmetastatic Prostate Cancer

    SciTech Connect

    Swisher-McClure, Samuel; Mitra, Nandita; Woo, Kaitlin; Smaldone, Marc; Uzzo, Robert; Bekelman, Justin E.

    2014-05-01

    Purpose: To examine recent practice patterns, using a large national cancer registry, to understand the extent to which dose-escalated external beam radiation therapy (EBRT) has been incorporated into routine clinical practice for men with prostate cancer. Methods and Materials: We conducted a retrospective observational cohort study using the National Cancer Data Base, a nationwide oncology outcomes database in the United States. We identified 98,755 men diagnosed with nonmetastatic prostate cancer between 2006 and 2011 who received definitive EBRT and classified patients into National Comprehensive Cancer Network (NCCN) risk groups. We defined dose-escalated EBRT as total prescribed dose of ≥75.6 Gy. Using multivariable logistic regression, we examined the association of patient, clinical, and demographic characteristics with the use of dose-escalated EBRT. Results: Overall, 81.6% of men received dose-escalated EBRT during the study period. The use of dose-escalated EBRT did not vary substantially by NCCN risk group. Use of dose-escalated EBRT increased from 70.7% of patients receiving treatment in 2006 to 89.8% of patients receiving treatment in 2011. On multivariable analysis, year of diagnosis and use of intensity modulated radiation therapy were significantly associated with receipt of dose-escalated EBRT. Conclusions: Our study results indicate that dose-escalated EBRT has been widely adopted by radiation oncologists treating prostate cancer in the United States. The proportion of patients receiving dose-escalated EBRT increased nearly 20% between 2006 and 2011. We observed high utilization rates of dose-escalated EBRT within all disease risk groups. Adoption of intensity modulated radiation therapy was strongly associated with use of dose-escalated treatment.

  6. Radiation Dose-Volume Effects and the Penile Bulb

    SciTech Connect

    Roach, Mack; Nam, Jiho; Gagliardi, Giovanna; El Naqa, Issam; Deasy, Joseph O.; Marks, Lawrence B.

    2010-03-01

    The dose, volume, and clinical outcome data for penile bulb are reviewed for patients treated with external-beam radiotherapy. Most, but not all, studies find an association between impotence and dosimetric parameters (e.g., threshold doses) and clinical factors (e.g., age, comorbid diseases). According to the data available, it is prudent to keep the mean dose to 95% of the penile bulb volume to <50 Gy. It may also be prudent to limit the D70 and D90 to 70 Gy and 50 Gy, respectively, but coverage of the planning target volume should not be compromised. It is acknowledged that the penile bulb may not be the critical component of the erectile apparatus, but it seems to be a surrogate for yet to be determined structure(s) critical for erectile function for at least some techniques.

  7. Differential Response and Priming Dose Effect on the Proteome of Human Fibroblast and Stem Cells Induced by Exposure to Low Doses of Ionizing Radiation.

    PubMed

    Hauptmann, Monika; Haghdoost, Siamak; Gomolka, Maria; Sarioglu, Hakan; Ueffing, Marius; Dietz, Anne; Kulka, Ulrike; Unger, Kristian; Babini, Gabriele; Harms-Ringdahl, Mats; Ottolenghi, Andrea; Hornhardt, Sabine

    2016-03-01

    It has been suggested that a mechanistic understanding of the cellular responses to low dose and dose rate may be valuable in reducing some of the uncertainties involved in current risk estimates for cancer- and non-cancer-related radiation effects that are inherited in the linear no-threshold hypothesis. In this study, the effects of low-dose radiation on the proteome in both human fibroblasts and stem cells were investigated. Particular emphasis was placed on examining: 1. the dose-response relationships for the differential expression of proteins in the low-dose range (40-140 mGy) of low-linear energy transfer (LET) radiation; and 2. the effect on differential expression of proteins of a priming dose given prior to a challenge dose (adaptive response effects). These studies were performed on cultured human fibroblasts (VH10) and human adipose-derived stem cells (ADSC). The results from the VH10 cell experiments demonstrated that low-doses of low-LET radiation induced unique patterns of differentially expressed proteins for each dose investigated. In addition, a low priming radiation dose significantly changed the protein expression induced by the subsequent challenge exposure. In the ADSC the number of differentially expressed proteins was markedly less compared to VH10 cells, indicating that ADSC differ in their intrinsic response to low doses of radiation. The proteomic results are further discussed in terms of possible pathways influenced by low-dose irradiation.

  8. The Effect of High-Dose Ionizing Radiation on the Astrobiological Model Lichen Circinaria gyrosa.

    PubMed

    de la Torre, Rosa; Miller, Ana Zélia; Cubero, Beatriz; Martín-Cerezo, M Luisa; Raguse, Marina; Meeßen, Joachim

    2017-02-01

    The lichen Circinaria gyrosa is an astrobiological model defined by its high capacity of resistance to space conditions and to a simulated martian environment. Therefore, it became part of the currently operated BIOMEX experiment on board the International Space Station and the recent STARLIFE campaign to study the effects of four types of space-relevant ionizing radiation. The samples were irradiated with helium and iron ions at doses up to 2 kGy, with X-rays at doses up to 5 kGy and with γ rays at doses from 6 to 113 kGy. Results on C. gyrosa's resistance to simulated space ionizing radiation and its post-irradiation viability were obtained by (i) chlorophyll a fluorescence of photosystem II (PSII), (ii) epifluorescence microscopy, (iii) confocal laser scanning microscopy (CLSM), and (iv) field emission scanning electron microscopy (FESEM). Results of photosynthetic activity and epifluorescence show no significant changes up to a dose of 1 kGy (helium ions), 2 kGy (iron ions), 5 kGy (X-rays)-the maximum doses applied for those radiation qualities-as well as a dose of 6 kGy of γ irradiation, which was the lowest dose applied for this low linear energy transfer (LET) radiation. Significant damage in a dose-related manner was observed only at much higher doses of γ irradiation (up to 113 kGy). These data corroborate the findings of the parallel STARLIFE studies on the effects of ionizing radiation on the lichen Circinaria gyrosa, its isolated photobiont, and the lichen Xanthoria elegans. Key Words: Simulated space ionizing radiation-Gamma rays-Extremotolerance-Lichens-Circinaria gyrosa-Photosynthetic activity. Astrobiology 17, 145-153.

  9. Alteration of cytokine profiles in mice exposed to chronic low-dose ionizing radiation

    SciTech Connect

    Shin, Suk Chul; Lee, Kyung-Mi; Kang, Yu Mi; Kim, Kwanghee; Kim, Cha Soon; Yang, Kwang Hee; Jin, Young-Woo; Kim, Chong Soon; Kim, Hee Sun

    2010-07-09

    While a high-dose of ionizing radiation is generally harmful and causes damage to living organisms, a low-dose of radiation has been shown to be beneficial in a variety of animal models. To understand the basis for the effect of low-dose radiation in vivo, we examined the cellular and immunological changes evoked in mice exposed to low-dose radiation at very low (0.7 mGy/h) and low (3.95 mGy/h) dose rate for the total dose of 0.2 and 2 Gy, respectively. Mice exposed to low-dose radiation, either at very low- or low-dose rate, demonstrated normal range of body weight and complete blood counts. Likewise, the number and percentage of peripheral lymphocyte populations, CD4{sup +} T, CD8{sup +} T, B, or NK cells, stayed unchanged following irradiation. Nonetheless, the sera from these mice exhibited elevated levels of IL-3, IL-4, leptin, MCP-1, MCP-5, MIP-1{alpha}, thrombopoietin, and VEGF along with slight reduction of IL-12p70, IL-13, IL-17, and IFN-{gamma}. This pattern of cytokine release suggests the stimulation of innate immunity facilitating myeloid differentiation and activation while suppressing pro-inflammatory responses and promoting differentiation of naive T cells into T-helper 2, not T-helper 1, types. Collectively, our data highlight the subtle changes of cytokine milieu by chronic low-dose {gamma}-radiation, which may be associated with the functional benefits observed in various experimental models.

  10. Internal Radiation Exposure Dose in Iwaki City, Fukushima Prefecture after the Accident at Fukushima Dai-ichi Nuclear Power Plant

    PubMed Central

    Orita, Makiko; Hayashida, Naomi; Nukui, Hiroshi; Fukuda, Naoko; Kudo, Takashi; Matsuda, Naoki; Fukushima, Yoshiko; Takamura, Noboru

    2014-01-01

    As a result of the accident at the Fukushima Daiichi Nuclear Power Plant (FNPP) on 11 March 2011, a huge amount of radionuclides, including radiocesium, was released and spread over a wide area of eastern Japan. Although three years have passed since the accident, residents around the FNPP are anxious about internal radiation exposure due to radiocesium. In this study, we screened internal radiation exposure doses in Iwaki city of Fukushima prefecture, using a whole-body counter. The first screening was conducted from October 2012 to February 2013, and the second screening was conducted from May to November 2013. Study participants were employees of ALPINE and their families who underwent examination. A total of 2,839 participants (1,366 men and 1,473 women, 1–86 years old) underwent the first screening, and 2,092 (1,022 men and 1,070 women, 1–86 years old) underwent the second screening. The results showed that 99% of subjects registered below 300 Bq per body in the first screening, and all subjects registered below 300 Bq per body in the second screening. The committed effective dose ranged from 0.01–0.06 mSv in the first screening and 0.01–0.02 mSv in the second screening. Long-term follow-up studies are needed to avoid unnecessary chronic internal exposure and to reduce anxiety among the residents by communicating radiation health risks. PMID:25478794

  11. Internal radiation exposure dose in Iwaki city, Fukushima prefecture after the accident at Fukushima Dai-ichi Nuclear Power Plant.

    PubMed

    Orita, Makiko; Hayashida, Naomi; Nukui, Hiroshi; Fukuda, Naoko; Kudo, Takashi; Matsuda, Naoki; Fukushima, Yoshiko; Takamura, Noboru

    2014-01-01

    As a result of the accident at the Fukushima Daiichi Nuclear Power Plant (FNPP) on 11 March 2011, a huge amount of radionuclides, including radiocesium, was released and spread over a wide area of eastern Japan. Although three years have passed since the accident, residents around the FNPP are anxious about internal radiation exposure due to radiocesium. In this study, we screened internal radiation exposure doses in Iwaki city of Fukushima prefecture, using a whole-body counter. The first screening was conducted from October 2012 to February 2013, and the second screening was conducted from May to November 2013. Study participants were employees of ALPINE and their families who underwent examination. A total of 2,839 participants (1,366 men and 1,473 women, 1-86 years old) underwent the first screening, and 2,092 (1,022 men and 1,070 women, 1-86 years old) underwent the second screening. The results showed that 99% of subjects registered below 300 Bq per body in the first screening, and all subjects registered below 300 Bq per body in the second screening. The committed effective dose ranged from 0.01-0.06 mSv in the first screening and 0.01-0.02 mSv in the second screening. Long-term follow-up studies are needed to avoid unnecessary chronic internal exposure and to reduce anxiety among the residents by communicating radiation health risks.

  12. Radiation Dose Reduction Efficiency of Buildings after the Accident at the Fukushima Daiichi Nuclear Power Station

    PubMed Central

    Monzen, Satoru; Hosoda, Masahiro; Osanai, Minoru; Tokonami, Shinji

    2014-01-01

    Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55±0.04, 0.15±0.02, and 0.19±0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites. PMID:24999992

  13. Natural radiation doses for cosmic and terrestrial components in Costa Rica.

    PubMed

    Mora, Patricia; Picado, Esteban; Minato, Susumu

    2007-01-01

    A study of external natural radiation, cosmic and terrestrial components, was carried out with in situ measurements using NaI scintillation counters while driving along the roads in Costa Rica for the period July 2003-July 2005. The geographical distribution of the terrestrial air-absorbed dose rates and the total effective dose rates (including cosmic) are represented on contour maps. Information on the population density of the country permitted the calculation of the per capita doses. The average effective dose for the total cosmic component was 46.88+/-18.06 nSvh(-1) and the average air-absorbed dose for the terrestrial component was 29.52+/-14.46 nGyh(-1). The average total effective dose rate (cosmic plus terrestrial components) was 0.60+/-0.18 mSv per year. The effective dose rate per capita was found to be 83.97 nSvh(-1) which gives an annual dose of 0.74 mSv. Assuming the world average for the internal radiation component, the natural radiation dose for Costa Rica will be 2.29 mSv annually.

  14. Radiation dose reduction efficiency of buildings after the accident at the Fukushima Daiichi Nuclear Power Station.

    PubMed

    Monzen, Satoru; Hosoda, Masahiro; Osanai, Minoru; Tokonami, Shinji

    2014-01-01

    Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55 ± 0.04, 0.15 ± 0.02, and 0.19 ± 0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites.

  15. Can the Equivalent Sphere Model Approximate Organ Doses in Space Radiation Environments?

    NASA Technical Reports Server (NTRS)

    Zi-Wei, Lin

    2007-01-01

    In space radiation calculations it is often useful to calculate the dose or dose equivalent in blood-forming organs (BFO). the skin or the eye. It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However previous studies have shown that a 5cm sphere gives conservative dose values for BFO. In this study we use a deterministic radiation transport with the Computerized Anatomical Man model to investigate whether the equivalent sphere model can approximate organ doses in space radiation environments. We find that for galactic cosmic rays environments the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent and marginally well for the BFO dose and the dose equivalent of the eye or the skin. For solar particle events the radius parameters for the organ dose equivalent increase with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin The ranges of the radius parameters are also shown and the BFO radius parameters are found to be significantly larger than 5 cm in all eases.

  16. Influence of Flat-Panel Fluoroscopic Equipment Variables on Cardiac Radiation Doses

    SciTech Connect

    Nickoloff, Edward L. Lu Zhengfeng; Dutta, Ajoy; So, James; Balter, Stephen; Moses, Jeffrey

    2007-04-15

    Purpose. To assess the influence of physician-selectable equipment variables on the potential radiation dose reductions during cardiac catheterization examinations using modern imaging equipment. Materials. A modern bi-plane angiography unit with flat-panel image receptors was used. Patients were simulated with 15-30 cm of acrylic plastic. The variables studied were: patient thickness, fluoroscopy pulse rates, record mode frame rates, image receptor field-of-view (FoV), automatic dose control (ADC) mode, SID/SSD geometry setting, automatic collimation, automatic positioning, and others. Results. Patient radiation doses double for every additional 3.5-4.5 cm of soft tissue. The dose is directly related to the imaging frame rate; a decrease from 30 pps to 15 pps reduces the dose by about 50%. The dose is related to [(FoV){sup -N}] where 2.0 < N < 3.0. Suboptimal positioning of the patient can nearly double the dose. The ADC system provides three selections that can vary the radiation level by 50%. For pediatric studies (2-5 years old), the selection of equipment variables can result in entrance radiation doses that range between 6 and 60 cGy for diagnostic cases and between 15 and 140 cGy for interventional cases. For adult studies, the equipment variables can produce entrance radiation doses that range between 13 and 130 cGy for diagnostic cases and between 30 and 400 cGy for interventional cases. Conclusions. Overall dose reductions of 70-90% can be achieved with pediatric patients and about 90% with adult patients solely through optimal selection of equipment variables.

  17. Low Dose Radiation Hypersensitivity is Caused by p53-dependent Apoptosis

    SciTech Connect

    Enns, L; Bogen, K; Wizniak, J; Murtha, A; Weinfeld, M

    2004-04-08

    Exposure to environmental radiation and the application of new clinical modalities, such as radioimmunotherapy, have heightened the need to understand cellular responses to low dose and low-dose rate ionizing radiation. Many tumor cell lines have been observed to exhibit a hypersensitivity to radiation doses below 50 cGy, which manifests as a significant deviation from the clonogenic survival response predicted by a linear-quadratic fit to higher doses. However, the underlying processes for this phenomenon remain unclear. Using a gel microdrop/flow cytometry assay to monitor single cell proliferation at early times post irradiation, we examined the response of human A549 lung carcinoma, T98G glioma and MCF7 breast carcinoma cell lines exposed to gamma radiation doses from 0 to 200 cGy delivered at 0.18 and 22 cGy/min. The A549 and T98G cells, but not MCF7 cells, showed the marked hypersensitivity at doses <50 cGy. To further characterize the low-dose hypersensitivity, we examined the influence of low-dose radiation on cell cycle status and apoptosis by assays for active caspase-3 and phosphatidylserine translocation (annexin-V binding). We observed that caspase-3 activation and annexin-V binding mirrored the proliferation curves for the cell lines. Furthermore, the low-dose hypersensitivity and annexin-V binding to irradiated A549 and T98G cells were eliminated by treating the cells with pifithrin, an inhibitor of p53. When p53-inactive cell lines (2800T skin fibroblasts and HCT116 colorectal carcinoma cells) were examined for similar patterns, we found that there was no HRS and apoptosis was not detectable by annexin-V or caspase-3 assays. Our data therefore suggest that low-dose hypersensitivity is associated with p53-dependent apoptosis.

  18. The Radiation Dose Determination of the Pulsed X-ray Source

    NASA Astrophysics Data System (ADS)

    Miloichikova, I.; Stuchebrov, S.; Zhaksybayeva, G.; Wagner, A.

    2014-10-01

    In this paper the radiation dose measurement technique of the pulsed X-ray source RAP-160-5 is described. The dose rate measurement results from the pulsed X-ray beams at the different distance between the pulsed X-ray source focus and the detector obtained with the help of the thermoluminescent detectors DTL-02, the universal dosimeter UNIDOS E equipped with the plane-parallel ionization chamber type 23342, the dosimeter-radiometer DKS-96 and the radiation dosimeter AT 1123 are demonstrated. The recommendations for the dosimetry measurements of the pulsed X-ray generator RAP-160-5 under different radiation conditions are proposed.

  19. Somnolence syndrome in leukemic children following reduced daily dose fractions of cranial radiation

    SciTech Connect

    Littman, P.; Rosenstock, J.; Gale, G.; Krisch, R.E.; Meadows, A.; Sather, H.; Coccia, P.; DeCamagro, B.

    1984-10-01

    A group of children with acute lymphocytic leukemia was studied to investigate if a reduction in daily dose fraction of cranial radiation would reduce the incidence of somnolence syndrome. Thirty-one evaluable patients received 100 rad x 18 cranial radiation therapy. Sixty-six similar evaluable patients were given 180 rad x 10. Both groups received the same chemotherapy including intrathecal methotrexate. Clinically detectable somnolence appeared in 58% of each group without significant differences in the overall frequency or severity of somnolence. This study failed to substantiate a radiation dose fraction size dependence for somnolence syndrome in children with acute lymphocytic leukemia.

  20. Gamma-irradiated onions as a biological indicator of radiation dose.

    PubMed

    Vaijapurkar, S G; Agarwal, D; Chaudhuri, S K; Senwar, K R; Bhatnagar, P K

    2001-10-01

    Post-irradiation identification and dose estimation are required to assess the radiation-induced effects on living things in any nuclear emergency. In this study, radiation-induced morphological/cytological changes i.e., number of root formation and its length, shooting length, reduction in mitotic index, micronuclei formation and chromosomal aberrations in the root tip cells of gamma-irradiated onions at lower doses (50-2000 cGy) are reported. The capabilities of this biological species to store the radiation-induced information are also studied.

  1. Nuclear medicine dose equivalent a method for determination of radiation risk

    SciTech Connect

    Huda, W.

    1986-12-01

    Conventional nuclear medicine dosimetry involves specifying individual organ doses. The difficulties that can arise with this approach to radiation dosimetry are discussed. An alternative scheme is described that is based on the ICRP effective dose equivalent, H/sub E/, and which is a direct estimate of the average radiation risk to the patient. The mean value of H/sub E/ for seven common /sup 99m/Tc nuclear medicine procedures is 0.46 rem and the average radiation risk from this level of exposure is estimated to be comparable to the risk from smoking approx. 28 packs of cigarettes or driving approx. 1300 miles.

  2. Radiation Dose-Volume Effects in the Larynx and Pharynx

    SciTech Connect

    Rancati, Tiziana; Schwarz, Marco; Allen, Aaron M.; Feng, Felix; Popovtzer, Aron; Mittal, Bharat; Eisbruch, Avraham

    2010-03-01

    The dose-volume outcome data for RT-associated laryngeal edema, laryngeal dysfunction, and dysphagia, have only recently been addressed, and are summarized. For late dysphagia, a major issue is accurate definition and uncertainty of the relevant anatomical structures. These and other issues are discussed.

  3. RISKS AND RADIATION DOSES DUE TO RESIDENTIAL RADON IN GERMANY.

    PubMed

    Beck, T R

    2017-01-10

    The population-averaged risk rate and the annual average effective dose due to residential radon in Germany were calculated. The calculations were based on an epidemiological approach taking into account the age- and gender-specific lung cancer incidence rates for the German population and the excess relative risk of 0.16 per 100 Bq·m(-3) for residential radon. In addition, the risk estimates adjusted for the smoking habits were determined. The population-averaged risk rate for the whole population was estimated with 4.1·10(-5) y(-1) (95% confidence interval (CI) 1.4·10(-5)-7.6·10(-5) y(-1)). Residential radon causes a detriment per year of 3.3·10(-5) y(-1) (95% CI 1.1·10(-5)-6.0·10(-5) y(-1)), which corresponds to an annual average effective dose of 0.6 mSv (95% CI 0.2-1.1 mSv). Annually, ~3400 lung cancer incidences are attributed to residential radon. The results from the epidemiological approach exercised in this study are considerably lower than the effective dose, which would be obtained from the dose conversion coefficient calculated using biokinetic and dosimetric models.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Method for detecting radiation dose utilizing thermoluminescent material

    DOEpatents

    Miller, Steven D.; McDonald, Joseph C.; Eichner, Fred N.; Durham, James S.

    1992-01-01

    The amount of ionizing radiation to which a thermoluminescent material has been exposed is determined by first cooling the thermoluminescent material and then optically stimulating the thermoluminescent material by exposure to light. Visible light emitted by the thermoluminescent material as it is allowed to warm up to room temperature is detected and counted. The thermoluminescent material may be annealed by exposure to ultraviolet light.

  6. Estimated Ultraviolet Radiation Doses in Wetlands in Six National Parks

    EPA Science Inventory

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

  7. Radiation Dose-Volume Effects of the Urinary Bladder

    SciTech Connect

    Viswanathan, Akila N.; Marks, Lawrence B.; Eifel, Patricia J.; Shipley, William U.

    2010-03-01

    An in-depth overview of the normal-tissue radiation tolerance of the urinary bladder is presented. The most informative studies consider whole-organ irradiation. The data on partial-organ/nonuniform irradiation are suspect because the bladder motion is not accounted for, and many studies lack long enough follow-up data. Future studies are needed.

  8. ESTIMATION OF UV RADIATION DOSE IN NORTHERN MINNESOTA WETLANDS

    EPA Science Inventory

    The ultraviolet (UV) B wavelength range (280 nm to 320 nm) of solar radiation can be a significant biological stressor, and has been hypothesized to be partially responsible for amphibian declines and malformation. This hypothesis has been difficult to evaluate, in part, because ...

  9. [Management and delivery of radiation dose distribution images using the Internet].

    PubMed

    Onogi, Y; Nakagawa, K; Aoki, Y; Kozuka, T; Toyoda, T; Sasaki, Y

    1998-01-01

    Dose distribution images play important roles in the management of cancer patients. To date hard copies of these images have been stored and referred to by radiation oncologists as needed. In most cases, these images were not available to medical personnel outside the radiation oncology department. We have developed a mechanism in the hospital to access these dose distribution images via WWW (World Wide Web). A screen snapshot of a dose distribution image on the CRT of a treatment planning machine is copied to the WWW server and converted to a GIF image. Similarly, we can register dose volume histograms and digitally reconstructed radiographs on the WWW. Medical personnel throughout the hospital can access the images through the WWW browser. As a result, radiation oncologists are given detailed information on target definition in treatment planning by expert physicians. The system also helps co-medical staff in understanding dose distributions and predicting radiation injuries. At the same time, it actualizes an electronic archive of dose distribution images, which is a database for quick and reliable review, evaluation and comparison of treatment plans. This technique also furthers a close relationship among radiation oncologists, physicians, and co-medical personnel.

  10. A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN.

    PubMed

    Bahadori, Amir A; Sato, Tatsuhiko; Slaba, Tony C; Shavers, Mark R; Semones, Edward J; Van Baalen, Mary; Bolch, Wesley E

    2013-10-21

    NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum.

  11. Nuclear energy and health: and the benefits of low-dose radiation hormesis.

    PubMed

    Cuttler, Jerry M; Pollycove, Myron

    2009-01-01

    Energy needs worldwide are expected to increase for the foreseeable future, but fuel supplies are limited. Nuclear reactors could supply much of the energy demand in a safe, sustainable manner were it not for fear of potential releases of radioactivity. Such releases would likely deliver a low dose or dose rate of radiation, within the range of naturally occurring radiation, to which life is already accustomed. The key areas of concern are discussed. Studies of actual health effects, especially thyroid cancers, following exposures are assessed. Radiation hormesis is explained, pointing out that beneficial effects are expected following a low dose or dose rate because protective responses against stresses are stimulated. The notions that no amount of radiation is small enough to be harmless and that a nuclear accident could kill hundreds of thousands are challenged in light of experience: more than a century with radiation and six decades with reactors. If nuclear energy is to play a significant role in meeting future needs, regulatory authorities must examine the scientific evidence and communicate the real health effects of nuclear radiation. Negative images and implications of health risks derived by unscientific extrapolations of harmful effects of high doses must be dispelled.

  12. Nuclear Energy and Health: And the Benefits of Low-Dose Radiation Hormesis

    PubMed Central

    Cuttler, Jerry M.; Pollycove, Myron

    2009-01-01

    Energy needs worldwide are expected to increase for the foreseeable future, but fuel supplies are limited. Nuclear reactors could supply much of the energy demand in a safe, sustainable manner were it not for fear of potential releases of radioactivity. Such releases would likely deliver a low dose or dose rate of radiation, within the range of naturally occurring radiation, to which life is already accustomed. The key areas of concern are discussed. Studies of actual health effects, especially thyroid cancers, following exposures are assessed. Radiation hormesis is explained, pointing out that beneficial effects are expected following a low dose or dose rate because protective responses against stresses are stimulated. The notions that no amount of radiation is small enough to be harmless and that a nuclear accident could kill hundreds of thousands are challenged in light of experience: more than a century with radiation and six decades with reactors. If nuclear energy is to play a significant role in meeting future needs, regulatory authorities must examine the scientific evidence and communicate the real health effects of nuclear radiation. Negative images and implications of health risks derived by unscientific extrapolations of harmful effects of high doses must be dispelled. PMID:19343116

  13. Image texture and radiation dose properties in CT.

    PubMed

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

    2016-05-08

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

  14. Cellular response to low dose radiation: Role of phosphatidylinositol-3 kinase like kinases

    SciTech Connect

    Balajee, A.S.; Meador, J.A.; Su, Y.

    2011-03-24

    It is increasingly realized that human exposure either to an acute low dose or multiple chronic low doses of low LET radiation has the potential to cause different types of cancer. Therefore, the central theme of research for DOE and NASA is focused on understanding the molecular mechanisms and pathways responsible for the cellular response to low dose radiation which would not only improve the accuracy of estimating health risks but also help in the development of predictive assays for low dose radiation risks associated with tissue degeneration and cancer. The working hypothesis for this proposal is that the cellular mechanisms in terms of DNA damage signaling, repair and cell cycle checkpoint regulation are different for low and high doses of low LET radiation and that the mode of action of phosphatidylinositol-3 kinase like kinases (PIKK: ATM, ATR and DNA-PK) determines the dose dependent cellular responses. The hypothesis will be tested at two levels: (I) Evaluation of the role of ATM, ATR and DNA-PK in cellular response to low and high doses of low LET radiation in simple in vitro human cell systems and (II) Determination of radiation responses in complex cell microenvironments such as human EpiDerm tissue constructs. Cellular responses to low and high doses of low LET radiation will be assessed from the view points of DNA damage signaling, DNA double strand break repair and cell cycle checkpoint regulation by analyzing the activities (i.e. post-translational modifications and kinetics of protein-protein interactions) of the key target proteins for PI-3 kinase like kinases both at the intra-cellular and molecular levels. The proteins chosen for this proposal are placed under three categories: (I) sensors/initiators include ATM ser1981, ATR, 53BP1, gamma-H2AX, MDC1, MRE11, Rad50 and Nbs1; (II) signal transducers include Chk1, Chk2, FANCD2 and SMC1; and (III) effectors include p53, CDC25A and CDC25C. The primary goal of this proposal is to elucidate the

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

    SciTech Connect

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

    2011-09-19

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

  16. Radiation Dose to the Skin and to the Gonads from Diagnostic X-Ray Procedures

    PubMed Central

    Duggan, H. E.; Olde, G. L.

    1963-01-01

    The design of a study to assess the hazard to patients from radiation received during diagnostic radiological procedures is described. The long-term accumulation of data relating to the skin and gonadal doses received by patients in a large x-ray department has been initiated. This will serve as a model for any situation involving small recurrent radiation doses to a significant proportion of the population. A description is given of the basic dose measurements made and the method used in calculating and recording the skin and gonadal doses for each patient. Although no definite conclusions concerning the presence or absence of a radiation hazard have yet been made, the proposed future course of this study is discussed. ImagesFig. 3Fig. 4 PMID:14079142

  17. Monitoring radiation dose to the hands in nuclear medicine: location of dosemeters.

    PubMed

    Williams, E D; Laird, E E; Forster, E

    1987-07-01

    The relatively high radiation dose which can be received by the hands of staff in nuclear medicine departments means that in many departments it is necessary to monitor such doses. A convenient method is to use a TLD sachet in a plastic strip around a finger. This study was done to determine whether a dosemeter worn at the base of the middle finger was adequate to monitor the dose to the surface of the whole hand. Dosemeters were worn at the finger tips, finger base and palm of both hands, on two people while preparing and dispensing radio-pharmaceuticals, and two others while giving injections using syringe shields. The pattern of distribution of radiation does to the hands was similar for all workers and for both types of work. A single, convenient site (base of middle finger) may therefore be used for monitoring radiation dose to the hand.

  18. Open-source radiation exposure extraction engine (RE3) for dose monitoring

    NASA Astrophysics Data System (ADS)

    Weisenthal, Samuel; Folio, Les; Derderian, Vana; Summers, Ronald M.; Yao, Jianhua

    2015-03-01

    Our goal was to investigate the feasibility of an open-source, PACS-integrated, DICOM header-based tool that automatically provides granular data for monitoring of CT radiation exposure. To do so, we constructed a radiation exposure extraction engine (RE3) that is seamlessly connected to the PACS using the digital imaging and communications in medicine (DICOM) toolkit (DCMTK) and runs on the fly within the workflow. We evaluated RE3's ability to determine the number of acquisitions and calculate the exposure metric dose length product (DLP) by comparing its output to the vendor dose pages. RE3 output closely correlated to the dose pages for both contiguously acquired exams (R2 =0.9987) and non-contiguously acquired exams (R2 =0.9994). RE3 is an open-source, automated radiation monitoring program to provide study-, series-, and slice-level radiation data.

  19. Estimation of annual occupational effective doses from external ionizing radiation at medical institutions in Kenya

    NASA Astrophysics Data System (ADS)

    Korir, Geoffrey; Wambani, Jeska; Korir, Ian

    2011-04-01

    This study details the distribution and trends of doses due to occupational radiation exposure among radiation workers from participating medical institutions in Kenya, where monthly dose measurements were collected for a period of one year ranging from January to December in 2007. A total of 367 medical radiation workers were monitored using thermoluminescent dosemeters. They included radiologists (27%), oncologists (2%), dentists (4%), Physicists (5%), technologists (45%), nurses (4%), film processor technicians (3%), auxiliary staff (4%), and radiology office staff (5%). The average annual effective dose of all categories of staff was found to range from 1.19 to 2.52 mSv. This study formed the initiation stage of wider, comprehensive and more frequent monitoring of occupational radiation exposures and long-term investigations into its accumulation patterns in our country.

  20. Hormetic Response to Low-Dose Radiation: Focus on the Immune System and Its Clinical Implications

    PubMed Central

    Cui, Jiuwei; Yang, Guozi; Pan, Zhenyu; Zhao, Yuguang; Liang, Xinyue; Li, Wei; Cai, Lu

    2017-01-01

    The interrelationship between ionizing radiation and the immune system is complex, multifactorial, and dependent on radiation dose/quality and immune cell type. High-dose radiation usually results in immune suppression. On the contrary, low-dose radiation (LDR) modulates a variety of immune responses that have exhibited the properties of immune hormesis. Although the underlying molecular mechanism is not fully understood yet, LDR has been used clinically for the treatment of autoimmune diseases and malignant tumors. These advancements in preclinical and clinical studies suggest that LDR-mediated immune modulation is a well-orchestrated phenomenon with clinical potential. We summarize recent developments in the understanding of LDR-mediated immune modulation, with an emphasis on its potential clinical applications. PMID:28134809

  1. Total-dose radiation effects data for semiconductor devices: 1985 supplement, volume 1

    NASA Technical Reports Server (NTRS)

    Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

    1985-01-01

    Steady-state, total-dose radiation test data are provided, in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 provides total-dose radiation test data on integrated circuits. Volume 1 of this 1985 Supplement contains new total-dose radiation test data generated since the August 1, 1981 release date of the original Volume 1. Publication of Volume 2 of the 1985 Supplement will follow that of Volume 1 by approximately three months.

  2. Hormetic Response to Low-Dose Radiation: Focus on the Immune System and Its Clinical Implications.

    PubMed

    Cui, Jiuwei; Yang, Guozi; Pan, Zhenyu; Zhao, Yuguang; Liang, Xinyue; Li, Wei; Cai, Lu

    2017-01-27

    The interrelationship between ionizing radiation and the immune system is complex, multifactorial, and dependent on radiation dose/quality and immune cell type. High-dose radiation usually results in immune suppression. On the contrary, low-dose radiation (LDR) modulates a variety of immune responses that have exhibited the properties of immune hormesis. Although the underlying molecular mechanism is not fully understood yet, LDR has been used clinically for the treatment of autoimmune diseases and malignant tumors. These advancements in preclinical and clinical studies suggest that LDR-mediated immune modulation is a well-orchestrated phenomenon with clinical potential. We summarize recent developments in the understanding of LDR-mediated immune modulation, with an emphasis on its potential clinical applications.

  3. Radiation doses received in the United Kingdom breast screening programme in 2010 to 2012

    PubMed Central

    Oduko, Jennifer M

    2016-01-01

    Objectives: To review the radiation doses received by women attending the UK breast-screening programme between 2010 and 2012. To compare doses with previous years and to quantify the impact on dose of changing from analogue to digital imaging and to analyse doses by type of imaging system. Methods: Measurements of doses to samples of about 50–100 women attending for screening were collected across the whole of the UK breast-screening programme. Results: Data were collected for 87,122 exposures, using 449 X-ray sets, for 25,408 women. The average mean glandular dose (MGD) was 1.79 mGy for mediolateral oblique images and 1.58 mGy for craniocaudal images. The average MGD per two-view examination was 4.01 mGy for film-screen imaging and 3.03 mGy for direct digital radiography (DR) and 4.69 mGy for computed radiography. Conclusion: The MGD to women attending breast screening has been reduced on average by about 25% where DR systems have replaced film-screen systems. The dose reduction was greatest for breasts with the largest compressed thickness. There are large variations in dose between the different models of DR system provided by different manufacturers. There should be further work to ensure that all DR systems are operated at the optimal dose level to ensure the best cancer detection while balancing the detriment caused by using radiation. Advances in knowledge: Changes in the radiation dose in breast screening over time have been determined. Specifically, the impact on radiation dose of introducing different types of DR and computed radiography system into breast screening has been quantified. PMID:26654386

  4. Ultrasound-detected thyroid nodule prevalence and radiation dose from fallout.

    PubMed

    Land, C E; Zhumadilov, Z; Gusev, B I; Hartshorne, M H; Wiest, P W; Woodward, P W; Crooks, L A; Luckyanov, N K; Fillmore, C M; Carr, Z; Abisheva, G; Beck, H L; Bouville, A; Langer, J; Weinstock, R; Gordeev, K I; Shinkarev, S; Simon, S L

    2008-04-01

    Settlements near the Semipalatinsk Test Site (SNTS) in northeastern Kazakhstan were exposed to radioactive fallout during 1949-1962. Thyroid disease prevalence among 2994 residents of eight villages was ascertained by ultrasound screening. Malignancy was determined by cytopathology. Individual thyroid doses from external and internal radiation sources were reconstructed from fallout deposition patterns, residential histories and diet, including childhood milk consumption. Point estimates of individual external and internal dose averaged 0.04 Gy (range 0-0.65) and 0.31 Gy (0-9.6), respectively, with a Pearson correlation coefficient of 0.46. Ultrasound-detected thyroid nodule prevalence was 18% and 39% among males and females, respectively. It was significantly and independently associated with both external and internal dose, the main study finding. The estimated relative biological effectiveness of internal compared to external radiation dose was 0.33, with 95% confidence bounds of 0.09-3.11. Prevalence of papillary cancer was 0.9% and was not significantly associated with radiation dose. In terms of excess relative risk per unit dose, our dose-response findings for nodule prevalence are comparable to those from populations exposed to medical X rays and to acute radiation from the Hiroshima and Nagasaki atomic bombings.

  5. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors

    PubMed Central

    Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

    2014-01-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to 239Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation–environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. PMID:24366315

  6. Space Radiation Organ Doses for Astronauts on Past and Future Missions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2007-01-01

    We review methods and data used for determining astronaut organ dose equivalents on past space missions including Apollo, Skylab, Space Shuttle, NASA-Mir, and International Space Station (ISS). Expectations for future lunar missions are also described. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra, or a related quantity, the lineal energy (y) spectra that is measured by a tissue equivalent proportional counter (TEPC). These data are used in conjunction with space radiation transport models to project organ specific doses used in cancer and other risk projection models. Biodosimetry data from Mir, STS, and ISS missions provide an alternative estimate of organ dose equivalents based on chromosome aberrations. The physical environments inside spacecraft are currently well understood with errors in organ dose projections estimated as less than plus or minus 15%, however understanding the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons for which there are no human data to estimate risks. The accuracy of projections of organ dose equivalents described here must be supplemented with research on the health risks of space exposure to properly assess crew safety for exploration missions.

  7. Low-Dose Radiation and Genotoxic Chemicals Can Protect Against Stochastic Biological Effects

    PubMed Central

    Scott, Bobby R.; Walker, Dale M.; Walker, Vernon E.

    2004-01-01

    A protective apoptosis-mediated (PAM) process that is turned on in mammalian cells by low-dose photon (X and γ) radiation and appears to also be turned on by the genotoxic chemical ethylene oxide is discussed. Because of the PAM process, exposure to low-dose photon radiation (and possibly also some genotoxic chemicals) can lead to a reduction in the risk of stochastic effects such as problematic mutations, neoplastic transformation (an early step in cancer occurrence), and cancer. These findings indicate a need to revise the current low-dose risk assessment paradigm for which risk of cancer is presumed to increase linearly with dose (without a threshold) after exposure to any amount of a genotoxic agent such as ionizing radiation. These findings support a view seldom mentioned in the past, that cancer risk can actually decrease, rather than increase, after exposure to low doses of photon radiation and possibly some other genotoxic agents. The PAM process (a form of natural protection) may contribute substantially to cancer prevention in humans and other mammals. However, new research is needed to improve our understanding of the process. The new research could unlock novel strategies for optimizing cancer prevention and novel protocols for low-dose therapy for cancer. With low-dose cancer therapy, normal tissue could be spared from severe damage while possibly eliminating the cancer. PMID:19330143

  8. A Dose of Reality: Radiation Analysis for Realistic Human Spacecraft

    NASA Technical Reports Server (NTRS)

    Barzilla, J. E.; Lee, K. T.

    2017-01-01

    INTRODUCTION As with most computational analyses, a tradeoff exists between problem complexity, resource availability and response accuracy when modeling radiation transport from the source to a detector. The largest amount of analyst time for setting up an analysis is often spent ensuring that any simplifications made have minimal impact on the results. The vehicle shield geometry of interest is typically simplified from the original CAD design in order to reduce computation time, but this simplification requires the analyst to "re-draw" the geometry with a limited set of volumes in order to accommodate a specific radiation transport software package. The resulting low-fidelity geometry model cannot be shared with or compared to other radiation transport software packages, and the process can be error prone with increased model complexity. The work presented here demonstrates the use of the DAGMC (Direct Accelerated Geometry for Monte Carlo) Toolkit from the University of Wisconsin, to model the impacts of several space radiation sources on a CAD drawing of the US Lab module. METHODS The DAGMC toolkit workflow begins with the export of an existing CAD geometry from the native CAD to the ACIS format. The ACIS format file is then cleaned using SpaceClaim to remove small holes and component overlaps. Metadata is then assigned to the cleaned geometry file using CUBIT/Trelis from csimsoft (Registered Trademark). The DAGMC plugin script removes duplicate shared surfaces, facets the geometry to a specified tolerance, and ensures that the faceted geometry is water tight. This step also writes the material and scoring information to a standard input file format that the analyst can alter as desired prior to running the radiation transport program. The scoring results can be transformed, via python script, into a 3D format that is viewable in a standard graphics program. RESULTS The CAD model of the US Lab module of the International Space Station, inclusive of all the

  9. Radiation dose to workers due to the inhalation of dust during granite fabrication.

    PubMed

    Zwack, L M; McCarthy, W B; Stewart, J H; McCarthy, J F; Allen, J G

    2014-03-01

    There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr(-1)) and limits applicable to the general public (1 mSv yr(-1)). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m(-3) over a full year had an estimated radiation dose of 0.062 mSv yr(-1). Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr(-1) and 0.002 mSv yr(-1), respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr(-1).

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

    PubMed Central

    2012-01-01

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

  11. Quantifying the Combined Effect of Radiation Therapy and Hyperthermia in Terms of Equivalent Dose Distributions

    SciTech Connect

    Kok, H. Petra; Crezee, Johannes; Franken, Nicolaas A.P.; Barendsen, Gerrit W.

    2014-03-01

    Purpose: To develop a method to quantify the therapeutic effect of radiosensitization by hyperthermia; to this end, a numerical method was proposed to convert radiation therapy dose distributions with hyperthermia to equivalent dose distributions without hyperthermia. Methods and Materials: Clinical intensity modulated radiation therapy plans were created for 15 prostate cancer cases. To simulate a clinically relevant heterogeneous temperature distribution, hyperthermia treatment planning was performed for heating with the AMC-8 system. The temperature-dependent parameters α (Gy{sup −1}) and β (Gy{sup −2}) of the linear–quadratic model for prostate cancer were estimated from the literature. No thermal enhancement was assumed for normal tissue. The intensity modulated radiation therapy plans and temperature distributions were exported to our in-house-developed radiation therapy treatment planning system, APlan, and equivalent dose distributions without hyperthermia were calculated voxel by voxel using the linear–quadratic model. Results: The planned average tumor temperatures T90, T50, and T10 in the planning target volume were 40.5°C, 41.6°C, and 42.4°C, respectively. The planned minimum, mean, and maximum radiation therapy doses were 62.9 Gy, 76.0 Gy, and 81.0 Gy, respectively. Adding hyperthermia yielded an equivalent dose distribution with an extended 95% isodose level. The equivalent minimum, mean, and maximum doses reflecting the radiosensitization by hyperthermia were 70.3 Gy, 86.3 Gy, and 93.6 Gy, respectively, for a linear increase of α with temperature. This can be considered similar to a dose escalation with a substantial increase in tumor control probability for high-risk prostate carcinoma. Conclusion: A model to quantify the effect of combined radiation therapy and hyperthermia in terms of equivalent dose distributions was presented. This model is particularly instructive to estimate the potential effects of interaction from different

  12. The effect of different adaptation strengths on image quality and radiation dose using Siemens Care Dose 4D.

    PubMed

    Söderberg, Marcus; Gunnarsson, Mikael

    2010-01-01

    The purpose of this study was to evaluate the effect of different choices of adaptation strengths on image quality and radiation exposure to the patient with Siemens automatic exposure control system called CARE Dose 4D. An anthropomorphic chest phantom was used to simulate the patient and computed tomography scans were performed with a Siemens SOMATOM Sensation 16 and 64. Owing to adaptation strengths, a considerable reduction (26.6-51.5 % and 27.5-49.5 % for Sensation 16 and Sensation 64, respectively) in the radiation dose was found when compared with using a fixed tube current. There was a substantial difference in the image quality (image noise) between the adaptation strengths. Independent of selected adaptation strengths, the level of image noise throughout the chest phantom increased when CARE Dose 4D was used (p < 0.0001). We conclude that the adaptation strengths can be used to obtain user-specified modifications to image quality or radiation exposure to the patient.

  13. The Effect of High-Dose Ionizing Radiation on the Astrobiological Model Lichen Circinaria gyrosa

    NASA Astrophysics Data System (ADS)

    de la Torre, Rosa; Zélia Miller, Ana; Cubero, Beatriz; Martín-Cerezo, M. Luisa; Raguse, Marina; Meeßen, Joachim

    2017-02-01

    The lichen Circinaria gyrosa is an astrobiological model defined by its high capacity of resistance to space conditions and to a simulated martian environment. Therefore, it became part of the currently operated BIOMEX experiment on board the International Space Station and the recent STARLIFE campaign to study the effects of four types of space-relevant ionizing radiation. The samples were irradiated with helium and iron ions at doses up to 2 kGy, with X-rays at doses up to 5 kGy and with γ rays at doses from 6 to 113 kGy. Results on C. gyrosa's resistance to simulated space ionizing radiation and its post-irradiation viability were obtained by (i) chlorophyll a fluorescence of photosystem II (PSII), (ii) epifluorescence microscopy, (iii) confocal laser scanning microscopy (CLSM), and (iv) field emission scanning electron microscopy (FESEM). Results of photosynthetic activity and epifluorescence show no significant changes up to a dose of 1 kGy (helium ions), 2 kGy (iron ions), 5 kGy (X-rays) - the maximum doses applied for those radiation qualities - as well as a dose of 6 kGy of γ irradiation, which was the lowest dose applied for this low linear energy transfer (LET) radiation. Significant damage in a dose-related manner was observed only at much higher doses of γ irradiation (up to 113 kGy). These data corroborate the findings of the parallel STARLIFE studies on the effects of ionizing radiation on the lichen Circinaria gyrosa, its isolated photobiont, and the lichen Xanthoria elegans.

  14. Radiation retinopathy after external-beam irradiation: Analysis of time-dose factors

    SciTech Connect

    Parsons, J.T.; Bova, F.J.; Mendenhall, W.M.

    1994-11-15

    To investigate the risk of radiation-induced retinopathy according to total radiation dose and fraction size, based on both retorspective and prospectively collected data. Between October 1964 and May 1989, 68 retinae in 64 patients received fractionated external-beam irradiation during the treatment of primary extracranial head and neck tumors. All patients had a minimum of 3 years of ophthalmologic follow-up (range, 3 to 26 years; mean, 9 years; median, 8 years). Twenty-seven eyes in 26 patients developed radiation retinopathy resulting in visual acuity of 20/200 or worse. The mean and median times to the onset of symptoms attributable to retinal ischemia were 2.8 and 2.5 years, respectively. Fourteen of the injured eyes developed rubeosis iridis and/or neovascular glaucoma. Radiation retinopathy was not observed at doses below 45 Gy, but increased steadily in incidence at doses {ge}45Gy. In the range of doses between 45 and 55 Gy, there was an increased risk of injury among patients who received doses per fraction of {ge}1.9Gy (p - .09). There was also a trend toward increased risk of injury among patients who received chemotherapy (two of two vs. four of ten in the 45-51 Gy range; p - .23). The lowest dose associated with retinopathy was 45 Gy delivered to a diabetic patient by twice-a-day fractionation. The data did not suggest an increased risk of radiation retinopathy with increasing age. The current study suggests the importance of total dose as well as dose per fraction, and adds support to a small body of literature suggesting that patients with diabetes mellitus or who receive chemotherapy are at increased risk of injury. A sigmoid dose-response curve is constructed from our current data and data from the literature. 36 refs., 5 figs., 4 tabs.

  15. Rapid assessment of high-dose radiation exposures through scoring of cell-fusion-induced premature chromosome condensation and ring chromosomes.

    PubMed

    Lamadrid Boada, A I; Romero Aguilera, I; Terzoudi, G I; González Mesa, J E; Pantelias, G; García, O

    2013-09-18

    Analysis of premature chromosome condensation (PCC) mediated by fusion of G0-lymphocytes with mitotic CHO cells in combination with rapid visualization and quantification of rings (PCC-Rf) is proposed as an alternative technique for dose assessment of radiation-exposed individuals. Isolated lymphocytes or whole blood from six individuals were γ-irradiated with 5, 10, 15 and 20Gy at a dose rate of 0.5Gy/min. Following either 8- or 24-h post-exposure incubation of irradiated samples at 37°C, chromosome spreads were prepared by standard PCC cytogenetic procedures. The protocol for PCC fusion proved to be effective at doses as high as 20Gy, enabling the analysis of ring chromosomes and excess PCC fragments. The ring frequencies remained constant during the 8-24-h repair time; the pooled dose relationship between ring frequency (Y) and dose (D) was linear: Y=(0.088±0.005)×D. During the repair time, excess fragments decreased from 0.91 to 0.59 chromatid pieces per Gy, revealing the importance of information about the exact time of exposure for dose assessment on the basis of fragments. Compared with other cytogenetic assays to estimate radiation dose, the PCC-Rf method has the following benefits: a 48-h culture time is not required, allowing a much faster assessment of dose in comparison with conventional scoring of dicentrics and rings in assays for chemically-induced premature chromosome condensation (PCC-Rch), and it allows the analysis of heavily irradiated lymphocytes that are delayed or never reach mitosis, thus avoiding the problem of saturation at high doses. In conclusion, the use of the PCC fusion assay in conjunction with scoring of rings in G0-lymphocytes offers a suitable alternative for fast dose estimation following accidental exposure to high radiation doses.

  16. Analysis of radiation doses from operation of postulated commercial spent fuel transportation systems: Main report

    SciTech Connect

    Schneider, K.J.; Hostick, C.J.; Ross, W.A.; Peterson, R.W.; Smith, R.I.; Stiles, D.L.; Daling, P.M.; Weakley, S.A.; Grinde, R.B.; Young, J.R.

    1987-11-01

    This report contains a system study of estimated radiation doses to the public and workers resulting from the transport of spent fuel from commercial nuclear power reactors to a geologic repository. The report contains a detailed breakdown of activities and a description of time/distance/dose-rate estimates for each activity within the system. Collective doses are estimated for each of the major activities at the reactor site, in transit, and at the repository receiving facility. Annual individual doses to the maximally exposed individuals or groups of individuals are also estimated. A total of 17 alternatives and subalternatives to the postulated reference transportation system are identified, conceptualized, and their dose-reduction potentials and costs estimated. Resulting ratios of ..delta..cost/..delta..collective system dose for each alternative relative to the postulated reference transportation system are given. Most of the alternatives evaluated are estimated to provide both cost and dose reductions. Major reductions in transportation system dose and cost are estimated to result from using higher-capacity rail and truck casks, and particularly when replacing legalweight truck casks with ''advanced design'' overweight truck casks. The greatest annual dose reduction to the highest exposed individual workers (i.e., at the repository) is estimated to be achieved by using remote handling equipment for the cask handling operations at the repository. Additional shielding is also effective in reducing doses to both radiation workers at the reactor and repository and to transport workers. 69 refs., 36 figs., 156 tabs.

  17. Contemporary radiation doses to murine rodents inhabiting the most contaminated part of the EURT.

    PubMed

    Malinovsky, G P; Yarmoshenko, I V; Zhukovsky, M V; Starichenko, V I; Chibiryak, M V

    2014-03-01

    The contemporary radiation doses to the organs and tissues of murine rodents inhabiting the most contaminated part of the EURT were estimated. The bones of animals trapped in 2005 at territories with a surface (90)Sr contamination of 24-40 MBq/m(2) were used for dose reconstruction. The concentration of (90)Sr in the animals' skulls was measured using the nondestructive method of bone radiometry. The dose estimation procedure included application of the published values of absorbed fractions of beta-radiation energy for different combinations of source and target organs, accounting for the distribution of radionuclide by organs and tissues. Twelve conversion coefficients were obtained to link the skeleton (90)Sr concentration and doses to eleven organs and the whole body. The whole-body dose rate on the 45th day after the beginning of exposure normalised to whole-body activity is 0.015 (mGy day(-1))/(Bq g(-1)). The estimation yields the following values of doses for Microtus agrestis, Sylvaemus uralensis and Clethrionomys rutilus, respectively: maximum absorbed doses in the skeleton: 267, 121 and 160 mGy; mean whole body internal doses: 37, 14 and 23 mGy; mean internal dose rates on the last day before trapping: 1.2; 0.44 and 0.75 mGy/day. Approaches to the assessment of doses to foetuses and to offspring before weaning were also developed.

  18. Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

    SciTech Connect

    Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.; Pasa-Tolic, Ljiljana; Stenoien, David L.

    2014-07-29

    To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides with 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.

  19. Method for detecting radiation dose utilizing thermoluminescent material

    DOEpatents

    Miller, Steven D.; McDonald, Joseph C.; Eichner, Fred N.; Tomeraasen, Paul L.

    1991-01-01

    The amount of ionizing radiation to which a thermoluminescent material has been exposed is determined by first cooling the thermoluminescent material to a cryogenic temperature. The thermoluminescent material is then optically stimulated by exposure to ultraviolet light. Visible light emitted by the thermoluminescent material as it is allowed to warm up to room temperature is detected and counted. The thermoluminescent material may be annealed by exposure to ultraviolet light.

  20. Method for detecting radiation dose utilizing thermoluminescent material

    DOEpatents

    Miller, S.D.; McDonald, J.C.; Eichner, F.N.; Durham, J.S.

    1992-08-04

    The amount of ionizing radiation to which a thermoluminescent material has been exposed is determined by first cooling the thermoluminescent material and then optically stimulating the thermoluminescent material by exposure to light. Visible light emitted by the thermoluminescent material as it is allowed to warm up to room temperature is detected and counted. The thermoluminescent material may be annealed by exposure to ultraviolet light. 5 figs.

  1. Behavioral Incapacitation from a High Dose of Ionizing Radiation

    DTIC Science & Technology

    1993-11-01

    1983. (UNCLASSIFIED) SMcMillan, G., Falkenberg , S., and Thompson, WI Early behavioral effects of ionizing radiation on fou• r species pf subhuman...aspect of Os, collection of iformatlort, indudkg Suggestions for reducing ttds burden, to Wahs ton HeadQuarters Services Directoralte f r infomratlon...wiere employed at the AFRRI in 1981 when the research was completed. R . W. Young and C. G. Franz were investigators in the Behavioral Science Department

  2. Contextual Atlas Regression Forests: Multiple-Atlas-Based Automated Dose Prediction in Radiation Therapy.

    PubMed

    McIntosh, Chris; Purdie, Thomas G

    2016-04-01

    Radiation therapy is an integral part of cancer treatment, but to date it remains highly manual. Plans are created through optimization of dose volume objectives that specify intent to minimize, maximize, or achieve a prescribed dose level to clinical targets and organs. Optimization is NP-hard, requiring highly iterative and manual initialization procedures. We present a proof-of-concept for a method to automatically infer the radiation dose directly from the patient's treatment planning image based on a database of previous patients with corresponding clinical treatment plans. Our method uses regression forests augmented with density estimation over the most informative features to learn an automatic atlas-selection metric that is tailored to dose prediction. We validate our approach on 276 patients from 3 clinical treatment plan sites (whole breast, breast cavity, and prostate), with an overall dose prediction accuracies of 78.68%, 64.76%, 86.83% under the Gamma metric.

  3. Fetal radiation dose estimates for I-131 sodium iodide in cases where conception occurs after administration

    SciTech Connect

    Sparks, R.B.; Stabin, M.G.

    1999-01-01

    After administration of I-131 to the female patient, the possibility of radiation exposure of the embryo/fetus exists if the patient becomes pregnant while radioiodine remains in the body. Fetal radiation dose estimates for such cases were calculated. Doses were calculated for various maternal thyroid uptakes and time intervals between administration and conception, including euthyroid and hyperthyroid cases. The maximum fetal dose calculating was about 9.8E-03 mGy/MBq, which occurred with 100% maternal thyroid uptake and a 1 week interval between administration and conception. Placental crossover of the small amount of radioiodine remaining 90 days after conception was also considered. Such crossover could result in an additional fetal dose of 9.8E-05 mGy/MBq and a maximum fetal thyroid self dose of 3.5E-04 mGy/MBq.

  4. Missing dose from mortality studies of radiation effects among workers at Oak Ridge National Laboratory.

    PubMed

    Kerr, G D

    1994-02-01

    Missing dose is a problem that has not been adequately addressed in the mortality studies of radiation effects among workers at Oak Ridge National Laboratory. The missing dose is a result of recording a zero for below-detectable doses, especially for frequent (weekly) film badge readings. To make the thorough dosimetry assessment needed in the current Oak Ridge National Laboratory worker studies, it will probably be necessary to consider all data at hand including personnel dose records, daily pocket meter readings used to supplement weekly and quarterly readings from other dosimeters, and monitoring results from both building surveys and fixed stations. The fixed-station data should be extremely useful in developing a better understanding of the unusual temporal variation of the external radiation doses to Oak Ridge National Laboratory workers during the high exposure-rate periods of the 1950s and early 1960s.

  5. Verification of absorbed dose using diodes in cobalt-60 radiation therapy.

    PubMed

    Gadhi, Muhammad Asghar; Fatmi, Shahab; Chughtai, Gul M; Arshad, Muhammad; Shakil, Muhammad; Rahmani, Uzma Mahmood; Imran, Malik Younas; Buzdar, Saeed Ahmad

    2016-03-01

    The objective of this work was to enhance the quality and safety of dose delivery in the practice of radiation oncology. To achieve this goal, the absorbed dose verification program was initiated by using the diode in vivo dosimetry (IVD) system (for entrance and exit). This practice was implemented at BINO, Bahawalpur, Pakistan. Diodes were calibrated for making absorbed dose measurements. Various correction factors (SSD, dose non-linearity, field size, angle of incidence, and wedge) were determined for diode IVD system. The measurements were performed in phantom in order to validate the IVD procedure. One hundred and nineteen patients were monitored and 995 measurements were performed. For phantom, the percentage difference between measured and calculated dose for entrance setting remained within ±2% and for exit setting ±3%. For patient measurements, the percentage difference between measured and calculated dose remained within ±5% for entrance/open fields and ±7% for exit/wedge/oblique fields. One hundred and nineteen patients and 995 fields have been monitored during the period of 6 months. The analysis of all available measurements gave a mean percent deviation of ±1.19% and standard deviation of ±2.87%. Larger variations have been noticed in oblique, wedge and exit measurements. This investigation revealed that clinical dosimetry using diodes is simple, provides immediate results and is a useful quality assurance tool for dose delivery. It has enhanced the quality of radiation dose delivery and increased/improved the reliability of the radiation therapy practice in BINO.

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

    SciTech Connect

    Strom, Daniel J.

    2005-01-14

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

  7. Key clinical beam parameters for nanoparticle-mediated radiation dose amplification

    PubMed Central

    Detappe, Alexandre; Kunjachan, Sijumon; Drané, Pascal; Kotb, Shady; Myronakis, Marios; Biancur, Douglas E.; Ireland, Thomas; Wagar, Matthew; Lux, Francois; Tillement, Olivier; Berbeco, Ross

    2016-01-01

    As nanoparticle solutions move towards human clinical trials in radiation therapy, the influence of key clinical beam parameters on therapeutic efficacy must be considered. In this study, we have investigated the clinical radiation therapy delivery variables that may significantly affect nanoparticle-mediated radiation dose amplification. We found a benefit for situations which increased the proportion of low energy photons in the incident beam. Most notably, “unflattened” photon beams from a clinical linear accelerator results in improved outcomes relative to conventional “flat” beams. This is measured by significant DNA damage, tumor growth suppression, and overall improvement in survival in a pancreatic tumor model. These results, obtained in a clinical setting, clearly demonstrate the influence and importance of radiation therapy parameters that will impact clinical radiation dose amplification with nanoparticles. PMID:27658637

  8. Stage specificity, dose response, and doubling dose for mouse minisatellite germ-line mutation induced by acute radiation.

    PubMed

    Dubrova, Y E; Plumb, M; Brown, J; Fennelly, J; Bois, P; Goodhead, D; Jeffreys, A J

    1998-05-26

    Germ-line mutation induction at mouse minisatellite loci by acute irradiation with x-rays was studied at premeiotic and postmeiotic stages of spermatogenesis. An elevated paternal mutation rate was found after irradiation of premeiotic spermatogonia and stem cells, whereas the frequency of minisatellite mutation after postmeiotic irradiation of spermatids was similar to that in control litters. In contrast, paternal irradiation did not affect the maternal mutation rate. A linear dose-response curve for paternal mutation induced at premeiotic stages was found, with a doubling dose of 0.33 Gy, a value close to those obtained in mice after acute spermatogonia irradiation using other systems for mutation detection. High frequencies of spontaneous and induced mutations at minisatellite loci allow mutation induction to be evaluated at low doses of exposure in very small population samples, which currently makes minisatellite DNA the most powerful tool for monitoring radiation-induced germ-line mutation.

  9. Towards a comprehensive CT image segmentation for thoracic organ radiation dose estimation and reporting

    NASA Astrophysics Data System (ADS)

    Lorenz, Cristian; Ruppertshofen, Heike; Vik, Torbjörn; Prinsen, Peter; Wiegert, Jens

    2014-03-01

    Administered dose of ionizing radiation during medical imaging is an issue of increasing concern for the patient, for the clinical community, and for respective regulatory bodies. CT radiation dose is currently estimated based on a set of very simplifying assumptions which do not take the actual body geometry and organ specific doses into account. This makes it very difficult to accurately report imaging related administered dose and to track it for different organs over the life of the patient. In this paper this deficit is addressed in a two-fold way. In a first step, the absorbed radiation dose in each image voxel is estimated based on a Monte-Carlo simulation of X-ray absorption and scattering. In a second step, the image is segmented into tissue types with different radio sensitivity. In combination this allows to calculate the effective dose as a weighted sum of the individual organ doses. The main purpose of this paper is to assess the feasibility of automatic organ specific dose estimation. With respect to a commercially applicable solution and respective robustness and efficiency requirements, we investigated the effect of dose sampling rather than integration over the organ volume. We focused on the thoracic anatomy as the exemplary body region, imaged frequently by CT. For image segmentation we applied a set of available approaches which allowed us to cover the main thoracic radio-sensitive tissue types. We applied the dose estimation approach to 10 thoracic CT datasets and evaluated segmentation accuracy and administered dose and could show that organ specific dose estimation can be achieved.

  10. Pharmacological doses of daily ascorbate protect tumors from radiation damage after a single dose of radiation in an intracranial mouse glioma model.

    PubMed

    Grasso, Carole; Fabre, Marie-Sophie; Collis, Sarah V; Castro, M Leticia; Field, Cameron S; Schleich, Nanette; McConnell, Melanie J; Herst, Patries M

    2014-01-01

    Pharmacological ascorbate is currently used as an anti-cancer treatment, potentially in combination with radiation therapy, by integrative medicine practitioners. In the acidic, metal-rich tumor environment, ascorbate acts as a pro-oxidant, with a mode of action similar to that of ionizing radiation; both treatments kill cells predominantly by free radical-mediated DNA damage. The brain tumor, glioblastoma multiforme (GBM), is very resistant to radiation; radiosensitizing GBM cells will improve survival of GBM patients. Here, we demonstrate that a single fraction (6 Gy) of radiation combined with a 1 h exposure to ascorbate (5 mM) sensitized murine glioma GL261 cells to radiation in survival and colony-forming assays in vitro. In addition, we report the effect of a single fraction (4.5 Gy) of whole brain radiation combined with daily intraperitoneal injections of ascorbate (1 mg/kg) in an intracranial GL261 glioma mouse model. Tumor-bearing C57BL/6 mice were divided into four groups: one group received a single dose of 4.5 Gy to the brain 8 days after tumor implantation, a second group received daily intraperitoneal injections of ascorbate (day 8-45) after implantation, a third group received both treatments and a fourth control group received no treatment. While radiation delayed tumor progression, intraperitoneal ascorbate alone had no effect on tumor progression. Tumor progression was faster in tumor-bearing mice treated with radiation and daily ascorbate than in those treated with radiation alone. Histological analysis showed less necrosis in tumors treated with both radiation and ascorbate, consistent with a radio-protective effect of ascorbate in vivo. Discrepancies between our in vitro and in vivo results may be explained by differences in the tumor microenvironment, which determines whether ascorbate remains outside the cell, acting as a pro-oxidant, or whether it enters the cells and acts as an anti-oxidant.

  11. Low-dose total-body γ irradiation modulates immune response to acute proton radiation.

    PubMed

    Luo-Owen, Xian; Pecaut, Michael J; Rizvi, Asma; Gridley, Daila S

    2012-03-01

    Health risks due to exposure to low-dose/low-dose-rate radiation alone or when combined with acute irradiation are not yet clearly defined. This study quantified the effects of protracted exposure to low-dose/low-dose-rate γ rays with and without acute exposure to protons on the response of immune and other cell populations. C57BL/6 mice were irradiated with ⁵⁷Co (0.05 Gy at 0.025 cGy/h); subsets were subsequently exposed to high-dose/high-dose-rate proton radiation (250 MeV; 2 or 3 Gy at 0.5 Gy/min). Analyses were performed at 4 and 17 days postexposure. Spleen and thymus masses relative to body mass were decreased on day 4 after proton irradiation with or without pre-exposure to γ rays; by day 17, however, the decrease was attenuated by the priming dose. Proton dose-dependent decreases, either with or without pre-exposure to γ rays, occurred in white blood cell, lymphocyte and granulocyte counts in blood but not in spleen. A similar pattern was found for lymphocyte subpopulations, including CD3+ T, CD19+ B, CD4+ T, CD8+ T and NK1.1+ natural killer (NK) cells. Spontaneous DNA synthesis by leukocytes after proton irradiation was high in blood on day 4 and high in spleen on day 17; priming with γ radiation attenuated the effect of 3 Gy in both body compartments. Some differences were also noted among groups in erythrocyte and thrombocyte characteristics. Analysis of splenocytes activated with anti-CD3/anti-CD28 antibodies showed changes in T-helper 1 (Th1) and Th2 cytokines. Overall, the data demonstrate that pre-exposure of an intact mammal to low-dose/low-dose-rate γ rays can attenuate the response to acute exposure to proton radiation with respect to at least some cell populations.

  12. Dose-Effect Relationship in Chemoradiotherapy for Locally Advanced Rectal Cancer: A Randomized Trial Comparing Two Radiation Doses

    SciTech Connect

    Jakobsen, Anders; Ploen, John; Vuong, Te; Appelt, Ane; Lindebjerg, Jan; Rafaelsen, Soren R.

    2012-11-15

    Purpose: Locally advanced rectal cancer represents a major therapeutic challenge. Preoperative chemoradiation therapy is considered standard, but little is known about the dose-effect relationship. The present study represents a dose-escalation phase III trial comparing 2 doses of radiation. Methods and Materials: The inclusion criteria were resectable T3 and T4 tumors with a circumferential margin of {<=}5 mm on magnetic resonance imaging. The patients were randomized to receive 50.4 Gy in 28 fractions to the tumor and pelvic lymph nodes (arm A) or the same treatment supplemented with an endorectal boost given as high-dose-rate brachytherapy (10 Gy in 2 fractions; arm B). Concomitant chemotherapy, uftoral 300 mg/m{sup 2} and L-leucovorin 22.5 mg/d, was added to both arms on treatment days. The primary endpoint was complete pathologic remission. The secondary endpoints included tumor response and rate of complete resection (R0). Results: The study included 248 patients. No significant difference was found in toxicity or surgical complications between the 2 groups. Based on intention to treat, no significant difference was found in the complete pathologic remission rate between the 2 arms (18% and 18%). The rate of R0 resection was different in T3 tumors (90% and 99%; P=.03). The same applied to the rate of major response (tumor regression grade, 1+2), 29% and 44%, respectively (P=.04). Conclusions: This first randomized trial comparing 2 radiation doses indicated that the higher dose increased the rate of major response by 50% in T3 tumors. The endorectal boost is feasible, with no significant increase in toxicity or surgical complications.

  13. Radiation dose from MDCT using Monte Carlo simulations: estimating fetal dose due to pulmonary embolism scans accounting for overscan

    NASA Astrophysics Data System (ADS)

    Angel, E.; Wellnitz, C.; Goodsitt, M.; DeMarco, J.; Cagnon, C.; Ghatali, M.; Cody, D.; Stevens, D.; McCollough, C.; Primak, A.; McNitt-Gray, M.

    2007-03-01

    Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimate radiation dose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal dose estimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiation dose to the fetus.

  14. The biobehavioral and neuroimmune impact of low-dose ionizing radiation

    PubMed Central

    York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

    2011-01-01

    In the clinical setting, repeated exposures (10–30) to low-doses of ionizing radiation (≤ 200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 h and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

  15. Systematic measurements of whole-body imaging dose distributions in image-guided radiation therapy

    SciTech Connect

    Haelg, Roger A.; Besserer, Juergen; Schneider, Uwe

    2012-12-15

    Purpose: The full benefit of the increased precision of contemporary treatment techniques can only be exploited if the accuracy of the patient positioning is guaranteed. Therefore, more and more imaging modalities are used in the process of the patient setup in clinical routine of radiation therapy. The improved accuracy in patient positioning, however, results in additional dose contributions to the integral patient dose. To quantify this, absorbed dose measurements from typical imaging procedures involved in an image-guided radiation therapy treatment were measured in an anthropomorphic phantom for a complete course of treatment. The experimental setup, including the measurement positions in the phantom, was exactly the same as in a preceding study of radiotherapy stray dose measurements. This allows a direct combination of imaging dose distributions with the therapy dose distribution. Methods: Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from imaging devices used with treatment machines from the manufacturers Accuray, Elekta, Siemens, and Varian and from computed tomography scanners from GE Healthcare were determined and the resulting effective dose was calculated. The list of investigated imaging techniques consisted of cone beam computed tomography (kilo- and megavoltage), megavoltage fan beam computed tomography, kilo- and megavoltage planar imaging, planning computed tomography with and without gating methods and planar scout views. Results: A conventional 3D planning CT resulted in an effective dose additional to the treatment stray dose of less than 1 mSv outside of the treated volume, whereas a 4D planning CT resulted in a 10 times larger dose. For a daily setup of the patient with two planar kilovoltage images or with a fan beam CT at the TomoTherapy unit, an additional effective dose outside of the treated volume of less than 0.4 mSv and 1

  16. SU-E-T-636: Investigation of Dose Variation in High Dose Radiation Brachytherapy

    SciTech Connect

    Hyvarinen, M; Leventouri, T; Casey, C; Long, S; Pella, S; Dumitru, N; Herrera, R

    2014-06-15

    Purpose: The purpose of this study is to revise most of the HDR types of treatments with their applicators and their localization challenges. Since every millimeter of misplacement counts the study will look into the necessity of increasing the immobilization for several types of applicators Methods: The study took over 136 plans generated by the treatment planning system (TPS) looking into the applicator's placement in regard to the organs at risk (OR) and simulated the three possible displacements at the hottest dose point on the critical organ for several accessories to evaluate the variation of the delivered dose at the point due to the displacement. Results: Significant dose variation was obtained for the Contura, Savi, MLM and Prostate applicators. Conclusion: This study data indicates that an improvement of the immobilization devices for HDR is absolutely necessary. Better applicator fixation devices are required too. Developing new immobilization devices for all the applicators is recommended. Florida Atlantic University may provide Travel reimbursements.

  17. Issues in Low Dose Radiation Biology: The Controversy Continues. A Perspective

    SciTech Connect

    Morgan, William F.; Bair, William J.

    2013-05-01

    Both natural and man-made sources of ionizing radiation contribute to human exposure and consequently pose a risk to human health. Much of this is unavoidable, e.g., natural background radiation, and as the use of radiation in modern medicine and industry increases so does the potential health risk. This perspective reflects the author’s view of current issues in low dose radiation biology research, highlights some of the controversies therein, and suggests areas of future research to address these issues. The views expressed here are the authors own and do not represent any institution, organization or funding body.

  18. Imaging doses in radiation therapy from kilovoltage cone-beam computed tomography

    NASA Astrophysics Data System (ADS)

    Hyer, Daniel Ellis

    Advances in radiation treatment delivery, such as intensity modulated radiation therapy (IMRT), have made it possible to deliver large doses of radiation with a high degree of conformity. While highly conformal treatments offers the advantage of sparing surrounding normal tissue, this benefit can only be realized if the patient is accurately positioned during each treatment fraction. The need to accurately position the patient has led to the development and use of gantry mounted kilovoltage cone-beam computed tomography (kV-CBCT) systems. These systems are used to acquire high resolution volumetric images of the patient which are then digitally registered with the planning CT dataset to confirm alignment of the patient on the treatment table. While kV-CBCT is a very useful tool for aligning the patient prior to treatment, daily use in a high fraction therapy regimen results in a substantial radiation dose. In order to quantify the radiation dose associated with CBCT imaging, an anthropomorphic phantom representing a 50th percentile adult male and a fiber-optic coupled (FOC) dosimetry system were both constructed as part of this dissertation. These tools were then used to directly measure organ doses incurred during clinical protocols for the head, chest, and pelvis. For completeness, the dose delivered from both the X-ray Volumetric Imager (XVI, Elekta Oncology Systems, Crawley, UK) and the On-Board Imager (OBI, Varian Medical Systems, Palo Alto, CA) were investigated. While this study provided a direct measure of organ doses for estimating risk to the patient, a practical method for estimating organ doses that could be performed with phantoms and dosimeters currently available at most clinics was also desired. To accomplish this goal, a 100 mm pencil ion chamber was used to measure the "cone beam dose index" (CBDI) inside standard CT dose index (CTDI) acrylic phantoms. A weighted CBDI (CBDIw), similar to the weighted CT dose index (CTDIw), was then calculated to

  19. ORBITAL MIGRATION OF LOW-MASS PLANETS IN EVOLUTIONARY RADIATIVE MODELS: AVOIDING CATASTROPHIC INFALL

    SciTech Connect

    Lyra, Wladimir; Mac Low, Mordecai-Mark; Paardekooper, Sijme-Jan E-mail: mordecai@amnh.or

    2010-06-01

    Outward migration of low-mass planets has recently been shown to be a possibility in non-barotropic disks. We examine the consequences of this result in evolutionary models of protoplanetary disks. Planet migration occurs toward equilibrium radii with zero torque. These radii themselves migrate inwards because of viscous accretion and photoevaporation. We show that as the surface density and temperature fall the planet orbital migration and disk depletion timescales eventually become comparable, with the precise timing depending on the mass of the planet. When this occurs, the planet decouples from the equilibrium radius. At this time, however, the gas surface density is already too low to drive substantial further migration. A higher mass planet, of 10 M {sub +}, can open a gap during the late evolution of the disk, and stops migrating. Low-mass planets, with 1 or 0.1 M {sub +}, released beyond 1 AU in our models avoid migrating into the star. Our results provide support for the reduced migration rates adopted in recent planet population synthesis models.

  20. What can be learned from epidemiologic studies of persons exposed to low doses of radiation?

    SciTech Connect

    Gilbert, E.S.

    1993-04-01

    The main objective of radiation risk assessment is to determine the risk of various adverse health effects associated with exposure to low doses and low dose rates. Extrapolation of risks from studies of persons exposed at high doses (generally exceeding 1 Sv) and dose rates has been the primary approach used to achieve this objective. The study of Japanese atomic bomb survivors in Hiroshima and Nagasaki has played an especially important role in risk assessment efforts. A direct assessment of the dose-response function based on studies of persons exposed at low doses and dose rates is obviously desirable. This paper focuses on the potential of both current and future nuclear workers studies for investigating the dose-response functions at low doses, and also discusses analyses making use of the low dose portion of the atomic bomb survivor data. Difficulties in using these data are the statistical imprecision of estimated dose