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Sample records for cumulative dose-response curves

  1. Dose-response curves from incomplete data

    International Nuclear Information System (INIS)

    Groer, P.G.

    1978-01-01

    Frequently many different responses occur in populations (animal or human) exposed to ionizing radiation. To obtain a dose-response curve, the exposed population is first divided into sub-groups whose members received the same radiation dose. To estimate the response, the fraction of subjects in each sub-group that showed the particular response of interest is determined. These fractions are plotted against dose to give the dose-response curve. This procedure of plotting the fractions versus the radiation dose is not the correct way to estimate the time distribution for a particular response at the different dose levels. Other observed responses competed for the individuals in the exposed population and therefore prevented manifestation of the complete information on the response-time distribution for one specific response. Such data are called incomplete in the statistical literature. A procedure is described which uses the by now classical Kaplan-Meier estimator, to establish dose-response curves from incomplete data under the assumption that the different observed responses are statistically independent. It is demonstrated that there is insufficient information in the observed survival functions to estimate the time distribution for one particular response if the assumption of independence is dropped. In addition, it is not possible to determine from the data (i.e. type of response and when it occurred) whether or not the different response-time distributions are independent. However, it is possible to give sharp bounds between which the response has to lie. This implies that for incomplete data, only a 'dose-response band' can be established if independence of the competing responses cannot be assumed. Examples are given using actual data to illustrate the estimation procedures

  2. Single-dose-response curves of murine gastrointestinal crypt stem cells

    International Nuclear Information System (INIS)

    Masuda, K.; Withers, H.R.; Mason, K.A.; Chen, K.Y.

    1977-01-01

    Dose-response curves for the reproductive capacity of crypt stem cells of murine colonic, jejunal, and gastric mucosae exposed in situ to multifractionated gamma ray exposures were analyzed and single-dose-survival curves of these cells were constructed. The following conclusions were drawn: (1) The single-dose-response curves bend downward over a dose range of approximately 200 to 1500 rad; (2) cell death seems to be due to nonrepairable damage at doses less than 250 rad for colon, and 220 rad for jejunum; (3) there are 21, 110, and 140 stem cells per crypt of gastric, colonic, and jejunal mucosa, respectively; and (4) jejunal stem cells are the most radiosensitive and gastric mucosal stem cells are the most resistant

  3. Establishment and verification of dose-response curve of chromosomal aberrations after exposure to very high dose γ-ray

    International Nuclear Information System (INIS)

    Chen Ying; Luo Yisheng; Cao Zhenshan; Liu Xiulin

    2006-01-01

    To estimate accurately biological dose of the victims exposed to high dose, the dose-response curves of chromosome aberration induced by 6-22 Gy 60 Co γ-ray were established. Human peripheral blood in vitro was irradiated, then lymphocytes were concentrated, cultured 52h, 68h and 72h and harvested. The frequencies of dicentrics (multi-centrics) and rings were counted and compared between different culture times. The dose-response curves and equations were established, as well as verified with high dose exposure accidents. The experiment showed that the culture time should be prolonged properly after high dose exposure, and no significant differences were observed between 52-72h culture. The dose-response curve of 6-22 Gy fitted to linear-square model Y=-2.269 + 0.776D - 7.868 x 10 -3 D 2 and is reliable through verification of the accident dose estimations. In this study, the dose-response curve and equation of chromosome dic + r after 6-22 Gy high dose irradiation were established firstly, and exact dose estimation can be achieved according to it. (authors)

  4. Cytogenetics dosimetry: dose-response curve for low doses of X-ray

    International Nuclear Information System (INIS)

    Lara, Virginia E. Noval; Pineda Bolivar, William R.; Riano, Victor M. Pabon; Ureana, Cecilia Crane

    2013-01-01

    The purpose of this study was to conduct a preliminary study for the standardization in the future, the dose-response curve for low doses of X-rays, through the analysis of in vitro cultures of peripheral blood samples of 3 men and 3 women occupationally not exposed to artificial sources of ionizing radiation, age 18-40 years, where possible nonsmokers

  5. Mathematical model for evaluation of dose-rate effect on biological responses to low dose γ-radiation

    International Nuclear Information System (INIS)

    Ogata, H.; Kawakami, Y.; Magae, J.

    2003-01-01

    Full text: To evaluate quantitative dose-response relationship on the biological response to radiation, it is necessary to consider a model including cumulative dose, dose-rate and irradiation time. In this study, we measured micronucleus formation and [ 3 H] thymidine uptake in human cells as indices of biological response to gamma radiation, and analyzed mathematically and statistically the data for quantitative evaluation of radiation risk at low dose/low dose-rate. Effective dose (ED x ) was mathematically estimated by fitting a general function of logistic model to the dose-response relationship. Assuming that biological response depends on not only cumulative dose but also dose-rate and irradiation time, a multiple logistic function was applied to express the relationship of the three variables. Moreover, to estimate the effect of radiation at very low dose, we proposed a modified exponential model. From the results of fitting curves to the inhibition of [ 3 H] thymidine uptake and micronucleus formation, it was obvious that ED 50 in proportion of inhibition of [ 3 H] thymidine uptake increased with longer irradiation time. As for the micronuclei, ED 30 also increased with longer irradiation times. These results suggest that the biological response depends on not only total dose but also irradiation time. The estimated response surface using the three variables showed that the biological response declined sharply when the dose-rate was less than 0.01 Gy/h. These results suggest that the response does not depend on total cumulative dose at very low dose-rates. Further, to investigate the effect of dose-rate within a wider range, we analyzed the relationship between ED x and dose-rate. Fitted curves indicated that ED x increased sharply when dose-rate was less than 10 -2 Gy/h. The increase of ED x signifies the decline of the response or the risk and suggests that the risk approaches to 0 at infinitely low dose-rate

  6. Maximum likelihood estimation for cytogenetic dose-response curves

    International Nuclear Information System (INIS)

    Frome, E.L.; DuFrain, R.J.

    1986-01-01

    In vitro dose-response curves are used to describe the relation between chromosome aberrations and radiation dose for human lymphocytes. The lymphocytes are exposed to low-LET radiation, and the resulting dicentric chromosome aberrations follow the Poisson distribution. The expected yield depends on both the magnitude and the temporal distribution of the dose. A general dose-response model that describes this relation has been presented by Kellerer and Rossi (1972, Current Topics on Radiation Research Quarterly 8, 85-158; 1978, Radiation Research 75, 471-488) using the theory of dual radiation action. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting dose-time-response models are intrinsically nonlinear in the parameters. A general-purpose maximum likelihood estimation procedure is described, and estimation for the nonlinear models is illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure

  7. Equivalent dose determination in foraminifera: analytical description of the CO2--signal dose-response curve

    International Nuclear Information System (INIS)

    Hoffmann, D.; Woda, C.; Mangini, A.

    2003-01-01

    The dose-response of the CO 2 - signal (g=2.0006) in foraminifera with ages between 19 and 300 ka is investigated. The sum of two exponential saturation functions is an adequate function to describe the dose-response curve up to an additional dose of 8000 Gy. It yields excellent dating results but requires an artificial doses of at least 5000 Gy. For small additional doses of about 500 Gy the single exponential saturation function can be used to calculate a reliable equivalent dose D E , although it does not describ the dose-response for higher doses. The CO 2 - -signal dose-response indicates that the signal has two components of which one is less stable than the other

  8. Maximum likelihood estimation for cytogenetic dose-response curves

    International Nuclear Information System (INIS)

    Frome, E.L; DuFrain, R.J.

    1983-10-01

    In vitro dose-response curves are used to describe the relation between the yield of dicentric chromosome aberrations and radiation dose for human lymphocytes. The dicentric yields follow the Poisson distribution, and the expected yield depends on both the magnitude and the temporal distribution of the dose for low LET radiation. A general dose-response model that describes this relation has been obtained by Kellerer and Rossi using the theory of dual radiation action. The yield of elementary lesions is kappa[γd + g(t, tau)d 2 ], where t is the time and d is dose. The coefficient of the d 2 term is determined by the recovery function and the temporal mode of irradiation. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting models are intrinsically nonlinear in the parameters. A general purpose maximum likelihood estimation procedure is described and illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure

  9. Maximum likelihood estimation for cytogenetic dose-response curves

    Energy Technology Data Exchange (ETDEWEB)

    Frome, E.L; DuFrain, R.J.

    1983-10-01

    In vitro dose-response curves are used to describe the relation between the yield of dicentric chromosome aberrations and radiation dose for human lymphocytes. The dicentric yields follow the Poisson distribution, and the expected yield depends on both the magnitude and the temporal distribution of the dose for low LET radiation. A general dose-response model that describes this relation has been obtained by Kellerer and Rossi using the theory of dual radiation action. The yield of elementary lesions is kappa(..gamma..d + g(t, tau)d/sup 2/), where t is the time and d is dose. The coefficient of the d/sup 2/ term is determined by the recovery function and the temporal mode of irradiation. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting models are intrinsically nonlinear in the parameters. A general purpose maximum likelihood estimation procedure is described and illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure.

  10. Dose - Response Curves for Dicentrics and PCC Rings: Preparedness for Radiological Emergency in Thailand

    International Nuclear Information System (INIS)

    Rungsimaphorn, B.; Rerkamnuaychoke, B.; Sudprasert, W.

    2014-01-01

    Establishing in-vitro dose calibration curves is important for reconstruction of radiation dose in the exposed individuals. The aim of this pioneering work in Thailand was to generate dose-response curves using conventional biological dosimetry: dicentric chromosome assay (DCA) and premature chromosome condensation (PCC) assay. The peripheral blood lymphocytes were irradiated with 137 Cs at a dose rate of 0.652 Gy/min to doses of 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4 and 5 Gy for DCA technique, and 5, 10, 15, 20 and 25 Gy for PCC technique. The blood samples were cultured and processed following the standard procedure given by the IAEA with slight modifications. At least 500-1,000 metaphases or 100 dicentrics/ PCC rings were analyzed using an automated metaphase finder system. The yield of dicentrics with dose was fitted to a linear quadratic model using Chromosome Aberration Calculation Software (CABAS, version 2.0), whereas the dose-response curve of PCC rings was fitted to a linear relationship. These curves will be useful for in-vitro dose reconstruction and can support the preparedness for radiological emergency in the country.

  11. Dose-response curve estimation: a semiparametric mixture approach.

    Science.gov (United States)

    Yuan, Ying; Yin, Guosheng

    2011-12-01

    In the estimation of a dose-response curve, parametric models are straightforward and efficient but subject to model misspecifications; nonparametric methods are robust but less efficient. As a compromise, we propose a semiparametric approach that combines the advantages of parametric and nonparametric curve estimates. In a mixture form, our estimator takes a weighted average of the parametric and nonparametric curve estimates, in which a higher weight is assigned to the estimate with a better model fit. When the parametric model assumption holds, the semiparametric curve estimate converges to the parametric estimate and thus achieves high efficiency; when the parametric model is misspecified, the semiparametric estimate converges to the nonparametric estimate and remains consistent. We also consider an adaptive weighting scheme to allow the weight to vary according to the local fit of the models. We conduct extensive simulation studies to investigate the performance of the proposed methods and illustrate them with two real examples. © 2011, The International Biometric Society.

  12. The dose-response relationship between cumulative lifting load and lumbar disk degeneration based on magnetic resonance imaging findings.

    Science.gov (United States)

    Hung, Yu-Ju; Shih, Tiffany T-F; Chen, Bang-Bin; Hwang, Yaw-Huei; Ma, Li-Ping; Huang, Wen-Chuan; Liou, Saou-Hsing; Ho, Ing-Kang; Guo, Yue L

    2014-11-01

    Lumbar disk degeneration (LDD) has been related to heavy physical loading. However, the quantification of the exposure has been controversial, and the dose-response relationship with the LDD has not been established. The purpose of this study was to investigate the dose-response relationship between lifetime cumulative lifting load and LDD. This was a cross-sectional study. Every participant received assessments with a questionnaire, magnetic resonance imaging (MRI) of the lumbar spine, and estimation of lumbar disk compression load. The MRI assessments included assessment of disk dehydration, annulus tear, disk height narrowing, bulging, protrusion, extrusion, sequestration, degenerative and spondylolytic spondylolisthesis, foramina narrowing, and nerve root compression on each lumbar disk level. The compression load was predicted using a biomechanical software system. A total of 553 participants were recruited in this study and categorized into tertiles by cumulative lifting load (ie, lifting load. The best dose-response relationships were found at the L5-S1 disk level, in which high cumulative lifting load was associated with elevated odds ratios of 2.5 (95% confidence interval [95% CI]=1.5, 4.1) for dehydration and 4.1 (95% CI=1.9, 10.1) for disk height narrowing compared with low lifting load. Participants exposed to intermediate lifting load had an increased odds ratio of 2.1 (95% CI=1.3, 3.3) for bulging compared with low lifting load. The tests for trend were significant. There is no "gold standard" assessment tool for measuring the lumbar compression load. The results suggest a dose-response relationship between cumulative lifting load and LDD. © 2014 American Physical Therapy Association.

  13. Complex, non-monotonic dose-response curves with multiple maxima: Do we (ever) sample densely enough?

    Science.gov (United States)

    Cvrčková, Fatima; Luštinec, Jiří; Žárský, Viktor

    2015-01-01

    We usually expect the dose-response curves of biological responses to quantifiable stimuli to be simple, either monotonic or exhibiting a single maximum or minimum. Deviations are often viewed as experimental noise. However, detailed measurements in plant primary tissue cultures (stem pith explants of kale and tobacco) exposed to varying doses of sucrose, cytokinins (BA or kinetin) or auxins (IAA or NAA) revealed that growth and several biochemical parameters exhibit multiple reproducible, statistically significant maxima over a wide range of exogenous substance concentrations. This results in complex, non-monotonic dose-response curves, reminiscent of previous reports of analogous observations in both metazoan and plant systems responding to diverse pharmacological treatments. These findings suggest the existence of a hitherto neglected class of biological phenomena resulting in dose-response curves exhibiting periodic patterns of maxima and minima, whose causes remain so far uncharacterized, partly due to insufficient sampling frequency used in many studies.

  14. Validation of dose-response calibration curve for X-Ray field of CRCN-NE/CNEN: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Laís Melo; Mendonç, Julyanne Conceição de Goes; Andrade, Aida Mayra Guedes de; Hwang, Suy F.; Mendes, Mariana Esposito; Lima, Fabiana F., E-mail: falima@cnen.gov.br, E-mail: mendes_sb@hotmail.com [Centro Regional de Ciências Nucleares, (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Melo, Ana Maria M.A., E-mail: july_cgm@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Vitória de Santo Antão, PE (Brazil). Centro Acadêmico de Vitória

    2017-07-01

    It is very important in accident investigations that accurate estimating of absorbed dose takes place, so that it contributes to medical decisions and overall assessment of long-term health consequences. Analysis of chromosome aberrations is the most developed method for biological monitoring, and frequencies of dicentric chromosomes are related to absorbed dose of human peripheral blood lymphocytes using calibration curves. International Atomic Energy Agency (IAEA) recommends that each biodosimetry laboratory sets its own calibration curves, given that there are intrinsic differences in protocols and dose interpretations when using calibration curves produced in other laboratories, which could add further uncertainties to dose estimations. The Laboratory for Biological Dosimetry CRCN-NE recently completed dose-response calibration curves for X ray field. Curves of chromosomes dicentrics and dicentrics plus rings were made using Dose Estimate. This study aimed to validate the calibration curves dose-response for X ray with three irradiated samples. Blood was obtained by venipuncture from healthy volunteer and three samples were irradiated by x-rays of 250 kVp with different absorbed doses (0,5Gy, 1Gy and 2Gy). The irradiation was performed at the CRCN-NE/CNEN Metrology Service with PANTAK X-ray equipment, model HF 320. The frequency of dicentric and centric rings chromosomes were determined in 500 metaphases per sample after cultivation of lymphocytes, and staining with Giemsa 5%. Results showed that the estimated absorbed doses are included in the confidence interval of 95% of real absorbed dose. These Dose-response calibration curves (dicentrics and dicentrics plus rings) seems valid, therefore other tests will be done with different volunteers. (author)

  15. Validation of dose-response calibration curve for X-Ray field of CRCN-NE/CNEN: preliminary results

    International Nuclear Information System (INIS)

    Silva, Laís Melo; Mendonç, Julyanne Conceição de Goes; Andrade, Aida Mayra Guedes de; Hwang, Suy F.; Mendes, Mariana Esposito; Lima, Fabiana F.; Melo, Ana Maria M.A.

    2017-01-01

    It is very important in accident investigations that accurate estimating of absorbed dose takes place, so that it contributes to medical decisions and overall assessment of long-term health consequences. Analysis of chromosome aberrations is the most developed method for biological monitoring, and frequencies of dicentric chromosomes are related to absorbed dose of human peripheral blood lymphocytes using calibration curves. International Atomic Energy Agency (IAEA) recommends that each biodosimetry laboratory sets its own calibration curves, given that there are intrinsic differences in protocols and dose interpretations when using calibration curves produced in other laboratories, which could add further uncertainties to dose estimations. The Laboratory for Biological Dosimetry CRCN-NE recently completed dose-response calibration curves for X ray field. Curves of chromosomes dicentrics and dicentrics plus rings were made using Dose Estimate. This study aimed to validate the calibration curves dose-response for X ray with three irradiated samples. Blood was obtained by venipuncture from healthy volunteer and three samples were irradiated by x-rays of 250 kVp with different absorbed doses (0,5Gy, 1Gy and 2Gy). The irradiation was performed at the CRCN-NE/CNEN Metrology Service with PANTAK X-ray equipment, model HF 320. The frequency of dicentric and centric rings chromosomes were determined in 500 metaphases per sample after cultivation of lymphocytes, and staining with Giemsa 5%. Results showed that the estimated absorbed doses are included in the confidence interval of 95% of real absorbed dose. These Dose-response calibration curves (dicentrics and dicentrics plus rings) seems valid, therefore other tests will be done with different volunteers. (author)

  16. Population variability in biological adaptive responses to DNA damage and the shapes of carcinogen dose-response curves

    International Nuclear Information System (INIS)

    Conolly, Rory B.; Gaylor, David W.; Lutz, Werner K.

    2005-01-01

    Carcinogen dose-response curves for both ionizing radiation and chemicals are typically assumed to be linear at environmentally relevant doses. This assumption is used to ensure protection of the public health in the absence of relevant dose-response data. A theoretical justification for the assumption has been provided by the argument that low dose linearity is expected when an exogenous agent adds to an ongoing endogenous process. Here, we use computational modeling to evaluate (1) how two biological adaptive processes, induction of DNA repair and cell cycle checkpoint control, may affect the shapes of dose-response curves for DNA-damaging carcinogens and (2) how the resulting dose-response behaviors may vary within a population. Each model incorporating an adaptive process was capable of generating not only monotonic dose-responses but also nonmonotonic (J-shaped) and threshold responses. Monte Carlo analysis suggested that all these dose-response behaviors could coexist within a population, as the spectrum of qualitative differences arose from quantitative changes in parameter values. While this analysis is largely theoretical, it suggests that (a) accurate prediction of the qualitative form of the dose-response requires a quantitative understanding of the mechanism (b) significant uncertainty is associated with human health risk prediction in the absence of such quantitative understanding and (c) a stronger experimental and regulatory focus on biological mechanisms and interindividual variability would allow flexibility in regulatory treatment of environmental carcinogens without compromising human health

  17. Biological effects in lymphocytes irradiated with 99mTc: determination of the curve dose-response

    International Nuclear Information System (INIS)

    Oliveira, Romero Marcilio Barros Matias de

    2002-08-01

    Biological dosimetry estimates the absorbed dose taking into account changes in biological parameters. The most used biological indicator of an exposition to ionizing radiation is the quantification of chromosomal aberrations of lymphocytes from irradiated individuals. The curves of dose versus induced biological effects, obtained through bionalyses, are used in used in retrospective evaluations of the dose, mainly in the case of accidents. In this research, a simple model for electrons and photons transports was idealized to simulate the irradiation of lymphocytes with 99m Tc, representing a system used for irradiation of blood cells. The objective of the work was to establish a curve of dose versus frequencies of chromosomal aberrations in lymphocytes of human blood. For the irradiation of blood samples micro spheres of human serum of albumin (HSAM) market with 99m Tc were used, allowing the irradiation of blood with different administered activities of 99m Tc, making possible the study the cytogenetical effects as a function of such activities. The conditions of irradiation in vivo using HSAM spheres marked with 99m Tc were simulated with MCNP 4C (Monte Carlo N-Particle) code to obtain the dose-response curve. Soft tissue composition was employed to simulate blood tissue and the analyses of the curve of dose versus biological effect showed a linear quadratic response of the unstable chromosomal aberrations. As a result, the response of dose versus chromosomal aberrations of blood irradiation with 99m Tc was best fitted by the curve Y=(8,99 ±2,06) x 1- -4 + (1,24 ±0,62) x 10 -2 D + (5,67 ± 0,64) x 10 -2 D 2 . (author)

  18. Modeling and regression analysis of semiochemical dose-response curves of insect antennal reception and behavior

    Science.gov (United States)

    Dose-response curves with semiochemicals are reported in many articles in insect chemical ecology regarding neurophysiology and behavioral bioassays. Most such curves are shown in figures where the x-axis has order of magnitude increases in dosages versus responses on the y-axis represented by point...

  19. Biological dosimetry in radiological protection: dose response curves elaboration for 60Co and 137Cs

    International Nuclear Information System (INIS)

    Silva, Marcia Augusta da

    1997-01-01

    Ionizing radiation sources for pacific uses are being extensively utilized by modern society and the applications of these sources have raised the probability of the occurrence of accidents. The accidental exposition to radiation creates a necessity of the development of methods to evaluate dose quantity. This data could be obtained by the measurement of damage caused by radiation in the exposed person. The radiation dose can be estimated in exposed persons through physical methods (physical dosimetry) but the biological methods can't be dispensed, and among them, the cytogenetic one that makes use of chromosome aberrations (dicentric and centric ring) formed in peripheral blood lymphocytes (PBL) exposed to ionizing radiation. This method correlates the frequency of radioinduced aberrations with the estimated absorbed dose, as in vitro as in vivo, which is called cytogenetic dosimetry. By the introduction of improved new techniques in culture, in the interpretation of aberrations in the different analysers of slides and by the adoption of different statistical programs to analyse the data, significant differences are observed among laboratories in dose-response curves (calibration curves). The estimation of absorbed dose utilizing other laboratory calibration curves may introduce some uncertainties, so the International Atomic Energy Agency (IAEA) advises that each laboratory elaborates your own dose-response curve for cytogenetic dosimetry. The results were obtained from peripheral blood lymphocytes of the healthy and no-smoking donors exposed to 60 Co and 137 Cs radiation, with dose rate of 5 cGy.min. -1 . Six points of dose were determined 20,50,100,200,300,400 cGy and the control not irradiated. The analysed aberrations were of chromosomic type, dicentric and centric ring. The dose response curve for dicentrics were obtained by frequencies weighted in liner-quadratic mathematic model and the equation resulted were for 60 Co: Y = (3 46 +- 2.14)10 -4 cGy -1 + (3

  20. Human evidence on the shape of the dose-response curves for radiation carcinogenesis

    International Nuclear Information System (INIS)

    Burkart, W.

    1981-09-01

    The carcinogenic effects of high levels of ionizing radiation are better understood than those of any other environmental agent. However, the somatic risk from low doses is highly disputed. The uncertainties stem from the fact that a direct estimation of small risks requires impracticably large samples. Therefore, risk estimates for low doses have to be derived indirectly by extrapolation from high exposure data and are heavily dependent on assumptions about the form of the dose-response curve. Although radiobiological theories tested on in vitro systems predict a quadratic term in the dose-response equation which should, at least for sparsely ionizing radiation, dominate the shape of the curve, the epidemiological data available cannot exclude the possibility of a pure linear relationship. In some cases, apparent thresholds may result from latent periods inversely related to dose. Besides depending on the quality of the radiation, the shape seems also to differ with the type of cancer induced. Studies on uranium miners, atomic bomb survivors and on irradiated patients are reviewed with emphasis on the shape of the dose-response. The credibility of the most publicized reports claiming a large cancer risk from low levels of radiation is assessed. The feasibility of a new study in an area of high natural background is explored. Finally, the influence of the uncertainties concerning the effect of low level radiation on future exposure limits set by regulatory bodies is discussed. (Auth.)

  1. Linear dose response curves in fungi and tradescantia

    International Nuclear Information System (INIS)

    Unrau, P.

    1999-07-01

    Tradescantia Clone 02 data suggests that linear non-threshold dose responses are expected to the lowest doses and dose rates of low linear energy transfer (LET) radiation. This is likely to be true for other living organisms even though Clone 02 is radiation sensitive. It is concluded that Clone 02 is partially defective in the RAD 6 pathway for the repair of DNA interstrand cross-links (ISCL) and other loss of coding damage (LCD), based on its cross sensitivities to EMS and ionizing radiation. Tradescantia Clone 02 data showing linear non-threshold induction of somatic genetic events in part reflects the repair deficiency of this Clone. More DNA damage is repaired by recombinational mechanisms in Clone 02 than would occur in a wild-type strain. Two important classes of DNA lesions are induced by ionizing radiation in DNA - double strand breaks (DSB) which are repaired by recombination mechanisms, and loss of coding information damage (LCD), which is repaired by error prone mechanisms but may also be a substrate for recombinational repair. Based on data from yeast, there are two different repair pathways which deal with these differing lesions with different somatic genetic consequences. From yeast, yield cross sections can be derived and applied to DNA damage and repair in Tradescantia. For Clone 02, per lesion, more visible genetic events are scored than in wild-type strains. In a radiation-derived sub-clone, Clone 0106, which is more variable than Clone 02, even more events occur per lesion. This derivative clone, plus breeding experiments, indicate that Clone 02 is heterozygous, or a 'carrier' for a mutant version of a gene in the Tradescantia RAD 6 repair pathway. Clone 02 is, therefore, much like a Fanconi's anemia carrier in a human population, while the Clone 0106 derivative is much like a homozygous Fanconi's anemia patient, with respect to its response to ionizing radiation damage. Two anomalies in its dose response curves for 'pink' loss of

  2. Linear dose response curves in fungi and tradescantia

    Energy Technology Data Exchange (ETDEWEB)

    Unrau, P. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)

    1999-07-15

    Tradescantia Clone 02 data suggests that linear non-threshold dose responses are expected to the lowest doses and dose rates of low linear energy transfer (LET) radiation. This is likely to be true for other living organisms even though Clone 02 is radiation sensitive. It is concluded that Clone 02 is partially defective in the RAD 6 pathway for the repair of DNA interstrand cross-links (ISCL) and other loss of coding damage (LCD), based on its cross sensitivities to EMS and ionizing radiation. Tradescantia Clone 02 data showing linear non-threshold induction of somatic genetic events in part reflects the repair deficiency of this Clone. More DNA damage is repaired by recombinational mechanisms in Clone 02 than would occur in a wild-type strain. Two important classes of DNA lesions are induced by ionizing radiation in DNA - double strand breaks (DSB) which are repaired by recombination mechanisms, and loss of coding information damage (LCD), which is repaired by error prone mechanisms but may also be a substrate for recombinational repair. Based on data from yeast, there are two different repair pathways which deal with these differing lesions with different somatic genetic consequences. From yeast, yield cross sections can be derived and applied to DNA damage and repair in Tradescantia. For Clone 02, per lesion, more visible genetic events are scored than in wild-type strains. In a radiation-derived sub-clone, Clone 0106, which is more variable than Clone 02, even more events occur per lesion. This derivative clone, plus breeding experiments, indicate that Clone 02 is heterozygous, or a 'carrier' for a mutant version of a gene in the Tradescantia RAD 6 repair pathway. Clone 02 is, therefore, much like a Fanconi's anemia carrier in a human population, while the Clone 0106 derivative is much like a homozygous Fanconi's anemia patient, with respect to its response to ionizing radiation damage. Two anomalies in its dose response curves for &apos

  3. Mathematical modeling improves EC50 estimations from classical dose-response curves.

    Science.gov (United States)

    Nyman, Elin; Lindgren, Isa; Lövfors, William; Lundengård, Karin; Cervin, Ida; Sjöström, Theresia Arbring; Altimiras, Jordi; Cedersund, Gunnar

    2015-03-01

    The β-adrenergic response is impaired in failing hearts. When studying β-adrenergic function in vitro, the half-maximal effective concentration (EC50 ) is an important measure of ligand response. We previously measured the in vitro contraction force response of chicken heart tissue to increasing concentrations of adrenaline, and observed a decreasing response at high concentrations. The classical interpretation of such data is to assume a maximal response before the decrease, and to fit a sigmoid curve to the remaining data to determine EC50 . Instead, we have applied a mathematical modeling approach to interpret the full dose-response curve in a new way. The developed model predicts a non-steady-state caused by a short resting time between increased concentrations of agonist, which affect the dose-response characterization. Therefore, an improved estimate of EC50 may be calculated using steady-state simulations of the model. The model-based estimation of EC50 is further refined using additional time-resolved data to decrease the uncertainty of the prediction. The resulting model-based EC50 (180-525 nm) is higher than the classically interpreted EC50 (46-191 nm). Mathematical modeling thus makes it possible to re-interpret previously obtained datasets, and to make accurate estimates of EC50 even when steady-state measurements are not experimentally feasible. The mathematical models described here have been submitted to the JWS Online Cellular Systems Modelling Database, and may be accessed at http://jjj.bio.vu.nl/database/nyman. © 2015 FEBS.

  4. Cumulative radiation dose of multiple trauma patients during their hospitalization

    International Nuclear Information System (INIS)

    Wang Zhikang; Sun Jianzhong; Zhao Zudan

    2012-01-01

    Objective: To study the cumulative radiation dose of multiple trauma patients during their hospitalization and to analyze the dose influence factors. Methods: The DLP for CT and DR were retrospectively collected from the patients during June, 2009 and April, 2011 at a university affiliated hospital. The cumulative radiation doses were calculated by summing typical effective doses of the anatomic regions scanned. Results: The cumulative radiation doses of 113 patients were collected. The maximum,minimum and the mean values of cumulative effective doses were 153.3, 16.48 mSv and (52.3 ± 26.6) mSv. Conclusions: Multiple trauma patients have high cumulative radiation exposure. Therefore, the management of cumulative radiation doses should be enhanced. To establish the individualized radiation exposure archives will be helpful for the clinicians and technicians to make decision whether to image again and how to select the imaging parameters. (authors)

  5. Relationship between mutation frequency of GPA locus and cumulative dose among medical diagnostic X-ray workers

    International Nuclear Information System (INIS)

    Wang Jixian; Yu Wenru; Li Benxiao; Fan Tiqiang; Li Zhen; Gao Zhiwei; Chen Zhenjun; Zhao Yongcheng

    2000-01-01

    Objective: To explore the feasibility of using GPA locus mutation assay as a bio-dosimeter for occupational exposure to ionizing radiation. Methods: An improved technique of GPA locus mutation assay was used in th study. The frequencies of mutant RBC in peripheral blood of 55 medical X-ray workers and 50 controls employed in different calendar-year periods were detected. The relationship between mutation frequencies (MFs) and period of entry, working years and cumulative doses were analyzed. Results: The MFs were significantly elevated among X-ray workers employed before 1970. This finding is similar to the result of cancer epidemiological study among medical X-ray workers , in which the cancer risk was significantly increased only X-ray workers employed before 1970. The MFs of GPA increased with increasing cumulative dose. The dose-effect relationship of Nφ MF with cumulative dose was closer than that of NN MF. Conclusion: There are many problems to be solved for using GPA MF assay as a bio-dosimeter such as individual variation, specificity and calibration curve of dose-effect relationship

  6. Validation of dose-response curve of CRCN-NE - Regional Center for Nuclear Sciences from Northeast Brazil for 60Co: preliminary results

    International Nuclear Information System (INIS)

    Mendonca, Julyanne C.G.; Mendes, Mariana E.; Hwang, Suy F.; Lima, Fabiana F.; Santos, Neide

    2014-01-01

    The cytogenetic study has the chromosomal alterations as biomarkers in absorbed dose estimation by the body of individuals involved in exposure to ionizing radiation by interpreting a dose response calibration curve. Since the development of the technique to the analysis of data, you can see protocol characteristics, leading the International Atomic Energy Agency indicate that any laboratory with intention to carry out biological dosimetry establish their own calibration curves. The Biological Dosimetry Laboratory of the Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN), Brazil, recently established the calibration curve related to gamma radiation ( 60 Co). Thus, this work aimed to start the validation of this calibration curve from samples of three different blood donors which were irradiated with an absorbed known single dose of 1 Gy. Samples were exposed to 60 Co source (Glaucoma 220) located in the Department of Nuclear Energy (DEN/UFPE). After fixation with methanol and acetic acid and 5% Giemsa staining, the frequency of chromosomal alterations (dicentric chromosomes, acentric rings and fragments) were established from reading of 500 metaphases per sample and doses were estimated using Dose Estimate program. The results showed that, using the dose-response curve calibration for dicentrics, the dose absorbed estimated for the three individuals ranged from 0.891 - 1,089Gy, taking into account the range of confidence of 95%. By using the dose-response curve for dicentrics added to rings and for the same interval of confidence the doses ranged from 0,849 - 1,081Gy. Thus, the estimative encompassed known absorbed dose the three individuals in confidence interval of 95%. These preliminary results seems to demonstrate that dicentric dose-response curves and dicentrics plus rings established by CRCN-NE / CNEN are valid for dose estimation in exposed individuals. This validation will continue with samples from different individuals at different doses

  7. Dose-response curves for fish MFO induction: How do we interpret different maxima and slopes?

    International Nuclear Information System (INIS)

    Parrott, J.L.

    1995-01-01

    Induction of hepatic mixed function oxygenase (MFO) activity has been useful for screening effluents from pulp mills and oil refineries. Effluents and pure compounds can be assessed by direct fish exposure or by concentration with semipermeable membrane devices (SPMDs) and by measuring MFO in fish liver cell lines exposed to SPMD extracts. In these experiments, both fish and fish cells showed differences in slopes of dose-response curves, and in the maximal ethoxyresorufin-O-deethylase (EROD) activity. For example, TCDD elicits an EROD maxima of over 500 pmol/mg/min in PLHC-1 (Poeciliopsis lucida hepatocellular carcinoma cell line), while pulp mill and oil refinery effluent extracts showed maxima of 40 to 200 pmol/mg/min. Substituted phenanthrenes caused induction maxima of 100 pmol/mg/min. Similarly, in rainbow trout in vivo, TCDD and other chlorinated dioxins and furans induced up to 500 pmol/mg/min, whereas pulp mill and refinery effluents and substituted phenanthrenes produced EROD maxima of up to 100 pmol/mg/min. Differences in the slopes of dose-response curves were also common. In the current assessment of potencies, these diverse response curves are boiled-down to one number, the EC50 or other threshold-type of concentration. Comparisons of EC50s cannot express these differences and instead, ignore them. However, the authors realize there must be a better approach that takes into account these large differences in dose-response curve shape, slope and maxima. Interaction and discussions with modelers in the session will allow them to discuss various approaches to expressing the potencies of MFO inducers in fish

  8. Electiveness of photorepair, influence of dark-repair on shape of dose-response curves, and high-dose decline, in UV-induced colour mutations of Serratia

    International Nuclear Information System (INIS)

    Kaplan, R.W.

    1978-01-01

    Strain CV of Serratia marcescens mutates by UV with high frequency to 3 groups of mutants (w, h, s) differing in colour from the red wild-type. The mutational dose-response curve has a curvature corresponding to about 3 hits. It reaches a peak and declines at high doses. Inactivation curves have a broad shoulder and mostly, but not always, a break to a lesser slope at UV doses near the peak of mutations. Photo reactivation (PR) gives a dose reduction of about 2 for both inactivation and mutation including the break and peak. The dose curve with PR for w-mutations shows 1 hit-, the other types 2-hit curvature leading to a change of mutation spectrum with dose due to PR. The UV-sensitive mutant uvs21 of CV has a survival curve with a small shoulder and a long upward concavity without a break, and the mutation curve is of the one-hit type without a peak and decline. PR gives a dose reduction of 12 for inactivation and of 7.5 for mutation. The 3-hit mutation curve of CV is interpreted by assuming that 2 further hits are required to protect the 1-hit pre-mutations from being abolished by the repair lacking in uvs21. UV induction of SOS repair cannot be responsible for the 3-hit curvature because UVR of phages and induction of prophage are already saturated at rather low doses. As high-dose decline is not observed in uvs21, possibly the non-mutagenic repair lacking from uvs21 interferes with the mutation finishing processes at high doses in the repair-proficient strain CV. However, UV induction of this interference cannot be a one-hit process but requires a very large number of hits. (Auth.)

  9. Low Birth Weight, Cumulative Obesity Dose, and the Risk of Incident Type 2 Diabetes

    OpenAIRE

    Feng, Cindy; Osgood, Nathaniel D.; Dyck, Roland F.

    2018-01-01

    Background. Obesity history may provide a better understanding of the contribution of obesity to T2DM risk. Methods. 17,634 participants from the 1958 National Child Development Study were followed from birth to 50 years. Cumulative obesity dose, a measure of obesity history, was calculated by subtracting the upper cut-off of the normal BMI from the actual BMI at each follow-up and summing the areas under the obesity dose curve. Hazard ratios (HRs) for diabetes were calculated using Cox regre...

  10. A dose-response curve for biodosimetry from a 6 MV electron linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Lemos-Pinto, M.M.P.; Cadena, M.; Santos, N.; Fernandes, T.S.; Borges, E.; Amaral, A., E-mail: marcelazoo@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear

    2015-10-15

    Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates. (author)

  11. A dose-response curve for biodosimetry from a 6 MV electron linear accelerator.

    Science.gov (United States)

    Lemos-Pinto, M M P; Cadena, M; Santos, N; Fernandes, T S; Borges, E; Amaral, A

    2015-10-01

    Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates.

  12. Dose-response curve for blood exposed to gamma-neutron mixed field by conventional cytogenetic method

    International Nuclear Information System (INIS)

    Brandao, Jose Odinilson de C.; Souza, Priscilla L.G.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F.; Calixto, Merilane S.; Santos, Neide

    2009-01-01

    There is increasing concern about airline crew members (about one million worldwide) are exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed field from sources 241 AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphase figures were analyzed for the presence of dicentrics by two experienced scorers after painted by giemsa 5%. Our preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  13. Dose-response curve for blood exposed to gamma-neutron mixed field by conventional cytogenetic method

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Jose Odinilson de C.; Souza, Priscilla L.G.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F., E-mail: jodinilson@cnen.gov.b, E-mail: fflima@cnen.gov.b, E-mail: jasantos@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Calixto, Merilane S.; Santos, Neide, E-mail: santos_neide@yahoo.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Genetica

    2009-07-01

    There is increasing concern about airline crew members (about one million worldwide) are exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed field from sources {sup 241}AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphase figures were analyzed for the presence of dicentrics by two experienced scorers after painted by giemsa 5%. Our preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  14. No-threshold dose-response curves for nongenotoxic chemicals: Findings and applications for risk assessment

    International Nuclear Information System (INIS)

    Sheehan, Daniel M.

    2006-01-01

    We tested the hypothesis that no threshold exists when estradiol acts through the same mechanism as an active endogenous estrogen. A Michaelis-Menten (MM) equation accounting for response saturation, background effects, and endogenous estrogen level fit a turtle sex-reversal data set with no threshold and estimated the endogenous dose. Additionally, 31 diverse literature dose-response data sets were analyzed by adding a term for nonhormonal background; good fits were obtained but endogenous dose estimations were not significant due to low resolving power. No thresholds were observed. Data sets were plotted using a normalized MM equation; all 178 data points were accommodated on a single graph. Response rates from ∼1% to >95% were well fit. The findings contradict the threshold assumption and low-dose safety. Calculating risk and assuming additivity of effects from multiple chemicals acting through the same mechanism rather than assuming a safe dose for nonthresholded curves is appropriate

  15. Dose-Response Relationship between Cumulative Occupational Lead Exposure and the Associated Health Damages: A 20-Year Cohort Study of a Smelter in China.

    Science.gov (United States)

    Wu, Yue; Gu, Jun-Ming; Huang, Yun; Duan, Yan-Ying; Huang, Rui-Xue; Hu, Jian-An

    2016-03-16

    Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China's existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into continuous contact with lead at work for longer than 3 months. The dose-response relationship between occupational cumulative lead exposure and lead poisoning, abnormal blood lead, urinary lead and erythrocyte zinc protoporphyrin (ZPP) were analyzed and the benchmark dose lower bound confidence limits (BMDLs) were calculated. Statistically significant positive correlations were found between cumulative lead dust and lead fumes exposures and workplace seniority, blood lead, urinary lead and ZPP values. A dose-response relationship was observed between cumulative lead dust or lead fumes exposure and lead poisoning (p lead dust and fumes doses were 0.68 mg-year/m³ and 0.30 mg-year/m³ for lead poisoning, respectively. The BMDLs of workplace airborne lead concentrations associated with lead poisoning were 0.02 mg/m³ and 0.01 mg/m³ for occupational exposure lead dust and lead fume, respectively. In conclusion, BMDLs for airborne lead were lower than occupational exposure limits, suggesting that the occupational lead exposure limits need re-examination and adjustment. Occupational cumulative exposure limits (OCELs) should be established to better prevent occupational lead poisoning.

  16. Cumulative response curves to enhance interpretation of treatment differences on the Self-Esteem And Relationship questionnaire for men with erectile dysfunction.

    Science.gov (United States)

    Cappelleri, Joseph C; Zou, Kelly H; Bushmakin, Andrew G; Carlsson, Martin O; Symonds, Tara

    2013-03-01

    What's known on the subject? and What does the study add? Studies on erectile dysfunction (ED) therapies rely heavily on patient-reported outcomes (PROs) to measure efficacy on treatment response. A challenge when using PROs is interpretation of the clinical meaning of changes in scores. A responder analysis provides a threshold score to indicate whether a change in score qualifies a patient as a responder. However, a major consideration with responder analysis is the sometimes arbitrary nature of defining the threshold for a response. By contrast, cumulative response curves (CRCs) display patient response rates over a continuum of possible thresholds, thus eliminating problems with a rigid threshold definition, allowing for a variety of response thresholds to be examined simultaneously, and encompassing all data. With respect to the psychosocial factors addressed in the Self-Esteem And Relationship questionnaire in ED, CRCs clearly, distinctly, and meaningfully highlighted the favourable profiles of responses to sildenafil compared with placebo. CRCs for PROs in urology can provide a clear, transparent and meaningful visual depiction of efficacy data that can supplement and complement other analyses. To use cumulative response curves (CRCs) to enrich meaning and enhance interpretation of scores on the Self-Esteem And Relationship (SEAR) questionnaire with respect to treatment differences for men with erectile dysfunction (ED). This post hoc analysis used data from all patients who took at least one dose of study drug and had at least one post-baseline efficacy evaluation in a previously published 12-week, multicentre, randomized, double-blind, placebo-controlled trial of flexible-dose (25, 50, or 100 mg) sildenafil citrate (Viagra) in adult men with ED who had scored ≤ 75 out of 100 on the Self-Esteem subscale of the SEAR questionnaire. CRCs were used on the numeric change in transformed SEAR scores from baseline to end-of-study for each SEAR component. The

  17. Regulation of operant oral ethanol self-administration: a dose-response curve study in rats.

    Science.gov (United States)

    Carnicella, Sebastien; Yowell, Quinn V; Ron, Dorit

    2011-01-01

    Oral ethanol self-administration procedures in rats are useful preclinical tools for the evaluation of potential new pharmacotherapies as well as for the investigation into the etiology of alcohol abuse disorders and addiction. Determination of the effects of a potential treatment on a full ethanol dose-response curve should be essential to predict its clinical efficacy. Unfortunately, this approach has not been fully explored because of the aversive taste reaction to moderate to high doses of ethanol, which may interfere with consumption. In this study, we set out to determine whether a meaningful dose-response curve for oral ethanol self-administration can be obtained in rats. Long-Evans rats were trained to self-administer a 20% ethanol solution in an operant procedure following a history of excessive voluntary ethanol intake. After stabilization of ethanol self-administration, the concentration of the solution was varied from 2.5 to 60% (v/v), and operant and drinking behaviors, as well as blood ethanol concentration (BEC), were evaluated following the self-administration of a 20, 40, and 60% ethanol solution. Varying the concentration of ethanol from 2.5 to 60% after the development of excessive ethanol consumption led to a typical inverted U-shaped dose-response curve. Importantly, rats adapted their level and pattern of responding to changes in ethanol concentration to obtain a constant level of intake and BEC, suggesting that their operant behavior is mainly driven by the motivation to obtain a specific pharmacological effect of ethanol. This procedure can be a useful and straightforward tool for the evaluation of the effects of new potential pharmacotherapies for the treatment of alcohol abuse disorders. Copyright © 2010 by the Research Society on Alcoholism.

  18. Dose-Response Calculator for ArcGIS

    Science.gov (United States)

    Hanser, Steven E.; Aldridge, Cameron L.; Leu, Matthias; Nielsen, Scott E.

    2011-01-01

    The Dose-Response Calculator for ArcGIS is a tool that extends the Environmental Systems Research Institute (ESRI) ArcGIS 10 Desktop application to aid with the visualization of relationships between two raster GIS datasets. A dose-response curve is a line graph commonly used in medical research to examine the effects of different dosage rates of a drug or chemical (for example, carcinogen) on an outcome of interest (for example, cell mutations) (Russell and others, 1982). Dose-response curves have recently been used in ecological studies to examine the influence of an explanatory dose variable (for example, percentage of habitat cover, distance to disturbance) on a predicted response (for example, survival, probability of occurrence, abundance) (Aldridge and others, 2008). These dose curves have been created by calculating the predicted response value from a statistical model at different levels of the explanatory dose variable while holding values of other explanatory variables constant. Curves (plots) developed using the Dose-Response Calculator overcome the need to hold variables constant by using values extracted from the predicted response surface of a spatially explicit statistical model fit in a GIS, which include the variation of all explanatory variables, to visualize the univariate response to the dose variable. Application of the Dose-Response Calculator can be extended beyond the assessment of statistical model predictions and may be used to visualize the relationship between any two raster GIS datasets (see example in tool instructions). This tool generates tabular data for use in further exploration of dose-response relationships and a graph of the dose-response curve.

  19. The shape of the cancer mortality dose-response curve for atomic bomb survivors

    International Nuclear Information System (INIS)

    Pierce, D.A.; Vaeth, M.

    1989-10-01

    The shape of the cancer mortality dose-response in the atomic bomb survivor data is analyzed in the context of linear-quadratic (LQ) models. Results are given for all cancers except leukemia as a group, for leukemia, and for combined inferences assuming common curvature. Since there is substantial information aside from these data suggesting a dose-response concave from above, the emphasis here is not on estimating the best-fitting dose-response curve, but rather on assessing the maximal extent of curvature under LQ models which is consistent with the data. Such inferences are substantially affected by imprecision in the dose estimates, and methods are applied which make explicit allowances for biases due to this. The primary means used here to express the extent of curvature is the factor by which linear risk estimates should be divided to arrive at appropriate low-dose risk estimates. In the past, influential committees have recommended ranges of 2-10 and of 1.5-3 for such a factor. Results here suggest that values greater than about 2 are at least moderately inconsistent with these data, within the context of LQ models. It is emphasized, however, that there is little direct information in these data regarding low-dose risks; the inferences here depend strongly on the link between low-dose and high-dose risks provided by the assumption of an LQ model. (author)

  20. Clinical application of Chamomilla recutita in phlebitis: dose response curve study.

    Science.gov (United States)

    Reis, Paula Elaine Diniz Dos; Carvalho, Emilia Campos de; Bueno, Paula Carolina Pires; Bastos, Jairo Kenupp

    2011-01-01

    This experimental and dose-response curve study aimed to carry out the quality control of the Chamomilla recutita sample, as well as to estimate the ideal dose, for anti-inflammatory effect, of the extract of its capitula, in patients with phlebitis due to peripheral intravenous infusion of antineoplastic chemotherapy and to evaluate the toxicity of this extract in human beings. The therapeutic efficacy, concerning the anti-inflammatory potential, of different doses of Chamomilla recutita extract were analyzed and compared in 25 patients. The time of regression of phlebitis was shorter for groups with 2.5% concentration (mean=29.2h, standard deviation = 8.98) and 5% concentration (mean = 38.8h, standard deviation = 17.47). Local toxicity was almost not observed. This research contributes to the innovation of the nursing clinical practice, since it suggests an alternative for the treatment of phlebitis through the clinical use of phytotherapeutic drugs.

  1. Dose gradient curve: A new tool for evaluating dose gradient.

    Science.gov (United States)

    Sung, KiHoon; Choi, Young Eun

    2018-01-01

    Stereotactic radiotherapy, which delivers an ablative high radiation dose to a target volume for maximum local tumor control, requires a rapid dose fall-off outside the target volume to prevent extensive damage to nearby normal tissue. Currently, there is no tool to comprehensively evaluate the dose gradient near the target volume. We propose the dose gradient curve (DGC) as a new tool to evaluate the quality of a treatment plan with respect to the dose fall-off characteristics. The average distance between two isodose surfaces was represented by the dose gradient index (DGI) estimated by a simple equation using the volume and surface area of isodose levels. The surface area was calculated by mesh generation and surface triangulation. The DGC was defined as a plot of the DGI of each dose interval as a function of the dose. Two types of DGCs, differential and cumulative, were generated. The performance of the DGC was evaluated using stereotactic radiosurgery plans for virtual targets. Over the range of dose distributions, the dose gradient of each dose interval was well-characterized by the DGC in an easily understandable graph format. Significant changes in the DGC were observed reflecting the differences in planning situations and various prescription doses. The DGC is a rational method for visualizing the dose gradient as the average distance between two isodose surfaces; the shorter the distance, the steeper the dose gradient. By combining the DGC with the dose-volume histogram (DVH) in a single plot, the DGC can be utilized to evaluate not only the dose gradient but also the target coverage in routine clinical practice.

  2. Cumulative effective dose associated with radiography and CT of adolescents with spinal injuries.

    Science.gov (United States)

    Lemburg, Stefan P; Peters, Soeren A; Roggenland, Daniela; Nicolas, Volkmar; Heyer, Christoph M

    2010-12-01

    The purpose of this study was to analyze the quantity and distribution of cumulative effective doses in diagnostic imaging of adolescents with spinal injuries. At a level 1 trauma center from July 2003 through June 2009, imaging procedures during initial evaluation and hospitalization and after discharge of all patients 10-20 years old with spinal fractures were retrospectively analyzed. The cumulative effective doses for all imaging studies were calculated, and the doses to patients with spinal injuries who had multiple traumatic injuries were compared with the doses to patients with spinal injuries but without multiple injuries. The significance level was set at 5%. Imaging studies of 72 patients (32 with multiple injuries; average age, 17.5 years) entailed a median cumulative effective dose of 18.89 mSv. Patients with multiple injuries had a significantly higher total cumulative effective dose (29.70 versus 10.86 mSv, p cumulative effective dose to multiple injury patients during the initial evaluation (18.39 versus 2.83 mSv, p cumulative effective dose. Adolescents with spinal injuries receive a cumulative effective dose equal to that of adult trauma patients and nearly three times that of pediatric trauma patients. Areas of focus in lowering cumulative effective dose should be appropriate initial estimation of trauma severity and careful selection of CT scan parameters.

  3. Switching From Age-Based Stimulus Dosing to Dose Titration Protocols in Electroconvulsive Therapy: Empirical Evidence for Better Patient Outcomes With Lower Peak and Cumulative Energy Doses.

    Science.gov (United States)

    O'Neill-Kerr, Alex; Yassin, Anhar; Rogers, Stephen; Cornish, Janie

    2017-09-01

    The aim of this study was to test the proposition that adoption of a dose titration protocol may be associated with better patient outcomes, at lower treatment dose, and with comparable cumulative dose to that in patients treated using an age-based stimulus dosing protocol. This was an analysis of data assembled from archived records and based on cohorts of patients treated respectively on an age-based stimulus dosing protocol and on a dose titration protocol in the National Health Service in England. We demonstrated a significantly better response in the patient cohort treated with dose titration than with age-based stimulus dosing. Peak doses were less and the total cumulative dose was less in the dose titration group than in the age-based stimulus dosing group. Our findings are consistent with superior outcomes in patients treated using a dose titration protocol when compared with age-based stimulus dosing in a similar cohort of patients.

  4. Cytogenetics dosimetry: dose-response curve for low doses of X-ray; Dosimetria citogenetica: curva dosis-respuesta para bajas dosis de rayos-X

    Energy Technology Data Exchange (ETDEWEB)

    Lara, Virginia E. Noval; Pineda Bolivar, William R.; Riano, Victor M. Pabon, E-mail: venovall.15@hotmail.com, E-mail: wrpineda@misena.edu.co, E-mail: vmpabonr@udistrital.edu.co [Universidad Distrital Francisco Jose de Caldas (UD), Bogota (Colombia). Grupo de Investigacion en Ciencia y Tecnologia Nuclear; Ureana, Cecilia Crane, E-mail: cecicrane@yahoo.com [Instituto Nacional de Salud (INS), Bogota (Colombia). Laboratorio de Genetica

    2013-07-01

    The purpose of this study was to conduct a preliminary study for the standardization in the future, the dose-response curve for low doses of X-rays, through the analysis of in vitro cultures of peripheral blood samples of 3 men and 3 women occupationally not exposed to artificial sources of ionizing radiation, age 18-40 years, where possible nonsmokers.

  5. Lead in teeth from lead-dosed goats: Microdistribution and relationship to the cumulative lead dose

    International Nuclear Information System (INIS)

    Bellis, David J.; Hetter, Katherine M.; Jones, Joseph; Amarasiriwardena, Dula; Parsons, Patrick J.

    2008-01-01

    Teeth are commonly used as a biomarker of long-term lead exposure. There appear to be few data, however, on the content or distribution of lead in teeth where data on specific lead intake (dose) are also available. This study describes the analysis of a convenience sample of teeth from animals that were dosed with lead for other purposes, i.e., a proficiency testing program for blood lead. Lead concentration of whole teeth obtained from 23 animals, as determined by atomic absorption spectrometry, varied from 0.6 to 80 μg g -1 . Linear regression of whole tooth lead (μg g -1 ) on the cumulative lead dose received by the animal (g) yielded a slope of 1.2, with r 2 =0.647 (p -1 , were found in circumpulpal dentine. Linear regression of circumpulpal lead (μg g -1 ) on cumulative lead dose (g) yielded a slope of 23 with r 2 =0.961 (p=0.0001). The data indicated that whole tooth lead, and especially circumpulpal lead, of dosed goats increased linearly with cumulative lead exposure. These data suggest that circumpulpal dentine is a better biomarker of cumulative lead exposure than is whole tooth lead, at least for lead-dosed goats

  6. Cumulative Training Dose's Effects on Interrelationships Between Common Training-Load Models During Basketball Activity.

    Science.gov (United States)

    Scanlan, Aaron T; Fox, Jordan L; Borges, Nattai R; Dascombe, Ben J; Dalbo, Vincent J

    2017-02-01

    The influence of various factors on training-load (TL) responses in basketball has received limited attention. This study aimed to examine the temporal changes and influence of cumulative training dose on TL responses and interrelationships during basketball activity. Ten state-level Australian male junior basketball players completed 4 × 10-min standardized bouts of simulated basketball activity using a circuit-based protocol. Internal TL was quantified using the session rating of perceived exertion (sRPE), summated heart-rate zones (SHRZ), Banister training impulse (TRIMP), and Lucia TRIMP models. External TL was assessed via measurement of mean sprint and circuit speeds. Temporal TL comparisons were performed between 10-min bouts, while Pearson correlation analyses were conducted across cumulative training doses (0-10, 0-20, 0-30, and 0-40 min). sRPE TL increased (P basketball activity. sRPE TL was only significantly related to Lucia TRIMP (r = .66-.69; P basketball training doses lasting beyond 20 min. Thus, the interchangeability of commonly used internal and external TL approaches appears dose-dependent during basketball activity, with various psychophysiological mediators likely underpinning temporal changes.

  7. Age- and gender-specific estimates of cumulative CT dose over 5 years using real radiation dose tracking data in children

    International Nuclear Information System (INIS)

    Lee, Eunsol; Goo, Hyun Woo; Lee, Jae-Yeong

    2015-01-01

    It is necessary to develop a mechanism to estimate and analyze cumulative radiation risks from multiple CT exams in various clinical scenarios in children. To identify major contributors to high cumulative CT dose estimates using actual dose-length product values collected for 5 years in children. Between August 2006 and July 2011 we reviewed 26,937 CT exams in 13,803 children. Among them, we included 931 children (median age 3.5 years, age range 0 days-15 years; M:F = 533:398) who had 5,339 CT exams. Each child underwent at least three CT scans and had accessible radiation dose reports. Dose-length product values were automatically extracted from DICOM files and we used recently updated conversion factors for age, gender, anatomical region and tube voltage to estimate CT radiation dose. We tracked the calculated CT dose estimates to obtain a 5-year cumulative value for each child. The study population was divided into three groups according to the cumulative CT dose estimates: high, ≥30 mSv; moderate, 10-30 mSv; and low, <10 mSv. We reviewed clinical data and CT protocols to identify major contributors to high and moderate cumulative CT dose estimates. Median cumulative CT dose estimate was 5.4 mSv (range 0.5-71.1 mSv), and median number of CT scans was 4 (range 3-36). High cumulative CT dose estimates were most common in children with malignant tumors (57.9%, 11/19). High frequency of CT scans was attributed to high cumulative CT dose estimates in children with ventriculoperitoneal shunt (35 in 1 child) and malignant tumors (range 18-49). Moreover, high-dose CT protocols, such as multiphase abdomen CT (median 4.7 mSv) contributed to high cumulative CT dose estimates even in children with a low number of CT scans. Disease group, number of CT scans, and high-dose CT protocols are major contributors to higher cumulative CT dose estimates in children. (orig.)

  8. Insect radiosensitivity: dose curves and dose-fractionation studies of dominant lethal mutations in the mature sperm of 4 insect species

    International Nuclear Information System (INIS)

    LaChance, L.E.; Graham, C.K.

    1984-01-01

    Males of 4 species of insects: Musca domestica L. (housefly) (Diptera), Oncopeltus fasciatus (Dallas) (milkweed bug) (Hemiptera), Anagasta kuhniella (Zeller) (mealmoth) (Lepidoptera) and Heliothis virescens (Fab.) (tobacco budworm) (Lepidoptera) were irradiated as adults. Dose-response curves for the induction of dominant lethal mutations in the mature sperm were constructed. The curves were analyzed mathematically and compared with theoretical computer simulated curves requiring 1, 2, 4, 8 and 16 'hits' for the induction of a dominant lethal mutation. The 4 species belonging to 3 different orders of insects showed a wide range in radiation sensitivity and vastly different dose-response curves. When the data were analyzed by several mathematical models the authors found that a logistic response curve gave reasonably good fit with vastly different parameters for the 4 species. Dose-fractionation experiments showed no reduction in the frequency of lethal mutations induced in any species when an acute dose was fractionated into 2 equal exposures separated by an 8-h period. (Auth.)

  9. SU-E-T-96: Energy Dependence of the New GafChromic- EBT3 Film's Dose Response-Curve.

    Science.gov (United States)

    Chiu-Tsao, S; Massillon-Jl, G; Domingo-Muñoz, I; Chan, M

    2012-06-01

    To study and compare the dose response curves of the new GafChromic EBT3 film for megavoltage and kilovoltage x-ray beams, with different spatial resolution. Two sets of EBT3 films (lot#A101711-02) were exposed to each x-ray beam (6MV, 15MV and 50kV) at 8 dose values (50-3200cGy). The megavoltage beams were calibrated per AAPM TG-51 protocol while the kilovoltage beam was calibrated following the TG-61 using an ionization chamber calibrated at NIST. Each film piece was scanned three consecutive times in the center of Epson 10000XL flatbed scanner in transmission mode, landscape orientation, 48-bit color at two separate spatial resolutions of 75 and 300 dpi. The data were analyzed using ImageJ and, for each scanned image, a region of interest (ROI) of 2×2cm 2 at the field center was selected to obtain the mean pixel value with its standard deviation in the ROI. For each energy, dose value and spatial resolution, the average netOD and its associated uncertainty were determined. The Student's t-test was performed to evaluate the statistical differences between the netOD/dose values of the three energy modalities, with different color channels and spatial resolutions. The dose response curves for the three energy modalities were compared in three color channels with 75 and 300dpi. Weak energy dependence was found. For doses above 100cGy, no statistical differences were observed between 6 and 15MV beams, regardless of spatial resolution. However, statistical differences were observed between 50kV and the megavoltage beams. The degree of energy dependence (from MV to 50kV) was found to be function of color channel, dose level and spatial resolution. The dose response curves for GafChromic EBT3 films were found to be weakly dependent on the energy of the photon beams from 6MV to 50kV. The degree of energy dependence varies with color channel, dose and spatial resolution. GafChromic EBT3 films were supplied by Ashland Corp. This work was partially supported by DGAPA

  10. Evaluation of rate of unstable chromosomal changes in human blood irradiated by X-rays: establishment of dose-response curve

    International Nuclear Information System (INIS)

    Mendonça, J.C.G.; Mendes, M.E.; Melo, A.M.M.A.; Silva, L.M.; Andrade, A.M.G.; Hwang, S.F.; Lima, F.F.

    2017-01-01

    Since the discovery of ionizing radiation, and consequently of its properties, there has been an increasing in its use, which in turn has raised concerns about the biological damage that it could cause in exposed individuals. As a result, cytogenetic dosimetry has emerged: a method that can be used as a complement or, in the absence of physical dosimetry, relating the frequency of chromosomal changes found in the blood of the exposed individual and the dose absorbed through dose-response calibration curves. This work aimed to verify the frequencies of the unstable chromosomal changes in human blood lymphocytes irradiated by X-rays of 250 kVp with different absorbed doses and later establish the dose-response calibration curves. The irradiation was performed at the CRCN-NE/CNEN-PE, Brazil metrology service on a PANTAK X-ray machine, model HF 320. The blood samples had their lymphocytes cultured in culture media and, after the processing, the metaphases were obtained. The chromosomal alterations analyzed were chromosomes dicentric, ring and isolated actinic fragments. There was an increase in frequencies of all chromosomal changes with increased absorbed dose. The calibration curves of dicentric and dicentric + rings presented good adjustments with the values of the coefficients Y = 0.0013 + 0.0271D + 0.0556D 2 (X 2 = 10.36 / GL = 6) and Y = 0.0013 + 0.0263D + 0.0640D 2 (X 2 = 7.43 / GL = 6), respectively. The establishment of these curves enables the Laboratory of Biological Dosimetry of the CRCN/NE/CNEN-PE to estimate the dose absorbed by occupationally exposed individuals and in cases of radiological accidents

  11. Validation of dose-response curve of CRCN-NE - Regional Center for Nuclear Sciences from Northeast Brazil for {sup 60}Co: preliminary results; Validacao da curva dose-resposta do CRCN-NE para {sup 60}Co: resultados preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Julyanne C.G.; Mendes, Mariana E.; Hwang, Suy F.; Lima, Fabiana F. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Santos, Neide, E-mail: july_cgm@yahoo.com.br [Universidade Federal de Pernambuco (CCB/UFPE), Recife, PE (Brazil). Departamento de Genetica

    2014-07-01

    The cytogenetic study has the chromosomal alterations as biomarkers in absorbed dose estimation by the body of individuals involved in exposure to ionizing radiation by interpreting a dose response calibration curve. Since the development of the technique to the analysis of data, you can see protocol characteristics, leading the International Atomic Energy Agency indicate that any laboratory with intention to carry out biological dosimetry establish their own calibration curves. The Biological Dosimetry Laboratory of the Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN), Brazil, recently established the calibration curve related to gamma radiation ({sup 60}Co). Thus, this work aimed to start the validation of this calibration curve from samples of three different blood donors which were irradiated with an absorbed known single dose of 1 Gy. Samples were exposed to {sup 60}Co source (Glaucoma 220) located in the Department of Nuclear Energy (DEN/UFPE). After fixation with methanol and acetic acid and 5% Giemsa staining, the frequency of chromosomal alterations (dicentric chromosomes, acentric rings and fragments) were established from reading of 500 metaphases per sample and doses were estimated using Dose Estimate program. The results showed that, using the dose-response curve calibration for dicentrics, the dose absorbed estimated for the three individuals ranged from 0.891 - 1,089Gy, taking into account the range of confidence of 95%. By using the dose-response curve for dicentrics added to rings and for the same interval of confidence the doses ranged from 0,849 - 1,081Gy. Thus, the estimative encompassed known absorbed dose the three individuals in confidence interval of 95%. These preliminary results seems to demonstrate that dicentric dose-response curves and dicentrics plus rings established by CRCN-NE / CNEN are valid for dose estimation in exposed individuals. This validation will continue with samples from different individuals at different doses.

  12. Dose-response calibration curves of {sup 137}Cs gamma rays for dicentric chromosome aberrations in human lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wol Soon; Oh, Su Jung; Jeong, Soo Kyun; Yang, Kwang Mo [Dept. of Research center, Dong Nam Institute of Radiological and Medical Sciences, Busan (Korea, Republic of); Jeong, Min Ho [Dept. of Microbiology, Dong A University College of Medicine, Busan (Korea, Republic of)

    2012-11-15

    Recently, the increased threat of radiologically industrial accident such as radiation nondestructive inspection or destruction of nuclear accident by natural disaster such as Fukushima accident requires a greater capacity for cytogenetic biodosimetry, which is critical for clinical triage of potentially thousands of radiation-exposed individuals. Dicentric chromosome aberration analysis is the conventional means of assessing radiation exposure. Dose–response calibration curves for {sup 13}'7Cs gamma rays have been established for unstable chromosome aberrations in human peripheral blood lymphocytes in many laboratories of international biodosimetry network. In this study, therefore, we established dose– response calibration curves of our laboratory for {sup 137}Cs gamma raysaccording to the IAEA protocols for conducting the dicentric chromosome assay We established in vitro dose–response calibration curves for dicentric chromosome aberrations in human lymphocytes for{sup 13}'7Cs gamma rays in the 0 to 5 Gy range, using the maximum likelihood linear-quadratic model, Y = c+αD+βD2. The estimated coefficients of the fitted curves were within the 95% confidence intervals (CIs) and the curve fitting of dose–effect relationship data indicated a good fit to the linear-quadratic model. Hence, meaningful dose estimation from unknown sample can be determined accurately by using our laboratory’s calibration curve according to standard protocol.

  13. The association between cumulative adversity and mental health: considering dose and primary focus of adversity.

    Science.gov (United States)

    Keinan, Giora; Shrira, Amit; Shmotkin, Dov

    2012-09-01

    The study addressed the dose-response model in the association of cumulative adversity with mental health. Data of 1,725 participants aged 50+ were drawn from the Israeli component of the Survey of Health, Ageing, and Retirement in Europe. Measures included an inventory of potentially traumatic events, distress (lifetime depression, depressive symptoms), and well-being (quality of life, optimism/hope). The maximal effect of cumulative trauma emerged in the contrast between 0-2 and 3+ events, where the higher number of events related to higher distress but also to higher well-being. While self-oriented adversity revealed no, or negative, association with well-being, other-oriented adversity revealed a positive association. The study suggests an experiential dose of cumulative adversity leading to a co-activation of distress and well-being. The source of this co-activation seems to be other-oriented adversity.

  14. Risk of therapy-related leukaemia and preleukaemia after Hodgkin's disease. Relation to age, cumulative dose of alkylating agents, and time from chemotherapy

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, J.; Specht, L.; Larsen, S.O.

    1987-01-01

    391 patients treated intensively for Hodgkin's disease were followed for up to 15 years to evaluate the risk of therapy-related acute non-lymphocytic leukaemia (t-ANLL) and preleukaemia. Only two independent factors, patient age and cumulative dose of alkylating agents, were related to the risk...... of t-ANLL. The hazard rate of t-ANLL was roughly proportional to the square of patient age and to the total cumulative dose of alkylating agents. In 320 patients treated with alkylating agents the cumulative risk of t-ANLL increased steadily from 1 year after the start of treatment and reached 13.......0% (SE 3.0) at 10 years after which time there were no further cases. Calculated from cessation of therapy with alkylating agents, however, the cumulative risk curve increased steeply during the first 1-2 years then gradually levelled out and no new cases were observed beyond 7 years. With a 15-year...

  15. Biological effects in lymphocytes irradiated with {sup 99m}Tc: determination of the curve dose-response; Efeitos biologicos em linfocitos irradiados com {sup 99m}Tc: determinacao da curva dose-resposta

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Romero Marcilio Barros Matias de

    2002-08-01

    Biological dosimetry estimates the absorbed dose taking into account changes in biological parameters. The most used biological indicator of an exposition to ionizing radiation is the quantification of chromosomal aberrations of lymphocytes from irradiated individuals. The curves of dose versus induced biological effects, obtained through bionalyses, are used in used in retrospective evaluations of the dose, mainly in the case of accidents. In this research, a simple model for electrons and photons transports was idealized to simulate the irradiation of lymphocytes with {sup 99m} Tc, representing a system used for irradiation of blood cells. The objective of the work was to establish a curve of dose versus frequencies of chromosomal aberrations in lymphocytes of human blood. For the irradiation of blood samples micro spheres of human serum of albumin (HSAM) market with {sup 99m} Tc were used, allowing the irradiation of blood with different administered activities of {sup 99m} Tc, making possible the study the cytogenetical effects as a function of such activities. The conditions of irradiation in vivo using HSAM spheres marked with {sup 99m} Tc were simulated with MCNP 4C (Monte Carlo N-Particle) code to obtain the dose-response curve. Soft tissue composition was employed to simulate blood tissue and the analyses of the curve of dose versus biological effect showed a linear quadratic response of the unstable chromosomal aberrations. As a result, the response of dose versus chromosomal aberrations of blood irradiation with {sup 99m} Tc was best fitted by the curve Y=(8,99 {+-}2,06) x 1-{sup -4} + (1,24 {+-}0,62) x 10{sup -2} D + (5,67 {+-} 0,64) x 10{sup -2} D{sup 2}. (author)

  16. A dose-surviving fraction curve for mouse colonic mucosa

    International Nuclear Information System (INIS)

    Tucker, S.L.; Thames, H.D. Jr.; Withers, H.R.; Mason, K.A.

    1983-01-01

    A dose-surviving fraction curve representing the response of the mouse colonic mucosa to single doses of 137 Cs gamma radiation was obtained from the results of a multifraction in vivo colony assay. Construction of the curve required an estimated of the average number of clonogens initially present per colonic crypt. The estimated clonogen count (88) was determined by a statistical method based on the use of doses per fraction common to different fractionation protocols. Parameters for the LQ and TC models of cell survival were obtained by weighted least-squares fits to the data. A comparison of the survival characteristics of cells from the mouse colonic and jejunal crypts suggested that the epithelium of the colon is less radiosensitive than that of the jejunum. (author)

  17. Cumulative doses analysis in young trauma patients: a single-centre experience.

    Science.gov (United States)

    Salerno, Sergio; Marrale, Maurizio; Geraci, Claudia; Caruso, Giuseppe; Lo Re, Giuseppe; Lo Casto, Antonio; Midiri, Massimo

    2016-02-01

    Multidetector computed tomography (MDCT) represents the main source of radiation exposure in trauma patients. The radiation exposure of young patients is a matter of considerable medical concern due to possible long-term effects. Multiple MDCT studies have been observed in the young trauma population with an increase in radiation exposure. We have identified 249 young adult patients (178 men and 71 women; age range 14-40 years) who had received more than one MDCT study between June 2010 and June 2014. According to the International Commission on Radiological Protection publication, we have calculated the cumulative organ dose tissue-weighting factors by using CT-EXPO software(®). We have observed a mean cumulative dose of about 27 mSv (range from 3 to 297 mSv). The distribution analysis is characterised by low effective dose, below 20 mSv, in the majority of the patients. However, in 29 patients, the effective dose was found to be higher than 20 mSv. Dose distribution for the various organs analysed (breasts, ovaries, testicles, heart and eye lenses) shows an intense peak for lower doses, but in some cases high doses were recorded. Even though cumulative doses may have long-term effects, which are still under debate, high doses are observed in this specific group of young patients.

  18. Calibration curve to establish the exposure dose at Co60 gamma radiation

    International Nuclear Information System (INIS)

    Guerrero C, C.; Brena V, M.

    2000-01-01

    The biological dosimetry is an adequate method for the dose determination in cases of overexposure to ionizing radiation or doubt of the dose obtained by physical methods. It is based in the aberrations analysis produced in the chromosomes. The behavior of leisure in chromosomes is of dose-response type and it has been generated curves in distinct laboratories. Next is presented the curve for gamma radiation produced in the National Institute of Nuclear Research (ININ) laboratory. (Author)

  19. The cumulative ash curve: a best tool to evaluate complete mill performance.

    Science.gov (United States)

    Sakhare, Suresh D; Inamdar, Aashitosh A

    2014-04-01

    Slick test is carried out by a flour miller to qualitatively segregate the flour from different streams in a roller flour mill. This test is done manually by pressing flour samples on tray using thin bladed paddle (the slick) and inspecting color or dress of the sample. However, the test is subjective and totally depends on human judgment. Cumulative ash curve relates to cumulative flour ash content and cumulative flour yield, which could help a flour miller to be more precise while selecting flour streams for different needs. In this study, cleaning and conditioning of wheat was carried out in the pilot plant of International School of Milling Technology (ISMT). Further, roller flour milling of wheat was done. Flour from different streams (four breaks, five reductions) was collected. Each flour stream was analyzed for ash content using standard AACC methods. The analytical values of ash content were used to plot the cumulative ash curve. It was found that ash content increased in the break passages from first to last break, with exception of first break (ash content 0.71%). An increase in percentage of ash was observed in the reduction passages (C1 to C5), however, C3 ash (0.76%) was slightly higher than that of C4 (0.65%). Higher yield of flour with minimum ash content was obtained from the front reduction passages C1 and C2; whereas, the break passages and the tail end reduction passages produce less flour with higher ash content.

  20. Evaluation of a post-analysis method for cumulative dose distribution in stereotactic body radiotherapy

    International Nuclear Information System (INIS)

    Imae, Toshikazu; Takenaka, Shigeharu; Saotome, Naoya

    2016-01-01

    The purpose of this study was to evaluate a post-analysis method for cumulative dose distribution in stereotactic body radiotherapy (SBRT) using volumetric modulated arc therapy (VMAT). VMAT is capable of acquiring respiratory signals derived from projection images and machine parameters based on machine logs during VMAT delivery. Dose distributions were reconstructed from the respiratory signals and machine parameters in the condition where respiratory signals were without division, divided into 4 and 10 phases. The dose distribution of each respiratory phase was calculated on the planned four-dimensional CT (4DCT). Summation of the dose distributions was carried out using deformable image registration (DIR), and cumulative dose distributions were compared with those of the corresponding plans. Without division, dose differences between cumulative distribution and plan were not significant. In the condition Where respiratory signals were divided, dose differences were observed over dose in cranial region and under dose in caudal region of planning target volume (PTV). Differences between 4 and 10 phases were not significant. The present method Was feasible for evaluating cumulative dose distribution in VMAT-SBRT using 4DCT and DIR. (author)

  1. Technical Note: SCUDA: A software platform for cumulative dose assessment

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seyoun; McNutt, Todd; Quon, Harry; Wong, John; Lee, Junghoon, E-mail: rshekhar@childrensnational.org, E-mail: junghoon@jhu.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, Maryland 21231 (United States); Plishker, William [IGI Technologies, Inc., College Park, Maryland 20742 (United States); Shekhar, Raj, E-mail: rshekhar@childrensnational.org, E-mail: junghoon@jhu.edu [IGI Technologies, Inc., College Park, Maryland 20742 and Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010 (United States)

    2016-10-15

    Purpose: Accurate tracking of anatomical changes and computation of actually delivered dose to the patient are critical for successful adaptive radiation therapy (ART). Additionally, efficient data management and fast processing are practically important for the adoption in clinic as ART involves a large amount of image and treatment data. The purpose of this study was to develop an accurate and efficient Software platform for CUmulative Dose Assessment (SCUDA) that can be seamlessly integrated into the clinical workflow. Methods: SCUDA consists of deformable image registration (DIR), segmentation, dose computation modules, and a graphical user interface. It is connected to our image PACS and radiotherapy informatics databases from which it automatically queries/retrieves patient images, radiotherapy plan, beam data, and daily treatment information, thus providing an efficient and unified workflow. For accurate registration of the planning CT and daily CBCTs, the authors iteratively correct CBCT intensities by matching local intensity histograms during the DIR process. Contours of the target tumor and critical structures are then propagated from the planning CT to daily CBCTs using the computed deformations. The actual delivered daily dose is computed using the registered CT and patient setup information by a superposition/convolution algorithm, and accumulated using the computed deformation fields. Both DIR and dose computation modules are accelerated by a graphics processing unit. Results: The cumulative dose computation process has been validated on 30 head and neck (HN) cancer cases, showing 3.5 ± 5.0 Gy (mean±STD) absolute mean dose differences between the planned and the actually delivered doses in the parotid glands. On average, DIR, dose computation, and segmentation take 20 s/fraction and 17 min for a 35-fraction treatment including additional computation for dose accumulation. Conclusions: The authors developed a unified software platform that provides

  2. Cumulative effective and individual organ dose levels in paediatric patients undergoing multiple catheterizations for congenital heart disease

    International Nuclear Information System (INIS)

    Jones, T.P.; Brennan, P.C.; Ryan, E.

    2017-01-01

    This study examines the cumulative radiation dose levels received by a group of children who underwent multiple cardiac catheterisation procedures during the investigation and management of congenital heart disease (CHD). The purpose is to calculate cumulative doses, identify higher dose individuals, outline the inconsistencies with risk assessment and encourage the establishment of dose databases in order to facilitate the longitudinal research necessary to better understand health risks. A retrospective review of patient records for 117 paediatric patients who have undergone two or more cardiac catheterizations for the investigation of CHD was undertaken. This cohort consisted of patients who were catheterised over a period from September 2002 to August 2014. The age distribution was from newborn to 17 y. Archived kerma-area product (P KA ) and fluoroscopy time (T) readings were retrieved and analysed. Cumulative effective and individual organ doses were determined. The cumulative P KA levels ranged from 1.8 to 651.2 Gycm 2 , whilst cumulative effective dose levels varied from 2 to 259 mSv. The cumulative fluoroscopy time was shown to vary from 8.1 to 193.5 min. Median cumulative organ doses ranged from 3 to 94 mGy. Cumulative effective dose levels are highly variable but may exceed 250 mSv. Individual organ and effective dose measurements remain useful for comparison purposes between institutions although current methodologies used for determining lifetime risks are inadequate. (authors)

  3. Quantitative radiation dose-response relationships for normal tissues in man. II. Response of the salivary glands during radiotherapy

    International Nuclear Information System (INIS)

    Mossman, K.L.

    1983-01-01

    A quantitative dose-response curve for salivary gland function in patients during radiotherapy is presented. Salivary-function data used in this study were obtained from four previously published reports. All patients were treated with 60 Co teletherapy to the head and neck using conventional treatment techniques. Salivary dysfunction was determined at specific dose levels by comparing salivary flow rates before therapy with flow rates at specific dose intervals during radiotherapy up to a total dose of 6000 cGy. Fifty percent salivary dysfunction occurred after 1000 cGy and eighty percent dysfunction was observed by the end of the therapy course (6000 cGy). The salivary-function curve was also compared to the previously published dose-response curve for taste function. Comparisons of the two curves indicate that salivary dysfunction precedes taste loss and that the shapes of the dose-response curves are different. A new term, tissue tolerance ratio, defined as the ratio of responses of two tissues given the same radiation dose, was used to make the comparisons between gustatory and salivary gland tissue effects. Measurements of salivary gland function and analysis of dose-response curves may be useful in evaluating chemical modifiers of radiation response

  4. Application of the ELDO approach to assess cumulative eye lens doses for interventional cardiologists

    International Nuclear Information System (INIS)

    Farah, J.; Jacob, S.; Clairand, I.; Struelens, L.; Vanhavere, F.; Auvinen, A.; Koukorava, C.; Schnelzer, M.

    2015-01-01

    In preparation of a large European epidemiological study on the relation between eye lens dose and the occurrence of lens opacities, the European ELDO project focused on the development of practical methods to estimate retrospectively cumulative eye lens dose for interventional medical professionals exposed to radiation. The present paper applies one of the ELDO approaches, correlating eye lens dose to whole-body doses, to assess cumulative eye lens dose for 14 different Finnish interventional cardiologists for whom annual whole-body dose records were available for their entire working period. The estimated cumulative left and right eye lens dose ranged from 8 to 264 mSv and 6 to 225 mSv, respectively. In addition, calculations showed annual eye lens doses sometimes exceeding the new ICRP annual limit of 20 mSv. The work also highlights the large uncertainties associated with the application of such an approach proving the need for dedicated dosimetry systems in the routine monitoring of the eye lens dose. (authors)

  5. Interpretation of the margin of exposure for genotoxic carcinogens - elicitation of expert knowledge about the form of the dose response curve at human relevant exposures.

    Science.gov (United States)

    Boobis, Alan; Flari, Villie; Gosling, John Paul; Hart, Andy; Craig, Peter; Rushton, Lesley; Idahosa-Taylor, Ehi

    2013-07-01

    The general approach to risk assessment of genotoxic carcinogens has been to advise reduction of exposure to "as low as reasonably achievable/practicable" (ALARA/P). However, whilst this remains the preferred risk management option, it does not provide guidance on the urgency or extent of risk management actions necessary. To address this, the "Margin of Exposure" (MOE) approach has been proposed. The MOE is the ratio between the point of departure for carcinogenesis and estimated human exposure. However, interpretation of the MOE requires implicit or explicit consideration of the shape of the dose-response curve at human relevant exposures. In a structured elicitation exercise, we captured expert opinion on available scientific evidence for low dose-response relationships for genotoxic carcinogens. This allowed assessment of: available evidence for the nature of dose-response relationships at human relevant exposures; the generality of judgments about such dose-response relationships; uncertainties affecting judgments on the nature of such dose-response relationships; and whether this last should differ for different classes of genotoxic carcinogens. Elicitation results reflected the variability in experts' views on the form of the dose-response curve for low dose exposure and major sources of uncertainty affecting the assumption of a linear relationship. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Similarity criterion analysis of dose-response curves in biological assay and radioimmunoassay of hormones

    International Nuclear Information System (INIS)

    Cristakou, H.D.

    1983-01-01

    The difficulties involved in the control of biological and radioimmunological assay systems, and in the maintenance of standard, as well as, the usual heterogeneity of assayed samples require some evidence of similarity between the dose-response curves obtained with the standard and the sample. Nowadays the parallelism test is used to provide such evidence. However, some indications of non-normal errors distribution, such as the presence of out layers, render the parallelism test both conceptually implausible and statistically inefficient. In such a manner we suggest the non-parametric 'frequencial' test as a more sounding option. (author)

  7. Eating behavior in humans, characterized by cumulative food intake curves--a review.

    Science.gov (United States)

    Westerterp-Plantenga, M S

    2000-03-01

    Cumulative food intake curves have been obtained by monitoring eating from a plate, placed on a scale built into a table, and connected to a digital computer. They describe and integrate parameters of consumption of an ad lib single course meal, i.e. meal size, meal duration, eating rate, change in eating rate, bite size and bite frequency. It is concluded that they are an adequate tool for analyzing dietary and clinical interventions on meal size, because the cumulative food intake curve parameters: are stable and consistent within subjects; show a clear relationship with the subject characteristics dietary restraint and obesity; show a clear relationship with the physiological parameters satiation, diet-induced thermogenesis and body-temperature near the liver, and with the cognitive parameter: estimating forthcoming ingestion; are sensitive to instructions, clinical and dietary interventions (preloads, palatability, energy density, macronutrient composition), and to a state of negative energy balance. Because of possible compensatory post-prandial effects, it is suggested that assessment of meal size should be part of a 24 h appetite profile and food intake observation.

  8. Confidence bounds for nonlinear dose-response relationships

    DEFF Research Database (Denmark)

    Baayen, C; Hougaard, P

    2015-01-01

    An important aim of drug trials is to characterize the dose-response relationship of a new compound. Such a relationship can often be described by a parametric (nonlinear) function that is monotone in dose. If such a model is fitted, it is useful to know the uncertainty of the fitted curve...... intervals for the dose-response curve. These confidence bounds have better coverage than Wald intervals and are more precise and generally faster than bootstrap methods. Moreover, if monotonicity is assumed, the profile likelihood approach takes this automatically into account. The approach is illustrated...

  9. The antiproton depth–dose curve measured with alanine detectors

    CERN Document Server

    Bassler, Niels; Palmans, Hugo; Holzscheiter, Michael H; Kovacevic, Sandra

    2008-01-01

    n this paper we report on the measurement of the antiproton depth–dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen and Olsen for conversion of calculated dose into response. A good agreement is observed between the measured and calculated relative effectiveness although an underestimation of the measured values beyond the Bragg-peak remains unexplained. The model prediction of response of alanine towards heavy charged particles encourages future use of the alanine detectors for dosimetry of mixed radiation fields.

  10. The Antiproton Depth Dose Curve Measured with Alanine Detectors

    DEFF Research Database (Denmark)

    Bassler, Niels; Hansen, Johnny Witterseh; Palmans, Hugo

    2008-01-01

    In this paper we report on the measurement of the antiproton depth dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen et Olsen for conversion of calculated dose...... into response. A good agreement was observed between the measured and calculated relative effectiveness although a slight underestimation of the calculated values in the Bragg peak remains unexplained. The model prediction of response of alanine towards heavy charged particles encourages future use...... of the alanine detectors for dosimetry of mixed radiation fields....

  11. TH-AB-207A-04: Assessment of Patients’ Cumulative Effective Dose From CT Examinations

    Energy Technology Data Exchange (ETDEWEB)

    Bostani, M; Cagnon, C; Sepahdari, A; Beckett, K; Oshiro, T; McNitt-Gray, M [UCLA School of Medicine, Los Angeles, CA (United States)

    2016-06-15

    Purpose: The Joint Commission requires institutions to consider patient’s age and recent imaging exams when deciding on the most appropriate type of imaging exam. Additionally, knowing patient’s imaging history can help prevent duplicate scans. Radiation dose management software affords new opportunities to identify and utilize patients with high cumulative doses as one proxy for subsequent review of imaging history and opportunities in avoiding redundant exams. Methods: Using dose management software (Radimetrics, Bayer Healthcare) a total of 72073 CT examinations performed from Jan 2015 to Jan 2016 were examined to categorize patients with a cumulative effective dose of 100 mSv and above. This threshold was selected based on epidemiological studies on populations exposed to radiation, which demonstrate a statistical increase of cancer risk at doses above 100 mSv. Histories of patients with highest cumulative dose and highest number of exams were further investigated by a Radiologist for appropriateness of recurrent studies and potential opportunities for reduction. Results: Out of 34762 patients, 927 (2.7%) were identified with a cumulative dose of 100 mSv and above. The highest cumulative dose (842 mSv) belonged to an oncology patient who underwent 2 diagnostic exams and 9 interventional ablative CT guided procedures. The patient with highest number of exams (56 counts) and cumulative dose of 170 mSv was a 17 year old trauma patient. An imaging history review of these two patients did not suggest any superfluous scans. Conclusion: Our limited pilot study suggests that recurrent CT exams for patients with oncologic or severe trauma history may be warranted and appropriate. As a result, for future studies we will be focusing on high dose patient cohorts not associated with oncology or severe trauma. Additionally, the review process itself has suggested areas for potential improvement in patient care, including improved documentation and Radiologist involvement

  12. TH-AB-207A-04: Assessment of Patients’ Cumulative Effective Dose From CT Examinations

    International Nuclear Information System (INIS)

    Bostani, M; Cagnon, C; Sepahdari, A; Beckett, K; Oshiro, T; McNitt-Gray, M

    2016-01-01

    Purpose: The Joint Commission requires institutions to consider patient’s age and recent imaging exams when deciding on the most appropriate type of imaging exam. Additionally, knowing patient’s imaging history can help prevent duplicate scans. Radiation dose management software affords new opportunities to identify and utilize patients with high cumulative doses as one proxy for subsequent review of imaging history and opportunities in avoiding redundant exams. Methods: Using dose management software (Radimetrics, Bayer Healthcare) a total of 72073 CT examinations performed from Jan 2015 to Jan 2016 were examined to categorize patients with a cumulative effective dose of 100 mSv and above. This threshold was selected based on epidemiological studies on populations exposed to radiation, which demonstrate a statistical increase of cancer risk at doses above 100 mSv. Histories of patients with highest cumulative dose and highest number of exams were further investigated by a Radiologist for appropriateness of recurrent studies and potential opportunities for reduction. Results: Out of 34762 patients, 927 (2.7%) were identified with a cumulative dose of 100 mSv and above. The highest cumulative dose (842 mSv) belonged to an oncology patient who underwent 2 diagnostic exams and 9 interventional ablative CT guided procedures. The patient with highest number of exams (56 counts) and cumulative dose of 170 mSv was a 17 year old trauma patient. An imaging history review of these two patients did not suggest any superfluous scans. Conclusion: Our limited pilot study suggests that recurrent CT exams for patients with oncologic or severe trauma history may be warranted and appropriate. As a result, for future studies we will be focusing on high dose patient cohorts not associated with oncology or severe trauma. Additionally, the review process itself has suggested areas for potential improvement in patient care, including improved documentation and Radiologist involvement

  13. Methods for extracting dose response curves from radiation therapy data. I. A unified approach

    International Nuclear Information System (INIS)

    Herring, D.F.

    1980-01-01

    This paper discusses an approach to fitting models to radiation therapy data in order to extract dose response curves for tumor local control and normal tissue damage. The approach is based on the method of maximum likelihood and is illustrated by several examples. A general linear logistic equation which leads to the Ellis nominal standard dose (NSD) equation is discussed; the fit of this equation to experimental data for mouse foot skin reactions produced by fractionated irradiation is described. A logistic equation based on the concept that normal tissue reactions are associated with the surviving fraction of cells is also discussed, and the fit of this equation to the same set of mouse foot skin reaction data is also described. These two examples illustrate the importance of choosing a model based on underlying mechanisms when one seeks to attach biological significance to a model's parameters

  14. Comparison of X-ray and gamma-ray dose-response curves for pink somatic mutations in Tradescantia clone 02

    International Nuclear Information System (INIS)

    Underbrink, A.G.; Kellerer, A.M.; Mills, R.E.; Sparrow, A.H.; Brookhaven National Lab., Upton, N.Y.

    1976-01-01

    Microdosimetric data indicate that the mean specific energy, xi, produced by individual charged particles from X rays and gamma rays is different for the two radiation qualities by nearly a factor of two. In order to test whether this influences the initial, linear component in the dose-effect relations, a comparison was made between dose-response curves for pink somatic mutations in Tradescantia clone 02 stamen hairs following X and gamma irradiations. Absorbed doses ranged from 2.66 to 300 rad. The results are in agreement with predictions made on the basis of microdosimetric data. At low doses gamma rays are substantially less effective than X rays. The RBE of gamma rays vs. X rays at low doses was approximately 0.6, a value lower than those usually reported in other experimental systems. (orig.) [de

  15. Comparative study of dose-response curve for chromosome aberrations induced in human lymphocytes by {sup 60}Co and X-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Mariana E.; Mendonça, Julyanne C.G.; Andrade, Aida M.G.; Silva, Laís M.; Hwang, Suy; Melo, Ana M.M.A.; Santos, Neide; Lima, Fabiana F., E-mail: mendes_sb@hotmail.com [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2017-11-01

    Biodosimetry represents a biological marker to the estimation of health risks after accidental overexposure to ionizing radiation. Chromosomal dicentric in peripheral blood lymphocytes have been the most reliable biomarker of exposure to IR during the last several decades. This technique could be used to support physical dosimetry or when it is impossible to achieve it. A reliable measurement of the absorbed dose is critical for medical decision, including the assessment of long-term health consequences. The aim of this research is to compare dose-response curves for dicentric aberration induced in human lymphocytes by {sup 60}Co and X-Rays. For both quality of radiation, the samples were exposed to at least eight different absorbed doses. The X-rays with dose rate of 0,275 Gy/min at Laboratory of Metrology (CRCN/NE - PE - Brazil) and the second one was exposed to cobalt source with dose rate of 0.055 Gy/min ({sup 60}Co Gammacell 220) located at Department of Nuclear Energy (UFPE-DEN-BRASIL). Mitotic metaphase cells were obtained by lymphocyte culture for chromosomal analysis and slides were stained with Giemsa 5%. The frequencies of dicentrics were counted in more than 18.000 metaphases for this comparison. After that, all frequencies and distributions of dicentrics were tested to analyze their conformity with Poisson distribution and then each quality of radiation were used for build the calibration curves using Dose Estimate program. These results showed that both curves followed the Poisson distribution and coefficients of each one are: YX-rays = 0,0013 (± 0,0006) + 0,0271 (± 0,0086)⁎D + 0,0556(±0,0050))⁎D{sup 2} and Y{sub Co-60} = 0,0014 (± 0,0010) + 0,0081 (± 0,0073))⁎D + 0,0451 (± 0,0046))⁎D{sup 2} (Y = frequency of dicentrics and D = absorbed dose). It was expected that there was no significant difference between this two types of radiation because both were low LET. We believed that dose rate have been a principal factor to produce this

  16. Natural and laboratory TT-OSL dose response curves: Testing the lifetime of the TT-OSL signal in nature

    International Nuclear Information System (INIS)

    Chapot, M.S.; Roberts, H.M.; Duller, G.A.T.; Lai, Z.P.

    2016-01-01

    This study compares natural and laboratory generated thermally transferred optically stimulated luminescence (TT-OSL) dose response curves (DRCs) for fine-grain quartz extracts from the Luochuan loess section in central China. Both DRCs saturate at high doses relative to the quartz OSL signal; the natural TT-OSL DRC saturates at about 2200 Gy and laboratory DRCs saturate at about 2700 Gy. However, the natural and laboratory TT-OSL DRCs deviate from one another at circa 150 Gy resulting in TT-OSL equivalent dose underestimation relative to palaeodoses expected from dose rates and independent age control. The lifetime of the TT-OSL signal at 10 °C, calculated from values of trap parameters E and s, is compared against the value for lifetime of the TT-OSL signal in nature at average burial temperature as determined from the age underestimation caused by deviation of the natural and laboratory generated DRCs. These two independent assessments of TT-OSL signal lifetime at Luochuan give similar values, suggesting that laboratory measurements of thermal stability reflect natural burial lifetimes and can potentially be used to correct TT-OSL ages for the difference between natural and laboratory dose response curves. - Highlights: • Natural and laboratory TT-OSL DRCs deviate at ∼150 Gy but saturate at higher doses. • TT-OSL signal lifetime at 10 °C calculated from measured E and s values is ∼180 ka. • TT-OSL signal lifetime at Luochuan estimated from the DRCs' deviation is ∼175 ka. • Natural and laboratory TT-OSL DRC deviation may be caused by low thermal stability. • Laboratory measurements of signal lifetime may be able to correct old TT-OSL ages.

  17. Dose Response Model of Biological Reaction to Low Dose Rate Gamma Radiation

    International Nuclear Information System (INIS)

    Magae, J.; Furikawa, C.; Hoshi, Y.; Kawakami, Y.; Ogata, H.

    2004-01-01

    It is necessary to use reproducible and stable indicators to evaluate biological responses to long term irradiation at low dose-rate. They should be simple and quantitative enough to produce the results statistically accurate, because we have to analyze the subtle changes of biological responses around background level at low dose. For these purposes we chose micronucleus formation of U2OS, a human osteosarcoma cell line, as indicators of biological responses. Cells were exposed to gamma ray in irradiation rom bearing 50,000 Ci 60Co. After irradiation, they were cultured for 24 h in the presence of cytochalasin B to block cytokinesis, and cytoplasm and nucleus were stained with DAPI and prospidium iodide, respectively. the number of binuclear cells bearing micronuclei was counted under a fluorescence microscope. Dose rate in the irradiation room was measured with PLD. Dose response of PLD is linear between 1 mGy to 10 Gy, and standard deviation of triplicate count was several percent of mean value. We fitted statistically dose response curves to the data, and they were plotted on the coordinate of linearly scale response and dose. The results followed to the straight line passing through the origin of the coordinate axes between 0.1-5 Gy, and dose and does rate effectiveness factor (DDREF) was less than 2 when cells were irradiated for 1-10 min. Difference of the percent binuclear cells bearing micronucleus between irradiated cells and control cells was not statistically significant at the dose above 0.1 Gy when 5,000 binuclear cells were analyzed. In contrast, dose response curves never followed LNT, when cells were irradiated for 7 to 124 days. Difference of the percent binuclear cells bearing micronucleus between irradiated cells and control cells was not statistically significant at the dose below 6 Gy, when cells were continuously irradiated for 124 days. These results suggest that dose response curve of biological reaction is remarkably affected by exposure

  18. Dose response curve of induction of MN in lymphocytes for energies Cs-137; Curva dosis respuesta de induccion de micronucleos en linfocitos para las energias Cs-137

    Energy Technology Data Exchange (ETDEWEB)

    Serna Berna, A.; Alcaraz, M.; Acevedo, C.; Vicente, V.; Fuente, I. de la; Canteras, M.

    2006-07-01

    The determination of the dose-response curve is a crucial step to use the Micronucleus assay in Lymphocytes as a biological dosimeters. The most widely used fitting function is the linear-quadratic function. The coefficients are fitted by calibration data provided by irradiations of blood from healthy donors. In our case we performed the calibration curve corresponding to gamma radiation from Cesium-137 (660 keV). Doses ranged from 0 to 16 Gy. The fitting procedure used was the iteratively re weighted least square algorithm implemented in a Matlab routine. The results of the analysis of our data show that the dose-effect curve does not follow a linear-quadratic curve at high radiation doses, diminishing the quadratic parameters as dose increases. This can be interpreted as a micronucleus saturation effect beyond a certain dose level. We conclude that the MN assay with lymphocytes can be well characterized as a biological dosimeters up to a maximum dose of 4.5 Gy. (Author)

  19. Heavy particle irradiation, neurochemistry and behavior: thresholds, dose-response curves and recovery of function

    Science.gov (United States)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.

    2004-01-01

    Exposure to heavy particles can affect the functioning of the central nervous system (CNS), particularly the dopaminergic system. In turn, the radiation-induced disruption of dopaminergic function affects a variety of behaviors that are dependent upon the integrity of this system, including motor behavior (upper body strength), amphetamine (dopamine)-mediated taste aversion learning, and operant conditioning (fixed-ratio bar pressing). Although the relationships between heavy particle irradiation and the effects of exposure depend, to some extent, upon the specific behavioral or neurochemical endpoint under consideration, a review of the available research leads to the hypothesis that the endpoints mediated by the CNS have certain characteristics in common. These include: (1) a threshold, below which there is no apparent effect; (2) the lack of a dose-response relationship, or an extremely steep dose-response curve, depending on the particular endpoint; and (3) the absence of recovery of function, such that the heavy particle-induced behavioral and neural changes are present when tested up to one year following exposure. The current report reviews the data relevant to the degree to which these characteristics are common to neurochemical and behavioral endpoints that are mediated by the effects of exposure to heavy particles on CNS activity.

  20. Dose-response curve for translocation frequency with single pair of painted chromosome. A comparison with dicentric and micronuclei frequency

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalam, P.; Paul, S.F.D.; Mohankumar, M.N.; Prabhu, B.K.; Gajendiran, N.; Jeevanram, R.K

    2000-07-01

    A translocation dose-response curve using a single pair of painted chromosomes was constructed. The translocation frequencies observed at different doses were compared to those obtained for dicentrics (DC) and micronuclei (MN). The translocation and DC frequency followed the Poisson distribution and MN showed over-dispersion. The translocation and DC frequencies were nearly the same for each dose point. Micronuclei showed a comparatively lower frequency. The alpha/beta ratio for translocations (0.916) and DC (0.974) were comparable, whereas the value for MN (1.526) was much higher. The equal frequencies of translocations and DC observed for a given dose indicated that genomic translocation frequency estimated using a single pair of painted chromosomes provides a reliable and easy method to measure translocation frequency. (autho000.

  1. Dose-response curve for translocation frequency with single pair of painted chromosome. A comparison with dicentric and micronuclei frequency

    International Nuclear Information System (INIS)

    Venkatachalam, P.; Paul, S.F.D.; Mohankumar, M.N.; Prabhu, B.K.; Gajendiran, N.; Jeevanram, R.K.

    2000-01-01

    A translocation dose-response curve using a single pair of painted chromosomes was constructed. The translocation frequencies observed at different doses were compared to those obtained for dicentrics (DC) and micronuclei (MN). The translocation and DC frequency followed the Poisson distribution and MN showed over-dispersion. The translocation and DC frequencies were nearly the same for each dose point. Micronuclei showed a comparatively lower frequency. The alpha/beta ratio for translocations (0.916) and DC (0.974) were comparable, whereas the value for MN (1.526) was much higher. The equal frequencies of translocations and DC observed for a given dose indicated that genomic translocation frequency estimated using a single pair of painted chromosomes provides a reliable and easy method to measure translocation frequency. (author)

  2. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation

    Science.gov (United States)

    Van Dongen, Hans P A.; Maislin, Greg; Mullington, Janet M.; Dinges, David F.

    2003-01-01

    OBJECTIVES: To inform the debate over whether human sleep can be chronically reduced without consequences, we conducted a dose-response chronic sleep restriction experiment in which waking neurobehavioral and sleep physiological functions were monitored and compared to those for total sleep deprivation. DESIGN: The chronic sleep restriction experiment involved randomization to one of three sleep doses (4 h, 6 h, or 8 h time in bed per night), which were maintained for 14 consecutive days. The total sleep deprivation experiment involved 3 nights without sleep (0 h time in bed). Each study also involved 3 baseline (pre-deprivation) days and 3 recovery days. SETTING: Both experiments were conducted under standardized laboratory conditions with continuous behavioral, physiological and medical monitoring. PARTICIPANTS: A total of n = 48 healthy adults (ages 21-38) participated in the experiments. INTERVENTIONS: Noctumal sleep periods were restricted to 8 h, 6 h or 4 h per day for 14 days, or to 0 h for 3 days. All other sleep was prohibited. RESULTS: Chronic restriction of sleep periods to 4 h or 6 h per night over 14 consecutive days resulted in significant cumulative, dose-dependent deficits in cognitive performance on all tasks. Subjective sleepiness ratings showed an acute response to sleep restriction but only small further increases on subsequent days, and did not significantly differentiate the 6 h and 4 h conditions. Polysomnographic variables and delta power in the non-REM sleep EEG-a putative marker of sleep homeostasis--displayed an acute response to sleep restriction with negligible further changes across the 14 restricted nights. Comparison of chronic sleep restriction to total sleep deprivation showed that the latter resulted in disproportionately large waking neurobehavioral and sleep delta power responses relative to how much sleep was lost. A statistical model revealed that, regardless of the mode of sleep deprivation, lapses in behavioral alertness

  3. The antiproton depth–dose curve in water

    CERN Document Server

    Bassler, N; Jäkel, O; Knudsen, H V; Kovacevic, S

    2008-01-01

    We have measured the depth–dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge for ion recombination effects. The results are compared with Monte Carlo calculations and were found to be in good agreement. Based on this agreement we calculate the antiproton depth–dose curve for antiprotons and compare it with that for protons and find a doubling of the physical dose in the peak region for antiprotons.

  4. The shapes of the radiation dose-mutation response curves in drosophila: Mechanisms and implications

    International Nuclear Information System (INIS)

    Abrahamson, S.; DeJongh, C.; Meyer, H.U.

    1981-01-01

    This chapter proposes that radiation induced mutations, namely sex-linked recessive lethals in Drosophila and forward mutations at specific loci in Drosophila, mammals and lower eucaryotes, are the result of two sub-lesions or hits, induced by either single ionization tracks or by the interaction of two independent tracks for low LET radiations, when the dose is delivered in an acute fashion. Utilizes the well recognized linear quadratic expression Y=C+αD+βD 2 , where C is the spontaneous frequency of events scored and α and β represent the coefficients of the dose. Concludes that for low LET radiations, X or gamma rays, the linear-quadratic model can be used to predict the genetic response of germ cells and somatic cells to a variety of radiation regimes. Points out that the point of inflection in the curve, α/β value, can be determined specifically by target dimensions which vary with respect to DNA content. Considers the difference in RBE values observed for different species to be a reflection of their different target sizes

  5. Thermoluminescence dose response of quartz as a function of irradiation temperature

    International Nuclear Information System (INIS)

    Kitis, G.; Kaldoudi, E.; Charalambous, S.

    1990-01-01

    The thermoluminescence (TL) response of pure Norwegian quartz as a function of irradiation temperature (T irr ) and dose has been investigated. The TL response of the (150-230 o C) and (230-350 o C) glow curve intervals shows a strong dependence on T irr between 77 and 373 K in the dose range from 54 to 8.4 x 10 4 Gy. Both glow curve intervals also show temperature dependent dose response properties. The 150-230 o C interval is supralinear from the lowest dose (54 Gy). Its maximum supralinearity factor appears at T irr = 293 K. The 230-350 o C interval shows sublinear behaviour below T irr = + 193 K, while at T irr ≥ 273 K it shows the well known dose response curves. Its maximum supralinearity factor appears at T irr = 323 K. The linear response is extended up to 460 Gy at T irr = 273 K and falls to 80 Gy at T irr = 373 K. (author)

  6. IRSL dating of K-feldspars: Modelling natural dose response curves to deal with anomalous fading and trap competition

    International Nuclear Information System (INIS)

    Kars, Romee H.; Wallinga, Jakob

    2009-01-01

    We recently proposed a model that reconstructs the natural dose response curve for K-rich feldspars, using laboratory fading measurements and dose response as input parameters. The model is based on the relationship between recombination centre density and trap lifetime. In this study we test the working of the model by comparing modelled feldspar ages with known quartz OSL ages of the same samples and with anomalous fading-corrected feldspar ages. The modelled feldspar ages are in good agreement with quartz OSL ages and corrected feldspar ages, opening possibilities for future use of the model on samples without independent age constraints. Furthermore, we investigate the effects of trap competition on the build-up of IRSL signal using two new variations of the model. Results show that incorporating trap competition into the model reduces the agreement between feldspar IRSL ages and quartz OSL ages.

  7. Learning curve for robotic-assisted surgery for rectal cancer: use of the cumulative sum method.

    Science.gov (United States)

    Yamaguchi, Tomohiro; Kinugasa, Yusuke; Shiomi, Akio; Sato, Sumito; Yamakawa, Yushi; Kagawa, Hiroyasu; Tomioka, Hiroyuki; Mori, Keita

    2015-07-01

    Few data are available to assess the learning curve for robotic-assisted surgery for rectal cancer. The aim of the present study was to evaluate the learning curve for robotic-assisted surgery for rectal cancer by a surgeon at a single institute. From December 2011 to August 2013, a total of 80 consecutive patients who underwent robotic-assisted surgery for rectal cancer performed by the same surgeon were included in this study. The learning curve was analyzed using the cumulative sum method. This method was used for all 80 cases, taking into account operative time. Operative procedures included anterior resections in 6 patients, low anterior resections in 46 patients, intersphincteric resections in 22 patients, and abdominoperineal resections in 6 patients. Lateral lymph node dissection was performed in 28 patients. Median operative time was 280 min (range 135-683 min), and median blood loss was 17 mL (range 0-690 mL). No postoperative complications of Clavien-Dindo classification Grade III or IV were encountered. We arranged operative times and calculated cumulative sum values, allowing differentiation of three phases: phase I, Cases 1-25; phase II, Cases 26-50; and phase III, Cases 51-80. Our data suggested three phases of the learning curve in robotic-assisted surgery for rectal cancer. The first 25 cases formed the learning phase.

  8. Accurate convolution/superposition for multi-resolution dose calculation using cumulative tabulated kernels

    International Nuclear Information System (INIS)

    Lu Weiguo; Olivera, Gustavo H; Chen Mingli; Reckwerdt, Paul J; Mackie, Thomas R

    2005-01-01

    Convolution/superposition (C/S) is regarded as the standard dose calculation method in most modern radiotherapy treatment planning systems. Different implementations of C/S could result in significantly different dose distributions. This paper addresses two major implementation issues associated with collapsed cone C/S: one is how to utilize the tabulated kernels instead of analytical parametrizations and the other is how to deal with voxel size effects. Three methods that utilize the tabulated kernels are presented in this paper. These methods differ in the effective kernels used: the differential kernel (DK), the cumulative kernel (CK) or the cumulative-cumulative kernel (CCK). They result in slightly different computation times but significantly different voxel size effects. Both simulated and real multi-resolution dose calculations are presented. For simulation tests, we use arbitrary kernels and various voxel sizes with a homogeneous phantom, and assume forward energy transportation only. Simulations with voxel size up to 1 cm show that the CCK algorithm has errors within 0.1% of the maximum gold standard dose. Real dose calculations use a heterogeneous slab phantom, both the 'broad' (5 x 5 cm 2 ) and the 'narrow' (1.2 x 1.2 cm 2 ) tomotherapy beams. Various voxel sizes (0.5 mm, 1 mm, 2 mm, 4 mm and 8 mm) are used for dose calculations. The results show that all three algorithms have negligible difference (0.1%) for the dose calculation in the fine resolution (0.5 mm voxels). But differences become significant when the voxel size increases. As for the DK or CK algorithm in the broad (narrow) beam dose calculation, the dose differences between the 0.5 mm voxels and the voxels up to 8 mm (4 mm) are around 10% (7%) of the maximum dose. As for the broad (narrow) beam dose calculation using the CCK algorithm, the dose differences between the 0.5 mm voxels and the voxels up to 8 mm (4 mm) are around 1% of the maximum dose. Among all three methods, the CCK algorithm

  9. Application of Glow Curve Deconvolution Method to Evaluate Low Dose TLD LiF

    International Nuclear Information System (INIS)

    Kurnia, E; Oetami, H R; Mutiah

    1996-01-01

    Thermoluminescence Dosimeter (TLD), especially LiF:Mg, Ti material, is one of the most practical personal dosimeter in known to date. Dose measurement under 100 uGy using TLD reader is very difficult in high precision level. The software application is used to improve the precision of the TLD reader. The objectives of the research is to compare three Tl-glow curve analysis method irradiated in the range between 5 up to 250 uGy. The first method is manual analysis, dose information is obtained from the area under the glow curve between pre selected temperature limits, and background signal is estimated by a second readout following the first readout. The second method is deconvolution method, separating glow curve into four peaks mathematically and dose information is obtained from area of peak 5, and background signal is eliminated computationally. The third method is deconvolution method but the dose is represented by the sum of area of peak 3,4 and 5. The result shown that the sum of peak 3,4 and 5 method can improve reproducibility six times better than manual analysis for dose 20 uGy, the ability to reduce MMD until 10 uGy rather than 60 uGy with manual analysis or 20 uGy with peak 5 area method. In linearity, the sum of peak 3,4 and 5 method yields exactly linear dose response curve over the entire dose range

  10. Dose response curve for prematurely condensed chromosome fragments of human lymphocytes after 60Co-γ ray exposure

    International Nuclear Information System (INIS)

    Gao Jinsheng; Zheng Siying; Bao Hong

    1992-06-01

    The dose-effect relationship of premature condensed chromosome fragments in human lymphocytes irradiated by 60 Co gamma ray was studied by PCC method (premature condensed chromosomes). In addition, The conventional cellular genetics method was also used in the study. The response curve of both methods can represented by two linear equations. The ratio of two slopes, K PCC /K M1 , is about 28. Comparing with conventional method, the PCC method has many advantages such as faster, simpler, more sensitive and accurate. The PCC method used in the studying of radiation damage is also discussed

  11. Bone cancer from radium: canine dose response explains data for mice and humans

    International Nuclear Information System (INIS)

    Raabe, O.G.; Book, S.A.; Parks, N.J.

    1980-01-01

    Analysis of lifetime studies of 243 beagles with skeletal burdens of radium-226 shows that the distribution of bone cancers clusters about a linear function of the logarithms of radiation dose rate to the skeleton and time from exposure until death. Similar relations displaced by species-dependent response ratios also provide satisfactory descriptions of the reported data on deaths from primary bone cancers in people and mice exposed to radium-226. The median cumulative doses (or times) leading to death from bone tumors are 2.9 times larger for dogs than for mice and 3.6 times larger for people than for dogs. These response ratios are well correlated with the normal life expectancies. The cumulative radiation dose required to give significant risk of bone cancer is found to be much less at lower dose rates than at higher rates, but the time required for the tumors to be manifested is longer. At low dose rates, this time exceeds the normal life-span and appears as a practical threshold, which for bone cancer is estimated to occur at an average cumulative radiation dose to the skeleton of about 50 to 110 rads for the three species

  12. Quantitative radiation dose-response relationships for normal tissues in man - I. Gustatory tissues response during photon and neutron radiotherapy

    International Nuclear Information System (INIS)

    Mossman, K.L.

    1982-01-01

    Quantitative radiation dose-response curves for normal gustatory tissue in man were studied. Taste function, expressed as taste loss, was evaluated in 84 patients who were given either photon or neutron radiotherapy for tumors in the head and neck region. Patients were treated to average tumor doses of 6600 cGy (photon) or 2200 cGy intervals for photon patients and 320-cGy intervals for neutron patients during radiotherapy. The dose-response curves for photons and neutrons were analyzed by fitting a four-parameter logistic equation to the data. Photon and neutron curves differed principally in their relative position along the dose axis. Comparison of the dose-response curves were made by determination of RBE. At 320 cGy, the lowest neutron dose at which taste measurements were made, RBE = 5.7. If this RBE is correct, then the therapeutic gain factor may be equal to or less than 1, indicating no biological advantage in using neutrons over photons for this normal tissue. These studies suggest measurements of taste function and evaluation of dose-response relationships may also be useful in quantitatively evaluating the efficacy of chemical modifiers of radiation response such as hypoxic cell radiosensitizers and radioprotectors

  13. Dose-response meta-analysis of differences in means

    Directory of Open Access Journals (Sweden)

    Alessio Crippa

    2016-08-01

    Full Text Available Abstract Background Meta-analytical methods are frequently used to combine dose-response findings expressed in terms of relative risks. However, no methodology has been established when results are summarized in terms of differences in means of quantitative outcomes. Methods We proposed a two-stage approach. A flexible dose-response model is estimated within each study (first stage taking into account the covariance of the data points (mean differences, standardized mean differences. Parameters describing the study-specific curves are then combined using a multivariate random-effects model (second stage to address heterogeneity across studies. Results The method is fairly general and can accommodate a variety of parametric functions. Compared to traditional non-linear models (e.g. E max, logistic, spline models do not assume any pre-specified dose-response curve. Spline models allow inclusion of studies with a small number of dose levels, and almost any shape, even non monotonic ones, can be estimated using only two parameters. We illustrated the method using dose-response data arising from five clinical trials on an antipsychotic drug, aripiprazole, and improvement in symptoms in shizoaffective patients. Using the Positive and Negative Syndrome Scale (PANSS, pooled results indicated a non-linear association with the maximum change in mean PANSS score equal to 10.40 (95 % confidence interval 7.48, 13.30 observed for 19.32 mg/day of aripiprazole. No substantial change in PANSS score was observed above this value. An estimated dose of 10.43 mg/day was found to produce 80 % of the maximum predicted response. Conclusion The described approach should be adopted to combine correlated differences in means of quantitative outcomes arising from multiple studies. Sensitivity analysis can be a useful tool to assess the robustness of the overall dose-response curve to different modelling strategies. A user-friendly R package has been developed to facilitate

  14. Extracting the normal lung dose–response curve from clinical DVH data: a possible role for low dose hyper-radiosensitivity, increased radioresistance

    International Nuclear Information System (INIS)

    Gordon, J J; Snyder, K; Zhong, H; Barton, K; Sun, Z; Chetty, I J; Matuszak, M; Ten Haken, R K

    2015-01-01

    In conventionally fractionated radiation therapy for lung cancer, radiation pneumonitis’ (RP) dependence on the normal lung dose-volume histogram (DVH) is not well understood. Complication models alternatively make RP a function of a summary statistic, such as mean lung dose (MLD). This work searches over damage profiles, which quantify sub-volume damage as a function of dose. Profiles that achieve best RP predictive accuracy on a clinical dataset are hypothesized to approximate DVH dependence.Step function damage rate profiles R(D) are generated, having discrete steps at several dose points. A range of profiles is sampled by varying the step heights and dose point locations. Normal lung damage is the integral of R(D) with the cumulative DVH. Each profile is used in conjunction with a damage cutoff to predict grade 2 plus (G2+) RP for DVHs from a University of Michigan clinical trial dataset consisting of 89 CFRT patients, of which 17 were diagnosed with G2+ RP.Optimal profiles achieve a modest increase in predictive accuracy—erroneous RP predictions are reduced from 11 (using MLD) to 8. A novel result is that optimal profiles have a similar distinctive shape: enhanced damage contribution from low doses (<20 Gy), a flat contribution from doses in the range ∼20–40 Gy, then a further enhanced contribution from doses above 40 Gy. These features resemble the hyper-radiosensitivity / increased radioresistance (HRS/IRR) observed in some cell survival curves, which can be modeled using Joiner’s induced repair model.A novel search strategy is employed, which has the potential to estimate RP dependence on the normal lung DVH. When applied to a clinical dataset, identified profiles share a characteristic shape, which resembles HRS/IRR. This suggests that normal lung may have enhanced sensitivity to low doses, and that this sensitivity can affect RP risk. (paper)

  15. Non-linear least squares curve fitting of a simple theoretical model to radioimmunoassay dose-response data using a mini-computer

    International Nuclear Information System (INIS)

    Wilkins, T.A.; Chadney, D.C.; Bryant, J.; Palmstroem, S.H.; Winder, R.L.

    1977-01-01

    Using the simple univalent antigen univalent-antibody equilibrium model the dose-response curve of a radioimmunoassay (RIA) may be expressed as a function of Y, X and the four physical parameters of the idealised system. A compact but powerful mini-computer program has been written in BASIC for rapid iterative non-linear least squares curve fitting and dose interpolation with this function. In its simplest form the program can be operated in an 8K byte mini-computer. The program has been extensively tested with data from 10 different assay systems (RIA and CPBA) for measurement of drugs and hormones ranging in molecular size from thyroxine to insulin. For each assay system the results have been analysed in terms of (a) curve fitting biases and (b) direct comparison with manual fitting. In all cases the quality of fitting was remarkably good in spite of the fact that the chemistry of each system departed significantly from one or more of the assumptions implicit in the model used. A mathematical analysis of departures from the model's principal assumption has provided an explanation for this somewhat unexpected observation. The essential features of this analysis are presented in this paper together with the statistical analyses of the performance of the program. From these and the results obtained to date in the routine quality control of these 10 assays, it is concluded that the method of curve fitting and dose interpolation presented in this paper is likely to be of general applicability. (orig.) [de

  16. Energy dependence of contrast-detail-dose and object-detectability-dose curves for CT scanners

    International Nuclear Information System (INIS)

    Wagner, L.K.; Cohen, G.

    1982-01-01

    The energy dependence of contrast-detail-dose (CdD) and object-detectability-dose (OdD) curves for computed tomographic scanners is investigated. The effects of changes in beam energy on perceptibility are shown to be due to changes in signal-to-noise ratio resulting from changes in contrast and photon statistics. Energy-dependence analysis of OdD curves is shown to depend on the atomic composition of the phantom used to generate the curves, while such an analysis of CdD curves is independent of the atomic composition of the phantom. It is also shown that any OdD curve can be generated from CdD curves and that use of this fact rectifies any potential energy-dependent interpretation of CdD curves

  17. Low Dose Radiation Response Curves, Networks and Pathways in Human Lymphoblastoid Cells Exposed from 1 to 10 cGy of Acute Gamma Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wyrobek, A. J.; Manohar, C. F.; Nelson, D. O.; Furtado, M. R.; Bhattacharya, M. S.; Marchetti, F.; Coleman, M.A.

    2011-04-18

    We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10 cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of {approx}80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10 cGy, some with suggestive evidence that transcription was modulated at doses below 1 cGy. MYC, FOS and TP53 were the major network nodes of the low-dose response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types and tissues, independent of proliferation status.

  18. Dose-response relationships for carcinogens: a review

    International Nuclear Information System (INIS)

    Zeise, L.; Wilson, R.; Crouch, E.A.C.

    1987-01-01

    The authors review the experimental evidence for various shapes of dose-response relationships for carcinogens and summarize those experiments that give the most information on relatively low doses. A brief review of some models is given to illustrate the shapes of dose-response curve expected from them. Their major interest is in the use of dose-response relationships to estimate risks to humans at low doses, and so they pay special attention to experimentally observed and theoretically expected nonlinearities. There are few experimental examples of nonlinear dose-response relations in humans, but this may simply be due to the limitations in the data. The several examples in rodents, even though for high dose data, suggest that nonlinearity is common. In some cases such nonlinearities may be rationalized on the basis of the pharmacokinetics of the test compound or its metabolites

  19. Dose response curves for effects of low-level radiation

    International Nuclear Information System (INIS)

    Myers, D.K.

    1980-01-01

    The linear dose-response model used by international committees to assess the genetic and carcinogenic hazards of low-level radiation appears to be the most reasonable interpretation of the available scientific data that are relevant to this topic. There are, of course, reasons to believe that this model may overestimate radiation hazards in certain instances, a fact acknowledged in recent reports of these committees. The linear model is now also being utilized to estimate the potential carcinogenic hazards of other agents such as asbestos and polycyclic aromatic hydrocarbons. This model implies that there is no safe dose for any of these agents and that potential health hazards will increase in direct proportion to total accumulated dose. The practical implication is the recommendation that all exposures should be kept 'as low as reasonably achievable, economic and social factors being taken into account'. (auth)

  20. Dose/response relationships and policy formulation

    International Nuclear Information System (INIS)

    Robinson, P.D.

    1981-01-01

    The ICRP 26 cost/benefit approach to establishing operational radiation protection guidelines is discussed. The purpose is to aid the policy maker in the decision making process, using as a basis the dose-response curve

  1. UV-radiation and skin cancer dose effect curves

    International Nuclear Information System (INIS)

    Henriksen, T.; Dahlback, A.; Larsen, S.H.

    1988-08-01

    Norwegian skin cancer data were used in an attempt to arrive at the dose effect relationship for UV-carcinogenesis. The Norwegian population is relatively homogenous with regard to skin type and live in a country where the annual effective UV-dose varies by approximately 40 percent. Four different regions of the country, each with a broadness of 1 o in latitude (approximately 111 km), were selected . The annual effective UV-doses for these regions were calculated assuming normal ozone conditions throughout the year. The incidence of malignant melanoma and non-melanoma skin cancer (mainly basal cell carcinoma) in these regions were considered and compared to the annual UV-doses. For both these types of cancer a quadratic dose effect curve seems to be valid. Depletions of the ozone layer results in larger UV-doses which in turn may yield more skin cancer. The dose effect curves suggest that the incidence rate will increase by an ''amplification factor'' of approximately 2

  2. Hypertonic Saline in Conjunction with High-Dose Furosemide Improves Dose-Response Curves in Worsening Refractory Congestive Heart Failure.

    Science.gov (United States)

    Paterna, Salvatore; Di Gaudio, Francesca; La Rocca, Vincenzo; Balistreri, Fabio; Greco, Massimiliano; Torres, Daniele; Lupo, Umberto; Rizzo, Giuseppina; di Pasquale, Pietro; Indelicato, Sergio; Cuttitta, Francesco; Butler, Javed; Parrinello, Gaspare

    2015-10-01

    14% for urine output; 29, 24, and 16% for total sodium excretion; 45, 34, and 20% for urinary osmolarity; and 27, 36, and 32% for total furosemide excretion in groups 1, 2, and 3, respectively. These findings were translated in an improvement in the furosemide dose-response curves in these patients. These results may serve as new pathophysiological basis for HSS use in the treatment of refractory CHF.

  3. Biological dosimetry in radiation accidents. Dose-response curve by chromosomal aberrations analysis

    International Nuclear Information System (INIS)

    Hadjidekova, V.; Hristova, R.; Atanasova, P.; Popova, L.; Stainova, A.; Bulanova, M.; Georgieva, I.; Vukov, M.

    2005-01-01

    The aim of this paper is to obtain a dose-response relationship for chromosomal aberrations induced in human lymphocytes after in vitro irradiation. Peripheral blood samples of 7 different donors were used. The blood irradiation was done with Cs137 gamma-rays at different doses: 0.0, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0 and 3.0 Gy. Lymphocyte cultures were established and maintain for 48 hours at 37 0 C in CO 2 incubator for chromosomal aberration analysis. The dose response relationship has been established based on dysenteric and ring chromosomes yield. The relationship can be described by the following equation: Y = 0.0274D + 0.0251 D 2 , where (Y) = dysenteric and ring chromosomes yield, (D) = radiation dose obtained. EXCEL software was established for calculation of the received dose by using this equation, as a whole body equivalent dose acute irradiation

  4. Experimental data and dose-response models

    International Nuclear Information System (INIS)

    Ullrich, R.L.

    1985-01-01

    Dose-response relationships for radiation carcinogenesis have been of interest to biologists, modelers, and statisticians for many years. Despite his interest there are few instances in which there are sufficient experimental data to allow the fitting of various dose-response models. In those experimental systems for which data are available the dose-response curves for tumor induction for the various systems cannot be described by a single model. Dose-response models which have been observed following acute exposures to gamma rays include threshold, quadratic, and linear models. Data on sex, age, and environmental influences of dose suggest a strong role of host factors on the dose response. With decreasing dose rate the effectiveness of gamma ray irradiation tends to decrease in essentially every instance. In those cases in which the high dose rate dose response could be described by a quadratic model, the effect of dose rate is consistent with predictions based on radiation effects on the induction of initial events. Whether the underlying reasons for the observed dose-rate effect is a result of effects on the induction of initial events or is due to effects on the subsequent steps in the carcinogenic process is unknown. Information on the dose response for tumor induction for high LET (linear energy transfer) radiations such as neutrons is even more limited. The observed dose and dose rate data for tumor induction following neutron exposure are complex and do not appear to be consistent with predictions based on models for the induction of initial events

  5. Single toxin dose-response models revisited

    Energy Technology Data Exchange (ETDEWEB)

    Demidenko, Eugene, E-mail: eugened@dartmouth.edu [Department of Biomedical Data Science, Geisel School of Medicine at Dartmouth, Hanover, NH03756 (United States); Glaholt, SP, E-mail: sglaholt@indiana.edu [Indiana University, School of Public & Environmental Affairs, Bloomington, IN47405 (United States); Department of Biological Sciences, Dartmouth College, Hanover, NH03755 (United States); Kyker-Snowman, E, E-mail: ek2002@wildcats.unh.edu [Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH03824 (United States); Shaw, JR, E-mail: joeshaw@indiana.edu [Indiana University, School of Public & Environmental Affairs, Bloomington, IN47405 (United States); Chen, CY, E-mail: Celia.Y.Chen@dartmouth.edu [Department of Biological Sciences, Dartmouth College, Hanover, NH03755 (United States)

    2017-01-01

    The goal of this paper is to offer a rigorous analysis of the sigmoid shape single toxin dose-response relationship. The toxin efficacy function is introduced and four special points, including maximum toxin efficacy and inflection points, on the dose-response curve are defined. The special points define three phases of the toxin effect on mortality: (1) toxin concentrations smaller than the first inflection point or (2) larger then the second inflection point imply low mortality rate, and (3) concentrations between the first and the second inflection points imply high mortality rate. Probabilistic interpretation and mathematical analysis for each of the four models, Hill, logit, probit, and Weibull is provided. Two general model extensions are introduced: (1) the multi-target hit model that accounts for the existence of several vital receptors affected by the toxin, and (2) model with a nonzero mortality at zero concentration to account for natural mortality. Special attention is given to statistical estimation in the framework of the generalized linear model with the binomial dependent variable as the mortality count in each experiment, contrary to the widespread nonlinear regression treating the mortality rate as continuous variable. The models are illustrated using standard EPA Daphnia acute (48 h) toxicity tests with mortality as a function of NiCl or CuSO{sub 4} toxin. - Highlights: • The paper offers a rigorous study of a sigmoid dose-response relationship. • The concentration with highest mortality rate is rigorously defined. • A table with four special points for five morality curves is presented. • Two new sigmoid dose-response models have been introduced. • The generalized linear model is advocated for estimation of sigmoid dose-response relationship.

  6. Parametric curve evaluation of a phototransistor used as detector in stereotactic radiosurgery X-ray beam

    International Nuclear Information System (INIS)

    Lima, Daniela Pontes A.; Santos, Luiz Antonio P.; Santos, Walter M.; Silva Junior, Eronides F. da

    2005-01-01

    Phototransistors have been widely used as detectors for low energy X-rays. However, when they are used in high energy X-rays fields like those generated from linear accelerators (linac), there is a certain loss of sensibility to the ionizing radiation. This damage is cumulative and irreversible. Thus, a correction factor must be applied to its response, which is proportional to the integrated dose. However, it is possible to estimate the correction factor by using the V x I parametric curve of the device. The aim of this work was to develop studies to evaluate and correlate the parametric response curve of a phototransistor with its loss of sensibility after irradiation. An Agilent 4155C semiconductor parameter analyzer was used to trace the parametric curve. X-rays were generated by a 14 MV Primus-Siemens linear accelerator. The results demonstrated that there is a correlation between the integrated dose applied to the phototransistor and the parametric response of the device. Studies are under way to determine how such behavior can provide information for the dosimetric planning in stereotactic radiosurgery. (author)

  7. Prediction of the cumulated dose for external beam irradiation of prostate cancer patients with 3D-CRT technique

    Directory of Open Access Journals (Sweden)

    Giżyńska Marta

    2016-03-01

    Full Text Available Nowadays in radiotherapy, much effort is taken to minimize the irradiated volume and consequently minimize doses to healthy tissues. In our work, we tested the hypothesis that the mean dose distribution calculated from a few first fractions can serve as prediction of the cumulated dose distribution, representing the whole treatment. We made our tests for 25 prostate cancer patients treated with three orthogonal fields technique. We did a comparison of dose distribution calculated as a sum of dose distribution from each fraction with a dose distribution calculated with isocenter shifted for a mean setup error from a few first fractions. The cumulative dose distribution and predicted dose distributions are similar in terms of gamma (3 mm 3% analysis, under condition that we know setup error from seven first fractions. We showed that the dose distribution calculated for the original plan with the isocenter shifted to the point, defined as the original isocenter corrected of the mean setup error estimated from the first seven fractions supports our hypothesis, i.e. can serve as a prediction for cumulative dose distribution.

  8. Radiologic imaging in cystic fibrosis: cumulative effective dose and changing trends over 2 decades.

    LENUS (Irish Health Repository)

    O'Connell, Oisin J

    2012-06-01

    With the increasing life expectancy for patients with cystic fibrosis (CF), and a known predisposition to certain cancers, cumulative radiation exposure from radiologic imaging is of increasing significance. This study explores the estimated cumulative effective radiation dose over a 17-year period from radiologic procedures and changing trends of imaging modalities over this period.

  9. Some hybrid models applicable to dose-response relationships

    International Nuclear Information System (INIS)

    Kumazawa, Shigeru

    1992-01-01

    A new type of models of dose-response relationships has been studied as an initial stage to explore a reliable extrapolation of the relationships decided by high dose data to the range of low dose covered by radiation protection. The approach is to use a 'hybrid scale' of linear and logarithmic scales; the first model is that the normalized surviving fraction (ρ S > 0) in a hybrid scale decreases linearly with dose in a linear scale, and the second is that the induction in a log scale increases linearly with the normalized dose (τ D > 0) in a hybrid scale. The hybrid scale may reflect an overall effectiveness of a complex system against adverse events caused by various agents. Some data of leukemia in the atomic bomb survivors and of rodent experiments were used to show the applicability of hybrid scale models. The results proved that proposed models fit these data not less than the popular linear-quadratic models, providing the possible interpretation of shapes of dose-response curves, e.g. shouldered survival curves varied by recovery time. (author)

  10. SU-D-16A-03: A Radiation Pneumonitis Dose-Response Model Incorporating Non- Local Radiation-Induced Bystander Effect

    International Nuclear Information System (INIS)

    Gordon, J; Snyder, K; Zhong, H; Chetty, I

    2014-01-01

    Purpose: Dose-response models that can reliably predict radiation pneumonitis (RP) to guide radiation therapy (RT) for lung cancer presently do not exist. A model is proposed that incorporates non-local radiationinduced bystander effect (RIBE). Methods: A single sigmoid response function, derived from published data for whole lung irradiation, relates RP probability to cumulative lung damage, regardless of fractionation scheme. Lung damage is assumed to be caused by direct local radiation damage, quantified via the linear-quadratic (LQ) model, and RIBE. Based on published data, RIBE is assumed to be activated when per-fraction dose rises above ∼0.6 Gy, but is constant with dose above that threshold. Integral RIBE damage is assumed proportional to lung volume irradiated above ∼0.6 Gy per fraction. Key model parameters include LQ α and β, and two RIBE parameters: the single-fraction probability δ of damage, and a proportionality parameter κ that relates the potential for RIBE damage to irradiated lung volume. All parameters are tentatively fitted from published data, the RIBE parameters from published RP rates for conventionally fractionated RT (CFRT) and stereotactic body RT (SBRT). Results: The model predicts dose-response curves that are consistent with clinical experience. It provides a tentative explanation for why V20 (33 fractions), V13 (20 fractions) and V5 (<10 fractions) are observed to be correlated with RP. It also provides a plausible explanation for the success of SBRT — RIBE damage increases with the number of fractions, so penalizes CFRT relative to SBRT. Conclusion: The proposed model is relatively simple, extrapolates from published data, plausibly explains several clinical observations, and produces dose-response curves that are consistent with clinical experience. While capable of elaboration, its ability to explain doseresponse experience with different fractionation schemes using a small number of assumptions and parameters is an

  11. SU-D-16A-03: A Radiation Pneumonitis Dose-Response Model Incorporating Non- Local Radiation-Induced Bystander Effect

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, J; Snyder, K; Zhong, H; Chetty, I [Henry Ford Health System, Dept. Radiation Oncology, Detroit, MI (United States)

    2014-06-01

    Purpose: Dose-response models that can reliably predict radiation pneumonitis (RP) to guide radiation therapy (RT) for lung cancer presently do not exist. A model is proposed that incorporates non-local radiationinduced bystander effect (RIBE). Methods: A single sigmoid response function, derived from published data for whole lung irradiation, relates RP probability to cumulative lung damage, regardless of fractionation scheme. Lung damage is assumed to be caused by direct local radiation damage, quantified via the linear-quadratic (LQ) model, and RIBE. Based on published data, RIBE is assumed to be activated when per-fraction dose rises above ∼0.6 Gy, but is constant with dose above that threshold. Integral RIBE damage is assumed proportional to lung volume irradiated above ∼0.6 Gy per fraction. Key model parameters include LQ α and β, and two RIBE parameters: the single-fraction probability δ of damage, and a proportionality parameter κ that relates the potential for RIBE damage to irradiated lung volume. All parameters are tentatively fitted from published data, the RIBE parameters from published RP rates for conventionally fractionated RT (CFRT) and stereotactic body RT (SBRT). Results: The model predicts dose-response curves that are consistent with clinical experience. It provides a tentative explanation for why V20 (33 fractions), V13 (20 fractions) and V5 (<10 fractions) are observed to be correlated with RP. It also provides a plausible explanation for the success of SBRT — RIBE damage increases with the number of fractions, so penalizes CFRT relative to SBRT. Conclusion: The proposed model is relatively simple, extrapolates from published data, plausibly explains several clinical observations, and produces dose-response curves that are consistent with clinical experience. While capable of elaboration, its ability to explain doseresponse experience with different fractionation schemes using a small number of assumptions and parameters is an

  12. The Roles of Macrobenthic Mollusks as Bioindicator in Response to Environmental Disturbance : Cumulative k-dominance curves and bubble plots ordination approaches

    Science.gov (United States)

    Putro, Sapto P.; Muhammad, Fuad; Aininnur, Amalia; Widowati; Suhartana

    2017-02-01

    Floating net cage is one of the aquaculture practice operated in Indonesian coastal areas that has been growing rapidly over the last two decades. This study is aimed to assess the roles of macrobenthic mollusks as bioindicator in response to environmental disturbance caused by fish farming activities, and compare the samples within the locations using graphical methods. The research was done at the floating net cage fish farming area in the Awerange Gulf, South Sulawesi, Indonesia at the coordinates between 79°0500‧- 79°1500‧ LS and 953°1500‧- 953°2000‧ BT, at the polyculture and reference areas, which was located 1 km away from farming area. Sampling period was conducted between October 2014 to June 2015. The sediment samples were taken from the two locations with two sampling time and three replicates using Van Veen Grab for biotic and abiotic assessment. Mollusks as biotic parameter were fixed using 4% formalin solution and were preserved using 70% ethanol solution after 1mm mesh size. The macrobenthic mollusks were found as many as 15 species consisting of 14 families and 2 classes (gastropods and bivalves). Based on cumulative k-dominance analysis projected on each station, the line of station K3T1 (reference area; first sampling time) and KJAB P3T2 (polyculture area; second sampling time) are located below others curves, indicating the highest evenness and diversity compared to the other stations, whereas station K2T1 (reference area; first sampling time) and K3T2 (polyculture area, second sampling time) are located on the top, indicate the lowest value of evenness and diversity. Based on the bubble plots NMDS ordination, the four dominant taxa/species did not clearly show involvement in driving/shifting the ordinate position of station on the graph, except T. agilis. However, the two species showed involvement in driving/shifting the ordinate position of two stations of the reference areas from the first sampling time by Rynoclavis sordidula

  13. Dose response of artificial irradiation of fluvial sediment sample for ESR dating

    International Nuclear Information System (INIS)

    Liu Chunru; Yin Gongming; Gao Lu; Li Jianping; Han Fei; Lin Min

    2011-01-01

    ESR dating samples need be irradiated to obtain dose response curve and the equivalent dose. The artificial dose rate is about 1 x 10 -1 -1 x 10 2 Gy/min, whereas the natural dose rate is about 3 Gy/ka. Therefore, one must be sure whether the much higher artificial dose rate is suitable for the ESR dating study. In this paper, we use different artificial dose rate to irradiate the same fluvial sample and measure the quartz Al centre ESR signal under the same conditions. The dose response curves are compared, in an attempt to gain a preliminary knowledge on that problem and build a good foundation for our ESR dating studies on fluvial samples. (authors)

  14. Maximum likelihood estimation of dose-response parameters for therapeutic operating characteristic (TOC) analysis of carcinoma of the nasopharynx

    International Nuclear Information System (INIS)

    Metz, C.E.; Tokars, R.P.; Kronman, H.B.; Griem, M.L.

    1982-01-01

    A Therapeutic Operating Characteristic (TOC) curve for radiation therapy plots, for all possible treatment doses, the probability of tumor ablation as a function of the probability of radiation-induced complication. Application of this analysis to actual therapeutic situation requires that dose-response curves for ablation and for complication be estimated from clinical data. We describe an approach in which ''maximum likelihood estimates'' of these dose-response curves are made, and we apply this approach to data collected on responses to radiotherapy for carcinoma of the nasopharynx. TOC curves constructed from the estimated dose-response curves are subject to moderately large uncertainties because of the limitations of available data.These TOC curves suggest, however, that treatment doses greater than 1800 rem may substantially increase the probability of tumor ablation with little increase in the risk of radiation-induced cervical myelopathy, especially for T1 and T2 tumors

  15. Patterns of prednisone use during pregnancy in women with rheumatoid arthritis: Daily and cumulative dose.

    Science.gov (United States)

    Palmsten, Kristin; Rolland, Matthieu; Hebert, Mary F; Clowse, Megan E B; Schatz, Michael; Xu, Ronghui; Chambers, Christina D

    2018-04-01

    To characterize prednisone use in pregnant women with rheumatoid arthritis using individual-level heat-maps and clustering individual trajectories of prednisone dose, and to evaluate the association between prednisone dose trajectory groups and gestational length. This study included pregnant women with rheumatoid arthritis who enrolled in the MotherToBaby Autoimmune Diseases in Pregnancy Study (2003-2014) before gestational week 20 and reported prednisone use without another oral glucocorticoid during pregnancy (n = 254). Information on medication use and pregnancy outcomes was collected by telephone interview plus by medical record review. Prednisone daily dose and cumulative dose were plotted by gestational day using a heat map for each individual. K-means clustering was used to cluster individual trajectories of prednisone dose into groups. The associations between trajectory group and demographics, disease severity measured by the Health Assessment Questionnaire at enrollment, and gestational length were evaluated. Women used prednisone 3 to 292 days during pregnancy, with daily doses ranging from <1 to 60 mg. Total cumulative dose ranged from 8 to 6225 mg. Disease severity, non-biologic disease modifying anti-rheumatic drug use, and gestational length varied significantly by trajectory group. After adjusting for disease severity, non-biologic disease modifying anti-rheumatic drug use, and other covariates, the highest vs lowest daily dose trajectory group was associated with reduced gestational age at delivery (β: -2.3 weeks (95%: -3.4, -1.3)), as was the highest vs lowest cumulative dose trajectory group (β: -2.6 weeks (95%: -3.6, -1.5)). In pregnant women with rheumatoid arthritis, patterns of higher prednisone dose were associated with shorter gestational length compared with lower dose. Copyright © 2018 John Wiley & Sons, Ltd.

  16. Response of human and rabbit lymphocytes to low doses of X-rays

    International Nuclear Information System (INIS)

    Fabry, L.

    1982-01-01

    The response of human and rabbit lymphocytes to low doses of X-rays was studied by the yields of dicentrics in first division metaphases. For both species, the dose-response curve was best fitted to the linear-quadratic model with a linear component predominating up to 67 and 42 rad respectively for man and rabbit. A calibration curve (5-400 rad) was obtained by combining the present results on man with previous data at higher doses. On the other hand, it appears that, at low doses, the radiosentivity of human lymphocytes is significantly higher than that of rabbit lymphocytes [fr

  17. Biological radiation dose estimation by chromosomal aberrations analysis in human peripheral blood (dose- effect curve)

    International Nuclear Information System (INIS)

    Al Achkar, W.

    2002-01-01

    In order to draw a dose-effect curve, blood from eight healthy people were studied. Samples were irradiated in tubes with 0.15-2.5 gray of gamma ray.Irradiated and control samples were incubated for cell cultures. Chromosomal aberrations from 67888 metaphases were scored. Curves from the total number of dicentrics, dicentrics+ rings and total numbers of breaks were drawn. The yield of chromosome aberrations is related to the dose used. These curves give a quick useful estimation of the accidentally radiation exposure. (author)

  18. Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry

    International Nuclear Information System (INIS)

    Sohrabpour, M.; Hassanzadeh, M.; Shahriari, M.; Sharifzadeh, M.

    2002-01-01

    The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators

  19. Dose-effect Curve for X-radiation in Lymphocytes in Goats

    International Nuclear Information System (INIS)

    Hasanbasic, D.; Saracevic, L.; Sacirbegovic, A.

    1998-01-01

    Dose-effect curve for X-radiation was made based on the analysis of chromosome aberrations in lympocytes of goats. Blood samples from seven goats were irradiated using MOORHEAD method, slightly modified and adapted to our conditions. Linear-square model was used, and the dose-effect curves were fitted by the smallest squares method. Dose-effect curve (collective) for goats is displayed as the following expression: y(D)= 8,6639·10 -3 D + 2,9748·10 -2 D 2 +2,9475·10 -3 . Comparison with some domestic animals such as sheep and pigs showed differences not only with respect to linear-square model, but to other mathematical presentations as well. (author)

  20. Dose-response relationship for chromosomal aberrations induced in human lymphocytes by 18 MeV electron beam irradiation

    International Nuclear Information System (INIS)

    Lashin, E.A.; Elaasar, E.M.; Moustafa, H.F.; Bakir, Y.Y.; Al Zenki, S.D.

    1990-01-01

    Dose response curves for lymphocyte chromosome aberration frequencies using X- and gamma radiation became an important and reliable indicator as biological dosimeter especially in radiation accidents and occupational over exposures. Nowadays electron beam therapy is frequently used for their advantages in cases of tumours under or near to the body surface. Dose-response curves for these electron beams are rarely published. Human peripheral blood lymphocytes were in vitro irradiated with various low and high doses (0.1 Gy to 4.9 Gy) of 18 MeV electron beams to utilize such a dose-response curve using chromosomal aberration frequencies as a biological indicator. Then we compared the biological curve with physically obtained curves normally used in planning for radiotherapy treatment. It is interesting to find a significant difference between both of them. The biological curve is generally higher in value and the aberrations induced by 93% of a dose is significantly higher and deeper in site than those aberrations induced by the 100% dose calculated physically. If the above observation is confirmed by detailed studies, it would be of importance to the radiotherapist to plan for isodose curves according to biological determinations. (author)

  1. Biological radiation dose estimation by chromosomal aberrations analysis in human peripheral blood (dose-effect curve)

    International Nuclear Information System (INIS)

    Al-Achkar, W.

    2001-09-01

    In order to draw a dose-effect curve, experimentally gamma ray induced chromosomal aberrations in human peripheral lymphocytes from eight healthy people were studied. Samples from 4 males and 4 females were irradiated in tubes with 0.15, 0.25, 0.5, 1, 1.5, 2, 2.5 gray of gamma ray (Co 60 at dose rate 0.3 Gy/min). Irradiated and control samples were incubated in 37 centigrade for 48 hours cell cultures. Cell cultures then were stopped and metaphases spread, Giemsa stained to score the induced chromosomal aberrations. Chromosomal aberrations from 67888 metaphases were scored. Curves from the total number of dicentrics, dicentrics + rings and total numbers of breaks in cell for each individual or for all people were drawn. An increase of all chromosomal aberrations types with the elevation of the doses was observed. The yield of chromosome aberrations is related to the dose used. These curves give a quick useful estimation of the accidentally radiation exposure. (author)

  2. Depth dose curves from 90Sr+90Y clinical applicators using the thermoluminescent technique

    International Nuclear Information System (INIS)

    Antonio, Patricia L.; Caldas, Linda V.E.; Oliveira, Mercia L.

    2009-01-01

    The 90 Sr+ 90 Y beta-ray sources widely used in brachytherapy applications were developed in the 1950's. Many of these sources, called clinical applicators, are still routinely used in several Brazilian radiotherapy clinics for the treatment of superficial lesions in the skin and eyes, although they are not commercialized anymore. These applicators have to be periodically calibrated, according to international recommendations, because these sources have to be very well specified in order to reach the traceability of calibration standards. In the case of beta-ray sources, the recommended quantity is the absorbed dose rate in water at a reference distance from the source. Moreover, there are other important quantities, as the depth dose curves and the source uniformity for beta-ray plaque sources. In this work, depth dose curves were obtained and studied of five dermatological applicators, using thin thermoluminescent dosimeters of CaSO 4 :Dy and phantoms of PMMA with different thicknesses (between 1.0 mm and 5.0 mm) positioned between each applicator and the TL pellets. The depth dose curves obtained presented the expected attenuation response in PMMA, and the results were compared with data obtained for a 90 Sr+ 90 Y standard source reported by the IAEA, and they were considered satisfactory. (author)

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

    Science.gov (United States)

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

    2016-09-01

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

  4. TL response of citrine samples for high-dose dosimetry

    International Nuclear Information System (INIS)

    Teixeira, Maria Ines; Caldas, Linda V.E.

    2011-01-01

    The possibility of using samples of Brazilian stones as quartz, amethyst, topaz, etc. for high-dose dosimetry has been studied in recent years at IPEN, using the thermoluminescence technique (TL). In this work, the TL properties of citrine samples were studied. They were exposed to different doses of gamma radiation ( 60 Co). The natural citrine stone was extracted from a mine in Minas Gerais state, Brazil; it is a tectosilicate ranked as one of three-dimensional structure, showing clear yellow to golden brown color. The natural citrine stone is classified as quartz (SiO 2 ), and it has a lower symmetry and more compact reticulum. The citrine stone samples were powdered, and the selected grains were mixed with Teflon in the proportion 2 (Teflon):1 (Citrine). The mixture was pressed and sintered for production of Citrine -Teflon pellets of 50 mg. The TL emission curve showed two peaks at 160 deg C and 220 deg C. To remove the TL peak (160 deg C) of the sintered citrine pellet glow curves, different thermal treatments were tested during several time intervals. The TL dose-response curve between 50 Gy and 100 kGy, the reproducibility of TL response and the lower detection dose were obtained. The preliminary results show that citrine may be useful for high-dose dosimetry. (author)

  5. Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film

    Directory of Open Access Journals (Sweden)

    Tatsuhiro Gotanda

    2016-01-01

    Full Text Available Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

  6. Dose response on the 110 °C thermoluminescence peak of un-heated, synthetic Merck quartz

    Energy Technology Data Exchange (ETDEWEB)

    Kaya Keleş, Şule, E-mail: sule.kaya@ankara.edu.tr; Meriç, Niyazi; Polymeris, George S.

    2016-07-15

    Studies on 110 °C TL peak have been carried out using natural quartz from different origins and synthetic quartz produced by different suppliers. The interest in quartz is due to its usage in dating and retrospective dosimetry as a main material; both synthetic and natural types of quartz yield the 110 °C TL peak in their glow curve. In most studies to understand the physical mechanism behind the TL system, synthetic quartz samples are used and there are many investigations about dose response, in both low and high radiation dose region. In these studies generally synthetic quartz samples produced by Sawyer Research Products are used and the studies showed that both heated and un-heated synthetic quartz samples have intense supra-linear responses. Supra-linearity was enhanced by applying a pre-irradiation while several models have been developed towards an explanation to these supra-linearity effects. In this study commercially available synthetic Merck quartz was used. Different combinations of optical filters were used to obtain dose response curves upto 266 Gy and the effect of pre-dose to these dose response curves was studied. Un-pre-dosed Merck quartz samples dose supra-linearity index is below 1 independently on the optical filters; so Merck quartz showed linear or sub-linear dose response.

  7. Evaluation of the learning curve for external cephalic version using cumulative sum analysis.

    Science.gov (United States)

    Kim, So Yun; Han, Jung Yeol; Chang, Eun Hye; Kwak, Dong Wook; Ahn, Hyun Kyung; Ryu, Hyun Mi; Kim, Moon Young

    2017-07-01

    We evaluated the learning curve for external cephalic version (ECV) using learning curve-cumulative sum (LC-CUSUM) analysis. This was a retrospective study involving 290 consecutive cases between October 2013 and March 2017. We evaluated the learning curve for ECV on nulli and over para 1 group using LC-CUSUM analysis on the assumption that 50% and 70% of ECV procedures succeeded by description a trend-line of quadratic function with reliable R 2 values. The overall success rate for ECV was 64.8% (188/290), while the success rate for nullipara and over para 1 groups was 56.2% (100/178) and 78.6% (88/112), respectively. 'H' value, that the actual failure rate does not differ from the acceptable failure rate, was -3.27 and -1.635 when considering ECV success rates of 50% and 70%, respectively. Consequently, in order to obtain a consistent 50% success rate, we would require 57 nullipara cases, and in order to obtain a consistent 70% success rate, we would require 130 nullipara cases. In contrast, 8 to 10 over para 1 cases would be required for an expected success rate of 50% and 70% on over para 1 group. Even a relatively inexperienced physician can experience success with multipara and after accumulating experience, they will manage nullipara cases. Further research is required for LC-CUSUM involving several practitioners instead of a single practitioner. This will lead to the gradual implementation of standard learning curve guidelines for ECV.

  8. Cumulative effective dose and cancer risk for pediatric population in repetitive full spine follow-up imaging: How micro dose is the EOS microdose protocol?

    Science.gov (United States)

    Law, Martin; Ma, Wang-Kei; Lau, Damian; Cheung, Kenneth; Ip, Janice; Yip, Lawrance; Lam, Wendy

    2018-04-01

    To evaluate and to obtain analytic formulation for the calculation of the effective dose and associated cancer risk using the EOS microdose protocol for scoliotic pediatric patients undergoing full spine imaging at different age of exposure; to demonstrate the microdose protocol capable of delivering lesser radiation dose and hence of further reducing cancer risk induction when compared with the EOS low dose protocol; to obtain cumulative effective dose and cancer risk for both genders scoliotic pediatrics of US and Hong Kong population using the microdose protocol. Organ absorbed doses of full spine exposed scoliotic pediatric patients have been simulated with the use of EOS microdose protocol imaging parameters input to the Monte Carlo software PCXMC. Gender and age specific effective dose has been calculated with the simulated organ absorbed dose using the ICRP-103 approach. The associated radiation induced cancer risk, expressed as lifetime attributable risk (LAR), has been estimated according to the method introduced in the Biological Effects of Ionizing Radiation VII report. Values of LAR have been estimated for scoliotic patients exposed repetitively during their follow up period at different age for US and Hong Kong population. The effective doses of full spine imaging with simultaneous posteroanterior and lateral projection for patients exposed at the age between 5 and 18 years using the EOS microdose protocol have been calculated within the range of 2.54-14.75 μSv. The corresponding LAR for US and Hong Kong population was ranged between 0.04 × 10 -6 and 0.84 × 10 -6 . Cumulative effective dose and cancer risk during follow-up period can be estimated using the results and are of information to patients and their parents. With the use of computer simulation and analytic formulation, we obtained the cumulative effective dose and cancer risk at any age of exposure for pediatric patients of US and Hong Kong population undergoing repetitive

  9. A method to adjust radiation dose-response relationships for clinical risk factors

    DEFF Research Database (Denmark)

    Appelt, Ane Lindegaard; Vogelius, Ivan R

    2012-01-01

    Several clinical risk factors for radiation induced toxicity have been identified in the literature. Here, we present a method to quantify the effect of clinical risk factors on radiation dose-response curves and apply the method to adjust the dose-response for radiation pneumonitis for patients...

  10. Analysis of thermal-dose response to heat

    International Nuclear Information System (INIS)

    Storm, F.; Roe, D.; Drury, B.

    1987-01-01

    The authors reasoned that if hyperthermia alone has a clinical anti-tumor effect, response should have a thermal dose relationship. The authors analyzed 100 patients with advanced cancer treated with magnetic-induction. Three methods of determining thermal dose were used: (A) t1x10, the lowest temperature sustained throughout the tumor for 30-60min during the first of ten daily treatments, which represents one usual course of ten hourly sessions; (B) t43 (equivalent minutes at 43C) which accounts for non-linear tumor heating by combining serially measured temperatures during the first treatment with a mathematical description of the time-temperature relationship for thermal inactivation or damage; (C) Ct43 (cumulative t43), which represents the t43 value multiplied by the actual number of subsequent daily treatments received. Response was defined as CR+PR+MR. The results show a statistically significant effect of heat alone for t1x10, t43, and Ct43. These analyses demonstrate a thermal-dose relationship between hyperthermia therapy and tumor response as a sole independent variable, which indicates that heat therapy has clinical anti-cancer activity

  11. Ranitidine Can Potentiate The Prokinetic Effect Of Itopride At Low Doses- An In Vitro Study.

    Science.gov (United States)

    Butt, Aroosa Ishtiaq; Khan, Bushra Tayyaba; Khan, Asma; Khan, Qamar-Uz-Zaman

    2017-01-01

    Gastroparesis and GERD occur concomitantly in 40 percent of the cases. Prokinetic drugs and acid blockers are employed as the main treatment modality. Ranitidine is an acid blocker with additional prokinetic activity and Itopride is a known prokinetic drug. This study was designed to observe the synergistic potentiating prokinetic effect of Ranitidine on itopride on isolated duodenum of rabbits. Ranitidine (10-5-10-3) and itopride (10-6-10-5) were added in increasing concentrations to isolated duodenum of rabbits and contractions were recorded on PowerLab Data acquisition unit AHK/214. Cumulative dose response curves were constructed. The potentiating prokinetic effect of Ranitidine on itopride was seen by using a fixed dose of ranitidine and cumulatively enhancing doses of itopride on iWorx. Ranitidine and itopride produced a dose dependent reversible contraction of the isolated tissue of rabbits with ranitidine showing a max response of 0.124mV and itopride showing a maximum response of 0.131mV. Ranitidine was able to potentiate the prokinetic effect of itopride at low doses but at high dose the effect began to wane off. Ranitidine and itopride produce a statistically significant synergistic potentiating prokinetic effect at low doses in vitro.

  12. Use of three-dimensional lognormal dose-response surfaces in lifetime studies of radiation-induced cancer

    International Nuclear Information System (INIS)

    Raabe, O.G.

    1986-01-01

    The three-dimensional lognormal cumulative probability power function was used to provide a unifying dose-response description of the lifetime cancer risk for chronic exposure of experimental animals and people, for risk evaluation, and for scaling between species. Bone tumor fatilities, primarily from alpha irradiation of the skeleton in lifetime studies of beagles injected with 226 Ra, were shown to be well described by this function. This function described cancer risk in lifetime studies as a curved smooth surface depending on radiation exposure rate and elapsed time, such that the principal risk at low dose rates occurred near the end of the normal life span without significant life shortening. Essentially identical functions with the median value of the power function displaced with respect to appropriate RBE values were shown to describe bone-cancer induction primarily from alpha irradiation of the skeleton in lifetime beagle studies with injected 226 Ra, 228 Th, 239 Pu and 241 Am, and with inhaled 238 Pu. Application of this model to human exposures to 226 Ra yielded a response ratio of 3.6; that is, the time required for development of bone cancer in people was 3.6 times longer than for beagles at the same average skeletal dose rate. It was suggested that similar techniques were appropriate to other carcinogens and other critical organs. 20 refs., 8 figs., 3 tabs

  13. Estimated cumulative radiation dose received by diagnostic imaging during staging and treatment of operable Ewing sarcoma 2005-2012

    International Nuclear Information System (INIS)

    Johnsen, Boel; Fasmer, Kristine Eldevik; Boye, Kjetil; Rosendahl, Karen; Aukland, Stein Magnus; Trovik, Clement; Biermann, Martin

    2017-01-01

    Patients with Ewing sarcoma are subject to various diagnostic procedures that incur exposure to ionising radiation. To estimate the radiation doses received from all radiologic and nuclear imaging episodes during diagnosis and treatment, and to determine whether 18 F-fluorodeoxyglucose positron emission tomography - computed tomography ( 18 F-FDG PET-CT) is a major contributor of radiation. Twenty Ewing sarcoma patients diagnosed in Norway in 2005-2012 met the inclusion criteria (age <30 years, operable disease, uncomplicated chemotherapy and surgery, no metastasis or residual disease within a year of diagnosis). Radiation doses from all imaging during the first year were calculated for each patient. The mean estimated cumulative radiation dose for all patients was 34 mSv (range: 6-70), radiography accounting for 3 mSv (range: 0.2-12), CT for 13 mSv (range: 2-28) and nuclear medicine for 18 mSv (range: 2-47). For the patients examined with PET-CT, the mean estimated cumulative effective dose was 38 mSv, of which PET-CT accounted for 14 mSv (37%). There was large variation in number and type of examinations performed and also in estimated cumulative radiation dose. The mean radiation dose for patients examined with PET-CT was 23% higher than for patients not examined with PET-CT. (orig.)

  14. The Antiproton Depth-Dose Curve in Water

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Jäkel, Oliver

    2008-01-01

    We have measured the depth-dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge...

  15. Cumulative cisplatin dose in concurrent chemoradiotherapy for head and neck cancer : A systematic review

    NARCIS (Netherlands)

    Strojan, Primoz; Vermorken, Jan B.; Beitler, Jonathan J.; Saba, Nabil F.; Haigentz, Missak; Bossi, Paolo; Worden, Francis P.; Langendijk, Johannes A.; Eisbruch, Avraham; Mendenhall, William M.; Lee, Anne W. M.; Harrison, Louis B.; Bradford, Carol R.; Smee, Robert; Silver, Carl E.; Rinaldo, Alessandra; Ferlito, Alfio

    Background. The optimal cumulative dose and timing of cisplatin administration in various concurrent chemoradiotherapy protocols for nonmetastatic head and neck squamous cell carcinoma (HNSCC) has not been determined. Methods. The absolute survival benefit at 5 years of concurrent chemoradiotherapy

  16. Establishment and validation of a dose-effect curve for γ-rays by cytogenetic analysis

    International Nuclear Information System (INIS)

    Barquinero, Joan F.; Caballin, Maria Rosa; Barrios, Leonardo; Ribas, Montserrat; Miro, Rosa; Egozcue, Josep

    1995-01-01

    A dose-effect curve obtained by analysis of dicentric chromosomes after irradiation of peripheral blood samples, from one donor, at 11 different doses of γ-rays is presented. For the elaboration of this curve, more than 18,000 first division metaphases have been analyzed. The results fit very well to the linear-quadratic model. To validate the curve, samples from six individuals (three controls and three occupationally exposed persons) were irradiated at 2 Gy. The results obtained, when compared with the curve, showed that in all cases the 95% confidence interval included the 2 Gy dose, with estimated dose ranges from 1.82 to 2.19 Gy

  17. Dose-response investigation into glucose facilitation of memory performance and mood in healthy young adults.

    Science.gov (United States)

    Sünram-Lea, Sandra I; Owen, Lauren; Finnegan, Yvonne; Hu, Henglong

    2011-08-01

    It has been suggested that the memory enhancing effect of glucose follows an inverted U-shaped curve, with 25 g resulting in optimal facilitation in healthy young adults. The aim of this study was to further investigate the dose dependency of the glucose facilitation effect in this population across different memory domains and to assess moderation by interindividual differences in glucose regulation and weight. Following a double-blind, repeated measures design, 30 participants were administered drinks containing five different doses of glucose (0 g, 15 g, 25 g, 50 g, and 60 g) and were tested across a range of memory tasks. Glycaemic response and changes in mood state were assessed following drink administration. Analysis of the data showed that glucose administration did not affect mood, but significant glucose facilitation of several memory tasks was observed. However, dose-response curves differed depending on the memory task with only performance on the long-term memory tasks adhering largely to the previously observed inverted U-shaped dose-response curve. Moderation of the response profiles by interindividual differences in glucose regulation and weight was observed. The current data suggest that dose-response function and optimal dose might depend on cognitive domain and are moderated by interindividual differences in glucose regulation and weight.

  18. Equivalent intraperitoneal doses of ibuprofen supplemented in drinking water or in diet: a behavioral and biochemical assay using antinociceptive and thromboxane inhibitory dose–response curves in mice

    Directory of Open Access Journals (Sweden)

    Raghda A.M. Salama

    2016-07-01

    Full Text Available Background. Ibuprofen is used chronically in different animal models of inflammation by administration in drinking water or in diet due to its short half-life. Though this practice has been used for years, ibuprofen doses were never assayed against parenteral dose–response curves. This study aims at identifying the equivalent intraperitoneal (i.p. doses of ibuprofen, when it is administered in drinking water or in diet. Methods. Bioassays were performed using formalin test and incisional pain model for antinociceptive efficacy and serum TXB2 for eicosanoid inhibitory activity. The dose–response curve of i.p. administered ibuprofen was constructed for each test using 50, 75, 100 and 200 mg/kg body weight (b.w.. The dose–response curves were constructed of phase 2a of the formalin test (the most sensitive phase to COX inhibitory agents, the area under the ‘change in mechanical threshold’-time curve in the incisional pain model and serum TXB2 levels. The assayed ibuprofen concentrations administered in drinking water were 0.2, 0.35, 0.6 mg/ml and those administered in diet were 82, 263, 375 mg/kg diet. Results. The 3 concentrations applied in drinking water lay between 73.6 and 85.5 mg/kg b.w., i.p., in case of the formalin test; between 58.9 and 77.8 mg/kg b.w., i.p., in case of the incisional pain model; and between 71.8 and 125.8 mg/kg b.w., i.p., in case of serum TXB2 levels. The 3 concentrations administered in diet lay between 67.6 and 83.8 mg/kg b.w., i.p., in case of the formalin test; between 52.7 and 68.6 mg/kg b.w., i.p., in case of the incisional pain model; and between 63.6 and 92.5 mg/kg b.w., i.p., in case of serum TXB2 levels. Discussion. The increment in pharmacological effects of different doses of continuously administered ibuprofen in drinking water or diet do not parallel those of i.p. administered ibuprofen. It is therefore difficult to assume the equivalent parenteral daily doses based on mathematical calculations.

  19. The impact of pediatric-specific dose modulation curves on radiation dose and image quality in head computed tomography

    International Nuclear Information System (INIS)

    Santos, Joana; Paulo, Graciano; Foley, Shane; Rainford, Louise; McEntee, Mark F.

    2015-01-01

    The volume of CT examinations has increased with resultant increases in collective dose values over the last decade. To analyze the impact of the tube current and voltage modulation for dose values and image quality of pediatric head CT examinations. Head CT examinations were performed on anthropomorphic phantoms and four pediatric age categories before and after the introduction of dedicated pediatric curves for tube voltage and current modulation. Local diagnostic reference levels were calculated. Visual grading characteristic image quality evaluation was performed by four pediatric neuroradiologists and image noise comparisons were performed. Pediatric-specific modulation curves demonstrated a 49% decrease in mean radiation dose for phantom examinations. The local diagnostic reference levels (CTDIvol) for clinical examinations decreased by 52%, 41%, 46% and 40% for newborn, 5-, 10- and 15-year-old patients, respectively. Visual grading characteristic image quality was maintained for the majority of age categorizations (area under the curve = 0.5) and image noise measurements did not change (P = 0.693). Pediatric-specific dose modulation curves resulted in an overall mean dose reduction of 45% with no significant differences in subjective or objective image quality findings. (orig.)

  20. The impact of pediatric-specific dose modulation curves on radiation dose and image quality in head computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Joana; Paulo, Graciano [Instituto Politecnico de Coimbra, ESTESC, DMIR, Coimbra (Portugal); Foley, Shane; Rainford, Louise [University College Dublin, School of Medicine and Medical Science, Health Science Centre, Dublin 4 (Ireland); McEntee, Mark F. [The University of Sydney, Faculty of Health Sciences, Cumberland Campus, Sydney (Australia)

    2015-11-15

    The volume of CT examinations has increased with resultant increases in collective dose values over the last decade. To analyze the impact of the tube current and voltage modulation for dose values and image quality of pediatric head CT examinations. Head CT examinations were performed on anthropomorphic phantoms and four pediatric age categories before and after the introduction of dedicated pediatric curves for tube voltage and current modulation. Local diagnostic reference levels were calculated. Visual grading characteristic image quality evaluation was performed by four pediatric neuroradiologists and image noise comparisons were performed. Pediatric-specific modulation curves demonstrated a 49% decrease in mean radiation dose for phantom examinations. The local diagnostic reference levels (CTDIvol) for clinical examinations decreased by 52%, 41%, 46% and 40% for newborn, 5-, 10- and 15-year-old patients, respectively. Visual grading characteristic image quality was maintained for the majority of age categorizations (area under the curve = 0.5) and image noise measurements did not change (P = 0.693). Pediatric-specific dose modulation curves resulted in an overall mean dose reduction of 45% with no significant differences in subjective or objective image quality findings. (orig.)

  1. Estimated cumulative radiation dose received by diagnostic imaging during staging and treatment of operable Ewing sarcoma 2005-2012

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Boel [Haukeland University Hospital, Centre for Nuclear Medicine and PET, Department of Radiology, P.O. Box 1400, Bergen (Norway); Fasmer, Kristine Eldevik [Haukeland University Hospital, Department of Oncology, Medical Physics Section, Bergen (Norway); Boye, Kjetil [Norwegian Radium Hospital, Oslo University Hospital, Department of Oncology, Oslo (Norway); Rosendahl, Karen; Aukland, Stein Magnus [Haukeland University Hospital, Department of Radiology, Paediatric Section, Bergen (Norway); University of Bergen, Department of Clinical Medicine, Bergen (Norway); Trovik, Clement [University of Bergen, Department of Clinical Medicine, Bergen (Norway); Haukeland University Hospital, Department of Surgery, Orthopaedic Section, Bergen (Norway); Biermann, Martin [Haukeland University Hospital, Centre for Nuclear Medicine and PET, Department of Radiology, P.O. Box 1400, Bergen (Norway); University of Bergen, Department of Clinical Medicine, Bergen (Norway)

    2017-01-15

    Patients with Ewing sarcoma are subject to various diagnostic procedures that incur exposure to ionising radiation. To estimate the radiation doses received from all radiologic and nuclear imaging episodes during diagnosis and treatment, and to determine whether {sup 18}F-fluorodeoxyglucose positron emission tomography - computed tomography ({sup 18}F-FDG PET-CT) is a major contributor of radiation. Twenty Ewing sarcoma patients diagnosed in Norway in 2005-2012 met the inclusion criteria (age <30 years, operable disease, uncomplicated chemotherapy and surgery, no metastasis or residual disease within a year of diagnosis). Radiation doses from all imaging during the first year were calculated for each patient. The mean estimated cumulative radiation dose for all patients was 34 mSv (range: 6-70), radiography accounting for 3 mSv (range: 0.2-12), CT for 13 mSv (range: 2-28) and nuclear medicine for 18 mSv (range: 2-47). For the patients examined with PET-CT, the mean estimated cumulative effective dose was 38 mSv, of which PET-CT accounted for 14 mSv (37%). There was large variation in number and type of examinations performed and also in estimated cumulative radiation dose. The mean radiation dose for patients examined with PET-CT was 23% higher than for patients not examined with PET-CT. (orig.)

  2. Dose Response of Alanine Detectors Irradiated with Carbon Ion Beams

    DEFF Research Database (Denmark)

    Herrmann, Rochus; Jäkel, Oliver; Palmans, Hugo

    2011-01-01

    Purpose: The dose response of the alanine detector shows a dependence on particle energy and type, when irradiated with ion beams. The purpose of this study is to investigate the response behaviour of the alanine detector in clinical carbon ion beams and compare the results with model predictions......-dose curves deviate from predictions in the peak region, most pronounced at the distal edge of the peak. Conclusions: The used model and its implementation show a good overall agreement for quasi mono energetic measurements. Deviations in depth-dose measurements are mainly attributed to uncertainties...

  3. Cumulative radiation dose caused by radiologic studies in critically ill trauma patients.

    Science.gov (United States)

    Kim, Patrick K; Gracias, Vicente H; Maidment, Andrew D A; O'Shea, Michael; Reilly, Patrick M; Schwab, C William

    2004-09-01

    Critically ill trauma patients undergo many radiologic studies, but the cumulative radiation dose is unknown. The purpose of this study was to estimate the cumulative effective dose (CED) of radiation resulting from radiologic studies in critically ill trauma patients. The study group was composed of trauma patients at an urban Level I trauma center with surgical intensive care unit length of stay (LOS) greater than 30 days. The radiology records were reviewed. A typical effective dose per study for each type of plain film radiograph, computed tomographic scan, fluoroscopic study, and nuclear medicine study was used to calculate CED. Forty-six patients met criteria. The mean surgical intensive care unit and hospital LOS were 42.7 +/- 14.0 and 59.5 +/- 28.5 days, respectively. The mean Injury Severity Score was 32.2 +/- 15.0. The mean number of studies per patient was 70.1 +/- 29.0 plain film radiographs, 7.8 +/- 4.1 computed tomographic scans, 2.5 +/- 2.6 fluoroscopic studies, and 0.065 +/- 0.33 nuclear medicine study. The mean CED was 106 +/- 59 mSv per patient (range, 11-289 mSv; median, 104 mSv). Among age, mechanism, Injury Severity Score, and LOS, there was no statistically significant predictor of high CED. The mean CED in the study group was 30 times higher than the average yearly radiation dose from all sources for individuals in the United States. The theoretical additional morbidity attributable to radiologic studies was 0.78%. From a radiobiologic perspective, risk-to-benefit ratios of radiologic studies are favorable, given the importance of medical information obtained. Current practice patterns regarding use of radiologic studies appear to be acceptable.

  4. Continuous dose-response relationship of the LDL-cholesterol-lowering effect of phytosterol intake.

    Science.gov (United States)

    Demonty, Isabelle; Ras, Rouyanne T; van der Knaap, Henk C M; Duchateau, Guus S M J E; Meijer, Linsie; Zock, Peter L; Geleijnse, Johanna M; Trautwein, Elke A

    2009-02-01

    Phytosterols (plant sterols and stanols) are well known for their LDL-cholesterol (LDL-C)-lowering effect. A meta-analysis of randomized controlled trials in adults was performed to establish a continuous dose-response relationship that would allow predicting the LDL-C-lowering efficacy of different phytosterol doses. Eighty-four trials including 141 trial arms were included. A nonlinear equation comprising 2 parameters (the maximal LDL-C lowering and an incremental dose step) was used to describe the dose-response curve. The overall pooled absolute (mmol/L) and relative (%) LDL-C-lowering effects of phytosterols were also assessed with a random effects model. The pooled LDL-C reduction was 0.34 mmol/L (95% CI: -0.36, -0.31) or 8.8% (95% CI: -9.4, -8.3) for a mean daily dose of 2.15 g phytosterols. The impacts of subject baseline characteristics, food formats, type of phytosterols, and study quality on the continuous dose-response curve were determined by regression or subgroup analyses. Higher baseline LDL-C concentrations resulted in greater absolute LDL-C reductions. No significant differences were found between dose-response curves established for plant sterols vs. stanols, fat-based vs. non fat-based food formats and dairy vs. nondairy foods. A larger effect was observed with solid foods than with liquid foods only at high phytosterol doses (>2 g/d). There was a strong tendency (P = 0.054) towards a slightly lower efficacy of single vs. multiple daily intakes of phytosterols. In conclusion, the dose-dependent LDL-C-lowering efficacy of phytosterols incorporated in various food formats was confirmed and equations of the continuous relationship were established to predict the effect of a given phytosterol dose. Further investigations are warranted to investigate the impact of solid vs. liquid food formats and frequency of intake on phytosterol efficacy.

  5. The evolutionary reserve cell concept and model of cellular response induced by low doses of radiation

    International Nuclear Information System (INIS)

    Spitkovsky, D.M.; Talyzina, T.A.

    1995-01-01

    The model is based on the concept of programmed initiation of genetic damage in sub-populations of specific evolutionary reserve cells (ERC). The model quantitatively predicts a dose response of genetic lesions at low dose range and furnishes an explanation of the minimum observed in the dose-response curve at doses corresponding to one (on the average) event of energy deposition per ERC. The complex shape of the dose-response curve is demonstrated to result from superposition of processes in different sub-populations within the exposed cell population (at low doses mainly in ERC). Programmed initiation of genetic lesions in ERC requires two hits to cell membrane and probably, at the same time, to the cell nucleus. The equation for dicentric yield in human lymphocytes as a function of dose describes the experimental observations rather well. (Author)

  6. Measurement of soil contamination by radionuclides due to the Fukushima Dai-ichi Nuclear Power Plant accident and associated estimated cumulative external dose estimation

    International Nuclear Information System (INIS)

    Endo, S.; Kimura, S.; Takatsuji, T.; Nanasawa, K.; Imanaka, T.; Shizuma, K.

    2012-01-01

    Soil sampling was carried out at an early stage of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Samples were taken from areas around FDNPP, at four locations northwest of FDNPP, at four schools and in four cities, including Fukushima City. Radioactive contaminants in soil samples were identified and measured by using a Ge detector and included 129m Te, 129 Te, 131 I, 132 Te, 132 I, 134 Cs, 136 Cs, 137 Cs, 140 Ba and 140 La. The highest soil depositions were measured to the northwest of FDNPP. From this soil deposition data, variations in dose rates over time and the cumulative external doses at the locations for 3 months and 1 y after deposition were estimated. At locations northwest of FDNPP, the external dose rate at 3 months after deposition was 4.8–98 μSv/h and the cumulative dose for 1 y was 51 to 1.0 × 10 3 mSv; the highest values were at Futaba Yamada. At the four schools, which were used as evacuation shelters, and in the four urban cities, the external dose rate at 3 months after deposition ranged from 0.03 to 3.8 μSv/h and the cumulative doses for 1 y ranged from 3 to 40 mSv. The cumulative dose at Fukushima Niihama Park was estimated as the highest in the four cities. The estimated external dose rates and cumulative doses show that careful countermeasures and remediation will be needed as a result of the accident, and detailed measurements of radionuclide deposition densities in soil will be important input data to conduct these activities.

  7. The induction by x rays of chromosome aberrations in male guinea-pigs, rabbits and golden hamsters. 3. Dose-response relationship after single doses of X-rays to spermatogonia

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, M F; Cox, B D

    1975-09-01

    The induction by X-rays of translocations in spermatogonia was studied by cytological means in spermatocytes derived from them. In the rabbit and guinea-pig, hump-shaped dose-response curves were obtained, with a linear relationship at the low doses. The shapes of the curves were similar to those reported for the mouse, except that the maximum occurred at 600-700 rad in the mouse as opposed to 300 rad in the guinea-pig and rabbit. Unlike the guinea-pig and rabbit, the golden hamster showed a hump dose-response curve without a definite peak value and with little decrease in yield at high radiation doses. Over the low dose range 100-300 rad, the slopes of the curves of translocation yield were in the order: mouse (highest), rabbit, guinea-pig and hamster. Data on sterile periods suggested that the amount of spermatogonial killing in the rabbit and guinea-pig was as great or greater than in the mouse, and that in the golden hamster it was most severe. It is suggested that the differing shapes of the dose-response curves can be explained by a lower sensitivity to translocation induction in the test species and, also especially in the golden hamster, a greater sensitivity to cell killing. The possibility of extrapolating from these data to other species is discussed.

  8. Effects of different premature chromosome condensation method on dose-curve of 60Co γ-ray

    International Nuclear Information System (INIS)

    Guo Yicao; Yang Haoxian; Yang Yuhua; Li Xi'na; Huang Weixu; Zheng Qiaoling

    2012-01-01

    Objective: To study the effect of traditional method and improved method of the premature chromosome condensation (PCC) on the dose-effect curve of 60 Co γ ray, for choosing the rapid and accurate biological dose estimating method for the accident emergency. Methods: Collected 3 healthy male cubits venous blood (23 to 28 years old), and irradiated by 0, 1.0, 5.0, 10.0, 15.0, 20.0 Gy 60 Co γ ray (absorbed dose rate: 0.635 Gy/min). Observed the relation of dose-effect curve in the 2 incubation time (50 hours and 60 hours) of the traditional method and improved method. Used the dose-effect curve to verify the exposure of 10.0 Gy (absorbed dose rate: 0.670 Gy/min). Results: (1) In the traditional method of 50-hour culture, the PCC cell count in 15.0 Gy and 20.0 Gy was of no statistical significance. But there were statistical significance in the traditional method of 60-hours culture and improved method (50-hour culture and 60-hour culture). Used the last 3 culture methods to make dose curve. (2) In the above 3 culture methods, the related coefficient between PCC ring and exposure dose was quite close (all of more than 0.996, P 0.05), the morphology of regression straight lines almost overlap. (3) Used the above 3 dose-effect curves to estimate the irradiation results (10.0 Gy), the error was less than or equal to 8%, all of them were within the allowable range of the biological experiment (15%). Conclusion: The 3 dose-effect curves of the above 3 culture methods can apply to biological dose estimating of large doses of ionizing radiation damage. Especially the improved method of 50-hour culture,it is much faster to estimate and it should be regarded as the first choice in accident emergency. (authors)

  9. Quantitative analysis of biological responses to low dose-rate γ-radiation, including dose, irradiation time, and dose-rate

    International Nuclear Information System (INIS)

    Magae, J.; Furukawa, C.; Kawakami, Y.; Hoshi, Y.; Ogata, H.

    2003-01-01

    Full text: Because biological responses to radiation are complex processes dependent on irradiation time as well as total dose, it is necessary to include dose, dose-rate and irradiation time simultaneously to predict the risk of low dose-rate irradiation. In this study, we analyzed quantitative relationship among dose, irradiation time and dose-rate, using chromosomal breakage and proliferation inhibition of human cells. For evaluation of chromosome breakage we assessed micronuclei induced by radiation. U2OS cells, a human osteosarcoma cell line, were exposed to gamma-ray in irradiation room bearing 50,000 Ci 60 Co. After the irradiation, they were cultured for 24 h in the presence of cytochalasin B to block cytokinesis, cytoplasm and nucleus were stained with DAPI and propidium iodide, and the number of binuclear cells bearing micronuclei was determined by fluorescent microscopy. For proliferation inhibition, cells were cultured for 48 h after the irradiation and [3H] thymidine was pulsed for 4 h before harvesting. Dose-rate in the irradiation room was measured with photoluminescence dosimeter. While irradiation time less than 24 h did not affect dose-response curves for both biological responses, they were remarkably attenuated as exposure time increased to more than 7 days. These biological responses were dependent on dose-rate rather than dose when cells were irradiated for 30 days. Moreover, percentage of micronucleus-forming cells cultured continuously for more than 60 days at the constant dose-rate, was gradually decreased in spite of the total dose accumulation. These results suggest that biological responses at low dose-rate, are remarkably affected by exposure time, that they are dependent on dose-rate rather than total dose in the case of long-term irradiation, and that cells are getting resistant to radiation after the continuous irradiation for 2 months. It is necessary to include effect of irradiation time and dose-rate sufficiently to evaluate risk

  10. 78 FR 25440 - Request for Information and Citations on Methods for Cumulative Risk Assessment

    Science.gov (United States)

    2013-05-01

    ... Citations on Methods for Cumulative Risk Assessment AGENCY: Office of the Science Advisor, Environmental... influence exposures, dose-response or risk/hazard posed by environmental contaminant exposures, and methods... who wish to receive further information about submitting information on methods for cumulative risk...

  11. Evaluation of rate of unstable chromosomal changes in human blood irradiated by X-rays: establishment of dose-response curve; Avaliação da taxa de alterações cromossômicas instáveis em sangue humano irradiado por Raios x: estabelecimento de curva dose-resposta

    Energy Technology Data Exchange (ETDEWEB)

    Mendonça, J.C.G.; Mendes, M.E.; Melo, A.M.M.A., E-mail: july_cgm@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Silva, L.M.; Andrade, A.M.G.; Hwang, S.F.; Lima, F.F. [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil). Lab. de Dosimetria Biológica

    2017-07-01

    Since the discovery of ionizing radiation, and consequently of its properties, there has been an increasing in its use, which in turn has raised concerns about the biological damage that it could cause in exposed individuals. As a result, cytogenetic dosimetry has emerged: a method that can be used as a complement or, in the absence of physical dosimetry, relating the frequency of chromosomal changes found in the blood of the exposed individual and the dose absorbed through dose-response calibration curves. This work aimed to verify the frequencies of the unstable chromosomal changes in human blood lymphocytes irradiated by X-rays of 250 kVp with different absorbed doses and later establish the dose-response calibration curves. The irradiation was performed at the CRCN-NE/CNEN-PE, Brazil metrology service on a PANTAK X-ray machine, model HF 320. The blood samples had their lymphocytes cultured in culture media and, after the processing, the metaphases were obtained. The chromosomal alterations analyzed were chromosomes dicentric, ring and isolated actinic fragments. There was an increase in frequencies of all chromosomal changes with increased absorbed dose. The calibration curves of dicentric and dicentric + rings presented good adjustments with the values of the coefficients Y = 0.0013 + 0.0271D + 0.0556D{sup 2} (X{sup 2} = 10.36 / GL = 6) and Y = 0.0013 + 0.0263D + 0.0640D{sup 2} (X{sup 2} = 7.43 / GL = 6), respectively. The establishment of these curves enables the Laboratory of Biological Dosimetry of the CRCN/NE/CNEN-PE to estimate the dose absorbed by occupationally exposed individuals and in cases of radiological accidents.

  12. Prediction of a photovoltaic system performance using cumulative frequency curves of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lasnier, F; Sivoththaman, S [Asian Inst. of Technology, Bangkok (TH). Div. of Energy Technology

    1990-01-01

    The system performance of stand-alone photovoltaic systems is analysed. From the hourly radiation data for Bangkok (from 1984 to 1987) the cumulative frequency curves of radiation are generated and a typical meteorological day (TMD) is created each year. The system performance is determined using both the TMD radiation and the actual radiation values. The comparison results show that the TMD method can be applied for the sizing of stand-alone photovoltaic systems. The storage batteries of realistic sizes usually exhibit a daily cyclic variation in state-of-charge, with constant load consumption. Only very large and unrealistic sizes of batteries show a seasonal variation in state-of-charge. This is the fact that prompted the attempt to predict the system performance for a season by using a single representative day (TMD) of that season. Apart from giving reliable results, the TMD method significantly reduces the computation time and simplifies the process. (author).

  13. Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate-Dependent Manner.

    Science.gov (United States)

    Vieira Dias, Juliana; Gloaguen, Celine; Kereselidze, Dimitri; Manens, Line; Tack, Karine; Ebrahimian, Teni G

    2018-01-01

    A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR.

  14. Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate–Dependent Manner

    Science.gov (United States)

    Vieira Dias, Juliana; Gloaguen, Celine; Kereselidze, Dimitri; Manens, Line; Tack, Karine; Ebrahimian, Teni G

    2018-01-01

    A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR. PMID:29531508

  15. Cancer risk of low dose/low dose rate radiation: a meta-analysis of cancer data of mammals exposed to low doses of radiation

    International Nuclear Information System (INIS)

    Ogata, Hiromitsu; Magae, Junji

    2008-01-01

    Full text: Linear No Threshold (LNT) model is a basic theory for radioprotection, but the adaptability of this hypothesis to biological responses at low doses or at low dose rates is not sufficiently investigated. Simultaneous consideration of the cumulative dose and the dose rate is necessary for evaluating the risk of long-term exposure to ionizing radiation at low dose. This study intends to examine several numerical relationships between doses and dose rates in biological responses to gamma radiation. Collected datasets on the relationship between dose and the incidence of cancer in mammals exposed to low doses of radiation were analysed using meta-regression models and modified exponential (MOE) model, which we previously published, that predicts irradiation time-dependent biological response at low dose rate ionizing radiation. Minimum doses of observable risk and effective doses with a variety of dose rates were calculated using parameters estimated by fitting meta-regression models to the data and compared them with other statistical models that find values corresponding to 'threshold limits'. By fitting a weighted regression model (fixed-effects meta-regression model) to the data on risk of all cancers, it was found that the log relative risk [log(RR)] increased as the total exposure dose increased. The intersection of this regression line with the x-axis denotes the minimum dose of observable risk. These estimated minimum doses and effective doses increased with decrease of dose rate. The goodness of fits of MOE-model depended on cancer types, but the total cancer risk is reduced when dose rates are very low. The results suggest that dose response curve for cancer risk is remarkably affected by dose rate and that dose rate effect changes as a function of dose rate. For scientific discussion on the low dose exposure risk and its uncertainty, the term 'threshold' should be statistically defined, and dose rate effects should be included in the risk

  16. Association of cumulative dose of haloperidol with next-day delirium in older medical ICU patients.

    Science.gov (United States)

    Pisani, Margaret A; Araujo, Katy L B; Murphy, Terrence E

    2015-05-01

    To evaluate the association between cumulative dose of haloperidol and next-day diagnosis of delirium in a cohort of older medical ICU patients, with adjustment for its time-dependent confounding with fentanyl and intubation. Prospective, observational study. Medical ICU at an urban, academic medical center. Age 60 years and older admitted to the medical ICU who received at least one dose of haloperidol (n = 93). Of these, 72 patients were intubated at some point in their medical ICU stay, whereas 21 were never intubated. None. Detailed data were collected concerning time, dosage, route of administration of all medications, as well as for important clinical covariates, and daily status of intubation and delirium using the confusion assessment method for the ICU and a chart-based algorithm. Among nonintubated patients, and after adjustment for time-dependent confounding and important covariates, each additional cumulative milligram of haloperidol was associated with 5% higher odds of next-day delirium with odds ratio of 1.05 (credible interval [CI], 1.02-1.09). After adjustment for time-dependent confounding and covariates, intubation was associated with a five-fold increase in odds of next-day delirium with odds ratio of 5.66 (CI, 2.70-12.02). Cumulative dose of haloperidol among intubated patients did not change their already high likelihood of next-day delirium. After adjustment for time-dependent confounding, the positive associations between indicators of intubation and of cognitive impairment and next-day delirium became stronger. These results emphasize the need for more studies regarding the efficacy of haloperidol for treatment of delirium among older medical ICU patients and demonstrate the value of assessing nonintubated patients.

  17. Nonlinearity and thresholds in dose-response relationships for carcinogenicity due to sampling variation, logarithmic dose scaling, or small differences in individual susceptibility

    International Nuclear Information System (INIS)

    Lutz, W.K.; Gaylor, D.W.; Conolly, R.B.; Lutz, R.W.

    2005-01-01

    Nonlinear and threshold-like shapes of dose-response curves are often observed in tests for carcinogenicity. Here, we present three examples where an apparent threshold is spurious and can be misleading for low dose extrapolation and human cancer risk assessment. Case 1: For experiments that are not replicated, such as rodent bioassays for carcinogenicity, random variation can lead to misinterpretation of the result. This situation was simulated by 20 random binomial samplings of 50 animals per group, assuming a true linear dose response from 5% to 25% tumor incidence at arbitrary dose levels 0, 0.5, 1, 2, and 4. Linearity was suggested only by 8 of the 20 simulations. Four simulations did not reveal the carcinogenicity at all. Three exhibited thresholds, two showed a nonmonotonic behavior with a decrease at low dose, followed by a significant increase at high dose ('hormesis'). Case 2: Logarithmic representation of the dose axis transforms a straight line into a sublinear (up-bent) curve, which can be misinterpreted to indicate a threshold. This is most pronounced if the dose scale includes a wide low dose range. Linear regression of net tumor incidences and intersection with the dose axis results in an apparent threshold, even with an underlying true linear dose-incidence relationship. Case 3: Nonlinear shapes of dose-cancer incidence curves are rarely seen with epidemiological data in humans. The discrepancy to data in rodents may in part be explained by a wider span of individual susceptibilities for tumor induction in humans due to more diverse genetic background and modulation by co-carcinogenic lifestyle factors. Linear extrapolation of a human cancer risk could therefore be appropriate even if animal bioassays show nonlinearity

  18. Dose dependent effect of progesterone on hypoxic ventilatory response in newborn rats.

    Science.gov (United States)

    Hichri, Oubeidallah; Laurin, Jean-C; Julien, Cécile A; Joseph, Vincent; Bairam, Aida

    2012-01-01

    The effect of progesterone as a respiratory stimulant in newborn subjects is less known than that in adults. This study investigated the dose-response curve (0, 2, 4, and 8 mg/kg, ip) of progesterone on ventilation in non-anesthetized newborn rats at 4- and 12-days old using plethysmography. Progesterone had no effects in the regulation of normoxic ventilation. However, it enhanced the response to moderate hypoxia (FiO(2) 12%, 20 min) in 4- but not in 12-days old pups. This response was similar between the dose of 4 and 8 mg/kg. These observations suggested that progesterone enhances in age- and dose-dependent manner the hypoxic ventilatory response in newborn rats.

  19. Response of mouse lung to irradiation at different dose-rates

    International Nuclear Information System (INIS)

    Hill, R.P.

    1983-01-01

    Groups of LAF1 mice were given thoracic irradiation using 60 Co γ-rays at dose-rates of 0.05 Gy/min (LDR) or 1.1 Gy/min (HDR) and the death of the animals was monitored as a function of time. It was found that the time pattern of animal deaths was similar for the two different dose-rates. Dose response curves for animals dying at various times up to 500 days after irradiation were calculated and the LD 50 values determined. The curves for the LD 50 values, plotted as a function of the time at analysis for treatment at HDR or LDR, were essentially parallel to each other but separated by a factor (LDR/HDR) of about 1.8. This indicates that the sparing effect of LDR treatment is the same for deaths occurring during the early pneumonitis phase or during the late fibrotic phase of lung damage. The available information on the response of patients to whole thoracic irradiation, given for either palliation or piror to bone marrow transplantation, suggests that for similar dose-rates to those studied here the ratio (LDR/HDR) is only 1.2 to 1.3. This difference between the animal and human data may reflect the modifying effect of the large doses of cytotoxic drugs used in combination with the irradiation of bone marrow transplant patients

  20. A personal radio-frequency dosimeter with cumulative-dose recording capabilities

    International Nuclear Information System (INIS)

    Rochelle, R.W.; Moore, M.R.; Thomas, R.S.; Ewing, P.D.; Hess, R.A.; Hoffheins, B.S.

    1990-01-01

    The radio-frequency (rf) dosimeter developed by the Oak Ridge National Laboratory is a portable, pocket-sized cumulative-dose recording device designed to detect and record the strengths and durations of electric fields present in the work areas of naval vessels. The device measures an integrated dose and records the electric fields that exceed the permissible levels set by the American National Standards Institute. Features of the rf dosimeter include a frequency range of 30 MHz to 10 GHz and a three-dimensional sensor. Data obtained with the rf dosimeter will be used to determine the ambient field-strength profile for shipboard personnel over an extended time. Readings are acquired and averaged over a 6-min period corresponding to the rise time of the core body temperature. These values are stored for up to 6 months, after which the data are transferred to a computer via the dosimeter's serial port. The rf dosimeter should increase knowledge of the levels of electric fields to which individuals are exposed. 13 refs., 16 figs., 2 tabs

  1. Dose-response characteristics of an amorphous silicon EPID

    International Nuclear Information System (INIS)

    Winkler, Peter; Hefner, Alfred; Georg, Dietmar

    2005-01-01

    Electronic portal imaging devices (EPIDs) were originally developed for the purpose of patient setup verification. Nowadays, they are increasingly used as dosimeters (e.g., for IMRT verification and linac-specific QA). A prerequisite for any clinical dosimetric application is a detailed understanding of the detector's dose-response behavior. The aim of this study is to investigate the dosimetric properties of an amorphous silicon EPID (Elekta IVIEWGT) with respect to three photon beam qualities: 6, 10, and 25 MV. The EPID showed an excellent temporal stability on short term as well as on long term scales. The stability throughout the day was strongly influenced by warming up, which took several hours and affected EPID response by 2.5%. Ghosting effects increased the sensitivity of the EPID. They became more pronounced with decreasing time intervals between two exposures as well as with increasing dose. Due to ghosting, changes in pixel sensitivity amounted up to 16% (locally) for the 25 MV photon beam. It was observed that the response characteristics of our EPID depended on dose as well as on dose rate. Doubling the dose rate increased the EPID sensitivity by 1.5%. This behavior was successfully attributed to a dose per frame effect, i.e., a nonlinear relationship between the EPID signal and the dose which was delivered to the panel between two successive readouts. The sensitivity was found to vary up to 10% in the range of 1 to 1000 monitor units. This variation was governed by two independent effects. For low doses, the EPID signal was reduced due to the linac's changing dose rate during startup. Furthermore, the detector reading was influenced by intrabeam variations of EPID sensitivity, namely, an increase of detector response during uniform exposure. For the beam qualities which were used, the response characteristics of the EPID did not depend on energy. Differences in relative dose-response curves resulted from energy dependent temporal output

  2. Response of rat spinal cord to single and fractionated doses of accelerated heavy ions

    International Nuclear Information System (INIS)

    Leith, J.L.; McDonald, M.; Powers-Risius, P.; Bliven, S.F.; Walton, R.E.; Woodruff, K.H.; Howard, J.

    1980-01-01

    The response of rat spinal cord to irradiation with accelerated heavy ions, in particular carbon and neon ions has been studied. Two different ionization regions in the modified Bragg curve for each ion have been studied for both single and fractionated exposures. We have defined the paralytic response as a function of dose and dose per fraction, and we have determined RBE and repair values. The response of rat spinal cord is both dose and LET dependent, which allows the derivation of RBE and repair values

  3. Responses of some normal tissues to low doses of γ-radiation

    International Nuclear Information System (INIS)

    Withers, H.R.

    1975-01-01

    The response of four normal tissues to low doses of γ-radiation was measured in mice using three indirect methods. The survival curves for cells of the tissues studied (colon, jejunum, testis and haemoleucopoietic system) may be exponential over an uncertain dose range (from zero to between 100 to 230 rad), the slope being about one third of that in the high-dose region. Some of the uncertainties in the data probably reflect variations in age-density distribution. (author)

  4. Applicability of the tissue stem cell turnover concept on the validity of cumulative dose based radiation risk evaluation

    International Nuclear Information System (INIS)

    Otsuka, Kensuke; Hamada, Nobuyuki; Iwasaki, Toshiyasu; Yoshida, Kazuo

    2011-01-01

    The radiation protection system adopts the linear no-threshold model to achieve proper radiation protection for considering cancer risks resulting from radiation exposure. This model uses cumulative dose to a tissue for risk evaluation in which cumulative dose is related to the amount of DNA damage and consequential induction of gene mutation. In this concept, gene mutation accumulates in tissue stem cells, the putative target of carcinogenesis, with total dose given to the tissue. Unlike high-dose-rate exposure, epidemiological studies in high radiation background areas, such as Kerala in India, revealed that cancer risks is not elevated by the dose to the inhabitants, suggesting that there exists some mechanisms to eliminate the damage/mutation in the exposed tissue under extremely low-dose-rate exposure situations. In this report, the dynamics of tissue stem cell turnover is evaluated as a possible mechanism under extremely low-dose-rate exposure situations. To this end, we reviewed recent literatures studying tissue stem cell turnover, and found that great advances in stem cell research have made it possible to trace a fate of stem cells in tissues. Furthermore, turnover of tissue stem cells is found to occur after irradiation, due to competition of stem cells within tissues. This raises a possibility that radiation effects may not accumulate in a tissue depending on the dose-rate and duration of exposure period. (author)

  5. Highway travel time information system based on cumulative count curves and new tracking technologies

    Energy Technology Data Exchange (ETDEWEB)

    Soriguera Marti, F.; Martinez-Diaz, M.; Perez Perez, I.

    2016-07-01

    Travel time is probably the most important indicator of the level of service of a highway, and it is also the most appreciated information for its users. Administrations and private companies make increasing efforts to improve its real time estimation. The appearance of new technologies makes the precise measurement of travel times easier than never before. However, direct measurements of travel time are, by nature, outdated in real time, and lack of the desired forecasting capabilities. This paper introduces a new methodology to improve the real time estimation of travel times by using the equipment usually present in most highways, i.e., loop detectors, in combination with Automatic Vehicle Identification or Tracking Technologies. One of the most important features of the method is the usage of cumulative counts at detectors as an input, avoiding the drawbacks of common spot-speed methodologies. Cumulative count curves have great potential for freeway travel time information systems, as they provide spatial measurements and thus allow the calculation of instantaneous travel times. In addition, they exhibit predictive capabilities. Nevertheless, they have not been used extensively mainly because of the error introduced by the accumulation of the detector drift. The proposed methodology solves this problem by correcting the deviations using direct travel time measurements. The method results highly beneficial for its accuracy as well as for its low implementation cost. (Author)

  6. Thermoluminescence response and glow curve structure of Sc2TiO5 ß-irradiated

    International Nuclear Information System (INIS)

    Muñoz, I.C.; Brown, F.; Durán-Muñoz, H.; Cruz-Zaragoza, E.; Durán-Torres, B.; Alvarez-Montaño, V.E.

    2014-01-01

    Discandium titanate (Sc 2 TiO 5 ) powder was synthesized in order to analyze its thermoluminescence (TL) response. The TL glow curve structure shows two peaks: at 453–433 K and at 590–553 K. The TL beta dose–response has a linear behavior over the dose range 50–500 Gy. The T stop preheat method shows five glow peaks that were taken into account to calculate the kinetic parameters using the CGCD procedure. TL results support the possible use of Sc 2 TiO 5 as a new phosphor in high ß-dose dosimetry. - Highlights: • Discandium titanate was synthesized, and its TL properties were analyzed. • The beta dose–response has a linear behavior on the dose range 50–500 Gy. • The kinetic parameters were obtained by the CGCD procedure. • Results support the possible use of Sc 2 TiO 5 as a new phosphor for ß-dose dosimetry

  7. The effect of an asynchronous population of cells on the initial slope of dose-effect curves

    International Nuclear Information System (INIS)

    Chadwick, K.H.; Leenhouts, H.P.

    1975-01-01

    The molecular theory of cell survival gives an equation S = exp [ -p(αD + β D 2 )] which can be used to analyse dose-effect curves for synchronized cells. The variation in the coefficients α and β through the cell cycle has been found to be consistent for the different radiation types and is compatible with the induction of DNA double-strand breaks which is assumed in the theory to be the mechanism which is responsible for the biological effect. The theory predicts that low-LET radiation will have an initial slope, given by the coefficient α, and the consistency of the analysis of synchronized cell survival substantiates this prediction. In the molecular theory the induction of mutations has also been proposed to arise from DNA double-strand breaks and to be represented by the equation M = 1 - exp [-q(αD + β D 2 )]. This implies that at low doses of low-LET radiation the radiobiological effect will be linear with dose and that high-dose results may be analysed to provide estimates of the radiosensitivity of cells to low doses of radiation for radiological protection purposes. In an asynchronous population of cells it is possible that a small proportion of very radiosensitive cells can lead to significant deviations from this straightforward analysis. This 'Oftedal effect' is applied using the molecular theory to give a general theoretical relationship between the induction of mutations and cell survival. The theoretical relationship is compared with experimental data available from the literature. It is concluded that the initial slope of a mutation or cancer induction curve may be more relevant to the determination of the radiation sensitivity at low doses than the initial slope of a survival curve. (author)

  8. Prospective Evaluation to Establish a Dose Response for Clinical Oral Mucositis in Patients Undergoing Head-and-Neck Conformal Radiotherapy

    International Nuclear Information System (INIS)

    Narayan, Samir; Lehmann, Joerg; Coleman, Matthew A.; Vaughan, Andrew; Yang, Claus Chunli; Enepekides, Danny; Farwell, Gregory; Purdy, James A.; Laredo, Grace; Nolan, Kerry A.S.; Pearson, Francesca S.; Vijayakumar, Srinivasan

    2008-01-01

    Purpose: We conducted a clinical study to correlate oral cavity dose with clinical mucositis, perform in vivo dosimetry, and determine the feasibility of obtaining buccal mucosal cell samples in patients undergoing head-and-neck radiation therapy. The main objective is to establish a quantitative dose response for clinical oral mucositis. Methods and Materials: Twelve patients undergoing radiation therapy for head-and-neck cancer were prospectively studied. Four points were chosen in separate quadrants of the oral cavity. Calculated dose distributions were generated by using AcQPlan and Eclipse treatment planning systems. MOSFET dosimeters were used to measure dose at each sampled point. Each patient underwent buccal sampling for future RNA analysis before and after the first radiation treatment at the four selected points. Clinical and functional mucositis were assessed weekly according to National Cancer Institute Common Toxicity Criteria, Version 3. Results: Maximum and average doses for sampled sites ranged from 7.4-62.3 and 3.0-54.3 Gy, respectively. A cumulative point dose of 39.1 Gy resulted in mucositis for 3 weeks or longer. Mild severity (Grade ≤ 1) and short duration (≤1 week) of mucositis were found at cumulative point doses less than 32 Gy. Polymerase chain reaction consistently was able to detect basal levels of two known radiation responsive genes. Conclusions: In our sample, cumulative doses to the oral cavity of less than 32 Gy were associated with minimal acute mucositis. A dose greater than 39 Gy was associated with longer duration of mucositis. Our technique for sampling buccal mucosa yielded sufficient cells for RNA analysis using polymerase chain reaction

  9. Cumulative total effective whole-body radiation dose in critically ill patients.

    Science.gov (United States)

    Rohner, Deborah J; Bennett, Suzanne; Samaratunga, Chandrasiri; Jewell, Elizabeth S; Smith, Jeffrey P; Gaskill-Shipley, Mary; Lisco, Steven J

    2013-11-01

    Uncertainty exists about a safe dose limit to minimize radiation-induced cancer. Maximum occupational exposure is 20 mSv/y averaged over 5 years with no more than 50 mSv in any single year. Radiation exposure to the general population is less, but the average dose in the United States has doubled in the past 30 years, largely from medical radiation exposure. We hypothesized that patients in a mixed-use surgical ICU (SICU) approach or exceed this limit and that trauma patients were more likely to exceed 50 mSv because of frequent diagnostic imaging. Patients admitted into 15 predesignated SICU beds in a level I trauma center during a 30-day consecutive period were prospectively observed. Effective dose was determined using Huda's method for all radiography, CT imaging, and fluoroscopic examinations. Univariate and multivariable linear regressions were used to analyze the relationships between observed values and outcomes. Five of 74 patients (6.8%) exceeded exposures of 50 mSv. Univariate analysis showed trauma designation, length of stay, number of CT scans, fluoroscopy minutes, and number of general radiographs were all associated with increased doses, leading to exceeding occupational exposure limits. In a multivariable analysis, only the number of CT scans and fluoroscopy minutes remained significantly associated with increased whole-body radiation dose. Radiation levels frequently exceeded occupational exposure standards. CT imaging contributed the most exposure. Health-care providers must practice efficient stewardship of radiologic imaging in all critically ill and injured patients. Diagnostic benefit must always be weighed against the risk of cumulative radiation dose.

  10. Neoplastic transformation in vitro by low doses of ionizing radiation: Role of adaptive response and bystander effects

    International Nuclear Information System (INIS)

    Ko, M.; Lao, X.-Y.; Kapadia, R.; Elmore, E.; Redpath, J.L.

    2006-01-01

    The shape of the dose-response curve for cancer induction by low doses of ionizing radiation is of critical importance to the assessment of cancer risk at such doses. Epidemiologic analyses are limited by sensitivity to doses typically greater than 50-100 mGy for low LET radiation. Laboratory studies allow for the examination of lower doses using cancer-relevant endpoints. One such endpoint is neoplastic transformation in vitro. It is known that this endpoint is responsive to both adaptive response and bystander effects. The relative balance of these processes is likely to play an important role in determining the shape of the dose-response curve at low doses. A factor that may influence this balance is cell density at time of irradiation. The findings reported in this paper indicate that the transformation suppressive effect of low doses previously seen following irradiation of sub-confluent cultures, and attributed to an adaptive response, is reduced for irradiated confluent cultures. However, even under these conditions designed to optimize the role of bystander effects the data do not fit a linear no-threshold model and are still consistent with the notion of a threshold dose for neoplastic transformation in vitro by low LET radiation

  11. Estimation of organ cumulated activities and absorbed doses on intakes of several 11C labelled radiopharmaceuticals from external measurement with thermoluminescent dosimeters.

    Science.gov (United States)

    Nakamura, T; Hayashi, Y; Watabe, H; Matsumoto, M; Horikawa, T; Fujiwara, T; Ito, M; Yanai, K

    1998-02-01

    We have developed a method for obtaining the cumulated activities in organs from radionuclides, which are injected into the patient in nuclear medicine procedures, by external exposure measurement with thermoluminescent dosimeters (TLDs) which are attached to the patient's body surface close to source organs to obtain information on body-surface doses. As the surface dose is connected to the cumulated activities in source organs through radiation transmission in the human body which can be estimated with the aid of a mathematical phantom, the organ cumulated activities can be obtained by the inverse transform method. The accuracy of this method was investigated by using a water phantom in which several gamma-ray volume sources of known activity were placed to simulate source organs. We then estimated by external measurements the organ cumulated activities and absorbed doses in subjects to whom the radiopharmaceuticals 11C-labelled Doxepin, 11C-labelled YM09151-2 and 11C-labelled Benzotropin were administered in clinical nuclear medicine procedures. The cumulated activities in the brain obtained with TLDs for Doxepin and YM09151-2 are 63.6 +/- 6.2 and 32.1 +/- 12.0 kBq h MBq-1 respectively, which are compared with the respective values of 33.3 +/- 9.9 and 23.9 +/- 6.2 kBq h MBq-1 with direct PET (positron emission tomography) measurements. The agreement between the two methods is within a factor of two. The effective doses of Doxepin, YM09151-2 and Benzotropin are determined as 6.92 x 10(-3), 7.08 x 10(-3) and 7.65 x 10(-3) mSv MBq-1 respectively with the TLD method. This method has great advantages, in that cumulated activities in several organs can be obtained easily with a single procedure, and the measurements of body surface doses are performed simultaneously with the nuclear medicine procedure, as TLDs are too small to interfere with other medical measurements.

  12. Cumulative high doses of inhaled formoterol have less systemic effects in asthmatic children 6-11 years-old than cumulative high doses of inhaled terbutaline.

    Science.gov (United States)

    Kaae, Rikke; Agertoft, Lone; Pedersen, Sören; Nordvall, S Lennart; Pedroletti, Christophe; Bengtsson, Thomas; Johannes-Hellberg, Ingegerd; Rosenborg, Johan

    2004-10-01

    To evaluate high dose tolerability and relative systemic dose potency between inhaled clinically equipotent dose increments of formoterol and terbutaline in children. Twenty boys and girls (6-11 years-old) with asthma and normal ECGs were studied. Ten doses of formoterol (Oxis) 4.5 microg (F4.5) or terbutaline (Bricanyl) 500 microg (T500) were inhaled cumulatively via a dry powder inhaler (Turbuhaler) over 1 h (three patients) or 2.5 h (17 patients) and compared to a day of no treatment, in a randomised, double-blind (active treatments only), crossover trial. Blood pressure (BP), ECG, plasma potassium, glucose, lactate, and adverse events were monitored up to 10 h to assess tolerability and relative systemic dose potency. Formoterol and terbutaline had significant beta2-adrenergic effects on most outcomes. Apart from the effect on systolic BP, QRS duration and PR interval, the systemic effects were significantly more pronounced with terbutaline than with formoterol. Thus, mean minimum plasma potassium, was suppressed from 3.56 (95% confidence interval, CI: 3.48-3.65) mmol l(-1) on the day of no treatment to 2.98 (CI: 2.90-3.08) after 10 x F4.5 and 2.70 (CI: 2.61-2.78) mmol l(-1) after 10 x T500, and maximum Q-Tc (heart rate corrected Q-T interval [Bazett's formula]) was prolonged from 429 (CI: 422-435) ms on the day of no treatment, to 455 (CI: 448-462) ms after 10 x F4.5 and 470 (CI: 463-476) ms after 10 x T500. Estimates of relative dose potency indicated that F4.5 microg had the same systemic activity as the clinically less effective dose of 250 microg terbutaline. The duration of systemic effects differed marginally between treatments. Spontaneously reported adverse events (most frequently tremor) were fewer with formoterol (78% of the children) than with terbutaline (95%). A serious adverse event occurred after inhalation of 45 microg formoterol over the 1 h dosing time, that prompted the extension of dosing time to 2.5 h. Multiple inhalations over 2.5 h of

  13. Skull base chordomas: analysis of dose-response characteristics

    International Nuclear Information System (INIS)

    Niemierko, Andrzej; Terahara, Atsuro; Goitein, Michael

    1997-01-01

    Objective: To extract dose-response characteristics from dose-volume histograms and corresponding actuarial survival statistics for 115 patients with skull base chordomas. Materials and Methods: We analyzed data for 115 patients with skull base chordoma treated with combined photon and proton conformal radiotherapy to doses in the range 66.6Gy - 79.2Gy. Data set for each patient included gender, histology, age, tumor volume, prescribed dose, overall treatment time, time to recurrence or time to last observation, target dose-volume histogram, and several dosimetric parameters (minimum/mean/median/maximum target dose, percent of the target volume receiving the prescribed dose, dose to 90% of the target volume, and the Equivalent Uniform Dose (EUD). Data were analyzed using the Kaplan-Meier survivor function estimate, the proportional hazards (Cox) model, and parametric modeling of the actuarial probability of recurrence. Parameters of dose-response characteristics were obtained using the maximum likelihood method. Results: Local failure developed in 42 (36%) of patients, with actuarial local control rates at 5 years of 59.2%. The proportional hazards model revealed significant dependence of gender on the probability of recurrence, with female patients having significantly poorer prognosis (hazard ratio of 2.3 with the p value of 0.008). The Wilcoxon and the log-rank tests of the corresponding Kaplan-Meier recurrence-free survival curves confirmed statistical significance of this effect. The Cox model with stratification by gender showed significance of tumor volume (p=0.01), the minimum target dose (p=0.02), and the EUD (p=0.02). Other parameters were not significant at the α level of significance of 0.05, including the prescribed dose (p=0.21). Parametric analysis using a combined model of tumor control probability (to account for non-uniformity of target dose distribution) and the Weibull failure time model (to account for censoring) allowed us to estimate

  14. Risk group dependence of dose-response for biopsy outcome after three-dimensional conformal radiation therapy of prostate cancer

    International Nuclear Information System (INIS)

    Levegruen, Sabine; Jackson, Andrew; Zelefsky, Michael J.; Venkatraman, Ennapadam S.; Skwarchuk, Mark W.; Schlegel, Wolfgang; Fuks, Zvi; Leibel, Steven A.; Ling, C. Clifton

    2002-01-01

    Background and purpose: We fit phenomenological tumor control probability (TCP) models to biopsy outcome after three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer patients to quantify the local dose-response of prostate cancer. Materials and methods: We analyzed the outcome after photon beam 3D-CRT of 103 patients with stage T1c-T3 prostate cancer treated at Memorial Sloan-Kettering Cancer Center (MSKCC) (prescribed target doses between 64.8 and 81 Gy) who had a prostate biopsy performed ≥2.5 years after end of treatment. A univariate logistic regression model based on D mean (mean dose in the planning target volume of each patient) was fit to the whole data set and separately to subgroups characterized by low and high values of tumor-related prognostic factors T-stage ( 6), and pre-treatment prostate-specific antigen (PSA) (≤10 ng/ml vs. >10 ng/ml). In addition, we evaluated five different classifications of the patients into three risk groups, based on all possible combinations of two or three prognostic factors, and fit bivariate logistic regression models with D mean and the risk group category to all patients. Dose-response curves were characterized by TCD 50 , the dose to control 50% of the tumors, and γ 50 , the normalized slope of the dose-response curve at TCD 50 . Results: D mean correlates significantly with biopsy outcome in all patient subgroups and larger values of TCD 50 are observed for patients with unfavorable compared to favorable prognostic factors. For example, TCD 50 for high T-stage patients is 7 Gy higher than for low T-stage patients. For all evaluated risk group definitions, D mean and the risk group category are independent predictors of biopsy outcome in bivariate analysis. The fit values of TCD 50 show a clear separation of 9-10.6 Gy between low and high risk patients. The corresponding dose-response curves are steeper (γ 50 =3.4-5.2) than those obtained when all patients are analyzed together (γ 50 =2

  15. Radiation Dose-Response Model for Locally Advanced Rectal Cancer After Preoperative Chemoradiation Therapy

    DEFF Research Database (Denmark)

    Appelt, A. L.; Ploen, J.; Vogelius, I. R.

    2013-01-01

    estimated radiation dose-response curves for various grades of tumor regression after preoperative CRT. Methods and Materials: A total of 222 patients, treated with consistent chemotherapy and radiation therapy techniques, were considered for the analysis. Radiation therapy consisted of a combination...... of external-beam radiation therapy and brachytherapy. Response at the time of operation was evaluated from the histopathologic specimen and graded on a 5-point scale (TRG1-5). The probability of achieving complete, major, and partial response was analyzed by ordinal logistic regression, and the effect...... of including clinical parameters in the model was examined. The radiation dose-response relationship for a specific grade of histopathologic tumor regression was parameterized in terms of the dose required for 50% response, D-50,D-i, and the normalized dose-response gradient, gamma(50,i). Results: A highly...

  16. Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

    Science.gov (United States)

    Wang, Yan; Xu, Chang; Du, Li Qing; Cao, Jia; Liu, Jian Xiang; Su, Xu; Zhao, Hui; Fan, Fei-Yue; Wang, Bing; Katsube, Takanori; Fan, Sai Jun; Liu, Qiang

    2013-01-01

    Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001). A time-response relationship was also found within 72 h after irradiation (p < 0.001). The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined. PMID:24240807

  17. Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2013-11-01

    Full Text Available Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001. A time-response relationship was also found within 72 h after irradiation (p < 0.001. The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined.

  18. Study on the dose response characteristics of a scanning liquid ion-chamber electronic portal imaging device

    CERN Document Server

    Ma Shao Gang; Song Yi Xin

    2002-01-01

    Objective: To study the dose response characteristics and the influence factors such as gantry angle, field size and acquisition mode on the dosimetric response curves, when using a scanning liquid ion-chamber electronic portal imaging device (EPID) for dose verification. Methods: All experiments were carried out on a Varian 600 C/D accelerator (6 MV X-ray) equipped with a Varian PortalVision sup T sup M MK2 type EPID. To obtain the dose response curve, the relationship between the incident radiation intensity to the detector and the pixel value output from the EPID were established. Firstly, the different dose rates of 6 MV X-rays were obtained by varying SSD. Secondly, three digital portal images were acquired for each dose rate using the EPID and averaged to avoid the influence of the dose rate fluctuations of the accelerator. The pixel values of all images were read using self-designed image analysis software, and and average for a region consisting of 11 x 11 pixels around the center was taken as the res...

  19. Comparison of the dose-response relationship of radiation-induced apoptosis in the hippocampal dentate gyrus and intestinal crypt of adult mice

    International Nuclear Information System (INIS)

    Kim, J. S.; Yang, M.; Kim, J.; Lee, D.; Kim, J. C.; Shin, T.; Kim, S. H.; Moon, C.

    2012-01-01

    The present study compared the dose-response curves for the frequency of apoptosis in mouse hippocampal dentate gyrus (DG) and intestinal crypt using whole-body gamma irradiation. The incidence of gamma-ray-induced apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end-labelling (TUNEL) method. TUNEL-positive apoptotic nuclei in the DG and intestinal crypt were increased in a dose-dependent pattern (0-2 Gy). The dose-response curves were linear-quadratic, with a significant relationship between the appearance of apoptosis and irradiation dose. The slopes of the dose-response curves in the DG were much steeper (∼5-6-fold) than those in the intestinal crypt within the range of 0-1 Gy exposure. Hippocampal DG might be a more effective and sensitive evaluation structure than the intestinal crypt to estimate the degree of radiation exposure in damaged organs of adult mice exposed to low irradiation dose. copy; The Author 2011. Published by Oxford Univ. Press. All rights reserved. (authors)

  20. Effect and adaptive response of lymphocytes DNA induced by low dose irradiation

    International Nuclear Information System (INIS)

    Du Zeji; Su Liaoyuan; Tian Hailin

    1994-09-01

    Fluorometric analysis of DNA unwinding (FADU) was conducted and was proved to be an optimal method for studying DNA strand breaks induced by low dose irradiation. The linear dose response curve was obtained. The minimum detected dose was 0.3 Gy. There was no effect of low dose γ-rays (0.5∼8.0 cGy) on DNA strand breaks of quiescent and mitogen-induced lymphocytes. The 0.5∼4.0 cGy γ-rats could induce adaptive response of lymphocytes' DNA strand breaks, especially, at the doses of 2.0 and 4.0 cGy. The challenge doses of 5∼20 Gy could make the adaptive response appearance, and the 15 Gy was the best one. The 3-AB could powerfully inhibit the adaptive response. The repair of DNA strand breaks (37 degree C, 15∼60 min) caused by 15 Gy γ-rays could be promoted by the low dose γ-ray irradiation (2.0 cGy), but no difference was found at 37 degree C, 120 min

  1. Thymocyte apoptosis in response to low-dose radiation

    International Nuclear Information System (INIS)

    Shu-Zheng, Liu; Ying-Chun, Zhang; Ying, Mu; Xu, Su; Jian-Xiang, Liu

    1996-01-01

    Thymocyte apoptosis was assessed by counting apoptotic bodies with flow cytometry (FCM) and measuring DNA fragmentation with fluorescence spectrophotometry (FSP). J-shaped dose-response curves were obtained after both whole-body irradiation (WBI) of mice and in vitro irradiation of EL4 cells with doses ranging from 0.025 to 4 Gy X-rays. There was a significant reduction of apoptosis rate to below control level with doses within 0.2 Gy, and a dose-dependent increase in apoptosis with doses above 0.5 Gy. When thymocytes were cultured 24 h after WBI with 75 mGy X-rays in complete RPMI 1640 medium, a reduction in apoptosis was observed in the course of incubation for 72 h, and the presence of Con A in the medium accentuated this reduction in a dose- and time-dependent manner. The implications of these observations and the possible molecular mechanisms for future studies are proposed

  2. Dose-responses for mortality from cerebrovascular and heart diseases in atomic bomb survivors: 1950-2003

    Energy Technology Data Exchange (ETDEWEB)

    Schoellnberger, Helmut [Helmholtz Zentrum Muenchen, Department of Radiation Sciences, Institute of Radiation Protection, Neuherberg (Germany); Federal Office for Radiation Protection, Department of Radiation Protection and the Environment, Neuherberg (Germany); Eidemueller, Markus; Simonetto, Cristoforo; Kaiser, Jan Christian [Helmholtz Zentrum Muenchen, Department of Radiation Sciences, Institute of Radiation Protection, Neuherberg (Germany); Cullings, Harry M. [Radiation Effects Research Foundation, Department of Statistics, Hiroshima (Japan); Neff, Frauke [Staedtisches Klinikum Muenchen and Technical University of Munich, Institute of Pathology, Munich (Germany)

    2018-03-15

    The scientific community faces important discussions on the validity of the linear no-threshold (LNT) model for radiation-associated cardiovascular diseases at low and moderate doses. In the present study, mortalities from cerebrovascular diseases (CeVD) and heart diseases from the latest data on atomic bomb survivors were analyzed. The analysis was performed with several radio-biologically motivated linear and nonlinear dose-response models. For each detrimental health outcome one set of models was identified that all fitted the data about equally well. This set was used for multi-model inference (MMI), a statistical method of superposing different models to allow risk estimates to be based on several plausible dose-response models rather than just relying on a single model of choice. MMI provides a more accurate determination of the dose response and a more comprehensive characterization of uncertainties. It was found that for CeVD, the dose-response curve from MMI is located below the linear no-threshold model at low and medium doses (0-1.4 Gy). At higher doses MMI predicts a higher risk compared to the LNT model. A sublinear dose-response was also found for heart diseases (0-3 Gy). The analyses provide no conclusive answer to the question whether there is a radiation risk below 0.75 Gy for CeVD and 2.6 Gy for heart diseases. MMI suggests that the dose-response curves for CeVD and heart diseases in the Lifespan Study are sublinear at low and moderate doses. This has relevance for radiotherapy treatment planning and for international radiation protection practices in general. (orig.)

  3. Response of cellulose nitrate track detectors to electron doses

    CERN Document Server

    Segovia, N; Moreno, A; Vazquez-Polo, G; Santamaría, T; Aranda, P; Hernández, A

    1999-01-01

    In order to study alternative dose determination methods, the bulk etching velocity and the latent track annealing of LR 115 track detectors was studied during electron irradiation runs from a Pelletron accelerator. For this purpose alpha irradiated and blank detectors were exposed to increasing electron doses from 10.5 to 317.5 kGy. After the irradiation with electrons the detectors were etched under routine conditions, except for the etching time, that was varied for each electron dose in order to reach a fixed residual thickness. The variation of the bulk etching velocity as a function of each one of the electron doses supplied, was interpolated in order to obtain dosimetric response curves. The observed annealing effect on the latent tracks is discussed as a function of the total electron doses supplied and the temperature.

  4. Radiation dose response of N channel MOSFET submitted to filtered X-ray photon beam

    Science.gov (United States)

    Gonçalves Filho, Luiz C.; Monte, David S.; Barros, Fabio R.; Santos, Luiz A. P.

    2018-01-01

    MOSFET can operate as a radiation detector mainly in high-energy photon beams, which are normally used in cancer treatments. In general, such an electronic device can work as a dosimeter from threshold voltage shift measurements. The purpose of this article is to show a new way for measuring the dose-response of MOSFETs when they are under X-ray beams generated from 100kV potential range, which is normally used in diagnostic radiology. Basically, the method consists of measuring the MOSFET drain current as a function of the radiation dose. For this the type of device, it has to be biased with a high value resistor aiming to see a substantial change in the drain current after it has been irradiated with an amount of radiation dose. Two types of N channel device were used in the experiment: a signal transistor and a power transistor. The delivered dose to the device was varied and the electrical curves were plotted. Also, a sensitivity analysis of the power MOSFET response was made, by varying the tube potential of about 20%. The results show that both types of devices have responses very similar, the shift in the electrical curve is proportional to the radiation dose. Unlike the power MOSFET, the signal transistor does not provide a linear function between the dose rate and its drain current. We also have observed that the variation in the tube potential of the X-ray equipment produces a very similar dose-response.

  5. Dose-response relationships for chromosome aberrations in peripheral blood lymphocytes after whole- and partial-body irradiations. Pt. 1

    International Nuclear Information System (INIS)

    Liniecki, J.; Bajerska, A.; Wyszynska, K.

    1983-01-01

    Dose-response relationships were established for yield of dicentrics and for a fraction of damaged metaphases in lymphocytes after γ-irradiation of rabbits' whole blood in vitro. These relationships were based on the scoring of cells only in their first post-stimulation division and they served as a reference system for comparison with results of 60 Co γ-irradiation in vivo, either of the whole or of predetermined parts of an animal's body. There was a statistically acceptable agreement between dose-response data established for dicentric yield after whole-body irradiation in vivo and the reference dose-response curve derived from exposure of rabbit's blood in vitro. For partial-body (1/2) irradiations there was a satisfactory agreement between the dose-response curves in vitro for dicentric yield and fraction of metaphases damaged on the one hand and the response in vivo when the latter was related to mean doses to circulating blood. However, there was a drastic disagreement with the dose responses in vitro when measured cytogenetic quantities were plotted versus mean doses to body mass. When the latter were substituted for by comparable doses to circulating blood the in vivo-in vitro agreement was acceptable after irradiation. (orig.)

  6. Radiosensitive xrs-5 and parental CHO cells show identical DNA neutral filter elution dose-response: implications for a relationship between cell radiosensitivity and induction of DNA double-strand breaks

    International Nuclear Information System (INIS)

    Iliakis, George; Okayasu, Ryuichi; Seaner, Robert

    1988-01-01

    The purpose of this work was to investigate a possible correlation between DNA elution dose-response and cell radiosensitivity. For this purpose neutral (pH 9.6) DNA filter elution dose-response curves were measured with radiosensitive xrs-5 and the parental Chinese hamster ovary (CHO) cells in the logarithmic and plateau phase of growth. No difference was observed between the two cell types in the DNA elution dose-response curves either in logarithmic or plateau phase, despite the dramatic differences in cell radiosensitivity. This observation indicates that the shape of the DNA elution dose-response curve and the shape of the cell survival curve are not causally related. It is proposed that the shoulder observed in the DNA elution dose-response curve reflects either partial release of DNA from chromatin, or cell cycle-specific alterations in the physicochemical properties of the DNA. (author)

  7. Estimating a population cumulative incidence under calendar time trends

    DEFF Research Database (Denmark)

    Hansen, Stefan N; Overgaard, Morten; Andersen, Per K

    2017-01-01

    BACKGROUND: The risk of a disease or psychiatric disorder is frequently measured by the age-specific cumulative incidence. Cumulative incidence estimates are often derived in cohort studies with individuals recruited over calendar time and with the end of follow-up governed by a specific date....... It is common practice to apply the Kaplan-Meier or Aalen-Johansen estimator to the total sample and report either the estimated cumulative incidence curve or just a single point on the curve as a description of the disease risk. METHODS: We argue that, whenever the disease or disorder of interest is influenced...

  8. Estimation of organ cumulated activities and absorbed doses on intakes of several {sup 11}C labelled radiopharmaceuticals from external measurement with thermoluminescent dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Takashi; Hayashi, Yoshiharu; Watabe, Hiroshi; Matsumoto, Masaki; Horikawa, Tohru; Fujiwara, Takehiko; Ito, Masatoshi; Yanai, Kazuhiko [Cyclotron and Radioisotope Center, Tohoku University, Aoba, Aramaki, Sendai 980-77 (Japan)

    1998-02-01

    We have developed a method for obtaining the cumulated activities in organs from radionuclides, which are injected into the patient in nuclear medicine procedures, by external exposure measurement with thermoluminescent dosimeters (TLDs) which are attached to the patient's body surface close to source organs to obtain information on body-surface doses. As the surface dose is connected to the cumulated activities in source organs through radiation transmission in the human body which can be estimated with the aid of a mathematical phantom, the organ cumulated activities can be obtained by the inverse transform method. The accuracy of this method was investigated by using a water phantom in which several gamma-ray volume sources of known activity were placed to simulate source organs. We then estimated by external measurements the organ cumulated activities and absorbed doses in subjects to whom the radiopharmaceuticals {sup 11}C-labelled Doxepin, {sup 11}C-labelled YM09151-2 and {sup 11}C-labelled Benzotropin were administered in clinical nuclear medicine procedures. The cumulated activities in the brain obtained with TLDs for Doxepin and YM09151-2 are 63.6{+-}6.2 and 32.1{+-}12.0 kBq h MBq{sup -1} respectively, which are compared with the respective values of 33.3{+-}9.9 and 23.9{+-}6.2 kBq h MBq{sup -1} with direct PET (positron emission tomography) measurements. The agreement between the two methods is within a factor of two. The effective doses of Doxepin, YM09151-2 and Benzotropin are determined as 6.92x10{sup -3}, 7.08x10{sup -3} and 7.65x10{sup -3} mSv MBq{sup -1} respectively with the TLD method. This method has great advantages, in that cumulated activities in several organs can be obtained easily with a single procedure, and the measurements of body surface doses are performed simultaneously with the nuclear medicine procedure, as TLDs are too small to interfere with other medical measurements. (author)

  9. Response of mouse tongue epithelium to single doses of bleomycin and radiation

    International Nuclear Information System (INIS)

    Dorr, W.; Hirler, E.; Honig, M.

    1993-01-01

    Both bleomycin (BLM) and local X-irradiation (25 kV) induce denudation in the tongue epithelium of the C3H-Neuherberg mouse in a dose-dependent manner. In the present study the effect of BLM alone and of combined single doses of drug and radiation were studied using the incidence of epithelial denudation as the end-point. In 'time-line' experiments, 8 mg/kg BLM were given before or after graded doses of X-rays. BLM treatment required a reduction of the radiation dose (ED 50 ) from 15 Gy to 5-7 Gy, independent of sequence or time interval. In contrast, the time course of the response was clearly dependent on the treatment interval. Latency decreased when the drug was injected less than 2 h before irradiation with minimum latency observed at 30 min. Isobologram analysis of experiments with varying combinations of X-rays and BLM demonstrated that small drug doses were relatively more effective than larger doses, suggesting an upward concavity of the BLM dose-effective curve in vivo, i.e. a 'negative shoulder' of the curve in the low dose region. In contrast to the response to X-rays alone, which has a constant latent time to ulcer of 10 days, the latency in combined treatment was clearly shortened with increasing drug dose and at high doses eventually approximated the epithelial turnover time of 5 days. The data suggest that BLM both as a single agent and in combination with X-rays reduced the probability of abortive divisions and through this effect shortened the latent time to epithelial denudation. (author)

  10. Dose response relationship in anti-stress gene regulatory networks.

    Science.gov (United States)

    Zhang, Qiang; Andersen, Melvin E

    2007-03-02

    To maintain a stable intracellular environment, cells utilize complex and specialized defense systems against a variety of external perturbations, such as electrophilic stress, heat shock, and hypoxia, etc. Irrespective of the type of stress, many adaptive mechanisms contributing to cellular homeostasis appear to operate through gene regulatory networks that are organized into negative feedback loops. In general, the degree of deviation of the controlled variables, such as electrophiles, misfolded proteins, and O2, is first detected by specialized sensor molecules, then the signal is transduced to specific transcription factors. Transcription factors can regulate the expression of a suite of anti-stress genes, many of which encode enzymes functioning to counteract the perturbed variables. The objective of this study was to explore, using control theory and computational approaches, the theoretical basis that underlies the steady-state dose response relationship between cellular stressors and intracellular biochemical species (controlled variables, transcription factors, and gene products) in these gene regulatory networks. Our work indicated that the shape of dose response curves (linear, superlinear, or sublinear) depends on changes in the specific values of local response coefficients (gains) distributed in the feedback loop. Multimerization of anti-stress enzymes and transcription factors into homodimers, homotrimers, or even higher-order multimers, play a significant role in maintaining robust homeostasis. Moreover, our simulation noted that dose response curves for the controlled variables can transition sequentially through four distinct phases as stressor level increases: initial superlinear with lesser control, superlinear more highly controlled, linear uncontrolled, and sublinear catastrophic. Each phase relies on specific gain-changing events that come into play as stressor level increases. The low-dose region is intrinsically nonlinear, and depending on

  11. Dose response relationship in anti-stress gene regulatory networks.

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2007-03-01

    Full Text Available To maintain a stable intracellular environment, cells utilize complex and specialized defense systems against a variety of external perturbations, such as electrophilic stress, heat shock, and hypoxia, etc. Irrespective of the type of stress, many adaptive mechanisms contributing to cellular homeostasis appear to operate through gene regulatory networks that are organized into negative feedback loops. In general, the degree of deviation of the controlled variables, such as electrophiles, misfolded proteins, and O2, is first detected by specialized sensor molecules, then the signal is transduced to specific transcription factors. Transcription factors can regulate the expression of a suite of anti-stress genes, many of which encode enzymes functioning to counteract the perturbed variables. The objective of this study was to explore, using control theory and computational approaches, the theoretical basis that underlies the steady-state dose response relationship between cellular stressors and intracellular biochemical species (controlled variables, transcription factors, and gene products in these gene regulatory networks. Our work indicated that the shape of dose response curves (linear, superlinear, or sublinear depends on changes in the specific values of local response coefficients (gains distributed in the feedback loop. Multimerization of anti-stress enzymes and transcription factors into homodimers, homotrimers, or even higher-order multimers, play a significant role in maintaining robust homeostasis. Moreover, our simulation noted that dose response curves for the controlled variables can transition sequentially through four distinct phases as stressor level increases: initial superlinear with lesser control, superlinear more highly controlled, linear uncontrolled, and sublinear catastrophic. Each phase relies on specific gain-changing events that come into play as stressor level increases. The low-dose region is intrinsically nonlinear

  12. Cumulative high doses of inhaled formoterol have less systemic effects in asthmatic children 6–11 years-old than cumulative high doses of inhaled terbutaline

    Science.gov (United States)

    Kaae, Rikke; Agertoft, Lone; Pedersen, Sören; Nordvall, S Lennart; Pedroletti, Christophe; Bengtsson, Thomas; Johannes-Hellberg, Ingegerd; Rosenborg, Johan

    2004-01-01

    Objectives To evaluate high dose tolerability and relative systemic dose potency between inhaled clinically equipotent dose increments of formoterol and terbutaline in children. Methods Twenty boys and girls (6–11 years-old) with asthma and normal ECGs were studied. Ten doses of formoterol (Oxis®) 4.5 µg (F4.5) or terbutaline (Bricanyl®) 500 µg (T500) were inhaled cumulatively via a dry powder inhaler (Turbuhaler®) over 1 h (three patients) or 2.5 h (17 patients) and compared to a day of no treatment, in a randomised, double-blind (active treatments only), crossover trial. Blood pressure (BP), ECG, plasma potassium, glucose, lactate, and adverse events were monitored up to 10 h to assess tolerability and relative systemic dose potency. Results Formoterol and terbutaline had significant β2-adrenergic effects on most outcomes. Apart from the effect on systolic BP, QRS duration and PR interval, the systemic effects were significantly more pronounced with terbutaline than with formoterol. Thus, mean minimum plasma potassium, was suppressed from 3.56 (95% confidence interval, CI: 3.48–3.65) mmol l−1 on the day of no treatment to 2.98 (CI: 2.90–3.08) after 10 × F4.5 and 2.70 (CI: 2.61–2.78) mmol l−1 after 10 × T500, and maximum Q-Tc (heart rate corrected Q-T interval [Bazett's formula]) was prolonged from 429 (CI: 422–435) ms on the day of no treatment, to 455 (CI: 448–462) ms after 10 × F4.5 and 470 (CI: 463–476) ms after 10 × T500. Estimates of relative dose potency indicated that F4.5 µg had the same systemic activity as the clinically less effective dose of 250 µg terbutaline. The duration of systemic effects differed marginally between treatments. Spontaneously reported adverse events (most frequently tremor) were fewer with formoterol (78% of the children) than with terbutaline (95%). A serious adverse event occurred after inhalation of 45 µg formoterol over the 1 h dosing time, that prompted the extension of dosing time to 2.5 h

  13. Radiation dose response of strand breaks in SINPV-DNA

    International Nuclear Information System (INIS)

    Zhang Chunxiang; Luo Daling; Li Mianfeng; Liu Xiaowei; Zeng Rong; Wang Xunzhang

    1995-01-01

    The Spodoplera litura Nuclear Polyhedrosis Viruses (SINPV) is a kind of insectile virus with a simple structure, in which a double helix DNA is encapsulated in a protein coat and there is no function of enzymatic repair. The SINPV samples in dry powdered form held in sealed plastic tube were irradiated by 1-100 kGy gamma rays. The single strand breaks (SSB) and double strand breaks (DSB) induced in SINPV after irradiation were measured by neutral and alkaline agarose gel electrophoresis. A dose-response function combining the responses of one-hit and two-hit events was used to describe the SSB and DSB dose-response curves. It is shown that the SSB are one-hit events and the DSB are the combination of both one-hit, and two-hit events, and two-hit events are predominant in the DSB process

  14. Calibration curve to establish the exposure dose at Co{sup 60} gamma radiation; Curva de calibracion para establecer dosis de exposicion a radiacion gamma de Co{sup 60}

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero C, C; Brena V, M [Departamento de Biologia, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. (Mexico)

    2000-07-01

    The biological dosimetry is an adequate method for the dose determination in cases of overexposure to ionizing radiation or doubt of the dose obtained by physical methods. It is based in the aberrations analysis produced in the chromosomes. The behavior of leisure in chromosomes is of dose-response type and it has been generated curves in distinct laboratories. Next is presented the curve for gamma radiation produced in the National Institute of Nuclear Research (ININ) laboratory. (Author)

  15. Cumulative radiation exposure in children with cystic fibrosis.

    LENUS (Irish Health Repository)

    O'Reilly, R

    2010-02-01

    This retrospective study calculated the cumulative radiation dose for children with cystic fibrosis (CF) attending a tertiary CF centre. Information on 77 children with a mean age of 9.5 years, a follow up time of 658 person years and 1757 studies including 1485 chest radiographs, 215 abdominal radiographs and 57 computed tomography (CT) scans, of which 51 were thoracic CT scans, were analysed. The average cumulative radiation dose was 6.2 (0.04-25) mSv per CF patient. Cumulative radiation dose increased with increasing age and number of CT scans and was greater in children who presented with meconium ileus. No correlation was identified between cumulative radiation dose and either lung function or patient microbiology cultures. Radiation carries a risk of malignancy and children are particularly susceptible. Every effort must be made to avoid unnecessary radiation exposure in these patients whose life expectancy is increasing.

  16. Pharmacoepidemiology of opiate use in the neonatal ICU: Increasing cumulative doses and iatrogenic opiate withdrawal.

    Science.gov (United States)

    Lewis, Tamorah; Erfe, Betty Luan; Ezell, Tarrah; Gauda, Estelle

    2015-01-01

    Neonatal intensive care unit (ICU) care involves use of opiates to treat postoperative, ventilated, or chronically ill infants. Opiates provide necessary analgesia and sedation, but the morbidities include prolonged neonatal abstinence syndrome (NAS) and extended length of stay for dose tapering. Our objective was to quantify trends in opiate exposure in a tertiary care NICU. The authors hypothesize that medical opiate exposure and resultant ICU-acquired NAS would increase over time. Retrospective cross-sectional cohort study. Tertiary care NICU. High-risk inborn infants admitted in fiscal years 2003-2004, 2007-2008, and 2010-2011. Average cumulative morphine exposure (all opiate doses converted to morphine equivalents) per time epoch was compared in cohorts of clinically similar infants. Linear regression was used to assess the primary outcome, assessing changes in opiate exposure over time. Sixty-three infants were included in the final analysis. The primary analysis assessing cumulative opiate exposure per infant showed an increase of 134 mg per time epoch (95% CI-12, 279 mg, p-value 0.071). There was a statistically significant increase in the percent of infants with a diagnosis of iatrogenic NAS, increasing from 9 to 35 to 50 percent (p-value 0.012).

  17. Guidelines for Use of the Approximate Beta-Poisson Dose-Response Model.

    Science.gov (United States)

    Xie, Gang; Roiko, Anne; Stratton, Helen; Lemckert, Charles; Dunn, Peter K; Mengersen, Kerrie

    2017-07-01

    For dose-response analysis in quantitative microbial risk assessment (QMRA), the exact beta-Poisson model is a two-parameter mechanistic dose-response model with parameters α>0 and β>0, which involves the Kummer confluent hypergeometric function. Evaluation of a hypergeometric function is a computational challenge. Denoting PI(d) as the probability of infection at a given mean dose d, the widely used dose-response model PI(d)=1-(1+dβ)-α is an approximate formula for the exact beta-Poisson model. Notwithstanding the required conditions α1, issues related to the validity and approximation accuracy of this approximate formula have remained largely ignored in practice, partly because these conditions are too general to provide clear guidance. Consequently, this study proposes a probability measure Pr(0 (22α̂)0.50 for 0.020.99) . This validity measure and rule of thumb were validated by application to all the completed beta-Poisson models (related to 85 data sets) from the QMRA community portal (QMRA Wiki). The results showed that the higher the probability Pr(0 Poisson model dose-response curve. © 2016 Society for Risk Analysis.

  18. A study of the relationship between peak skin dose and cumulative air kerma in interventional neuroradiology and cardiology

    International Nuclear Information System (INIS)

    Neil, S; Padgham, C; Martin, C J

    2010-01-01

    A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3 Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose-area product (DAP) for particular types of procedure, and DAPs of 200-300 Gy cm 2 could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

  19. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  20. Implications of the quadratic cell survival curve and human skin radiation ''tolerance doses'' on fractionation and superfractionation dose selection

    International Nuclear Information System (INIS)

    Douglas, B.G.

    1982-01-01

    An analysis of early published multifraction orthovoltage human acute skin irradiation tolerance isoeffect doses is presented. It indicates that human acute skin radiation reactions may result from the repetition, with each dose fraction, of a cell survival curve of the form: S = e/sup -(αD + βD 2 )/). The analysis also shows no need for an independent proliferation related time factor for skin, for daily treatments of six weeks or less in duration. The value obtained for the constant β/α for orthovoltage irradiation from these data is 2.9 x 10 -3 rad -1 for the cell line determining acute skin tolerance. A radiation isoeffect relationship, based on the quadratic cell survival curve, is introduced for human skin. This relationship has some advantages over the nominal standard dose (NSD). First, its use is not restricted to tolerance level reactions. Second, a modification of the relationship, which is also introduced, may be employed in the selection of doses per treatment when irradiation dose fractions are administered at short intervals where repair of sublethal injury is incomplete

  1. Estimated cumulative radiation dose from PET/CT in children with malignancies: a 5-year retrospective review

    International Nuclear Information System (INIS)

    Chawla, Soni C.; Federman, Noah; Zhang, Di; Nagata, Kristen; Nuthakki, Soujanya; McNitt-Gray, Michael; Boechat, M.I.

    2010-01-01

    The increasing use of serial PET/CT scans in the management of pediatric malignancies raises the important consideration of radiation exposure in children. To estimate the cumulative radiation dose from PET/CT studies to children with malignancy and to compare with the data in literature. Two hundred forty-eight clinical PET/CT studies performed on 78 patients (50 boys/28 girls, 1.3 to 18 years old from December 2002 to October 2007) were retrospectively reviewed under IRB approval. The whole-body effective dose (ED) estimates for each child were obtained by estimating the effective dose from each PET/CT exam performed using the ImPACT Patient Dosimetry Calculator for CT and OLINDA for PET. The average number of PET/CT studies was 3.2 per child (range: 1 to 14 studies). The average ED of an individual CT study was 20.3 mSv (range: 2.7 to 54.2), of PET study was 4.6 mSv (range: 0.4 to 7.7) and of PET/CT study was 24.8 mSv (range: 6.2 to 60.7). The average cumulative radiation dose per patient from CT studies was 64.4 mSv (range: 2.7 to 326), from PET studies was 14.5 mSv (range: 2.8 to 73) and from PET/CT studies was 78.9 mSv (range: 6.2 to 399). The radiation exposure from serial PET/CT studies performed in pediatric malignancies was considerable; however, lower doses can be used for both PET and CT studies. The ALARA principle must be applied without sacrificing diagnostic information. (orig.)

  2. Optimizing clopidogrel dose response: a new clinical algorithm comprising CYP2C19 pharmacogenetics and drug interactions

    Directory of Open Access Journals (Sweden)

    Saab YB

    2015-09-01

    Full Text Available Yolande B Saab,1 Rony Zeenny,2 Wijdan H Ramadan2 1School of Pharmacy, Pharmaceutical Sciences Department, 2School of Pharmacy, Pharmacy Practice Department, Lebanese American University, Byblos, Lebanon Purpose: Response to clopidogrel varies widely with nonresponse rates ranging from 4% to 30%. A reduced function of the gene variant of the CYP2C19 has been associated with lower drug metabolite levels, and hence diminished platelet inhibition. Drugs that alter CYP2C19 activity may also mimic genetic variants. The aim of the study is to investigate the cumulative effect of CYP2C19 gene polymorphisms and drug interactions that affects clopidogrel dosing, and apply it into a new clinical-pharmacogenetic algorithm that can be used by clinicians in optimizing clopidogrel-based treatment. Method: Clopidogrel dose optimization was analyzed based on two main parameters that affect clopidogrel metabolite area under the curve: different CYP2C19 genotypes and concomitant drug intake. Clopidogrel adjusted dose was computed based on area under the curve ratios for different CYP2C19 genotypes when a drug interacting with CYP2C19 is added to clopidogrel treatment. A clinical-pharmacogenetic algorithm was developed based on whether clopidogrel shows 1 expected effect as per indication, 2 little or no effect, or 3 clinical features that patients experience and fit with clopidogrel adverse drug reactions. Results: The study results show that all patients under clopidogrel treatment, whose genotypes are different from *1*1, and concomitantly taking other drugs metabolized by CYP2C19 require clopidogrel dose adjustment. To get a therapeutic effect and avoid adverse drug reactions, therapeutic dose of 75 mg clopidogrel, for example, should be lowered to 6 mg or increased to 215 mg in patients with different genotypes. Conclusion: The implementation of clopidogrel new algorithm has the potential to maximize the benefit of clopidogrel pharmacological therapy

  3. Curvas dose-resposta em espécies de plantas daninhas com o uso do herbicida glyphosate(1 Dose-response curves in weed species with the use of herbicide glyphosate

    Directory of Open Access Journals (Sweden)

    André Luiz de Souza Lacerda

    2004-01-01

    . The herbicide glyphosate, inhibitor of the enzyme EPSPs, was used at rate 0.0; 11.3; 22.5; 45; 90; 180; 360; 720 and 1440 g.ha-1 a.i. Curves of dose-response were made by the adjustment of the equation of the collected data of green biomass using the log-logistic model: Y = C+D-C / 1 + Exp{b[log(x-log(RC50]}, calculated by the no linear statistical model through the SAS statistical program. After the determination of the dose-response curves for the species mentioned above the Bidens pilosa was considered the most susceptible weed to glyphosate, showing the houvest RC50 (31.86 g.ha-1 a.i.. The species Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia and Commelina benghalensis obtained RC50 equal to 58.40; 128.50; 250.44; 615.49 and > 1440.00 g.ha-1 a.i., respectively, what means that the necessary amount of herbicide to reduce in 50% the green biomass was 1.83; 4.03; 7.86; 19.31 and >359.56 times higher in relation the Bidens pilosa.

  4. Maintenance hemodialysis patients have high cumulative radiation exposure.

    LENUS (Irish Health Repository)

    Kinsella, Sinead M

    2010-10-01

    Hemodialysis is associated with an increased risk of neoplasms which may result, at least in part, from exposure to ionizing radiation associated with frequent radiographic procedures. In order to estimate the average radiation exposure of those on hemodialysis, we conducted a retrospective study of 100 patients in a university-based dialysis unit followed for a median of 3.4 years. The number and type of radiological procedures were obtained from a central radiology database, and the cumulative effective radiation dose was calculated using standardized, procedure-specific radiation levels. The median annual radiation dose was 6.9 millisieverts (mSv) per patient-year. However, 14 patients had an annual cumulative effective radiation dose over 20 mSv, the upper averaged annual limit for occupational exposure. The median total cumulative effective radiation dose per patient over the study period was 21.7 mSv, in which 13 patients had a total cumulative effective radiation dose over 75 mSv, a value reported to be associated with a 7% increased risk of cancer-related mortality. Two-thirds of the total cumulative effective radiation dose was due to CT scanning. The average radiation exposure was significantly associated with the cause of end-stage renal disease, history of ischemic heart disease, transplant waitlist status, number of in-patient hospital days over follow-up, and death during the study period. These results highlight the substantial exposure to ionizing radiation in hemodialysis patients.

  5. Response of human fibroblasts to low dose rate gamma irradiation

    International Nuclear Information System (INIS)

    Dritschilo, A.; Brennan, T.; Weichselbaum, R.R.; Mossman, K.L.

    1984-01-01

    Cells from 11 human strains, including fibroblasts from patients with the genetic diseases of ataxia telangiectasia (AT), xeroderma pigmentosum (XP), and Fanconi's anemia (FA), were exposed to γ radiation at high (1.6-2.2 Gy/min) and at low (0.03-0.07 Gy/min) dose rates. Survival curves reveal an increase inthe terminal slope (D 0 ) when cells are irradiated at low dose rates compared to high dose rates. This was true for all cell lines tested, although the AT, FA, and XP cells are reported or postulated to have radiation repair deficiencies. From the response of these cells, it is apparent that radiation sensitivities differ; however, at low dose rate, all tested human cells are able to repair injury

  6. Derivation of electron and photon energy spectra from electron beam central axis depth dose curves

    Energy Technology Data Exchange (ETDEWEB)

    Deng Jun [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)]. E-mail: jun@reyes.stanford.edu; Jiang, Steve B.; Pawlicki, Todd; Li Jinsheng; Ma, C.M. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)

    2001-05-01

    A method for deriving the electron and photon energy spectra from electron beam central axis percentage depth dose (PDD) curves has been investigated. The PDD curves of 6, 12 and 20 MeV electron beams obtained from the Monte Carlo full phase space simulations of the Varian linear accelerator treatment head have been used to test the method. We have employed a 'random creep' algorithm to determine the energy spectra of electrons and photons in a clinical electron beam. The fitted electron and photon energy spectra have been compared with the corresponding spectra obtained from the Monte Carlo full phase space simulations. Our fitted energy spectra are in good agreement with the Monte Carlo simulated spectra in terms of peak location, peak width, amplitude and smoothness of the spectrum. In addition, the derived depth dose curves of head-generated photons agree well in both shape and amplitude with those calculated using the full phase space data. The central axis depth dose curves and dose profiles at various depths have been compared using an automated electron beam commissioning procedure. The comparison has demonstrated that our method is capable of deriving the energy spectra for the Varian accelerator electron beams investigated. We have implemented this method in the electron beam commissioning procedure for Monte Carlo electron beam dose calculations. (author)

  7. Survival patterns and hemopathological responses of dogs under continuous gamma irradiation

    International Nuclear Information System (INIS)

    Seed, T.M.; Fritz, T.E.; Tolle, D.V.; Poole, C.M.; Lombard, L.S.; Doyle, D.E.; Kaspar, L.V.; Cullen, S.M.; Carnes, B.A.

    1983-01-01

    Survival curves were constructed and analyzed relative to contributing hematopathological responses for groups of beagles exposed continuously for duration of life to low daily doses of whole body 60 Co gamma irradiation (27.3 rads/day to 4 rads/day). The survival curves versus time were progressively displaced toward longer survival as rates of exposure were reduced from the relatively high dose rate of 27.3 rads/day to the low dose rate of 4.0 rads/day. Average survival times increased from 57 days at 27.3 rads/day to 1830 days at 4.0 rads/day, representing fractional increased life-spans from 1.5% to 50.8%, respectively. Survival curves versus total dose were markedly displaced along the cumulative radiation dose axis at the extreme dose rates (i.e., 27.3 and 4.0 rads/day), but not at the intermediate dose rates (i.e., 13.4 and 7.9 rads/day) in which the upper linear portions of the survival curves are superimposed. From these dose-dependent survival curves, LD 50 values for whole body gamma irradiation, delivered chronically at 27.3, 13.4, 7.9, and 4.0 rads per day were estimated to be 1442, 2124, 2039, and 7161 rads, respectively. Both time- and dose-dependent survival curves for the intermediate dose rates, in contrast to the extreme dose rates, exhibited pronounced transitions in the lethality rate below the 50% survival level. These lethality rate transitions occurred at approx. 2500 rads of accumulated dose and were attributed to a shift in the spectrum of developing hematopathologies: namely, from a predominance of the acutely ablative radiation-induced lymphohematopoietic syndromes (i.e., septicemias and aplastic anemias) to a predominance of the late arising hematopoietic neoplasias (myelogenous leukemia and related myeloproliferative disorders)

  8. Human cytogenetic dosimetry: a dose-response relationship for alpha particle radiation from 241Am

    International Nuclear Information System (INIS)

    DuFrain, R.J.; Littlefield, L.G.; Joiner, E.E.; Frome, E.L.

    1979-01-01

    Cytogenetic dosimetry estimates to guide treatment of persons internally contaminated with transuranic elements have not previously been possible because appropriate in vitro dose-response curves specifically for alpha particle irradiation of human lymphocytes do not exist. Using well-controlled cytogenetic methods for human lymphocyte culture, an experimentally derived dose-response curve for 241 Am alpha particle (5.49 and 5.44 MeV) radiation of G 0 lymphocytes was generated. Cells were exposed to 43.8, 87.7, 175.3 or 350.6 nCi/ml 241 Am for 1.7 hr giving doses of 0.85, 1.71, 3.42 or 6.84 rad. Based on dicentric chromosome yield, the linear dose-response equation is Y = 4.90(+-0.42) x 10 -2 X, with Y given as dicentrics per cell and X as dose in rads. The study also shows that the two-break asymmetrical exchanges in cells damaged by alpha particle radiation are overdispersed when compared to a Poisson distribution. An example is presented to show how the derived dose-response equation can be used to estimate the radiation dose for a person internally contaminated with an actinide. An experimentally derived RBE value of 118 at 0.85 rad is calculated for the efficiency of 241 Am alpha particle induction of dicentric chromosomes in human G 0 lymphocytes as compared with the efficiency of 60 Co gamma radiation. The maximum theoretical value for the RBE for cytogenetic damage from alpha irradiation was determined to be 278 at 0.1 rad or less which is in marked contrast to previously reported RBE values of approx. 20. (author)

  9. A unified dose response relationship to predict high dose fractionation response in the lung cancer stereotactic body radiation therapy

    Directory of Open Access Journals (Sweden)

    Than S Kehwar

    2017-01-01

    Full Text Available Aim: This study is designed to investigate the superiority and applicability of the model among the linear-quadratic (LQ, linear-quadratic-linear (LQ-L and universal-survival-curve (USC models by fitting published radiation cell survival data of lung cancer cell lines. Materials and Method: The radiation cell survival data for small cell (SC and non-small cell (NSC lung cancer cell lines were obtained from published reports, and were used to determine the LQ and cell survival curve parameters, which ultimately were used in the curve fitting of the LQ, LQ-L and USC models. Results: The results of this study demonstrate that the LQ-L(Dt-mt model, compared with the LQ and USC models, provides best fit with smooth and gradual transition to the linear portion of the curve at transition dose Dt-mt, where the LQ model loses its validity, and the LQ-L(Dt-2α/β and USC(Dt-mt models do not transition smoothly to the linear portion of the survival curve. Conclusion: The LQ-L(Dt-mt model is able to fit wide variety of cell survival data over a very wide dose range, and retains the strength of the LQ model in the low-dose range.

  10. PSOD: an interactive Fortran program to simulate the radiation dose response of membrane populations

    International Nuclear Information System (INIS)

    Perry, K.A.; Szekely, J.G.

    1982-04-01

    Program PSOD was written to simulate the distribution in responses of membrane populations subjected to random radiation doses and dose rates. It computes the response (damage) according to one of three formulas selected by the user, and outputs statistical results to the terminal. It will plot simulated dose- and response-frequency distributions in two or three dimensions. Doses and dose rates are selected from the log normal distribution; other distributions can be incorporated as the need arises. A true log normal curve with defined mean and standard deviation can also be generated. The purpose of this documentation is to provide a complete operating manual for the program. A user guide is available on-line after initiating a session of PSOD. Detailed examinations of the statistical validity of various steps have been included to aid future modifications and updating

  11. Optimization of equivalent uniform dose using the L-curve criterion

    International Nuclear Information System (INIS)

    Chvetsov, Alexei V; Dempsey, James F; Palta, Jatinder R

    2007-01-01

    Optimization of equivalent uniform dose (EUD) in inverse planning for intensity-modulated radiation therapy (IMRT) prevents variation in radiobiological effect between different radiotherapy treatment plans, which is due to variation in the pattern of dose nonuniformity. For instance, the survival fraction of clonogens would be consistent with the prescription when the optimized EUD is equal to the prescribed EUD. One of the problems in the practical implementation of this approach is that the spatial dose distribution in EUD-based inverse planning would be underdetermined because an unlimited number of nonuniform dose distributions can be computed for a prescribed value of EUD. Together with ill-posedness of the underlying integral equation, this may significantly increase the dose nonuniformity. To optimize EUD and keep dose nonuniformity within reasonable limits, we implemented into an EUD-based objective function an additional criterion which ensures the smoothness of beam intensity functions. This approach is similar to the variational regularization technique which was previously studied for the dose-based least-squares optimization. We show that the variational regularization together with the L-curve criterion for the regularization parameter can significantly reduce dose nonuniformity in EUD-based inverse planning

  12. Optimization of equivalent uniform dose using the L-curve criterion

    Energy Technology Data Exchange (ETDEWEB)

    Chvetsov, Alexei V; Dempsey, James F; Palta, Jatinder R [Department of Radiation Oncology, University of Florida, Gainesville, FL 32610-0385 (United States)

    2007-09-21

    Optimization of equivalent uniform dose (EUD) in inverse planning for intensity-modulated radiation therapy (IMRT) prevents variation in radiobiological effect between different radiotherapy treatment plans, which is due to variation in the pattern of dose nonuniformity. For instance, the survival fraction of clonogens would be consistent with the prescription when the optimized EUD is equal to the prescribed EUD. One of the problems in the practical implementation of this approach is that the spatial dose distribution in EUD-based inverse planning would be underdetermined because an unlimited number of nonuniform dose distributions can be computed for a prescribed value of EUD. Together with ill-posedness of the underlying integral equation, this may significantly increase the dose nonuniformity. To optimize EUD and keep dose nonuniformity within reasonable limits, we implemented into an EUD-based objective function an additional criterion which ensures the smoothness of beam intensity functions. This approach is similar to the variational regularization technique which was previously studied for the dose-based least-squares optimization. We show that the variational regularization together with the L-curve criterion for the regularization parameter can significantly reduce dose nonuniformity in EUD-based inverse planning.

  13. Optimization of equivalent uniform dose using the L-curve criterion.

    Science.gov (United States)

    Chvetsov, Alexei V; Dempsey, James F; Palta, Jatinder R

    2007-10-07

    Optimization of equivalent uniform dose (EUD) in inverse planning for intensity-modulated radiation therapy (IMRT) prevents variation in radiobiological effect between different radiotherapy treatment plans, which is due to variation in the pattern of dose nonuniformity. For instance, the survival fraction of clonogens would be consistent with the prescription when the optimized EUD is equal to the prescribed EUD. One of the problems in the practical implementation of this approach is that the spatial dose distribution in EUD-based inverse planning would be underdetermined because an unlimited number of nonuniform dose distributions can be computed for a prescribed value of EUD. Together with ill-posedness of the underlying integral equation, this may significantly increase the dose nonuniformity. To optimize EUD and keep dose nonuniformity within reasonable limits, we implemented into an EUD-based objective function an additional criterion which ensures the smoothness of beam intensity functions. This approach is similar to the variational regularization technique which was previously studied for the dose-based least-squares optimization. We show that the variational regularization together with the L-curve criterion for the regularization parameter can significantly reduce dose nonuniformity in EUD-based inverse planning.

  14. Statistical issues in radiation dose-response analysis of employees of the nuclear industry in Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Frome, E.L.; Watkins, J.P.

    1997-01-01

    Poisson regression methods are used to describe dose-response relations for cancer mortality for a subcohort of 28,347 white male radiation workers. Age specific baseline rates are described using both internal and external (US white male) rates. Regression analyses are based on an analytic data structure (ADS) that consists of a table of observed deaths, expected deaths, and person-years at risk for each combination of levels of seven risk factors. The factors are socioeconomic status, length of employment, birth cohort, age at risk, facility, internal exposure, and external exposure. Each observation in the ADS consists of the index value of each of the stratifying factors, the observed deaths, the expected deaths, the person-years, and the ten year lagged average cumulative dose. Regression diagnostics show that a linear exponential relative risk model is not appropriate for these data. Results are presented using a main effects model for factors other than external radiation, and an excess relative risk term for cumulative external radiation dose

  15. Clinical significance of cumulative biological effective dose and overall treatment time in the treatment of carcinoma cervix

    Directory of Open Access Journals (Sweden)

    Mandal Abhijit

    2007-01-01

    Full Text Available The purpose of this retrospective study is to report the radiotherapy treatment response of, and complications in, patients with cervical cancer on the basis of cumulative biologic effective dose (BED and overall treatment time (OTT. Sixty-four (stage II - 35/64; stage III - 29/64 patients of cervical cancer were treated with combination of external beam radiotherapy (EBRT and low dose rate intracavitary brachytherapy (ICBT. The cumulative BED was calculated at Point A (BED 10 ; and bladder, rectal reference points (BED 2.5 using the linear-quadratic BED equations. The local control (LC rate and 5-year disease-free survival (DFS rate in patients of stage II were comparable for BED 10 < 84.5 and BED 10 > 84.5 but were much higher for BED 10 > 84.5 than BED 10 < 84.5 ( P < 0.01 in stage III patients. In the stage II patients, The LC rate and 5-year DFS rate were comparable for OTT < 50 days and for OTT> 50 days but were much higher in stage III patients with OTT < 50 than OTT> 50 days ( P < 0.001. It was also observed that patients who received BED 2.5 < 105 had lesser rectal ( P < 0.001 and bladder complications than BED 2.5 > 105. Higher rectal complication-free survival (CFS R rate, bladder complication-free survival (CFS B rate and all-type late complication-free survival rate were observed in patients who received BED 2.5 < 105 than BED 2.5 > 105. A balanced, optimal and justified radiotherapy treatment schedule to deliver higher BED 10 (>84.5 and lower BED 2.5 (< 105 in lesser OTT (< 50 days is essential in carcinoma cervix to expect a better treatment outcome in all respects.

  16. Method for calculating individual equivalent doses and cumulative dose of population in the vicinity of nuclear power plant site

    International Nuclear Information System (INIS)

    Namestek, L.; Khorvat, D; Shvets, J.; Kunz, Eh.

    1976-01-01

    A method of calculating the doses of external and internal person irradiation in the nuclear power plant vicinity under conditions of normal operation and accident situations has been described. The main difference between the above method and methods used up to now is the use of a new antropomorphous representation of a human body model together with all the organs. The antropomorphous model of human body and its organs is determined as a set of simple solids, coordinates of disposistion of the solids, sizes, masses, densities and composition corresponding the genuine organs. The use of the Monte-Carlo method is the second difference. The results of the calculations according to the model suggested can be used for determination: a critical group of inhabitans under conditions of normal plant operation; groups of inhabitants most subjected to irradiation in the case of possible accident; a critical sector with a maximum collective dose in the case of an accident; a critical radioisotope favouring the greatest contribution to an individual equivalent dose; critical irradiation ways promoting a maximum contribution to individual equivalent doses; cumulative collective doses for the whole region or for a chosen part of the region permitting to estimate a population dose. The consequent method evoluation suggests the development of separate units of the calculationg program, critical application and the selection of input data of physical, plysiological and ecological character and improvement of the calculated program for the separate concrete events [ru

  17. Implications of tissue target-cell survival-curve shape for values of split-dose recovery doses: late versus early effects

    International Nuclear Information System (INIS)

    Redpath, J.L.; Peel, D.M.; Hopewell, J.W.

    1984-01-01

    Recent data from this laboratory on split-dose recovery for early and late effects in pig skin are consistent with the linear-quadratic model for cell survival, and with relative cell survival-curve shapes for early- and late-effect target cells where the early-effect cells have an intially steeper and straighter survival-curve than the late-effect cells. (author)

  18. Albumin treatment regimen for type 1 hepatorenal syndrome: a dose-response meta-analysis.

    Science.gov (United States)

    Salerno, Francesco; Navickis, Roberta J; Wilkes, Mahlon M

    2015-11-25

    Recommended treatment for type 1 hepatorenal syndrome consists of albumin and vasoconstrictor. The optimal albumin dose remains poorly characterized. This meta-analysis aimed to determine the impact of albumin dose on treatment outcomes. Clinical studies of type 1 hepatorenal syndrome treatment with albumin and vasoconstrictor were sought. Search terms included: hepatorenal syndrome; albumin; vasoconstrictor; terlipressin; midodrine; octreotide; noradrenaline; and norepinephrine. A meta-analysis was performed of hepatorenal syndrome reversal and survival in relation to albumin dose. Nineteen clinical studies with 574 total patients were included, comprising 8 randomized controlled trials, 8 prospective studies and 3 retrospective studies. The pooled percentage of patients achieving hepatorenal syndrome reversal was 49.5% (95% confidence interval, 40.0-59.1%). Increments of 100 g in cumulative albumin dose were accompanied by significantly increased survival (hazard ratio, 1.15; 95% confidence interval, 1.02-1.31; p = 0.023). A non-significant increase of similar magnitude in hepatorenal syndrome reversal was also observed (odds ratio, 1.15; 95% confidence interval, 0.97-1.37; p = 0.10). Expected survival rates at 30 days among patients receiving cumulative albumin doses of 200, 400 and 600 g were 43.2% (95% confidence interval, 36.4-51.3%), 51.4% (95% confidence interval, 46.3-57.1%) and 59.0% (95% confidence interval, 51.9-67.2), respectively. Neither survival nor hepatorenal syndrome reversal was significantly affected by vasoconstrictor dose or type, treatment duration, age, baseline serum creatinine, bilirubin or albumin, baseline mean arterial pressure, or study design, size or time period. This meta-analysis suggests a dose-response relationship between infused albumin and survival in patients with type 1 hepatorenal syndrome. The meta-analysis provides the best current evidence on the potential role of albumin dose selection in improving outcomes of

  19. Quantitative assessment of the dose-response of alkylating agents in DNA repair proficient and deficient ames tester strains.

    Science.gov (United States)

    Tang, Leilei; Guérard, Melanie; Zeller, Andreas

    2014-01-01

    Mutagenic and clastogenic effects of some DNA damaging agents such as methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) have been demonstrated to exhibit a nonlinear or even "thresholded" dose-response in vitro and in vivo. DNA repair seems to be mainly responsible for these thresholds. To this end, we assessed several mutagenic alkylators in the Ames test with four different strains of Salmonella typhimurium: the alkyl transferases proficient strain TA1535 (Ogt+/Ada+), as well as the alkyl transferases deficient strains YG7100 (Ogt+/Ada-), YG7104 (Ogt-/Ada+) and YG7108 (Ogt-/Ada-). The known genotoxins EMS, MMS, temozolomide (TMZ), ethylnitrosourea (ENU) and methylnitrosourea (MNU) were tested in as many as 22 concentration levels. Dose-response curves were statistically fitted by the PROAST benchmark dose model and the Lutz-Lutz "hockeystick" model. These dose-response curves suggest efficient DNA-repair for lesions inflicted by all agents in strain TA1535. In the absence of Ogt, Ada is predominantly repairing methylations but not ethylations. It is concluded that the capacity of alkyl-transferases to successfully repair DNA lesions up to certain dose levels contributes to genotoxicity thresholds. Copyright © 2013 Wiley Periodicals, Inc.

  20. Linking fluorescence induction curve and biomass in herbicide screening.

    Science.gov (United States)

    Christensen, Martin G; Teicher, Harald B; Streibig, Jens C

    2003-12-01

    A suite of dose-response bioassays with white mustard (Sinapis alba L) and sugar beet (Beta vulgaris L) in the greenhouse and with three herbicides was used to analyse how the fluorescence induction curves (Kautsky curves) were affected by the herbicides. Bentazone, a photosystem II (PSII) inhibitor, completely blocked the normal fluorescence decay after the P-step. In contrast, fluorescence decay was still obvious for flurochloridone, a PDS inhibitor, and glyphosate, an EPSP inhibitor, which indicated that PSII inhibition was incomplete. From the numerous parameters that can be derived from OJIP-steps of the Kautsky curve the relative changes at the J-step [Fvj = (Fm - Fj)/Fm] was selected to be a common response parameter for the herbicides and yielded consistent dose-response relationships. Four hours after treatment, the response Fvj on the doses of bentazone and flurochloridone could be measured. For glyphosate, the changes of the Kautsky curve could similarly be detected 4 h after treatment in sugar beet, but only after 24 hs in S alba. The best prediction of biomass in relation to Fvj was found for bentazone. The experiments were conducted between May and August 2002 and showed that the ambient temperature and solar radiation in the greenhouse could affect dose-response relationships. If the Kautsky curve parameters should be used to predict the outcome of herbicide screening experiments in the greenhouse, where ambient radiation and temperature can only partly be controlled, it is imperative that the chosen fluorescence parameters can be used to predict accurately the resulting biomass used in classical bioassays.

  1. Universal Survival Curve and Single Fraction Equivalent Dose: Useful Tools in Understanding Potency of Ablative Radiotherapy

    International Nuclear Information System (INIS)

    Park, Clint; Papiez, Lech; Zhang Shichuan; Story, Michael; Timmerman, Robert D.

    2008-01-01

    Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and well-tolerated therapeutic option. The aim of this study was to offer an alternative method of analyzing the effect of SBRT by constructing a universal survival curve (USC) that provides superior approximation of the experimentally measured survival curves in the ablative, high-dose range without losing the strengths of the LQ model around the shoulder. Methods and Materials: The USC was constructed by hybridizing two classic radiobiologic models: the LQ model and the multitarget model. We have assumed that the LQ model gives a good description for conventionally fractionated radiotherapy (CFRT) for the dose to the shoulder. For ablative doses beyond the shoulder, the survival curve is better described as a straight line as predicted by the multitarget model. The USC smoothly interpolates from a parabola predicted by the LQ model to the terminal asymptote of the multitarget model in the high-dose region. From the USC, we derived two equivalence functions, the biologically effective dose and the single fraction equivalent dose for both CFRT and SBRT. Results: The validity of the USC was tested by using previously published parameters of the LQ and multitarget models for non-small-cell lung cancer cell lines. A comparison of the goodness-of-fit of the LQ and USC models was made to a high-dose survival curve of the H460 non-small-cell lung cancer cell line. Conclusion: The USC can be used to compare the dose fractionation schemes of both CFRT and SBRT. The USC provides an empirically and a clinically well-justified rationale for SBRT while preserving the strengths of the LQ model for CFRT

  2. A dose-effect curve of premature condensation chromosome ring in lymphocytes of human peripheral blood exposed to high dose of 60Co γ-rays in vitro

    International Nuclear Information System (INIS)

    Yao Bo; Li Yufang; Liu Guangxian; Huang Shan; Jiang Benrong; Ai Huisheng

    2009-01-01

    Objective: To establish a dose-effect curve of premature condensation chromosome ring (PCC-R) in lymphocytes of human peripheral blood after exposed to high doses of γ-rays. Methods: Peripheral blood samples was drawn from three healthy individuals, and exposed to 60 Co γ-rays with doses between 0 and 30 Gy. The frequencies of PCC-R in premature condensation chromosome (PCC) cells obtained by Okadaic acid (OA) induction were calculated, and a dose-effect curve was fitted. Results: PCC index tapered with dose. Frequencies of PCC-R per cell increased until 20 Gy, and then saturation was observed. The results were fitted to a lineal model up to 20 Gy: y=-0.020 + 0.052D, where y was the frequencies of PCC-R per cell, D was the radiation dose(Gy). Conclusions: The highest dose could be estimated is 20 Gy by the dose-effect curve established with PCC-R method. Its utility and validity will be verified in the future application of radiation accident. (authors)

  3. Dose-effect curves for electron-beam irradiation of some collection microbial strains

    International Nuclear Information System (INIS)

    Ferdes, O.; Dumitru, E.; Catargiu, L.; Ferdes, M.; Minea, R.; Oproiu, C.; Niculescu, A.

    1994-01-01

    There were electron-beam irradiated some microbial strains of B.subtilis ICA I-60 both in germination and in sporulated forms. The irradiation were performed at the IPTRD's electron accelerator at 6 MeV, and in the dose range between 0.1-5.0 kGy, at different dose-rate varying from 50 Gy/minute to 100 Gy/minute. The dosimetry was carried out by a PTW medical dosemeter. There were established the dose-effect relationships and curves, the inactivation dose (factor) and the optimum domain for electron-beam mutagenesis. There were obtained some mutant strains with 2-3.5 higher biosynthesis potential, which are in the IFC's collection. (Author)

  4. Assessing the implications of human land-use change for the transient climate response to cumulative carbon emissions

    International Nuclear Information System (INIS)

    Simmons, C T; Matthews, H D

    2016-01-01

    Recent research has shown evidence of a linear climate response to cumulative CO 2 emissions, which implies that the source, timing, and amount of emissions does not significantly influence the climate response per unit emission. Furthermore, these analyses have generally assumed that the climate response to land-use CO 2 emissions is equivalent to that of fossil fuels under the assumption that, once in the atmosphere, the radiative forcing induced by CO 2 is not sensitive to the emissions source. However, land-cover change also affects surface albedo and the strength of terrestrial carbon sinks, both of which have an additional climate effect. In this study, we use a coupled climate-carbon cycle model to assess the climate response to historical and future cumulative land-use CO 2 emissions, in order to compare it to the response to fossil fuel CO 2 . We find that when we isolate the CO 2 -induced (biogeochemical) temperature changes associated with land-use change, then the climate response to cumulative land-use emissions is equivalent to that of fossil fuel CO 2 . We show further that the globally-averaged albedo-induced biophysical cooling from land-use change is non-negligible and may be of comparable magnitude to the biogeochemical warming, with the result that the net climate response to land-use change is substantially different from a linear response to cumulative emissions. However, our new simulations suggest that the biophysical cooling from land-use change follows its own independent (negative) linear response to cumulative net land-use CO 2 emissions, which may provide a useful scaling factor for certain applications when evaluating the full transient climate response to emissions. (letter)

  5. Re-irradiation: Outcome, cumulative dose and toxicity in patients retreated with stereotactic radiotherapy in the abdominal or pelvic region

    NARCIS (Netherlands)

    H. Abusaris (Huda); M.S. Hoogeman (Mischa); J.J.M.E. Nuyttens (Joost)

    2012-01-01

    textabstractThe purpose of the present study was to explore the outcome, cumulative dose in tumor and organs at risk and toxicity after extra-cranial stereotactic re-irradiation. Twenty-seven patients were evaluated who had been re-irradiated with stereotactic body radiotherapy (SBRT) after

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

    Energy Technology Data Exchange (ETDEWEB)

    Berrington de Gonzalez, Amy, E-mail: berringtona@mail.nih.gov [Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States); Gilbert, Ethel; Curtis, Rochelle; Inskip, Peter; Kleinerman, Ruth; Morton, Lindsay; Rajaraman, Preetha; Little, Mark P. [Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States)

    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.

  7. Morphology of the cumulative logistic distribution when used as a model of radiologic film characteristic curves

    International Nuclear Information System (INIS)

    Prince, J.R.

    1988-01-01

    The cumulative logistic distribution (CLD) is an empiric model for film characteristic curves. Characterizing the shape parameters of the CLD in terms of contrast, latitude and speed is required. The CLD is written as Υ-F=D/[1+EXP-(Κ+κ 1 X)] where Υ is the optical density (OD) at log exposure X, F is fog level, D is a constant equal to Dm-F, Κ and κ 1 are shape parameters, and Dm is the maximum attainable OD. Further analysis demonstrates that when Κ is held constant, Κ 1 characterizes contrast (the larger κ 1 , the greater the contrast) and hence latitude; when κ 1 is held constant, Κ characterizes film speed (the larger Κ is, the faster the film). These equations and concepts are further illustrated with examples from radioscintigraphy, diagnostic radiology, and light sensitometry

  8. Low-dose mutation-response relationships in Tradescantia; principles and comparison to mutagenesis following low-dose gaseous chemical mutagen exposure

    International Nuclear Information System (INIS)

    Nauman, C.H.; Sparrow, A.H.; Underbrink, A.G.; Schairer, L.A.

    1976-01-01

    Inflorescences of several clones of Tradescantia heterozygous for flower color have been treated with ionizing radiation and with the gaseous form of several known or suspected chemical mutagens. Pink somatic mutations were subsequently scored in the stamen hair cells of mature flowers and dose-/exposure-response curves constructed. Results indicate clearly that there is no evidence for a threshold for mutation response following x or neutron irradiation. Results so far obtained for gaseous chemical mutagens are less clear, but also suggest that there is no threshold for mutation response

  9. SU-E-J-106: The Use of Deformable Image Registration with Cone-Beam CT for a Better Evaluation of Cumulative Dose to Organs

    Energy Technology Data Exchange (ETDEWEB)

    Fillion, O; Gingras, L; Archambault, L [Universite Laval, Quebec, Quebec (Canada); Centre de recherche du CHU de Quebec, Quebec, Quebec (Canada); Centre de recherche sur le cancer, Quebec, Quebec (Canada)

    2015-06-15

    Purpose: The knowledge of dose accumulation in the patient tissues in radiotherapy helps in determining the treatment outcomes. This project aims at providing a workflow to map cumulative doses that takes into account interfraction organ motion without the need for manual re-contouring. Methods: Five prostate cancer patients were studied. Each patient had a planning CT (pCT) and 5 to 13 CBCT scans. On each series, a physician contoured the prostate, rectum, bladder, seminal vesicles and the intestine. First, a deformable image registration (DIR) of the pCTs onto the daily CBCTs yielded registered CTs (rCT) . This rCT combined the accurate CT numbers of the pCT with the daily anatomy of the CBCT. Second, the original plans (220 cGy per fraction for 25 fractions) were copied on the rCT for dose re-calculation. Third, the DIR software Elastix was used to find the inverse transform from the rCT to the pCT. This transformation was then applied to the rCT dose grid to map the dose voxels back to their pCT location. Finally, the sum of these deformed dose grids for each patient was applied on the pCT to calculate the actual dose delivered to organs. Results: The discrepancy between the planned D98 and D2 and these indices re-calculated on the rCT, are, on average, of −1 ± 1 cGy and 1 ± 2 cGy per fraction, respectively. For fractions with large anatomical motion, the D98 discrepancy on the re-calculated dose grid mapped onto the pCT can raise to −17 ± 4 cGy. The obtained cumulative dose distributions illustrate the same behavior. Conclusion: This approach allowed the evaluation of cumulative doses to organs with the help of uncontoured daily CBCT scans. With this workflow, the easy evaluation of doses delivered for EBRT treatments could ultimately lead to a better follow-up of prostate cancer patients.

  10. SU-E-J-106: The Use of Deformable Image Registration with Cone-Beam CT for a Better Evaluation of Cumulative Dose to Organs

    International Nuclear Information System (INIS)

    Fillion, O; Gingras, L; Archambault, L

    2015-01-01

    Purpose: The knowledge of dose accumulation in the patient tissues in radiotherapy helps in determining the treatment outcomes. This project aims at providing a workflow to map cumulative doses that takes into account interfraction organ motion without the need for manual re-contouring. Methods: Five prostate cancer patients were studied. Each patient had a planning CT (pCT) and 5 to 13 CBCT scans. On each series, a physician contoured the prostate, rectum, bladder, seminal vesicles and the intestine. First, a deformable image registration (DIR) of the pCTs onto the daily CBCTs yielded registered CTs (rCT) . This rCT combined the accurate CT numbers of the pCT with the daily anatomy of the CBCT. Second, the original plans (220 cGy per fraction for 25 fractions) were copied on the rCT for dose re-calculation. Third, the DIR software Elastix was used to find the inverse transform from the rCT to the pCT. This transformation was then applied to the rCT dose grid to map the dose voxels back to their pCT location. Finally, the sum of these deformed dose grids for each patient was applied on the pCT to calculate the actual dose delivered to organs. Results: The discrepancy between the planned D98 and D2 and these indices re-calculated on the rCT, are, on average, of −1 ± 1 cGy and 1 ± 2 cGy per fraction, respectively. For fractions with large anatomical motion, the D98 discrepancy on the re-calculated dose grid mapped onto the pCT can raise to −17 ± 4 cGy. The obtained cumulative dose distributions illustrate the same behavior. Conclusion: This approach allowed the evaluation of cumulative doses to organs with the help of uncontoured daily CBCT scans. With this workflow, the easy evaluation of doses delivered for EBRT treatments could ultimately lead to a better follow-up of prostate cancer patients

  11. Effects of prescription depth, cylinder size, treatment length, tip space, and curved end on doses in high-dose-rate vaginal brachytherapy

    International Nuclear Information System (INIS)

    Li Shidong; Aref, Ibrahim; Walker, Eleanor; Movsas, Benjamin

    2007-01-01

    Purpose: To determine the effects of the prescription depth, cylinder size, treatment length, tip space, and curved end on high-dose-rate vaginal brachytherapy (HDR-VBT) of endometrial cancer. Methods and Materials: Treatment plans were prescribed and optimized based on points at the cylinder surface or at 0.5-cm depth. Cylinder sizes ranging from 2 to 4 cm in diameter, and treatment lengths ranging from 3 to 8 cm were used. Dose points in various depths were precisely defined along the cylinder dome. The given dose and dose uniformity to a depth of interest were measured by the mean dose (MD) and standard deviation (SD), respectively, among the dose points belonging to the depth. Dose fall-off beyond the 0.5 cm treatment depth was determined by the ratio of MD at 0.75-cm depth to MD at 0.5-cm depth. Results: Dose distribution varies significantly with different prescriptions. The surface prescription provides more uniform doses at all depths in the target volume, whereas the 0.5-cm depth prescription creates larger dose variations at the cylinder surface. Dosimetric uncertainty increases significantly (>30%) with shorter tip space. Extreme hot (>150%) and cold spots (<60%) occur if no optimization points were placed at the curved end. Conclusions: Instead of prescribing to a depth of 0.5 cm, increasing the dose per fraction and prescribing to the surface with the exact surface points around the cylinder dome appears to be the optimal approach

  12. Analysis of LDPE-ZnO-clay nanocomposites using novel cumulative rheological parameters

    Science.gov (United States)

    Kracalik, Milan

    2017-05-01

    Polymer nanocomposites exhibit complex rheological behaviour due to physical and also possibly chemical interactions between individual phases. Up to now, rheology of dispersive polymer systems has been usually described by evaluation of viscosity curve (shear thinning phenomenon), storage modulus curve (formation of secondary plateau) or plotting information about dumping behaviour (e.g. Van Gurp-Palmen-plot, comparison of loss factor tan δ). On the contrary to evaluation of damping behaviour, values of cot δ were calculated and called as "storage factor", analogically to loss factor. Then values of storage factor were integrated over specific frequency range and called as "cumulative storage factor". In this contribution, LDPE-ZnO-clay nanocomposites with different dispersion grades (physical networks) have been prepared and characterized by both conventional as well as novel analysis approach. Next to cumulative storage factor, further cumulative rheological parameters like cumulative complex viscosity, cumulative complex modulus or cumulative storage modulus have been introduced.

  13. Radiation Dose-Response Model for Locally Advanced Rectal Cancer After Preoperative Chemoradiation Therapy

    International Nuclear Information System (INIS)

    Appelt, Ane L.; Pløen, John; Vogelius, Ivan R.; Bentzen, Søren M.; Jakobsen, Anders

    2013-01-01

    Purpose: Preoperative chemoradiation therapy (CRT) is part of the standard treatment of locally advanced rectal cancers. Tumor regression at the time of operation is desirable, but not much is known about the relationship between radiation dose and tumor regression. In the present study we estimated radiation dose-response curves for various grades of tumor regression after preoperative CRT. Methods and Materials: A total of 222 patients, treated with consistent chemotherapy and radiation therapy techniques, were considered for the analysis. Radiation therapy consisted of a combination of external-beam radiation therapy and brachytherapy. Response at the time of operation was evaluated from the histopathologic specimen and graded on a 5-point scale (TRG1-5). The probability of achieving complete, major, and partial response was analyzed by ordinal logistic regression, and the effect of including clinical parameters in the model was examined. The radiation dose-response relationship for a specific grade of histopathologic tumor regression was parameterized in terms of the dose required for 50% response, D 50,i , and the normalized dose-response gradient, γ 50,i . Results: A highly significant dose-response relationship was found (P=.002). For complete response (TRG1), the dose-response parameters were D 50,TRG1 = 92.0 Gy (95% confidence interval [CI] 79.3-144.9 Gy), γ 50,TRG1 = 0.982 (CI 0.533-1.429), and for major response (TRG1-2) D 50,TRG1 and 2 = 72.1 Gy (CI 65.3-94.0 Gy), γ 50,TRG1 and 2 = 0.770 (CI 0.338-1.201). Tumor size and N category both had a significant effect on the dose-response relationships. Conclusions: This study demonstrated a significant dose-response relationship for tumor regression after preoperative CRT for locally advanced rectal cancer for tumor dose levels in the range of 50.4-70 Gy, which is higher than the dose range usually considered.

  14. Harderian Gland Tumorigenesis: Low-Dose and LET Response

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Polly Y. [SRI International, Menlo Park, CA (United States). Biosciences Div.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Div.; Cucinotta, Francis A. [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Health Physics and Diagnostic Sciences; Bjornstad, Kathleen A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Div.; Bakke, James [SRI International, Menlo Park, CA (United States). Biosciences Div.; Rosen, Chris J. [SRI International, Menlo Park, CA (United States). Biosciences Div.; Du, Nicholas [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Div.; Fairchild, David G. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Div.; Cacao, Eliedonna [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Health Physics and Diagnostic Sciences; Blakely, Eleanor A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Div.

    2016-04-19

    Increased cancer risk remains a primary concern for travel into deep space and may preclude manned missions to Mars due to large uncertainties that currently exist in estimating cancer risk from the spectrum of radiations found in space with the very limited available human epidemiological radiation-induced cancer data. Existing data on human risk of cancer from X-ray and gamma-ray exposure must be scaled to the many types and fluences of radiations found in space using radiation quality factors and dose-rate modification factors, and assuming linearity of response since the shapes of the dose responses at low doses below 100 mSv are unknown. The goal of this work was to reduce uncertainties in the relative biological effect (RBE) and linear energy transfer (LET) relationship for space-relevant doses of charged-particle radiation-induced carcinogenesis. The historical data from the studies of Fry et al. and Alpen et al. for Harderian gland (HG) tumors in the female CB6F1 strain of mouse represent the most complete set of experimental observations, including dose dependence, available on a specific radiation-induced tumor in an experimental animal using heavy ion beams that are found in the cosmic radiation spectrum. However, these data lack complete information on low-dose responses below 0.1 Gy, and for chronic low-dose-rate exposures, and there are gaps in the LET region between 25 and 190 keV/μm. In this study, we used the historical HG tumorigenesis data as reference, and obtained HG tumor data for 260 MeV/u silicon (LET ~70 keV/μm) and 1,000 MeV/u titanium (LET ~100 keV/μm) to fill existing gaps of data in this LET range to improve our understanding of the dose-response curve at low doses, to test for deviations from linearity and to provide RBE estimates. Animals were also exposed to five daily fractions of 0.026 or 0.052 Gy of 1,000 MeV/u titanium ions to simulate chronic exposure, and HG tumorigenesis from this fractionated study were compared to the

  15. Estimation of absorbed doses in humans due to intravenous administration of fluorine-18-fluorodeoxyglucose in PET studies

    International Nuclear Information System (INIS)

    Mejia, A.A.; Nakamura, T.; Masatoshi, I.; Hatazawa, J.; Masaki, M.; Watanuki, S.

    1991-01-01

    Radiation absorbed doses due to intravenous administration of fluorine-18-fluorodeoxyglucose in positron emission tomography (PET) studies were estimated in normal volunteers. The time-activity curves were obtained for seven human organs (brain, heart, kidney, liver, lung, pancreas, and spleen) by using dynamic PET scans and for bladder content by using a single detector. These time-activity curves were used for the calculation of the cumulative activity in these organs. Absorbed doses were calculated by the MIRD method using the absorbed dose per unit of cumulated activity, 'S' value, transformed for the Japanese physique and the organ masses of the Japanese reference man. The bladder wall and the heart were the organs receiving higher doses of 1.2 x 10(-1) and 4.5 x 10(-2) mGy/MBq, respectively. The brain received a dose of 2.9 x 10(-2) mGy/MBq, and other organs received doses between 1.0 x 10(-2) and 3.0 x 10(-2) mGy/MBq. The effective dose equivalent was estimated to be 2.4 x 10(-2) mSv/MBq. These results were comparable to values of absorbed doses reported by other authors on the radiation dosimetry of this radiopharmaceutical

  16. Does the acute pulmonary response to ozone depend on the cumulative exposure?

    International Nuclear Information System (INIS)

    Anon.

    2008-01-01

    In experimental conditions, repeated ozone exposure induces adaptive phenomena that attenuate lung function and inflammatory responses. But this study did not find that lifetime cumulative exposure had a protective effect; indeed, it found the contrary. (author)

  17. Synergistic effect of cumulative corticosteroid dose and immunosuppressants on avascular necrosis in patients with systemic lupus erythematosus.

    Science.gov (United States)

    Kwon, H H; Bang, S Y; Won, S; Park, Y; Yi, J H; Joo, Y B; Lee, H S; Bae, S C

    2018-01-01

    Objectives Avascular necrosis (AVN) is one of the most common causes of organ damage in patients with systemic lupus erythematosus (SLE) and often causes serious physical disability. The aims of this study were to investigate clinical risk factors associated with symptomatic AVN and to analyze their synergistic effects in a large SLE cohort in Korea. Methods Patients with SLE were enrolled and followed from 1998 to 2014 in the Hanyang BAE Lupus cohort, and damage was measured annually according to the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI). AVN was confirmed by imaging study if patients had symptoms. To determine risk factors for AVN, clinical, laboratory and therapeutic variables were analyzed by logistic regression. Relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy index (S) were calculated to measure interactions between significant variables. Results Among 1219 SLE patients, symptomatic AVN was the most common type of musculoskeletal damage (10.8%, n = 132). SLE patients with AVN showed an earlier onset age, demonstrated AVN more commonly in conjunction with certain other clinical manifestations such as renal and neuropsychiatric disorders, and received significantly higher total cumulative corticosteroid dose and immunosuppressive agents than did patients without AVN. However, in multivariable analysis, only two variables including use of a cumulative corticosteroid dose greater than 20 g (odds ratio (OR) 3.62, p = 0.015) and use of immunosuppressants including cyclophosphamide or mycophenolate mofetil (OR 4.51, p AVN. Patients with cumulative corticosteroid dose > 20 g and immunosuppressant use had a 15.44-fold increased risk for AVN, compared with patients without these risk factors ( p AVN in our Korean lupus cohort. Conclusions An individual risk assessment for AVN development should be made prior to and during treatment for SLE

  18. Stochastic basis for curve shape, RBE and temporal dependence

    International Nuclear Information System (INIS)

    Bond, V.P.

    1982-01-01

    This paper uses biophysical-microdosimetric quantities, measured in a physical surrogate or phantom cell, to explain the shape of absorbed dose-quantal cell response curves, the role of radiation quality and the influence of dose rate. Responses expected are explored first in simple autonomous cell systems, followed by increasingly-complex systems. Complications seen with increasingly-complex systems appear to be confined largely to the higher dose and dose rate ranges

  19. Cumulative inhibitory effect of low-dose aspirin on vascular prostacyclin and platelet thromboxane production in patients with atherosclerosis.

    Science.gov (United States)

    Weksler, B B; Tack-Goldman, K; Subramanian, V A; Gay, W A

    1985-02-01

    The relationship between the antithrombotic and antiplatelet effects of aspirin is complex, since aspirin influences other systems that protect against thrombosis as well as inhibiting platelet function. We investigated possible cumulative effects of low-dose aspirin on vascular production of prostacyclin in patients with documented atherosclerotic cardiovascular disease. Candidates for coronary artery vein graft bypass ingested 20 mg of aspirin daily during the week before surgery, and platelet aggregation, platelet formation of thromboxane A2 (TXA2), aortic and saphenous vein production of prostacyclin (PGI2), and hemostatic status were measured at the time of the bypass surgery. Low-dose aspirin markedly inhibited platelet aggregation responses and reduced TXA2 generation by greater than 90%, effects similar to those observed with much higher doses of aspirin. Both aortic and saphenous vein production of PGI2 were inhibited by 50% compared with PGI2 produced by vascular tissues of control subjects who received no aspirin preoperatively (51 +/- 10 pg 6-keto-PGF1 alpha/mg aortic wet weight [mean +/- SEM] in aspirin-treated subjects vs 130 +/- 16 pg/mg in control subjects, and 71 +/- 8 pg/mg saphenous vein wet weight vs 131 +/- 17 pg/mg). Blood loss at surgery was not significantly increased by preoperative low-dose aspirin as measured by chest tube drainage (754 +/- 229 ml in aspirin-treated subjects vs 645 +/- 271 ml in control subjects), hematocrit nadir (31.2 +/- 1.9% vs 31.8 +/- 1.7%), or transfusions (2.2 +/- 1.3 units of red blood cells vs 2.2 +/- 1.7 units).(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Relationship of cumulative low-level dose of ionizing radiation on human eye lens and occurrence of cataract

    International Nuclear Information System (INIS)

    Deolalikar, Raghavendra

    2015-01-01

    International Commission on Radiological Protection (ICRP), issued a statement on Tissue Reaction, lowering the equivalent dose limit for eye lens for occupational exposure to 20 mSv per year. With a view to determine presence of any relationship between the cumulative low-level occupational radiation dose to the eye lens and occurrence of cataract, departmental records of the annual medical examination of employees of Narora Atomic Power Plant were examined along with the NAPS eye camps and surgical records of the employees. Analysis of the data showed no demonstrable definite relationship between the two. The analysis of the data and the observations are discussed in this paper. (author)

  1. Dose-response of seeds of the parasitic weeds Striga and Orobanche toward the synthetic germination stimulants GR24.

    NARCIS (Netherlands)

    Wigchert, S.C.M.; Kuiper, E.; Boelhouwer, G.J.; Nefkens, G.H.L.; Verkley, J.A.C.; Zwanenburg, B.

    1999-01-01

    Striga and Orobanche seeds germinate in response to a host-derived germination stimulant. Dose-response curves of the synthetic strigolactone analogues GR 24 and Nijmegen 1 were determined, and their activities were compared to that of the naturally occurring stimulant sorgolactone. Typical

  2. Dose escalation with 3-D CRT in prostate cancer: five year dose responses and optimal treatment

    International Nuclear Information System (INIS)

    Hanks, Gerald; Hanlon, Alexandra; Pinover, Wayne; Hunt, Margie; Movsas, Benjamin; Schultheiss, Timothy

    1997-01-01

    Purpose: To report 5 yr dose responses in prostate cancer patients treated with 3D-CRT and describe optimal treatment based on dose response. Methods: Dose escalation was studied in 233 consecutive patients treated with 3D-CRT between 3/89 and 10/92. All surviving patients have >32 mo follow-up, the median follow-up is 55 mo. Estimated logistic cumulative distribution functions (logit response models) fit to 5 yr actuarial bNED outcome are reported for 3 dose groups in each of 3 pretreatment PSA groupings (10-19.9 ng/ml and 20+ ng/ml); no dose response is observed for patients with pretreatment PSA <10 ng/ml. Logit response models fit to 5 yr actuarial late morbidity rates (grade 2 GI, grade 2 GU, grade 3,4 GI) are also reported for 4 dose groups. Patients are treated with CT planned 4-field conformal technique where the PTV encompasses the CTV by 1.0 cm in all directions including the anterior rectal wall margin. Patients are followed at 6 mo intervals with PSA and DRE, and bNED failure is defined as PSA ≥1.5 ng/ml and rising on two consecutive measures. The Fox Chase modification of the LENT morbidity scale is used for GI morbidity including any blood transfusion and/or more than 2 coagulations as a grade 3 event. GU morbidity follows the RTOG scale. Results: The logit response models based on 5 yr bNED results have slopes of 27% and 18% for pretreatment PSA grouping 10-19.9 ng/ml and 20+ ng/ml, respectively. The 50% bNED response is observed at 71 Gy and 80 Gy respectively, while the 80% bNED response is observed at 76 Gy for the 10-19.9 ng/ml group and estimated at 88 Gy for the 20+ ng/ml group. Logit dose response models for grade 2 GI and grade 2 GU morbidity show markedly different slopes, 23% versus 4%, respectively. The slope for grade 3,4 GI is 12%. The dose response model indicates grade 3,4 GI complication rates at 5 yrs are 8% at 76 Gy and 12% at 80 Gy. Conclusion: Based on 5 yr results, we can draw some conclusions about appropriate dose from these

  3. X-ray dose response of calcite—A comprehensive analysis for optimal application in TL dosimetry

    International Nuclear Information System (INIS)

    Kalita, J.M.; Wary, G.

    2016-01-01

    Highlights: • Effect of annealing temperature on TL signal of calcite has been studied. • Specific annealing treatment for optimal dose response has been evaluated. • The dose response of natural calcite has been analyzed quantitatively. - Abstract: The effect of various annealing treatments on dosimetric characteristics of orange calcite (CaCO_3) mineral has been studied in detail. Quantitative analysis on the dose response shows that the 573 K annealed sample showed sublinear dose response from 10 mGy to 1 Gy. The fading and reproducibility of this sample are also good enough for dosimetric application. However, a specific annealing treatment after irradiation shows some significant improvements in the dosimetric characteristics of the sample. The 773 K pre-annealed sample, after X-ray irradiation post-annealing at 340 K for 6 min provides linear dose response from 10 mGy to 3.60 Gy, very less fading and good reproducibility. Moreover, this sample after post-annealing at 380 K for 6 min shows linear dose response from 10 mGy to 5.40 Gy when analyzed from the ∼408 K thermoluminescence (TL) glow peak. Analysis of TL glow curves confirmed that the 1.30 eV trap center in calcite crystal is the most effective trapping site for dosimetric application.

  4. X-ray dose response of calcite—A comprehensive analysis for optimal application in TL dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, J.M., E-mail: jitukalita09@gmail.com; Wary, G.

    2016-09-15

    Highlights: • Effect of annealing temperature on TL signal of calcite has been studied. • Specific annealing treatment for optimal dose response has been evaluated. • The dose response of natural calcite has been analyzed quantitatively. - Abstract: The effect of various annealing treatments on dosimetric characteristics of orange calcite (CaCO{sub 3}) mineral has been studied in detail. Quantitative analysis on the dose response shows that the 573 K annealed sample showed sublinear dose response from 10 mGy to 1 Gy. The fading and reproducibility of this sample are also good enough for dosimetric application. However, a specific annealing treatment after irradiation shows some significant improvements in the dosimetric characteristics of the sample. The 773 K pre-annealed sample, after X-ray irradiation post-annealing at 340 K for 6 min provides linear dose response from 10 mGy to 3.60 Gy, very less fading and good reproducibility. Moreover, this sample after post-annealing at 380 K for 6 min shows linear dose response from 10 mGy to 5.40 Gy when analyzed from the ∼408 K thermoluminescence (TL) glow peak. Analysis of TL glow curves confirmed that the 1.30 eV trap center in calcite crystal is the most effective trapping site for dosimetric application.

  5. Performance of thermoluminescent materials for high dose dosimetry

    International Nuclear Information System (INIS)

    Texeira, Maria I.; Cecatti, Sonia G.P.; Caldas, Linda V.E.

    2008-01-01

    Cases involving high-doses of ionizing radiation are becoming increasingly common.The objective of this work was to characterize thermoluminescent materials for the dosimetry of workers exposed to high doses. Samples of TLD-200, TLD-400 and TLD-800 pellets from Thermo Electron Corporation were studied in gamma high-doses. Dose-response curves were obtained for doses between 100 mGy and 100 Gy. The reproducibility, the lower detection limits and dose-response curves were obtained for all three materials. The different kinds of detectors show usefulness for dosimetry of workers exposed accidentally to high doses. (author)

  6. The shape of dose-effect curves for diploid yeast cells irradiated with ionizing particles

    International Nuclear Information System (INIS)

    Pohlit, W.

    1975-01-01

    In a cybernetic model for the radiation reactions in eukaryotic cells, after irradiation they are assumed to be in one of three states: (a) viable cells; (b) with repairable damage; and (c) with irreparable damage. Two biological counter reactions with certain time constants can be observed: (i) recovery from sublethal damage; and (ii) repair of potential lethal damage. The shape of the dose-effect curve is influenced in a characteristic way by the different occupation of these states of the cells and by the time constants of the biological counter reactions. The biochemical analysis of the biological counter reactions, recovery and repair, has shown that both are linked together by the energy pool in the cell. In this way changes in the slope of the dose-effect curve due to different metabolic states of the cells can be understood quantitatively. Also the complicated dependence of survival cells on the absorbed dose rate over a wide range can be explained quantitatively. (author)

  7. The radiochromic dye film dose meter as a possible test of particle track theory

    International Nuclear Information System (INIS)

    Hansen, J.W.; Jensen, M.; Katz, R.

    1980-09-01

    The response characteristic of the thin-film radiometric dye cyanide plastic dose meter to ionizing radiation of electrons and heavy charged particles is investigated as a possible test of the particle track theory worked out by Robert Katz and coworkers. Dose response curves for low-LET radiation have been investigated and are used for a quality estimation of the response for protons and oxygen ions at 16 and 4 MeV/amu, respectively. A bleaching effect on the colouration at high doses intimates that the target cannot be interpreted lieerally, but it might still be possinle to transfer the function of the macroscopic dose response to a theoretical dose response curve in a microscopic scale for a single ion. From this relation the macroscopic dose response curve can be determined qhen the film is irradiated with heavy ions. It will be shown theoretically that for protons there is no saturation in the track core, whereas calculations for oxygen ions show a heavy saturation in the track core, which means that a part of the ions loose their energy ineffectively. We can conclude that itis possible qualitatively to predict the dose response curve for high-LET particles by means of the dose response curve for low-LET radiation. (author)

  8. Transcriptional profiling of the dose response: a more powerful approach for characterizing drug activities.

    Directory of Open Access Journals (Sweden)

    Rui-Ru Ji

    2009-09-01

    Full Text Available The dose response curve is the gold standard for measuring the effect of a drug treatment, but is rarely used in genomic scale transcriptional profiling due to perceived obstacles of cost and analysis. One barrier to examining transcriptional dose responses is that existing methods for microarray data analysis can identify patterns, but provide no quantitative pharmacological information. We developed analytical methods that identify transcripts responsive to dose, calculate classical pharmacological parameters such as the EC50, and enable an in-depth analysis of coordinated dose-dependent treatment effects. The approach was applied to a transcriptional profiling study that evaluated four kinase inhibitors (imatinib, nilotinib, dasatinib and PD0325901 across a six-logarithm dose range, using 12 arrays per compound. The transcript responses proved a powerful means to characterize and compare the compounds: the distribution of EC50 values for the transcriptome was linked to specific targets, dose-dependent effects on cellular processes were identified using automated pathway analysis, and a connection was seen between EC50s in standard cellular assays and transcriptional EC50s. Our approach greatly enriches the information that can be obtained from standard transcriptional profiling technology. Moreover, these methods are automated, robust to non-optimized assays, and could be applied to other sources of quantitative data.

  9. A mathematical function for the description of nutrient-response curve.

    Directory of Open Access Journals (Sweden)

    Hamed Ahmadi

    Full Text Available Several mathematical equations have been proposed to modeling nutrient-response curve for animal and human justified on the goodness of fit and/or on the biological mechanism. In this paper, a functional form of a generalized quantitative model based on Rayleigh distribution principle for description of nutrient-response phenomena is derived. The three parameters governing the curve a has biological interpretation, b may be used to calculate reliable estimates of nutrient response relationships, and c provide the basis for deriving relationships between nutrient and physiological responses. The new function was successfully applied to fit the nutritional data obtained from 6 experiments including a wide range of nutrients and responses. An evaluation and comparison were also done based simulated data sets to check the suitability of new model and four-parameter logistic model for describing nutrient responses. This study indicates the usefulness and wide applicability of the new introduced, simple and flexible model when applied as a quantitative approach to characterizing nutrient-response curve. This new mathematical way to describe nutritional-response data, with some useful biological interpretations, has potential to be used as an alternative approach in modeling nutritional responses curve to estimate nutrient efficiency and requirements.

  10. A threshold in the dose-response relationship for X-ray induced somatic mutation frequency in drosophila melanogaster

    International Nuclear Information System (INIS)

    Koana, Takao; Sakai, Kazuo; Okada, M.O.

    2004-01-01

    The dose-response relationship of ionizing radiation and its stochastic effects has been thought to be linear without any thresholds for a long time. The basic data for this model was obtained from mutational assays using germ cells of male fruit fly Drosophila melanogaster. However, cancer-causing activity should be examined more appropriately in somatic cells than in germ cells. In this paper, we examined the dose-response relationship of X-ray irradiation and somatic mutation in drosophila, and found a threshold at approximately 1 Gy in the DNA repair proficient flies. In the repair deficient siblings, the threshold was smaller and the inclination of the dose-response curve was five times steeper. These results suggest that the dose-response relationship between X-ray irradiation and somatic mutation has a threshold, and that the DNA repair function contributes to its formation. (author)

  11. WE-D-BRE-06: Quantification of Dose-Response for High Grade Esophagtis Patients Using a Novel Voxel-To-Voxel Method

    International Nuclear Information System (INIS)

    Niedzielski, J; Martel, M; Tucker, S; Gomez, D; Court, L; Yang, J; Briere, T

    2014-01-01

    Purpose: Radiation induces an inflammatory response in the esophagus, discernible on CT studies. This work objectively quantifies the voxel esophageal radiation-response for patients with acute esophagitis. This knowledge is an important first-step towards predicting the effect of complex dose distributions on patient esophagitis symptoms. Methods: A previously validated voxel-based methodology of quantifying radiation esophagitis severity was used to identify the voxel dose-response for 18 NSCLC patients with severe esophagitis (CTCAE grading criteria, grade2 or higher). The response is quantified as percent voxel volume change for a given dose. During treatment (6–8 weeks), patients had weekly 4DCT studies and esophagitis scoring. Planning CT esophageal contours were deformed to each weekly CT using a demons DIR algorithm. An algorithm using the Jacobian Map from the DIR of the planning CT to all weekly CTs was used to quantify voxel-volume change, along with corresponding delivered voxel dose, to the planning voxel. Dose for each voxel for each time-point was calculated on each previous weekly CT image, and accumulated using DIR. Thus, for each voxel, the volume-change and delivered dose was calculated for each time-point. The data was binned according to when the volume-change first increased by a threshold volume (10%–100%, in 10% increments), and the average delivered dose calculated for each bin. Results: The average dose resulting in a voxel volume increase of 10–100% was 21.6 to 45.9Gy, respectively. The mean population dose to give a 50% volume increase was 36.3±4.4Gy, (range:29.8 to 43.5Gy). The average week of 50% response was 4.1 (range:4.9 to 2.8 weeks). All 18 patients showed similar dose to first response curves, showing a common trend in the initial inflammatoryresponse. Conclusion: We extracted the dose-response curve of the esophagus on a voxel-to-voxel level. This may be useful for estimating the esophagus response (and patient symptoms

  12. Negative impact of high cumulative glucocorticoid dose on bone metabolism of patients with myasthenia gravis.

    Science.gov (United States)

    Braz, Nayara Felicidade Tomaz; Rocha, Natalia Pessoa; Vieira, Érica Leandro Marciano; Gomez, Rodrigo Santiago; Barbosa, Izabela Guimarães; Malheiro, Olívio Brito; Kakehasi, Adriana Maria; Teixeira, Antonio Lucio

    2017-08-01

    This current study aimed to evaluate the frequency of low bone mass, osteopenia, and osteoporosis in patients with myasthenia gravis (MG) and to investigate the possible association between bone mineral density (BMD) and plasma levels of bone metabolism markers. Eighty patients with MG and 62 controls BMD were measured in the right femoral neck and lumbar spine by dual-energy X-ray absorptiometry. Plasma concentrations of osteocalcin, osteopontin, osteoprotegerin, tumor necrosis factor (TNF-α), interleukin (IL)-1β, IL-6, dickkopf (DKK-1), sclerostin, insulin, leptin, adrenocorticotropic hormone, parathyroid hormone, and fibroblast growth factor (FGF-23) were analyzed by Luminex®. The mean age of patients was 41.9 years, with 13.5 years of length of illness, and a mean cumulative dose of glucocorticoids 38,123 mg. Patients had significant reduction in BMD of the lumbar, the femoral neck, and in the whole body when compared with controls. Fourteen percent MG patients had osteoporosis at the lumbar spine and 2.5% at the femoral neck. In comparison with controls, patients with MG presented lower levels of osteocalcin, adrenocorticotropic hormone, parathyroid hormone, sclerostin, TNF-α, and DKK-1 and higher levels of FGF-23, leptin, and IL-6. There was a significant negative correlation between cumulative glucocorticoid dose and serum calcium, lumbar spine T-score, femoral neck BMD, T-score, and Z-score. After multivariate analysis, higher TNF-α levels increased the likelihood of presenting low bone mass by 2.62. MG patients under corticotherapy presented low BMD and altered levels of bone markers.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  14. Test-Anchored Vibration Response Predictions for an Acoustically Energized Curved Orthogrid Panel with Mounted Components

    Science.gov (United States)

    Frady, Gregory P.; Duvall, Lowery D.; Fulcher, Clay W. G.; Laverde, Bruce T.; Hunt, Ronald A.

    2011-01-01

    rich body of vibroacoustic test data was recently generated at Marshall Space Flight Center for component-loaded curved orthogrid panels typical of launch vehicle skin structures. The test data were used to anchor computational predictions of a variety of spatially distributed responses including acceleration, strain and component interface force. Transfer functions relating the responses to the input pressure field were generated from finite element based modal solutions and test-derived damping estimates. A diffuse acoustic field model was applied to correlate the measured input sound pressures across the energized panel. This application quantifies the ability to quickly and accurately predict a variety of responses to acoustically energized skin panels with mounted components. Favorable comparisons between the measured and predicted responses were established. The validated models were used to examine vibration response sensitivities to relevant modeling parameters such as pressure patch density, mesh density, weight of the mounted component and model form. Convergence metrics include spectral densities and cumulative root-mean squared (RMS) functions for acceleration, velocity, displacement, strain and interface force. Minimum frequencies for response convergence were established as well as recommendations for modeling techniques, particularly in the early stages of a component design when accurate structural vibration requirements are needed relatively quickly. The results were compared with long-established guidelines for modeling accuracy of component-loaded panels. A theoretical basis for the Response/Pressure Transfer Function (RPTF) approach provides insight into trends observed in the response predictions and confirmed in the test data. The software developed for the RPTF method allows easy replacement of the diffuse acoustic field with other pressure fields such as a turbulent boundary layer (TBL) model suitable for vehicle ascent. Structural responses

  15. Cumulative or delayed nephrotoxicity after cisplatin (DDP) treatment.

    Science.gov (United States)

    Pinnarò, P; Ruggeri, E M; Carlini, P; Giovannelli, M; Cognetti, F

    1986-04-30

    The present retrospective study reports data regarding renal toxicity in 115 patients (63 males, 52 females; median age, 56 years) who received cumulative doses of cisplatin (DDP) greater than or equal to 200 mg/m2. DDP was administered alone or in combination at a dose of 50-70 mg/m2 in 91 patients, and at a dose of 100 mg/m2 in 22 patients. Two patients after progression of ovarian carcinoma treated with conventional doses of DDP received 4 and 2 courses, respectively, of high-dose DDP (40 mg/m2 for 5 days) in hypertonic saline. The median number of DDP courses was 6 (range 2-14), and the median cumulative dose was 350 mg/m2 (range, 200-1200). Serum creatinine and urea nitrogen were determined before initiating the treatment and again 13-16 days after each administration. The incidence of azotemia (creatinina levels that exceeded 1.5 mg/dl) was similar before (7.8%) and after (6.1%) DDP doses of 200 mg/m2. Azotemia appears to be related to the association of DDP with other potentially nephrotoxic antineoplastic drugs (methotrexate) more than to the dose per course of DDP. Of 59 patients followed for 2 months or more after discontinuing the DDP treatment, 3 (5.1%) presented creatinine values higher than 1.5 mg/dl. The data deny that the incidence of nephrotoxicity is higher in patients receiving higher cumulative doses of DDP and confirm that increases in serum creatinine levels may occur some time after discontinuation of the drug.

  16. a new approach of Analysing GRB light curves

    International Nuclear Information System (INIS)

    Varga, B.; Horvath, I.

    2005-01-01

    We estimated the T xx quantiles of the cumulative GRB light curves using our recalculated background. The basic information of the light curves was extracted by multivariate statistical methods. The possible classes of the light curves are also briefly discussed

  17. Hierarchical Bayesian inference for ion channel screening dose-response data [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Ross H Johnstone

    2017-03-01

    Full Text Available Dose-response (or ‘concentration-effect’ relationships commonly occur in biological and pharmacological systems and are well characterised by Hill curves. These curves are described by an equation with two parameters: the inhibitory concentration 50% (IC50; and the Hill coefficient. Typically just the ‘best fit’ parameter values are reported in the literature. Here we introduce a Python-based software tool, PyHillFit , and describe the underlying Bayesian inference methods that it uses, to infer probability distributions for these parameters as well as the level of experimental observation noise. The tool also allows for hierarchical fitting, characterising the effect of inter-experiment variability. We demonstrate the use of the tool on a recently published dataset on multiple ion channel inhibition by multiple drug compounds. We compare the maximum likelihood, Bayesian and hierarchical Bayesian approaches. We then show how uncertainty in dose-response inputs can be characterised and propagated into a cardiac action potential simulation to give a probability distribution on model outputs.

  18. An assessment of cumulative external doses from Chernobyl fallout for a forested area in Russia using the optically stimulated luminescence from quartz inclusions in bricks

    DEFF Research Database (Denmark)

    Ramzaev, V.; Bøtter-Jensen, Lars; Thomsen, Kristina Jørkov

    2008-01-01

    . The area was significantly contaminated by Chernobyl fallout with initial (CS)-C-137 ground deposition level of similar to 1.1 MBq m(-2). The accumulated OSL doses in sections of the bricks varied from 141 to 207 mGy, of which between 76 and 146 mGy are attributable to Chernobyl fallout. Using the OSL...... depth-dose profiles obtained from the exposed bricks and the results from a gamma-ray-survey of the area, the Chernobyl-related cumulative gamma-ray dose for a point detector located in free air at a height of 1 m above the ground in the study area was estimated to be ca. 240 mGy for the time period...... starting on 27 April 1986 and ending on 31 July 2004. This result is in good agreement with the result of deterministic modelling of the cumulative gamma-ray dose in free air above undisturbed ground from the Chernobyl source in the Bryansk Region. Over the same time period, the external Chernobyl...

  19. Inverted U-Shaped Dose-Response Curve of the Anxiolytic Effect of Cannabidiol during Public Speaking in Real Life.

    Science.gov (United States)

    Zuardi, Antonio W; Rodrigues, Natália P; Silva, Angélica L; Bernardo, Sandra A; Hallak, Jaime E C; Guimarães, Francisco S; Crippa, José A S

    2017-01-01

    The purpose of this study was to investigate whether the anxiolytic effect of cannabidiol (CBD) in humans follows the same pattern of an inverted U-shaped dose-effect curve observed in many animal studies. Sixty healthy subjects of both sexes aged between 18 and 35 years were randomly assigned to five groups that received placebo, clonazepam (1 mg), and CBD (100, 300, and 900 mg). The subjects were underwent a test of public speaking in a real situation (TPSRS) where each subject had to speak in front of a group formed by the remaining participants. Each subject completed the anxiety and sedation factors of the Visual Analog Mood Scale and had their blood pressure and heart rate recorded. These measures were obtained in five experimental sessions with 12 volunteers each. Each session had four steps at the following times (minutes) after administration of the drug/placebo, as time 0: -5 (baseline), 80 (pre-test), 153 (speech), and 216 (post-speech). Repeated-measures analyses of variance showed that the TPSRS increased the subjective measures of anxiety, heart rate, and blood pressure. Student-Newman-Keuls test comparisons among the groups in each phase showed significant attenuation in anxiety scores relative to the placebo group in the group treated with clonazepam during the speech phase, and in the clonazepam and CBD 300 mg groups in the post-speech phase. Clonazepam was more sedative than CBD 300 and 900 mg and induced a smaller increase in systolic and diastolic blood pressure than CBD 300 mg. The results confirmed that the acute administration of CBD induced anxiolytic effects with a dose-dependent inverted U-shaped curve in healthy subjects, since the subjective anxiety measures were reduced with CBD 300 mg, but not with CBD 100 and 900 mg, in the post-speech phase.

  20. Inverted U-Shaped Dose-Response Curve of the Anxiolytic Effect of Cannabidiol during Public Speaking in Real Life

    Directory of Open Access Journals (Sweden)

    Antonio W. Zuardi

    2017-05-01

    Full Text Available The purpose of this study was to investigate whether the anxiolytic effect of cannabidiol (CBD in humans follows the same pattern of an inverted U-shaped dose-effect curve observed in many animal studies. Sixty healthy subjects of both sexes aged between 18 and 35 years were randomly assigned to five groups that received placebo, clonazepam (1 mg, and CBD (100, 300, and 900 mg. The subjects were underwent a test of public speaking in a real situation (TPSRS where each subject had to speak in front of a group formed by the remaining participants. Each subject completed the anxiety and sedation factors of the Visual Analog Mood Scale and had their blood pressure and heart rate recorded. These measures were obtained in five experimental sessions with 12 volunteers each. Each session had four steps at the following times (minutes after administration of the drug/placebo, as time 0: -5 (baseline, 80 (pre-test, 153 (speech, and 216 (post-speech. Repeated-measures analyses of variance showed that the TPSRS increased the subjective measures of anxiety, heart rate, and blood pressure. Student-Newman-Keuls test comparisons among the groups in each phase showed significant attenuation in anxiety scores relative to the placebo group in the group treated with clonazepam during the speech phase, and in the clonazepam and CBD 300 mg groups in the post-speech phase. Clonazepam was more sedative than CBD 300 and 900 mg and induced a smaller increase in systolic and diastolic blood pressure than CBD 300 mg. The results confirmed that the acute administration of CBD induced anxiolytic effects with a dose-dependent inverted U-shaped curve in healthy subjects, since the subjective anxiety measures were reduced with CBD 300 mg, but not with CBD 100 and 900 mg, in the post-speech phase.

  1. Comparison of dose response functions for EBT3 model GafChromic™ film dosimetry system.

    Science.gov (United States)

    Aldelaijan, Saad; Devic, Slobodan

    2018-05-01

    Different dose response functions of EBT3 model GafChromic™ film dosimetry system have been compared in terms of sensitivity as well as uncertainty vs. error analysis. We also made an assessment of the necessity of scanning film pieces before and after irradiation. Pieces of EBT3 film model were irradiated to different dose values in Solid Water (SW) phantom. Based on images scanned in both reflection and transmission mode before and after irradiation, twelve different response functions were calculated. For every response function, a reference radiochromic film dosimetry system was established by generating calibration curve and by performing the error vs. uncertainty analysis. Response functions using pixel values from the green channel demonstrated the highest sensitivity in both transmission and reflection mode. All functions were successfully fitted with rational functional form, and provided an overall one-sigma uncertainty of better than 2% for doses above 2 Gy. Use of pre-scanned images to calculate response functions resulted in negligible improvement in dose measurement accuracy. Although reflection scanning mode provides higher sensitivity and could lead to a more widespread use of radiochromic film dosimetry, it has fairly limited dose range and slightly increased uncertainty when compared to transmission scan based response functions. Double-scanning technique, either in transmission or reflection mode, shows negligible improvement in dose accuracy as well as a negligible increase in dose uncertainty. Normalized pixel value of the images scanned in transmission mode shows linear response in a dose range of up to 11 Gy. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  2. Dose and energy dependence of response of Gafchromic XR-QA film for kilovoltage x-ray beams.

    Science.gov (United States)

    Rampado, O; Garelli, E; Deagostini, S; Ropolo, R

    2006-06-07

    There is a growing interest in Gafchromic films for patient dosimetry in radiotherapy and in radiology. A new model (XR-QA) with high sensitivity to low dose was tested in this study. The response of the film to different x-ray beam energies (range 28-145 kVp with various filtrations, dose range 0-100 mGy) and to visible light was investigated, together with the after exposure darkening properties. Exposed films were digitized with a commercially available, optical flatbed scanner. A single functional form for dose versus net pixel value variation has been determined for all the obtained calibration curves, with a unique fit parameter different for each of the used x-ray beams. The film response was dependent on beam energy, with higher colour variations for the beams in the range 80-140 kVp. Different sources of uncertainties in dose measurements, governed by the digitalization process, the film response uniformity and the calibration curve fit procedure, have been considered. The overall one-sigma dose measurement uncertainty depended on the beam energy and decreased with increasing absorbed dose. For doses above 10 mGy and beam energies in the range 80-140 kVp the total uncertainty was less than 5%, whereas for the 28 kVp beam the total uncertainty at 10 mGy was about 10%. The post-exposure colour variation was not negligible in the first 24 h after the exposure, with a consequent increase in the calculated dose of about 10%. Results of the analysis of the sensitivity to visible light indicated that a short exposure of this film to ambient and scanner light during the measurements will not have a significant impact on the radiation dosimetry.

  3. Tritium β-radiation induction of chromosomal damage: a calibration curve for low dose, low dose rate exposures of human cells to tritiated water

    International Nuclear Information System (INIS)

    Morrison, D.P.; Gale, K.L.; Lucas, J.N.

    1997-01-01

    Radiation exposures from tritium contribute to the occupational radiation exposures associated with CANDU reactors. Tritiated water is of particular interest since it is readily taken up by human cells and its elimination from the body, and, consequently, the radiation exposure of the cells, is spread over a period of days. Occupational exposures to tritiated water result in what are effectively chronic β-radiation exposures. The doses and dose rates ordinarily used in the definition of cellular responses to radiation in vitro, for use in biological dosimetry (the assessment of radiation exposures based on the observed levels of changes in the cells of exposed individuals), are usually much higher than for most occupational exposures and involve radiations other than tritium β-rays. As a result, their use in assessing the effects from tritiated water exposures may not be appropriate. We describe here an in vitro calibration curve for chronic tritium β-radiation induction of reciprocal chromosomal translocations in humn peripheral blood lymphocytes (PBLs) for use in biodosimetry. (author)

  4. SU-E-T-488: An Iso-Dose Curve Based Interactive IMRT Optimization System for Physician-Driven Plan Tuning

    International Nuclear Information System (INIS)

    Shi, F; Tian, Z; Jia, X; Jiang, S; Zarepisheh, M; Cervino, L

    2014-01-01

    Purpose: In treatment plan optimization for Intensity Modulated Radiation Therapy (IMRT), after a plan is initially developed by a dosimetrist, the attending physician evaluates its quality and often would like to improve it. As opposed to having the dosimetrist implement the improvements, it is desirable to have the physician directly and efficiently modify the plan for a more streamlined and effective workflow. In this project, we developed an interactive optimization system for physicians to conveniently and efficiently fine-tune iso-dose curves. Methods: An interactive interface is developed under C++/Qt. The physician first examines iso-dose lines. S/he then picks an iso-dose curve to be improved and drags it to a more desired configuration using a computer mouse or touchpad. Once the mouse is released, a voxel-based optimization engine is launched. The weighting factors corresponding to voxels between the iso-dose lines before and after the dragging are modified. The underlying algorithm then takes these factors as input to re-optimize the plan in near real-time on a GPU platform, yielding a new plan best matching the physician's desire. The re-optimized DVHs and iso-dose curves are then updated for the next iteration of modifications. This process is repeated until a physician satisfactory plan is achieved. Results: We have tested this system for a series of IMRT plans. Results indicate that our system provides the physicians an intuitive and efficient tool to edit the iso-dose curves according to their preference. The input information is used to guide plan re-optimization, which is achieved in near real-time using our GPU-based optimization engine. Typically, a satisfactory plan can be developed by a physician in a few minutes using this tool. Conclusion: With our system, physicians are able to manipulate iso-dose curves according to their preferences. Preliminary results demonstrate the feasibility and effectiveness of this tool

  5. The response of mouse skin to multiple small doses of radiation

    International Nuclear Information System (INIS)

    Denekamp, J.; Harris, S.R.

    1975-01-01

    The response of mouse skin has been tested by irradiating the foot of albino mice and scoring erythema and desquamation during the following month. Multiple small doses of 150, 250 and 350 rad have been given 'daily', and the test dose necessary to achieve a given reaction has been determined one day after the last small fraction. This test dose has been compared with the single dose necessary to produce the same reaction level in previously untreated mice, in order to determine the ratio of the slopes of the dose-response curve at low and high doses: Slope ratio = (single dose - test dose)/total fractionated priming dose. In three separate experiments the slope ratio decreased as the dose per fraction was reduced from 350 to 150 rad. This conflicts with the data of Dutreix et al, who found a constant slope ratio over this dose range. The present data are compared with those obtained by Denekamp using 4, 9 and 14 fractions of 300 rad and by Douglas et al, using the same experimental technique, over the dose range 45 to 200 rad/fraction. In addition, the results from multifraction experiments in which equal dose increments were administered until the requisite skin reaction was achieved are also analysed in terms of their slope ratio (Fowler et al. Douglas et al). When all these results are plotted it is impossible to be sure whether the slope ratio is decreasing over the range 300 to 45 rad per fraction, although it seems likely. Most of the values at low doses lie in the range 0.15 to 0.25, indicating that at low doses the radiation is only 15 to 25% as effective per rad in causing cell death as at higher doses. (author)

  6. Preliminary evaluation of lung doses for dogs exposed to 239PuO2

    International Nuclear Information System (INIS)

    Fisher, D.R.; Cannon, W.C.; Hadley, R.T.; Park, J.F.

    1986-01-01

    A group of beagle dogs exposed to inhaled 239 PuO 2 is being followed for life-span effects. This paper reports preliminary lung dose estimates and dose-response relationships for incidence of lung tumors and radiation pneumonitis which have been observed to date. Doses were estimated by using both conventional dose-averaging and microdosimetric techniques. Cascade impactor sampling data were used to reconstruct the original plutonium aerosol size distributions unique to each of about 120 individual dogs exposed to 239 PuO 2 . Data providing the initial plutonium lung burden and lifetime lung retention-clearance functions of plutonium for each dog were used for calculating average dose rates, cumulative absorbed doses, and specific energy distributions. A linear dose-response relationship for lung tumor induction was estimated on the basis of cumulative lung dose. Average time to death was estimated as a function of average dose rate. Conclusions regarding the potential value of microdosimetry in the interpretation of such dose-response relationships are discussed. 8 refs., 5 figs., 1 tab

  7. A model for inverse dose-rate effects - low dose-rate hyper-sensibility in response to targeted radionuclide therapy

    International Nuclear Information System (INIS)

    Murray, I.; Mather, S.J.

    2015-01-01

    Full text of publication follows. The aim of this work was to test the hypothesis that the Linear-Quadratic (LQ) model of cell survival, developed for external beam radiotherapy (EBRT), could be extended to targeted radionuclide therapy (TRT) in order to predict dose-response relationships in a cell line exhibiting low dose hypersensitivity (LDH). Methods: aliquots of the PC-3 cancer cell line were treated with either EBRT or an in-vitro model of TRT (Irradiation of cell culture with Y-90 EDTA over 24, 48, 72 or 96 hours). Dosimetry for the TRT was calculated using radiation transport simulations with the Monte Carlo PENELOPE code. Clonogenic as well as functional biological assays were used to assess cell response. An extension of the LQ model was developed which incorporated a dose-rate threshold for activation of repair mechanisms. Results: accurate dosimetry for in-vitro exposures of cell cultures to radioactivity was established. LQ parameters of cell survival were established for the PC-3 cell line in response to EBRT. The standard LQ model did not predict survival in PC-3 cells exposed to Y 90 irradiation over periods of up to 96 hours. In fact cells were more sensitive to the same dose when irradiation was carried out over 96 hours than 24 hours. I.e. at a lower dose-rate. Deviations from the LQ predictions were most pronounced below a threshold dose-rate of 0.5 Gy/hr. These results led to an extension of the LQ model based upon a dose-rate dependent sigmoid model of single strand DNA repair. This extension to the model resulted in predicted cell survival curves that closely matched the experimental data. Conclusion: the LQ model of cell survival to radiation has been shown to be largely predictive of response to low dose-rate irradiation. However, in cells displaying LDH, further adaptation of the model was required. (authors)

  8. Study of the response reduction of LiF:Mg, Ti dosimeter for high dose dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Torkzadeh, Falamarz [Nuclear Sciences and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Applications Research School; AEOI, Tehran (Iran, Islamic Republic of); Faripour, Heidar [Nuclear Sciences and Technology Research Institute, Tehran (Iran, Islamic Republic of). Laser and Optics Research School; AEOI, Tehran (Iran, Islamic Republic of); Mardashti, Forough; Manouchehri, Farhad [Nuclear Sciences and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Applications Research School

    2017-07-15

    A single crystal and 5 polycrystalline samples of LiF:Mg, Ti and their pellets were prepared and investigated so as to apply thermoluminescence high gamma dose dosimetry. Three zones of single crystal with dopant concentrations of 200 ppm of Mg and 20 ppm of Ti were also used to prepare the single crystal samples. For polycrystalline samples, dopant concentrations of 0.062 mol% Mg and Ti concentrations in the range of 0.016 and 0.046 mol% were used. All the samples were exposed to gamma doses of 1 kGy to 700 kGy and their response changes were determined by a gamma dose test of about 60 mGy. According to the results obtained, the use of response reduction by curve-fitting up to about 300 kGy can be performed reliably for high dose gamma dosimetry.

  9. Radiation absorbed dose estimates for [1-carbon-11]-glucose in adults: The effects of hyperinsulinemia

    International Nuclear Information System (INIS)

    Powers, W.J.

    1996-01-01

    As preparation for studies of blood-brain glucose transport in diabetes mellitus, radiation absorbed dose estimates from intravenous administration of [1- 11 C]-glucose for 24 internal organs, lens, blood and total body were calculated for three physiologic conditions: euinsulinemic euglycemia, hyperinsulinemic euglycemia and hyperinsulinemic hyperglycemia. Cumulated activities in blood, insulin-independent and insulin-dependent compartments were calculated from blood time-activity curves in normal human volunteers and macaques. Apportionment of cumulated activity to individual organs in insulin-dependent and insulin-independent compartments was based on previously published data. Absorbed doses were calculated with the computer program MIRDOSE 3 for the 70-kg adult phantom. S for blood was calculated separately. The heart wall, lungs and spleen were the organs receiving the highest dose. The effect of hyperinsulinemia was demonstrated by the increase in adsorbed dose to the muscle, heart and blood with a decrease to other internal organs. This effect was more pronounced during hyperinsulinemic hyperglycemia. Hyperinsulinemia produced a decrease in effective dose due to the decrease in cumulated activity in organs with specified weighting factors greater than 0.05. The effective dose per study for [1- 11 C]-glucose is comparable to that reported for 2-deoxy-[2- 18 F]-glucose. 43 refs., 1 fig., 4 tabs

  10. Salvage Radiation Therapy Dose Response for Biochemical Failure of Prostate Cancer After Prostatectomy—A Multi-Institutional Observational Study

    Energy Technology Data Exchange (ETDEWEB)

    Pisansky, Thomas M., E-mail: pisansky.thomas@mayo.edu [Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (United States); Agrawal, Shree [Case Western Reserve University School of Medicine, Cleveland, Ohio (United States); Hamstra, Daniel A. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Koontz, Bridget F. [Department of Radiation Oncology, Duke Cancer Institute, Durham, North Carolina (United States); Liauw, Stanley L. [Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois (United States); Efstathiou, Jason A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Michalski, Jeff M. [Department of Radiation Oncology, Washington University, St. Louis, Missouri (United States); Feng, Felix Y. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Abramowitz, Matthew C.; Pollack, Alan [Department of Radiation Oncology, University of Miami, Miami, Florida (United States); Anscher, Mitchell S. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Moghanaki, Drew [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Hunter Holmes McGuire Veterans Administration Medical Center, Richmond, Virginia (United States); Den, Robert B. [Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania (United States); Stephans, Kevin L. [Department of Radiation Oncology, Cleveland Clinic, Cleveland, Ohio (United States); Zietman, Anthony L. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Lee, W. Robert [Department of Radiation Oncology, Duke Cancer Institute, Durham, North Carolina (United States); Kattan, Michael W. [Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio (United States); and others

    2016-12-01

    Purpose: To determine whether a dose-response relationship exists for salvage radiation therapy (RT) of biochemical failure after prostatectomy for prostate cancer. Methods and Materials: Individual data from 1108 patients who underwent salvage RT at 10 academic centers were pooled. The cohort was enriched for selection criteria more likely associated with tumor recurrence in the prostate bed (margin positive and pre-RT prostate-specific antigen [PSA] level of ≤2.0 ng/mL) and without the confounding of planned androgen suppression. The cumulative incidence of biochemical failure and distant metastasis over time was computed, and competing risks hazard regression models were used to investigate the association between potential predictors and these outcomes. The association of radiation dose with outcomes was the primary focus. Results: With a 65.2-month follow-up duration, the 5- and 10-year estimates of freedom from post-RT biochemical failure (PSA level >0.2 ng/mL and rising) was 63.5% and 49.8%, respectively, and the cumulative incidence of distant metastasis was 12.4% by 10 years. A Gleason score of ≥7, higher pre-RT PSA level, extraprostatic tumor extension, and seminal vesicle invasion were associated with worse biochemical failure and distant metastasis outcomes. A salvage radiation dose of ≥66.0 Gy was associated with a reduced cumulative incidence of biochemical failure, but not of distant metastasis. Conclusions: The use of salvage radiation doses of ≥66.0 Gy are supported by evidence presented in the present multicenter pooled analysis of individual patient data. The observational reporting method, limited sample size, few distant metastasis events, modest follow-up duration, and elective use of salvage therapy might have diminished the opportunity to identify an association between the radiation dose and this endpoint.

  11. Salvage Radiation Therapy Dose Response for Biochemical Failure of Prostate Cancer After Prostatectomy—A Multi-Institutional Observational Study

    International Nuclear Information System (INIS)

    Pisansky, Thomas M.; Agrawal, Shree; Hamstra, Daniel A.; Koontz, Bridget F.; Liauw, Stanley L.; Efstathiou, Jason A.; Michalski, Jeff M.; Feng, Felix Y.; Abramowitz, Matthew C.; Pollack, Alan; Anscher, Mitchell S.; Moghanaki, Drew; Den, Robert B.; Stephans, Kevin L.; Zietman, Anthony L.; Lee, W. Robert; Kattan, Michael W.

    2016-01-01

    Purpose: To determine whether a dose-response relationship exists for salvage radiation therapy (RT) of biochemical failure after prostatectomy for prostate cancer. Methods and Materials: Individual data from 1108 patients who underwent salvage RT at 10 academic centers were pooled. The cohort was enriched for selection criteria more likely associated with tumor recurrence in the prostate bed (margin positive and pre-RT prostate-specific antigen [PSA] level of ≤2.0 ng/mL) and without the confounding of planned androgen suppression. The cumulative incidence of biochemical failure and distant metastasis over time was computed, and competing risks hazard regression models were used to investigate the association between potential predictors and these outcomes. The association of radiation dose with outcomes was the primary focus. Results: With a 65.2-month follow-up duration, the 5- and 10-year estimates of freedom from post-RT biochemical failure (PSA level >0.2 ng/mL and rising) was 63.5% and 49.8%, respectively, and the cumulative incidence of distant metastasis was 12.4% by 10 years. A Gleason score of ≥7, higher pre-RT PSA level, extraprostatic tumor extension, and seminal vesicle invasion were associated with worse biochemical failure and distant metastasis outcomes. A salvage radiation dose of ≥66.0 Gy was associated with a reduced cumulative incidence of biochemical failure, but not of distant metastasis. Conclusions: The use of salvage radiation doses of ≥66.0 Gy are supported by evidence presented in the present multicenter pooled analysis of individual patient data. The observational reporting method, limited sample size, few distant metastasis events, modest follow-up duration, and elective use of salvage therapy might have diminished the opportunity to identify an association between the radiation dose and this endpoint.

  12. Pediatric patient doses in interventional cardiology procedures; Doses em paciente pediatrico em procedimentos de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, R.B.; Murata, C.H.; Moreira, A.C., E-mail: rbitelli2012@gmail.com, E-mail: camila.murata@gmail.com, E-mail: antonio.xray@gmail.com [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil). Escola Pulista de Medicina; Khoury, H.J.; Borras, C., E-mail: hjkhoury@gmail.com, E-mail: cariborras@starpower.net [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Engenharia Nuclear; Silva, M.S.R da, E-mail: msrochas2003@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil)

    2014-07-01

    The radiation doses from interventional procedures is relevant when treating children because of their greater radiosensitivity compared with adults. The purposes of this paper were to estimate the dose received by 18 pediatric patients who underwent cardiac interventional procedures and to correlate the maximum entrance surface air kerma (Ke,max), estimated with radiochromic films, with the cumulative air kerma values displayed at the end of procedures. This study was performed in children up to 6 years. The study was performed in two hospitals, one located in Recife and the other one in São Paulo. The x-ray imaging systems used were Phillips Allura 12 model with image intensifier system and a Phillips Allura FD10 flat panel system. To estimate the Ke,max on the patient’s skin radiochromic films(Gafchromic XR-RV2) were used. These values were estimated from the maximum optical density measured on film using a calibration curve. The results showed cumulative air kerma values ranging from 78.3- 500.0mGy, with a mean value of 242,3 mGy. The resulting Ke,max values ranged from 20.0-461.8 mGy, with a mean value of 208,8 mGy. The Ke,max values were correlated with the displayed cumulative air kerma values. The correlation factor R² was 0.78, meaning that the value displayed in the equipment’s console can be useful for monitoring the skin absorbed dose throughout the procedure. The routine fluoroscopy time records is not able by itself alert the physician about the risk of dose exceeding the threshold of adverse reactions, which can vary from an early erythema to serious harmful skin damage. (author)

  13. Bayesian nonparametric estimation of continuous monotone functions with applications to dose-response analysis.

    Science.gov (United States)

    Bornkamp, Björn; Ickstadt, Katja

    2009-03-01

    In this article, we consider monotone nonparametric regression in a Bayesian framework. The monotone function is modeled as a mixture of shifted and scaled parametric probability distribution functions, and a general random probability measure is assumed as the prior for the mixing distribution. We investigate the choice of the underlying parametric distribution function and find that the two-sided power distribution function is well suited both from a computational and mathematical point of view. The model is motivated by traditional nonlinear models for dose-response analysis, and provides possibilities to elicitate informative prior distributions on different aspects of the curve. The method is compared with other recent approaches to monotone nonparametric regression in a simulation study and is illustrated on a data set from dose-response analysis.

  14. Exercise, oxidants, and antioxidants change the shape of the bell-shaped hormesis curve

    Directory of Open Access Journals (Sweden)

    Zsolt Radak

    2017-08-01

    Full Text Available It is debated whether exercise-induced ROS production is obligatory to cause adaptive response. It is also claimed that antioxidant treatment could eliminate the adaptive response, which appears to be systemic and reportedly reduces the incidence of a wide range of diseases. Here we suggest that if the antioxidant treatment occurs before the physiological function-ROS dose-response curve reaches peak level, the antioxidants can attenuate function. On the other hand, if the antioxidant treatment takes place after the summit of the bell-shaped dose response curve, antioxidant treatment would have beneficial effects on function. We suggest that the effects of antioxidant treatment are dependent on the intensity of exercise, since the adaptive response, which is multi pathway dependent, is strongly influenced by exercise intensity. It is further suggested that levels of ROS concentration are associated with peak physiological function and can be extended by physical fitness level and this could be the basis for exercise pre-conditioning. Physical inactivity, aging or pathological disorders increase the sensitivity to oxidative stress by altering the bell-shaped dose response curve.

  15. Biological dose estimation and comet analysis of the victims in a high dose 60Co radiation accident

    International Nuclear Information System (INIS)

    Chen Ying; Liu Xiulin; Luo Yisheng; Li You; Yao Bo

    2007-01-01

    Objective: To explore the methods of chromosome preparation in human peripheral blood and bone marrow after very high dose exposure and fit the dose-response curve of dicentrics and tings in the range of high doses over 6 Gy for estimating biological dose and detecting DNA damage in the victims of '10.21' accident. Methods: The samples of peripheral blood and bone marrow in 2 victims were collected to prepare chromosome mataphases and dicentrics (multicentrics) + rings were counted. The dose-response curve and equation of human blood irradiated between 6-22 Gy in vitro were established and applied to assess biological dose of 2 victims. In addition, their DNA damages were tested by alkaline single cell gel electrophoresis. Results: The dicentric + ring numbers of 4.47 per cell in victims B's peripheral blood lymphocytes and 9.15 per cell in victim A's bone marrow who had no mitosis in peripheral blood cell. The whole body average doses of victims B and A estimated by 6-22 Gy equation arrived at 9.4 Gy and 19.5 Gy, respectively. The serious DNA damages were expressed by small head and large tail comet figures. Conclusions: The biological doses of 2 victims estimated by 6-22 Gy dose-response curve have reached the levels of extreme grave bone marrow and intestinal ARS, respectively. (authors)

  16. Chromosome aberrations induced by low doses of X-rays in human lymphocytes in vitro

    International Nuclear Information System (INIS)

    Ziemba-Zoltowska, B.; Bocian, E.; Rosiek, O.; Sablinski, J.

    1980-01-01

    Curves derived from the dose-response data for the yield of aberrations in human lymphocytes can be represented by a quadratic equation at all but low dose ranges. A calibration curve has therefore been determined at a low dose range of X-radiation (11.5 to 57.5 rad). The frequencies of dicentrics plus centric rings, and of acentrics were better fitted by linear dose-response models than quadratic. The linearity of the relationship indicated that asymmetrical chromosome exchanges at low doses of radiation are produced predominantly by a single track mechanism. A dose-response curve for dicentrics plus centric rings (5 to 60 rad) has also been derived by pooling published data with the results of this study. This calibration curve is relevant to cytogenetic dosimetry in radiological protection. (UK)

  17. Computational tools for the construction of calibration curves for use in dose calculations in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Oliveira, Alex C.H.; Vieira, Jose W.; Escola Politecnica de Pernambuco , Recife, PE

    2011-01-01

    The realization of tissue inhomogeneity corrections in image-based treatment planning improves the accuracy of radiation dose calculations for patients undergoing external-beam radiotherapy. Before the tissue inhomogeneity correction can be applied, the relationship between the computed tomography (CT) numbers and density must be established. This relationship is typically established by a calibration curve empirically obtained from CT images of a phantom that has several inserts of tissue-equivalent materials, covering a wide range of densities. This calibration curve is scanner-dependent and allows the conversion of CT numbers in densities for use in dose calculations. This paper describes the implementation of computational tools necessary to construct calibration curves. These tools are used for reading and displaying of CT images in DICOM format, determination of the mean CT numbers (and their standard deviations) of each tissue-equivalent material and construction of calibration curves by fits with bilinear equations. All these tools have been implemented in the Microsoft Visual Studio 2010 in C≠ programming language. (author)

  18. Notes on the effect of dose uncertainty

    International Nuclear Information System (INIS)

    Morris, M.D.

    1987-01-01

    The apparent dose-response relationship between amount of exposure to acute radiation and level of mortality in humans is affected by uncertainties in the dose values. It is apparent that one of the greatest concerns regarding the human data from Hiroshima and Nagasaki is the unexpectedly shallow slope of the dose response curve. This may be partially explained by uncertainty in the dose estimates. Some potential effects of dose uncertainty on the apparent dose-response relationship are demonstrated

  19. Dose and energy dependence of response of Gafchromic (registered) XR-QA film for kilovoltage x-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Rampado, O; Garelli, E; Deagostini, S; Ropolo, R [Struttura Complessa fisica Sanitaria, Azienda Ospedaliera San Giovanni Battista, Corso Bramante 88, 10126 Turin (Italy)

    2006-06-07

    There is a growing interest in Gafchromic (registered) films for patient dosimetry in radiotherapy and in radiology. A new model (XR-QA) with high sensitivity to low dose was tested in this study. The response of the film to different x-ray beam energies (range 28-145 kVp with various filtrations, dose range 0-100 mGy) and to visible light was investigated, together with the after exposure darkening properties. Exposed films were digitized with a commercially available, optical flatbed scanner. A single functional form for dose versus net pixel value variation has been determined for all the obtained calibration curves, with a unique fit parameter different for each of the used x-ray beams. The film response was dependent on beam energy, with higher colour variations for the beams in the range 80-140 kVp. Different sources of uncertainties in dose measurements, governed by the digitalization process, the film response uniformity and the calibration curve fit procedure, have been considered. The overall one-sigma dose measurement uncertainty depended on the beam energy and decreased with increasing absorbed dose. For doses above 10 mGy and beam energies in the range 80-140 kVp the total uncertainty was less than 5%, whereas for the 28 kVp beam the total uncertainty at 10 mGy was about 10%. The post-exposure colour variation was not negligible in the first 24 h after the exposure, with a consequent increase in the calculated dose of about 10%. Results of the analysis of the sensitivity to visible light indicated that a short exposure of this film to ambient and scanner light during the measurements will not have a significant impact on the radiation dosimetry.

  20. Cumulative Lung Dose for Several Motion Management Strategies as a Function of Pretreatment Patient Parameters

    International Nuclear Information System (INIS)

    Hugo, Geoffrey D.; Campbell, Jonathon; Zhang Tiezhi; Yan Di

    2009-01-01

    Purpose: To evaluate patient parameters that may predict for relative differences in cumulative four-dimensional (4D) lung dose among several motion management strategies. Methods and Materials: Deformable image registration and dose accumulation were used to generate 4D treatment plans for 18 patients with 4D computed tomography scans. Three plans were generated to simulate breath hold at normal inspiration, target tracking with the beam aperture, and mid-ventilation aperture (control of the target at the mean daily position and application of an iteratively computed margin to compensate for respiration). The relative reduction in mean lung dose (MLD) between breath hold and mid-ventilation aperture (ΔMLD BH ) and between target tracking and mid-ventilation aperture (ΔMLD TT ) was calculated. Associations between these two variables and parameters of the lesion (excursion, size, location, and deformation) and dose distribution (local dose gradient near the target) were also calculated. Results: The largest absolute and percentage differences in MLD were 1.0 Gy and 21.5% between breath hold and mid-ventilation aperture. ΔMLD BH was significantly associated (p TT was significantly associated with excursion, deformation, and local dose gradient. A linear model was constructed to represent ΔMLD vs. excursion. For each 5 mm of excursion, target tracking reduced the MLD by 4% compared with the results of a mid-ventilation aperture plan. For breath hold, the reduction was 5% per 5 mm of excursion. Conclusions: The relative difference in MLD among different motion management strategies varied with patient and tumor characteristics for a given dosimetric target coverage. Tumor excursion is useful to aid in stratifying patients according to appropriate motion management strategies.

  1. Cumulative keyboard strokes: a possible risk factor for carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Eleftheriou Andreas

    2012-08-01

    Full Text Available Abstract Background Contradictory reports have been published regarding the association of Carpal Tunnel Syndrome (CTS and the use of computer keyboard. Previous studies did not take into account the cumulative exposure to keyboard strokes among computer workers. The aim of the present study was to investigate the association between cumulative keyboard use (keyboard strokes and CTS. Methods Employees (461 from a Governmental data entry & processing unit agreed to participate (response rate: 84.1 % in a cross-sectional study. Α questionnaire was distributed to the participants to obtain information on socio-demographics and risk factors for CTS. The participants were examined for signs and symptoms related to CTS and were asked if they had previous history or surgery for CTS. The cumulative amount of the keyboard strokes per worker per year was calculated by the use of payroll’s registry. Two case definitions for CTS were used. The first included subjects with personal history/surgery for CTS while the second included subjects that belonged to the first case definition plus those participants were identified through clinical examination. Results Multivariate analysis used for both case definitions, indicated that those employees with high cumulative exposure to keyboard strokes were at increased risk of CTS (case definition A: OR = 2.23;95 % CI = 1.09-4.52 and case definition B: OR = 2.41; 95%CI = 1.36-4.25. A dose response pattern between cumulative exposure to keyboard strokes and CTS has been revealed (p  Conclusions The present study indicated a possible association between cumulative exposure to keyboard strokes and development of CTS. Cumulative exposure to key-board strokes would be taken into account as an exposure indicator regarding exposure assessment of computer workers. Further research is needed in order to test the results of the current study and assess causality between cumulative keyboard strokes and

  2. Effects of mistuning and matrix structure on the topology of frequency response curves

    Science.gov (United States)

    Afolabi, Dare

    1989-01-01

    The stability of a frequency response curve under mild perturbations of the system's matrix is investigated. Using recent developments in the theory of singularities of differentiable maps, it is shown that the stability of a response curve depends on the structure of the system's matrix. In particular, the frequency response curves of a cylic system are shown to be unstable. Consequently, slight parameter variations engendered by mistuning will induce a significant difference in the topology of the forced response curves, if the mistuning transformation crosses the bifurcation set.

  3. A Threshold Exists in the Dose-response Relationship for Somatic Mutation Frequency Inducted by X-ray Irradiation of Drosophia

    International Nuclear Information System (INIS)

    Koana, T.; Takashima, Y.; Okada, M. O.; Ikehata, M.; Miyakoshi, J.; Sakai, K.

    2004-01-01

    The dose-response relationship of ionizing radiation and its stochastic effects has been thought to be linear without any thresholds. The basic data for this model was obtained from mutational assays in the male germ cells of fruits fly Drosophila melanogaster. However, carcinogenic activity should be examined more appropriately in somatic cells than in germ cells. Here, the dose-response relationship of X- ray irradiation and somatic mutation is examined in Drosophila. A threshold at approximately 1Gy was observed in the DNA repair proficient flies. In the repair deficient siblings, the threshold was smaller and the inclination of the dose-response curve was much steeper. These results suggest that the dose-response relationship between X-ray irradiation and somatic mutation has a threshold, and that the DNA repair function contributes to its formation. (Author) 35 refs

  4. Implications of effects ''adaptive response'', ''low-dose hypersensitivity'' und ''bystander effect'' for cancer risk at low doses and low dose rates

    International Nuclear Information System (INIS)

    Jacob, P

    2006-01-01

    A model for carcinogenesis (the TSCE model) was applied in order to examine the effects of ''Low-dose hypersensitivity (LDH)'' and the ''Bystander effect (BE)'' on the derivation of radiation related cancer mortality risks. LDH has been discovered to occur in the inactivation of cells after acute exposure to low LET radiation. A corresponding version of the TSCE model was applied to the mortality data on the Abomb survivors from Hiroshima and Nagasaki. The BE has been mainly observed in cells after exposure to high LET radiation. A Version of the TSCE model which included the BE was applied to the data on lung cancer mortality from the workers at the Mayak nuclear facilities who were exposed to Plutonium. In general an equally good description of the A-bomb survivor mortality data (for all solid, stomach and lung tumours) was found for the TSCE model and the (conventional) empirical models but fewer parameters were necessary for the TSCE model. The TSCE model which included the effects of radiation induced cell killing resulted in non-linear dose response curves with excess relative risks after exposure at young ages that were generally lower than in the models without cell killing. The main results from TSCE models which included cell killing described by either conventional survival curves or LDH were very similar. A sub multiplicative effect from the interaction of smoking and exposure to plutonium was found to result from the analysis of the Mayak lung cancer mortality data. All models examined resulted in the predominant number of Mayak lung cancer deaths being ascribed to smoking. The interaction between smoking and plutonium exposures was found to be the second largest effect. The TSCE model resulted in lower estimates for the lung cancer excess relative risk per unit plutonium dose than the empirical risk model, but this difference was not found to be statistically significant. The excess relative risk dose responses were linear in the empirical model and

  5. Study of cumulative fatigue damage detection for used parts with nonlinear output frequency response functions based on NARMAX modelling

    Science.gov (United States)

    Huang, Honglan; Mao, Hanying; Mao, Hanling; Zheng, Weixue; Huang, Zhenfeng; Li, Xinxin; Wang, Xianghong

    2017-12-01

    Cumulative fatigue damage detection for used parts plays a key role in the process of remanufacturing engineering and is related to the service safety of the remanufactured parts. In light of the nonlinear properties of used parts caused by cumulative fatigue damage, the based nonlinear output frequency response functions detection approach offers a breakthrough to solve this key problem. First, a modified PSO-adaptive lasso algorithm is introduced to improve the accuracy of the NARMAX model under impulse hammer excitation, and then, an effective new algorithm is derived to estimate the nonlinear output frequency response functions under rectangular pulse excitation, and a based nonlinear output frequency response functions index is introduced to detect the cumulative fatigue damage in used parts. Then, a novel damage detection approach that integrates the NARMAX model and the rectangular pulse is proposed for nonlinear output frequency response functions identification and cumulative fatigue damage detection of used parts. Finally, experimental studies of fatigued plate specimens and used connecting rod parts are conducted to verify the validity of the novel approach. The obtained results reveal that the new approach can detect cumulative fatigue damages of used parts effectively and efficiently and that the various values of the based nonlinear output frequency response functions index can be used to detect the different fatigue damages or working time. Since the proposed new approach can extract nonlinear properties of systems by only a single excitation of the inspected system, it shows great promise for use in remanufacturing engineering applications.

  6. Uncertainty analysis technique of dynamic response and cumulative damage properties of piping system

    International Nuclear Information System (INIS)

    Suzuki, Kohei; Aoki, Shigeru; Hara, Fumio; Hanaoka, Masaaki; Yamashita, Tadashi.

    1982-01-01

    It is a technologically important subject to establish the method of uncertainty analysis statistically examining the variation of the earthquake response and damage properties of equipment and piping system due to the change of input load and the parameters of structural system, for evaluating the aseismatic capability and dynamic structural reliability of these systems. The uncertainty in the response and damage properties when equipment and piping system are subjected to excessive vibration load is mainly dependent on the irregularity of acting input load such as the unsteady vibration of earthquakes, and structural uncertainty in forms and dimensions. This study is the basic one to establish the method for evaluating the uncertainty in the cumulative damage property at the time of resonant vibration of piping system due to the disperse of structural parameters with a simple model. First, the piping models with simple form were broken by resonant vibration, and the uncertainty in the cumulative damage property was evaluated. Next, the response analysis using an elasto-plastic mechanics model was performed by numerical simulation. Finally, the method of uncertainty analysis for response and damage properties by the perturbation method utilizing equivalent linearization was proposed, and its propriety was proved. (Kako, I.)

  7. Radiobiological responses for two cell lines following continuous low dose-rate (CLDR) and pulsed dose rate (PDR) brachytherapy

    International Nuclear Information System (INIS)

    Hanisch, Per Henrik; Furre, Torbjoern; Olsen, Dag Rune; Pettersen, Erik O.

    2007-01-01

    The iso-effective irradiation of continuous low-dose-rate (CLDR) irradiation was compared with that of various schedules of pulsed dose rate (PDR) irradiation for cells of two established human lines, T-47D and NHIK 3025. Complete single-dose response curves were obtained for determination of parameters α and β by fitting of the linear quadratic formula. Sublethal damage repair constants μ and T 1/2 were determined by split-dose recovery experiments. On basis of the acquired parameters of each cell type the relative effectiveness of the two regimens of irradiation (CLDR and PDR) was calculated by use of Fowler's radiobiological model for iso-effect irradiation for repeated fractions of dose delivered at medium dose rates. For both cell types the predicted and observed relative effectiveness was compared at low and high iso-effect levels. The results indicate that the effect of PDR irradiation predicted by Fowler's model is equal to that of CLDR irradiation for both small and large doses with T-47D cells. With NHIK 3025 cells PDR irradiation induces a larger effect than predicted by the model for small doses, while it induces the predicted effect for high doses. The underlying cause of this difference is unclear, but cell-cycle parameters, like G2-accumulation is tested and found to be the same for the two cell lines

  8. Patch test dose-response study: polysensitized individuals do not express lower elicitation thresholds than single/double-sensitized individuals

    DEFF Research Database (Denmark)

    Carlsen, B C; Fischer, Louise Arup; Sosted, H

    2009-01-01

    with nickel sulphate, methyldibromo glutaronitrile (MDBGN) and p-phenylenediamine (PPD) in dilution series. The ratio between the doses eliciting a response in 50% of patients in the two groups was used as the measure for relative sensitivity. RESULTS: The dose-response curves of the polysensitized group...... for MDBGN and PPD were shifted to the right, and for nickel sulphate shifted to the left, compared with the single/double-sensitized group. The relative sensitivity for each of the three allergens and a combined relative sensitivity for all three allergens were not significantly different when comparing...

  9. COMPARING BEHAVIORAL DOSE-EFFECT CURVES FOR HUMANS AND LABORATORY ANIMALS ACUTELY EXPOSED TO TOLUENE.

    Science.gov (United States)

    The utility of laboratory animal data in toxicology depends upon the ability to generalize the results quantitatively to humans. To compare the acute behavioral effects of inhaled toluene in humans to those in animals, dose-effect curves were fitted by meta-analysis of published...

  10. Health effects of low doses at low dose rates: dose-response relationship modeling in a cohort of workers of the nuclear industry

    International Nuclear Information System (INIS)

    Metz-Flamant, Camille

    2011-01-01

    The aim of this thesis is to contribute to a better understanding of the health effects of chronic external low doses of ionising radiation. This work is based on the French cohort of CEA-AREVA NC nuclear workers. The mains stages of this thesis were (1) conducting a review of epidemiological studies on nuclear workers, (2) completing the database and performing a descriptive analysis of the cohort, (3) quantifying risk by different statistical methods and (4) modelling the exposure-time-risk relationship. The cohort includes monitored workers employed more than one year between 1950 and 1994 at CEA or AREVA NC companies. Individual annual external exposure, history of work, vital status and causes of death were reconstructed for each worker. Standardized mortality ratios using French national mortality rates as external reference were computed. Exposure-risk analysis was conducted in the cohort using the linear excess relative risk model, based on both Poisson regression and Cox model. Time dependent modifying factors were investigated by adding an interaction term in the model or by using exposure time windows. The cohort includes 36, 769 workers, followed-up until age 60 in average. During the 1968- 2004 period, 5, 443 deaths, 2, 213 cancers, 62 leukemia and 1, 314 cardiovascular diseases were recorded. Among the 57% exposed workers, the mean cumulative dose was 21.5 milli-sieverts (mSv). A strong Healthy Worker Effect is observed in the cohort. Significant elevated risks of pleura cancer and melanoma deaths were observed in the cohort but not associated with dose. No significant association was observed with solid cancers, lung cancer and cardiovascular diseases. A significant dose-response relationship was observed for leukemia excluding chronic lymphatic leukemia, mainly for doses received less than 15 years before and for yearly dose rates higher than 10 mSv. This PhD work contributes to the evaluation of risks associated to chronic external radiation

  11. Pediatric patient doses in interventional cardiology procedures

    International Nuclear Information System (INIS)

    Medeiros, R.B.; Murata, C.H.; Moreira, A.C.

    2014-01-01

    The radiation doses from interventional procedures is relevant when treating children because of their greater radiosensitivity compared with adults. The purposes of this paper were to estimate the dose received by 18 pediatric patients who underwent cardiac interventional procedures and to correlate the maximum entrance surface air kerma (Ke,max), estimated with radiochromic films, with the cumulative air kerma values displayed at the end of procedures. This study was performed in children up to 6 years. The study was performed in two hospitals, one located in Recife and the other one in São Paulo. The x-ray imaging systems used were Phillips Allura 12 model with image intensifier system and a Phillips Allura FD10 flat panel system. To estimate the Ke,max on the patient’s skin radiochromic films(Gafchromic XR-RV2) were used. These values were estimated from the maximum optical density measured on film using a calibration curve. The results showed cumulative air kerma values ranging from 78.3- 500.0mGy, with a mean value of 242,3 mGy. The resulting Ke,max values ranged from 20.0-461.8 mGy, with a mean value of 208,8 mGy. The Ke,max values were correlated with the displayed cumulative air kerma values. The correlation factor R² was 0.78, meaning that the value displayed in the equipment’s console can be useful for monitoring the skin absorbed dose throughout the procedure. The routine fluoroscopy time records is not able by itself alert the physician about the risk of dose exceeding the threshold of adverse reactions, which can vary from an early erythema to serious harmful skin damage. (author)

  12. SU-C-207A-07: Cumulative 18F-FDG Uptake Histogram Relative to Radiation Dose Volume Histogram of Lung After IMRT Or PSPT and Their Association with Radiation Pneumonitis

    International Nuclear Information System (INIS)

    Shusharina, N; Choi, N; Bortfeld, T; Liao, Z; Mohan, R

    2016-01-01

    Purpose: To determine whether the difference in cumulative 18F-FDG uptake histogram of lung treated with either IMRT or PSPT is associated with radiation pneumonitis (RP) in patients with inoperable stage II and III NSCLC. Methods: We analyzed 24 patients from a prospective randomized trial to compare IMRT (n=12) with vs. PSPT (n=12) for inoperable NSCLC. All patients underwent PET-CT imaging between 35 and 88 days post-therapy. Post-treatment PET-CT was aligned with planning 4D CT to establish a voxel-to-voxel correspondence between post-treatment PET and planning dose images. 18F-FDG uptake as a function of radiation dose to normal lung was obtained for each patient. Distribution of the standard uptake value (SUV) was analyzed using a volume histogram method. The image quantitative characteristics and DVH measures were correlated with clinical symptoms of pneumonitis. Results: Patients with RP were present in both groups: 5 in the IMRT and 6 in the PSPT. The analysis of cumulative SUV histograms showed significantly higher relative volumes of the normal lung having higher SUV uptake in the PSPT patients for both symptomatic and asymptomatic cases (VSUV=2: 10% for IMRT vs 16% for proton RT and VSUV=1: 10% for IMRT vs 23% for proton RT). In addition, the SUV histograms for symptomatic cases in PSPT patients exhibited a significantly longer tail at the highest SUV. The absolute volume of the lung receiving the dose >70 Gy was larger in the PSPT patients. Conclusion: 18F-FDG uptake – radiation dose response correlates with RP in both groups of patients by means of the linear regression slope. SUV is higher for the PSPT patients for both symptomatic and asymptomatic cases. Higher uptake after PSPT patients is explained by larger volumes of the lung receiving high radiation dose.

  13. Repair and dose-response at low doses

    International Nuclear Information System (INIS)

    Totter, J.R.; Weinberg, A.M.

    1977-04-01

    The DNA of each individual is subject to formation of some 2-4 x 10 14 ion pairs during the first 30 years of life from background radiation. If a single hit is sufficient to cause cancer, as is implicit in the linear, no-threshold theories, it is unclear why all individuals do not succumb to cancer, unless repair mechanisms operate to remove the damage. We describe a simple model in which the exposed population displays a distribution of repair thresholds. The dose-response at low dose is shown to depend on the shape of the threshold distribution at low thresholds. If the probability of zero threshold is zero, the response at low dose is quadratic. The model is used to resolve a longstanding discrepancy between observed incidence of leukemia at Nagasaki and the predictions of the usual linear hypothesis

  14. Dose-response-a challenge for allelopathy?

    Science.gov (United States)

    Belz, Regina G; Hurle, Karl; Duke, Stephen O

    2005-04-01

    The response of an organism to a chemical depends, among other things, on the dose. Nonlinear dose-response relationships occur across a broad range of research fields, and are a well established tool to describe the basic mechanisms of phytotoxicity. The responses of plants to allelochemicals as biosynthesized phytotoxins, relate as well to nonlinearity and, thus, allelopathic effects can be adequately quantified by nonlinear mathematical modeling. The current paper applies the concept of nonlinearity to assorted aspects of allelopathy within several bioassays and reveals their analysis by nonlinear regression models. Procedures for a valid comparison of effective doses between different allelopathic interactions are presented for both, inhibitory and stimulatory effects. The dose-response applications measure and compare the responses produced by pure allelochemicals [scopoletin (7-hydroxy-6-methoxy-2H-1-benzopyran-2-one); DIBOA (2,4-dihydroxy-2H-1,4-benzoxaxin-3(4H)-one); BOA (benzoxazolin-2(3H)-one); MBOA (6-methoxy-benzoxazolin-2(3H)-one)], involved in allelopathy of grain crops, to demonstrate how some general principles of dose responses also relate to allelopathy. Hereupon, dose-response applications with living donor plants demonstrate the validity of these principles for density-dependent phytotoxicity of allelochemicals produced and released by living plants (Avena sativa L., Secale cereale L., Triticum L. spp.), and reveal the use of such experiments for initial considerations about basic principles of allelopathy. Results confirm that nonlinearity applies to allelopathy, and the study of allelopathic effects in dose-response experiments allows for new and challenging insights into allelopathic interactions.

  15. The occurrence of primary pulmonary neoplasms in rats after inhalation of 147Pm in fused aluminosilicate particles

    International Nuclear Information System (INIS)

    Herbert, R.A.; Scott, B.R.; Hahn, F.F.; Newton, G.J.; Snipes, M.B.; Damon, E.G.; Boecker, B.B.

    1988-01-01

    To determine the biological response following low-energy, beta irradiation of the lung, F344/Crl rats were exposed to aerosols of promethium-147 in fused aluminosilicate particles and observed for their life spans. Radiation pneumonitis and pulmonary fibrosis caused the majority of deaths during the first year after exposure with cumulative doses to the lungs of 210 to 630 Gy. Primary pulmonary neoplasms were responsible for the majority of deaths that occurred beyond 1 yr after exposure and in rats receiving lower cumulative doses to the lung. Hemangiosarcomas and squamous cell carcinomas were the most prevalent pulmonary neoplasms. Three adenocarcinomas were found. The uncorrected crude incidence of primary lung tumors increased with increasing dose to the lung for cumulative doses less than 140 Gy. With higher doses, the incidence declined. Adjusting the data for competing risks eliminated the turnover in the dose-response curve. The times of onset of pulmonary tumors and median survival times were dose-dependent. Rats with higher accumulated radiation doses developed fatal lung tumors at earlier times after exposure. (author)

  16. Establishment of 60Co dose calibration curve using fluorescent in situ hybridization assay technique: Result of preliminary study

    International Nuclear Information System (INIS)

    Rahimah Abdul Rahim; Noriah Jamal; Noraisyah Mohd Yusof; Juliana Mahamad Napiah; Nelly Bo Nai Lee

    2010-01-01

    This study aims at establishing an in-vitro 60 Co dose calibration curve using Fluorescent In-Situ Hybridization assay technique for the Malaysian National Bio dosimetry Laboratory. Blood samples collected from a female healthy donor were irradiated with several doses of 60 Co radiation. Following culturing of lymphocytes, microscopic slides are prepared, denatured and hybridized. The frequencies of translocation are estimated in the metaphases. A calibration curve was then generated using a regression technique. It shows a good fit to a linear-quadratic model. The results of this study might be useful in estimating absorbed dose for the individual exposed to ionizing radiation retrospectively. This information may be useful as a guide for medical treatment for the assessment of possible health consequences. (author)

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

    International Nuclear Information System (INIS)

    Levy, R.P.

    1991-01-01

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

  18. Lysis solution composition and non-linear dose-response to ionizing radiation in the non-denaturing DNA filter elution technique

    International Nuclear Information System (INIS)

    Radford, I.R.

    1990-01-01

    The suggestion by Okayasu and Iliakis (1989) that the non-linear dose-response curve, obtained with the non-denaturing filter elution technique for mammalian cells exposed to low-LET radiation, is the result of a technical artefact, was not confirmed. (author)

  19. Bootstrap confidence intervals for principal response curves

    NARCIS (Netherlands)

    Timmerman, Marieke E.; Ter Braak, Cajo J. F.

    2008-01-01

    The principal response curve (PRC) model is of use to analyse multivariate data resulting from experiments involving repeated sampling in time. The time-dependent treatment effects are represented by PRCs, which are functional in nature. The sample PRCs can be estimated using a raw approach, or the

  20. Bootstrap Confidence Intervals for Principal Response Curves

    NARCIS (Netherlands)

    Timmerman, M.E.; Braak, ter C.J.F.

    2008-01-01

    The principal response curve (PRC) model is of use to analyse multivariate data resulting from experiments involving repeated sampling in time. The time-dependent treatment effects are represented by PRCs, which are functional in nature. The sample PRCs can be estimated using a raw approach, or the

  1. A dose of nature: Tree cover, stress reduction, and gender differences

    Science.gov (United States)

    Bin Jiang; Chun-Yen Chang; William C. Sullivan

    2014-01-01

    Although it is well established that exposure to nearby nature can help reduce stress in individuals, the shape of the dose-response curve is entirely unclear. To establish this dose-response curve, we recruited 160 individuals for a laboratory experiment. Participants engaged in the Trier Social Stress Test (TSST) to induce psychological stress, and were then randomly...

  2. Dose-response regressions for algal growth and similar continuous endpoints: Calculation of effective concentrations

    DEFF Research Database (Denmark)

    Christensen, Erik R.; Kusk, Kresten Ole; Nyholm, Niels

    2009-01-01

    We derive equations for the effective concentration giving 10% inhibition (EC10) with 95% confidence limits for probit (log-normal), Weibull, and logistic dose -responsemodels on the basis of experimentally derived median effective concentrations (EC50s) and the curve slope at the central point (50......% inhibition). For illustration, data from closed, freshwater algal assays are analyzed using the green alga Pseudokirchneriella subcapitata with growth rate as the response parameter. Dose-response regressions for four test chemicals (tetraethylammonium bromide, musculamine, benzonitrile, and 4...... regression program with variance weighting and proper inverse estimation. The Weibull model provides the best fit to the data for all four chemicals. Predicted EC10s (95% confidence limits) from our derived equations are quite accurate; for example, with 4-4-(trifluoromethyl)phenoxy-phenol and the probit...

  3. The alanine detector in BNCT dosimetry: dose response in thermal and epithermal neutron fields.

    Science.gov (United States)

    Schmitz, T; Bassler, N; Blaickner, M; Ziegner, M; Hsiao, M C; Liu, Y H; Koivunoro, H; Auterinen, I; Serén, T; Kotiluoto, P; Palmans, H; Sharpe, P; Langguth, P; Hampel, G

    2015-01-01

    The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a (60)Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes fluka and mcnp. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen & Olsen alanine response model. The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. The alanine detector can be used without

  4. SU-G-BRB-14: Uncertainty of Radiochromic Film Based Relative Dose Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Devic, S; Tomic, N; DeBlois, F; Seuntjens, J [McGill University, Montreal, QC (Canada); Lewis, D [RCF Consulting, LLC, Monroe, CT (United States); Aldelaijan, S [King Faisal Specialist Hospital & Research Center, Riyadh (Saudi Arabia)

    2016-06-15

    Purpose: Due to inherently non-linear dose response, measurement of relative dose distribution with radiochromic film requires measurement of absolute dose using a calibration curve following previously established reference dosimetry protocol. On the other hand, a functional form that converts the inherently non-linear dose response curve of the radiochromic film dosimetry system into linear one has been proposed recently [Devic et al, Med. Phys. 39 4850–4857 (2012)]. However, there is a question what would be the uncertainty of such measured relative dose. Methods: If the relative dose distribution is determined going through the reference dosimetry system (conversion of the response by using calibration curve into absolute dose) the total uncertainty of such determined relative dose will be calculated by summing in quadrature total uncertainties of doses measured at a given and at the reference point. On the other hand, if the relative dose is determined using linearization method, the new response variable is calculated as ζ=a(netOD)n/ln(netOD). In this case, the total uncertainty in relative dose will be calculated by summing in quadrature uncertainties for a new response function (σζ) for a given and the reference point. Results: Except at very low doses, where the measurement uncertainty dominates, the total relative dose uncertainty is less than 1% for the linear response method as compared to almost 2% uncertainty level for the reference dosimetry method. The result is not surprising having in mind that the total uncertainty of the reference dose method is dominated by the fitting uncertainty, which is mitigated in the case of linearization method. Conclusion: Linearization of the radiochromic film dose response provides a convenient and a more precise method for relative dose measurements as it does not require reference dosimetry and creation of calibration curve. However, the linearity of the newly introduced function must be verified. Dave Lewis

  5. Individualized versus standard FSH dosing in women starting IVF/ICSI: An RCT. Part 2: The predicted hyper responder

    OpenAIRE

    Oudshoorn, Simone C.; Van Tilborg, Theodora C.; Eijkemans, Marinus J. C.; Oosterhuis, G. Jur E.; Friederich, Jaap; van Hooff, Marcel H. A.; van Santbrink, Evert J. P.; Brinkhuis, Egbert A.; Smeenk, Jesper M. J.; Kwee, Janet; de Koning, Corry H.; Groen, Henk; Lambalk, Cornelis B.; Mol, Ben Willem J.; Broekmans, Frank J. M.

    2017-01-01

    STUDY QUESTION: Does a reduced FSH dose in women with a predicted hyper response, apparent from a high antral follicle count (AFC), who are scheduled for IVF/ICSI lead to a different outcome with respect to cumulative live birth rate and safety? SUMMARY ANSWER: Although in women with a predicted hyper response (AFC > 15) undergoing IVF/ICSI a reduced FSH dose (100 IU per day) results in similar cumulative live birth rates and a lower occurrence of any grade of ovarian hyperstimulation syndrom...

  6. Optimal sensitometric curves of Kodak EDR2 film for dynamic intensity modulated radiation therapy verification.

    Science.gov (United States)

    Suriyapee, S; Pitaxtarnin, N; Oonsiri, S; Jumpangern, C; Israngkul Na Ayuthaya, I

    2008-01-01

    To investigate the optimal sensitometric curves of extended dose range (EDR2) radiographic film in terms of depth, field size, dose range and processing conditions for dynamic intensity modulated radiation therapy (IMRT) dosimetry verification with 6 MV X-ray beams. A Varian Clinac 23 EX linear accelerator with 6 MV X-ray beam was used to study the response of Kodak EDR2 film. Measurements were performed at depths of 5, 10 and 15 cm in MedTec virtual water phantom and with field sizes of 2x2, 3x3, 10x10 and 15x15 cm(2). Doses ranging from 20 to 450 cGy were used. The film was developed with the Kodak RP X-OMAT Model M6B automatic film processor. Film response was measured with the Vidar model VXR-16 scanner. Sensitometric curves were applied to the dose profiles measured with film at 5 cm in the virtual water phantom with field sizes of 2x2 and 10x10 cm(2) and compared with ion chamber data. Scanditronix/Wellhofer OmniPro(TM) IMRT software was used for the evaluation of the IMRT plan calculated by Eclipse treatment planning. Investigation of the reproducibility and accuracy of the film responses, which depend mainly on the film processor, was carried out by irradiating one film nine times with doses of 20 to 450 cGy. A maximum standard deviation of 4.9% was found which decreased to 1.9% for doses between 20 and 200 cGy. The sensitometric curves for various field sizes at fixed depth showed a maximum difference of 4.2% between 2x2 and 15x15 cm(2) at 5 cm depth with a dose of 450 cGy. The shallow depth tended to show a greater effect of field size responses than the deeper depths. The sensitometric curves for various depths at fixed field size showed slightly different film responses; the difference due to depth was within 1.8% for all field sizes studied. Both field size and depth effect were reduced when the doses were lower than 450 cGy. The difference was within 2.5% in the dose range from 20 to 300 cGy for all field sizes and depths studied. Dose profiles

  7. Calibration Curves for Biological Dosimetry by Fluorescence In situ Hybridisation

    International Nuclear Information System (INIS)

    Stonati, L.; Durante, M.; Gensabella, G.; Gialanella, G.; Grossi, G.F.; Pugliese, M.; Scampoli, P.; Sgura, A.; Testa, A.; Tanzarella, C.

    2001-01-01

    Dose-response curves were measured for the induction of chromosomal aberrations in peripheral blood lymphocytes after acute exposure in vitro to 60 Co γ rays. Blood was obtained from four different healthy donors, and chromosomes were either observed at metaphase, following colcemid accumulation, or prematurely condensed by calyculin A. Cells were analysed in three different Italian laboratories. Chromosomes 1, 2, and 4 were painted, and simple-type interchanges between painted and non-painted chromosomes were scored in cells exposed in the dose range 0.1-3.0 Gy. The chemical-induced premature chromosome condensation method was also used combined with chromosome painting (chromosome 4 only) to determine calibration curves for high dose exposures (up to 20 Gy X rays). Calibration curves described in this paper will be used in our laboratories for biological dosimetry by fluorescence in situ hybridisation. (author)

  8. Smooth time-dependent receiver operating characteristic curve estimators.

    Science.gov (United States)

    Martínez-Camblor, Pablo; Pardo-Fernández, Juan Carlos

    2018-03-01

    The receiver operating characteristic curve is a popular graphical method often used to study the diagnostic capacity of continuous (bio)markers. When the considered outcome is a time-dependent variable, two main extensions have been proposed: the cumulative/dynamic receiver operating characteristic curve and the incident/dynamic receiver operating characteristic curve. In both cases, the main problem for developing appropriate estimators is the estimation of the joint distribution of the variables time-to-event and marker. As usual, different approximations lead to different estimators. In this article, the authors explore the use of a bivariate kernel density estimator which accounts for censored observations in the sample and produces smooth estimators of the time-dependent receiver operating characteristic curves. The performance of the resulting cumulative/dynamic and incident/dynamic receiver operating characteristic curves is studied by means of Monte Carlo simulations. Additionally, the influence of the choice of the required smoothing parameters is explored. Finally, two real-applications are considered. An R package is also provided as a complement to this article.

  9. Determination of electron depth-dose curves for water, ICRU tissue, and PMMA and their application to radiation protection dosimetry

    International Nuclear Information System (INIS)

    Grosswendt, B.

    1994-01-01

    For monoenergetic electrons in the energy range between 60 keV and 10 MeV, normally incident on water, 4-element ICRU tissue and PMMA phantoms, depth-dose curves have been calculated using the Monte Carlo method. The phantoms' shape was that of a rectangular solid with a square front face of 30 cm x 30 cm and a thickness of 15 cm; it corresponds to that recommended by the ICRU for use in the procedure of calibrating radiation protection dosemeters. The depth-dose curves have been used to determine practical ranges, half-value depths, electron fluence to maximum absorbed dose conversion factors, and conversion factors between electron fluence and absorbed dose at depths d corresponding to 0.007 g.cm -2 , 0.3 g.cm -2 , and 1.0 g.cm -2 . The latter data can be used as fluence to dose equivalent conversion factors for extended parallel electron beams. (Author)

  10. Dose-response relationship in clinical oncology

    International Nuclear Information System (INIS)

    Gehan, E.A.

    1984-01-01

    The relationship of dose (and dose rate) to response and toxicity in clinical oncology is reviewed. The concepts expressed by some authors in dose-response studies in animal and human systems are reviewed briefly. Dose rate and tactics of conducting clinical studies are reviewed for both radiotherapy and various types of chemotherapeutic treatment. Examples are given from clinical studies in Hodgkin's disease, acute leukemia, and breast cancer that may prove useful in planning future clinical studies

  11. VMAT QA: Measurement-guided 4D dose reconstruction on a patient

    Energy Technology Data Exchange (ETDEWEB)

    Nelms, Benjamin E.; Opp, Daniel; Robinson, Joshua; Wolf, Theresa K.; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir [Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Live Oak Technologies LLC, Kirkwood, Missouri 63122 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States)

    2012-07-15

    Purpose: To develop and validate a volume-modulated arc therapy (VMAT) quality assurance (QA) tool that takes as input a time-resolved, low-density ({approx}10 mm) cylindrical surface dose map from a commercial helical diode array, and outputs a high density, volumetric, time-resolved dose matrix on an arbitrary patient dataset. This first validation study is limited to a homogeneous 'patient.'Methods: A VMAT treatment is delivered to a diode array phantom (ARCCHECK, Sun Nuclear Corp., Melbourne, FL). 3DVH software (Sun Nuclear) derives the high-density volumetric dose using measurement-guided dose reconstruction (MGDR). MGDR cylindrical phantom results are then used to perturb the three-dimensional (3D) treatment planning dose on the patient dataset, producing a semiempirical volumetric dose grid. Four-dimensional (4D) dose reconstruction on the patient is also possible by morphing individual sub-beam doses instead of the composite. For conventional (3D) dose comparison two methods were developed, using the four plans (Multi-Target, C-shape, Mock Prostate, and Head and Neck), including their structures and objectives, from the AAPM TG-119 report. First, 3DVH and treatment planning system (TPS) cumulative point doses were compared to ion chamber in a cube water-equivalent phantom ('patient'). The shape of the phantom is different from the ARCCHECK and furthermore the targets were placed asymmetrically. Second, coronal and sagittal absolute film dose distributions in the cube were compared with 3DVH and TPS. For time-resolved (4D) comparisons, three tests were performed. First, volumetric dose differences were calculated between the 3D MGDR and cumulative time-resolved patient (4D MGDR) dose at the end of delivery, where they ideally should be identical. Second, time-resolved (10 Hz sampling rate) ion chamber doses were compared to cumulative point dose vs time curves from 4D MGDR. Finally, accelerator output was varied to assess the linearity of

  12. Dose-response relationship of dicentric chromosomes in human lymphocytes obtained for the fission neutron therapy facility MEDAPP at the research reactor FRM II.

    Science.gov (United States)

    Schmid, E; Wagner, F M; Romm, H; Walsh, L; Roos, H

    2009-02-01

    The biological effectiveness of neutrons from the neutron therapy facility MEDAPP (mean neutron energy 1.9 MeV) at the new research reactor FRM II at Garching, Germany, has been analyzed, at different depths in a polyethylene phantom. Whole blood samples were exposed to the MEDAPP beam in special irradiation chambers to total doses of 0.14-3.52 Gy at 2-cm depth, and 0.18-3.04 Gy at 6-cm depth of the phantom. The neutron and gamma-ray absorbed dose rates were measured to be 0.55 Gy min(-1) and 0.27 Gy min(-1) at 2-cm depth, while they were 0.28 and 0.25 Gy min(-1) at 6-cm depth. Although the irradiation conditions at the MEDAPP beam and the RENT beam of the former FRM I research reactor were not identical, neutrons from both facilities gave a similar linear-quadratic dose-response relationship for dicentric chromosomes at a depth of 2 cm. Different dose-response curves for dicentrics were obtained for the MEDAPP beam at 2 and 6 cm depth, suggesting a significantly lower biological effectiveness of the radiation with increasing depth. No obvious differences in the dose-response curves for dicentric chromosomes estimated under interactive or additive prediction between neutrons or gamma-rays and the experimentally obtained dose-response curves could be determined. Relative to (60)Co gamma-rays, the values for the relative biological effectiveness at the MEDAPP beam decrease from 5.9 at 0.14 Gy to 1.6 at 3.52 Gy at 2-cm depth, and from 4.1 at 0.18 Gy to 1.5 at 3.04 Gy at 6-cm depth. Using the best possible conditions of consistency, i.e., using blood samples from the same donor and the same measurement techniques for about two decades, avoiding the inter-individual variations in sensitivity or the differences in methodology usually associated with inter-laboratory comparisons, a linear-quadratic dose-response relationship for the mixed neutron and gamma-ray MEDAPP field as well as for its fission neutron part was obtained. Therefore, the debate on whether the fission

  13. Dose-response relationship for elective neck irradiation of head and neck cancer - facts and controversies

    International Nuclear Information System (INIS)

    Suwinski, R.; Maciejewski, B.; Withers, H.R.

    1998-01-01

    The aim of this study is to assign dose-response relationship for subclinical neck metastases of squamous cell head and neck cancer based on extensive survey of 24 data sets collected from the literature. Neck relapse rates (NRR) without and after elective (ENI) or preoperative irradiation were estimated for each site and stage of primary tumor and the reduction in neck relapse rate was calculated. An average NRR without ENI was 22% (12-35% ) and only 2.5% (0-1 0%) after the ENI with total dose of 46- 50 Gy which gives high reduction rate in the risk of neck recurrences being on the average 89% and 42% (0-46%) after preoperative irradiation using 22-30 Gy. Dose response curve for elective and preoperative irradiation have shown that 50 Gy in 2 Gy fraction reduces the incidence of neck relapses in the NO patients by more than 90% and only by less than 50% after total doses lower than 30 Gy. No correlation between the risk of neck metastases without ENI and the reduction in neck relapses after ENI was found. (authors)

  14. Statistical determination of significant curved I-girder bridge seismic response parameters

    Science.gov (United States)

    Seo, Junwon

    2013-06-01

    Curved steel bridges are commonly used at interchanges in transportation networks and more of these structures continue to be designed and built in the United States. Though the use of these bridges continues to increase in locations that experience high seismicity, the effects of curvature and other parameters on their seismic behaviors have been neglected in current risk assessment tools. These tools can evaluate the seismic vulnerability of a transportation network using fragility curves. One critical component of fragility curve development for curved steel bridges is the completion of sensitivity analyses that help identify influential parameters related to their seismic response. In this study, an accessible inventory of existing curved steel girder bridges located primarily in the Mid-Atlantic United States (MAUS) was used to establish statistical characteristics used as inputs for a seismic sensitivity study. Critical seismic response quantities were captured using 3D nonlinear finite element models. Influential parameters from these quantities were identified using statistical tools that incorporate experimental Plackett-Burman Design (PBD), which included Pareto optimal plots and prediction profiler techniques. The findings revealed that the potential variation in the influential parameters included number of spans, radius of curvature, maximum span length, girder spacing, and cross-frame spacing. These parameters showed varying levels of influence on the critical bridge response.

  15. Repeated Radionuclide therapy in metastatic paraganglioma leading to the highest reported cumulative activity of 131I-MIBG

    International Nuclear Information System (INIS)

    Ezziddin, Samer; Sabet, Amir; Ko, Yon-Dschun; Xun, Sunny; Matthies, Alexander; Biersack, Hans-Jürgen

    2012-01-01

    131 I-MIBG therapy for neuroendocrine tumours may be dose limited. The common range of applied cumulative activities is 10-40 GBq. We report the uneventful cumulative administration of 111 GBq (= 3 Ci) 131 I-MIBG in a patient with metastatic paraganglioma. Ten courses of 131 I-MIBG therapy were given within six years, accomplishing symptomatic, hormonal and tumour responses with no serious adverse effects. Chemotherapy with cisplatin/vinblastine/dacarbazine was the final treatment modality with temporary control of disease, but eventually the patient died of progression. The observed cumulative activity of 131 I-MIBG represents the highest value reported to our knowledge, and even though 12.6 GBq of 90 Y-DOTATOC were added intermediately, no associated relevant bone marrow, hepatic or other toxicity were observed. In an individual attempt to palliate metastatic disease high cumulative activity alone should not preclude the patient from repeat treatment

  16. Cumulative exposure to prior collective trauma and acute stress responses to the Boston marathon bombings.

    Science.gov (United States)

    Garfin, Dana Rose; Holman, E Alison; Silver, Roxane Cohen

    2015-06-01

    The role of repeated exposure to collective trauma in explaining response to subsequent community-wide trauma is poorly understood. We examined the relationship between acute stress response to the 2013 Boston Marathon bombings and prior direct and indirect media-based exposure to three collective traumatic events: the September 11, 2001 (9/11) terrorist attacks, Superstorm Sandy, and the Sandy Hook Elementary School shooting. Representative samples of residents of metropolitan Boston (n = 846) and New York City (n = 941) completed Internet-based surveys shortly after the Boston Marathon bombings. Cumulative direct exposure and indirect exposure to prior community trauma and acute stress symptoms were assessed. Acute stress levels did not differ between Boston and New York metropolitan residents. Cumulative direct and indirect, live-media-based exposure to 9/11, Superstorm Sandy, and the Sandy Hook shooting were positively associated with acute stress responses in the covariate-adjusted model. People who experience multiple community-based traumas may be sensitized to the negative impact of subsequent events, especially in communities previously exposed to similar disasters. © The Author(s) 2015.

  17. Cumulative occupational shoulder exposures and surgery for subacromial impingement syndrome: a nationwide Danish cohort study.

    Science.gov (United States)

    Dalbøge, Annett; Frost, Poul; Andersen, Johan Hviid; Svendsen, Susanne Wulff

    2014-11-01

    The primary aim was to examine exposure-response relationships between cumulative occupational shoulder exposures and surgery for subacromial impingement syndrome (SIS), and to compare sex-specific exposure-response relationships. The secondary aim was to examine the time window of relevant exposures. We conducted a nationwide register study of all persons born in Denmark (1933-1977), who had at least 5 years of full-time employment. In the follow-up period (2003-2008), we identified first-time events of surgery for SIS. Cumulative exposure estimates for a 10-year exposure time window with a 1-year lag time were obtained by linking occupational codes with a job exposure matrix. The exposure estimates were expressed as, for example, arm-elevation-years in accordance with the pack-year concept of tobacco consumption. We used a multivariable logistic regression technique equivalent to discrete survival analysis. The adjusted OR (ORadj) increased to a maximum of 2.1 for arm-elevation-years, repetition-years and force-years, and to 1.5 for hand-arm-vibration-years. Sex-specific exposure-response relationships were similar for men and women, when assessed using a relative risk scale. The ORadj increased gradually with the number of years contributing to the cumulative exposure estimates. The excess fraction was 24%. Cumulative occupational shoulder exposures carried an increase in risk of surgery for SIS with similar exposure-response curves for men and women. The risk of surgery for SIS increased gradually, when the period of exposure assessment was extended. In the general working population, a substantial fraction of all first-time operations for SIS could be related to occupational exposures. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  18. Modularization and Response Curve Engineering of a Naringenin-Responsive Transcriptional Biosensor.

    Science.gov (United States)

    De Paepe, Brecht; Maertens, Jo; Vanholme, Bartel; De Mey, Marjan

    2018-05-18

    To monitor the intra- and extracellular environment of micro-organisms and to adapt their metabolic processes accordingly, scientists are reprogramming nature's myriad of transcriptional regulatory systems into transcriptional biosensors, which are able to detect small molecules and, in response, express specific output signals of choice. However, the naturally occurring response curve, the key characteristic of biosensor circuits, is typically not in line with the requirements for real-life biosensor applications. In this contribution, a natural LysR-type naringenin-responsive biosensor circuit is developed and characterized with Escherichia coli as host organism. Subsequently, this biosensor is dissected into a clearly defined detector and effector module without loss of functionality, and the influence of the expression levels of both modules on the biosensor response characteristics is investigated. Two collections of ten unique synthetic biosensors each are generated. Each collection demonstrates a unique diversity of response curve characteristics spanning a 128-fold change in dynamic and 2.5-fold change in operational ranges and 3-fold change in levels of Noise, fit for a wide range of applications, such as adaptive laboratory evolution, dynamic pathway control and high-throughput screening methods. The established biosensor engineering concepts, and the developed biosensor collections themselves, are of use for the future development and customization of biosensors in general, for the multitude of biosensor applications and as a compelling alternative for the commonly used LacI-, TetR- and AraC-based inducible circuits.

  19. Dose volume assessment of high dose rate 192IR endobronchial implants

    International Nuclear Information System (INIS)

    Cheng, B. Saw; Korb, Leroy J.; Pawlicki, Todd; Wu, Andrew

    1996-01-01

    Purpose: To study the dose distributions of high dose rate (HDR) endobronchial implants using the dose nonuniformity ratio (DNR) and three volumetric irradiation indices. Methods and Materials: Multiple implants were configured by allowing a single HDR 192 Ir source to step through a length of 6 cm along an endobronchial catheter. Dwell times were computed to deliver a dose of 5 Gy to points 1 cm away from the catheter axis. Five sets of source configurations, each with different dwell position spacings from 0.5 to 3.0 cm, were evaluated. Three-dimensional (3D) dose distributions were then generated for each source configuration. Differential and cumulative dose-volume curves were generated to quantify the degree of target volume coverage, dose nonuniformity within the target volume, and irradiation of tissues outside the target volume. Evaluation of the implants were made using the DNR and three volumetric irradiation indices. Results: The observed isodose distributions were not able to satisfy all the dose constraints. The ability to optimally satisfy the dose constraints depended on the choice of dwell position spacing and the specification of the dose constraint points. The DNR and irradiation indices suggest that small dwell position spacing does not result in a more homogeneous dose distribution for the implant. This study supports the existence of a relationship between the dwell position spacing and the distance from the catheter axis to the reference dose or dose constraint points. Better dose homogeneity for an implant can be obtained if the spacing of the dwell positions are about twice the distance from the catheter axis to the reference dose or dose constraint points

  20. Cumulative effective dose associated with computed tomography examinations in adolescent trauma patients.

    Science.gov (United States)

    Choi, Seung Joon; Kim, Eun Young; Kim, Hyung Sik; Choi, Hye-Young; Cho, Jinseong; Yang, Hyuk Jun; Chung, Yong Eun

    2014-07-01

    The aims of this study were to analyze cumulative effective dose (cED) and to assess lifetime attributable risk (LAR) of cancer due to radiation exposure during computed tomography (CT) examinations in adolescent trauma patients. Between January 2010 and May 2011, the adolescent patients with trauma were enrolled in this study. Numbers of CT examinations and body regions examined were collated, and cEDs were calculated using dose-length product values and conversion factors. Lifetime attributable risk for cancer incidence and cancer-associated mortality were quantified based on the studies of survivors of the atomic bombs on Japan. Data were stratified according to severity of trauma: minor trauma, injury severity score of less than 16; and major trauma, injury severity score of 16 or greater. A total of 698 CT scans were obtained on the following regions of 484 adolescent patients: head CT, n = 647; rest of the body, n = 41; and thorax, n = 10. Mean cED per patient was 3.4 mSv, and mean LARs for cancer incidence and mortality were 0.05% and 0.02%, respectively. The majority of patients (98.4%) experienced minor trauma, and their mean cED and LARs for cancer incidence and mortality (3.0 mSv and 0.04% and 0.02%, respectively) were significantly lower than those of patients with major trauma (24.3 mSv and 0.31% and 0.15%, respectively, all P values trauma was found to be relatively low in adolescent patients. However, adolescent patients with major trauma were exposed to a substantial amount of radiation during multiple CT examinations.

  1. Biological responses to low dose rate gamma radiation

    International Nuclear Information System (INIS)

    Magae, Junji; Ogata, Hiromitsu

    2003-01-01

    Linear non-threshold (LNT) theory is a basic theory for radioprotection. While LNT dose not consider irradiation time or dose-rate, biological responses to radiation are complex processes dependent on irradiation time as well as total dose. Moreover, experimental and epidemiological studies that can evaluate LNT at low dose/low dose-rate are not sufficiently accumulated. Here we analyzed quantitative relationship among dose, dose-rate and irradiation time using chromosomal breakage and proliferation inhibition of human cells as indicators of biological responses. We also acquired quantitative data at low doses that can evaluate adaptability of LNT with statistically sufficient accuracy. Our results demonstrate that biological responses at low dose-rate are remarkably affected by exposure time, and they are dependent on dose-rate rather than total dose in long-term irradiation. We also found that change of biological responses at low dose was not linearly correlated to dose. These results suggest that it is necessary for us to create a new model which sufficiently includes dose-rate effect and correctly fits of actual experimental and epidemiological results to evaluate risk of radiation at low dose/low dose-rate. (author)

  2. Competing risk theory and radiation risk assessment

    International Nuclear Information System (INIS)

    Groer, P.G.

    1980-01-01

    New statistical procedures are applied to estimate cumulative distribution functions (c.d.f.), force of mortality, and latent period for radiation-induced malignancies. It is demonstrated that correction for competing risks influences the shape of dose response curves, estimates of the latent period, and of the risk from ionizing radiations. The equivalence of the following concepts is demonstrated: force of mortality, hazard rate, and age or time specific incidence. This equivalence makes it possible to use procedures from reliability analysis and demography for radiation risk assessment. Two methods used by reliability analysts - hazard plotting and total time on test plots - are discussed in some detail and applied to characterize the hazard rate in radiation carcinogenesis. C.d.f.'s with increasing, decreasing, or constant hazard rate have different shapes and are shown to yield different dose-response curves for continuous irradiation. Absolute risk is shown to be a sound estimator only if the force of mortality is constant for the exposed and the control group. Dose-response relationships that use the absolute risk as a measure for the effect turn out to be special cases of dose-response relationships that measure the effect with cumulative incidence. (H.K.)

  3. Absorbed dose distributions in patients with bone metastases from hormone refractory prostate cancer treated with Re-186 HEDP

    International Nuclear Information System (INIS)

    Denis Bacelar, A.M.; Dearnaley, D.P.; Divoli, A.; Chittenden, S.; Du, Y.; Flux, G.D.; O'Sullivan, J.M.

    2015-01-01

    Full text of publication follows. Aim: intravenous administration of Re-186 hydroxyethylidene-diphosphonate (HEDP) is used for metastatic bone pain palliation in hormone refractory prostate cancer patients. Dosimetry for bone seeking radionuclides is challenging due to the complex structure with osteoblastic, osteolytic and mixed lesions. The aim of this study was to perform image-based patient-specific 3D convolution dosimetry to obtain a distribution of the absorbed doses to each lesion and estimate inter- and intra-patient variations. Materials and methods: 28 patients received a fixed 5 GBq activity of Re-186 HEDP followed by peripheral blood stem cell rescue at 14 days in a phase II trial. A FORTE dual-headed gamma camera was used to acquire sequential Single-Photon-Emission Computed Tomography (SPECT) data of the thorax and pelvis area at 1, 4, 24, 48 and 72 hours following administration. The projection data were reconstructed using filtered-back projection and were corrected for attenuation and scatter. Voxelised cumulated activity distributions were obtained with two different methods. First, the scans were co-registered and the time-activity curves were obtained on a voxel-by-voxel basis. Second, the clearance curve was obtained from the mean number of counts in each individual lesion and used to scale the uptake distribution taken at 24 hours. The calibration factors required for image quantification were obtained from a phantom experiment. An in-house developed EGSnrc Monte Carlo code was used for the calculation of dose voxel kernels for soft-tissue and cortical/trabecular bone used to perform convolution dosimetry. Cumulative dose-volume histograms were produced and mean absorbed doses calculated for each spinal and pelvic lesion. Results: preliminary results show that the lesion mean absorbed doses ranged from 25 to 55 Gy when the medium was soft tissue and decreased by 40% if bone was considered. The use of the cumulated activity distribution

  4. Physiological and immunological changes following exposure to low versus high-dose ionizing irradiation; comparative analysis with dose rate and cumulative dose

    International Nuclear Information System (INIS)

    Heesun, Kim; Heewon, Jang; Soungyeon, Song; Shinhye, Oh; Cukcheul, Shin; Meeseon, Jeong; Chasoon, Kim; Kwnaghee, Yang; Seonyoung, Nam; Jiyoung, Kim; Youngwoo, Jin; Changyoung, Cha

    2008-01-01

    Full text: While high-dose of ionizing radiation is generally harmful and causes damage to living organisms some reports suggest low-dose of radiation may not be as damaging as previously thought. Despite increasing evidence regarding the protective effect of low-dose radiation, no studies have directly compared the exact dose-response pattern by high- and low-dose of radiation exposed at high-and low-dose rate. This study aims to explore the cellular and molecular changes in mice exposed to low- and high-dose of radiation exposed at low- and high-dose rate. When C57BL/6 mice (Female, 6 weeks) were exposed at high-dose rate, 0.8 Gy/min, no significant change on the level of WBC, RBC, or platelets was observed up to total dose of 0.5 Gy. However, 2 Gy of radiation caused dramatic reduction in the level of white blood cells (WBC) and platelets. This reduction was accompanied by increased DNA damage in hematopoietic environments. The reduction of WBC was mainly due to the reduction in the number of CD4+ T cells and CD19+ B cells. CD8+ T cells and NK cells appeared to be relatively resistant to high-dose of radiation. This change was also accompanied by the reduction of T- and B- progenitor cells in the bone marrow. In contrast, no significant changes of the number of CD4+ T, CD8+ T, NK, and B cells were observed in the spleen of mice exposed at low-dose-rate (0.7 m Gy/h or 3.95 mGy/h) for up to 2 Gy, suggesting that low-dose radiation does not alter cellular distribution in the spleen. Nevertheless, mice exposed to low-dose radiation exhibited elevation of VEGF, MCP-1, IL-4, Leptin, IL-3, and Tpo in the peripheral blood and slight increases in MIP-2, RANTES, and IL-2 in the spleen. This suggests that chronic γ-radiation can stimulate immune function without causing damage to the immune components of the body. Taken together, these data indicate hormesis of low-dose radiation, which could be attributed to the stimulation of immune function. Dose rate rather than total

  5. Parotid gland mean dose as a xerostomia predictor in low-dose domains.

    Science.gov (United States)

    Gabryś, Hubert Szymon; Buettner, Florian; Sterzing, Florian; Hauswald, Henrik; Bangert, Mark

    2017-09-01

    Xerostomia is a common side effect of radiotherapy resulting from excessive irradiation of salivary glands. Typically, xerostomia is modeled by the mean dose-response characteristic of parotid glands and prevented by mean dose constraints to either contralateral or both parotid glands. The aim of this study was to investigate whether normal tissue complication probability (NTCP) models based on the mean radiation dose to parotid glands are suitable for the prediction of xerostomia in a highly conformal low-dose regime of modern intensity-modulated radiotherapy (IMRT) techniques. We present a retrospective analysis of 153 head and neck cancer patients treated with radiotherapy. The Lyman Kutcher Burman (LKB) model was used to evaluate predictive power of the parotid gland mean dose with respect to xerostomia at 6 and 12 months after the treatment. The predictive performance of the model was evaluated by receiver operating characteristic (ROC) curves and precision-recall (PR) curves. Average mean doses to ipsilateral and contralateral parotid glands were 25.4 Gy and 18.7 Gy, respectively. QUANTEC constraints were met in 74% of patients. Mild to severe (G1+) xerostomia prevalence at both 6 and 12 months was 67%. Moderate to severe (G2+) xerostomia prevalence at 6 and 12 months was 20% and 15%, respectively. G1 + xerostomia was predicted reasonably well with area under the ROC curve ranging from 0.69 to 0.76. The LKB model failed to provide reliable G2 + xerostomia predictions at both time points. Reduction of the mean dose to parotid glands below QUANTEC guidelines resulted in low G2 + xerostomia rates. In this dose domain, the mean dose models predicted G1 + xerostomia fairly well, however, failed to recognize patients at risk of G2 + xerostomia. There is a need for the development of more flexible models able to capture complexity of dose response in this dose regime.

  6. Epidemiological methods for assessing dose-response and dose-effect relationships

    DEFF Research Database (Denmark)

    Kjellström, Tord; Grandjean, Philippe

    2007-01-01

    Selected Molecular Mechanisms of Metal Toxicity and Carcinogenicity General Considerations of Dose-Effect and Dose-Response Relationships Interactions in Metal Toxicology Epidemiological Methods for Assessing Dose-Response and Dose-Effect Relationships Essential Metals: Assessing Risks from Deficiency......Description Handbook of the Toxicology of Metals is the standard reference work for physicians, toxicologists and engineers in the field of environmental and occupational health. This new edition is a comprehensive review of the effects on biological systems from metallic elements...... access to a broad range of basic toxicological data and also gives a general introduction to the toxicology of metallic compounds. Audience Toxicologists, physicians, and engineers in the fields of environmental and occupational health as well as libraries in these disciplines. Will also be a useful...

  7. Dose-response relationship with radiotherapy: an evidence?

    International Nuclear Information System (INIS)

    Chauvet, B.; Rauglaudre, G. de; Mineur, L.; Alfonsi, M.; Reboul, F.

    2003-01-01

    The dose-response relationship is a fundamental basis of radiobiology. Despite many clinical data, difficulties remain to demonstrate a relation between dose and local control: relative role of treatment associated with radiation therapy (surgery, chemotherapy, hormonal therapy), tumor heterogeneity, few prospective randomized studies, uncertainty of local control assessment. Three different situations are discussed: tumors with high local control probabilities for which dose effect is demonstrated by randomized studies (breast cancer) or sound retrospective data (soft tissues sarcomas), tumors with intermediate local control probabilities for which dose effect seems to be important according to retrospective studies and ongoing or published phase III trials (prostate cancer), tumors with low local control probabilities for which dose effect appears to be modest beyond standard doses, and inferior to the benefit of concurrent chemotherapy (lung and oesophageal cancer). For head and neck tumors, the dose-response relationship has been explored through hyperfractionation and accelerated radiation therapy and a dose effect has been demonstrated but must be compared to the benefit of concurrent chemotherapy. Last but not least, the development of conformal radiotherapy allow the exploration of the dose response relationship for tumors such as hepatocellular carcinomas traditionally excluded from the field of conventional radiation therapy. In conclusion, the dose-response relationship remains a sound basis of radiation therapy for many tumors and is a parameter to take into account for further randomized studies. (author)

  8. A meta-analysis on dose-response relationship between night shift work and the risk of breast cancer.

    Science.gov (United States)

    Wang, F; Yeung, K L; Chan, W C; Kwok, C C H; Leung, S L; Wu, C; Chan, E Y Y; Yu, I T S; Yang, X R; Tse, L A

    2013-11-01

    This study aimed to conduct a systematic review to sum up evidence of the associations between different aspects of night shift work and female breast cancer using a dose-response meta-analysis approach. We systematicly searched all cohort and case-control studies published in English on MEDLINE, Embase, PSYCInfo, APC Journal Club and Global Health, from January 1971 to May 2013. We extracted effect measures (relative risk, RR; odd ratio, OR; or hazard ratio, HR) from individual studies to generate pooled results using meta-analysis approaches. A log-linear dose-response regression model was used to evaluate the relationship between various indicators of exposure to night shift work and breast cancer risk. Downs and Black scale was applied to assess the methodological quality of included studies. Ten studies were included in the meta-analysis. A pooled adjusted relative risk for the association between 'ever exposed to night shift work' and breast cancer was 1.19 [95% confidence interval (CI) 1.05-1.35]. Further meta-analyses on dose-response relationship showed that every 5-year increase of exposure to night shift work would correspondingly enhance the risk of breast cancer of the female by 3% (pooled RR = 1.03, 95% CI 1.01-1.05; Pheterogeneity night shifts would result in a 13% (RR = 1.13, 95% CI 1.07-1.21; Pheterogeneity = 0.06) increase in breast cancer risk. This systematic review updated the evidence that a positive dose-response relationship is likely to present for breast cancer with increasing years of employment and cumulative shifts involved in the work.

  9. Interference of intrinsic UV response of LiF:Mg,Ti (Poland) pellets in dose reassessment

    International Nuclear Information System (INIS)

    Bhasin, B.D.; Kalyane, G.N.; Kathuria, S.P.; Sunta, C.M.

    1987-01-01

    The thermoluminescence (TL) behaviour of sintered pellets of LiF:Mg,Ti (Poland) (LiF(P)) is markedly different from that of LiF:Mg,Ti TLD-100 (Harshaw) phosphor as far as their intrinsic responses to ultraviolet (UV) (253.7 nm) radiation are concerned. The intrinsic response of LiF(P) phosphor is very much dependent on the physical form of the phosphor. In addition, it is highly sensitive to any changes in experimental conditions such as the nature of the atmosphere during readout, the pre-heat and the readout history of the phosphor. The high intrinsic UV response (IUVR) of LiF(P) interferes in the dose reassessment by the PTTL (photo-transferred thermoluminescence) technique. Nevertheless, a fortuitous situation exists wherein a PTTL dosimetry peak signal is seen clearly over-riding the IUVR valley at the corresponding point of the glow curve. A procedure to correct for the IUVR interference and to re-estimate the dose by the PTTL technique is described. (author)

  10. Cumulative dose 60Co gamma irradiation effects on AlGaN/GaN Schottky diodes and its area dependence

    Science.gov (United States)

    Sharma, Chandan; Laishram, Robert; Rawal, Dipendra Singh; Vinayak, Seema; Singh, Rajendra

    2018-04-01

    Cumulative dose gamma radiation effects on current-voltage characteristics of GaN Schottky diodes have been investigated. The different area diodes have been fabricated on AlGaN/GaN high electron mobility transistor (HEMT) epi-layer structure grown over SiC substrate and irradiated with a dose up to the order of 104 Gray (Gy). Post irradiation characterization shows a shift in the turn-on voltage and improvement in reverse leakage current. Other calculated parameters include Schottky barrier height, ideality factor and reverse saturation current. Schottky barrier height has been decreased whereas reverse saturation current shows an increase in the value post irradiation with improvement in the ideality factor. Transfer length measurement (TLM) characterization shows an improvement in the contact resistance. Finally, diodes with larger area have more variation in the calculated parameters due to the induced local heating effect.

  11. The Use of the Kurtosis-Adjusted Cumulative Noise Exposure Metric in Evaluating the Hearing Loss Risk for Complex Noise.

    Science.gov (United States)

    Xie, Hong-Wei; Qiu, Wei; Heyer, Nicholas J; Zhang, Mei-Bian; Zhang, Peng; Zhao, Yi-Ming; Hamernik, Roger P

    2016-01-01

    To test a kurtosis-adjusted cumulative noise exposure (CNE) metric for use in evaluating the risk of hearing loss among workers exposed to industrial noises. Specifically, to evaluate whether the kurtosis-adjusted CNE (1) provides a better association with observed industrial noise-induced hearing loss, and (2) provides a single metric applicable to both complex (non-Gaussian [non-G]) and continuous or steady state (Gaussian [G]) noise exposures for predicting noise-induced hearing loss (dose-response curves). Audiometric and noise exposure data were acquired on a population of screened workers (N = 341) from two steel manufacturing plants located in Zhejiang province and a textile manufacturing plant located in Henan province, China. All the subjects from the two steel manufacturing plants (N = 178) were exposed to complex noise, whereas the subjects from textile manufacturing plant (N = 163) were exposed to a G continuous noise. Each subject was given an otologic examination to determine their pure-tone HTL and had their personal 8-hr equivalent A-weighted noise exposure (LAeq) and full-shift noise kurtosis statistic (which is sensitive to the peaks and temporal characteristics of noise exposures) measured. For each subject, an unadjusted and kurtosis-adjusted CNE index for the years worked was created. Multiple linear regression analysis controlling for age was used to determine the relationship between CNE (unadjusted and kurtosis adjusted) and the mean HTL at 3, 4, and 6 kHz (HTL346) among the complex noise-exposed group. In addition, each subject's HTLs from 0.5 to 8.0 kHz were age and sex adjusted using Annex A (ISO-1999) to determine whether they had adjusted high-frequency noise-induced hearing loss (AHFNIHL), defined as an adjusted HTL shift of 30 dB or greater at 3.0, 4.0, or 6.0 kHz in either ear. Dose-response curves for AHFNIHL were developed separately for workers exposed to G and non-G noise using both unadjusted and adjusted CNE as the exposure

  12. Dissolution glow curve in LLD

    International Nuclear Information System (INIS)

    Haverkamp, U.; Wiezorek, C.; Poetter, R.

    1990-01-01

    Lyoluminescence dosimetry is based upon light emission during dissolution of previously irradiated dosimetric materials. The lyoluminescence signal is expressed in the dissolution glow curve. These curves begin, depending on the dissolution system, with a high peak followed by an exponentially decreasing intensity. System parameters that influence the graph of the dissolution glow curve, are, for example, injection speed, temperature and pH value of the solution and the design of the dissolution cell. The initial peak does not significantly correlate with the absorbed dose, it is mainly an effect of the injection. The decay of the curve consists of two exponential components: one fast and one slow. The components depend on the absorbed dose and the dosimetric materials used. In particular, the slow component correlates with the absorbed dose. In contrast to the fast component the argument of the exponential function of the slow component is independent of the dosimetric materials investigated: trehalose, glucose and mannitol. The maximum value, following the peak of the curve, and the integral light output are a measure of the absorbed dose. The reason for the different light outputs of various dosimetric materials after irradiation with the same dose is the differing solubility. The character of the dissolution glow curves is the same following irradiation with photons, electrons or neutrons. (author)

  13. The role of cumulative physical work load in symptomatic knee osteoarthritis – a case-control study in Germany

    Directory of Open Access Journals (Sweden)

    Abolmaali Nasreddin

    2008-07-01

    Full Text Available Abstract Objectives To examine the dose-response relationship between cumulative exposure to kneeling and squatting as well as to lifting and carrying of loads and symptomatic knee osteoarthritis (OA in a population-based case-control study. Methods In five orthopedic clinics and five practices we recruited 295 male patients aged 25 to 70 with radiographically confirmed knee osteoarthritis associated with chronic complaints. A total of 327 male control subjects were recruited. Data were gathered in a structured personal interview. To calculate cumulative exposure, the self-reported duration of kneeling and squatting as well as the duration of lifting and carrying of loads were summed up over the entire working life. Results The results of our study support a dose-response relationship between kneeling/squatting and symptomatic knee osteoarthritis. For a cumulative exposure to kneeling and squatting > 10.800 hours, the risk of having radiographically confirmed knee osteoarthritis as measured by the odds ratio (adjusted for age, region, weight, jogging/athletics, and lifting or carrying of loads is 2.4 (95% CI 1.1–5.0 compared to unexposed subjects. Lifting and carrying of loads is significantly associated with knee osteoarthritis independent of kneeling or similar activities. Conclusion As the knee osteoarthritis risk is strongly elevated in occupations that involve both kneeling/squatting and heavy lifting/carrying, preventive efforts should particularly focus on these "high-risk occupations".

  14. NRPB TLD and dose record keeping service - further progress

    International Nuclear Information System (INIS)

    Greenslade, E.

    1979-01-01

    Various aspects of the National Radiological Protection Board's service are described. An increasing number of UK employers are transferring from film monitors, and record keeping is now provided for both large and small groups of workers. Data entry directly from punched cards prepared by the larger employers has reduced initial costs and therefore carries a reduced registration fee for these users. Computerized dose record keeping allows automatic retrieval of cumulative dose information from any NRPB record of previous employment, thus safeguarding itinerant workers. Warning Dose Reports are issued automatically when cumulative dose totals reach or exceed 60% of a limit, or when a dose rate greater than 0.1 rem per 4 weeks is recorded. Flexibility in wearing period results in dosemeter economy and reduces laboratory work load. High recorded doses can be checked by UV stimulation of both disks to confirm the accuracy of the previous measurement. Employers are provided with a comprehensive and accurate monitoring package, fulfilling HSE requirements and exempting employers from their former responsibility to keep their own comprehensive records. (UK)

  15. Radiation dose response correlation between thermoluminescence and optically stimulated luminescence in quartz

    International Nuclear Information System (INIS)

    Oniya, E.O.; Polymeris, G.S.; Tsirliganis, N.C.; Kitis, G.

    2012-01-01

    The fast, linearly modulated optically stimulated luminescence (LM-OSL) component in quartz is the main dosimetric signal used for the dating applications of this material. Since the blue light stimulation (470 nm, 40 mW cm −2 ) time needed to obtain the fast LM-OSL component is less than 50 s the electron trapping levels responsible for it are still highly populated. In this way an active radiation history is created which could play an important role in the dosimetric characteristics of the fast OSL signal. In the present work the dose response behavior of the fast OSL signal is investigated in quartz samples with an annealed radiation history and quartz samples possessing an artificial radiation history. A computerized curve de-convolution analysis of the LM-OSL curves for 50 s stimulation time showed that it consists of three individual OSL components. The faster component C 1 with peak maximum time around 5 s has a linear dose response in virgin samples, which turns to a slight superlinearity as a function of the artificial radiation history. On the other hand the component C 2 with peak maximum time at 12 s is slightly superlinear which turns into strong superlinearity as a function of artificial radiation history. Finally, component C 3 with peak maximum time at about 45 s is strongly superlinear for both virgin samples and as a function of artificial radiation history. The implications to practical application are discussed. - Highlights: ► The fast OSL component consists of three components. ► The linearity of first fast component does not depend on radiation history. ► The linearity of second and third components depend on radiation history. ► The TL between 180 and 300 °C is the major source of OSL.

  16. Investigation of practical approaches to evaluating cumulative dose for cone beam computed tomography (CBCT) from standard CT dosimetry measurements: a Monte Carlo study.

    Science.gov (United States)

    Abuhaimed, Abdullah; Martin, Colin J; Sankaralingam, Marimuthu; Gentle, David J

    2015-07-21

    A function called Gx(L) was introduced by the International Commission on Radiation Units and Measurements (ICRU) Report-87 to facilitate measurement of cumulative dose for CT scans within long phantoms as recommended by the American Association of Physicists in Medicine (AAPM) TG-111. The Gx(L) function is equal to the ratio of the cumulative dose at the middle of a CT scan to the volume weighted CTDI (CTDIvol), and was investigated for conventional multi-slice CT scanners operating with a moving table. As the stationary table mode, which is the basis for cone beam CT (CBCT) scans, differs from that used for conventional CT scans, the aim of this study was to investigate the extension of the Gx(L) function to CBCT scans. An On-Board Imager (OBI) system integrated with a TrueBeam linac was simulated with Monte Carlo EGSnrc/BEAMnrc, and the absorbed dose was calculated within PMMA, polyethylene (PE), and water head and body phantoms using EGSnrc/DOSXYZnrc, where the body PE body phantom emulated the ICRU/AAPM phantom. Beams of width 40-500 mm and beam qualities at tube potentials of 80-140 kV were studied. Application of a modified function of beam width (W) termed Gx(W), for which the cumulative dose for CBCT scans f (0) is normalized to the weighted CTDI (CTDIw) for a reference beam of width 40 mm, was investigated as a possible option. However, differences were found in Gx(W) with tube potential, especially for body phantoms, and these were considered to be due to differences in geometry between wide beams used for CBCT scans and those for conventional CT. Therefore, a modified function Gx(W)100 has been proposed, taking the form of values of f (0) at each position in a long phantom, normalized with respect to dose indices f 100(150)x measured with a 100 mm pencil ionization chamber within standard 150 mm PMMA phantoms, using the same scanning parameters, beam widths and positions within the phantom. f 100(150)x averages the dose resulting from

  17. Experimental determination of the lateral dose response functions of detectors to be applied in the measurement of narrow photon-beam dose profiles.

    Science.gov (United States)

    Poppinga, D; Meyners, J; Delfs, B; Muru, A; Harder, D; Poppe, B; Looe, H K

    2015-12-21

    This study aims at the experimental determination of the detector-specific 1D lateral dose response function K(x) and of its associated rotational symmetric counterpart K(r) for a set of high-resolution detectors presently used in narrow-beam photon dosimetry. A combination of slit-beam, radiochromic film, and deconvolution techniques served to accomplish this task for four detectors with diameters of their sensitive volumes ranging from 1 to 2.2 mm. The particular aim of the experiment was to examine the existence of significant negative portions of some of these response functions predicted by a recent Monte-Carlo-simulation (Looe et al 2015 Phys. Med. Biol. 60 6585-607). In a 6 MV photon slit beam formed by the Siemens Artiste collimation system and a 0.5 mm wide slit between 10 cm thick lead blocks serving as the tertiary collimator, the true cross-beam dose profile D(x) at 3 cm depth in a large water phantom was measured with radiochromic film EBT3, and the detector-affected cross-beam signal profiles M(x) were recorded with a silicon diode, a synthetic diamond detector, a miniaturized scintillation detector, and a small ionization chamber. For each detector, the deconvolution of the convolution integral M(x)  =  K(x)  ∗  D(x) served to obtain its specific 1D lateral dose response function K(x), and K(r) was calculated from it. Fourier transformations and back transformations were performed using function approximations by weighted sums of Gaussian functions and their analytical transformation. The 1D lateral dose response functions K(x) of the four types of detectors and their associated rotational symmetric counterparts K(r) were obtained. Significant negative curve portions of K(x) and K(r) were observed in the case of the silicon diode and the diamond detector, confirming the Monte-Carlo-based prediction (Looe et al 2015 Phys. Med. Biol. 60 6585-607). They are typical for the perturbation of the secondary electron field by a detector with

  18. Radiation-induced rectal complications are not influenced by age: a dose fractionation study in the rat.

    Science.gov (United States)

    van den Aardweg, Gerard J M J; Olofsen-van Acht, Manouk J J; van Hooije, Christel M C; Levendag, Peter C

    2003-05-01

    Radiation-induced complications of the rectum are an important dose-limiting factor in radiotherapy of pelvic malignancies. In general, animal studies demonstrated no differences in acute and late normal tissue toxicity with age, but little is known about rectal complications in relation to age. For this purpose, an extensive histological and dose fractionation study was carried out on the rectum of young (12 weeks) and older (77-80 weeks) rats. In this paper, the results of dose fractionation are presented in relation to age at the time of irradiation. Young and older animals were irradiated with single and fractionated doses. After irradiation, rectal complications could lead to occlusion and stenosis, eventually resulting in the clinical symptoms of a megacolon and a possible fistula. For each dose group, cumulative survival rates were obtained with Kaplan-Meier analysis, from which dose-effect curves and the associated LD(50) values for a megacolon/fistula were calculated. The majority of responders died between 8 and 24 weeks after irradiation, irrespective of age. For both age groups, only the fractionation data showed a reduction in the mean latency with increasing dose. In the older age group, 39% of the responders developed a fistula compared to 26% for the younger animals. The LD(50) values increased from around 30 Gy after single doses to nearly 65 Gy after 10 fractions. The increases in LD(50) values with the number of fractions were independent of the age of the rats. For each of the dose fractionation schedules, log-rank testing indicated no significant differences in cumulative survival rates between younger and older animals (P > 0.10). The high alpha/beta ratios obtained for both the young and older animals strongly suggested that the late rectal complications were a consequence of early epithelial injury. Associated histological findings indicated that blood vessel damage, which was already evident at a high incidence at 4 weeks after irradiation

  19. CARCINOGENIC EFFECTS OF LOW DOSES OF IONIZING RADIATION

    Science.gov (United States)

    Carcinogenic Effects of Low Doses of Ionizing RadiationR Julian Preston, Environmental Carcinogenesis Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711The form of the dose-response curve for radiation-induced cancers, particu...

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

    International Nuclear Information System (INIS)

    Perry, K.A.; Szekely, J.G.

    1983-09-01

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

  1. Defining a dose-response relationship for prostate external beam radiotherapy

    International Nuclear Information System (INIS)

    Trada, Yuvnik; Plank, Ash; Martin, Jarad

    2013-01-01

    We aimed to quantify a relationship between radiotherapy dose and freedom from biochemical failure (FFBF) in low- and intermediate-risk prostate cancer. To reduce confounding we used data with a standardised end–point, mature follow-up, low competing risk of metastatic failure, conventional fractionation and separate reporting for outcomes with hormonal therapy (HT). A systematic review of the literature was carried out. Studies that reported the use of radiotherapy alone in 1.8–2Gy fractions in low- and intermediate-risk prostate cancer were included. The primary end–point was Phoenix definition 5-year FFBF. A logistic regression was used to quantify the dose–response relationship. Data from eight studies with 3037 patients met the inclusion criteria. The data from 810 low-risk patients and 2245 intermediate-risk patients were analysed. A strong association between radiotherapy dose and FFBF was found in low- and intermediate-risk patients managed with radiotherapy alone. In low-risk patients not treated with HT the dose required to achieve 50% biochemical tumour control (TCD 50 ) is 52.0 Gy and the slope of the dose–response curve at TCD 50 (γ 50 ) is 2.1%/Gy. At 78Gy this represented a FFBF of 90.3%. In intermediate-risk patients not treated with HT the TCD 50 is 64.7Gy and γ 50 is 3.2%/Gy. At 78 Gy this translated into a FFBF of 84.3%. HT had a small effect for low-risk patients and an inconsistent effect for intermediate-risk men. A strong association was found between radiation dose and biochemical outcome in both low- and intermediate-risk patients. Standardised reporting of results from future studies will make future analyses more robust.

  2. Architecture of a minimal signaling pathway explains the T-cell response to a 1 million-fold variation in antigen affinity and dose

    Science.gov (United States)

    Lever, Melissa; Lim, Hong-Sheng; Kruger, Philipp; Nguyen, John; Trendel, Nicola; Abu-Shah, Enas; Maini, Philip Kumar; van der Merwe, Philip Anton

    2016-01-01

    T cells must respond differently to antigens of varying affinity presented at different doses. Previous attempts to map peptide MHC (pMHC) affinity onto T-cell responses have produced inconsistent patterns of responses, preventing formulations of canonical models of T-cell signaling. Here, a systematic analysis of T-cell responses to 1 million-fold variations in both pMHC affinity and dose produced bell-shaped dose–response curves and different optimal pMHC affinities at different pMHC doses. Using sequential model rejection/identification algorithms, we identified a unique, minimal model of cellular signaling incorporating kinetic proofreading with limited signaling coupled to an incoherent feed-forward loop (KPL-IFF) that reproduces these observations. We show that the KPL-IFF model correctly predicts the T-cell response to antigen copresentation. Our work offers a general approach for studying cellular signaling that does not require full details of biochemical pathways. PMID:27702900

  3. Radiation Dose-Response Relationships and Risk Assessment

    International Nuclear Information System (INIS)

    Strom, Daniel J.

    2005-01-01

    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

  4. Kinetic and dose dependencies of the SOS-induction in E.coli K-12 (uvrA) cells exposed to different UV doses

    International Nuclear Information System (INIS)

    Komova, O.V.; Kandiano, E.S.; Malavina, G.; )

    2000-01-01

    Kinetic and dose dependencies of the SOS-induction in E. coli (uvrA) cells exposed to UV light were investigated. below 2 J/m 2 the rate of the SOS-induction increased with dose. Maximal level of the SOS-response was proportional to the UV dose. Pyrimidine dimers were necessary for the induction. In the dose range 2-10 J/m 2 the rate of SOS-induction decreased with dose. Dose-maximum response curve was non-linear. Pyrimidine dimers were not required for the induction. nature of the molecular events leading to the SOS-induction at low and high doses was discussed [ru

  5. Estimating a population cumulative incidence under calendar time trends

    DEFF Research Database (Denmark)

    Hansen, Stefan N; Overgaard, Morten; Andersen, Per K

    2017-01-01

    BACKGROUND: The risk of a disease or psychiatric disorder is frequently measured by the age-specific cumulative incidence. Cumulative incidence estimates are often derived in cohort studies with individuals recruited over calendar time and with the end of follow-up governed by a specific date...... by calendar time trends, the total sample Kaplan-Meier and Aalen-Johansen estimators do not provide useful estimates of the general risk in the target population. We present some alternatives to this type of analysis. RESULTS: We show how a proportional hazards model may be used to extrapolate disease risk...... estimates if proportionality is a reasonable assumption. If not reasonable, we instead advocate that a more useful description of the disease risk lies in the age-specific cumulative incidence curves across strata given by time of entry or perhaps just the end of follow-up estimates across all strata...

  6. Phase response curves for models of earthquake fault dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Franović, Igor, E-mail: franovic@ipb.ac.rs [Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Kostić, Srdjan [Institute for the Development of Water Resources “Jaroslav Černi,” Jaroslava Černog 80, 11226 Belgrade (Serbia); Perc, Matjaž [Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, SI-2000 Maribor (Slovenia); CAMTP—Center for Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Klinshov, Vladimir [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation); Nekorkin, Vladimir [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation); University of Nizhny Novgorod, 23 Prospekt Gagarina, 603950 Nizhny Novgorod (Russian Federation); Kurths, Jürgen [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation); Potsdam Institute for Climate Impact Research, 14412 Potsdam (Germany); Institute of Physics, Humboldt University Berlin, 12489 Berlin (Germany)

    2016-06-15

    We systematically study effects of external perturbations on models describing earthquake fault dynamics. The latter are based on the framework of the Burridge-Knopoff spring-block system, including the cases of a simple mono-block fault, as well as the paradigmatic complex faults made up of two identical or distinct blocks. The blocks exhibit relaxation oscillations, which are representative for the stick-slip behavior typical for earthquake dynamics. Our analysis is carried out by determining the phase response curves of first and second order. For a mono-block fault, we consider the impact of a single and two successive pulse perturbations, further demonstrating how the profile of phase response curves depends on the fault parameters. For a homogeneous two-block fault, our focus is on the scenario where each of the blocks is influenced by a single pulse, whereas for heterogeneous faults, we analyze how the response of the system depends on whether the stimulus is applied to the block having a shorter or a longer oscillation period.

  7. Phase response curves for models of earthquake fault dynamics

    International Nuclear Information System (INIS)

    Franović, Igor; Kostić, Srdjan; Perc, Matjaž; Klinshov, Vladimir; Nekorkin, Vladimir; Kurths, Jürgen

    2016-01-01

    We systematically study effects of external perturbations on models describing earthquake fault dynamics. The latter are based on the framework of the Burridge-Knopoff spring-block system, including the cases of a simple mono-block fault, as well as the paradigmatic complex faults made up of two identical or distinct blocks. The blocks exhibit relaxation oscillations, which are representative for the stick-slip behavior typical for earthquake dynamics. Our analysis is carried out by determining the phase response curves of first and second order. For a mono-block fault, we consider the impact of a single and two successive pulse perturbations, further demonstrating how the profile of phase response curves depends on the fault parameters. For a homogeneous two-block fault, our focus is on the scenario where each of the blocks is influenced by a single pulse, whereas for heterogeneous faults, we analyze how the response of the system depends on whether the stimulus is applied to the block having a shorter or a longer oscillation period.

  8. Radiation doses and cause-specific mortality among workers at a nuclear materials fabrication plant

    International Nuclear Information System (INIS)

    Checkoway, H.; Pearce, N.; Crawford-Brown, D.J.; Cragle, D.L.

    1988-01-01

    A historical cohort mortality study was conducted among 6781 white male employees from a nuclear weapons materials fabrication plant for the years 1947-1979. Exposures of greatest concern are alpha and gamma radiation emanating primarily from insoluble uranium compounds. Among monitored workers, the mean cumulative alpha radiation dose to the lung was 8.21 rem, and the mean cumulative external whole body penetrating dose from gamma radiation was 0.96 rem. Relative to US white males, the cohort experienced mortality deficits from all causes combined, cardiovascular diseases, and from most site-specific cancers. Mortality excesses of lung and brain and central nervous system cancers were seen from comparisons with national and state rates. Dose-response trends were detected for lung cancer mortality with respect to cumulative alpha and gamma radiation, with the most pronounced trend occurring for gamma radiation among workers who received greater than or equal to 5 rem of alpha radiation. These trends diminished in magnitude when a 10-year latency assumption was applied. Under a zero-year latency assumption, the rate ratio for lung cancer mortality associated with joint exposure of greater than or equal to 5 versus less than 1 rem of both types of radiation is 4.60 (95% confidence limits (CL) 0.91, 23.35), while the corresponding result, assuming a 10-year latency, is 3.05 (95% CL 0.37, 24.83). While these rate ratios, which are based on three and one death, respectively, lack statistical precision, the observed dose-response trends indicate potential carcinogenic effects to the lung of relatively low-dose radiation. There are no dose-response trends for mortality from brain and central nervous system cancers

  9. Health effects of low doses at low dose rates: dose-response relationship modeling in a cohort of workers of the nuclear industry; Effets sanitaires des faibles doses a faibles debits de dose: modelisation de la relation dose-reponse dans une cohorte de travailleurs du nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Metz-Flamant, Camille

    2011-09-19

    The aim of this thesis is to contribute to a better understanding of the health effects of chronic external low doses of ionising radiation. This work is based on the French cohort of CEA-AREVA NC nuclear workers. The mains stages of this thesis were (1) conducting a review of epidemiological studies on nuclear workers, (2) completing the database and performing a descriptive analysis of the cohort, (3) quantifying risk by different statistical methods and (4) modelling the exposure-time-risk relationship. The cohort includes monitored workers employed more than one year between 1950 and 1994 at CEA or AREVA NC companies. Individual annual external exposure, history of work, vital status and causes of death were reconstructed for each worker. Standardized mortality ratios using French national mortality rates as external reference were computed. Exposure-risk analysis was conducted in the cohort using the linear excess relative risk model, based on both Poisson regression and Cox model. Time dependent modifying factors were investigated by adding an interaction term in the model or by using exposure time windows. The cohort includes 36, 769 workers, followed-up until age 60 in average. During the 1968- 2004 period, 5, 443 deaths, 2, 213 cancers, 62 leukemia and 1, 314 cardiovascular diseases were recorded. Among the 57% exposed workers, the mean cumulative dose was 21.5 milli-sieverts (mSv). A strong Healthy Worker Effect is observed in the cohort. Significant elevated risks of pleura cancer and melanoma deaths were observed in the cohort but not associated with dose. No significant association was observed with solid cancers, lung cancer and cardiovascular diseases. A significant dose-response relationship was observed for leukemia excluding chronic lymphatic leukemia, mainly for doses received less than 15 years before and for yearly dose rates higher than 10 mSv. This PhD work contributes to the evaluation of risks associated to chronic external radiation

  10. Droplet-based microfluidics for dose-response assay of enzyme inhibitors by electrochemical method.

    Science.gov (United States)

    Gu, Shuqing; Lu, Youlan; Ding, Yaping; Li, Li; Zhang, Fenfen; Wu, Qingsheng

    2013-09-24

    A simple but robust droplet-based microfluidic system was developed for dose-response enzyme inhibition assay by combining concentration gradient generation method with electrochemical detection method. A slotted-vials array and a tapered tip capillary were used for reagents introduction and concentration gradient generation, and a polydimethylsiloxane (PDMS) microfluidic chip integrated with microelectrodes was used for droplet generation and electrochemical detection. Effects of oil flow rate and surfactant on electrochemical sensing were investigated. This system was validated by measuring dose-response curves of three types of acetylcholinesterase (AChE) inhibitors, including carbamate pesticide, organophosphorus pesticide, and therapeutic drugs regulating Alzheimer's disease. Carbaryl, chlorpyrifos, and tacrine were used as model analytes, respectively, and their IC50 (half maximal inhibitory concentration) values were determined. A whole enzyme inhibition assay was completed in 6 min, and the total consumption of reagents was less than 5 μL. This microfluidic system is applicable to many biochemical reactions, such as drug screening and kinetic studies, as long as one of the reactants or products is electrochemically active. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Stochastic evaluation of the dynamic response and the cumulative damage of nuclear power plant piping

    International Nuclear Information System (INIS)

    Suzuki, Kohei; Aoki, Shigeru; Hanaoka, Masaaki

    1981-01-01

    This report deals with a fundamental study concerning an evaluation of uncertainties of the nuclear piping response and cumulative damage under excess-earthquake loadings. The main purposes of this study cover following several problems. (1) Experimental estimation analysis of the uncertainties concerning the dynamic response and the cumulative failure by using piping test model. (2) Numerical simulation analysis by Monte Carlo method under the assumption that relation between restoring force and deformation is characterized by perfectly elasto-plastic one. (Checking the mathematical model.) (3) Development of the conventional uncertainty estimating method by introducing a perturbation technique based on an appropriate equivalently linearized approach. (Checking the estimation technique.) (4) An application of this method to more realistical cases. Through above mentioned procedures some important results are obtained as follows; First, fundamental statistical properties of the natural frequencies and the number of cycle to failure crack initiation are evaluated. Second, the effect of the frequency fluctuation and the yielding fluctuation are estimated and examined through Monte Carlo simulation technique. It has become clear that the yielding fluctuation gives significant effect on the piping power response up to its failure initiation. Finally some results through proposed perturbation technique are discussed. Statistical properties estimated coincide fairly well with those through numerical simulation. (author)

  12. Quartz luminescence response to a mixed alpha-beta field: Investigations on Romanian loess

    International Nuclear Information System (INIS)

    Constantin, Daniela; Jain, Mayank; Murray, Andrew S.; Buylaert, Jan-Pieter; Timar-Gabor, Alida

    2015-01-01

    Previous SAR-OSL dating studies using quartz extracted from Romanian and Serbian loess samples report SAR-OSL dose–response curves on fine grained (4–11 μm) quartz that grow to much higher doses compared to those of coarse-grained (63–90, 90–125, 125–180 μm) quartz. Furthermore, quartz SAR-OSL laboratory dose response curves do not reflect the growth of the OSL signal in nature. A main difference in coarse- and fine-grained quartz dating lies in the alpha irradiation history, but the effect of mixed alpha-beta fields has so far received little attention. In the present study we investigate whether the alpha dose experienced by fine grains over geological cycles of irradiation and bleaching may have an effect on the saturation characteristics of the laboratory dose response. By applying time resolved optically stimulated luminescence we confirm that the OSL signals induced in quartz by alpha and beta radiation follow the same recombination path. We also show that a mixed alpha-beta dose response reproduces the beta dose response only up to about 800 Gy. Assuming an a-value of 0.04 we have shown that laboratory alpha and beta dose response curves overlap up to effective alpha doses of ∼50 Gy. Based on these results, we conclude that exposure of fine grains to alpha radiation during burial and transport cycles prior to deposition, as well exposure to the mixed radiation field experienced during burial are not responsible for the age discrepancies previously reported on fine and coarse grained quartz extracted from Romanian and Serbian loess. - Highlights: • Prior alpha irradiation history does not influence the laboratory beta growth curves. • Alpha and beta induced photon emissions in quartz follow the same recombination path. • Laboratory alpha and beta growth curves overlap up to total alpha doses of ∼1250 Gy. • Mixed alpha-beta growth curves reproduce the beta dose response curves up to ∼800 Gy. • Mixed radiation field is not

  13. Mean inactivation dose: a useful concept for intercomparison of human cell survival curves

    International Nuclear Information System (INIS)

    Fertil, B.; Dertinger, H.; Courdi, A.; Malaise, E.P.

    1984-01-01

    The mean inactivation dose (anti D) is calculated for published in vitro survival curves obtained from cell lines of both normal and neoplastic human tissues. Cells belonging to different histological categories (melanomas, carcinomas, etc.) are shown to be characterized by distinct values of anti D which are related to the clinical radiosensitivity of tumors from these categories. Compared to other ways of representing in vitro radiosensitivity, e.g., by the multitarget parameters D 8 and n, the parameter anti D has several specific advantages

  14. In-plane impulse response of a curved bar with varying cross-section

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin; Miyashita, Yasushi.

    1984-01-01

    The vibration problem of a curved bar, of which the center line is represented with a plane curve, is important for the aseismatic design of the piping system and structures in chemical and nuclear plants. The dynamic response problem of an in-plane curved bar has not been sufficiently examined. In this study, the in-plane impact response of an in-plane curved bar having varying cross section when impact load acts in the direction of the center of curvature was analyzed. First, the Lagrangian of a curved bar with varying cross section when general exciting distributed load acts in the direction of the center of curvature along the center line was determined by the classic theory, and from its stationary condition, the equations of motion and boundary conditions were derived. Next, the equations of motion were analyzed by eigen-function development method. In the example of numerical calculation, the variation of displacement and bending moment in course of time when stepwise concentrated impact load acts on a both ends fixed symmetric semi-elliptic arc bar was determined. Besides, the change of response due to the change of cross section and the change of the point of impact load application was clarified. Displacement and bending moment varied at a certain period with static value at the center. (Kako, I.)

  15. Non-Chemical Stressors and Cumulative Risk Assessment: An Overview of Current Initiatives and Potential Air Pollutant Interactions

    Science.gov (United States)

    Lewis, Ari S.; Sax, Sonja N.; Wason, Susan C.; Campleman, Sharan L.

    2011-01-01

    Regulatory agencies are under increased pressure to consider broader public health concerns that extend to multiple pollutant exposures, multiple exposure pathways, and vulnerable populations. Specifically, cumulative risk assessment initiatives have stressed the importance of considering both chemical and non-chemical stressors, such as socioeconomic status (SES) and related psychosocial stress, in evaluating health risks. The integration of non-chemical stressors into a cumulative risk assessment framework has been largely driven by evidence of health disparities across different segments of society that may also bear a disproportionate risk from chemical exposures. This review will discuss current efforts to advance the field of cumulative risk assessment, highlighting some of the major challenges, discussed within the construct of the traditional risk assessment paradigm. Additionally, we present a summary of studies of potential interactions between social stressors and air pollutants on health as an example of current research that supports the incorporation of non-chemical stressors into risk assessment. The results from these studies, while suggestive of possible interactions, are mixed and hindered by inconsistent application of social stress indicators. Overall, while there have been significant advances, further developments across all of the risk assessment stages (i.e., hazard identification, exposure assessment, dose-response, and risk characterization) are necessary to provide a scientific basis for regulatory actions and effective community interventions, particularly when considering non-chemical stressors. A better understanding of the biological underpinnings of social stress on disease and implications for chemical-based dose-response relationships is needed. Furthermore, when considering non-chemical stressors, an appropriate metric, or series of metrics, for risk characterization is also needed. Cumulative risk assessment research will benefit

  16. A study on dose response of NIPAM-based dosimeter used in radiotherapy

    International Nuclear Information System (INIS)

    Hsieh, B.T.; Wu, J.; Chang, Y.J.; Han, R.P.; Hsieh, L.L.; Chang, C.J.

    2011-01-01

    The newly manufactured N-isopropylacrylamide (NIPAM) polymer gel is composed of four components, i.e., gelatin, monomer (NIPAM), crosslinker (N,N'-methylenebisacrylamide, Bis), and antioxidant (tetrakis hydroxymethyl phosphonium chloride, THPC). In this study, we investigated the effects of gel composition on the dose response of NIPAM polymer gel. A statistical experiment to analyze the contribution of each composition to the linearity and sensitivity of NIPAM gel was performed. Results indicate that the amount of gelatin, NIPAM (15.17%), Bis, and THPC have dominant effects on the sensitivity of the gel, with contributions of 59.73, 15.17, 10.64, and 14.45%, respectively. The amount of gelatin and Bis mainly affected the linearity of the gel, with contributions of 44.70 and 50.99%, respectively. The linearity of most compositions of the gel was greater than 0.99 when (%C)/(%T) was lower than 8.0. Optimal (%C)/(%T) for higher sensitivity should be in the range of 4-9. The temporal stability experiment showed that the dose response curve attained stability at about 5 h after irradiation and persisted up to 3 months. (author)

  17. Spectral calibration of EBT3 and HD-V2 radiochromic film response at high dose using 20 MeV proton beams

    Science.gov (United States)

    Feng, Yiwei; Tiedje, Henry F.; Gagnon, Katherine; Fedosejevs, Robert

    2018-04-01

    Radiochromic film is used extensively in many medical, industrial, and scientific applications. In particular, the film is used in analysis of proton generation and in high intensity laser-plasma experiments where very high dose levels can be obtained. The present study reports calibration of the dose response of Gafchromic EBT3 and HD-V2 radiochromic films up to high exposure densities. A 2D scanning confocal densitometer system is employed to carry out accurate optical density measurements up to optical density 5 on the exposed films at the peak spectral absorption wavelengths. Various wavelengths from 400 to 740 nm are also scanned to extend the practical dose range of such films by measuring the response at wavelengths removed from the peak response wavelengths. Calibration curves for the optical density versus exposure dose are determined and can be used for quantitative evaluation of measured doses based on the measured optical densities. It was found that blue and UV wavelengths allowed the largest dynamic range though at some trade-off with overall accuracy.

  18. Dose estimation from residual and fallout radioactivity, 1

    International Nuclear Information System (INIS)

    Takeshita, Kenji

    1975-01-01

    External dose rates and cumulative doses for early entrants from areal surveys and simulated experiments are reviewed. The average cumulative doses to infinity at the hypocenters were 101 rad in Hiroshima and 32 rad in Nagasaki, with a variation of about 60 percent. Radioactive fallout areas nearly matched the ''black rain'' areas in Nagasaki and in Hiroshima. Radioactivity in the fallout areas was affected by radioactive decay and by the leaching and dissipation by rains. Considering these factors, the cumulative dose to infinity in the fallout area of Hiroshima was estimated to be 13 rad, excluding internal radiation doses from inhaled and ingested radionuclides. Attempts to estimate radiation dose from internally deposited radionuclides are also described. (auth.)

  19. Estimation of absorbed dose for 2-[F-18]fluoro-2-deoxy-d- glucose using whole-body positron emission tomography and magnetic resonance imaging

    International Nuclear Information System (INIS)

    Deloar, H.M.; Fujiwara, Takehiko; Shidahara, Miho; Nakamura, Takashi; Watabe, Hiroshi; Narita, Yuichiro; Itoh, Masatoshi; Miyake, Masayasu; Watanuki, Shoichi

    1998-01-01

    The purpose of this study was to measure the cumulated activity and absorbed dose in organs after i.v. administration of 18 F-FDG using whole-body PET and MRI. Whole-body dynamic emission scans for 18 F-FDG were performed in six normal volunteers after transmission scans. The total activity of a source organ was obtained from the activity concentration of the organ measured by whole-body PET and the volume of that organ measured by whole-body T1-weighted MRI. The cumulated activity of each source organ was calculated from the time-activity curve. Absorbed doses to the individuals were estimated by the MIRD (medical internal radiation dosimetry) method. Another calculation of cumulated activities and absorbed doses was performed using the organ volumes from the MIRD phantom and the ''Japanese reference man'' to investigate the discrepancy of actual individual results against the phantom results. The cumulated activities of 18 source organs were calculated, and absorbed doses of 27 target organs estimated. Among the target organs, bladder wall, brain and kidney received the highest doses for the above three sets of organ volumes. Using measured individual organ volumes, the average absorbed doses for those organs were found to be 3.1 x 10 -1 , 3.7 x 10 -2 and 2.8 x 10 -2 mGy/MBq, respectively. The mean effective doses in this study for individuals of average body weight (64.5 kg) and the MIRD phantom of 70 kg were the same, i.e. 2.9 x 10 -2 mSv/MBq, while for the Japanese reference man of 60 kg the effective dose was 2.1 x 10 -2 mSv/MBq. The results for measured organ volumes derived from MRI were comparable to those obtained for organ volumes from the MIRD phantom. Although this study considered 18 F-FDG, combined use of whole-body PET and MRI might be quite effective for improving the accuracy of estimations of the cumulated activity and absorbed dose of positron-labelled radiopharmaceuticals.(orig./MG) (orig.)

  20. Statistical and low dose response

    International Nuclear Information System (INIS)

    Thorson, M.R.; Endres, G.W.R.

    1981-01-01

    The low dose response and the lower limit of detection of the Hanford dosimeter depend upon may factors, including the energy of the radiation, whether the exposure is to be a single radiation or mixed fields, annealing cycles, environmental factors, and how well various batches of TLD materials are matched in the system. A careful statistical study and sensitivity analysis were performed to determine how these factors influence the response of the dosimeter system. Estimates have been included in this study of the standard deviation of calculated dose for various mixed field exposures from 0 to 1000 mrem

  1. Brachytherapy dose measurements in heterogeneous tissues

    International Nuclear Information System (INIS)

    Paiva F, G.; Luvizotto, J.; Salles C, T.; Guimaraes A, P. C.; Dalledone S, P. de T.; Yoriyaz, H.; Rubo, R.

    2014-08-01

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  2. Brachytherapy dose measurements in heterogeneous tissues

    Energy Technology Data Exchange (ETDEWEB)

    Paiva F, G.; Luvizotto, J.; Salles C, T.; Guimaraes A, P. C.; Dalledone S, P. de T.; Yoriyaz, H. [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil); Rubo, R., E-mail: gabrielpaivafonseca@gmail.com [Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, 05403-900 Sao Paulo (Brazil)

    2014-08-15

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  3. The injury and cumulative effects on human skin by UV exposure from artificial fluorescence emission.

    Science.gov (United States)

    Tian, Yan; Liu, Wei; Niu, TianHui; Dai, CaiHong; Li, Xiaoxin; Cui, Caijuan; Zhao, Xinyan; E, Yaping; Lu, Hui

    2014-01-01

    The injury and cumulative effects of UV emission from fluorescence lamp were studied. UV intensity from fluorescence lamp was measured, and human skin samples (hips, 10 volunteers) were exposed to low-dose UV irradiation (three times per week for 13 consecutive weeks). Three groups were examined: control group without UV radiation; low-dose group with a cumulative dose of 50 J cm(-2) which was equivalent to irradiation of the face during indoor work for 1.5 years; and high-dose group with 1000 J cm(-2) cumulative dose equivalent to irradiation of the face during outdoor activities for 1 year. Specific indicators were measured before and after UVA irradiation. The findings showed that extending the low-dose UVA exposure decreased the skin moisture content and increased the transepidermal water loss as well as induced skin color changes (decreased L* value, increased M index). Furthermore, irradiated skin showed an increased thickness of cuticle and epidermis, skin edema, light color and unclear staining collagen fibers in the dermis, and elastic fiber fragmentation. In addition, MMP-1, p53 and SIRT1 expression was also increased. Long-term exposure of low-dose UVA radiation enhanced skin photoaging. The safety of the fluorescent lamp needs our attention. © 2014 The American Society of Photobiology.

  4. A new form of the calibration curve in radiochromic dosimetry. Properties and results

    International Nuclear Information System (INIS)

    Tamponi, Matteo; Bona, Rossana; Poggiu, Angela; Marini, Piergiorgio

    2016-01-01

    Purpose: This work describes a new form of the calibration curve for radiochromic dosimetry that depends on one fit parameter. Some results are reported to show that the new curve performs as well as those previously used and, more importantly, significantly reduces the dependence on the lot of films, the film orientation on the scanner, and the time after exposure. Methods: The form of the response curve makes use of the net optical densities ratio against the dose and has been studied by means of the Beer–Lambert law and a simple modeling of the film. The new calibration curve has been applied to EBT3 films exposed at 6 and 15 MV energy beams of linear accelerators and read-out in transmission mode by means of a flatbed color scanner. Its performance has been compared to that of two established forms of the calibration curve, which use the optical density and the net optical density against the dose. Four series of measurements with four lots of EBT3 films were used to evaluate the precision, accuracy, and dependence on the time after exposure, orientation on the scanner and lot of films. Results: The new calibration curve is roughly subject to the same dose uncertainty, about 2% (1 standard deviation), and has the same accuracy, about 1.5% (dose values between 50 and 450 cGy), as the other calibration curves when films of the same lot are used. Moreover, the new calibration curve, albeit obtained from only one lot of film, shows a good agreement with experimental data from all other lots of EBT3 films used, with an accuracy of about 2% and a relative dose precision of 2.4% (1 standard deviation). The agreement also holds for changes of the film orientation and of the time after exposure. Conclusions: The dose accuracy of this new form of the calibration curve is always equal to or better than those obtained from the two types of curves previously used. The use of the net optical densities ratio considerably reduces the dependence on the lot of films, the

  5. A new form of the calibration curve in radiochromic dosimetry. Properties and results

    Energy Technology Data Exchange (ETDEWEB)

    Tamponi, Matteo, E-mail: mtamponi@aslsassari.it; Bona, Rossana; Poggiu, Angela; Marini, Piergiorgio [Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari 07100 (Italy)

    2016-07-15

    Purpose: This work describes a new form of the calibration curve for radiochromic dosimetry that depends on one fit parameter. Some results are reported to show that the new curve performs as well as those previously used and, more importantly, significantly reduces the dependence on the lot of films, the film orientation on the scanner, and the time after exposure. Methods: The form of the response curve makes use of the net optical densities ratio against the dose and has been studied by means of the Beer–Lambert law and a simple modeling of the film. The new calibration curve has been applied to EBT3 films exposed at 6 and 15 MV energy beams of linear accelerators and read-out in transmission mode by means of a flatbed color scanner. Its performance has been compared to that of two established forms of the calibration curve, which use the optical density and the net optical density against the dose. Four series of measurements with four lots of EBT3 films were used to evaluate the precision, accuracy, and dependence on the time after exposure, orientation on the scanner and lot of films. Results: The new calibration curve is roughly subject to the same dose uncertainty, about 2% (1 standard deviation), and has the same accuracy, about 1.5% (dose values between 50 and 450 cGy), as the other calibration curves when films of the same lot are used. Moreover, the new calibration curve, albeit obtained from only one lot of film, shows a good agreement with experimental data from all other lots of EBT3 films used, with an accuracy of about 2% and a relative dose precision of 2.4% (1 standard deviation). The agreement also holds for changes of the film orientation and of the time after exposure. Conclusions: The dose accuracy of this new form of the calibration curve is always equal to or better than those obtained from the two types of curves previously used. The use of the net optical densities ratio considerably reduces the dependence on the lot of films, the

  6. Evaluating Pharmacokinetic and Pharmacodynamic Interactions with Computational Models in Supporting Cumulative Risk Assessment

    Science.gov (United States)

    Tan, Yu-Mei; Clewell, Harvey; Campbell, Jerry; Andersen, Melvin

    2011-01-01

    Simultaneous or sequential exposure to multiple chemicals may cause interactions in the pharmacokinetics (PK) and/or pharmacodynamics (PD) of the individual chemicals. Such interactions can cause modification of the internal or target dose/response of one chemical in the mixture by other chemical(s), resulting in a change in the toxicity from that predicted from the summation of the effects of the single chemicals using dose additivity. In such cases, conducting quantitative cumulative risk assessment for chemicals present as a mixture is difficult. The uncertainties that arise from PK interactions can be addressed by developing physiologically based pharmacokinetic (PBPK) models to describe the disposition of chemical mixtures. Further, PK models can be developed to describe mechanisms of action and tissue responses. In this article, PBPK/PD modeling efforts conducted to investigate chemical interactions at the PK and PD levels are reviewed to demonstrate the use of this predictive modeling framework in assessing health risks associated with exposures to complex chemical mixtures. PMID:21655141

  7. Preliminary mortality survey from 1973 to 1977 of Japanese radiological technologists and analyses of the association of mortality with cumulative doses

    International Nuclear Information System (INIS)

    Aoyama, Takashi; Ishizaka, Masatsuna; Yamamoto, Yoichi; Kano, Eiichi; Nikaido, Osamu.

    1981-01-01

    The Japan Association of Radiologic Technologists reported that, from 1941 to 1978, 395 deaths occurred among Japanese radiological technologists who belong to the association. Using these data, Sakka, Kitabatake and colleagues, and the present authors studied mortality and cause of death among these technologists for 11 years from 1955 to 1965, for 7 years from 1966 to 1972, and for 5 years from 1973 to 1977, respectively. In general, the number of cancer deaths in the three studies was less than expected. However, Kitabatake et al. and the present authors found that deaths from skin cancer were significantly more frequent than expected. The present authors recently estimated the cumulative doses of radiation exposure for the majority of deaths (268 out of 395). The mean dose of radiation related to cancer deaths was then compared with that for non-cancer deaths. Also the proportional mortality ratios for cancers were observed in relation to the estimated dose level. In the present study, however, statistical tests to assess for the relationship between mortality and dose of radiation exposure showed no correlation, for the majority of deaths from cancer. (author)

  8. Maximizing the Benefit-Cost Ratio of Anthracyclines in Metastatic Breast Cancer: Case Report of a Patient with a Complete Response to High-Dose Doxorubicin

    Directory of Open Access Journals (Sweden)

    Kevin Shee

    2016-12-01

    Full Text Available Despite the clinical efficacy of anthracycline agents such as doxorubicin, dose-limiting cardiac toxicities significantly limit their long-term use. Here, we present the case of a 33-year-old female patient with extensive metastatic ER+/PR+/HER2– mucinous adenocarcinoma of the breast, who was started on doxorubicin/cyclophosphamide therapy after progressing on paclitaxel and ovarian suppressor goserelin with aromatase inhibitor exemestane. The patient was comanaged by cardiology, who carefully monitored measures of cardiac function, including EKGs, serial echocardiograms, and profiling of lipids, troponin, and pro-BNP every 2 months. The patient was treated with the cardioprotective agent dexrazoxane, and changes in cardiac markers [e.g. decreases in ejection fraction (EF] were immediately addressed by therapeutic intervention with the ACE inhibitor lisinopril and beta-blocker metoprolol. The patient had a complete response to doxorubicin therapy, with a cumulative dose of 1,350 mg/m2, which is significantly above the recommended limits, and to our knowledge, the highest dose reported in literature. Two and a half years after the last doxorubicin cycle, the patient is asymptomatic with no cardiotoxicity and an excellent quality of life. This case highlights the importance of careful monitoring and management of doxorubicin-mediated cardiotoxicity, and that higher cumulative doses of anthracyclines can be considered in patients with ongoing clinical benefit.

  9. The determination of patient dose from 18F-FDG PET/CT examination

    International Nuclear Information System (INIS)

    Khamwan, K.; Krisanachinda, A.; Pasawang, P.

    2010-01-01

    The use of positron emission tomography/computed tomography (PET/CT) system has heightened the need for medical diagnosis. However, the patient dose is increasing in comparison to whole-body PET/CT dose. The aim of this study is to determine the patient effective dose in 35 oncology Thai patients with the age range of 28-60 y from PET scan using [fluorine-18]-fluoro-2-deoxy-D-glucose and from CT scan. Cumulated activity and residence time of various organs were calculated from time-activity curves by using S-value based on the body mass. Mean organ absorbed dose and the effective dose from CT scan were calculated using the Medical Internal Radiation Dosimetry method and Monte Carlo simulation, respectively. The average whole-body effective doses from PET and CT were 4.40 ± 0.61 and 14.45 ± 2.82 mSv, respectively, resulting in the total patient dose of 18.85 mSv. This can be used as the reference dose in Thai patients. (authors)

  10. CABAS: A freely available PC program for fitting calibration curves in chromosome aberration dosimetry

    International Nuclear Information System (INIS)

    Deperas, J.; Szluiska, M.; Deperas-Kaminska, M.; Edwards, A.; Lloyd, D.; Lindholm, C.; Romm, H.; Roy, L.; Moss, R.; Morand, J.; Wojcik, A.

    2007-01-01

    The aim of biological dosimetry is to estimate the dose and the associated uncertainty to which an accident victim was exposed. This process requires the use of the maximum-likelihood method for fitting a calibration curve, a procedure that is not implemented in most statistical computer programs. Several laboratories have produced their own programs, but these are frequently not user-friendly and not available to outside users. We developed a software for fitting a linear-quadratic dose-response relationship by the method of maximum-likelihood and for estimating a dose from the number of aberrations observed. The program called as CABAS consists of the main curve-fitting and dose estimating module and modules for calculating the dose in cases of partial body exposure, for estimating the minimum number of cells necessary to detect a given dose of radiation and for calculating the dose in the case of a protracted exposure. (authors)

  11. A model to accumulate fractionated dose in a deforming organ

    International Nuclear Information System (INIS)

    Yan Di; Jaffray, D.A.; Wong, J.W.

    1999-01-01

    Purpose: Measurements of internal organ motion have demonstrated that daily organ deformation exists throughout the course of radiation treatment. However, a method of constructing the resultant dose delivered to the organ volume remains a difficult challenge. In this study, a model to quantify internal organ motion and a method to construct a cumulative dose in a deforming organ are introduced. Methods and Materials: A biomechanical model of an elastic body is used to quantify patient organ motion in the process of radiation therapy. Intertreatment displacements of volume elements in an organ of interest is calculated by applying an finite element method with boundary conditions, obtained from multiple daily computed tomography (CT) measurements. Therefore, by incorporating also the measurements of daily setup error, daily dose delivered to a deforming organ can be accumulated by tracking the position of volume elements in the organ. Furthermore, distribution of patient-specific organ motion is also predicted during the early phase of treatment delivery using the daily measurements, and the cumulative dose distribution in the organ can then be estimated. This dose distribution will be updated whenever a new measurement becomes available, and used to reoptimize the ongoing treatment. Results: An integrated process to accumulate dosage in a daily deforming organ was implemented. In this process, intertreatment organ motion and setup error were systematically quantified, and incorporated in the calculation of the cumulative dose. An example of the rectal wall motion in a prostate treatment was applied to test the model. The displacements of volume elements in the rectal wall, as well as the resultant doses, were calculated. Conclusion: This study is intended to provide a systematic framework to incorporate daily patient-specific organ motion and setup error in the reconstruction of the cumulative dose distribution in an organ of interest. The realistic dose

  12. Analytical investigations of thermoluminescence glow curve on quartz for luminescence dating

    International Nuclear Information System (INIS)

    Kim, K.B.; Hong, D.G.

    2015-01-01

    Investigations of bleaching and thermoluminescence (TL) response to radiation dose of quartz are importance in luminescence dating. Although such research has been extensively carried out for various types of quartz, most work was performed on the basis of TL intensity integrated for a particular temperature range on the glow curve, without any peak separation. In this study we investigated bleaching by a blue light stimulation and radiation dose behaviour for separated TL glow peaks of quartz, which are thermally stable, by using the computerized glow curve deconvolution (CGCD) method combined with the T_m–T_s_t_o_p method. The T_m–T_s_t_o_p method indicates that the glow curve of quartz is the superposition of at least seven components (P1–P7) in the temperature range between room temperature and 450 °C. A bleaching experiment for four thermally stable glow peaks (P4–P7) using a blue light stimulation revealed that the bleaching rate of peak P4 exhibits three different exponential decays, whereas the peaks P5, P6 and P7 are bleached with two different exponential decays. After bleaching of 12 h, the TL intensity of peaks P4, P5, P6 and P7 were reduced to approximately 6%, 16%, 26% and 68% of the initial value, respectively. Additionally, in a study of the radiation dose response of the four thermally stable glow peaks, all peaks have a similar pattern, which are well fitted by a single saturating exponential function. - Highlights: • We studied the physical characteristics of the separated TL glow peaks on quartz. • The kinetic parameters of each separated glow peak are evaluated by a CGCD method. • The separated peaks were bleached with two or three exponential decays. • The dose responses for the separated peaks showed a similar growth curve.

  13. Dose/dose-rate responses of shrimp larvae to UV-B radiation

    International Nuclear Information System (INIS)

    Damkaer, D.M.

    1981-01-01

    Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm -2 sub([DNA]) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm -2 sub([DNA]). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation. (orig.)

  14. Dose/dose-rate responses of shrimp larvae to UV-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Damkaer, D.M.; Dey, D.B.; Heron, G.A.

    1981-01-01

    Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm/sup -2/sub((DNA)) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm/sup -2/sub((DNA)). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation.

  15. Effects of oxygen and TMPN on the initial part of the dose-effect curves of human cells in culture

    International Nuclear Information System (INIS)

    Pettersen, E.O.; Wibe, E.; Lovhaug, D.; Oftebro, R.; Brustad, T.

    1975-01-01

    Human cells of the established cell line NHIK 3025 have been irradiated under various conditions of oxygen and TMPN concentrations. Complete survival curves are presented for each concentration of both oxygen and TMPN. The survival curves for extremely hypoxic cells in the absence of TMPN were found to be strictly exponential in the dose range below about 2300 rad, irrespective of the technique used. Oxygen at a concentration of 37 ppm was found to protect the cells at least above the dose range up to 2500 rad, while 250 ppm of oxygen exerted a protective effect in the dose range below 1200 rad and a sensitizing effect (OER = 1.43) for higher doses. However, the protective effect below 700 rad was found to be higher in the presence of 250 ppm O 2 , than 37 ppm O 2 , indicating that the degree of protection in this low-dose range is optimal for an oxygen concentration higher than 37 ppm. TMPN provides a protective and a sensitizing effect in about the same way as oxygen does, but TMPN is less effective. When the TMPN concentration is increased from 0.5 to 10 mM the maximum dose for which TMPN exerts a protective effect on the hypoxic cells decreases from 700 to 400 rad. However the degree of protection in the dose range below 300 rad is higher for TMPN concentrations of 1 mM and 3 mM than for 0.5 mM and 10 mM. Results indicate that the degree of protection is optimal in the low-dose range (< 300 rad) for a TMPN concentration somewhere between 0.5 mM and 3 mM. (author)

  16. Electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects

    International Nuclear Information System (INIS)

    Yan Zhi; Jiang Liying

    2011-01-01

    This work investigates the electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects through the surface-layer-based model and the generalized Young-Laplace equations. For nanoscale piezoelectric structures, the surface effects also include surface piezoelectricity in addition to the residual surface stress and surface elasticity for elastic nanomaterials. A Euler-Bernoulli curved beam theory is used to get the explicit solutions for the electroelastic fields of a curved cantilever beam when subjected to mechanical and electrical loads. In order to apply the appropriate boundary conditions on the beam, effective axial force, shear force and moment are derived. The results indicate that the surface effects play a significant role in the electroelastic fields and the piezoelectric response of the curved piezoelectric nanobeam. It is also found that the coupling of the residual surface stress, the surface elasticity and the surface piezoelectricity may be dramatic despite that the influence of the individual one is small under some circumstances. This study is expected to be useful for design and applications of curved beam based piezoelectric nanodevices, such as the curved nanowires/nanobelts or nanorings as nanoswitches or nanoactuators for displacement control purpose.

  17. Current and historical individual data about exposure of workers in the rayon industry to carbon disulfide and their validity in calculating the cumulative dose.

    Science.gov (United States)

    Göen, Thomas; Schramm, Axel; Baumeister, Thomas; Uter, Wolfgang; Drexler, Hans

    2014-08-01

    The objective of the study was to investigate how exposure to carbon disulfide (CS2) in a rayon-manufacturing plant has changed within two decades and whether it is possible to calculate valid data for the individual cumulative exposure. The data for CS2 concentration in air and biological exposure monitoring (2-thio-1,3-thiaxolidine-4-carboxylic acid (TTCA) in urine) from two cross-sectional studies, performed in 1992 (n = 362) and 2009 (n = 212) in a German rayon-manufacturing plant, were compared to data obtained from company-internal measurements between the studies. Using the data from the cross-sectional studies and company-internal data, cumulative external exposure and the cumulative internal exposure were calculated for each worker. External and internal CS2 exposure of the employees decreased from 1992 (medians 4.0 ppm and 1.63 mgTTCA/g creatinine) to 2009 (medians 2.5 ppm and 0.86 mg/g). However, company-internal CS2 data do not show a straight trend for this period. The annual medians of the company-internal measurement of external exposure to CS2 have varied between 2.7 and 8.4 ppm, in which median values exceeded 5 ppm generally since 2000. The annual medians for the company-internal biomonitoring assessment ranged between 1.2 and 2.8 mg/g creatinine. The cumulative CS2 exposure ranged from 8.5 to 869.5 ppm years for external exposure and between 1.30 and 176.2 mg/g creatinine years for the internal exposure. Significant correlations were found between the current air pollution and the internal exposure in 2009 but also between the cumulative external and internal CS2 exposure. Current exposure data, usually collected in cross-sectional studies, rarely allow a reliable statement on the cumulative dose, because of higher exposure in the past and of fluctuating courses of exposure. On the other hand, company-internal exposure data may be affected by non-representative measurement strategies. Some verification of the reliability of

  18. Cumulative high doses of inhaled formoterol have less systemic effects in asthmatic children 6-11 years-old than cumulative high doses of inhaled terbutaline

    DEFF Research Database (Denmark)

    Kaae, Rikke; Agertoft, Lone; Pedersen, Sören

    2004-01-01

    OBJECTIVES: To evaluate high dose tolerability and relative systemic dose potency between inhaled clinically equipotent dose increments of formoterol and terbutaline in children. METHODS: Twenty boys and girls (6-11 years-old) with asthma and normal ECGs were studied. Ten doses of formoterol (Oxi...

  19. The influence of high doses of radiation in citrine stones

    International Nuclear Information System (INIS)

    Teixeira, M. I.; Caldas, L. V. E.

    2014-08-01

    The possibility of using samples of Brazilian stones as quartz, amethyst, topaz, jasper, etc. for high-dose dosimetry has been studied in recent years at IPEN, using the techniques of optical absorption (Oa), thermoluminescent (Tl), optically stimulated luminescence (OSL) and resonance paramagnetic electron (EPR). In this work, the Tl properties of citrine samples were studied. They were exposed to different doses of gamma radiation ( 60 Co). The natural citrine stone was extracted from a mine in Minas Gerais state, Brazil; it is a tecto silicate ranked as one of three-dimensional structure, showing clear yellow to golden brown color. The natural citrine stone is classified as quartz (SiO 2 ), and it has a lower symmetry and more compact reticulum. The Tl emission curve showed two peaks at 160 grades C and 220 grades C. To remove the Tl peak (160 grades C) of the sintered citrine pellet glow curves, different thermal treatments were tested during several time intervals. The Tl dose-response curve between 50 Gy and 100 kGy, the reproducibility of Tl response and the lower detection dose were obtained. The results show that citrine may be useful as high-dose detectors. (Author)

  20. The influence of high doses of radiation in citrine stones

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, M. I. [Universidade Nove de Julho - UNINOVE, Rua Vergueiro 235/249, 01504-001 Sao Paulo (Brazil); Caldas, L. V. E., E-mail: miteixeira@ipen.br [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    The possibility of using samples of Brazilian stones as quartz, amethyst, topaz, jasper, etc. for high-dose dosimetry has been studied in recent years at IPEN, using the techniques of optical absorption (Oa), thermoluminescent (Tl), optically stimulated luminescence (OSL) and resonance paramagnetic electron (EPR). In this work, the Tl properties of citrine samples were studied. They were exposed to different doses of gamma radiation ({sup 60}Co). The natural citrine stone was extracted from a mine in Minas Gerais state, Brazil; it is a tecto silicate ranked as one of three-dimensional structure, showing clear yellow to golden brown color. The natural citrine stone is classified as quartz (SiO{sub 2}), and it has a lower symmetry and more compact reticulum. The Tl emission curve showed two peaks at 160 grades C and 220 grades C. To remove the Tl peak (160 grades C) of the sintered citrine pellet glow curves, different thermal treatments were tested during several time intervals. The Tl dose-response curve between 50 Gy and 100 kGy, the reproducibility of Tl response and the lower detection dose were obtained. The results show that citrine may be useful as high-dose detectors. (Author)

  1. A neutron dose equivalent meter at CAEP

    International Nuclear Information System (INIS)

    Tian Shihai; Lu Yan; Wang Heyi; Yuan Yonggang; Chen Xu

    2012-01-01

    The measurement of neutron dose equivalent has been a widespread need in industry and research. In this paper, aimed at improving the accuracy of neutron dose equivalent meter: a neutron dose counter is simulated with MCNP5, and the energy response curve is optimized. The results show that the energy response factor is from 0.2 to 1.8 for neutrons in the energy range of 2.53×10 -8 MeV to 10 MeV Compared with other related meters, it turns that the design of this meter is right. (authors)

  2. Kinetic and dose dependences of the SOS-induction in E.coli K-12 (uvrA) cells exposed to the different UV doses

    International Nuclear Information System (INIS)

    Komova, O.V.; Kandiano, E.S.; Malavya, G.

    1999-01-01

    The kinetic and dose dependences of the SOS-induction in E.coli (uvrA) cells exposed to UV light were investigated. Below 2 J/m 2 the rate of the SOS-induction increased with dose. The maximal level of the SOS-response was proportional to the UV dose. Pyrimidine dimers were necessary for the induction. In the dose range 2-10 J/m 2 the rate of the SOS-induction decreased with dose. The dose-response curve was non-linear. Pyrimidine dimers were not required for the induction. The nature of the molecular events leading to the SOS-induction at low and high UV doses was discussed. (author)

  3. Tissue responses to low protracted doses of high LET radiations or photons: Early and late damage relevant to radio-protective countermeasures

    Science.gov (United States)

    Ainsworth, E. J.; Afzal, S. M. J.; Crouse, D. A.; Hanson, W. R.; Fry, R. J. M.

    in host defense mechanisms was detected by a shorter mean survival time following challenge with transplantable leukemia cells. Comparison of dose-response curves for life shortening after irradiation with fission-spectrum neutrons or high energy silicon particles indicated high initial slopes for both radiation qualities at low doses, but for higher doses of silicon, the effect per Gy decreased to a value similar to that for γ rays. The two component life-shortening curve for silicon particles has implications for the potential efficacy of radioprotectants. Recent studies on protection against early and late effects by aminothiols, prostaglandins, and other compounds are discussed.

  4. Determination of electron clinical spectra from percentage depth dose (PDD) curves by classical simulated annealing method

    International Nuclear Information System (INIS)

    Visbal, Jorge H. Wilches; Costa, Alessandro M.

    2016-01-01

    Percentage depth dose of electron beams represents an important item of data in radiation therapy treatment since it describes the dosimetric properties of these. Using an accurate transport theory, or the Monte Carlo method, has been shown obvious differences between the dose distribution of electron beams of a clinical accelerator in a water simulator object and the dose distribution of monoenergetic electrons of nominal energy of the clinical accelerator in water. In radiotherapy, the electron spectra should be considered to improve the accuracy of dose calculation since the shape of PDP curve depends of way how radiation particles deposit their energy in patient/phantom, that is, the spectrum. Exist three principal approaches to obtain electron energy spectra from central PDP: Monte Carlo Method, Direct Measurement and Inverse Reconstruction. In this work it will be presented the Simulated Annealing method as a practical, reliable and simple approach of inverse reconstruction as being an optimal alternative to other options. (author)

  5. Cumulative and antagonistic effects of a mixture of the antiandrogens vinclozolin and iprodione in the pubertal male rat.

    Science.gov (United States)

    Blystone, Chad R; Lambright, Christy S; Cardon, Mary C; Furr, Johnathan; Rider, Cynthia V; Hartig, Phillip C; Wilson, Vickie S; Gray, Leon E

    2009-09-01

    Vinclozolin and iprodione are dicarboximide fungicides that display antiandrogenic effects in the male rat, which suggests that a mixture would lead to cumulative effects on androgen-sensitive end points. Iprodione is a steroid synthesis inhibitor, but androgen receptor antagonist activity, which is displayed by vinclozolin, has not been fully evaluated. Here, we demonstrate that iprodione binds to the human androgen receptor (IC(50) = 86.0 microM), reduces androgen-dependent gene expression, and reduces androgen-sensitive tissue weights in castrated male rats (Hershberger assay). Since vinclozolin and iprodione affect common targets in the pubertal male rat, we tested the hypothesis that a mixture would have cumulative antiandrogenic effects. An iprodione dose, that does not significantly affect androgen-dependent morphological end points, was combined with vinclozolin doses (2 x 5 factorial design). Sprague-Dawley rats were dosed by gavage with vinclozolin at 0, 10, 30, 60, and 100 mg/kg/day with and without 50 mg iprodione/kg/day from postnatal day (PND) 23 to 55-57 (n = 8 per group). The age at puberty (preputial separation [PPS]), organ weights, serum hormones, and ex vivo testis steroid hormone production were measured. Vinclozolin delayed PPS, reduced androgen-sensitive organ weights, and increased serum testosterone. The addition of iprodione enhanced the vinclozolin inhibition of PPS (PND 47.5 vs.49.1; two-way ANOVA: iprodione main effect p = 0.0002). The dose response for several reproductive and nonreproductive organ weights was affected in a cumulative manner. In contrast, iprodione antagonized the vinclozolin-induced increase in serum testosterone. These results demonstrate that these fungicides interact on common targets in a tissue-specific manner when coadministered to the pubertal male rat.

  6. Low dose response analysis through a cytogenetic end-point

    International Nuclear Information System (INIS)

    Bojtor, I.; Koeteles, G.J.

    1998-01-01

    The effects of low doses were studied on human lymphocytes of various individuals. The frequency of micronuclei in cytokinesis-blocked cultured lymphocytes was taken as end-point. The probability distribution of radiation-induced increment was statistically proved and identified as to be asymmetric when the blood samples had been irradiated with doses of 0.01-0.05 Gy of X-rays, similarly to that in unirradiated control population. On the contrary, at or above 1 Gy the corresponding normal curve could be accepted only reflecting an approximately symmetrical scatter of the increments about their mean value. It was found that the slope as well as the closeness of correlation of the variables considerably changed when lower and lower dose ranges had been selected. Below approximately 0.2 Gy even an unrelatedness was found betwen the absorbed dose and the increment

  7. Dose response relationship in local radiotherapy for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Park, Hee Chul; Seong, Jin Sil; Han, Kwang Hyub; Chon, Chae Yoon; Moon, Young Myoung; Song, Jae Seok; Suh, Chang Ok

    2001-01-01

    In this study, it was investigated whether dose response relation existed or not in local radiotherapy for primary hepatocellular carcinoma. From January 1992 to March 2000, 158 patients were included in present study. Exclusion criteria included the presence of extrahepatic metastasis, liver cirrhosis of Child's class C, tumors occupying more than two thirds of the entire liver, and performance status on the ECOG scale of more than 3. Radiotherapy was given to the field including tumor with generous margin using 6, 10-MV X-ray. Mean tumor dose was 48.2±7.9 Gy in daily 1.8 Gy fractions. Tumor response was based on diagnostic radiologic examinations such as CT scan, MR imaging, hepatic artery angiography at 4-8 weeks following completion of treatment. Statistical analysis was done to investigate the existence of dose response relationship of local radiotherapy when it was applied to the treatment of primary hepatocellular carcinoma. An objective response was observed in 106 of 158 patients, giving a response rate of 67. 1%. Statistical analysis revealed that total dose was the most significant factor in relation to tumor response when local radiotherapy was applied to the treatment of primary hepatocellular carcinoma. Only 29.2% showed objective response in patients treated with dose less than 40 Gy, while 68.6% and 77.1 % showed major response in patients with 40-50 Gy and more than 50 Gy, respectively. Child-Pugh classification was significant factor in the development of ascites, overt radiation induced liver disease and gastroenteritis. Radiation dose was an important factor for development of radiation induced gastroduodenal ulcer. Present study showed the existence of dose response relationship in local radiotherapy for primary hepatocellular carcinoma. Only radiotherapy dose was a significant factor to predict the objective response. Further study is required to predict the maximal tolerance dose in consideration of liver function and non-irradiated liver

  8. Fluid Overload and Cumulative Thoracostomy Output Are Associated With Surgical Site Infection After Pediatric Cardiothoracic Surgery.

    Science.gov (United States)

    Sochet, Anthony A; Nyhan, Aoibhinn; Spaeder, Michael C; Cartron, Alexander M; Song, Xiaoyan; Klugman, Darren; Brown, Anna T

    2017-08-01

    To determine the impact of cumulative, postoperative thoracostomy output, amount of bolus IV fluids and peak fluid overload on the incidence and odds of developing a deep surgical site infection following pediatric cardiothoracic surgery. A single-center, nested, retrospective, matched case-control study. A 26-bed cardiac ICU in a 303-bed tertiary care pediatric hospital. Cases with deep surgical site infection following cardiothoracic surgery were identified retrospectively from January 2010 through December 2013 and individually matched to controls at a ratio of 1:2 by age, gender, Risk Adjustment for Congenital Heart Surgery score, Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery category, primary cardiac diagnosis, and procedure. None. Twelve cases with deep surgical site infection were identified and matched to 24 controls without detectable differences in perioperative clinical characteristics. Deep surgical site infection cases had larger thoracostomy output and bolus IV fluid volumes at 6, 24, and 48 hours postoperatively compared with controls. For every 1 mL/kg of thoracostomy output, the odds of developing a deep surgical site infection increase by 13%. By receiver operative characteristic curve analysis, a cutoff of 49 mL/kg of thoracostomy output at 48 hours best discriminates the development of deep surgical site infection (sensitivity 83%, specificity 83%). Peak fluid overload was greater in cases than matched controls (12.5% vs 6%; p operative characteristic curve analysis, a threshold value of 10% peak fluid overload was observed to identify deep surgical site infection (sensitivity 67%, specificity 79%). Conditional logistic regression of peak fluid overload greater than 10% on the development of deep surgical site infection yielded an odds ratio of 9.4 (95% CI, 2-46.2). Increased postoperative peak fluid overload and cumulative thoracostomy output were associated with deep surgical site infection after pediatric

  9. Cumulative Risk and Adolescent's Internalizing and Externalizing Problems: The Mediating Roles of Maternal Responsiveness and Self-Regulation

    Science.gov (United States)

    Doan, Stacey N.; Fuller-Rowell, Thomas E.; Evans, Gary W.

    2012-01-01

    The purpose of the present study was to examine longitudinal associations among maternal responsiveness, self-regulation, and behavioral adjustment in adolescents. The authors used structural equation modeling to test a model that demonstrates that the effects of early cumulative risk on behavioral problems is mediated by maternal responsiveness…

  10. Dose-response relationship of γ-H2AX foci induction in human lymphocytes after X-rays exposure

    International Nuclear Information System (INIS)

    Mandina, Tania; Roch-Lefevre, Sandrine H.; Voisin, Pascale; Gonzalez, Jorge E.; Lamadrid, Ana I.; Romero, Ivonne; Garcia, Omar; Voisin, Philippe; Roy, Laurence

    2011-01-01

    Biological dosimeters are recommended for dose estimation in case of human overexposure to ionising radiation. Rapid measurement of γ-H2AX foci as a marker of DNA double-strand breaks (DSB) induction has been recently tested with this purpose. Here we reported a dose-response relationship after X-ray irradiation at different times post-exposure. Blood samples were obtained from several healthy donors and exposed to doses between 0 and 2 Gy. After irradiation, blood samples were incubated at 37 deg. C during 0.5 h, 5 h, and 8 h. Scoring of cells and γ-H2AX foci was performed by software. The dose-response curves for different incubation times were as follows: Y (0.5h) = 11.66D + 0.15 (R 2 = 0.99), Y (5h) = 2.44D + 0.15 (R 2 = 0.99), Y (8h) = 1.57D + 0.22 (R 2 = 0.99). At 0.5 h post-exposure, the dose-response relationship for X-irradiated lymphocytes was similar to the one obtained after gamma-irradiation using the same protocol. On the other hand, the results were not similar after 8 h due to different kinetics after gamma- and X-irradiation. Our results confirm the possibilities of using γ-H2AX foci method for dose estimation in a period from 0.5 h up to 8 h post X-irradiation and support the hypothesis of differences in γ-H2AX foci kinetics after gamma- and X-irradiation in vitro.

  11. Dose-response relationship of {gamma}-H2AX foci induction in human lymphocytes after X-rays exposure

    Energy Technology Data Exchange (ETDEWEB)

    Mandina, Tania [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Roch-Lefevre, Sandrine H.; Voisin, Pascale [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France); Gonzalez, Jorge E.; Lamadrid, Ana I.; Romero, Ivonne [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Garcia, Omar, E-mail: omar@cphr.edu.cu [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Voisin, Philippe; Roy, Laurence [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France)

    2011-09-15

    Biological dosimeters are recommended for dose estimation in case of human overexposure to ionising radiation. Rapid measurement of {gamma}-H2AX foci as a marker of DNA double-strand breaks (DSB) induction has been recently tested with this purpose. Here we reported a dose-response relationship after X-ray irradiation at different times post-exposure. Blood samples were obtained from several healthy donors and exposed to doses between 0 and 2 Gy. After irradiation, blood samples were incubated at 37 deg. C during 0.5 h, 5 h, and 8 h. Scoring of cells and {gamma}-H2AX foci was performed by software. The dose-response curves for different incubation times were as follows: Y{sub (0.5h)} = 11.66D + 0.15 (R{sup 2} = 0.99), Y{sub (5h)} = 2.44D + 0.15 (R{sup 2} = 0.99), Y{sub (8h)} = 1.57D + 0.22 (R{sup 2} = 0.99). At 0.5 h post-exposure, the dose-response relationship for X-irradiated lymphocytes was similar to the one obtained after gamma-irradiation using the same protocol. On the other hand, the results were not similar after 8 h due to different kinetics after gamma- and X-irradiation. Our results confirm the possibilities of using {gamma}-H2AX foci method for dose estimation in a period from 0.5 h up to 8 h post X-irradiation and support the hypothesis of differences in {gamma}-H2AX foci kinetics after gamma- and X-irradiation in vitro.

  12. Case Example of Dose Optimization Using Data From Bortezomib Dose-Finding Clinical Trials.

    Science.gov (United States)

    Lee, Shing M; Backenroth, Daniel; Cheung, Ying Kuen Ken; Hershman, Dawn L; Vulih, Diana; Anderson, Barry; Ivy, Percy; Minasian, Lori

    2016-04-20

    The current dose-finding methodology for estimating the maximum tolerated dose of investigational anticancer agents is based on the cytotoxic chemotherapy paradigm. Molecularly targeted agents (MTAs) have different toxicity profiles, which may lead to more long-lasting mild or moderate toxicities as well as to late-onset and cumulative toxicities. Several approved MTAs have been poorly tolerated during long-term administration, leading to postmarketing dose optimization studies to re-evaluate the optimal treatment dose. Using data from completed bortezomib dose-finding trials, we explore its toxicity profile, optimize its dose, and examine the appropriateness of current designs for identifying an optimal dose. We classified the toxicities captured from 481 patients in 14 bortezomib dose-finding studies conducted through the National Cancer Institute Cancer Therapy Evaluation Program, computed the incidence of late-onset toxicities, and compared the incidence of dose-limiting toxicities (DLTs) among groups of patients receiving different doses of bortezomib. A total of 13,008 toxicities were captured: 46% of patients' first DLTs and 88% of dose reductions or discontinuations of treatment because of toxicity were observed after the first cycle. Moreover, for the approved dose of 1.3 mg/m(2), the estimated cumulative incidence of DLT was > 50%, and the estimated cumulative incidence of dose reduction or treatment discontinuation because of toxicity was nearly 40%. When considering the entire course of treatment, the approved bortezomib dose exceeds the conventional ceiling DLT rate of 20% to 33%. Retrospective analysis of trial data provides an opportunity for dose optimization of MTAs. Future dose-finding studies of MTAs should take into account late-onset toxicities to ensure that a tolerable dose is identified for future efficacy and comparative trials. © 2016 by American Society of Clinical Oncology.

  13. Peak oil analyzed with a logistic function and idealized Hubbert curve

    International Nuclear Information System (INIS)

    Gallagher, Brian

    2011-01-01

    A logistic function is used to characterize peak and ultimate production of global crude oil and petroleum-derived liquid fuels. Annual oil production data were incrementally summed to construct a logistic curve in its initial phase. Using a curve-fitting approach, a population-growth logistic function was applied to complete the cumulative production curve. The simulated curve was then deconstructed into a set of annual oil production data producing an 'idealized' Hubbert curve. An idealized Hubbert curve (IHC) is defined as having properties of production data resulting from a constant growth-rate under fixed resource limits. An IHC represents a potential production curve constructed from cumulative production data and provides a new perspective for estimating peak production periods and remaining resources. The IHC model data show that idealized peak oil production occurred in 2009 at 83.2 Mb/d (30.4 Gb/y). IHC simulations of truncated historical oil production data produced similar results and indicate that this methodology can be useful as a prediction tool. - Research Highlights: →Global oil production data were analyzed by a simple curve fitting method. →Best fit-curve results were obtained using two logistic functions on select data. →A broad potential oil production peak is forecast for the years from 2004 to 2014. →Similar results were obtained using historical data from about 10 to 30 years ago. →Two potential oil production decline scenarios were presented and compared.

  14. Task 4 Improvised Nuclear Device Response Curves

    Energy Technology Data Exchange (ETDEWEB)

    Alai, Maureen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Neuscamman, Stephanie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-05-31

    LLNL performed fallout and nuclear blast modeling for the 60 cities using the NARAC modeling system and predominant weather patterns determined in a previous Task 4 effort. LLNL performed model simulations and analyses to identify and provide response curves (expressed as two-dimensional contours) for radioactive fallout deposition, transport, population, and blast overpressure as a function of yield, weather, location and time. These contours can then be further combined and correlated with infrastructure and population databases to estimate city specific effects on KPFs such as impacted infrastructure and casualty rates.

  15. Existence of a common growth curve for silt-sized quartz OSL of loess from different continents

    International Nuclear Information System (INIS)

    Lai Zhongping; Brueckner, Helmut; Zoeller, Ludwig; Fuelling, Alexander

    2007-01-01

    Recent publications revealed different opinions regarding the existence of a common growth curve (CGC) for OSL of quartz. In the current study, 18 loess samples were collected from four continents (Asia, America, Africa, and Europe) in order to further examine this issue. Except the three samples from Chile in South America, 15 samples display similar dose-response curves up to a regeneration dose of 200 Gy using the SAR protocol, suggesting the existence of a global CGC for loess from different continents. For samples with equivalent doses (D e ) from ∼10 to ∼170Gy, the D e s determined by the CGC are in good agreement with the D e s by the SAR protocol. The Chilean samples posses a growth curve that differs from the CGC, showing much lower saturation doses. We suggest that it may be due to contamination with heavy minerals

  16. Study of teflon pads as high doses dosemeters

    International Nuclear Information System (INIS)

    Teixeira, Maria Ines; Caldas, Linda V.E.

    2013-01-01

    The aim of this work is to study the Teflon, which is used as a binder in the manufacture of dosimetric tablets, for the feasibility of this material as high dose dosemeter. In this paper we used the technique of thermally stimulated luminescence (OSL) to characterize the dosimetric properties of Teflon. Teflon samples were exposed to different doses of radiation, using a source of gamma radiation ( 60 Co). It was obtained dose-response curve between 100 Gy to 50 kGy and reproducibility of OSL response. The preliminary results show that Teflon is a useful material to high dose dosimetry

  17. Summary of dosimetry, pathology, and dose response for bone sarcomas in beagles injected with radium-226

    International Nuclear Information System (INIS)

    Wrenn, M.E.; Taylor, G.N.; Stevens, W.

    1986-01-01

    In the completed 226 Ra portion of a 30-year-long experiment to determine the relative radiotoxicity of injected 226 Ra and 239 Pu, 42 of 116 animals injected with 226 Ra developed 63 bone sarcomas; none were observed in 44 controls. Average alpha plus beta dose to the skeleton to death was calculated on the basis of mathematical functions developed from sequential measurements of radium and radon retention in each dog. Bone sarcomas were identified radiographically or clinically, with subsequent histopathological confirmation and classification. Most primary bone tumors were classified as osteosarcomas if osteoid arose from a malignant stroma. The dose-response curve over the six lowest injected dose levels fits well to a linear, no-threshold, least squares fit, through a control incidence of 0.8%, and with a slope of 0.042% incidence per rad. 19 refs., 5 figs., 2 tabs

  18. Application of Hill's equation for estimating area under the concentration-time curve (AUC) and use of time to AUC 90% for expressing kinetics of drug disposition.

    Science.gov (United States)

    Cheng, Hsien C

    2009-01-01

    Half life and its derived pharmacokinetic parameters are calculated on an assumption that the terminal phase of drug disposition follows a constant rate of disposition. In reality, this assumption may not necessarily be the case. A new method is needed for analyzing PK parameters if the disposition does not follow a first order PK kinetic. Cumulative area under the concentration-time curve (AUC) is plotted against time to yield a hyperbolic (or sigmoidal) AUC-time relationship curve which is then analyzed by Hill's equation to yield AUC(inf), time to achieving AUC50% (T(AUC50%)) or AUC90% (T(AUC90%)), and the Hill's slope. From these parameters, an AUC-time relationship curve can be reconstructed. Projected plasma concentration can be calculated for any time point. Time at which cumulative AUC reaches 90% (T(AUC90%)) can be used as an indicator for expressing how fast a drug is cleared. Clearance is calculated in a traditional manner (i.v. dose/AUC(inf)), and the volume of distribution is proposed to be calculated at T(AUC50%) (0.5 i.v. dose/plasma concentration at T(AUC50%)). This method of estimating AUC is applicable for both i.v. and oral data. It is concluded that the Hill's equation can be used as an alternative method for estimating AUC and analysis of PK parameters if the disposition does not follow a first order kinetic. T(AUC90%) is proposed to be used as an indicator for expressing how fast a drug is cleared from the system.

  19. The influence of dose fractionation and dose rate on normal tissue responses

    International Nuclear Information System (INIS)

    Barendsen, G.W.

    1982-01-01

    An analysis of responses of a variety of normal tissues in animals to fractionated irradiations has been made with the aim of developing a formalism for the prediction of tolerance doses as a function of the dose per fraction and the overall treatment time. An important feature of the formalism is that it is directly based on radiological insights and therefore provides a logical concept to account for the diversity of tissue responses. (Auth.)

  20. TESS-based dose-response using pediatric clonidine exposures.

    Science.gov (United States)

    Benson, Blaine E; Spyker, Daniel A; Troutman, William G; Watson, William A

    2006-06-01

    The toxic and lethal doses of clonidine in children are unclear. This study was designed to determine whether data from the American Association of Poison Control Centers Toxic Exposure Surveillance System (TESS) could be utilized to determine a dose-response relationship for pediatric clonidine exposure. 3,458 single-substance clonidine exposures in children TESS from January 2000 through December 2003 were examined. Dose ingested, age, and medical outcome were available for 1550 cases. Respiratory arrest cases (n = 8) were classified as the most severe of the medical outcome categories (Arrest, Major, Moderate, Mild, and No effect). Exposures reported as a "taste or lick" (n = 51) were included as a dose of 1/10 of the dosage form involved. Dose ranged from 0.4 to 1980 (median 13) microg/kg. Weight was imputed based on a quadratic estimate of weight for age. Dose certainty was coded as exact (26% of cases) or not exact (74%). Medical outcome (response) was examined via logistic regression using SAS JMP (release 5.1). The logistic model describing medical outcome (P TESS data can provide the basis for a statistically sound description of dose-response for pediatric clonidine poisoning exposures.

  1. A Generalized QMRA Beta-Poisson Dose-Response Model.

    Science.gov (United States)

    Xie, Gang; Roiko, Anne; Stratton, Helen; Lemckert, Charles; Dunn, Peter K; Mengersen, Kerrie

    2016-10-01

    Quantitative microbial risk assessment (QMRA) is widely accepted for characterizing the microbial risks associated with food, water, and wastewater. Single-hit dose-response models are the most commonly used dose-response models in QMRA. Denoting PI(d) as the probability of infection at a given mean dose d, a three-parameter generalized QMRA beta-Poisson dose-response model, PI(d|α,β,r*), is proposed in which the minimum number of organisms required for causing infection, K min , is not fixed, but a random variable following a geometric distribution with parameter 0Poisson model, PI(d|α,β), is a special case of the generalized model with K min = 1 (which implies r*=1). The generalized beta-Poisson model is based on a conceptual model with greater detail in the dose-response mechanism. Since a maximum likelihood solution is not easily available, a likelihood-free approximate Bayesian computation (ABC) algorithm is employed for parameter estimation. By fitting the generalized model to four experimental data sets from the literature, this study reveals that the posterior median r* estimates produced fall short of meeting the required condition of r* = 1 for single-hit assumption. However, three out of four data sets fitted by the generalized models could not achieve an improvement in goodness of fit. These combined results imply that, at least in some cases, a single-hit assumption for characterizing the dose-response process may not be appropriate, but that the more complex models may be difficult to support especially if the sample size is small. The three-parameter generalized model provides a possibility to investigate the mechanism of a dose-response process in greater detail than is possible under a single-hit model. © 2016 Society for Risk Analysis.

  2. Cholinergic neuromodulation changes phase response curve shape and type in cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Klaus M Stiefel

    Full Text Available Spike generation in cortical neurons depends on the interplay between diverse intrinsic conductances. The phase response curve (PRC is a measure of the spike time shift caused by perturbations of the membrane potential as a function of the phase of the spike cycle of a neuron. Near the rheobase, purely positive (type I phase-response curves are associated with an onset of repetitive firing through a saddle-node bifurcation, whereas biphasic (type II phase-response curves point towards a transition based on a Hopf-Andronov bifurcation. In recordings from layer 2/3 pyramidal neurons in cortical slices, cholinergic action, consistent with down-regulation of slow voltage-dependent potassium currents such as the M-current, switched the PRC from type II to type I. This is the first report showing that cholinergic neuromodulation may cause a qualitative switch in the PRCs type implying a change in the fundamental dynamical mechanism of spike generation.

  3. Acute and Cumulative Effects of Unmodified 50-nm Nano-ZnO on Mice.

    Science.gov (United States)

    Kong, Tao; Zhang, Shu-Hui; Zhang, Ji-Liang; Hao, Xue-Qin; Yang, Fan; Zhang, Cai; Yang, Zi-Jun; Zhang, Meng-Yu; Wang, Jie

    2018-01-02

    Nanometer zinc oxide (nano-ZnO) is widely used in diverse industrial and agricultural fields. Due to the extensive contact humans have with these particles, it is crucial to understand the potential effects that nano-ZnO have on human health. Currently, information related to the toxicity and mechanisms of nano-ZnO is limited. The aim of the present study was to investigate acute and cumulative toxic effects of 50-nm unmodified ZnO in mice. This investigation will seek to establish median lethal dose (LD50), a cumulative coefficient, and target organs. The acute and cumulative toxicity was investigated by Karber's method and via a dose-increasing method, respectively. During the experiment, clinical signs, mortality, body weights, hematology, serum biochemistry, gross pathology, organ weight, and histopathology were examined. The LD50 was 5177-mg/kg·bw; the 95% confidence limits for the LD50 were 5116-5238-mg/kg·bw. It could be concluded that the liver, kidney, lung, and gastrointestinal tract were target organs for the 50-nm nano-ZnO acute oral treatment. The cumulative coefficient (K) was 1.9 which indicated that the cumulative toxicity was apparent. The results also indicated that the liver, kidney, lung, and pancrea were target organs for 50-nm nano-ZnO cumulative oral exposure and might be target organs for subchronic and chronic toxicity of oral administered 50-nm ZnO.

  4. Mean inactivation dose (D)

    International Nuclear Information System (INIS)

    Vijayakumar, S.; Ng, T.C.; Raudkivi, U.; Meaney, T.J.

    1990-01-01

    By predicting treatment outcome to radiotherapy from in vitro radiobiological parameters, not only individual patient treatments can be tailored, but also new promising treatment protocols can be tried in patients in whom unfavorable outcome is predicted. In this respect, choosing the right parameter can be very important. Unlike D 0 and N which provide information of the distal part of the survival curve, mean inactivation dose (D) estimates overall radiosensitivity. However, the parameters reflecting the response at the clinically relevant low-dose region are neglected in the literature. In a literature survey of 98 papers in which survival curves or D 0 /N were used, only in 2 D was used. In 21 papers the D 0 /n values were important in drawing conclusions. By calculating D in 3 of these 21 papers, we show that the conclusion drawn may be altered with the use of D. The importance of ''low-dose-region-parameters'' is reviewed. (orig.)

  5. A learning curve for solar thermal power

    Science.gov (United States)

    Platzer, Werner J.; Dinter, Frank

    2016-05-01

    Photovoltaics started its success story by predicting the cost degression depending on cumulated installed capacity. This so-called learning curve was published and used for predictions for PV modules first, then predictions of system cost decrease also were developed. This approach is less sensitive to political decisions and changing market situations than predictions on the time axis. Cost degression due to innovation, use of scaling effects, improved project management, standardised procedures including the search for better sites and optimization of project size are learning effects which can only be utilised when projects are developed. Therefore a presentation of CAPEX versus cumulated installed capacity is proposed in order to show the possible future advancement of the technology to politics and market. However from a wide range of publications on cost for CSP it is difficult to derive a learning curve. A logical cost structure for direct and indirect capital expenditure is needed as the basis for further analysis. Using derived reference cost for typical power plant configurations predictions of future cost have been derived. Only on the basis of that cost structure and the learning curve levelised cost of electricity for solar thermal power plants should be calculated for individual projects with different capacity factors in various locations.

  6. Cumulative toxicity of neonicotinoid insecticide mixtures to Chironomus dilutus under acute exposure scenarios.

    Science.gov (United States)

    Maloney, Erin M; Morrissey, Christy A; Headley, John V; Peru, Kerry M; Liber, Karsten

    2017-11-01

    Extensive agricultural use of neonicotinoid insecticide products has resulted in the presence of neonicotinoid mixtures in surface waters worldwide. Although many aquatic insect species are known to be sensitive to neonicotinoids, the impact of neonicotinoid mixtures is poorly understood. In the present study, the cumulative toxicities of binary and ternary mixtures of select neonicotinoids (imidacloprid, clothianidin, and thiamethoxam) were characterized under acute (96-h) exposure scenarios using the larval midge Chironomus dilutus as a representative aquatic insect species. Using the MIXTOX approach, predictive parametric models were fitted and statistically compared with observed toxicity in subsequent mixture tests. Single-compound toxicity tests yielded median lethal concentration (LC50) values of 4.63, 5.93, and 55.34 μg/L for imidacloprid, clothianidin, and thiamethoxam, respectively. Because of the similar modes of action of neonicotinoids, concentration-additive cumulative mixture toxicity was the predicted model. However, we found that imidacloprid-clothianidin mixtures demonstrated response-additive dose-level-dependent synergism, clothianidin-thiamethoxam mixtures demonstrated concentration-additive synergism, and imidacloprid-thiamethoxam mixtures demonstrated response-additive dose-ratio-dependent synergism, with toxicity shifting from antagonism to synergism as the relative concentration of thiamethoxam increased. Imidacloprid-clothianidin-thiamethoxam ternary mixtures demonstrated response-additive synergism. These results indicate that, under acute exposure scenarios, the toxicity of neonicotinoid mixtures to C. dilutus cannot be predicted using the common assumption of additive joint activity. Indeed, the overarching trend of synergistic deviation emphasizes the need for further research into the ecotoxicological effects of neonicotinoid insecticide mixtures in field settings, the development of better toxicity models for neonicotinoid mixture

  7. TLD-100 glow-curve deconvolution for the evaluation of the thermal stress and radiation damage effects

    CERN Document Server

    Sabini, M G; Cuttone, G; Guasti, A; Mazzocchi, S; Raffaele, L

    2002-01-01

    In this work, the dose response of TLD-100 dosimeters has been studied in a 62 MeV clinical proton beams. The signal versus dose curve has been compared with the one measured in a sup 6 sup 0 Co beam. Different experiments have been performed in order to observe the thermal stress and the radiation damage effects on the detector sensitivity. A LET dependence of the TL response has been observed. In order to get a physical interpretation of these effects, a computerised glow-curve deconvolution has been employed. The results of all the performed experiments and deconvolutions are extensively reported, and the TLD-100 possible fields of application in the clinical proton dosimetry are discussed.

  8. Mahalanobis distance and variable selection to optimize dose response

    International Nuclear Information System (INIS)

    Moore, D.H. II; Bennett, D.E.; Wyrobek, A.J.; Kranzler, D.

    1979-01-01

    A battery of statistical techniques are combined to improve detection of low-level dose response. First, Mahalanobis distances are used to classify objects as normal or abnormal. Then the proportion classified abnormal is regressed on dose. Finally, a subset of regressor variables is selected which maximizes the slope of the dose response line. Use of the techniques is illustrated by application to mouse sperm damaged by low doses of x-rays

  9. An application of the learning curve-cumulative summation test to evaluate training for endotracheal intubation in emergency medicine.

    Science.gov (United States)

    Je, Sangmo; Cho, Youngsuk; Choi, Hyuk Joong; Kang, Boseung; Lim, Taeho; Kang, Hyunggoo

    2015-04-01

    The learning curve-cumulative summation (LC-CUSUM) test allows for quantitative and individual assessments of the learning process. In this study, we evaluated the process of skill acquisition for performing endotracheal intubation (ETI) in three emergency medicine (EM) residents over a 2 year period in their first 2 years of their EM residency. We evaluated 342 ETI cases performed by three EM residents using the LC-CUSUM test according to their rate of success or failure of ETI. A 90% success rate (SR) was chosen to define adequate performance and an SR of 80% was considered inadequate. After the learning phase, the standard CUSUM test was applied to ensure that performance was maintained. The mean number of ETI cases required to reach the predefined level of performance was 74.7 (95% CI 62.0 to 87.3). CUSUM tests confirmed that performance was maintained after the learning phase. By using the LC-CUSUM test, we were able to quantitatively monitor the acquisition of the skill of ETI by EM residents. The LC-CUSUM could be useful for monitoring the learning process for the training of airway management in the practice of EM. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  10. Calibration curves for biological dosimetry by drug-induced prematurely condensed chromosomes in human lymphocytes

    International Nuclear Information System (INIS)

    Kang, C. M.; Chung, H. C.; Cho, C. K.

    2002-01-01

    To develop the cytogenetic tool to detect chromosome damages after high dose exposure with 60 Coγ- rays, dose-response curves were measured for induction of prematurely condensed chromosomes (PCC) in peripheral lymphocytes. Blood was obtained from 10 different healthy donors, and given okadaic acid (OA) 500nM in cultured lymphocytes 1h after radiation exposure. Cells were analyzed by the frequencies of OA-induced PCC rings because it is difficult to obtain mitotic chromosomes using a conventional chromosome aberration (CA). PCC-rings were scored in cells exposed in the dose range of 0.2-16Gy. The frequency of the cells with PCC and the dose-response relationship for the yield of PCC rings were examined in the irradiated lymphocytes. The yield of PCC-rings increased with dose dependent-manner up to 16Gy. The observed dose-effect relationship for the percentage of cells with PCC-rings was calculated by linear-quadratic model. This technique can be applied to biological dosimetry of radiation exposures involving whole body irradiation to allow damaged chromosomes to be detected with great sensitivity. Detection of okadaic acid-induced PCC rings is a useful method up to 16Gy or more doses in estimating the absorbed doses of victims after high dose exposure. Calibration curves described in this paper will be used in our laboratory for biological dosimetry by PCC-ring after a high dose exposure

  11. Dose-response relationship of induction kinetics of In vivo DNA damage and repair in mouse leukocytes exposed to gamma radiation

    International Nuclear Information System (INIS)

    Mendiola C, M.T.; Morales, R.P.

    2000-01-01

    The Unicellular electrophoresis in gel technique is a useful tool in the determination of simple ruptures and labile sites to the alkali in DNA of eucariontes cells. The determination of the induction kinetics of damage and repair of DNA can give more information. The objective of this work was to determine whether the analysis of the area under the damage/repair induction kinetics curve in comets percent or the comets frequency in the two peaks of maximum induction is adequate for determining the dose-response relationship. The mice were exposed at the doses of 0.5, 1.0, 2.0 Gy. (Author)

  12. Dose-response relationships and risk estimates for the induction of cancer due to low doses of low-LET radiation

    International Nuclear Information System (INIS)

    Elaguppillai, V.

    1981-01-01

    Risk estimates for radiation-induced cancer at low doses can be obtained only by extrapolation from the known effects at high doses and high dose rates, using a suitable dose-response model. The applicability of three different models, linear, sublinear and supralinear, are discussed in this paper. Several experimental studies tend to favour a sublinear dose-response model (linear-quadratic model) for low-LET radiation. However, human epidemiological studies do not exclude any of the dose-response relationships. The risk estimates based on linear and linear quadratic dose-response models are compared and it is concluded that, for low-LET radiation, the linear dose-response model would probably over-estimate the actual risk of cancer by a factor of two or more. (author)

  13. Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture

    Directory of Open Access Journals (Sweden)

    Timothy J. Albaugh

    2015-08-01

    Full Text Available We examined three hypotheses in a nutrient dose and application frequency study installed in juvenile (aged 2–6 years old Pinus stands at 22 sites in the southeastern United States. At each site, eight or nine treatments were installed where nitrogen was applied at different rates (0, 67, 134, 268 kg ha−1 and frequencies (0, 1, 2, 4 and 6 years in two or four replications. Phosphorus was applied at 0.1 times the nitrogen rate and other elements were added as needed based on foliar nutrient analysis to insure that nutrient imbalances were not induced with treatment. Eight years after treatment initiation, the site responses were grouped based on texture and drainage characteristics: soil group 1 consisted of poorly drained soils with a clayey subsoil, group 2 consisted of poorly to excessively drained spodic soils or soils without a clay subsoil, and group 3 consisted of well-drained soils with a clayey subsoil. We accepted the first hypothesis that site would be a significant factor explaining growth responses. Soil group was also a significant factor explaining growth response. We accepted our second hypothesis that the volume growth-cumulative dose response function was not linear. Volume growth reached an asymptote in soil groups 1 and 3 between cumulative nitrogen doses of 300–400 kg ha−1. Volume growth responses continued to increase up to 800 kg ha−1 of cumulatively applied nitrogen for soil group 2. We accepted our third hypothesis that application rate and frequency did not influence the growth response when the cumulative nitrogen dose was equivalent. There was no difference in the growth response for comparisons where a cumulative nitrogen dose of 568 kg ha−1 was applied as 134 kg ha−1 every two years or as 269 kg ha−1 every four years, or where 269 kg ha−1 of nitrogen was applied as four applications of 67 kg ha−1 every two years or as two applications of 134 kg ha−1 every four years. Clearly, the sites examined

  14. Estimation of chloroform inhalation dose by other routes based on the relationship of area under the blood concentration-time curve (AUC)-inhalation dose to chloroform distribution in the blood of rats.

    Science.gov (United States)

    Take, Makoto; Takeuchi, Tetsuya; Haresaku, Mitsuru; Matsumoto, Michiharu; Nagano, Kasuke; Yamamoto, Seigo; Takamura-Enya, Takeji; Fukushima, Shoji

    2014-01-01

    The present study investigated the time-course changes of concentration of chloroform (CHCl3) in the blood during and after exposure of male rats to CHCl3 by inhalation. Increasing the dose of CHCl3 in the inhalation exposed groups caused a commensurate increase in the concentration of CHCl3 in the blood and the area under the blood concentration-time curve (AUC). There was good correlation (r = 0.988) between the inhalation dose and the AUC/kg body weight. Based on the AUC/kg body weight-inhalation dose curve and the AUC/kg body weight after oral administration, inhalation equivalent doses of orally administered CHCl3 were calculated. Calculation of inhalation equivalent doses allows the body burden due to CHCl3 by inhalation exposure and oral exposure to be directly compared. This type of comparison facilitates risk assessment in humans exposed to CHCl3 by different routes. Our results indicate that when calculating inhalation equivalent doses of CHCl3, it is critical to include the AUC from the exposure period in addition to the AUC after the end of the exposure period. Thus, studies which measure the concentration of volatile organic compounds in the blood during the inhalation exposure period are crucial. The data reported here makes an important contribution to the physiologically based pharmacokinetic (PBPK) database of CHCl3 in rodents.

  15. The Dose Response Relationship for Radiation Carcinogenesis

    Science.gov (United States)

    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

  16. TESS-based dose-response using pediatric clonidine exposures

    International Nuclear Information System (INIS)

    Benson, Blaine E.; Spyker, Daniel A.; Troutman, William G.; Watson, William A.

    2006-01-01

    Objective: The toxic and lethal doses of clonidine in children are unclear. This study was designed to determine whether data from the American Association of Poison Control Centers Toxic Exposure Surveillance System (TESS) could be utilized to determine a dose-response relationship for pediatric clonidine exposure. Methods: 3458 single-substance clonidine exposures in children <6 years of age reported to TESS from January 2000 through December 2003 were examined. Dose ingested, age, and medical outcome were available for 1550 cases. Respiratory arrest cases (n = 8) were classified as the most severe of the medical outcome categories (Arrest, Major, Moderate, Mild, and No effect). Exposures reported as a 'taste or lick' (n = 51) were included as a dose of 1/10 of the dosage form involved. Dose ranged from 0.4 to 1980 (median 13) μg/kg. Weight was imputed based on a quadratic estimate of weight for age. Dose certainty was coded as exact (26% of cases) or not exact (74%). Medical outcome (response) was examined via logistic regression using SAS JMP (release 5.1). Results: The logistic model describing medical outcome (P < 0.0001) included Log dose/kg (P 0.0000) and Certainty (P = 0.045). Conclusion: TESS data can provide the basis for a statistically sound description of dose-response for pediatric clonidine poisoning exposures

  17. Teflon pastille use in high dose dosimetry; Utilizacao de pastilhas de teflon em dosimetria de doses altas

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Maria Ines [Associacao Educacional Nove de Julho (UNINOVE), Sao Paulo, SP (Brazil); Caldas, Linda V.E., E-mail: miteixeira@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-10-26

    This paper study the Teflon, which is used as aglomerant in the confection of dosimetric pastilles, for the viabilization of this material as high dose dosimeter. This paper used the OSL technique for the characterization of dosimetric properties of Teflon. The doses-response curve has been obtained for {sup 60}Co radiation between 100 Gy and 50 kGy, and the OSL answer reproducibility. The preliminary results shown that the Teflon is a material which can be used for high dose dosimetry

  18. Studies on adaptive response of lymphocyte transformation induced by low-dose irradiation

    International Nuclear Information System (INIS)

    Du Zeji; Su Liaoyuan; Tian Hailin; Zou Huawei

    1995-10-01

    Human peripheral blood lymphocytes stimulated by mitogen in vitro for 24 h were exposed to low-dose γ-ray irradiation (0.5∼4.0 cGy, adaptive dose). They showed an adaptive response to the inhibition of 3 H-TdR incorporation by subsequent higher acute doses of γ-ray (challenge dose). At the interval of 24 h between adaptive dose and challenge dose, the strongest adaptive response induced by low-dose irradiation was found. It is also found that the response induced by 1.0 cGy of adaptive dose was more obvious than that by other doses and that 3.0 Gy of challenge dose produced the strongest adaptive response. As the challenge doses increased, the adaptive response reduced. (2 figs., 2 tabs.)

  19. De determination for young samples using the standardised OSL response of coarse-grain quartz

    International Nuclear Information System (INIS)

    Burbidge, C.I.; Duller, G.A.T.; Roberts, H.M.

    2006-01-01

    It has recently been shown that it is possible to construct standardised curves of the sensitivity corrected growth in optically stimulated luminescence (OSL) with exposure to ionising radiation, and that they may be used in the dating of quartz and polymineral samples. Standardised growth curves are particularly advantageous where measurement time is limited, as once they have been defined, only the natural signal and the response to a subsequent test dose are required in order to determine the equivalent dose of a sub-sample. The present study is concerned with the application of the standardised growth curve approach to OSL dating of Holocene age samples. Systematic changes in the shape of the standardised growth curve of coarse-grain quartz are identified as the size of the test dose is varied, because of non-proportionality between the test dose and the luminescence test response. The effect is characterised by fitting the change in gradient of the standardised growth curve as test dose is varied. An equation is defined to describe standardised growth as a function of regenerative dose and test dose. Regenerative dose responses of other samples in this study are treated as unknowns and recovered through different growth curves to compare precision and accuracy of various methods of D e determination. The standardised growth curve is found to yield similar precision to conventional fits of single aliquot regenerative data, but slightly poorer accuracy. The standardised growth curve approach was refined by incorporating the measurement of one regenerative response for each aliquot as well as its natural signal. Measurements of this additional data point for aliquots of 22 samples were used to adjust the standardised growth equation, improving its accuracy. The incorporation of this additional data point also indicated a systematic uncertainty of 2.4% in the estimates of D e

  20. Dose-response relationship in local radiotherapy for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Park, Hee Chul; Seong, Jinsil; Han, Kwang Hyub; Chon, Chae Yoon; Moon, Young Myoung; Suh, Chang Ok

    2002-01-01

    Purpose: Dose escalation using three-dimensional conformal radiotherapy (3D-CRT) is based on the hypothesis that increasing the dose can enhance tumor control. This study aimed to determine whether a dose-response relationship exists in local radiotherapy for primary hepatocellular carcinoma (HCC). Methods and Materials: One hundred fifty-eight patients were enrolled in the present study between January 1992 and March 2000. The exclusion criteria included the presence of an extrahepatic metastasis, liver cirrhosis of Child class C, tumors occupying more than two-thirds of the entire liver, and a performance status on the Eastern Cooperative Oncology Group scale of more than 3. Radiotherapy was given to the field, including the tumor, with generous margin using 6- or 10-MV X-rays. The mean radiation dose was 48.2 ± 7.9 Gy in daily 1.8-Gy fractions. The tumor response was assessed based on diagnostic radiologic examinations, including a computed tomography scan, magnetic resonance imaging, and hepatic artery angiography 4-8 weeks after the completion of treatment. Liver toxicity and gastrointestinal complications were evaluated. Results: An objective response was observed in 106 of 158 (67.1%) patients. Statistical analysis revealed that the total dose was the most significant factor associated with the tumor response. The response rates in patients treated with doses 50 Gy were 29.2%, 68.6%, and 77.1%, respectively. Survivals at 1 and 2 years after radiotherapy were 41.8% and 19.9%, respectively, with a median survival time of 10 months. The rate of liver toxicity according to the doses 50 Gy was 4.2%, 5.9%, and 8.4%, respectively, and the rate of gastrointestinal complications was 4.2%, 9.9%, and 13.2%, respectively. Conclusions: The present study showed the existence of a dose-response relationship in local radiotherapy for primary HCC. Only the radiation dose was a significant factor for predicting an objective response. The results of this study showed that 3D

  1. Tumor and normal tissue responses to fractioned non-uniform dose delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kaellman, P; Aegren, A; Brahme, A [Karolinska Inst., Stockholm (Sweden). Dept. of Radiation Physics

    1996-08-01

    The volume dependence of the radiation response of a tumor is straight forward to quantify because it depends primarily on the eradication of all its clonogenic cells. A tumor therefore has a parallel organization as any surviving clonogen in principle can repopulate the tumor. The difficulty with the response of the tumor is instead to know the density and sensitivity distribution of the most resistant clonogenic cells. The increase in the 50% tumor control dose and the decrease in the maximum normalized slope of the dose response relation, {gamma}, in presence of small compartments of resistant tumor cells have therefore been quantified to describe their influence on the dose response relation. Injury to normal tissue is a much more complex and gradual process. It depends on earlier effects induced long before depletion of the differentiated and clonogenic cells that in addition may have a complex structural and functional organization. The volume dependence of the dose response relation of normal tissues is therefore described here by the relative seriality, s, of the infrastructure of the organ. The model can also be generalized to describe the response of heterogeneous tissues to non uniform dose distributions. The new model is compared with clinical and experimental data on normal tissue response, and shows good agreement both with regard to the shape of dose response relation and the volume dependence of the isoeffect dose. The response of tumors and normal tissues are quantified for arbitrary dose fractionations using the linear quadratic cell survival parameters {alpha} and {beta}. The parameters of the dose response relation are derived both for a constant dose per fraction and a constant number of dose fractions, thus in the latter case accounting also for non uniform dose delivery. (author). 26 refs, 4 figs.

  2. Calibration curves for biological dosimetry

    International Nuclear Information System (INIS)

    Guerrero C, C.; Brena V, M. . E-mail cgc@nuclear.inin.mx

    2004-01-01

    The generated information by the investigations in different laboratories of the world, included the ININ, in which settles down that certain class of chromosomal leisure it increases in function of the dose and radiation type, has given by result the obtaining of calibrated curves that are applied in the well-known technique as biological dosimetry. In this work is presented a summary of the work made in the laboratory that includes the calibrated curves for gamma radiation of 60 Cobalt and X rays of 250 k Vp, examples of presumed exposure to ionizing radiation, resolved by means of aberration analysis and the corresponding dose estimate through the equations of the respective curves and finally a comparison among the dose calculations in those people affected by the accident of Ciudad Juarez, carried out by the group of Oak Ridge, USA and those obtained in this laboratory. (Author)

  3. Introduction to benchmark dose methods and U.S. EPA's benchmark dose software (BMDS) version 2.1.1

    International Nuclear Information System (INIS)

    Davis, J. Allen; Gift, Jeffrey S.; Zhao, Q. Jay

    2011-01-01

    Traditionally, the No-Observed-Adverse-Effect-Level (NOAEL) approach has been used to determine the point of departure (POD) from animal toxicology data for use in human health risk assessments. However, this approach is subject to substantial limitations that have been well defined, such as strict dependence on the dose selection, dose spacing, and sample size of the study from which the critical effect has been identified. Also, the NOAEL approach fails to take into consideration the shape of the dose-response curve and other related information. The benchmark dose (BMD) method, originally proposed as an alternative to the NOAEL methodology in the 1980s, addresses many of the limitations of the NOAEL method. It is less dependent on dose selection and spacing, and it takes into account the shape of the dose-response curve. In addition, the estimation of a BMD 95% lower bound confidence limit (BMDL) results in a POD that appropriately accounts for study quality (i.e., sample size). With the recent advent of user-friendly BMD software programs, including the U.S. Environmental Protection Agency's (U.S. EPA) Benchmark Dose Software (BMDS), BMD has become the method of choice for many health organizations world-wide. This paper discusses the BMD methods and corresponding software (i.e., BMDS version 2.1.1) that have been developed by the U.S. EPA, and includes a comparison with recently released European Food Safety Authority (EFSA) BMD guidance.

  4. Depressive disorder, coronary heart disease, and stroke: dose-response and reverse causation effects in the Whitehall II cohort study.

    Science.gov (United States)

    Brunner, Eric J; Shipley, Martin J; Britton, Annie R; Stansfeld, Stephen A; Heuschmann, Peter U; Rudd, Anthony G; Wolfe, Charles D A; Singh-Manoux, Archana; Kivimaki, Mika

    2014-03-01

    Systematic reviews examining associations of depressive disorder with coronary heart disease and stroke produce mixed results. Failure to consider reverse causation and dose-response patterns may have caused inconsistencies in evidence. This prospective cohort study on depressive disorder, coronary heart disease, and stroke analysed reverse causation and dose-response effects using four 5-year and three 10-year observation cycles (total follow up 24 years) based on multiple repeat measures of exposure. Participants in the Whitehall II study (n = 10,036, 31,395 person-observations, age at start 44.4 years) provided up to six repeat measures of depressive symptoms via the 30-item General Health Questionnaire (GHQ-30) and one measure via Center for Epidemiologic Studies Depression Scale (CES-D). The cohort was followed up for major coronary events (coronary death/nonfatal myocardial infarction) and stroke (stroke death/morbidity) through the national mortality register Hospital Episode Statistics, ECG-screening, medical records, and self-report questionnaires. GHQ-30 caseness predicted stroke over 0-5 years (age-, sex- and ethnicity-adjusted HR 1.60, 95% CI 1.1-2.3) but not over 5-10 years (HR 0.94, 95% CI 0.6-1.4). Using the last 5-year observation cycle, cumulative GHQ-30 caseness was associated with incident coronary heart disease in a dose-response manner (1-2 times a case: HR 1.12, 95% CI 0.7-1.7; 3-4 times: HR 2.06, 95% CI 1.2-3.7), and CES-D caseness predicted coronary heart disease (HR 1.81, 95% CI 1.1-3.1). There was evidence of a dose-response effect of depressive symptoms on risk of coronary heart disease. In contrast, prospective associations of depressive symptoms with stroke appeared to arise wholly or partly through reverse causation.

  5. Using plant biomonitors and flux modelling to develop O3 dose-response relationships in Catalonia

    International Nuclear Information System (INIS)

    Filella, Iolanda; Pen-tilde uelas, Josep; Ribas, Angela

    2005-01-01

    We used tobacco Bel-W3 biomonitoring data and ozone flux modelling (WINDEP model) with the aim of developing the absorbed dose-response relationship, and comparing this approach with the most commonly used AOT40 (the sum of hourly ozone concentrations above a cut-off of 40 ppb during daylight hours, when global radiation exceeds 50 W m -2 ) in the estimation of exposure-damage curves. Leaf damage values were more related to OAD 15days,potential (potential ozone absorbed dose calculated over 15 consecutive days) than to AOT40 in all the studied stations. An OAD 15days,potential of 180 mg m -2 was found to be the threshold for damage to the most sensitive species in this region under well watered conditions. The results show the applicability of the flux approach for risk assessment at the local scale, the improvement of the ozone damage estimation when the potential absorbed dose is modelled and used instead of just the ozone exposure, and finally, the possibilities opened by the use of biomonitoring networks. - Modelling of biomonitors ozone absorbed dose improves damage estimation in comparison with exposure indices such as AOT40

  6. The cumulative effect of air pollutants on the acute exacerbation of COPD in Shanghai, China.

    Science.gov (United States)

    Sun, Xian Wen; Chen, Pei Li; Ren, Lei; Lin, Ying Ni; Zhou, Jian Ping; Ni, Lei; Li, Qing Yun

    2018-05-01

    Epidemiologic studies have shown the effect of air pollutants on acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, little is known regarding the dose-response relationship. This study aimed to investigate the cumulative effect of air pollutants on AECOPD. We collected 101 patients with AECOPD from November 2010 through August 2011 in Shanghai. Multiple logistic regression was used to estimate associations between air pollutants and AECOPD. Poisson regression was then applied to determine the cumulative effect of air pollutants including particulate matter 10 (PM10), PM2.5, nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ) and ozone (O 3 ) on AECOPD, of which the seasonal variation was further explored. The monthly episodes of AECOPD were associated with the concentrations of PM2.5 (r=0.884, peffect in cold season, whereas 7days in warm season. The RR for AECOPD for per 10μg/m 3 increment in NO 2 was 1.07, with a 5-day cumulative effect without seasonal variation. High consecutive levels of PM2.5 and NO 2 increase the risk of developing AECOPD. Cumulative effect of PM2.5 and NO 2 appears before the exacerbation onset. These gradations were more evident in the PM2.5 during different seasons. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Bermudagrass (Cynodon spp) dose-response relationships with clethodim, glufosinate and glyphosate.

    Science.gov (United States)

    Webster, Theodore M; Hanna, Wayne W; Mullinix, Benjamin G

    2004-12-01

    Greenhouse studies were conducted to evaluate the sensitivity of three commercial cultivars, eight experimental cultivars and common bermudagrass to clethodim, glufosinate and glyphosate. Each herbicide was applied at eight doses. Data were regressed on herbicide dose using a log-logistic curve (R2 = 0.56-0.95 for clethodim, R2 = 0.60-0.94 for glufosinate, and R2 = 0.70-0.96 for glyphosate). The herbicide rate that elicited a 50% plant response (I50) in the bermudagrass cultivars ranged from 0.04 to 0.19 kg ha(-1) clethodim, 0.19 to 1.33 kg ha(-1) glufosinate and 0.34 to 1.14 kg ha(-1) glyphosate. Relative to other cultivars, common bermudagrass was intermediate in its response to clethodim and among the most tolerant cultivars to glufosinate and glyphosate. TifSport was relatively tolerant to clethodim and glufosinate compared with other cultivars, but relatively sensitive to glyphosate. One cultivar, 94-437, was consistently among the most sensitive cultivars to each of the herbicides. While there were differential herbicide tolerances among the tested bermudagrass cultivars, there did not appear to be any naturally occurring herbicide resistance that could be commercially utilized. However, research indicated that breeding efforts should target herbicide resistance that is at least four times the registered use rate. Also, TifSport and Tifway have been identified as suitable representatives of triploid hybrid bermudagrass cultivars to be used to evaluate the success of turfgrass renovation programs. 2004 Society of Chemical Industry.

  8. Analyzing Multiple-Choice Questions by Model Analysis and Item Response Curves

    Science.gov (United States)

    Wattanakasiwich, P.; Ananta, S.

    2010-07-01

    In physics education research, the main goal is to improve physics teaching so that most students understand physics conceptually and be able to apply concepts in solving problems. Therefore many multiple-choice instruments were developed to probe students' conceptual understanding in various topics. Two techniques including model analysis and item response curves were used to analyze students' responses from Force and Motion Conceptual Evaluation (FMCE). For this study FMCE data from more than 1000 students at Chiang Mai University were collected over the past three years. With model analysis, we can obtain students' alternative knowledge and the probabilities for students to use such knowledge in a range of equivalent contexts. The model analysis consists of two algorithms—concentration factor and model estimation. This paper only presents results from using the model estimation algorithm to obtain a model plot. The plot helps to identify a class model state whether it is in the misconception region or not. Item response curve (IRC) derived from item response theory is a plot between percentages of students selecting a particular choice versus their total score. Pros and cons of both techniques are compared and discussed.

  9. Construction of dose-effect curves by irradiating peripheral blood mononuclear cells analyzed with the alkaline comet assay

    International Nuclear Information System (INIS)

    Rueda, Lenin; Rosales Jaime; Leon, Kety; Espinoza, Marco

    2015-01-01

    The suitability of the alkaline comet assay to detect levels of DNA damage in human monocytes and lymphocytes under radiation was tested. For this purpose, four dose-effect curves by irradiation of cells isolated from blood samples of 4 young, health and non-smoker donors. A gamma ray source of "6"0Co was used and doses of 0, 2.5, 5 and 7 Gy were delivered to blood cells. The results show good correlation (R2 = 0.973, SD = 0.009) between the radiation dose and DNA damage as measured by the parameter Tail Intensity (percentage of DNA in the tail of the 'comet'). Furthermore, we observe the variability in predicting DNA damage by Gy (7.59, SD = 1.5). Potential use of this technique in the biological dosimetry of ionizing radiations is being evaluated. (author)

  10. Effect of iron salt counter ion in dose-response curves for inactivation of Fusarium solani in water through solar driven Fenton-like processes

    Science.gov (United States)

    Aurioles-López, Verónica; Polo-López, M. Inmaculada; Fernández-Ibáñez, Pilar; López-Malo, Aurelio; Bandala, Erick R.

    2016-02-01

    The inactivation of Fusarium solani in water was assessed by solar driven Fenton-like processes using three different iron salts: ferric acetylacetonate (Fe(acac)3), ferric chloride (FeCl3) and ferrous sulfate (FeSO4). The experimental conditions tested were [Fe] ≈ 5 mg L-1, [H2O2] ≈ 10 mg L-1 and [Fe] ≈ 10 mg L-1; [H2O2] ≈ 20 mg L-1 mild and high, respectively, and pH 3.0 and 5.0, under solar radiation. The highest inactivation rates were observed at high reaction conditions for the three iron salts tested at pH 5.0 with less than 3.0 kJ L-1 of accumulate energy (QUV) to achieve over 99.9% of F. solani inactivation. Fe(acac)3 was the best iron salt to accomplishing F. solani inactivation. The modified Fermi equation was used to fix the experimental inactivation, data showed it was helpful for modeling the process, adequately describing dose-response curves. Inactivation process using FeSO4 at pH 3.0 was modeled fairly with r2 = 0.98 and 0.99 (mild and high concentration, respectively). Fe(acac)3, FeCl3 and FeSO4 at high concentration (i.e. [Fe] ≈ 10 mg L-1; [H2O2] ≈ 20 mg L-1) and pH 5.0 showed the highest fitting values (r2 = 0.99). Iron salt type showed a remarkable influence on the Fenton-like inactivation process.

  11. Linearization of Positional Response Curve of a Fiber-optic Displacement Sensor

    Science.gov (United States)

    Babaev, O. G.; Matyunin, S. A.; Paranin, V. D.

    2018-01-01

    Currently, the creation of optical measuring instruments and sensors for measuring linear displacement is one of the most relevant problems in the area of instrumentation. Fiber-optic contactless sensors based on the magneto-optical effect are of special interest. They are essentially contactless, non-electrical and have a closed optical channel not subject to contamination. The main problem of this type of sensors is the non-linearity of their positional response curve due to the hyperbolic nature of the magnetic field intensity variation induced by moving the magnetic source mounted on the controlled object relative to the sensing element. This paper discusses an algorithmic method of linearizing the positional response curve of fiber-optic displacement sensors in any selected range of the displacements to be measured. The method is divided into two stages: 1 - definition of the calibration function, 2 - measurement and linearization of the positional response curve (including its temperature stabilization). The algorithm under consideration significantly reduces the number of points of the calibration function, which is essential for the calibration of temperature dependence, due to the use of the points that randomly deviate from the grid points with uniform spacing. Subsequent interpolation of the deviating points and piecewise linear-plane approximation of the calibration function reduces the microcontroller storage capacity for storing the calibration function and the time required to process the measurement results. The paper also presents experimental results of testing real samples of fiber-optic displacement sensors.

  12. Dose-response relationship for breast cancer induction at radiotherapy dose

    Directory of Open Access Journals (Sweden)

    Gruber Günther

    2011-06-01

    Full Text Available Abstract Purpose Cancer induction after radiation therapy is known as a severe side effect. It is therefore of interest to predict the probability of second cancer appearance for the patient to be treated including breast cancer. Materials and methods In this work a dose-response relationship for breast cancer is derived based on (i the analysis of breast cancer induction after Hodgkin's disease, (ii a cancer risk model developed for high doses including fractionation based on the linear quadratic model, and (iii the reconstruction of treatment plans for Hodgkin's patients treated with radiotherapy, (iv the breast cancer induction of the A-bomb survivor data. Results The fitted model parameters for an α/β = 3 Gy were α = 0.067Gy-1 and R = 0.62. The risk for breast cancer is according to this model for small doses consistent with the finding of the A-bomb survivors, has a maximum at doses of around 20 Gy and drops off only slightly at larger doses. The predicted EAR for breast cancer after radiotherapy of Hodgkin's disease is 11.7/10000PY which can be compared to the findings of several epidemiological studies where EAR for breast cancer varies between 10.5 and 29.4/10000PY. The model was used to predict the impact of the reduction of radiation volume on breast cancer risk. It was estimated that mantle field irradiation is associated with a 3.2-fold increased risk compared with mediastinal irradiation alone, which is in agreement with a published value of 2.7. It was also shown that the modelled age dependency of breast cancer risk is in satisfying agreement with published data. Conclusions The dose-response relationship obtained in this report can be used for the prediction of radiation induced secondary breast cancer of radiotherapy patients.

  13. The utility of the historical record for assessing the transient climate response to cumulative emissions

    Science.gov (United States)

    Friedlingstein, Pierre

    2018-01-01

    The historical observational record offers a way to constrain the relationship between cumulative carbon dioxide emissions and global mean warming. We use a standard detection and attribution technique, along with observational uncertainties to estimate the all-forcing or ‘effective’ transient climate response to cumulative emissions (TCRE) from the observational record. Accounting for observational uncertainty and uncertainty in historical non-CO2 radiative forcing gives a best-estimate from the historical record of 1.84°C/TtC (1.43–2.37°C/TtC 5–95% uncertainty) for the effective TCRE and 1.31°C/TtC (0.88–2.60°C/TtC 5–95% uncertainty) for the CO2-only TCRE. While the best-estimate TCRE lies in the lower half of the IPCC likely range, the high upper bound is associated with the not-ruled-out possibility of a strongly negative aerosol forcing. Earth System Models have a higher effective TCRE range when compared like-for-like with the observations over the historical period, associated in part with a slight underestimate of diagnosed cumulative emissions relative to the observational best-estimate, a larger ensemble mean-simulated CO2-induced warming, and rapid post-2000 non-CO2 warming in some ensemble members. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. PMID:29610381

  14. The utility of the historical record for assessing the transient climate response to cumulative emissions

    Science.gov (United States)

    Millar, Richard J.; Friedlingstein, Pierre

    2018-05-01

    The historical observational record offers a way to constrain the relationship between cumulative carbon dioxide emissions and global mean warming. We use a standard detection and attribution technique, along with observational uncertainties to estimate the all-forcing or `effective' transient climate response to cumulative emissions (TCRE) from the observational record. Accounting for observational uncertainty and uncertainty in historical non-CO2 radiative forcing gives a best-estimate from the historical record of 1.84°C/TtC (1.43-2.37°C/TtC 5-95% uncertainty) for the effective TCRE and 1.31°C/TtC (0.88-2.60°C/TtC 5-95% uncertainty) for the CO2-only TCRE. While the best-estimate TCRE lies in the lower half of the IPCC likely range, the high upper bound is associated with the not-ruled-out possibility of a strongly negative aerosol forcing. Earth System Models have a higher effective TCRE range when compared like-for-like with the observations over the historical period, associated in part with a slight underestimate of diagnosed cumulative emissions relative to the observational best-estimate, a larger ensemble mean-simulated CO2-induced warming, and rapid post-2000 non-CO2 warming in some ensemble members. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

  15. Study of a new glass matrix by thermoluminescent technique for high-dose dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Pamela Z.; Carvalho, Gabriel S. Marchiori de; Cunha, Diego M. da; Dantas, Noelio O.; Silva, Anielle C.A.; Neves, Lucio P.; Perini, Ana P., E-mail: anapaula.perini@ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil). Instituto de Fisica; Linda, V.E. Caldas [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carrera, Betzabel N.S.; Watanabe, Shigueo [Universidade de Sao Paulo (IF/USP), Sao Paulo, SP (Brazil). Instituto de Fisica

    2016-07-01

    The thermoluminescence technique is widely used for both personal and for high-dose dosimetry. In this work, the thermoluminescence technique was utilized to study a new glass matrix, with nominal composition of 20Li{sub 2}CO{sub 3}.10Al{sub 2}O{sub 3}.30BaO.40B{sub 2}O{sub 3} (mol%), irradiated with different doses in a {sup 60}Co source. The glow curves and the dose-response curve were obtained for radiation doses of 10, 50, 100, 200 e 700 Gy. The results showed that this new glass matrix has potential use in high-dose dosimetry. (author)

  16. Red light-induced shift of the fluence-response curve for first positive curvature of maize [Zea mays] coleoptiles

    International Nuclear Information System (INIS)

    Hofmann, E.; Schäfer, E.

    1987-01-01

    The fluence-response curve for first positive phototropic curvture of dark-grown maize coleoptiles is shifted to ten-fold higher fluences if the coieoptiles are irradiated with red light 2 h prior to the phototropic induction with blue light. Fluence-response curves for this red-induced shift were obtained with unilateral red irradiations 2 h prior to inductive blue pulses of different fluences. They differ significantly depending on whether the red light was given from the same side as or the opposite side to the respective inductive blue pulse, thus demonstrating that the red light effect is a local response of the coleoptile. The fluence-response curves for an inductive blue pulse in the ascending part were compared with those for an inductive blue pulse in the descending part of the fluence-response curve for blue light induced phototropism. They are quite different in threshold of red light sensitivity and shape for irradiations from both the same and the opposite sides. This offers evidence for the hypothesis that at least two different photosystems are involved in phototropism, and that they are modulated differently by a red light preirradiation. All these fluence-response curves indicate that it is possible to increase the response in the coleoptile, if the red light preirradiation is given opposite to the inductive blue pulse. This is supported by blue light fluence-response curves obtained after a weak unilateral red preirradiation. (author)

  17. Heterogeneity in glucose response curves during an oral glucose tolerance test and associated cardiometabolic risk

    DEFF Research Database (Denmark)

    Hulman, Adam; Simmons, Rebecca Kate; Vistisen, Dorte

    2017-01-01

    patterns of plasma glucose change during the oral glucose tolerance test. Cardiometabolic risk factor profiles were compared between the identified groups. Using latent class trajectory analysis, five glucose response curves were identified. Despite similar fasting and 2-h values, glucose peaks and peak......We aimed to examine heterogeneity in glucose response curves during an oral glucose tolerance test with multiple measurements and to compare cardiometabolic risk profiles between identified glucose response curve groups. We analyzed data from 1,267 individuals without diabetes from five studies...... in Denmark, the Netherlands and the USA. Each study included between 5 and 11 measurements at different time points during a 2-h oral glucose tolerance test, resulting in 9,602 plasma glucose measurements. Latent class trajectories with a cubic specification for time were fitted to identify different...

  18. Dose-Response Relationship between Cumulative Occupational Lead Exposure and the Associated Health Damages: A 20-Year Cohort Study of a Smelter in China

    OpenAIRE

    Yue Wu; Jun-Ming Gu; Yun Huang; Yan-Ying Duan; Rui-Xue Huang; Jian-An Hu

    2016-01-01

    Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China’s existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into continuous contact with lead at work for longer than 3 months. The dose-response relationship between o...

  19. Cumulative effects of forest management activities: how might they occur?

    Science.gov (United States)

    R. M. Rice; R. B. Thomas

    1985-01-01

    Concerns are often voiced about possible environmental damage as the result of the cumulative sedimentation effects of logging and forest road construction. In response to these concerns, National Forests are developing procedures to reduce the possibility that their activities may lead to unacceptable cumulative effects

  20. The effect of pre-dose on thermally and optically stimulated luminescence from α-Al2O3:C,Mg and α-Al2O3:C.

    Science.gov (United States)

    Kalita, J M; Chithambo, M L

    2018-06-15

    We report the effect of pre-dose on the thermoluminescence (TL) and optically stimulated luminescence (OSL) dose response of α-Al 2 O 3 :C,Mg and α-Al 2 O 3 :C. Before any luminescence measurement, the samples were irradiated with different doses, namely 100, 500 and 1000 Gy to populate the deep electron traps. This is the pre-dose. The results from TL and OSL studies are compared with results from samples used without any pre-measurement dose. The TL glow curves and OSL decay curves of α-Al 2 O 3 :C,Mg recorded after pre-doses of 100, 500 and 1000 Gy are identical to those from a sample used without any pre-dose. Further, the TL and OSL dose response of all α-Al 2 O 3 :C,Mg samples are similar regardless of pre-dose. In comparison, the TL glow curves and OSL decay curves of α-Al 2 O 3 :C are influenced by pre-dose. We conclude that the differences in the TL and OSL dose response of various pre-dosed samples of α-Al 2 O 3 :C are due to the concentration of charge in the deep traps. On the other hand, owing to the lower concentration of such deep traps in α-Al 2 O 3 :C,Mg, the TL or OSL dose responses are not affected by pre-dose in this material. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. The Key Events Dose-Response Framework: a cross-disciplinary mode-of-action based approach to examining dose-response and thresholds.

    Science.gov (United States)

    Julien, Elizabeth; Boobis, Alan R; Olin, Stephen S

    2009-09-01

    The ILSI Research Foundation convened a cross-disciplinary working group to examine current approaches for assessing dose-response and identifying safe levels of intake or exposure for four categories of bioactive agents-food allergens, nutrients, pathogenic microorganisms, and environmental chemicals. This effort generated a common analytical framework-the Key Events Dose-Response Framework (KEDRF)-for systematically examining key events that occur between the initial dose of a bioactive agent and the effect of concern. Individual key events are considered with regard to factors that influence the dose-response relationship and factors that underlie variability in that relationship. This approach illuminates the connection between the processes occurring at the level of fundamental biology and the outcomes observed at the individual and population levels. Thus, it promotes an evidence-based approach for using mechanistic data to reduce reliance on default assumptions, to quantify variability, and to better characterize biological thresholds. This paper provides an overview of the KEDRF and introduces a series of four companion papers that illustrate initial application of the approach to a range of bioactive agents.

  2. Dose-response analysis using R

    DEFF Research Database (Denmark)

    Ritz, Christian; Baty, Florent; Streibig, Jens Carl

    2015-01-01

    Dose-response analysis can be carried out using multi-purpose commercial statistical software, but except for a few special cases the analysis easily becomes cumbersome as relevant, non-standard output requires manual programming. The extension package drc for the statistical environment R provides...

  3. Analysis of Cumulative Dose to Implanted Pacemaker According to Various IMRT Delivery Methods: Optimal Dose Delivery Versus Dose Reduction Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Woo; Hong, Se Mie [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of)

    2011-11-15

    Cancer patients with implanted cardiac pacemaker occasionally require radiotherapy. Pacemaker may be damaged or malfunction during radiotherapy due to ionizing radiation or electromagnetic interference. Although radiotherapy should be planned to keep the dose to pacemaker as low as possible not to malfunction ideally, current radiation treatment planning (RTP) system does not accurately calculate deposited dose to adjacent field border or area beyond irradiated fields. In terms of beam delivery techniques using multiple intensity modulated fields, dosimetric effect of scattered radiation in high energy photon beams is required to be detailed analyzed based on measurement data. The aim of this study is to evaluate dose discrepancies of pacemaker in a RTP system as compared to measured doses. We also designed dose reduction strategy limited value of 2 Gy for radiation treatment patients with cardiac implanted pacemaker. Total accumulated dose of 145 cGy based on in-vivo dosimetry was satisfied with the recommendation criteria to prevent malfunction of pacemaker in SS technique. However, the 2 mm lead shielder enabled the scattered doses to reduce up to 60% and 40% in the patient and the phantom, respectively. The SS technique with the lead shielding could reduce the accumulated scattered doses less than 100 cGy. Calculated and measured doses were not greatly affected by the beam delivery techniques. In-vivo and measured doses on pacemaker position showed critical dose discrepancies reaching up to 4 times as compared to planned doses in RTP. The current SS technique could deliver lower scattered doses than recommendation criteria, but use of 2 mm lead shielder contributed to reduce scattered doses by 60%. The tertiary lead shielder can be useful to prevent malfunction or electrical damage of implanted pacemakers during radiotherapy. It is required to estimate more accurate scattered doses of the patient or medical device in RTP to design proper dose reduction strategy.

  4. Analysis of Cumulative Dose to Implanted Pacemaker According to Various IMRT Delivery Methods: Optimal Dose Delivery Versus Dose Reduction Strategy

    International Nuclear Information System (INIS)

    Lee, Jeong Woo; Hong, Se Mie

    2011-01-01

    Cancer patients with implanted cardiac pacemaker occasionally require radiotherapy. Pacemaker may be damaged or malfunction during radiotherapy due to ionizing radiation or electromagnetic interference. Although radiotherapy should be planned to keep the dose to pacemaker as low as possible not to malfunction ideally, current radiation treatment planning (RTP) system does not accurately calculate deposited dose to adjacent field border or area beyond irradiated fields. In terms of beam delivery techniques using multiple intensity modulated fields, dosimetric effect of scattered radiation in high energy photon beams is required to be detailed analyzed based on measurement data. The aim of this study is to evaluate dose discrepancies of pacemaker in a RTP system as compared to measured doses. We also designed dose reduction strategy limited value of 2 Gy for radiation treatment patients with cardiac implanted pacemaker. Total accumulated dose of 145 cGy based on in-vivo dosimetry was satisfied with the recommendation criteria to prevent malfunction of pacemaker in SS technique. However, the 2 mm lead shielder enabled the scattered doses to reduce up to 60% and 40% in the patient and the phantom, respectively. The SS technique with the lead shielding could reduce the accumulated scattered doses less than 100 cGy. Calculated and measured doses were not greatly affected by the beam delivery techniques. In-vivo and measured doses on pacemaker position showed critical dose discrepancies reaching up to 4 times as compared to planned doses in RTP. The current SS technique could deliver lower scattered doses than recommendation criteria, but use of 2 mm lead shielder contributed to reduce scattered doses by 60%. The tertiary lead shielder can be useful to prevent malfunction or electrical damage of implanted pacemakers during radiotherapy. It is required to estimate more accurate scattered doses of the patient or medical device in RTP to design proper dose reduction strategy.

  5. ESR response of powder samples of clear fused quartz material to high doses of 10 MeV electrons: possible applications for industrial radiation processing

    International Nuclear Information System (INIS)

    Aliabadi, R.; Amraei, R.; Ranjbar, A.H.; Rafieian, Sh.; Nasirimoghadam, S.

    2010-01-01

    Powder samples of clear fused quartz were irradiated by 10 MeV electrons at doses between 6-15 kGy and 25-37 kGy and analyzed with electron spin resonance. The reproducibility of the material dose response curve was studied, in which the irradiated samples were annealed and reused for further investigations. Results indicate a good linearity between the absorbed dose and the ESR intensity of the signals. They also showed that in the reuse processes, the electron spin resonance signal intensity, in both dose ranges was decreased. The thermal fading represented a relative sharp decay at room temperature through 15 days, after which the decay-rate was negligible for a measurement period of 60 days.

  6. RADIOIODINE TREATMENT OF GRAVES’ DISEASE – DOSE/RESPONSE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Jitka Čepková

    2014-01-01

    Full Text Available The clinical outcome of 153 Graves’ disease patients treated with a wide dose range of radioactive iodine-131 (RAI was analyzed retrospectively. Six to nine months after the first dose of RAI 60 patients (39% were hypothyroid (or rather thyroxine-substituted and 26 (17% were euthyroid, while 67 patients (44% did not respond properly: in 32 (21% their antithyroid drug (ATD dose could be reduced but not withdrawn (partial response and 35 (23% remained hyperthyroid or the same dose of ATD was necessary (no response. The outcome did not correspond significantly to the administered activity of RAI (medians 259, 259, 222, and 259 MBq for hypothyroid, euthyroid, partial, and no response subgroups, respectively, or the activity retained in the gland at 24 h (medians 127, 105, 143, and 152 MBq. The effect was, however, clearly, and in a stepwise pattern, dependent on initial thyroid volume (17, 26, 33 and 35 ml, P  6 MBq/g, cure rate 80% and lower (≤ 6 MBq/g, cure rate 46% doses gave highly significant difference (P < 0.001. With our dosing range we found a dose-dependent clinical outcome that suggests an optimum delivered dose near 6.5 MBq/g, resulting in successful treatment of ca 80% patients.

  7. Biological dose estimation for accidental supra-high dose gamma-ray exposure

    International Nuclear Information System (INIS)

    Chen, Y.; Yan, X.K.; Du, J.; Wang, Z.D.; Zhang, X.Q.; Zeng, F.G.; Zhou, P.K.

    2011-01-01

    To correctly estimate the biological dose of victims accidentally exposed to a very high dose of 60 Co gamma-ray, a new dose-effect curve of chromosomal dicentrics/multicentrics and rings in the supra-high dose range was established. Peripheral blood from two healthy men was irradiated in vitro with doses of 60 Co gamma-rays ranging from 6 to 22 Gy at a dose rate of 2.0 Gy/min. Lymphocytes were concentrated, cultured and harvested at 52 h, 68 h and 72 h. The numbers of dic + r were counted. The dose-effect curves were established and validated using comparisons with doses from the Tokai-mura accident and were then applied to two victims of supra-high dose exposure accident. The results indicated that there were no significant differences in chromosome aberration frequency among the different culture times from 52 h to 72 h. The 6-22 Gy dose-effect curve was fitted to a linear quadratic model Y = -2.269 + 0.776D - 7.868 x l0 -3 D 2 . Using this mathematic model, the dose estimates were similar to data from Tokai-mura which were estimated by PCC ring. Whole body average doses of 9.7 Gy and 18.1 Gy for two victims in the Jining accident were satisfactorily given. We established and successfully applied a new dose-effect curve of chromosomal dicentrics plus ring (dic + r) after 6-22 Gy γ-irradiation from a supra-high dose 60 Co gamma-ray accident.

  8. Extending the relationship between global warming and cumulative carbon emissions to multi-millennial timescales

    International Nuclear Information System (INIS)

    Frölicher, Thomas L; Paynter, David J

    2015-01-01

    The transient climate response to cumulative carbon emissions (TCRE) is a highly policy-relevant quantity in climate science. The TCRE suggests that peak warming is linearly proportional to cumulative carbon emissions and nearly independent of the emissions scenario. Here, we use simulations of the Earth System Model (ESM) from the Geophysical Fluid Dynamics Laboratory (GFDL) to show that global mean surface temperature may increase by 0.5 °C after carbon emissions are stopped at 2 °C global warming, implying an increase in the coefficient relating global warming to cumulative carbon emissions on multi-centennial timescales. The simulations also suggest a 20% lower quota on cumulative carbon emissions allowed to achieve a policy-driven limit on global warming. ESM estimates from the Coupled Model Intercomparison Project Phase 5 (CMIP5–ESMs) qualitatively agree on this result, whereas Earth System Models of Intermediate Complexity (EMICs) simulations, used in the IPCC 5th assessment report to assess the robustness of TCRE on multi-centennial timescales, suggest a post-emissions decrease in temperature. The reason for this discrepancy lies in the smaller simulated realized warming fraction in CMIP5–ESMs, including GFDL ESM2M, than in EMICs when carbon emissions increase. The temperature response to cumulative carbon emissions can be characterized by three different phases and the linear TCRE framework is only valid during the first phase when carbon emissions increase. For longer timescales, when emissions tape off, two new metrics are introduced that better characterize the time-dependent temperature response to cumulative carbon emissions: the equilibrium climate response to cumulative carbon emissions and the multi-millennial climate response to cumulative carbon emissions. (letter)

  9. Internal and external generalizability of temporal dose-response relationships for xerostomia following IMRT for head and neck cancer.

    Science.gov (United States)

    Thor, Maria; Owosho, Adepitan A; Clark, Haley D; Oh, Jung Hun; Riaz, Nadeem; Hovan, Allan; Tsai, Jillian; Thomas, Steven D; Yom, Sae Hee K; Wu, Jonn S; Huryn, Joseph M; Moiseenko, Vitali; Lee, Nancy Y; Estilo, Cherry L; Deasy, Joseph O

    2017-02-01

    To study internal and external generalizability of temporal dose-response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. Objective xerostomia was assessed in 121 patients (n Cohort1 =55; n Cohort2 =66) treated to 70Gy@2Gy in 2006-2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer-Lemeshow p-values (p HL )). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmean contra , Dmean ipsi ) were estimated from the generated dose-response curves. The observed xerostomia rate was 38%/47% (3months) and 19%/23% (11-12months) in Cohort1/Cohort2. Risk of xerostomia at 3months increased for higher Dmean contra and Dmean ipsi (Cohort1: 0.17·Dmean contra +0.11·Dmean ipsi -8.13; AUC=0.90±0.05; p=0.0002±0.002; p HL =0.22±0.23; Cohort2: AUC=0.81; pxerostomia following IMRT. Our results also suggest decreasing Dmean contra to below 20Gy, while keeping Dmean ipsi to around 25Gy. Long-term xerostomia was less frequent, and no dose-response relationship was established for this follow-up time. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. Dose-response relationships for environmentally mediated infectious disease transmission models.

    Directory of Open Access Journals (Sweden)

    Andrew F Brouwer

    2017-04-01

    Full Text Available Environmentally mediated infectious disease transmission models provide a mechanistic approach to examining environmental interventions for outbreaks, such as water treatment or surface decontamination. The shift from the classical SIR framework to one incorporating the environment requires codifying the relationship between exposure to environmental pathogens and infection, i.e. the dose-response relationship. Much of the work characterizing the functional forms of dose-response relationships has used statistical fit to experimental data. However, there has been little research examining the consequences of the choice of functional form in the context of transmission dynamics. To this end, we identify four properties of dose-response functions that should be considered when selecting a functional form: low-dose linearity, scalability, concavity, and whether it is a single-hit model. We find that i middle- and high-dose data do not constrain the low-dose response, and different dose-response forms that are equally plausible given the data can lead to significant differences in simulated outbreak dynamics; ii the choice of how to aggregate continuous exposure into discrete doses can impact the modeled force of infection; iii low-dose linear, concave functions allow the basic reproduction number to control global dynamics; and iv identifiability analysis offers a way to manage multiple sources of uncertainty and leverage environmental monitoring to make inference about infectivity. By applying an environmentally mediated infectious disease model to the 1993 Milwaukee Cryptosporidium outbreak, we demonstrate that environmental monitoring allows for inference regarding the infectivity of the pathogen and thus improves our ability to identify outbreak characteristics such as pathogen strain.

  11. Low level dose induced chromosome aberrations in human blood lymphocytes

    International Nuclear Information System (INIS)

    Pohl-Rueling, J.

    1992-01-01

    Unstable structural aberrations in chromosomes of human blood lymphocytes cannot be used as biological dosemeters in the low dose range, when extrapolating from high doses using a linear dose response, as required by the original formula of the dual radiation action theory. A survey is given of experimental dose-response curves of chromosome aberrations, obtained in investigations not only by this institute, in cooperation with many other laboratories, but also by various authors in different areas of the world. The results are not compatible with the predicted linear dose relationships at in vivo dose ranges up to 30 mGy.y -1 . The aberration frequencies rise sharply with dose within the normal environmental exposure up to about twice that level. At higher doses, aberration frequencies increase less rapidly and reach a plateau. Some in vitro experiments of various authors with higher doses of low LET radiations, up to about 400 mGy have found dose responses with steps. (author)

  12. Modified Exponential (MOE) Models: statistical Models for Risk Estimation of Low dose Rate Radiation

    International Nuclear Information System (INIS)

    Ogata, H.; Furukawa, C.; Kawakami, Y.; Magae, J.

    2004-01-01

    Simultaneous inclusion of dose and dose-rate is required to evaluate the risk of long term irradiation at low dose-rates, since biological responses to radiation are complex processes that depend both on irradiation time and total dose. Consequently, it is necessary to consider a model including cumulative dose,dose-rate and irradiation time to estimate quantitative dose-response relationship on the biological response to radiation. In this study, we measured micronucleus formation and (3H) thymidine uptake in U2OS, human osteosarcoma cell line, as indicators of biological response to gamma radiation. Cells were exposed to gamma ray in irradiation room bearing 50,000 Ci 60Co. After irradiation, they were cultured for 24h in the presence of cytochalasin B to block cytokinesis, and cytoplasm and nucleus were stained with DAPI and propidium iodide. The number of binuclear cells bearing a micronucleus was counted under a florescence microscope. For proliferation inhibition, cells were cultured for 48 h after the irradiation and (3h) thymidine was pulsed for 4h before harvesting. We statistically analyzed the data for quantitative evaluation of radiation risk at low dose/dose-rate. (Author)

  13. Biological stress response terminology: Integrating the concepts of adaptive response and preconditioning stress within a hormetic dose-response framework

    International Nuclear Information System (INIS)

    Calabrese, Edward J.; Bachmann, Kenneth A.; Bailer, A. John; Bolger, P. Michael; Borak, Jonathan; Cai, Lu; Cedergreen, Nina; Cherian, M. George; Chiueh, Chuang C.; Clarkson, Thomas W.; Cook, Ralph R.; Diamond, David M.; Doolittle, David J.; Dorato, Michael A.; Duke, Stephen O.; Feinendegen, Ludwig; Gardner, Donald E.; Hart, Ronald W.; Hastings, Kenneth L.; Hayes, A. Wallace; Hoffmann, George R.; Ives, John A.; Jaworowski, Zbigniew; Johnson, Thomas E.; Jonas, Wayne B.; Kaminski, Norbert E.; Keller, John G.; Klaunig, James E.; Knudsen, Thomas B.; Kozumbo, Walter J.; Lettieri, Teresa; Liu, Shu-Zheng; Maisseu, Andre; Maynard, Kenneth I.; Masoro, Edward J.; McClellan, Roger O.; Mehendale, Harihara M.; Mothersill, Carmel; Newlin, David B.; Nigg, Herbert N.; Oehme, Frederick W.; Phalen, Robert F.; Philbert, Martin A.; Rattan, Suresh I.S.; Riviere, Jim E.; Rodricks, Joseph; Sapolsky, Robert M.; Scott, Bobby R.; Seymour, Colin; Sinclair, David A.; Smith-Sonneborn, Joan; Snow, Elizabeth T.; Spear, Linda; Stevenson, Donald E.; Thomas, Yolene; Tubiana, Maurice; Williams, Gary M.; Mattson, Mark P.

    2007-01-01

    Many biological subdisciplines that regularly assess dose-response relationships have identified an evolutionarily conserved process in which a low dose of a stressful stimulus activates an adaptive response that increases the resistance of the cell or organism to a moderate to severe level of stress. Due to a lack of frequent interaction among scientists in these many areas, there has emerged a broad range of terms that describe such dose-response relationships. This situation has become problematic because the different terms describe a family of similar biological responses (e.g., adaptive response, preconditioning, hormesis), adversely affecting interdisciplinary communication, and possibly even obscuring generalizable features and central biological concepts. With support from scientists in a broad range of disciplines, this article offers a set of recommendations we believe can achieve greater conceptual harmony in dose-response terminology, as well as better understanding and communication across the broad spectrum of biological disciplines

  14. Theory of thermoluminescence gamma dose response: The unified interaction model

    International Nuclear Information System (INIS)

    Horowitz, Y.S.

    2001-01-01

    We describe the development of a comprehensive theory of thermoluminescence (TL) dose response, the unified interaction model (UNIM). The UNIM is based on both radiation absorption stage and recombination stage mechanisms and can describe dose response for heavy charged particles (in the framework of the extended track interaction model - ETIM) as well as for isotropically ionising gamma rays and electrons (in the framework of the TC/LC geminate recombination model) in a unified and self-consistent conceptual and mathematical formalism. A theory of optical absorption dose response is also incorporated in the UNIM to describe the radiation absorption stage. The UNIM is applied to the dose response supralinearity characteristics of LiF:Mg,Ti and is especially and uniquely successful in explaining the ionisation density dependence of the supralinearity of composite peak 5 in TLD-100. The UNIM is demonstrated to be capable of explaining either qualitatively or quantitatively all of the major features of TL dose response with many of the variable parameters of the model strongly constrained by ancilliary optical absorption and sensitisation measurements

  15. Cytogenetic characterization of low-dose hyper-radiosensitivity in Cobalt-60 irradiated human lymphoblastoid cells

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Gnanada S. [Department of Biological Sciences, Wayne State University, Detroit, MI 48202 (United States); Joiner, Michael C. [Department of Radiation Oncology, Wayne State University, Detroit, MI 48201 (United States); Tucker, James D., E-mail: jtucker@biology.biosci.wayne.edu [Department of Biological Sciences, Wayne State University, Detroit, MI 48202 (United States)

    2014-12-15

    Highlights: • Human cells were irradiated in G1 or G2 and evaluated for micronuclei and bridges. • Cells irradiated in G2 but not in G1 exhibit low dose hyper-radiosensitivity. • Response curves of cells irradiated in G2 do not fit a linear-no-threshold model. • Response curves of cells irradiated in G1 fit a linear-no-threshold model. - Abstract: The dose-effect relationships of cells exposed to ionizing radiation are frequently described by linear quadratic (LQ) models over an extended dose range. However, many mammalian cell lines, when acutely irradiated in G2 at doses ≤0.3 Gy, show hyper-radiosensitivity (HRS) as measured by reduced clonogenic cell survival, thereby indicating greater cell lethality than is predicted by extrapolation from high-dose responses. We therefore hypothesized that the cytogenetic response in G2 cells to low doses would also be steeper than predicted by LQ extrapolation from high doses. We tested our hypothesis by exposing four normal human lymphoblastoid cell lines to 0–400 cGy of Cobalt-60 gamma radiation. The cytokinesis block micronucleus assay was used to determine the frequencies of micronuclei and nucleoplasmic bridges. To characterize the dependence of the cytogenetic damage on dose, univariate and multivariate regression analyses were used to compare the responses in the low- (HRS) and high-dose response regions. Our data indicate that the slope of the response for all four cell lines at ≤20 cGy during G2 is greater than predicted by an LQ extrapolation from the high-dose responses for both micronuclei and bridges. These results suggest that the biological consequences of low-dose exposures could be underestimated and may not provide accurate risk assessments following such exposures.

  16. Biological dose assessment of 15 victims in Haerbin radiation accident

    International Nuclear Information System (INIS)

    Liu, Jian-xiang; Huang, Min-yan; Ruan, Jian-lei; Bai, Yu-shu; Xu, Su

    2008-01-01

    unstable aberrations were analyzed and biological dose was assessed according to the dose-effect curves built by our lab member. For micronucleus analysis, blood were added cytochalasin-B after culturing 40 hours. The doses were assessed according to the dose-effect curves built by our lab member. According to a human lymphocyte chromosome aberration and micronucleus analysis, the estimated maximum irradiation dose of 3 exposed patients is lower than 2 Gy, equal to the dose of once uneven total-body irradiation. In vitro dose-response calibration curves for (60)Co gamma rays have been established for unstable chromosome aberrations in human peripheral blood lymphocytes. The observed dose-response data were fitted to a linear quadratic model. The calibration curve parameters were used to estimate the equivalent whole-body dose and dose to the irradiated region in partial body irradiation of cancer patients. The derived partial body doses and fractions of lymphocytes irradiated were in agreement with those estimated from the radiotherapy regimes. (author)

  17. The high dose response of silicon carbide MESFET; Reponse d'un transistor MESFET SiC irradie a de tres fortes doses cumulees

    Energy Technology Data Exchange (ETDEWEB)

    Brisset, C.; Picard, C.; Joffre, F. [CEA Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire, LETI, 91 - Gif-sur-Yvette (France); Noblanc, O.; Brylinski, C. [Thomson-CSF Lab. Central de Recherches, 91 - Orsay (France)

    1999-07-01

    The performance of MESFET-SiC transistors submitted to {sup 60}Co gamma radiation has been studied. MESFETs irradiated in the passing mode present a satisfactorily behaviour till cumulated dose below 10 MGy(Si). The off-state operating mode is the most unfavourable, in this case a complete loss of functionality was observed, followed by a slow comeback to an almost normal functioning after several months of rest. (A.C.)

  18. The dose-response analysis between BMI and common chronic diseases in northeast China.

    Science.gov (United States)

    Yu, Jianxing; Tao, Yuchun; Dou, Jing; Ye, Junsen; Yu, Yaqin; Jin, Lina

    2018-03-09

    High body mass index (BMI) predisposes to several chronic diseases, but a large-scale systematic and detailed study of dose-response relationship between BMI and chronic diseases has not been reported previously. In this study, we aimed to investigate the relationship between BMI and 3 chronic diseases (hypertension, dyslipidemia and MetS) in northeast China. A sample of 16412 participants aged 18~79 years old were included in Jilin province in 2012. The lambda-mu-sigma (LMS) method was applied to examine the trend of BMI by age, and the restricted cubic splines were used to investigate the non-linear associations (dose-response curve) between BMI and chronic diseases. It was pointed out that BMI increased rapidly when young, then kept steady in middle age, and finally declined slowly in old age, and accordingly age was divided into 3 segments, which were different by gender. The odds ratios (ORs) of BMI for the chronic diseases increased relatively slowly when young, then increased dramatically in middle-age and old population, especially for men. Further, the ORs of BMI among non-smokers were lower than those among smokers, and the same trend was shown to be more apparent among drinkers and non-drinkers. The risk of BMI for common chronic diseases increased dramatically in middle-aged, especially for men with drinking and smoking habits.

  19. Multifraction dose response of growing and resting phase hair follicles

    International Nuclear Information System (INIS)

    Vegesna, V.; Withers, H.R.

    1987-01-01

    It has been established in both the clinic and the laboratory that there is a differentiation response to changes in dose per fraction in early and late responding tissues. To study one possible biological reason for differences in early and late responses. The authors selected one kind of cellular entity, the hair follicle, in two different phases of mitotic activity. The follicles are usually in a resting phase (7-12 wks), but mitotic activity can be initiated by plucking the club hairs. This was done on one half of the thorax and then exposing mice to doses of radiation (cesium gamma-ray). Dose responses for epilation between growing (early) and resting (late) follicles were compared for the same mouse. The fractionated response was studied by reducing the dose down to 2.5 Gy/fx. As the literature suggests, the total dose tolerated by a resting (late) follicle increased more than that for a growing (early) follicle

  20. Cisatracurium dose–response relationship in patients with chronic liver disease

    Directory of Open Access Journals (Sweden)

    Mohamed Z. Ali

    2014-04-01

    Results: The preoperative laboratory parameters showed statistically significant differences between the two groups regarding serum albumin, total bilirubin, ALT, AST, PT, PC and INR. The operative data showed statistically insignificant difference between the two groups regarding the 1st dose response (p = 0.152, the estimated ED80 (p = 0.886 and the calculated 2nd dose (p = 0.886 and statistically significant differences between the two groups regarding the 2nd dose response (p = 0.006, the measured ED50 (p = 0.010 and the measured ED95 (p = 0.001. In conclusion, the measured ED50 and ED95 through two-dose dose–response curve technique were clinically insignificant from using the single-dose technique. The dose–response curve of cisatracurium in patients with chronic liver disease was clinically insignificant in comparison with healthy subjects.

  1. Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

    Science.gov (United States)

    Yang, Shu; Han, Shou-Hong; Lu, Zhen-Hua

    2014-01-01

    It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a “soft” outer face and a “hard” inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances. PMID:25126606

  2. Dynamic response and optimal design of curved metallic sandwich panels under blast loading.

    Science.gov (United States)

    Qi, Chang; Yang, Shu; Yang, Li-Jun; Han, Shou-Hong; Lu, Zhen-Hua

    2014-01-01

    It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a "soft" outer face and a "hard" inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

  3. Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

    Directory of Open Access Journals (Sweden)

    Chang Qi

    2014-01-01

    Full Text Available It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a “soft” outer face and a “hard” inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

  4. Dose-response relationship between cigarette smoking and site-specific cancer risk: protocol for a systematic review with an original design combining umbrella and traditional reviews.

    Science.gov (United States)

    Lugo, Alessandra; Bosetti, Cristina; Peveri, Giulia; Rota, Matteo; Bagnardi, Vincenzo; Gallus, Silvano

    2017-11-01

    Only a limited number of meta-analyses providing risk curve functions of dose-response relationships between various smoking-related variables and cancer-specific risk are available. To identify all relevant original publications on the issue, we will conduct a series of comprehensive systematic reviews based on three subsequent literature searches: (1) an umbrella review, to identify meta-analyses, pooled analyses and systematic reviews published before 28 April 2017 on the association between cigarette smoking and the risk of 28 (namely all) malignant neoplasms; (2) for each cancer site, an updated review of original publications on the association between cigarette smoking and cancer risk, starting from the last available comprehensive review identified through the umbrella review; and (3) a review of all original articles on the association between cigarette smoking and site-specific cancer risk included in the publications identified through the umbrella review and the updated reviews. The primary outcomes of interest will be (1) the excess incidence/mortality of various cancers for smokers compared with never smokers; and (2) the dose-response curves describing the association between smoking intensity, duration and time since stopping and incidence/mortality for various cancers. For each cancer site, we will perform a meta-analysis by pooling study-specific estimates for smoking status. We will also estimate the dose-response curves for other smoking-related variables through random-effects meta-regression models based on a non-linear dose-response relationship framework. Ethics approval is not required for this study. Main results will be published in peer-reviewed journals and will also be included in a publicly available website. We will provide therefore the most complete and updated estimates on the association between various measures of cigarette smoking and site-specific cancer risk. This will allow us to obtain precise estimates on the cancer burden

  5. Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

    Science.gov (United States)

    Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

    2001-01-01

    The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

  6. Pegylated interferon fractal pharmacokinetics: individualized dosing for hepatitis C virus infection.

    Science.gov (United States)

    Jain, Mamta K; Pasipanodya, Jotam G; Alder, Lara; Lee, William M; Gumbo, Tawanda

    2013-03-01

    Despite recent advances in hepatitis C virus (HCV) therapeutics, the combination of pegylated interferon and ribavirin (PEGIFN/RBV) remains the cornerstone of treatment. Optimization and individualization of PEGIFN dosing could improve outcomes. Week one PEGIFN serum concentrations in 42 HCV genotype 1-infected patients treated with conventional PEGIFN/RBV were analyzed using multicompartmental pharmacokinetic models. For each patient, pharmacokinetic parameter estimates, weight, age, interleukin-28B (IL-28B) single-nucleotide polymorphism, CD4 count, baseline HCV RNA, gender, race, and HIV status were examined using classification and regression tree analysis to identify factors predictive of sustained viral response (SVR). Survival analysis was performed to compare the time to undetectable viral load in patients with and without the highest scoring predictor. PEGIFN concentrations varied at least 87-fold. Pharmacokinetics were best described by a two-compartment model with an 8.4-h absorption lag. Patient weight correlated with PEGIFN systemic clearance based on fractal geometry relationships. SVR was achieved in 36% of patients; a PEGIFN cumulative 1-week area under the curve (AUC) of ≤0.79 mg · h/liter scored highest in predicting poor response, followed by a weight of ≥93.7 kg. Patients with a PEGIFN AUC of >0.79 mg · h/liter achieved undetectable viral load more rapidly than those with a lower AUC (hazard ratio, 1.63; 95% confidence interval, 1.21 to 2.04). PEGIFN exhibits wide pharmacokinetic variability, mainly driven by patient weight, so that the standard dose may not reach levels needed to achieve SVR. Optimizing dose to patient weight and PEGIFN AUC in the first week offers a solution to improve SVR and to potentially shorten duration of therapy.

  7. Critical target and dose and dose-rate responses for the induction of chromosomal instability by ionizing radiation

    Science.gov (United States)

    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), 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.

  8. Analysis of variation in calibration curves for Kodak XV radiographic film using model-based parameters.

    Science.gov (United States)

    Hsu, Shu-Hui; Kulasekere, Ravi; Roberson, Peter L

    2010-08-05

    Film calibration is time-consuming work when dose accuracy is essential while working in a range of photon scatter environments. This study uses the single-target single-hit model of film response to fit the calibration curves as a function of calibration method, processor condition, field size and depth. Kodak XV film was irradiated perpendicular to the beam axis in a solid water phantom. Standard calibration films (one dose point per film) were irradiated at 90 cm source-to-surface distance (SSD) for various doses (16-128 cGy), depths (0.2, 0.5, 1.5, 5, 10 cm) and field sizes (5 × 5, 10 × 10 and 20 × 20 cm²). The 8-field calibration method (eight dose points per film) was used as a reference for each experiment, taken at 95 cm SSD and 5 cm depth. The delivered doses were measured using an Attix parallel plate chamber for improved accuracy of dose estimation in the buildup region. Three fitting methods with one to three dose points per calibration curve were investigated for the field sizes of 5 × 5, 10 × 10 and 20 × 20 cm². The inter-day variation of model parameters (background, saturation and slope) were 1.8%, 5.7%, and 7.7% (1 σ) using the 8-field method. The saturation parameter ratio of standard to 8-field curves was 1.083 ± 0.005. The slope parameter ratio of standard to 8-field curves ranged from 0.99 to 1.05, depending on field size and depth. The slope parameter ratio decreases with increasing depth below 0.5 cm for the three field sizes. It increases with increasing depths above 0.5 cm. A calibration curve with one to three dose points fitted with the model is possible with 2% accuracy in film dosimetry for various irradiation conditions. The proposed fitting methods may reduce workload while providing energy dependence correction in radiographic film dosimetry. This study is limited to radiographic XV film with a Lumisys scanner.

  9. Dose-response models for the radiation-induction of skin tumours in mice

    International Nuclear Information System (INIS)

    Papworth, D.G.; Hulse, E.V.

    1983-01-01

    Extensive data on radiation-induced skin tumours in mice were examined using 8 models, all based on the concept that incidences of radiation-induced tumours depend on a combination of two radiation effects: a tumour induction process and the loss of reproductive integrity by the potential tumour cells. Models with and without a threshold were used, in spite of theoretical objections to threshold models. No model fitted well both the epidermal and the dermal tumour data and models which proved to be statistically satisfactory for some of the data were rejected for biological reasons. It is concluded that, for skin tumours, dose-response curves depending on a combination of cancer induction and loss of cellular reproductive integrity are distorted by some special, relatively radio-resistant, factor which we have previously postulated as being involved in radiation skin carcinogenesis. (author)

  10. Task-based detectability comparison of exponential transformation of free-response operating characteristic (EFROC) curve and channelized Hotelling observer (CHO)

    Science.gov (United States)

    Khobragade, P.; Fan, Jiahua; Rupcich, Franco; Crotty, Dominic J.; Gilat Schmidt, Taly

    2016-03-01

    This study quantitatively evaluated the performance of the exponential transformation of the free-response operating characteristic curve (EFROC) metric, with the Channelized Hotelling Observer (CHO) as a reference. The CHO has been used for image quality assessment of reconstruction algorithms and imaging systems and often it is applied to study the signal-location-known cases. The CHO also requires a large set of images to estimate the covariance matrix. In terms of clinical applications, this assumption and requirement may be unrealistic. The newly developed location-unknown EFROC detectability metric is estimated from the confidence scores reported by a model observer. Unlike the CHO, EFROC does not require a channelization step and is a non-parametric detectability metric. There are few quantitative studies available on application of the EFROC metric, most of which are based on simulation data. This study investigated the EFROC metric using experimental CT data. A phantom with four low contrast objects: 3mm (14 HU), 5mm (7HU), 7mm (5 HU) and 10 mm (3 HU) was scanned at dose levels ranging from 25 mAs to 270 mAs and reconstructed using filtered backprojection. The area under the curve values for CHO (AUC) and EFROC (AFE) were plotted with respect to different dose levels. The number of images required to estimate the non-parametric AFE metric was calculated for varying tasks and found to be less than the number of images required for parametric CHO estimation. The AFE metric was found to be more sensitive to changes in dose than the CHO metric. This increased sensitivity and the assumption of unknown signal location may be useful for investigating and optimizing CT imaging methods. Future work is required to validate the AFE metric against human observers.

  11. Proposal of a probabilistic dose-response model

    International Nuclear Information System (INIS)

    Barrachina, M.

    1997-01-01

    A biologically updated dose-response model is presented as an alternative to the linear-quadratic model currently in use for cancer risk assessment. The new model is based on the probability functions for misrepair and/or unrepair of DNA lesions, in terms of the radiation damage production rate in the cell (supposedly, a stem cell) and its repair-rate constant. The model makes use, interpreting it on the basis of misrepair probabilities, of the ''dose and dose-rate effectiveness factor'' of ICRP, and provides the way for a continuous extrapolation between the high and low dose-rate regions, ratifying the ''linear non-threshold hypothesis'' as the main option. Anyhow, the model throws some doubts about the additive property of the dose. (author)

  12. Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2004

    Energy Technology Data Exchange (ETDEWEB)

    Diefenderfer, Heida L.; Roegner, Curtis; Thom, Ronald M.; Dawley, Earl M.; Whiting, Allan H.; Johnson, Gary E.; Sobocinski, Kathryn L.; Anderson, Michael G.; Ebberts, Blaine

    2005-12-15

    The restoration of wetland salmon habitat in the tidal portion of the Columbia River is occurring at an accelerating pace and is anticipated to improve habitat quality and effect hydrological reconnection between existing and restored habitats. Currently multiple groups are applying a variety of restoration strategies in an attempt to emulate historic estuarine processes. However, the region lacks both a standardized means of evaluating the effectiveness of individual projects as well as methods for determining the cumulative effects of all restoration projects on a regional scale. This project is working to establish a framework to evaluate individual and cumulative ecosystem responses to restoration activities in order to validate the effectiveness of habitat restoration activities designed to benefit salmon through improvements to habitat quality and habitat opportunity (i.e. access) in the Columbia River from Bonneville Dam to the ocean. The review and synthesis of approaches to measure the cumulative effects of multiple restoration projects focused on defining methods and metrics of relevance to the CRE, and, in particular, juvenile salmon use of this system. An extensive literature review found no previous study assessing the cumulative effects of multiple restoration projects on the fundamental processes and functions of a large estuarine system, although studies are underway in other large land-margin ecosystems including the Florida Everglades and the Louisiana coastal wetlands. Literature from a variety of scientific disciplines was consulted to identify the ways that effects can accumulate (e.g., delayed effects, cross-boundary effects, compounding effects, indirect effects, triggers and thresholds) as well as standard and innovative tools and methods utilized in cumulative effects analyses: conceptual models, matrices, checklists, modeling, trends analysis, geographic information systems, carrying capacity analysis, and ecosystem analysis. Potential

  13. Low-dose radiation-induced adaptive response in bone marrow cells of mice

    International Nuclear Information System (INIS)

    Farooqi, Zeba; Kesavan, P.C.

    1993-01-01

    Using bone marrow cells of whole body irradiated mice, the cytogenetic adaptive response induced by low conditioning doses of gamma-rays was investigated. The conditioning doses (0.025 and 0.05 Gy) were given at a dose-rate of 1.67 Gy/min. The challenging dose of 1 Gy was given at a dose-rate of 0.045 Gy/s. The challenging dose was given at different time intervals after the conditioning dose. The time intervals between the conditioning dose and challenging dose were 2, 7.5, 13, 18.5 and 24 h. When the time interval between the conditioning dose and the challenging dose was 2 h, both conditioning doses (0.025 and 0.05 Gy) reduced the frequency of MNPCEs and chromosomal aberrations in the bone marrow cells. The data collected at different time intervals (7.5, 13, 18.5 h) reveal that the radioadaptive response persisted for a longer time when the lower conditioning dose (0.025 Gy) was given. With the higher conditioning dose (0.05 Gy), the radioadaptive response disappeared after a time interval of 13 h. When the time interval between the conditioning dose and the challenging doses was 18.5 or 24 h, only the lower conditioning dose appeared effective in inducing the radioadaptive response

  14. Evaluation of Different Dose-Response Models for High Hydrostatic Pressure Inactivation of Microorganisms

    Directory of Open Access Journals (Sweden)

    Sencer Buzrul

    2017-09-01

    Full Text Available Modeling of microbial inactivation by high hydrostatic pressure (HHP requires a plot of the log microbial count or survival ratio versus time data under a constant pressure and temperature. However, at low pressure and temperature values, very long holding times are needed to obtain measurable inactivation. Since the time has a significant effect on the cost of HHP processing it may be reasonable to fix the time at an appropriate value and quantify the inactivation with respect to pressure. Such a plot is called dose-response curve and it may be more beneficial than the traditional inactivation modeling since short holding times with different pressure values can be selected and used for the modeling of HHP inactivation. For this purpose, 49 dose-response curves (with at least 4 log10 reduction and ≥5 data points including the atmospheric pressure value (P = 0.1 MPa, and with holding time ≤10 min for HHP inactivation of microorganisms obtained from published studies were fitted with four different models, namely the Discrete model, Shoulder model, Fermi equation, and Weibull model, and the pressure value needed for 5 log10 (P5 inactivation was calculated for all the models above. The Shoulder model and Fermi equation produced exactly the same parameter and P5 values, while the Discrete model produced similar or sometimes the exact same parameter values as the Fermi equation. The Weibull model produced the worst fit (had the lowest adjusted determination coefficient (R2adj and highest mean square error (MSE values, while the Fermi equation had the best fit (the highest R2adj and lowest MSE values. Parameters of the models and also P5 values of each model can be useful for the further experimental design of HHP processing and also for the comparison of the pressure resistance of different microorganisms. Further experiments can be done to verify the P5 values at given conditions. The procedure given in this study can also be extended for

  15. Aspects of pre-dose and other luminescence phenomena in quartz absorbed dose estimation

    International Nuclear Information System (INIS)

    Adamiec, G.

    2000-01-01

    The understanding of all luminescence processes occurring in quartz is of paramount importance in the further development of robust absorbed dose estimation techniques (for the purpose of dating and retrospective dosimetry). The findings presented in this thesis, aid future improvements of absorbed dose estimation techniques using quartz by presenting investigations in the following areas: 1) interpretation of measurement results, 2) numerical modelling of luminescence in quartz, 3) phenomena needing inclusion in future physical models of luminescence. In the first part, the variability of properties of single quartz grains is examined. Through empirical and theoretical considerations, investigations are made of various problems of measurements of luminescence using multi-grain aliquots, and specifically areas where the heterogeneity of the sample at the inter-grain level may be misinterpreted at the multi-grain-aliquot level. The results obtained suggest that the heterogeneity of samples is often overlooked, and that such differences can have a profound influence on the interpretation of measurement results. Discussed are the shape of TL glow curves, OSL decay curves, dose response curves (including consequences for using certain signals as proxies for others), normalisation procedures and D E estimation techniques. Further, a numerical model of luminescence is proposed, which includes multiple R-centres and is used to describe the pre-dose sensitisation in quartz. The numerical model exhibits a broad-scale behaviour observed experimentally in a sample of annealed quartz. The shapes of TAC for lower (20 Gy) and higher doses (1 kGy) and the evolution with temperature of the isothermal sensitisation curves are qualitatively matched for the empirical and numerical systems. In the third area, a preliminary investigation of the properties of the '110 deg. C peak' in the 550 nm emission band, in annealed quartz is presented. These properties are in sharp contrast with

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Levy, Richard P. [Univ. of California, Berkeley, CA (United States)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Levy, R.P.

    1991-12-01

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

  19. Dose-response of photographic emulsions under gamma irradiation

    International Nuclear Information System (INIS)

    Tran Dai Nghiep; Do Thi Nguyet Minh; Le Van Vinh

    2003-01-01

    Photographic emulsion is irradiated under gamma rays irradiation of 137 Cs in the IAEA/WHO secondary standard dosimetry laboratory. Dose-response of the film is established. The sensitivity of the film is determined. The dose-rate effect is studied. (author)

  20. A method for the rapid generation of nonsequential light-response curves of chlorophyll fluorescence.

    Science.gov (United States)

    Serôdio, João; Ezequiel, João; Frommlet, Jörg; Laviale, Martin; Lavaud, Johann

    2013-11-01

    Light-response curves (LCs) of chlorophyll fluorescence are widely used in plant physiology. Most commonly, LCs are generated sequentially, exposing the same sample to a sequence of distinct actinic light intensities. These measurements are not independent, as the response to each new light level is affected by the light exposure history experienced during previous steps of the LC, an issue particularly relevant in the case of the popular rapid light curves. In this work, we demonstrate the proof of concept of a new method for the rapid generation of LCs from nonsequential, temporally independent fluorescence measurements. The method is based on the combined use of sample illumination with digitally controlled, spatially separated beams of actinic light and a fluorescence imaging system. It allows the generation of a whole LC, including a large number of actinic light steps and adequate replication, within the time required for a single measurement (and therefore named "single-pulse light curve"). This method is illustrated for the generation of LCs of photosystem II quantum yield, relative electron transport rate, and nonphotochemical quenching on intact plant leaves exhibiting distinct light responses. This approach makes it also possible to easily characterize the integrated dynamic light response of a sample by combining the measurement of LCs (actinic light intensity is varied while measuring time is fixed) with induction/relaxation kinetics (actinic light intensity is fixed and the response is followed over time), describing both how the response to light varies with time and how the response kinetics varies with light intensity.

  1. Optimal dose-response relationships in voice therapy.

    Science.gov (United States)

    Roy, Nelson

    2012-10-01

    Like other areas of speech-language pathology, the behavioural management of voice disorders lacks precision regarding optimal dose-response relationships. In voice therapy, dosing can presumably vary from no measurable effect (i.e., no observable benefit or adverse effect), to ideal dose (maximum benefit with no adverse effects), to doses that produce toxic or harmful effects on voice production. Practicing specific vocal exercises will inevitably increase vocal load. At ideal doses, these exercises may be non-toxic and beneficial, while at intermediate or high doses, the same exercises may actually be toxic or damaging to vocal fold tissues. In pharmacology, toxicity is a critical concept, yet it is rarely considered in voice therapy, with little known regarding "effective" concentrations of specific voice therapies vs "toxic" concentrations. The potential for vocal fold tissue damage related to overdosing on specific vocal exercises has been under-studied. In this commentary, the issue of dosing will be explored within the context of voice therapy, with particular emphasis placed on possible "overdosing".

  2. Effect of high-dose irradiation on the optically stimulated luminescence of Al{sub 2}O{sub 3}:C

    Energy Technology Data Exchange (ETDEWEB)

    Yukihara, E.G. E-mail: yukihara@thor.phy.okstate.edu; Whitley, V.H.; McKeever, S.W.S. E-mail: swsm@okstate.edu; Akselrod, A.E.; Akselrod, M.S

    2004-06-01

    This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al{sub 2}O{sub 3}:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F{sup +}-centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al{sub 2}O{sub 3}:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed.

  3. Differential Kolaviron Attenuated Contractile Responses to Agonists on Isolated Rabbit Aorta in Na+-K+ Pump Blockade.

    Science.gov (United States)

    Uche, O K; Ofeimun, J O

    2017-12-30

    The mechanism of kolaviron-induced vascular smooth muscles (VSMs) responses has not been fullycharacterised. The present study investigated the effect and mode of action of kolaviron a biflavanoid-complex and majorcomponent of Garcinia Kola-fraction on differential contractile responses to agonists-[phenylephrine (PHE) and histamine(HIST)] on VSMs of rabbit isolated aortic rings in K+-free physiological salt solution (KFPSS). Cumulative concentrationresponses to PHE and HIST were examined on 2 mm ring segments of the thoracic aortae which were suspended in 20 mlorgan baths containing physiological salt solution (PSS) for measurement of isometric contractions, at 370C and pH 7.4. Themedium was bubbled with 95% O2, 5% CO2, and rings were given an initial load of 1g. Cumulative contractile responses tothe agonists were studied in normal PSS (control) and following 30 minutes exposure to K+-free PSS and/or 800µg/mLkolaviron. Contractile responses were expressed as percentage of 80 mM K+ contractions in normal PSS. Maximalcontractions (Emax) induced by PHE and HIST compared with high K+ contraction in the various preparations weredifferentially altered following exposure to K+-free or 800µg/mL kolaviron in both intact (+E) and endotheliumdenuded (-E) rings. Based on the efficacy (Emax) and potency (EC50) values for the dose-response curves of the agonists, it isconcluded that enhanced differential contractile responses elicited by agonists in K+-free PSS were significantly attenuatedby kolaviron concentration-dependently. This observation probably suggests the existence of another pathway of kolavironmode of action in vascular smooth muscle reactivity.

  4. Investigation of the characteristics of thermoluminescence glow curves of natural hydrothermal quartz from Hakkari area in Turkey

    International Nuclear Information System (INIS)

    Topaksu, M.; Yüksel, M.; Dogan, T.; Nur, N.; Akkaya, R.; Yegingil, Z.; Topak, Y.

    2013-01-01

    In this study the dosimetric characteristics of some natural hydrothermal quartz (NHQ) samples collected from Hakkari were investigated by using the thermoluminescence (TL) technique for the purpose of determining whether they are suitable as dosimetric materials or not and calculating the kinetic parameters. The experiments carried out can be outlined as: analyzing TL glow curves of NHQ; determining the annealing conditions; the effects of pre-irradiation annealing procedures on TL sensitivity; the investigation of the characteristics of TL glow curves obtained after annealing the samples; determination of the trap parameters with the computerized glow curve deconvolution (CGCD) method and the peak shape (PS) method. The obtained results showed that the trap depths and the frequency factor values are consistent with the literature. The studied samples have linear dose responses for the absorbed doses ranging between ∼6.689 Gy and ∼301 Gy. In conclusion, the examined quartz samples can be used as dosimetric materials in high dose applications

  5. A thermoluminescence study of mineral silicates extracted from herbs in the dose range 0.5–5 Gy

    International Nuclear Information System (INIS)

    Della Monaca, Sara; Fattibene, Paola; Bortolin, Emanuela

    2013-01-01

    The presence of silicates in many personal objects suggests their potential use at low dose as fortuitous dosimeter in an accidental radiological exposure, when conventional dosimetry is not available. The goal of the present work is the dosimetric characterization of mineral silicates extracted from the plant Hibiscus Sabdariffa L, known as Jamaica flower, in the dose range 0.5–5 Gy. By studying the radiation-induced signal in time, the temperature integration region between 210 °C and 250 °C was found to be the most stable and also reduced the effects of thermal fading in the dose reconstruction process; the dose response curve was linear between 0.5 Gy and 5 Gy. By checking the change in sensitivity after repeated exposures to ionizing radiations and to high temperature heating, no variation in the glow curve shape or peak intensities were detected. To eliminate a pre-existing background signal, all the characterization measurements were performed with aliquots “annealed” by a preliminary readout of the TL. - Highlights: • Glow curves change in shape and intensity just in the first 3 days after irradiation. • The dose response is linear in the dose range 0.5–5 Gy. • The curve shape or intensity don't change after repeated exposures and heatings. • Encouraging results were obtained in the dose recovery test

  6. Prediction of response to continuous irradiation at low dose rate for repeated administrations in radiotherapy with beta emitters

    International Nuclear Information System (INIS)

    Calderon, Carlos; Gonzalez, Joaquin; Quesada, Waldo

    2009-01-01

    The absorbed dose to tumors after systemic administration of radiopharmaceuticals is not sufficient to achieve acceptable levels of probability of tumor control without compromising on critical tissue toxicity (kidney and / or bone marrow (BM)). There are reports of trials with multiple administrations, about tolerance level inter-administration intervals to allow recovery of the BM, with good results. The biokinetic behavior of some radiopharmaceuticals known makes possible the application of several administrations with short intervals of time.It is the present work combines two kinetic models of tumor growth and cell kinetics in the BM for predicting the response to continuous irradiation at low dose rate. The estimation of the effects of irradiation on tumor and kidneys was done using a formulation of the linear-quadratic model functions suitable for dose rate and multi-exponential repair. The estimation of the response in WB performed using a compartmental model previously reported. The absorbed dose to organs were calculated using the MIRD formulation taking into account the effect of irradiation cross. Biokinetic data were used for therapeutic radiopharmaceuticals 90Y, 131I and 177Lu, as well as radiobiological parameters reported for experimental animals. The effect on the response by the variation of inter-administration interval in slow-growing tumors and fast, so as the radiosensitive and radioresistant tumors. You can set conditions irradiation to an acceptable level of thrombocytopenia (onset and duration of the minimum in the curve) and renal irradiation below the limit of tolerance. It is possible to design experiments evaluation of therapeutic radiopharmaceuticals with a greater degree of refinement. (author)

  7. Optimal Clinical Doses of Faropenem, Linezolid, and Moxifloxacin in Children With Disseminated Tuberculosis: Goldilocks.

    Science.gov (United States)

    Srivastava, Shashikant; Deshpande, Devyani; Pasipanodya, Jotam; Nuermberger, Eric; Swaminathan, Soumya; Gumbo, Tawanda

    2016-11-01

     When treated with the same antibiotic dose, children achieve different 0- to 24-hour area under the concentration-time curves (AUC 0-24 ) because of maturation and between-child physiological variability on drug clearance. Children are also infected by Mycobacterium tuberculosis isolates with different antibiotic minimum inhibitory concentrations (MICs). Thus, each child will achieve different AUC 0-24 /MIC ratios when treated with the same dose.  We used 10 000-subject Monte Carlo experiments to identify the oral doses of linezolid, moxifloxacin, and faropenem that would achieve optimal target exposures associated with optimal efficacy in children with disseminated tuberculosis. The linezolid and moxifloxacin exposure targets were AUC 0-24 /MIC ratios of 62 and 122, and a faropenem percentage of time above MIC >60%, in combination therapy. A linezolid AUC 0-24 of 93.4 mg × hour/L was target for toxicity. Population pharmacokinetic parameters of each drug and between-child variability, as well as MIC distribution, were used, and the cumulative fraction of response (CFR) was calculated. We also considered drug penetration indices into meninges, bone, and peritoneum.  The linezolid dose of 15 mg/kg in full-term neonates and infants aged up to 3 months and 10 mg/kg in toddlers, administered once daily, achieved CFR ≥ 90%, with linezolid AUC 0-24 associated with toxicity. The moxifloxacin dose of 25 mg/kg/day achieved a CFR > 90% in infants, but the optimal dose was 20 mg/kg/day in older children. The faropenem medoxomil optimal dosage was 30 mg/kg 3-4 times daily.  The regimen and doses of linezolid, moxifloxacin, and faropenem identified are proposed to be adequate for all disseminated tuberculosis syndromes, whether drug-resistant or -susceptible. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.

  8. Statistical and biophysical aspects of survival curve

    International Nuclear Information System (INIS)

    Kellerer, A.M.

    1980-01-01

    Statistic fluctuation in a series of consequently taken survival curves of asynchronous cells of a hamster of the V79 line during X-ray irradiation, are considered. In each of the experiments fluctuations are close to those expected on the basis of the Poisson distribution. The fluctuation of cell sensitivity in different experiments of one series can reach 10%. The normalization of each experiment in mean values permits to obtain the ''idealized'' survival curve. The survival logarithm in this curve is proportional to the absorbed dose and its square only at low radiation doses. Such proportionality in V lab 79 cells in the late S-phase is observed at all doses. Using the microdosimetric approach, the distance where the interaction of radiolysis products or subinjury takes place to make the dependence of injury on the dose non-linear, is determined. In the case of interaction distances of 10-100 nm, the linear component is shown to become comparable in value with the linear injury component at doses of the order of several hundred rad only in the case, when the interaction distance is close to micrometre [ru

  9. On the analysis of Canadian Holstein dairy cow lactation curves using standard growth functions.

    Science.gov (United States)

    López, S; France, J; Odongo, N E; McBride, R A; Kebreab, E; AlZahal, O; McBride, B W; Dijkstra, J

    2015-04-01

    Six classical growth functions (monomolecular, Schumacher, Gompertz, logistic, Richards, and Morgan) were fitted to individual and average (by parity) cumulative milk production curves of Canadian Holstein dairy cows. The data analyzed consisted of approximately 91,000 daily milk yield records corresponding to 122 first, 99 second, and 92 third parity individual lactation curves. The functions were fitted using nonlinear regression procedures, and their performance was assessed using goodness-of-fit statistics (coefficient of determination, residual mean squares, Akaike information criterion, and the correlation and concordance coefficients between observed and adjusted milk yields at several days in milk). Overall, all the growth functions evaluated showed an acceptable fit to the cumulative milk production curves, with the Richards equation ranking first (smallest Akaike information criterion) followed by the Morgan equation. Differences among the functions in their goodness-of-fit were enlarged when fitted to average curves by parity, where the sigmoidal functions with a variable point of inflection (Richards and Morgan) outperformed the other 4 equations. All the functions provided satisfactory predictions of milk yield (calculated from the first derivative of the functions) at different lactation stages, from early to late lactation. The Richards and Morgan equations provided the most accurate estimates of peak yield and total milk production per 305-d lactation, whereas the least accurate estimates were obtained with the logistic equation. In conclusion, classical growth functions (especially sigmoidal functions with a variable point of inflection) proved to be feasible alternatives to fit cumulative milk production curves of dairy cows, resulting in suitable statistical performance and accurate estimates of lactation traits. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  10. Cumulative ionizing radiation exposure in patients with end stage kidney disease: a 6-year retrospective analysis.

    LENUS (Irish Health Repository)

    Coyle, Joe

    2011-08-13

    OBJECTIVE: To quantify cumulative exposure to ionizing radiation in patients with end stage kidney disease (ESKD). To investigate factors which may be independently associated with risk of high cumulative effective dose (CED). MATERIALS AND METHODS: The study had local institutional review board ethical approval. We conducted a retrospective study of 394 period prevalent ESKD patients attending a single tertiary referral centre between 2004 and 2009. Patient demographics were obtained from case records. Details of radiological investigations were obtained from the institutional radiology computerized database. CED was calculated using standard procedure specific radiation levels. High exposure was defined as CED > 50 mSv, an exposure which has been reported to increase cancer mortality by 5%. Data were compared using Pearson χ(2) and Mann-Whitney U test or Kruskal-Wallis tests. RESULTS: 394 patients were followed for a median of 4 years (1518 patient years follow-up). Of these 63% were male. Seventeen percent of patients had a CED of >50 mSv. Computed tomography (CT) accounted for 9% of total radiological studies\\/procedures while contributing 61.4% of total study dose. Median cumulative dose and median dose per patient year were significantly higher in the hemodialysis (HD) group (15.13 and 5.79 mSv, respectively) compared to the post-transplant group (2.9 and 0.52 mSv, respectively) (P < 0.001). CONCLUSION: ESKD patients are at risk of cumulative exposure to significant levels of diagnostic radiation. The majority of this exposure is imparted as a result of CT examinations to patients in the HD group.

  11. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    Directory of Open Access Journals (Sweden)

    Cheng-Ting Shih

    Full Text Available Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM images. The modified N-isopropyl-acrylamide (NIPAM gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM. The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  12. Determination of tolerance dose uncertainties and optimal design of dose response experiments with small animal numbers

    International Nuclear Information System (INIS)

    Karger, C.P.; Hartmann, G.H.

    2001-01-01

    Background: Dose response experiments aim to determine the complication probability as a function of dose. Adjusting the parameters of the frequently used dose response model P(D)=1/[1+(D 50 /D) k ] to the experimental data, 2 intuitive quantities are obtained: The tolerance dose D 50 and the slope parameter k. For mathematical reasons, however, standard statistic software uses a different set of parameters. Therefore, the resulting fit parameters of the statistic software as well as their standard errors have to be transformed to obtain D 50 and k as well as their standard errors. Material and Methods: The influence of the number of dose levels on the uncertainty of the fit parameters is studied by a simulation for a fixed number of animals. For experiments with small animal numbers, statistical artifacts may prevent the determination of the standard errors of the fit parameters. Consequences on the design of dose response experiments are investigated. Results: Explicit formulas are presented, which allow to calculate the parameters D 50 and k as well as their standard errors from the output of standard statistic software. The simulation shows, that the standard errors of the resulting parameters are independent of the number of dose levels, as long as the total number of animals involved in the experiment, remains constant. Conclusion: Statistical artifacts in experiments containing small animal numbers may be prevented by an adequate design of the experiment. For this, it is suggested to select a higher number of dose levels, rather than using a higher number of animals per dose level. (orig.) [de

  13. Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Diefenderfer, Heida L.; Borde, Amy B.; Bryson, Amanda J.; Cameron, April; Coleman, Andre M.; Corbett, C.; Dawley, Earl M.; Ebberts, Blaine D.; Kauffman, Ronald; Roegner, G. Curtis; Russell, Micah T.; Silva, April; Skalski, John R.; Thom, Ronald M.; Vavrinec, John; Woodruff, Dana L.; Zimmerman, Shon A.

    2010-10-26

    This is the sixth annual report of a seven-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the lower Columbia River and estuary (LCRE). The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers Portland District (USACE) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), the Columbia River Estuary Study Taskforce (CREST), and the University of Washington. The goal of the Cumulative Effects Study is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the 235-km-long LCRE. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2009, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tidegate replacement vs. culvert replacement vs. dike breach).

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

    International Nuclear Information System (INIS)

    Schultheiss, Timothy E.

    2008-01-01

    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 α/β 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 α/β = 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 α/β is smaller than usually quoted, but values this small were found in some studies. Using α/β = 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

  15. A review: Development of a microdose model for analysis of adaptive response and bystander dose response behavior.

    Science.gov (United States)

    Leonard, Bobby E

    2008-02-27

    Prior work has provided incremental phases to a microdosimetry modeling program to describe the dose response behavior of the radio-protective adaptive response effect. We have here consolidated these prior works (Leonard 2000, 2005, 2007a, 2007b, 2007c) to provide a composite, comprehensive Microdose Model that is also herein modified to include the bystander effect. The nomenclature for the model is also standardized for the benefit of the experimental cellular radio-biologist. It extends the prior work to explicitly encompass separately the analysis of experimental data that is 1.) only dose dependent and reflecting only adaptive response radio-protection, 2.) both dose and dose-rate dependent data and reflecting only adaptive response radio-protection for spontaneous and challenge dose damage, 3.) only dose dependent data and reflecting both bystander deleterious damage and adaptive response radio-protection (AR-BE model). The Appendix cites the various applications of the model. Here we have used the Microdose Model to analyze the, much more human risk significant, Elmore et al (2006) data for the dose and dose rate influence on the adaptive response radio-protective behavior of HeLa x Skin cells for naturally occurring, spontaneous chromosome damage from a Brachytherapy type (125)I photon radiation source. We have also applied the AR-BE Microdose Model to the Chromosome inversion data of Hooker et al (2004) reflecting both low LET bystander and adaptive response effects. The micro-beam facility data of Miller et al (1999), Nagasawa and Little (1999) and Zhou et al (2003) is also examined. For the Zhou et al (2003) data, we use the AR-BE model to estimate the threshold for adaptive response reduction of the bystander effect. The mammogram and diagnostic X-ray induction of AR and protective BE are observed. We show that bystander damage is reduced in the similar manner as spontaneous and challenge dose damage as shown by the Azzam et al (1996) data. We cite

  16. Bragg Curve, Biological Bragg Curve and Biological Issues in Space Radiation Protection with Shielding

    Science.gov (United States)

    Honglu, Wu; Cucinotta, F.A.; Durante, M.; Lin, Z.; Rusek, A.

    2006-01-01

    The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. To achieve a Bragg curve distribution, we exposed cells to energetic heavy ions with the beam geometry parallel to a monolayer of fibroblasts. Qualitative analyses of gamma-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high linear energy transfer (LET) particle traversal of cells beyond the Bragg peak. A quantitative biological response curve generated for micronuclei (MN) induction across the Bragg curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono-to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results, along with other biological concerns, show that space radiation protection with shielding can be a complicated issue.

  17. Urinary bladder dose-response relationships for patient-reported genitourinary morbidity domains following prostate cancer radiotherapy.

    Science.gov (United States)

    Thor, Maria; Olsson, Caroline; Oh, Jung Hun; Petersen, Stine Elleberg; Alsadius, David; Bentzen, Lise; Pettersson, Niclas; Muren, Ludvig Paul; Høyer, Morten; Steineck, Gunnar; Deasy, Joseph O

    2016-04-01

    Radiotherapy (RT) induced genitourinary (GU) morbidity is typically assessed by physicians as single symptoms or aggregated scores including symptoms from various domains. Here we apply a method to group patient-reported GU symptoms after RT for localized prostate cancer based on their interplay, and study how these relate to urinary bladder dose. Data were taken from two Scandinavian studies (N=207/276) including men treated with external-beam RT (EBRT) to 78/70Gy (2Gy/fraction; median time-to-follow-up: 3.6-6.4y). Within and across cohorts, bladder dose-volume parameters were tested as predictors for GU symptom domains identified from two study-specific questionnaires (35 questions on frequency, incontinence, obstruction, pain, urgency, and sensory symptoms) using univariate and multivariate logistic regression analysis (MVA) with 10-fold cross-validation. Performance was evaluated using Area Under the Receiver Operating Characteristic Curve (Az). For the identified Incontinence (2-5 symptoms), Obstruction (3-5 symptoms), and Urgency (2-7 symptoms) domains, MVA demonstrated that bladder doses close to the prescription doses were the strongest predictors for Obstruction (Az: 0.53-0.57) and Urgency (Az: 0.60). For Obstruction, performance increased for the across cohort analysis (Az: 0.61-0.64). Our identified patient-reported GU symptom domains suggest that high urinary bladder doses, and increased focus on both obstruction and urgency is likely to further add to the understanding of GU tract RT responses. Published by Elsevier Ireland Ltd.

  18. The dose-response relationship for UV-tumorigenesis

    International Nuclear Information System (INIS)

    Gruijl, F.R. de.

    1982-01-01

    The main objective of the investigations was to extend the knowledge on experimental UV-carcinogenesis and to use the experimental results as guidelines for developing a dose-response model for UV-carcinogenesis. The animal experiments carried out were all long-term ones. It was decided that - in anticipation of the data to be obtained - a model for such an assessment should be developed using the experimental results available at the start of the present study (1977). This initial study is presented. The results of two animal experiments are presented, which show that UV radiation is capable of inducing a systemic effect that enhances the de novo formation of UV induced tumors. The results of the main experiment are presented. In this experiment groups of mice were subjected to daily exposure to a certain dose of UV radiation in order to find the dose-response relationship. The relation between the daily dose and the duration of the treatment till the appearance of tumors (for instance, as measured by the yield) was ascertained for tumors of different sizes. It appears that the growth of a tumor is dose-independent, and, therefore, only the initiation of a tumor is dose-dependent. Finally an experiment is presented in which it was measured that, if a mouse is subjected to daily UV exposure, the transmission of the epidermis in the shortwave UV region decreases continuously. This decrease is due to hyperplasia of the epidermis, i.e., thickening of the epidermis by an increase in the number of cells per unit surface area. (Auth.)

  19. Magnetic response of certain curved graphitic geometries

    International Nuclear Information System (INIS)

    Wang, L.; Davids, P.S.; Saxena, A.; Bishop, A.R.

    1992-01-01

    The quasi-particle energy spectra associated with some members of buckyfamily (curved graphitic geometries), in particular C 50 , C 60 , C 70 and related fullerenes as well as coaxial helical microtubules of graphite, are obtained analytically within the mean-field approximation. These energy spectra are then used to calculate various response functions. Specifically, we calculate the specific heat, magnetization and magnetic susceptibility in the presence of an external magnetic field at low temperatures. For a single microtubule an extra peak superimposed on the first de Haas van Alphen (dHvA) oscillation in magnetic susceptibility is found in the 50--170 Tesla range depending on the radius which is possibly accessible in special (explosive flux compression) experiments. Finally, we point to important potential applications of these novel mesoscopic structures in nanotechnology

  20. Behaviors of the percentage depth dose curves along the beam axis of a phantom filled with different clinical PTO objects, a Monte Carlo Geant4 study

    International Nuclear Information System (INIS)

    EL Bakkali, Jaafar; EL Bardouni, Tarek; Safavi, Seyedmostafa; Mohammed, Maged; Saeed, Mroan

    2016-01-01

    The aim of this work is to assess the capabilities of Monte Carlo Geant4 code to reproduce the real percentage depth dose (PDD) curves generated in phantoms which mimic three important clinical treatment situations that include lung slab, bone slab, bone-lung slab geometries. It is hoped that this work will lead us to a better understanding of dose distributions in an inhomogeneous medium, and to identify any limitations of dose calculation algorithm implemented in the Geant4 code. For this purpose, the PDD dosimetric functions associated to the three clinical situations described above, were compared to one produced in a homogeneous water phantom. Our results show, firstly, that the Geant4 simulation shows potential mistakes on the shape of the calculated PDD curve of the first physical test object (PTO), and it is obviously not able to successfully predict dose values in regions near to the boundaries between two different materials. This is, surely due to the electron transport algorithm and it is well-known as the artifacts at interface phenomenon. To deal with this issue, we have added and optimized the StepMax parameter to the dose calculation program; consequently the artifacts due to the electron transport were quasi disappeared. However, the Geant4 simulation becomes painfully slow when we attempt to completely resolve the electron artifact problems by considering a smaller value of an electron StepMax parameter. After electron transport optimization, our results demonstrate the medium-level capabilities of the Geant4 code to modeling dose distribution in clinical PTO objects. - Highlights: • Assessment of the capabilities of Geant4 code to reproduce the PDD curves in heterogeneities. • Resolving artifacts due to the electron transport. • Understanding in dose distribution differences in interfaces which include water, bone, and lung interfaces.